A power loading scheme for space-time trellis codes based on channel magnitude feedback

In this paper, we present a novel power loading scheme for several existing space-time trellis codes (STTCs). These STTCs are originally designed for the open loop systems where no channel state information is available at the transmitter. To further enhance the performance of these STTCs, we assume that the scalar quantized channel magnitude information is available at the transmitter through a feedback channel. Therefore, the error performance of these STTCs is improved through proper power loading on the different transmit antennas. To calculate the power loading parameters, we derive the distance spectrum of these STTCs based on the channel magnitude information. We also use a novel transfer function analysis to optimize the overall distance spectrum. The proposed power loading algorithm is flexible enough to be applied for various kinds of existing STTCs and it also enjoys easy implementation at the transmitter. Finally, numerical simulations show that the new power loading scheme accomplishes superior performance compared to several widely used open loop algorithms as well as some popular closed loop algorithms in the literature