Distributed STBC-OFDM and Distributed SFBC-OFDM for Frequency-Selective and Time-Varying Channels

Distributed space-time block coding with orthogonal frequency division multiplexing (DSTBC-OFDM) and distributed space-frequency block coding with orthogonal frequency division multiplexing (DSFBC-OFDM) are introduced in this paper. Unlike the original DSTBC scheme which was designed for networks with a fixed number of relays operating in frequency-nonselective channels with insignificant Doppler spread, the proposed schemes are designed specifically for networks with an arbitrary number of relays and wireless channels with significant delay spread and Doppler spread. It is shown that geographically distributed antennas employing the new transmission schemes in a frequencyselective and severe Doppler spread environment can achieve the same performance (in terms of diversity gain and coding gain) as the previously proposed scheme.