19-06-2014, 12:49 PM
GSM Architecture
GSM Architecture.ppt (Size: 1.39 MB / Downloads: 126)
Network Structure
A cell is the basic unit of a cellular system and is defined as the radio coverage given by one BTS
LOCATION AREA
A LA is defined as a group of cells.Within the network, a subsriber’s location is known by the LA which they are in.
The identity of the LA in which an MS is currently located is stored in the VLR. (LAI)
MSC Service Area
An MSC Service Area is made up of LAs and represents the geographical part of the network controlled by one MSC
PLMN SERVICE AREA[/b]
A PLMN service area is the entire set of cells served by one network operator
and is defined as the area in which an operator offers radio coverage and access to its network
GSM SERVICE AREA
The GSM service area is the entire geographical area in which a subscriber can gain access to a GSM network
Functions of Mobile Station
Voice and data transmission & receipt
Frequency and time synchronization
Monitoring of power and signal quality of the surrounding cells
Provision of location updates even during inactive state
Mobile Station
Can receive, store, send SMS up to 160 characters.
MS identified by unique IMEI shown on pressing *#06#.
Power levels of 20W, 8W, 5W, 2W and .8W
Temporary Mobile subscriber Identity
TMSI is a temporary IMSI no. made known to an MS at registration.
The VLR assigns a TMSI to each mobile subscribers entering the VLR area.
Assigned only after successful authentication.
[b]Transcoder
Is a device that takes 13 KBPS speech data and multiplexes four of them into standard 64 Kbps data
VISITOR LOCATION REGISTER (VLR)
It contains data of all mobiles roaming in its area.
One VLR may be incharge of one or more LA.
VLR is updated by HLR on entry of MS its area.
VLR assigns TMSI which keeps on changing.
Operations and Maintenance Centre OMC
The centralized operation of the various units in the system and functions needed to maintain the subsystems.
Dynamic monitoring and controlling of the network