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FIXED AND MOBILE WIMAX
Within the last two decades, communication advances have reshaped the way we live our daily lives. Wireless communications has grown from an obscure, unknown service to an ubiquitous technology that serves almost half of the people on Earth. Whether we know it or not, computers now play a dominant role in our daily activities, and the Internet has completely reoriented the way people work, communicate, play, and learn. However severe the changes in our lifestyle may seem to have been over the past few years, the convergence of wireless with the Internet is about to unleash a change so dramatic that soon wireless ubiquity will become as pervasive as paper and pen. WiMaxâ€ which stands for Worldwide Interoperability for Microwave Accessâ€is about to bring the wireless and Internet revolutions to portable devices across the globe. Just as broadcast television in the 1940â„¢s and 1950â„¢s changed the world of entertainment, advertising, and our social fabric, WiMax is poised to broadcast the Internet throughout the world, and the changes in our lives will be dramatic. In a few years, WiMax will provide the capabilities of the Internet, without any wires, to every living room, portable computer, phone, and handheld device.
In its simplest form, WiMax promises to deliver the Internet throughout the globe, connecting the last mile of communications services for both developed and emerging nations.
LIST OF ACRONYMS
ARQ: Automatic Repeat Request. In case of errors in a transmitted packet or anon received packet retransmission will occur.
ATM: Asynchronous Transfer Mode
BRAS: Broadband Remote Access Server
BS: Base Station
BWA: Broadband Wireless Access. Enabling high-speed broadband connections the air instead of over wired (fixed) connections
CDMA: Code Division Multiple Access
CPE: Customer Premises Equipment
DHCP: Dynamic Host Configuration Protocol
DSL: Digital Subscriber Line
DSLAM: DSL Access Multiplexer
EIRP: Effective Isotropic Radiated Power
ETSI: European Telecommunications Standards Institute
EUL: Enhanced Up Link,
FDD: Frequency Division Duplex
GPRS: General Packet Radio Service
GSM: Global System for Mobile communication
HSPA: High Speed Packet Access, refers to both downlink (HSDPA) and uplink
HSDPA: High Speed Downlink Packet Access
HSUPA: High Speed Uplink Packet Access, same as EUL
IEEE: Institution for Electrical and Electronics Engineers. Standardization body.
IMT-2000: International Mobile Telecommunications-2000 (IMT-2000)
IMS: IP Multimedia Subsystem
IP: Internet Protocol
ITU: International Telecommunication Union.
MAC: Medium Access Control
MAN: Metropolitan Area Network
MTBF: Mean Time Between Failure
NAT: Network Address Translation. Used to expand the addressing capabilities of
OFDM: Orthogonal Frequency Division Multiplexing
PDA: Personal Digital Assistant
PHY: Physical Layer
Prosumers: Professionals and enterprise users/subscribers
PSTN: Public Switched Telephone Network
QoS: Quality of Service
RF: Radio Frequency
SGSN: Serving GPRS Support Node
SIP: Simple Internet Protocol
SME: Small and Medium size Enterprises
SoHo: Small Office Home Office
SS: Subscriber Station
STC: Space-Time Codes
TCO: Total Cost of Ownership
TDD: Time Division Duplex
TDM: Time Division Multiplexing
TDMA: Time-Division Multiple Access
Users: Consumers, presumes, end-users and subscribers
VDSL: Very high bitrate DSL
VoIP: Voice over Internet Protocol technology enables users to transmit voice calls via
the Internet using packet-linked routes.
WCDMA: Wideband Code Division Multiple Access
WiFi: Wireless Fidelity, or Wireless Local Area Network, WLAN
WiMAX: World-wide interoperability for Microwave Access
WISP: Wireless Internet Service Provider
CHAPTER â€œ 1
Broadband wireless sits at the confluence of two of the most remarkable growth stories of the telecommunications industry in recent years. Both wireless and broadband have on their own enjoyed rapid mass-market adoption. Wireless mobile services grew from 11 million subscribers worldwide in 1990 to more than 2 billion in 2005 . During the same period, the Internet grew from being a curious academic tool to having about a billion users.
This staggering growth of the Internet is driving demand for higher-speed Internet-access services, leading to a parallel growth in broadband adoption. In less than a decade, broadband subscription worldwide has grown from virtually zero to over 200 million . Will combining the convenience of wireless with the rich performance of broadband be the next frontier for growth in the industry Can such a combination be technically and commercially viable Can wireless deliver broadband applications and services that are of interest to the end-users Many industry observers believe so. Before we delve into broadband wireless, let us review the state of broadband access today. Digital subscriber line (DSL) technology, which delivers broadband over twisted-pair telephone wires, and cable modem technology, which delivers over coaxial cable TV plant, is the predominant mass-market broadband access technologies today. Both of these technologies typically provide up to a few megabits per second of data to each user, and continuing advances are making several tens of megabits per second possible. Since their initial deployment in the late 1990s, these services have enjoyed considerable growth. The United States has more than 50 million broadband subscribers, including more than half of home Internet users. Worldwide, this number is more than 200 million today and is project and implimentationed to grow to more than 400 million by 2010 . The availability of a wireless solution for broadband could potentially accelerate this growth. What are the applications that drive this growth
Broadband users worldwide are finding that it dramatically changes how we share information, conduct business, and seek entertainment. Broadband access not only provides faster Web surfing and quicker file downloads but also enables several
multimedia applications, such as real-time audio and video streaming, multimedia conferencing, and interactive gaming. Broadband connections are also being used for voice telephony using voice-over-Internet Protocol (VoIP) technology.
Worldwide subscriber growth 1990â€œ2006 for mobile telephony, Internet usage, and broadband access
More advanced broadband access systems, such as fiber-to-the-home (FTTH) and very high data rate digital subscriber loop (VDSL), enable such applications as entertainmentquality video, including high-definition TV (HDTV) and video on demand (VoD). As the broadband market continues to grow, several new applications are likely to emerge, and it is difficult to predict which ones will succeed in the future. So what is broadband wireless Broadband wireless is about bringing the broadband experience to a wireless context, which offers users certain unique benefits and convenience. There are two fundamentally different types of broadband wireless services. The first type attempts to provide a set of services similar to that of the traditional fixedline broadband but using wireless as the medium of transmission. This type, called fixed wireless broadband, can be thought of as a competitive alternative to DSL or cable modem. The second type of broadband wireless, called mobile broadband, offers the additional functionality of portability, nomadicity,1 and mobility.
Mobile broadband attempts to bring broadband applications to new user experience scenarios and hence can offer the end user a very different value proposition. WiMax (worldwide interoperability for microwave access) technology,
In many parts of the world, existing fixed-line carriers that do not own cellular, PCS, or 3G spectrums could turn to WiMax for provisioning mobility services. As the industry moves along the path of quadruple-play service bundlesâ€voice, data, video, and mobility â€some service providers that do not have a mobility component in their portfoliosâ€cable operators, satellite companies, and incumbent phone companiesâ€are likely to find WiMax attractive. For many of these companies, having a mobility plan will be not only a new revenue opportunity but also a defensive play to mitigate churn by enhancing the value of their product set. Existing mobile operators are less likely to adopt WiMax and more likely to continue along the path of 3G evolution for higher data rate capabilities. There may be scenarios, however, in which traditional mobile operators may deploy WiMax as an overlay solution to provide even higher data rates in targeted urban centers or metro zones. In addition to higher-speed Internet access, mobile WiMax can be used to provide voiceover- IP services in the future. The low-latency design of mobile WiMax makes it possible to deliver VoIP services effectively. VoIP technologies may also be leveraged to provide innovative new services, such as voice chatting, push-to-talk, and multimedia chatting. New and existing operators may also attempt to use WiMax to offer differentiated personal broadband services, such as mobile entertainment. The flexible channel bandwidths and multiple levels of quality-of-service (QoS) support may allow WiMax to be used by service providers for differentiated high-bandwidth and low-latency entertainment applications. For example, WiMax could be embedded into a portable gaming device for use in a fixed and mobile environment for interactive gaming. Other examples would be streaming audio services delivered to MP3 players and video services delivered to portable media players. As traditional telephone companies move into the entertainment area with IP-TV (Internet Protocol television), portable WiMAX could be used as a solution to extend applications and content beyond the home.
The WiMax standard has been developed with many objectives in mind. These are
Flexible Architecture: WiMax supports several system architectures, including Point-to-Point, Point-to-Multipoint, and ubiquitous coverage. The WiMax MAC (Media Access Control) supports Point-to-Multipoint and ubiquitous service by scheduling a time slot for each Subscriber Station (SS). If there is only one SS in the network, the WiMax Base Station (BS) will communicate with the SS on a Point-to-Point basis. A BS in a Point-to-Point configuration may use a narrower beam antenna to cover longer distances.
High Security: WiMax supports AES (Advanced Encryption Standard) and 3DES (Triple DES, where DES is the Data Encryption Standard). By encrypting the links between the BS and the SS, WiMax provides subscribers with privacy (against eavesdropping) and security across the broadband wireless interface. Security also provides operators with strong protection against theft of service. WiMax also has built-in VLAN support, which provides protection for data that is being transmitted by different users on the same BS.
Quick Deployment: Compared with the deployment of wired solutions, WiMax requires little or no external plant construction. For example, excavation to support the trenching of cables is not required. Operators that have obtained licenses to use
one of the licensed bands, or that plan to use one of the unlicensed bands, do not need to submit further applications to the Government. Once the antenna and equipment are installed and powered, WiMax is ready for service. In most cases, deployment of WiMax can be completed in a matter of hours, compared with months for other solutions.
Multi-Level Service: The manner in which QoS is delivered is generally based on the Service Level Agreement (SLA) between the service provider and the end-user. Further, one service provider can offer different SLA s to different subscribers, or even to different users on the same SS.
Interoperability: WiMax is based on international, vendor-neutral standards, which make it easier for end-users to transport and use their SS at different locations, or with different service providers. Interoperability protects the early investment of an operator since it can select equipment from different equipment vendors, and it will continue to drive the costs of equipment down as a result of mass adoption.
Portability: As with current cellular systems, once the WiMax SS is powered up, it identifies itself, determines the characteristics of the link with the BS, as long as the SS is registered in the system database, and then negotiates its transmission characteristics accordingly.
Mobility: The IEEE 802.16e amendment has added key features in support of mobility. Improvements have been made to the OFDM and OFDMA physical layers to support devices and services in a mobile environment. These improvements, which include Scaleable OFDMA, MIMO, and support for idle/sleep mode and hand-off, will allow full mobility at speeds up to 160 km/hr.
Cost-effective: WiMax is based on an open, international standard. Mass adoption of the standard, and the use of low-cost, mass-produced chipsets, will drive costs down dramatically, and the resultant competitive pricing will provide considerable cost savings for service providers and end-users.
Wider Coverage: WiMax dynamically supports multiple modulation levels, including BPSK, QPSK, 16-QAM, and 64-QAM. When equipped with a highpower amplifier and operating with a low-level modulation (BPSK or QPSK, for
example),WiMax systems are able to cover a large geographic area when the path between the BS and the SS is unobstructed.
Non-Line-of-Sight Operation: NLOS usually refers to a radio path with its first Fresnel zone completely blocked. WiMax is based on OFDM technology, which has the inherent capability of handling NLOS environments. This capability helps WiMax products deliver broad bandwidth in a NLOS environment, which other wireless product cannot do.
High Capacity: Using higher modulation (64-QAM) and channel bandwidth(currently 7 MHz, with planned evolution towards the full bandwidth specified in the standards), WiMax systems can provide significant 1.4 Organization. The report is organized into five chapters.
Chapter 1 Deals with the introduction part of the report. It provides the background information necessary for understanding WiMax. Provides a brief introduction of broadband wireless, necessity of WiMax & its objectives.
Chapter 2 Deals with literature review of WiMax (related information available in standard books, journals ,internet websites etc.)
Chapter 3 Deals with the System development of WiMax . For example IEEE 802.16, IEEE 802.16a, WiMax vs. WLAN, WiMax Vs. WiFi, HIPERMAN, Mesh Networks, Wireless Services, WiMax Infrastructure, End-to-End WiMax Architecture, WiMax Protocol, Mobile WiMax and Advanced Features of WiMax.
Chapter 4 Deals with the Performance Analysis of WiMax .This chapter shows Markets for WiMax, Current Status of WiMax, The WiMax Scenario, and WiMax versus 3G and Wi-Fi & Competing technologies.
Chapter 5 Deals with the Conclusion , future scope & Applications of WiMax
CHAPTER - 2
Zakhia Abichar, Yanlin Peng, and J. Morris Chang in 2006 shows WiMax: The Emergence of Wireless Broadband The much-anticipated technology of WIMax,the Worldwide Interoperability for Microwave Access, aims to provide business and consumer wireless broadband services on the scale of the Metropolitan Area Network (MAN).WiMax will bring a standards- based technology to a sector that otherwise depended on proprietary solutions.The technology has a target range of up to 31 miles and a target transmission rate exceeding 100 Mbps and is expected to challenge DSL and T1 lines (both expensive technologies to deploy and maintain) especially in emerging markets.
Dusit Niyato and Ekram Hossain in 2007 shows Integration of WiMax and WiFi Broadband wireless access networks based on WiMax can provide backhaul support for mobile WiFi hotspots. We consider an integrated WiMax/WiFi network for such an application where the licensed WiMax spectrum is shared by the WiFi access points/routers to provide Internet connectivity to mobile WiFi users. The WiMax backbone network and WiFi hotspots are operated by different service providers. Issues such as protocol adaptation, quality of service support, and pricing for bandwidth sharing that are related to integration of these networks are discussed. In addition, they propose a model for optimal pricing for bandwidth sharing in an integrated WiMax/WiFi network
Chizu Fukao Jun in 2007 Study on the Detection Scheme of WiMax signal for DAA Operation in MB-OFDM. In the first, by comparing the power 1-3 of the WiMax signal derived from the FFT outputs of the MB-OFDM receiver with the background noise, power detection scheme is performed. And using the central limit L theorem, Correlation detection comparing power detection scheme. It was confirmed that this scheme has much better performance than the power detection scheme under low signal to noise ratio situation. Therefore, it references is considered that the use of the guard interval information "Ultra-Wide Bandwidth
-Time of WiMax signal is very effective for the detection of the Hopping Spread- Spectrum Impulse Radio for Wireless Multiple-Access Communications signal
- Kejie Lu and Yi Qian in 2007 shows a Secure and Service-Oriented Network Control Framework for WiMax Networks, Worldwide Interoperability for Microwave Access, is an emerging wireless communication system that can provide broadband access with large-scale coverage. As a cost-effective solution, multihop communication is becoming more and more important to WiMax systems. To successfully deploy multihop WiMax networks, security is one of the major challenges that must be addressed. Another crucial issue is how to support different services and applications in WiMax networks. Since WiMax is a relatively new standard, very little work has been presented in the literature. In this article we propose a secure and service-oriented network control framework for WiMax networks. In the design of this framework we consider both the security requirements of the communications and the requirements of potential WiMax applications that have not been fully addressed previously in the network layer design. The proposed framework consists of two basic components: a serviceaware control framework and a unified routing scheme. Besides the design of the framework, we further study a number of key enabling technologies that are important to a practical WiMax network. Our study can provide a guideline for the design of a more secure and practical WiMax network.
-A Joon Ho Park, Mingji Ban in 2008 Designed Mobile WiMax System for Military Applications and Its Performance in Fading Channels The IEEE 802.16e mobile WiMax system may not be quite suitable in some applications where the uplink (UL) requires higher transmission rate than the downlink (DL). In particular, many cases in military applications often require higher transmission rate in the uplink. Proposal for a new mobile WiMax scheme that provides the DL to UL ratio (DUR) to be 9:33 by modify the frame structure. Fading channels for the modified mobile WiMax system are presented. They evaluate the bit error rate (BER) performance and compare the throughput at the different DUR. The IEEE 802.16e mobile WiMax system may not be quite suitable in some applications
where the uplink (UL) requires higher transmission rate than the downlink (DL). In particular, many cases in military applications often require higher transmission rate in the uplink. In this paper, they propose a new mobile WiMax scheme that provides the DL to UL ratio (DUR) to be 9:33 by modify the frame structure. Fading channels for the modified mobile WiMax system are presented. They evaluate the bit error rate (BER) performance and compare the throughput at the different DUR.
-D. J. Shyy Jamie Mohamed in 2008 designed WIMax RF Planner Fixed WiMax (IEEE 802.16d) is positioned as a wireless broadband alternative to the traditional cable and Digital Subscriber Line (DSL) technologies. Mobile WiMax (IEEE 802.16e) has been chosen as the 3G/4G technology by major mobile/cellular service providers around the globe. Many Government organizations are also interested in the WIiMax technologies. We have built a WIMax RF Planner, a WiMax cell planning tool. The WiMax RF Planner incorporates all the standard features of commercial RF planning tools with additional features tailored for government requirements including: support of base station mobility as well as interfacing to WiMax radios, OPNET and Google Earth.
-Rajeshree Raut in 2008 presented Codec Design for WiMax System Wireless communication is the fastest growing segment of the communication industry. New services are being added and data is provided at higher bit rates to the end users. With these advancements any communication system has to critically consider data integrity. This requires, maintaining a lower bit error rate. Present work focuses on the Broadcast Wireless Access standard named WiMax (Worldwide Interoperability for Microwave Access). Possible options for maintaining a lower bit error rate in WiMax System are worked out. In particular a Novel Approach which uses a concatenation of RS and Turbo Codes for the Codec design in The WiMax Communication System is presented. The paper also discusses use of OQPSK Modulation Technique in place of the conventional QPSK system, for performance improvement. The comparative simulation results of existing WiMax System and the system using the novel approach are also provided. These results are used to draw useful conclusions for reducing the bit
- Lang Wei-min in 2008 proposed a simple Key Management Scheme based on WiMax WiMax security has two goals, one is to provide privacy across the wireless network and the other is to provide access control to the network. The security sub-layer of IEEE 802.16 employs an authenticated client/server key management protocol in which the BS, the server, controls the distribution of keying material to the client SS. This paper analyzes the physical layer threat and MAC layer threat of WiMax, and then lists the security requirements of a WiMax system. Furthermore, they propose the security architecture of WiMax and the key management scheme from the aspects of Authorization Key (AK) exchange, TEK exchange and AK management. In conclusion, this paper gives the security issues and countermeasures in WiMax system.
- Sassan Ahmadi in 2009 present an Overview of Next-Generation Mobile WiMax Technology The IEEE 802.16m is designed to provide state of-the-art mobile broadband wireless access in the next decade and to satisfy the growing demand for advanced wireless WiMax profile are expected to be completed by2011. Multihop relay architecture, multi-carrier operation, self-configuration, advanced single user/ multi-user multi-antenna schemes and interference mitigation techniques, enhanced multicast-broadcast service, increased VoIP capacity, improved cell-edge user throughput, and support of vehicular speeds up to 500 km/h, and so on are among the most prominent features that would make IEEE 802.16m one of the most successful and advanced broadband wire time applications and services.
- Steven J. Vaughan in 2009 proposed Mobile WiMax The Next Wireless Battleground The IEEE plans to adopt mobile WiMax 2.0â€formally called IEEE 802.16m. The technology would offer data rates of 100 Mbps for mobile uses and 1 Gbps for fixed applications via enhanced MIMO technology. If adopted on schedule, industry observers expect mobile WiMax 2.0 to appear in products by 2012
- Jarno Pinola and Kostas Pentikousis in 2009 proposed IPTV over WiMax with MIPv6 Handovers As the IPv4 unallocated address pool nears exhaustion, an increasing number of IPv6 deployments is anticipated. In the domain of mobility management research and development, Mobile IPv6 has long been favored over Mobile IPv4. Nevertheless, although in principle WiMax supports IPv6 in various configurations and requires MIPv6 for network-level mobility management, in practice, vendors are actively deploying these capabilities only in part. They provide a thorough review of the role of IPv6 and MIPv6 in WiMax networks, surveying the work in relevant standardization bodies. The second contribution of is a test bed evaluation of IPTV streaming over WiMax. They employ two WiMax test beds deployed in Finland and Portugal, interconnected by GEANT and Quantify MIPv6 performance in a real-time multimedia streaming scenario over WiMax. Beyond demonstrating the feasibility of such a deployment, their results indicate that WiMax can provide a viable option as both access and backhauling technology.
- Yue Li1 & Demetres Kouvatsos in 2009 shows Performance Modeling and Bandwidth Management of WiMax Systems Worldwide Interpretability for Microwave Access is a competitive connection oriented technology for metropolitan broadband wireless access with very high data rate, large service coverage and flexible quality of service (QoS). Due to the large number of connections, the efficient bandwidth management and related channel allocation for the uplink access in WiMax networks is a very challenging task of the medium access control (MAC) protocol. In order to provide better bandwidth utilization and network throughput, a cost-effective WiMax bandwidth management scheme is devised, named as the WiMax partial sharing scheme (WPSS) and compared against a simpler scheme, named as the WiMax complete sharing scheme (WCPS). An analytic maximum entropy (ME) model is proposed for the cost-effective performance evaluation of the two bandwidth management schemes associated with networks with a large number of stations and/or the connections. In this context, an open queuing network model (QNM) is devised,
3.1. IEEE 802.16
The IEEE 802.16 Working Group is the IEEE group for wireless metropolitan area network. The IEEE 802.16 standard defines the Wireless MAN (metropolitan area network) air interface specification (officially known as the IEEE Wireless MAN standard). This wireless broadband access standard could supply the missing link for the last mile connection in wireless metropolitan area networks. Wireless broadband access is set up like cellular systems, using base stations that service a radius of several miles/kilometers. Base stations do not necessarily have to reside on a tower. More often than not, the base station antenna will be located on a rooftop of a tall building or other elevated structure such as a grain silo or water tower. A customer premise unit, similar to a satellite TV setup, is all it takes to connect the base station to a customer. The signal is then routed via standard Ethernet cable either directly to a single computer, or to an 802.11hot spot or a wired Ethernet LAN.
The IEEE 802.16 designed to operate in the 10-66 GHz spectrum and it specifies the physical layer (PHY) and medium access control layer (MAC) of the air interface BWA systems. At 10-66 GHz range, transmission requires Line-of-Sight (LOS).IEEE 802.16 is working group number 16 of IEEE 802, specializing in point-to-multipoint broadband wireless access.
The IEEE 802.16 standard provides the foundation for a wireless MAN industry. However, the physical layer is not suitable for lower frequency applications where nonline- of-sight (NLOS) operation is required . For this reason, the IEEE published 802.16a standard to accommodate NLOS requirement in April 2003. The standard operates in licensed and unlicensed frequencies between 2 GHz and 11 GHz, and it is an extension of the IEEE 802.16standard.The IEEE 802.16 Working Group created a new standard, commonly known as WiMax, for broadband wireless access at high speed and low cost, which is easy to deploy, and which provides a scalable solution for extension of a fiber-optic backbone.
WiMax base stations can offer greater wireless coverage of about 5 miles, with LOS (line 12 of sight) transmission within bandwidth of up to 70 Mbps. WiMax is supported by the industry itself, including Intel, Dell, Motorola, Fujitsu, AT&T, British Telecom, France Telecom, Reliance Infocomm, Siemens, Sify,Price Warehouse Coopers and Tata Teleservices â€œ forming an alliance called WiMax Forum. It represents the next generation of wireless networking . WiMAX original release the 802.16standard addressed applications in licensed bands in the 10 to 66 GHz frequency range. Subsequent amendments have extended the 802.16 air interface standard to cover non-line of sight (NLOS) applications in licensed and unlicensed bands in the sub 11 GHz frequency range. Filling the gap between Wireless LANs and wide area networks, WiMAX-compliant systems will provide a cost-effective fixed wireless alternative to conventional wire-line DSL and cable in areas where those technologies are readily available. And more importantly the WiMAX technology can provide a cost-effective broadband access solution in areas beyond the reach of DSL and cable. The ongoing evolution of IEEE 802.16 will expand the standard to address mobile applications thus enabling broadband access directly to WiMAX-enabled portable devices ranging from smart phones and Pads to notebook and laptop computers.
3.2. IEEE 802.16a
The IEEE 802.16a standard allows users to get broadband connectivity without needing direct line of sight with the base station. The IEEE 802.16a specifies three air interface specifications and these options provide vendors with the opportunity to customize their product for different types of deployments. The three physical layer specifications in 802.16a are:
-Wireless MAN-SC which uses a single carrier modulation format.
-Wireless MAN-OFDM which uses orthogonal frequency division multiplexing
(OFDM) with 256 point Fast Fourier Transform (FFT). This modulation is
mandatory for license exempt bands.
-Wireless MAN-OFDMA which uses orthogonal frequency division multiple access (OFDMA) with a 2048 point FFT. Multiple accesses are provided by addressing a subset of the multiple carriers to individual receivers.
In 1998, the IEEE (The Institute of Electrical and Electronics Engineers) began a standards project and implimentation to specify a point-to-multipoint broadband wireless access system suitable for the delivery of data, voice, and video services to fixed customer sites. The initial standard, designated IEEE 802.16, was developed for the higher microwave bands (> 10 GHz) where line-of-sight between system antennas is required for reliable service. Despite the availability of licensed spectrum for potential deployments, completion of the standard in 2001 failed to have a significant impact; most vendors abandoned their proprietary equipment and did not attempt to implement high-frequency multipoint systems based on the 802.16 standard.
Factors beyond equipment cost (e.g., installation, roof rights, backhaul, spectrum costs)
were significant contributors to the poor economics of the high-frequency multipoint
systems. In early 2000, work on a low-frequency (<11 GHz) revision of the 802.16
standard was begun by the IEEE working group. This revision (designated 802.16a)
incorporated new radio link system options more suitable for low-frequency service while
maintaining most of the access control system specifications of the original standard
Completed in January 2000, the 802.16a standard included features supporting:
-Non-line-of-sight service capability
-Multiple radio modulation options (single carrier, OFDM)
-Licensed and unlicensed band implementations
Versatile access control and QoS features, including TDM and packet services, advanced security A corrected and modified version of 802.16a (designated 802.16-REVd) was completed in June 2004. Initial WiMAX profiles are a subset of the 802.16- REVdstandard. A mobile extension to the low-frequency 802.16 standard is now being developed by the IEEE 802.16e working group. This extension will support delivery of broadband data to a moving wireless terminal, such as a laptop computer with an integrated WiMAX modem being used by a passenger on a commuter train. The WiMAX Forum expects to endorse a mobile profile following completion of the 802.16e standard.
3.3. WiMax vs. WLAN
Unlike WLAN, WiMAX provides a media access control (MAC) layer that uses a grant request mechanism to authorize the exchange of data. This feature allows better exploitation of the radio resources, in particular with smart antennas, and independent management of the traffic of every user. This simplifies the support of real-time and voice applications.
One of the inhibitors to widespread deployment of WLAN was the poor security feature of the first releases. WiMAX proposes the full range of security features to ensure secured data exchange:
-Terminal authentication by exchanging certificates to prevent rogue devices,
-User authentication using the Extensible Authentication Protocol (EAP),
-Data encryption using the Data Encryption Standard (DES) or Advanced
Encryption Standard (AES), both much more robust than the Wireless Equivalent Privacy (WEP) initially used by WLAN. Furthermore, each service is encrypted with its own security association and private keys.
3.4. WiMax VS. WiFi
WiMAX operates on the same general principles as WiFi -- it sends data from one computer to another via radio signals. A computer (either a desktop or a laptop) equipped with WiMAX would receive data from the WiMAX transmitting station, probably using encrypted data keys to prevent unauthorized users from stealing access. The fastest WiFi connection can transmit up to 54 megabits per second under optimal conditions. WiMAX should be able to handle up to 70 megabits per second. Even once that70 megabits is split up between several dozen businesses or a few hundred home users, 15 it will provide at least the equivalent of cable-modem transfer rates to each user. The biggest difference isn't speed; it's distance. WiMAX outdistances WiFi by miles. WiFi's range is about 100 feet (30 m). WiMAX will blanket a radius of 30 miles (50 km) with wireless access. The increased range is due to the frequencies used and the power of the transmitter. Of course, at that distance, terrain, weather and large buildings will act to reduce the maximum range in some circumstances, but the potential is there to cover huge tracts of land.
WiMax is not designed to clash with WiFi, but to coexist with it. WiMax coverage is measured in square kilometers, while that of WiFi is measured in square meters. The original WiMax standard (IEEE 802.16) proposes the usage of 10-66 GHz frequency spectrum for the WiMax transmission, which is well above the WiFi range (up to 5GHz maximum). But 802.16a added support for 2-11 GHz frequency also. One WiMax base station can be accessed by more than 60 users. WiMax can also provide broadcasting services also. WiMax specifications also provides much better facilities than WiFi, providing higher bandwidth and high data security by the use of enhanced encryption schemes. WiMax can also provide service in both Line Of Sight (LOS) and Non-Line Of Sight (NLOS) locations, but the range will vary accordingly.
WiMax will allow the interpenetration for broadband service provision of VoIP, video, and internet access â€œ simultaneously. WiMax can also work with existing mobile networks. WiMax antennas can "share" a cell tower without compromising the function of cellular arrays already in place.
The ETSI has created wireless MAN standard for frequency band between 2 GHz and 11GHz. The ETSI Hiperman standard was issued in Nov 2003. The ETSI works closely with the IEEE 802.16 group and the HIPERMAN standard has essentially followed 802.16â„¢s lead.
The Hiperman standard provides a wireless network communication in the 2 â€œ 11 GHz bands across Europe. The Hiperman working group utilizes the 256 point FFT OFDM modulation scheme. It is one of the modulation schemes defined in the IEEE 802.16a standard.
Worldwide Interoperability for Microwave Access (WiMAX) is currently one of the hottest technologies in wireless. The Institute of Electrical and Electronics Engineers 16 (IEEE) 802 committee, which sets networking standards such as Ethernet (802.3) and WiFi (802.11), has published a set of standards that define WiMAX. IEEE 802.16-2004 (also known as Revision D) Was published in 2004 for fixed applications; 802.16 Revision E (which adds mobility) is duplicated in July 2005. The WiMAX Forum is an industry body formed to promote the IEEE 802.16 standard and perform interoperability testing. The WiMAX Forum has adopted certain profiles based on the 802.16 standards for interoperability testing and WiMAX certification.
These operate in the 2.5GHz, 3.5GHz and 5.8GHz frequency bands, which typically are licensed by various government authorities. WiMAX, is based on an RF technology called Orthogonal Frequency Division Multiplexing (OFDM), which is a very effective means of transferring data when carriers of width of 5MHz or greater can be used. Below 5MHz carrier width, current CDMA based 3G systems are comparable to OFDM in terms of performance.
WiMAX is a standard-based wireless technology that provides high throughput broadband connections over long distance. WiMAX can be used for a number of applications, including last mile broadband connections, hotspots and high-speed connectivity for business customers. It provides wireless metropolitan area network (MAN) connectivity at speeds up to 70 Mbps and the WiMAX base station on the average can cover between 5 to 10 km. Figure 3.1. WiMAX Overview.
3.6.1. WiMax Forum
WiMax Forum is a non-profit corporation that was formed in April 2001 by equipment 17 and component suppliers to help to promote and certify the compatibility and interoperability of Broadband Wireless Access (BWA) equipment. As of May 2004, there are over 100 members of WiMax Forum. WiMaxâ„¢s members, which include Air span, Alcatel, Alvarion, Fujitsu, Intel, OFDM Forum, Proxim, Siemens, account for over 75 percent of sales in the 2 to 11 GHz BWA market. The WiMax Forum (the Forum) is a coalition of wireless and computer industry companies that has endorsed and is aggressively marketing the WiMax standard. A principal purpose of the organization is to promote and certify compatibility and interoperability of devices based on the various 802.16 specifications and to develop such devices for the global marketplace. The Forum believes that the adoption of industry standards will be a key factor in any successful deployment of WiMax technology . For example, one of the most significant problems with WiFi initial deployment was the lack of any early industry standards. In the early days of WiFi deployment, the marketplace was saturated with equipment well before industry standards were adopted. As a result, equipment often lacked interoperability and was expensive.
One of the purposes of the WiMax Forum is to create a single interoperable standard from the IEEE and ETSI BWA standards. In order to create a single interoperable standard, WiMax has decided to focus on the 256 FFT OFDM which is common between 802.16a and HIPERMAN. WiMax has developed system profiles covering the popular licenceexempted bands in 2.4 GHz and 5 GHz and other licensed bands in 2.3 GHz, 2.5 GHz and 3.5 GHz. At the moment, WiMax will focus its conformance and interoperability test procedures on equipment that operates in 2.5 GHz and 3.5 GHz licensed bands and 5.8 GHz unlicensed band using 256 FFT OFDM modulation scheme. The flexible channel plan from 1.5 MHz to 20 MHz per channel will be adopted by WiMax. The WiMax Forum strategy has been formed in an attempt to promote high-volume, worldwide adoption of WiMax equipment. Components of the WiMax Forum strategy include:
-Select a workable subset of the many allowed system profiles and variations in the 802.16standard
-Develop a testing and certification process to validate that equipment submitted by
vendors conforms to WiMax certification requirements of standard compliance18 and multi-vendor interoperabilit
-Continue to support IEEE 802.16 standard updates and corrections, including the current mobile enhancement project and implimentation (802.16e) The availability of a standard eliminates the need for the large investment by equipment vendors required to develop and verify basic radio and access control systems from scratch. With volume, equipment costs are further lowered as component makers and system integrators achieve manufacturing efficiencies. Service providers (and ultimately consumers) benefit from the interoperability requirement, as multiple vendors compete for business during initial system build-out, expansion, and evolutionary upgrades. The WiMax Forum timeline (past and project and implimentationed) for standard development, certification testing, and availability of initial WiMax equipment.
3.6.2. WiMax Spectrum â€ Licensed and Unlicensed
As with any other spectrum based technology, successful WiMAX deployment will depend largely upon the availability and suitability of spectrum resources. For entities providing wireless communications services, two sources of spectrum are available:
-Licensed spectrum and
Licensed spectrum requires an authorization/license from the Commission, which offers that individual user or Licensee the exclusive rights to operate on a specific frequency (or frequencies) at a particular location or within a defined geographic area. In contrast, unlicensed spectrum permits any user to access specific frequencies within any geographic area inside the United States without prior Commission authorization. While users of this spectrum do not have to apply for individual licenses or pay to use the spectrum, they are still subject to certain rules. First, unlicensed users must not cause interference to licensed users and must accept any interference they receive. Second, any equipment that will be utilized on unlicensed spectrum must be approved in advance by the Commission. Because of its broad operating range, licensed and unlicensed spectrum options for WiMax technology are extensive. To take best advantage of the benefits provided by WiMax systems, large block spectrum assignments are most desirable. This enables systems to be deployed in TDD mode with large channel bandwidths, flexible frequency re-use and with minimal spectral inefficiencies for guard-bands to facilitate coexistence with adjacent operators.
Another key activity for the WiMax Forum is collaborating with standards and regulatory bodies worldwide to promote the allocation of spectrum in the lower frequency bands (< 6 GHz) that is both application and technology neutral. Additionally, there is a major push for greater harmonization in spectrum allocations so as to minimize the number equipment variants required to cover worldwide The initial system performance profiles that will be developed by the WiMax Forum for the recently approved 802.16-2005 air interface standard are expected to be in the licensed 2.3 GHz, 2.5 GHz and 3.5 GHz frequency bands. The 2.3 GHz band has been allocated in South Korea for WiBro services based on the Mobile WiMax technology. With a 27 MHz block of spectrum assignment to each operator, this band will support a TDD deployment with 3 channels per base station and a nominal channel bandwidth of 8.75 MHz. The 2.5 to 2.7 GHz band is already available for mobile and fixed wireless services in the United States. This band is also currently underutilized and potentially available in many countries throughout South America and Europe as well as some countries in the Asia-Pacific region. The 3.5 GHz band is already allocated for fixed 20 wireless services in many countries worldwide and is also well-suited to WiMax solutions for both fixed and mobile services.
3.7. Mesh Networks
The IEEE 802.16 WiMax standard provides a mechanism for creating multi-hop mesh, which can be deployed as a high speed wide-area wireless network. Beyond just providing a single last hop access to a broadband ISP, WiMax technology can be used for creating wide-area wireless backhaul network. When a backhaul-based WiMax is deployed in Mesh mode, it does not only increase the wireless coverage, but it also provides features such as lower backhaul deployment cost, rapid deployment, and re configurability. Various deployment scenarios include citywide wireless coverage, backhaul for connecting 3G RNC (Radio Network Controller) with base stations, and others. In addition to the single hop IEEE 802.16 PMP (point-to multipoint) operation, IEEE 802.16a standard defined the basic signaling flows and message formats to establish a mesh network connection.
Subsequently, the Mesh mode specifications were integrated into the IEEE 802.16-2004 revision. Although single hop WiMax provides high flexibility to attain Quality of Service in terms of data throughput, achieving the same in multi-hop WiMax mesh is challenging. One of the major problems is dealing with the interference from transmission of the neighboring WiMax nodes. Cross-layer design and optimization is known to improve the performance of wireless communication and mobile networks. Interference in wireless systems is one of the most significant factors that limit the network capacity and scalability of wireless mesh networks. Consideration of interference conditions during radio resource allocation and route formation processes impacts the design of concurrent transmission schemes with better spectral utilization while limiting the mutual interference.
A newly formed group within 802.16, the Mesh Ad Hoc committee, is investigating ways to improve the coverage of base stations even more. Mesh networking allows data to hop from point to point, circumventing obstacles such as hills Only a small amount of meshing is required to see a large improvement in the coverage of a single base station. If this groupâ„¢s proposal is accepted, they will become Task Force F and develop an 802.16f standard.
In comparison to IEEE 802.11a/b/g based mesh network, the 802.16-based WiMax mesh provides various advantages apart from increased range and higher bandwidth. The TDMA based scheduling of channel access in WiMax-based multi-hop relay system provides fine granularity radio resource control. This TDMA based scheduling mechanism allows centralized slot allocation, which provides overall efficient resource utilization suitable for fixed wireless backhaul network. (The WiMax based mesh backhaul application differs from the802.11a/b/gbased mesh, which targets mobile ad hoc networks.) However, the interference remains a major issue in multi hop WiMax mesh networks. To provide high spectral usage, inefficient algorithm for slot allocation is needed, so as to maximize the concurrent transmissions of data in the mesh. The level of interference depends upon how the data is routed in the WiMax network. In IEEE 802.16 Mesh mode, a Mesh base station (BS) provides backhaul connectivity of the mesh network and controls one or more subscriber stations (SS). When centralized scheduling scheme is used, the Mesh BS is responsible for collecting bandwidth request from subscriber stations and for managing resource allocation. First will be introduced the 802.16 Mesh network entry process (i.e., a process by which a new node joins the mesh), and then we describe the network resource allocation request/granting procedure. In IEEE 802.16 Mesh mode, Mesh Network Configuration (MSH-NCFG) and Mesh Network Entry (MSH-NENT) messages are used for advertisement of the mesh network and for helping new nodes to synchronize and to joining the mesh network. Active nodes within the mesh periodically advertise MSH-NCFG messages with Network Descriptor, which outlines the basic network configuration information such as BS ID number and the base channel currently used. A new node that plans to join an active mesh network scans for active networks and listens to MSH-NCFG message. The new node establishes coarse synchronization and starts the network entry process based on the information given by MSHNCFG. Among all possible neighbors that advertise MSH-NCFG, the joining node (which is Called Candidate Node in the 802.16 Mesh mode terminologies) selects a potential Sponsoring Node to connect to. A Mesh Network Entry message (MSH-NENT) with Net Entry Request information is then sent by the Candidate Node to join the mesh. The IEEE 802.16 Mesh mode MAC supports both centralized scheduling and distributed scheduling.
22 Centralized mesh scheme is used to establish high-speed broadband mesh connections, where the Mesh BS coordinates the radio resource allocation within the mesh network. In the centralized scheme, every Mesh SS estimates and sends its resource request to the Mesh BS, and the Mesh BS determined the amount of granted resources for each link and communicates. The request and grant process uses the Mesh Centralized Scheduling (MSHCSCH) message type. A Subscriber Stations capacity requests are sent using the MSHCSCH:
Request message to the Subscriber Stationâ„¢s parent node. After the Mesh BS determines the resource allocation results, the MSH-CSCH: Grant is propagated along the route from Mesh BS. To disseminate the link, node, and scheduling tree configuration information to all participants within the mesh network, the Mesh Centralized Scheduling Configuration (MSHCSCF) message is broadcasted by the Mesh BS and then re-broadcasted .
3.8. Wireless Services
What this points out is that WiMax actually can provide two forms of wireless service:
- There is the non-line-of-sight, WiFi sort of service, where a small antenna on subscriber computer connects to the tower. In this mode, WiMAX uses a lower frequency range 2GHz to 11 GHz (similar to WiFi). Lower-wavelength transmissions are not as easily disrupted by physical obstructions -- they are better able to diffract, or bend, around obstacles.
There is line-of-sight service, where a fixed dish antenna points straight at the WiMax tower from a rooftop or pole. The line-of-sight connection is stronger and more stable, so it's able to send a lot of data with fewer errors. Line-of-sight transmissions use higher frequencies, with ranges reaching a possible 66 GHz. At higher frequencies, there is less interference and lots more bandwidth WiFi-style access will be limited to a 4-to-6 mile radius (perhaps 25 square miles or 65 square km of coverage, which is similar in range to a cell-phone zone). Through the stronger line-of sight antennas, the WiMax transmitting station would send data to WiMAX-enabled computers or routers set up within the transmitter's 30-mile radius (2,800 square miles or 9,300 square km of coverage). This is what allows WiMAX to achieve its maximum range..
3.9. WiMax Infrastructure
Typically, a WiMax system consists of two parts:
- A WiMax Base Station- Base station consists of indoor electronics and a WiMax tower. Typically, a base station can cover up to 10 km radius (Theoretically, a base station can cover-up to 50 kilo meter radius or 30 miles, however practical considerations limit it to about 10km or 6 miles). Any wireless node within the coverage area would be able to access the Internet.
- A WiMax receiver - The receiver and antenna could be a stand-alone box or a PC card that sits in your laptop or computer. Access to WiMax base station is similar to accessing a Wireless Access Point in a WiFi network, but the coverage is more.
Several base stations can be connected with one another by use of high-speed backhaul microwave links. This would allow for roaming by a WiMax subscriber from one base station to another base station area, similar to roaming enabled by Cellular phone companies. Several topology and backhauling options are to be supported on the WiMax base stations wire line backhauling (typically over Ethernet), microwave Point-to-Point connection, as well as WiMax backhaul. With the latter option, the base station has the capability to backhaul itself. This can be achieved by reserving part of the bandwidth normally used for the end-user traffic and using it for backhauling purposes.
3.10. WiMAX Network IP-Based Architecture
The network specifications for WiMax-based systems are based on several basic network architecture tenets, including those listed below. Some general tenets have guided the development of Mobile WiMax Network Architecture and include the following:
-Provision of logical separation between such procedures and IP addressing, routing and connectivity management procedures and protocols to enable use of the access architecture primitives in standalone and interworking deployment scenarios,
- Support for sharing of ASN(s) (Access Service Networks) of a Network Access Provider (NAP) among multiple NSPs, - Support of a single NSP (Network Service Provider) providing service over multiple ASN(s) â€œ managed by one or more NAPs,
- Support for the discovery and selection of accessible NSPs by an MS or SS,
-Support of NAPs that employ one or more ASN topologies,
-Support of access to incumbent operator services through internetworking functions as needed,
-Specification of open and well-defined reference points between various groups of network functional entities (within an ASN, between ASNs, between an ASN and a CSN (Connectivity Service Network) , and between CSNs), and in particular between an MS, ASN and CSN to enable multi-vendor interoperability,
-Support for evolution paths between the various usage models subject to reasonable technical assumptions and constraints,
- Enabling different vendor implementations based on different combinations of 25 functional entities on physical network entities, as long as these implementations comply with the normative protocols and procedures across applicable reference points, as defined in the network specifications
- Support for the most trivial scenario of a single operator deploying an ASN together with a limited set of CSN functions, so that the operator can offer basic Internet access service without consideration for roaming or interworking. The WiMax architecture also allows both IP and Ethernet services, in a standard mobile IP compliant network. The flexibility and interoperability supported by the WiMax network provides operators with a multi-vendor low cost implementation of a WiMax network even with a mixed deployment of distributed and centralized ASNâ„¢s in the network. The WiMax network has the following major features:
- Security. The end-to-end WiMax Network Architecture is based on a security framework that is agnostic to the operator type and ASN topology and applies consistently across Greenfield and internetworking deployment models and usage scenarios. In particular there is support for:
1. Strong mutual device authentication between an MS and the WiMax network, based on the IEEE 802.16 security framework, 2. All commonly deployed authentication mechanisms and authentication in home and visited operator network scenarios based on a consistent and extensible authentication framework 3. Data integrity, replay protection, confidentiality and non-repudiation using applicable key lengths, 4. Use of MS initiated/terminated security mechanisms such as Virtual Private Networks (VPNs), 5. Standard secure IP address management mechanisms between the MS/SS and its home or visited NSP.
-Mobility and Handovers. The end-to-end WiMax Network Architecture has extensive capability to support mobility and handovers. It will:
1. Include vertical or inter-technology handoversâ€ e.g., to Wi-Fi, 3GPP (The Third Generation Partnership Project) , 3GPP2, DSL, or MSO (Multiple Service Operators) â€œ when such capability is enabled in multi-mode MS, 26
2. Support IPv4 (IP Version 4) or IPv6 based mobility management. Within this framework, and as applicable, the architecture shall accommodate MS with multiple IP addresses and simultaneous IPv4 and IPv6 connections,
3. Support roaming between NSPs,
4. Utilize mechanisms to support seamless handovers at up to vehicular speedsâ€ satisfying well defined (within WiMax Forum) bounds of service disruption.
Some of the additional capabilities in support of mobility include the support of:
1. Dynamic and static home address configurations,
2. Dynamic assignment of the Home Agent in the service provider network as a form of route optimization, as well as in the home IP network as a form of load balancing
3. Dynamic assignment of the Home Agent based on policies.
- Quality of Service. The WiMax Network Architecture has provisions for support of QoS mechanisms. In particular, it enables flexible support of simultaneous use of a diverse set of IP services. The architecture supports:
1. Differentiated levels of QoS - coarse-grained (per user/terminal) and/or finegrained (per service flow per user/terminal),
2. Admission control, and 3. Bandwidth management Extensive use is made of standard IETF mechanisms for managing policy definition and policy enforcement between operators. 3.11. End-to-End WiMax Architecture
The IEEE only defined the Physical (PHY) and Media Access Control (MAC) layers in 802.16. This approach has worked well for technologies such as Ethernet and WiFi, which rely on other bodies such as the IETF (Internet Engineering Task Force) to set the standards for higher layer protocols such as TCP/IP, SIP, VoIP and IPSec. In the mobile wireless world, standards bodies such as 3GPP and 3GPP2 set standards over a wide range of interfaces and protocols because they require not only air link interoperability, but also inter-vendor internet work interoperability for roaming, multivendor access networks, and inter-company billing.
Vendors and operators have recognized this issue, and have formed additional working 27 groups to develop standard network reference models for open inter-network interfaces. Two of these are the WiMax Forumâ„¢s Network Working Group, which is focused on creating higher-level networking specifications for fixed, nomadic, portable and mobile WiMax systems beyond what is defined in the IEEE 802.16 standard, and Service Provider Working Group which helps write requirements and prioritizes them to help drive the work of Network WG. The Mobile WiMax End-to-End Network Architecture is based an All-IP platform, all packet technology with no legacy circuit telephony. It offers the advantage of reduced total cost of ownership during the lifecycle of a WiMax network deployment.
The use of All-IP means that a common network core can be used, without the need to maintain both packet and circuit core networks, with all the overhead that goes with it. A further benefit of All-IP is that it places the network on the performance growth curve of general processing advances occur much faster than advances in telecommunications equipment because general purpose hardware is not limited to telecommunications equipment cycles, which tend to be long and cumbersome. The end result is a network that continually performs at ever higher capital and operational efficiency, and takes advantage of 3rd party developments from the Internet community. This results in lower cost, high scalability, and rapid deployment since the networking functionality is all primarily software-based services. In order to deploy successful and operational commercial systems, there is need for support beyond 802.16 (PHY/MAC) air interface specifications. Chief among them is the need to support a core set of networking functions as part of the overall End-to-End WiMax system architecture. Before delving into some of the details of the architecture, we can note a few basic tenets that have guided the WiMax architecture development:
-The architecture is based on a packet-switched framework, including native procedures based on the IEEE 802.16 standard and its amendments, appropriate IETF RFCs and Ethernet standards.
- The architecture permits decoupling of access architecture (and supported topologies) from connectivity IP service. Network elements of the connectivity system are agnostic to the IEEE 802.16 radio specifics.
- The architecture allows modularity and flexibility to accommodate a broad range of deployment options such as:
1. Small-scale to large-scale (sparse to dense radio coverage and capacity) WiMax networks.
2. Urban, suburban, and rural radio propagation environments
3. Licensed and/or licensed-exempt frequency bands
4. Hierarchical, flat, or mesh topologies, and their variants
5. Co-existence of fixed, nomadic, portable and mobile usage models
3.11.1 Support for Services and Applications. The end-to-end architecture includes the support for:
-Voice, multimedia services and other mandated regulatory services such as emergency services and lawful interception,
-Access to a variety of independent Application Service Provider (ASP) networks in an agnostic manner,
-Mobile telephony communications using VoIP,
-Support interfacing with various interworking and media gateways permitting delivery of incumbent/legacy services translated over IP (for example, SMS over IP, MMS, WAP) to WiMax access networks and
-Support delivery of IP Broadcast and Multicast services over WiMax access networks.
3.11.2 Interworking and Roaming. Another key strength of the End-to-End Network Architecture with support for a number of deployment scenarios. In particular, there will be support of - Loosely-coupled interworking with existing wireless networks such as 3GPP and 3GPP2 or existing wire line networks such as DSL, with the interworking interface(s) based on a standard IETF suite of protocols,
- Global roaming across WiMAX operator networks, including support for credential reuse, consistent use of AAA for accounting and billing, and consolidated/common billing and settlement,
- A variety of user authentication credential formats such as username/password, digital certificates, Subscriber Identify Module (SIM), Universal SIM (USIM), and Removable User Identify Module (RUIM).
WiMax Forum industry participants have identified a WiMax Network Reference Model(NRM) that is a logical representation of the network architecture. The NRM
identifies functional entities and reference points over which interoperability is achieved between functional entities. The architecture has been developed with the objective of providing unified support of functionality needed in a range of network deployment models and usage scenarios (ranging from fixed â€œ nomadic â€œ portable â€œ simple mobility â€œ to fully mobile subscribers).
3.12. WiMax Protocol
An 802.16 wireless service provides a communications path between a subscriber site and a core network such as the public telephone network and the Internet. Table3.3 WiMax, WLAN, and Bluetooth parameters This wireless broadband access standard provides the missing link for the "last mile" connection in metropolitan area networks where DSL, Cable and other broadband access methods are not available or too expensive. The Wireless MAN technology is also branded as WiMax
IEEE 802.16 Protocol Architecture has 4 layers: Convergence, MAC, Transmission and
physical, which can be map to two OSI lowest layers: physical and data link, as shown at
3.13 Mobile WiMax
The WiMax technology, based on the IEEE 802.16-2004 Air Interface Standard is rapidly proving it.
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WiMAX Vs WiFi.ppt (Size: 1.09 MB / Downloads: 397)
WiMAX Vs Wi-Fi
Worldwide Interoperability for Microwave Access
Brand licensed by the WiMax Forum.
“a standards-based technology enabling the delivery of last mile wireless broadband access as an alternative to cable and DSL”
WiMAX was seen as more of a Metropolitan Area Network (MAN) technology providing a much larger coverage.
Based on IEEE 802.16
WiMAX, in fact, comes in two forms, a so called ‘fixed WiMAX’ and a ‘mobile WiMAX’.
WiMAX in its fixed form is seen as a possible alternative to expensive cable and fibre deployment.
It is faster to deploy and less expensive and it also offers operators more flexibility in terms of deployment time frame and possible installation areas.
3G or other cellular network operators could see this as a potential substitute or as a complement to their cellular product.
Stands for Wireless Fidelity.
Brand licensed by the Wi-Fi Alliance.
Wi-Fi is a local area network technology that was originally thought to replace the thousands of miles of LAN cables.
Wireless Local Area Networks (WLAN)
Based on IEEE 802.11
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Mobile WiMax: The Next Wireless Battleground
The new technologies that satisfy the ongoing demand for faster data rates with longer transmission ranges are being researched by the scientists. Thus the lucrative mobile-communications market has become a virtual battleground. mobile WiMax is the latest to join the series. This addition will complete the alliance of Wi-Fi, and last-mile Internet-access technologies such as DSL and cable. mobile WiMax doesn’t need wireline systems’ expensive and hard-to-install infrastructure. The networking between carriers’ fixed base stations and mobile devices is implemented by IEEE 802.16e. This enables switching of data transmissions from one
base station to another base station as the client device moves from one base station to the other. soft handoffs or hard handoffs can be used. Mobile WiMax works via modems powered by chipsets .
mobile WiMax delivers quality of service unlike its parent Wimax. An access slot is assigned to each of the participating devices. mobile WiMax
works with multiple-input, multiple-output technology (MIMO) is being implemented by the mobile Wimax technology.
Rate, range, and spectrum
A maximum data rate of 70 Mbits per second is theoretically possible in the standard. a maximum transmission range of 35 miles i spossible for mobile wimax.
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WiMAX (Worldwide Interoperability for Microwave Access)
) is a telecommunications protocol that provides fixed and fully mobile internet access. The current WiMAX revision provides up to 40 Mbit/s with the IEEE 802.16m update expected offer up to 1 Gbit/s fixed speeds. (WiMAX is based on the IEEE 802.16 standard, also called Broadband Wireless Access). The name "WiMAX" was created by the WiMAX Forum, which was formed in June 2001 to promote conformity and interoperability of the standard. The forum describes WiMAX as "a standards-based technology enabling the delivery of last mile wireless broadband access as an alternative to cable and DSL".[4
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wimax.rtf (Size: 3.01 MB / Downloads: 85)
The major performance objectives of the next-generation wireless communication systems are high link capacity and increase application/service performance from the user perspective. An attractive technology for providing broadband access is WiMAX network. For the network and application-level capacity and performance analysis, we first provide an overview of WiMAX network architecture and system performance. Afterward we discuss the benefits and challenges of flat architecture for mobile networks. In this kind of architecture the access service network gateway and base stations are consolidated into a single channel. All-IP flat architecture is a promising option. However, performance goals of the WiMAX system are conflicting: maintenance VoIP quality vs. completely utilization of the remaining capacity for TCP. We investigate the approaches in performance optimization based on TCP modification schemes. The solution is to control TCP traffic before entering WiMAX network in conjunction with methods to dynamically estimate available bandwidth in real time.
The success of WiMAX high data rate communications in metropolitan area networks (MAN) depends on its capability of providing cost-effective solution for a variety of services . In 2001, the first IEEE802.16 standard was published, while in 2005, the standard IEEE802.16e was approved as the official standard for mobile applications . The mobile WiMAX systems have a higher system capacity and a more sophisticated mechanism to provide a better quality of service (QoS) . To evaluate the mobile WiMAX system capacity and performance, all the aspects of the performance evaluation – from air link to application– are required.
A mobile WiMAX network support both voice and TCP services. However, performance goals of the system are conflicting: maintenance VoIP quality vs. completely utilization of the remaining capacity for TCP. Services VoIP and TCP cannot simply share the WiMAX medium without severe voice quality degradation and/or reduction in TCP capacity . In order to investigate the interaction between these two categories of traffic, we present TCP modification and control schemes. The solution is to control TCP traffic before entering the multihop network.
The article is structured as follows. The next section discusses the state of the art in WiMAX networks and system performance evaluation, together with benefits of flat architecture of mobile network. We then present solution approaches for TCP and VoIP performance optimization based on traffic modification and control.
2 WiMAX networks architecture
WiMAX (Worldwide interoperability for microwave access) has been proposed as an attractive wireless communication technology due to the fact that it can provide high data rate communications for metropolitan areas. Until now, a number of specifications for WiMAX were standardized by the IEEE802.16 Working group . In addition companies in the industry also have formed the WiMAX Forum to promote the development and deployment of WiMAX systems. According to the standards, WiMAX can support up to a 75 Mbps data rate (single channel) and can cover on how it can provide cost-effective solutions for a variety of existing and potential services .
The specifications in the current WiMAX standards can be partitioned into two important parts, the physical (PHY) layer and the medium access control (MAC) layer: