H3C Wi-Fi 6 Urban Rail Transit Train-to-ground Wireless Communication Solution

The Wi-Fi 6 urban rail transit vehicle-to-ground wireless communication solution of H3C Group, a subsidiary of Unisplendour Corporation Limited (UNIS), has won bids for Shenzhen Metro Line 14 and Line 16 and Hangzhou Metro Line 3. This is the first three metro lines in China to adopt Wi-Fi 6 wireless communication technology, demonstrating the strength and technical advantages of H3C in the field of metro train-to-ground wireless communication.

With the introduction of full-auto driving and more smart services in the future, the communication and service systems of urban rail transit for bandwidth of the train-to-ground wireless communication network continue to increase. WLAN train-to-ground communication and train-to-ground wireless communication solution have been one of the solutions with cost efficiency, high technology maturity, complete ecological chain, and widely used cases. At present, more than 65-70% of urban metro lines choose to use WLAN technology to build the train-to-ground wireless communication network every year. Since the application of WLAN technology to urban rail transit scenario in 2007, H3C Group has been making achievements as the industry leader: Introducing IEEE802.11ac wave1 technology to domestic urban rail transit industry in Nanning Metro Line 1 in 2016; being the first to apply IEEE802.11ac wave2 technology in Shijiazhuang Metro Line 2 in 2020; releasing the new generation of urban rail transit dedicated AP, based on IEEE802.11axWi-Fi 6. H3C has been leading technological transformations by providing innovative and customized train-to-ground communication and train-to-ground wireless communication solutions for customers.

I. Wi-Fi 6 technology greatly improves the application experience of train-to-ground wireless communication solutions with WLAN technology.

H3C Wi-Fi 6 urban rail transit solution brings a comprehensive technological reform. It provides better application experiences for full rail transit scenarios.

Overview of metro Wi-Fi 6 applications

Wi-Fi 6 uses the OFDMA technology, which redesigns the frame structure into several resource units (RUs) that can be allocated to different users at the same time. This greatly improves the access efficiency of the terminals. Especially in intensive coverage scenarios like metro depot, Wi-Fi 6 uses the OFDMA technology that will greatly improve the access rate of trains, enabling automatic and fast transmission of train O&M data and other video and audio data. Meanwhile, with the perfect MU-MIMO technology and the new spatial reuse (SR) technology, the performance of MU-MIMO scenarios is improved and the problem of interference to the same channel communication is solved. It is especially suitable for scenarios such as depot, station halls and platforms where intensive coverage is accompanied by same-frequency interference. It can greatly improve the experience of using Wi-Fi networks. The higher 1024QAM modulation mode brings the greater data throughput performance. The actual train-to-ground communication and train-to-ground wireless communication data throughput rate can reach more than 1 Gbps, and the ultra-high bandwidth for the train-to-ground communication and the train-to-ground wireless communication reserves an efficient data transmission channel for the introduction of AI, VR and AR technologies in the future.

II. H3C expands the application of WLAN technology for Wi-Fi 6 train-to-ground wireless communication solution with comprehensive ICT convergence capabilities.

With the comprehensive convergence capabilities of the H3C Group, the integration of IoT capabilities is carried out on the metro dedicated Wi-Fi 6 products, which can extend IoT base stations through trackside devices to achieve a variety of IoT network coverage, enabling high-precision positioning of people and important equipment in the tunnel.

With the WLAN terminal access capability, a PoC network can be built, where trunking communications, work order issuance and expert remote consultation within the O&M system can be realized through a simple cell phone terminal and the trunking communication app. It helps the urban rail transit industry build a smart O&M system.

III. H3C is committed to bringing excellent customized professional devices to the metro industry

In 2020, H3C Group released the industrial Wi-Fi 6 AP devices for metro, which fully considered the deployment environment of metro industry applications and user habits in product design. It greatly simplifies the device deployment. Currently, H3C metro dedicated industrial Wi-Fi 6 devices are also the first metro dedicated AP devices in the industry to obtain the radio transmission equipment type approval certificate and the professional environmental test report for the metro industry.

Trackside Wi-Fi 6 products and onboard Wi-Fi 6 products

These products can support up to 8 spatial streams, and can also be split into two 4 spatial streams RF to meet the custom needs for different scenarios. Both products can adapt to both trackside and onboard power supply environments without the need to configure additional power modules. This effectively reduces failure points and improves the stability and reliability of the entire system.

IV. H3C's original soft switching technology of train-to-ground communication and train-to-ground wireless communication guarantees low latency and low packet loss rate for switching.

The wireless link switching during the train movement at a high speed is one of the most critical factors affecting the effectiveness of the train-to-ground communication and train-to-ground wireless communication. In order to meet the demand of wireless link switching in metro, H3C Group has developed a unique and innovative wireless link switching technology based on wireless mobile fast switching technology, whose algorithm allows the on-board AP and trackside AP to transmit data while establishing a backup link with the adjacent trackside AP. The wireless link switching is a soft switch between the primary and backup links, resulting in fast link switching and low packet loss.

V. H3C realizes the application of WLAN technology on moving trains at the speed of 160 km/h.

As more and more high-speed metro lines and urban rail lines are prepared for construction, as well as the continuous advancement of the intelligence in metro, the high-speed adaptability and high bandwidth requirements of the train-to-ground wireless communication have become a challenge that stands in the way of the metro industry development. Facing the challenges of rapid progress in the metro industry, H3C Group actively responds to the market's demand and upgrades the WLAN train-to-ground wireless solution. It organizes the dynamic test on train-to-ground wireless communication of high speed trains at the National Railway Track Test Center of China Academy of Railway Sciences, and invites experts from the State Key Laboratory of Rail Transit Control and Safety (Beijing Jiaotong University), an authoritative third party, to preside over the tests to ensure the advancedness of the test methods and the authoritativeness of the test results.

Train operation test

According to the test results, H3C WLAN train-to-ground wireless communication solution is completely adaptive to high speed train operation scenarios. The average packet loss rate is less than 0.1% and the average switching latency is less than 15ms. With the original wireless link switching technology, the MESH networking and the original MLSP technology, the train-to-ground wireless communication under the high-speed train operation scenario fully meets the relevant standards of the passenger information system (PIS) in the rail transit industry, demonstrating the technicality of H3C WLAN train-to-ground wireless communication solution.