Tech Briefs

This system allows VR headsets to communicate without a cord.

One of the limits of today's virtual reality (VR) headsets is that they must be tethered to computers in order to process data well enough to deliver high-resolution visuals. Wearing an HDMI cable reduces mobility, and can even lead to users tripping over cords. Researchers have developed a prototype system called MoVR that allows use of any VR headset wirelessly.

MoVR consists of two directional phased-array antennas, each less than half the size of a credit card. (Photo: MIT CSAIL)

MoVR can enable untethered communication at a rate of multiple Gbps, or billions of bits per second. The system uses special high-frequency radio signals — millimeter waves (mmWaves) — that could also help deliver faster 5G smartphones. The system was tested on an HTC Vive, but it can work with any headset.

One issue with existing wireless technologies like WiFi is that they can't support advanced data processing. Replacing the HDMI cable with a wireless link requires streaming high-resolution, multi-view video in real time. This requires sustaining data rates of more than 6 Gbps while the user is moving and turning, which cannot be achieved by any of today's systems. Since VR platforms have to work in real time, systems also can't use compression to accommodate lower data rates.

The researchers instead turned to mmWaves, which have promising applications for everything from high-speed Internet to cancer diagnosis. The high-frequency waves have one major downside, which is that they don't work well with obstacles or reflections. For mm Waves to deliver constant connectivity for a VR game, there must always be a line of sight between the transmitter and receiver. The signal can be blocked even by just briefly moving a hand in front of the headset.

To overcome this challenge, MoVR acts as a programmable mirror that detects the direction of the incoming mmWave signal, and reconfigures itself to reflect it toward the receiver on the headset. MoVR can learn the correct signal direction to within two degrees, allowing it to correctly configure its angles. With a traditional mirror, light reflects off the mirror at the same angle as it arrives. With MoVR, angles can be specifically programmed so that the mirror receives the signal from the mmWave transmitter and reflects it towards the headset, regardless of its actual direction.

Each MoVR device consists of two directional antennas that are each less than half the size of a credit card. The antennas use phased arrays to focus signals into narrow beams that can be electronically steered at a timescale of microseconds.

Future versions of MoVR's hardware could be as small as a smartphone, allowing for users to put several devices in a single room.

For more information, contact Adam Conner-Simons at This email address is being protected from spambots. You need JavaScript enabled to view it. u; 617-324-9135.

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