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arXiv 2007.05873eess.SPcs.SYeess.SY
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可重构智能表面辅助mmWave NOMA:联合功率分配、相移和混合波束形成优化

Reconfigurable Intelligent Surfaces Aided mmWave NOMA: Joint Power Allocation,Phase Shifts, and Hybrid Beamforming Optimization

Yue Xiu, Jun Zhao, Wei Sun, Marco Di Renzo, Guan Gui, Zhongpei Zhang, Ning Wei

摘要:

研究了一种可重构智能表面(RIS)辅助的毫米波(mmWave)非正交多址接入(NOMA)系统。特别地,我们考虑具有混合波束成形结构的RIS辅助mmWave-NOMA下行链路系统。为了在最小速率约束和最小发射功率约束下最大化可实现的和速率,提出了一个RIS相移、混合波束赋形和功率分配的联合问题。为了解决这个非凸优化问题,我们开发了一个交替优化算法。具体地,首先,非凸问题被转化为三个子问题,即,功率分配、联合相移和模拟波束成形优化以及数字波束成形设计。然后,我们解决了固定相位偏移的RIS和混合波束形成的功率分配问题。最后,在给定功率分配矩阵的情况下,分别采用基于交替流形优化(AMO)的方法和基于逐次凸逼近(SCA)的方法设计相移、模拟波束形成和发射波束形成。数值结果表明,所提出的交替优化算法优于国家的最先进的计划在和率。此外,与没有RIS的传统mmWave-NOMA系统相比,所提出的RIS辅助mmWave-NOMA系统能够提高系统的可实现的和速率。

英文摘要:

In this paper, an reconfigurable intelligent surface (RIS)-aided millimeter wave (mmWave) non-orthogonal multiple access (NOMA) system is considered. In particular, we consider an RIS-aided mmWave-NOMA downlink system with a hybrid beamforming structure. To maximize the achievable sum-rate under a minimum rate constraint for the users and a minimum transmit power constraint, a joint RIS phase shifts, hybrid beamforming, and power allocation problem is formulated. To solve this non-convex optimization problem, we develop an alternating optimization algorithm. Specifically, first, the non-convex problem is transformed into three subproblems, i.e., power allocation, joint phase shifts and analog beamforming optimization, and digital beamforming design. Then, we solve the power allocation problem under fixed phase shifts of the RIS and hybrid beamforming. Finally, given the power allocation matrix, an alternating manifold optimization (AMO)-based method and a successive convex approximation (SCA)-based method are utilized to design the phase shifts, analog beamforming, and transmit beamforming, respectively. Numerical results reveal that the proposed alternating optimization algorithm outperforms state-of-the-art schemes in terms of sum-rate. Moreover, compared to a conventional mmWave-NOMA system without RIS, the proposed RIS-aided mmWave-NOMA system is capable of improving the achievable sum-rate of the system.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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