Methods for channel estimation in ofdma based hybrid beamforming (hbf) systems

Abstract

The method is for channel estimation with transmitter (Tx) and receiver (Rx) beam training in an OFDMA HBF system wherein the transmitter and receiver communicate over a channel and each include a plurality of Radio Frequency (RF) chains and an antenna array of antenna elements corresponding to each RF chain, and wherein the transmitter includes an analog beamformer and the receiver includes an analog combiner. The method includes generating a set of orthogonal Tx training beams for the transmitter based upon a number of antenna elements in the transmitter antenna array, and generating a set of orthogonal Rx training beams for the receiver based upon a number of antenna elements in the receiver antenna array. The method includes probing the channel by simultaneously transmitting OFDMA preambles with each RF chain using a different one of the orthogonal Tx training beams and receiving the OFDMA preambles with each of the orthogonal Rx training beams in a scheduling sequence that includes a pairing of each orthogonal Tx training beam with each orthogonal Rx training beam, and performing channel estimation based upon probing feedback results including a channel response between different pairs of the orthogonal Tx training beams and the orthogonal Rx training beams.