Chapter 2 - MAC & PHY

Layer 2 - The Data Link Layer has two sublayers

• Logical Link Control sublayer - Shared sublayer across all 802 standards
• Medium Access Control sublayer

Layer 1 - Physical Layer is often abbreviated as PHY - Also divided into two sublayers

• Physical Medium Dependent (PMD)
• Physical Layer Convergence Protocol (PLCP)

Carpenter, Tom. CWAP: Certified Wireless Analysis Professional: Official study guide: Edition CWAP-402. Certitrek Publishing, 2016.

PMD and PLCP

PMD - Physical Medium Dependent - This is where the data is actually modulated. You can remember that because if you look at the name, its Dependent on the Physical Medium. At least if you read it backwards.

• The 802.11 standard states that every PHY provide different PMDs. The majority of these different PMDs are the modulation schemes.
• The MAC layer remains the same for most of the current PHY's deployed today. Although some will have special features. Such as protection mechanisms or optional features like QoS.

PLCP - Acts as a mediator and/or translator between the MAC layer(s) and the PMD.