VirtualLink was a proposed USB-C alternate mode that was historically intended to allow the power, video, and data required to power virtual reality headsets to be delivered over a single USB-C cable and connector instead of set of three different cables as it was in older headsets. The standard was supported by Nvidia, AMD, HTC Vive, Oculus VR, Valve, and Microsoft. The VirtualLink Consortium was chaired by Rambo Jacoby representing Nvidia. VirtualLink never launched successfully.
According to its specifications, the VirtualLink cable consisted of:
- 4x DisplayPort balanced pair data path
- DisplayPort HPD (hot-plug detection pin) as a single wire.
- DisplayPort AUX signal as a balanced pair
- USB 3.1 signals
- A USB TX balanced pair for USB 3.0 data
- A USB RX balanced pair for USB 3.0 data
- I2C wire to control the USB Billboard interface, in case the cable is plugged into an unsupported interface.
- VBUS carrying power to HMD visor
- GND ground
The USB-C plug pinout specified:
Unlike most alt-modes this remapped A7, A6, B6, B7 to carry a USB 3.0 signal, instead of the usual passive USB 2.0 signal. This means that one would not be able to extend the cable using a standard USB-C 3.0 cable, which has these pins mapped only for unshielded USB 2.0 signals. Also this required the VirtualLink port to also detect the correct orientation of the USB-C plug to ensure that the USB 3.0 TX and RX lanes are correctly connected.
In VirtualLink mode, there were six high-speed lanes active in the USB-C connector and cable: four lanes transmit four DisplayPort HBR 3 video streams from the PC to the headset while two lanes implement a bidirectional USB 3.1 Gen 2 channel between the PC and the headset. Unlike the classic DisplayPort USB-C alternate mode, VirtualLink has no USB 2.0 channels active, instead providing a higher speed USB 3.1 Gen 2 (SuperSpeed+) over the same A6, A7, B7, B6 pins. VirtualLink also required the PC to provide 15 to 27 watts of power. No information pertaining to VirtualLink alternate mode compatibility with USB4 (and so Thunderbolt 3 alternate mode) had been published.
To achieve six high-speed lanes over USB-C, VirtualLink required special cables that conformed to version 1.3 of the USB-C standard and used shielded differential pairs for both USB 2.0 pairs.
The available bandwidth was estimated to be equivalent to DisplayPort 1.4 (32.4 Gbit/s, up to 4K @ 120 Hz with 8 bpc color) for video and 10 Gbit/s of USB 3.1 Gen 2 data.
Implementation in graphics cards and devices
As of March 2023 Sony PSVR2 has a single 5m cable VirtualLink connection to PS5 which seems to be working with Nvidia GeForce 20 series cards as well.
Nvidia GeForce 20 series cards, initially released in 2018, implemented a single VirtualLink port in all RTX Founders Edition (FE) cards (2060, 2070, 2080, 2080 Ti). This port was also made available on Quadro RTX cards.
As of Nvidia's GeForce 30 series cards announcement, all of Nvidia's new Founders Edition GPUs, alongside the partner boards announced so far, lacked a VirtualLink port due to its discontinuation. By contrast, the AMD Radeon RX 6000 series, announced in October 2020, implemented a VirtualLink port for the first time.
Discontinuation & abandonment
As of August 2020, the VirtualLink standard had failed to propagate into the virtual reality headset market. The Valve Index had initially developed a VirtualLink accessory, but it was canceled due to technical signaling and reliability issues. By September of that year, it had been abandoned by its consortium, and the website now redirects to its Wikipedia page.
- ^ "The next generation of VR headsets will connect over a single USB-C cable". The Verge.
- ^ "VirtualLink: Everything USB Type-C Is Supposed To Be". Forbes. 2018-08-17.
- ^ a b c d Smith, Ryan (July 17, 2018). "VirtualLink USB-C Alt Mode Announced: Standardized Connector for VR Headsets". AnandTech. Retrieved 2018-08-21.
- ^ "Virtual reality giants unveil VirtualLink as a standardized cable that may simplify VR rigs". PCWorld.
- ^ "VirtualLink Removes Tangles from VR Goggles". EEJournal. 7 August 2018.
- ^ Lang, Ben (20 August 2018). "GeForce RTX Cards Announced with VirtualLink VR Connector". Road to VR.
- ^ "NVIDIA Unveils Quadro RTX, World's First Ray-Tracing GPU". NVIDIA.
- ^ Smith, Ryan. "NVIDIA Announces the GeForce RTX 30 Series: Ampere For Gaming, Starting With RTX 3080 & RTX 3090". www.anandtech.com. Retrieved 2020-09-03.
- ^ Lang, Ben (2020-10-28). "AMD Announces Radeon RX 6000-series GPUs with USB-C "for a modern VR experience"". Road to VR. Retrieved 2020-11-09.
- ^ "Valve Cancels VirtualLink Adapter Accessory for Index, Cites Technical Issues & Laptop Adoption". RoadtoVR.
- ^ Lang, Ben (2020-09-03). "The VirtualLink Single-cable VR Headset Connection Standard Has Been Abandoned". Road to VR. Retrieved 2021-12-11.