Orthogonal-like space-time coded CPM with fast demodulation for three and four transmit antennas

The Alamouti´s orthogonal space-time block codes are for QAM modulations and two transmit antennas. We have recently generalized it for the continuous phase modulation (CPM) by maintaining the orthogonality (for the fast ML decoding/demodulation) and the phase continuity of two signals from two transmit antennas denoted as OST-CPM. In this paper, we design orthogonal-like space-time coded CPM systems for three and four transmit antennas based on the existing orthogonal and quasi-orthogonal space-time codes in the literature. Although the signals from the transmit antennas in the proposed orthogonal-like space-time coded CPM systems are not orthogonal, the fast decoding/demodulation is maintained as in the two transmit antenna case. Simulation results show that the performance of the proposed orthogonal-like space-time coded CPM systems for four transmit antennas is much better than that of the OST-CPM systems for two transmit antennas.