The Defence and Automation Solutions Company - Dynalog India

DEVELOPING REAL-TIME VIDEO DATA COMMUNICATION FOR A METRO [case study]

Introduction One of the largest players within the railway industry needed to develop the rail communication network for a metro in India. In order to enhance passenger safety, the network needed to be able to support a state of the art CCTV surveillance system that provides real-time monitoring from the control center. The project requires a reliable train-to-ground wireless network that connects to rail-certified onboard wireless clients, trackside wireless units, and trackside Ethernet switches. The onboard wireless clients need to provide seamless roaming, wireless network redundancy, and sufficient bandwidth to ensure smooth video data transmission on constantly moving trains. For the trackside network, a redundant network topology is required to avoid packet loss when transmitting data from the trackside to the control center.

SYSTEM REQUIREMENTS ● Wireless devices that can transmit video data at up to 12 Mbps ● A fast roaming mechanism to ensure seamless transmission of video footage while trains are operating ● A network redundancy mechanism for train to ground communications in order to support real-time monitoring from the control center

MOXA SOLUTION To assist the company develop a reliable train-to-ground wireless network, Moxa provided a variety of rail-certified products that were deployed onboard and at the trackside. Our AWK-4121* Series, which was customized for this project, was used

onboard as a wireless client to deliver video data seamlessly to the trackside by offering 12 Mbps throughput. This was complemented by WAC-2004 controllers that support 50 ms handoff times, which were located in the control center. Moreover, our customized AWK-4121* Series wireless client features AeroLink Protection which ensures reliable wireless network failover connection times of less than 300 ms. The TAP-6226** wireless trackside units functioned as wireless APs to collect the video data onboard and a built-in fiber Ethernet switch was used to deliver the video data to the fiber network backbone. As the overall length of the metro line exceeds 25 km, the network backbone requires several switches with large bandwidth capabilities to ensure smooth data transmission. The IKS-G6524A layer 2 full Gigabit rackmount switches were deployed at the trackside and the ICS-G7828A layer 3 full Gigabit rackmount switches were utilized in the fiber network backbone to create the Turbo Chain topology. In addition, our rugged trackside wireless unit, TAP-6226**, provided network redundancy by guaranteeing recovery times of less than 100 ms.

All of the products Moxa provided have rugged designs to withstand the harsh environments that are experienced onboard trains and at the trackside. Our products’ features include the ability to withstand strong vibrations, operating temperature ranges of up to -40 to 75°C, and waterproof designs that include products with the IP68-rating.

A combination of our unique network technology, rail-certified products, and our sincere customer service allow Moxa to help our customers develop reliable CCTV communication systems that enhance passenger safety onboard trains.

WHY MOXA ● Use of the IEEE 802.11a/b/g standard ensures 12 Mbps throughput ● Controller-based Turbo Roaming technology for roaming handoff under 50 ms ● Turbo Chain topology provides fast network recovery (under 100 ms) at the trackside

● AeroLink Protection provides wireless network failover mechanism (under 300 ms) for train-to-ground network communications ● IP68-rated products for outdoor applications ● -40 to 75°C wide operating temperature range (T models) ● TAP-6226** wireless units and AWK-4121* Series wireless clients comply with the relevant portions of the EN 50155 standard ● EN 50121-4 compliant for IKS-G6524A and ICS-G7824A full Gigabit Ethernet switches