Multi-Pair Two-Way Massive MIMO Relaying With Zero Forcing: Energy Efficiency and Power Scaling Laws

Abstract

In this paper, we study a multi-pair two-way half-duplex decode-and-forward (DF) massive multiple-input multiple-output (MIMO) relaying system, in which multiple single-antenna user pairs can exchange information through a massive MIMO relay. For low-complexity transmission, zeroforcing reception/zero-forcing transmission (ZFR/ZFT) is employed at the relay. First, we analytically study the large-scale approximations of the sum spectral efficiency (SE). Furthermore, we focus on three specific power scaling laws to study the tradeoff between the transmit powers of each pilot symbol, each user and the relay, and also focus on how the transmit powers scale with the number of relay antennas, M, to maintain a finite SE performance. Additionally, we consider a practical power consumption model to investigate the energy efficiency (EE), and illustrate the impact of M and the interplay between the power scaling laws and the EE performance. Finally, we consider the system fairness via maximizing the minimum achievable SE among all user pairs. Index Terms-Decode-and-forward relaying, half-duplex, massive MIMO, Max-min fairness, power scaling laws, spectral efficiency and energy efficiency, zero-forcing.

Transmission Schemes and Power Allocation for Multiuser Massive MIMO Relaying

“…More specifically, [13] revealed that by utilizing massive antennas at the base station, the performance loss due to the low-resolution ADCs can be compensated. Further investigations on multipair systems have been recently reported in [9], [14]. In [9], the energy efficiency and power scaling laws of multipair two-way massive MIMO relaying systems with zero-forcing were examined.…”

On the Effects of Channel Aging in D2D Two-Way Relaying with Space-Constrained Massive MIMO

“…As per the Multiple Access Broadcast (MABC) protocol [5], the two-way relayed D2D data transmission process is divided into two stages with equal time slots. At the time instant n, all devices transmit signals to the relay simultaneously in the Multiple Access Channel (MAC) phase and the received signal at the relay is given by [6], [9], [11]…”

“…Additionally, supported by Eqns. ( 15)-( 18) and the standard lower capacity bound with the worst-case uncorrelated additive noise [9], the respective…”

“…Moreover, the proven SE benefits of massive multiple-input multiple-output (MIMO) have promoted its use in the multipair two-way relay systems [7], [8]. Multi-pair two-way massive MIMO relaying with imperfect channel state information (CSI) has been studied since perfect CSI is impossible in most practical scenarios [6], [9]. Additionally, channel aging making the estimated CSI out of date has been introduced in the multipair massive MIMO relay system, most of the relevant studies are operated in full-duplex AF mode [3], [10], [11] or halfduplex AF mode [10], while multi-pair D2D two-way halfduplex DF relay system with channel aging is overlooked.…”

“…In addition, employing large antenna arrays in constrained space leads to the consideration of spatial correlation [12], [13], which is rarely considered in the multi-pair half-duplex DF two-way relayed D2D communication systems. To this end, based on the studies in [9], a detailed analysis of the achievable SE performance of a multi-pair D2D two-way massive MIMO half-duplex relay system under DF protocol considering both the spatial correlation due to the space-constrained antenna deployment and the time correlation due to channel aging is presented. As shown in Fig.…”