Candidate codeword selection scheme with bit flipping for outer code in overloaded MIMO-OFDM system

This paper presents a candidate codeword selection scheme with bit flipping in two step joint decoding of block coded signals in an overloaded multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) system. In previous literature, the two step joint decoding scheme has been proposed for complexity reduction of maximum likelihood decoding of a block code in the overloaded MIMO system. However, the two step decoding scheme has not been combined with an outer code. The selection of the candidate codewords in the inner block code may not always be able to provide the metric of a binary coded symbol for the outer code. Candidate codewords are then created through bit flipping in the proposed scheme. It is shown that the two step decoding scheme reduces the complexity by about 0.026 for 4 signal streams with the cost of bit error rate degradation within 0.5dB.