IJ
Ivan Jovanovski
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IJ
Ivan Jovanovski

Electrical Engineer building practical solutions in energy systems, automotive electronics, and embedded systems.

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Secure Distributed IoT Sensor Network

LoRaESP32IoTMQTTKafkaAES-128low-power
General

Project Overview

End-to-end telemetry system with LoRa nodes (SX127x), ESP32 gateway, MQTT/Kafka backend, AES-128 encryption, and custom TDMA scheduling for multi-month field operation.

Version:v1.0
Time:~60.0 hours
Cost:~$150
Status:complete

Materials

  • SX127x LoRa Modules × 5
  • ESP32 DevKit × 1
  • STM32/Arduino Sensor Nodes × 4
  • Temperature/Humidity Sensors × 4
  • LiPo Batteries × 4
  • Solar Panels (optional) × 2

Tools

  • Logic Analyzer
  • Oscilloscope
  • RF Spectrum Analyzer (optional)
  • VS Code + PlatformIO

Build Steps

1. LoRa Node Design

⏱️ ~12.0h

Designed sensor nodes with SX127x LoRa modules. Implemented deep-sleep with peripheral clock gating and optimized wake-up intervals for multi-month battery life.

2. ESP32 Gateway

⏱️ ~8.0h

Built ESP32 gateway bridging LoRa uplink traffic to MQTT/Kafka backend. Simple provisioning allows new nodes to be added by deploying and registering in backend.

3. TDMA Scheduling

⏱️ ~6.0h

Implemented lightweight TDMA-like time-slot scheme on top of LoRa's ALOHA MAC to reduce collisions and improve reliability in the 433MHz ISM band.

4. Security Implementation

⏱️ ~5.0h

Secured the full path with AES-128 payload encryption on nodes and SSL/TLS on gateway-backend link, hardening against eavesdropping and message injection.

Results

Reliable multi-node sensor network with months of battery life and secure data transmission.

  • Deep-sleep Current: <10 µA
  • Range: 2+ km
  • Battery Life: 3-6 months

Safety Notes

Ensure compliance with local ISM band regulations (433MHz).