Communication Options

for IoT

Credits: Marco Zennaro, PhD

Ermanno Pietrosemoli, ICTP ICTP
Andri Yadi
Parameters
When considering communications options,
parameters to be taken into account are:

Range Cost (device)

Multihop capabilities Cost (service)
Battery consumption Availability
Security Regulation
IoT specific case
IoT nodes can accept:

Low throughput, for many applications

Delays

Long Sleeping times

Options
We will consider the following options for IoT
communications:
802.15.4 WiFi
Zigbee Cellular based
RFID Satellite
Bluetooth and BLE TV White Spaces
(Bluetooth Low Energy) LPWAN
802.15.4
802.11 – Wireless Local Area Networks (WiFi)
802.11a, 802.11b, 80211g, 802.11n
802.15 – Wireless Personal Access Networks (WPAN)
Task Group 1 – Bluetooth (802.15.1)
Task Group 2 – Co-existence (802.15.2)
Task Group 3 – High Rate WPAN (802.15.3)
Task Group 4 – Low Rate WPAN (802.15.4 or 802.15 TG4)
Task Group 5 – Mesh Networking (802.15.5)
802.16 – Wireless Metropolitan Area Networks (WiMax)
802.20 – Mobile Broadband Wireless Access (Mobile-Fi) - Defunct
802.22 – Wireless Regional Access Network (WRAN)
Utilize free space in the allocated TV spectrum
802.15.4
This standard defines a communication layer at level 2 in the
OSI (Open System Interconnection) model. Its main purpose
is to let the communication between two devices.

It was created by the Institute of Electrical and Electronics

Engineers (IEEE), entity which main task is to set standards
so that technological developments can count with a common
platform of rules to be set over.
OSI model
802.15.4
Channels:

868.0 - 868.6MHz -> 1 channel (Europe)

902.0-928.0MHz -> 10 channels (USA)
2.40-2.48GHz -> 16 channels (Worldwide)

Bit Rates:

868.0 - 868.6MHz -> 20/100/250 Kb/s

902.0-928.0MHz -> 40/250 Kb/s
2.40-2.48GHz -> 250 Kb/s
802.15.4 – topologies
Networks can be built as either peer-to-peer or star
networks.

However, every network needs at least one node to work as

the coordinator of the network.

Each device has a unique 64-bit identifier, and if some

conditions are met short 16-bit identifiers can be used within
a restricted environment. Namely, within each PAN domain,
communications will probably use short identifiers.
802.15.4 – topologies
802.15.4 – characteristics
Range 10m
Multihop capabilities no
Battery consumption low
Security no
Cost (device) low
Cost (service) free
Availability good
Regulation good
Zigbee
This standard defines a communication layer at level 3 and
upper in the OSI model. Its main purpose is to create a
network topology (hierarchy) to let a number of devices
communicate among them and to set extra communication
features such as authentication, encryption, association and
in the upper layer application services.

It was created by a set of companies which form the ZigBee

Alliance.
Zigbee – node types
Co-ordinator: all ZigBee networks must
have one (and only one) Co-ordinator
Zigbee
The tasks of the Co-ordinator at the network layer are:

1. Selects the frequency channel to be used by the network (usually the

one with the least detected activity)
2. Starts the network
3. Allows other devices to connect to it (that is, to join the network.

The Co-ordinator can also provide message routing (for

example, in a Star network), security management and other
services.
Zigbee – node types
End Devices are always located at the
extremities of a network:
Zigbee
The main tasks of an End Device at the network level are
sending and receiving messages. Note that End Devices
cannot relay messages and cannot allow other nodes to
connect to the network through them.

An End Device can often be battery-powered and, when not

transmitting or receiving, can sleep in order to conserve
power.
Zigbee – node types
Networks with Tree or Mesh topologies
need at least one Router.
Zigbee – characteristics
Range 10m
Multihop capabilities yes
Battery consumption low
Security yes
Cost (device) low
Cost (service) free
Availability good
Regulation good
RFID
RFID is a very successful application of short distance radio
technology. It uses an object (typically referred to as an RFID
tag) applied to a product, animal, or person for the purpose
of identification and tracking.

The tag maybe passive, in which case it will just modify the
signal transmitted to it by a short distance reader or active
in which case the reader might be at several meters of
distance and beyond LOS.
RFID
RFID
Used in shops to expedite check out, automate inventory
control and for theft prevention.

Embedded in passports and in even in animals.

May be read only, like for inventory control applications, or

writeable for more advanced ones.

Have been implanted in humans.

RFID
RFID frequencies of operation
Band Regulation Range Data speed

120-150 kHz Unregulated 10 cm low

13.56 MHz ISM 10 cm-1 m low to moderate

433 MHz SRD (Europe) 1-100m moderate

865-868 MHz SRD (Europe) 1-12 m moderate

902-928 MHz ISM (US) 1-12 m moderate to high

2400/5825 MHz ISM 1-2 m High

RDIF – characteristics
Range 1m
Multihop capabilities no
Battery consumption low
Security yes
Cost (device) low
Cost (service) free
Availability good
Regulation good
Bluetooth

79 channels 1 MHz wide and frequency hopping to

combat interference in the crowded 2.4 GHz band.

Used mainly for speakers, health monitors and other short

range applications.
Bluetooth architecture
Master node controls up to 7 active slave nodes and up 255
inactive nodes, forming a piconet.

Several piconets can form a scatternet by leveraging

bridging nodes associated to more than one master.

Slaves must communicate through the master node.

Bluetooth architecture
Bluetooth Low Energy (BLE)
Subset of Bluetooth 4.0, but stemming from an independent
Nokia solution.
Smart Mesh.
40 channels 2 MHz wide and frequency hopping to combat
interference.
Used in smartphones, tablets, smart watches, health and
fitness monitoring devices.
Bluetooth – characteristics
Range 10m
Multihop capabilities no
Battery consumption low
Security yes
Cost (device) low
Cost (service) free
Availability good
Regulation good
GSM in Rwanda

https://data.worldbank.org
3GPP
LTE cat 0 LTE cat M1 LTE cat NB1 EC-GPRS LTE cat 1 GSM 900
(eMTC) (NB IoT)

DL BW 20 MHz 1.4 MHz 180 kHz 200 kHz 20 MHz 200 kHz

UL BW 20 MHz 1.4 MHz 180 kHz 200 kHz 20 MHz 200 kHz

DL Peak 1 Mb/s 1 Mb/s 250 kb/s 10 kb/s 10 Mb/s 22.8 kb/s

rate

UL Peak 1 Mb/s 1 Mb/s 250 kb/s 10 kb/s 5 Mb/s 22.8 kb/s

rate (Multitone
) 20 kb/s
(Single
tone)

Duplex half or full half or full half half full full

3GPP
FiPy
GSM – characteristics
Range infinite
Multihop capabilities no
Battery consumption medium
Security yes
Cost (device) medium
Cost (service) high
Availability good
Regulation good
WiFi

Credit: WiFi Aliance

IEEE 802.11 Amendments
802.11ah (WiFi HaLow)
Sub 1 GHz, most commonly 900 MHz
Low power, long range WiFi, less attenuated by walls and
vegetation.
Up to 1 km range.
Lower power consumption thanks to sleep mode capabilities.
1, 2, 4, 8 and 16 MHz channels.
Competes with Bluetooth, speed from 100 kb/s to 40 Mb/s.
Support of Relay AP to further extend coverage.
WiFi – characteristics
Range 1km
Multihop capabilities no
Battery consumption mid
Security yes
Cost (device) low
Cost (service) free
Availability good
Regulation good
Satellite
Satellite
Satellite – characteristics
Range infinite
Multihop capabilities no
Battery consumption high
Security no
Cost (device) medium
Cost (service) medium
Availability low
Regulation poor
TVWS
In telecommunications, white spaces refer to
frequencies allocated to a broadcasting service but
not used locally.

In addition to white space assigned for technical reasons,

there is also unused radio spectrum which has either never
been used, or is becoming free as a result of technical
changes.
TVWS
Weightless is a royalty-free open standard focused on M2M
(Machine to Machine Communication).

It uses frequency hopping at the frame rate to minimize the

impact of interference - both received and caused.
It has been designed to minimize costs and power
consumption employing a highly efficient MAC-level
protocols that result in small headers per transmission.
TVWS – characteristics
Range 10km
Multihop capabilities no
Battery consumption medium
Security yes
Cost (device) high
Cost (service) free
Availability low
Regulation poor
LPWAN
LPWAN
Low Power, Wide Area Networks

Connectivity designed specifically for IoT

Low data throughput = High sensitivity = Long range

(Relatively) low cost

Using licensed or unlicensed spectrum

LPWAN
LPWAN
LPWAN
Sigfox
Ultra narrowband technology designed for low throughput
and few messages/day. Low consumption, low cost

High receiver sensitivity: -134 dBm at 600 b/s or - 142 dBm

at 100 b/s on a 100 Hz channel, allows 146 to 162 dB of link
budget.

Each message transmitted 3 times in 3 different frequencies

offering resilience to interference.
Sigfox
Unlicensed frequencies: 868 MHz in Europe, 915 MHz in US.

Maximum of 140 uplink messages/day with 12 octets

payload, 26 octets total with overhead.

Maximum of 4 downlink messages/day with 8 octets payload.

Mobility restricted to 6 km/h.

Sigfox
Partnerships with cellular providers with an aim to
worldwide penetration.

Many network operators worldwide offer Sigfox services

on a subscription basis.

Cloud managed leveraging SDR to offer many services.

Coarse geolocation capability without GPS.
Roaming capability.
Sigfox coverage
Sigfox – characteristics
Range 10km
Multihop capabilities no
Battery consumption low
Security yes
Cost (device) low
Cost (service) low
Availability low
Regulation good
What is LoRa
Wireless modulation technology, based on Semtech’s
proprietary Chirp Spread Spectrum (CSS)

Physical (PHY) layer for long range wireless communications

Operates in the license-free Industrial Scientific Medical
(ISM) bands all around the world

Based on spread spectrum, trading bandwidth for S/N.

What is LoRa
Sub-GHz frequency, e.g: 433, 868, 915 MHz, depends on the
country’s regulation

Regulated power, duty-cycle, and bandwidth.

E.g: in EU, 1% per sub-band duty-cycle limitation (per hour,

meaning transmission is allowed for 36 sec in each 1 hour)

In Rwanda?
LoRa modulation
Uses linearly varying frequency pulses called
“chirps” inspired in radar signals.
LoRa Physical Layer

Preamble: at least 10 up-chirps Data: information transmitted by the

followed by 2.25 down-chirps instantaneous frequency transitions
What is LoRa
LoRa frequency bands
LoRa nodes
What is LoRaWAN
Communications protocol and architecture utilizing the LoRa
physical layer

Open Source and freely available, specified by LoRa Alliance

Star of Starts Topology. Nodes connect to multiple

gateways
What is LoRaWAN
Adaptive Data Rate (ADR) to improve performance

Built-in multiple levels of security: network or application

level encryption, frame counter, etc
LoRaWAN end device/mote
Communicates with LoRaWAN gateways, never
directly with other motes.

Has 64 bit globally unique identifier: DevEUI.

When joining a network, it receives a 32 bit unique identifier:

DevAddr.

Defined 3 device classes: A, B, and C

LoRaWAN device classes
LoRaWAN architecture
LoRaWAN products
LoRaWAN – characteristics
Range 10km
Multihop capabilities no
Battery consumption low
Security yes
Cost (device) low
Cost (service) free
Availability good
Regulation good
Summary
We analyzed different communication options for
IoT.
We looked into details of LPWAN.
We've seen why LoRaWAN is a good candidate for
applications.
Feedback?
Email me mzennaro@ictp.it