Improved turbo decoder structures for burst error channels

We present an extended version of a turbo decoder which can cope with occasional phase shifts of the received signal. Such shifts are usually caused by noise bursts which prevent a proper synchronization of the incoming signal. To model such a channel, we propose a concatenation of the BSC (binary symmetric channel) and the AWGN channel which can easily be incorporated into the classical turbo decoding algorithm by extending the state space. The proposed algorithm improves the performance by 0.2-0.6 dB as compared to the classical turbo decoder. A simplified version of the algorithm is also presented and shown to perform as well as the full version