Analysis of wireless communication technology for trains and vehicles

Automatic train operation (ATO) and automatic train protection (ATP) greatly improve the efficiency and safety of train operation. In order to establish communication between trains and tracks, CBTC (communication-based train control technology) currently uses WLAN as the system foundation. WLAN solutions have become an important tool for inter-vehicle and vehicle-to-ground communication networks because they have broken through the cable. With enhanced reliability and bandwidth, WLAN can also be used to support in-vehicle video surveillance, passenger information systems, and train control technology as an important part of ATO and ATS. The vehicle is a uniquely challenging operating environment. All equipment used on the train must meet the EN50155 standard, including specifications for EMC, shock and shock, extreme temperature, and humidity resistance.

Application requirements

Seamless connection between the car and the inner ring of the car covers flexible car changes, low maintenance requirements and reliable real-time PIS (passenger information system)
The high throughput of the real-time public address and video surveillance system complies with strict vehicle standards

System specification

Passenger safety and high-availability connections are the most important for on-board train networks. These networks allow railway operators to share real-time train, OCC, and inter-station communications to provide immediate status updates and emergency control.

In this application, the train has 6 cars. The AWK series is used to provide Wi-Fi on trains. Each car is equipped with a VPort 15 IP video camera, connected to the wireless network through the built-in Ethernet port. Single RF device AWK-3121, used as a client to access the camera in the front and rear cars. The dual-radio frequency device AWK-5222 is deployed in the middle 4 cars and can be configured through the AP client connection mode. In this mode, the first RF provides a link between cars, or AP mode, and the second RF provides client mode access to the camera. One path uses 802.11b 2.4 GHz and the other path uses 802.11a 5 GHz to overcome radio frequency interference in the RF environment.

In order to maintain stable communication during data transmission, the fourth car also includes an additional 802.11n AWK-3132 connected via the Ethernet port of AWK-5222 and running as a client. Outdoor 802.11n AWK-4132 is set as an AP outside the station. Such an IEEE802.11n architecture provides high bandwidth to ensure real-time train public address and video surveillance. When the AWK-3121 in the car is in motion, fast roaming ensures a seamless car-to-ground connection. There is an on-board server connected to the EN50155 network-managed switch in the front car, which is used to handle on-board traffic and data transmission between the train and the ground.

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