Robust null-forming in a mm-wave adaptive array with discrete phase shifting schemes

In future dense 60 GHz wireless environments, cochannel interference (CCI) is a potential problem degrading the link quality. In [1], a genetic algorithm (GA) assisted analog adaptive array was proposed for 60 GHz applications to mitigate the CCI. The array optimizes the least-significant-bits of the discrete weights on each receiver path, so that the nulls in the array’s antenna pattern are adjusted to the interference direction resulting in an improved signal-to-interference-plus-noise ratio (SINR). In this paper, we propose two different phase shifting schemes in a 60 GHz sliding-IF receiver front-end, in LO path and in baseband respectively. High resolution is targeted for the GA assisted null-forming array. Simulations of the two sets of constellation points by the two schemes allow verifying the performance of the adaptive array. The results show that the SINR can be improved significantly and efficiently. This paper further demonstrates that the optimization is robust against random weighting errors which is common in practice.