Performance comparison of distributed IDM-STC versus cooperative OFDM for practical decode-and-forward relay-networks

In this paper, we compare two different multiplexing strategies for a two-hop parallel relay channel. Precisely, we show the performance of distributed Interleave-Division-Multiplexing Space-Time Coding (dIDM-STC) and cooperative Orthogonal Frequency Division Multiplexing (cOFDM) operating in a decode-and-forward relay network, under the constraint of imperfect channel knowledge and timing and carrier frequency offsets. These impairments have to be estimated with either a complete pilot layer in dIDM-STC or orthogonal pilot symbols in cOFDM. While both schemes can cope with timing offsets of integer multiples of the sampling interval very well, cOFDM requires an adjustment of all transmit frequencies in order to avoid inter-carrier interference which would destroy orthogonality of the subcarriers and lead to severe performance degradations.