Performance of Cyclic Delay Diversity in Ricean Channels

Abstract

Cyclic delay diversity (CDD) provides additional diversity in Rayleigh fading channels, and therefore, improves system performance. For line-of-sight (LOS) propagation, e.g. the additive white Gaussian noise channel, the implementation of CDD yields to a performance loss. Therefore, we investigate CDD for Ricean channels with different Ricean factors. To combat the SNR loss for significant LOS propagation we propose the principle of antenna power weighting. The idea is to feed different power levels into the multiple transmit (TX) antenna branches rather than distributing the TX power uniformly among the TX-antennas. We exemplarily implement CDD with antenna power weighting to the terrestrial digital video broadcasting system (DVB-T). Simulation results show that antenna power weighting significantly reduces the SNR loss in LOS propagation by the cost of a slight degradation of the SNR gain in non-LOS scenarios.