A Delay Diversity Code for Frequency Selective Channels

Introduction: There is increasing interest [1], [2], [3], [4] in space-time coding for multiple input multiple output (MIMO) frequency selective wireless channels. This paper addresses space-time code design for such channels from a single carrier perspective. We derive code construction criterion for exploiting full spatio-temporal diversity in the channel. We analyze the delay diversity code [5] in the presence of delay spread and show that it does not exploit full spatio-temporal diversity. We propose a generalized delay diversity code which adapts the code delay to the delay spread and show that it exploits full spatio-temporal diversity. We support our analysis through simulations. Signal and Channel Model: Consider a point-to-point multiple antenna wireless link with MT transmit and MR receive antennas. The channel between the t transmit and r receive antenna is frequency selective and its symbolsampled baseband impulse response hr,t has L taps as follows