In future wireless systems, a large number of users may access the networks via moving relays (MRs) installed on top of vehicles. One of the main challenges of MRs is rapid channel variation, which may make channel estimation and its following procedures difficult. To address these issues, various schemes are designed, among which the predictor antenna (PA) is a candidate. The PA setup refers to a system with two (sets of) antennas on top of a vehicle, where the PA(s) positioned in front of the vehicle is (are) utilized to predict the channel state information required for data transmission to the receive antennas aligned behind the PA. In this article, we introduce the concept and the potential of PA systems. Moreover, summarizing the field trials for PAs and the 3GPP attempts on (moving) relays, we compare the performance of different PA and non-PA methods for vehicle communications in both urban and rural areas with the PA setup backhauled through terrestrial or satellite technology, respectively. As we show, with typical parameter settings and vehicle speeds, a single-antenna PA-assisted setup can boost the backhaul throughput of MRs, compared to state-of-the-art open-loop schemes, by up to 50 percent.

中文翻译：

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预测天线：一种提高移动继电器性能的技术

在未来的无线系统中，大量用户可能会通过安装在车辆顶部的移动中继 (MR) 来访问网络。MR 的主要挑战之一是快速的信道变化，这可能会使信道估计及其后续过程变得困难。为了解决这些问题，设计了各种方案，其中预测器天线（PA）是候选方案。PA 设置是指在车辆顶部具有两个（组）天线的系统，其中位于车辆前方的 PA 用于预测数据传输到接收端所需的信道状态信息。天线在 PA 后面对齐。在本文中，我们将介绍 PA 系统的概念和潜力。此外，总结 PA 的现场试验和 3GPP 对（移动）中继的尝试，我们分别比较了不同 PA 和非 PA 方法在城市和农村地区与通过地面或卫星技术回程的 PA 设置进行车辆通信的性能。正如我们所展示的，通过典型的参数设置和车辆速度，与最先进的开环方案相比，单天线 PA 辅助设置可以将 MR 的回程吞吐量提高多达 50%。