Broadband on Trains: Improving Passenger Experience and Expanding Business Opportunities
| By Huang Liang, Transportation Industry Marketing Manager, Huawei Enterprise Business Group
On-board Broadband Improves Passenger Connectivity Experience
Compared to travel by land or air, rail offers many benefits: greater comfort, freedom to move around, larger capacity, and less environmental impact. In addition to these advantages, business people prefer trains that offer Internet access so they can work as they travel. Smart device users want to be able to make full use of their technology.
Traditional narrowband communication technologies, such as GSM for Railways (GSM-R), provide minimal communications for train scheduling and control signaling. Unfortunately, wireless networks deployed by telecom carriers along railways are only able to provide limited Internet access for passengers. As trains run faster and railways extend further, Internet access and phone calls become increasingly unstable for three reasons: First, radio signals attenuate as they pass through train body. Second, network signals are blocked when trains travel over bridges, through tunnels, or across extreme environments. Third, large numbers of concurrent service requests reduce access availability.
Evolving Train-Ground Broadband Technologies
Providing broadband access on trains improves the passengers' connectivity experience and presents significant business opportunities. Europe, the U.S., and many other countries have experimented with technologies such as satellite, GSM, 3G, WiMAX, Wi-Fi, and LTE. However, most solutions proved costly, ineffective, or constrained by other factors.
• Satellite communications system: In 2004, the Fast Internet for Fast Train Hosts (FIFTH) project team of the Italian train operator Trenitalia used a Ku-band satellite to enable wireless communications between passenger trains and ground sites. The satellite communications system provided a downlink bandwidth of 1.5 Mbit/s and an uplink bandwidth of 0.5 Mbit/s. However, the satellite solution is restricted by high costs, limited uplink bandwidth, high latency, and poor blind spot and tunnel coverage from satellite signal blockage; therefore it has not been widely adopted.
• GSM network + satellite: In 2003, Icomera AB of Sweden developed the Icomera Mobile System (IMS) that used a satellite for downlink transmission and GSM/GPRS for uplink transmission. The IMS provided a download speed of 560 Kbit/s at peak, with 44 Kbit/s on average. It was only sufficient for receiving and sending emails and browsing basic Web pages.
• Public 3G + WiMAX: In 2007, T-Mobile helped the UK Southern Railway deploy a WiMAX-based Nomad Digital Rail (NDR) system on trains between London and Brighton. The NDR system supports large file transfers and entertainment services. It offers a 2 Mbit/s uplink and downlink bandwidth between the two cities, including tunnels up to six kilometers long. However, because WiMAX is evolving quickly and the NDR system depends heavily on a specific chip vendor, the NDR system is unlikely to be used on a large scale.
• Wi-Fi: Wi-Fi is widely used in train-ground communications in urban rail transit, and its available bandwidth can reach 10 Mbit/s without interference. However, the Shenzhen Metro incident in November 2012 when a train stopped due to Wi-Fi interference from passenger mobile phones raised security concerns about broadcasting train control signals on license-free 2.4 GHz ISM bands. Broadband Wi-Fi on trains requires a large number of Access Points (APs) and optical fibers alongside railways, resulting in heavy maintenance workloads. Furthermore, the limited availability of 2.4 GHz channels makes providing high-quality Wi-Fi access extremely difficult. Therefore, Wi-Fi is not suitable for long-distance lines.
• Private wireless protocols similar to Wi-Fi: Some systems using private wireless protocols similar to Wi-Fi can provide sufficient train-ground bandwidth, but they lack compatibility and are costly.
In 2010, Huawei tested FDD-LTE on 431-km/h Shanghai Maglev trains. The peak downlink and uplink rates reached 50 Mbit/s and 30 Mbit/s, respectively, raising new hope for reliable broadband on trains.
In 2012, China Mobile deployed Huawei TD-LTE networks for Hangzhou Metro Line 1, Shenzhen Metro Line 2, and partial coverage for Shenzhen Metro Line 4. In field tests, the peak bandwidth reached 50 Mbit/s and the average uplink and downlink rates reached 38 Mbit/s and 8.1 Mbit/s, respectively, with no lost connections. The success rate of cross-cell handover was 100 percent, and the minimum downlink rate exceeded 8 Mbit/s.
Providing Optimal On-board Mobile Broadband Experience
Broadband-enabled trains need to offer high train-ground bandwidth, connecting high-speed trains with ground networks and management centers securely and efficiently by advanced wireless communications technologies; providing onboard video surveillance systems to ensure public safety, passenger information systems to guide passengers effectively, and the other services like Wi-Fi access for customers. But to provide an optimal experience, train operators need to answer the following questions:
- How to handle massive, concurrent broadband access requests?
Use large-capacity, manageable networking devices. Aggregate wireless links on train-ground communication channels to access multiple terrestrial networks simultaneously and increase bandwidth. Refine network management to authenticate passengers accessing the network and block unauthorized users. Save bandwidth and reduce data center load by processing service and device management activity locally, using on-board servers.
- How to provide high-quality multimedia content and services?
Large-capacity servers on board store large-volume content (for example, video and music), provide cache for content, update content during idle time, and store surveillance videos locally. When trains reach their destinations, local management centers can retrieve and archive all trip data, including surveillance video.
- How best to modernize existing train communications networks quickly to provide new services?
Use dual-band APs to create WLAN bridges to connect all passenger cars into a single LAN. Network switching devices on trains can eliminate network capacity bottlenecks from multi-level bridging, and employ Access Controllers (ACs) to improve WLAN reliability.
Powerful communication technologies like LTE enable secure and efficient data transmission between high-speed trains, ground networks, and management centers. It is essential that customers partner with experienced manufacturers who are able to provide highly stable products designed and certified to meet Electro-Magnetic Compatibility (EMC) requirements. Network design, planning, and deployment rely on meeting the special operating environments found in railroad systems and fulfilling the massive traffic volumes needed to ensure passenger satisfaction and future business opportunities.