Joint Downlink/Uplink Design for Wireless Powered Networks With Interference
Joint Downlink/Uplink Design for Wireless Powered Networks With Interference
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DOI：
10.1109/access.2017.2657801
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发表时间：
2017-01-01
期刊：
影响因子：
3.9
通讯作者：
Nallanathan, Arumugam
中科院分区：
文献类型：
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作者：
Diamantoulakis, Panagiotis D.;Pappi, Koralia N.;Nallanathan, Arumugam
本文联合研究了受级联近远问题影响的无线供电网络（wpn）的下行/上行链路，即由于不同的路径损耗值而导致的用户性能的不对称整体下降。更具体地说，假设用户能够从干扰信号和期望信号中获取能量，较高的路径损耗会降低远端用户的下行速率，同时也会对其上行速率产生负面影响，因为在下行期间可以获取的能量更少。此外，如果远端用户位于小区边缘，则其性能受到干扰的影响更严重，尽管从干扰信号中收集能量可能会获得增益。为此，我们利用相应的优先级权重，公平地最大化下行/上行用户的速率。下行链路采用时分多址和非正交多址（NOMA）两种通信协议，上行链路采用分时多址协议。将公式化的多维非凸优化问题转化为等价的凸优化问题，求解的复杂度较低。仿真结果表明：1)可以实现相对较高的下行速率，而上行所需的能量由用户同时收集；2)下行链路NOMA是相对于网络拓扑更合适的选择，特别是当需要较高的下行速率时。
This paper jointly investigates the downlink/uplink of wireless powered networks (WPNs), which are exposed to the effect of the cascaded near-far problem, i.e., the asymmetric overall degradation of the users' performance, due to different path-loss values. More specifically, assuming that the users are able to harvest energy both from interference and desired signals, higher path loss reduces the downlink rate of the far user, while it also negatively affects its uplink rate, since less energy can be harvested during downlink. Furthermore, if the far user is located at the cell edge, its performance is more severely impaired by interference, despite the potential gain due to energy harvesting from interference signals. To this end, we fairly maximize the downlink/uplink users' rates, by utilizing corresponding priority weights. Two communication protocols are taken into account for the downlink, namely, time division multiple access and non-orthogonal multiple access (NOMA), while NOMA with time sharing is considered for the uplink. The formulated multidimensional non-convex optimization problems are transformed into the equivalent convex ones and can be solved with low complexity. Simulations results illustrate that: 1) a relatively high downlink rate can be achieved, while the required energy is simultaneously harvested by the users for the uplink and 2) dowlink NOMA is a more appropriate option with respect to the network topology, especially when a high downlink rate is desired.