The USB Implementers Forum (USB-IF) has announced the USB4 specifications have been published. USB4 is hailed as a significant update that will deliver next-generation USB architecture that complements and builds upon the existing USB 3.2 and USB 2.0 architectures. USB4 is based on the Thunderbolt protocol specification that was contributed recently by Intel and the USB Promoter Group.
USB4 promises to double the maximum aggregate bandwidth of USB and enables simultaneous data and display protocols. Development of USB4 specifications started in Q1 2019 and is now officially available for download here [ZIP].
USB4 offers two-lane operation using existing USB Type-C cables and supports up to 40Gbps operation over certified cables. The specification supports multiple data and display protocols and efficiently shares the maximum aggregate bandwidth. USB4 is backward compatible with USB 3.2, USB 2.0, and Thunderbolt 3 despite introducing a new underlying protocol.
USB-IF notes that the USB Type-C connector has evolved into an external display port for many host products and that the USB4 spec provides the ability to optimally scale allocations for display data flow. By integrating Thunderbolt into the USB4 specification, this should mean that computer makers standardize USB-C ports in the future.
The first systems using USB4 are expected to hit the market in early 2020, and we can expect for it to slowly be integrated into systems much in the same way that we say with USB-C and Thunderbolt 3, which are now commonplace on laptop and desktop PCs.