Wireless & Mobile Communications Multiple Choice Questions on “GSM Channel Types”.
1. __________ carries digitally encoded user data.
a) Traffic channels
b) Control channels
c) Signalling channels
d) Forward channels
Answer: a
Clarification: Traffic channels carry digitally encoded user speech or user data. It has identical functions and formats on both the forward and reverse links.
2. ____________ carries signalling and synchronizing commands.
a) Traffic channels
b) Control channels
c) Signalling channels
d) Forward channels
Answer: b
Clarification: Control channels carry signalling and synchronizing commands between the base station and mobile station. Certain types of control channels are defined for just the forward or reverse link.
3. Which of the following is not a control channel of GSM?
a) BCH
b) CCCH
c) DCCH
d) TCH
Answer: d
Clarification: There are three main control channels in the GSM system. These are the broadcast channel (BCH), the common control channel (CCCH) and the dedicated control channel (DCCH). Each control channel consists of several logical channels.
4. Which of the following is the forward control channel that is used to broadcast information?
a) BCCH
b) CCCH
c) DCCH
d) TCH
Answer: a
Clarification: The broadcast control channel (BCCH) is a forward channel that is used to broadcast information such as cell and network identity, and operating characteristics of the cell.
5. Which of the following channel does not come under CCCH?
a) PCH
b) RACH
c) DCCH
d) AGCH
Answer: c
Clarification: CCCH consists of three different channels. They are paging channel (PCH), which is a forward link channel, the random access channel (RACH) which is a reverse link channel, and the access grant channel (AGCH) which is a forward link channel.
6. Which of the following channel provides paging signals from base station to all mobiles in the cell?
a) RACH
b) AGCH
c) DCCH
d) PCH
Answer: d
Clarification: The PCH provides paging signals from the base station to all mobiles in the cell. It notifies a specific mobile of an incoming call which originates from the PSTN.
7. ___________ is a reverse link channel used by a subscriber unit to acknowledge.
a) RACH
b) AGCH
c) DCCH
d) PCH
Answer: a
Clarification: The RACH (Random Access Channel) is a reverse link channel used by a subscriber unit to acknowledge a page from the PCH. It is also used by mobiles to originate a call.
8. Which of the following channel is used by base station to provide forward link communication to mobile?
a) RACH
b) AGCH
c) DCCH
d) PCH
Answer: b
Clarification: The AGCH (Access Grant Channel) is used by the base station to provide forward link communication to the mobile. It carries data which instructs the mobile to operate in a particular physical channel with particular dedicated control channel.
9. Which of the following burst is used to broadcast the frequency and time synchronization control messages?
a) FCCH and SCH
b) TCH and DCCH
c) RACH and TCH
d) FCCH and DCCH
Answer: a
Clarification: FCCH and SCH burst are used to broadcast the frequency and time synchronization control messages. They are used in TS0 of specific frames.
10. Which of the following burst is used to access service from any base station?
a) TCH
b) RACH
c) SCH
d) FCCH
Answer: b
Clarification: Each user transmits a burst of data during the time slot assigned to it. The RACH burst is used by all mobiles to access service from any base station, and dummy burst is used as filter information for unused timeslots on forward link.
11. Group of superframes in GSM is called multiframe.
a) True
b) False
Answer: b
Clarification: Each of the normal speech frames are grouped into larger structures called multiframes. These multiframes are grouped into superframes and hyperframes.