TCS Papers: Sample Questions 480 - 481 of 502

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Question number: 480

» Basic CS » Networks

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Describe in Detail

Compare Error Detection and Error Correction:


Compare error detection and error correction

Compare error detection and error correction

Error Detection

Error Correction

Checks only if any error has occurred. A single bit error is the same as a burst error.

Finds exact number and location of corrupted bits. The number of the errors and size of message are important.

Depends on redundancy bits to detect errors and on ACKs and retransmissions to recover from the errors.

Needs larger redundancy to detect and correct errors. Error correcting codes are often referred as forward error correction.

Verifies correctness of received information without any information on original message.

Next step from error detection- the error is corrected by the error correcting codes.

Sender adds some redundant bits to the original message based on some property of message signal (i. e. parity bits) and on the receiver side these bits are used to predict the error.

In some cases it may ask the sender to resend the data.

Parity Checking,

Longitudinal Redundancy check (LRC),

Cyclic Redundancy Check (CRC),

Check Sum are commonly used error detection techniques

Hamming distance code is most common best error correction technique.

Question number: 481

» Basic CS » Networks

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Describe in Detail

What is multiplexing?


  • Multiplexing allows simultaneous transmission of multiple signals across a single data link.

  • It is the process of combining many separate signals to send them over the same transmission media

  • High-bandwidth media such as optical fiber have carrying capacity far in excess of that needed for the average transmission signal- thus multiplexing maximizes the utilization of all facilities.

  • This new channel can be added for increasing traffic or higher bandwidth links can be used to carry multiple signals.

Image of the multiplexing

Image of the Multiplexing

Given the image is define the multiplexing