rf technologies for wireless sensor networks
DESCRIPTION
Tim Cutlers seminarie om trådlösa sensornätverk från Scanautomaticmässan 2010 i Göteborg.TRANSCRIPT
Confidential & Proprietary RF Monolithics, Inc.
RF Technologies for Wireless RF Technologies for Wireless Sensor NetworksSensor Networks
ScanautomaticScanautomatic
Tim Cutler – Dir. Mktg. Tim Cutler – Dir. Mktg.
October 28, 2010October 28, 2010
Confidential & Proprietary RF Monolithics, Inc.
Agenda
l Introduction
l Characteristics of Wireless Sensor Networks
l Bluetooth
l ZigBee
l 802.15.4/6LoWPAN
l WiFi
l WirelessHART
l DASH7
l EnOcean
l Proprietary
Confidential & Proprietary RF Monolithics, Inc.
Introduction
l Who is RFM?
– Over 22 years experience in license-free module design and development
– Wide array of license-free wireless modules
• 802.11g/WiFi
• 802.15.4
• ZigBee
• WirelessHART
• Proprietary Frequency Hopping
• 900MHz and 2.4GHz
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Introduction
l Wireless Sensor Networks
– More sensors than there are people
– Application in a wide variety of markets
– Huge growth potential
l RF Technologies
– There are almost as many technologies as there are applications
– Which technology is best suited for which application?
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WSN Characteristics
l Key market drivers for WSN acceptance
– Low cost
– Simple to deploy
– Low maintenance
– Secure
– Reliable
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WSN Characteristics
l WSN solutions must:
– Consume small amounts of power
– Cover varying ranges - <10m to several 100s of meters
– Support large number of nodes
– Require little, if any, commissioning
– Not require mains power
– Be robust in noisy environments
– Be secure
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Bluetooth
l Standard, high data rate, frequency hopping technology
– Optimized for voice applications
l Frequency Hopping Technology
– Class I – 100mW ~ 100M
– Class II – 2.5mW ~ 10M
l Limited to 8 active nodes at a time
l Battery lifetimes range from a few hours to a few days
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Bluetooth
Cost Good
Power Consumption Fair
Deployment Ease Good
Network Size Poor
Security Good
Range Fair
Robustness Good
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Bluetooth Low Energy
l New standard, low data rate, frequency hopping technology
– Optimized for wireless sensing applications
l 260Kbps versus 3Mbps for Bluetooth
l Large number of periodically transmitting nodes
l Lower power consumption than Bluetooth
l New standard whose performance will need to be demonstrated in the field
Confidential & Proprietary RF Monolithics, Inc.
Bluetooth Low Energy
Cost Good
Power Consumption Good
Deployment Ease Good
Network Size Good
Security Good
Range Fair
Robustness Good
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ZigBee
l Standard, low data rate, direct sequence technology
– Utilizes 802.15.4 MAC and PHY layers with mesh networking layer
l Direct Sequence Technology
– ~8dB processing gain
– 16 channels
– 1mW and 100mW products available
l 250Kbps RF Data Rate
– Throughput is substantially less
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ZigBee
l Designed as low power, low data rate sensing technology
– Sleeping end nodes run for years on battery
– Routing nodes cannot sleep
l Extends coverage area through mesh technology
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ZigBee
Cost Good
Power Consumption Good
Deployment Ease Good
Network Size Fair
Security Good
Range Good*
Robustness Fair
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802.15.4
l Standards-based, low data rate, direct sequence technology
– Proprietary solutions, basically ZigBee without the mesh
l Direct Sequence Technology
– ~8dB processing gain
– 16 channels
– 1mW and 100mW products available
l 250Kbps RF Data Rate
– Throughput is less but better than ZigBee due to reduced overhead
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802.15.4
Cost Good
Power Consumption Good
Deployment Ease Good
Network Size Fair
Security Good
Range Fair
Robustness Fair
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6LoWPAN
l IPv6 over Low power Wireless Personal Area Networks
l Can use various transport mechanisms but early work has focused on 802.15.4
l Each node is natively addressable using IP
l Challenge is routing IP over lossy links
– IETF RoLL
– Header compression
l Allows larger networks
l To date, wireless performance is 802.15.4
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802.11a/b/g/n WiFi
l Standard, high data rate, direct sequence technology
– RF data rates from 1Mbps to 54Mbps in best effort approach
l Direct Sequence Technology
– Processing gain from 0 – 10dB
– 3-4 Non-overlapping channels
– RF Power typically up to 100mW
l Range enhanced by ubiquity of access points
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802.11a/b/g/n WiFi
l New technology has reduced power consumption
– Years of battery operation now possible
l Systems are inherently IP-based
– Well understood by IT departments
– Straightforward Internet access
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802.11g WiFi
Cost Good
Power Consumption Good
Deployment Ease Good
Network Size Good
Security Good
Range Good
Robustness Fair
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WirelessHART/ISA100
l HART standard has existed as a wired standard
– HART designed for process industries
– Version 7.0 of the HART standard added wireless
– Based on Dust’s TSMP
– TSMP uses 802.15.4 16 channels to create a 16-channel frequency hopping radio
– Sleeping routers can be battery powered
– Adds path diversity to frequency diversity to deliver very high reliable wireless performance
– Provides seamless connectivity of wireless devices to existing wired HART systems
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WirelessHART/ISA100
l ISA100 is the family of standards for wireless networks in industrial automation
– ISA100.11a is the first standard finalized and is focused at process industrial automation
– Based on Dust’s TSMP technology
– Very similar to WirelessHART
– Does not interoperate with WirelessHART even though the hardware platform is the same
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WirelessHART/ISA100
Cost Fair
Power Consumption Good
Deployment Ease Good
Network Size Good
Security Good
Range Good
Robustness Good
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DASH7 Mode 2
l ISO 18000-7
– Active RFID standard
– Recently announced Mode 2 Draft
• Targeting wireless sensing applications
– 433MHz
• 8 Channels – FSK modulation
• 1mW Transmit power (4500m LOS)
• 28K or 200K boost mode
• End node latency ~2 sec max
– Support for mobile end points
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DASH7 Mode 2
l Various profiles
– Supported through database approach
– Profile support for IPv6
l New proposed standard – Mode 2
– Some silicon available that can support Mode 2, more on the way
l Untested in the field
– Narrowband FSK technology
– Relies on infrequent transmissions to avoid interference
• Presumably by allowing a lot of time for retries
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DASH7 Mode 2
Cost Good
Power Consumption Good
Deployment Ease Good
Network Size Fair
Security Good
Range Good*
Robustness Fair
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EnOcean
l Originally developed for energy harvesting light switches
– 315MHz
– 868MHz
– Amplitude Shift Keying (AM Radio)
– 3mW RF Power; -95dBm receive sensitivity
– Overseen by EnOcean Alliance – ZigBee organization model
l Extended as Bi-directional transceivers for application in sensing applications
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EnOcean
l Field proven for lighting applications, bi-directional operation newer
l Standard profiles for variety of applications
– Development environment for custom applications
l Transmission rate dependent on energy available
– Support for energy harvesting
– Transceivers consume 25 – 40mA when operating
l Support for powered repeaters
l Simple protocol
– Well suited to simple applications
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EnOcean
Cost Good
Power Consumption Good
Deployment Ease Good
Network Size Fair
Security Fair
Range Good*
Robustness Poor
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Proprietary
l Proprietary = Single Sourced
l Most proprietary solutions use Frequency Hopping technology
– Provides best immunity to interference and fading
– Allows longer ranges to be obtained
l Available in 900MHz and 2.4GHz
l Wide range of RF data rates
– 9600 to 1Mbps+
l Frequency synchronization needed
– Increases time nodes must be awake
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Proprietary
l Wide variety of solutions available
– Increases the likelihood of finding a solution that is closer fit to your application
l Battery life very dependent on reporting duty cycle
– Radio is off when not transmitting instead of low power sleep mode
– Sleep modes are supported in many products but typically in excess of 10uA
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Proprietary
Cost -
Power Consumption Fair
Deployment Ease -
Network Size Good
Security Good
Range Good
Robustness Good
Confidential & Proprietary RF Monolithics, Inc.
Conclusions
Cost Good Good Good Good Good Fair Good Good -
Power Consumption Fair Good Good Good Good Good Good Good Fair
Deployment Ease Good Good Good Good Good Good Good Good -
Network Size Poor Good Fair Fair Good Good Fair Fair Good
Security Good Good Good Good Good Good Good Fair Good
Range Fair Good Good* Fair Good Good Good* Good* Good
Robustness Good Fair Fair Fair Fair Good Poor Poor Good
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* Range extended through the use of mains powered routers/repeaters
Confidential & Proprietary RF Monolithics, Inc.
Conclusions
l Each technology has its own strengths and weaknesses
– Specific application requirements must be measured against each technology
l One size does not fit all
– Depending on the application, one technology will emerge as the best solution
– Market acceptance of technologies can be a guide to technology selection
l Do not attempt to force fit a technology to an application
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Thank You!
Questions?