An algorithm approach to optical true time delay pool enabled centralized control beamforming for wireless base station

Abstract

In this paper, we propose an optimized approach to generation algorithm of optical true time delay pool (OTTD-P), by building the forbidden wavelength spacing matrixes (FWSMs), for the centralized control of beamforming (CCBF) system. In this optimized generation algorithm, we simplify the complex processes in the traversal process by FWSMs, so only a simple 0/1 decision is needed in the traversal cycle. And the design of OTTD-P correspondingly changes into a compatibility problem of the wavelength sequence heads. Moreover, a proof-of-concept CCBF system with 8-element phased array antennas is demonstrated to verify the feasibility of the optimized generation algorithm, in which 12 basic beam directions based on a 29.5 GHz millimeter wave signal are formed to provide a 360-degree beam steering. The time complexity of processes in the traversal algorithm is about 7×1023 steps which is a product of 2376 steps in the verification process and 3×1020 steps in the traversal process. But the time complexity is only about 2×1010 steps in the optimized generation algorithm. Finally, based on the optimized generation algorithm, a compression of needed optical wavelengths can be achieved and the rate of compressed-to-uncompressed (CTU) optical wavelengths decreases from 95% to 19% with the increasing beam directions.