Design and analysis of a novel architecture for 5G communications using mobile relays in LTE and mmWave bands for high speed trains

The great advancements in modern communications have permitted to connect people like never before. Nowadays, people are permanently connected. This tendency of ubiquitous connectivity has led users to demand new ways of access and faster and more efficient communication systems. Furthermore, vehicular communications currently lack of good data access for onboard passengers. Concretely in High Speed Trains, railway authorities wish to provide broadband communications to passengers. The aim of this Master Thesis is to study the performance of a novel architecture in High Speed Railways utilizing cutting-edge technologies. In railway scenarios, two types of communications can be considered: critical and noncritical. Critical communications are for signaling and control purposes, hence they handle traffic to provide a minimum Quality of Service (QoS). Critical communications have to ensure passenger safety and provide real-time multimedia information. Various standards have been proposed: GSM-Railway, TETRA or the next-generation network, LTE-R. On the contrary, noncritical communications are specific for information and entertainment for the train passengers. Currently, there are no dedicated standards for the latter type of service. Therefore, railway operators have to come up with their own solutions to provide Wi-Fi to most passengers. High Speed Railway (HSR) scenarios suffer from poor propagation conditions with high fastfading, high Doppler spread or high Vehicular Penetration Losses (VPL) between others. New architectures and technologies, like the Mobile Relay Node (MRN) or the utilization of millimeter wave (mmWave) bands, have been developed to counteract these adverse effects. Moreover, MIMO techniques permit to increase the link capacity by the number of spatial channels. Ultimately, the combination of all of these technologies will provide the capacity and latency needed for future communications in HSR scenarios. Standardization organizations, like ITU-R or 3GPP, have struggled to offer a good Quality of Experience (QoE) with gigabit data rates in mobile communications. This is a major problem for high speed environments where there are very poor propagation conditions. Therefore, it is going to be studied the feasibility of current and new architectures in HSR environments and how to bypass the problems associated with these scenarios. In addition to that, a two-hop relay architecture using the LTE-Advanced network and mmWave bands inside the train will be presented. Besides, the relay will be mounted on top of the train providing coverage to the train passengers and a MIMO channel will be established between the base station and the users. The proposed architecture the link feasibility is analyzed by means of a link-level simulator. Simulations will be carried out to study the improvement in performance and capacity of the architecture proposed as opposed to current deployments in high speed scenarios. Moreover, different topologies and situations will be introduced to be able to compare and evaluate its performance under different outlooks