Today, passengers of transportation systems expect similar Internet access to what they are used to at home so that productivity is maintained while in transit. Providing communications to trains is not an easy task, and the following possibilities can be explored:
- Commercial Cellular: Although there are several cellular operators, coverage is spotty along the railroad with long lengths of limited or no coverage. Spare traffic availability per cell is limited, so only throughput availability can be expected. Trains will be generally at the edge of cell coverage and communicate at low modulation schemes, consequently reducing the cell capacity.
- Private Trackside Network: This is the best way to guarantee uniform quality and throughput, but the deployment can be expensive and is only justifiable in high traffic density routes.
- Satellite: Existing Ku-band satellites have low capacity, are congested, and prices are high. New Ka-band satellites should be fully available by the end of 2016 when higher capacity and lower prices can be expected. Due to price issues this solution is sensible only when the other solutions are not available.
CelPlan’s CellRail™ solution explores these three possibilities, routing the traffic so that throughput is maximized, and costs minimized. The service offering inside the train also has many challenges and requires a careful design. A single car may require a throughput of 20+ Mbps. The CelPlan solution provides a train throughput above 100 Mbps. Deploying antennas at every car is expensive and a cumbersome for maintenance, so inter-car connections are recommended. These connections must be economical and high capacity, as they may have to carry additional content, like on-demand video.
Additionally, technology is evolving at a high pace, and better solutions became available constantly. An effective deployment should use COTS (Commercial Off-The-Shelf) components that can be upgraded/replaced with ease. With all this in mind, CelPlan developed CellRail ™. It can be customized to customer needs, using different COTS options and can be evolved and upgraded over time. CellRail ™ also provides intra-train communications support for other applications such as PTC (Positive Train Control).
The CellRail composition is shown in the diagram.