ABBAS ACADEMY: Renewable Energy Sources & Telecom Tower Business in India -- Part-I

Basic Overview of Mobile Technology and Components

Mobile Phone Technology:

There are two basic technologies in the mobile phones. These are GSM and CDMA. GSM stands for Global System for Mobiles while CDMA stands for Code Division Multiple Access. GSM comes from Industry consortium whereas CDMA is owned by chipmaker Qualcomm. CDMA and GSM are both multiple access technologies. GSM came first, and it is ‘Time Division’ system. CDMA is a ‘Code Division’ system. [1]

Prominent Mobile Service Providers or Operators in India are:

CDMA Operator: Tata Teleservices, Reliance Communications, BSNL, MTNL

GSM Operator: Airtel, Vodafone, Idea Cellular, BSNL, MTNL

Key Elements of a GSM Network:

Fig: components of GSM Network[2]

A GSM network is a complex system composed by several components. The last mile of this system is the BTS (Base Transceiver Station). The BTS is responsible to transmit and receive the RF (Radio Frequency) signals to the user terminal (cell phone, PDA, modem, etc). The BTS’s are controlled by a BSC (Base Station Controller) that is connected to the MSC/VLR (Mobile Switching Center/Visitor Location Register). Basically, the MSC/VLR is responsible to authenticate the user against the database (HLR - Home Location Register, AuC - Authentication Center).[3]

Cell site: Telecom Tower and BTS

Cell site consists of Mast Telecom Tower and BTS. Physical structure which hosts the antenna equipment needed for broadcasting the operators’ network signal is referred as Mast/Telecom Tower. The equipment cabinet that houses the electronics and system necessary for the transmission and reception of signals between the network and the subscriber is called Base Transceiver Station (BTS).[4]

A cell site has active and passive infrastructure components. Active component includes the antenna, transceivers, feeder cables and microwave radio equipments. Passive components include the land, tower, shelter, air conditioning equipment, diesel electric generator, battery, electrical supply, technical premises and easements etc.[5]

Fig.: Cell site components

BTS Configuration:

Depending upon number of subscribers and type of BTS, BTS configuration can be 2,2,2 or 4,4,4 or 6,6,6…

Eg 2,2,2 is the two trx cards for each sector, and there are three sectors in BTS.[6]

The antennas on the cell tower are always arranged in a triangle. Each of the three antenna arrays covers a 120^osector with tower at its focus. By convention these sectors are referred as alpha, beta and gamma.[7]

Microwave Antenna and GSM Antenna

Microwave Antennas are used for link between BTS whereas GSM antennas are directly link with customers.