As the Cellular systems improvised with respect to voice quality and data rate, they were categorized into generations. In this section, the main features of all generations are described.

A. First Generation (1G): These phones were the first mobile phones to be used, which was introduced in 1982 and completed in early 1990. It was used for voice services and was based on AMPS. The AMPS system was frequency modulated and used frequency division multiple access (FDMA) with a channel capacity of 30 KHz and frequency band of 824- 894MHz. Its basic features were:

• Use analog signal
• Poor voice quality
• Poor battery life
• Large phone size
• Limited capacity
• Poor security
• Offered very low level of spectrum efficiency

It introduced mobile technologies such as Mobile Telephone System (MTS), Advanced Mobile Telephone System (AMTS), Improved Mobile Telephone Service (IMTS), and Push to Talk (PTT). It had no security at all since voice calls were played back in radio towers, making these calls susceptible to unwanted eavesdropping by third parties.

B. Second Generation (2G): 2G refers to the second generation based on GSM and was emerged in late 1980s. It uses digital signals for voice transmission. Main focus of this technology was on digital signals and it also provides services to deliver text and picture message at low speed (in Kbps). It uses the bandwidth of 30 to 200 KHz. The main features of 2G are :

• Data speed: upto 9.6 Kbps to 14.4 Kbps.
• Use digital signals
• Enables services such as text messages
• Provides better quality and capacity
• Unable to handle complex data such as videos

C. 2.5 G and 2.75 G: The GSM technology was continuously modified and improvised to provide better services which led to development of advanced technologies between 2G and 3G. Next to 2G, 2.5G and then 2.75 G system uses packet switched and circuit switched domain and provides data rate up to 384 kbps. e.g. GPRS , EDGE and IS95B. It’s features are:

• Totally digital and packet switched
• Send/receive e-mail messages
• Web browsing
• Speed : 64-384 Kbps
• Camera phones
• Take a time of 6-9 mins. to download a 3 mins. MP3 song.

D. Third Generation (3G): 3G is based on GSM and was launched in 2000. The aim of this technology was to offer high speed data. The original technology was improved to allow data up to 14 Mbps and more using packet switching. It also offers data services, access to television/video, new services like Global Roaming. It operates at a range of 2100MHz and has a bandwidth of 5-20MHz used for High-speed internet service, video chatting. 3G mobile system is called as UMTS (Universal Mobile Telecommunication System) in Europe, while CDMA2000 is the name of American 3G variant.

The main features of 3G are:

• Speed: 2 Mbps, hence provides faster communication
• Typically, the devices are called smart phones
• Increased bandwidth and data transfer rates to accommodate web-based applications and audio and video files.
• Provides faster communication
• High speed web/more security/video conferencing/3D gaming
• Large capacities and broadband capabilities ( To download a 3 minute MP3 song only 11 sec-1.5 mins time required. )
• TV streaming/mobile TV/Phone calls
• Expensive fees for 3G licenses services
• It was challenge to build the infrastructure for 3G
• High bandwidth requirement
• Expensive 3G handsets

E. Fourth Generation (4G): 4G offers a downloading speed of 100Mbps. 4G provides same feature as 3G and additional services like Multi-Media Newspapers, to watch T.V programs with more clarity and send data much faster than previous generations . LTE (Long Term Evolution) is considered as 4G technology. 4G is being developed to accommodate the (Quality of Service) QoS and rate requirements set by forthcoming applications like wireless broadband access, Multimedia Messaging Service (MMS), video chat, mobile TV, HDTV content, Digital Video Broadcasting (DVB), minimal services like voice and data, and other services that utilize bandwidth.

The main features of 4G are:

• Speed: 10Mbps-1Gbps
• High quality streaming video
• High security
• Provide any kind of service at any time as per user requirements anywhere
• Expanded multimedia services
• Complex to implement
• Need complicated hardware
• Expensive equipments required to implement next generation network

F. Fifth Generation (5G): 5G refers to Fifth Generation which started from late 2010s. Facilities that might be seen with 5G technology includes far better levels of connectivity and coverage. The main focus of 5G will be on world-Wireless World Wide Web (WWWW). It is a complete wireless communication with no limitations. The main features of 5G are :

• It is highly supportable to WWWW (wireless World Wide Web)
• High speed, high capacity
• Provides large broadcasting of data in Gbps
• Multi-media newspapers, watch TV programs with the clarity (HD Clarity)
• Faster data transmission that of the previous generation
• Large phone memory, dialing speed, clarity in audio/video
• Support interactive multimedia, voice, streaming video, internet and other