Low density spreading for multicarrier systems

Low density spreading (LDS) for multicarrier (MC) systems has been proposed to exploit the trade-off between the receiver complexity and performance improvement. Due to the LSD, the diversity gain from the frequency domain can be achieved by the maximum-likelihood (ML) detector. The structured LDS allows the use of the Viterbi algorithm (VA) to implement the ML detection computationally efficiently. It is also shown that the LSD-MC can perform better than orthogonal frequency division multiplexing (OFDM) for coded signals.