(7,4)Hamming Code BER Simulation

The decoding of the transmitted bits have been done using two methods, (1) Hard or Bit Wise Decoding and (2) Soft or Block Wise Decoding. First the 4 information bits are converted (coded) to 7 code bits to form one codewords. The three parity check bits are bit1+bit2+bit3, bit1+bit3+bit3 and bit1+bit2+bit4 respectively. The code bits are first modulated using SNR. The noise power(Gaussian) at the receiver is assumed to be 1 and mean 0. (1) Hard decoding:-First the transmitted bits are converted to +1 and 0, if the are positive and negative respectively. Using the syndrome detection one bit is flipped, if there is an error. The decoded code bits are compared to transmitted and BER is calculated. (2) Soft Decoding:- Distance of received codeword is calculated from all 16 possible valid codewords and the transmitted codeword is decoded into the one from which the distance is minimum. Then the decoded codewords are compared to transmitted and BER is calculated.