Notes for Hungry Minds:
1. Wi-Fi channels in the 5 GHz band are not assigned in strict increments of 1. In this band, channel numbers don't always follow a strict sequential pattern for every 5 MHz increment in the spectrum. Instead, they are assigned based on 20 MHz channel spacing (for standard use).
Channels like 101, 103 are not valid Wi-Fi channels because their center frequencies (e.g., 5505 MHz etc.) are not standardized. They might exist in theoretical or experimental configurations (e.g., in SDR or military systems), but they are not part of the IEEE 802.11 Wi-Fi standard. This is a common point of confusion because the underlying spectrum is continuous, but the Wi-Fi standards define discrete channels at specific center frequencies and widths.

2. The channels 36, 40, 44, and 48 are often considered the "core" or primary non-DFS channels in the U-NII-1 band. These are almost universally supported by all 5 GHz Wi-Fi devices globally. This may be because Early 5 GHz Wi-Fi deployments and chipsets may have focused on a more limited set of channels, and 36-48 became the de facto standard for the lower band. As technology evolved, new channels were added, but 32 might have been an "edge case" in some earlier implementations.
Channel 32 (5160 MHz) is at the very lower edge of the 5150-5250 MHz U-NII-1 band. While it's within the allowed range, operating very close to the band edge can sometimes introduce more complex filtering or power spectral density requirements for manufacturers to ensure emissions don't spill into adjacent restricted bands.

3. How Wi-Fi Devices Check for Radar Pulses for DFS In India, the regulatory body for wireless communications is the Wireless Planning and Coordination (WPC) Wing of the Department of Telecommunications (DoT). For Dynamic Frequency Selection (DFS) in the 5 GHz band, India largely aligns its regulations with international standards, particularly those established by the ETSI (European Telecommunications Standards Institute) and the IEEE 802.11h standard, which specifies DFS functionality for Wi-Fi devices. I shall write a separate article on DFS.