Deck 8: Channel Coding and Error Correction Techniques

Question 1

For a error free channel, conditional probability should be

A)zero
B)one
C)equal to joint probability
D)equal to individual probability

Answer 1

zero

Question 2

Average effective information is obtained by

A)subtracting equivocation from entropy
B)adding equivocation with entropy
C)ratio of number of error bits by total number of bits
D)none of the mentioned

Answer 2

subtracting equivocation from entropy

Question 3

Turbo codes are

A)forward error correction codes
B)backward error correction codes
C)error detection codes
D)none of the mentioned

Answer 3

forward error correction codes

Question 4

Components used for generation of turbo codes are

A)inter leavers
B)punching pattern
C)inter leavers & punching pattern
D)none of the mentioned

Question 5

Decoders are connected in series.

Question 6

The inter leaver connected between the two decoders is used to

A)remove error bursts
B)scatter error bursts
C)add error bursts
D)none of the mentioned

Question 7

In soft decision approach what does -127 mean?

A)certainly one
B)certainly zero
C)very likely zero
D)very likely one

Question 8

In soft decision approach 100 means?

A)certainly one
B)certainly zero
C)very likely zero
D)very likely one

Question 9

In soft decision approach 0 represents

A)certainly one
B)certainly zero
C)very likely zero
D)could be either zero or one

Question 10

In layering, n layers provide service to

A)n layer
B)n-1 layer
C)n+1 layer
D)none of the mentioned

Question 11

Which can be used as an intermediate device in between transmitter entity and receiver entity?

A)ip router
B)microwave router
C)telephone switch
D)all of the mentioned

Question 12

Which has comparatively high frequency component?

A)sine wave
B)cosine wave
C)square wave
D)none of the mentioned

Question 13

Which has continuous transmission?

A)asynchronous
B)synchronous
C)asynchronous & synchronous
D)none of the mentioned

Question 14

Which requires bit transitions?

A)asynchronous
B)synchronous
C)asynchronous & synchronous
D)none of the mentioned

Question 15

In synchronous transmission, receiver must stay synchronous for

A)4 bits
B)8 bits
C)9 bits
D)16 bits

Question 16

How error detection and correction is done?

A)by passing it through equalizer
B)by passing it through filter
C)by amplifying it
D)by adding redundancy bits

Question 17

Which is more efficient?

A)parity check
B)cyclic redundancy check
C)parity & cyclic redundancy check
D)none of the mentioned

Question 18

Which can detect two bit errors?

A)parity check
B)cyclic redundancy check
C)parity & cyclic redundancy check
D)none of the mentioned

Question 19

CRC uses

A)multiplication
B)binary division
C)multiplication & binary division
D)none of the mentioned

Question 20

Block codes can achieve a larger coding gain than convolution coding.

Question 21

Which of the following indicates the number of input bits that the current output is dependent upon?

A)constraint length
B)code length
C)search window
D)information rate

Question 22

Which of the following is not a way to represent convolution code?

A)state diagram
B)trellis diagram
C)tree diagram
D)linear matrix

Question 23

Which of the following is not an algorithm for decoding convolution codes?

A)viterbi algorithm
B)stack algorithm
C)fano's sequential coding
D)ant colony optimization

Question 24

Fano's algorithm searches all the paths of trellis diagram at same time to find the most probable path.

Question 25

Which of the following is not an advantage of Fano's algorithm in comparison to Viterbi's algorithm?

A)less storage
B)large constraint length
C)error rate
D)small delays