Digital Communications Multiple Choice Questions on “Cellular systems”.
1. In the case of direct CDMA, interference will occur if the PN codes are
A. Orthogonal to each other
B. Non orthogonal to each other
C. Orthogonal & Non orthogonal to each other
D. None of the mentioned
Answer: B
Clarification: If the PN codes are not purely orthogonal in direct CDMA interference will occur.
2. If the active users using a cell doubles, the required Eb/I0
A. Doubles
B. Halves
C. Remains the same
D. None of the mentioned
Answer: B
Clarification: If the active users were to double, then the received Eb/I0 would essentially be halved.
3. In CDMA ______ frequency reuse is possible.
A. No
B. 50%
C. 90%
D. 100%
Answer: D
Clarification: In CDMA, 100% frequency reuse can be employed.
4. Bandwidth efficiency improvement involves
A. Dividing the geographical region into cells
B. Allowing frequency allocation
C. Dividing the geographical region into cells & Allowing frequency allocation
D. None of the mentioned
Answer: C
Clarification: The idea of dividing the geographical region into cells and allowing frequency allocation of one cell can be reused represents bandwidth efficiency improvement methods.
5. Which has more user capacity?
A. CDMA
B. AMPS
C. TDMA
D. None of the mentioned
Answer: A
Clarification: CDMA has more user capacity compared to AMPS and TDMA.
6. Which technique is interference limited?
A. TDMA
B. CDMA
C. AMPS
D. None of the mentioned
Answer: B
Clarification: CDMA technique capacity is interference limited.
7. Which technique is dimension limited?
A. TDMA
B. FDMA
C. TDMA & FDMA
D. None of the mentioned
Answer: C
Clarification: TDMA and FDMA capacity is dimension limited.
8. Which type of channel does the forward link contain?
A. Paging
B. Pilot
C. Traffic
D. All of the mentioned
Answer: D
Clarification: The forward link contains different types of channels such as paging, pilot, synchronization and traffic.
9. The types of channels that reverse channel contains are
A. Traffic
B. Access
C. Traffic & Access
D. None of the mentioned
Answer: C
Clarification: The reverse channel contains two types of channels – traffic and access.
10. The steps followed in forward channel CDMA includes
A. Modulo 2 addition
B. Channelization
C. Modulo 2 addition & Channelization
D. None of the mentioned
Answer: C
Clarification: Forward channel CDMA includes steps like modulo 2 addition, channelization, and base station identification.
11. Walsh cover technique is used for
A. Channelization
B. Spreading
C. Channelization & Spreading
D. None of the mentioned
Answer: C
Clarification: Walsh cover is used for channelization plus spreading.
12. Short code is configured using ______ shift register.
A. 4-stage
B. 2-stage
C. 12-stage
D. 15-stage
Answer: D
Clarification: The code in the forward direction, short code is designed using 15 stage shift register.
13. How many channels are transmitted in the forward and reverse direction?
A. 1,64
B. 64,1
C. 2,32
D. 32,2