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1.

CDMA uses(a) Hard hand off(b) Soft hand off(c) Hard & Soft hand off(d) None of the mentionedI have been asked this question in exam.Query is from Spread Spectrum and CDMA topic in chapter Multiplexing and Multiple Access of Digital Communications

Answer»

Correct OPTION is (B) SOFT hand off

For EXPLANATION: CDMA uses soft hand off which PROVIDES more reliable communication.
Discussion
2.

Frequency planning is very essential in(a) FDMA(b) TDMA(c) FDMA & TDMA(d) None of the mentionedI had been asked this question during a job interview.I want to ask this question from Spread Spectrum and CDMA topic in division Multiplexing and Multiple Access of Digital Communications

Answer»

Right choice is (C) FDMA & TDMA

Easy EXPLANATION: FREQUENCY PLANNING is NECESSARY for both TDMA and FDMA.
Discussion
3.

CDMA rejects(a) Narrow band interference(b) Wide band interference(c) Narrow & Wide band interference(d) None of the mentionedThe question was posed to me in an online quiz.The origin of the question is Spread Spectrum and CDMA in section Multiplexing and Multiple Access of Digital Communications

Answer» CORRECT OPTION is (a) Narrow band INTERFERENCE

Easy explanation: CDMA EFFECTIVELY rejects narrow band interference.
Discussion
4.

Which is more suitable when large number of transmitters are used?(a) Synchronous CDMA(b) Asynchronous CDMA(c) Synchronous & Asynchronous CDMA(d) None of the mentionedThis question was addressed to me by my college director while I was bunking the class.This interesting question is from Spread Spectrum and CDMA topic in section Multiplexing and Multiple Access of Digital Communications

Answer»

The correct OPTION is (b) ASYNCHRONOUS CDMA

For explanation: Asynchronous CDMA is more suitable for large number of TRANSMITTERS.
Discussion
5.

Which uses orthogonal codes?(a) Synchronous CDMA(b) Asynchronous CDMA(c) Synchronous & Asynchronous CDMA(d) None of the mentionedThe question was posed to me during an internship interview.Enquiry is from Spread Spectrum and CDMA topic in section Multiplexing and Multiple Access of Digital Communications

Answer»
Discussion
6.

Which is more simpler to implement?(a) Direct sequence spread spectrum(b) Frequency hopping spread spectrum(c) Time hopping spread spectrum(d) None of the mentionedThis question was addressed to me by my college professor while I was bunking the class.My question is based upon Spread Spectrum and CDMA in chapter Multiplexing and Multiple Access of Digital Communications

Answer» RIGHT option is (a) Direct sequence spread SPECTRUM

To ELABORATE: Direct sequence spread spectrum is more simpler to IMPLEMENT.
Discussion
7.

Which is better for avoiding jamming?(a) Direct sequence spread spectrum(b) Frequency hopping spread spectrum(c) Time hopping spread spectrum(d) None of the mentionedI got this question in an online interview.This key question is from Spread Spectrum and CDMA in portion Multiplexing and Multiple Access of Digital Communications

Answer» RIGHT answer is (B) FREQUENCY hopping SPREAD spectrum

The BEST I can explain: Frequency hopping spread spectrum is better for avoiding jamming.
Discussion
8.

Which is more bandwidth efficient?(a) Direct sequence spread spectrum(b) Frequency hopping spread spectrum(c) Time hopping spread spectrum(d) None of the mentionedThe question was asked in semester exam.My question is from Spread Spectrum and CDMA in division Multiplexing and Multiple Access of Digital Communications

Answer»

Right OPTION is (c) Time HOPPING spread SPECTRUM

For explanation: Time hopping spread spectrum is more BANDWIDTH efficient.
Discussion
9.

Processing gain is the ratio of message bandwidth to signal bandwidth.(a) True(b) FalseThis question was posed to me by my college director while I was bunking the class.I want to ask this question from Spread Spectrum and CDMA in chapter Multiplexing and Multiple Access of Digital Communications

Answer»

The correct CHOICE is (B) False

The BEST explanation: Processing gain is the ratio of signal BANDWIDTH to message bandwidth.
Discussion
10.

In digital communication, interaction between ______ is possible.(a) Any layer to layer(b) One layer to next layer(c) layers(d) None of the mentionedI have been asked this question in final exam.My doubt stems from TDM vs FDM in portion Multiplexing and Multiple Access of Digital Communications

Answer»

The correct CHOICE is (B) ONE layer to NEXT layer

To elaborate: In digital communication, in layers only one layer and its next layer can COMMUNICATE.
Discussion
11.

Some advantages of spread spectrum are(a) Low susceptibility(b) Immunity to jamming(c) Reduced interference(d) All of the mentionedI got this question in quiz.My question is from Spread Spectrum and CDMA topic in portion Multiplexing and Multiple Access of Digital Communications

Answer» CORRECT answer is (d) All of the mentioned

To explain I would say: Advantages of spread spectrum are low SUSCEPTIBILITY, reduced interference, IMMUNITY to JAMMING and co existence of multi path system.
Discussion
12.

A mechanism for breaking the problem down is(a) Layering(b) Dividing(c) Abstraction(d) Entity sharingThe question was asked in a job interview.This question is from TDM vs FDM in chapter Multiplexing and Multiple Access of Digital Communications

Answer»

Right ANSWER is (c) ABSTRACTION

The explanation: Abstraction is the MECHANISM of breaking the PROBLEM down.
Discussion
13.

In which reusing of components can be made possible?(a) Analog communication(b) Digital communication(c) Analog & Digital communication(d) None of the mentionedI had been asked this question in exam.This question is from TDM vs FDM in portion Multiplexing and Multiple Access of Digital Communications

Answer»
Discussion
14.

Which maintains better fidelity?(a) Analog communication(b) Digital communication(c) Analog & Digital communication(d) None of the mentionedThis question was posed to me during an interview.My enquiry is from TDM vs FDM topic in chapter Multiplexing and Multiple Access of Digital Communications

Answer»

Right answer is (B) Digital communication

To EXPLAIN: Digital communication provides BETTER FIDELITY control.
Discussion
15.

Using sampling theorem, analog signal cannot be reconstructed.(a) True(b) FalseThis question was addressed to me during an interview.My question is based upon TDM vs FDM in division Multiplexing and Multiple Access of Digital Communications

Answer»

Correct choice is (B) False

Easiest explanation: USING SAMPLING theorem ANALOG signal can be reconstructed.
Discussion
16.

Which has lower noise immunity?(a) TDM(b) FDM(c) TDM & FDM(d) None of the mentionedThis question was addressed to me in a national level competition.This question is from TDM vs FDM topic in chapter Multiplexing and Multiple Access of Digital Communications

Answer» RIGHT CHOICE is (a) TDM

The best EXPLANATION: TDM has lower noise IMMUNITY.
Discussion
17.

TDM can be employed to transmit channels having unequal bandwidth,(a) True(b) FalseI have been asked this question in examination.Origin of the question is TDM vs FDM topic in section Multiplexing and Multiple Access of Digital Communications

Answer»

The correct option is (a) True

The EXPLANATION: True. TDM can be EMPLOYED to transmit channels having unequal BANDWIDTH.
Discussion
18.

Which has greater bandwidth?(a) TDM(b) FDM(c) TDM & FDM(d) None of the mentionedI had been asked this question in examination.This interesting question is from TDM vs FDM topic in chapter Multiplexing and Multiple Access of Digital Communications

Answer» RIGHT option is (b) FDM

The best I can explain: FDM has greater BANDWIDTH.
Discussion
19.

TDM is used to(a) Increase the information transmission rate(b) Use only one carrier frequency to handle different signals(c) To use different frequency bands for different signals(d) To protect all small signals in PCM from quantizing noiseI got this question during an internship interview.Origin of the question is TDM vs FDM topic in section Multiplexing and Multiple Access of Digital Communications

Answer»

The CORRECT option is (b) USE only ONE carrier frequency to handle different signals

To ELABORATE: TDM is used to use only one carrier frequency to handle different signals.
Discussion
20.

Companding is used to(a) Increase the information transmission rate(b) Use only one carrier frequency to handle different signals(c) To use different frequency bands for different signals(d) To protect all small signals in PCM from quantizing noiseThe question was posed to me in exam.The above asked question is from TDM vs FDM topic in chapter Multiplexing and Multiple Access of Digital Communications

Answer» CORRECT CHOICE is (d) To protect all SMALL signals in PCM from quantizing noise

To ELABORATE: COMPANDING is used to protect all small signals in PCM from quantizing noise.
Discussion
21.

Which are non orthogonal multiplexing?(a) TDM(b) FDM(c) TDM & FDM(d) None of the mentionedThe question was asked in a job interview.Enquiry is from TDM and FDM topic in chapter Multiplexing and Multiple Access of Digital Communications

Answer» RIGHT answer is (d) NONE of the mentioned

The explanation: TDM and FDM are both ORTHOGONAL MULTIPLEXING.
Discussion
22.

Minimum packet size increases as(a) Speed increases(b) Distance increases(c) Speed & Distance increases(d) None of the mentionedThis question was addressed to me during an interview.I'd like to ask this question from TDM and FDM topic in portion Multiplexing and Multiple Access of Digital Communications

Answer» RIGHT choice is (c) Speed & DISTANCE increases

Explanation: As speed and distance GOES up, minimum packet size also goes up.
Discussion
23.

Which isolates collision?(a) Bridges(b) Routers(c) Bridges & Routers(d) None of the mentionedI had been asked this question by my college professor while I was bunking the class.The query is from TDM and FDM in chapter Multiplexing and Multiple Access of Digital Communications

Answer»

Right option is (c) BRIDGES & Routers

For EXPLANATION I WOULD say: Bridges and routers isolates COLLISION.
Discussion
24.

Reservation systems are useful when(a) Delay is small(b) Delay is large(c) Delay is small or large(d) None of the mentionedThis question was posed to me in class test.This intriguing question comes from TDM and FDM in portion Multiplexing and Multiple Access of Digital Communications

Answer» CORRECT option is (b) DELAY is large

To explain: Reservation systems are USEFUL when DELAYS are large.
Discussion
25.

In CSMA, collision window is _____ to cable length.(a) Equal(b) Greater(c) Lesser(d) None of the mentionedThe question was asked in an online interview.This intriguing question comes from TDM and FDM in division Multiplexing and Multiple Access of Digital Communications

Answer» RIGHT option is (b) Greater

To explain I WOULD say: The collision window is TWICE the cable LENGTH.
Discussion
26.

In slotted system, access is(a) Synchronous(b) Asynchronous(c) Synchronous & Asynchronous(d) None of the mentionedI have been asked this question by my college professor while I was bunking the class.Origin of the question is TDM and FDM in division Multiplexing and Multiple Access of Digital Communications

Answer»

Right OPTION is (b) ASYNCHRONOUS

The best explanation: In slotted system, access is asynchronous and requires ADDRESSING INFORMATION INSIDE.
Discussion
27.

Example of reservation system is(a) Synchronous TDM(b) Non synchronous TDM(c) Synchronous & Non synchronous TDM(d) None of the mentionedI have been asked this question in unit test.Query is from TDM and FDM in chapter Multiplexing and Multiple Access of Digital Communications

Answer» RIGHT choice is (a) SYNCHRONOUS TDM

For explanation: Synchronous TDM is an example for the RESERVATION system.
Discussion
28.

Random access is(a) Distributed(b) Fault tolerant(c) Distributed & Fault tolerant(d) None of the mentionedI got this question in unit test.Origin of the question is TDM and FDM topic in division Multiplexing and Multiple Access of Digital Communications

Answer»

Right option is (C) Distributed & Fault tolerant

To elaborate: RANDOM access is SIMPLE, distributed and very fault tolerant.
Discussion
29.

Which provides constant delay?(a) Synchronous TDM(b) Non synchronous TDM(c) Synchronous & Non synchronous TDM(d) None of the mentionedI had been asked this question by my college professor while I was bunking the class.My doubt is from TDM and FDM topic in division Multiplexing and Multiple Access of Digital Communications

Answer» RIGHT choice is (a) Synchronous TDM

For explanation I WOULD SAY: Synchronous time division multiplexing PROVIDES CONSTANT bandwidth and constant delay.
Discussion
30.

Which is based on orthogonality?(a) TDM(b) FDM(c) TDM & FDM(d) None of the mentionedThis question was addressed to me in an online interview.My doubt stems from TDM and FDM in division Multiplexing and Multiple Access of Digital Communications

Answer» CORRECT ANSWER is (b) FDM

The best I can explain: FDM TECHNIQUE is based on the orthogonality of SINUSOIDS.
Discussion
31.

Which technique needs precise synchronization?(a) TDMA(b) FDMA(c) TDMA & FDMA(d) None of the mentionedThe question was posed to me at a job interview.My question is from INTELSAT in division Multiplexing and Multiple Access of Digital Communications

Answer»

The correct choice is (a) TDMA

For EXPLANATION: TDMA OPERATION needs very precise synchronization needed to assure ORTHOGONALITY of TIME slots.
Discussion
32.

Which is more costlier?(a) TDMA(b) FDMA(c) ALOHA(d) None of the mentionedThis question was posed to me during a job interview.The above asked question is from INTELSAT in chapter Multiplexing and Multiple Access of Digital Communications

Answer»

Correct OPTION is (a) TDMA

Best EXPLANATION: TDMA EARTH station equipment is more COSTLIER than the FDMA equipments.
Discussion
33.

In SPADE system, the carrier is done based on(a) Fixed assignment(b) Demand assignment(c) Fixed & Demand assignment(d) None of the mentionedI have been asked this question by my college director while I was bunking the class.My question is from INTELSAT in division Multiplexing and Multiple Access of Digital Communications

Answer»

Right option is (b) DEMAND assignment

Easiest explanation: In SPADE system, the carrier is ASSIGNED DYNAMICALLY, that is on demand.
Discussion
34.

SPADE is a(a) MAA system(b) DAMA system(c) MAA & DAMA system(d) None of the mentionedI have been asked this question in homework.My query is from INTELSAT topic in chapter Multiplexing and Multiple Access of Digital Communications

Answer»

Correct CHOICE is (B) DAMA SYSTEM

The best explanation: SPADE is a DAMA system where all channels are SHARED.
Discussion
35.

SPADE uses(a) QPSK(b) BPSK(c) FSK(d) MSKThe question was posed to me in an online quiz.This intriguing question comes from INTELSAT topic in portion Multiplexing and Multiple Access of Digital Communications

Answer» CORRECT CHOICE is (a) QPSK

Explanation: SPADE uses DIGITAL voice transmission – QPSK.
Discussion
36.

Which method is better when traffic is heavy?(a) SPADE(b) Binary tree search(c) SPADE & Binary tree search(d) None of the mentionedI got this question during an internship interview.My enquiry is from INTELSAT topic in portion Multiplexing and Multiple Access of Digital Communications

Answer»

Correct choice is (c) SPADE & BINARY tree search

Easiest explanation: SPADE OPERATION and binary tree search can be used when the TRAFFIC is heavy.
Discussion
37.

TWTA which operates in the linear region(a) Reduces interference(b) Provide less overall power(c) Is power limited(d) All of the mentionedThe question was asked in homework.Asked question is from INTELSAT in chapter Multiplexing and Multiple Access of Digital Communications

Answer»

Right OPTION is (d) All of the mentioned

To explain: TWTA operating in the linear region reduces interference, and can provide less OVERALL POWER. The channel BECOMES power limited and can service fewer carriers.
Discussion
38.

As the number of carriers increases, the number of guard bands(a) Increases(b) Decreases(c) Remains the same(d) None of the mentionedThe question was asked in final exam.I need to ask this question from INTELSAT topic in portion Multiplexing and Multiple Access of Digital Communications

Answer»

The correct CHOICE is (a) Increases

To explain I would say: Guard bands are needed between the carriers. THUS as carriers increases, guard bands are ALSO increases.
Discussion
39.

As the number of carriers, the capacity of the transponder(a) Increases(b) Decreases(c) Remains the same(d) None of the mentionedThis question was posed to me in an international level competition.The doubt is from INTELSAT in portion Multiplexing and Multiple Access of Digital Communications

Answer»

The CORRECT OPTION is (B) Decreases

The explanation is: The capacity of the transponder drops as the NUMBER of carriers increases.
Discussion
40.

INTELSAT II and III operates their TWTA in(a) Saturation region(b) Linear region(c) Hard limiting region(d) None of the mentionedI have been asked this question in an online interview.Question is taken from INTELSAT in division Multiplexing and Multiple Access of Digital Communications

Answer» CORRECT choice is (B) Linear region

The best explanation: INTELSAT II and III operate its traveling wave tube AMPLIFIERS in linear region.
Discussion
41.

Binary tree search is used for(a) Multiple users(b) Single users(c) Single & Multiple users(d) None of the mentionedThe question was posed to me in a national level competition.I need to ask this question from Multiple Access Techniques for LAN and Access Algorithms topic in section Multiplexing and Multiple Access of Digital Communications

Answer»

Correct choice is (a) Multiple users

The BEST explanation: BINARY tree search is used for RAPID polling of user population and it is used for multiple users.
Discussion
42.

For a higher throughput value which method works efficiently?(a) S-ALOHA(b) Pure ALOHA(c) R-ALOHA(d) None of the mentionedI have been asked this question in unit test.Query is from Multiple Access Techniques for LAN and Access Algorithms topic in portion Multiplexing and Multiple Access of Digital Communications

Answer»

Right CHOICE is (C) R-ALOHA

Explanation: At lower throughput values, S-ALOHA works BETTER and for HIGHER throughput values R-ALOHA works better.
Discussion
43.

Which method is better suited for large population?(a) Straight polling(b) Binary tree search(c) Straight polling & Binary tree search(d) None of the mentionedThe question was posed to me in unit test.The above asked question is from Multiple Access Techniques for LAN and Access Algorithms in section Multiplexing and Multiple Access of Digital Communications

Answer»

The CORRECT OPTION is (b) Binary tree SEARCH

To explain I would say: Binary tree search is more efficient METHOD than straight polling in case of a large POPULATION.
Discussion
44.

For a throughput value of 0.20 to 0.67, which has less average delay?(a) S-ALOHA(b) Pure ALOHA(c) R-ALOHA(d) None of the mentionedThe question was posed to me during an interview.I'd like to ask this question from Multiple Access Techniques for LAN and Access Algorithms in division Multiplexing and Multiple Access of Digital Communications

Answer» RIGHT OPTION is (C) R-ALOHA

For explanation: For throughput VALUE of 0.20 to 0.67, it is clear that R-ALOHA is superior and has less AVERAGE delay than S-ALOHA.
Discussion
45.

For a throughput of value less than 0.20, which has less average delay?(a) S-ALOHA(b) Pure ALOHA(c) R-ALOHA(d) None of the mentionedThe question was asked by my school principal while I was bunking the class.My query is from Multiple Access Techniques for LAN and Access Algorithms in portion Multiplexing and Multiple Access of Digital Communications

Answer»

The correct option is (a) S-ALOHA

For EXPLANATION I WOULD say: For a throughput value of less than 0.20, S-ALOHA has less AVERAGE DELAY than R-ALOHA.
Discussion
46.

In which technique, packet size are constant?(a) Pure Aloha(b) Slotted Aloha(c) Pure & Slotted Aloha(d) None of the mentionedI had been asked this question by my school principal while I was bunking the class.The question is from Multiple Access Techniques for LAN and Access Algorithms topic in portion Multiplexing and Multiple Access of Digital Communications

Answer» RIGHT option is (a) Pure Aloha

The EXPLANATION: The Pure Aloha TECHNIQUE has constant packet lengths.
Discussion
47.

In Aloha technique, the re-transmission takes place immediately.(a) True(b) FalseThe question was posed to me in an online quiz.This interesting question is from Multiple Access Techniques for LAN and Access Algorithms in division Multiplexing and Multiple Access of Digital Communications

Answer»

Right answer is (B) False

Explanation: In Aloha technique if the NEGATIVE acknowledgment is received, the re-transmission is DONE after a RANDOM delay so that it doesn’t collide again.
Discussion
48.

As channel capacity increases, channel throughput(a) Increases(b) Decreases(c) Remains the same(d) None of the mentionedI have been asked this question in class test.My doubt is from Multiple Access Techniques for LAN and Access Algorithms topic in section Multiplexing and Multiple Access of Digital Communications

Answer»

Right option is (a) INCREASES

To explain: As channel CAPACITY R increases, the channel THROUGHPUT should also increase.
Discussion
49.

Bit stuffing is done by inserting _____, after ____ consecutive ones.(a) Zero, seven(b) Zero, five(c) One, seven(d) One, fiveI had been asked this question during an interview.Question is taken from Multiple Access Techniques for LAN and Access Algorithms topic in portion Multiplexing and Multiple Access of Digital Communications

Answer» RIGHT OPTION is (a) Zero, seven

The best explanation: Bit STUFFING is done by INSERTING a zero in the data stream after seven CONSECUTIVE ones.
Discussion
50.

The interface between the ring and the stations are passive.(a) True(b) FalseI had been asked this question in unit test.My question comes from Multiple Access Techniques for LAN and Access Algorithms topic in division Multiplexing and Multiple Access of Digital Communications

Answer»

Correct CHOICE is (B) False

Explanation: The INTERFACE between the rings and the STATIONS are active rather than passive.
Discussion