Timing estimation in multiple-antenna systems over Rayleigh flat-fading channels

The use of multiple transmit and receive antennas can offer substantial performance improvement to a wireless communication system by providing spatial diversity and supporting high data rate services. Many of the current space-time coding schemes proposed for multiple-antenna systems assume perfect timing information to achieve the expected performance gain. The lack of timing synchronization between the transmit and receive signals could degrade the system performance. In this paper, we investigate the problem of timing estimation in multiple-antenna systems with the aid of training signals. A slow, independent and identically distributed Rayleigh flat-fading channel model is considered. We derive two maximum likehood timing estimators based on two different approaches, namely, treating the channel deterministic and random and present the corresponding Crame´r-Rao bounds (CRBs). Then, the optimal designs of training signals based on some figures of merit associated with the CRBs are discussed.