Scalable ASIP implementation and parallelization of a MIMO sphere detector

High detection complexity is known to be one of the major challenges in MIMO communications based on spatial multiplexing. Tuple Search Detector (TSD) was recently introduced, significantly reducing detection complexity in comparison to conventional algorithms while achieving close to full max-log-APP BER performance. Besides high computational complexity, irregular control flow and sequential nature of the tree search represent major limitations of depth-first-based detectors, frustrating efficient application of parallelization techniques and hence leading to inefficient realizations with regard to most practical applications. This work presents a novel TSD implementation, scalable in constellation size and number of antennas and mapped to a highly parallel and pipelined ASIP architecture. Major challenges and key strategies enabling a high-throughput and low-complexity realization are presented and performance of the resulting flexible and efficient detector implementation is evaluated. Proposed realization is shown to achieve >; 300 Mbps throughput at a reference clock frequency of 400 MHz (regarding 4×4 MIMO transmission with 16-QAM), by far outperforming comparable state-of-the-art realizations.