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Trains Run Almost Anywhere with GSM-R

9/04/2013 9:21:00 AM

Background

Carrying an average of 4.9 million passengers every weekday, the MTR is regarded as one of the world's leading railways for safety, reliability, customer service, and cost-efficiency. To perfect China's high-speed railway link network and enhance communication between Hong Kong and the Chinese mainland, Guangzhou-Shenzhen-Hong Kong XRL is a strategic railway project that must align with the Chinese Train Control System Level-3 (CTCS L3) (equal to European Train Control System Level-2 (ETCS L2) standards). This XRL consists of two sections: the Guangzhou-Shenzhen and Hong Kong sections. The 102 km Guangzhou-Shenzhen section opened on December 26, 2011. Trains on the Guangzhou-Shenzhen section will run at speeds as high as 350 km/h. The entire Guangzhou – Shenzhen – Hong Kong XRL is scheduled to open in 2015. Now, this XRL is the Pearl River Delta cross-boundary transport infrastructure.

Challenges

Trains will run on the Hong Kong section at high speeds and must do so in a complex geographic environment. In view of the requirements, Guangzhou Railway and MTR were concerned about ensuring railway security, reliability, and efficiency. For the communications system, Guangzhou Railway and MTR were facing the following challenges:

  • Tunnels: The Shiziyang Tunnel was the most important tunnel in the Guangzhou-Shenzhen section. This tunnel crosses the Pearl River estuary with a length of 10.8 kilometers. It is designed for speeds up to 350 km/h – the fastest underwater tunnel in the world
  • Shared Operations: Two railway operators manage the Guangzhou-Shenzhen and Hong Kong sections – Guangzhou Railway and MTR. This raised the challenge of how Guangzhou Railway and MTR would cooperate in constructing and operating a cross-border XRL in a secure, fast, and efficient manner
  • Interoperability: The Base Station System (BSS) layer in the Hong Kong section must interconnect with the Network SubSystem (NSS) layer in the Guangzhou-Shenzhen section. Signaling of the two sections was provided by different vendors, which increased requirements on device interoperability and interface openness
  • Coverage and interference: Multiple interference factors exist along the railway, including radio signals from UMTS 900M cellular systems, which increased difficulties of signal coverage and network planning

Solution

The Guangzhou-Shenzhen section runs on a bridge across the Pearl River while the Hong Kong section connects Shenzhen and Hong Kong through tunnels. Both sections carry high-speed rail traffic and run through complex geographic environments, and demand wireless dispatch systems with 99.999% reliability along the entire network. Huawei offered a solution tailored to the customers' high network security and reliability requirements. Huawei's solution has the following key features:

  • System-level redundancy: Because of multi-underwater tunnels, especially Shiziyang Tunnel, both sections required class-leading signal coverage. After field surveys and precise network planning, Huawei offers a solution that uses system-level redundancy backup to improve the security and reliability of the communications system
  • Joint operation of Guangzhou Railway and MTR: The Guangzhou-Shenzhen and Hong Kong sections are operated by two railway operators. However, the core networking equipment of the Guangzhou-Shenzhen-Hong Kong XRL was designed to reside in Guangzhou. To both connect and isolate the networks of the Guangzhou-Shenzhen and Hong Kong sections, Huawei deployed one Base Station Controller (BSC) for the Guangzhou-Shenzhen section and another for the Hong Kong section. The two BSCs helped the cross-border BTSs better manage edge network planning and reduce interference. Additionally, in Huawei's solution the MTR's BBS layer connects to the Operations Support System (OSS) in Guangzhou Railway, while MTR's Fiber Access System (FAS) directly connects to the FAS in Guangzhou Railway. Therefore, Guangzhou Railway and MTR can collaborate with each other efficiently, achieving synchronous dispatching and operation
  • Field-proven device interoperability: Railway communications is founded on collaboration among multiple communications units. The GSM-R solution must ensure interoperability with all third-party devices, including railway signaling system. The communications part of this project also involved a large number of third-party devices, such as third-party dispatch systems and handheld devices. Huawei GSM-R devices had solved these challenges well
  • Coverage and interference: A railway communications system must be immune to interference. Huawei's solution uses guard space at the edge of the band and leaves a 2.7-MHz space between the center frequencies of UTMS and GSM-R networks. Huawei's solution reduces interferences from sites located away from railway tracks by decreasing their UMTS900M transmit power

Benefits

The Guangzhou – Shenzhen – Hong Kong XRL project connects Pearl River Delta (PRD) 1-hour, and Beijing 10-hour economic and living circles, and reaches 16 cities of China's mainland. This project will promote Hong Kong up to HK$87 billion in economic development over the next 50 years and further consolidate Hong Kong's position as a regional center.

Additionally, this project brings new railway operation and technology innovation values to MTR and upgrades the reliability of wireless communications.:

  • Railway operation: Huawei's comprehensive end-to-end wireless solution lays a solid groundwork for MTR's secure, efficient, and green railway operation
  • Technology innovation: This project breaks through conventional system-level communications redundancy and signal coverage technologies, enhances the modernization of the railway communications equipment, and paves the way for standard railway communications in both Hong Kong and China's mainland