IMPROVING SNR AND MINIMIZING INTERFERENCE FOR 8X8 MU-MIMO SYSTEMS DOWNLINK WITH A FIXED-COMPLEXITY SPHERE DECODER AND BD, OBD AND SIC TECHNIQUES

This study presents an interference mitigation strategy and a fixed-complexity sphere decoder (FSD) for downlink (DL) multiuser (MU) multiple-input multiple-output (MIMO) systems. An hardware-friendly optimal interference mitigation technique is presented to reduce the effect of inter-user interference on the performance of DL MU-MIMO systems. The suggested method outperforms the current interference whitening filter by 4 dB, performing 0.5 dB near-optimally for the soft-output choice. In order to offer 8X8 antenna MIMO detection and interference mitigation for 4 extra streams, the suggested interference mitigation technique is used to both hard and soft-output FSD detectors in this work. Additionally, Block Diagonalization (BD) and Optimized Block Diagonalization (OBD) techniques are used. Lastly, Successive Interference Cancellation (SIC) is used prior to transmission in order to minimize interference and reduce it to lower levels. For signals modulated by 64-QAM, 3.6 Gbps @ 150 MHz is supported using a fully pipelined architecture. The planned symbol detector, according to the synthesis result, has a gate count of 1220 K for interference mitigation and 887 K for the FSD without a pre-processor. The suggested architecture for DL MU-MIMO systems shows promise in terms of a notable improvement in performance with regard to inter-user interference when compared to previously deployed MIMO detectors.

Keywords: Fixed-Complexity Sphere Decoder (FSD), Block Diagonalization (BD), 8X8 Antenna MU-MIMO, Optimized Block Diagonalization (OBD), Successive Interference Cancellation (SIC). b