Describes the key protocols used in Internet of Things across the network stack. It covers the MAC protocol such as 802.15.4, Zigbee, Z-wave, Bluetooth, BLE, some key protocol used in IIoT - Industrial Internet of Things / Automation such as ISA 100.11, Wireless HART, NB-IoT, LTE-M Effort has been made to keep the explanation short and crisp. The intention was never to replace numerous books on this subject.

1. IOT Protocols: MAC, Networking &
Session Layer
Nagesh T Rao

2. Internet of Things - IoT
• The Internet of Things
(IoT) is the network of
physical objects that
contain embedded
technology to
communicate and sense or
interact with their
internal states or the
external environment
• Network of Physical Objects
• Contains embedded
technology
• To communicate
• Sense
• Interact
• w/t their internal states or …
• The external environment
Courtesy: Gartner

3. TCP/IP : Quick Revisit
Physical Device
PPP, SLIP, Ethernet
IP, ARP, ICMP
TCP, UDP
Socket API, Telnet,
FTP,TFTP,DHCP,SNMP,HTTP
1. Physical Layer
2. Data Link Layer
3. Network Layer
4. Transport Layer
5-6-7. Application Layer
Ethernet Header IP Header TCP Header Application Data Ethernet Trailer
Ethernet Frame: Src & Dest. Mac Address
IP Header TCP Header Application Data
TCP Header Application Data
App Header User Data
User Data
IP Datagram: Src & Dest. IP Address
TCP Segment: H2H Comm.

4. OSI, TCP/IP, IOT
OSI Model TCP/IP Model Layer Functions Protocols
Application Layer
Application
Interact and support user
application
Http, Https, CoAPP, MQTT,
AMQP, SMQP
Presentation Layer
Session Layer
Transport Layer Transport
Handle Reliability, Flow
Control, Congestion
Avoidance, Error Correction
TCP, UDP
Network Layer Internet
Logical Addressing, Routing,
SAR
IP, 6LoPAN, 6Lo, 6TiSCH,
LOADng, RPL, CoRPL, CARP
Data Link Layer
Network Access and Physical
Layer
Define physical connection
of end devices to the
network – Wired or Wireless
LPWAN, Wi-Fi, LTE,HART,
802.15.4, BT/ BLE, ZigBee,
Z-Wave
Physical Layer

5. IoT Protocol & Layers
• IoT protocols operate at
different layers of the
networking stack …
including:
• Medium Access Control
(MAC) layer
• network layer
• session layer
MAC
• WiFi, BLE, Z-Wave, ZigBeeSmart
• DECT/ULE, 3G/LTE, NFC, Weightless, HomePlug GP, 802.11ah,
802.15.4e, G.9959, Wireless HART, DASH7, ANT+, LTE-A,
LoRaWAN
Network
Layer
• Routing Protocol
• RPL
• LOADng
• CARP
• Encapsulation – 6LoPAN, 6Lo, 6TiSCH
Session
Layer
• MQTT
• CoAP
• AMQP
• SMQTT
Protocols offered by Internet Engineering Task
Force (IETF), Institute of Electrical and
Electronics Engineers (IEEE), International
Telecommunication Union (ITU) and other
standard organizations.

6. Data Link and MAC Protocol
IEEE
802.15.4
WiFi
Bluetooth
Low Energy -
BLE
ZigBee
Z-Wave 3G/LTE 802.11AH LoRaWAN
WirlessHART RFID ISA 100.11 NFC
• Includes
physical (PHY)
and MAC layer
protocols which
are combined
by most
standards

7. Communication Technology
Technology Frequency Data Rate Range Power Usage Cost
2G/3G Cellular Brand 384 Kbps/10 Mbps Several Km High High
Bluetooth/BLE 2.4 GHz 1,2,3 Mbps 1, 10, 100 m Low Low
802.15.4 Sub GHz, 2.4 GHz 40,250 Kbps 10-75 m Low Low
LoRa Sub GHz < 50 Kbps 1.5 – 4.5 Km Low Medium
LTE Cellular Brand 1 Gbps Several Km Medium High
NB-IoT Cellular Brand 0.1 – 1 Mbps Several Km Medium High
SigFox Sub GHz < 1 Kbps Several Km Low Medium
Weightless Sub GHz 0.1 – 1 Mbps Several Km Low Low
WiFi Sub GHz, 2.4 GHz, 5 GHz 0.1 – 54 Mbps < 100 m Medium Low
WirelessHART 2.4 GHz 250 Kbps ~100 m Medium Medium
Zigbee 2.4 GHz 250 Kbps ~100 m Low Medium
Z-Wave Sub GHz 40 Kbps ~30 m Low Medium
5G 30 GHz 10 Gbps 400 m High High

8. IEEE 802.15.4 / 802.15.4e
Low Rate Wireless Personal Area Network
• IEEE 802.15.4 is the most commonly
used MAC Protocol for IoT
• Many other popular IoT protocol uses
this protocol for their MAC layer –
ZigBee, ISA 100.11, Wireless HART etc
• It defines frame format, headers with
source and destination addresses, and
communication between nodes
• Traditional networks are not suitable
for low power multi-hop networking in
IoT due to their large frame formats
• IEEE802.15.4e was developed for IoT
extending IEEE802.15.4 to support low
power communication
• Uses time synchronization and channel
hopping for high reliability
• IEEE 802.15.4e uses slotted frame
Structure and is designed for scheduling
and telling each node what to do
• A node can be in sleep more, or send, or
receive information
• In the sleep mode, the node switch off its
radio to save power and store all messages
to send at the next transmission
opportunity
• When transmitting, it sends its data, wait
for acknowledgment and goes to sleep
• When receiving, the node turns on its
radio before scheduled time to receive,
receives the data, sends an
acknowledgement, turn off its radio,
delivers the data to upper layers and goes
to sleep

9. 802.11 AH
• Also called Wi-Fi HaLow. Developed for low power communication
• Uses 900 MHz, compared to traditional Wi-Fi networks which uses 2.4 GHz and
5 GHz bands
• Lighter and low overhead version of original IEEE 802.11 Wi-Fi protocol, fitting
IOT requirements
• Low frame overheads and power consumption
• MAC frame is 12 bytes Vs 30 bytes for 802.11
• Low energy consumption, fit for sensors nodes in wireless sensor network
(WSN) that can cooperate with other nodes
• Competes with Bluetooth, due to its low power requirement, with added
benefit of higher data rates and wider coverage area/range

10. Zigbee
• Zigbee is wireless
technology developed as
an open global standard to
address the unique needs
of low-cost, low-power
wireless IoT networks.
• The Zigbee standard
operates on the IEEE
802.15.4 physical radio
specification
• It works in unlicensed
bands including 2.4 GHz,
900 MHz and 868 MHz
• ZigBee is used for a large range of IoT applications including but not
limited to smart homes, healthcare systems and remote controls.
• The ZigBee protocol is determined by layer 3 and above. For the PHY
and MAC it is defined by 802.15.4 layers 1 and 2
• Supports wide range of network topologies including star, peer-to-
peer and mesh.
• Zigbee based sensor nodes are very popular in WSN when
implemented in Mesh topology.
• The network is controlled by the co-ordinator and is the central
node in a star topology or, root in a tree or, be located anywhere in
mesh topology
• ZigBee device can be of following types
• ZigBee Coordinator, ZigBee Router(ZR), ZigBee end-device (ZED)

11. Bluetooth & Bluetooth Low Energy (BLE)
• Bluetooth is a short range communication technology.
• IEEE 802.15.1 has adopted the standard for Physical and MAC
layer based on Bluetooth technology spec 1.1
• Developed for replacing cables connecting portable units
• Its is based on Ad-hoc technology also known as ad-hoc
Piconet
• It follows master/slave architecture and offers two types of
frames: advertising & data frames
• The Advertising frame is for discovery and is sent by slaves on
one or more dedicated advertisement channels
• Master nodes sense advertisement channels to find slaves and
connect with them
• After connection is established, the master tells the slave it’s
waking cycle and scheduling sequence
• Nodes are awake only during communication, otherwise they
go to sleep to save the power
• Bluetooth low energy (BLE) is developed for low
data rate, better power saving and supporting
massive number of slaves helping IoT based
applications
• BLE’s power consumption is nearly half that of
classic Bluetooth device
• BLE supports 24 bit address vs classic Bluetooth 3
bit. Theoretically almost unlimited slaves (224 – 1) !
• Topology can be point-to-point, point-to-
multipoint, start & mesh
• BLE range is more than that of Bluetooth. Can
support range up to 400 m as per BLE 5.0
• Use case include – medical device – BP monitor,
Activity Tracker, audio HS
• Can be used even for developing IoT gateway

12. Z-wave
• Zwave (or Z‐wave) is a protocol
developed for communication
among devices typically for home
automation
• It has communication range of ~100
feet point-to-point and is suitable
for small messages in IoT
applications, smart homes,
wearable healthcare, remote
control and others.
• It uses CSMA/CA for collision
detection and ACK messages for
reliable transmission
• Follows Master/Slave config.
• A Master sets‐up and manages a Zwave
network
• Each logical Zwave network has 1 Home
(Network) ID and multiple node IDs - upto
232 nodes
• Nodes related to one network (home id)
can not communicate with other network
(different home id)
• Devices communicate with one another
when in range
• When devices are not in range, messages
are routed though different nodes to
bypass obstructions or radio dead spot
• This is called Healing

13. HART/Wireless HART
• HART - Highway Addressable Remote
Transducer – developed for supporting large
number of field devices for field networks
• It is a bidirectional request-response
communication protocol
• Uses current loop technology, supporting
analog and digital sensors
• Wireless version of HART makes it more cost
efficient and easier to implement
• The Wired HART differs from the Wireless
version where the wired version lacks Network
Layer. Both have different physical and data
link layer
• Application layer is common for both Wired
and Wireless
• The physical layer of the wireless HART is
based on 802.15.4
• Operated only in 2.4 GHz of the ISM band
• It uses 15 channels to support reliability,
uses super-frames, channel hopping and
channel blacklisting for transmission quality
• Uses Mesh topology where each device is
prepared to forward packets from every
other devices and have updated network
graph to handle routing
• The network manager supervises each node
and decides who will send the packet and
who listen and frequency for each time slot
• It also handles security by deciding which
node can join the network preventing
unauthorized node from joining

14. ISA 100.11A
• Developed by International Society of
Automation for large scale industrial
plant automation
• This is one more protocol based on
802.15.4
• Network and Transport layer is
based on IP and TCP / UDP with IPv6
support for 802.15.4 i.e 6LoPAN
• Topology support includes Mesh, Star
and Tree
• Can also be integrated with wired
networks using ethernet – ISA over
Ethernet
• To address interference issues over
wireless channels in the same band, it
uses frequency hopping spread spectrum
(FHSS) over a total of 16 channels.
• Channel blacklisting is also used to
further improved the quality
• Support tunnelling mode to allow legacy
data through the ISA100.11A network
• 128 bit AES to secure all communication.
Data link layer secures the frames with
each hopping and Transport layer
secures the pear-to-pear communication

15. CAN – Controller Area Network / CAN Bus
• CAN enables fast
communication between
electronic devices and
modules in vehicles
• It is a robust in-vehicle
bus standard designed,
supporting message based
communication
• It is a multi-master serial
bus standard for connecting
Electronic Control Units (ECUs)
• Allows microcontrollers and devices to
communicate with each other's applications
without a host computer
• In case if more than one device try to
transmit at the same time the highest
priority device is gets the chance to continue
while the other devises are put on hold
• ISO 11898-1 and ISO 11898-2
• It is a broadcast type bus
• 1 Mbit/second. Max cable 40m
• 120 Ohms cable

16. LPWAN – Low Power Wide Area Network
LoRaWAN LoRa SigFox
Symphony
Link
Weightless LTE-M NB-IoT

17. LoRa
• LoRa and LoRaWAN are different
• LoRaWAN is a protocol for WAN communications and
• LoRa is a technology for wide area network.
• LoRa is a non-cellular modulation technology for LoRaWAN
• LoRa is used primarily in two ways:
• One is LoRaWAN, predominantly deployed in Europe.
It has very small message capacity – 12 bytes.
• Another is Symphony Link, which is a product of Link
Labs.
• Symphony Link is a preoperatory wireless system
owned by Semtech, built on LoRa technology that is
designed to overcome the limitations of a LoRaWAN
systems
• Symphony Link is often included as a
component of more complex LoRa
networking solutions, used mostly in the
U.S. and Canada, and is designed for
industrial applications
• LoRa is a radio network technology used for
IoT solutions and has better link budgets
than other comparable radio technologies.
• However apart from some key European
markets, if one want to connect to LoRaWAN
networks—or use LoRa at all—one needs to
deploy their own network gateway

18. NB-IoT Narrow Band IoT
• NB-IoT is a 3GPP initiative
• Addresses the IoT needs of very low data rate
devices that can connect to mobile networks,
may often be powered by batteries
• It is a cellular standard for IoT devices to be
interoperable and more reliable
• Uses OFDM modulation
• The chips are complex, but the link budgets are
better
• Users get the high performance level associated
with cellular connections, at the cost of more
complexity and greater power consumption
• NB-IoT can be used to send and receive
small amounts of data—a few tens or
hundreds of bytes per day produced by
low data-generating IoT nodes/devices
• It supports message-based communication
with faster modulation rate that can
handle a lot more data than other low
power communication technologies
• It is non IP-based communication protocol
• It was developed for simple IoT
applications and is much more power
efficient than LTE-M but designed for more
infrequent communication

19. LTE-M
• LTE-M - Machine Type Communication, which
includes eMTC enhanced Machine Type Communication is a type
of low power wide area network (LPWAN) radio technology
standard from 3GPP
• IP based communication
• Higher data rate in comparison to NB-IoT
• Supports Mobility and Voice over the network
• But it requires higher bandwidth
• Due to its complexity it is less economical

20. SigFox
• SigFox is a proprietary Low
Power WAN network
• It has the lowest cost radio
modules
• Sigfox is uplink only.
• Downlink is possible, but
highly limited by bandwidth,
their link budget is not
supported to downlink
• Sigfox is an end-to-end
network and technology
company
• Advantage
• It consumes a low amount of power
• Works well for low power devices that transmit
infrequently
• It sends very small amounts of data at a very low rate
• It supports wide coverage in the areas the network is
implemented
• Disadvantage
• Network is deployed only in some geography
• Communication is better from the IoT node to endpoint
to the base station.
• Though it has bidirectional functionality, but its has
constrain to communicate from the base station back
to the endpoint
• Poor link budget for downlink than going up
• Mobility will be a problem with Sigfox device

21. RFID – Radio Frequency Identification
• RFID is a technology whereby
digital data encoded in RFID
tags or smart labels are
captured by a RFID reader
using radio waves
RFID is similar to barcoding in that data
from a tag or label are captured by a
device that stores the data in a database.
RFID, however, has several advantages
over systems that use barcode asset
tracking software. The most notable is that
RFID tag data can be read outside the line-
of-sight, whereas barcodes must be aligned
with an optical scanner.
RFID systems consist of three components:
• an RFID tag or smart label
• an RFID reader and …
• An antenna.
• RFID tags contain an integrated circuit and an
antenna, which are used to transmit data to the
RFID reader (also called an interrogator).
• The reader then converts the radio waves to a
more usable form of data.
• Information collected from the tags is then
transferred through a communications interface to
a host computer system, where the data can be
stored in a database and analysed at a later time.
• Active Tags Vs Passive Tags
• Passive tags must be “powered up” by the
RFID reader before they can transmit data
Source : AB&R®

22. Network Layer : Routing Protocols
• Standard and
non-standard
protocols for
routing
• Routing in
network layer
handles the
packet transfer
from source to
destination for
IoT applications
•Distance Vector IPv6 based routing protocol for low power lossy networks
•Builds a Destination Oriented Directed Acyclic Graph (DODAG) which can have only
one route from leaf node to the root
• Low rate beaconing used for maintain topology
• Routing info in datagram packet itself
RPL
• Routing base on AODV, extended for use in IoT
• Generation of Route Requests by the originator i.e LOADng router for path discovery to
the destination
• Intermediate nodes receives the route request and forwards the request to the next
node until the request reaches the destination LOADng router
• Destination router generates the route reply and the route is established
LOADng
•Channel-Aware Routing Protocol (CARP) is designed for underwater communication
and used in IoT
•It is a distributed routing protocol and uses lightweight packets
•Uses link quality as a parameter to establish the route, which is computed based on
successful historical transmission. This quality parameter is gathered from
neighbouring sensors, based on which it selects the forwarding nodes.
CARP

23. Network Layer : Encapsulation Protocols
• Problem with IoT
applications is that IPv6
addresses are too long
and cannot fit in most
IoT datalink frames
which are relatively
smaller
• IETF has developed a
set of standards to
encapsulate IPv6
datagrams in different
datalink layer frames
for use in IoT
applications
•Low power Wireless Personal Area Network over IPv6
•Allows low power resource constrained devices to connect to Internet
•Most common standard for Ipv6 encapsulation
•Allows 802.15.4 radio to carry 128 bit address of IPv6. This is active through
header compression, translation and reformatting
•IETF RFC 5933 and RFC 4919
6LoPAN
•6TiSCH is developed by a different group in IETF, for Time-Slotted Channel
Hopping (TiSCH) mode of IEEE 802.15.4e datalinks
6TiSCH
• This again is a group in IETF to address fitting the IPv6 into data
links other than what is addressed by 6LoPAN and 6TiSCH
6LO

24. Session Layer Protocols
MQTT SMQTT AMQP
XMPP DDS

25. MQTT
• A lightweight text based
messaging protocol based on
publish-subscribe architecture
• Uses TCP/IP
• Provides message based
communication between
application & middleware on one
side, and network and
communication on other side
• The system consists of three main
components:
• Publishers
• Subscribers, and
• Broker
• Publishers are lightweight sensors that connect to
the broker to transmit their data and go back to
sleep
• Subscribers are applications that are interested in
the sensory data based on topic, it subscribes to
the broker to be informed whenever relevant data
is received
• The brokers classify sensory data into topics and
send them to subscribers who has subscribed to
the topics
• A Topic is a simple string that can have hierarchies
and wild cards separated by a “/”
• A topic can look like the following …
• home/kitchen/temperature OR
• home/+/temperature (sends the temperature of
all areas of home

26. SMQTT – Secure MQTT
• SMQTT is the secured version of the
MQTT which uses encryption based on
lightweight attribute
• The main advantage of using such
encryption is the broadcast
encryption feature, in which the
message is encrypted and delivered to
multiple other nodes
• Algorithm consists of four main
stages:
• Setup
• Encryption
• Publish
• decryption
• In the setup phase, the subscribers
and publishers register themselves to
the broker and get a master secret
key according to their developer’s
choice of key generation algorithm
• When the data is published, it is
encrypted, published by the broker
and sends it to the subscribers who
finally decrypts. The subscriber
should be having the same master
secret key for successful decryption
• It is to be noted that the key
generation and encryption algorithms
are not standardized

27. AMQP – Advance Message Queuing Protocol
• AMQP is a session layer protocol
• It is designed to connect between
systems and business processes
supporting inter organization
communication
• It uses a publish/ subscribe
architecture implemented using TCP
• Basic unit of data is frames
• Here the broker is divided into two
main components:
• exchange
• queues
• The exchange receives the messages
from publisher (IoT nodes) and
distributing them to queues based
on pre-defined roles and conditions.
• Queues represent the topics and
subscribed by subscribers which will
get the sensory data whenever they
are available in the queue
• RabbitMQ uses AMQP

28. CoAP - Constrained Application Protocol
• CoAP is a session layer protocol which
provides lightweight RESTful (HTTP)
interface
• Representational State Transfer (REST) is a
standard interface between HTTP client and
servers
• REST could result in significant overhead
and power consumption making it unsuitable
for use in IoT
• CoAP is designed for IoT and enables low-
power sensors to use RESTful services while
meeting their low power requirement
• It is built over UDP, instead of TCP and has
a mechanism to provide reliability
• CoAP architecture has two sublayers:
• messaging
• request/response
• The messaging sublayer is responsible
for reliability of the communication
and ensure no duplication of
messages
• Request/response sublayer is
responsible for communication

29. Comparison of Session Protocols
Protocol UDP/TCP Architecture Security &
QoS
Header Size Max Length
(Bytes)
MQTT TCP Pub/Subscriber Both 2 5
AMQP TCP Pub/Subscriber Both 8 -
CoAPP UDP Req/Response Both 4 20 (typical)
XMPP TCP Both Security - -
DDS TCP/UDP Pub/Subscriber QoS - -

30. Thank You
Nagesh T. Rao
nagesh_t_rao@hotmail.com