Impact of trellis termination on performance of turbo codes

Decoding performance of turbo decoder is weakened, if trellis ends in an unknown state. Trellis termination is an important method for overcoming this problem and improving performance of turbo codes by periodically adding tail bits into information sequence. In this paper various types of trellis termination are described. Performance of a turbo code without trellis termination and the turbo code with its first trellis terminated is compared. Turbo encoder used in simulations is based on design from 3GPP/UMTS and 3GPP/LTE standards while BCJR algorithm is used for decoding.