Channel estimation techniques for half-duplex cooperative communication systems

In this work we present efficient channel estimation algorithms for wideband detect-and-forward (DF) based relay networks. A generalization of a recently proposed transmission model is utilized and the analysis is completely performed in the frequency domain (FD). It is shown that all channels in the network from any node to the destination/receiver node can be blindly estimated up to a phase ambiguities vector, related to the source to destination channel frequency response. Hence, by utilizing a small number of pilot symbols, phase ambiguities can be effectively resolved. As verified by computer simulations, the proposed methods exhibit high estimation accuracy even for a short training sequence, and outperform direct training-based channel estimation. A performance study of the proposed schemes in high SNR conditions is also presented and verified through computer simulations.