Learn about GSM architecture in 5 minutes

GSM Architecture. ( This lesson is for the students of MBA, MCA Courses)


Q) Define GSM architecture?

• There are three subsystem comes in GSM architecture:-
1. A radio subsystem (RSS).
2. Network and switching subsystem (NSS).
3. The operation subsystem (OSS).

Q2. Define radio subsystem?

• Radio subsystem includes BSS, BTS, BSC and MS.
• The BSS perform all function necessary to maintain radio connection to an MS, coding decoding of voice. The VSS contain several BTS.
• BTS (Base transiver subsystem) having all radio equipment that is antenna, signal processing, amplifiers necessary for radio transmission.
• The BSC manages the BTS. It reverse radio frequency, handle the handover from one BTS to another within the BS.
• MS includes all over equipments. The MS consists of the SIM (Subscriber identification module) which store all user specific data. MS can identify through IMEI (International mobile equipment identify) without SIM only emergency call are possible. The SIM contain CARD type, serial number a list of subscriber services, a pin & a PUK, an authorization key & the IMSI(International mobile subscriber identity) pin is used to unlock the MS, using the wrong PIN three time will lock the SIM then the PUK is needed to unlock the SIM.

Q3. Define Network and switching subsystem?

• The heart of the GSM system is found by network and switching subsystem includes MSC, HLR, and VLR.
• MSC: - MSC are high performance digital ISDN switches. An MSC manages several BSC.
• HLR: - The most important database stored all user related information such as MS-ISDN (mobile subscriber ISDN number), IMSI and also the current location of MS, MSRN (mobile subscriber roaming number) the current VLR and MSC.
• VLR: - It is a dynamic database which stored all important information needed for the MS user currently in the location area that is associated to the MSC.

Q4 Define operating subsystem?

• It contains necessary function for network.
• OMC (operation and maintenance center):- It monitors and controls all other network entities. Its function is traffic monitoring, static’s report of network entity, subscriber and security management and billing.
• AVC (Authentication center):- A separate AVC has been defined to protect user identify and data transmission. The AVC contains algorithm for authentication as well as key for encryption.
• EIR (Encryption identification register):- It stores all the device identification register for a network. As mobile station are mobiles, they can be stolen with a valid SIM anyone can use the stolen MS. The EIR has a black list of stolen device as the MS is useless as soon as the owner as reported. The EIR also contain a list of valid IMEI (white list).

Q5. What are the different types of Handover in GSM?

• There are basically four types of Handover in GSM:-
1. Intra cell handover.
2. Inter cell, Intra BSC handover.
3. Inter BSC, Intra MSC handover.
4. Inter MSC handover.