GSM EVOLUTION

HISTORY OF GSM EVALUATION OF 1G

The first commercially cellular network was launched in Japan by NTT in 1979,

The network which covers the metropolis of Tokoyo with 23 base stations and five

years after the  network was expanded covering the entire population of Japan.

This was the first nation 1G network as it covered only Japan.

       In 1981 the next 1G network was launched in Denmark, Finland, Norway and Sweden by the Nordic mobile telephone(NMT) system. The NMT was able to implement international warning. The first Generation cellular network was based on frequency division multiplexing Access (FDMA)

                          EVOLUTION OF 2G

The conference European et postes des Administration Telecommunication (EPT) came on board to solve the problem that was inherent in the first Generation network (2G) as a result of the (FDMA) .CEPT came to provide a network with the following features:

(1)               Calls without limitation

(2)               Calls with good speed quality

(3)               Calls that are secured (ciphering)

(4)               Network that support messaging

(5)               Network that support local and international roaming.

With all this quality CEPT came up with the name Groupe spaciale  mobile which was later changed to Global system for mobile communication in 1982 by the European Telecommunication standard, institute (ESTI).

      The second Generation (2G) Contains the following features

(i) High speed circuit switched data (HSCSD)

(ii) Time Division Multiple Access

(iii) Digital signal unlike the 1G that made use of Analog signal.

(iv)A Data rate of 9.6 -14.4kbys

      Though the 2G could meet up with peoples demand as it was not possible to implement per second billing.The first GSM network (2G) was launched in Finland.

  EVOLUTION OF THIRD GENERATION

With the high demand of mobile services the 2G Network there was need for a better network to met up with the high density of mobile subscribers. The 2G network gave birth to 2.5G and 2.75G Networks as a transition to the new evolution of the next generation of GSM network .

    2.5 ushered in features like GPRS (General packet radio service) with two equipment under it. That is the Gateway GPRS support Node(GGSN) and the serving GPRS support Node (SGSN).Both features make up WAP which gave rise to internet access on mobile phones. The data rate was increased to 115-170kbps .this also give rise to per second billing.

    2.75G (EDGE): Enhance Data rate for Global evolution (EDGE)  is an improved version of GPRS. It was a cost effective way of migrating from 2G to 3G network features of 2.75G network are support for high volume movement with a transmission power of 384kbps software base and does not required special equipment for its implementation and technology was concentration the air interface, that is between the MS (mobile station) and the base transceiver station.

     Around mid 2000s another GSM Generation evolved known the universal mobile Telecommunication system (UMTS). This is the 3G network . During this period the 3G Technology also implemented high speed downlink packet access (HSDPA) which is enhanced version of 3G  3.5G an 3Gt or turbo 3G were derived for high data transfer speeds and capacity. 3G network achieved a data rata of 2mbps. The implementation does not require a BTS or RBS cabinet.

        EVOLUTION OF 4G (4^th Generation of GSM). 4G also known as long term Evolution (LTE) is an all based network.LTE is faster that UMTS and as the ability to utilize packet switching over internet, LAN or WAN network, allows video and audio streaming presently in Nigeria and other part of Africa we are yet to utilize the features of the 3G and 4G networks.

                     GSM ARCHITECTURE

     The GSM network consist of the following components

(1)Mobile station  (MS): this consist of the mobile Equipment (ME) and the subscriber identification module (SIM) Every ME comes with an international mobile equipment identification (IMEI)

The IMET is a unique number for mobile equipment. This is different from IMSI (international mobile subscriber identify. To check the IMEI of any ME, type

(2)BTS or RBS: The base transceiver station or Radio Base Station consist of the following

(a)BTS or RBS cabinet

(b)Transmission cabinet

(c)Sectorialized antenna and

(d)Microwave link (PDH plesiochroniaics digital hieraechy) for transmission.

The PDH carries the E1 link

   In the 2G network the BTS or RBS cabinet consist of transceivers which are capable of transmitting and receiving calla from the MS. The KBS data from the MS through the air interface via the sectorial antenna.

The transmission cabinet route the data out of the BTS station through the Abis interface with the help of the PDH (microwave link).

Sectorialized antennas divide a GSM network into sectors. These antennas are connected directly to a dual radio unit (DRU) through feeder cables. Note that it is the sectorialized antenna that link you MS (phone) to the networks. The interface is the medium, which is the air interface.

                        BSC: Base System Controller (BSC)

The BSC controls several RBS stations through the Abis interface. The BSC takes care of allocating radio channels controls handover from BTS to BTS and so on.

Communication between the RBS and BSC is through microwave link (PDH) that is sent to the BSC are multiplexed into E1 before sending it to the MSC

Mobile Switching Center (MSC):The MSC is in charge of bandwidth allocation while the BSC is in charge of Bandwidth sharing. The bandwidth comes in turn  of E1 which is equal to 32 channels. Each channels is 64kbps in speed. Mathematically the speed of E1=32 channels 64kbps

=2048kbps=2.048mbps

MSC consist of the following
        (1) Home location register  (HLR)

(2) Visitors location register (VLR)

(3) Authentication center (AUC)

(4) Equipment identification register (EIR)

Gateway mobile station Center (GMSC)