Recently, wireless powered cooperative cognitive radio networks (CRNs), which combine the technologies of radio frequency (RF) energy harvesting and CR, have drawn great attention. In such networks, energy cooperation between the cognitive users (CUs) and the wireless powered primary users (PUs) can be performed, where the CUs can charge the PUs wirelessly in exchange for the spectrum access. Specifically, energy cooperation and information transmission is executed in two phases, where the CUs transmit their data signals and the PUs harvest energy from these signals in the first phase, and the PUs transmit their data using the harvested energy in the second phase. In particular, we consider two multiple access schemes for the CUs, namely non-orthogonal multiple access (NOMA) and time-division multiple access (TDMA). For both NOMA and TDMA, the PU sum-rate maximization problems under the minimum CU sum-rate constraint are first simplified by exploring particular problem structure, then are transformed to convex problems, and finally are solved optimally. The PU sum-rates of the two schemes are compared theoretically as well as numerically. It is revealed that the circuit power consumption at the CUs, the required minimum CU sum-rate, and the PU energy harvesting sensitivity and saturation thresholds play key roles in the PU performance comparison of the two schemes.

中文翻译：

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协作 CRN 的无线供电主要用户的总速率最大化：认知用户的 NOMA 或 TDMA？


最近，结合了射频（RF）能量收集和CR技术的无线供电的协作认知无线电网络（CRN）引起了极大的关注。在这样的网络中，可以执行认知用户（CU）和无线供电的主用户（PU）之间的能量协作，其中CU可以对PU进行无线充电以换取频谱访问。具体地，能量协作和信息传输分两个阶段执行，其中CU发送其数据信号并且PU在第一阶段从这些信号中收获能量，并且PU在第二阶段使用收获的能量发送其数据。特别地，我们考虑CU的两种多址方案，即非正交多址(NOMA)和时分多址(TDMA)。对于NOMA和TDMA，首先通过探索特定的问题结构来简化最小CU和速率约束下的PU和速率最大化问题，然后将其转化为凸问题，最后进行优化求解。从理论上和数值上比较了两种方案的 PU 总速率。结果表明，CU 处的电路功耗、所需的最小 CU 总速率以及 PU 能量收集灵敏度和饱和阈值在两种方案的 PU 性能比较中起着关键作用。