1117 Sigfox Technology Deep Dive

1117.1 Sigfox Technology Overview

1117.1.1 The Company and Vision

Sigfox is a French company founded in 2009 with a vision to connect billions of IoT devices using a dedicated low-power wide-area network. Rather than selling equipment for customers to build their own networks, Sigfox operates as a network service provider—similar to how cellular carriers operate.

Key philosophy:

Software-based solution: Network and computing complexity managed in the cloud
Simple devices: All intelligence in the network, not the endpoints
Global coverage: Single subscription works across countries
Ultra-low cost: Minimal device complexity reduces hardware costs

Table 1117.1

Table: Sigfox Technology Summary

Property	Details
Name	Sigfox
Standard protocol is based on	Ultra Narrow Band (UNB) ISM radio band
Designed for	• Uses Ultra Narrow Band (UNB) to transmit information between low power devices operating at 868 MHz frequency band, that divides the spectrum into 400 of 100 Hz channels
Connection range	30-50 km for rural areas, and 3-10 km for urban areas
Data rate	100bps, with a limit of 140 messages per day for each end device

graph TB
    subgraph "Traditional IoT"
    T1["Complex Device<br/>(Wi-Fi/Cellular)"]
    T2["Local Gateway/<br/>Base Station"]
    T3["Local Processing"]
    T4["Cloud"]
    T1 --> T2 --> T3 --> T4
    end

    subgraph "Sigfox Approach"
    S1["Simple Device<br/>(Sigfox Module)"]
    S2["Sigfox<br/>Base Station"]
    S3["Sigfox Cloud<br/>(All Processing)"]
    S1 --> S2 --> S3
    end

    style T1 fill:#ffe1e1
    style S1 fill:#e1ffe1
    style S3 fill:#e1f5ff

1117.1.2 Ultra-Narrow Band Modulation

Sigfox uses Ultra Narrow Band (UNB) modulation, which is fundamentally different from spread spectrum techniques used by LoRa or frequency hopping used by Bluetooth.

UNB Characteristics: - Extremely narrow channel bandwidth: 100 Hz per channel - Multiple channels across the ISM band - Low data rate: 100 bps uplink, 600 bps downlink - High receiver sensitivity: -126 to -142 dBm - Robust against interference and jamming

Sigfox ultra-narrowband modulation architecture showing 868/902 MHz ISM band (192 kHz total) divided into ~1,920 channels of 100 Hz each. Frequency hopping selects random channel per message. Bandwidth comparison shows Sigfox at 100 Hz (ultra narrow), compared to NB-IoT 180 kHz (1,800× wider), LoRa 125 kHz (1,250× wider), and Wi-Fi 20-40 MHz (200,000-400,000× wider). Ultra-narrow design provides excellent interference resistance, long range through concentrated power density, and enables low-cost receivers.

Comparison with other modulation schemes:

Technology	Bandwidth	Data Rate	Sensitivity
Sigfox (UNB)	100 Hz	100 bps	-142 dBm
LoRa (CSS)	125-500 kHz	250-5,470 bps	-148 dBm
FSK (Cellular)	200 kHz	1-100 kbps	-110 dBm
Wi-Fi (OFDM)	20-40 MHz	1-600 Mbps	-90 dBm

1117.1.3 Sigfox Radio Parameters

The technical specifications of Sigfox’s radio system define its unique operational characteristics and constraints:

Sigfox radio parameters showing regional frequency bands (RC1 Europe 868MHz, RC2 Americas 902MHz, RC3 Asia Pacific 923MHz, RC4 LATAM 920MHz). Uplink specifications: 12-byte payload, 100 bps, DBPSK modulation, 14-27 dBm TX power, -126 dBm sensitivity, 140 messages/day limit. Downlink specifications: 8-byte payload, 600 bps, GFSK modulation, 20-25 second RX window, -142 dBm sensitivity, 4 messages/day limit. Performance: 10-40 km rural range, 3-10 km urban, limited indoor penetration (~20 dB loss), 10-20 year battery life.

Key Constraints to Remember: - Message Limits: 140 uplink + 4 downlink per day (non-negotiable) - Payload Size: 12 bytes uplink, 8 bytes downlink (extremely small) - Data Rate: 100 bps uplink means ~2 seconds per transmission - Downlink Cost: Listening for downlink consumes significant battery (20-25 seconds RX) - Regional Variations: Different frequency bands and regulations per region

1117.1.4 Sigfox vs LoRaWAN: Architectural Comparison

Understanding the fundamental differences between Sigfox and LoRaWAN helps in making informed technology choices:

Sigfox vs LoRaWAN architectural comparison. Sigfox (orange): UNB 100 Hz channels, 12-byte uplink/8-byte downlink payload, 140 uplink/4 downlink daily limit, operator-managed infrastructure (cannot deploy own), $6-10/year subscription with $5-15 device cost, optimized for utilities and simple metering. LoRaWAN (green): CSS 125-500 kHz modulation, 243-byte payload, unlimited messages (duty cycle limits), user-deployable private networks or TTN, gateway cost $200-1,000 with $10-25 devices, flexible for agriculture and smart buildings. Sigfox offers simplest deployment and lowest device cost with global coverage; LoRaWAN provides more data capacity, infrastructure control, and no message limits.

Decision Framework: When to Choose Each Technology

Choose Sigfox when: - Coverage exists in your deployment region (verify first!) - Small, infrequent messages (environmental monitoring, asset tracking) - Deployment < 1,000 devices (subscription model economical) - No infrastructure management capability - Global roaming needed (single subscription works across countries)

Choose LoRaWAN when: - Need larger payloads (> 12 bytes) or frequent updates (> 140/day) - Large-scale deployment (> 1,000 devices - infrastructure becomes cheaper) - Want network control and coverage customization - Sigfox coverage unavailable in deployment area - Private network required (security/compliance)

Crossover Point: Around 1,000-2,000 devices, LoRaWAN’s infrastructure cost becomes competitive with Sigfox’s cumulative subscription fees.

1117.2 Decision Framework: Choosing the Right LPWAN Technology

When Should You Use Each Technology?

Use Sigfox when: - Simple sensors with infrequent data (temperature, water meters, parking sensors) - Message size under 12 bytes and less than 140 messages/day - Coverage exists in your deployment region (verify first!) - Small to medium deployment (<1,000 devices) - No infrastructure management capability or desire - Global roaming needed (single subscription works across countries) - Budget-constrained project (lowest upfront and operational cost)

Use LoRaWAN when: - Need larger payloads (>12 bytes) or more frequent updates (>140/day) - Large-scale deployment (>1,000 devices - infrastructure becomes economical) - Want network control and coverage customization - Sigfox coverage unavailable in your deployment area - Private network required (security/compliance/independence) - Bidirectional communication needed (sensors + actuators)

Use NB-IoT when: - Need high data rates (>1 kbps) or larger payloads (>1 KB) - Mobile assets requiring seamless handover (vehicles, shipping) - Real-time applications with latency <5 seconds - Existing cellular carrier relationships - Indoor/underground deployments (better penetration than LPWAN) - Willing to pay premium for carrier-grade reliability

1117.2.1 LPWAN Technology Comparison with Real Numbers

Criterion	Sigfox	LoRaWAN	NB-IoT
Range	10-50 km rural, 3-10 km urban	2-15 km rural, 1-5 km urban	1-10 km (cellular coverage)
Payload	12 bytes up, 8 bytes down	Up to 242 bytes	Up to 1600 bytes
Messages	140 up/4 down per day	Unlimited (duty cycle limited)	Unlimited
Battery Life	10-20 years	5-15 years	2-10 years
Device Cost	$5-15	$10-25	$15-30
Connectivity	$1-2/device/year	$0 (own infrastructure) or $1-5/year (TTN)	$6-24/device/year
Infrastructure	$0 (operator-provided)	$200-1,500 per gateway	$0 (carrier-provided)
Coverage	75+ countries, operator-dependent	Self-deployed or community (TTN)	190+ countries (cellular)
Deployment	Easiest (plug-and-play)	Moderate (gateway setup)	Easy (SIM card)
Latency	2-90 seconds	1-5 seconds	1-10 seconds

1117.2.2 Cost Crossover Analysis (5-Year Total Cost of Ownership)

100 DEVICES (5 years):
━━━━━━━━━━━━━━━━━━━━━━
Sigfox:    $1,500 devices + $500 subscription = $2,000 ✓ CHEAPEST
LoRaWAN:   $2,000 devices + $500 gateway + $0 subscription = $2,500
NB-IoT:    $2,000 devices + $12,000 subscription = $14,000

1,000 DEVICES (5 years):
━━━━━━━━━━━━━━━━━━━━━━━━
Sigfox:    $12,000 devices + $5,000 subscription = $17,000 ✓ WINNER
LoRaWAN:   $20,000 devices + $5,000 gateways + $0 subscription = $25,000
NB-IoT:    $25,000 devices + $120,000 subscription = $145,000

10,000 DEVICES (5 years):
━━━━━━━━━━━━━━━━━━━━━━━━━
Sigfox:    $120,000 devices + $50,000 subscription = $170,000
LoRaWAN:   $200,000 devices + $50,000 gateways + $0 subscription = $250,000 ✓ STARTS TO WIN
NB-IoT:    $250,000 devices + $1,200,000 subscription = $1,450,000

50,000+ DEVICES: LoRaWAN becomes most economical (infrastructure amortized)

Key Insight: Sigfox wins for small-to-medium deployments (<5,000 devices). LoRaWAN becomes cheaper at scale due to zero per-device fees. NB-IoT is premium option for specific use cases only.

1117.3 Deep Dive: Advanced Sigfox Concepts

Technical Deep Dive: UNB Modulation Details

Ultra-Narrow Band (UNB) Modulation Explained:

Sigfox uses DBPSK (Differential Binary Phase Shift Keying) for uplink and GFSK (Gaussian Frequency Shift Keying) for downlink, both squeezed into extremely narrow 100 Hz channels.

Why 100 Hz Channels?

Bandwidth vs Range Trade-off:
━━━━━━━━━━━━━━━━━━━━━━━━━━
Wide channel (Wi-Fi 20 MHz):     High data rate, short range, high power
Medium channel (LoRa 125 kHz):  Moderate data, long range, low power
Narrow channel (Sigfox 100 Hz): Tiny data, extreme range, minimal power

Shannon-Hartley Theorem: C = B × log₂(1 + SNR)
- Sigfox reduces bandwidth (B) dramatically
- Compensates by improving SNR through long transmission time
- Result: Same information, much lower power density

Technical Specifications:

Parameter	Uplink (DBPSK)	Downlink (GFSK)
Modulation	Differential BPSK	Gaussian FSK
Bandwidth	100 Hz	600 Hz
Data Rate	100 bps	600 bps
TX Power	14-27 dBm (25-500 mW)	N/A (base station)
RX Sensitivity	-126 dBm typical, -142 dBm best	-142 dBm
Transmission Time	~6 seconds per message	~4 seconds
Frequency Hop	Random per message	Fixed during RX window

Link Budget Calculation:

Sigfox Link Budget (Uplink):
━━━━━━━━━━━━━━━━━━━━━━━━━━━
TX Power:              +14 dBm (device)
Antenna Gain (device): -2 dBm (PCB antenna)
Path Loss (10 km):     -125 dB (free space + obstacles)
Antenna Gain (BS):     +10 dBm (base station tower)
━━━━━━━━━━━━━━━━━━━━━━━━━━━
Received Signal:       -103 dBm

RX Sensitivity:        -126 dBm (typical)
Link Margin:           23 dB ✓ (good margin)

With 30 km range:
Path Loss:             -135 dB
Received Signal:       -113 dBm
Link Margin:           13 dB ✓ (still works)

Why This Matters: The extreme sensitivity (-142 dBm) enables Sigfox to work in very challenging RF environments - underground pipes, inside metal containers, dense urban areas.

Show code

{
  const container = document.getElementById('kc-sigfox-11');
  if (container && typeof InlineKnowledgeCheck !== 'undefined') {
    container.innerHTML = '';
    container.appendChild(InlineKnowledgeCheck.create({
      question: "Sigfox achieves -142 dBm receiver sensitivity using 100 Hz ultra-narrow band channels, while LoRa at SF12 achieves -137 dBm with 125 kHz channels. What does this 5 dB advantage translate to in practice?",
      options: [
        {text: "Sigfox can transmit 5x more data per message", correct: false, feedback: "The sensitivity advantage relates to range, not data capacity. In fact, Sigfox's narrow channels mean LESS data (12 bytes vs LoRa's 242 bytes)."},
        {text: "Sigfox can achieve approximately 1.8x longer range in the same conditions", correct: true, feedback: "Correct! Every 6 dB doubles the range in free space. 5 dB gives approximately 1.78x range improvement. This is why Sigfox can achieve 30-50 km rural range vs LoRa's 15-30 km, making it ideal for sparse deployments where base stations are far apart."},
        {text: "Sigfox devices use 5 dB less transmit power", correct: false, feedback: "Both technologies transmit at similar power levels (14-27 dBm depending on region). The sensitivity advantage is on the RECEIVER side at the base station."},
        {text: "Sigfox messages arrive 5x faster than LoRa messages", correct: false, feedback: "Actually, Sigfox is slower! Its 100 bps data rate means a 12-byte message takes ~2 seconds, while LoRa SF12 at 250 bps is faster for similar payloads."}
      ],
      difficulty: "hard",
      topic: "sigfox-unb"
    }));
  }
}

Technical Deep Dive: Sigfox Network Architecture

Three-Tier Architecture:

%% fig-alt: Sigfox three-tier network architecture showing end devices connecting via UNB radio to base stations which forward messages via IP to the Sigfox cloud backend
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flowchart TB
    subgraph T1["Tier 1: End Devices"]
        T1A["Sensors with Sigfox radio modules"]
        T1B["Ultra-simple: No network stack"]
        T1C["Fire-and-forget transmission"]
        T1D["10-20 year battery life"]
    end

    subgraph T2["Tier 2: Base Stations (Operator-Owned)"]
        T2A["Receive messages from multiple devices"]
        T2B["No device authentication at radio layer"]
        T2C["Record: message, RSSI, SNR, timestamp"]
        T2D["Forward to Sigfox Cloud via IP"]
    end

    subgraph T3["Tier 3: Sigfox Cloud Backend"]
        T3A["Message deduplication (if multiple BS)"]
        T3B["Geolocation calculation (RSSI-based)"]
        T3C["Device authentication & billing"]
        T3D["HTTPS callbacks to customer apps"]
        T3E["Downlink message queueing"]
    end

    T1 -->|"UNB 100 Hz<br/>(868/902 MHz ISM)"| T2
    T2 -->|"Internet<br/>(Backhaul)"| T3

    style T1 fill:#2C3E50,color:#fff
    style T2 fill:#16A085,color:#fff
    style T3 fill:#E67E22,color:#fff

Spatial Diversity (Redundant Reception):

Sigfox base stations operate in “always listening” mode. When a device transmits, multiple base stations typically receive the same message, improving reliability:

Message Reception Example:
━━━━━━━━━━━━━━━━━━━━━━━━━━
Device sends 1 message

BS #1: RSSI -98 dBm, SNR 12 dB → ✓ Received
BS #2: RSSI -115 dBm, SNR 3 dB → ✓ Received
BS #3: RSSI -130 dBm, SNR -5 dB → ✗ Missed

Sigfox Cloud:
• Receives message from BS #1 and BS #2
• Deduplicates (keeps strongest signal)
• Uses triangulation for geolocation
• Result: 99%+ reliability even if one BS fails

Geolocation Without GPS:

Sigfox can estimate device location using signal strength from multiple base stations:

RSSI-Based Geolocation:
━━━━━━━━━━━━━━━━━━━━━━
BS #1 (-98 dBm): Device ~5 km away
BS #2 (-110 dBm): Device ~15 km away
BS #3 (-105 dBm): Device ~10 km away

Triangulation Algorithm:
→ Calculates most likely position
→ Accuracy: 1-10 km (rural) to 100-500 m (urban)
→ No GPS needed (saves device cost + power)

Use Cases: Asset tracking without GPS modules, emergency location for lone workers, wildlife monitoring.

Show code

{
  const container = document.getElementById('kc-sigfox-12');
  if (container && typeof InlineKnowledgeCheck !== 'undefined') {
    container.innerHTML = '';
    container.appendChild(InlineKnowledgeCheck.create({
      question: "A wildlife conservation project tracks elephants across a national park. Budget is tight, so they want to use Sigfox Atlas (RSSI-based geolocation) instead of GPS. The park covers 5,000 km2 with 3 Sigfox base stations. Is Atlas suitable for this application?",
      options: [
        {text: "Yes - Atlas provides 1-5 km accuracy which is sufficient for wildlife conservation", correct: true, feedback: "Correct! Atlas uses RSSI triangulation from multiple base stations to estimate location within 1-10 km. For tracking elephants across a large park, knowing they're in 'sector 7' (5 km accuracy) is valuable for anti-poaching patrols and population monitoring - and saves the $5-15 GPS module cost plus significant battery drain."},
        {text: "No - elephants move too fast for Sigfox's slow update rate", correct: false, feedback: "Elephants typically move 3-6 km/hour. With hourly updates (easily within 140/day limit), you'd track their general movement patterns effectively. Real-time tracking isn't needed for conservation."},
        {text: "No - Atlas requires at least 10 base stations for any accuracy", correct: false, feedback: "Atlas works with 2+ base stations for triangulation. With 3 base stations covering 5,000 km2, you'll get 1-10 km accuracy depending on geometry and terrain. Not GPS-grade, but useful for wildlife."},
        {text: "Yes - but only if elephants stay within 1 km of base stations", correct: false, feedback: "Atlas doesn't require proximity to base stations. It uses signal strength differences from multiple distant stations (up to 30-50 km range) to triangulate position."}
      ],
      difficulty: "medium",
      topic: "sigfox-atlas"
    }));
  }
}

Technical Deep Dive: Sigfox Atlas Geolocation

Sigfox Atlas is a cloud-based service that provides device geolocation without requiring GPS hardware.

How It Works:

RSSI Collection: Multiple base stations record signal strength (RSSI) when receiving device message
Propagation Model: Sigfox applies radio propagation models accounting for terrain, buildings, weather
Triangulation: Calculates most probable device location using RSSI from 2+ base stations
Machine Learning: Improves accuracy over time by learning environmental factors

Accuracy Comparison:

Environment	Atlas Accuracy	GPS Accuracy	Power/Cost Difference
Open rural	1-5 km	5-10 m	Atlas: 0 mW, $0
Suburban	500 m - 2 km	5-10 m	GPS: +50 mW, +$5-15
Dense urban	100-500 m	5-30 m	GPS battery: 2× drain
Indoor	Not available	Not available	Both fail indoors

When to Use Atlas vs GPS:

Use Atlas: Low-precision tracking (city-level), cost-sensitive, battery-critical
Use GPS: High-precision needed (<100 m), mobile assets, outdoor-only deployment

1117.4 Videos

LPWAN Overview (Context for Sigfox)

Lesson 4 — LPWAN positioning and trade-offs (provides context for Sigfox's operator model and UNB design).

1117.6 Summary

Key Takeaways:

UNB Modulation: Ultra-narrow 100 Hz channels enable extreme sensitivity (-142 dBm) and long range (10-50 km)
Three-Tier Architecture: Simple devices → Operator base stations → Sigfox cloud backend
Spatial Diversity: Multiple base stations receive same message for 99%+ reliability
Atlas Geolocation: RSSI-based positioning (1-10 km accuracy) without GPS hardware
Network Philosophy: All intelligence in cloud, minimal device complexity

Technology Comparisons:

Feature	Sigfox	LoRaWAN	NB-IoT
Modulation	UNB (DBPSK)	CSS (LoRa)	LTE (OFDMA)
Bandwidth	100 Hz	125-500 kHz	180 kHz
Sensitivity	-142 dBm	-148 dBm	-164 dBm
Infrastructure	Operator-only	User-deployable	Carrier-only
Cost (1K?) devices	$17K (5yr)	$25K (5yr)	$145K (5yr)

1117.7 What’s Next

In the next chapters, explore:

Worked Examples: Practical calculations for message budgets, TCO analysis, link budgets, and duty cycle compliance
Assessment: Test your Sigfox knowledge with comprehensive quizzes