60-GHz adaptive beamforming receiver arrays for interference mitigation

This paper describes a millimetre-wave receiver beamforming for interference mitigation as well as array gain enhancement. Like the beamforming architecture in the IEEE 802.15.3c standard, it is based on only one baseband processor to support multiple N-element antenna arrays for low-cost implementation. This makes it difficult to estimate received signals and channel state information on each antenna, which restricts baseband digital processing and introduces large overheads for adaptive beamforming. For these reasons, the IEEE 802.15.3c standard utilizes 2-bit beam codebook for repetitive beam-searching, however it cannot offer adaptive interference nulling capability. We propose an algorithm to get received signal information on each antenna so that we can find optimum weight vectors for maximum beamforming gain. This also enables to mitigate co-channel interference, which increase total throughput by enhancing spatial re-use in multiple 60-GHz indoor networks. The structural difference from the IEEE 802.15.3c beamformer is to employ a continuous phase-shifter, however our implementation proves that it exhibits almost same-level complexity as 2-bit phase-shifters.