[Cross_Layer] What is a notion?

Notion::

The existing networks layer consists of OSI 7 layers. The rule is, each layer work independent.

The Cross layer, however, even break the rules of such a hierarchy, a independent property of OSI 7.

That is, the cross layer means that specific information send to a non-adjacent layer, or shared variables to share In 

order to improve the efficiency in communication,

Why need::

It help the wireless communication that based on a existing OSI 7 layer,  to improve about efficiency. Because the 

wireless communication is not good in existing OSI 7 layer.

2 problems::

1) small scale channel variations

2) Large-scale channel variation

Therefore, we need a another architecture for wireless communication compared with OSI 7 layers.