1. Wearable Communication Part 2 Jan Beutel, Thomas von Büren, Holger Junker, Matthias Stäger Computer Engineering and Networks Lab - Electronics Lab May 3, 2002 Computer Engineering and Networks Laboratory

2. 2 ETH Zurich May 3, 2002 The Wearable Perspective display context sensor array: camera, light, microphone, GPS distributed reconfigurable computer body area network: wireless communication: WLAN, GSM,

3. 3 ETH Zurich May 3, 2002 Wireless Access Systems Why Wireless: Mobility Target: IP Connectivity, Compatibility Multi Rate/Multi System Mobile Wireless Access –UMTS –GPRS –IEEE 802.11a and IEEE 802.11b –Bluetooth Frontends are self-contained subsystems that are operated by commands from a host system Status of our work: Each system operational on IpaQ 3870, joint operation will be available in June

4. 4 ETH Zurich May 3, 2002 Overlay Access Networking Area Scenario RangeSystemBandwidthResource s Global1000 kmUMTS Satellite+ + + WAN20 kmGPRS/EDGE/…473.6 kbit/sec+ Campus500 mIEEE 802.111 Mbit/sec+ Building100 mIEEE 802.b11 Mbit/sec+ + + Floor12 mIEEE 802.a54 Mbit/sec+ + Room10 mBluetooth768 kbit/sec+ / - PAN1 m Sensor10 cmRFID/Passivebits/sec- - -

5. 5 ETH Zurich May 3, 2002 Low Duty Cycle Concurrent Operation Host System running Linux OS Communication Frontend B Communication Frontend A BAN Communication Frontend C Cost/Perf TableCommand Mapping All Interfaces disabled Application requesting Data Transfer at Host System Evaluation of optimal cost/performance Init of selected Interface; Channel setup Data Transfer Shutdown of selected Interface Update of Cost/Performance Table

6. 6 ETH Zurich May 3, 2002 Benefits Operation in best performance mode Scalable from 2.4 kbit/sec to n  54 Mbit/sec Quasi seamless handover Reduction of the ON/TX duty cycles –Best energy performance for non power optimized systems –Operation adaptive to the applications –Optimal usage of the available TX channel –Accounting for burstiness of data transfers Use of common protocols and applications Example: TX of 1 Mbyte data with ACK from 10 kbit/sec data source 1.Constant transmitting of data 1 sec init  71 mW + 2 sec setup  162 mW + 800 sec  151 mW = 121195 mWsec 2.768 kbit/sec Bursts 10  1 sec init  71 mW + 10  2 sec setup  162 mW + 10  1 sec  151 mW = 5460 mWsec

7. 7 ETH Zurich May 3, 2002 Local Ad-Hoc Networking Why Wireless: Easy Configuration, Scalability Target: Better Utilization of Resources, Flexible Usage Very short range (sub meter) Medium range (meter) Status of our work: Prototype on Bluetooth will be used to test setups/configurations but will not be optimal in terms of energy consumption, size, setup latency. First Motion Sensor Network based on I2C and serial communication in test phase. Todo: Research in low power, very short range data communication

8. 8 ETH Zurich May 3, 2002 Topology Issues Star topology does not work –Too many frontends –Asymmetric communication demands –Not everything will need central coordination Fully distributed does not work –Coordination too difficult Idea: Hierarchical Subsystems with sub-controllers –Linking Units geographically and logically –Outsourcing processing tasks Host System Sub System Leg Motion Sensors Head Up Display Audio System

9. 9 ETH Zurich May 3, 2002 Demo Application 1: Audio Recording Wired transmission from microphone to codec Audio preprocessing with codec logic Reduction to 10 kbit/sec Buffering to allow burst transfers Wireless transmit with 10 packets of 64 kbits each every 65 seconds Temporary storage of audio data in cache file system on mobile device Move to fileserver storage if not accessed on mobile device wireless link reconfigurable logic, inside watch wired microphone, attached to watch main computing unit, in jacket

10. 10 ETH Zurich May 3, 2002 Demo Application 2: Motion Sensor (hj) Use multiple motion sensors for context awareness Idea: Many sensors reveal „more context“  Architecture required to combine those sensors.  Hierarchical approach makes sense  Information content of sensors is weighted differently  Reduce overall data load (minimize bandwidth requirements) ... Map hierarchical topology to human body

11. 11 ETH Zurich May 3, 2002 Current Development: BTnode rev2 8-Bit RISC CPU, 1 MIPS/MHz @ 3.6 (or 5.2) MHz 128 k Flash, 68 k SRAM IO, Timer, Analog, UART, I2C Idle @3.6 MHz, 3.3V 6 mW Active @3.6 MHz, 3.3V15 mW Will be used as subsystem controller Status: Testing of the design now SW Kit/Drivers and Volume production in June 61 mm 40 mm

12. 12 ETH Zurich May 3, 2002 Parameters Influencing Communication Please identify the parameters important for you component/application until mid May: –Radio Range –Frequency –Modulation –Cell Capacity –Raw Bandwidth –Data Types –Power Consumption –Duty Cycle –Setup Times –Latency –Burst Behavior –Quality of Service Guarantees