TV white spaces for railway wireless applications

Samra, Mohamed (2020). TV white spaces for railway wireless applications. University of Birmingham. Ph.D.

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Abstract

Train-to-ground communication is one of the most crucial features of modern railway systems. The extensive use of emerging wireless technologies helps to achieve the rail industry vision of implementing intelligent trains, having a customised experience for travelling passengers, and running trains closer together. The Global System for Mobile Communications-Railway (GSM-R) is an international wireless communications standard introduced for train-to-ground communications in mainline railways. However, GSM-R currently suffers from severe interference and capacity problems that impede the consideration of this technology for emerging rail applications.

The prospect of opportunistic access to an inefficiently utilised frequency spectrum, known as TV White Spaces (TVWS), that exploits desirable railway propagation characteristics is proposed to solve the spectrum scarcity problem. In order to provide full protection for spectrum Primary Users (PUs), The IEEE 802.22 standard sets strict policies for mobile platforms. This research proposes a handover procedure and channel access scheme that maintain seamless connectivity for various railway wireless applications in the mobility-restrictive TVWS. The suitability of the approach is tested through its application in Remote Condition Monitoring (RCM) systems whose telecommunication requirements can tolerate the uncertainty in the TVWS spectrum availability. The method is applicable to other rail applications if special considerations are given to the specific application requirements.

Prior knowledge of the train’s trajectory enables the method to pre-select a list channels that last for long distances, which minimises unnecessary control messages overhead. The newly proposed method indicates an improvement of 37.8% in the channel utilisation distance, as the train can have an uninterrupted connection for an average consecutive distance of 1.188 km using the new scheme compared with an average of 0.862 km for the IEEE 802.22 standard. Besides that, for the same data rate, an extra 6.5% of maintenance data can be transmitted using the new approach if compared with the IEEE 802.22 standard under various spectrum availability. The results also reflect 0% probability of channel collision under all spectrum availability, due to the first-come-first-served spectrum access adopted, and 0% probability of overall network blocking at spectrum availability that is (≥ 30%). Finally, the new method does not cause any interference to the surrounding PUs and enables better transmission power for the spectrum Secondary Users (SUs) that can reach up to 42.2 dBm under different channel availability, which directly improves the overall network throughput.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):