Performance of Unequal Error Protection Using Soft Output Viterbi (SOVA) Algorithm and Modified SOVA in AWGN and Fading Channel

Turbo decoder uses any one of the decoding algorithm of Maximum a-posteriori Probability algorithm (MAP) or Soft Output Viterbi Algorithm (SOVA). SOVA provides an efficient way to find the most likely sequence of state transitions of a finite state chain. SOVA determine the most likely sequence to have been transmitted instead of determining most likelihood for each data bit. The traditional turbo code system use Equal Error Protection (EEP). In many applications all the information don't need equal importance. So we need a new method Unequal Error Protection (UEP). By doing so the important message is more protected than the other message bits. In this paper BER performance of UEP in fading channel is analyzed. BER performance substantially improved for the important class messages in UEP.