CIoTP flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Latency budget formula

End-to-end latency equals sensor sampling period plus network transit time across hops plus processing and queueing plus actuation time. Use worst-case values for safety-critical control paths.

Battery life estimate

Divide battery capacity in mAh by average current in mA, where average current weights active and sleep currents by their duty cycle. Derate the result for temperature and cell aging.

Data volume sizing

Bytes per day equals payload bytes times samples per day times device count. This figure sizes backhaul bandwidth, storage retention, and cloud ingest charges during planning.

Total cost of ownership

Sum hardware, installation labor, connectivity subscriptions, cloud and storage fees, and maintenance visits over the depreciation period. Retrofit installation often exceeds device hardware cost.

Requirement triage

Separate functional requirements such as sensing rate and actuation latency from non-functional constraints such as power, cost, size, and environmental rating before selecting any hardware.

IoT risk register

A list of identified risks such as single gateway failure, firmware end-of-life, spectrum congestion, and physical tampering, each with a mitigation and a named owner.

MQTT QoS levels

QoS 0 is at-most-once with no acknowledgment. QoS 1 is at-least-once and may duplicate. QoS 2 is exactly-once with extra handshake overhead. Choose per message criticality.

MQTT retained message

A message the broker stores on a topic and delivers immediately to any new subscriber. It provides last known state without waiting for the next device publish.

MQTT last will

A message the broker publishes on a device's behalf when the connection drops ungracefully. Commonly used to flag offline status to monitoring subscribers.

CoAP protocol facts

CoAP runs over UDP, uses confirmable and non-confirmable messages, supports an observe option for push notifications and block-wise transfer for large payloads, and secures with DTLS.

Protocol selection rule

Use MQTT for many-to-broker telemetry over TCP, CoAP for constrained UDP devices, LoRaWAN or NB-IoT for long-range low-power links, and BLE or Thread for short-range use.

Edge versus cloud split

Place safety interlocks, closed-loop control, and bandwidth-heavy filtering at the edge. Place long-term analytics, cross-site correlation, and model training in the cloud.

IoT security baseline

Unique per-device credentials, mutual TLS or DTLS, encryption in transit and at rest, signed OTA images, least-privilege broker ACLs, and segmented IoT network VLANs.

Topic hierarchy design

Structure topics as site, building, device type, device ID, then measurement. Design subscriptions to avoid broad wildcards that force the broker to fan out excessively.

Idempotent message handling

Handlers tolerate duplicate and out-of-order delivery by carrying device timestamp and sequence number in the payload, so reprocessing the same message yields the same state.

Firmware partition layout

A typical layout has a bootloader with secure boot verification, an application slot, an OTA staging slot, and a persistent configuration store using wear leveling.

Nyquist sampling rule

Sample faster than twice the highest frequency of interest in the signal. Undersampling aliases higher frequencies into the measured band and corrupts derived analytics.

Compact payload encoding

CBOR, protobuf, or packed binary structs reduce payload size versus JSON on constrained links. A JSON float can cost ten or more bytes against four bytes binary.

Local buffering policy

When connectivity drops, queue telemetry to non-volatile storage in a circular buffer with a defined drop policy, usually oldest-first, to bound storage use.

Command idempotency token

Downlink commands carry a unique command ID and expiry so that retries do not double-actuate a relay or valve after a lost acknowledgment.

Hardware-in-the-loop testing

Tests that run firmware on real or simulated hardware against sensor drivers and protocol peers, exercising timing, bus behavior, and recovery that host unit tests cannot cover.

Time synchronization approach

Devices sync via NTP or GPS, store timestamps in UTC with a monotonic sequence number, and let the platform convert to local time for display.

Staged firmware rollout

Deploy signed firmware to canary devices first, verify health checks, then expand in cohorts while retaining the previous known-good image for rollback.

Device provisioning sequence

Create identity, inject credentials into a secure element or encrypted store, join the network, register the device, then assign it to a site or tenant.

Commissioning acceptance checks

Verify RF signal strength at the mounted position, supply voltage, time sync, round-trip latency to the broker, and successful publish and subscribe on each required topic.

Gateway placement rule

Mount gateways above obstructions with antenna clearance and confirm coverage using a post-installation site survey rather than trusting the original design model.

Zero-touch enrollment

Devices self-register using a bootstrap claim certificate or manufacturer serial allowlist, and the bootstrap credential is revoked after first successful enrollment.

IoT network segmentation

Place IoT devices and management interfaces on separate VLANs, allowing only required outbound ports such as 8883 for MQTT over TLS and 5684 for CoAP over DTLS.

Pilot before scale

Commission a small representative site, compare measured latency and power against the plan, then expand in batches each gated by an acceptance checklist.

Dead-man heartbeat alert

Alert when expected data stops arriving within a timeout window, rather than waiting for an error code, because silent device failure is the most common IoT fault.

Credential rotation and revocation

Rotate certificates and keys on a defined schedule, revoke compromised identities in both registry and broker ACLs, and audit for default or shared credentials.

Telemetry retention tiers

Keep raw telemetry for a short window and aggregated rollups for the long term. Tiering controls storage cost while preserving trend analysis.