Direction-time transmission for fast fading vector channel

Transmit diversity and space-time coding have received a lot of attention in previous years. We propose a direction-time transmit scheme for a fast block fading channel which exploits the parametric structure of the time-varying vector channel. Specular propagation and local scattering are assumed at the base-station and mobile station respectively. The partial channel knowledge needed for the transmit design includes: the number of specular paths, path direction vectors and length of the coherent interval. Transmission matrix codewords are formed according to this partial channel information such that multiple channels are induced and symbols are spread over different transmission directions. Diversity gain and blind channel estimation are achieved simultaneously at the mobile station through equalization