In checksum error detection scheme, the data is divided into k segments each of m bits. In the sender’s end the segments are added using 1’s complement arithmetic to get the sum. The sum is complemented to get the checksum. The checksum segment is sent along with the data segments.. At the receiver’s end, all received segments are added using 1’s complement arithmetic to get the sum. The sum is complemented. If the result is zero, the received data is accepted; otherwise discarded.

The checksum detects all errors involving an odd number of bits. It also detects most errors involving even number of bits.

(a) Sender’s end for the calculation of the checksum, (b) Receiving end for checking the checksum