Optimal Energy-Efficient Relay Deployment for the Bidirectional Relay Transmission Schemes
Optimal Energy-Efficient Relay Deployment for the Bidirectional Relay Transmission Schemes
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DOI：
10.1109/tvt.2013.2295413
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发表时间：
2014-07
影响因子：
6.8
通讯作者：
Qimei Cui;Xianjun Yang;Jyri Hämäläinen;Xiaofeng Tao;Ping Zhang
中科院分区：
文献类型：
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作者：
Qimei Cui;Xianjun Yang;Jyri Hämäläinen;Xiaofeng Tao;Ping Zhang
近年来，中继网络的能效问题已成为无线通信领域的研究热点。本文从中继部署的角度研究了三种基本的双向中继传输方案（即四时隙（4TS）、三时隙（3TS）和两时隙（2TS））的能量效率。由于一个真实的功耗模型在分析能效时非常重要，而功率放大器（PA）的功耗高达总功率的70%，因此我们考虑一个真实的非理想PA模型。推导出的继电器最优配置的封闭表达式和仿真结果揭示了以下重要结论：首先，在恶劣的信道条件下，可以同时实现最佳的能量效率和扩大蜂窝覆盖范围，但在良好的信道条件下，这可能是非常具有挑战性的。其次，在非对称流量条件下，特别是下行速率大于上行速率时，上述三种方案的中继最优部署几乎相同，但在频谱效率较大时，2TS方案的能量效率最高。第三，中继节点应部署在离非理想扩音器基站较近的位置，且非理想扩音器的最优能效远高于理想扩音器。此外，小尺度衰落的影响取决于路径损耗的大小。为了克服小尺度衰落，中继网络需要消耗更多的能量。
Recently, the energy efficiency of a relay network has become a hot research topic in the wireless communication society. In this paper, we investigate the energy efficiency of three basic bidirectional relay transmission schemes [i.e., the four time-slot (4TS), three time-slot (3TS), and two time-slot (2TS) schemes] from the angle of relay deployment. Since a realistic power consumption model is very important in analyzing energy efficiency, and a power amplifier (PA) consumes up to 70% of the total power, we consider a realistic nonideal PA model. The derived closed-form expressions for the optimal relay deployment and the simulation results reveal the following important conclusions. First, it is possible to achieve the optimal energy efficiency and enlarge the cell coverage simultaneously in bad channel conditions, but it may be very challenging in good channel conditions. Second, under asymmetric traffic conditions, particularly when the downlink rate is larger than the uplink rate, all the aforementioned three schemes have almost the same optimal relay deployment, but the 2TS scheme has the highest energy efficiency when the spectral efficiency is large. Third, the relay node should be deployed closer to the base station with the nonideal PA than that with the ideal PA, and the optimal energy efficiency with the nonideal PA is much higher than that with the ideal PA. Moreover, the impact of small-scale fading depends on the value of path loss. To overcome the small-scale fading, the relay network needs to consume more energy.