1110  Sigfox Introduction and Basics

1110.1 Introduction

⏱️ ~10 min | ⭐⭐ Intermediate | 📋 P09.C10.U01

Sigfox is both a proprietary LPWAN technology and the name of the French company that developed and operates it. Unlike other LPWAN technologies where you can deploy your own network, Sigfox operates as a network operator providing connectivity services globally. Sigfox pioneered the concept of ultra-narrow band (UNB) modulation for IoT, enabling billions of low-power devices to communicate with minimal infrastructure and energy consumption.

NoteLearning Objectives

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

• Understand Sigfox’s ultra-narrow band (UNB) technology
• Explain the Sigfox network architecture and business model
• Compare Sigfox with LoRaWAN for different deployment scenarios
• Evaluate Sigfox suitability for different IoT applications
• Understand the 12-byte payload and 140 message/day constraints

NoteKey Takeaway

In one sentence: Sigfox is an ultra-low-power, operator-managed LPWAN that sends tiny messages (12 bytes) over extreme distances with no local infrastructure required.

Remember this rule: Choose Sigfox over LoRaWAN when you need global coverage without building infrastructure, only send small infrequent messages (<140/day), and can accept the operator’s coverage footprint; choose LoRaWAN when you need network control, larger payloads, or coverage in areas Sigfox doesn’t reach.

1110.2 Prerequisites

Before diving into this chapter, you should be familiar with:

• LPWAN Fundamentals: Understanding low-power wide-area network characteristics and trade-offs provides essential context for Sigfox’s design decisions and positioning
• Networking Basics: Familiarity with wireless communication concepts, modulation schemes, and network topologies helps you understand Sigfox’s ultra-narrow band technology
• LoRaWAN Fundamentals: Knowledge of alternative LPWAN technologies like LoRaWAN enables meaningful comparisons of deployment models, message limits, and coverage approaches
• Wireless Sensor Networks: Understanding battery-powered sensor constraints and long-range communication needs explains why Sigfox targets specific IoT use cases

1110.3 Getting Started (For Beginners)

TipNew to Sigfox? Start Here!

If terms like “ultra-narrow band,” “uplink-only,” or “140 messages/day” sound confusing, this section will explain Sigfox’s unique approach with a simple analogy.

1110.3.1 What is Sigfox? (Simple Explanation)

Analogy: Think of Sigfox like a telegram service for IoT - tiny messages sent over huge distances, ultra-reliable, and incredibly cheap.

REGULAR CELLULAR (4G/5G)         SIGFOX
━━━━━━━━━━━━━━━━━━━━━━           ━━━━━━
📱 → 📶 → 🌐                      📟 → 📶 → ☁️
• Send texts, calls, video        • Send tiny messages (12 bytes)
• High data, high cost            • Very low data, very low cost
• Monthly subscription            • $1-2/device/year
• Need SIM card                   • Simple radio chip

Like comparing:
📧 Email (any size, any time)     ✉️ Postcard (small, limited)

Key Terms Explained:

Term	Simple Explanation
UNB (Ultra Narrow Band)	Radio signal squeezed into extremely thin channel - like using a laser pointer vs flashlight
Uplink	Message from device to cloud (140 messages/day allowed)
Downlink	Message from cloud to device (only 4 messages/day - very limited!)
Base Station	Sigfox tower that receives messages - you don’t build these, Sigfox does

Why This Matters: - Coverage in 75+ countries without you building a single tower - Simplest LPWAN deployment - just buy devices and they work (if coverage exists) - 10-20 year battery life means “install and forget”

1110.3.2 What Makes Sigfox Different from LoRaWAN?

Feature	Sigfox	LoRaWAN
Network ownership	Sigfox operates it (like AT&T)	You can build your own
Messages per day	Limited to 140 uplink	Unlimited (fair use)
Downlink messages	Only 4/day	Varies by device class
Coverage	75+ countries (they build towers)	You choose coverage
Payload size	12 bytes max	Up to 242 bytes
Cost model	Pay per device/year	Pay for infrastructure
Range	10-50 km (rural), 3-10 km (urban)	2-15 km (similar)
Power	10-20 year battery life	5-15 year battery life

{
  const container = document.getElementById('kc-sigfox-1');
  if (container && typeof InlineKnowledgeCheck !== 'undefined') {
    container.innerHTML = '';
    container.appendChild(InlineKnowledgeCheck.create({
      question: "A startup wants to deploy IoT sensors in rural Kenya where there's no existing IoT infrastructure. They need to send 100-byte sensor readings twice daily. Which technology decision is most appropriate?",
      options: [
        {text: "Choose Sigfox because it's cheaper per device", correct: false, feedback: "Sigfox requires existing operator coverage. If Kenya lacks Sigfox infrastructure, your devices simply won't connect regardless of cost savings."},
        {text: "Choose LoRaWAN because you can deploy your own gateways and handle larger payloads", correct: true, feedback: "Correct! LoRaWAN lets you build your own network with gateways ($200-1,500 each) and supports payloads up to 242 bytes. Sigfox is limited to 12 bytes and requires operator infrastructure you cannot deploy."},
        {text: "Choose Sigfox because it has global coverage in 75+ countries", correct: false, feedback: "While Sigfox operates in 75+ countries, coverage varies dramatically by region. Rural Kenya likely has no coverage, and you CANNOT deploy your own Sigfox base stations."},
        {text: "Choose either technology since both support 100-byte payloads", correct: false, feedback: "Sigfox is limited to 12 bytes per message - it cannot send 100 bytes in a single transmission. You'd need multiple messages which quickly exceeds daily limits."}
      ],
      difficulty: "medium",
      topic: "sigfox-vs-lorawan"
    }));
  }
}

1110.3.3 When to Use Sigfox

NoteAcademic Resource: Stanford IoT Course - Smart Agriculture Evolution

Evolution of precision agriculture showing how LPWAN enables connected farming

Source: Stanford University IoT Course - This diagram illustrates the evolution of precision agriculture and how LPWAN technologies like Sigfox enable the “Future” scenario where distributed sensors (weather stations, plant sensors, UAVs) communicate over long ranges to provide integrated data insights. Sigfox’s 10-50 km range and 10+ year battery life make it ideal for agricultural deployments where sensors are spread across large farms.

Perfect for: - Asset tracking (where is my shipping container?) - Simple sensors (parking spot occupied? yes/no) - Utility meters (monthly water reading) - Environmental monitoring (temperature once per hour) - Global deployments (single subscription works across countries)

NOT suitable for: - Real-time control (too slow, limited downlinks) - Large data (12-byte limit) - Frequent updates (140/day max) - Private networks (you can’t run your own Sigfox) - Areas without Sigfox coverage (operator dependency)

1110.3.4 The 12-Byte Challenge

Sigfox messages are tiny—only 12 bytes! Here’s what you can fit:

12 BYTES = What Can You Send?
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
✅ Temperature + Humidity + Battery: 6 bytes
✅ GPS coordinates (lat/long):       8 bytes
✅ Door status + timestamp:          5 bytes
✅ Water meter reading:              4 bytes

❌ Photo:                          ~100,000 bytes (impossible!)
❌ Audio clip:                     ~50,000 bytes (impossible!)
❌ Detailed log:                   ~500 bytes (too big)

Design Tip: You need to get creative with data encoding. Use integers instead of floats, pack multiple values into single bytes, send only changes (deltas) instead of absolute values.

{
  const container = document.getElementById('kc-sigfox-2');
  if (container && typeof InlineKnowledgeCheck !== 'undefined') {
    container.innerHTML = '';
    container.appendChild(InlineKnowledgeCheck.create({
      question: "You're designing a Sigfox-based soil sensor that needs to transmit: soil moisture (0-100%), temperature (-40 to 60C), soil pH (0-14), and a 4-byte device ID. Can you fit this in a single Sigfox message?",
      options: [
        {text: "No - this requires at least 16 bytes which exceeds the 12-byte limit", correct: false, feedback: "Let's calculate: moisture (1 byte), temperature (1 byte as signed int), pH (1 byte scaled x10), device ID (4 bytes) = 7 bytes total. This fits easily!"},
        {text: "Yes - with efficient encoding this fits in about 7 bytes, leaving room for battery status", correct: true, feedback: "Correct! Moisture: 1 byte (0-100). Temperature: 1 byte (-128 to 127 covers -40 to 60). pH: 1 byte (0-140 for 0.0-14.0 with 0.1 resolution). Device ID: 4 bytes. Total: 7 bytes with 5 bytes spare for battery, timestamp, or flags!"},
        {text: "Yes - but only if you remove the device ID to save space", correct: false, feedback: "Device IDs are important for identifying which sensor sent the data, but with proper encoding you can fit everything. The key is using 1 byte per measurement instead of floats."},
        {text: "No - temperature requires 4 bytes as a float to maintain precision", correct: false, feedback: "For agricultural sensors, 1-degree precision is sufficient. A signed byte (-128 to 127) easily covers the -40 to 60C range. Floats waste precious payload space."}
      ],
      difficulty: "medium",
      topic: "sigfox-payload"
    }));
  }
}

1110.3.5 Self-Check: Understanding the Basics

Before continuing, make sure you can answer:

1. What is Sigfox’s main advantage? → Very low cost ($1-2/device/year), global coverage without building your own network, simplest deployment
2. Why only 12 bytes? → Ultra-narrow band modulation (100 Hz channels) trades data size for extreme range and low power
3. When would you choose Sigfox over LoRaWAN? → When you want global coverage without infrastructure investment, only need tiny infrequent messages, and have operator coverage in your area
4. What’s the downlink limitation? → Only 4 downlink messages per day per device - mostly one-way communication, use sparingly

1110.4 In Plain English: Sigfox Explained

TipThink of Sigfox as Sending Postcards Instead of Emails

Imagine you’re traveling the world and want to update your family about your location:

Email (like Wi-Fi/Cellular): - Send long messages with photos and videos - Requires finding Wi-Fi or buying expensive data plans - Battery drains quickly from constant connectivity - Can send unlimited messages anytime

Postcard (like Sigfox): - Write a tiny message: “Arrived Paris. Weather nice. -John” - Works everywhere (global postal system) - Extremely cheap ($1-2 per year unlimited) - Limited space (12 bytes = ~12 characters) - Can only send 140 postcards per day - Takes time to deliver (not instant)

Key Insight: Sigfox trades message size and frequency for extreme affordability and simplicity. It’s designed for devices that say “I’m here” or “Temperature: 72°F” - not devices having conversations.

Real-World Translation:

Wi-Fi Smart Home:                Sigfox Smart Sensor:
─────────────────               ───────────────────
🏠 "Camera uploading 4K video"  📟 "Door opened"
💰 $50/month broadband          💰 $1/year total
🔋 Plugged into wall power     🔋 10-year battery
📱 Send gigabytes anytime       📱 Send 12 bytes max, 140×/day

The Genius: For most IoT sensors, you don’t NEED video quality - you just need to know “yes/no” or “current value.” Sigfox strips away everything except the essentials, making it dirt cheap and ultra-reliable.

1110.5 Real-World Example: Concrete Numbers

NoteCase Study: Smart Waste Management in Barcelona

The Challenge: Barcelona needed to monitor 20,000 trash bins across the city to optimize garbage truck routes and reduce fuel costs.

Traditional Approach (Cellular IoT):

Solution: NB-IoT with daily status reports
─────────────────────────────────────────
Cost per bin:
• Hardware: $30 (NB-IoT modem + sensor)
• Subscription: $5/month × 12 = $60/year
• Total 5-year cost: $30 + ($60 × 5) = $330 per bin
• City total: 20,000 bins × $330 = $6,600,000

Message capacity:
• Can send 500+ messages/day
• Each message up to 1600 bytes
• ...but bins only need 1 update/day!

Sigfox Approach (What Barcelona Actually Chose):

Solution: Sigfox with daily fill-level updates
──────────────────────────────────────────────
Cost per bin:
• Hardware: $12 (Sigfox module + ultrasonic sensor)
• Subscription: $1/year (Sigfox annual fee)
• Total 5-year cost: $12 + ($1 × 5) = $17 per bin
• City total: 20,000 bins × $17 = $340,000

Message breakdown:
• Daily message: Fill level (1 byte) + GPS (6 bytes)
                 + battery (1 byte) + bin ID (2 bytes)
                 + timestamp (2 bytes) = 12 bytes ✓
• Frequency: 1 message/day = 30 messages/month
• Within limit: 140 messages/day max ✓✓
• Downlink use: Emergency requests only (4/day available)

Results After 3 Years: - Cost savings: $6.26M vs $340K = $5.92M saved (95% reduction) - Fuel savings: 30% reduction in truck routes (optimized pickup) - Efficiency: Bins emptied when 80%+ full (not on fixed schedule) - Battery life: 8-10 years per sensor (no maintenance) - Coverage: 99.7% message delivery rate in urban environment

Why Sigfox Was Perfect: 1. Tiny payloads (12 bytes sufficient for “bin 45% full”) 2. Infrequent updates (once per day, not real-time) 3. Massive deployment (20,000 devices = subscription savings) 4. Existing coverage (Sigfox already deployed in Barcelona) 5. Long battery life (10+ years = minimal maintenance)

The Lesson: When your IoT application needs tiny messages sent infrequently across many devices, Sigfox can deliver 95% cost savings compared to cellular alternatives.

{
  const container = document.getElementById('kc-sigfox-3');
  if (container && typeof InlineKnowledgeCheck !== 'undefined') {
    container.innerHTML = '';
    container.appendChild(InlineKnowledgeCheck.create({
      question: "Barcelona's waste management system sends one 12-byte message per day from 20,000 trash bins. A competing city wants to add real-time alerts when bins are vandalized (estimated 50 alerts per day across all bins). Is Sigfox still suitable?",
      options: [
        {text: "No - 50 extra messages exceeds Sigfox's daily limit", correct: false, feedback: "The 140 message/day limit is PER DEVICE. 50 alerts spread across 20,000 bins means each bin sends at most 1-2 vandalism alerts per year, well within limits."},
        {text: "Yes - 50 alerts distributed across 20,000 bins adds negligible load per device", correct: true, feedback: "Correct! 50 daily alerts across 20,000 bins = 0.0025 alerts/bin/day average. Combined with the 1 daily reading, each bin uses ~1.003 messages/day - far below the 140 limit. Sigfox handles this easily."},
        {text: "No - vandalism alerts require faster than Sigfox's 30-90 second latency", correct: false, feedback: "While Sigfox has higher latency than cellular, 30-90 seconds is acceptable for vandalism alerts. You're not trying to catch the vandal in real-time - just log the incident."},
        {text: "Yes - but only if you upgrade to Sigfox's premium real-time tier", correct: false, feedback: "Sigfox doesn't have tier-based latency options. The 30-90 second latency is inherent to the UNB technology and applies to all subscriptions."}
      ],
      difficulty: "medium",
      topic: "sigfox-message-limits"
    }));
  }
}

Network Architecture

Sigfox Network Architecture

UNB Technology

Sigfox UNB Modulation

Message Flow

Sigfox Message Flow

Figure 1110.1: Sigfox network architecture and ultra-narrow band technology

1110.6 Summary

This chapter introduced Sigfox’s fundamental concepts and positioning as an operator-managed LPWAN:

• Sigfox is a network service, not just a technology - you cannot deploy your own infrastructure
• Ultra-low cost ($1-2/device/year) with extreme simplicity (no gateway setup)
• 12-byte payload limit requires efficient data encoding strategies
• 140 uplink + 4 downlink messages/day suits infrequent sensor data, not real-time applications
• Coverage dependency - must verify operator coverage exists before deployment
• Ideal for: simple sensors, asset tracking, utility metering in covered areas

1110.7 What’s Next

Continue learning about Sigfox with these related chapters:

• Sigfox Scenarios and Common Mistakes - Learn what happens when requirements don’t match Sigfox’s constraints
• Sigfox Technology Deep Dive - Understand UNB modulation and network architecture
• Sigfox Examples and Assessment - Worked examples and knowledge checks
• Sigfox Advanced Topics - Deep dive into implementation details