Design Trade offs in Wireless Sensor Network System Development Lakshmi Venkatraman Robert Bosch Corporation Research and Technology Center Palo Alto CA Lakshmi Venkatraman rtc bosch com Jan 04 Robert Bosch GmbH reserves all rights even in the event of industrial property rights We reserve all rights of disposal such as copying and passing on to third parties 1 RTC Overview Introduction System Design Constraints Sensor Node Architecture Protocol Design Issues Summary Jan 04 Robert Bosch GmbH reserves all rights even in the event of industrial property rights We reserve all rights of disposal such as copying and passing on to third parties 2 RTC Overview Introduction System Design Constraints Sensor Node Architecture Protocol Design Issues Summary Jan 04 Robert Bosch GmbH reserves all rights even in the event of industrial property rights We reserve all rights of disposal such as copying and passing on to third parties 3 RTC Sensor Network Applications Building Automation HVAC Control Lighting Control Access Control Refrigeration Control Industrial Automation Temperature Sensing and Control Pressure Sensing Level Sensing Machinery Monitoring Power and Utility Automation Remote reading of Residential Meters Power Distribution Diagnostics Jan 04 Robert Bosch GmbH reserves all rights even in the event of industrial property rights We reserve all rights of disposal such as copying and passing on to third parties 4 RTC Sensor Network Applications 2 Environmental Monitoring Air quality water quality and seismic activity Helps maintaining the integrity and safety of buildings industrial facilities roadways water supplies utilities and other public infrastructure Tele Health Monitoring and Diagnostics Significantly reduce overall medical costs by enabling homebased proactive monitoring and medical care Create personalized patient based monitoring techniques heart rate respiration etc Jan 04 Robert Bosch GmbH reserves all rights even in the event of industrial property rights We reserve all rights of disposal such as copying and passing on to third parties 5 RTC Why is Bosch interested Several wire based sensor actuator network products in Building automation Industrial automation Security systems Automotive All share the disadvantages to be Expensive to install Inflexible once installed Limited in size complexity and functionality Obtrusive in existing infrastructure BUT a wireless channel clearly creates challenges in terms of Reliability Security Bandwidth Jan 04 Robert Bosch GmbH reserves all rights even in the event of industrial property rights We reserve all rights of disposal such as copying and passing on to third parties 6 RTC Wireless Sensor Network Advantages What factors outweigh these challenges New functions Wireless data collection Collective operation of simple sensors for complex tasks Scalability Multi hop networks 10 1000s of devices Robustness Ad hoc Network Self Reconfiguration Distributed Intelligence Profitability Low installation cost Flexibility New market opportunities Jan 04 Robert Bosch GmbH reserves all rights even in the event of industrial property rights We reserve all rights of disposal such as copying and passing on to third parties 7 RTC Application Scenarios Building Control Networks Tens to thousands of nodes Many device types sensors actuators Low effective data rate Regular low priority data Thermo technology Climate control systems Tens to hundreds of nodes Frequent communication of non critical data Security Systems Tens up to several thousand nodes Asynchronous high priority data Periodic low priority data Safety critical products Jan 04 Robert Bosch GmbH reserves all rights even in the event of industrial property rights We reserve all rights of disposal such as copying and passing on to third parties 8 RTC Overview Introduction System Design Constraints Sensor Node Architecture Protocol Design Issues Summary Jan 04 Robert Bosch GmbH reserves all rights even in the event of industrial property rights We reserve all rights of disposal such as copying and passing on to third parties 9 RTC Sensor Network System Nodes Application specific sensors Few tens to thousands small low cost smart Low power 2x AA Static nodes Base station Control of network Data aggregation and interpretation Network protocol Ad hoc multi hop operation Self organizing self healing Scalable network Interfaces to other networks Jan 04 Robert Bosch GmbH reserves all rights even in the event of industrial property rights We reserve all rights of disposal such as copying and passing on to third parties 10 RTC System Design Constraints 1 System Cost No redundant nodes Low cost microcontroller low available memory Expensive labor Infrequent maintenance requirements Limited technical expertise of installers no configuration tools Marketing Issues Ease of use user friendly functioning Low latency for control commands from user System for global market Secure communication Network life longevity Additional appealing features Jan 04 Robert Bosch GmbH reserves all rights even in the event of industrial property rights We reserve all rights of disposal such as copying and passing on to third parties 11 RTC System Design Constraints 2 Application specific requirements Latency requirements for high priority data Periodic monitoring of nodes Detection of channel jamming Government regulations on frequency usage Limited output power Depending on frequency band limitations on output power Transmitter field strength is restricted to 1dBm when spread spectrum is not used FCC 15 249 Duty cycle restrictions Limited channel width Few available channels Jan 04 Robert Bosch GmbH reserves all rights even in the event of industrial property rights We reserve all rights of disposal such as copying and passing on to third parties 12 RTC Design Challenges Latency vs Low Power Power limitation Sleep as much as possible Low latency requirements Wakeup frequently Frequent low priority data vs Low Power Frequent low priority data Communication overhead Power limitation Low communication overhead Ad hoc reconfigurable vs Low Power memory Ad hoc reconfigurable Complex algorithms high communication overhead Power limitation Low communication overhead Jan 04 Robert Bosch GmbH reserves all rights even in the event of industrial property rights We reserve all rights of disposal such as copying and passing on to third parties 13 RTC Overview Introduction System Design Constraints Sensor Node Architecture Protocol