1068  LPWAN Architectures

1068.1 Learning Objectives

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

  • Design LoRaWAN Networks: Plan star-of-stars topologies with gateways and network servers
  • Configure Sigfox Deployments: Understand operator-managed networks and callback mechanisms
  • Compare LPWAN Topologies: Analyze architectural differences between LoRaWAN, Sigfox, and NB-IoT
  • Implement Device Classes: Select appropriate LoRaWAN device classes (A/B/C) for application needs
  • Plan Backhaul Connectivity: Design gateway-to-server connections using IP networks
  • Evaluate Network Scalability: Assess capacity limits and coverage requirements for LPWAN deployments

1068.2 Prerequisites

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

  • LPWAN Fundamentals: Understanding core LPWAN characteristics and technology trade-offs is essential for evaluating different architectural approaches
  • Network Topologies: Knowledge of star, mesh, and hybrid topologies provides context for understanding LPWAN-specific topology choices
  • LoRaWAN Overview: Familiarity with LoRaWAN basics, device classes, and protocol fundamentals is necessary for understanding detailed architectural design
  • Wireless Sensor Networks: WSN architecture principles and multi-hop communication concepts help contextualize LPWAN deployment strategies

If you’re deploying hundreds or thousands of IoT sensors across a city, campus, or farm, you face a critical design question: How should your network be structured? LPWAN architectures answer this question differently than traditional networks.

LoRaWAN: Star-of-Stars (DIY Model) Think of LoRaWAN like setting up your own cellular network. You buy gateways (like cell towers) and place them strategically. Sensors send data to any gateway in range—often multiple gateways receive the same transmission (redundancy!). Gateways forward everything to your network server (in the cloud), which deduplicates, decrypts, and routes to your application. You control everything: gateway placement, network configuration, data ownership.

Sigfox: Operator-Managed (Subscription Model) Sigfox is like using Verizon or AT&T for IoT. The Sigfox company operates the base stations—you just buy sensors and subscribe. Your sensors transmit; Sigfox infrastructure receives and forwards data to your server via callbacks (webhooks). Simple, but you’re dependent on Sigfox coverage and subject to their limits (140 messages/day).

NB-IoT/LTE-M: Cellular (Telco Model) Uses existing cell towers from AT&T, Vodafone, T-Mobile, etc. Sensors have SIM cards like phones. Maximum coverage (wherever cell service exists), but higher power consumption and recurring cellular data costs.

Term Simple Explanation
Star-of-Stars Devices → Gateways → Network Server (LoRaWAN topology)
Gateway Antenna receiving LoRa transmissions and forwarding to network server
Network Server Central system managing security, routing, deduplication
Backhaul Internet connection from gateway to network server (Ethernet/4G)
Operator-Managed Network run by company (Sigfox)—you just subscribe
Private Network You own and control all infrastructure (LoRaWAN)
Callbacks Webhooks—Sigfox pushes data to your HTTP endpoint
Device Class LoRaWAN A/B/C—determines power use vs downlink capability
NoteCross-Hub Connections

Explore Related Learning Resources:

  • Simulations Hub - Interactive LPWAN network planning tools and coverage calculators
  • Videos Hub - Visual explanations of star-of-stars topology and gateway operation
  • Quizzes Hub - Test your understanding of LoRaWAN, Sigfox, and NB-IoT architectures
  • Knowledge Map - See how LPWAN architectures connect to topology, routing, and deployment strategies

Why These Matter: LPWAN architectures require understanding trade-offs between coverage, cost, and control. The simulations hub helps visualize gateway placement, while the knowledge map shows how architecture choices affect protocol selection and application design.

WarningCommon Misconception: “LPWAN = Always Long Range”

The Myth: Many assume all LPWAN technologies automatically provide 10+ km range in any environment.

The Reality: Range is highly deployment-specific:

  • LoRaWAN Urban Reality: Typical urban range is 2-5 km, not 15 km
    • Buildings, interference, and antenna height drastically reduce theoretical range
    • Gateway at ground level: ~500m-1km effective coverage
    • Gateway on rooftop: 3-5 km typical, 10 km possible with clear line-of-sight
  • Sigfox Base Station Density: Operator claims “40 km range” refer to rural open field conditions
    • Urban deployments: Base stations every 2-5 km for reliability
    • Indoor penetration: Signals attenuate 20-30 dB through buildings
  • NB-IoT Coverage Limitations: Uses cellular towers, but indoor coverage can be poor
    • NB-IoT has 20 dB better penetration than LTE-M, but still struggles in basements
    • ~164 dB link budget (NB-IoT) vs ~146 dB (LTE-M) vs ~157 dB (LoRaWAN SF12)

Key Insight: Always conduct a site survey before deploying LPWAN networks. Theoretical range calculations (Friis equation) assume free space—real deployments require accounting for: - Building penetration loss (10-30 dB) - Foliage attenuation (0.5-1 dB per tree) - Interference from other ISM band devices (Wi-Fi, Bluetooth) - Antenna gain and height (every 6 dB doubles range)

Example: A farm deployment claiming “15 km LoRaWAN range” likely uses: - Gateway on 30m tower or silo (height advantage) - High-gain directional antennas (8-12 dBi) - Rural environment with minimal interference - Line-of-sight to most sensors

Replicating this in a city with gateway on a 10m building rooftop? Expect 2-3 km maximum.

1068.3 LPWAN Technology Comparison

⏱️ ~10 min | ⭐⭐ Intermediate | 📋 P09.C03.U01

Comprehensive IoT layered architecture diagram from NPTEL IIT Kharagpur course showing five tiers. From bottom: Context-Aware Tier (Data Collector layer with sensors, two-dimensional codes, RFID, multi-media information; Coordination and Collaboration layer with low/medium/high speed communication, self-learn network, collaboration technology, sensor middleware technology). Network Tier (Network Support Technology layer with next generation network, hybrid network infrastructure, mobile network, internet; Interconnect with network and context-aware layer). Application Tier (Intelligent Computer Technology layer with SOA, platform enhanced technology, cloud computer; Middleware Layer with info management, service management, user management, technical management, authentication and authorization, billing; Application Layer with environmental monitor, IA power, IA logistics, industry monitor). Demonstrates how LPWAN fits in the network support technology layer connecting context-aware sensors to application services.

IoT multi-tier architecture showing network support layer where LPWAN operates

Source: NPTEL Internet of Things Course, IIT Kharagpur - This architecture shows how LPWAN technologies fit within the Network Support Technology layer, connecting the Context-Aware Tier (sensors, RFID, data collectors) to the Application Tier (middleware, cloud services, industry applications). LPWAN provides the “low, medium, and high speed communication” bridge in this layered model.

Understanding the differences between LPWAN technologies helps you choose the right solution for your deployment. This comprehensive comparison covers the three major LPWAN options:

Feature LoRaWAN Sigfox NB-IoT / LTE-M
Deployment Model Private or operator Operator-managed only Telco operator (licensed)
Network Ownership You own (private) or subscribe Subscription only Cellular subscription
Spectrum Unlicensed ISM (868/915 MHz) Unlicensed ISM (868/915 MHz) Licensed cellular bands
Range 2-15 km (urban/rural) 10-40 km (excellent) Cellular coverage (km)
Data Rate 0.3-50 kbps (adaptive) 100 bps (very limited) NB-IoT: 250 kbps, LTE-M: 1 Mbps
Payload Size Up to 242 bytes 12 bytes uplink, 8 bytes downlink Flexible (1-1000+ bytes)
Messages per Day Unlimited (fair use) 140 uplink, 4 downlink (hard limit) Unlimited (data plan limits)
Latency Seconds (Class A), ms (Class C) Seconds to minutes <1 second (LTE-M), seconds (NB-IoT)
Battery Life 5-10 years typical 10-15 years (ultra-low power) 5-10 years (PSM/eDRX modes)
Bi-directional Yes (Class A/B/C options) Limited (4 downlinks/day) Yes (full duplex)
Mobility Support Limited (stationary focus) Good (handoff between stations) Excellent (cellular handoff)
Infrastructure Cost $500-1000 per gateway None (operator-managed) None (cellular towers exist)
Device Cost $5-20 (modules) $5-15 (modules) $10-30 (modules)
Setup Complexity Medium (deploy gateways) Easy (just subscribe) Easy (SIM card)
Network Scalability High (add gateways) Limited (operator capacity) Very high (cellular infrastructure)
Security AES-128 (end-to-end) AES-128 (operator-managed) 3GPP cellular security
Geolocation TDOA (with 3+ gateways) RSSI-based (built-in) Cell tower triangulation
Standards Body LoRa Alliance Sigfox (proprietary) 3GPP (international standard)
TipWhich LPWAN Should You Choose?

Choose LoRaWAN when: - ✅ You want to own the network (no recurring subscription fees) - ✅ You need flexible data rates and payload sizes (up to 242 bytes) - ✅ You need bidirectional communication (downlinks to devices) - ✅ You’re deploying in areas without Sigfox or cellular coverage - ✅ You need unlimited messages per day - ✅ You have budget for gateway infrastructure ($500-1000 per gateway)

Example: Farm monitoring (50-acre property, 100 soil sensors, no cell coverage) → Deploy 2 LoRaWAN gateways

Choose Sigfox when: - ✅ You want simplest deployment (no infrastructure to manage) - ✅ You have tiny payloads (≤12 bytes) and infrequent updates (≤140/day) - ✅ Sigfox coverage exists in your region (check coverage map) - ✅ You need ultra-long battery life (10-15 years) - ✅ Uplink-only communication is sufficient (or very rare downlinks)

Example: Asset tracking (shipping pallets reporting GPS every 30 min = 48 messages/day)

Choose NB-IoT / LTE-M when: - ✅ You need reliable, nationwide coverage (anywhere cell service exists) - ✅ You need higher data rates (250 kbps - 1 Mbps) for occasional firmware updates - ✅ You need low latency (<1 second for LTE-M) - ✅ Mobility support is required (asset tracking with handoff between cell towers) - ✅ You’re okay with recurring cellular data costs (similar to phone plan) - ✅ You need guaranteed QoS from telco operator SLA

Example: Smart parking meters (city-wide, need reliable uptime, firmware updates, existing AT&T/Verizon coverage)

NoteCost Comparison Example (1000 devices, 5 years)

LoRaWAN (Private Network):

Infrastructure: 10 gateways × $1000 = $10,000
Device modules: 1000 × $10 = $10,000
Network server: $100/month × 60 months = $6,000
Total 5-year cost: $26,000 ($5.20 per device/year)

Sigfox (Subscription):

Infrastructure: $0 (operator-managed)
Device modules: 1000 × $10 = $10,000
Subscription: 1000 × $10/year × 5 years = $50,000
Total 5-year cost: $60,000 ($12 per device/year)

NB-IoT (Cellular):

Infrastructure: $0 (cellular towers)
Device modules: 1000 × $20 = $20,000
Data plan: 1000 × $5/month × 60 months = $300,000
Total 5-year cost: $320,000 ($64 per device/year)

Key Insight: LoRaWAN private networks have higher upfront cost but lowest ongoing cost. Cellular has highest cost but best coverage and reliability. Sigfox is middle ground between DIY and cellular.

1068.4 LoRaWAN Star‑of‑Stars

⏱️ ~15 min | ⭐⭐ Intermediate | 📋 P09.C03.U02

LoRaWAN uses a star‑of‑stars topology: battery devices send LoRa frames to nearby gateways; gateways forward to a network server, which routes to application servers.

%%{init: {'theme': 'base', 'themeVariables': {'primaryColor': '#2C3E50', 'primaryTextColor': '#fff', 'primaryBorderColor': '#16A085', 'lineColor': '#16A085', 'secondaryColor': '#E67E22', 'tertiaryColor': '#7F8C8D', 'background': '#ffffff', 'mainBkg': '#2C3E50', 'secondBkg': '#16A085', 'tertiaryBkg': '#E67E22'}}}%%
graph TB
    subgraph devices[" End Devices "]
        D1[Sensor 1<br/>Class A]
        D2[Sensor 2<br/>Class A]
        D3[Actuator<br/>Class C]
        D4[Beacon<br/>Class B]
    end

    subgraph gateways[" Gateways "]
        GW1[Gateway 1<br/>Ethernet]
        GW2[Gateway 2<br/>Wi-Fi]
        GW3[Gateway 3<br/>4G]
    end

    subgraph backend[" Backend Infrastructure "]
        NS[Network Server<br/>Deduplication<br/>MAC Commands]
        AS[Application Server<br/>Data Processing]
    end

    D1 -.->|LoRa RF| GW1
    D1 -.->|LoRa RF| GW2
    D2 -.->|LoRa RF| GW2
    D2 -.->|LoRa RF| GW3
    D3 -.->|LoRa RF| GW1
    D4 -.->|LoRa RF| GW3

    GW1 -->|Packet Forwarder<br/>IP/UDP| NS
    GW2 -->|Packet Forwarder<br/>IP/UDP| NS
    GW3 -->|Packet Forwarder<br/>IP/UDP| NS

    NS -->|Application Data| AS
    AS -.->|Downlink| NS
    NS -.->|MAC/App Data| GW1
    NS -.->|MAC/App Data| GW2

    style devices fill:#f0f0f0,stroke:#2C3E50,stroke-width:2px
    style gateways fill:#f0f0f0,stroke:#16A085,stroke-width:2px
    style backend fill:#f0f0f0,stroke:#E67E22,stroke-width:2px
    style D1 fill:#2C3E50,stroke:#16A085,color:#fff
    style D2 fill:#2C3E50,stroke:#16A085,color:#fff
    style D3 fill:#2C3E50,stroke:#16A085,color:#fff
    style D4 fill:#2C3E50,stroke:#16A085,color:#fff
    style GW1 fill:#16A085,stroke:#2C3E50,color:#fff
    style GW2 fill:#16A085,stroke:#2C3E50,color:#fff
    style GW3 fill:#16A085,stroke:#2C3E50,color:#fff
    style NS fill:#E67E22,stroke:#2C3E50,color:#fff
    style AS fill:#E67E22,stroke:#2C3E50,color:#fff

Figure 1068.1: LoRaWAN star-of-stars architecture with multi-gateway redundancy

{fig-alt=“LoRaWAN star-of-stars architecture showing end devices (Classes A, B, C) communicating via LoRa RF to multiple gateways, which forward packets over IP backhaul (Ethernet, Wi-Fi, 4G) to the Network Server for deduplication and routing to Application Server. Demonstrates redundancy with devices reaching multiple gateways.”}

%%{init: {'theme': 'base', 'themeVariables': {'primaryColor': '#2C3E50', 'primaryTextColor': '#fff', 'primaryBorderColor': '#16A085', 'lineColor': '#16A085', 'secondaryColor': '#E67E22', 'tertiaryColor': '#7F8C8D'}}}%%
graph TB
    subgraph ClassA["Class A: Lowest Power"]
        A1["Uplink triggered by device"]
        A2["RX1: 1 sec after TX"]
        A3["RX2: 2 sec after TX"]
        A4["Sleep until next uplink"]
    end

    subgraph ClassB["Class B: Scheduled Windows"]
        B1["Beacon synchronized"]
        B2["Scheduled RX slots"]
        B3["Predictable latency"]
        B4["Medium power"]
    end

    subgraph ClassC["Class C: Always Listening"]
        C1["Continuous RX"]
        C2["Minimal latency"]
        C3["Highest power"]
        C4["For actuators"]
    end

    A1 --> A2 --> A3 --> A4
    B1 --> B2 --> B3 --> B4
    C1 --> C2 --> C3 --> C4

    style ClassA fill:#16A085,stroke:#2C3E50
    style ClassB fill:#E67E22,stroke:#2C3E50
    style ClassC fill:#2C3E50,stroke:#16A085

This diagram compares the three LoRaWAN device classes, showing how each trades off power consumption against downlink latency and receive window availability.

Key points: - Uplink frames can be received by multiple gateways; the network server de‑duplicates - Class A/B/C end device classes trade battery vs. latency - Gateways are stateless packet forwarders; backhaul via Ethernet/Wi-Fi/Cellular

1068.5 Sigfox Operator Model

⏱️ ~10 min | ⭐⭐ Intermediate | 📋 P09.C03.U03

Sigfox provides a fully managed network. Devices use ultra‑narrowband to operator base stations; backend routes messages to customer callbacks.

%%{init: {'theme': 'base', 'themeVariables': {'primaryColor': '#2C3E50', 'primaryTextColor': '#fff', 'primaryBorderColor': '#16A085', 'lineColor': '#16A085', 'secondaryColor': '#E67E22', 'tertiaryColor': '#7F8C8D', 'background': '#ffffff', 'mainBkg': '#2C3E50', 'secondBkg': '#16A085', 'tertiaryBkg': '#E67E22'}}}%%
graph TB
    subgraph devices[" Sigfox Devices "]
        SD1[Device 1<br/>12 bytes UL]
        SD2[Device 2<br/>8 bytes DL]
        SD3[Device 3<br/>Uplink Only]
    end

    subgraph operator[" Sigfox Operator Network "]
        BS1[Base Station 1<br/>Ultra-Narrowband]
        BS2[Base Station 2<br/>100 Hz BW]
        BS3[Base Station 3<br/>Spatial Diversity]
        BE[Sigfox Backend<br/>Message Processing<br/>Geolocation]
    end

    subgraph customer[" Customer Infrastructure "]
        CB[Callback Server<br/>HTTP/HTTPS<br/>Webhook]
        APP[Application<br/>Data Processing]
    end

    SD1 -.->|UNB 868/902 MHz| BS1
    SD1 -.->|3× Repetition| BS2
    SD2 -.->|UNB| BS2
    SD2 -.->|UNB| BS3
    SD3 -.->|UNB| BS3

    BS1 -->|Proprietary Protocol| BE
    BS2 -->|Proprietary Protocol| BE
    BS3 -->|Proprietary Protocol| BE

    BE -->|REST API/Callback<br/>JSON Payload| CB
    CB -->|Application Data| APP
    APP -.->|Downlink Request<br/>4 msgs/day max| CB
    CB -.->|API Call| BE
    BE -.->|Downlink| BS2

    style devices fill:#f0f0f0,stroke:#2C3E50,stroke-width:2px
    style operator fill:#f0f0f0,stroke:#E67E22,stroke-width:2px
    style customer fill:#f0f0f0,stroke:#16A085,stroke-width:2px
    style SD1 fill:#2C3E50,stroke:#16A085,color:#fff
    style SD2 fill:#2C3E50,stroke:#16A085,color:#fff
    style SD3 fill:#2C3E50,stroke:#16A085,color:#fff
    style BS1 fill:#E67E22,stroke:#2C3E50,color:#fff
    style BS2 fill:#E67E22,stroke:#2C3E50,color:#fff
    style BS3 fill:#E67E22,stroke:#2C3E50,color:#fff
    style BE fill:#E67E22,stroke:#2C3E50,color:#fff
    style CB fill:#16A085,stroke:#2C3E50,color:#fff
    style APP fill:#16A085,stroke:#2C3E50,color:#fff

Figure 1068.2: Sigfox operator-managed network with webhook callbacks

{fig-alt=“Sigfox operator-managed architecture showing devices transmitting ultra-narrowband (UNB) messages with 3× repetition for spatial diversity to multiple base stations. Operator backend processes messages and delivers to customer callback servers via HTTP webhooks. Downlink path limited to 4 messages per day.”}

Characteristics: - Very small payloads (uplink‑focused), extremely low power - Coverage and QoS tied to operator footprint - Simple device model (no gateway to manage)

1068.6 NB‑IoT / LTE‑M Architecture

Cellular LPWAN integrates with 4G/5G core. Devices attach to eNodeB/gNodeB; data egresses via EPC/5GC to application servers.

%%{init: {'theme': 'base', 'themeVariables': {'primaryColor': '#2C3E50', 'primaryTextColor': '#fff', 'primaryBorderColor': '#16A085', 'lineColor': '#16A085', 'secondaryColor': '#E67E22', 'tertiaryColor': '#7F8C8D', 'background': '#ffffff', 'mainBkg': '#2C3E50', 'secondBkg': '#16A085', 'tertiaryBkg': '#E67E22'}}}%%
graph TB
    subgraph devices[" NB-IoT/LTE-M Devices "]
        ND1[NB-IoT Device<br/>eSIM/SIM<br/>PSM Mode]
        ND2[LTE-M Device<br/>Voice Support<br/>Mobile]
        ND3[NB-IoT Sensor<br/>eDRX Mode<br/>Stationary]
    end

    subgraph ran[" Radio Access Network "]
        ENB1[eNodeB 1<br/>4G Base Station]
        ENB2[eNodeB 2<br/>Licensed Spectrum]
        GNB[gNodeB<br/>5G Base Station]
    end

    subgraph core[" Core Network "]
        MME[MME/AMF<br/>Mobility Management]
        SGW[SGW/UPF<br/>Packet Gateway]
        HSS[HSS/UDM<br/>Subscriber DB]
    end

    subgraph external[" External Networks "]
        PDN[PDN Gateway<br/>Internet Access]
        APP[Application Server<br/>IoT Platform]
    end

    ND1 -.->|NB-IoT<br/>Licensed Band| ENB1
    ND2 -.->|LTE-M Cat-M1| ENB2
    ND2 -.->|Handoff| GNB
    ND3 -.->|NB-IoT| ENB2

    ENB1 -->|S1 Interface| MME
    ENB2 -->|S1 Interface| MME
    GNB -->|NG Interface| MME

    MME <-->|Auth/Attach| HSS
    MME -->|Bearer Setup| SGW
    SGW -->|User Plane| PDN

    PDN -->|IP Connection| APP
    APP -.->|MT Data| PDN

    style devices fill:#f0f0f0,stroke:#2C3E50,stroke-width:2px
    style ran fill:#f0f0f0,stroke:#16A085,stroke-width:2px
    style core fill:#f0f0f0,stroke:#E67E22,stroke-width:2px
    style external fill:#f0f0f0,stroke:#7F8C8D,stroke-width:2px
    style ND1 fill:#2C3E50,stroke:#16A085,color:#fff
    style ND2 fill:#2C3E50,stroke:#16A085,color:#fff
    style ND3 fill:#2C3E50,stroke:#16A085,color:#fff
    style ENB1 fill:#16A085,stroke:#2C3E50,color:#fff
    style ENB2 fill:#16A085,stroke:#2C3E50,color:#fff
    style GNB fill:#16A085,stroke:#2C3E50,color:#fff
    style MME fill:#E67E22,stroke:#2C3E50,color:#fff
    style SGW fill:#E67E22,stroke:#2C3E50,color:#fff
    style HSS fill:#E67E22,stroke:#2C3E50,color:#fff
    style PDN fill:#7F8C8D,stroke:#2C3E50,color:#fff
    style APP fill:#7F8C8D,stroke:#2C3E50,color:#fff

Figure 1068.3: NB-IoT and LTE-M cellular architecture with 4G/5G core

{fig-alt=“NB-IoT and LTE-M cellular LPWAN architecture showing devices with SIM cards attaching to licensed spectrum base stations (eNodeB/gNodeB), connecting through 4G/5G core network (MME, SGW, HSS) to reach application servers via PDN Gateway. Demonstrates PSM/eDRX power-saving modes and mobile handoff capabilities.”}

Design notes: - Licensed spectrum, mobility, and SIM/eSIM lifecycle - Power‑saving modes: PSM/eDRX for multi‑year battery life - Best for nationwide coverage and operator‑managed SLAs

1068.7 Videos

NoteLPWAN Overview
LPWAN Overview
Lesson 4 — positioning LPWAN technologies and design trade-offs.

Deep Dives: - LoRaWAN Overview - Core LoRaWAN architecture and fundamentals - LoRaWAN Architecture - Detailed network design and device classes - Sigfox Fundamentals - Operator-managed LPWAN alternative - LPWAN Fundamentals - Core concepts and technology comparison

Comparisons: - LPWAN Comparison - Compare LoRaWAN, Sigfox, NB-IoT architectures - NB-IoT Fundamentals - Cellular LPWAN architecture - LTE-M Fundamentals - Mobile cellular IoT alternative

Products:

Learning: - Quizzes Hub - Test your LPWAN architecture knowledge - Simulations Hub - Interactive LPWAN network tools

1068.9 Summary

This chapter covered LPWAN network architectures and topologies:

  • LoRaWAN Star-of-Stars: End devices communicate through stateless gateways that forward to network servers, enabling de-duplication and scalable deployments
  • Device Classes: LoRaWAN Class A (lowest power), Class B (scheduled downlinks), and Class C (continuous receive) provide different latency-power trade-offs
  • Sigfox Operator Model: Fully managed network with ultra-narrowband communication to operator base stations, routing messages to customer endpoints via callbacks
  • Cellular LPWAN Integration: NB-IoT and LTE-M integrate with 4G/5G core networks, leveraging licensed spectrum and existing cellular infrastructure
  • Backhaul Connectivity: Gateways use IP networks (Ethernet, Wi-Fi, cellular) to connect to network servers, enabling flexible deployment options
  • Power-Saving Modes: Technologies like PSM (Power Saving Mode) and eDRX enable multi-year battery life in cellular LPWAN deployments
  • Deployment Trade-offs: Private LoRaWAN networks offer control and no subscription costs, while operator models (Sigfox, NB-IoT) provide managed coverage with SLAs

1068.10 Knowledge Check

What is the typical network topology for LPWAN technologies like LoRaWAN?

Options: - A) Mesh topology - B) Star-of-stars topology - C) Ring topology - D) Full mesh topology

Correct: B) Star-of-stars topology

LPWAN typically uses star-of-stars: end devices connect to gateways (first star), and gateways connect to a central network server (second star). This simplifies end devices and reduces their power consumption.

What is a key architectural difference between LPWAN and traditional cellular IoT?

Options: - A) LPWAN requires SIM cards - B) LPWAN can use unlicensed spectrum - C) Cellular has longer range - D) LPWAN requires more gateways

Correct: B) LPWAN can use unlicensed spectrum

Technologies like LoRaWAN use unlicensed ISM bands, allowing private network deployment. Cellular IoT (NB-IoT, LTE-M) requires licensed spectrum and carrier agreements.

In LoRaWAN, if multiple gateways receive the same uplink message, what happens?

Options: - A) Only the first gateway forwards it - B) All gateways forward it; server deduplicates - C) Gateways coordinate to choose one - D) The message is discarded as duplicate

Correct: B) All gateways forward it; server deduplicates

Multiple gateway reception improves reliability. The network server receives all copies and deduplicates, using the best signal for processing.

Question 1: A vending machine needs to report sales data every hour and receive restocking alerts from the central server within 5 seconds. Which LoRaWAN class is most appropriate?

Explanation: Class C is correct because vending machines are mains-powered (no battery constraint) and require low-latency downlinks.

LoRaWAN Device Classes:

Class Receive Windows Power Downlink Latency Use Case
A After uplink only (RX1, RX2) Lowest Seconds to hours Battery sensors
B Scheduled beacon slots Medium Predictable (128ms-4s slots) Scheduled commands
C Continuous (except TX) Highest <2 seconds Mains-powered actuators

Why Class C for vending machines: - Mains-powered (always plugged in) - 5-second alert requirement needs continuous listening - Restocking alerts are time-sensitive - Power consumption is not a constraint

Question 2: Which LoRaWAN class would be WORST for a battery-powered wildlife tracker that reports location twice daily?

Explanation: Class C is the worst choice because continuous receive mode consumes 10-15 mA constantly.

Battery Life Comparison (225 mAh coin cell):

Class C (continuous RX):
- Current: 10-15 mA
- Battery life: 225 mAh / 12.5 mA = 18 hours!

Class A (TX + RX windows only):
- Active: ~0.5 seconds every 12 hours
- Sleep: 99.999% of time at 2 µA
- Battery life: 5-10 years

Difference: 4,380× longer life with Class A

Key insight: Device class determines receive behavior. Class C assumes mains power; Class A assumes battery power.

Question 3: A smart grid utility needs to send load-shedding commands to 50,000 smart meters with predictable latency (within 30 seconds) but wants to preserve battery life. Which approach is best?

Explanation: Class B provides the best balance of predictable latency and power efficiency.

Class B Mechanism:

Network beacons: Every 128 seconds (GPS-synchronized)
Ping slots: Device wakes at scheduled times (128ms-4s windows)
Result: Guaranteed downlink within beacon period + 1 ping slot

Example with 8 ping slots per beacon:
- Beacon period: 128 seconds
- Ping slot: 16 seconds average (128/8)
- Max latency: ~144 seconds (worst case)
- Typical latency: ~16 seconds

Power Comparison:

Class A (uplink every 30s to reduce wait):
- 48 uplinks/day × 0.1 mWh = 4.8 mWh/day
- Battery life: 2-3 years

Class B (beacon sync + ping slots):
- 672 beacon syncs/day × 0.01 mWh = 6.7 mWh/day
- 672 ping slots/day × 0.005 mWh = 3.4 mWh/day
- Total: ~10 mWh/day
- Battery life: 3-5 years

Class C (continuous RX):
- Battery life: Days to weeks

Why Class B wins for smart grid: - Predictable 30-second latency achievable (8 ping slots per 128s beacon) - Power efficiency acceptable for 10+ year meter battery - Scalable to 50,000 devices without overloading network with frequent uplinks

Question 4: Which LoRaWAN device class is the baseline that all LoRaWAN end devices must support?

Explanation: Class A is mandatory in LoRaWAN and provides the lowest-power uplink-triggered receive windows. Classes B and C are optional extensions for scheduled or near-continuous downlink reception.

1068.10.1 LPWAN Technology Selection Decision Tree (Variant View)

This decision flowchart provides an alternative approach to selecting the optimal LPWAN technology based on deployment requirements, ownership model, and technical constraints:

%%{init: {'theme': 'base', 'themeVariables': {'primaryColor': '#2C3E50', 'primaryTextColor': '#fff', 'primaryBorderColor': '#16A085', 'lineColor': '#E67E22', 'secondaryColor': '#16A085', 'tertiaryColor': '#7F8C8D'}}}%%
flowchart TD
    START(["LPWAN Technology<br/>Selection"])
    Q1{"Own network<br/>infrastructure?"}
    Q2{"Global cellular<br/>coverage needed?"}
    Q3{"Bidirectional<br/>communication?"}
    Q4{"Message payload<br/>size?"}
    Q5{"Downlink<br/>requirements?"}
    Q6{"Real-time<br/>latency needed?"}

    LORAWAN["LoRaWAN<br/>Private Network"]
    LORAWAN_PUB["LoRaWAN<br/>Public Network (TTN)"]
    SIGFOX["Sigfox<br/>Operator Network"]
    NBIOT["NB-IoT<br/>Cellular IoT"]
    LTEM["LTE-M<br/>Cellular IoT"]

    LW_FEATURES["Features:<br/>• Up to 243 bytes payload<br/>• Class A/B/C device options<br/>• AES-128 encryption<br/>• No message limits<br/>• Private or public network"]
    SF_FEATURES["Features:<br/>• 12 bytes uplink payload<br/>• 140 messages/day limit<br/>• Global operator coverage<br/>• Ultra-low power<br/>• No infrastructure needed"]
    NB_FEATURES["Features:<br/>• Deep indoor penetration<br/>• 10+ year battery life<br/>• Carrier-grade reliability<br/>• Unlimited messages<br/>• Higher latency (seconds)"]
    LM_FEATURES["Features:<br/>• Voice support (VoLTE)<br/>• Mobility/handover<br/>• Lower latency (ms)<br/>• OTA firmware updates<br/>• Higher power consumption"]

    START --> Q1
    Q1 -->|"Yes"| LORAWAN
    Q1 -->|"No"| Q2
    Q2 -->|"Yes"| Q6
    Q2 -->|"No"| Q3
    Q3 -->|"Minimal/None"| Q4
    Q3 -->|"Required"| LORAWAN_PUB
    Q4 -->|"≤12 bytes"| SIGFOX
    Q4 -->|">12 bytes"| LORAWAN_PUB
    Q6 -->|"Yes (<1s)"| LTEM
    Q6 -->|"No"| Q5
    Q5 -->|"Frequent"| NBIOT
    Q5 -->|"Rare/None"| NBIOT

    LORAWAN --> LW_FEATURES
    LORAWAN_PUB --> LW_FEATURES
    SIGFOX --> SF_FEATURES
    NBIOT --> NB_FEATURES
    LTEM --> LM_FEATURES

    style START fill:#7F8C8D,color:#fff
    style Q1 fill:#2C3E50,color:#fff
    style Q2 fill:#2C3E50,color:#fff
    style Q3 fill:#2C3E50,color:#fff
    style Q4 fill:#2C3E50,color:#fff
    style Q5 fill:#2C3E50,color:#fff
    style Q6 fill:#2C3E50,color:#fff
    style LORAWAN fill:#16A085,color:#fff
    style LORAWAN_PUB fill:#16A085,color:#fff
    style SIGFOX fill:#E67E22,color:#fff
    style NBIOT fill:#3498db,color:#fff
    style LTEM fill:#9b59b6,color:#fff
    style LW_FEATURES fill:#d4efdf,color:#2C3E50
    style SF_FEATURES fill:#fdebd0,color:#2C3E50
    style NB_FEATURES fill:#d6eaf8,color:#2C3E50
    style LM_FEATURES fill:#ebdef0,color:#2C3E50

Figure 1068.4: LPWAN technology selection decision tree guiding choices based on infrastructure ownership, coverage requirements, bidirectional needs, payload size, and latency constraints. LoRaWAN (teal) for private networks or flexible public deployment. Sigfox (orange) for ultra-simple uplink-focused applications with tiny payloads. NB-IoT (blue) for carrier-grade reliability with deep penetration. LTE-M (purple) for mobile assets requiring low latency and voice. {fig-alt=“LPWAN selection decision flowchart. Starts with ‘Own network infrastructure?’ If yes, choose LoRaWAN Private Network. If no, check ‘Global cellular coverage needed?’ If yes and real-time latency needed, choose LTE-M; otherwise NB-IoT. If no cellular needed, check bidirectional requirements: minimal leads to payload size check (≤12 bytes→Sigfox, >12 bytes→LoRaWAN Public), required leads to LoRaWAN Public. Each technology shows key features: LoRaWAN (243 bytes, Class A/B/C, no limits), Sigfox (12 bytes, 140 msgs/day, ultra-low power), NB-IoT (deep penetration, 10+ year battery), LTE-M (voice, mobility, low latency).”}

1068.10.2 LPWAN Power vs Range Trade-off (Variant View)

This scatter-plot style diagram visualizes the fundamental trade-offs between power consumption, range, and data rate across LPWAN technologies:

%%{init: {'theme': 'base', 'themeVariables': {'primaryColor': '#2C3E50', 'primaryTextColor': '#fff', 'primaryBorderColor': '#16A085', 'lineColor': '#E67E22', 'secondaryColor': '#16A085', 'tertiaryColor': '#7F8C8D'}}}%%
graph TB
    subgraph Header["LPWAN Technology Positioning"]
        direction LR
        H1["📶 Range"]
        H2["⚡ Power"]
        H3["📊 Data Rate"]
    end

    subgraph LoRa["LoRaWAN Characteristics"]
        L1["Range: 2-15 km<br/>Urban: 2-5 km<br/>Rural: 10-15 km"]
        L2["Power: 10+ year battery<br/>Class A optimized<br/>Sleep: 1 µA"]
        L3["Data Rate: 0.3-50 kbps<br/>Payload: 243 bytes<br/>Adaptive SF7-12"]
        L4["Use Case:<br/>Smart agriculture<br/>Asset tracking<br/>Building automation"]
    end

    subgraph Sig["Sigfox Characteristics"]
        S1["Range: 10-50 km<br/>Urban: 3-10 km<br/>Rural: 30-50 km"]
        S2["Power: 15+ year battery<br/>Ultra-low duty cycle<br/>Sleep: 0.5 µA"]
        S3["Data Rate: 100 bps<br/>Payload: 12 bytes UL<br/>8 bytes DL"]
        S4["Use Case:<br/>Simple sensors<br/>Utility metering<br/>Logistics tracking"]
    end

    subgraph Cell["NB-IoT/LTE-M Characteristics"]
        C1["Range: Cellular coverage<br/>Indoor: Enhanced<br/>Licensed spectrum"]
        C2["Power: 10+ year battery<br/>PSM/eDRX modes<br/>Higher peak power"]
        C3["Data Rate: 250 kbps-1 Mbps<br/>Payload: Flexible<br/>IP-based"]
        C4["Use Case:<br/>Smart meters<br/>Fleet management<br/>Healthcare wearables"]
    end

    subgraph Compare["Technology Trade-offs"]
        T1["🏆 Best Range: Sigfox"]
        T2["🏆 Best Power: Sigfox"]
        T3["🏆 Best Data Rate: LTE-M"]
        T4["🏆 Best Flexibility: LoRaWAN"]
        T5["🏆 Best Coverage: NB-IoT"]
    end

    LoRa --> Compare
    Sig --> Compare
    Cell --> Compare

    style Header fill:#f9f9f9,stroke:#2C3E50
    style LoRa fill:#16A085,color:#fff
    style Sig fill:#E67E22,color:#fff
    style Cell fill:#2C3E50,color:#fff
    style Compare fill:#7F8C8D,color:#fff
    style L1 fill:#d4efdf,color:#2C3E50
    style L2 fill:#d4efdf,color:#2C3E50
    style L3 fill:#d4efdf,color:#2C3E50
    style L4 fill:#d4efdf,color:#2C3E50
    style S1 fill:#fdebd0,color:#2C3E50
    style S2 fill:#fdebd0,color:#2C3E50
    style S3 fill:#fdebd0,color:#2C3E50
    style S4 fill:#fdebd0,color:#2C3E50
    style C1 fill:#e8e8e8,color:#2C3E50
    style C2 fill:#e8e8e8,color:#2C3E50
    style C3 fill:#e8e8e8,color:#2C3E50
    style C4 fill:#e8e8e8,color:#2C3E50

Figure 1068.5: LPWAN technology positioning showing LoRaWAN (teal) balanced for flexibility with adaptive data rates and private network option, Sigfox (orange) optimized for ultra-low power and maximum range with constrained payload, NB-IoT/LTE-M (navy) leveraging cellular infrastructure for reliability and higher data rates. Trade-off summary shows each technology’s strengths. {fig-alt=“LPWAN technology comparison matrix. LoRaWAN in teal: 2-15 km range, 10+ year battery, 0.3-50 kbps adaptive, best for smart agriculture and building automation. Sigfox in orange: 10-50 km range, 15+ year battery, 100 bps with 12-byte payload, best for simple sensors and metering. NB-IoT/LTE-M in navy: cellular coverage, 10+ year battery with PSM, 250 kbps-1 Mbps, best for smart meters and fleet management. Summary: Best Range = Sigfox, Best Power = Sigfox, Best Data Rate = LTE-M, Best Flexibility = LoRaWAN, Best Coverage = NB-IoT.”}

1068.11 What’s Next

Continue to LPWAN Comparison and Review for a detailed comparison of different LPWAN technologies.