wireless communication on wearable systems coreco i, wems ii + iii jan beutel, computer engineering...
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Wireless Communication Wireless Communication
on Wearable Systemson Wearable SystemsCORECO I, WEMS II + IIICORECO I, WEMS II + III
Jan Beutel, Computer Engineering and Networks Lab
Mathias Stäger, Holger Junker, Electronics Lab
December 4, 2002
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The Body Area Networking DifferenceThe Body Area Networking Difference
• Distributed Configurable Computing Platform
– heterogeneous components
– communication centric
– low power
– varying configurations and requirements
– many components (~20…50)
Display
Context Sensor Array Camera, light,
microphone, GPS
Distributed Reconfigurable
Computer
Body Area NetworkWired and wireless
Access Networking Bluetooth, WLAN
variants, GSM,UMTS, Thuraya
Sensors
Interaction with ubiquitous appliances
Audio
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CompetitorsCompetitors
• Wearable Systems– single garment, wired-up solutions
MIThril (DeVaul)– custom box-type computer (Starner)
• Sensor Networks– low bit-rate SOC transceivers (Rabaey)– COTS sensor networks (Pister et al)
• Power Management– dynamic power saving states
(De Micheli, Gupta)– low power frontends (Enz, Meng)
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Our Research IssuesOur Research Issues
• Scalable low power networking on Wearable Systems
– optimal use of resources
– low power body area networking transceivers
– fast prototyping for the implementation of real life scenarios
• Design parameters from the network view– network topology– spatial capacity– link data rates– latency/burstiness– transceiver architectures– protocol features
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Investigation of Standard ConceptsInvestigation of Standard Concepts
• Why standardized wireless devices?– operational components available today for prototypes– foundation of methodical approach to distributed systems
• Goals– knowledge to select the right hard/software architectures– optimal duty cycle performance dependant on the application– future replacement by custom components
• Our contribution– characterization and benchmarking of existing wireless communication
devices, protocols and transmission schemes – results are used in the modeling of communication channels for Design
Space Exploration of Wearable Systems [Anliker et al, submitted to TOC]– implementation of a Bluetooth protocol stack on Linux and uC
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Communication ModelCommunication Model
• The Problem optimal device configuration for each linkPower Consumption and Delay
• Assumptions– multiple periodic inputs– deadline associated to data– four operating states: standby, idle, transmit, receive
continuousduty cycle 1
burstduty cycle 2/3
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BTnodes – Bluetooth Smart NodesBTnodes – Bluetooth Smart Nodes
• Programmable networking node for
fast prototyping
– 8-Bit RISC CPU, (max. 8 MIPS @ 8 MHz)– 128 k Flash, 64 k SRAM, 4k EEPROM– generic sensor interfaces– power and frequency management– Bluetooth with integrated antenna
– idle @7.3 MHz, 3.3V <0.5 mW– active @7.3 MHz, 3.3V 150 mW
• Status– initial sw kit, drivers and demo
applications available– current deployment ~ 200 (12
research groups worldwide)– [Beutel et al, submitted to MobiSys]
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Integrated Network Protocols using Integrated Network Protocols using BTnodesBTnodes
• Bluetooth Multihop Prototype– integrated scalable application
protocol– based on Dynamic Source
Routing (CMU)– routing across piconet borders
to support >8 nodes
• Status– first implementation on
BTnodes available
– integration with the Physical Activity Detection Network PADnet (Demo)
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Comparison Transceiver ArchitecturesComparison Transceiver Architectures
• Goal– dedicated architecture for on-body sensor network
– short distance (50 cm)– low bit rate (0.1 ~ 1 kbit/s)
– low power consumption (100 W targeted)
• Comparison of– traditional far field architectures– near field systems
– magnetic induction– capacitive coupling
– ultra wideband architecture
• UWB as promising new candidate– simplicity of implementation– relatively new research field
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The Road so FarThe Road so Far
• Interfacing within the Polyproject – modeling of communication systems
► Design Space Exploration CORECO IV– BTnode
► user activity network and reconfigurable computing CORECO I + IV
• In two years…– a refined communication model
– on-line tradeoff and application of different interface types
– UWB channel characterized and suitable architecture implemented
– integration into the demonstrator platform