Design and implementation of a high throughput soft output MIMO detector

In this paper, a new soft output MIMO decoder based on the k-best search scheme and additional partial Euclidian distance (PED) update schemes is developed. The k-best framework facilitates a constant throughput implementation and the PED update schemes help achieve a more accurate log-likelihood ratio (LLR) calculation. A LLR clamping technique is further adopted to enhance the BER performance when combining with the LDPC coding. Simulation results indicate the effectiveness of the proposed PED update schemes against previous works. Efficient architecture design is next developed capable of accomplishing one 4×4 MIMO signal vector detection every 4 clock cycles. In FPGA implementation, the maximum working frequency can be up to 121.3MHz and suggests a 720Mbps data rate for a 4×4 MIMO system using 64QAM modulation.