Classification of Wireless Systems

First Generation Analog Wireless Systems

• The First generation of wireless telecommunication technology is known as 1G was introduced in 1980.
• The main difference between then existing systems and 1G was invent of cellular technology and hence it is also known as First generation of analog cellular telephone.
• In 1G or First generation of wireless telecommunication technology the network contains  many cells (Land area was divided into small sectors, each sector is known as cell, a cell is covered by a radio network with one transceiver) and so same frequency can be reused many times which results in great spectrum usage and thus increased the system capacity i.e. large number of users could be accommodated easily.
• The First generation of wireless telecommunication technology used analog transmission techniques which were basically used for transmitting voice signals.
• 1G or  first generation of wireless telecommunication technology also consist of various standards among which most popular were Advance Mobile Phone Service (AMPS), Nordic Mobile Telephone (NMT), Total Access Communication System (TACS).
• All of the standards in 1G use frequency modulation techniques for voice signals and all the handover decisions were taken at the Base Stations (BS).
• The spectrum within cell was divided into number of channels and every call is allotted a dedicated pair of channels. Data transmission between the wire part of connection and PSTN (Packet Switched Telephone Network) was done using packet-switched network.

Second  Generation Digital  Wireless Systems

• Second-generation (2G) digital cellular systems constitute the majority of cellular communication infrastructures deployed today.
• 2G systems such as Global System for Mobile communication(GSM), whose rollout started in 1987, signaled a major shift in the way mobile communications is used worldwide.
• In part they helped fuel the transition of a mobile phone from luxury to necessity and helped to drive subscriber costs down by more efficient utilization of air interface and volume deployment of infrastructure components and handsets.

Third Generation Wireless Systems

• 3rd Generation Mobile Telecommunications (3G), is a set of standards that came about as a result of the International Telecommunication Union’s (ITU) initiative known as IMT-2000 (International Mobile Telecommunications-2000).
• 3G systems are expected to deliver quality multimedia to mobile devices by way of faster and easier wireless communications as well as “anytime, anywhere” services.
  This term is also known as 3^rd generation mobile telecommunications.

Written By A.Devasena

Associate Professor/ ECE Dept.