Capstone & Resources · Study deck
IoT Glossary: Terms From W Through Z
WebSockets keep one TCP link open for traffic in both directions.
Test Tessa is your guide for this deck.
After studying this chapter
Learning objectives
You will be able to:
- Test w with a concrete scenario and pass criteria.
- Validate match the wireless protocol to its key trait with a concrete scenario and pass criteria.
- test w with a concrete scenario and pass criteria
- validate match the wireless protocol to its key trait with a concrete scenario and pass criteria
Major section
Additional Reference Terms
In simple terms: Using cell phone networks for IoT - connecting devices through the same towers your phone uses, providing coverage almost anywhere without deploying your own network.
- Definition: Application of IoT technologies in industrial settings for manufacturing, energy, transportation, and other industrial processes, emphasizing reliability, safety, and interoperability.
- Definition: System responses occurring within defined time constraints, where data is processed and delivered within the deadline needed for action or feedback.
- In simple terms: How fast waves wiggle - measured in cycles per second, different frequencies are used for different purposes (2.4 GHz Wi-Fi, 915 MHz LoRa, etc.).
Major section
Worked Example: Selecting QoS Levels for a Multi-Sensor IoT System
Their different consequences and repetition rates are why one QoS setting cannot be assumed for the whole system.
- The numbers below are worksheet assumptions for comparing choices; replace them with measured radio current, broker logs, and failure costs in a real design.
- QoS level 0 provides at-most-once, fire-and-forget delivery.
- QoS level 1 provides acknowledged at-least-once delivery, but duplicates remain possible.
Major section
Worked Example: Selecting QoS Levels for a Multi-Sensor IoT System (continued)
System Overview:: Begin with the traffic classes: 30 temperature sensors report at 1-minute intervals, 15 vibration sensors report equipment-health data every 10 seconds, and 5 emergency-stop buttons send immediate alerts.
- Losing one isolated reading from this high-frequency trend may be acceptable only when aggregation, alerting, and data-quality rules tolerate gaps.
- Step 2: Vibration Monitoring: Vibration monitoring is predictive-maintenance evidence, so a missed high-vibration event could delay intervention; quantify that consequence from the asset and workflow.
- Tag each reading with a timestamp and sequence number, then use idempotency checks at the backend.
Major section
Worked Example: Selecting QoS Levels for a Multi-Sensor IoT System (continued)
Step 3: Emergency Stop Buttons: Life-safety commands need controlled execution, explicit acknowledgement, and a safe final state.
- QoS level 2 narrows duplicate delivery through the MQTT exactly-once exchange, but duplicate and missed-stop handling still belong in the application safety design.
- Step 4: Gateway Heartbeats: Gateway heartbeats are telemetry for online or offline health, sent every 60 seconds.
- If the stale-state policy accepts that detection interval, a lost heartbeat is replaced by the next scheduled observation.
- At QoS 0, the worksheet's 43,200 daily temperature messages require 43,200 MQTT transmission legs.
Major section
Worked Example: Selecting QoS Levels for a Multi-Sensor IoT System (continued)
The bounded decision is therefore QoS 0 for redundant, fire-and-forget pings, with the 60-second delay made visible to operators.
- Treating the four-step QoS 2 exchange as four legs would produce 172,800 legs, four times the simplified count.
- The glossary's "Common confusions" section for QoS emphasizes: "Higher QoS means more overhead and latency" - reserve QoS 2 only for irreplaceable commands.
- On those worksheet assumptions, choose QoS 0: one MQTT transmission per reading and no acknowledgement exchange, which reduces radio airtime relative to QoS 1 or QoS 2.
Major section
Common Mistake: Misunderstanding Time Series Database Requirements
The Problem: Students often say "I'll use InfluxDB" or "I'll use TimescaleDB" without understanding when a TSDB is actually needed.
- Step 1 — Wrong query shape for the index: A simple timestamp table can work, but long time-range aggregation may need partitioning, rollups, or a purpose-built store.
- Step 2 — No downsampling policy: Raw data kept forever can make old queries expensive when older data only needs hourly or daily summaries.
- Step 3 — No compression or retention plan: TSDBs often provide compression and retention controls that general tables need to be configured to match.
Major section
How These Terms Interconnect
Quality of Service Ecosystem:: QoS connects to at-least-once, at-most-once, exactly-once, idempotency, and retry logic.
- This chain shows how delivery semantics require specific design patterns.
- Database Decision Tree:: High-rate time series data often requires a TSDB.
- TSDB options: InfluxDB (purpose-built) vs TimescaleDB (SQL-based) Schema determines query patterns and storage efficiency.
Deck summary
Key takeaways
In simple terms: Using cell phone networks for IoT - connecting devices through the same towers your phone uses, providing coverage almost anywhere without deploying your own network.
- Their different consequences and repetition rates are why one QoS setting cannot be assumed for the whole system.
- System Overview:: Begin with the traffic classes: 30 temperature sensors report at 1-minute intervals, 15 vibration sensors report equipment-health data every 10 seconds, and 5 emergency-stop buttons send immediate alerts.
- Step 3: Emergency Stop Buttons: Life-safety commands need controlled execution, explicit acknowledgement, and a safe final state.
Retrieval practice
Recall check 1 of 2
Test Tessa says: answer from memory, then check your reasoning.
Q1A browser dashboard needs updates in both directions without repeated polling. Which glossary concept matches?
Show answer
Answer: C The glossary describes a persistent, full-duplex connection between web client and server.
Q2A home system has Zigbee devices and a proposed Z-Wave replacement. What should the glossary prevent the designer from assuming?
Show answer
Answer: B The glossary separates the two protocols despite their home-automation roles.
Retrieval practice
Recall check 2 of 2
Test Tessa says: answer from memory, then check your reasoning.
Q3Place each Q-Z glossary term where it governs the path so you can distinguish radio reach, delivery rules, and trusted records.
Show answer
Answer: A Follow a reading from wireless reach through topic and QoS rules into protected time-series evidence so you can connect Q-Z terms to a real message path.
Q4Complete the end-to-end IoT data pipeline:
Show answer
Answer: A The pipeline pattern chains processing stages sequentially.
Print reference
Answers
Answer key.
- C · The glossary describes a persistent, full-duplex connection between web client and server.
- B · The glossary separates the two protocols despite their home-automation roles.
- A · Follow a reading from wireless reach through topic and QoS rules into protected time-series evidence so you can connect Q-Z terms to a real message path.
- A · The pipeline pattern chains processing stages sequentially.