Rail and Military Applications Boosted Through Wi-Fi Node Mobility

MeshDynamics' MD4000 family of wireless mesh networking nodes has demonstrated new mobility capabilities in technical pilot trials in high-speed rail and military applications.In the rail application, a series of MD4000 wireless mesh nodes deployed lineside along the tracks was able to communicate with additional MD4000 nodes installed on railcars moving at speeds well over 100 mph. This successful pilot paves the way for deployment of commuter Wi-Fi services inside the moving railcars, IP video surveillance of rail car interiors, and safety-related driver video of station platform approaches, among others.

The military application supported threat sensors in a deployed combat environment. MeshDynamics MD4000 nodes mounted on moving vehicles were able to maintain seamless communications as the vehicles moved about in the terrain. Although the network topology changed continuously, significantly, and unpredictably, communication between the networked sensors was maintained through the MD4000 wireless mesh network.

The Challenge of Wireless Mesh Node Mobility
While the Wi-Fi 802.11 specifications implicitly provide for client mobility, in most cases wireless mesh node mobility has been limited to low-performance single radio ad hoc mesh solutions. Higher performance third-generation wireless mesh products often require extensive site engineering and aiming of directional antennas, which precludes node mobility. Moving any node would break its connection with the rest of the network.

"Users were always stuck with two bad choices: low performance one-radio nodes that could move, or higher performance nodes that were fixed," suggested Francis daCosta, CTO of MeshDynamics. "What MeshDynamics has done is prove that very high performance mesh nodes can be mobile -- and at high speeds."

Distributed Intelligence Provides High Speed Mobility
MeshDynamics' enhanced performance in high speed mobility applications is due to dynamic distributed radio intelligence in each wireless mesh node. In essence, MeshDynamics has created a wireless radio "robot" in each node, managing topology and channel selection in an independent but coordinated fashion with the rest of the network.

This distributed dynamic radio intelligence is combined with a scanning radio in each mobile wireless mesh node. The scanning radio constantly monitors the environment for interference sources and other MeshDynamics wireless mesh nodes that are part of the same network. This capability allows the moving node to communicate its switchover from a node it is leaving to a node it is approaching. This seamless hand-off from node to node allows commuters in a railcar to maintain uninterrupted Internet sessions at speeds up to and beyond 250 mph (400 kph).

"The switchover must be coordinated," noted daCosta "Or clients associated to the moving nodes may be disconnected abruptly. And the network must use Third-Generation multi-radio technology or advanced applications such as video won't work. Only MeshDynamics provides both capabilities in a single node."

With these successful rail and military trials complete, MeshDynamics is looking forward to rolling out a number of production mobile networks in the next 6 months.

Mobility Features across Multiple Radio Types
Because the enhanced mobility features for the MD4000 family are primarily software-based, the capabilities are available for all current and future supported radio protocols. Besides Wi-Fi 802.11a/b/g, mobility features are also supported for the company's new 4.9 GHz public safety band radios, for applications such as mobile first responder and security vehicles.