Question

Info: 1111101 has to be sent on a data link. The sender and receiver share a polynomial: x³ + x²+ 1

a. Generate the syndrome using CRC
b. Show the actual message to be transmitted

Answer 1

The question pertains to encoding a message using a CRC method in Computer Networks. The original message 1111101 is transmitted with a CRC code appending, derived by XOR division of the message with zeros appended with the binary representation of the polynomial. Syndrome is checked on the receiver's end to detect errors.

Step-by-step explanation:

The student is asking about a concept in Computer Networks, specifically transmitting a message using Cyclic Redundancy Check (CRC). CRC is a method of detecting accidental changes or errors in the communication channel. The polynomial given is x³ + x² + 1, which will be used to generate the CRC bits. To encode the original message 1111101 using CRC, we need to follow a few steps.

• First, represent the polynomial in binary. For x³ + x² + 1, this is 1101.
• Append three zeros (equal to the degree of the polynomial) to the original binary message to account for the CRC bits: 1111101000.
• Divide the appended binary message by the polynomial binary representation using XOR division.
• The remainder from this division is the CRC code. This remainder will be appended to the original message to create the actual message to be transmitted.

To find the syndrome in CRC, you would need to perform the same division process on the received message (including the CRC) and check if the remainder (syndrome) is zero. If it is not zero, it indicates that an error occurred during transmission.