IoT Fundamentals · Study deck

Protocol Selector Wizard

A field monitor must report a water level for two years on one battery.

Physics Phoebe is your guide for this deck.

protocolselectorwizard
Physics Phoebe, the module guide, in a scene from this chapter.
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After studying this chapter

Learning objectives

You will be able to:

  • Systematically evaluate IoT protocol options against your project requirements using weighted scoring criteria
  • Analyse trade-offs between range, power, bandwidth, latency, and cost for competing protocol families
  • Select and justify a connectivity stack for a given IoT deployment scenario with quantitative reasoning
  • Compare protocols side-by-side by mapping detailed technical specifications to application constraints
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Major section

In 60 Seconds · Start With the Story · Protocol Selector Wizard

A field monitor must report a water level for two years on one battery.

  • It sits behind a stone wall and has no nearby mains power.
  • The project meeting begins with a favourite technology, but the site has already set the real rules.

Key terms

No single protocol
No single protocol is "best" -- the optimal choice depends on your specific constraints, and the most important first filter is usually range (short vs.
Use the wizard flow as an evidence checklist, not just a scoring form.
Use the wizard flow as an evidence checklist, not just a scoring form.
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Major section

Key Concepts · For Beginners: What is Protocol Selection? · Tool Components

Rationale matters: A strong selection rationale explains why finalists were chosen and why others were rejected.

  • No universal winner: The best protocol is the one that fits this deployment, not the one with the strongest headline specification.
  • Quick Check: Wizard Limits.
  • Reliability = More overhead: Like insurance - costs more but protects you.
Use the wizard flow as an evidence checklist, not just a scoring form.
Use the wizard flow as an evidence checklist, not just a scoring form.
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Major section

Quick Decision Guide · Put Numbers to the Decision

where rir_iri​ is a normalized rating (0 to 1) for each criterion (range, power, bandwidth, latency, cost).

  • The 0.26 score gap quantifies why LoRaWAN is favored for long-life telemetry even though Wi-Fi wins on raw bandwidth.
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Major section

Worked Example: Use the Decision Guide for a Real Project

All component prices, currents, ranges, airtimes, and link counts below are worksheet assumptions, not vendor specifications or a validated site survey.

  • Latency sensitivity: No, hourly data is fine.
  • Infrastructure: Farm has Wi-Fi in the barn (100m away).
  • Implication: existing Wi-Fi could help, but only near the barn.

Key terms

But 200m
But 200m is overkill for LPWAN.

Why it matters

Wooden hive boxes allow signal penetration better than concrete.

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Major section

Worked Example: Use the Decision Guide for a Real Project (continued)

Alternative from table: "Long range (km) + Battery (years)" → Consider: LoRaWAN, Sigfox, NB-IoT: But 200m is overkill for LPWAN.

  • Barn Wi-Fi reaches ~50m.
  • A real Wi-Fi transmitter may draw much more; measure wake, association, and transmit current.
  • No recurring costs (unlike NB-IoT).
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Major section

Worked Example: Use the Decision Guide for a Real Project (continued)

Step 2: Apply Quick Guide Rules: From table: "Short range (m) + Battery life" → Consider: BLE, Zigbee, Thread: But wait -- 200m exceeds typical direct BLE range (10-50m) and Zigbee/Thread range (10-100m).

  • A 2000 mAh battery and 1W solar panel need a site-specific winter energy budget before viability can be claimed.
  • Cost: $15 hardware + $10 gateway share + $10 solar/battery = $35/hive (over budget).
  • Avg 4 hops to reach barn (50m per hop × 4 = 200m).
  • Cost: $11 hardware + $0.50 coordinator share + $8 solar/battery = $19.50/hive (within budget).
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Major section

Worked Example: Use the Decision Guide for a Real Project (continued)

A Zigbee router must also remain available to receive and forward traffic; this sleep model cannot predict its real battery life.

  • Four 50m hops could cover 200m if each link passes a site test.
  • Solar and battery sizing require measured router receive current, winter yield, and battery losses; the worksheet's ~0.10 mAh/day omits these loads.
  • Mesh can provide alternate paths if the topology and router availability support them.
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Major section

Worked Example: Use the Decision Guide for a Real Project (continued)

Key Lesson: The quick decision guide gives starting points, but real projects require measured link and energy budgets.

  • A 200m route may favor a mesh or an LPWAN link depending on obstruction, router power, gateway cost, and winter solar yield.
  • Interactive worksheet (illustrative currents only):: This arithmetic omits Wi-Fi association, LoRaWAN receive windows, Zigbee router listening, retries, usable capacity, aging, and solar harvest.
  • Wooden hive boxes allow signal penetration better than concrete.
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Major section

Common Pitfalls · Practice the Selection Workflow

Relying on theoretical models without profiling actual behavior can lead to designs that miss performance targets.

  • Optimizing one parameter in isolation (latency, throughput, energy) without considering impact on others creates systems that excel on benchmarks but fail in production.
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Major section

Scenario Requirements Move the Protocol Answer · Summary · Match the Scenario to the Protocol

The best way to internalize protocol selection is to run the same method on concrete scenarios and watch the answer change with the requirements.

  • A selector wizard asks about range, payload, power, latency, topology, mobility, and operations, then steers toward the technology whose compromises fit.
  • LoRa Larry is perfect.

Why it matters

This ordering matters because weighted scoring can hide a fatal constraint if a failed candidate keeps competing.

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Deck summary

Key takeaways

A field monitor must report a water level for two years on one battery.

  • Rationale matters: A strong selection rationale explains why finalists were chosen and why others were rejected.
  • where rir_iri​ is a normalized rating (0 to 1) for each criterion (range, power, bandwidth, latency, cost).
  • All component prices, currents, ranges, airtimes, and link counts below are worksheet assumptions, not vendor specifications or a validated site survey.
  • Alternative from table: "Long range (km) + Battery (years)" → Consider: LoRaWAN, Sigfox, NB-IoT: But 200m is overkill for LPWAN.
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Retrieval practice

Recall check 1 of 5

Physics Phoebe says: answer from memory, then check your reasoning.

Q1How should a learner use the protocol selector wizard responsibly?

AKeep default weights because the standard scoring already reflects battery and coverage costs.
BTreat the highest score as final proof that the protocol will survive deployment
CPick the newest radio family and use the wizard only to justify that prior decision
DShortlist, then test range, power, cost and risk on site.
Show answer

Answer: D A wizard is a decision aid; the engineering assumptions still need validation.

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Retrieval practice

Recall check 2 of 5

Physics Phoebe says: answer from memory, then check your reasoning.

Q2A farmer needs soil moisture data from sensors spread across 50 acres, sending one reading every 30 minutes on battery. Which protocol family is most appropriate?

AWi-Fi, because it has high bandwidth and farm routers are easy to extend across open fields
BBluetooth LE, because it is low power and many small sensor boards already support it
C5G cellular, because it has wide-area coverage and strong throughput for modern devices
DLPWAN such as LoRaWAN, because it provides long range, low power, and low data rate
Show answer

Answer: D The requirements -- long range, battery-powered devices, and infrequent small readings -- match the Quick Decision Guide row for long range plus battery life.

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Retrieval practice

Recall check 3 of 5

Physics Phoebe says: answer from memory, then check your reasoning.

Q3What weighted comparison explains why one feasible protocol fits priorities better than another?

ADefine Constraints
BScore Finalists
CFilter Must-Haves
DValidate Choice
Show answer

Answer: B Weighted criteria expose why one feasible protocol fits the priorities better than another.

Q4A livestock tracker on a 50km² ranch sends a 20-byte GPS update every 10 minutes, must last 2+ years on an AA battery, and cannot rely on cellular. Which protocol family should you evaluate first?

ABluetooth 5 mesh or long-range links
BWi-Fi HaLow for sub-GHz IP coverage
CZigbee mesh for low-power local networking
DLoRaWAN for multi-km, low-power telemetry
Show answer

Answer: D The first filters are range and battery life, and both point to LPWAN.

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Retrieval practice

Recall check 4 of 5

Physics Phoebe says: answer from memory, then check your reasoning.

Q5Why is there no single best IoT protocol?

AManufacturers have not yet agreed on one global standard that every IoT product must use
BOnly expensive protocols can meet field requirements for range, power, bandwidth, and cost
CDifferent applications have conflicting requirements for range, power, bandwidth, and cost
DIoT is too new for mature protocols to cover real deployments across industries
Show answer

Answer: C No protocol optimizes every dimension at once.

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Retrieval practice

Recall check 5 of 5

Physics Phoebe says: answer from memory, then check your reasoning.

Q6A smart building needs real-time occupancy video analytics from 20 cameras across 3 floors, all connected to mains power. Which protocol is most suitable?

ALoRaWAN for video streams
BWi-Fi for powered video
CNFC for camera networking
DZigbee for video backhaul
Show answer

Answer: B Video analytics makes throughput the dominant constraint, and mains power makes Wi-Fi a reasonable first candidate.

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Print reference

Answers 1 of 2

Answer key.

  1. D · A wizard is a decision aid; the engineering assumptions still need validation.
  2. D · The requirements -- long range, battery-powered devices, and infrequent small readings -- match the Quick Decision Guide row for long range plus battery life.
  3. B · Weighted criteria expose why one feasible protocol fits the priorities better than another.
  4. D · The first filters are range and battery life, and both point to LPWAN.
  5. C · No protocol optimizes every dimension at once.
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Print reference

Answers 2 of 2

Answer key.

  1. B · Video analytics makes throughput the dominant constraint, and mains power makes Wi-Fi a reasonable first candidate.
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