Exploring the Physical Layers in IEEE 802.11 WLAN Standards

In this lecture, we will delve into the physical layers defined in the IEEE 802.11 standard for wireless local area networks (WLAN). We will explore the various physical layers utilized in WLAN, focusing specifically on the IEEE 802.11-2020 standard. This standard outlines the physical characteristics that dictate data rates, channel widths, and frequency bands used in wireless communication.

Overview of IEEE 802.11-2020

The IEEE 802.11-2020 standard serves as a critical framework for WLAN technology, detailing the physical and data link layers responsible for wireless connectivity. The physical layers encompass essential factors such as modulation techniques, coding schemes, channel widths, and frequency usage. These elements collectively determine the performance and capabilities of a wireless network.

Impact of Channel Width and Modulation on Data Rates

Channel width and modulation are significant determinants of data rates in WLANs. As previously discussed regarding the Modulation and Coding Scheme (MCS) index, these factors contribute to the throughput experienced in wireless communication. Channel width refers to the amount of spectrum allocated for a specific communication channel. For instance, a standard 20 MHz channel can be combined with another to create a 40 MHz channel, enhancing throughput. However, it is crucial to note that wider channels may lead to reduced coverage.

Throughout this lecture, we will examine the different physical layers, including their respective channel widths, modulation techniques, and data rates.

Let’s begin with an in-depth analysis of each physical layer.

1. Direct Sequence Spread Spectrum (DSSS)

DSSS is one of the earliest physical layers defined in the 802.11 standard and continues to be supported in modern devices. Operating exclusively on the 2.4 GHz frequency band, DSSS employs a channel width of 22 MHz. This approach allows for the transmission of data over a defined frequency range.

In a DSSS configuration, a single spatial stream is used, meaning that only one antenna is required for both transmission and reception. This design limits data throughput to 1 and 2 megabits per second, making it relatively slow compared to newer standards. It is important to remember the key parameters of DSSS: