Error detection and correction

17,106 views

Published on

Computer Network

Published in: Technology
0 Comments
3 Likes
Statistics
Notes
  • Be the first to comment

No Downloads
Views
Total views
17,106
On SlideShare
0
From Embeds
0
Number of Embeds
4
Actions
Shares
0
Downloads
463
Comments
0
Likes
3
Embeds 0
No embeds

No notes for slide

Error detection and correction

  1. 1. Error Detection and Correction
  2. 2. Coding: Redundancy is achieved through various coding Scheme. The sender adds the redundancy bit to the original message and create relationship. The receiver checks the relationship b/w two sets of bits to detect (or) correct the errors. Robustness of the process are important factors in any coding scheme.
  3. 3. The Structure of encoder and decoder
  4. 4. 2 categories Block coding 2. Convolution coding-more complex(less use) 1.
  5. 5. Modular Arithmetic Use only limited range of integers. We, define upper limit, called a ,modulus N. Then use only the integers 0 to N-1. This is modulo-N arithmetic.
  6. 6. Modulo-2 Arithmetic Here modulus N is 2. we can use only 0 and 1. operation in this arithmetic are very simple. The addition and subtraction give the same results. Here, we use XOR operation for both the add and sub. The result of an XOR operation is 0(if both the bits are same. The result is 1 if the any of the two bit is different.)
  7. 7. Block coding Divide the message into blocks, each of k bits, called datawords. Then add r redundant bit to make length n=k+r The resulting n-bit blocks are called codewords.
  8. 8. Error Detection The receiver can detect a change in the original codeword. by 1. The receiver has a list of valid codewords. 2. The original codeword has changed to an invalid one.
  9. 9. Error Detection
  10. 10. Example code word
  11. 11. Error Correction

×