Study of High-Speed Wireless Data Transmissions for Railroad Operation
Terry Tse · Research Results · 2007
With the widespread deployment of high performance wireless data network technologies (such as Institute of Electrical and Electronics Engineers (IEEE) 802.11a/b/g, 802.16e, etc.), it has become feasible to utilize these standard-based wireless technologies for applications desired by the railroad industry for improving operations effectiveness, monitoring and control, and safety. Before any of these wireless systems are employed, however, serious questions must be answered to assure that the railroad requirements of mobility, throughput, coverage range, Doppler effects, and response times are met. The University of Nebraska, under a grant from the Federal Railroad Administration (FRA), has been studying the feasibility of using 802.11a/b/g-based wireless networks for mobile railroad environments. A 3.5-mile test bed has been designed and implemented with a series of access points in the Burlington Northern Santa Fe Railroad (BNSF) Hastings Subdivision near Lincoln, NE, to support this study. The test bed has complemented the theoretical study supported with in-depth computer models and simulations to measure and analyze network throughput of 802.11a/b/g for trains under different velocities. Simulation results have been compared and verified with test bed measurements to analyze performance characteristics of 802.11-based networks for mobile trains. Results and analysis show that even though the system throughput of 802.11 standard decreases under high velocity, it can still support railroad applications if the coverage range is provided. Therefore, an 802.11-based wireless network can support real-time Internet accessibility for trains’ crew, passenger, and railway workers, improving railroad operating safety and efficiency.