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Wireless Connectivity

For the sake of convenience, we use WiFi connectivity, a WiFi Access Point is available everywhere and we can even use our mobile phone in tethering, however:

Warning

WiFi is not appropriate for IoT connectivity since it is power demanding

The selection of the most appropriate wireless connectivity technology depends mostly on the application requirements and it is usually a tradeoff among energy, data throughput, coverage and cost.

The following table compares different wireless technologies. WiFi has the highest figures in terms of energy consumptions.

https://www.emnify.com/blog/iot-connectivity

In our experiments, we us LoRaWAN. In particular, we have a Gateway connected to The Thing Network (TTN).

Heltec, produces a nice device, the WiFi LoRa 32(V3), that we use in our experiments.

A simple code to establish a first connection si available here.

It is basically the ttn-otaa example available in the rgot-org/TTN_esp32 library.

Ad-hoc networking

1️⃣ ESP-NOW (ESP32 Proprietary, Peer-to-Peer Mesh)

https://github.com/espressif/esp-now/tree/master

A low-latency, connectionless, peer-to-peer protocol developed by Espressif. It allows multiple ESP32 devices to communicate directly without Wi-Fi infrastructure. Supports broadcast and unicast messages.

  • Features:

    • Low-power, fast transmission.
    • Multi-hop is possible with custom routing logic.
    • Can coexist with Wi-Fi AP/STA modes.

  • Arduino Implementation:

    • esp_now.h library included in Arduino-ESP32 framework.
    • Simple example for sending sensor data across nodes: each node knows neighbors and relays messages.

Pros: Very fast, low-power, native to ESP32.
Cons: Multi-hop requires you to implement your own routing; no automatic self-organization.

2️⃣ painlessMesh

https://gitlab.com/painlessMesh/painlessMesh

An open-source mesh networking library for ESP8266/ESP32 using Arduino framework. Implements self-organizing, multi-hop mesh out-of-the-box.

  • Features:

    • Each node discovers neighbors automatically.
    • Multi-hop routing included.
    • Messages propagate reliably across mesh.
    • Supports dynamic nodes joining/leaving.

  • Arduino Implementation:

    • Install the painlessMesh library from Arduino Library Manager.
    • Example usage: mesh.sendBroadcast("Hello World");

Pros: Full multi-hop, self-healing mesh, easy to integrate.
Cons: Limited to local area (Wi-Fi range ~100–200 m per hop), message size constraints (~1000 bytes).

3️⃣ ESP-MESH (Espressif Official Wi-Fi Mesh)

Espressif’s official Wi-Fi mesh protocol. Fully multi-hop and self-organizing. Designed for large-scale ESP32 networks.

  • Features:

    • Dynamic routing and node discovery.
    • Supports up to hundreds of nodes.
    • Compatible with standard Wi-Fi devices at the root (bridge to AP).

  • Arduino Implementation:

    • ESP-IDF has full support; Arduino-ESP32 includes esp_mesh.h examples.
    • Example: mesh.init() initializes the mesh, nodes auto-connect.

Pros: Scales well, official support, self-healing.
Cons: Slightly higher memory footprint, more complex API than painlessMesh.

4️⃣ Custom Multi-Hop Protocols Using Wi-Fi Ad-Hoc Mode

ESP32 supports Wi-Fi Station + Soft-AP mode, which allows you to implement ad-hoc networks manually. Each node can act as a relay.

  • Implementation Ideas:

    • Each node maintains a neighbor table.
    • Implement a simple routing protocol like flooding, AODV, or OLSR-lite.
    • Use Arduino Wi-Fi libraries (WiFi.h) for communication.
    • Pros: Full flexibility; can implement experimental protocols.
    • Cons: You must implement routing, discovery, retries manually.

🔹 Comparison Table

Protocol / Library Multi-Hop Self-Organizing Arduino Support Ease of Use Best Use Case
ESP-NOW Optional (manual) No Yes (esp_now.h) Easy Low-latency peer-to-peer
painlessMesh Yes Yes Yes (Library) Easy Small-to-medium mesh networks
ESP-MESH Yes Yes Yes (Arduino wrapper) Medium Large-scale, self-healing mesh
Custom Wi-Fi Ad-hoc Yes Yes (if implemented) Yes Hard Research / experimental protocols

💡 Tip:
For most IoT courses or projects on ESP32, painlessMesh is the easiest way to teach true multi-hop, self-organizing networks in Arduino. ESP-MESH is more production-ready but heavier.