Detecting Dark Cars in Railroad Operations using Multi-Antenna Beamforming for Long-Distance Discovery and Identification of AEI Tags

One recurring problem that the North American railroad industry faces is the tracking of lost railroad cars. Railroad cars are often parked on track sidings of train stations or train depot, and forgotten or lost over time. This results in so-called Dark Cars. All railcars in North America are equipped with automatic equipment identification (AEI) tags, which is built upon radio-frequency identification (RFID) technology to uniquely identify each railcar. When queried, the tag provides a digital version of the railcar's reporting mark, among other information. RFID is an application of radio frequency backscatter communications between a reader and the tag. Passive RFID read distances are typically fairly limited, which has hindered an effective solution to detect dark cars on track sidings. In this study, we propose a framework to significantly extend the current AEI read distance in railroad industry. To accomplish this task, we propose a novel multi-antenna beamforming AEI tag reader powered by and mounted on locomotives. As a result of the proposed multi-antenna beamforming, the directionality and steerability of the emitted beam are increased. In other words, this implies additional increase in effective read distance while staying within the FCC-power budget, and satisfying the electromagnetic field strength needed to power up the AEI tag during a read operation. We conducted an in-depth model-driven performance evaluation of different multipath channel models affecting the link budget, including Rayleigh, Rician, and Two-Ray Ground. The receiver component of the AEI tag reader can benefit from the directionality and beam steering to effectively suppress undesirable directions through null placement and thus improve noise resiliency. The simulation results of our proposed approach show a significant increase in read distance (from 3-4 meters to 35 meters) in comparison to conventional AEI tag readers that utilize a single-antenna design.