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Internet of Things

Lecture 2 - Wireless Sensor Networks

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1980

2010

2020

Moore

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Procesare

Era informației

More than Moore

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Detecție

Era interacției

Beyond Moore

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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
    • 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 communicates directly with the GW
    • May need a high transmission power
    • May not be feasible to cover a wide area
  • Mesh topology (multi-hop)
    • Sensors act as forwarders for other nodes
    • This may reduce 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:
    • Distributed Sensor Nets Workshop (1978)
    • Distributed Sensor Networks (DSN) program (early 1980s)
    • Sensor Information Technology (SensIT) program

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  • 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)

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  • Sensinode (2005) aquired by ARM in 2013

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Sensor Nodes

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What is a Mote?

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  • mote   noun [C] LITERARY�something, especially a bit of dust, that is so small it is almost impossible to see�---Cambridge Advanced Learner’s Dictionary

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Sensor Node Components

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  • Low-power microcontroller
    • Limited computing power
    • OSes: NuttX, Contiki, TinyOS, etc.
  • Sensors
    • Scalar: temperature, light, etc.
    • Image sensors, microphones, etc.
  • Memory
    • Limited capacity
  • 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 => Usually low data rate
  • 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)
    • Prevalent in nodes without strict energy constraints
    • Medium power consumption
    • Used frequently in commercial solutions
  • Bluetooth Low Energy standard (BLE)
    • Low power consumption
    • Used in many commercial solutions

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Network Communication

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Network Communication

  • Networking is a key component (protocol stacks)
  • Addressing schemes (IPv4, IPv6/6LoWPAN)
  • 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

Lecture 2 - WSN

Microsal

UPB

Sparrow

UPB

ESP32 Sparrow

UPB

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UC Berkeley Sensor Nodes

  • UC Berkeley hardware platform evolution

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Sparrow Nodes (v3 & v4)

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  • Low-power MCU
  • 2.4GHz transceiver
    • Works with IEEE 802.15.4
    • 256kbps transfer speed
  • Temperature, humidity, light sensors
  • 9-DOF IMU
  • 16MHz
  • 8KB RAM
  • 128KB Flash
  • ~ $10
  • 50mW, 36uW (sleep)
  • 7g, 50x30x5mm

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Sparrow Nodes vs IBM PC

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  • 16MHz
  • 8KB RAM
  • 128KB Flash
  • ~ $10
  • 50mW, 36uW (sleep)
  • 7g, 50x30x5mm
  • 4.77MHz
  • 16-256KB RAM
  • 160KB Floppies
  • ~ $6,000
  • ~ 64W
  • 12kg, 500x140x400mm

IBM PC Original (1981)

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ESP32 Sparrow

  • ESP32 microcontroller
    • Wi-Fi, BLE
    • GPIOs
  • BME680 sensor - temperature, humidity, pressure, gas (VOC)
  • Light sensor
  • OLED screen, microphone
  • SD card reader
  • Low power, low cost
  • Arduino-compatible

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Source: https://github.com/dantudose/ESP32-Sparrow-rev2

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Sparrow ESP32

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WSN Applications

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Sparrow Sensor Nodes @ UPB

  • Low-power (13mA Runtime, 6uA Sleep)
  • Autonomy measured in years
  • May run many OSes and protocol stacks
  • Arduino compatible
  • Designed for energy harvesting

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Sparrow - Technical Specs

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Sparrow - Technical Specs

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Range

Humidity

Meas. interval: 0 … 100 %

Meas. error: ± 2% RH

Luminosity

 

Meas. interval: 0...100000lux Visible & IR

UV index

 

Temperature

Meas. Interval: -40 … 100˚C

Meas. error: ±0.5˚C

 

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Deployment: Off-grid building

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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
  • Achieves total energy independence in outdoor & indoor scenarios

PV panel

with DC/DC

converter

20F Supercap

Regular Sparrow Node

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Results

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  • Adaptive duty-cycling
    • 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 when there is a minor earthquake

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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
  • Monitor vibrations
    • High-precision accelerometer
  • 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
    • simulated 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

  • Treatment of xerostomia
  • Neuro-electrostimulator for the salivary glands
  • Measured the level of salivary pH and humidity in the oral cavity
  • Stimulate the salivary glands to produce more saliva
  • Miniaturized dental implant incorporated in a dental crown

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Microsal – Salivary Pacemaker

  • Connectivity to a tablet through BLE
    • See logged data
    • Set parameters
  • Data send and stored in Cloud

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Microsal – Salivary Pacemaker

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Microsal – Salivary Pacemaker

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Keywords

  • Wireless Sensor Networks
  • Sensor node
  • Mote
  • Single-hop
  • Multi-hop
  • Sparrow

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Lecture 2 - WSN