WIRELESS COMMUNICATION TECHNOLOGIES

WIRELESS COMMUNICATION
CELLULAR COMMUNICATION GENERATIONS

• 1G(first generation)

It is the 1st generation of wireless telephony cellphones.These are the analog cellphone standards that were introduced in the 1980s and continued untill replaced by 2G digital cellphones. 1G signals were modulated to higher frequency(typically 150MHz and up).Following are the 1G mobile phone standards:

1.NMT

2.AMPS

3CDPD

• 2G (Second Generation cellular networks)

STANDARDs

GSM: It supports 8 time slotted users for each 200KHz radio channel and employed in whole world.

IS-136: It supports 3 slootted users for each 30KHz radio channel.It is mostly used in North America, South America, Australia.

PDC: It is similar to IS-136 but it is Japaneese TDMA standard.

CDMA:(IS-95) It supports 64 users that are orthogonally coded and simultanously transmitted on each 1.25MHz channel.It is mainly used in North America,Korea, Japan,China, India.

2G networks have the data transfer speed ranging from 9Kbps to 14Kbps.They are used only for voice communication & SMSing.

EVOLUTION OF 2.5G:

In the year 1999 internet was made available on cellphones under he standard called 2.5G or GPRS(General packet for radio services).It increased the data transfer speed up to 53Kbps.Now data transfer services like e-mailing, www viewing, fax were available on cellphones.

EVOLUTION OF 2.75G:

Speed of 53was not enough for voice & video content from internet.So a new standard came in 2001 which allowed data transfer with speed of upto 236Kbps.It is also called EDGE.It alowed transmission of voice and video over internet.

• 3G(Third Generation cellular network):

It's standard was presnted by ITU-T and is known as IMT-2000.It is adopted by whole world.But 3G came into act before this was established . In the year 2005 JAPAN was the first to adopted 3G.In India it came in to act in August 2008. Third generation cellular networks provide speed of upto 2Mbps.Now we can also enjoy online voice & video chatting, Live TV, online gaming,video conferencing and many more services on our 3G enabled handset.