Cellular Systems

1. In case of direct CDMA, interference will occur if the PN codes are
a) Orthogonal to each other
b) Non orthogonal to each other
c) Both of the mentioned
d) None of the mentioned
Answer: b

Explanation: 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
Explanation: 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
Explanation: 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) Both of the mentioned
d) None of the mentioned

Answer: c
Explanation: 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
Explanation: CDMA has more user capacity compared to AMPS and TDMA.

6. Which technique is interference limited?
a) TDMA
b) CDMA
c) Both of the mentioned
d) None of the mentioned

Answer: b
Explanation: CDMA technique capacity is interference limited.

7. Which technique is dimension limited?
a) TDMA
b) FDMA
c) Both of the mentioned
d) None of the mentioned

Answer: c
Explanation: 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
Explanation: The forward link contains different types of channels such as paging, pilot, synchronisation and traffic.

9. The types of channels that reverse channel contains are
a) Traffic
b) Access
c) Both of the mentioned
d) None of the mentioned

Answer: c
Explanation: 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) Both of the mentioned
d) None of the mentioned

Answer: c
Explanation: 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) Both of the mentioned
d) None of the mentioned

Answer: c
Explanation: 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
Explanation: 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

Answer: b
Explanation: In forward direction 64 channels are transmitter and in reverse direction only one channel is transmitted.

14. Which channel is more robust?
a) Forward channel
b) Reverse channel

Answer: a
Explanation: Forward channel is more robust than the reverse channel.

15. Which serves the hard hand-off process?
a) Base station
b) Mobile switching center
c) Mobile
d) None of the mentioned

Answer: b
Explanation: Mobile unit continuously scans for stronger pilot and provides and serves hand off process.

16. Which serves the soft hand-off process?
a) Base station
b) Mobile switching center
c) Mobile
d) None of the mentioned

Answer: c
Explanation: Soft hand off process is served by the mobile. It scans for stronger pilot and requests handoff to base station.