2.4 GHz Wi-Fi Protocol Guide: 802.11b/g/n/ax Diagnostics

Core Technical Specifications

center Freq 2.412–2.472 GHz (Channels 1–13)

modulation DSSS (11b) / OFDM (11g/n/ax) / OFDMA (11ax)

data Encoding CCK, 64-QAM, 256-QAM (11n), 1024-QAM (11ax)

operating Range 30–100 m indoor, 100–300 m outdoor

antenna PCB trace, ceramic chip, or external dipole

tx Power ≤ 100 mW EIRP (EU) / ≤ 1 W EIRP (US)

bandwidth 20 MHz / 40 MHz (HT40)

channel Spacing 5 MHz (only ch 1, 6, 11 non-overlapping)

Real-World Devices & Applications

IoT & Smart Home

ESP8266 / ESP32 IoT devices
Smart plugs, bulbs, cameras (Tuya, TP-Link, Shelly)
Voice assistants (Alexa, Google Home)
Smart TVs and streaming devices

Networking

Wi-Fi access points and routers
Mesh networking systems (Eero, Google Nest)
Wi-Fi range extenders / repeaters

Reference Circuits & Schematics

ESP8266 / ESP32 Wi-Fi Module

The most popular Wi-Fi MCUs for IoT with full TCP/IP stack and radio on-chip.

Pin	Description
`VIN / 3.3V`	5V via USB or 3.3V regulated
`GND`	Ground
`GPIO0`	Boot mode (LOW=flash, HIGH=run)
`TX/RX`	UART for programming and debug
`ANT`	On-board PCB or u.FL for external

Circuit Walk-Through

The ESP connects to Wi-Fi using SSID/password in firmware. Operates as STA, AP, or both. GPIO pins interface sensors/actuators while Wi-Fi stack handles TCP/UDP/MQTT.

Signal Structure & Waveform Analysis

2.4 GHz Channel Layout

14 channels (13 common), each 22 MHz wide with 5 MHz spacing causing overlap.

Channel 1

2.412 GHz

Non-overlapping with 6, 11

Channel 6

2.437 GHz

Non-overlapping with 1, 11

Channel 11

2.462 GHz

Non-overlapping with 1, 6

Channel 13

2.472 GHz

EU/JP only, overlaps with 11

Timing Notes: Deploy on channels 1, 6, or 11 for minimal co-channel interference. 802.11n HT40 uses 40 MHz — only feasible in uncrowded environments. Wi-Fi 6 adds OFDMA for multi-client channel sharing.

Analysis & Capture Tips

Wi-Fi Analyser app to scan channels and identify congestion
Wireshark filter wlan.fc.type_subtype == 0x000c for deauth frames
Check HT40 vs HT20 — HT40 in crowded areas causes harm
ESP: WiFi.RSSI() below −75 dBm = weak signal

Bench Troubleshooting & Repair Guide

1. Channel Congestion

Wi-Fi Analyser / inSSIDer

Use Wi-Fi analyser to scan all channels. Move to least-congested non-overlapping channel (1, 6, or 11). In dense environments, force 20 MHz bandwidth.

2. ESP Connectivity Issues

Serial Monitor / RSSI logging

Check: correct SSID/password, 2.4 GHz network (ESP8266 doesn’t support 5 GHz), no MAC filter, RSSI > −70 dBm. Add WiFi.setAutoReconnect(true).

3. Deauth Attack Detection

Wireshark / Kismet

Sudden disconnections suggest deauth attack. Capture with Wireshark for deauth frames (reason code 7). Enable 802.11w PMF if supported.

2.4 GHz Wi-Fi