An improved numerical optimization method for efficient beam search in 60 GHz indoor millimeter wave wireless networks

Directional communication is a key element in the sustenance of high data rate links in millimeter wave communications, and can be realized using antenna beamforming. To reduce training overhead and establish a reliable link in indoor millimeter wave communications, the beam switching technique is adopted with an objective to identify the optimal transmit-receive beam pair that maximizes the signal-to-noise ratio. Numerical optimization techniques based on direct search further seek to reduce the search complexity. The existing methods explored in literature work effectively for relatively smooth objective functions. However, indoor millimeter wave channels are typically characterized by non-smooth complicated objective functions. In this paper we propose a numerical search algorithm based on the Rosenbrock's direct search technique applicable for 60 GHz indoor millimeter wave systems. The proposed method is shown to yield an improved search success percentage during the beam search procedure without affecting the search complexity as compared to state-of-the-art techniques.