DARPA, Northrop Grumman data-link demo showcased 100 Gpbs over 20 kilometers
NewsAugust 23, 2018
REDONDO BEACH, Calif. Defense Advanced Research Projects Agency (DARPA) and Northrop Grumman Corp. engineers set a new standard for wireless transmission by operating a data link at 100 gigabits per second (Gbps) over a distance of 20 kilometers in a city environment.
The two-way data link, which featured active pointing and tracking, was demonstrated early in the year in Los Angeles. According to Northrop Grumman officials, the data rate is fast enough to download a 50 Gigabyte blue ray video in four seconds. The demonstration marked the completion of Northrop Grumman’s Phase 2 contract for DARPA’s 100 Gbps (100G) RF Backbone program.
The 100G system is capable of rate adaptation on a frame by frame basis from 9 Gbps to 102 Gbps to maximize data rate throughout dynamic channel variations. Extensive link characterization demonstrated short-term error-free performance from 9 to 91 Gbps, and a maximum data rate of 102 Gbps with 1 erroneous bit received per ten thousand bits transmitted.
The successful data link results from the integration of several technologies. The link operates at millimeter wave frequencies (in this case, 71-76 gigahertz and 81-86 gigahertz) with 5 gigahertz of bandwidth, or data carrying capacity, and uses a bandwidth efficient signal modulation technique to transmit 25 Gbps data streams on each 5 gigahertz channel. To double the rate within the fixed bandwidth, the data link transmits dual orthogonally polarized signals from each antenna. Additionally, the link transmits from two antennas simultaneously (spatial multiplexing) and uses multiple-input-multiple-output (MIMO) signal processing techniques to separate the signals at two receiving antennas, thus again doubling the data rate within the fixed bandwidth.
“This dramatic improvement in data transmission performance could significantly increase the volume of airborne sensor data that can be gathered and reduce the time needed to exploit sensor data,” says Louis Christen, director, research and technology, Northrop Grumman.
“Next generation sensors such as hyperspectral imagers typically collect data faster, and in larger quantity than most air-to-ground data links can comfortably transmit,” Christen adds. “Without such a high data rate link data would need to be reviewed and analyzed after the aircraft lands.”
By contrast, a 100G data link could transmit high-rate data directly from the aircraft to commanders on the ground in near real time, allowing them to respond more quickly to dynamic operations.
The 100G ground demonstration sets the stage for the flight test phase of the 100G RF Backbone program. This next phase, which started in June, demonstrates the 100G air-to-ground link up to 100 Gbps over a 100 km range and extended ranges with lower data rates. The 100G hardware will be flown aboard the Proteus demonstration aircraft developed by Northrop Grumman subsidiary Scaled Composites.
Northrop Grumman’s 100G industry team includes Raytheon, which developed the millimeter wave antennas and related RF electronics and Silvus Technologies, which provides the key spatial multiplexing and MIMO signal processing technologies.
