Adapting MAC Scheduling Based On PHY Parameters
Communication systems that need to operate over media with non stationary background noise may benefit from having a close coordination between the MAC layer (which is responsible for scheduling transmissions) and the PHY layer (which manages actual transmission and reception of data over the media).
In some communications channels (for example, in power lines), noise may be non-stationary and might vary synchronously with the 50 or 60 Hz AC current cycle. In scenarios like this, overall system performance can be improved if the MAC can get information from the PHY regarding when and how the noise level is changing, so that the MAC can schedule transmission during the periods of time in which noise levels are lower.
An example of a communications system that allows this kind of Cross-layer optimization is the ITU-T G.hn standard, which provides high-speed local area networking over existing home wiring (power lines, phone lines and coaxial cables).
Read more about this topic: Cross-layer Optimization
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