Complexity Reduction of Ordered Statistics Decoding Using Side Information

In this letter, the complexity of the ordered statistics decoding of linear binary block codes is reduced assuming that partial knowledge about the transmitted codeword is available at the decoder. Such side information is provided to the decoder at the receiver from the encoder at the transmitter over a highly reliable low-rate channel. Side information is exploited at the decoder to significantly reduce the number of test codewords that have to be examined during the decoding without sacrificing the error rate performance of the decoder. Side information is represented either by the single parity checks of non-overlapping codeword segments, or by the Hamming weight of the codeword or its part. The proposed method can be readily integrated with other list decoding techniques. Finally, implementation of the proposed complexity reducing scheme in practical systems is also discussed.