HCIA-IoT cheat sheet

IoT definition: physical objects with sensing, actuation, and network interfaces that exchange data over networks with minimal human intervention.

Four-layer reference architecture: perception/device layer (sensors, actuators), network layer (access and transport), platform/service layer (device management, data analytics), application layer (industry solutions).

Alternative three-layer view collapses platform and application into one 'application layer'; Huawei-oriented material often uses device, network, platform, and application layers.

Edge computing places compute near the data source to cut latency and backhaul traffic; cloud handles elastic storage and large-scale analytics.

Key IoT characteristics: massive connections, low data rate per device, low power consumption, often low mobility, and heterogeneous protocols.

Terminal classes: passive (no battery, e.g. RFID tags), semi-active, and active (battery-powered, e.g. NB-IoT modules).

M2M vs IoT: M2M is point-to-point machine communication; IoT adds cloud platforms, analytics, and application enablement.

Architecture design rule: choose the network technology after fixing device power budget, data rate, latency, and coverage requirements.

Short-range: Bluetooth/BLE (~10 m, 1-2 Mbps), Zigbee (IEEE 802.15.4, 2.4 GHz, mesh, low power), Wi-Fi (IEEE 802.11, high rate, higher power).

LPWA categories: NB-IoT and LTE-M are licensed-spectrum cellular; LoRa, Sigfox, and RPMA are unlicensed or proprietary.

NB-IoT: 180 kHz bandwidth, uplink single-tone or multi-tone, ~20-25 dB link budget gain over GSM, no connected-mode handover, supports massive connections per cell.

NB-IoT user-plane options: CP (control plane) CIoT optimization carries small data without a data radio bearer; UP option uses a data bearer with suspend/resume.

LoRa physical layer uses chirp spread spectrum; spreading factor SF7-SF12 trades data rate against range and time-on-air.

LoRaWAN device classes: A (bidirectional, two receive windows after uplink), B (scheduled beacon receive windows), C (continuous receive).

CoAP runs over UDP with a 4-byte header and methods GET/POST/PUT/DELETE; MQTT runs over TCP with publish/subscribe and QoS 0, 1, 2.

Selection rule: high data rate and mains power favor Wi-Fi or Ethernet; years of battery life at low rate favors NB-IoT, LoRa, or Zigbee.

IPv4 has 32-bit addresses; IPv6 has 128-bit addresses, providing enough space for massive IoT device addressing.

6LoWPAN adapts IPv6 to IEEE 802.15.4 by header compression and fragmentation of packets to the 127-byte frame payload.

RPL is an IPv6 distance-vector routing protocol for low-power lossy networks; it builds a DODAG rooted at a border router.

CoAP observation lets a client register interest in a resource so the server pushes state changes without repeated polling.

MQTT topic wildcards: single-level '+' and multi-level '#'; a broker routes messages based on topic filters.

Cellular attach flow: PLMN selection, random access, RRC connection setup, authentication and security, then PDN/PDU session establishment.

NAT and private addressing break end-to-end reachability; IoT platforms often use brokers, gateways, or IPv6 to restore addressing.

Gateway functions: protocol translation (e.g. Modbus to MQTT), local buffering, edge pre-processing, and device authentication.

Platform core functions: device access and registration, device management, data storage, rule engine, application enablement (APIs), and operations/monitoring.

Device lifecycle states typically include register, activate/online, offline, deactivate, and deregister; commands only reach online devices.

Profile model: product model defines services, properties (reported/desired), commands, and events; each device instance carries a unique device ID and secret.

Device bootstrap: authenticate with device ID and secret or certificate, obtain an access token, then establish MQTT/CoAP/HTTP session.

Shadow/device twin stores last reported state and desired state so applications can read state while a device is offline.

OTA upgrade flow: create upgrade package, create upgrade task, select target devices, push notification, device downloads, verifies, installs, reports result.

Rule engine: trigger (device data or event) plus condition plus action (forward to another topic, database, or application) enables no-code data routing.

Northbound APIs serve applications (device CRUD, command delivery, data query); southbound interfaces connect devices via gateways or direct access.

Security triad: confidentiality (encryption), integrity (MAC/hash), availability (resilience to DoS); authentication and non-repudiation are added goals.

Symmetric algorithms: AES for bulk encryption, HMAC-SHA for integrity; asymmetric: RSA, ECC for key exchange and signatures; hashes: SHA-256.

TLS secures MQTT/HTTP/CoAP sessions; DTLS provides the equivalent for UDP-based CoAP.

Device identity options: pre-shared key, X.509 certificate, or hardware root of trust (secure element/TPM) that stores keys unextractable.

Key risks: default or hardcoded credentials, weak random number generation, unencrypted local buses, missing firmware signature verification.

Layered defense: device hardening, secure onboarding, network segmentation, platform access control (RBAC), and audit logging.

Secure boot verifies firmware signature at each boot; secure OTA adds package signing and rollback protection.

Privacy and compliance: minimize collected personal data, encrypt data at rest and in transit, and follow regional data-protection rules.

Smart home: BLE/Zigbee/Wi-Fi devices, gateway-centric control, voice assistants, and cloud scene automation.

Smart metering: NB-IoT or PLC meters report readings periodically; key requirements are deep coverage (basements), low power, and massive scale.

Smart city: street lighting, parking, waste bins, and environmental monitoring; typical technologies are NB-IoT and LoRa with a city platform.

Industrial IoT: low-latency deterministic links (TSN, industrial Ethernet, 5G uRLLC) for closed-loop control; predictive maintenance uses vibration and temperature sensing.

Connected vehicle: V2X (IEEE 802.11p or C-V2X), cellular telematics, and fleet management; latency and reliability drive technology choice.

Smart agriculture: soil moisture and climate sensors over LoRa/NB-IoT in wide rural coverage; irrigation actuation closes the loop.

Healthcare IoT: wearable vital-sign monitoring needs low power and privacy protection; hospital asset tracking often uses BLE or RFID.

Solution selection rule: map coverage, mobility, data rate, latency, power, and cost constraints to a technology before choosing a platform.