In this letter, we investigate the use of reconfigurable intelligent surfaces (RISs) to jointly estimate the position and channel of a user equipment (UE) using uplink pilot signals. We consider a setup with a user and a base station (BS), where the direct path between the BS and the UE is blocked and virtual line-of-sight (LOS) links are created over two reconfigurable intelligent surfaces (RISs). We investigate the benefits of exploiting the channel geometry to estimate the user’s position and the user-RIS channels jointly in terms of estimation performance and pilot overhead. To this end, we consider the Cramér-Rao Lower Bound for channel estimation and UE localization. Our numerical results show that exploiting the LOS structure of the channels improves the channel estimation performance by several orders of magnitude and reduces the channel estimation performance by reducing the number of unknown parameters.

中文翻译：

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RIS 辅助通信系统中基于联合飞行员的定位和信道估计


在本文中，我们研究了使用可重构智能表面 （RIS） 来使用上行链路导频信号联合估计用户设备 （UE） 的位置和信道。我们考虑一个用户和一个基站 （BS） 的设置，其中 BS 和 UE 之间的直接路径被阻塞，并在两个可重构智能表面 （RIS） 上创建虚拟视距 （LOS） 链路。我们研究了利用通道几何结构来估计用户位置和用户 RIS 通道在估计性能和导频开销方面联合估计的好处。为此，我们考虑了用于信道估计和 UE 定位的 Cramér-Rao 下界。我们的数值结果表明，利用信道的LOS结构，可以提高信道估计性能几个数量级，而减少未知参数的数量，从而降低信道估计性能。