This set of Data communication and Networking Multiple Choice Questions and Answers (MCQs) focuses on “Multiplexing Demultiplexing techniques – frequency-division multiplexing (FDM) , Time-division multiplexing (TDM) , Wavelength division multiplexing (WDM) , Mode-division multiplexing (MDM)”.
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1. A multiplexer _______ several transmission streams while a demultiplexer _______ them
- combines; separates
- compresses; decompresses
- encrypts; decrypts
- separates; combines
A. combines; separates
2. One _______ can be made of many _______
- channel; paths
- path; channels
- path; links
- channel; links
B. path; channels
3. Which of the following is a digital multiplexing method?
- FDM
- asynchronous TDM
- synchronous TDM
- b and c
D. b and c
4. Which is not a basic multiplexing method?
- FDM
- TDM
- WDM
- MDM
D. MDM
5. _______ is an analog multiplexing technique usually involving signals that are not in the visible light frequencies
- FDM
- TDM
- WDM
- MDM
A. FDM
6. _______ is a digital multiplexing technique usually involving signals that are not in the visible light frequencies
- FDM
- TDM
- WDM
- MDM
B. TDM
7. _______ is an analog multiplexing technique usually involving signals in the visible light frequencies.
- FDM
- TDM
- WDM
- MDM
C. WDM
8. In FDM, the bandwidth of the link must be _______ the sum of the bandwidths of the signals to be combined
- equal to
- less than
- greater than
- an order of magnitude greater than
C. greater than
9. In FDM, if five signals are to be multiplexed, at least _______ carriers, each of a different frequency, must be modulated
- 1
- 5
- 6
- 10
B. 5
10. FDM uses _______ to prevent modulated signals from overlapping
- physical hardware devices
- carrier frequencies
- guard bands
- demultiplexers
C. guard bands
11. In FDM, the _______ signals can all have the same frequency range
- modulating
- carrier
- modulated
- b or c
A. modulating
12. The FDM demultiplexer uses a series of _______ to decompose the multiplexed signal into its constituent signals,
- guard bands
- filters
- repeaters
- amplifiers
B. filters
13. WDM is very similar in concept to _______.
- asynchronous TDM
- synchronous TDM
- FDM
- AM or FM
C. FDM
14. If the sum of the data rates of the sending devices is X, TDM can be applied when the data rate capacity of the transmission medium is _______.
- less than X
- greater than X
- one half X
- two times X
B. greater than X
15. In _______ the multiplexer allocates exactly the same time slot to each device at all times
- synchronous TDM
- asynchronous TDM
- FDM
- WDM
A. synchronous TDM
16. In _______, if a device has no data to send, its time slot remains empty
- synchronous TDM
- asynchronous TDM
- FDM
- WDM
A. synchronous TDM
17. In synchronous TDM, a _______ is a complete cycle of time slots, including one or more slots dedicated to each sending device.
- filter
- carrier
- signal
- frame
D. frame
18. What is the efficiency of a system using synchronous TDM if 2 of the 5 devices have nothing to send?
- 20%
- 50%
- 60%
- 100%
C. 60%
19. In synchronous TDM, if device X has data to send, the data go to _______ in the frame
- the next available slot
- a preassigned slot
- the first slot
- none of the above
B. a preassigned slot
20. In asynchronous TDM, if device X has data to send, the data go to _______ in the frame.
- the next available slot
- a preassigned slot
- the first slot
- none of the above
A. the next available slot
21. In synchronous TDM, if device X has no data to send, what happens to its allotted slot?
- The next device in line takes it.
- An error message is sent.
- The bit pattern 01010101 is sent.
- The slot remains empty.
D. The slot remains empty.
22. In synchronous TDM, each frame is filled with data from the devices in a fixed order. We call this _______
- interleaving
- synchronization
- switching
- line discipline
A. interleaving
23. _______ allow the demultiplexer to synchronize with the incoming stream
- Slots
- Framing bits
- Demultiplexing bits
- Trailers
B. Framing bits
24. In synchronous TDM, if ten devices are each sending data at the rate of 2000 bps, what is the data rate for the line carrying the multiplexed signals?
- 2000 bps
- 20,000 bps
- greater than 20,000 bps
- less than 20,000 bps
C. greater than 20,000 bps
25. What is the major weakness of asynchronous TDM?
- There aren't enough slots in each frame.
- There are too many slots per frame.
- Each slot requires an address.
- All of the above
C. Each slot requires an address.
26. What is the major weakness of synchronous TDM?
- Some slots may remain empty.
- There aren't enough slots.
- The slots are too small.
- All of the above.
A. Some slots may remain empty.
27. Which type of multiplexing takes data from one high-speed line and breaks it into portions that can be sent across several lower-speed lines simultaneously?
- asynchronous TDM
- synchronous TDM
- FDM
- inverse multiplexing
D. inverse multiplexing
