Exploiting Direct Links in Multiuser Multirelay SWIPT Cooperative Networks With Opportunistic Scheduling
Exploiting Direct Links in Multiuser Multirelay SWIPT Cooperative Networks With Opportunistic Scheduling
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DOI：
10.1109/twc.2017.2710307
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发表时间：
2017-06
影响因子：
10.4
通讯作者：
Nhu Tri Do;D. B. da Costa;T. Duong;Vo Nguyen Quoc Bao;Beongku An
中科院分区：
文献类型：
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作者：
Nhu Tri Do;D. B. da Costa;T. Duong;Vo Nguyen Quoc Bao;Beongku An
本文分析了由一个源、多个射频能量收集中继和多个目标组成的双跳合作网络中机会调度的下行中断性能。为此，提出了两种低复杂度、次优但高效的中继目的地选择方案，即直接链路加机会主义信道状态信息（CSI）的选择（DOS）方案和直接链路加部分基于CSI的选择（DPS）方案。考虑译码转发（DF）、变增益放大转发（VG-AF）和定增益放大转发（FG-AF）三种中继策略，从中断概率（OP）的角度对每种选择方案进行性能分析。对于DF和VG-AF策略，导出了OP的精确解析表达式和紧闭近似表达式。对于FG-AF策略，提供了OP的精确封闭形式表达式。此外，我们提出了一种基于梯度的搜索方法来寻找功率分割比的最优值，使达到的OPs最小。通过蒙特卡罗仿真验证了本文的分析结果。与最优联合选择方案进行了比较，表明所提出的方案在获得相当的中断性能的同时显著减少了信道估计量。此外，无论采用何种中继策略，数值结果表明，DOS方案实现了完全的分集增益，即$M+K$， DPS方案实现了$M+1$的分集增益，其中$M$和$K$分别为目的地和中继的数量。
In this paper, we analyze the downlink outage performance of opportunistic scheduling in dual-hop cooperative networks consisting of one source, multiple radio-frequency energy harvesting relays, and multiple destinations. To this end, two low-complexity, suboptimal, yet efficient, relay-destination selection schemes are proposed, namely direct links plus opportunistic channel state information (CSI)-based selection (DOS) scheme and direct links plus partial CSI-based selection (DPS) scheme. Considering three relaying strategies, i.e., decode-and-forward (DF), variable-gain amplify-and-forward (VG-AF), and fixed-gain amplify-and-forward (FG-AF), the performance analysis in terms of outage probability (OP) is carried out for each selection scheme. For the DF and VG-AF strategies, exact analytical expressions and tight closed-form approximate expressions for the OP are derived. For the FG-AF strategy, an exact closed-form expression for the OP is provided. Additionally, we propose a gradient-based search method to find the optimal values of the power-splitting ratio that minimizes the attained OPs. The developed analysis is corroborated through Monte Carlo simulation. Comparisons with the optimal joint selection scheme are performed and it is shown that the proposed schemes significantly reduce the amount of channel estimations while achieving comparable outage performance. In addition, regardless of relaying strategy used, numerical results show that the DOS scheme achieves full diversity gain, i.e., $M+K$ , and the DPS scheme achieves the diversity gain of $M+1$ , where $M$ and $K$ are the numbers of destinations and relays, respectively.