Joint source channel VL coding/decoding for deep space communication networks based on a space trellis

This paper presents joint source channel variable length （VL） coding/decoding based on a space trellis. Through constructing a joint decoding plane trellis, better decoding performance can be achieved than by using the bit-level decoding algorithm. However, the plane trellis is complicated, which results in high decoding complexity for decoding VL turbo codes. To solve this problem, we construct a space trellis and design a low-complexity joint decoding algorithm with a variable length symbol-a posteriori probability （VLS- APP） algorithm in resource constrained deep space communication networks. Simulation results show that the proposed approach reduces the decoding complexity by 10% compared with the plane trellis, and the gain of Eb/No is about 0.2 dB at SER = 10-4. Furthermore, it provides substantial error protection for variable-length encoded image data.