What are the principal features of the A-PHY physical layer?

A-PHY layer has the following features and functions:

• Unified structure to reduce complexity
• Shared 8B/10B Physical Coding Sublayer (PCS) for speed Gear 1 and 2 and uplink channel.
• Retransmission (RTS) sublayer (local retransmission mechanism):
  
  • Manage data packing and buffering
  • Assign message counter (MC) and CRC (Cyclic Redundancy Check)
  • In Profile 2: the retransmission process for A-Packets that are erroneous or that are not received
• Physical Coding Sublayer (PCS):
  
  • Specifies the conversion of Data Link Layer A-Packets into PHY symbols
  • In Profile 2, PCS also handles the Just In Time Canceller (JITC) retraining
• Physical Media Dependent (PMD) sublayer:
  
  • Defines the electrical specifications and the physical medium