100-Gigabit per second RF communications link envisioned between airborne and ground assets

Fiber optic cables provide the core backbone for military and civilian networks, enabling Internet, phone, video and other data to move at super-high speeds with virtually no degradation over long distances. In deployed environments, where a fiber optic backbone doesn't exist, other communications modes are used resulting in reduced data-rate capacity for the warfighter.

DARPA's 100 Gb/s RF Backbone (100G) intends to develop a fiber-optic-equivalent communications backbone that can be deployed worldwide. The goal is to create a 100 Gb/s data link that achieves a range greater than 200 kilometers between airborne assets and a range greater than 100 kilometers between an airborne asset (at 60,000 feet) and the ground. The 100G program goal is to meet the weight and power metrics of the Common Data Link (CDL) deployed by Forces today for high-capacity data streaming from platforms.

A major challenge to providing 100 Gb/s from an airborne asset to the ground is cloud cover. Free-space optical links won't propagate through the cloud layer, which means RF is the only option. The system will be designed to provide all-weather capability enabling tactically relevant data throughput and link ranges through clouds, fog or rain. Technical advances in modulation of millimeter-wave frequencies open the door to achieving 100G's goals.

"Providing fiber-optic-equivalent capacity on a radio frequency carrier will require spectrally efficient use of available RF spectrum," said Dick Ridgway, DARPA program manager. "100G plans to demonstrate how high-order modulation and spatial multiplexing can be synergistically combined to achieve 100 Gigabits per second with the size, weight and power needed for a deployable system. We believe that to achieve the program's goals requires the convergence of telecommunications system providers and the defense communications tech base."