Optimum Performance Boundaries of OSTBC Based AF-MIMO Relay System With Energy Harvesting Receiver
Optimum Performance Boundaries of OSTBC Based AF-MIMO Relay System With Energy Harvesting Receiver
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DOI：
10.1109/tsp.2013.2265224
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发表时间：
2013-09
影响因子：
5.4
通讯作者：
B. K. Chalise;Wing-Kin Ma;Yimin D. Zhang;H. Suraweera;M. Amin
中科院分区：
文献类型：
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作者：
B. K. Chalise;Wing-Kin Ma;Yimin D. Zhang;H. Suraweera;M. Amin
本文研究了具有多天线能量收集（EH）接收机的两跳多天线放大转发（AF）中继系统的最优性能边界。源节点和中继节点采用正交空时分组码进行数据传输。当瞬时信道状态信息（CSI）可用时，我们设计联合最优的源端和中继端预编码器，以实现能量和信息传输之间的不同权衡，这些权衡由速率 - 能量（R - E）区域的边界来表征。为此，将优化问题表述为一个松弛的凸问题，并且通过证明总能获得秩 - 1最优预编码器来确认其最优性。结果表明，像阿拉莫蒂码这样的全速率正交空时分组码（OSTBC）可用于发射节点（源节点和中继节点）的任意数量的天线，并支持多达七个同时存在的EH接收机。当只有CSI的二阶统计量可用时，中断概率（OP）和能量之间的权衡由中断概率 - 能量（OP - E）区域的边界来表征。在这种情况下，由于精确的OP表达式难以进行易于处理的优化，预编码器设计问题是使用对OP的凸上界近似来表述的。数值结果表明，通过OP上界获得的OP - E区域优于基于长期平均信噪比（SNR）最大化的方法所得到的区域。通过仿真展示了不同参数（如平均SNR、天线数量和空间相关性）对R - E和OP - E区域边界的作用。
This paper studies the optimum performance boundaries of a two-hop multi-antenna amplify-and-forward (AF) relay system with a multi-antenna energy harvesting (EH) receiver. The source and relay nodes employ orthogonal space-time block codes for data transmission. When instantaneous channel state information (CSI) is available, we design joint optimal source and relay precoders to achieve different tradeoffs between the energy and information transfers, which are characterized by the boundary of the rate-energy (R-E) region. For this purpose, the optimization problem is formulated as a relaxed convex problem but its optimality is confirmed with a proof that rank-one optimal precoders can always be obtained. As a consequence, it is shown that the full-rate OSTBC, like the Alamouti code, can be employed for an arbitrary number of antennas at the transmit nodes (source and relay) and support up to seven simultaneously existing EH receivers. When only second order statistics of the CSI is available, the tradeoff between outage probability (OP) and energy is characterized by the boundary of the OP-energy (OP-E) region. In this case, the precoder design problem is formulated using a convex upper bound approximation to the OP, since the exact OP expression is difficult for tractable optimization. Numerical results show that the OP-E region obtained with the upper bound of the OP is better than that with the approach based on maximization of the long-term average signal-to-noise ratio (SNR). The role of the different parameters such as average SNR, numbers of antennas, and spatial correlation on the boundaries of the R-E and OP-E regions is demonstrated via simulations.