2G vs 3G Network Technology
The initialization of communication networks began with the analog (1G) mobile telephony in which many of the features available in current networks were not available such as SIM etc. The evolution of mobile telephony began with GSM (2G) and now we are on the door step to 4G passing 2.5G, 2.75G, 3G and 3.5G.
2G (GSM) Network Technology
Global System for Mobile communication is also known as 2G is the first attempt to standardizing modern digital cellular concept. Technology standard was first introduced in 1991 and from that onwards number of subscribers has grown over 200 million during 1998. The standard has become so popular among people since the voice transmission was highly a success and with the technological advancements GSM handsets become handy.
According to specifications GSM handsets consists of an identifier which is used to authenticate subscriber in the network and called it as SIM (Subscriber Identity Module). The multiple access technology used is a hybrid version of FDMA (Frequency Division Multiple Access) and TDMA (Time Division Multiple Access) in order to increase the subscriber support in a given cell. Also the concept of cell is also populated and in order to cover the air interface an area is divided in to small hexagonal areas which are known as cells and each is covered by using 3 GSM sector antennas.
The GSM radio interface has data rate of 270Kbps and the voice channel bandwidth is limited to 200 kHz which is quite enough to carry voice data. The spectrum allocation for GSM by 3GPP consists of 14 bands in which following bands are heavily used in mobile networks such as GSM 850, GSM 900, GSM 1800 and GSM 1900. Here the uplink and downlink uses distinct bands for communication and the duplex distance is 45MHz for GSM 900 band. So the uplink frequencies are 890-915 MHz and downlink frequency band is 935-960 MHz and each band is sub divided in to 200 kHz channels.
Spectrum utilization for GSM falls in to several bands like GSM 900 and GSM 1800 (DCS) used in areas like Asia, Europe etc and GSM 850 and GSM 1900 used mainly in USA and Canada.
3G Network Technology
As mobile networks grow voice transmission is not the only facility being provided through the networks. Further it is enhanced to support high data rates for applications like video calling, streaming video and audio, video conferencing and multimedia applications etc in a mobile environment. There are two collaborations exists namely 3GPP and 3GPP2 the latter is the one making standards for 3G based on CDMA technology.
According to ITU (International Telecommunications Union) the following requirements has to be met by any network to be called as a 3G network as proposed by 3GPP. Data transfer rates (down link) of 144Kbps minimum for moving handsets and 384Kbps for pedestrian traffic and 2Mbps in indoor conditions for downlink. On demand bandwidth and 2Mbps broadband internet access are also specified by the 3GPP.
The multiple access technology being used is CDMA and which is based on a pseudo random code for each user allowing full access to bandwidth in air interface. CDMA technologies like CDMA2000, CDMA2000 1x EV-DO are used in various places over the world for 3G networks and the bandwidth is 1.25MHz for CDMA 2000 and WCDMA uses 5 MHz bandwidth.
|Difference between 2G and 3G Network Technologies |
1. 2G is the GSM specification intended for providing mobile communication for voice and 3G is the specification for mobile communication with enhanced services for mobile users other than voice.
2. GSM uses TDMA and FDMA for multiple access technology and 3G utilizes variations of CDMA technology like WCDMA, CDMA2000, CDA2000 1X EV-DO.
3. GSM air interface data rate is 270Kbps and 3G allows a minimum of 2Mbps downlink in stationary mobile and 384Kbps while moving.
4. A5 ciphering algorithm is used in 2G and a more secured KASUMI encryption is used in 3G mobile communication in authentication process.
5. 2G uses channel bandwidth of 200 kHz for voice transmission and 3G uses 1.25 MHz channel.