Beamforming Synthesis for Initial Access Fairness in Wireless Networks

This article introduces an Initial Access Fairness Beamforming (IAFB) approach for wireless networks using millimeter wave and terahertz frequencies and proposes novel synthesis method. The fairness is establishing independence between user location and the initial access signals received power level. We propose codeword synthesis with phase-only control which is beneficial for passive implementation of the receiver (Rx) and improves power utilization at the transmitter (Tx), which reduces mutual coupling impact for both Rx and Tx directions. In contrast to classical shaped beam synthesis methods where desired radiation patterns are targeted, we target the fairness of the received power distribution at the desired coverage area by solving a multi-objective nonconvex optimization problem. We address the known nonconvex optimization issues of initial state sensitivity and convergence rate by splitting the problem into a sequence of concatenated sub-problems, where the solution of one sub-problem defines the initial state for the next sub-problem.