Languages-C & C Plus Plus [Samsung Placement]: Sample Questions 1 - 1 of 1

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Question 1

C & C Plus Plus

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Why channel coding is done? (2004)


  • Channel coding is a method to detect and possibly correct errors byintroducing redundancy to the stream of bitsto be sent to the channel. The Channel Encoder will add bits to the message bits to be transmitted systematically. Afterpassing through the channel, the Channel decoder will detect and correct the errors.
  • A simple example is to send ‘000’ ( ‘111’ correspondingly) instead of sending only one ‘0’ ( ‘1’ correspondingly) to the channel. Dueto noise in the channel, the received bitsmay become ‘001’ . But since either ‘000’ or ‘111’ could have been sent. By majority-logic decoding scheme, it willbe decoded as ‘000’ andtherefore the message has been a ‘0’ . In general the channel encoder will divides the input message bits into locksof k messages bits and replaces each k messagebits block with a n-bit code word byintroducing (n-k) check bits to each message block. Some major codes include theBlock CodesandConvolutional Codes.

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