1. Transmission bandwidth: USB 3.2 has a maximum of 20Gbps (USB3.2X2 has a maximum of 40Gbps), while USB4 has a maximum of 40Gbps.
2. Transmission protocol: USB 3.2 mainly transmits data through the USB protocol, or configures USB and DP through DP Alt Mode (alternative mode). USB4 uses tunneling technology to encapsulate USB 3.2, DP and PCIe protocols into data packets and send them simultaneously.
3. DP transmission: all support DP 1.4. USB 3.2 configures output through DP Alt Mode (alternative mode); USB4 can not only configure output through DP Alt Mode (alternative mode), but also extract DP data through USB4 tunnel protocol packets.
4. PCIe transmission: USB 3.2 does not support PCIe, only USB4 does. Extract PCIe data through USB4 tunneling protocol packets.
5. TBT3 transmission: USB 3.2 does not support it, but USB4 does. It extracts PCIe and DP data through USB4 tunnel protocol packets.
6. Host to Host: Communication between host and host, USB3.2 is not supported, USB4 is supported. Mainly USB4 supports the PCIe protocol to support this function.
7. USB4™ Tunneling architecture packages USB3/DisplayPort™/PCI Express in the same interface for transmission, and the bandwidth allocation of each protocol can be dynamically adjusted
8. USB4™ can choose whether it is compatible with TBT3 system
9. USB4™ supports Host to Host (host-to-host docking and transmission signal)
In USB 3.2, DisplayPort video and USB 3.2 data are transmitted on different channel adapters, while in USB4, DisplayPort video, USB 3.2 data and PCIe data can be transmitted on the same channel. This is the biggest difference between the two. .
From the above characteristics, it is not difficult to find that the logical architecture of USB4™ is very similar to the network architecture. A fixed frame and physical layer are used to carry different protocol packets, which can include data and image packets, and each packet is marked with an address to ensure correct transmission. Therefore, USB4™ gradually gets rid of the functional limitations of traditional USB Host and USB Device. USB4™ uses point-to-point transmission method. This design reserves great flexibility for improving transmission speed and functionality in the future.
