In backscatter communication (BackCom), the direct link between the tag and the reader is susceptible to the deep shadowing due to the obstruction between them. In this paper, we consider cooperative transmission to relay the tag information. The harvest-then-transmit (HTT) protocol is adopted in the relay, where the relay harvests energy in the first time slot and forwards the tag signal after decoding and re-encoding it. Our objective is to maximize the capacity performance subject to the relay residual energy constraint, the tag circuit energy constraint and the total time constraint by optimizing the power splitting factor and time slots. The resulting optimization problem is shown to be convex, however should be numerically evaluated for optimality. In order to gain more insight and avoid high computational complexity, closed-form expressions are derived for sub-optimal solutions. Simulation results confirm the near-optimal performance of sub-optimal solutions, which are shown to perform much better than traditional schemes.

中文翻译：

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通过“收获-然后-传输”中继的反向散射通信

在反向散射通信 (BackCom) 中，标签和阅读器之间的直接链接由于它们之间的障碍而容易受到深阴影的影响。在本文中，我们考虑协作传输来中继标签信息。中继采用HTT协议，中继在第一个时隙收集能量，解码并重新编码后转发标签信号。我们的目标是通过优化功率分配因子和时隙来最大化受继电器剩余能量约束、标签电路能量约束和总时间约束的容量性能。由此产生的优化问题被证明是凸的，但是应该对最优性进行数值评估。为了获得更多的洞察力并避免高计算复杂度，封闭形式的表达式是为次优解导出的。仿真结果证实了次优解决方案的近乎最优性能，其性能比传统方案好得多。