Communication for the Wearable Platform
Jan BeutelComputer Engineering and Networks Lab
Swiss Federal Institute of Technology (ETH) Zurich
October 19, 2001
Computer EngineeringComputer Engineeringand Networks Laboratoryand Networks Laboratory
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Zuric
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Jan Beutel, October 19, 2001Jan Beutel, October 19, 2001
The Wearable Perspective
displaycontext sensor array: camera, light, microphone, GPS
distributed reconfigurable computer
body area network:wireless
communication:WLAN, GSM,
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Zuric
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Jan Beutel, October 19, 2001Jan Beutel, October 19, 2001
The WearArm Platform• Standard Bus Architecture based on
commercially available Chipsets many different Interfaces
• Wired Connections parallel buses, concurrent operation, available at all times, no degradation, no loss
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Jan Beutel, October 19, 2001Jan Beutel, October 19, 2001
What is Communicating on a Wearable?
• Communicating Components of a single Wearable Computer System
– Processor Bus CPU, Memory, Storage, UI, NIC…
– Peripheral Interconnect UI, Audio, Sensors, Actors…
– NetworkingTo the Access Network
To other Persons/Wearables
To Multiple Wearable Computer Systems per Person?
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Jan Beutel, October 19, 2001Jan Beutel, October 19, 2001
The Wearable Difference• Distributed (Re-)(Configurable) Computing
Platform
– Heterogeneous Components– Many Components (~10…20)– Varying Configurations of Components
– Distributed over whole Body, unreliable– Distributed Power Sources
– Dynamic Environment
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Jan Beutel, October 19, 2001Jan Beutel, October 19, 2001
Communication Tradeoff
CPU
Sensor
NIC
UI/VGA
MemorySensor
Actor
Sensor
DSP
UI ?
Goal: To Find the best Medium for each required
Interaction
??
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Zuric
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Jan Beutel, October 19, 2001Jan Beutel, October 19, 2001
The Wireless Difference• Shared Medium• Degradation on Use• Errors depending on Environment
Ad-Hoc Networking Advantages:• Simple Deployment• Adaptive to Heterogeneous Environment• On Demand Availability• Distributed Resources
Low Power/Cost Flexibility
Performance
Tradeoff
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Jan Beutel, October 19, 2001Jan Beutel, October 19, 2001
Network Protocol Services• Finding Network
Nodes• Service Discovery
• Setting up Connections
• Sending Data
• Maintaining Connections
• Maintaining Routes• Positioning
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Jan Beutel, October 19, 2001Jan Beutel, October 19, 2001
Component RequirementsDevice Datarate Access-
RateAsync/Sync
BER/PER
Uni/Bidi-rectional
Routing/Bridging
Multi-Access
Display textDisplay HiRes1280x1024x16k
<=100Bit/sec>>1Mbit/sec
Async/Sync
10-5/10-5
10-2/10-5
No No??
Mouse Very Low Regular, Bytewise
Sync 10-2/10-5 No
Memory Very High 0/0 No YesDisk High Burst 0/0 ?Coprocessor Medium to
Very HighOn-Demand
0/0 Yes
Network IF High 0/0 Yes ?Network Connection
Medium Asnyc 10-5/10-2 Yes ?
Audio/Video
Medium/High
Stream,On-Demand
Sync 10-2/10-2 Yes
…
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Zuric
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Jan Beutel, October 19, 2001Jan Beutel, October 19, 2001
First Generation Network Node
Communication via Bluetooth Transceiver
Generic Sensor InterfaceGPIO, I2C
UART Data Interface
Microprocessor and Memory Powermanagem
ent
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Jan Beutel, October 19, 2001Jan Beutel, October 19, 2001
Bluetooth Module
State Machine Programming Model• Modular State Machine
Model• Low Level Drivers
– 2 Serial Ports, ADC, Random Number Generator, System Clock, GPIO, I2C
• Simple Event Driven Scheduler with Callback Functions
• Stripped down Bluetooth Stack (HCI, L2CAP)
• ~50k Code
Bluetooth Module
Bluetooth Module
Microcontroller
Connect
Button Event
I2C Event
Protocol Event
Scheduler
Comm
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Zuric
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Jan Beutel, October 19, 2001Jan Beutel, October 19, 2001
The Wearable Potential
BT
WearArmBT
SensorBT
SensorBT
KeyboardBT
WearArmBT
SensorBT
SensorBT
BT
• Ad-Hoc Networking Prototype• Distributed Positioning Service
Needed are:• Detailed Interface Specification• Prototype Hard/Software Environment• Higher Application Layer API• Usage Scenario for Wearable System
BT