The USB Promoter Group, the organization responsible for setting the specifications for USB connectors, announced the latest update to the USB protocol, called the USB4. The organization based the newest USB specification on the proprietary Thunderbolt interface developed by Intel, and the specification offers a bandwidth of 40Gbps over two data lanes. In comparison, USB 3.2 standard, which the group unveiled back in 2017, can only provide a 20Gbps connection over two lanes.
While previous generations of the USB protocol already allowed people to connect displays through the USB Type-C port, USB4, with its increased bandwidth and broader support of display interfaces, now enables users to connect multiple devices with the same wire. However, having massive amounts of bandwidth is not enough to ensure that all devices that communicate through the same link have sufficient bandwidth. The new connectivity standard solves this concern by supporting a broader range of data and display protocols, and it also introduces a new method that quickly and automatically adjusts the transfer of data. For example, in the case of multiple devices like monitors and external storage connected on the same link, USB4 enables host devices to allocate the amount of data delivered to each device dynamically.
Despite the new features offered by the USB4 protocol, the latest specification remains compatible with existing two-lane USB Type-C cables currently used by USB 3.2 devices, although cables that already support 40Gbps data speeds are needed to achieve the maximum data transfer rates offered by USB4. Furthermore, USB4 also maintains compatibility with USB 3.2, USB 2.0, and Thunderbolt 3.0 devices, which may include external storage devices and GPU enclosures. Nonetheless, the USB Promoter Group will update the USB Type-C port to better support the performance requirements and identification of USB4 devices.
Background: The introduction of the USB4 specification is one of the recent changes made to the USB protocol. Recently, USB-IF announced a new designation for existing standards USB 3.2, USB 3.1, and USB 3.0. USB-IF now classifies all three standards as USB 3.2, and all of them will bear the SuperSpeed designation. For example, USB 3.0 will now be called as both SuperSpeed USB and USB 3.2 Gen 1, while the USB 3.1 standard will now be identified as USB 3.2 Gen 2 and SuperSpeed USB 10Gbps. Meanwhile, people may classify USB 3.2 as SuperSpeed USB 20Gbps and USB 3.2 Gen 2x2, a likely reference to the specification's support for two data lanes. The organization has yet to identify a commercial name for the USB4 protocol, although it may also feature the SuperSpeed name once the standard becomes more widely available.
Impact: The full description of the USB4 protocol will likely become available once the USB Promoter Group publishes the details of the specification by mid-2019. Once the information on the standard become available, consumers will have a better idea of all the improvements included with the new standard. Furthermore, some of the features from previous versions of the protocol will likely be present in USB4, including support for 100-watt charging made possible by USB Power Delivery. Moreover, the USB Promoter Group also stated that there would be improvements to the USB Type-C port and the USB Power Delivery technology, and the organization will detail these changes in the second half of 2019.