Linear dispersion space-time codes for frequency selective fading channels

Multiple antenna systems that operate at high rates require simple yet effective space-time transmission schemes to handle the large traffic volume in real time. In the last investigations, LD (linear dispersion) codes were proposed that can handle any configuration of transmit and receive antennas for frequency non-selective fading channels. This scheme transmits substreams of data in linear combinations over space and time and the codes are designed to optimize the mutual information between the transmitted and received signals with low complexity decoding. In this paper we try to design LD codes for frequency selective fading channels. We suppose that in each signaling interval, L independent copy of transmitted signals arrive at each receiver antenna. We first focus on the structure of such a system in the presence of LD codes and extract the capacity relation of a multiple antenna system in a frequency selective fading channel. Then we exploit the capacity formula to find the best LD codes that can reach the capacity.