DARPA goes rugged with battlefield communications

Modern armies rely on battlefield communications and networking systems to maintain situational awareness. This is especially true for smaller units operating in rugged and remote areas where there is little or no infrastructure. The advent of unmanned vehicles and handheld devices designed to receive data from various reconnaissance assets overhead has also created an additional need to extend communications down to individual squads and soldiers operating at the very edges of military networks.

To meet these needs, the Defense Advanced Research Projects Agency has launched several related efforts designed to provide warfighters in remote areas with high-bandwidth communications. The goal of the Fixed Wireless at a Distance program is to develop mobile systems that provide cell tower-class performance without the fixed infrastructure.

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DARPA’s Mobile Hotspots program plans to develop and demonstrate a mobile millimeter-wave communications backbone with the capacity, range and scalability to link dismounted troops with forward operating bases, tactical operations centers, intelligence, surveillance and reconnaissance assets, and fixed communications infrastructure. The planned backbone should also provide end-to-end data delivery between wireless hotspots and from ISR platforms and command posts to hot spot users, DARPA officials said.

Current military communication systems have limited ability to support mobile, distributed operations in remote geographic areas because of small network sizes and the relatively short range of military radios.

The military uses mobile ad hoc networks to relay communications traffic and provide wireless links beyond the range of a single radio. But when a MANET grows, traffic is divided into the number of users on the network, and the service data rate delivered to an individual in a MANET drops to a small fraction of the radio capability, DARPA officials said. According to the agency, the scaling limitations of a MANET — typically tens to hundreds of users — are reached when the traffic that can be delivered to an individual becomes unacceptably low. Much larger networks will be required as operations become more distributed and higher numbers of autonomous sensors are deployed.

Service delivery is expected to support three types of client radio systems: enhanced range communication devices, legacy military radio systems and commercial communications systems (such as 3G/4G cellular and Wi-Fi) for operations in the vicinity of the forward operating base, DARPA officials said.

Communications and data connectivity will be provided by air, mobile and fixed platforms. Most of these assets will be integral to the deployed unit and provide a 1 gigabit/sec tactical backbone network that extends down to the smallest units, DARPA officials said. The program plans to develop advanced pointing, acquisition and tracking technologies to provide high connectivity to the mobile hot spots. PAT technology is a vital piece necessary to turn small unmanned aerial vehicles into flying nodes on the mobile high-speed backbone, agency officials said.

Although some advanced commercial systems can be modified for the program, a number of technical challenges remain to providing data to remote operating zones.

“Mobile hot spots will require the development of steerable antennas, efficient millimeter-wave power amplifiers, and dynamic networking to establish and maintain the mobile data backhaul network,” program manager Dick Ridgway said in a statement. “We anticipate using commercial radio protocols, such as Wi-Fi, WiMax or LTE [Long Term Evolution], as a cost-effective demonstration of the high-capacity backbone. However, the millimeter-wave mobile backbone developed during this program will be compatible with other military radios and protocols.”

The program also seeks novel technologies to increase the transmission power to provide adequate ranges within the small size, weight and power constraints required for company-level UAVs. The Broad Agency Announcement can be viewed here.

About the Author

Henry Kenyon is a contributing writer for Defense Systems.

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