The focus of this paper is to demonstrate an over-the-air (OTA) 5G new radio (NR) sidelink communication prototype. 5G NR sidelink communications allow NR UEs to transfer data independently without the assistance of a base station (gNB), which enables V2X communications, including platooning, autonomous driving, sensor extension, industrial IoT, public safety communication and much more. Our design leverages the open-source OpenAirInterface5G (OAI) software, which operates on software-defined radios (SDRs) and can be easily extended for mesh networking. The software includes all signal processing components specified by the 3GPP 5G sidelink standards, including Low-Density Parity Check (LDPC) encoding/decoding, polar encoding/decoding, data and control multiplexing, modulation/demodulation, and orthogonal frequency-division multiplexing (OFDM) modulation/demodulation. It can be configured to operate with different bands, bandwidths, and antenna settings. The first milestone in this work was to demonstrate the completed Physical Sidelink Broadcast Channel (PSBCH) development, which conducts synchronization between a Synchronization Reference (SyncRef) UE and a nearby UE. The SyncRef UE broadcasts a sidelink synchronization signal block (S-SSB) periodically, which the nearby UE detects and uses to synchronize its timing and frequency components with the SyncRef UE. Once a connection is established, the next developmental milestone is to transmit real data (text messages) via the Physical Sidelink Shared Channel (PSSCH). Our PHY sidelink framework is tested using both an RF simulator and an OTA testbed with multiple nearby UEs. Beyond the development of synchronization and data transmission/reception in 5G sidelink, we conclude with various performance tests and validation experiments. The results of these metrics show that our simulator is comparable to the OTA testbed.

翻译：本文旨在演示一种基于空口（OTA）的5G新空口（NR）侧链通信原型系统。5G NR侧链通信允许NR用户设备（UE）在无需基站（gNB）辅助的情况下独立传输数据，从而支持车联网（V2X）通信，包括队列行驶、自动驾驶、传感器扩展、工业物联网、公共安全通信等多种应用场景。我们的设计基于开源软件OpenAirInterface5G (OAI)，该软件运行于软件定义无线电（SDR）平台上，并易于扩展至网状网络。该软件包含3GPP 5G侧链标准规定的所有信号处理模块，包括低密度奇偶校验（LDPC）编码/解码、极化编码/解码、数据与控制复用、调制/解调以及正交频分复用（OFDM）调制/解调。系统可配置为在不同频段、带宽和天线设置下运行。本工作的首个里程碑是完成物理侧链广播信道（PSBCH）的开发，该信道实现同步参考（SyncRef）UE与邻近UE之间的同步。SyncRef UE周期性地广播侧链同步信号块（S-SSB），邻近UE检测该信号并据此同步其时序和频率分量与SyncRef UE。一旦建立连接，下一个开发里程碑是通过物理侧链共享信道（PSSCH）传输真实数据（文本消息）。我们的物理层侧链框架已通过射频模拟器及包含多个邻近UE的空口测试平台进行验证。除5G侧链同步与数据收发功能的开发外，我们还进行了多项性能测试与验证实验。结果表明，模拟器性能与空口测试平台具有可比性。