FPGA implementation of 1 Gbps real-time 4×4 MIMO-MLD

We developed two types of practical maximum-likelihood detectors (MLD) for multiple-input multiple-output (MIMO) systems with 1 Gbps-order real-time processing speed, using an FPGA device. We introduce two simplified metrics for implementations; referred to as a Manhattan metric and a correlation metric. In using the Manhattan metric, the detector needs no multiplication operations, at the cost of slight performance degradation within 1 dB. By using the correlation metric, the MIMO-MLD can significantly reduce the complexity in both multiplications and additions without any performance degradation. This paper demonstrates the BER performance of these MLD prototypes through the use of an all-digital baseband 4×4 MIMO testbed integrated on the same FPGA chip.