1072  LPWAN Assessment: Technology Selection

1072.1 Introduction

This chapter provides comprehensive assessment scenarios for LPWAN technology selection, including detailed analysis of real-world deployment decisions involving cost, scale, and technical constraints.

NoteLearning Objectives
  • Apply multi-criteria decision making for LPWAN technology selection
  • Analyze complex deployment scenarios with competing constraints
  • Calculate and compare Total Cost of Ownership across technologies
  • Understand spectrum allocation differences between LPWAN technologies

1072.2 Technology Selection Scenario

Complex deployment decisions require careful analysis of all constraints.

Question: A logistics company wants to deploy 10,000 asset trackers that report GPS location + temperature every 15 minutes (96 messages/day). Each message payload is 45 bytes. Battery life must exceed 3 years. They’re evaluating LoRaWAN vs Sigfox. Which technology should they choose and why?

This demonstrates LPWAN technology selection based on application constraints:

From the text - LoRaWAN vs Sigfox:

LoRaWAN: - Data rate: 0.3-50 kbps (adaptive) - Max Payload: 243 bytes - Messages/Day: Unlimited (duty cycle limited) - Battery Life: 5-10 years

Sigfox: - Data rate: 100 bps uplink, 600 bps downlink - Max Payload: 12 bytes (uplink) - Messages/Day: 140 uplink, 4 downlink (hard limit) - Battery Life: 10-20 years

Application Requirements vs Technology Capabilities:

Requirement Value LoRaWAN Sigfox Result
Messages/day 96 Unlimited Max 140 Sigfox barely OK
Payload size 45 bytes 243 max 12 max Sigfox FAILS
Battery life 3+ years 5-10 yr 10-20 yr Both OK
Device count 10,000 Scalable Scalable Both OK
Bi-directional Yes (GPS) A/B/C Limited LoRaWAN better

Critical Failure Analysis:

The 45-byte payload requirement for GPS tracker data cannot fit in Sigfox’s 12-byte maximum:

Field Bytes Purpose
GPS Lat 4 Latitude coordinate
GPS Lon 4 Longitude coordinate
Altitude 2 Height above sea level
Speed 2 Movement speed
Heading 2 Direction of travel
Temperature 2 Sensor reading
Battery 1 Remaining charge
Device ID 4 Identification
Timestamp 4 Reading time
Status Flags 2 Device status
Checksum 2 Data integrity
Total 29+ bytes Minimum GPS payload

Even with extreme compression, the fundamental data requirements exceed Sigfox’s 12-byte limit.

Battery Life Calculation (SF7, 45-byte payload, 96 msg/day):

Component Value Calculation
TX current 120 mA During transmission
TX time 200 ms 45 bytes at SF7
TX per day 96 Every 15 minutes
TX energy/day 0.64 mAh (120 mA x 0.2s / 3600s) x 96
Sleep current 5 uA Deep sleep mode
Sleep energy/day 0.12 mAh (5 uA / 1000) x 24h
Total daily 0.76 mAh/day TX + Sleep
Battery capacity 2400 mAh 2x AA lithium batteries
Battery life 8.6 years 2400 / (0.76 x 365)
vs Requirement 2.9x margin Exceeds 3-year requirement

Summary - Why LoRaWAN is the only choice:

  1. Payload: 45 bytes fits in LoRaWAN (243 max) but exceeds Sigfox (12 max) - DEAL BREAKER
  2. Messages: 96/day well within LoRaWAN capacity, marginal on Sigfox
  3. Battery: Both exceed 3-year requirement
  4. Flexibility: LoRaWAN allows future expansion, Sigfox is maxed out
  5. Downlinks: LoRaWAN unlimited, Sigfox only 4/day

The payload constraint alone eliminates Sigfox, making LoRaWAN the only viable LPWAN option for this application.

1072.3 Large-Scale Cost Analysis

Understanding TCO at scale is critical for enterprise deployments.

Question: A water utility plans to deploy 50,000 smart water meters across a region. Each meter sends one reading per day (24 bytes). Comparing 5-year TCO: Private LoRaWAN costs 1,500 EUR/gateway x 30 gateways + 15 EUR/sensor + 300 EUR/month network server. NB-IoT costs 20 EUR/sensor + 1.50 EUR/device/month data plan. What is the approximate cost difference favoring the cheaper option?

This demonstrates LPWAN TCO analysis for large-scale deployments:

Complete Cost Breakdown:

Private LoRaWAN costs

  • Initial investment (Year 1):

    Component Calculation Cost
    Gateways 30 x 1,500 EUR 45,000 EUR
    Sensors 50,000 x 15 EUR 750,000 EUR
    Installation (estimate) - 100,000 EUR
    Total initial 895,000 EUR

  • Recurring costs (Years 1-5):

    Component Calculation Cost
    Network server 300 EUR/month x 12 x 5 18,000 EUR
    Maintenance 5,000 EUR/year x 5 25,000 EUR
    Total 5-year recurring 43,000 EUR

5-year total cost of ownership (TCO): 895,000 + 43,000 = 938,000 EUR.

NB-IoT (cellular) costs

  • Initial investment (Year 1):

    Component Calculation Cost
    Sensors 50,000 x 20 EUR 1,000,000 EUR
    Installation (estimate) - 100,000 EUR
    Total initial 1,100,000 EUR

  • Recurring costs (Years 1-5):

    Component Calculation Cost
    Data plan 50,000 devices x 1.50 EUR/month x 12 x 5 4,500,000 EUR

5-year total cost of ownership (TCO): 1,100,000 + 4,500,000 = 5,600,000 EUR.

Cost comparison

Technology 5-year TCO Breakdown
Private LoRaWAN 938,000 EUR 895k initial + 43k recurring
NB-IoT cellular 5,600,000 EUR 1.1M initial + 4.5M recurring

Difference: 5,600,000 - 938,000 = 4,662,000 EUR - NB-IoT costs significantly more.

Year-by-Year Cost Analysis (Cumulative TCO):

Year LoRaWAN TCO NB-IoT TCO Difference LoRaWAN Savings
1 903,600 EUR 2,000,000 EUR 1,096,400 EUR 54% cheaper
2 912,200 EUR 2,900,000 EUR 1,987,800 EUR 69% cheaper
3 920,800 EUR 3,800,000 EUR 2,879,200 EUR 76% cheaper
4 929,400 EUR 4,700,000 EUR 3,770,600 EUR 80% cheaper
5 938,000 EUR 5,600,000 EUR 4,662,000 EUR 83% cheaper

Key Insight: LoRaWAN’s cost advantage grows over time due to minimal recurring costs (8.6k EUR/year) vs NB-IoT’s massive subscriptions (900k EUR/year).

Cost Per Device Analysis (50,000 devices):

Metric LoRaWAN NB-IoT Ratio
Total 5-year TCO 938,000 EUR 5,600,000 EUR 6.0x
Cost per device (5yr) 18.76 EUR 112.00 EUR 6.0x
Cost per device per year 3.75 EUR 22.40 EUR 6.0x
Cost per device per month 0.31 EUR 1.87 EUR 6.0x

Conclusion: NB-IoT costs 6x more per device due to recurring subscription fees.

Why the Difference is So Large:

Cost Type LoRaWAN (5yr) NB-IoT (5yr) Difference % of Total Diff
Initial hardware 895,000 EUR 1,100,000 EUR 205,000 EUR (NB-IoT more) 4%
Recurring (5yr) 43,000 EUR 4,500,000 EUR 4,457,000 EUR 96%
Total TCO 938,000 EUR 5,600,000 EUR 4,662,000 EUR 100%

Analysis: 96% of cost difference comes from recurring subscription fees. The larger the scale and longer the timeframe, the more dominant LoRaWAN’s cost advantage becomes.

1072.4 Spectrum Allocation Understanding

Question: An IoT architect must explain LPWAN spectrum allocation to stakeholders. Which statement is MOST accurate regarding LPWAN spectrum usage?

Option B is correct - LPWAN technologies split between spectrum types:

Unlicensed ISM Bands (LoRaWAN, Sigfox): - Regions: - EU: 868 MHz (863-870 MHz) - US: 915 MHz (902-928 MHz) - Asia: 923 MHz (920-925 MHz) - Advantages: - No spectrum licensing fees - No recurring regulatory costs - Freely deployable private networks - Disadvantages: - Duty cycle restrictions (1% EU, listen-before-talk US) - Interference from other ISM users (industrial equipment, home automation) - No QoS guarantees - Power limits (14 dBm EU, 30 dBm US)

Licensed Cellular Spectrum (NB-IoT, LTE-M): - Bands: LTE bands (700, 800, 900, 1800, 2100, 2600 MHz) - Advantages: - Protected spectrum (no interference) - Guaranteed QoS and SLAs - Higher allowed transmit power (23 dBm) - No duty cycle restrictions - Disadvantages: - Requires cellular subscription (2-10 EUR/device/month) - Carrier-dependent (no private network option) - Spectrum auction costs passed to consumers

Why A is wrong: NB-IoT and LTE-M do NOT use ISM bands.

Why C is wrong: LoRaWAN and Sigfox use unlicensed, not licensed.

Why D is wrong: Spectrum licensing has no inherent relationship to coverage - it depends on frequency (lower is generally better), power, and modulation.

Strategic implication: Choose unlicensed (LoRaWAN) for private networks with zero recurring costs, or licensed (NB-IoT) for carrier-managed networks with guaranteed QoS.

1072.5 Agricultural Deployment Scenario

Question: A company evaluates LPWAN options for 10,000 remote agricultural sensors across 200 sq km. Each sensor reports soil data (50 bytes) twice daily for 10 years. Cellular coverage exists but is spotty. They can install infrastructure on water towers and grain silos. What is the MOST cost-effective strategy?

Private LoRaWAN (C) is most cost-effective at this scale:

Cost Analysis:

LoRaWAN (Private): - Sensors: 10,000 x $15 = $150,000 - Gateways: 200 sq km / 4 sq km per gateway = 50 gateways x $1,500 = $75,000 - Network server: $5,000/year x 10 years = $50,000 - Total: $275,000 over 10 years

Sigfox (Operator): - Sensors: 10,000 x $10 = $100,000 - Subscription: 10,000 x $6/year x 10 years = $600,000 - Total: $700,000 (2.5x more than LoRaWAN)

NB-IoT (Cellular): - Sensors: 10,000 x $20 = $200,000 - Subscription: 10,000 x $24/year x 10 years = $2,400,000 - Total: $2,600,000 (9.5x more than LoRaWAN!)

Why LoRaWAN wins: 1. Infrastructure control - Company owns water towers and grain silos (perfect gateway locations) 2. Zero recurring costs - No subscriptions after initial deployment 3. Scale economics - At 10,000 devices, gateway cost ($75k) amortizes to $7.50/device 4. Coverage - 200 sq km rural area well-suited for LoRa’s 15km range 5. 10-year lifespan - Private network costs are upfront; cellular costs compound annually

Hybrid approach (D) would cost more than pure LoRaWAN while adding complexity. Since they can install gateways on existing structures, achieving 100% LoRaWAN coverage is feasible.

ROI calculation: LoRaWAN saves $425k-$2.3M over alternatives. Payback period: Immediate (no recurring costs vs. $60k-$240k/year for alternatives).

1072.6 Summary

This technology selection assessment covered:

  • Complex Deployment Scenarios: Analyzing GPS tracker requirements against LoRaWAN and Sigfox constraints
  • Enterprise TCO Analysis: Understanding cost dynamics for 50,000+ device deployments
  • Spectrum Considerations: Licensed vs unlicensed spectrum trade-offs
  • Agricultural Use Cases: Optimizing for long-term, large-scale rural deployments

Key Takeaways: - Payload constraints can eliminate technologies regardless of other advantages - Recurring subscription costs dominate cellular IoT TCO at scale - Private networks become economical at ~1,000+ devices with 5+ year deployments - Infrastructure availability (towers, silos) enables cost-effective private network coverage

1072.7 What’s Next

Continue your LPWAN assessment with: