Browsing by Author "Tang, Mengxue"
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Item LI Cancellation and Power Allocation for Multipair FD Relay Systems with Massive Antenna Arrays(IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2019-08-01) Tang, Mengxue; Vehkapera, Mikko; Chu, Xiaoli; Wichman, Risto; Dept Signal Process and Acoust; Risto Wichman Group; University of SheffieldMassive antenna arrays are capable of canceling out the loop interference (LI) at the relay station in multipair full-duplex (FD) relay networks even without LI channel knowledge if the number of antennas is allowed to grow without a bound. For large but finite number of antennas, however, channel estimation-based LI cancelation is required. In this letter, we propose a pilot protocol for LI channel estimation by exploiting the channel coherence time difference between static and moving transceivers in a multipair FD relay system. To maximize the end-to-end achievable rate, we also design a novel power allocation scheme to adjust the transmit power of each link at the relay. The analytical and numerical results show that the proposed novel pilot protocol and power allocation scheme jointly improve spectral and energy efficiency significantly with realistic coherence time differences.Item Power allocation for multipair massive MIMO FD relay systems with low resolution ADCs(2019-08-01) Tang, Mengxue; Vehkapera, Mikko; Chu, Xiaoli; Wichman, Risto; Dept Signal Process and Acoust; Risto Wichman Group; University of SheffieldTo reduce energy consumption, relay stations with massive antenna arrays can be equipped with low resolution analog-to-digital converters (ADCs). Due to powerful loop interference in full-duplex (FD) relaying, however, low resolution ADCs generate strong quantization noise that has severe impact on the throughput of the system. In this paper, the throughput and energy efficiency of a FD decode-and-forward relay system with low resolution ADCs is investigated. Based on the mathematical analysis, a novel iterative power allocation scheme that mitigates the impact of the quantization noise via reducing the received LI power is proposed. The power allocation scheme aims at maximizing the end-to-end achievable rate by adjusting the per-link transmit powers at the relay. The numerical results show that compared to half-duplex relaying, using FD with the proposed power allocation scheme improves the system throughput and energy efficiency significantly.