Assuring an uninterrupted high Quality of Service (QoS) of railway communications between on-board terminals and base stations creates challenges for the provider. This is partly explained by the inherent mobility and the high penetration loss of carriages. Deploying mobile relays in public transportation is possible with a 100%-compatible LTE/EPC architecture. This effectively ensures that the electromagnetic insulation is kept to a minimum as QoS on board can be dramatically affected and worsened within the railway vehicles. Yet all users’ traffic congregates via the radio backhaul link and needs to take into consideration the extra packet-overhead and signaling messages that as a general rule get transmitted via the fixed links. The paper’s aim is to analyze the performance of mobile relays in loaded conditions comparing this to the standard direct mode. We propose an analytical model to compute the signaling rate. We parametrize it with experiments done on a testbed with real radio transmissions and show that signaling has no major impact on performance. We then evaluate the QoS experienced by passengers by means of simulations for two representative services: Web browsing and voice communications. The packet loss ratio for voice communications is reduced at the expense of a slight end-to-end latency increase thanks to mobile relays. During the high load conditions there is a significant reduction in the load time of a Web page and the throughput is increased.

确保车载终端与基站之间铁路通信的不间断高服务质量（QoS）给提供商带来了挑战。这部分是由于车架固有的移动性和高穿透损失造成的。通过100％兼容的LTE / EPC体系结构，可以在公共交通中部署移动中继。这可以有效地确保将电磁绝缘保持在最低水平，因为铁路车辆内的QoS可能会受到极大影响并恶化。然而，所有用户的流量都通过无线电回程链路聚合，并且需要考虑通常通过固定链路传输的额外的包开销和信令消息。本文的目的是分析移动继电器在负载条件下的性能，并将其与标准直接模式进行比较。我们提出了一种分析模型来计算信号速率。我们通过在具有真实无线电传输的测试台上进行的实验对它进行参数化，结果表明信令对性能没有重大影响。然后，我们通过模拟两种有代表性的服务来评估乘客体验到的QoS：Web浏览和语音通信。借助移动中继，降低了语音通信的丢包率，但端到端的等待时间却略有增加。在高负载条件下，网页的加载时间显着减少，吞吐量增加。我们通过在具有真实无线电传输的测试台上进行的实验对它进行参数化，结果表明信令对性能没有重大影响。然后，我们通过模拟两种有代表性的服务来评估乘客体验到的QoS：Web浏览和语音通信。借助移动中继，降低了语音通信的丢包率，但端到端等待时间略有增加。在高负载条件下，网页的加载时间显着减少，吞吐量增加。我们通过在具有真实无线电传输的测试台上进行的实验对它进行参数化，结果表明信令对性能没有重大影响。然后，我们通过模拟两种有代表性的服务来评估乘客体验到的QoS：Web浏览和语音通信。借助移动中继，降低了语音通信的丢包率，但端到端的等待时间却略有增加。在高负载条件下，网页的加载时间显着减少，吞吐量增加。借助移动中继，降低了语音通信的丢包率，但端到端等待时间略有增加。在高负载条件下，网页的加载时间显着减少，吞吐量增加。借助移动中继，降低了语音通信的丢包率，但端到端等待时间略有增加。在高负载条件下，网页的加载时间显着减少，吞吐量增加。