840  Wi-Fi for IoT: Overview and Introduction

Prerequisites: Mobile Wireless Basics | Networking Fundamentals

This enables: Wi-Fi Standards Evolution | Wi-Fi Security

840.1 Learning Objectives

By the end of this chapter series, you should be able to:

  • Understand Wi-Fi standards (802.11 b/g/n/ac/ax) and their IoT applications
  • Configure ESP32 and Raspberry Pi for Wi-Fi connectivity
  • Implement Wi-Fi security protocols (WPA2/WPA3) for IoT devices
  • Design Wi-Fi mesh networks for extended coverage
  • Optimize Wi-Fi for low-power IoT applications
  • Troubleshoot common Wi-Fi connectivity issues
  • Compare Wi-Fi with other IoT wireless technologies
  • Implement Wi-Fi provisioning and device onboarding

840.2 Wi-Fi for IoT

TipIn Plain English

Wi-Fi is the wireless technology you use every day for internet. For IoT, it offers high bandwidth and easy integration - but uses more power than protocols like Zigbee or BLE. Best for devices that are plugged in or need to send lots of data.

Everyday Analogy: Wi-Fi is like a highway - fast and carries lots of traffic, but takes more fuel (power) than a small country road (BLE).

When to use Wi-Fi for IoT: - Device needs video/audio streaming (security cameras, smart displays) - You already have Wi-Fi infrastructure at home/office - Device is plugged into wall power (not battery) - Needs direct internet access without a hub

When NOT to use Wi-Fi: - Battery-powered sensor that needs to last years - Tiny amounts of data (like temperature readings) - Very long range (kilometers, not meters) - High-density deployments without careful planning (e.g., hundreds of devices on a consumer router/AP)

NoteKey Takeaway

In one sentence: Wi-Fi offers the highest bandwidth for IoT but at the cost of power consumption, making it ideal for plugged-in devices that need video, audio, or direct internet access.

Remember this rule: Use Wi-Fi when devices are mains-powered and need high throughput or existing infrastructure; use BLE/Zigbee/LoRaWAN for battery-powered sensors where power efficiency matters more than speed.

840.3 What is Wi-Fi?

Wi-Fi is a family of wireless networking standards (IEEE 802.11). It enables devices to exchange data wirelessly over radio waves, typically in the 2.4 GHz and 5 GHz frequency bands (and 6 GHz for Wi-Fi 6E/7).

NoteWi-Fi Characteristics for IoT
  • Standards: IEEE 802.11 b/g/n/ac/ax (Wi-Fi 4/5/6)
  • Frequency: 2.4 GHz (longer range) and 5 GHz (higher speed)
  • Range: 30-50 meters indoors, up to 100 meters outdoors
  • Data Rate: 1 Mbps to 9.6 Gbps (depending on standard)
  • Power: Medium to high (10-500 mW transmit power)
  • Topology: Star (infrastructure mode) or mesh

840.4 Wi-Fi Chapter Series

This comprehensive guide to Wi-Fi for IoT is organized into focused chapters:

Chapter Topic Key Content
1. Wi-Fi Overview This chapter Introduction, basics, when to use Wi-Fi
2. Wi-Fi Standards Evolution Standards 802.11 b/g/n/ac/ax, Wi-Fi 6 features, HaLow
3. Wi-Fi Frequency Bands Spectrum 2.4/5/6 GHz, channel planning, interference
4. Wi-Fi Power Consumption Battery life TWT, power optimization, protocol comparison
5. Wi-Fi Deployment Planning Implementation Capacity planning, common mistakes, case studies
6. Wi-Fi Certification Reference Compliance Standards, regional requirements, testing
7. Wi-Fi Hands-On Labs Practice Exercises, Wokwi simulator, weather station

840.5 For Kids: Wi-Fi is Like Magic Invisible Roads!

Have you ever wondered how your tablet gets the internet without any wires?

840.5.1 The Invisible Highway

Wi-Fi is like an invisible highway in the air! Just like cars drive on roads to get places, information travels through the air on invisible Wi-Fi signals.

Imagine this: > Your house has invisible roads made of radio waves. When you watch a video on your tablet, tiny packets of information drive super fast on these invisible roads from your router (like a gas station) to your device!

840.5.2 The Wi-Fi Story

Once upon a time, computers needed long cables to talk to each other. It was like having to hold hands with everyone you wanted to talk to - very inconvenient!

Then some smart engineers invented Wi-Fi - magic invisible signals that carry information through the air, just like how voices carry through the air when you talk. Now devices can “talk” without touching!

840.5.3 How Wi-Fi Works (The Singing Analogy)

Think of Wi-Fi like singing:

  1. Your router sings a special song (broadcasts its signal)
  2. Your phone hears the song and knows where to connect
  3. They start talking by taking turns “singing” information back and forth
  4. Really really fast! Millions of “words” per second!

840.5.4 Key Words for Kids

Word What It Means
Wi-Fi Invisible signals that carry internet through the air
Router The box that creates Wi-Fi in your house
Signal The invisible “road” that carries information
Connected When your device can “hear” the Wi-Fi
Password The secret code to use someone’s Wi-Fi

840.5.5 Try This!

Look at the Wi-Fi symbol on your phone or tablet (it looks like curved lines spreading out). The more curved lines you see, the stronger the signal - like being closer to someone who’s singing so you can hear them better!

840.5.6 Signal Sam Says:

“Wi-Fi is my favorite way to send big messages! It’s super fast - like a rocket ship compared to my slow postal service. But remember, it needs a lot of power, so it’s best for devices that are plugged in!”

840.6 Getting Started (For Beginners)

TipWhat is Wi-Fi? (Simple Explanation)

Wi-Fi is a family of wireless networking standards (IEEE 802.11) that uses radio waves to provide high-speed network connectivity without physical cables. Originally designed for laptops and computers, Wi-Fi has become the backbone of smart home connectivity.

The Problem Wi-Fi Solves:

Before Wi-Fi, connecting devices to a network required running Ethernet cables through walls. Wi-Fi eliminates this by using radio frequencies (2.4 GHz and 5 GHz) to transmit data through the air, allowing any device within range to connect wirelessly.

Analogy: Wi-Fi is like wireless ethernet - same high speed as wired connections, but more convenient. However, for IoT sensors, it’s like using a fire hose to fill a teacup - powerful but power-hungry!

840.6.1 Key Wi-Fi Terms Explained

Term What It Means Everyday Example
SSID Network name “Home_Wi-Fi” or “Coffee_Shop_Guest”
AP (Access Point) The “hub” all devices connect to Your Wi-Fi router
Station Any device connecting to Wi-Fi Your phone, laptop, smart bulb
Channel Radio “lane” (like highway lanes) Channel 1, 6, or 11 on 2.4 GHz
Band Frequency range (2.4 GHz or 5 GHz) 2.4 = slower/longer range, 5 = faster/shorter

840.6.2 Hands-on: Connect a Raspberry Pi to Wi-Fi (CLI)

Raspberry Pi OS commonly uses either NetworkManager (newer releases) or wpa_supplicant + dhcpcd (older/minimal images).

Option A: NetworkManager (nmcli)

sudo nmcli dev wifi list
sudo nmcli dev wifi connect "<SSID>" password "<PASSWORD>" ifname wlan0
ip -br a show wlan0
ping -c 3 1.1.1.1

Option B: wpa_supplicant (legacy / minimal installs)

Edit /etc/wpa_supplicant/wpa_supplicant.conf:

country=US
ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev
update_config=1

network={
  ssid="YOUR_SSID"
  psk="YOUR_PASSWORD"
}

Then apply and verify:

sudo wpa_cli -i wlan0 reconfigure
sudo systemctl restart dhcpcd || true
ip -br a show wlan0
iw dev wlan0 link

840.6.3 Hands-on: Connect an ESP32 to Wi-Fi (Arduino)

#include <WiFi.h>

const char* ssid = "YOUR_SSID";
const char* password = "YOUR_PASSWORD";

void setup() {
  Serial.begin(115200);
  WiFi.mode(WIFI_STA);
  WiFi.begin(ssid, password);

  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }

  Serial.println();
  Serial.print("IP address: ");
  Serial.println(WiFi.localIP());
}

void loop() {}

For production devices, avoid hardcoding secrets and use provisioning/onboarding flows (see Wi-Fi Security).

840.7 Why This Matters for IoT

Wi-Fi powers 18+ billion devices worldwide (2025): - High bandwidth: Perfect for cameras (need 5-10 Mbps each) - Ubiquitous: Already in every home and office - Easy setup: Just enter password and connect - Power hungry: 200-300 mA transmit (vs BLE 15 mA) - Battery unfriendly: Most Wi-Fi IoT devices need wall power

%%{init: {'theme': 'base', 'themeVariables': { 'primaryColor': '#2C3E50', 'primaryTextColor': '#fff', 'primaryBorderColor': '#16A085', 'lineColor': '#16A085', 'secondaryColor': '#E67E22', 'tertiaryColor': '#ecf0f1', 'fontSize': '14px'}}}%%
graph LR
    ROUTER[Wi-Fi Router<br/>Access Point]
    PHONE[Smartphone]
    LAPTOP[Laptop]
    CAMERA[Security Camera]
    SENSOR[IoT Sensor]

    ROUTER <-->|2.4 GHz or 5 GHz| PHONE
    ROUTER <-->|Wireless Signals| LAPTOP
    ROUTER <-->|Video Stream| CAMERA
    ROUTER <-->|Telemetry Data| SENSOR

    ROUTER -->|Internet| CLOUD[Cloud/Internet]

    style ROUTER fill:#2C3E50,stroke:#16A085,stroke-width:3px,color:#fff
    style PHONE fill:#16A085,stroke:#2C3E50,stroke-width:2px
    style LAPTOP fill:#16A085,stroke:#2C3E50,stroke-width:2px
    style CAMERA fill:#E67E22,stroke:#2C3E50,stroke-width:2px
    style SENSOR fill:#E67E22,stroke:#2C3E50,stroke-width:2px
    style CLOUD fill:#7F8C8D,stroke:#2C3E50,stroke-width:2px

Figure 840.1: Wi-Fi Infrastructure Mode Network with Access Point and Client Devices

840.8 When to Choose Wi-Fi for IoT

Wi-Fi is ideal when: - High bandwidth needed (cameras, audio, video) - Existing Wi-Fi infrastructure available - Devices are mains-powered or frequently charged - Internet connectivity required - Low latency critical - Easy user setup (familiar to users)

Consider alternatives when: - Ultra-low power required (years on battery) - Very long range needed (>100m) - Very dense networks (hundreds of devices) - Low data rate sensors (<1 kbps)

Scenario Better Choice Why
Battery-powered sensor Zigbee, BLE 10x better battery life
1000+ devices LoRaWAN, Zigbee Wi-Fi routers can’t handle it
Very long range (km) LoRaWAN, Sigfox Wi-Fi only reaches ~100m
Ultra-low latency Thread, Zigbee Mesh networks are faster for local

840.9 Quick Self-Check

  1. Your smart thermostat needs Wi-Fi. Should it use 2.4 GHz or 5 GHz?
    • 2.4 GHz (better range through walls, lower power)
  2. Your security camera streams HD video. Which frequency?
    • 5 GHz (higher bandwidth, less interference)
  3. Why might a temperature sensor choose Zigbee over Wi-Fi?
    • Much better battery life for small, infrequent data

840.10 What’s Next

Continue to Wi-Fi Standards Evolution to learn about 802.11 generations from Wi-Fi 1 to Wi-Fi 7, including the game-changing Wi-Fi 6 features like TWT (Target Wake Time) for battery savings and OFDMA for efficient multi-device communication.

Wi-Fi Deep Dives: - Wi-Fi Standards Evolution - 802.11 generations - Wi-Fi Frequency Bands - Channel planning - Wi-Fi Power Consumption - Battery optimization - Wi-Fi Deployment Planning - Capacity and case studies - Wi-Fi Architecture and Mesh - Network topologies - Wi-Fi Security - WPA3 and provisioning - Wi-Fi IoT Implementations - Practical applications

Wireless Comparisons: - Bluetooth - Low-power personal area networks - Zigbee - Mesh networking alternative - Thread - IP-based mesh

Learning Hubs: - Quiz Navigator - Wi-Fi quizzes - Simulations Hub - Network tools