Nulling and cancellation detector for MIMO channels and its application to multistage receiver for coded signals: performance and optimization

In this paper, we address some performance issues of multiple input multiple output (MIMO) channels with a nulling and cancellation (N/C) detector, which is based on the QR factorization. We find a theoretical bit error rate (BER). With this, an optimization for the bit energy allocation across multiple transmitter antennas has been considered with the proposed optimization criterion. In addition, the concept of multilevel coding has been adopted for optimizing the performance of a multistage receiver with the N/C detector when a channel code is employed. Through simulations, the performance has been compared for coded signals. Both the code rate and energy optimization across layers are shown to be effective means for improving the performance of MIMO systems when the multistage receiver is employed. In addition, it has been shown that the optimization of code rate for each layer is more effective means than that of bit energy.