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wirelesscommuniction introdution

Transcript of wireless communication intro

Unit I Unit II Unit III Unit IV

Unit V

Evolution of Mobile Radio CommunicationsPaging Systems Cordless Telephone Systems Cellular Telephone Systems

Modern Wireless Communication Systems2G Networks 3G Networks WLL Wireless local Loop LMDS Local Multipoint Distribution Systems Bluetooth Personal Area Networks

UNIT II Frequency reuse Channel assignment strategies Hand off Strategies Interference and system capacity Trunking and Grade of service Improving Coverage and capacity in Cellular Systems

UNIT III Large Scale path loss

Free space propagation model Basic propagation Mechanism Fading and its types Small scale and Multipath fading Small scale and Multipath Propagation

Impulse response model of Multipath channel Small scale multipath measurements Parameters of mobile multipath channel


Modulation techniques for mobile radio Equalization and its Different TypesLinear and Non Linear Equalizers

Diversity Techniques Rake receiver Interleaving

UNIT V Difference between Wireless and Fixed telephone networks Development of Wireless Networks Fixed network Transmission hierarchy Traffic routing in Wireless networks Wireless data services Signaling techniques Wireless System Standards GSM, CDMA, CT2, PACS

1. Theodore S. Rappaport, Wireless communications Principles and Practice, Pearson Education, Second Edition, 2002. 2. William C.Y.Lee, Wireless and Cellular Communications, Tata McGraw Hill Publishers, Third Edition, 2006.

3. Kamilo Feher, Wireless Digital Communications, Prentice Hall of India, 2004.

Motorolos DynaTec

AMPS Phone

First Mobile Phone

Evolution of Mobile Radio CommunicationsPaging Systems Cordless Telephone Systems Cellular Telephone Systems

Modern Wireless Communication Systems2G Networks 3G Networks WLL Wireless local Loop LMDS Local Multipoint Distribution Systems Bluetooth Personal Area Networks

History of Mobile CellularTechnology Based:

The analog frequency division multiple access (FDMA) systems are 1G systems. The digital time division multiple access (TDMA) systems with circuit switching are 2G systems. The code division multiple access (CDMA) systems with packet/circuit switching are 3G systems Advanced mobile access technology used with an all Internet protocol (IP) network will be called 4G.

History of Mobile CellularWith respect to Time period: The Analog systems are 1G Digital voice systems are 2GDigital voice/data systems are B2G

Broadband digital systems are 3G Wireless local area network/wireless metropolitan area network (WLAN/WMAN) are B3G systems

Very-high-speed systems





- Simplex: communication in only one direction Half-duplex: same radio channel for both transmission and reception (push-to-talk)

Full-duplex: simultaneous radio transmission and reception (FDD, TDD) Frequency division duplexing uses two radio channel Time division duplexing shares a single radio channel in time.

Evolution of Mobile Radio Communications- 1946 Public Mobile Phone Telephone Service

introduced in 25 major American Cities - Each System used High Power Transmitter to cover 50 km - 1940s Push To Talk used 120 kHz Spectrum (though 3 kHz is sufficient due to filters & ckts) - By 1960s FM Spectrum came to 30 kHz - Automatic Channel Trunking (1950s & 1960s) - Cellular concept developed by AT &T Bell Labs

In 1983, FCC allocated 666 duplex Channels (40 MHz of spectrum in the 800 MHz band, each channel having one way bandwidth of 30 kHz) for AMPS system In 1989, FCC granted additional 166 Channels (10 MHz) for rapid growth and demand

Example of Mobile Radio Systems Garage door openers, Remote Controllers Pagers Cordless phone Cellular telephone Remote controller Hand-held walkie-talkies Wireless LAN Mobile any radio terminal that could be moves during operation Portable hand-held and used at walking speed Subscriber - mobile or portable user

A pager (page, beeper, bleep or bleeper) is a simple personal telecommunications device for short messages. A one-way numeric pager can only receive a message consisting of a few digits, typically a phone number that the user is then expected to call. Alphanumeric pagers are available, as well as two-way pagers that have the ability to send and receive email, numeric pages, and SMS messages.

Conventional paging system send brief messages to a subscriber Modern paging system: news headline, stock quotations, faxes, etc. Simultaneously broadcast paging message from each base station(simulcasting) Large transmission power to cover wide area.

Cordless telephone systems are full duplex communication systems. First generation cordless phone in-home use communication to dedicated base unit few tens of meters Second generation cordless phone outdoor combine with paging system few hundred meters per station

Provide connection to the PSTN for any user location within the radio range of the system. Characteristic Large number of users Large Geographic area Limited frequency spectrum Reuse of the radio frequency by the concept of cell. Basic cellular system: mobile stations, base stations, Base station Controller mobile switching center.






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There are two basic cellular systems;Circuit-switched system and Packet-switched system.

Circuit Switched System - each traffic channel is dedicated to a user until its cell is terminated. We can further distinguish circuit-switched systems into two: Analog system and Digital system

Analog System

A basic analog cellular system13 consists of three subsystems: a mobile unit, a cell site, and a mobile telephone switching office (MTSO) ,


Mobile units. A mobile telephone unit control unit, transceiver and antenna system.

2. Cell site. The cell site provides interface between the MTSO and the mobile units. Control unit, Radio cabinets, antennas, a power plant, and data terminals3. MTSO. The switching office, the central coordinating element for all cell sites, The cellular processor and Cellular switch. 4. Connections. The radio and high-speed data links connect the three subsystems.

B. Digital SystemsA basic digital system consists of four elements:

mobile station (MS), base transceiver station (BTS), base station controller (BSC), and switching subsystems (SS),MS: It consists of two parts, mobile equipment (ME) and subscriber identify module (SIM). SIM contains all subscriber-specific data stored on the MS side. BTS: Besides having the same function as the analog BTS, it has the Transcoder/Rate Adapter Unit(TRAU), which carries out coding and decoding as well as rate adaptation in case data rate varies. BSC: A new element in digital systems that performs the Radio Resource (RR) management for the cells under its control. BSC also handles handovers, power management time and frequency synchronization, and frequency reallocation among BTSs.

Switching Subsystems:a. MSC: The main function of MSC is to coordinate the setup of calls between MS and PSTN users. b. VLR (Visitor Location Register): A database of all mobiles roaming in the MSCs area of control.

c. HLR(Home Location Register):Acentralized database of all subscribers registered in a Public Land Mobile Network (PLMN).d. AUC (Authentication Center): Provides HLR with authentication parameters and ciphering keys that are used for security purposes. e. EIR (Equipment Identity Register): A database for storing all registered mobile equipment numbers.

f. IWF (Inter Working Function): Provides the subscriber with data services that can acess data rate and protocol conversion facilities and interfaces with public and private data networks. g. EC (Echo Canceller): Used on the PSTN side of the MSC for all voice circuits. h. XC (Transcoder): Usually installs in each BTS. But for the cost reason, it can be installed in BSC or MSC.


OMC(Operational and Maintenance Center): This function resided in analog MSC but became a separated entity in digital systems.

A cellular packet-switched systemThere are six elements: MS, Node B, RNC, SGSN, GGSN, and GF

MS: Provides the voice and packet data services. It is also called UE (User Equipment).Node B: The name for base station in GSM.

RNC (Radio Network Controller): Controls the radio resources of the Node Bs that are connected to it. Its function is similar to BSC.PCU (Packet Control Unit) converts the data stream into packet format. SGSN (Service GPRS Support Node): Analogous to MSC/VLR in the circuit-switched system. This includes mobility management, security, and access control functions. It interfaces to HLR.

GGSN (Gateway GPRS Support Node): The point of interface with external packet data networks such as the Internet. CGF (Changing Gateway Function): Mainly for billing. RNS (Radio Network Subsystem): It consists of RNC and Node B. UTRAN consists of two or more RNS.