Multipair Full-Duplex Relaying With Massive Arrays and Linear Processing
Multipair Full-Duplex Relaying With Massive Arrays and Linear Processing
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DOI：
10.1109/jsac.2014.2330091
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发表时间：
2014-05
影响因子：
16.4
通讯作者：
H. Ngo;H. Suraweera;M. Matthaiou;Erik G. Larsson
中科院分区：
文献类型：
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作者：
H. Ngo;H. Suraweera;M. Matthaiou;Erik G. Larsson
我们考虑一个多对解码和转发中继信道，其中多个源同时发送他们的信号到多个目的地的帮助下，一个全双工中继站。我们假设中继站配备了大量的阵列，而所有的源和目的地有一个单一的天线。中继站使用从接收到的导频和迫零（ZF）或最大比组合/最大比传输（MRC/MRT）获得的信道估计来处理信号。为了显著地减少环路干扰效应，我们提出了两种技术：i）使用大规模接收天线阵列;或者ii）在中继站处使用大规模发射天线阵列以及非常低的发射功率。我们推导出一个精确的可实现的速率表达式在封闭形式的MRC/MRT处理和ZF处理的可实现的速率的解析近似。这种近似是非常严格的，特别是对于大量的中继站天线。这些封闭形式的表达式使我们能够确定全双工模式优于半双工模式的区域，以及设计一个最佳的功率分配方案。这种最优功率分配方案的目标是在中继站和源的峰值功率约束下，在给定的频谱效率和下，最大化能量效率。数值结果验证了最优功率分配方案的有效性。此外，我们表明，通过加倍的中继站的发射/接收天线的数量，每个源和中继站的发射功率可以减少1.5 dB，如果导频功率等于信号功率，和3 dB，如果导频功率保持固定，同时保持给定的服务质量。
We consider a multipair decode-and-forward relay channel, where multiple sources transmit simultaneously their signals to multiple destinations with the help of a full-duplex relay station. We assume that the relay station is equipped with massive arrays, while all sources and destinations have a single antenna. The relay station uses channel estimates obtained from received pilots and zero-forcing (ZF) or maximum-ratio combining/maximum-ratio transmission (MRC/MRT) to process the signals. To significantly reduce the loop interference effect, we propose two techniques: i) using a massive receive antenna array; or ii) using a massive transmit antenna array together with very low transmit power at the relay station. We derive an exact achievable rate expression in closed-form for MRC/MRT processing and an analytical approximation of the achievable rate for ZF processing. This approximation is very tight, particularly for a large number of relay station antennas. These closed-form expressions enable us to determine the regions where the full-duplex mode outperforms the half-duplex mode, as well as to design an optimal power allocation scheme. This optimal power allocation scheme aims to maximize the energy efficiency for a given sum spectral efficiency and under peak power constraints at the relay station and sources. Numerical results verify the effectiveness of the optimal power allocation scheme. Furthermore, we show that, by doubling the number of transmit/receive antennas at the relay station, the transmit power of each source and of the relay station can be reduced by 1.5 dB if the pilot power is equal to the signal power, and by 3 dB if the pilot power is kept fixed, while maintaining a given quality of service.