zigbee networks full report
Thread Rating:
  • 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5
project reporter
Active In SP
**

Posts: 45
Joined: Jan 2010
#1
01-02-2010, 04:19 PM



.doc   ZigBee Networks.doc (Size: 2.76 MB / Downloads: 701)



ABSTRACT
Wireless connectivity of a vast number of industrial and home applications has modest transmission data requirements, but demands reliable and secure communication using simple low-cost and low-power radio systems. In the quest for high-bandwidth, multimedia-capable wireless networks, the need for cost and power-effective radio solutions for this vast number of fairly simple applications was only recently addressed by a standardized technology.
The IEEE 802.15.4 standard and ZigBee wireless technology are designed to satisfy the market's need for a low-cost, standard-based and flexible wireless network technology, which offers low power consumption, reliability, interoperability and security for control and monitoring applications with low to moderate data rates.
The complexity and cost of the IEEE802.15.4/Zigbee-compliant devices are intended to be low and scalable (application dependent) in order to enable broad commercial adaptation in cost-sensitive applications. In addition, the compliant system implementations will enable long battery life by using the power-saving features at the physical, MAC and network layers specified by this standard.
In this respect, the implementation of the physical layer of the IEEE 802.15.4 standard, including the RF, IF and de-modulation must be optimized to meet the challenging low-cost and low-power targets.
CHAPTER 1
INTRODUCTION
INTRODUCTION 1
1.1 Evolution of LR-WPAN Standardization
The cellular network was a natural extension of the wired telephony network that became pervasive during the mid-20th century. As the need for mobility and the cost of laying new wires increased, the motivation for a personal connection independent of location to that network also increased. Coverage of large area is provided through (1-2km) cells that cooperate with their neighbors to create a seemingly seamless network. Examples of standards are GSM, IS-136, IS-95. Cellular standards basically aimed at facilitating voice communications throughout a metropolitan area.
During the mid-1980s, it turned out that an even smaller coverage area is needed for higher user densities and the emergent data traffic. The IEEE 802.11 working group for WLANs is formed to create a wireless local area network standard.
Whereas IEEE 802.11 was concerned with features such as Ethernet matching speed, long-range(100m), complexity to handle seamless roaming, message forwarding, and data throughput of 2-11Mbps, WPANs are focused on a space around a person or object that typically extends up to 10m in all directions. The focus of WPANs is low-cost, low power, short range and very small size. The IEEE802.15 working group is formed to create WPAN standard. This group has currently defined three classes of WPANs that are differentiated by data rate, battery drain and quality of service (QoS). The high data rate WPAN (IEEE 802.15.3) is suitable for multi-media applications that require very high QoS. Medium rate WPANs (IEEE802.15.1/Blueetooth) will handle a variety of tasks ranging from cell phones to PDA communications and have QoS suitable for voice communications. The low rate WPANs (IEEE 802.15.4/LR-WPAN) is intended to serve a set of industrial, residential and medical applications with very low power consumption and cost requirement not considered by the above WPANs and with relaxed needs for data rate and QoS. The low data rate enables the LR-WPAN to consume very little power.
1.2 ZigBee and IEEE 802.15.4
ZigBee technology is a low data rate, low power consumption, low cost; wireless networking protocol targeted towards automation and remote control applications. IEEE 802.15.4 committee started working on a low data rate standard a short while later. Then the ZigBee Alliance and the IEEE decided to join forces and ZigBee is the commercial name for this technology.
ZigBee is expected to provide low cost and low power connectivity for equipment that needs battery life as long as several months to several years but does not require data transfer rates as high as those enabled by Bluetooth. In addition, ZigBee can be implemented in mesh networks larger than is possible with Bluetooth. ZigBee compliant wireless devices are expected to transmit 10-75 meters, depending on the RF environment and the power output consumption required for a given application, and will operate in the unlicensed RF worldwide (2.4GHz global, 915MHz in USA OR 868MHz in Europe). The data rate is 250kbps at 2.4GHz, 40kbps at 915MHz and 20kbps at 868MHz.
IEEE and ZigBee Alliance have been working closely to specify the entire protocol stack. IEEE 802.15.4 focuses on the specification of the lower two layers o f the protocol (physical and data link layer). On the other hand, ZigBee Alliance aims to provide the upper layers of the protocol stack (from network to the application layer) for interoperable data networking, security services and a range of wireless home and building control solutions, provide interoperability compliance testing, marketing of the standard, advanced engineering for the evolution of the standard. This will assure consumers to buy products from different manufacturers with confidence that the products will work together.
IEEE 802.15.4 is now detailing the specification of PHY and MAC by offering building blocks for different types of networking known as star, mesh, and cluster tree. Network routing schemes are designed to ensure power conservation, and low latency through guaranteed time slots. A unique feature of ZigBee network layer is communication redundancy eliminating single point of failure in mesh networks. Key features of PHY include energy and link quality detection, clear channel assessment for improved coexistence with other wireless networks.

1.3 Why is ZigBee Needed
There are a multitude of standards like Bluetooth and WiFi that address mid to high data rates for voice, PC LANs, video, etc. However, up till now there hasn't been a wireless network standard that meets the unique needs of sensors and control devices. Sensors and controls don't need high bandwidth but they do need low latency and very low energy consumption for long battery lives and for large device arrays.
There are a multitude of proprietary wireless systems manufactured today to solve a multitude of problems that don't require high data rates but do require low cost and very low current drain. These proprietary systems were designed because there were no standards that met their application requirements. These legacy systems are creating significant interoperability problems with each other and with newer technologies.
ZigBee is poised to become the global control/sensor network standard. It has been designed to provide the following features:
Low power consumption, simply implemented
Users expect batteries to last many months to years! Consider that a typical single family house has about 6 smoke/CO detectors. If the batteries for each one only lasted six months, the home owner would be replacing batteries every month!
In contrast to Bluetooth, which has many different modes and states depending upon your latency and power requirements, ZigBee/IEEE 802.15.4 has two major states: active (transmit/receive) or sleep. The application software needs to focus on the application, not on which power mode is optimum for each aspect of operation.
Even mains powered equipment needs to be conscious of energy. ZigBee devices will be more ecological than their predecessors saving megawatts at it full deployment. Consider a future home that has 100 wireless control/sensor devices,
o Case 1: 802.11 Rx power is 667 mW (always on)@ 100
Devices/home & 50,000 homes/city = 3.33 megawatts
o Case 2: 802.15.4 Rx power is 30 mW (always on)@ 100
Devices/home & 50,000 homes/city = 150 kilowatts
o Case 3: 802.15.4 power cycled at .1% (typical duty cycle) = 150 watts
Low cost to the users means low device cost, low installation cost and low maintenance.
o ZigBee devices allow batteries to last up to years using primary cells
(low cost) without any chargers (low cost and easy installation). ZigBee's simplicity allows for inherent configuration and redundancy of network devices provides low maintenance.
High density of nodes per network
o ZigBee's use of the IEEE 802.15.4 PHY and MAC allows networks to handle any number of devices. This attribute is critical for massive sensor arrays and control networks.
Simple protocol, global implementation
o ZigBee's protocol code stack is estimated to be about 1/4th of Bluetooth's or 802.11's. Simplicity is essential to cost, interoperability, and maintenance. The IEEE 802.15.4 PHY adopted by ZigBee has been designed for the 868 MHz band in Europe, the 915 MHz band in N America, Australia, etc; and the 2.4 GHz band is now recognized to be a global band accepted in almost all countries.
1.4 ZigBee vs. Bluetooth
ZigBee looks rather like Bluetooth but is simpler, has a lower data rate and spends most of its time snoozing. This characteristic means that a node on a ZigBee network should be able to run for six months to two years on just two AA batteries.
The operational range of ZigBee is 10-75m compared to 10m for Bluetooth
(without a power amplifier).
ZigBee sits below Bluetooth in terms of data rate.
The data rate of ZigBee is
250kbps at 2.4GHz, 40kbps at 915MHz and 20kbps at 868MHz whereas that of Bluetooth is 1Mbps.
ZigBee uses a basic master-slave configuration suited to static star networks of many infrequently used devices that talk via small data packets. It allows up to 254 nodes. Bluetoothâ„¢s protocol is more complex since it is geared towards handling voice, images and file transfers in ad hoc networks. Bluetooth devices can support scatter nets of multiple smaller non-synchronized networks (piconets). It only allows up to 8 slave nodes in a basic master-slave piconet set-up.
When ZigBee node is powered down, it can wake up and get a packet in around 15msec whereas a Bluetooth device would take around 3sec to wake up and respond.
ZigBee and Bluetooth are two solutions for two different application areas. Bluetooth has addressed a voice application by embodying a fast frequency hopping system with a master slave protocol. ZigBee has addressed sensors, controls, and other short message applications by embodying a direct sequence system with a star or peer to peer protocols.
1.5 Wireless technology comparison chart
Wi-Fi Bluetooth WiMAX WiMedia ZigBee
Primary Use Laptop networking Cable replacement, cellphones Wireless broadband Internet access Multimedia consumer electronics Sensor networks, industrial control
LAN type WLAN WPAN WMAN WPAN WPAN
IEEE 802.11n 802.15.1 802.16 802.15.3 802.15.4
Standards Wi-Fi Alliance Bluetooth SIG WiMAX Forum WiMedia Alliance ZigBee Alliance
URL wi-fi.org bluetooth.org wimaxforum.org wimedia.org zigbee.org
Range(m) 100m 10-100m 50km 4-10m 30-70m
Bands 2.4 GHz 2.4 GHz 2.5 GHz, 3.5 GHz 3.1-10.6 GHz 2.4 GHz, 866/900 MHz
Data Speeds 11-54 Mbps 1 Mbps 280 Mbps 110-480 Mbps 20-250Kbps
BOM (US$) 9 6 150 20 3
Battery Life Hours Days N/A Days-weeks Months-years
ZigBee
CHAPTER 2
ZigBee / IEEE 802.15.4 WPLAN
2.0 ZigBee / IEEE 802.15.4 WPAN
The main features of this standard are network flexibility, low cost, very low power consumption, and low data rate in an adhoc self-organizing network among inexpensive fixed, portable and moving devices. It is developed for applications with relaxed throughput requirements which cannot handle the power consumption of heavy protocol stacks.
2.1 Components of WPAN
A ZigBee system consists of several components. The most basic is the device. A device can be a full-function device (FFD) or reduced-function device (RFD). A network shall include at least one FFD, operating as the PAN coordinator.
The FFD can operate in three modes: a personal area network (PAN) coordinator, a coordinator or a device. An RFD is intended for applications that are extremely simple and do not need to send large amounts of data. An FFD can talk to RFDs or FFDs while an RFD can only talk to an FFD.
2.2 Network Topologies
ZigBee supports 3 types of topologies - star topology, peer-to-peer topology and cluster tree topology.
2.2.1 Star Topology
In the star topology, the communication is established between devices and a single central controller, called the PAN coordinator. The PAN coordinator may be mains powered while the devices will most likely be battery powered. Applications that benefit from this topology include home automation, personal computer (PC) peripherals, toys and games.
After an FFD is activated for the first time, it may establish its own network and become the PAN coordinator. Each start network chooses a PAN identifier, which is not currently used by any other network within the radio sphere of influence. This allows each star network to operate independently.
2.2.2 Peer-to-peer Topology
In peer-to-peer topology, there is also one PAN coordinator. In contrast to star topology, any device can communicate with any other device as long as they
are in range of one another. A peer-to-peer network can be ad hoc, self-organizing and self-healing. Applications such as industrial control and monitoring, wireless sensor networks, asset and inventory tracking would benefit from such a topology. It also allows multiple hops to route messages from any device to any other device in the network. It can provide reliability by multi path routing.
2.2.3 Cluster-tree Topology
Cluster-tree network is a special case of a peer-to-peer network in which most devices are FFDs and an RFD may connect to a cluster-tree network as a leave node at the end of a branch. Any of the FFD can act as a coordinator and provide synchronization services to other devices and coordinators. Only one of these coordinators however is the PAN coordinator.
The PAN coordinator forms the first cluster by establishing itself as the cluster head
(CLH) with a cluster identifier (CID) of zero, choosing an unused PAN identifier, and broadcasting beacon frames to neighboring devices. A candidate device receiving a beacon frame may request to join the network at the CLH. If the PAN coordinator permits the device to join, it will add this new device as a child device in its neighbor list. The newly joined device will add the CLH as its parent in its neighbor list and begin transmitting periodic beacons such that other candidate devices may then join the network at that device. Once application or network requirements are met, the PAN coordinator may instruct a device to become the CLH of a new cluster adjacent to the first one. The advantage of this clustered structure is the increased coverage area at the cost of increased message latency.
2.3 ZigBee Architecture
ZigBee architecture comprises a PHY, which contains the radio frequency (RF) transceiver along with its low-level control mechanism, and a MAC sublayer that provides access to the physical channel for all types of transfer. The upper layers consists of a network layer, which provides network configuration, manipulation, and message routing, and application layer, which provides the intended function of a device. An IEEE 802.2 logical link control (LLC) can access the MAC sublayer through the service specific convergence sublayer (SSCS). Chapter 3 describes the physical layer of IEEE 802.15.4. Chapter 4 explains the MAC layer of IEEE 802.15.4. Chapter 6 gives the routing mechanisms that are going to be used in the ZigBee.
ZigBee
CHAPTER 3
PHYSICAL LAYER
PHYSICAL LAYER 3
3.0 IEEE 802.15.4 PHY
The PHY provides two services: the PHY data service and PHY management service interfacing to the physical layer management entity (PLME). The PHY data service enables the transmission and reception of PHY protocol data units (PPDU) across the physical radio channel.
The features of the PHY are activation and deactivation of the radio transceiver, energy detection (ED), link quality indication (LQI), channel selection, clear channel assessment (CCA) and transmitting as well as receiving packets across the physical medium.
The standard offers two PHY options based on the frequency band. Both are based on direct sequence spread spectrum (DSSS). The data rate is 250kbps at 2.4GHz, 40kbps at 915MHz and 20kbps at 868MHz. The higher data rate at 2.4GHz is attributed to a higher-order modulation scheme. Lower frequencies provide longer range due to lower propagation losses. Low rate can be translated into better sensitivity and larger coverage area. Higher rate means higher throughput, lower latency or lower duty cycle. This information is summarized in the table below.
There is a single channel between 868 and 868.6MHz, 10 channels between 902.0
and 928.0MHz, and 16 channels between 2.4 and 2.4835GHz as shown in
Figure 3.2.
Several channels in different frequency bands enables the ability to relocate within spectrum. The standard also allows dynamic channel selection, a scan function that steps through a list of supported channels in search of beacon, receiver energy detection, link quality indication, channel switching.
Receiver sensitivities are -85dBm for 2.4GHz and -92dBm for 868/915MHz. The advantage of 6-8dB comes from the advantage of lower rate. The achievable range is a function of receiver sensitivity and transmits power.
The maximum transmit power shall conform with local regulations. A compliant device shall have its nominal transmit power level indicated by the PHY parameter, phyTransmitPower.
Figure 3.2: Operating frequency bands.
3.1 Receiver Energy Detection (ED)
The receiver energy detection (ED) measurement is intended for use by a network layer as part of channel selection algorithm. It is an estimate of the received signal power within the bandwidth of an IEEE 802.15.4 channel. No attempt is made to identify or decode signals on the channel. The ED time should be equal to 8 symbol periods.
The ED result shall be reported as an 8-bit integer ranging from 0x00 to 0xff. The minimum ED value (0) shall indicate received power less than 10dB above the specified receiver sensitivity. The range of received power spanned by the ED values shall be at least 40dB. Within this range, the mapping from the received power in decibels to ED values shall be linear with an accuracy of + - 6dB.
3.2 Link Quality Indication (LQI)
Upon reception of a packet, the PHY sends the PSDU length, PSDU itself and link quality (LQ) in the PD-DATA. indication primitive. The LQI measurement is a characterization of the strength and/or quality of a received packet. The measurement may be implemented using receiver ED, a signal-to-noise estimation or a combination of these methods. The use of LQI result is up to the network or application layers.
The LQI result should be reported as an integer ranging from 0x00 to 0xff. The minimum and maximum LQI values should be associated with the lowest and highest quality IEEE 802.15.4 signals detectable by the receiver and LQ values should be uniformly distributed between these two limits.
3.3 Clear Channel Assessment (CCA)
The clear channel assessment (CCA) is performed according to at least one of the following three methods:
¢ Energy above threshold. CCA shall report a busy medium upon detecting any energy above the ED threshold.
¢ Carrier sense only. CCA shall report a busy medium only upon the detection of a signal with the modulation and spreading characteristics of IEEE 802.15.4. This signal may be above or below the ED threshold.
¢ Carrier sense with energy above threshold. CCA shall report a busy medium only upon the detection of a signal with the modulation and spreading characteristics of IEEE 802.15.4 with energy above the ED threshold.
3.4 PPDU Format
The PPDU packet structure is illustrated in Figure 3.3. Each PPDU packet consists of the following basic components:
¢ SHR, which allows a receiving device to synchronize and lock into the bit stream
¢ PHR, which contains frame length information
¢ A variable length payload, which carries the MAC sub layer frame.
Figure 3.3: Format of the PPDU.
ZigBee
CHAPTER 4
MEDIA ACCESS CONTROL LAYER
MAC LAYER 4
4.0 IEEE 802.15.4 MAC
The MAC (Media access control) layer sub layer provides two services: the MAC data service and the MAC management service interfacing to the MAC sub layer management entity (MLME) service access point (SAP) (MLMESAP). The MAC data service enables the transmission and reception of MAC protocol data units
(MPDU) across the PHY data service.
The features of MAC sub layer are beacon management, channel access, GTS management, frame validation, acknowledged frame delivery, association and disassociation.
4.1 Frame Structure
The frame structures have been designed to keep the complexity to a minimum while at the same time making them sufficiently robust for transmission on a noisy channel. Each successive protocol layer adds to the structure with layer-specific headers and footers.
The IEEE 802.15.4 MAC defines four frame structures
¢ A beacon frame, used by a coordinator to transmit beacons.
¢ A data frame, used for all transfers of data.
¢ An acknowledgment frame, used for confirming successful frame reception.
¢ A MAC command frame, used for handling all MAC peer entity control transfers.
The data frame is illustrated below:
The Physical Protocol Data Unit is the total information sent over the air. As shown in the illustration above the Physical layer adds the following overhead:
Preamble Sequence 4 Octets Start of Frame Delimiter 1 Octet Frame Length 1 Octet
The MAC adds the following overhead:
Frame Control 2 Octets Data Sequence Number 1 Octet Address Information 4 “ 20 Octets Frame Check Sequence 2 Octets
In summary the total overhead for a single packet is therefore 15 -31 octets (120 bits); depending upon the addressing scheme used (short or 64 bit addresses). Please note that these numbers do not include any security overhead.
4.2 Channel access and Addressing
Two channel-access mechanisms are implemented in 802.15.4. For a non-beacon network, a standard ALOHA CSMA-CA (carrier-sense medium-access with collision avoidance) communicates with positive acknowledgement for successfully received packets. In a beacon-enabled network, a superframe structure is used to control channel access. The superframe is set up by the network coordinator to transmit beacons at predetermined intervals (multiples of 15.38ms, up to 252s) and provides
16 equal-width time slots between beacons for contention-free channel access in each time slot. The structure guarantees dedicated bandwidth and low latency. Channel access in each time slot is contention-based. However, the network coordinator can dedicate up to seven guaranteed time slots per beacon interval for quality of service.
Device addresses employ 64-bit IEEE and optional 16-bit short addressing. The address field within the MAC can contain both source and destination address information (needed for peer-to-peer operation). This dual address information is used in mesh networks to prevent a single point of failure within the network.
4.3 Super Frame Structure
The LR-WPAN standard allows the optional use of a superframe structure. The format of the superframe is defined by the coordinator. The superframe is bounded by network beacons, is sent by the coordinator (See Figure 4) and is divided into 16 equally sized slots. The beacon frame is transmitted in the first slot of each superframe. If a coordinator does not wish to use a superframe structure it may turn off the beacon transmissions. The beacons are used to synchronize the attached devices, to identify the PAN, and to describe the structure of the superframes. Any device wishing to communicate during the contention access period (CAP) between two beacons shall compete with other devices using a slotted CSMA-CA mechanism. All transactions shall be completed by the time of the next network beacon.
Figure 4.1
For low latency applications or applications requiring specific data bandwidth, the PAN coordinator may dedicate portions of the active superframe to that application. These portions are called guaranteed time slots (GTSs). The guaranteed time slots comprise the contention free period (CFP), which always appears at the end of the active superframe starting at a slot boundary immediately following the CAP, as shown in Figure 5. The PAN coordinator may allocate up to seven of these GTSs and a GTS may occupy more than one slot period. However, a sufficient portion of the CAP shall remain for contention based access of other networked devices or new devices wishing to join the network. All contention based transactions shall be complete before the CFP begins. Also each device transmitting in a GTS shall ensure that its transaction is complete before the time of the next GTS or the end of the CFP.
Figure 4.2
4.4 CSMA-CA Algorithm
If superframe structure is used in the PAN, then slotted CSMA-CA shall be used. If beacons are not being used in the PAN or a beacon cannot be located in a beacon- enabled network, unslotted CSMA-CA algorithm is used. In both cases, the algorithm is implemented using units of time called backoff periods, which is equal to aUnitBackoffPeriod symbols.
In slotted CSMA-CA channel access mechanism, the backoff period boundaries of every device in the PAN are aligned with the superframe slot boundaries of the PAN coordinator. In slotted CSMA-CA, each time a device wishes to transmit data frames during the CAP, it shall locate the boundary of the next backoff period. In unslotted CSMA-CA, the backoff periods of one device do not need to be synchronized to the backoff periods of another device.
Each device has 3 variables: NB, CW and BE. NB is the number of times the CSMA-CA algorithm was required to backoff while attempting the current transmission. It is initialized to 0 before every new transmission. CW is the contention window length, which defines the number of backoff periods that need to be clear of activity before the transmission can start. It is initialized to 2 before each transmission attempt and reset to 2 each time the channel is assessed to be busy. CW is only used for slotted CSMA-CA. BE is the backoff exponent, which is related to how many backoff periods a device shall wait before attempting to assess the channel. Although the receiver of the device is enabled during the channel assessment portion of this algorithm, the device shall discard any frames received during this time.
In slotted CSMA-CA, NB, CW and BE are initialized and the boundary of the next backoff period is located. In unslotted CSMA-CA, NB and BE are initialized (step1). The MAC layer shall delay for a random number of complete backoff periods in the range 0 to 2BE - 1 (step 2) then request that PHY performs a CCA (clear channel assessment) (step 3). The MAC sublayer shall then proceed if the remaining CSMA-CA algorithm steps, the frame transmission, and any acknowledgement can be completed before the end of the CAP. If the MAC sublayer cannot proceed, it shall wait until the start of the CAP in the next
superframe and repeat the evaluation.
If the channel is assessed to be busy (step 4), the MAC sublayer shall increment both NB and BE by one, ensuring that BE shall be no more than aMaxBE. In slotted CSMA-CA, CWcan also be reset to 2. If the value of NB is less than or equal to macMaxCSMABackoffs, the CSMA-CA shall return to step 2, else the CSMA-CA shall terminate with a Channel Access Failure status.
If the channel is assessed to be idle (step 5), in a slotted CSMA-CA, the MAC sublayer shall ensure that contention window is expired before starting transmission. For this, the MAC sublayer first decrements CW by one. If CW is not equal to 0, go to step 3 else start transmission on the boundary of the next backoff period. In the unslotted CSMA-CA, the MAC sublayer start transmission immediately if the channel is assessed to be idle.
4.5 Data Transfer model
Three types of data transfer transactions exist: from a coordinator to a device, from a device to a coordinator and between two peer devices. The mechanism for each of these transfers depend on whether the network supports the transmission of beacons. When a device wishes to transfer data in a nonbeacon-enabled network, it simply transmits its data frame, using the unslotted CSMA-CA, to the coordinator. There is also an optional acknowledgement at the end as shown in Figure 4.3.
Figure 4.3: Communication to a coordinator in a beacon-enabled network.
When a device wishes to transfer data to a coordinator in a beacon-enabled network, it first listens for the network beacon. When the beacon is found, it synchronizes to the superframe structure. At the right time, it transmits its data frame, using slotted CSMA-CA, to the coordinator. There is an optional acknowledgement at the end as shown in Figure 4.4.
Figure 4.4: Communication to a coordinator in a non beacon-enabled network.
The applications transfers are completely controlled by the devices on a PAN rather than by the coordinator. This provides the energy-conservation feature of the ZigBee network. When a coordinator wishes to transfer data to a device in a beacon-enabled network, it indicates in the network beacon that the data message is pending. The device periodically listens to the network beacon, and if a message is pending, transmits a MAC command requesting this data, using slotted CSMA- CA. The coordinator optionally acknowledges the successful transmission of this packet. The pending data frame is then sent using slotted CSMA-CA. The device acknowledged the successful reception of the data by transmitting an acknowledgement frame. Upon receiving the acknowledgement, the message is removed from the list of pending messages in the beacon as shown in Figure 4.5.
Figure 4.5: Communication from a coordinator in a beacon-enabled network.
When a coordinator wishes to transfer data to a device in a nonbeacon-enabled network, it stores the data for the appropriate device to make contact and request data. A device may make contact by transmitting a MAC command requesting the data, using unslotted CSMA-CA, to its coordinator at an application-defined rate. The coordinator acknowledges this packet. If data are pending, the coordinator transmits the data frame using unslotted CSMA-CA. If data are not pending, the coordinator transmits a data frame with a zero-length payload to indicate that no data were pending. The device acknowledges this packet as shown in Figure 4.6.
Figure 4.6: Communication from a coordinator in a non beacon-enabled network.
In a peer-to-peer network, every device can communicate with any other device in its transmission radius. There are two options for this. In the first case, the node will listen constantly and transmit its data using unslotted CSMA-CA. In the second case, the nodes synchronize with each other so that they can save power
4.6 MAC Layer Security
When security of MAC layer frames is desired, ZigBee uses MAC layer security to secure MAC command, beacon, and acknowledgement frames. ZigBee may secure messages transmitted over a single hop using secured MAC data frames, but for multi-hop messaging ZigBee relies upon upper layers (such as the NWK layer) for security. The MAC layer uses the Advanced Encryption Standard (AES) as its core cryptographic algorithm and describes a variety of security suites that use the AES algorithm. These suites can protect the confidentiality, integrity, and authenticity of MAC frames. The MAC layer does the security processing, but the upper layers, which set up the keys and determine the security levels to use, control this processing. When the MAC
layer transmits (receives) a frame with security enabled, it looks at the destination (source) of the frame, retrieves the key associated with that destination (source), and then uses this key to process the frame according to the security suite designated for the key being used. Each key is associated with a single security suite and the MAC frame header has a bit that specifies whether security for a frame is enabled or disabled.
When transmitting a frame, if integrity is required, the MAC header and payload data are used in calculations to create a Message Integrity Code (MIC) consisting of 4, 8, or 16 octets. The MIC is right appended to the MAC payload. If confidentiality is required, the MAC frame payload is also left appended with frame and sequence counts (data used to form a nonce). The nonce is used when encrypting the payload and also ensures freshness to prevent replay attacks. Upon receipt of a frame, if a MIC is present, it is verified and if the payload is encrypted, it is decrypted. Sending devices will increase the frame count with every message sent and receiving devices will keep track of the last received count from each sending device. If a message with an old count is detected, it is flagged with a security error. The MAC layer security suites are based on three modes of operation. Encryption at the MAC layer is done using AES in Counter (CTR) mode and integrity is done using AES in Cipher Block Chaining (CBC- MAC) mode [16]. A combination of encryption and integrity is done using a mixture of CTR and CBC- MAC modes called the CCM mode.
ZigBee
CHAPTER 5
NETWORK LAYER
NETWORK LAYER 5
5.0 NWK LAYER
The NWK layer associates or dissociates devices using the network coordinator, implements security, and routes frames to their intended destination. In addition, the NWK layer of the network coordinator is responsible for starting a new network and assigning an address to newly associated devices.
The NWK layer supports multiple network topologies including star, cluster tree, and mesh, all of which are shown in Figure 5.1
Figure 5.1: Network topologies
In a star topology, one of the FFD-type devices assumes the role of network coordinator and is responsible for initiating and maintaining the devices on the network. All other devices, known as end devices, directly communicate with the coordinator.
In a mesh topology, the ZigBee coordinator is responsible for starting the network and for choosing key network parameters, but the network may be extended through the use of ZigBee routers. The routing algorithm uses a request-response protocol to eliminate sub-optimal routing. Ultimate network size can reach 264 nodes (more than we'll probably need). Using local
addressing, you can configure simple networks of more than 65,000 (216) nodes, thereby reducing address overhead.
5.1 ZigBee Network Node
¢ Designed for battery powered or high energy savings
¢ Searches for available networks
¢ Transfers data from its application as necessary
¢ Determines whether data is pending
¢ Requests data from the network coordinator
¢ Can sleep for extended periods
5.2 Responsibilities of the ZigBee NWK layer
¢ Starting a network : The ability to successfully establish a new network.
¢ Joining and leaving a network: The ability to gain membership (join) or relinquish membership (leave) a network.
¢ Configuring a new device: The ability to sufficiently configure the stack for operation as required.
¢ Addressing: The ability of a ZigBee coordinator to assign addresses to devices joining the network.
¢ Synchronization within a network: The ability for a device to achieve synchronization with another device either through tracking beacons or by polling.
¢ Security: applying security to outgoing frames and removing security to terminating frames
¢ Routing: routing frames to their intended destinations.
The network layer builds upon the IEEE 802.15.4 MACâ„¢s features to allow extensibility of coverage. Additional clusters can be added; networks can be consolidated or split up.
5.3 Network Layer Security
The NWK layer also makes use of the Advanced Encryption Standard (AES). However, unlike the MAC layer, the security suites are all based on the CCM mode of operation. The CCM mode of operation is a minor modification of the CCM mode used by the MAC layer. It includes all of the capabilities of CCM and additionally offers encryption-only and integrity-only capabilities. These extra capabilities simplify the NWK layer security by eliminating the need for CTR and CBC-MAC modes. Also, the use of CCM in all security suites allows a single key to be used for different suites. Since a key is not strictly bound to a single security suite, an application has the flexibility to specify the actual security suite to apply to each NWK frame, not just whether security is enabled or disabled
When the NWK layer transmits (receives) a frame using a particular security suite it uses the Security Services Provider (SSP) to process the frame. The SSP looks at the destination (source) of the frame, retrieves the key associated with that destination (source), and then applies the security suite to the frame. The SSP provides the NWK layer with a primitive to apply security to outgoing frames and a primitive to verify and remove security from incoming frames. The NWK layer is responsible for the security processing, but the upper layers control the processing by setting up the keys and determining which CCM security suite to use for each frame. Similar to the MAC layer frame format, a frame sequence count and MIC may be added to secure a NWK frame.
ZigBee
CHAPTER 6
ZigBee ROUTING MECHANISMS
ZigBee ROUTING MECHANISMS 6
6.0 ZigBee routing algorithm
ZigBee routing algorithm can be thought of a hierarchical routing strategy with table-driven optimizations applied where possible. The routing layer is said to start with the well-studied public domain algorithm Ad hoc On Demand Distance Vector (AODV) and Motorolaâ„¢s Cluster-Tree algorithm.
6.1 AODV: Ad hoc On Demand Distance Vector
AODV is a pure on-demand route acquisition algorithm: nodes that do not lie on active paths neither maintain any routing information nor participate in any periodic routing table exchanges. Further, a node does not have to discover and maintain a route to another node until the two need to communicate, unless the former node is offering services as an intermediate forwarding station to maintain connectivity between two other nodes.
The primary objectives of the algorithm are to broadcast discovery packets only when necessary, to distinguish between local connectivity management and general topology maintenance and to disseminate information about changes in local connectivity to those neighboring mobile nodes that are likely to need the information.
When a source node needs to communicate with another node for which it has no routing information in its table, the Path Discovery process is initiated. Every node maintains two separate counters: sequence number and broadcast id. The source node initiates path discovery by broadcasting a route request (RREQ) packet to its neighbors, which includes source address, source sequence number, broadcast id, destination address, destination sequence number, hop cnt. (Source sequence number is for maintaining freshness information about the reverse route whereas the destination sequence number is for maintaining freshness of the route to the destination before it can be accepted by the source.)
The pair source address, broadcast id uniquely identifies a RREQ, where broadcast id is incremented whenever the source issues a new RREQ. When an intermediate node receives a RREQ, if it has already received a RREQ with the same broadcast id and source address, it drops the redundant RREQ and does not rebroadcast it.
Otherwise, it rebroadcasts it to its own neighbors after increasing hop cnt. Each node keeps the following information: destination IP address, source IP address, broadcast id, expiration time for reverse path route entry and source nodeâ„¢s sequence number.
As the RREQ travels from a source to destinations, it automatically sets up the reverse path from all nodes back to the source. To set up a reverse path, a node records the address of the neighbor from which it received the first copy of RREQ. These reverse path route entries are maintained for at least enough time for the RREQ to traverse the network and produce a reply to the sender.
Figure 6.1: Reverse and forward path formation in AODV protocol.
When the RREQ arrives at a node, possibly the destination itself, that possesses a current route to the destination, the receiving node first checks that the RREQ was received over a bi-directional link. If this node is not destination but has route to the destination, it determines whether the route is current by comparing the destination sequence number in its own route entry to the destination sequence number in the RREQ. If RREQâ„¢s sequence number for the destination is greater than that recorded by the intermediate node, the intermediate node must not use this route to respond to the RREQ, instead rebroadcasts the RREQ. If the route has a destination sequence number that is greater than that contained in the RREQ or equal to that contained in the RREQ but a smaller hop count, it can
unicasts a route reply packet (RREP) back to its neighbor from which it received
the RREQ. A RREP contains the following information: source address, dest addr, dest sequence number, hop cnt and lifetime. As the RREP travels back to the source, each node along the path sets up a forward pointer to the node from which the RREP came, updates its timeout information for route entries to the source and destination, and records the latest destination sequence number for the requested destination.
Nodes that are along the path determined by the RREP will timeout after route request expiration timer and will delete the reverse pointers since they are not on the path from source to destination as shown in Figure 6.1. The value of this timeout time depends on the size of the ad hoc network. Also, there is the routing caching timeout that is associated with each routing entry to show the time after which the route is considered to be invalid. Each time a route entry is used to transmit data from a source toward a destination, the timeout for the entry is reset to the current time plus active-route-timeout.
The source node can begin data transmission as soon as the first RREP is received, and can later update its routing information if it learns of a better route.
Each routing table entry includes the following fields: destination, next hop, number of hops (metric), sequence number for the destination, active neighbors for this route, and expiration time for the route table entry.
For path maintenance, each node keeps the address of active neighbors through which packets for the given destination are received is maintained. This neighbor is considered active if it originates or relays at least one packet for that destination within the last active-timeout period. Once the next hop on the path from source to the destination becomes unreachable (hello messages are not received for a certain time, hello messages also ensures that only nodes with bidirectional connectivity are considered to be neighbors, therefore each hello message included the nodes from which the node has heard), the node upstream of the break propagates an unsolicited RREP with a fresh sequence number and hop count of 1to all active upstream nodes. This process continues until all active source nodes are notified. Upon receiving the notification of a broken link, the source nodes can restart the discovery process if they still require a route to the destination. If it decides that it would like to rebuild the route to the destination, it sends out an RREQ with a destination
sequence number of one greater than the previously known sequence number, to ensure that it builds a new, viable route and that no nodes reply if
they still regard the previous route as valid.
6.2 Cluster-Tree Algorithm
The cluster-tree protocol is a protocol of the logical link and network layers that uses link-state packets to form either a single cluster network or a potentially larger cluster tree network. The network is basically self-organized and supports network redundancy to attain a degree of fault resistance and self-repair.
Nodes select a cluster head and form a cluster according to the self-organized manner. Then self-developed clusters connect to each other using the Designated Device (DD).
6.2.1 Single Cluster Network
The cluster formation process begins with cluster head selection. After a cluster head is selected, the cluster head expands links with other member nodes to form a cluster.
After a node turns on, it scans the channels to search for a HELLO message form other nodes (HELLO messages correspond to beacons in MAC layer of IEEE
802.15.4). If it canâ„¢t get any HELLO messages for a certain time, then it turns to a cluster head as shown in Figure 6.2 and sends out HELLO messages to its neighbours. The new cluster head wait for responses from neighbours for a while. If it hasnâ„¢t received any connection requests, it turns back to a regular node and listens again. The cluster head can also be selected based on stored parameters of each node, like transmission range, power capacity, computing ability or location information.
Figure 6.2: Cluster head selection process.
After becoming the cluster head (CH), the node broadcasts a periodic HELLO message that contains a part of the cluster head MAC address and node ID 0 that indicates the cluster head. The nodes that receive this message send a CONNECTION REQUEST message to the cluster head. When the CH receives it, it responds to the node with a CONNECTION RESPONSE message that contains a node ID for the node (node ID corresponds to the short address at the MAC layer). The node that is assigned a node ID replies with an ACK message to the cluster head. The message exchange is shown in Figure 6.3.
Figure 6.3: Link setup between CH and member node.
If all nodes are located in the range of the cluster head, the topology of connection becomes a star and every member nodes are connected to the cluster head with one hop. A cluster can expand into a multi-hop structure when each node supports multiple connections. The message exchange for the multi hop cluster set up procedure is shown in Figure 6.4.
Figure 6.4: Multi hop cluster setup procedure.
If the cluster head has run out of all node IDs or the cluster has reached some other defined limit, it should reject connection requests from new nodes. The rejection is through the assignment of a special ID to the node.
The entry of the neighbour list and the routes is updated by the periodic HELLO message. If a node entry does not update until a certain timeout limit, it should be eliminated.
A node may receive a HELLO message from a node that belongs to different cluster. In that case, the node adds the cluster ID (CID) of the transmitting node in the neighbour list and then sends it inside a LINK STATE REPORT to the CH so that CH knows which clusters its cluster has intersection.
The LINK STATE REPORT message also contain the neighbors node ID list of the node so that the CH knows the complete topology to make topology optimizations. If the topology change is required, then the CH sends a TOPOLOGY UPDATE message. If a member receives a TOPOLOGY UPDATE message that the different parent node is linked to the node, it changes the parent node as indicated in the message. And it also records its child nodes and the nodes below it in the tree at this time.
If a member node has trouble and becomes unable to communicate, the tree route of the cluster would be reconfigured. The CH knows the presence of a trouble by the periodic LINK STATE REPORT. When the cluster head has trouble, the distribution of HELLO message is stopped and all member nodes know that they have lost the CH. The cluster would then be reconfigured in the same way as the cluster formation process.
6.2.2 Multi-Cluster Network
To form a network, a Designated Device (DD) is needed. The DD has responsibility to assign a unique cluster ID to each cluster head. This cluster ID combined with the node ID that the CH assigns to each node within a cluster forms a logical address and is used to route packets. Another role of the DD is to calculate the shortest route from the cluster to the DD and inform it to all nodes within the network.
When the DD joins the network, it acts as the CH of cluster 0 and starts to send HELLO message to the neighborhood. If a CH has received this message, it sends a CONNECTION REQUEST message and joins the cluster 0. After that, the CH requests a CID to the DD. In this case, the CH is a border node that has two logical addresses. One is for a member of the cluster 0 and the other is for a CH. When the CH gets a new CID, it informs its member nodes by the HELLO message.
If a member has received the HELLO message from the DD, it adds CID 0 in its neighbor list and reports to its CH. The reported CH selects the member node as a border node to its parent cluster and sends a network connection request message to the member node to set up a connection with the DD. The border node requests a connection and joins the cluster 0 as its member node. Then it sends a CID REQUEST message to the DD. After the CID RESPONSE message arrival, the border node sends NETWORK CONNECTION RESPONSE message that contains a new CID to the CH when the CH gets a new CID, it informs to its member nodes by the HELLO message.
The clusters not bordering cluster 0 use intermediate clusters to get a CID. Again, either the CH becomes the border node to its parent cluster or the CH names a member node as the border to its parent cluster. These processes are shown in Figures 6.5,6.6,6.7,6.8.
Figure 6.5: CID assignment 1
Figure 6.6: CID assignment 2.
Figure 6.7: CID assignment 3.
Figure 6.8: CID assignment 4.
Each member node of the cluster has to record its parent cluster, child/lower clusters and the border node IDs associated with both the parent and child clusters. The DD should store the whole tree structure of the clusters.
Like the nodes in the clusters, the CHs report their link state information to the DD. The CH periodically sends a NETWORK LINK STATE REPORT message that contains its neighbor cluster CID list to the DD. Then this information can be used to calculate the optimized route and periodically update the topology for the network redundancy. In the same way, the DD can send TOPOLOGY UPDATE message to inform up-to-date route from the DD to the clusters.
A backup DD (BDD) can be prepared to prevent network down time due to the DD trouble. Inter-cluster communication, which is shown in Figure 6.9, is realized by routing. The border nodes act as routers that connect clusters and relay packets between the clusters. When a border node receives a packet, it examines the destination address, then forwards to the next border node in the adjacent cluster or to the destination node within the cluster.
Figure 6.9: A multi cluster network and the border nodes.
Only the DD can send a message to all the nodes within its network. The message is forwarded along the tree route of clusters. The border node should forward the broadcast packet from the parent cluster to the child cluster.
ZigBee
CHAPTER 7
APPLICATION LAYER
APPLICATION LAYER 7
7.0 APPLICATION LAYER
The ZigBee application layer consists of the APS sub-layer, the ZDO and the manufacturer-defined application objects. The responsibilities of the APS sub-layer include maintaining tables for binding, which is the ability to match two devices together based on their services and their needs, and forwarding messages between bound devices. Another responsibility of the APS sub-layer is discovery, which is the ability to determine which other devices are operating in the personal operating space of a device. The responsibilities of the ZDO include defining the role of the device within the network (e.g., ZigBee coordinator or end device), initiating and/or responding to binding requests and establishing a secure relationship between network devices. The manufacturer-defined application objects implement the actual applications according to the ZigBee-defined application descriptions

7.1 Application Support Layer
This layer provides the following services:
¢ Discovery: The ability to determine which other devices are operating in the personal operating space of a device.
¢ Binding: The ability to match two or more devices together based on their services and their needs and forwarding messages between bound devices
7.2 The General Operation Framework (GOF)
The General Operation Framework (GOF) is a glue layer between applications and rest of the protocol stack. The GOF currently covers various elements that are common for all devices. It includes sub addressing and addressing modes and device descriptions, such as type of device, power source, sleep modes, and coordinators. Using an object model, the GOF specifies methods, events, and data formats that are used by application profiles to construct set/get commands and their responses.
Actual application profiles are defined in the individual profiles of the IEEE's working groups. Each ZigBee device can support up to 30 different profiles.
Currently, only one profile, Commercial and Residential Lighting, is defined. It includes switching anddimming load controllers, corresponding remote-control devices, and occupancy and light sensors.
7.3 ZigBee Device
There are two physical device types for the lowest system cost. The IEEE standard defines two types of devices:
¢ Full function device (FFD)
o Can function in any topology
o Capable of being the network coordinator
o Capable of being a coordinator
o Can talk to any other device
¢ Reduced function device (RFD)
o Limited to star topology
o Cannot become a network coordinator
o Talks only to a network coordinator
o Very simple implementation
An IEEE 802.15.4/ZigBee network requires at least one full function device as a network coordinator, but endpoint devices may be reduced functionality devices to reduce system cost.
¢ All devices must have 64 bit IEEE addresses
¢ Short (16 bit) addresses can be allocated to reduce packet size
¢ Addressing modes:
o Network + device identifier (star)
o Source/destination identifier (peer-peer)
7.4 ZigBee Device Objects
¢ Defines the role of the device within the network (e.g., ZigBee coordinator or end device)
¢ Initiates and/or responds to binding requests
¢ Establishes a secure relationship between network devices selecting one of
ZigBeeâ„¢s security methods such as public key, symmetric key, etc.
ZigBee
CHAPTER 8
ZigBee -APPLICATIONS
ZigBee - APPLICATIONS 8
8.1 Product Examples
Warehouses, Fleet management, Factory, Supermarkets, Office complexes
¢ Gas/Water/Electric meter, HVAC
¢ Smoke, CO, H2O detector
¢ Refrigeration case or appliance
¢ Equipment management services & PM
¢ Security services
¢ Lighting control
¢ Assembly line and work flow, Inventory
¢ Materials processing systems (heat, gas flow, cooling, chemical)
Energy, diagnostics, e-Business services
¢ Gateway or Field Service links to sensors & equipment
“ Monitored to suggest PM, product updates, status changes
¢ Nodes link to PC for database storage
“ PC Modem calls retailer, Service Provider, or Corp headquarters
“ Corp headquarters remotely monitors assets, billing, energy management
8.2 Home & Diagnostics Examples
¢ Mobile clients link to PC for database storage
“ PC links to peripherals, interactive toys
“ PC Modem calls retailer, SOHO, Service Provider
¢ Gateway links to security system, temperature sensor, AC system, entertainment, health.
¢ Gateway links to field sales/service
ZigBee
ZigBee
CONCLUSION
CONCLUSION 9
IEEE 802.15.4 is a new standard that still needs to pass through the circles of rigorous technology critics and establish its own place in the industry. Predictions for the future of ZigBee-enabled devices are a popular topic for numerous market- research firms.
While I intend to stay objective, I believe, based on protocol features implemented in 802.15.4, that ZigBee has a bright future. Backed by IEEE, ZigBee has the potential to unify methods of data communication for sensors, actuators, appliances, and asset-tracking devices. It offers a means to build a reliable but affordable network backbone that takes advantage of battery-operated devices with a low data rate and a low duty cycle. ZigBee can be used in many applications, from industrial automation, utility metering, and building control to even toys. Home automation, however, is the biggest market for ZigBee-enabled devices. This follows from the number of remote controlled devices (or devices that may be connected wirelessly) in the average household. This cost-effective and easy-to- use home network potentially creates a whole new ecosystem of interconnected home appliances, light and climate control systems, and security and sensor sub networks.
ZigBee
ZigBee
BIBILOGRAPHY
BIBLIOGRAPHY
On the web
ZigBee Alliance, cabastandard/zigbee.html.
ZigBee Alliance, zigbee.org
IEEE 802.15.4 web site, ieee80215/pub/TG4.html
wireless.weblogsincentry/1234000283039483/
On the press
LAN-MAN Standards Committee of the IEEE Computer Society, Wireless Medium Access Control (MAC) and Physical Layer (PHY) Specifications for Low-Rate Wireless Personal Area Networks (LR-WPANs), IEEE, 2003
IEEE P802.15 Working Group for WPANs, Cluster Tree Network
TABLE OF CONTENTS
CHAPTER 1: INTRODUCTION 06
1.1 EVOLUTION OF LR-WPAN STANDARDIZATION 06
1.2 ZigBee AND IEEE 802.15.4 07
1.3 WHY IS ZigBee NEEDED 08
1.4 ZigBee AND BLUETOOTH 09
1.5 WIRELESS TECHNOLOGY COMPARISON CHART 10
CHAPTER 2: ZIGBEE / IEEE 802.15. 4 WPAN 12
2.1 COMPONENTS OF WPAN 12
2.2 NETWORK TOPOLOGIES 12
2.2.1 STAR TOPOLOGY 12
2.2.2 PEER-TO-PEER TOPOLOGY 13
2.2.3 CLUSTER-TREE TOPOLOGY 14
2.3 ZIGBEE ARCHITECTURE 15
CHAPTER 3: IEEE 802.15. 4 PHY 17
3.1 RECEIVER ENERGY DETECTION (ED) 19
3.2 LINK QUALITY INDICATION (LQI) 19
3.3 CLEAR CHANNEL ASSESSMENT (CCA) 20
3.4 PPDU FORMAT 20
CHAPTER 4: IEEE 802.15. 4 MAC 22
4.1 FRAME STRUCTURE 22
4.2 CHANNEL ACCESS AND ADDRESSING 23
4.3 SUPER FRAME STRUCTURE 24
4.4 CSMA-CA ALGORITHM 25
4.5 DATA TRANSFER MODEL 26
4.6 MAC LAYER SECURITY 28
TABLE OF CONTENTS (2)
CHAPTER 5: NERWORK LAYER 31
5.1 ZIGBEE NETWORK NODE 32
5.2 RESPONSIBILITIES OF THE ZIGBEE NWK LAYER 32
5.3 NETWORK LAYER SECURITY 33
CHAPTER 6: ZIGBEE ROUTING MECHANISM 35
6.1 AODV: AD HOC ON DEMAND DISTANCE VECTOR 35
6.2 CLUSTER-TREE ALGORITHM 38
6.2.1 SINGLE CLUSTER NETWORK 38
6.2.2 MULTI-CLUSTER NETWORK 41
CHAPTER 7: APPLICATION LAYER 46
7.1 APPLICATION SUPPORT LAYER 46
7.2 THE GENERAL OPERATION FRAMEWORK (GOF) 46
7.3 ZIGBEE DEVICE 47
7.4 ZIGBEE DEVICE OBJECTS 47
CHAPTER 8: ZIGBEE - APPLICATIONS 48
8.1 PRODUCT EXAMPLES 49
8.2 HOME & DIAGNOSTICS EXAMPLES 49
ZIGBEE: CONCLUSION 50
ZIGBEE: BIBLIOGRAPHY 51
ZigBee
Reply
project report tiger
Active In SP
**

Posts: 1,062
Joined: Feb 2010
#2
12-02-2010, 12:04 PM


.doc   ZigBee (IEEE802.15.4).doc (Size: 201.5 KB / Downloads: 233)

ABSTRACT
ZigBee is the name of a specification for a suite of high level communication protocols using small, low-power digital radios based on the IEEE 802.15.4 standard for wireless personal area networks (WPANs). IEEE 802.15.4-2003 (Low Rate WPAN) deals with low data rate but very long battery life (months or even years) and very low complexity. The first edition of the 802.15.4 standard was released in May 2003.
The ZigBee standard was developed by the ZigBee Alliance, which is an association of companies working together to enable reliable, cost-effective, low-power, wirelessly networked, monitoring and control products based on an open global standard. Philips, Motorola, Intel, HP are all members of the Alliance. The goal is to provide the consumer with ultimate flexibility, mobility, and ease of use by building wireless intelligence and capabilities into every day devices.
ZigBee technology is embedded in a wide range of products and applications across consumer, commercial, industrial and government markets worldwide. For the first time, companies will have a standards-based wireless platform optimized for the unique needs of remote monitoring and control applications, including simplicity, reliability, low-cost and low-power.
1. INTRODUCTION
ZigBee is an established set of specifications for wireless personal area networking (WPAN). WPAN Low Rate or ZigBee provides specifications for devices that have low data rates, consume very low power and are thus characterized by long battery life. ZigBee makes possible completely networked homes where all devices are able to communicate and be controlled by a single unit.
When you hold the TV remote and wish to use it you have to necessarily point your control at the device. This one-way, line-of-sight, short-range communication uses infrared (IR) sensors to enable communication and control and it is possible to operate the TV remotely only with its control unit. Add other home theatre modules, an air-conditioner and remotely enabled fans and lights to your room, and you become a juggler who has to handle not only these remotes, but also more numbers that will accompany other home appliances you are likely to use.
Some remotes do serve to control more than one device after memorizing' access codes, but this interoperability is restricted to LOS, that too only for a set of related equipment, like the different units of a home entertainment system
Now picture a home with entertainment units, security systems including fire alarm, smoke detector and burglar alarm, air-conditioners and kitchen appliances all within whispering distance from each other and imagine a single unit that talks with all the devices, no longer depending on line-of-sight, and traffic no longer being one-way.
This means that the devices and the control unit would all need a common standard to enable intelligible communication. ZigBee is such a standard for embedded application software and has been ratified in late 2004 under IEEE 802.15.4 Wireless Networking Standards.
This kind of network eliminates use of physical data buses like USB and Ethernet cables. The devices could include telephones, hand-held digital assistants, sensors and controls located within a few meters of each other.
2. ARCHITECTURE
ZigBee stack architecture is made up of a set of blocks called layers. Each layer performs a specific set of services for the layer above: a data entity provides a data transmission service and a management entity provides all other services. Each service entity exposes an interface to the upper layer through a service access point (SAP), and each SAP supports a number of service primitives to achieve the required functionality.
The ZigBee stack architecture, which is depicted in figure 1 below, is based on the standard Open Systems Interconnection (OSI) seven-layer model but defines only those layers relevant to achieving functionality in the intended market space. The IEEE 802.15.4-2003 standard defines the lower two layers:
¢ The physical (PHY) layer
¢ Medium access control (MAC) sub-layer.
The ZigBee Alliance builds on this foundation by providing the network (NWK) layer and the framework for the application layer, which includes the application support sub-layer (APS), the ZigBee device objects (ZDO) and the manufacturer defined application objects.
IEEE 802.15.4-2003 has two PHY layers that operate in two separate frequency ranges: 868/915 MHz and 2.4 GHz. The lower frequency PHY layer covers both the 868 MHz European band and the 915 MHz band that is used in countries such as the United States and Australia. The higher frequency PHY layer is used virtually worldwide.
The IEEE 802.15.4-2003 MAC sub-layer controls access to the radio channel using a CSMA-CA mechanism. Its responsibilities may also include transmitting beacon frames, synchronization and providing a reliable transmission mechanism.
The responsibilities of the ZigBee NWK layer shall include mechanisms used to join and leave a network, to apply security to frames and to route frames to their intended destinations. In addition, the discovery and maintenance of routes between devices devolve to the NWK layer. The NWK layer of a ZigBee coordinator is

responsible for starting a new network, when appropriate, and assigning addresses to newly associated devices.
The ZigBee application layer consists of the APS, the Application Framework (AF), the ZDO and the manufacturer-defined application objects. The responsibilities of the APS sub-layer include maintaining tables for binding, which is the ability to match two devices together based on their services and their needs, and forwarding messages between bound devices. The responsibilities of the ZDO include defining the role of the device within the network (e.g., ZigBee coordinator or end device), initiating and/or responding to binding requests and establishing a secure relationship between network devices. The ZDO is also responsible for discovering devices on the network and determining which application services they provide.

E£E 802.15.4
defirsd
ZigBe*„¢ Alliance cefred
End manufacturer ifrtsd
Layer
function

APS Sa unly A I'S Mcsaaat
Mam!! .11 Kill M.ui.iMit'iil
Network1 (NWK) Layer
SiAiirtty NWk Message Routing
Urokcr Maiueenicnl
Medium \ecess Control (MAC) Lay
_J I'DiS.VI'
8f.S"l>Mllz
Physical (PHY) Laver
:.4CiH/Itkti..

fF\ is

Figure 1: ZigBee-Stack Architecture

3. DEVICE TYPES
There are three different types of ZigBee device:
(Full-function Device) 3. Device(Reduced of full function device)
¢ ZigBee coordinator (ZC): The most capable device, the coordinator forms the root of the network tree and might bridge to other networks. There is exactly one ZigBee coordinator in each network. It is able to store information about the network, including acting as the repository lor security keys.
¢ ZigBee Router (ZR): Routers can act as an intermediate router, passing data from other devices.
¢ ZigBee End Device (ZED): Contains just enough functionality to talk to its parent node (either the coordinator or a router); it cannot relay data from other devices. It requires the least amount of memory, and therefore can be less expensive to manufacture than a ZR or ZC.
4. MESSAGING
The three messaging modes are:
1. Direct addressing.
2. Indirect addressing.
3. Broadcast addressing.
4.1 DIRECT ADRESSING
Direct addressing assumes device discovery and service discovery have identified a particular device and endpoint. which supply a complementary service to the requestor. Specifically, direct addressing defines a means of directing messages to the device by including its full address and endpoint information. Once devices have been associated, commands can be sent from one device to another. A command is sent to an application object at the destination address.
4.2 INDIRECT ADDRESSING
Use of direct addressing requires the controlling device to have knowledge of the address, endpoint, cluster identifier and attribute identifier of the target device that it wishes to communicate with and to have this information committed to a binding table on the ZigBee coordinator prior to the creation of an indirectly addressed message between the device pair.
A full IEEE 802.15.4 address amounts to 10 octets (PAN identifier plus 64-bit IEEE address) and a further octet is required for the endpoint. Extremely simple devices, such as battery-powered switches, may not want the overhead of storing this information, nor the software for acquiring this information. For these devices, indirect addressing will be more appropriate.
In Indirect addressing mode .when a source device wishes to send a command to a destination, instead of including the address of the destination device (which it does not know and has not stored), it omits the address and specifies indirect addressing via the APSDE-SAP. The included source address, source endpoint and cluster identifier in the indirect addressed message are translated via the binding table to those of the destination device(s) and the messages are relayed to each indicated destination.
Where a cluster contains several attributes, the cluster identifier is used for addressing and the attribute identifier is used in the command itself to identify a particular attribute within the cluster. Attributes are not used in the indirect addressing mechanism and are treated as a part of the data payload. The applications, however, can parse and utilize the attributes as defined within their profile.
4.3 BROADCAST ADDRESSING
An application may broadcast messages to all endpoints on a given destination device. This form of broadcast addressing is called application broadcast. The destination address shall be the 16-bit network broadcast address and the broadcast flag shall be set in the APS frame control field. The source shall include the cluster identifier, profile identifier and source endpoint fields in the APS frame.
5. FRAME FORMAT
This sub-clause specifies the format of the NWK frame (NPDU). Each NWK frame consists of the following basic components:
” A NWK header, which comprises frame control, addressing and sequencing information.
” A NWK payload, of variable length, which contains information specific to the frame type.
5.1 GENERAL NPDU FRAME FORMAT
The NWK frame format is composed of a NWK header and a NWK payload. The fields of the NWK header appear in a fixed order, however, the addressing and sequencing fields may not be included in all frames.
Octets: 2 2 ¦>
L. 1 1 Variable
Frame Con¬trol Destination Address Source Address Radius3 Sequence NumbQi* Frame Payload
Routing Fields
NWK Header NWK Payload
Figure2: NPDU Frame Format
Frame Control Field:-
The frame control field is 16-bits in length and contains information defining the frame type, addressing and sequencing fields and other control flags.
Bits: 0-1 2-5 6-7a 8 9 10-15
Frame type Protocol version Discover route Re-served Security Reserved
Figure3: Frame Control Field The frame type sub-field is two bits in length and shall be set to one of the non-reserved values. The protocol version sub-field is four bits in length and shall be set to a
number reflecting the ZigBee NWK protocol version in use. The DiscoverRoute parameter may be used 10 control route discovery operations for the transit of the frame. The security sub-field shall have a value of 1 if and only if the frame is to have NWK security operations enabled. If security for this frame is implemented at another layer or disabled entirely, it shall have a value of 0.
Destination Address Field:-
The destination address field shall always be present. It shall be 2 octets in length and shall hold the 16-bit network address of the destination device or the broadcast address (Oxffff). The network address of a device shall always be the same as its IEEE 802.15.4-2003 MAC short address.
Source Address Field:-
The source address field shall always be present. It will always be 2 octets in length and shall hold the network address of the source device of the frame. The network address of a device shall always be the same as its IEEE 802.15.4-2003 MAC short address.
Radius Field:-
The radius field shall always be present. It will be one octet in length and specifies the range of a radius transmission. The field shall be decremented by 1 by each receiving device.
Sequence number Fiekl:-
The sequence number field is present in every frame and is 1 octet in length. The sequence number value will be incremented by 1 with each new transmitted frame and the values of the source address field and the sequence number field of a frame, taken as a pair, may be used to uniquely identify a frame within the constraints imposed by the sequence number's 1-octet range. Frame Payload Field:-
The frame payload field has a variable length and contains information specific to individual frame types.
5.2 FORMAT OF INDIVIDUAL FRAME TYPE
There are two delined NWK frame types:
1. Data Frame format
2. NWK command.
1. Data Frame Format:-
The data frame shall be formatted as
Octets: 2 Sec Figure 36 Variable
Frame conlrfli Routing fields Data payload
NWK header NWK pay! oad
Fi2ure4: Data Frame Format
Data frame NWK header field:-
The NWK header tield of a data frame shall contain the frame control field and an appropriate combination of routing fields as required. In the frame control field, the frame type sub-field shall contain the value that indicates a data frame. All other sub-fields shall be set according to the intended use of the data frame. The routing fields shall contain an appropriate combination of address and broadcast fields, depending on the settings in the frame control field.
Data payload field:-
The data payload field of a data frame shall contain the sequence of octets, which the next higher layer has requested the NWK layer to transmit.
2. NWK command frame format:-
The NWK command frame shall be formatted as
Octets.: 1 See Figure 3U 1 Variable
Frame control Routing fields. NWK command identifier NWK command payload
NWK header NWK payload
Figure5: NWK command frame format
NWK command frame NWK header field:-
The NWK header field of a NWK command frame shall contain the frame control field and an appropriate combination of routing fields as required. In the frame control field, the frame type sub-field shall contain the value that indicates a NWK command frame. All other sub-fields shall be set according to the intended use of the NWK command frame. The routing fields shall contain an appropriate combination of address and broadcast fields, depending on the settings in the frame control field.
NWK command identifier field:-
The NWK command identifier field indicates the NWK command being used. This field shall be set to one of the non-reserved values.
NWK command payload field:-
The NWK command payload field of a NWK command frame shall contain the NWK command itself.
5.3 COMMAND FRAMES
The command frames defined by the NWK layer are listed below:-
Command frame identifiei Command nam* Reference
0x01 Route request 2.5.1
Figure6: Command Format
Route request command:-
The route request command allows a device to request that other devices within radio range engage in a search for a particular destination device and establish state within the network that will allow messages to be routed to that destination more easily and economically in the future.
Route reply command:-
The route reply command allows the specified destination device of a route request command to inform the originator of the route request that the request has been received. It also allows ZigBee routers along the path taken by the route request to establish state information that will enable frames sent from the source device to the destination device to travel more efficiently.
Route error command:-
A device uses the route error command when it is unable to forward a data frame. The command notifies the source device of the data frame about the failure in forwarding the frame.
Leave command:-
The leave command is used by the NLME (Network Layer Management Entity) to inform the parent and children of a device that it is leaving the network or else to request that a device leave the network.
6. NETWORK TOPOLOGY
The ZigBee network layer (NWK) supports 3 types of topologies:
¢ Star topology.
¢ Tree topology.
¢ Mesh topology.
In a star topology, the network is controlled by one single device called the ZigBee coordinator. The ZigBee coordinator is responsible for initiating and maintaining the devices on the network, and all other devices, known as end devices, directly communicate with the ZigBee coordinator.
In mesh and tree topologies, the ZigBee coordinator is responsible for starting the network and for choosing certain key network parameters but the network may be extended through the use of ZigBee routers.
CD
In tree networks, routers move data and control messages through the network using a hierarchical routing strategy. Tree networks may employ beacon-oriented communication as described in the IEEE 802.15.4-2003 specification. Mesh networks shall allow full peer to- peer communication. ZigBee routers in mesh networks shall not emit regular IEEE 802.15.4-2003 beacons.
7. GENERAL CHARACTERISTICS
¢ The focus of network applications under the IEEE 802.15.4 / ZigBee standard include the features of low power consumption, needed for only two major modes (Tx/Rx or Sleep), high density of nodes per network, low costs and simple implementation.
¢ 2.4GHz and 868/915 MHz dual PHY modes. This represents three license-free bands: 2.4-2.4835 GHz, 868-870 MHz and 902-928 MHz. The number of channels allotted to each frequency band is fixed at sixteen (numbered 11-26), one (numbered 0) and ten (numbered 1-10) respectively. The higher frequency band is applicable worldwide, and the lower band in the areas of North America, Europe, Australia and New Zealand.
¢ Low power consumption, with battery life ranging from months to years. Considering the number of devices with remotes in use at present, it is easy to see that more numbers of batteries need to be provisioned every so often, entailing regular (as well as timely), recurring expenditure. In the ZigBee standard, longer battery life is achievable by either of two means: continuous network connection and slow but sure battery drain, or intermittent connection and even slower battery drain.
¢ Maximum data rates allowed for each of these frequency bands are fixed as 250 kbps @2.4 GHz, 40 kbps @ 915 MHz, and 20 kbps @868 MHz.
¢ High throughput and low latency for low duty-cycle applications (<0.1%)
¢ Channel access using Carrier Sense Multiple Access with Collision Avoidance (CSMA - CA)
¢ Addressing space of up to 64 bit IEEE address devices, 65,535 networks, 50m typical range.
¢ Fully reliable hand-shaked data transfer protocol.
8. TRAFFIC TYPES
ZigBee/IEEE 802.15.4 addresses three typical traffic types. IEEE 802.15.4 MAC can accommodate all the types.
¢ Data is periodic: - The application dictates the rate, and the sensor activates, checks for data and deactivates.
¢ Data is intermittent. The application, or other stimulus, determines the rate, as in the case of say smoke detectors. The device needs to connect to the network only when communication is necessitated. This type enables optimum saving on energy.
¢ Data is repetitive, and the rate is fixed a priori. Depending on allotted time slots, called GTS (guaranteed time slot), devices operate for fixed durations.
ZigBee employs either of two modes, beacon or non-beacon to enable the to-and-fro data traffic. Beacon mode is used when the coordinator runs on batteries and thus offers maximum power savings, whereas the non-beacon mode finds favour when the coordinator is mains-powered.
In the beacon mode, a device watches out for the coordinator's beacon that gets transmitted at periodically, locks on and looks for messages addressed to it. If message transmission is complete, the coordinator dictates a schedule for the next beacon so that the device goes to sleep; in fact, the coordinator itself switches to sleep mode.
While using the beacon mode, all the devices in a mesh network know when to communicate with each other. In this mode, necessarily, the timing circuits have to be quite accurate, or wake up sooner to be sure not to miss the beacon. This in turn means an increase in power consumption by the coordinator's receiver, entailing an optimal increase in costs.
Coordinator Network Device
Beacon
Data w
Acknowledgment k
2 P
(optional}
Figure7: Beacon Network Communication
The non-beacon mode will be included in a system where devices are asleep nearly always, as in smoke detectors and burglar alarms. The devices wake up and confirm their continued presence in the network at random intervals.
On detection of activity, the sensors spring to attention, as it were, and transmit to the ever-waiting coordinator's receiver (since it is mains-powered). However, there is the remotest of chances that a sensor finds the channel busy, in which case the receiver unfortunately would miss a call
Coords N*»k |
. .. Data.
Acknowledgment

Figure8: Non-Beacon Network Communication.

9. NETWORK MODEL
The functions of the Coordinator, which usually remains in the receptive mode, encompass network set-up, beacon transmission, node management, storage of node information and message routing between nodes.

Figure9: Zigbee Network Model
For the sake of simplicity without jeopardizing robustness, this particular IEEE standard defines a quartet frame structure and a super-frame structure used optionally only by the coordinator.
The four frame structures are:-
¢ Beacon frame for transmission of beacons
¢ Data frame for all data transfers
The network node, however, is meant to save energy (and so sleeps for long periods) and its functions include searching for network availability, data transfer, checks for pending data and queries for data from the coordinator.
¢ Acknowledgement frame for successful frame receipt confirmations
¢ MAC command frame
These frame structures and the coordinator's super-frame structure play critical roles in security of data and integrity in transmission.
All protocol layers contribute headers and footers to the frame structure, such that the total overheads for each data packet range are from 15 octets (for short addresses) to 31 octets (for 64-bit addresses).
The coordinator lays down the format for the super-frame for sending beacons after every 15.38 ms or/and multiples thereof, up to 252s. This interval is determined a priori and the coordinator thus enables sixteen time slots of identical width between beacons so that channel access is contention-less. Within each time slot, access is contention-based. Nonetheless, the coordinator provides as many as seven GTS (guaranteed time slots) for every beacon interval to ensure better quality.
10. PHYSICAL PACKET STRUCTURE
Preamble Start of Packet Delimiter ptn
Header PHY Service Data Unit (PSDU)
h
6 octets w 0-127 Octets
The Physical packet fields are:
¢ Preamble
¢ SPD(Start of packet delimiter)
¢ Physical header
¢ Physical service data unit(PSDU)
Preamble:-32bits (4 octets) of alternating 0s and Is is to synchronize the receivers.
SPD Start of Packet Delimiter: This would be 8 bits (I octet)in length marking the start of the packet. Its appearance depends on the signaling method. It provides a secure way of detecting the start of the frame.
Physical Header: This would be 8 bits that are used to denote the Physical service data unit length.
PSDU (Physical service data unit): This would be 0-1016 (1-127 octets) bits to carry the actual data.
11. TECHNOLOGY COMPARISON
Why Zigbee This question could be easily answered by undergoing a comparison study of Zigbee with one of the wireless technology-Bluetooth.
The bandwidth of Bluetooth is 1 Mbps; ZigBee's is one-fourth of this value. The strength of Bluetooth lies in its ability to allow interoperability and replacement of cables, ZigBee's, of course, is low costs and long battery life.
In terms of protocol stack size, ZigBee's 32 KB is about one-third of the stack size necessary in other wireless technologies (for limited capability end devices, the stack size is as low as 4 KB).
Most important in any meaningful comparison are the diverse application areas of all the different wireless technologies. Bluetooth is meant for such target areas as wireless USB's, handsets and headsets, whereas ZigBee is meant to cater to the sensors and remote controls market and other battery operated products.
In a gist, it may be said that they are neither complementary standards nor competitors, but just essential standards for different targeted applications. The earlier Bluetooth targets interfaces between PDA and other device (mobile phone / printer etc) and cordless audio applications.
The IEEE 802.15.4 based ZigBee is designed for remote controls and sensors, which are very many in number, but need only small data packets and, mainly, extremely low power consumption for (long) life. Therefore they are naturally different in their approach to their respective application arenas.
12. CONCLUSION
The ZigBee Alliance is an association of companies working together to enable reliable, cost-effective, low-power, wirelessly networked, monitoring and control products based on an open global standard.
It is the only global wireless communications standard that allows the development of easily deployable, low-power monitoring and control products.
ZigBee technology is being embedded into a growing number of products across consumer, commercial, industrial and government markets worldwide. The ZigBee communication standard is key to the growth of wireless home and building automation applications where various end products need to communicate with each other.
The ZigBee standard is the only standard that specifically addresses the typical requirements for wireless control and monitoring applications such as:
¢ Large number of nodes/sensors
¢ Very low system/node costs
¢ Operation for years on inexpensive batteries
¢ Reliable and secure links between network nodes
¢ Easy deployment and configuration
¢ Global solutions
13. FUTURE SCOPE
The ZigBee Alliance targets applications "across consumer, commercial, industrial and government markets worldwide".
Unwired applications are highly sought after in many networks that are characterized by numerous nodes consuming minimum power and enjoying long battery lives.
ZigBee technology is designed to best suit these applications, for the reason that it enables reduced costs of development, very fast market adoption, and rapid ROI.
Airbee Wireless Inc has tied up with Radiocrafts AS to deliver "out-of-the-box" ZigBee-ready solutions; the former supplying the software and the latter making the module platforms. With even light controls and thermostat producers joining the ZigBee Alliance, the list is growing healthily and includes big OEM names like HP, Philips, Motorola and Intel.
With ZigBee designed to enable two-way communications, not only will the consumer be able to monitor and keep track of domestic utilities usage, but also feed it to a computer system for data analysis.
A recent analyst report issued by West Technology Research Solutions estimates that by the year 2008, "annual shipments for ZigBee chipsets into the home automation segment alone will exceed 339 million units," and will show up in "light switches, fire and smoke detectors, thermostats, appliances in the kitchen, video and audio remote controls, landscaping, and security systems."
Since Wireless personal Area Networking applies not only to household devices, but also to individualized office automation applications, ZigBee is here to stay. It is more than likely the basis of future home-networking solutions.


1. zigbee.org
2. wikipedia.com
3. ti.com
4. zigbeetutorial.com
14. BIBLIOGRAPHY
W *rA.

CONTENTS
Page No:
1. INTRODUCTION I
2. ARCHITECTURE 2
3. DEVICE TYPES 4 ¦
4. MESSAGING 5
4.1) DIRECT ADDRESSING 5
4.2) INDIRECT ADDRESSING 5
4.3) BROADCAST ADDRESSING 6
5. FRAME FORMAT 7
5.1) GENERAL NPDU FRAME FORMAT 7
5.2) FORMAT OF INDIVIDUAL FRAME TYPE 9
5.3) COMMAND FRAME 11
6. NETWORK TOPOLOGY 12
7. GENERAL CHARCTERISTICS 13
8. TRAFFIC TYPES 14
9. NETWORK MODEL 16
10. PHYSICAL PACKET STRUCTURE 18
11. TECHNOLOGY COMPARISON 19
12. CONCLUSION 20
13. FUTURE SCOPE 21
14. BIBLIOGRAPHY 22
Reply
seminar presentation
Active In SP
**

Posts: 582
Joined: Apr 2010
#3
01-05-2010, 07:45 PM

please read topicideashow-to-zigbee-networks-full-report and topicideashow-to-seminar and presentation-report-on-zigbee-next-generation-wireless-network for getting more information of zigbee technology
Use Search at http://topicideas.net/search.php wisely To Get Information About Project Topic and Seminar ideas with report/source code along pdf and ppt presenaion
Reply
computer science topics
Active In SP
**

Posts: 610
Joined: Jun 2010
#4
07-06-2010, 09:27 PM


.docx   WIRELESS COMMUNICATION ZIGBEE.docx (Size: 392.38 KB / Downloads: 173)
WIRELESS COMMUNICATION
ZIGBEE

Presented BY,
N.Devi Sowjanya
III/IV ECE
G.Anusha
III/IV ECE
SHRI VISHNU ENGINEERING COLLEGE FOR WOMEN
BHIMAVARAM
ANDHRA PRADESH

SVECW
1

Abstract

The concept of zigbee is associated with controlling all electronic
devices and communicating with themselves with the surrounding by using simple our
mobile or pc by using this latest technology.The serious problem in this world is cables
tremendous growth in science which is solved by this.
Zigbee is a set of specs built around the IEEE 802.15.4 wireless
protocol. Zigbee devices are actively limited to a through-rate of 250kbps,operating on
the 2.4GHZ ISM band,which is available throughout most of the world .This acts as co-
ordinate and slave.This gives commands and receives commands from other electronic
devices. This can connect upto 65,553 devices per unit.The important feature of Zigbee is
provide with memory and logical unit for the first time.This helps in taking independent
decisions by itself with need of coordinator,which help in sensor devices.There are
technologies which already available in the market line BloothTooth.Their some ensured
suides in that which lead to develop Zigbee.It has major advantage that it has low power
consumption (30ma). Other advantages that it provide high security to all electronic
devices.Another important thing is that it is of low cost.This can serve all purposes in
industries and home appliancies ¦.It is very simple to operate by everyone . By all my
statements I can conclude that in future we are going to a new world with
cables,everything is done by single controls without using multi switches multi purposes.

Introduction

ZigBee is the name of a specification for a suite of high level
communication protocols using small, low-power digital radios based on the IEEE
802.15.4 standard for wireless personal area networks (WPANs).
ZigBee operates in the industrial, scientific and medical ( ISM) radio
bands; 868 MHz in Europe, 915 MHz in the USA and 2.4 GHz in most jurisdictions
worldwide. The technology is intended to be simpler and cheaper than other WPANs
SVECW
2
such as Bluetooth. The most capable ZigBee node type is said to require only about 10%
of the software of a typical Bluetooth or Wireless Internet node, while the simplest nodes
are about 2%. However, actual code sizes are much higher, more like 50% of Bluetooth
code size. ZigBee chip vendors have announced 128-kilobyte devices.
What is Zigbee?
Zigbee is a wireless networking standard that is aimed at remote control
and sensor applications which is suitable for operation in harsh radio environments and in
isolated locations. It builds on IEEE standard 802.15.4 which defines the physical and
MAC layers. Above this, Zigbee defines the application and security layer specifications
enabling interoperability between products from different manufacturers. In this way
Zigbee is a superset of the 802.15.4 specification.
The 802.15.4 standard is primarily aiming at monitoring and control applications. Low
power consumption is the most important feature that makes battery operated devices
operates for a long time. The amount of data throughput (bandwidth) is relatively low
compared to wireless LAN for example, but with 250kbps for many applications more
than enough. The distance between 2 nodes can be up to 50 meters but be aware the each
node can relay data to the next making a very big network, covering significant distances,
possible.
Hardware (Physical and MAC layers)
The 2.4GHz frequency band is a license free band, so a ZigBee product may
be used all over the world. All current products seem to be using the 2.4GHz band at the
moment. Take a look at the next table for a few differences between the bands:
Frequency
Bandwidth
868 MHz
20 kbps
915 MHz
40 kbps
2.4GHz
250 kbps
SVECW
Nr. of channels 1
3
10
16
In all bands DSSS (Direct sequence spread spectrum) is used. 868 and 915 MHz are
using Binary Phase Shift Keying and 2.4GHz uses O-QPSK (Offset Quadrature Phase
Shift Keying). Like in any network data is transmitted in packets. ZigBee's packets have
a maximum size of 128 bytes including protocol overhead. In total there is room for a
maximum of 104 bytes. For realtime features, ZigBee has the possibility to define high
priority messages. This is achieved by use of a guaranteed timeslot mechanism so that the
high priority messages can be send as fast as possible.
ZigBee uses 2 kinds of addressing. There is a 64 bit IEEE address that can be compared
to the IP address on the internet. There is also a 16 bit short address. The short addresses
are used once a network is setup so this makes a total of 2^16 = ~64000 nodes within one
network possible. This is enough for almost anything imaginable.
The ZigBee upper layers
Figure 1:Layers in Zigbee
The layers above that what 802.15.4 specifies is what we call the ZigBee
standard (look above for a graphical overview). Many aspect of the network are specified
in this layer, like: Application profiles, security settings and the messaging.
SVECW
4
ZigBee is known because of its mesh network architecture but it does also support a star
topology or cluster tree or hybrid architecture. Depending on the application or situation
each kind of topology has its own advantages and disadvantages. A star topology is very
simple, all nodes directly communicate with one central node (like a star...). The mesh
topology is more complicated, each node may communicate with any other node within
range. It's easy to understand that this gives many possible routes through the network;
this makes it a very robust topology because bad performing routes can be ignored. The
cluster tree topology is basically a combination of star and mesh.

Software and hardware

The software is designed to be easy to develop on small, cheap
microprocessors. The radio design used by ZigBee has been carefully optimized for low
cost in large scale production. It has few analog stages and uses digital circuits wherever
possible.
Even though the radios themselves are cheap, the ZigBee Qualification Process involves
a full validation of the requirements of the physical layer. This amount of concern about
the Physical Layer has multiple benefits, since all radios derived from that semiconductor
mask set would enjoy the same RF characteristics. On the other hand, an uncertifed
physical layer that malfunctions could cripple the Battery lifespan of other devices on a
Zigbee Network. Where other protocols can mask poor sensitivity or other esoteric
problems in a fade compensation response, ZigBee radios have very tight engineering
constraints: they are both power and bandwidth constrained. Thus, radios are tested to the
ISO-17025 standard with guidance given by Clause 6 of the 802.15.4-2003 Standard.
Most vendors plan to integrate the radio and microcontroller onto a single chip.

Why choose ZigBee?

¢ Reliable and self healing
¢ Supports large number of nodes
SVECW
5
¢ Easy to deploy
¢ Very long battery life
¢ Secure
¢ Low cost
¢ Can be used globally
The 802 Wireless Space


ZigBee specification

The ZigBee Alliance is an association of companies working together to
enable reliable, cost-effective, low-power, wirelessly networked, monitoring and control
products based on an open global standard.
Data Reliability
Reliable data delivery is critical to ZigBee applications. The underlying
802.15.4 standard provides strong reliability through several mechanisms at multiple
layers. For example, it uses 27 channels in three separate frequency bands (see Figure 3).
SVECW
6
IEEE 802.15.4 provides three
frequency bands for
communications. Global utility,
propagation, path loss, and data
rate differences let ZigBee profile
developers optimize system
performance.
Figure 3.
The 2.4 GHz band is used worldwide and has 16 channels and a maximum over-the-air
data rate of 250 Kbps. Lower frequency bands are also specified.
The information is coded onto the carrier with direct sequence spread spectrum (DSSS),
an inherently robust method of improving multipath performance and receiver sensitivity
through signal processing gain. The receiver sensitivity and selectivity is well suited for
inexpensive silicon processes, with most vendors promising to meet or beat the standard.
The size of the data payload ranges from 0 to 104 bytes, more than enough to meet most
sensor needs. Figure 4 shows the construction of the data frame, also called a data packet.
The data packet is one of four packet structures provided
in 802.15.4/ZigBee. In the MAC protocol data unit, the
data payload is appended with source and destination
addresses, a sequence number to allow the receiver to
recognize that all packets transmitted have been received,
frame control bytes that specify the network environment
and other important parameters, and finally a frame check
sequence that lets the receiver verify that the packet was
received uncorrupted. This MAC frame is appended to a
PHY synchronization and PHY header, which provides a
Figure 4.
robust mechanism for the receiver to quickly recognize
and decode the received packet.
After receiving a data packet, the receiver performs a 16-bit cyclic redundancy check
(CRC) to verify that the packet was not corrupted in transmission. With a good CRC, the
SVECW
7
receiver can automatically transmit an acknowledgement packet (depending on
application and network needs), allowing the transmitting station to know that the data
were received in an acceptable form. If the CRC indicates the packet was corrupt, the
packet is dropped and no acknowledgement is transmitted. When a developer configures
the network to expect acknowledgement, the transmitting station will retransmit the
original packet a specified number of times to ensure successful packet delivery. If the
path between the transmitter and receiver has become less reliable or a network failure
has occurred, ZigBee provides the network with self- healing capabilities when alternate
paths (if physically available) can be established autonomously.

Battery Life

In many applications, you canâ„¢t afford to make regular trips back to a sensor
to change the battery. Ideally, the sensor is good for the life of the battery.
The basic 802.15.4 node is fundamentally efficient in terms of battery performance. You
can expect battery lifetimes from a few months to many years as a result of a host of
system power-saving modes and battery-optimized network parameters, such as a
selection of beacon intervals, guaranteed time slots, and enablement/disablement options.
Star networks are the most common, basic structure with
broad utility. For larger physical environments, the cluster
tree is a good way to aggregate multiple basic star networks
into one larger network. Some applications will make best
use of the mesh structure, which provides alternate route
flexibility and the capability for the network to heal itself
when intermediate nodes are removed or RF paths change.
Figure 5.
SVECW
8

Transmission Range

The standard specifies transmitter output power at a nominal “3 dBm (0.5
mW), with the upper limit controlled by the regulatory agencies of the region in which
the sensor is used. At “3 dBm output, single-hop ranges of 10 to more than 100 m are
reasonable, depending on the environment, antenna, and operating frequency band.
Data Rate
Higher data rates at a given power level mean thereâ„¢s less energy per
transmitted bit, which generally implies reduced range. But both 802.15.4 and ZigBee
value battery life more than raw range and provide mechanisms to improve range while
always concentrating on battery life.

Data Latency

Sensor systems have a broad range of data-latency requirements. If sensor
data are needed within tens of milliseconds, as op-posed to dozens of seconds, the
requirement places different demands on the type and extent of the intervening network.
For many sensor applications, data latency is less critical than battery life or data
reliability.For simple star networks (many clients, one network coordinator), ZigBee can
provide latencies as low as ~16 ms in a beacon-centric network, using guaranteed time
slots to prevent interference from other sensors. Data latency can also affect battery life.
Size
As silicon processes and radio technology progress, transceiver systems
shrink in physical size. . In the case of ZigBee systems, the radio transceiver has become
a single piece of silicon, with a few passive components and a relatively non critical
board design.
SVECW
9

Data Security

Itâ„¢s important to provide your sensor network with adequate security to
prevent the data from being compromised, stolen, or tampered with. IEEE 802.15.4
provides authentication, encryption, and integrity services for wireless systems that allow
systems developers to apply security levels as required. The ZigBee security toolbox
consists of key management features that let you safely manage a network remotely.

APPLICATIONS

Zigbee protocols are intended for use in embedded applications requiring low
data rates and low power consumption. ZigBee's current focus is to define a general-
purpose, inexpensive, self-organizing, mesh network that can be used for industrial
control, embedded sensing, medical data collection, smoke and intruder warning,
building automation, home automation, etc.
ZigBee standard addresses the unique needs of most remote monitoring and control
applications:
Enables the broad based deployment of simple, reliable, low cost wireless
network solutions
Provides the ability to run for years on inexpensive primary batteries
Provides the ability to inexpensively support robust mesh networking
technologies .
Home Automation
Building Automation
Industrial Automation
Figure 6: ZigBee Home Automation
SVECW
10

Conclusion

ZigBee is all set to provide the consumers with ultimate flexibility,
mobility, and ease of use by building wireless intelligence and capabilities into every day
devices. ZigBee technology will be embedded in a wide range of products and
applications across consumer, commercial, industrial and government markets
worldwide. For the first time, companies will have a standards-based wireless platform
optimized for the unique needs of remote monitoring and control applications, including
simplicity, reliability, low-cost and low-power.

REFERENCES

1. INTRODUCTION - Z:\wireless com-zig\wireless-zigbee\ZigBee - Wikipedia, the
free encyclopedia.htm
2. WHAT IS ZIGBEE - Z:\wireless com- zig\wireless-zigbee\What is ZigBee.htm-
Z:\wireless com- zig\wireless
3. UPPER LAYERS - zigbee\ZigBee, a wireless mesh network (hasse_nl).htm
4. SPECIFICATIONS - Z:\wireless com- zig\wireless-zigbee\zig.htm
5. APPLICATIONS - Z:\wireless com- zig\wireless-zigbee\ZigBee - Wikipedia, the
free encyclopedia.htm
SVECW
11
Use Search at http://topicideas.net/search.php wisely To Get Information About Project Topic and Seminar ideas with report/source code along pdf and ppt presenaion
Reply
project report helper
Active In SP
**

Posts: 2,270
Joined: Sep 2010
#5
05-10-2010, 11:36 AM


.doc   REPORT ON Zigbee.doc (Size: 980 KB / Downloads: 192)
ZigBee IEEE 802

SUBMITTED IN PARTIAL FULFILLMENT FOR THE DEGREE OF BACHELOR OF ENGINEERING IN
COMPUTER ENGINEERING



SUBMITTED BY:-

Amit Shah 56
Ramesh Shekelli 58
Gauri Sawant 54


UNDER THE GUIDANCE OF
Mr. Alone
PADMABHUSHAN VASANTDADA PATIL PRATHISHTHAN
COLLEGE OF ENGINEERING
MUMBAI – 400022



ABSTRACT

ZigBee is a low-cost, low-power, wireless mesh networking proprietary standard. The low cost allows the technology to be widely deployed in wireless control and monitoring applications, the low power-usage allows longer life with smaller batteries, and the mesh networking provides high reliability and larger range.

The ZigBee Alliance is an association of companies working together to enable reliable, cost-effective, low-power, wirelessly networked, monitoring and control products based on an open global standard. As per its main role, it standardize the body that defines ZigBee, also publishes application profiles that allow multiple OEM vendors to create interoperable products.

The current list of application profiles either published or in the works are:

* Home Automation
* ZigBee Smart Energy 1.0/2.0
* Commercial Building Automation
* Telecommunication Applications
* Personal, Home, and Hospital Care
* Toys

Reply
project report helper
Active In SP
**

Posts: 2,270
Joined: Sep 2010
#6
09-10-2010, 12:12 PM


.docx   Mccs final assainment 1.docx (Size: 412.63 KB / Downloads: 102)
ZIGBEE MESH ROUTING VERSUS TREE ROUTING


Mobile Computer Communication Systems

Submitted by:
SOWMYA DYAKAM
(08008481)

Submitted to:
Dr. Alison Carrington



Abstract:
Zigbee is an open technology which was formulated by Zigbee alliance to lead the drawbacks of Bluetooth and Wi-Fi, It is an IEEE 802.15.4 standard developed for wide communications. In this paper we discuss about the Zigbee applications, security, sensors and feature work, about mesh routing and how it works, tree routing and how it works, similarities and difference between mesh and the critical analysis on simulation results
Introduction:
Wireless networking faced a rapid growth in past few decades, at the early invention period this is mainly concentrated on long range and fast communication which is Wi-Fi (IEEE 802.11). Then Bluetooth was originated in 1994 which is mainly focused on low rate WPAN (Wireless Personal Area Network) but a little problem occurs due to its limited range of network (10m). After the deep research in wireless systems IEEE developed a new standard in order to satisfy all the needs like longer battery life, most economical and high security. With these standards IEEE clubbed with Zigbee Alliance to start a new era in the history of wireless networking is ZIGBEE. There are many other wireless networks like Wi-Fi and BLUETOOTH which does not satisfy the complete requirements in control devices and sensors. Though sensors and control devices do not require high bandwidth, they require low energy consumption for long battery life. In order to meet all these requirements ZIGBEE was developed, it allows the battery to last up to years irrespective of changing their cells (Anil 2007). Zigbee supports three types of routing topologies star, mesh and tree. In mesh routing it has connection with all the nodes within the
network. Star routing has hub at the centre at which all other nodes are connected from hub. Tree is also known as hierarchical routing, in this topology the central root node is joined to one or more nodes (Karris 2009).

Reply
seminar surveyer
Active In SP
**

Posts: 3,541
Joined: Sep 2010
#7
20-10-2010, 03:47 PM


Prepared by:
Sinem Coleri Ergen


Abstract
This document gives the motivation for the ZigBee alliance and explains the physical, medium access and routing layers of ZigBee.

Introduction

Evolution of LR-WPAN Standardization
The cellular network was a natural extension of the wired telephony network that became pervasive during the mid-20th century. As the need for mobility and the cost of laying new wires increased, the motivation for a personal connection independent of location to that network also increased. Coverage of large area is provided through (1-2km) cells that cooperate with their neighbors to create a seemingly seamless network. Examples of standards are GSM, IS-136, IS-95. Cellular standards basically aimed at facilitating voice communications throughout a metropolitan area. During the mid-1980s, it turned out that an even smaller coverage area is needed for higher user densities and the emergent data traffic. The IEEE 802.11 working group for WLANs is formed to create a wireless local area network standard.

Whereas IEEE 802.11 was concerned with features such as Ethernet matching speed, longrange( 100m), complexity to handle seamless roaming, message forwarding, and data throughput of 2-11Mbps, WPANs focus of WPANs is low-cost, low power, short range and very small size. The IEEE 802.15 working group is formed to create WPAN standard. This group has currently defined three classes of WPANs that are differentiated by data rate, battery drain and quality of service(QoS). The high data rate WPAN(IEEE 802.15.3) is suitable for multi-media applications that require very high QoS. Medium rate WPANs (IEEE 802.15.1/Blueetooth) will handle a variety of tasks ranging from cell phones to PDA communications and have QoS suitable for voice communications. The low rate WPANs(IEEE 802.15.4/LR-WPAN) is intended to serve a set of industrial, residential and medical applications with very low power consumption and cost requirement not considered by the aboveWPANs and with relaxed needs for data rate and QoS. The low data rate enables the LR-WPAN to consume very little power.

ZigBee and IEEE 802.15.4
ZigBee technology is a low data rate, low power consumption, low cost, wireless networking protocol targeted towards automation and remote control applications. IEEE 802.15.4 committee started working on a low data rate standard a short while later. Then the ZigBee Alliance and the IEEE decided to join forces and ZigBee is the commercial name for this technology. ZigBee is expected to provide low cost and low power connectivity for equipment that needs battery life as long as several months to several years but does not require data transfer rates as high as those enabled by Bluetooth. In addition, ZigBee can be implemented in mesh networks larger than is possible with Bluetooth. ZigBee compliant wireless devices are expected to transmit 10-75 meters, depending on the RF environment and the power output consumption required for a given application, and will operate in the unlicensed RF worldwide(2.4GHz global, 915MHz Americas or 868 MHz Europe). The data rate is 250kbps at 2.4GHz, 40kbps at 915MHz and 20kbps at 868MHz. IEEE and ZigBee Alliance have been working closely to specify the entire protocol stack. IEEE 802.15.4 focuses on the specification of the lower two layers of the protocol(physical and data link layer). On the other hand, ZigBee Alliance aims to provide the upper layers of the protocol stack (from network to the application layer) for interoperable data networking, security services and a range of wireless home and building control solutions, provide interoperability compliance testing, marketing of the standard, advanced engineering for the evolution of the standard. This will assure consumers to buy products from different manufacturers with confidence that the products will work together.

IEEE 802.15.4 is now detailing the specification of PHY and MAC by offering building blocks for different types of networking known as ”star, mesh, and cluster tree”. Network routing schemes are designed to ensure power conservation, and low latency through guaranteed time slots. A unique feature of ZigBee network layer is communication redundancy eliminating ”single point of failure” in mesh networks. Key features of PHY include energy and link quality detection, clear channel assessment for improved coexistence with other wireless networks.

ZigBee vs. Bluetooth
ZigBee looks rather like Bluetooth but is simpler, has a lower data rate and spends most of its time snoozing. This characteristic means that a node on a ZigBee network should be able to run for six months to two years on just two AA batteries. (HOW?) The operational range of ZigBee is 10-75m compared to 10m for Bluetooth(without a power amplifier).
ZigBee sits below Bluetooth in terms of data rate. The data rate of ZigBee is 250kbps at 2.4GHz, 40kbps at 915MHz and 20kbps at 868MHz whereas that of Bluetooth is 1Mbps. ZigBee uses a basic master-slave configuration suited to static star networks of many infrequently used devices that talk via small data packets. It allows up to 254 nodes. Bluetooth’s protocol is more complex since it is geared towards handling voice, images and file transfers in ad hoc networks. Bluetooth devices can support scatternets of multiple smaller non-synchronized networks(piconets). It only allows up to 8 slave nodes in a basic master-slave piconet set-up. When ZigBee node is powered down, it can wake up and get a packet in around 15 msec whereas a Bluetooth device would take around 3sec to wake up and respond.


for more details, please visit
sinemergenzigbee.pdf

Reply
project report helper
Active In SP
**

Posts: 2,270
Joined: Sep 2010
#8
20-10-2010, 05:15 PM


.pptx   zigbee.pptx (Size: 981.05 KB / Downloads: 112)
ZigBee

By

Akshaya Hebbar
Sneha Wadke
Pallavi Kulkarni



INTRODUCTION


ZigBee - based on IEEE 802.15.4 wireless protocol.

The ZigBee Alliance aims at key design requirements of wireless networks such as low costs, reliability and less complexity.

It works in the RF range- 2.4 GHz worldwide,868 MHz is the European standard and 916 in the US.
Reply
project report helper
Active In SP
**

Posts: 2,270
Joined: Sep 2010
#9
01-11-2010, 02:01 PM


.ppt   ZigBee.ppt (Size: 1.92 MB / Downloads: 112)
ZigBee THE FUTURE OF TOMORROW

Presented by

VENKATA KRISHNA BANDARU
10407202
4th year E.C.E D



ZigBee Frequencies

Operates in Unlicensed Bands
ISM 2.4 GHz Global Band at 250kbps
868 MHz European Band at 20kbps
915 MHz North American Band at 40kbps

Reply
seminar class
Active In SP
**

Posts: 5,361
Joined: Feb 2011
#10
11-03-2011, 04:40 PM

Presented by:
Chris Diamond
Michael Gordon
Priya Joshi
Gideon Wamae


.ppt   ZigBee.ppt (Size: 2.22 MB / Downloads: 115)
ZigBee
Presentation Outline

 Gideon
– What ZigBee is
– What ZigBee does
 Chris
– How ZigBee works
– The hype cycle
 Priya
– Academic research
 Michael:
– Products
– Future
– What is ZigBee?
Technological Standard Created for Control and Sensor Networks
 Based on the IEEE 802.15.4 Standard
 Created by the ZigBee Alliance
 IEEE 802.15.4 & ZigBee In Context
 The 802 Wireless Space
 ZigBee and Other Wireless Technologies
 ZigBee Aims Low
 Low data rate
 Low power consumption
 Small packet devices
 ZigBee Frequencies
 Operates in Unlicensed Bands
 ISM 2.4 GHz Global Band at 250kbps
 868 MHz European Band at 20kbps
 915 MHz North American Band at 40kbps
What Does ZigBee Do?
 Designed for wireless controls and sensors
 Operates in Personal Area Networks (PAN’s) and device-to-device networks
 Connectivity between small packet devices
 Control of lights, switches, thermostats, appliances, etc.
 Lights and Switches
 How ZigBee Works
 Topology
– Star
– Cluster Tree
– Mesh
 Network coordinator, routers, end devices
How ZigBee Works
 States of operation
– Active
– Sleep
 Devices
– Full Function Devices (FFD’s)
– Reduced Function Devices (RFD’s)
 Modes of operation
– Beacon
– Non-beacon
ZigBee Mesh Networking
 Research in ZigBee
 Introduction
 Research
 Research Papers
Introduction
 The IEEE 802.15.4 standard was completed in May 2003.
 The ZigBee specifications were ratified on 14 December 2004.
 The ZigBee Alliance announced public availability of Specification 1.0 on 13 June 2005.
 Much research is still going on with ZigBee.
 Academic Research
Research in ZigBee is being conducted in different fields:
 Wireless and sensor networks
 Wireless communications
 Neuroengineering
Research Papers
 Time Synchronization for ZigBee Networks
 ZigBee: “Wireless Control That Simply Works”
 Journal of Neuroengineering and Rehabilitation
 Development of Ubiquitous Sensor Network
 Wireless Technologies for Data Acquisition Systems
ZigBee and the Market
 The next big thing
 Expected to hit the market full force in 2006
 Companies have already invested millions
ZigBee Products
 Development Kits
 Sensors
 Transceivers
 Modules
Current ZigBee Uses
 Environmental Monitoring
 Agricultural Monitoring
 Home Automation Still on Horizon
Product Applications
 Road map products-tracking
 Consumer electronics
 PC
 Personal and healthcare
 Commercial and residential control
Reply
seminar class
Active In SP
**

Posts: 5,361
Joined: Feb 2011
#11
15-03-2011, 10:00 AM


.pdf   Vineet - Original Report.pdf (Size: 209.71 KB / Downloads: 64)
ABSTRACT
My seminar and presentation topic is “ZigBee”. ZigBee is a new wireless technology developed by the
ZigBee Alliance to overcome the limitations of BLUETOOTH and Wi-Fi. ZigBee is
developed on the top of IEEE 802.15.4 standard. It is designed for low-power
consumption allowing batteries to essentially last forever.Though we have couple of
methods for multimedia applications, till now nothing has been developed for sensor
networking and control machines which require longer battery life and continuous
working without human intervention. ZigBee devices allow batteries to last up to
years using primary cells (low cost) without any chargers (low cost and easy
installation).
The ZigBee standard provides network, security, and application support services
operating on top of the IEEE 802.15.4.IEEE 802.15.4 standard has two basic layers
medium Access Control (MAC) and Physical Layer (PHY) wireless standard. The
network layer supports various topologies such star, clustered tree topology and self
healing mesh topology. Apart from easy installation and easy implementation ZigBee
has a wide application area such as home networking, industrial networking, many
more having different profiles specified for each field. The upcoming of ZigBee will
revolutionize the home networking and rest of the wireless world.
Introduction:
ZigBee is an established set of specifications for wireless personal area networking
(WPAN), i.e. digital radio connections between computers and related devices.
WPAN Low Rate or ZigBee provides specifications for devices that have low data
rates, consume very low power and are thus characterized by long battery life.
ZigBee makes possible completely networked homes where all devices are able to
communicate and be controlled by a single unit.
ZigBee is a low-cost, low-power, wireless mesh networking standard. First, the low
cost allows the technology to be widely deployed in wireless control and monitoring
applications. Second, the low power-usage allows longer life with smaller batteries.
Third, the mesh networking provides high reliability and more extensive range.
ZigBee is designed for wireless controls and sensors. It could be built into just about
anything you have around your home or office, including lights,switches, doors and
appliances. These devices can then interact without wires, and you can control them
all . . . from a remote control or even your mobile phone.Although ZigBee's
underlying radio-communication technology isn't revolutionary, it goes well beyond
single-purpose wireless devices, such as garage door openers and "The Clapper" that
turns light on and off. It allows wireless two-way communications between lights and
switches, thermostats and furnaces, hotel-room air-conditioners and the front desk,
and central command posts. It travels across greater distances and handles many
sensors that can be linked to perform different tasks.
Zigbee Alliance
The ZigBee Alliance is an association of companies working together to enable
reliable, cost-effective, and low-power wirelessly networked monitoring and control
products based on an open global standard.
Origin of ZigBee name
The name of the brand is originated with reference to the behaviour of honey bees
after their return to the beehive.
Zigbee characteristics
The focus of network applications under the IEEE 802.15.4 / ZigBee standard include
the features of low power consumption, needed for only two major modes (Tx/Rx or
Sleep), high density of nodes per network, low costs and simple implementation. These
features are enabled by the following characteristics (technical data from ZigBee:
'Wireless Control That Simply Works') :

• 2.4GHz and 868/915 MHz dual PHY modes. This represents three license-free bands:
2.4-2.4835 GHz, 868-870 MHz and 902-928 MHz. The number of channels allotted to
each frequency band is fixed at sixteen (numbered 11-26), one (numbered 0) and ten
(numbered 1-10) respectively. The higher frequency band is applicable worldwide, and
the lower band in the areas of North America, Europe, Australia and New Zealand .
• Low power consumption, with battery life ranging from months to years. Considering
the number of devices with remotes in use at present, it is easy to see that more numbers
of batteries need to be provisioned every so often, entailing regular (as well as timely),
recurring expenditure. In the ZigBee standard, longer battery life is achievable by either
of two means: continuous network connection and slow but sure battery drain, or
intermittent connection and even slower battery drain.
• Maximum data rates allowed for each of these frequency bands are fixed as 250 kbps
@2.4 GHz, 40 kbps @ 915 MHz, and 20 kbps @868 MHz.
• High throughput and low latency for low duty-cycle applications (<0.1%)
• Channel access using Carrier Sense Multiple Access with Collision Avoidance
(CSMA - CA)
• Addressing space of up to 64 bit IEEE address devices, 65,535 networks
• 50m typical range
• Fully reliable “hand-shaked” data transfer protocol.
• Different topologies as illustrated below: star, peer-to-peer, mesh
• Band – 868, 902-928MHz, and 2.4GHz
• Topology – Ad-hoc, Star, Point to Point, Mesh
• Data Rate – 20/40Kb/s and 250Kb/s
• Power Consumption – Very Low
• Range – 10-100+ meters
• Security – very high; AES-128 level encryption
• Size – up to 64K nodes in a single logical network
Device Types
There are three different ZigBee device types .These devices have 64-bit IEEE
addresses, with option to enable shorter addresses to reduce packet size, and work in
either of two addressing modes – star and peer-to-peer.
1. The ZigBee(PAN) coordinator node :
There is one, and only one, ZigBee coordinator in each network to act as the
router to other networks, and can be likened to the root of a (network) tree. It is
designed to store information about the network.
2. The full function device FFD :
The FFD is an intermediary router transmitting data from other devices. It
needs lesser memory than the ZigBee coordinator node, and entails lesser
manufacturing costs. It can operate in all topologies and can act as a
coordinator.
3. The reduced function device RFD :
This device is just capable of talking in the network; it cannot relay data from
other devices. Requiring even less memory, (no flash, very little ROM and
RAM), an RFD will thus be cheaper than an FFD. This device talks only to a
network coordinator and can be implemented very simply in star topology

Reply
seminar class
Active In SP
**

Posts: 5,361
Joined: Feb 2011
#12
24-03-2011, 04:23 PM


.doc   zigbee.doc (Size: 993 KB / Downloads: 47)
1. INTRODUCTION
ZigBee is an established set of specifications for wireless personal area
networking (WPAN). WPAN Low Rate or ZigBee provides specifications for devices
that have low data rates, consume very low power and are thus characterized by long
battery life. ZigBee makes possible completely networked homes where all devices are
able to communicate and be controlled by a single unit.
When you hold the TV remote and wish to use it you have to necessarily point
your control at the device. This one-way, line-of-sight, short-range communication uses
infrared (IR) sensors to enable communication and control and it is possible to operate
the TV remotely only with its control unit. Add other home theatre modules, an airconditioner
and remotely enabled fans and lights to your room, and you become a
juggler who has to handle not only these remotes, but also more numbers that will
accompany other home appliances you are likely to use.
Some remotes do serve to control more than one device after memorizing' access
codes, but this interoperability is restricted to LOS, that too only for a set of related
equipment, like the different units of a home entertainment system.
Now picture a home with entertainment units, security systems including fire
alarm, smoke detector and burglar alarm, air-conditioners and kitchen appliances all
within whispering distance from each other and imagine a single unit that talks with all
the devices, no longer depending on line-of-sight, and traffic no longer being one-way.
This means that the devices and the control unit would all need a common
standard to enable intelligible communication. ZigBee is such a standard for embedded
application software and has been ratified in late 2004 under IEEE 802.15.4 Wireless
Networking Standards.
This kind of network eliminates use of physical data buses like USB and Ethernet
cables. The devices could include telephones, hand-held digital assistants, sensors and
controls located within a few meters of each other.
2. ARCHITECTURE
ZigBee stack architecture is made up of a set of blocks called layers. Each layer
performs a specific set of services for the layer above: a data entity provides a data
transmission service and a management entity provides all other services. Each service
entity exposes an interface to the upper layer through a service access point (SAP), and
each SAP supports a number of service primitives to achieve the required functionality.
The ZigBee stack architecture, which is depicted in figurel below, is based on the
standard Open Systems Interconnection (OSI) seven-layer model but defines only those
layers relevant to achieving functionality in the intended market space. The IEEE
802.15.4-2003 standard defines the lower two layers:
• The physical (PHY) layer
• Medium access control (MAC) sub-layer.
The ZigBee Alliance builds on this foundation by providing the network (NWK)
layer and the framework for the application layer, which includes the application
support sub-layer (APS), the ZigBee device objects (ZDO) and the manufacturer
defined application objects.
IEEE 802.15.4-2003 has two PHY layers that operate in two separate frequency
ranges: 868/915 MHz and 2.4 GHz. The lower frequency PHY layer covers both the
868 MHz European band and the 915 MHz band that is used in countries such as the
United States and Australia. The higher frequency PHY layer is used virtually
worldwide.
The IEEE 802.15.4-2003 MAC sub-layer controls access to the radio channel
using a CSMA-CA mechanism. Its responsibilities may also include transmitting
beacon frames, synchronization and providing a reliable transmission mechanism.
The responsibilities of the ZigBee NWK layer shall include mechanisms used to
join and leave a network, to apply security to frames and to route frames to their
intended destinations. In addition, the discovery and maintenance of routes between
devices devolve to the NWK layer. The NWK layer of a ZigBee coordinator is
responsible for starting a new network, when appropriate, and assigning addresses to
newly associated devices.
The ZigBee application layer consists of the APS, the Application Framework
(AF), the ZDO and the manufacturer-defined application objects. The responsibilities of
the APS sub-layer include maintaining tables for binding, which is the ability to match
two devices together based on their services and their needs, and forwarding messages
between bound devices. The responsibilities of the ZDO include defining the role of the
device within the network (e.g., ZigBee coordinator or end device), initiating and/or
responding to binding requests and establishing a secure relationship between network
devices. The ZDO is also responsible for discovering devices on the network and
determining which application services they provide.
3. DEVICE TYPES
There are three different types of ZigBee device:
• ZigBee coordinator (ZC): The most capable device, the coordinator forms the root
of the network tree and might bridge to other networks. There is exactly one ZigBee
coordinator in each network. It is able to store information about the network, including
acting as the repository for security keys.
• ZigBee Router (ZR): Routers can act as an intermediate router, passing data from
other devices.
• ZigBee End Device (ZED): Contains just enough functionality to talk to its parent
node (either the coordinator or a router); it cannot relay data from other devices. It
requires the least amount of memory, and therefore can be less expensive to
manufacture than a ZR or ZC.
4. MESSAGING
The three messaging modes are:
1.Direct addressing.
2.Indirect addressing.
3. Broadcast addressing.
4.1 DIRECT ADRESSING
Direct addressing assumes device discovery and service discovery have identified
a particular device and endpoint, which supply a complementary service to the
requestor. Specifically, direct addressing defines a means of directing messages to the
device by including its full address and endpoint information. Once devices have been
associated, commands can be sent from one device to another. A command is sent to an
application object at the destination address.
4.2 INDIRECT ADDRESSING
Use of direct addressing requires the controlling device to have knowledge of the
address, endpoint, cluster identifier and attribute identifier of the target device that it
wishes to communicate with and to have this information committed to a binding table
on the ZigBee coordinator prior to the creation of an indirectly addressed message
between the device pair.
A full IEEE 802.15.4 address amounts to 10 octets (PAN identifier plus 64-bit
IEEE address) and a further octet is required for the endpoint. Extremely simple
devices, such as battery-powered switches, may not want the overhead of storing this
information, nor the software for acquiring this information. For these devices, indirect
addressing will be more appropriate.
In Indirect addressing mode .when a source device wishes to send a command to
a destination, instead of including the address of the destination device (which it does
not know and has not stored), it omits the address and specifies indirect addressing via
the APSDE-SAP. The included source address, source endpoint and cluster identifier in
the indirect addressed message are translated via the binding table to those of the
destination device(s) and the messages are relayed to each indicated destination.
Where a cluster contains several attributes, the cluster identifier is used for
addressing and the attribute identifier is used in the command itself to identify a
particular attribute within the cluster. Attributes are not used in the indirect addressing
mechanism and are treated as a part of the data payload. The applications, however, can
parse and utilize the attributes as defined within their profile.
4.3 BROADCAST ADDRESSING
An application may broadcast messages to all endpoints on a given destination
device. This form of broadcast addressing is called application broadcast. The
destination address shall be the 16-bit network broadcast address and the broadcast flag
shall be set in the APS frame control field. The source shall include the cluster
identifier, profile identifier and source endpoint fields in the APS frame.
5. FRAME FORMAT
This sub-clause specifies the format of the NWK frame (NPDU). Each NWK frame
consists of the following basic components:
 A NWK header, which comprises frame control, addressing and sequencing
information.
 A NWK payload, of variable length, which contains information specific to the
frame type.
5.1 GENERAL NPDU FRAME FORMAT
The NWK frame format is composed of a NWK header and a NWK payload. The
fields of the NWK header appear in a fixed order, however, the addressing and
sequencing fields may not be included in all frames.
Reply
seminar class
Active In SP
**

Posts: 5,361
Joined: Feb 2011
#13
07-04-2011, 04:15 PM


.ppt   ZigBee (3).ppt (Size: 2.1 MB / Downloads: 56)
Introduction
What is Zigbee?

 Technological Standard created for control and sensor networks.
 Based on IEEE 802.15.4 Standard.
 Developed By Zigbee Alliance
Motivation
The ZigBee standard was developed to address the following needs:
• Low cost and secure
• Reliable and self healing
• Flexible and extendable
• Low power consumption
• Easy and inexpensive to deploy
• Global with use of unlicensed radio bands
• Integrated intelligence for network set-up and message routing
The ZigBee Name
 Named for erratic, zig-zagging patterns of bees between flowers
 Symbolizes communication between nodes in a mesh network
 Network components analogous to queen bee, drones, worker bees
IEEE 802.15.4 & ZigBee In Context
IEEE 802.15.4 Overview

 Standard for Low- rate Wireless Personal Area Networks (LR-WPANs)
 Includes features such as low power consumption , high density of nodes per network , low cost and simple implementation
 Uses the unlicensed frequency bands 16 channels at 2.4 GHz , 10 channels at 915 MHz and 1 channel at 868 Mhz.
 Device types- PAN Coordinator , Fully Functional Device , Reduced Functional Device
 Topologies - star , peer-to-peer , cluster-tree
IEEE 802.15.4 PHY(Physical layer)
 Provides interface between MAC Layer and physical radio channel
 Consists of two services PHY data service, PHY management service which form the Physical Layer
Management Entity (PLME)
 Features are activation and deactivation of radio transreciever ,energy detection (ED), Link Quality Indication (LQI), channel selection , Clear Channel Assessment(CCA) and transmitting and receiving packet
• Each Physical Protocol Data Unit(PPDU) consists of Physical header , Synchronisation header and a variable payload
IEEE 802.15.4 MAC
 Interface between System Specific Convergence Sublayer (SSCS) and PHY
 Responsible for reliable communication between a node and its neighbours
 Two services MAC data service and MAC management service forming MAC Layer Management Entity
 MAC data service enables transmission and reception of MAC Data Protocol Units (MPDU)
 Features are beacon management , channel access , GTS management

Reply
seminar class
Active In SP
**

Posts: 5,361
Joined: Feb 2011
#14
11-04-2011, 02:50 PM


.ppt   zigbee.ppt (Size: 2.19 MB / Downloads: 56)
What is ZigBee?
 Technological Standard Created for Control and Sensor Networks
 The 802 Wireless Space
 ZigBee and Other Wireless Technologies
ZigBee Aims Low
 Low data rate
 Low power consumption
 Small packet devices
ZigBee Frequencies
 Operates in Unlicensed Bands
 ISM 2.4 GHz Global Band at 250kbps
 868 MHz European Band at 20kbps
 915 MHz North American Band at 40kbps
What Does ZigBee Do?
 Designed for wireless controls and sensors
 Operates in Personal Area Networks (PAN’s) and device-to-device networks
 Connectivity between small packet devices
 Control of lights, switches, thermostats, appliances, etc.
How ZigBee Works
 Topology
– Star
– Cluster Tree
– Mesh
 Network coordinator, routers, end devices
How ZigBee Works
 States of operation
– Active
– Sleep
 Devices
– Full Function Devices (FFD’s)
– Reduced Function Devices (RFD’s)
 Modes of operation
– Beacon
– Non-beacon
ZigBee Mesh Networking
ZigBee and the Hype Cycle

 Research in ZigBee
 The IEEE 802.15.4 standard was completed in May 2003.
 The ZigBee specifications were ratified on 14 December 2004.
 The ZigBee Alliance announced public availability of Specification 1.0 on 13 June 2005.
 Much research is still going on with ZigBee.
 Academic Research
Research in ZigBee is being conducted in different fields:
 Wireless and sensor networks
 Wireless communications
 Neuroengineering
 Research Papers
 Time Synchronization for ZigBee Networks
 ZigBee: “Wireless Control That Simply Works”
 Journal of Neuroengineering and Rehabilitation
 Development of Ubiquitous Sensor Network
 Wireless Technologies for Data Acquisition Systems
ZigBee and the Market
 The next big thing
 Expected to hit the market full force in 2009
 Companies have already invested millions
ZigBee Products
 Development Kits
 Sensors
 Transceivers
 Modules
Current ZigBee Uses
 Environmental Monitoring
 Agricultural Monitoring
 Home Automation Still on Horizon
 Product Applications
 Road map products-tracking
 Consumer electronics
 PC
 Personal and healthcare
 Commercial and residential control
ZigBee’s Future
ZigBee Product Companies

 Helicomm
 MaxStream
 Luxoft Labs
 Crossbow Technology
 Innovative Wireless Technologies
Reply
seminar class
Active In SP
**

Posts: 5,361
Joined: Feb 2011
#15
12-04-2011, 03:50 PM


.doc   SSZIGBEE.doc (Size: 266.58 KB / Downloads: 41)
1. ABSTRACT
ZigBee is a new wireless technology developed by the ZigBee Alliance to overcome the limitations of BLUETOOTH and Wi-Fi. ZigBee is developed on the top of IEEE 802.15.4 standard. It is designed for low-power consumption allowing batteries to essentially last forever. Though we have couple of methods for multimedia applications, till now nothing has been developed for sensor networking and control machines which require longer battery life and continuous working without human intervention. ZigBee devices allow batteries to last up to years using primary cells (low cost) without any chargers (low cost and easy installation).
The ZigBee standard provides network, security, and application support services operating on top of the IEEE 802.15.4.IEEE 802.15.4 standard has two basic layers medium Access Control (MAC) and Physical Layer (PHY) wireless standard. The network layer supports various topologies such star, clustered tree topology and self healing mesh topology. Apart from easy installation and easy implementation ZigBee has a wide application area such as home networking, industrial networking, many more having different profiles specified for each field. The upcoming of ZigBee will revolutionize the home networking and rest of the wireless world.
2. INTRODUCTION
The cellular network was a natural extension of the wired telephony network that became persistent during the mid-20th century. As the need for mobility and the cost of laying new wires increased, the motivation for a personal connection independent of location to that network also increased. Coverage of large area is provided through (1-2km) cells that co-operate with their neighbors to create a seamless network. Cellular standards basically aimed at facilitating voice communications throughout a metropolitan area. During the mid-1980s, it turned out that an even smaller coverage area is needed for higher user densities and the emergent data traffic. The IEEE 802.11 working group for Wireless Local Area Network (WLAN) is formed, to create a wireless local area network standard. Whereas IEEE 802.11 was concerned with features such as Ethernet matching speed, long range(100m), complexity to handle seamless roaming, message forwarding, and data throughput of 2-11Mbps. Wireless personal area networks (WPANs) are used to convey information over relatively short distances. WPANs are focused on a space around a person or object that typically extends up to 10m in all directions. The focus of WPANs is low-cost, low power, short range and very small size. The IEEE 802.15 working group is formed in 1998 to create WPAN standard. This group has currently defined three classes of WPANs that are differentiated by data rate, battery drain and quality of service (QoS).
 The high data rate WPAN (IEEE 802.15.3) is suitable for multi-media applications that require very high QoS.
 Medium rate WPANs (IEEE 802.15.1/Bluetooth) will handle a variety of tasks ranging from cell phones to PDA communications and have QoS suitable for voice communications.
 The low rate WPANs (IEEE 802.15.4/LR-WPAN) is intended to serve a set of industrial, residential and medical applications with very low power consumption, with relaxed needs for data rate and QoS.
3. HISTORY OF ZIGBEE
 October 2002
ZigBee Alliance is formed
 December 2004
ZigBee 1.0 is released
 Current releases
IEEE 802.15.4 standard in 2006
ZigBee specification in 2007
3.1 ZigBee Alliance
The ZigBee Alliance is an association of companies working together to enable reliable, cost-effective, low-power, wirelessly networked, monitoring and control products based on an open global standard.
The goal of the ZigBee Alliance is to provide the consumer with ultimate flexibility, mobility, and ease of use by building wireless intelligence and capabilities into every day devices. ZigBee technology will be embedded in a wide range of products and applications across consumer, commercial, industrial and government markets worldwide. For the first time, companies will have a standards-based wireless platform optimized for the unique needs of remote monitoring and control applications, including simplicity, reliability, low-cost and low-power.
3.2 Why is it called Zigbee?
It has been suggested that the name evokes the haphazard paths that bees follow as they harvest pollen, similar to the way packets would move through a mesh network
Using communication system, whereby the bee dances in a zig-zag pattern, worker bee is able to share information such as the location, distance,
And direction of a newly discovered food source to her fellow colony members. Instinctively implementing the ZigBee Principle, bees around the world actively sustain productive itchiness and promote future generations of Colony members.
3.3 Why do we need Zigbee?
ZigBee is the only standards-based technology that addresses the unique needs of most remote monitoring and control and sensory network applications. The Alliance's members' low cost, low power solutions will enable the broad-based deployment of wireless networks that are able to run for years on standard batteries for a typical monitoring application.
Reply

Important Note..!

If you are not satisfied with above reply ,..Please

ASK HERE

So that we will collect data for you and will made reply to the request....OR try below "QUICK REPLY" box to add a reply to this page

Quick Reply
Message
Type your reply to this message here.


Image Verification
Please enter the text contained within the image into the text box below it. This process is used to prevent automated spam bots.
Image Verification
(case insensitive)

Possibly Related Threads...
Thread Author Replies Views Last Post
  the client/server network strategy can handle very large networks efficiently. jaseelati 0 268 11-12-2014, 02:17 PM
Last Post: jaseelati
  witricity full report project report tiger 28 38,168 30-08-2014, 02:26 AM
Last Post: radiopodarok.ru
  ACCIDENT PREVENTION USING WIRELESS COMMUNICATION full report computer science topics 5 7,602 17-04-2014, 11:07 AM
Last Post: seminar project topic
  silicon on plastic full report computer science technology 2 2,952 13-04-2014, 10:34 PM
Last Post: 101101
  TOPOLOGY CONTROL IN MOBILE AD HOC NETWORKS WITH COOPERATIVE COMMUNICATIONS seminar flower 4 2,323 24-03-2014, 04:35 PM
Last Post: seminar project topic
  Automatic Emergency Light full report seminar class 7 17,594 08-03-2014, 02:28 PM
Last Post: seminar project topic
  ACD-Anti Collision Device full report seminar presentation 11 18,226 10-01-2014, 03:20 PM
Last Post: seminar project topic
  wireless charger full report project topics 21 18,553 10-01-2014, 12:58 PM
Last Post: seminar project topic
  EMBEDDED SYSTEMS full report computer science technology 34 30,027 10-11-2013, 07:51 PM
Last Post: Guest
  wireless charging through microwaves full report project report tiger 106 74,752 22-10-2013, 01:40 PM
Last Post: Guest