Performance Investigation of Distributed STBC-OFDM System with Multiple Carrier Frequency Offsets

In the distributed space time block coded (DSTBC) orthogonal frequency division multiplexing (OFDM) system (DSTBC-OFDM), since the transmit antennas belong to different nodes that are distributed, there may exist multiple carrier frequency offsets (CFOs) to the transmitters at the receiver. Several kinds of equalization techniques, which intend to mitigate the intercarrier interference (ICI) when detecting symbols, are compared in terms of the BER performance. And an equalization method based on iterative ICI cancellation is proposed. Simulation results show that when the difference of normalized CFOs (with respect to the subcarrier spacing) between distributed transmitters is not more than 0.2, the proposed iterative ICI cancellation method could combat ICI effectively at very low computational cost. However, in case of large difference of normalized CFOs, i.e., 0.4, the frequency offsets could cancel the space diversity gain of distributed STBC totally even when ideal ICI cancellation is assumed, and the performance is close to that of OFDM system using single transmit antenna without space time block coding