This paper studies optimal resource allocation in the wireless powered communication networks (WPCN) combined with time reversal (TR) in which one hybrid access point (H-AP) broadcasts constant wireless energy to a set of distributed users in the downlink (DL) and receives information from the users via space division multiple access (SDMA) in the uplink (UL). Inevitable interferences will occur when users transmit information in the UL simultaneously and the special space-time focusing of TR is used to suppress the interferences. An efficient protocol is proposed to support wireless energy transfer (WET) and TR in the DL and wireless information transmission in the UL for the proposed TR-WPCN. We optimize the time allocations to the H-AP for DL WET, DL TR, and UL WIT to maximize the sum throughput. Due to the nonconvexity of the studied optimization problem, we optimize variables successively, where the nonconvex optimization problem is transformed into the convex optimization problem. The approximate convex optimization problem can then be solved iteratively combined with the dichotomy method. Simulation results show that the proposed scheme can effectively suppress interferences and improve system performance.

中文翻译：

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时间反向无线通信网络中的时间分配和优化

本文研究了无线通信网络（WPCN）与时间反转（TR）相结合的最佳资源分配，其中一个混合接入点（H-AP）向下行链路（DL）中的一组分布式用户广播恒定的无线能量，通过上行链路（UL）中的空分多址（SDMA）从用户接收信息。当用户在UL中同时发送信息时，不可避免的干扰会发生，并且使用TR的特殊时空聚焦来抑制干扰。对于所提出的TR-WPCN，提出了一种有效的协议来支持DL中的无线能量传输（WET）和TR以及UL中的无线信息传输。我们为DL WET，DL TR和UL WIT优化了对H-AP的时间分配，以最大化总吞吐量。由于所研究的优化问题的非凸性，我们先对变量进行优化，将非凸优化问题转化为凸优化问题。然后可以与二分法迭代地解决近似凸优化问题。仿真结果表明，该方案可以有效抑制干扰，提高系统性能。