Design of single carrier beamforming systems for MIMO communications in wideband millimeter wave channel

Abstract

A way to solve the ever-increasing demand for mobile data traffic is to utilize a broadband millimeter wave resources. In order to effectively utilize wideband channels at high frequencies, high path loss and frequency selective fading should be overcome. In particular, when a signal is transmitted at a high data rate, as the symbol interval becomes shorter than the spread delay of a wideband channel, inter-symbol interference (ISI) occurs in which symbols transmitted at different times overlap each other. As a method of securing a symbol interval preventing signal overlap, data can be transmitted by dividing a wideband channel into several subcarriers. However, when a larger number of subcarriers are used according to bandwidth expansion and a higher data rate is required, power consumption significantly increases and effective wireless data transmission efficiency may be quite low due to constraints in hardware implementation. This dissertation deals with the single carrier system that does not divide broadband channels to reduce power consumption. We design transmit and receive beamforming that mitigates ISI in a single carrier system where ISI occurs, and further propose an optimal design algorithm for hybrid beamforming that reduces power consumption and implementation complexity. In addition, by analyzing the interference mitigation capability of the proposed beamforming design, an algorithm improvement method for efficiently finding an optimal solution and a suitable system parameter selection method are provided.