February 11, 2014

LTE displays potential in Zhengzhou

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Zhengzhou's metro is the first network in the world to utilise a 4G LTE communications platform. Kevin Smith travelled to China to witness the system in action.

ATTENDING a launch event for a new railway solution at a hotel rather than a station or at the trackside is not perhaps the most inspiring scenario, particularly following a long-haul flight just a few hours before.

But on this occasion in Zhengzhou, China, there was good reason for the neutral venue. After a set piece countdown had concluded and both Mr Zhang Jianhui, vice mayor of Zhengzhou, and Mr Patrick Zhang, president of marketing and solutions at Huawei Enterprises, ceremoniously pushed a mock switch forward to launch eLTE, Huawei's new fourth-generation (4G) Long-Term Evolution (LTE) platform, a live image of a female Zhengzhou metro staff member immediately appeared on a large screen in the backdrop.

Visible through crystal-clear high-definition (HD) video, she informed the audience via perfect audio that she was transmitting live from a train a few kilometres away which was operating during a test run on the city's new 26.3km metro Line 1, which opened to the public on December 26.

Zhengzhou is the first metro in the world to adopt LTE and the second Chinese railway to utilise Huawei's LTE solution following Shuo Huang Railway which is aiming to boost capacity on its coal network (IRJ August 2013 p24). Zhengzhou is initially using LTE to host onboard passenger information and CCTV services alongside separate systems for its ground-based IT networks, communication-based train control (CBTC) signalling and Tetra voice systems. However, tests will begin in 2014 to host the metro's CBTC signalling on LTE, and if they are successful, a complete switchover could take place by the end of the year.

Huawei is certainly confident that these tests will go well and was keen to show off what it has done in Zhengzhou to around 150 partners, existing and potential customers, as well as the domestic and international media. In particular representatives were enthusiastic to stress the system's capabilities compared with existing WiFi-based platforms, and Zhengzhou's willingness to be the first to adopt the new platform.

"The big data era is coming which will require mobile solutions that provide broadband based quality services," Zhang says. "We analysed the metro market and identified huge potential to move from narrow-broadband applications. In Zhengzhou they have a vision for the future and were not afraid to do something that others might believe is a risk, because they still have a plan B. They, like us, believe that LTE is the future of railway communications."

good-noseHuawei was awarded the contract in Zhengzhou at the end of 2010 with the brief to "provide increased convenience to passengers." The network consists of the core network which is connected to dispatchers and video processing, storage and distribution devices, which in turns feeds to an IP cloud network which connects with ground-based terminals at stations such as CCTV cameras, public address (PA) speakers, phones, and the LTE base stations. These base stations provide the LTE frequency and connect via an antenna with the onboard train access unit (TAU) to deliver broadband-quality data to onboard devices including passenger information screens, the PA system, and CCTV cameras.

While current WiFi systems used on metros are able to host video, Huawei says they are unable to deliver this high quality data which translates into the high-definition live feed demonstrated at the launch event and now available onboard Zhengzhou's trains. They are also susceptible to interference and limited in their capacity and speeds.

The live HD video stream is possible through LTE's high-bandwidth capacity of 150MB/s which is scalable and utilises clustering across multiple nodes which means that it is capable of hosting multiple services on a single platform while providing high availability. The video platform for example offers upload speeds of up to 100MB/s and a download speed of up to 50MB/s, which is superior to home and public broadband speeds, and unlike WiFi is not impacted by the number of users accessing the system.

The system also offers a latency of just 50ms, even when operating at 200km/h, with successful tests of its resilience carried out at speeds as high as 430km/h on Shanghai's Maglev line. Huawei says this is a major advantage over WiFi which can become unreliable at speeds of more than 100km/h.

Another major selling point that Huawei is pushing is the platform's capability to lower life-cycle costs by reducing the amount of equipment required for installation. By hosting all services on a single platform, equipment required for separate infrastructure is removed and with it the risk of a fault arising.

In addition LTE utilises less equipment to support the communications network compared with WiFi-based networks. On these networks base stations are required to be positioned around 300-500m apart to support the high-frequency but low-power WiFi signal derived from a leaky feeder cable. In contrast LTE (and GSM-R) are derived from public mobile networks with much stronger amplifiers which enables them to use leaky feeder cables and antennas at distances of 1.6 to 3.2km between base stations. On Line 1 in Zhengzhou a total of 23 base stations are installed. These are supported by 62 antennas in each of the network's twin-bore tunnels which emit the frequency.

WiFi's ability to provide a stable service at speeds of less than 100km/h, which is the norm for metro operations, and the relatively low cost of maintaining base stations and reasonably long maintenance intervals, still makes it a commercially attractive installation.

Huawei argues that the capability to position base stations at varying distances means it is possible to locate them next to existing power sources and also avoid the need for maintenance staff to work in the tunnels and potentially disrupt traffic. Indeed Huawei says reducing the amount of equipment in use overall will counter the higher cost of its LTE platform in the long-term, while its ability to easily host bandwidth-hungry applications such as CCTV and public WiFi networks makes the switch to LTE increasingly attractive.

"In my opinion on metro lines that already use WiFi, it is possible to initially adopt eLTE as a backup system to these existing platforms and for them to function together with a view to eventually replacing WiFi-based networks with LTE," Zhang says. "We are ready to work with these existing networks. For the Metro Line 2 extension in Zhengzhou, we are hoping to gradually put LTE into use and by guaranteeing that it will facilitate the move from separate Tetra communications to those hosted over LTE."

Big test

Of course hosting signalling and other safety-critical communications over LTE is the big test for the platform and Huawei and other suppliers' arguments that it will become the choice for the next generation of railway communications. Insigma, China, in partnership with Ansaldo STS, installed the CBTC signalling network in Zhengzhou and while the system was built for WiFi, the supplier will work closely with Huawei over the next few months to facilitate the upgrade.

Tests to host CBTC on eLTE are already underway and Huawei says it has reported a 94% successful connection rate at a latency of 100ms or less, with some tests reporting success at as low as 28ms.

"We are taking a prudent attitude to adopting CBTC," Zhang says. "We are currently cooperating with Insigma to conduct tests at the laboratory at Tanjing University where we have run a simulator which has produced the expected results. We will repeat this and run more tests to further our cooperation which will result in moving CBTC to the LTE network."

Zhang says adopting industry-recognised standards will be a major step forward for the adoption of LTE but admits that this is still "two to three years away," adding that in China Huawei hopes that LTE becomes the standard communications platform for proposed "smart cities."

As a newcomer to the international market, research and development is driving Huawei's attempts to establish itself as the major supplier of the next generation of communications technology. The company invested a whopping $US 4.8bn in technologies such as LTE in 2012, which Zhang says is key to the company's growth.

Outside China, he says Huawei is targeting the Asia-Pacific region, South America and at some point Africa with its LTE solutions. And while "interest is growing in Europe in its products," Zhang says it remains a "rather conservative" market. "We will need references before we are able to succeed here," he says.

Zhengzhou is the first such reference for a metro application and it is evident that Huawei hopes success here will begin to convince other operators of 4G LTE's potential. Indeed with passengers increasingly demanding access to data-hungry applications while on the move, it is certainly an argument that is gaining traction.

Zhengzhou metro up and running

ZHENGZHOU Metro Line 1, runs entirely underground for 26.3km from Xiliuhu to City Sports Centre with 18 intermediate stations.

Construction commenced in June 2009 and was completed in March 2013. Line 1 is expected to serve a peak of 100,000 passengers during holidays and is served by a fleet of 25 six-car Type B metro tzhengzhourains supplied by CSR Zhuzhou. Siemens supplied propulsion systems for the trains, with 12 of the 22 sets delivered so far now in service. The full fleet is expected to enter service by September, operating at six-minute intervals.

Zhengzhou's metro plans do not stop at Line 1. Zhengzhou Metro Company plans to invest Yuan 10.2bn ($US 1.68bn) in its metro network development plan, with construction of the initial 19km, 16-station section of the north-south Line 2, 17.25km of which is underground, underway and expected to open in 2015.

Work on the 40.8km east-west Line 3 is set to commence later this year and be completed by 2018, while work on the 35.3km Z-shaped Line 4 will start in 2015 and open in 2020. Line 5, a 41.8km ring line, which has received funding from the World Bank, will be completed in 2016. North and south extensions of Line 1 are also envisaged.

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