FEC is a technique where the sender adds redundant data to its messages. This allows the receiver to detect and correct errors without needing a retransmission. The defines a lightweight FEC scheme specifically optimized for PCIe.
The Peripheral Component Interconnect Express (PCI Express) is a high-speed interface standard that connects peripherals, such as graphics cards, hard drives, and network cards, to a computer's motherboard. The PCI Express Base Specification Revision 6.0 PDF is the latest version of the specification, which outlines the requirements and guidelines for designing and implementing PCI Express systems.
The Revision 6.0 specification introduces three major architectural shifts to maintain high signal integrity and low latency while doubling performance: PCI Express 6.0 Specification Overview | PDF - Scribd
The 6.0 revision shifts from traditional binary signaling to more complex modulation and packet management to achieve its performance goals: