Traditional wireless mobile communication

WIRELESS COMMUNICATION

Traditional wireless mobile communication

A Cellular device today has become unthinkingly an extension of our anthropological arms that has endowed us with an added means of communication, which we term as wireless communication or mobile telecommunication.

GSM system can be dissected into three main subsystems: Radio subsystem, Network subsystem, and Operation subsystem.

 RADIO SUBSYSTEM –

• The Mobile station (MS) is the user equipment, essentially our cellphones in hardware and the SIM as part of the software. 
• The SIM card is the soul of communication for our device and contains all the user-specific data such as serial number, card type, PIN, authentication key, PIN unblocking key, International Mobile Subscriber Identity (IMSI), and list of subscribed services.
• The MS also stores dynamic data required for wireless communication such as location information and a cipher key for encryption and decryption.

• The Base station system (BSS) is mainly responsible for maintaining the radio connection to the MS and performing coding and decoding of the voice communication. 
• Now, the BSS is able to do this with the help of radio equipment such as antennas, amplifiers and signal processors, which we see as the cell tower, officially termed as the Base Transceiver Station (BTS).
•  Each BTS acts within a radius or cell region and there are several BTSs and BSSs, each controlled by a Base Station Controller (BSC). The BSC is the prime manager of the BTS. 
• It designates radio frequencies for communication and performs handover from one BTS to another within the BSS when the MS signal is weak.

Network Subsystem –


This part of the communication system is another level up and handles the handover from one BSS to another. This enables what we know as national and international roaming. This handover is performed by the MSC or the Mobile Switching Center. The MSC is aware of the subscriber location via its databases- the Home Location Register (HLR) and Visitor Location Register (VLR).