1096 LoRaWAN Simulation Lab

Prerequisites: LoRaWAN Network Architecture | ADR Optimization

This enables: Practice Exercises | Real hardware deployment

1096.1 Learning Objectives

By completing this lab, you will be able to:

Understand LoRaWAN packet structure: DevAddr, FCnt (frame counter), FPort, and encrypted payload fields
Implement uplink/downlink communication: Simulate Class A receive windows (RX1 and RX2)
Observe spreading factor effects: See how SF7-SF12 affects airtime, range simulation, and throughput
Manage duty cycle compliance: Implement 1% EU868 duty cycle tracking and enforcement
Experience ADR behavior: Watch the network automatically adjust spreading factors based on link quality

1096.2 Why Simulate LoRaWAN?

Real LoRaWAN requires specialized hardware (SX1276/SX1262 radio modules) and licensed spectrum access. This simulation lets you:

Learn protocol mechanics without hardware investment
Visualize packet flow that would be invisible with real radios
Experiment with ADR in seconds instead of hours
Test duty cycle scenarios without regulatory concerns

The simulation accurately models packet structure, timing behaviors, and protocol state machines - the same concepts you will apply with real LoRaWAN hardware.

1096.3 LoRaWAN Concepts Demonstrated

Concept	Real LoRaWAN	This Simulation
Physical Layer	LoRa CSS modulation	ESP-NOW 2.4 GHz
Packet Format	PHYPayload with MHDR, MACPayload, MIC	Identical structure
Spreading Factor	SF7-SF12 radio parameter	Simulated airtime delays
Duty Cycle	1% TX time per hour	Tracked and enforced
ADR	Network server algorithm	Simplified SNR-based
Device Classes	Class A/B/C	Class A implemented
Security	AES-128 encryption	Simulated (visible for learning)

1096.4 Lab Architecture

The simulation creates a LoRaWAN network with three ESP32 devices:

%%{init: {'theme': 'base', 'themeVariables': { 'primaryColor': '#2C3E50', 'primaryTextColor': '#fff', 'primaryBorderColor': '#16A085', 'lineColor': '#E67E22', 'secondaryColor': '#7F8C8D', 'tertiaryColor': '#ECF0F1', 'fontSize': '14px'}}}%%
graph TB
    subgraph EndDevices["End Devices (Class A)"]
        ED1["ESP32 #1<br/>Sensor Node<br/>DevAddr: 0x26011234"]
        ED2["ESP32 #2<br/>Sensor Node<br/>DevAddr: 0x26015678"]
    end

    subgraph Gateway["LoRaWAN Gateway"]
        GW["ESP32 #3<br/>Gateway Simulator<br/>+ Network Server"]
    end

    subgraph NetworkFunctions["Network Server Functions"]
        ADR["ADR Algorithm"]
        DC["Duty Cycle Monitor"]
        DL["Downlink Scheduler"]
    end

    ED1 -->|"Uplink SF7-SF12"| GW
    ED2 -->|"Uplink SF7-SF12"| GW
    GW -->|"RX1/RX2 Downlink"| ED1
    GW -->|"RX1/RX2 Downlink"| ED2
    GW --- ADR
    GW --- DC
    GW --- DL

    style ED1 fill:#16A085,stroke:#2C3E50,stroke-width:2px,color:#fff
    style ED2 fill:#16A085,stroke:#2C3E50,stroke-width:2px,color:#fff
    style GW fill:#E67E22,stroke:#2C3E50,stroke-width:3px,color:#fff
    style ADR fill:#ECF0F1,stroke:#7F8C8D,stroke-width:1px,color:#2C3E50
    style DC fill:#ECF0F1,stroke:#7F8C8D,stroke-width:1px,color:#2C3E50
    style DL fill:#ECF0F1,stroke:#7F8C8D,stroke-width:1px,color:#2C3E50

Figure 1096.1: LoRaWAN simulation architecture with two end devices and a gateway/network server

1096.5 Embedded Wokwi Simulator

How to Use This Simulator

Click the green Play button to start the simulation
Watch the Serial Monitor for detailed LoRaWAN packet logs
Copy the code from the repository to run the full demonstration
Modify spreading factors and observe the airtime changes
Trigger downlinks by pressing the boot button on end devices

Show code

html`<iframe
  src="https://wokwi.com/projects/new/esp32"
  style="width:100%; height:600px; border:2px solid #16A085; border-radius:12px; box-shadow: 0 4px 6px rgba(0,0,0,0.1);"
  allow="accelerometer; ambient-light-sensor; camera; encrypted-media; geolocation; gyroscope; microphone; midi; payment; usb; vr; xr-spatial-tracking"
  sandbox="allow-forms allow-modals allow-popups allow-presentation allow-same-origin allow-scripts"
  loading="lazy"
  title="LoRaWAN Network Simulator">
</iframe>`

1096.6 Lab Challenges

1096.6.1 Challenge 1: Implement Confirmed Uplinks

Modify the end device to send confirmed uplinks and handle ACK responses:

Change MType from 2 (Unconfirmed) to 4 (Confirmed) in uplink frames
Implement ACK timeout and retransmission logic
Track confirmed vs. unconfirmed delivery rates
Observe how confirmed uplinks affect duty cycle budget

1096.6.2 Challenge 2: Add Class B Beacon Simulation

Extend the simulation to support Class B scheduled receive windows:

Gateway broadcasts a beacon every 128 seconds
End device synchronizes to beacon and opens ping slots
Implement ping slot scheduling based on DevAddr hash
Compare downlink latency between Class A and Class B

1096.6.3 Challenge 3: Implement Join Procedure (OTAA)

Add the LoRaWAN join procedure:

Create JoinRequest message with DevEUI and AppEUI
Gateway responds with JoinAccept containing DevAddr and session keys
Derive AppSKey and NwkSKey from AppKey and nonces
Transition from join state to data transmission state

1096.6.4 Challenge 4: Multi-Gateway Reception

Simulate multiple gateways receiving the same uplink:

Add a second gateway node
Both gateways forward uplinks to the “network server”
Implement deduplication logic (keep best RSSI)
Demonstrate how multi-gateway improves reliability

1096.7 Key Concepts Learned

1096.7.1 Concept: DevAddr and Frame Counters

DevAddr (Device Address) is a 4-byte network-assigned identifier: - Assigned during join (OTAA) or pre-configured (ABP) - Used for routing at the network server - Format: 0x26XXXXXX for private networks

Frame Counters (FCnt) prevent replay attacks: - FCntUp: Incremented by device on each uplink - FCntDown: Incremented by network on each downlink - Network rejects packets with out-of-sequence counters

1096.7.2 Concept: Spreading Factor Trade-offs

SF	Airtime (20 bytes)	Range	Sensitivity	Battery Impact
SF7	50 ms	~2 km	-123 dBm	Lowest (1x)
SF8	100 ms	~4 km	-126 dBm	2x
SF9	200 ms	~6 km	-129 dBm	4x
SF10	400 ms	~8 km	-132 dBm	8x
SF11	800 ms	~11 km	-134.5 dBm	16x
SF12	1600 ms	~15 km	-137 dBm	32x

1096.7.3 Concept: Duty Cycle Regulations

EU868 Regulations: - Sub-band g (868.0-868.6 MHz): 1% duty cycle = 36 seconds/hour - Sub-band g1 (868.7-869.2 MHz): 0.1% = 3.6 seconds/hour - Sub-band g3 (869.4-869.65 MHz): 10% = 360 seconds/hour (used for downlinks)

US915 Regulations: No duty cycle limit, but: - 400ms dwell time per channel - Frequency hopping required (>50 channels) - Fair Access Policy recommends 30 seconds/day

1096.7.4 Concept: Adaptive Data Rate (ADR)

How ADR Works: 1. Network server collects SNR/RSSI from last 20 uplinks 2. Calculates link margin above sensitivity threshold 3. If margin > 10 dB, recommends lower SF (faster, less power) 4. Sends LinkADRReq MAC command in downlink 5. Device acknowledges and applies new SF

1096.8 Lab Summary

Exercise	LoRaWAN Concept	What You Learned
Basic transmission	Packet structure	DevAddr, FCnt, FPort, MIC fields
SF modification	Spreading factors	Airtime vs range trade-off
Duty cycle test	Regulatory compliance	EU868 1% limit enforcement
Multi-device	ADR algorithm	Network-optimized SF selection
Challenge 1	Confirmed messages	Reliability with ACK/retry
Challenge 2	Class B	Beacon-synchronized receive
Challenge 3	OTAA	Secure device activation
Challenge 4	Redundancy	Multi-gateway reception

1096.9 Real Hardware Next Steps

After completing this simulation lab, you are ready to work with real LoRaWAN hardware:

Hardware: Get an ESP32 + SX1276/SX1262 module (Heltec WiFi LoRa 32, TTGO LoRa32, or separate module)
Library: Use LMIC (LoRaWAN-in-C) or RadioLib for Arduino
Network: Register with The Things Network (TTN) or Chirpstack
Activation: Use OTAA (more secure) or ABP (simpler for testing)

The packet structures and concepts from this lab translate directly to real deployments - the primary difference is the physical LoRa radio layer.

1096.10 What’s Next

Continue to Practice Exercises to test your understanding of LoRaWAN concepts.

Alternative paths: - LoRaWAN Overview - Return to the chapter index - LoRaWAN Architecture - Deep dive into protocol specifications