NCS 20022101010 NCSS 2G RA OaM 2 2 Practice Exam
Question 1.Which interface connects the Mobile Station (MS) to the Base
Transceiver Station (BTS) in a GSM network?
A) Abis
B) A
C) Um
D) RAN
Answer: C
Explanation: The Um interface is the air interface between the MS and BTS,
carrying both signaling and traffic.
Question 2. What is the primary function of the Base Station Controller (BSC) in
the GSM Radio Access Network?
A) Manage subscriber billing records
B) Perform speech coding for voice calls
C) Control handovers and allocate radio resources
D) Store subscriber profiles
Answer: C
Explanation: The BSC manages radio resources, coordinates handovers, and
handles frequency allocation for the BTSs under its control.
Question 3.In GSM, which logical channel is used to broadcast the cell’s identity
and system information to all mobiles?
A) SDCCH
, NCS 20022101010 NCSS 2G RA OaM 2 2 Practice Exam
B) BCCH
C) TCH
D) PACCH
Answer: B
Explanation: The Broadcast Control Channel (BCCH) continuously transmits cell
identification, frequency list, and other system information.
Question 4.Which core network element is responsible for routing voice calls
between different MSCs and the Public Switched Telephone Network (PSTN)?
A) VLR
B) HLR
C) GMSC
D) BTS
Answer: C
Explanation: The Gateway Mobile Switching Center (GMSC) interfaces the GSM
network with the PSTN and other MSCs, routing inbound and outbound calls.
Question 5.What does the Home Location Register (HLR) store for each
subscriber?
A) Real‑time radio channel assignments
B) Permanent subscriber profile and service subscription data
C) Temporary visitor location information
D) Current battery level of the mobile device
, NCS 20022101010 NCSS 2G RA OaM 2 2 Practice Exam
Answer: B
Explanation: The HLR maintains the master subscriber record, including
authentication keys, service subscriptions, and billing information.
Question 6.In the GSM architecture, which component holds the temporary
subscriber data when a mobile roams into a foreign network?
A) HLR
B) VLR
C) MSC
D) BSC
Answer: B
Explanation: The Visitor Location Register (VLR) stores temporary location and
service data for roaming mobiles within its serving area.
Question 7.What is the purpose of the Transcoder and Rate Adaptation Unit
(TRAU) in a GSM BSS?
A) Convert analog RF signals to digital baseband
B) Perform voice compression and adapt data rates between the BTS and MSC
C) Manage handover decisions between cells
D) Store configuration files for the BSC
Answer: B
Explanation: TRAU performs speech coding/decoding and adapts the data rate of
traffic channels to match the MSC’s requirements.
, NCS 20022101010 NCSS 2G RA OaM 2 2 Practice Exam
Question 8.Which frequency reuse pattern is most commonly used in GSM to
minimize co‑channel interference?
A) 3/9
B) 1/1
C) 4/12
D) 7/21
Answer: D
Explanation: A 7/21 reuse pattern (seven cells per cluster, 21 available
frequencies) is standard in GSM planning to balance capacity and interference.
Question 9.What triggers an intra‑BSC handover in GSM?
A) A subscriber moving from one BSC’s coverage to another BSC’s coverage
B) A change in the subscriber’s tariff plan
C) Degradation of signal quality within the same BSC’s cells
D) A failure of the MSC
Answer: C
Explanation: Intra‑BSC handovers occur when a mobile’s signal quality
deteriorates and the BSC reassigns it to a neighboring cell under the same BSC.
Question 10.Which GSM logical channel carries signaling for call set‑up and SMS
messages?
A) TCH
Question 1.Which interface connects the Mobile Station (MS) to the Base
Transceiver Station (BTS) in a GSM network?
A) Abis
B) A
C) Um
D) RAN
Answer: C
Explanation: The Um interface is the air interface between the MS and BTS,
carrying both signaling and traffic.
Question 2. What is the primary function of the Base Station Controller (BSC) in
the GSM Radio Access Network?
A) Manage subscriber billing records
B) Perform speech coding for voice calls
C) Control handovers and allocate radio resources
D) Store subscriber profiles
Answer: C
Explanation: The BSC manages radio resources, coordinates handovers, and
handles frequency allocation for the BTSs under its control.
Question 3.In GSM, which logical channel is used to broadcast the cell’s identity
and system information to all mobiles?
A) SDCCH
, NCS 20022101010 NCSS 2G RA OaM 2 2 Practice Exam
B) BCCH
C) TCH
D) PACCH
Answer: B
Explanation: The Broadcast Control Channel (BCCH) continuously transmits cell
identification, frequency list, and other system information.
Question 4.Which core network element is responsible for routing voice calls
between different MSCs and the Public Switched Telephone Network (PSTN)?
A) VLR
B) HLR
C) GMSC
D) BTS
Answer: C
Explanation: The Gateway Mobile Switching Center (GMSC) interfaces the GSM
network with the PSTN and other MSCs, routing inbound and outbound calls.
Question 5.What does the Home Location Register (HLR) store for each
subscriber?
A) Real‑time radio channel assignments
B) Permanent subscriber profile and service subscription data
C) Temporary visitor location information
D) Current battery level of the mobile device
, NCS 20022101010 NCSS 2G RA OaM 2 2 Practice Exam
Answer: B
Explanation: The HLR maintains the master subscriber record, including
authentication keys, service subscriptions, and billing information.
Question 6.In the GSM architecture, which component holds the temporary
subscriber data when a mobile roams into a foreign network?
A) HLR
B) VLR
C) MSC
D) BSC
Answer: B
Explanation: The Visitor Location Register (VLR) stores temporary location and
service data for roaming mobiles within its serving area.
Question 7.What is the purpose of the Transcoder and Rate Adaptation Unit
(TRAU) in a GSM BSS?
A) Convert analog RF signals to digital baseband
B) Perform voice compression and adapt data rates between the BTS and MSC
C) Manage handover decisions between cells
D) Store configuration files for the BSC
Answer: B
Explanation: TRAU performs speech coding/decoding and adapts the data rate of
traffic channels to match the MSC’s requirements.
, NCS 20022101010 NCSS 2G RA OaM 2 2 Practice Exam
Question 8.Which frequency reuse pattern is most commonly used in GSM to
minimize co‑channel interference?
A) 3/9
B) 1/1
C) 4/12
D) 7/21
Answer: D
Explanation: A 7/21 reuse pattern (seven cells per cluster, 21 available
frequencies) is standard in GSM planning to balance capacity and interference.
Question 9.What triggers an intra‑BSC handover in GSM?
A) A subscriber moving from one BSC’s coverage to another BSC’s coverage
B) A change in the subscriber’s tariff plan
C) Degradation of signal quality within the same BSC’s cells
D) A failure of the MSC
Answer: C
Explanation: Intra‑BSC handovers occur when a mobile’s signal quality
deteriorates and the BSC reassigns it to a neighboring cell under the same BSC.
Question 10.Which GSM logical channel carries signaling for call set‑up and SMS
messages?
A) TCH
