Enhanced beamforming for 60GHz OFDM system with co-channel interference mitigation

Abstract

Beamforming is one of the key technique for 60GHz wireless system to work at this millimeter-wave region with high propagation path loss. In IEEE 802.15.3c standard, a codebook based analog beamforming mechanism is adopted for its simplicity and feasibility. However, this simple beam sweep mechanism may not work properly in the presence of Co-Channel Interference (CCI) when dense spatial reuse is required. In this paper, an enhanced beamforming technique is proposed with mixed analog and digital beamforming structure for 60GHz Orthogonal Frequency Division Multiplexing (OFDM) system. Beam sweep mechanism with such as codebook based phased antenna array can be applied to analog beamforming for its hardware simplicity. On the other hand, more than one RF chains can be introduced to enable adaptive digital beamforming for improved performance and robustness. A Minimum Mean Square Error (MMSE) based switched beam or beamforming codeword selection algorithm is proposed for this mixed analog/digital beamforming structure to achieve enhanced interference mitigation and spatial reuse capability in the presence of CCI.