Cellular Networks

NAME- ADITYA PANDEY ENROLL. NO.-

1

04613304409

CONTENTSIntroductionWorkingBenefitsCharacteristicsMovement From Cell To CellMobile Phone NetworksFuture ScopeBibliography

2

3

INTRODUCTION

3

•A cellular network is a radio network made up of a number of radio cells (or just cells) each served by at least one fixed-location transceiver known as a cell site or base station.

ExampleAn example of a simple non-telephone

cellular system is an taxi driver's radio system where the taxi company has several transmitters based around a city that can communicate directly with each taxi.

4

WORKING

5

MSMobile station; BSTBase station transceiver; MSCMobile switching center; BSCBase station controller; PSTNPublic switched telephone network

BENEFITSMore capacity due to spectral reuseLower transmission power due to smaller

transmitter/receiver distancesreduced power usagelarger coverage areareduced interference from other signals

6

CHARACTERISTICSPAGING

7

• Paging takes place by sending the broadcast message to all of the cells.

• In mobile telephony systems, the most important use of broadcast information is to set up channels for one to one communication between the mobile transceiver and the base station.

• Paging messages can be used for information transfer.

FREQUENCY REUSE

8

•FDMA

•Frequency Division Multiple Access or FDMA is a channel access method used in multiple-access protocols as a channelization protocol.

•FDMA gives users an individual allocation of one or several frequency bands, or channels. Multiple Access systems coordinate access between multiple users.

9

•CDMA

• Code division multiple access (CDMA) is a channel access method utilized by various radio communication technologies.

• It should not be confused with the mobile phone standards called cdmaOne and CDMA2000 (which are often referred to as simply "CDMA"), which use CDMA as an underlying channel access method.

• TDMA• Time division multiple access. A method of digital

wireless communications transmission that allows a large number of users to access (in sequence) a single radio frequency channel without interference by allocating unique time slots to each user within the channel. Each frequency is broken into time slots through which bits of data flow.

• TDMA is used in second generation wireless phone systems, such as GSM and TDMA.

• TDMA cannot be used to separate signals from one cell to the next since the effects of both vary with position and this would make signal separation practically impossible. 

• Time division multiple access, however, is used in combination with either FDMA or CDMA in a number of systems to give multiple channels within the coverage area of a single cell.

10

MOVEMENT FROM CELL TO CELL & HANDOVER

11

•RADIO TAXI NETWORK•In a primitive taxi system, when the taxi moved away from a first tower and closer to a second tower, the taxi driver manually switched from one frequency to another as needed. If a communication was interrupted due to a loss of a signal, the taxi driver asked the base station operator to repeat the message on a different frequency.

MOVEMENT FROM CELL TO CELL & HANDOVER

•CELLULAR NETWORK•In a cellular system, as the distributed mobile transceivers move from cell to cell during an ongoing continuous communication, switching from one cell frequency to a different cell frequency is done electronically without interruption.•This is called the handover or handoff.

12

MOBILE PHONE NETWORKS The most common example of a cellular network is

a mobile phone (cell phone) network. A mobile phone is a portable telephone which receives or

makes calls through a cell site (base station), or transmitting tower.

Since almost all mobile phones use cellular technology, including GSM, CDMA, and AMPS (analog), the term "cell phone" is in some regions, notably the US, used

interchangeably with "mobile phone". However, satellite phones are mobile phones that do not

communicate directly with a ground-based cellular tower, but may do so indirectly by way of a satellite.

13

MOBILE PHONE NETWORKS(Contd.)

There are a number of different digital cellular technologies, including: Global System for Mobile Communications (GSM)  General Packet Radio Service (GPRS)  Code Division Multiple Access (CDMA)  Evolution-Data Optimized (EV-DO)  Enhanced Data Rates for GSM Evolution (EDGE or GSM

EDGE)  3GSM  Digital Enhanced Cordless Telecommunications (DECT)  Digital AMPS (IS-136/TDMA)  Integrated Digital Enhanced Network (iDEN).

CDMAInterim Standard 95 (IS-95) is the first CDMA-based digital

cellular standard pioneered by Qualcomm. The brand name for IS-95 is cdmaOne.

It is a 2G Mobile Telecommunications Standard that uses CDMA, a multiple access scheme for digital radio, to send voice, data and signaling data (such as a dialed telephone number) between mobile telephones and cell sites.

CDMA or "code division multiple access" is a digital radio system that transmits streams of bits (PN codes).

CDMA permits several radios to share the same frequencies.Unlike TDMA "time division multiple access", a competing

system used in 2G GSM, all radios can be active all the time, because network capacity does not directly limit the number of active radios.

15

CDMA (Contd.)

Since larger numbers of phones can be served by smaller numbers of cell-sites, CDMA-based standards have a significant economic advantage over TDMA-based standards that used frequency-division multiplexing.

16

GSMGSM (Global System for Mobile communications:

originally from Groupe Spécial Mobile) is the most popular standard for mobile phones in the world.

Its promoter, the GSM Association, estimates that 80% of the global mobile market uses the standard. GSM is used by over 3 billion people across more than 212 countries and territories.

GSM differs from its predecessors in that both signaling and speech channels are digital, and thus is considered a second generation (2G) mobile phone system.

This has also meant that data communication was easy to build into the system. GSM EDGE is a 3G version of the protocol.

17

FUTURE SCOPENext Generation Mobile Networks (NGMN) Ltd. -

Consortium with partnership of major mobile operators

Recommendations without specific technology prescriptions

Target to establish performance targets, recommendations and deployment scenarios for future wide-area mobile broadband network packet switched core.

The architecture intended to provide a smooth migration of existing 2G/3G networks towards an IP network that is cost competitive and has broadband performance.

Multi-hopping Networks.

18

BIBLIOGRAPHYwww.google.comwww.wikipedia.orghttp://www.acm.org/crossroads/xrds7-2/

cellular.html

19

Thank You

20