C4ISR

Radio connectivity on the fly

The Soldier Radio Waveform (SRW), and its reputation for agility, is a big part of what makes the Rifleman and other Joint Tactical Radio System radios so advanced.

“Waveform” is a catchall term for the processed radio signal that carries voice and data communications through the electromagnetic spectrum. What sets SRW apart is its ability to manage a mesh network environment essentially on its own, said Larry Williams, JTRS technical director for ITT, the SRW developer. The company delivered a fully functional version to the JTRS joint program executive office in January, after a little more than two years of development work.

“This is a big deal,” Williams said. SRW is the first formally qualified JTRS waveform to reach the military, although it is still undergoing formal information assurance certification.

“Delivery of SRW capability is an absolutely essential enabler in achieving the JTRS Enterprise vision of delivering networking capability to warfighters at the tactical edge,” said Navy Capt. Jeff Hoyle, JTRS network enterprise domain program manager in a statement. It is one of several waveforms in development for the JTRS program, including the Wideband Networking Waveform, Joint Airborne Networking-Tactical Edge waveform and the Mobile User Objective System waveform.

SRW isn’t the first waveform to enable mesh networking, but it is extraordinarily agile in its ability to manage the mesh, Williams said. When radios act as both primary communication devices and routing nodes for signals coming from other devices in the network, there’s a danger that the routing function could swamp the network.

How quickly that occurs depends on what Williams describes as the network metabolism. That’s a way of describing how quickly conditions are changing, how many nodes are dropping in and out of connectivity, and how fast they’re moving in relation to one another. ITT’s solution was to create functionality that automatically subdivides the network into manageable tiers.

“I need to know in very real time what my connectivity is with my nearest neighbors. But I really don’t care to know what the connectivity is for people who are seven or eight hops away,” Williams said. Devices that drop out of one SRW network tier can automatically affiliate with another. “The network just manages itself,” he added.

This degree of automation surprised the Army during testing, Williams said. “Initial users want to over-manage the network; they want to define it specifically because that’s what they’ve done in the past. It will take them time to release control of it.” 

“Only a small portion of the channel is required to handle the overhead information flow,” he added.

Data messages will be lower priority than voice communications in SRW transmissions, Williams said. The amount of bandwidth at any one time consumed by data messages will depend on whether voice simultaneously requires bandwidth, he said.

About the Author

David Perera is a special contributor to Defense Systems.

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