arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2008.00619eess.SP
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基于物理的可重构智能表面辅助多用户通信系统信道模型

A Novel Physics-based Channel Model for Reconfigurable Intelligent Surface-assisted Multi-user Communication Systems

Jiaqi Xu, Yuanwei Liu

摘要:

可重构智能表面(RIS)是下一代智能无线电环境的重要技术之一。提出了一种新的基于物理的RIS信道模型。特别地,我们通过研究信号的多径传播以及RIS的辐射方向图,将RIS和散射环境作为一个整体来考虑。该模型表明,RIS辅助的无线信道可以近似为Rician分布。解析表达式推导出的形状因子和比例因子的分布。对于连续相移的情况,分布取决于RIS的元件的数量和接收器的观测方向。对于连续相移的情况,分布还取决于RIS相位误差的量化水平。由分布的比例因子得到平均接收功率的比例律。对于RIS作为异常反射器的应用场景,我们研究了单RIS辅助的多址接入网络在时分多址接入(TDMA)、频分多址接入(FDMA)和非正交多址接入(NOMA)下的性能。封闭形式的表达式所提出的信道模型的中断概率。证明了存在一个与RIS元素个数无关的常数分集阶。仿真结果证实了该模型有效地适用于相控阵实现的RISs。

英文摘要:

The reconfigurable intelligent surface (RIS) is one of the promising technologies contributing to the next generation smart radio environment. A novel physics-based RIS channel model is proposed. Particularly, we consider the RIS and the scattering environment as a whole by studying the signal's multipath propagation, as well as the radiation pattern of the RIS. The model suggests that the RIS-assisted wireless channel can be approximated by a Rician distribution. Analytical expressions are derived for the shape factor and the scale factor of the distribution. For the case of continuous phase shifts, the distribution depends on the number of elements of the RIS and the observing direction of the receiver. For the case of continuous phase shifts, the distribution further depends on the quantization level of the RIS phase error. The scaling law of the average received power is obtained from the scale factor of the distribution. For the application scenarios where RIS functions as an anomalous reflector, we investigate the performance of single RIS-assisted multiple access networks for time-division multiple access (TDMA), frequency-division multiple access (FDMA) and non-orthogonal multiple access (NOMA). Closed-form expressions for the outage probability of the proposed channel model are derived. It is proved that a constant diversity order exists, which is independent of the number of RIS elements. Simulation results are presented to confirm that the proposed model applies effectively to the phased-array implemented RISs.

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