This glossary provides definitions for common terms related to GSM (Global System for Mobile communications) technology.

A

• A5/1: A stream cipher used to provide over-the-air communication privacy in GSM.
• Authentication Center (AuC): A database that stores subscriber authentication information and generates keys for encryption.

B

• Base Station Controller (BSC): Controls multiple Base Transceiver Stations (BTS) and manages radio resources.
• Base Transceiver Station (BTS): The radio equipment that communicates with mobile phones.
• Burst: A short time slot used for transmission in GSM.

• Base Station Subsystem (BSS): Comprises the Base Station Controller (BSC) and Base Transceiver Stations (BTS). ##C

• Cell: A geographical area covered by a single Base Transceiver Station (BTS).
• Cipher: An algorithm used for encryption or decryption.
• Companding: A technique used to compress and expand audio signals to improve dynamic range.

  E

• Encryption: The process of converting information into a secret code to protect it from unauthorized access.
• Equipment Identity Register (EIR): A database that stores information about mobile equipment, such as IMEI numbers.

  F

• Frequency Hopping: A technique used to avoid interference by changing the transmission frequency rapidly.
• Full-rate Codec: A speech codec used in GSM that provides higher quality audio compared to half-rate codecs.

  G

• GPRS (General Packet Radio Service): A packet-switched data service that provides higher data rates than traditional GSM.
• GSM (Global System for Mobile communications): A standard for digital mobile communication.

  H

• Half-rate Codec: A speech codec used in GSM that provides lower quality audio but uses less bandwidth.
• Home Location Register (HLR): A central database that stores subscriber information, such as phone numbers and service subscriptions.

  I

• IMEI (International Mobile Equipment Identity): A unique number that identifies a mobile device.
• IMSI (International Mobile Subscriber Identity): A unique number that identifies a GSM subscriber.

  K

• Ki: A secret key used for subscriber authentication.

  L

• Location Area: A group of cells that are served by a single Visitor Location Register (VLR).

  M

• Mobile Switching Center (MSC): The central switching element in a GSM network that handles call routing and mobility management.
• MSISDN (Mobile Station ISDN Number): The phone number of a mobile subscriber.

  N

• Network Subsystem: The core network of a GSM system, responsible for call routing, mobility management, and other network functions.

  P

• Paging: The process of alerting a mobile phone that there is an incoming call or message.

  R

• Roaming: The ability to use a mobile phone on a different network than the one it is subscribed to.

  S

• SIM (Subscriber Identity Module): A smart card that stores subscriber information and authentication keys.
• Short Message Service (SMS): A service for sending and receiving text messages.

  T

• TDMA (Time Division Multiple Access): A multiple access technique used in GSM where multiple users share the same frequency channel by dividing it into time slots.
• TMSI (Temporary Mobile Subscriber Identity): A temporary identifier assigned to a mobile subscriber to protect their privacy.

  V

• Visitor Location Register (VLR): A database that stores information about mobile subscribers who are currently located in a particular area.

This glossary is not exhaustive, but it covers some of the most important terms related to GSM.