GSM Architecture basic for mobile communication
|Gsm Architecture basic for mobile communication|
GSM stand for Global system for mobile if we are discussing about GSM architecture means we are talking about 2G technology architecture you should remember this point telecom evolution has brought advance technology 3G,4G LTE but here we are talking about GSM architecture simple means we are talking about 2G architecture latter on we will discuss about 3G and 4G LTE architecture step by step so that you can understand better GSM architecture is road map for other advance technology 3G and 4G LTE so it is very important to understand first GSM architecture then other advance technology architecture will become easy to understand.
MS- mobile station is your mobile phone if it support GSM architecture then there will be two things one is your mobile equipment and other is your SIM card SIM(subscriber identity module) only your mobile equipment is not called mobile station it must contain with a valid SIM card activated and connected with network then MS is called mobile station.
BTS– base transceiver station this is a hardware installed near mobile tower you generally see mobile tower on ground and roof where BTS is installed and connected by GSM antenna through coaxial feeder cable this GSM antenna is installed on height of tower now mobile station is connected with near your BTS location.
BTS functionality it is clear from its name transceiver means can transfer the call and receive the call hence it receives the call from MS and forwarded to BSC and it receive the call from BSC and forwarded to MS hence it is interface between MS and BSC apart from this BTS do many work like encrypt, encoding, multiplexing, modulate the signal, frequency hopping,establish call between MS and BSC.
BSC- base station controller is connected with many BTS and manage all BTS request in a local town or city one BSC has many BTS connected its depends upon the BSC capacity but its main function is to manage or control all BTS request and communicate with MSC forward request to MSC and receive request from MSC its one important work is to handover the calls among the BTS suppose you are talking on mobile phone and moving from one location to other location then your call handover always BTS near to you for better voice quality without call drop this important work done by BSC handle handover from one BTS to other BTS apart from this BSC manage all radio resources means when you talk then some channel is allocated to you without channel communication is not possible hence BSC manage radio resource channels like which channel is free which channel need to assign any particular user this all is manage by BSC it also help to call setup with MSC.
MSC- mobile switching center it contains many BSC one MSC can control many MSC depend upon MSC capacity it is hardcore network if any user call other user and suppose your call request is not reaching up to MSC then your call will never be establish hence its important function is call setup and call routing even your billing, channel allocation is done by MSC sometime you try to call your friends and a message you got all lines of this route are busy this message initiated by MSC because MSC send a alert that all channel are in use or busy even this message can be initiated by BSC also if all channel are busy in BSC both has this message alert option MSC has many other work caller tune message is stored in MSC, user location update continuously in HLR and VLR .
HLR- home location register store the important data IMSI (international mobile subscriber identity unique number identity) number, MSISDN number ( this is your mobile number ), subscriber identification data, supplementary services call waiting, subscriber status it is a permanent memory where your data is permanently stored, authentication key.
VLR- visitor location register this is a temporary memory where user data is copy from HLR when user is in other location area from his registered location area that is called roaming suppose you have purchased your SIM in Delhi then your home location register is in Delhi if you move to other state Mumbai then you will be in roaming your mobile will not stop working a copy of HLR information from Delhi will send to Mumbai HLR you will avail all facility but according to roaming Mumbai is your VLR current location update is saved in VLR.
AUC – authentication center validate the customer identification as well as its balance is available or not, prepaid, postpaid customer, customer is blocked for particular services.
EIR: equipment identity register IMEI (International mobile equipment identity) there are three types of list saved in EIR one is white list second is gray list and third is black list suppose you have purchased your phone on your name then you list will be in white list now which mobile stolen and complaint raised FIR police is searching that IMEI number it save under gray list now which mobile stolen and police not found if you want to black list that IMEI number so that no anyone can use this mobile in network if black listed IMEI number then it will not work in network.
GMSC: gateway MSC work for communication from one circle to other circle means one state to other state or one network to other network like Airtel to Vodafone then all call will route through GMSC.
PSTN: public switched telephone network allow users to make landline telephone calls to another the call is placed after it is routed through multiples switching.
now this is all about GSM architecture we will continue in next post more about telecommunication i hope you have enjoyed learning GSM Architecture thanks for reading and sharing with others keep reading more and more for better tomorrow.
Dated 30th Sep 2018.