Active In SP
Joined: Feb 2011
03-03-2011, 02:41 PM
37765527-Mobile-Communication.pptx (Size: 794.96 KB / Downloads: 92)
History of Mobile Communication
Mobile phones have their roots in radiophones.
Radiophones have a long and varied history going back to Reginald Fessenden’s invention and shore-to-ship demonstration of radio telephony, through the Second World War with military use of radio telephony links and civil services in the 1950s, while hand-held cellular radio devices have been available since 1973.
Due to their low establishment costs and rapid deployment, mobile phone networks have since spread rapidly throughout the world, outstripping the growth of fixed telephony.
The concepts of frequency reuse and handoff as well as a number of other concepts that formed the basis of modern Cell Phone or mobile phone.
Cellular Technology - Telephony, a generic for all wireless phones, and cellular, a term derived from cellular base stations that control phone calls, are a combination of technologies that allow for mobile phone transmission and reception in a given area.
Generation of mobile phones
First Generation Mobile Phones (Also known as 1G ) came into vogue first in the United States of America in 1973.
It used analog signals and hence needed more than one base stations which were closely located.
The first handheld mobile phone to become commercially available to the US market was the Motorola DynaTAC 8000X which received approval in 1983.
Mobile were too robust and heavy, they were static and designed for permanent installation in vehicles.
Features of First generation
Analog voice signaling was use.
Not much reliable networks.
No SMS and Roaming Facility.
Example: Advanced Mobile Phone System (AMPS) is the analog mobile phone system standard developed by Bell Labs.
Second Generation Mobile Phones (Also known as 2G ) adopt the system of digital signaling in order to establish a connection between the radio towers.
first digital cellular phone call was made in the United States in 1990 and still in use.
Second Generation Mobile Phones were digital circuit and the use of advanced and fast phone to network signaling.
Frequency was much higher.
Features of 2G
GSM – GLOBAL SYSTEM FOR MOBILE COMMUNICATION
GSM technology which stands for GLOBAL SYSTEM FOR MOBILE COMMUNICATION, The GSM belonging to TDMA is the most widely used technology across the world and was first started in Finland
Phase I of GSM specifications was published in 1990
International demand was so great that the system name was changed from Groupe Special Mobile to Global Systems for Mobile Communications (still GSM).
Commercial service started in mid-1991
1992 first paying customers were signed up for service.
By 1993 there were 36 GSM networks in 22 countries
Early 1994 there were 1.3 million subscribers worldwide
By 1996 there were more than 25 million subscribers worldwide
By October 1997 it had grown to more than 55 million subscribers worldwide
Mobile Station (MS)
Produced by many different manufacturers
Must obtain approval from the standardization body
Uniquely identified by an IMEI (International Mobile Equipment Identity
Subscriber Identity Module (SIM)
Smart card containing the International Mobile Subscriber Identity (IMSI)
Allows user to send and receive calls and receive other subscribed services
Encoded network identification details
Protected by a password or PIN
Can be moved from phone to phone – contains key information to activate the phone
Base Station Subsystem is composed of two parts that communicate across the standardized Abis interface allowing operation between components made by different suppliers
Base Transceiver Station (BTS)
Base Station Controller (BSC)
Base Transceiver Station (BTS)
Houses the radio transceivers that define a cell
Handles radio-link protocols with the Mobile Station
Speech and data transmissions from the MS are recoded
Requirements for BTS:
• minimum costs
Base Station Controller (BSC)
Manages Resources for BTS
Handles call set up
Handover for each MS
Mobile Switching Center (MSC)
Switch speech and data connections between:
• Base Station Controllers
• Mobile Switching Centers
• Other external networks
Heart of the network
Three main jobs:
1) connects calls from sender to receiver
2) collects details of the calls made and received
3) supervises operation of the rest of the network components
Home Location Registers (HLR)
Contains administrative information of each subscriber
Current location of the mobile
Visitor Location Registers (VLR)
contains selected administrative information from the HLR
authenticates the user
tracks which customers have the phone on and ready to receive a call
periodically updates the database on which phones are turned on and ready to receive calls
Authentication Center (AUC)
Mainly used for security
Mata storage location and functional part of the network
Ki is the primary element
Equipment Identity Register (EIR)
Database that is used to track handsets using the IMEI (International Mobile Equipment Identity)
Made up of three sub-classes: The White List, The Black List and the Gray List
Basic Features Provided by GSM
Advanced Features Provided by GSM
2.5G is a stepping stone between 2G and 3G cellular wireless technologies.
2.5G provides some of the benefits of 3G (e.g. it is packet-switched) and can use some of the existing 2G infrastructure such as GSM networks.
GPRS and EDGM services got introduced due to the increase in the demand of internet. Currently we are in 2.5G which comprises of GSM, EDGM and GPRS.
Stand for General Packet Radio Service
packet oriented Mobile Data Service available to users of Global System for Mobile Communications (GSM).
Provide Internet communication services such as email and World Wide Web access.
Always connected and send data immediately
higher speeds: typically 32-48 kbps.
GPRS data is handled as a series of "packets" that can be routed over several paths through the network, rather than as a continuous bit-stream.
the information is split into separate but related "packets" before being transmitted and reassembled at the receiving end.
Stands for Enhanced Data rates for GSM Evolution.
maximum data transfer rate of 384 kbps
EDGE offers the best that can be achieved with a 2.5G network
Future -- UMTS (Universal Mobile Telephone System)
Reasons for innovations
new service requirements
availability of new radio bands
seamless Internet-Intranet access
wide range of available services
compact, lightweight and affordable terminals
simple terminal operation
open, understandable pricing structures for the whole spectrum of available services
3G was introduced in the United States early in 2002.
send data up to 40 times the rates of earlier digital networks.
Applicable to mobile as well as fixed wireless systems.
Should be operational on, above and below the earth.
Potential for 3G
Possibilities with 3G
Mobile internet connectivity.
Multimedia services such as digital photos.
Wireless application downloading.
Video on demand.
Real-time multiplayer gaming.
Enhanced emergency and location based service.
Push to talk & push to video message.
Voice/high quality audio.
Evolution of 3G
Leading UN agency for Information & Communication.
Organizes Telecom events.
Includes 191 member states and more than 700 sector members and associates.
Made a 3G standard called IMT-2000
Single global wireless standard.
linking of diverse systems of terrestrial and/or satellite based networks.
Various 3G services used across the world
Mobile T.V. based on video streaming, T-Mobile (Germany).
Mobile Earth for navigation, Vodafone (Germany).
Mobile Radio based on audio streaming, TELUS Mobility (Canada).
Banking & Finance services, Telstra (Australia).
Technology behind UMTS
Closely linked to GSM standard
It was evolved by 3GPP
Was finalized in 1999
Chip Rate 3.84 Mcps.
UMTS uses 15 slots per frame.
Adaptive power control based on SIR.
Smart antennas can be used to increase capacity and coverage.
Frequency band 1920-1980 MHz and 2110-2170 MHz.
Channel Bit Rate 5.76 Mbps.
Frame length is 10 ms(38400 chips).
Number of Chips per slot is 2560
W-CDMA has Two modes of Operation
Time-division duplexing (TDD) is the application of time-division multiplexing to separate outward and return signals. It emulates full-duplex communication over a half-duplex communication link
In this method uplink and downlink transmission are carried over the same frequency band using synchronized time intervals.
The uplink and downlink transmissions employ two different frequency band. A pair of frequency band with specified separation is assigned for a connection
Active In SP
Joined: Feb 2011
08-03-2011, 03:37 PM
mobile comm.ppt (Size: 1.16 MB / Downloads: 127)
Chapter 1: Introduction
Computers for the next century?
Computers are integrated
small, cheap, portable, replaceable - no more separate devices
Technology in the background
computer are aware of their environment and adapt (“location awareness”)
computer recognize the location of the user and react appropriately (e.g., call forwarding, fax forwarding)
Advances in technology
more computing power in smaller devices
flat, lightweight displays with low power consumption
new user interfaces due to small dimensions
more bandwidth per cubic meter
multiple wireless interfaces: wireless LANs, wireless WANs, regional wireless telecommunication networks etc. („overlay networks“)
Aspects of mobility:
user mobility: users communicate (wireless) “anytime, anywhere, with anyone”
device portability: devices can be connected anytime, anywhere to the network
Wireless vs. mobile Examples
û û stationary computer
û ü notebook in a hotel
ü û wireless LANs in historic buildings
ü ü Personal Digital Assistant (PDA)
The demand for mobile communication creates the need for integration of wireless networks into existing fixed networks:
local area networks: standardization of IEEE 802.11,
Internet: Mobile IP extension of the internet protocol IP
wide area networks: e.g., internetworking of GSM and ISDN
transmission of news, road condition, weather, music via DAB
personal communication using GSM
position via GPS
local ad-hoc network with vehicles close-by to prevent accidents, guidance system, redundancy
vehicle data (e.g., from busses, high-speed trains) can be transmitted in advance for maintenance
early transmission of patient data to the hospital, current status, first diagnosis
replacement of a fixed infrastructure in case of earthquakes, hurricanes, fire etc.
direct access to customer files stored in a central location
consistent databases for all agents
Replacement of fixed networks
remote sensors, e.g., weather, earth activities
flexibility for trade shows
LANs in historic buildings
Entertainment, education, ...
outdoor Internet access
intelligent travel guide with up-to-date location dependent information
ad-hoc networks for multi user games
Location dependent services
Location aware services
what services, e.g., printer, fax, phone, server etc. exist in the local environment
automatic call-forwarding, transmission of the actual workspace to the current location
„push“: e.g., current special offers in the supermarket
„pull“: e.g., where is the Black Forrest Cherry Cake?
caches, intermediate results, state information etc. „follow“ the mobile device through the fixed network
who should gain knowledge about the location
Wireless networks in comparison to fixed networks
Higher loss-rates due to interference
emissions of, e.g., engines, lightning
Restrictive regulations of frequencies
frequencies have to be coordinated, useful frequencies are almost all occupied
Low transmission rates
local some Mbit/s, regional currently, e.g., 9.6kbit/s with GSM
Higher delays, higher jitter
connection setup time with GSM in the second range, several hundred milliseconds for other wireless systems
Lower security, simpler active attacking
radio interface accessible for everyone, base station can be simulated, thus attracting calls from mobile phones
Always shared medium
secure access mechanisms importantEarly history of wireless communication Many people in history used light for communication
heliographs, flags („semaphore“), ...
150 BC smoke signals for communication;(Polybius, Greece)
1794, optical telegraph, Claude Chappe
Here electromagnetic waves are of special importance:
1831 Faraday demonstrates electromagnetic induction
J. Maxwell (1831-79): theory of electromagnetic Fields, wave equations (1864)
H. Hertz (1857-94): demonstrateswith an experiment the wave character of electrical transmission through space(1886, in Karlsruhe, Germany, at the location of today’s University of Karlsruhe)