IEEE 802.11ba

4Physical Layer Description

4.1 Introduction

The physical (PHY) layer specifies the waveform that is transmitted over the wireless medium. The wireless medium is the airwaves. At the transmitter, the PHY layer receives the physical layer service unit (PSDU), which comes from the medium access control (MAC) layer, which is right above the PHY layer in the protocol stack. The output of the PHY layer is called the PHY protocol data unit (PPDU). So, the job of the PHY layer at the transmitter is to convert the PSDU into the PPDU. The input to the PHY layer at the receiver is the received PPDU which the PHY layer processes and converts to the PSDU, which it sends up to the MAC layer within the receiver. The PPDU, which is sent over the wireless medium, is sometimes casually referred to as the PHY “packet.”

The standard specifies the details of how the PHY at the transmitter converts the PSDU into the PPDU to be sent over the wireless medium. Typically, the standard does not specify how the receiver processes the received PPDU to produce the PSDU. How this is done at the receiver is considered to be “implementation specific” and outside the scope of the standard. When developing the standard, the engineers often consider possible ways the receiver might be implemented, but a specific implementation is left up to the implementor.

The standard specifies how to construct the PPDU in sufficient detail so that different vendors can design and build transmitters and receivers that can ...