Date of this Version
2020 is the target year for the roll out of fifth generation wireless communication methodologies. The commercial vendors have characterized 5G as a collection of disruptive set of technologies to provide high throughput, low latency communication supporting a variety of services, i.e., machine to machine communication to next generation base stations and vehicle-to-vehicle communication to radio-over-fiber and high mobility channels. High-speed train wireless communication channels as a subset of high mobility channels have their clear advantages and disadvantages considering other vehicular channels. The speed of high-speed trains is going to reach 500km/hr and with Hyperloop it may reach 1000km/hr. LTE for railways (have) has been specified to support train to ground communication channels only up to 350km/hr and is still not future proof considering the bandwidth intensive passenger services. The next generation passenger services include conference calls, Ultra-HD video streaming, video streaming and downloads, resource intensive multimedia services for passengers comprising of gaming, personalized advertising, virtual and augmented reality, etc. Therefore, high-speed trains being next generation transportation system, the services provided to passengers on-board may suffer compared to the ground. The difference in provided services may sound significant compared to in-flight infotainment services based on satellite communication and on-board Wi-Fi.
In our approach, we have investigated the 5G physical deployment scenario without disrupting or interfering with prioritized train control communication channels. The novelty of separating train control and passenger services can be observed with mapping of different planes in 5G/LTE evolution specification. The separation provides an opportunity to not to compromise passenger services, maintaining quality of service in resource sensitive bandwidth. In our study, we found out that with more number of physical small cell deployment, capacity and area spectral efficiency are biased in front of base stations. In most of the conventional architectures the reliability and bandwidth efficiency of the architecture degrade beyond according to Gaussian distribution, which is directly related to propagation distance. In our proposed architecture, we showed that with a deployment scheme of on-roof multi train antennas, physical size of small cells can be reduced further and adaptably extended based on antenna distances. The on-roof antennas connected through fiber can access small cells in First In First Out manner without any additional signaling overhead or forwarding. The scope of this adaptability reduces outage probability comparable to macro cells and achieves flexible power consumption with high area spectral efficiency. The proposed architecture can attain a 10-15-fold improvement in spectral efficiency and 95% improvement in reliability than conventional architectures.
Advisor: Hamid R. Sharif-Kashani