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Internet of Things

Lecture 2 - Wireless Sensor Networks and Applications

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1980

2010

2020

Moore

Procesare

Era informației

More than Moore

Detecție

Era interacției

Beyond Moore

Actuare

Era îmbunătățirii

Laptop

Personal Computer

Creștere exponențială

Smartphones

Tablets

Servitori Robotici

Vehicule

Autonome

Wearables

Drone

Smart

home

2040

Contopire?

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Wireless Sensor Networks

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Wireless Sensor Networks

Hundreds/thousands of sensors nodes
Monitor environment parameters
Gateway/base station/sink

Receive data from nodes
Send commands to nodes

Storage, analysis, processing in cloud

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Characteristics

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Small size

Low bandwidth (10s-100s kbps)

Star and mesh topology

Low power, battery operated

Low cost

Ad-hoc network

Unreliable wireless medium

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Single-Hop versus Multi-Hop

Star topology (single-hop)

Sensors communicate directly with the GW
May need a high transmission power
May not be feasible to cover a wide area
Does not scale well
No routing protocol

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Source: https://www.lprsiot.com/networks/

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Single-Hop versus Multi-Hop

Mesh topology (multi-hop)

Sensors act as forwarders for other nodes
This may reduce overall the energy consumption
May increase coverage
Routing protocol

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Source: https://www.lprsiot.com/networks/

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Brief History

DARPA (US army):

Distributed Sensor Nets Workshop (1978)
Distributed Sensor Networks (DSN) program (early 1980s)
Sensor Information Technology (SensIT) program

UCLA and Rockwell Science Center

Wireless Integrated Network Sensors (WINS)
Low Power Wireless Integrated Microsensor (LWIM) (1996)

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Brief History

UC-Berkeley

Smart Dust project (1999)
The concept of mote

Berkeley Wireless Research Center (BWRC)

PicoRadio project (2000)

MIT

μAMPS (micro-Adaptive Multidomain Power-aware Sensors) (2005)

Sensinode (2005) aquired by ARM in 2013

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Sensor Nodes

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Sensor Node Components

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Low-power microcontroller

Limited computing power
Bare-metal code (Arduino)
OSes: NuttX, Zephyr, Contiki, RIOT, FreeRTOS, etc.

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Sensor Node Components

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Sensors

Scalar: temperature, light, humidity, etc.
Image sensors, microphones, etc.

Memory

Limited capacity

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Sensor Node Components

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Radio Transceiver

Low-power
Low data rate, limited range

Actuators
Power supply: batteries, energy harvesting

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Network Communication

Low-power
Low-cost
Low data rate (Kbps-Mbps)

Enough for sensor data

Strong power consumption constraints

=> energy limits bandwidth

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Network Communication

IEEE 802.15.4 standard

Designed for WSN networks
Low power consumption
Short to medium range communication (max 100m)
Low data rate (250 kpbs)
ZigBee and 6LoWPAN are based on it
Widespread use in academic or commercial solutions

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Network Communication

IEEE 802.11 standard (Wi-Fi)

For nodes without strict energy constraints
Medium power consumption
Widely used in commercial applications

Bluetooth Low Energy standard (BLE)

Low power consumption
Used in many commercial solutions
Nodes communicate with a mobile device

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Network Communication

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Source: https://arxiv.org/pdf/1611.00861.pdf

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Network Communication

Protocol stacks
Addressing schemes (IPv4, IPv6)
Data transmission (802.15.4, WiFi, BLE, LoRa, LTE, 5G, etc.)
Transfer rate (Kbps, Mbps, Gbps)
Application layer (CoAP, MQTT, HTTP, etc.)

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Examples of Sensor Nodes

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MicaZ, Mica2, Mica2 Dot

UC Berkeley

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Microsal

UPB

Sparrow

UPB

ESP32 Sparrow

UPB

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IoT Research @ UPB

Sparrow

designed for energy harvesting research

Ultra Low-power
Protocol stacks and Real-Time OSes
Arduino compatible!
Days to years of battery lifetime

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Sparrow Nodes (v3 & v4)

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Low-power MCU
2.4GHz transceiver

IEEE 802.15.4
256kbps

Temperature, humidity, luminosity
9-DOF IMU

16MHz
8KB RAM
128KB Flash
50mW, 36uW (sleep)
7g, 50x30x5mm
~ $10

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ESP32 Sparrow

ESP32-C6 microcontroller (dual core)
Wi-Fi, BLE
Temperature, humidity, pressure, and air quality sensor (I2C)
3-axis accelerometer and gyroscope (I2C)
Ambient light sensor (I2C)
64 MB Flash memory (SPI)
128x32 OLED display (I2C)

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Source: https://github.com/dantudose/ESP32-Sparrow-rev3

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ESP32 Sparrow

High-quality digital microphone (I2S)
Neopixel RGB LED (GPIO)
SD card slot (SPI)
Low power, low cost
Arduino-compatible
NuttX, Zephyr OS

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Source: https://github.com/dantudose/ESP32-Sparrow-rev3

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Sparrow ESP32

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Source: https://github.com/dantudose/ESP32-Sparrow-rev3

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Applications

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Deployment: Off-grid building

Sparrow nodes deployed in the "passive house" (energy efficient)
Rainwater harvesting
Photovoltaic panels
Thermal insulation
Energy-efficient HVAC system
Canadian well

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Floor plan

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Energy-Independent Indoor WSN

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Employs energy harvesting
Miniature Solar Panel
Ultra low-power DC/DC
Super-capacitor storage
Total energy independence
Outdoor & indoor
Mounted on the wall

PV panel

with DC/DC

converter

20F Supercap

Regular Sparrow Node

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Results

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Adaptive duty-cycling => high availability

adjust data transmission frequency to available energy

Voltage between 2.2V and 3V

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Results

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Seismic Building Monitoring

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Measuring and monitoring seismic activities
How buildings behave during a minor earthquake
Weekly earthquakes in Vrancea area

magnitude 3-4 on Richter scale

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Seismic Building Monitoring

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Platform Design

Sparrow nodes
Attached to the outside of buildings walls, on different floors
High-precision accelerometer

Monitor vibrations

Very high energy availability

Large battery
Autonomy of at least one year

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Communication

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Experimental Setup

Seismic shake table

slide and vibrate in two axes
simulates the resistance structure of a building using a metallic structure

At each level - a sensor node

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Results

Seismic waves on each floor
Behavior is completely different depending on the distance from the base

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Microsal – Salivary Pacemaker

Neuro-electrostimulator for salivary glands
Treatment of xerostomia
Level of salivary pH and humidity in the oral cavity
Stimulate the salivary glands to produce more saliva
Miniaturized dental implant

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Microsal – Salivary Pacemaker

Connectivity to a tablet through BLE

Receive and visualize collected data
Set parameters for neural stimulation

Data is sent and stored in Cloud

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Microsal – Salivary Pacemaker

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Microsal – Salivary Pacemaker

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