The EPC GEN 2 communication protocol for Ultra-high frequency Radio Frequency Identification (RFID) has offered a promising avenue for advancing the intelligence of transportation infrastructure. With the capability of linking vehicles to RFID readers to crowdsource information from RFID tags on road infrastructures, the RF-enhanced road infrastructure (REI) can potentially transform data acquisition for urban transportation. Despite its potential, the broader adoption of RFID technologies in building intelligent roads has been limited by a deficiency in understanding how the GEN 2 protocol impacts system performance under different transportation settings. This paper fills this knowledge gap by presenting the system architecture and detailing the design challenges associated with REI. Comprehensive real-world experiments are conducted to assess REI's effectiveness across various urban contexts. The results yield crucial insights into the optimal design of on-vehicle RFID readers and on-road RFID tags, considering the constraints imposed by vehicle dynamics, road geometries, and tag placements. With the optimized designs of encoding schemes for reader-tag communication and on-vehicle antennas, REI is able to fulfill the requirements of traffic sign inventory management and environmental monitoring while falling short of catering to the demand for high-speed navigation. In particular, the Miller 2 encoding scheme strikes the best balance between reading performance (e.g., throughput) and noise tolerance for the multipath effect. Additionally, we show that the on-vehicle antenna should be oriented to maximize the available time for reading on-road tags, although it may reduce the received power by the tags in the forward link.

翻译：EPC GEN 2通信协议用于超高频射频识别（RFID）技术，为提升交通基础设施的智能化水平提供了有前景的途径。通过将车辆与RFID读写器相连，以众包方式采集道路基础设施上RFID标签的信息，RF增强型道路基础设施（REI）有望改变城市交通的数据采集方式。然而，尽管具有巨大潜力，RFID技术在构建智能道路中的广泛应用仍受到限制，原因在于对GEN 2协议在不同交通环境下如何影响系统性能缺乏深入理解。本文通过阐述REI的系统架构并详述其设计挑战，填补了这一知识空白。我们开展了全面的实地实验，评估REI在多种城市环境下的有效性。实验结果揭示了车载RFID读写器与道路RFID标签的优化设计关键见解，需考虑车辆动力学、道路几何形状以及标签布局等因素带来的约束。通过优化读写器-标签通信的编码方案及车载天线设计，REI能够满足交通标志库存管理和环境监测的需求，但尚不足以支持高速导航应用。具体而言，Miller 2编码方案在读取性能（如吞吐量）与多径效应噪声容限之间实现了最佳平衡。此外，我们指出车载天线的朝向应最大化读取道路标签的可用时间，尽管这可能会降低前向链路中标签接收的功率。