Does the A-PHY specification cover communication link requirements (e.g., s-parameters)?

All the communication link requirements are covered within the A-PHY specification (e.g., return loss, insertion loss, etc.). There is a clear definition for the channel, with the parameters required to design transmitters and end receivers for MIPI A-PHY.

Note: A channel model for simulation is available that can be used by MIPI members for validation.