Dynamic Transmit Power Allocation in Space-Time Trellis Coded Systems

Space-time trellis codes (STTCs) have been shown to efficiently use transmit diversity to improve error performance. In existing STTCs, the transmit power is equally distributed across all transmit antennas. In fact, when feedback information is available at the transmitter, the equal power allocation strategy is not optimum regarding the error performance. In this paper, we propose a new scheme, referred to as space-time trellis codes with dynamic transmit power allocation (STTCs/DTPA), when partial channel state information (CSI) is available at the transmitter. A closed-form pairwise error probability (PEP) upper bound is derived. The optimum power allocation scheme and the code design criteria, based on the PEP upper bound, are proposed. Theoretical and simulation results show that the proposed scheme performs much better in terms of error probability than the general open-loop STTCs and other closed- loop transmit diversity schemes. For example, the new 16-state STTCs/DTPA scheme is 5.6 dB better than the standard 16-state Chen/Yuan/Vucetic code for three transmit antennas.