senigallia, 18-19 june 2007

Senigallia, 18-19 June 2007

European Workshop

ICT and Civil Protection:

current state and future scenarios

ICT and Civil Protection Senigallia, 18-19 June 2007

Wireless sensors solutions for

environmental monitoring applications: why?

Advantages:

- No connection problems due to distance between the sensor and the LWU and obstacles between them

- Freedom in the choice of the installation place

- Easy to connect (plug and play solution)

- Unlimited diffusion of the data (with access key)

- Fast and easy to install and to mantain (there is no need of qualified people to do it)


Wireless sensors solutions for environmental monitoring applications: architecture


Wireless sensors solutions for environmental monitoring applications: protocols

The wireless solution in the field of sensors presents wide sperimental andinnovation margin. This solutions can be searched inside various polifunctionalstandard, that can be classified depending on the working area:

• WPAN (Wireless Personal Area Network)– BlueTooth (IEEE 802.15.1)– BlueTooth 2 (IEEE 802.15.3)– ZigBee (IEEE 802.15.4)– sensori smart WPAN (IEEE P1451.5a)– WUSB a basso rate (Wireless Universal Serial Bus su LR-WPAN, IEEE 802.15.4)– WUSB ad alto rate (Wireless Universal Serial Bus su HR-WPAN, IEEE 802.15.3)– Wireless Firewire (IEEE1394, UWB)

• WLAN (Wireless Local Area Network, IEEE 802.11)– WiFi (IEEE 802.11b-g)– sensori smart WLAN (IEEE P1451.5b)

• WMAN (Wireless Metropolitan Area Network, IEEE 802.16)– sensori smart WMAN (IEEE P1451.5c)– WiMAX (IEEE 802.16)


Wireless sensors solutions for environmental monitoring applications

• The possible solutions, arranged on the previous categories, can be compared referring to the specific requests and the additional parameters; principally:

– Number of connecting sensor– Cost – Power / consumption– Safety – Hardiness / EMC– Distance – Performance (error rate)– Compactness – Transmission speed

• Inside the large range of possible solutions showed before, the choice must be restricted toward one of this two standards: ZigBee or WUSB; for each of them here are some of the principal characteristics:


• Datarate: 62.5 kbps max;

• Star topology;

• Spatial coverage from a minimum of 10m to 50m in open space;

• Transmitted signal modulation DSSS type (Direct Sequence Spread Spectrum)

• Dinamic adressing of the devices;

• Transmission affidability;

• Low consumption (average current 90µA);

• 79 channels in ISM band at 2.4GHz, that through a mulplation technique of the code can be used to reach a maximum of 3871 simultaneous communications;

• Duty-cycle 1%;

• Low unitary cost of the devices.

WUSB characteristics


• Datarate: 250 kbps max, 20 kbps and 40kpbs ;

• Star topology or peer to peer topology;

• Spatial coverage from a minimum of 10m to 100m in open space;

• Transmitted signal modulation DSSS type (Direct Sequence Spread

Spectrum)

• Dinamic adressing of the devices (till 65536 connected nodes);

• Transmission affidability;

• Low consumption (average current 40µA);

• 16 channels in ISM band at 2.4GHz, 10 channels in ISM band at

915MHz and one channel in the European band at 868MHz;

• Duty-cycle < 0.1%;

ZigBee/802.15.4:characteristics


Operating systems for wireless sensors

• The properties of a wireless sensors network impose the use of an

operating system, that considers:

– Small hardware dimensions and low energy avaliability

– High number of events in the use of sensors network

– Low parallelism level of the sensors network

– Need to adequate the same kind of software to different hardware

devices

– Tolerance to damages in sensors network that work in critical

environment


Operating systems for wireless sensors

• An operating system for wireless sensors must be characterized from:

– Simplicity: it must avoid operations unuseful and hard working for the operating system

– Energetic saving: it must turn off the hardware resources when not working

– Efficency: it must fastly manage a large quantity of events to avoid losing precious information

– Low parallelism: fast access to the hardware and low execution overhead

– Modularity: it must grant reusability and maintenance of the software

– Failure tolerance: it must support the development of reliable distributed solutions


TinyOS

• Open source operating system for wireless sensor network

• Developed by Berkley’s University and by the Intel research center (www.tinyos.net).

• TinyOS has been developed with the following objectives:

– Reduce energy consumption, computational charge and memory occupation

– Support intensive contemporaneous, robust, efficient and modular operations requests

• The result is an operating system characterized by:

– Reduced kernel that allows the direct access to the hardware

– The memory is considered as a unique and linear physical space, allocated at compilation time

http://www.tinyos.net/

http://www.tinyos.net/scoop/


TinyOS

• TinyOS is a very small dimensions operaing system

• To satisfy the efficency requirement, TinyOS has been implemented

following the events model.

• In the field of wireless sensors network, the external events based approach

allows to use the hardware resources in the most efficient way.

• To satisfy the modularity requirement, TinyOS has been implemented

using a components model.

• Each component present in TinyOS is an independent software unit

provided with interfaces.

• The TinyOS system and its applications are written in NesC language.

http://www.tinyos.net/scoop/


Wireless intelligent sensors- General characteristics -

• Radio link between the sensor and the LWU (local web unit)

• Used frequency range: ISM 2,4GHz

• The use of this particular range allows to operate freely without the need

of licenses or grants dealing with the European Standards EN 300-220-3,

EN 3001-489-3 and to the raccomandations CEPT-ERC-REC 70-03

• Software selectable number of useful channels : 12

• Communication protocol from sensors to the Zbee LWU

• Transmission rate: 9600bit/s

• Number of connectable sensors 20

• Normal polling cicle: 30 minutes (programmable from 15 minutes to 24

hours)


Wireless intelligent sensors- General characteristics -

• Fast polling cycle: 3 minutes

• Each sensor clock interlocked with the LWU one

• Auto configuration of every sensor inside the LWU network

• Distance between the sensor and the LWU:

• superior to 300m without obstacles between the terminals

• superior to 30m in presence of obstacles that obstruct the visibility

• Non rechargeable power batteries

• Power and voltage of the batteries: depending on the sensor

• Battery life: superior to 6/12 months depending on the sensor


- Termoigrometer -Every minute, acquisition of temperature and relative damp values.Validation, through apposite algorithm, of the acquired values.Maximum and minimum values calculation, in the record interval.

• Temperature range: –30°C +50°C• Temperature values accuracy: 0,3°C• Range: 0% 100% • Accuracy: 3%

4 batteries size “C” Absorption during measurement 5mAStand-by absorption 100AAverage absorption including radio module 0,5mAWorking autonomy superior to 12 months


- Anemometer -

Acquisition of speed values every 5 seconds.Validation, through apposite algorithm, of the acquired values.Maximum and minimum values calculation, in the record interval.• Measurement range: 0m/s 50m/s • Measurement accuracy: 0,5m/s



- Gonioanemometer -

Acquisition of speed values every 5 seconds.Validation, through apposite algorithm, of the acquired values.Maximum and minimum values calculation, in the record interval.

• Measurement range: 0° 360°• Measurement accuracy: 2°



- Rainfall sensor-

Registration of the single tip and of the tipping Instant.Measures compensation algorithm due to the rain intensity.

Measurement range: 0 a 300mm/h• Measurement accuracy: 3%

4 batteries size “C”

Working autonomy superior to 12 months


- Ultrasonic level sensor -

Acquisition of water level every 2 minutes.Validation, through apposite algorithm, of the acquired values.Maximum and minimum values calculation, in the record interval.

• Measurement range: 1cm • Measurement accuracy: 0,5m 6m

4 batteries size “D” Absorption during measurement 50mAStand-by absorption 100AAverage absorption including radio module 2mAWorking autonomy superior to 6 months


- LWU (local web unit) -

The LWU picks up the data sent via radio from the sensors and through a web server.

It sends the data via GPRS or UHF radio module, with a 9600bit/s modem to the

center.

The power for Rx/Tx devices and the Web server it is given by a battery and a solar

panel.

Composition of the LWU:

• Tx/Rx ISM module for the sensors connection

• Web server

• Radio device for the connection with the

“Access point”

• Average absorption of ISM module during the

connection with the sensor: ≤ 50mA


- LWU -

• Average absorption of the radio device during the connection with the “Access

Point”: ≤ 800mA

• Average absorption of the system: ≤ 65mA

• Autonomy without sunstroke: >30gg

The alternative modules to the radio are:

• GPRS module

• Trasmitter receiver in UHF band with data

•speed trasmission 9600bit/s (GP340 data)

senigallia, 18-19 june 2007

Documents

wireless sensors solutions

zigbee ieee

civil protection senigallia

cwimax ieee

wifi ieee

sensori smart wpan ieee

wireless firewire ieee1394

protocolsthe wireless