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CITS3002 Computer Networks |
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Error Detection and CorrectionData may be modified so that errors can either be:
Correction is required where communication must be simplex (only possible in one direction), but correction is expensive. A good example of its need is between Earth and inter-planetary spacecraft. Error correction by the receiver is referred to as forward error correction, whereas re-transmission schemes are referred to as reverse error correction. Codewords are constructed consisting of both data and check bits.
The Hamming distance between two codewords consists of the number of
bit positions in which they differ.
e.g. 1 ⊕ 1 = 0 ⊕ 0 = 0 1 ⊕ 0 = 0 ⊕ 1 = 1
10011101
10111110
--------------
⊕ 00100011
Here, the Hamming distance is 3.
The Hamming distance of a code is the minimum Hamming
distance between any two words in that code.
CITS3002 Computer Networks, Lecture 2, The Physical Layer, Errors detection and correction, p9, 6th March 2024.
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