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Social network experiments with WiGig, 96-antenna MIMO to improve coverage, capacity.
Facebook this week revealed it is experimenting with two upcoming network technologies that promise to improve high-speed wireless capacity and coverage.
The first is called Terragraph and uses the WiGig WiFi standard to provide gigabit broadband in urban environments.
WiGig uses the unlicensed 60 GHz band, which helps to keep costs down but also presents a problem in the form of poor signal propagation. To overcome this, Facebook’s Terragraph system consists of distribution nodes placed at 200 metre-250 metre intervals. These nodes are equipped with phase array antennas to ‘steer’ signals around obstacles.
These distribution nodes connect to client nodes, such as a WiFi or Ethernet access point, to provide the final connection to the device. The network is monitored and controlled by the same technology Facebook uses in its data centres.
"Terragraph is one of the lowest-cost solutions to achieve 100% street-level coverage of gigabit WiFi," declared Facebook.
Facebook is currently testing out Terragraph at its Menlo Park headquarters, and is planning a live trial in San Jose, California.
The second network experiment unveiled by Facebook this week is called Project ARIES (Antenna Radio Integration for Efficiency in Spectrum).
Based on massive multiple input, multiple output (MIMO), it uses 96 antennas and spatial multiplexing to transmit 24 data streams simultaneously over the same frequency to improve spectral and energy efficiency.
"We are currently able to demonstrate 71 bps/Hz (bits per second, per hertz) of spectral efficiency, and when complete, ARIES will demonstrate an unprecedented 100+ bps/Hz of spectral efficiency," Facebook said.
Facebook sees Project ARIES as a means of providing wide-area mobile coverage in rural areas.
According to Facebook’s research, nearly 97% of the world’s population lives within 40 kilometres of a major city, so it is keen to explore how ARIES can be deployed in cities to provide coverage to surrounding rural areas.
"Additionally, providing backhaul to rural environments can be prohibitively expensive, but the hope with systems such as these is that costly rural infrastructure can be avoided while still providing high-speed connectivity," Facebook said.
