Wireless Mobile Communication:
Mobile communication is one of the hottest and continuously increasing areas that are improving and becoming advanced at a booming speed, along with upcoming advanced techniques appearing within all the fields of mobile and the wireless communications. There is a phenomenal growth in the wireless communication techniques and also in the subscribers. Mobile wireless technology industry has been started in the early 1970’s. This technology has offered us with lot many technologies like Constant connection, mobility, access to upto date information, freedom to roam, better connection and many more benefits as the technology has been enhanced.
We have witnessed wireless communications starting from the first generation upto the fourth generation (that is not yet been developed to estimated rate).Sri-Lanka is the first country to adopt the fourth generation within their communication range.
Fifth generation is paving the way to achieve more intelligent technology that interconnects the entire world.
Analyzing the different generations:
First Generation (1G):
This wireless generation was developed in1980’s. The mobile communication based upon the first generation approach uses the analog signalling technique. The main technology upon which the 1G was based, named as the AMPS: Advanced Mobile Phone System network. AMPS tech. was voice-only network, which is operating on the 800MHz band. Being a primitive radio technology, AMPS functions in similar manner just as a regular radio transmission, just like the UHF radio, where 800MHz band was divided into number of channels (395 voices, 21 controls) through FDMA (Frequency Division Multiple Access). Every channel was 30 KHz wide and was able to support only one user at a time, states that the maximum number of mobile phone users per cell tower was 395. Tower assessed the signal strength of each user and allocated the channels dynamically, assuring that the channels could be reused by different towers without interference.
Limitations:
a) 1G mostly focuses upon the voice only, and data services were almost non-existent.
b) Incompatible standards:-
i) Different frequency and signalling.
ii) International roaming was impossible.
c) Low capacity and unreliable hand-off.
Second Generations (2G):
Second generation was a step ahead of 1G, started in the late 1980’s. It was planned mainly for voice transmission along with digital signal. Unlike 1G, 2G provides the facility of short message transfer (SMS) along with the voice call. The bandwidth of 2G is 30-200 KHz. During 2nd generations, there was an exponential growth in subscribers and value added services. Second generations also introduced the GSM technology, GSM or global system for mobile communication uses the digital modulation in order to improve the quality of voice; however it offers limited data service. As the demand increases, 2G starts to improve and begin to provide more value added services like voice message, text messages, and voice-mail.
Intermediate 2.5G:
2.5G wireless technology is considered as a stepping stone which bridged the 2G to 3G wireless technology. It utilizes the GPRS technology that delivers packet-switched data capabilities to the existing GSM networks. EDGE is a superset to the GPRS, and can function on any network with GPRS deployed on it. EDGE provides a three-fold increase in the capacity of the GSM/GPRS networks.
Third Generations (3G):
Third generation was introduced in the 2004-05; its advent has introduced the clarity, highly sophisticated form of communication. It is based upon the wide band wireless network fulfilling the specifications of the International Mobile Telecommunicaitons-2000 (IMT-2000). This generation function in the range of 2100 Hz and bandwidth of 5-20 MHz Recent 3G has provided mobile broadband access of various M bit/s to smart phones and mobile modems in laptop computers. Data rate of 3G is upto 2/mbps.
Benefits of the 3G:
a) Phone calls/fax.
b) Send/ receive large email messages.
c) Capability to support circuit and packet data at high bit rates.
d) Support of multimedia services/capabilities.
e) It also provides facility of videoconferencing.
There exist two prominent radio transmission standards approved for 3G:
a) W-CDMA: Wireless Code Division Multiple is an interface standards found within 3G technologies. It uses FDD duplexing method supporting many users in comparison to the TDMA.
b) CDMA 2000: It uses CDMA channel access to send voices data and signalling data between mobile phones and cell sites. It is also known as CDMA mutli-carrier.
Fourth Generations (4G):
It is a wireless access technology and a successor of 3G. It has a transmission rate upto 20 Mbps higher in comparison to the 3G. It also provides high downloading speed of about 100 Mbps. It has many more advanced features to offer. However, we are in a transition period between 2G and 3G technology. 4G has a long way to come up.