Physical layer architecture

The physical layer is divided into two sublayers. They are the physical layer convergence procedure (PLCP) sublayer and the physical medium dependent (PMD) sublayer. The physical layer logical architecture is illustrated in Figure 11.1.

OSI layer 2: Data link MAC

OSI layer 1: Physical

PLCP

Physical layer logical architecture

The PLCP acts as the binding agent between the medium access control (MAC) frames and the aerial radio transmissions. It adds its own header. Usually, frames make use of a preamble in order to facilitate synchronization of incoming transmissions. The preamble requirements may depend on the modulation method. However, PLCP adds its own header to any transmitted frames. It is the PMDs responsibility for transmitting the bits it receives from the PLCP into the air employing an antenna.

A clear channel assessment (CCA) function is incorporated by the physical layer to indicate to the MAC when a signal is detected.

0 0

Post a comment