Space diversity schemes with feedback for three transmit antennas

In this paper, we propose two-space diversity schemes with feedback for three transmit antennas which perform independently for each signaling interval. The first one is a pure code selection technique which provides, with two feedback bits, an E_b/N₀ advantage of nearly compared to the pure antenna selection technique where the best one of the three antennas is used. The second one is a hybrid selection scheme which consists of a combination of antenna and code selection techniques. The selection is performed out of 13 possible precoding vectors requiring four feedback bits, to maximize the diversity for all possible channel situations. It was shown by computer simulations that E_b/N₀ gains of approximately 1.25 and are possible, compared to the pure antenna selection and code selection schemes, respectively. Mapping rules between feedback codewords and precoding vectors, which results in improvement over random mapping, are obtained to minimize the error probability in the case of feedback errors.