Transmission rate and harvested energy are well-known conflictive optimization objectives in simultaneous wireless information and power transfer (SWIPT) systems, and thus their trade-off and joint optimization are important problems to be studied. In this paper, we investigate joint power allocation and splitting control in a SWIPT-enabled non-orthogonal multiple access (NOMA) system with the power splitting (PS) technique, with an aim to optimize the total transmission rate and harvested energy simultaneously whilst satisfying the minimum rate and the harvested energy requirements of each user. These two conflicting objectives make the formulated problem a constrained multi-objective optimization problem. Since the harvested power is usually stored in the battery and used to support the reverse link transmission, we transform the harvested energy into throughput and define a new objective function by summing the weighted values of the transmission rate achieved by information decoding and transformed throughput from energy harvesting, defined as equivalent-sum-rate (ESR). As a result, the original problem is transformed into a single-objective optimization problem. The considered ESR maximization problem which involves joint optimization of power allocation and PS ratio is nonconvex, and hence challenging to solve. In order to tackle it, we decouple the original nonconvex problem into two convex subproblems and solve them iteratively. In addition, both equal PS ratio case and independent PS ratio case are considered to further explore the performance. Numerical results validate the theoretical findings and demonstrate that significant performance gain over the traditional rate maximization scheme can be achieved by the proposed algorithms in a SWIPT-enabled NOMA system.

中文翻译：

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支持 SWIPT 的 NOMA 系统的联合功率分配和分流控制

传输速率和收集的能量是同步无线信息和功率传输 (SWIPT) 系统中众所周知的冲突优化目标，因此它们的权衡和联合优化是有待研究的重要问题。在本文中，我们使用功率分配 (PS) 技术研究了启用 SWIPT 的非正交多址 (NOMA) 系统中的联合功率分配和分配控制，旨在同时优化总传输速率和收集的能量，同时满足每个用户的最低速率和收集的能量要求。这两个相互冲突的目标使制定的问题成为受约束的多目标优化问题。由于收集到的电力通常存储在电池中并用于支持反向链路传输，我们将收集的能量转换为吞吐量，并通过将信息解码实现的传输速率的加权值与能量收集的转换吞吐量相加来定义新的目标函数，定义为等效总和速率 (ESR)。结果，原问题转化为单目标优化问题。所考虑的涉及功率分配和 PS 比联合优化的 ESR 最大化问题是非凸的，因此解决起来具有挑战性。为了解决这个问题，我们将原始非凸问题解耦为两个凸子问题并迭代求解。此外，还考虑了相等 PS 比率情况和独立 PS 比率情况，以进一步探索性能。