Ace test series

Question

 

Guys, I am not getting C as the ans..Can someone help.

 

Comments

The point Here is to remember is that if N is the degree of polynomial then We have to insert N in Message.

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I am getting 101. Is there something wrong.

We have add 3 bits at the end right? Then after division .

or message polynomial itself contains the padded bits.

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You are doing something wrong. Post your solution here , I will look.

Answer 1

If the Degree of the Polynomial is N then CRC Generator will be of Degree N+1 bits And CRC Will be N bits.

The message is Given as M(x) = x⁷ + x⁴ + x³ + x Then Message bits  = 10011010

CRC Generator G(x) = x³ + x² +1    =  1101

Then CRC(After performing XOR operation or Modulo 2 operation Between Message and CRC Generator) = 001

So , the message We have to send is 

Message                                                                                   CRC Bits

10011010

001

 

Comments

Why u are not adding the padding bits (3) in the message polynomial???

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this solution is incorrect. where is the padding ? you just XORed Message Polynomial with Generator Polynomial

We also have to augment the message polynomial

Answer 2

Remainder will be 101 and padding is required before xor