1. A Systematic Approach to the Design of Distributed Wearable Systems Urs Anliker, Jan Beutel, Matthias Dyer, Rolf Enzler, Paul Lukowicz Computer Engineering and Networks Lab & Wearable Lab Swiss Federal Institute of Technology (ETH) Zurich September 25, 2001 Computer Engineering and Networks Laboratory

2. 2 ETH Zurich Jan Beutel, September 25, 2002 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 October 2001

3. 3 ETH Zurich Jan Beutel, September 25, 2002 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… –Networking - To the Access Network - To other Persons/Wearables - To Multiple Wearable Computer Systems per Person? October 2001

4. 4 ETH Zurich Jan Beutel, September 25, 2002 Computation Communication Tradeoff CPU Sensor NIC UI/VGA Memory Sensor Actor Sensor DSP UI ? Goal: To Find the best Resource and Medium for each required Interaction ? ? storing listening computing displaying alerting filtering sleeping October 2001

5. 5 ETH Zurich Jan Beutel, September 25, 2002 The Wearable Potential BT WearArm BT Sensor BT Sensor BT Keyboard BT WearArm BT Sensor BT Sensor BT Needed are: Detailed Interface Specification Prototype Hard/Software Environment Higher Application Layer API Usage Scenario for Wearable System BT Low Power/Cost Flexibility Performance Tradeoff October 2001

6. 6 ETH Zurich Jan Beutel, September 25, 2002 Exploration Methodology Overview

7. 7 ETH Zurich Jan Beutel, September 25, 2002 System Specification Load Specification (task profiling) –Assembly of Scenarios, Applications and Tasks Architecture Specification –System Topology (tree structure) –Module Properties (hard and soft constraints) –Connection Properties (wired or wireless) –Task Mapping Resource Specification –Computing Devices (speed, power, form factor) –Communication Channels (bandwidth, delay, power, form factor)

8. 8 ETH Zurich Jan Beutel, September 25, 2002 Load Specification

9. 9 ETH Zurich Jan Beutel, September 25, 2002 Generic System Model

10. 10 ETH Zurich Jan Beutel, September 25, 2002 Task Mappings

11. 11 ETH Zurich Jan Beutel, September 25, 2002 Communication Model Multiple periodic inputs Deadline associated with each sample Four operating states: Standby, Idle, Transmit, Receive Two modes: Continuous vs. Burst Optimal reduction of the duty cycle Result: T WC P CH P tx + P rx 2P i 2P s P tx + P rx

12. 12 ETH Zurich Jan Beutel, September 25, 2002 Results of an Exploration Pareto optimal points Communication costs strongly influence architecture Power Consumption Form Factor

13. 13 ETH Zurich Jan Beutel, September 25, 2002 DSE and Modeling Achievements Hierarchical Specification Model –Tasks, Applications and Scenario specification –Performance and resource requirements of Tasks Wearable Computing Architecture Specification –Modules consisting of individual computing resources and communication channels –Associated performance parameters Determine relevant properties of a Wearable System –Centralized vs. Distributed Exploration of the Wearable Design Space

14. 14 ETH Zurich Jan Beutel, September 25, 2002 Future Work Modelling –Improving communication model –Memory requirement and configuration –Hardware and initialization overhead –Abstract device model for different device classes and hardware normalization –Profiling further applications, verification of scenarios Exploration –Integration of new model –Dynamic binding and allocation