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CS-803 (C) · Internet of Things/Quick Revision Short Notes

Internet of Things (CS-803 (C)) - Unit 3 Short Notes

How unit 3 is examined

This unit covers the networking layer of IoT: functional components, SOA, challenges, the short-range wireless technologies (6LoWPAN, ZigBee, RFID, NFC, Bluetooth) and wireless sensor networks. Every past question is a 7-mark "explain", so ZigBee, functional components, NFC, WSN and SDN carry the marks.

Basics of IoT Networking

<span style="display:inline-block;padding:.16em .6em;border:1.5px solid currentColor;border-radius:999px;font-size:.68em;font-weight:700;letter-spacing:.06em;text-transform:uppercase;opacity:.75">Not asked since 2022</span>

Definition. <mark>IoT networking is the set of protocols, links and devices that let constrained things (sensors, actuators, tags) exchange data with each other, with gateways and with the cloud over wired or wireless links.</mark>

Key points.

  1. IoT devices are constrained in power, memory and bandwidth, so they use low-power links such as 802.15.4, BLE and NFC instead of Wi-Fi or Ethernet.
  2. Data flows from device to gateway to internet to cloud, and commands flow back the same way.
  3. Software defined networking (SDN) separates the control plane (routing decisions, in a central controller) from the data plane (forwarding, in switches), which suits large IoT networks.
  4. SDN benefits to IoT: centralised management of thousands of devices; programmability, so policies change by software without touching hardware; agility, since new devices and traffic flows are provisioned quickly; lower cost, because cheap forwarding switches replace complex routers; and scalability, since the controller sees the whole network.
  5. SDN helps IoT specifically through dynamic routing around congestion or failed nodes, better resource management (bandwidth given to critical flows), and security, because the controller can isolate a compromised device at once. Example: a smart-city controller reroutes traffic-sensor data when a link fails.

Asked: [7 marks] (May 2023) What are the benefits provided by SDN (software defined networking) to IoT.

IoT Components, Functional components of IoT

<span style="display:inline-block;padding:.16em .6em;border:1.5px solid currentColor;border-radius:999px;font-size:.68em;font-weight:700;letter-spacing:.06em;text-transform:uppercase;opacity:.75">Low weight</span>

Definition. <mark>The functional components of IoT are the building blocks that together sense the physical world, communicate the data, process it, present it to applications and keep it secure.</mark>

Diagram. <figure class="ds-fig" style="margin:1.4rem 0;overflow-x:auto"><svg xmlns="http://www.w3.org/2000/svg" id="dsfig-u3-01" viewBox="0 0 467 209" width="467" height="209" role="img" aria-label="Functional components: Sen = sensing and actuation, Com = communication, Pro = processing and storage, App = application, Sec = security spanning all"><style>#dsfig-u3-01 .e{stroke:#454C5A;stroke-width:1.4;fill:none}#dsfig-u3-01 .e.hi{stroke:#2340B8;stroke-width:2.6}#dsfig-u3-01 .n{fill:#FFFFFF;stroke:#16181D;stroke-width:1.4}#dsfig-u3-01 .n.hi{fill:#E3E9FC;stroke:#2340B8;stroke-width:2.2}#dsfig-u3-01 .n.rb-b{fill:#16181D;stroke:#16181D}#dsfig-u3-01 .n.rb-r{fill:#BD3227;stroke:#BD3227}#dsfig-u3-01 text{font-family:"JetBrains Mono",ui-monospace,Menlo,Consolas,monospace;font-size:13px}#dsfig-u3-01 .t{fill:#16181D;font-weight:500}#dsfig-u3-01 .t.inv{fill:#FFFFFF;font-weight:700}#dsfig-u3-01 .kd{stroke:#16181D;stroke-width:1.2}#dsfig-u3-01 .dot{fill:#16181D}#dsfig-u3-01 .ann{fill:#2340B8;font-size:11px;font-weight:700}#dsfig-u3-01 .lbl{fill:#6F7787;font-family:system-ui,-apple-system,sans-serif;font-size:12px;font-weight:700}#dsfig-u3-01 .ptr{fill:#2340B8;font-size:12px;font-weight:700}#dsfig-u3-01 .ah{fill:#454C5A}#dsfig-u3-01 .ah.hi{fill:#2340B8}#dsfig-u3-01 .wl rect{fill:#FFFFFF;stroke:#DCE0E7}#dsfig-u3-01 .wl .t{font-size:12px;font-weight:700}#dsfig-u3-01 .wl.hi rect{fill:#2340B8;stroke:#2340B8}#dsfig-u3-01 .wl.hi .t{fill:#FFFFFF}html.dark #dsfig-u3-01 .e{stroke:#B1B7C3}html.dark #dsfig-u3-01 .e.hi{stroke:#8FA3FF}html.dark #dsfig-u3-01 .n{fill:#161920;stroke:#E6E8ED}html.dark #dsfig-u3-01 .n.hi{fill:#1E2748;stroke:#8FA3FF}html.dark #dsfig-u3-01 .n.rb-b{fill:#E6E8ED;stroke:#E6E8ED}html.dark #dsfig-u3-01 .n.rb-r{fill:#FF7E71;stroke:#FF7E71}html.dark #dsfig-u3-01 .t{fill:#E6E8ED}html.dark #dsfig-u3-01 .t.inv{fill:#0F1115}html.dark #dsfig-u3-01 .kd{stroke:#E6E8ED}html.dark #dsfig-u3-01 .dot{fill:#E6E8ED}html.dark #dsfig-u3-01 .ann{fill:#8FA3FF}html.dark #dsfig-u3-01 .lbl{fill:#858D9C}html.dark #dsfig-u3-01 .ptr{fill:#8FA3FF}html.dark #dsfig-u3-01 .ah{fill:#B1B7C3}html.dark #dsfig-u3-01 .ah.hi{fill:#8FA3FF}html.dark #dsfig-u3-01 .wl rect{fill:#161920;stroke:#2A2E37}html.dark #dsfig-u3-01 .wl.hi rect{fill:#8FA3FF;stroke:#8FA3FF}html.dark #dsfig-u3-01 .wl.hi .t{fill:#0F1115}</style><defs><marker id="ah3" viewBox="0 0 10 10" refX="9" refY="5" markerWidth="7" markerHeight="7" orient="auto-start-reverse"><path class="ah" d="M0,1 L9,5 L0,9 z"/></marker><marker id="ahh3" viewBox="0 0 10 10" refX="9" refY="5" markerWidth="7" markerHeight="7" orient="auto-start-reverse"><path class="ah hi" d="M0,1 L9,5 L0,9 z"/></marker></defs><path class="e" d="M59,40 L148,40" marker-end="url(#ah3)"/><path class="e" d="M188,40 L277,40" marker-end="url(#ah3)"/><path class="e" d="M317,40 L406,40" marker-end="url(#ah3)"/><path class="e" d="M225,152 L177.5,57"/><path class="e" d="M242,152 L289.5,57"/><circle class="n" cx="40" cy="40" r="18"/><text class="t" x="40" y="40" dy=".35em" text-anchor="middle">Sen</text><circle class="n" cx="169" cy="40" r="18"/><text class="t" x="169" y="40" dy=".35em" text-anchor="middle">Com</text><circle class="n" cx="298" cy="40" r="18"/><text class="t" x="298" y="40" dy=".35em" text-anchor="middle">Pro</text><circle class="n" cx="427" cy="40" r="18"/><text class="t" x="427" y="40" dy=".35em" text-anchor="middle">App</text><circle class="n" cx="233.5" cy="169" r="18"/><text class="t" x="233.5" y="169" dy=".35em" text-anchor="middle">Sec</text></svg><figcaption style="font-size:.82em;opacity:.72;margin-top:.45rem">Functional components: Sen = sensing and actuation, Com = communication, Pro = processing and storage, App = application, Sec = security spanning all</figcaption></figure>

Key points.

  1. Sensing and actuation: sensors collect physical data (temperature, motion) and actuators act on commands.
  2. Communication: gateways and protocols (ZigBee, BLE, Wi-Fi, MQTT) carry the data to the processing side.
  3. Processing and storage: edge or cloud processors analyse and store the data and take decisions.
  4. Application: dashboards and apps turn results into services such as a smart home or smart farm.
  5. Security and management: authentication, encryption and device management protect every layer.
  6. The components interact as a chain: sense, transmit, process, act or display, with security wrapped around it. Example: a soil-moisture sensor sends readings through a gateway to the cloud, which starts an irrigation pump.

Answer frame. Open with the definition; draw the block diagram; develop points 1-5 in order; explain the interaction with the soil-moisture example; close with "security is required at every stage".

Asked: [7 marks] (May 2023) What are the functional components of IoT explain.

IoT service oriented architecture

<span style="display:inline-block;padding:.16em .6em;border:1.5px solid currentColor;border-radius:999px;font-size:.68em;font-weight:700;letter-spacing:.06em;text-transform:uppercase;opacity:.75">Not asked since 2022</span>

Definition. <mark>IoT service oriented architecture (SOA) exposes every device capability as a loosely coupled, reusable service that applications discover and compose, whatever the hardware underneath.</mark>

Key points.

  1. Layers: sensing, network, service (service composition and management), and application/interface.
  2. Devices publish services in a registry, and applications find and call them, so no one writes device-specific code.
  3. Loose coupling and reuse give interoperability across vendors and easy addition of new devices.
  4. Services can be combined into a bigger service, for example a temperature service plus a fan service gives a comfort service.

IoT challenges

<span style="display:inline-block;padding:.16em .6em;border:1.5px solid currentColor;border-radius:999px;font-size:.68em;font-weight:700;letter-spacing:.06em;text-transform:uppercase;opacity:.75">Not asked since 2022</span>

Definition. <mark>IoT challenges are the technical and social problems that limit large-scale IoT deployment.</mark>

Key points.

  1. Security and privacy: constrained devices are easy to attack and collect personal data.
  2. Interoperability: many vendors and protocols do not work together.
  3. Power: battery devices must last years, so energy use must be tiny.
  4. Scalability and bandwidth: billions of devices produce huge data and congestion.
  5. Heterogeneity, reliability and standardisation gaps add cost and complexity.

6LowPAN

<span style="display:inline-block;padding:.16em .6em;border:1.5px solid currentColor;border-radius:999px;font-size:.68em;font-weight:700;letter-spacing:.06em;text-transform:uppercase;opacity:.75">Not asked since 2022</span>

Definition. <mark>6LoWPAN (IPv6 over Low-power Wireless Personal Area Networks) is an adaptation layer that lets IPv6 packets travel over IEEE 802.15.4 links.</mark>

Key points.

  1. IPv6 needs a minimum MTU of 1280 bytes but an 802.15.4 frame carries only 127 bytes, so 6LoWPAN fragments and reassembles packets.
  2. It compresses the 40-byte IPv6 header to a few bytes, so payload space is saved.
  3. It uses 16-bit short or 64-bit addresses mapped to IPv6, giving every node an internet address.
  4. It sits between the network and MAC layers and works with low-power mesh networks.

IEEE 802.15.4, ZigBee and its types

<span style="display:inline-block;padding:.16em .6em;border:1.5px solid currentColor;border-radius:999px;font-size:.68em;font-weight:700;letter-spacing:.06em;text-transform:uppercase;opacity:.75">Low weight</span>

Definition. <mark>ZigBee is a low-power, low-data-rate, short-range wireless standard for mesh networks that builds its network and application layers on top of the IEEE 802.15.4 physical and MAC layers.</mark>

Diagram. <figure class="ds-fig" style="margin:1.4rem 0;overflow-x:auto"><svg xmlns="http://www.w3.org/2000/svg" id="dsfig-u3-02" viewBox="0 0 467 338" width="467" height="338" role="img" aria-label="ZigBee network: C = coordinator, R = router, E = end device; star, tree and mesh possible"><style>#dsfig-u3-02 .e{stroke:#454C5A;stroke-width:1.4;fill:none}#dsfig-u3-02 .e.hi{stroke:#2340B8;stroke-width:2.6}#dsfig-u3-02 .n{fill:#FFFFFF;stroke:#16181D;stroke-width:1.4}#dsfig-u3-02 .n.hi{fill:#E3E9FC;stroke:#2340B8;stroke-width:2.2}#dsfig-u3-02 .n.rb-b{fill:#16181D;stroke:#16181D}#dsfig-u3-02 .n.rb-r{fill:#BD3227;stroke:#BD3227}#dsfig-u3-02 text{font-family:"JetBrains Mono",ui-monospace,Menlo,Consolas,monospace;font-size:13px}#dsfig-u3-02 .t{fill:#16181D;font-weight:500}#dsfig-u3-02 .t.inv{fill:#FFFFFF;font-weight:700}#dsfig-u3-02 .kd{stroke:#16181D;stroke-width:1.2}#dsfig-u3-02 .dot{fill:#16181D}#dsfig-u3-02 .ann{fill:#2340B8;font-size:11px;font-weight:700}#dsfig-u3-02 .lbl{fill:#6F7787;font-family:system-ui,-apple-system,sans-serif;font-size:12px;font-weight:700}#dsfig-u3-02 .ptr{fill:#2340B8;font-size:12px;font-weight:700}#dsfig-u3-02 .ah{fill:#454C5A}#dsfig-u3-02 .ah.hi{fill:#2340B8}#dsfig-u3-02 .wl rect{fill:#FFFFFF;stroke:#DCE0E7}#dsfig-u3-02 .wl .t{font-size:12px;font-weight:700}#dsfig-u3-02 .wl.hi rect{fill:#2340B8;stroke:#2340B8}#dsfig-u3-02 .wl.hi .t{fill:#FFFFFF}html.dark #dsfig-u3-02 .e{stroke:#B1B7C3}html.dark #dsfig-u3-02 .e.hi{stroke:#8FA3FF}html.dark #dsfig-u3-02 .n{fill:#161920;stroke:#E6E8ED}html.dark #dsfig-u3-02 .n.hi{fill:#1E2748;stroke:#8FA3FF}html.dark #dsfig-u3-02 .n.rb-b{fill:#E6E8ED;stroke:#E6E8ED}html.dark #dsfig-u3-02 .n.rb-r{fill:#FF7E71;stroke:#FF7E71}html.dark #dsfig-u3-02 .t{fill:#E6E8ED}html.dark #dsfig-u3-02 .t.inv{fill:#0F1115}html.dark #dsfig-u3-02 .kd{stroke:#E6E8ED}html.dark #dsfig-u3-02 .dot{fill:#E6E8ED}html.dark #dsfig-u3-02 .ann{fill:#8FA3FF}html.dark #dsfig-u3-02 .lbl{fill:#858D9C}html.dark #dsfig-u3-02 .ptr{fill:#8FA3FF}html.dark #dsfig-u3-02 .ah{fill:#B1B7C3}html.dark #dsfig-u3-02 .ah.hi{fill:#8FA3FF}html.dark #dsfig-u3-02 .wl rect{fill:#161920;stroke:#2A2E37}html.dark #dsfig-u3-02 .wl.hi rect{fill:#8FA3FF;stroke:#8FA3FF}html.dark #dsfig-u3-02 .wl.hi .t{fill:#0F1115}</style><defs><marker id="ah4" viewBox="0 0 10 10" refX="9" refY="5" markerWidth="7" markerHeight="7" orient="auto-start-reverse"><path class="ah" d="M0,1 L9,5 L0,9 z"/></marker><marker id="ahh4" viewBox="0 0 10 10" refX="9" refY="5" markerWidth="7" markerHeight="7" orient="auto-start-reverse"><path class="ah hi" d="M0,1 L9,5 L0,9 z"/></marker></defs><path class="e" d="M198.6,53.4 L96.4,155.6"/><path class="e" d="M225.4,53.4 L327.6,155.6"/><path class="e" d="M102,169 L322,169"/><path class="e" d="M77,187 L46,280"/><path class="e" d="M93.5,184.8 L158.5,282.2"/><path class="e" d="M335,187 L304,280"/><path class="e" d="M351.5,184.8 L416.5,282.2"/><circle class="n" cx="212" cy="40" r="18"/><text class="t" x="212" y="40" dy=".35em" text-anchor="middle">C</text><circle class="n" cx="83" cy="169" r="18"/><text class="t" x="83" y="169" dy=".35em" text-anchor="middle">R1</text><circle class="n" cx="341" cy="169" r="18"/><text class="t" x="341" y="169" dy=".35em" text-anchor="middle">R2</text><circle class="n" cx="40" cy="298" r="18"/><text class="t" x="40" y="298" dy=".35em" text-anchor="middle">E1</text><circle class="n" cx="169" cy="298" r="18"/><text class="t" x="169" y="298" dy=".35em" text-anchor="middle">E2</text><circle class="n" cx="298" cy="298" r="18"/><text class="t" x="298" y="298" dy=".35em" text-anchor="middle">E3</text><circle class="n" cx="427" cy="298" r="18"/><text class="t" x="427" y="298" dy=".35em" text-anchor="middle">E4</text></svg><figcaption style="font-size:.82em;opacity:.72;margin-top:.45rem">ZigBee network: C = coordinator, R = router, E = end device; star, tree and mesh possible</figcaption></figure>

Key points.

  1. IEEE 802.15.4 defines the PHY and MAC: 250 kbps at 2.4 GHz (16 channels), 40 kbps at 915 MHz and 20 kbps at 868 MHz.
  2. The ZigBee stack adds the network layer (routing), the application support sub-layer and the application layer over PHY and MAC.
  3. Device types: the coordinator (one per network, starts it and holds security keys), routers (relay data, extend range) and end devices (sleep to save battery, reduced-function).
  4. Topologies: star (all to coordinator), tree (routers as branches) and mesh (multiple paths, self-healing).
  5. Features: low power (battery lasts years), range 10-100 m, low cost, AES-128 security, up to about 65,000 nodes.
  6. Uses: smart home lighting, smart meters, industrial monitoring and healthcare.

Answer frame. Open by defining ZigBee on 802.15.4; draw the topology sketch, labelling coordinator, routers and end devices; then develop points 3, 4, 2, 5; close with the use cases.

Asked: [7 marks] (May 2023) Explain about ZigBee with suitable sketch.

RFID Features, RFID working principle and applications

<span style="display:inline-block;padding:.16em .6em;border:1.5px solid currentColor;border-radius:999px;font-size:.68em;font-weight:700;letter-spacing:.06em;text-transform:uppercase;opacity:.75">Not asked since 2022</span>

Definition. <mark>RFID (Radio Frequency Identification) uses radio waves from a reader to identify and track tags attached to objects without contact or line of sight.</mark>

Key points.

  1. A system has tags (chip plus antenna), a reader with antenna, and a back-end database.
  2. Working: the reader sends a radio signal, the tag powers up or responds by backscatter with its ID, and the reader passes the ID to the database.
  3. Passive tags have no battery and short range; active tags have a battery and range of 100 m or more; semi-passive lie between.
  4. Bands: LF 125 kHz, HF 13.56 MHz, UHF 860-960 MHz.
  5. Applications: supply-chain tracking, toll collection, library books, access cards, livestock ID.

NFC (Near Field communication)

<span style="display:inline-block;padding:.16em .6em;border:1.5px solid currentColor;border-radius:999px;font-size:.68em;font-weight:700;letter-spacing:.06em;text-transform:uppercase;opacity:.75">Low weight</span>

Definition. <mark>NFC is a short-range (about 4 cm), contactless communication technology at 13.56 MHz based on RFID that works by magnetic induction between two devices.</mark>

Key points.

  1. NFC operates at 106-424 kbps with modes: reader/writer, peer-to-peer and card emulation.
  2. IoT challenge of pairing and commissioning: touching two NFC devices configures them (for example Wi-Fi or Bluetooth credentials) without typing anything.
  3. Challenge of security: the very short range makes eavesdropping hard, and secure elements provide authentication for access control and payments.
  4. Challenge of power: passive NFC tags need no battery, being powered by the reader's field.
  5. Challenge of heterogeneity: NFC bootstraps other links, so devices of different vendors connect easily.
  6. Examples: smart pairing, door access, contactless payment.

Answer frame. Open by defining NFC; list the challenges (pairing, security, power, heterogeneity); for each show how NFC addresses it (points 2-5); close with the examples.

Asked: [7 marks] (May 2023) How we can address IoT network challenges by using NFC (Near Field Communication).

Bluetooth

<span style="display:inline-block;padding:.16em .6em;border:1.5px solid currentColor;border-radius:999px;font-size:.68em;font-weight:700;letter-spacing:.06em;text-transform:uppercase;opacity:.75">Not asked since 2022</span>

Definition. <mark>Bluetooth is a short-range wireless standard in the 2.4 GHz ISM band that connects personal devices using frequency hopping.</mark>

Key points.

  1. It hops over 79 channels of 1 MHz at 1600 hops per second, which avoids interference.
  2. A piconet has one master and up to seven active slaves; linked piconets form a scatternet.
  3. Range is about 10 m (class 2) and classic data rate up to 3 Mbps.
  4. Bluetooth Low Energy (BLE) uses 40 channels and very low power, so it suits IoT sensors and wearables.

Wireless Sensor Networks and its Applications

<span style="display:inline-block;padding:.16em .6em;border:1.5px solid currentColor;border-radius:999px;font-size:.68em;font-weight:700;letter-spacing:.06em;text-transform:uppercase;opacity:.75">Low weight</span>

Definition. <mark>A wireless sensor network (WSN) is a group of spatially distributed, battery-powered sensor nodes that sense a physical quantity and cooperatively pass data by wireless links to a sink.</mark>

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Key points.

  1. Need in IoT: WSNs let many cheap sensors cover a large area, providing the data that IoT applications use.
  2. Architecture: sensor nodes (sensor, processor, radio, battery), a sink or base station that collects data, and a gateway linking to the internet; topology is star, tree or mesh.
  3. Protocol stack: physical, data link, network, transport and application layers, with power, mobility and task management planes across them.
  4. Working: nodes sense, aggregate and forward data hop by hop to the sink, which sends it to the user.
  5. Applications: environmental and habitat monitoring, military surveillance, healthcare, smart agriculture and industrial control.
  6. Advantages: easy deployment, low cost, self-organising and fault tolerant. Challenges: limited energy, memory and bandwidth, plus security and node failure.

Answer frame. Open with the definition and need; draw the sensor-sink-gateway figure; develop points 2-4; then applications; close with advantages and challenges.

Asked: [7 marks] (May 2023) Describe wireless sensor network technology in detail.

Last-minute revision

  • IoT networking uses low-power, short-range links between constrained devices, gateways and cloud.
  • SDN separates control plane from data plane; benefits are central management, programmability, agility, cost, scalability.
  • Functional components: sensing, communication, processing, application, security.
  • 6LoWPAN = IPv6 over 802.15.4; IPv6 MTU 1280 bytes versus 127-byte frame, so header compression and fragmentation.
  • 802.15.4 rates: 250 kbps (2.4 GHz), 40 kbps (915 MHz), 20 kbps (868 MHz).
  • ZigBee devices: coordinator, router, end device; topologies star, tree, mesh; AES-128.
  • RFID: tag, reader, database; bands 125 kHz, 13.56 MHz, 860-960 MHz.
  • NFC: 13.56 MHz, about 4 cm, modes reader/writer, peer-to-peer, card emulation.
  • Bluetooth: 2.4 GHz, 79 channels, master plus 7 active slaves per piconet.
  • WSN: sensor nodes, sink, gateway; five-layer stack plus three management planes.

Memory hooks

  • Functional components: "S-C-P-A-S" = Sense, Communicate, Process, Apply, Secure.
  • ZigBee devices: "Coordinator commands, Routers relay, End devices sleep".
  • Bluetooth: one master, seven slaves, 79 hops.
  • NFC = "Near, Nearly Nothing to type": touch to pair.
  • SDN: brain (control) apart from muscle (data).

Coverage checklist

  • Basics of IoT Networking: SDN benefits to IoT (May 2023).
  • IoT Components, Functional components of IoT: functional components (May 2023).
  • IoT service oriented architecture: no past questions.
  • IoT challenges: no past questions.
  • 6LowPAN: no past questions.
  • IEEE 802.15.4, ZigBee and its types: ZigBee with sketch (May 2023).
  • RFID Features, RFID working principle and applications: no past questions.
  • NFC (Near Field communication): NFC for IoT challenges (May 2023).
  • Bluetooth: no past questions.
  • Wireless Sensor Networks and its Applications: WSN in detail (May 2023).
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