UNIT – III
Introduction to
Internet of Things
IoT Connectivity & Communication Technologies
IEEE 802.15.4 · ZigBee · Thread · ISA100.11a · WirelessHART · RFID · NFC
DASH7 · Z-Wave · Weightless · Sigfox · LoRa · NB-IoT · Wi-Fi · Bluetooth
Infrastructure · Discovery · Data · Identification · Device Mgmt · Semantic
Introduction to IoT
— P T Krishna Sai
Dept. of IT
UNIT – III : Course Outline
Topics at a Glance
01
Connectivity Technologies – Introduction
Frequency bands · Range · Power overview · Classification
02
IEEE 802.15.4, ZigBee & Thread
LR-WPAN PHY/MAC · Zigbee mesh · Thread IPv6
03
ISA100.11a & WirelessHART
Industrial wireless · FHSS · TDMA · Channel hopping
04
RFID, NFC & DASH7
Active/passive tags · Magnetic induction · 433 MHz
05
Z-Wave, Weightless & Sigfox
GFSK · Home automation · UNB · BPSK · LPWAN
06
LoRa, NB-IoT, Wi-Fi & Bluetooth
CSS · OFDM · IEEE 802.11 · FHSS · Piconet
07
Communication Technologies – Introduction
Constrained nodes/networks · 6 protocol categories
08
Infrastructure Protocols
IPv6 · LOADng · RPL · 6LoWPAN · QUIC · uIP · CCN
09
Discovery & Data Protocols
Physical Web · mDNS · UPnP · MQTT · CoAP · AMQP · REST
10
Identification, Device Mgmt & Semantic
EPC · uCode · URI · TR-069 · OMA-DM · JSON-LD · WoT
IoT Connectivity Technologies
Part 1 — IEEE 802.15.4 · ZigBee · Thread · ISA100.11a · WirelessHART · RFID · NFC · DASH7 · Z-Wave · Weightless · Sigfox · LoRa · NB-IoT · Wi-Fi · Bluetooth
UNIT – III | Introduction to IoT
IoT Connectivity Technologies — Introduction
1.1
IoT connectivity technologies are primarily wireless. Selection depends on frequency band, range, data rate, power consumption, and topology. They span from near-field (centimetres) to wide area (kilometres). Short-range technologies use ISM bands (2.4 GHz / 900 MHz). LPWAN technologies use sub-GHz for long-range, low-power deployments.
Near Field
(< 1m)
NFC · Passive RFID
Short Range
(1–100m)
ZigBee · Z-Wave · Thread
802.15.4 · Bluetooth
Local Area
(100m–2km)
Wi-Fi · DASH7
WirelessHART · ISA100
Wide Area
(2–20km)
LoRa · Sigfox
Weightless
Cellular LPWAN
(> 10km)
NB-IoT · (Licensed
LTE spectrum)
← Near Field ————————— Increasing Range ————————— Wide Area →
Quick Comparison of Key Connectivity Technologies
Technology
Frequency
Range
Data Rate
Power
Topology
ZigBee
2.4 GHz / 868/915 MHz
10–100m
250 kbps
Low
Star, Mesh, Cluster-tree
LoRa/LoRaWAN
169/433/868/915 MHz
15–20 km
0.3–50 kbps
Very Low
Star (end-nodes → gateway)
NB-IoT
LTE Guard/In-band
Up to 10 km
20–250 kbps
Very Low
Cellular star topology
Wi-Fi 802.11
2.4 GHz / 5.8 GHz
~100m
11 Mbps–Gbps
High
Infrastructure (AP-based)
Bluetooth
2.4 GHz (ISM)
~10m (BLE: 400m)
1–3 Mbps
Low–Med
Piconet (1 master, 7 slaves)
IEEE 802.15.4 · ZigBee · Thread
1.2 – 1.4
IEEE 802.15.4 — Foundation of Low-Rate WPAN
Frequency:
2.4 GHz (16 ch @ 250 kbps); 868 MHz (1 ch @ 20 kbps); 915 MHz (10 ch @ 40 kbps)
MAC:
CSMA-CA channel access; beacon-enabled & non-beacon modes; superframe structure
Topology:
Star, mesh, peer-to-peer; FFD (Full Function) & RFD (Reduced Function) devices; AES-128 security
ZigBee
Application (ZDO/APS)
ZigBee Network Layer
IEEE 802.15.4 MAC
IEEE 802.15.4 PHY
Built on IEEE 802.15.4 PHY/MAC
Self-forming, self-healing mesh network
Up to 65,000 nodes per network
3 device types: Coordinator, Router, End Device
Range 10–100m; 250 kbps @ 2.4 GHz
Network topologies: Star, Mesh, Cluster-tree
AODV-based routing for multi-hop paths
Applications: Smart home, lighting, HVAC, energy
Thread
Application (CoAP/HTTP)
IPv6 / 6LoWPAN / MLE
IEEE 802.15.4 MAC
IEEE 802.15.4 PHY
IP-based mesh protocol using IPv6
Built on IEEE 802.15.4 with 6LoWPAN
Developed by Nest (Google) in 2014
OpenThread: open-source implementation
Border Router bridges Thread ↔ Internet
No gateway needed — native IP connectivity
Used in: Nest, Apple HomeKit, Amazon
Smart home standard: Matter protocol basis
ISA100.11a · WirelessHART
1.5 & 1.6
ISA100.11a (IEC 62734)
Industrial wireless standard for process automation. Operates at 2.4 GHz using IEEE 802.15.4 PHY. Uses FHSS (frequency hopping spread spectrum) across 16 channels with channel blacklisting to avoid interference. Provides end-to-end IPv6 connectivity via 6LoWPAN.
Protocol Stack vs OSI:
Application Layer
UDP Transport
IPv6 Network (6LoWPAN)
ISA100 Data Link Control
IEEE 802.15.4 PHY
Key Features:
Field devices: routing, non-routing, handheld
Backbone: routers, gateways, system/security managers
Supports mesh, star, and star–mesh topologies
Used in oil & gas, chemical plants, pharma
WirelessHART (IEC 62591)
Wireless evolution of HART protocol. License-free, developed for smart field devices in industrial environments. Uses IEEE 802.15.4 at 2.4 GHz with only 15 channels. Uses TDMA with 10ms time-slots and channel hopping for 99.999% reliability. Back-compatible with legacy wired HART devices.
Protocol Stack vs OSI:
Application Layer
WirelessHART Network/Transport
Logical Link Control (TDMA)
IEEE 802.15.4 MAC
IEEE 802.15.4 PHY (2.4 GHz)
Key Features:
Superframes: groups of 10ms time-slots for scheduling
Channel blacklisting removes interference-prone channels
Network manager decides routing paths and time-slots
Direct (LOS 250m) and indirect (mesh) communication
RFID · NFC · DASH7
1.7 – 1.9
RFID
TAG
READER
DB
RF waves
Tags: Passive (reader-powered) & Active (battery)
LF: 125 kHz; HF: 13.56 MHz; UHF: 860–960 MHz
No line-of-sight required (unlike barcodes)
Reads multiple tags simultaneously
Applications: inventory, asset tracking, access control, supply chain, livestock ID
NFC (Near Field Communication)
Peer-to-Peer
Read/Write
Card Emulation
3 Operating Modes
Developed by Philips & Sony jointly
Frequency: 13.56 MHz; Range: up to 4 cm
Data rates: 106, 212, or 424 kbps
Works by magnetic induction / inductive coupling
Passive NFC: tags only store data (no power)
Active NFC: smartphones, POS terminals
Applications: mobile payments, transport cards, smart posters, IoT device pairing
DASH7 (ISO 18000-7)
Application
Transport/Network
PHY (433 MHz FSK)
Full OSI stack — adaptable to Sigfox/LoRa PHY
Based on active RFID (ISO 18000-7) standard
Frequency: 433 MHz ISM band (FSK modulation)
Range: 1–10 km; query latency 1–10 seconds
Can communicate with NFC (via 433.92/13.56 harmonics)
Integrated file system; low memory footprint
Tag-to-tag communication without base station
Dense deployments; very low power consumption
Applications: agriculture, vehicles, logistics
Z-Wave · Weightless · Sigfox
1.10 – 1.12
Z-Wave
Developed by Zensys for home automation. Uses source-routed mesh (up to 4 hops). Each network has a 4-byte Home ID and 1-byte Node ID. Healing messages reroute around dead-spots. Backward compatible. Mobile devices excluded — static devices only.
Frequency:
800–900 MHz (GFSK modulation)
Max Nodes:
232 per network (1 hub/home)
Range:
30–100m indoors
Weightless-P
Open LPWAN standard. Three variants: N (simplex uplink), P (bi-directional, accepted standard), W (TV white space). Weightless-P uses star topology with end devices and base stations. Ultra-low power comparable to cellular. Base station network (BSN) manages scheduling and resources.
Frequency:
Sub-GHz ISM: 138/433/868/915 MHz
Data Rate:
0.625 kbps to 100 kbps
Payload:
< 48 bytes
Sigfox
LPWAN using ultra-narrow band (UNB) technology. Uses time and frequency diversity: each message sent twice at different frequencies. Spatial diversity: any nearby base station receives messages. Receivers monitor full 192 kHz spectrum for UNB transmissions. AES security; supports authentication and anti-replay. Better for indoor dense deployments.
Frequency:
868/868.2 MHz (EU); 902/928 MHz (US)
Payload:
0–12 bytes; 140 messages/day uplink
Modulation:
UNB (192 kHz wide); BPSK 100 Hz wide
Key Differences At a Glance
Technology
Frequency
Range
Data Rate
Topology
Applications
Z-Wave
800–900 MHz
30–100m
40 kbps
Source-routed mesh
Smart home (locks, lights, HVAC, alarms)
Weightless-P
Sub-GHz ISM
Up to 5 km
0.6–100 kbps
Star (ED→BS→BSN)
Smart city, utilities, infrastructure
Sigfox
868/902 MHz
10–50 km
100–600 bps
End-points → base stations → cloud
Meters, parking, agriculture, logistics
LoRa / LoRaWAN · NB-IoT · Wi-Fi · Bluetooth
1.13 – 1.16
LoRa / LoRaWAN (1.13)
Application
LoRaWAN MAC
LoRa PHY (CSS)
RF (169/433/868/915 MHz)
CSS modulation with 125 kHz wideband; chirp signal provides coding gain
Star-of-stars: end-nodes → LoRaWAN gateways → network server
Range 15–20 km; supports millions of devices per gateway
Adaptive Data Rate (ADR) optimizes range vs data rate
Lower data rates (27–50 kbps) but very long battery life
Applications: smart agriculture, electric grid monitoring, asset tracking
NB-IoT — Narrowband IoT (1.14)
In-band LTE
Guard-band
Standalone GSM
3 Deployment Modes
3GPP Release 13 — coexists with 2G/3G/4G cellular
OFDM modulation for higher data capacity
Battery life up to 10 years on a single cell
20 dB better coverage than GPRS — deep indoor
Higher QoS and lower latency than LoRa/Sigfox
Better for static deployments; no mobility support
Applications: smart meters, fixed sensors, parking
Wi-Fi — IEEE 802.11 (1.15)
802.11b
2.4 GHz
11 Mbps
802.11a
5 GHz
54 Mbps (OFDM)
802.11g
2.4 GHz
54 Mbps (OFDM)
802.11n
5 GHz
140 Mbps
802.11ax (Wi-Fi 6)
2.4/5/6 GHz
~Gbps (OFDMA)
CSMA/CA; TDMA time-sharing for multiple devices
Device → Wireless AP → WLAN → Internet
Smart home hubs, cameras, IoT gateways
Bluetooth — IEEE 802.15.1 (1.16)
Application
L2CAP / RFCOMM
Baseband
PHY Radio (2.4 GHz)
FHSS: 79 channels of 1 MHz; 800 hops/second (AFH)
Piconet: 1 master + up to 7 slave devices
Scatternet: overlapping piconets via bridge node
BR mode: GFSK 1 Mbps; EDR: π/4 DQPSK 2 Mbps; 8-DPSK 3 Mbps
Applications: wearables, health monitors, speakers, IoT pairing
IoT Communication Technologies
Part 2 — Infrastructure · Discovery · Data · Identification · Device Management · Semantic Protocols
UNIT – III | Introduction to IoT
IoT Communication Technologies — Introduction
2.1
IoT communication protocols are organized into 6 groups based on functionality: Infrastructure, Discovery, Data, Identification, Device Management, and Semantic. These protocols are designed for constrained nodes (limited memory, CPU, power) and constrained networks (low data rate, high packet loss, asymmetric links).
Constrained Device Classes (2.1.3)
Class 0
Severely constrained. Cannot communicate directly to Internet. Must use a gateway/proxy. No security mechanisms possible.
Class 1
Constrained code space and CPU. Can access Internet but cannot use full HTTP stack. Uses CoAP. Has security. No gateway needed.
Class 2
Functionally similar to regular portable computers. Can use standard protocol stacks. Runs full IP and HTTP comfortably.
6 IoT Protocol Categories
Infrastructure
IPv6 · LOADng · RPL · 6LoWPAN · QUIC · uIP · CCN
Discovery
Physical Web · mDNS · UPnP (SSDP)
Data
MQTT · MQTT-SN · CoAP · AMQP · XMPP · REST · WebSocket
Identification
EPC · uCode · URI / URL / URN
Device Mgmt
TR-069 (CWMP) · OMA-DM
Semantic
JSON-LD · Web Thing Model (WoT)
Infrastructure Protocols
2.2
Infrastructure protocols operate at network layer and below. They form the backbone of IoT communications — enabling routing, addressing, and transport across constrained heterogeneous networks. 8 key protocols: IPv6, LOADng, RPL, 6LoWPAN, QUIC, uIP, NanoIP, CCN.
IPv6
128-bit addressing (2¹²⁸ addresses). Features: end-to-end connectivity (no NAT), auto-configuration (stateless/stateful), inbuilt IPSec security, mobility support (Care-of-Address), multicast, extensible headers, faster packet forwarding.
3 unicast types: GUA (global), Link-Local (LL), Unique-Local (ULA). IID generated via EUI-64 from MAC address.
LOADng
Lightweight On-demand Ad hoc Distance vector Routing Protocol – Next Generation. Reactive routing inspired by AODV. Router generates RREQs (Route Requests) for flooding; destination replies with RREP. RERR sent if route is down.
Bi-directional route discovery. Route maintenance only when data is being sent or route is down.
RPL
Routing Protocol for Low-Power and Lossy Networks (RFC 6550). Builds Destination Oriented Directed Acyclic Graph (DODAG). Nodes can join multiple RPL instances. Supports QoS-aware and constraint-based routing.
Global instances: multiple DODAGs, long lifetime. Local instances: single DODAG. Handles intra-mesh addressing.
6LoWPAN
IPv6 over Low-Power WPAN. Enables IPv6 on IEEE 802.15.4 frames using header compression, fragmentation, mesh addressing. RFDs forward to FFDs; FFDs forward to 6LoWPAN gateway which connects to IPv6 domain.
Address format: 16-bit short (PAN-specific) + 64-bit extended (globally unique). Header types: Dispatch, Mesh, Fragmentation.
QUIC
Quick UDP Internet Connection. Low-latency TCP alternative. Includes session negotiation in initial packet. Uses packet pacing, proactive speculative retransmission for congestion avoidance. Enables multiple secured requests per congestion window.
Reduces round-trips vs TCP handshake. Static config records published by servers. UDP-based with multiple paths.
uIP / NanoIP
uIP: micro-IP extending TCP/IP to 8/16-bit microcontrollers. Open-source by SICS. Minimal packet buffer (1 packet). Half-duplex buffer reuse. NanoIP: nanoTCP+nanoUDP for sensor devices using MAC addresses instead of IP. Supports nHTTP and nPing.
uIP: no OS required; hardware driver handles packet build/send. NanoIP: 256 source+destination ports. Very low overhead.
CCN
Content-Centric Networking (also ICN/NDN). Communication by uniquely named data — not addresses. Anchorless: supports mobility, in-network caching. Forwarder uses hierarchical prefix matching (FIB) to route named requests.
Users access cached content from trusted servers. Binary comparison for prefix matching. Independent of location/storage.
Discovery Protocols & Data Protocols
2.3 & 2.4
Discovery Protocols (2.3)
Physical Web
Broadcasts list of URLs via BLE (Eddystone protocol) within short radius. Users see available URLs and interact with physical objects. Uses HTTPS for security.
mDNS
Multicast DNS for small networks. Uses multicast UDP to resolve hostnames without a local DNS server. Zero-configuration service. Apple Bonjour uses mDNS.
UPnP (SSDP)
Universal Plug & Play. Devices auto-configure and advertise services over network. SSDP uses HTTP over UDP multicast. Managed by Open Connectivity Foundation.
Data Protocols (2.4) — 7 Protocols
MQTT
TCP
Pub/Sub
Lightweight broker-based pub/sub. Fixed header = 2 bytes. 3 QoS levels: at-most-once, at-least-once, exactly-once. 14 message types (CONNECT, PUBLISH, SUBSCRIBE…). MQTT-SN variant for sensor networks over UDP.
CoAP
UDP
Req/Res
RESTful protocol for constrained devices. 4-byte header. 4 message types: CON, NON, ACK, RESET. GET/PUT/POST/DELETE methods. Supports multicast, URI, DTLS security, piggybacking, separate responses.
AMQP
TCP
Pub/Sub + P2P
Application layer middleware. 9 frame types (Open/Begin/Attach/Transfer/Flow/Disposition/Detach/End/Close). Credit-based flow control. 3 reliability guarantees. Cross-vendor interoperability.
XMPP
TCP
P2P/Pub-Sub
Extensible Messaging and Presence Protocol. Jabber ID (JID): user@domain/resource. XML streaming over network. TLS encryption + SASL authentication. Supports multi-device login with resource priorities.
REST
HTTP/TCP
Req/Res
Representational State Transfer. 6 constraints: Stateless, Uniform Interface, Client-Server, Cacheable, Layered System, Code on Demand. Responds with HTML/XML/JSON payloads. Stateless — server retains no client state.
WebSocket
TCP
Full-duplex
IETF-standardized full-duplex protocol (OSI L7) over single TCP. Initiated by HTTP handshake then separates to bi-directional WS. Uses Sec-WebSocket-Key header. Supports message fragmentation and multiplexing.
Identification · Device Management · Semantic Protocols
2.5 – 2.7
Identification (2.5)
Header
8-bit
EPC Manager
28-bit
Object Class
24-bit
Serial No.
36-bit
EPC Structure (96-bit)
EPC
Electronic Product Code. Universal identifier for physical objects. Official representation as pure identity URI. Open standard by EPCglobal Tag Data Standard.
uCode
128-bit code from uID Center Japan. 3.4×10³⁸ unique codes. Application and technology independent. 5 tag categories: print, acoustic, active RF, active IR, passive RFID. Hierarchical resolution: root → TLD → SLD.
URI / URL / URN
URI: Uniform Resource Identifier — identifies resources by character string. URL: locates resource + access mechanism. URN: identifies in specific namespace only. Used in CoAP resource identification.
Device Management (2.6)
TR-069 (CWMP)
Broadband Forum Technical Report 069. CPE WAN Management Protocol (CWMP) — SOAP/HTTP based bi-directional. Auto-configuration via Auto Configuration Server (ACS). Covers: firmware/software management, diagnostics, performance reporting. CPE sends 'inform' → ACS responds → provisioning session begins.
OMA-DM
Open Mobile Alliance Device Management. Asynchronous server-initiated communication via WAP push/SMS. Request–response model with XML (SyncML). Supports USB, RS-232, GSM, CDMA, Bluetooth transports. Authentication built-in to prevent unauthorized access.
Semantic Protocols (2.7)
Semantic protocols encode meaning of IoT data for machine understanding — enabling cross-vendor interoperability and intelligent data fusion.
{
"@context": "https://schema.org",
"@type": "BlogPosting",
"headline": "Hello Readers",
"description": "This is a test"
}
JSON-LD: @context adds semantic meaning
JSON-LD:
JSON for Linked Data. Adds @context to JSON for semantic meaning. Built on RDF. Enables interoperability of JSON data over Web. Context can be direct or via HTTP link headers.
Web Thing Model (WoT):
W3C initiative for application-layer framework giving URLs to IoT devices. 3 integration patterns: Direct, Gateway-based, Cloud-based. Transforms 'Web of Pages' to 'Web of Things'. Aims to avoid proprietary data formats.
UNIT – III Summary
802.15.4 / ZigBee / Thread
IEEE 802.15.4: LR-WPAN PHY/MAC; CSMA-CA; AES-128. ZigBee: 65K nodes; mesh; AODV; Coordinator/Router/End Device. Thread: IPv6 mesh; 6LoWPAN; no gateway needed; OpenThread.
ISA100 / WirelessHART
ISA100.11a: FHSS 16ch; channel blacklisting; IPv6/6LoWPAN; field + backbone devices; oil/gas/pharma. WirelessHART: TDMA 10ms slots; superframes; channel hopping; 99.999% reliable; IEC 62591.
RFID / NFC / DASH7
RFID: LF/HF/UHF; passive+active tags; no LOS; inventory/asset tracking. NFC: 13.56 MHz 4cm; 3 modes (P2P/R-W/Card Emul); mobile payments. DASH7: 433 MHz FSK; 1–10 km; full OSI stack.
Z-Wave / Weightless / Sigfox
Z-Wave: 800–900 MHz GFSK; 232 nodes; source-routed mesh; healing. Weightless-P: sub-GHz; bi-directional; star topology. Sigfox: UNB 12B payload; BPSK; time+freq+spatial diversity.
LoRa / NB-IoT / WiFi / BT
LoRa: CSS 125 kHz; 15–20 km; ADR; star-of-stars. NB-IoT: 3GPP R13; OFDM; 10yr battery; 20dB GPRS coverage. WiFi: CSMA/CA; 11–Gbps. Bluetooth: FHSS 79ch; piconet/scatternet.
Infrastructure Protocols
IPv6: 128-bit; IPSec; auto-config; mobility. LOADng: reactive AODV-inspired routing. RPL: DODAG mesh routing. 6LoWPAN: IPv6 on 802.15.4; header compression. QUIC: low-latency UDP. uIP/NanoIP: microcontroller IP stacks. CCN: named data networking.
Discovery & Data Protocols
Discovery: Physical Web (BLE/Eddystone), mDNS (Bonjour), UPnP/SSDP. Data: MQTT (pub/sub, TCP, 3 QoS), CoAP (REST/UDP, 4B header), AMQP (9 frame types), XMPP (JID), REST (6 constraints, stateless), WebSocket (full-duplex TCP).