An OFDM transmission scheme using variable-length groupwise orthogonal code multiplexing

This paper proposes a novel orthogonal frequency division multiplexing (OFDM) transmission scheme using variable-length groupwise (VLG) orthogonal code multiplexing (OCM). It reduces significantly the complexity for multiplexing and demultiplexing with just a little sacrifice in the performance as compared with the ordinary OCM scheme (S.K. Oh et al., (2003)). In the proposed scheme, all the subcarriers are divided into multiple subcarrier groups, in which each group is composed of only relatively less correlated subcarriers. The scheme then transmits modulation symbols through two-step interleaving and groupwise OCM. As a proper set of VLG orthogonal codes, and use the set of discrete Fourier transform (DFT) codes. Also consider the coded and uncoded VLG-OCM OFDM systems. Finally, evaluate the bit error rate (BER) performance and the complexity according to the OCM code length.