An improved detection algorithm for MIMO-OFDM beamforming system with dynamic subchannel allocation

Dynamic subchannel allocation based MIMO-OFDM beamforming system outperforms conventional MIMO-OFDM beamforming system with considerable gain. Unfortunately, the imperfect channel state information, which is due to processing or feedback time delay, will be used by the transmitter to transmit data symbols. The resulted inter-streams interference will degrade the system performance significantly. In this paper, an improved detection scheme is proposed to combat effectively with this interference according to the analysis of the effect due to delay. By constructing equivalent MIMO system model, the inter-streams interference is suppressed though MIMO detection algorithms. Furthermore, eigenvalue decomposition of equivalent MIMO channel is applied to whiten the noise so that equivalent Gaussian channel model can be obtained to compute the log-likelihood ratio of coded bits. Simulation results show the proposed detection scheme outperforms conventional scheme with a gain of 2.5~4 dB.