Cyclic Redundancy Check

Ø  It uses small number of redundant bits to detect errors.

Ø  Divisor is calculated by the polynomial functions under two conditions

a.    It should not be divisible by x

b.   It should be divisible by x+1

8     Consider the original message as M(x) – n+1 bits

9     Divisor C(x) – K bits

10  Original sent message = M(x) + k-1 bits

Steps

Ø  Append k-1 zeros with M(x) – P(x)

Ø  Divide P(x) by C(x)

Ø  Subtract the remainder from T(x)

Ø  Subtraction is made by making XOR operation

Eg:     100100 by 1101