Equalization techniques for space-time coded cooperative systems

We extend three equalization schemes proposed originally for conventional space-time block codes (STBC) (Lindskog, E. and Paulraj, A., Proc. Int. Conf. Commun., 2000; Al-Dhahir, N., IEEE Commun. Lett., vol.5, no.7, 2001; Liu, Z. et al., Proc. 33rd Asilomar Conf. on Sig., Systems, and Comp., 1999). We extend them to cooperative schemes, carefully exploiting the underlying orthogonality of STBC. These three distributed schemes are named after their conventional counterparts as distributed time-reversal (DTR) STBC, distributed single-carrier (D-SC) STBC and distributed orthogonal frequency division multiplexed (DOFDM) STBC. Considering the special case of single relay employment, our performance analysis for frequency-selective fading channels of memory L demonstrates that the D-TR-STBC and D-SC-STBC schemes are able to achieve a maximum diversity order of 2(L+1) under the assumption of appropriate power control imposed on the relay terminal and high signal-to-noise ratio for the source-to-relay link. Extensive Monte-Carlo simulation results confirm the analytical results.