Architecture
What three subsytems comprise the GSM network?
Mobile Station, Base Station Subsystem, Network Switching Subsystem.
What is used to mask the IMSI on the radio interface?
The Temporary Mobile Subscriber Identity (TMSI).
What does GSM stand for?
Global System for Mobile Telecommunications.
Which database stores encryption keys and algorithms?
Authentication Center (AUC).
What identity is assigned by the GSMC and is used to route calls to external networks?
Mobile Station Roaming Number (MSRN).
What is the Mobile Station comprised of?
Mobile Equipment and the Subscriber Identity Module.
What is a phone number called in GSM?
Mobile Station International Subscriber Director Number (MSISDN)
What does IMEI stand for?
International Mobile Equipment Identifier.
The MSC controls a geographic region called what?
Location Area (LAC).
What does an MS use to determine which towers it can connect with?
Preferred Roaming List (PRL) or Public Land Mobile Network Code (PLMN).
Where is the Preferred Roaming List stored?
Subscriber Identity Module (SIM).
What type of modulation does GSM use?
Gaussian Minimum Shift Keying (GMSK).
How many digits is an IMEI?
15
How many timeslots does GSM use?
8.
What two messages can the AGCH carry?
Immediate Assignment or Immediate Reject.
What are the three components of an IMSI?
Mobile Country Code (MCC), Mobile Network Code (MNC), Mobile Subscriber Identity Number (MSIN).
What multiple access schemes does GSM use?
Frequency Division Multiple Access (FDMA), Time Division Multiple Access (TDMA).
Explain the makeup of an IMEI after 2003.
8 Digit Type Allocation Code (TAC), 6 Digit Serial Number (SN), 1 Digit Check Digit (CD).
What is the bandwidth of a GSM channel?
200 kHz.
What timeslot are Common Control Channels sent on?
TS 0.
What are the elements of the Base Station Subsystem?
Base Transceiver Station (BTS), Base Station Controller (BSC).
Describe TDMA.
Time Division Multiple Access. Users are divided by timeslots on the same frequency.
What can be learned from the first 8 digits of an IMEI.
Make and Model (From the TAC).
What is used to ensure a signal arrives in its proper timeslot?
Timing Advance.
GSM Channels are called what?
Absolute Radio Frequency Channel Number (ARFCN).