MS

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 Mobile Station: 

MS provide radio and processing function which allow subscriber to access the mobile network via the air interface. subscriber-related information is stored on a specific device call a SIM. The SIM is a removable smart card that conforms to internationally recognized standards. it contains the IMSI. this is used by the network operator to identify the subscriber in the network and to provide security and protection against misuse. Each mobile station has it own IMEI. The IMEI is used by the network operator to prevent stolen or non-type approved mobile station from accessing the network.

there are three type of mobile station in GSM network:

1. Phase I
2. Phase I extended
3. phase II

 FI on GPRS mobile stations, refer to gprs elements. MS have different capability according to the class of mobile station and the purpose for which the mobile station was designed. these differences include power output and ciphering. 
Only phase II mobile stations can turn off ciphering, or change the ciphering mode, during a channel change procedure such as a handover. the ciphering capability of a mobile station is signaled to the BSS in the mobile station class-mark..

Ciphering is used to protect information transmitted on the air interface. this is performed between the BTS and the MS. Transmission ciphering does not depend on the type of data to  be transmitted, but on normal transmission bursts.

Mobile Station Idle Mode

A MS is in idle mode when it is switched on, but not communicating with the network on an SDCCH channel or a TCH.

There are support four idle mode functions:

1. Cell selection and cell reselection
2. GPRS/GSM to UMTS cell reselection
3. Overload control
4. Location Updating

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MS: Mobile Station is the equipment that can receive signal from BTS and can send uplink back to BTS and also can measurement signal strength to outgoing handover.

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