Adaptive Modulation for Space-Time Trellis Coded Multiple Input Multiple Output Systems with Imperfect Channel State Information

Here it is proposed a novel adaptive transmission scheme for space-time trellis coded multipleinput multiple-output beamforming systems with imperfect channel state information at the transmitter, of which the signal constellation, total transmit power (temporal power), and power allocation among eigenbeams (spatial power) are jointly adapted to maximize the average spectral efficiency, subject to a target bit-error-rate and an average power constraint. The power allocation over the spatial and temporal domains makes the traditional approach of partitioning the received signal-to-noise ratio (SNR) inapplicable to the above design problem. By introducing a new variable, called as effective signal-tonoise-to-modulation ratio (ESNMR), we derive a rate-selection policy by partitioning the range of the ESNMR with an optimal set of thresholds. A closed-form temporal power control policy and a simple spatial power allocation algorithm are also obtained. Numerical results demonstrate that the new adaptive transmission scheme yields a significant performance gain over existing adaptation systems.