Northrop, DARPA set new wireless transmission standard

Northrop Grumman and DARPA have set a new standard for wireless transmission by operating a data link at 100 gigabits per second (Gbps) over a distance of 20km in a city environment.

The two-way data link featuring active pointing and tracking was demonstrated in Los Angeles as part of Northrop Grumman’s Phase 2 contract for DARPA’s 100Gbps (100G) RF Backbone programme.

The 100G system is capable of rate adaptation on a frame by frame basis from nine Gbps to 102Gbps to maximise data rate throughout dynamic channel variations. 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.

Extensive link characterisation demonstrated short-term error-free performance from nine to 91 Gbps and a maximum data rate of 102Gbps with one erroneous bit received per ten thousand bits transmitted.

The link operates at millimeter wave frequencies - 71-76 gigahertz and 81-86 gigahertz - with five gigahertz of bandwidth or data carrying capacity and uses a bandwidth efficient signal modulation technique to transmit 25Gbps data streams on each five gigahertz channel.

To double the rate within the fixed bandwidth, the data link transmits dual orthogonally polarised signals from each antenna. Additionally, the link transmits from two antennas simultaneously (spatial multiplexing) and uses multiple-input-multiple-output signal processing techniques to separate the signals at two receiving antennas.

The flight test phase of the 100G RF Backbone programme will now demonstrate the 100G air-to-ground link up to 100Gbps over a 100km range and extended ranges with lower data rates.