The main user-level feature provided bythat L1.5 for users is to allow the bandwidth of a UniPro link to be increased by using 2, 3 or 4 lanes when a single lane does not provide enough bandwidth. To the user, such a multi-lane link simply looks like a faster physical layer because the sybols are sent across 2, 3 or 4 lanes in parallel. Applications that require very high bandwidth in one direction but require less bandwidth in the opposite direction, can have multiple lanes in the high bandwidth direction and a single lane in the other direction.
Architecturally, the PHY Adapter layer also serves to hide the differences between the alternativedifferent PHY technologiesoptions (D- and M-PHY). This abstraction thus mainly gives architectural flexibility. Abstracted PHY details include the various power states and employed symbol encoding schemes.
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