Performance of Mobile Relays in Loaded Conditions for Railway Transportation

Abstract

Deploying mobile relays in public transportation is a simple yet effective way to avoid the electromagnetic insulation within vehicles and to increase the Quality of Service (QoS) perceived by passengers, which is sometimes low. Mobile relaying can be done by using an LTE/EPC 100%-compatible architecture. However, this solution induces extra-overhead. In this paper we evaluate the QoS of an LTE mobile relay architecture for public railway transport systems for two representative services: client-server requests and voice communications. We compare the performance of a direct transmission against a mobile relay architecture for different types of requests and different load conditions. This work, therefore, evaluates the mobile relay performance in terms of load time, throughput, packet loss ratio and end-to-end latency. Our findings show that a mobile relay architecture highly improves the QoS performance for train passengers. Furthermore, the gain is greater as the load increases.

A Comprehensive Survey on Moving Networks

“…As a relay, a mobile cell can carry information from the macro-cell base station to the in-vehicle users with a dual hop, circumventing the VPL. The existing researches have demonstrated significant increase in QoS for users inside the "mobile relays", despite the addition of a single hop [51], [55], [56]. From the standardization standpoint, 3GPP ratified specifications for moving relays in Release-12 [57].…”

“…In [56], The authors analyzed QoS enhancement for commuting users using mobile relays in the railways. The authors compared in-vehicle communication when users were served with mobile relays versus when they were directly connected to a nearby fixed base station.…”

Mobile relays for urban rail transportation systems

“…By performing real radio transmissions with a testbed in [22] we proved that a mobile relay architecture can be easily implemented with standard Evolved Packet Core (EPC) and with full compatibility with 3GPP recommendations. We evaluated the performance of this relay architecture by means of simulation in loaded conditions in [21]. In addition to a Voice over Internet Protocol (VoIP) service, we considered a simple client-server protocol.…”

“…Though we consider the whole network, we focus on the backhaul link. In addition to our previous work [21,22], we study the signaling load on the backhaul, we consider a Web service instead of a simple client-server exchange and we integrate handover.…”