843  Wi-Fi Architecture and Mesh

843.1 Overview

This chapter has been split into focused modules for easier learning. Wi-Fi architecture choices - infrastructure mode, Wi-Fi Direct, or mesh networking - fundamentally determine coverage, complexity, and power requirements for IoT deployments.

NoteKey Takeaway

In one sentence: Wi-Fi mesh networks extend coverage through multi-hop routing and self-healing topology, making Wi-Fi viable for large-scale IoT deployments beyond single access point range.

Remember this rule: Use infrastructure mode for simple deployments, Wi-Fi Direct for temporary peer-to-peer connections without routers, and mesh for whole-building coverage with seamless roaming.

843.2 Chapter Modules

This topic is covered in four focused chapters:

843.2.1 Wi-Fi Architecture Fundamentals

Difficulty: Beginner | Time: ~20 minutes

Learn the three main Wi-Fi architecture modes and when to use each:

  • Infrastructure Mode: Star topology with central access point - most common for home/office IoT
  • Wi-Fi Direct: Peer-to-peer connections without router - useful for provisioning and temporary links
  • Mesh Networks: Multi-hop topology with self-healing - extends coverage for large areas
  • Hidden Terminal Problem: Why sensors canโ€™t always hear each other and how RTS/CTS helps

843.2.2 Wi-Fi Mesh Lab and Self-Healing

Difficulty: Intermediate | Time: ~30 minutes

Hands-on ESP32 mesh implementation with interactive challenges:

  • painlessMesh Setup: Configure multi-node mesh networks with Arduino
  • Self-Healing Demo: Test automatic rerouting when nodes fail
  • Hop Count Analysis: Understand latency and bandwidth impact of multi-hop
  • Root Node Selection: Choose appropriate power sources for mesh gateways
  • Interactive Challenges: Four scenario-based exercises with solutions

843.2.3 Wi-Fi MAC Layer and IoT Applications

Difficulty: Intermediate | Time: ~20 minutes

Channel access mechanisms and real-world IoT use cases:

  • CSMA/CA: Carrier sense and collision avoidance for shared medium
  • QoS Differentiation: 802.11e traffic priorities (Voice, Video, Best Effort, Background)
  • Smart Home: 2.4 GHz for range, 5 GHz for cameras
  • Industrial IoT: Wi-Fi 6 OFDMA for dense sensor deployments
  • Healthcare: Wi-Fi Direct to smartphone gateways with WPA3 security

843.2.4 Wi-Fi Mesh Design and Exercises

Difficulty: Advanced | Time: ~40 minutes

Deployment best practices with worked examples and hands-on exercises:

  • Common Pitfalls: Node placement, backhaul capacity, battery power mistakes
  • Roaming Configuration: 802.11k/r/v setup for mobile robots
  • Backhaul Planning: Camera bandwidth calculations for tri-band mesh
  • Campus Design: Multi-building mesh with redundant paths
  • Practice Exercises: Mesh setup, hidden terminal analysis, roaming optimization

843.3 Learning Path

Recommended order:

  1. Start with Fundamentals for architecture concepts
  2. Complete the Mesh Lab for hands-on experience
  3. Review MAC and Applications for channel access and use cases
  4. Apply knowledge with Design and Exercises

843.4 Prerequisites

Before starting these chapters, you should be familiar with:

843.6 Whatโ€™s Next

Continue to Wi-Fi Architecture Fundamentals to learn about infrastructure mode, Wi-Fi Direct, and mesh networking concepts.