Wireless technology has transformed our lives in many ways. Until very recently, we needed a computer wired to a port, to get online. Even wired telephones are becoming a thing of past. Nowadays, we use our mobile phones for banking, to check ticket availability at a Cinema Hall, and many more. Wireless communication is the transfer of information over a distance without the use of enhanced electrical conductors or "wires”. And, Wireless networking refers to any kind of networking that does not involve cables. It helps in saving the cost of cables for networking in addition to providing the mobility.
There are different types of wireless networks defined on the basis of their size, range and data transfer rate.
· Wireless PAN - Personal area network Wireless Personal Area Networks
· Wireless LAN - Local Area Network
· Wireless MAN - Metropolitan Area Networks
· Wireless WAN- Wide Area Networks
· Mobile devices networks
Mobile networks have evolved tremendously in last 3 decades. Cellular concept was introduced with 1G (‘G’ stands for generation) networks. Today, 4G technology is getting ready to storm the markets. Not only that, research on 5G technology has already begun.
Evolution of Mobile Technologies
Zero Generation Technology (0G)
0G refers to pre-cell phone mobile telephony. Being the predecessors of the first generation of cellular telephones, these systems are called 0G (zero generation) systems. Usually vehicle mounted, they had the transceivers mounted in the vehicle trunk and dials & display mounted near the driver seat.
Technologies used in 0G systems included PTT (Push to Talk), MTS (Mobile Telephone System), IMTS (Improved Mobile Telephone Service), and AMTS (Advanced Mobile Telephone System).
First Generation Technology (1G)
1G refers to the first generation of wireless telecommunication technology, more popularly known as cell phones. In 1G, Narrow band analogue wireless network is used; with this we can have the voice calls. These services are provided with circuit switching. Through 1G, a voice call gets modulated to a higher frequency of about 150MHz and up as it is transmitted between radio towers using a technique called Frequency-Division Multiple Access (FDMA).
Different 1G standards prevalent were AMPS (Advanced Mobile Phone System) in the United States, TACS (Total Access Communications System) in the United Kingdom, NMT (Nordic Mobile Telephone), used in Nordic countries, Eastern Europe and Russia, etc.
Second Generation Technology
2G - 2G first appeared around late 1980’s; 2G system digitized the voice signal, as well as the control link. It provided the facility of short message service (SMS) unlike 1G that had its prime focus on verbal communication. Depending on the type of multiplexing used 2G technologies can be divided into Time Division Multiple Access (TDMA) based and Code Division Multiple Access (CDMA). 2G system offered better quality and much more capacity. 2G cellphone units were generally smaller than 1G units, since they emitted less radio power.
Based on TDMA, Global System for Mobile communications (GSM) is the first European standard & the first commercial network for use by the public for 2nd generation mobile (2G) telephony. A typical 2G G.S.M network service uses 800/900MHz or 1800/1900 frequency spectrum. Typical average data rate of GSM is 9.6 kbps. 2G CDMA (IS-95A) uses BPSK and offers data rate upto 14.4 kbps. The bandwidth of 2G is 30-200 KHz.
2.5G – GPRS (General Packet Radio Service) - 2.5G, which stands for "second and a half generation," is a cellular wireless technology developed in between its predecessor, 2G, and its successor, 3G. The term "second and a half generation" is used to describe 2G-systems that have implemented a packet switched domain in addition to the circuit switched domain.
‘2.5G’ is an informal term, invented solely for marketing purposes, unlike "2G" or "3G" which are officially defined standards based on those defined by the International Telecommunication (ITU).
GPRS (CS1 to CS4) uses GMSK modulation with symbol rate (& modulation rate) of 270 ksym/s. Typical data rate of GPRS is ~115 kbps. It can be used for services such as Wireless Application Protocol (WAP) access, Multimedia Messaging Service (MMS) and for accessing internet.
IS-95B or cdmaOne is the evolved version of IS-95A and is also designated as 2.5G with theoretical data rates of upto 115 kbps, with generally experienced rates of 64 kbps.
2.75 – EDGE (Enhanced Data rates for GSM Evolution) - EDGE (EGPRS) is an abbreviation for Enhanced Data rates for GSM Evolution, is a digital mobile phone technology, invented by AT&T. EDGE technology is an extended version of GSM & works in GSM networks. EDGE is add-on to GPRS and can function on any network with GPRS deployed on it, provided the carrier implements the necessary upgrades. It allows the clear and fast transmission of data. One need not install any additional hardware and software in order to make use of EDGE Technology. Also, there are no additional charges for utilizing this technology.
Uses 9 Modulation coding schemes (MCS1-9). MCS (1-4) uses GMSK, while MCS (5-9) uses 8PSK modulation. 8PSK Increases throughput by 3x (8-PSK – 3 bits/symbol vs GMSK 1 bit/symbol). Modulation bit rate is 810 kbps. It offers data rates of 384kbps, theoretically up to 473.6kbps.