Sensor Network with Mobile Access: An Experimental Testbed Adaptive Communications and Signal Processing Group School of Electrical & Computer Engineering Cornell University Ithaca, NY 14853

Sensor Network with Mobile Access Minimal Low Power Sensors –Sensing, storing, delivering –Local sensor communications –Opportunistic multiaccess to mobile access points Powerful Mobile Access Points –Data collection and transport –Network management

Opportunistic ALOHA Sensor Networks –Random deployment –Large number of nodes –Limited battery => mobile AP –AP-initiated uplink => Probabilistic TX, Probabilistic TX, Use of channel state Use of channel state => Opportunistic ALOHA => Opportunistic ALOHA

Acoustic SENMA Testbed Feasibility in Real Environment –Verification of the SENMA architecture –Manageable dimension –Preliminary step to full RF system Performance Evaluation –MAC protocol: ALOHA vs. Opportunistic-ALOHA –Target detection

System Configuration

Indoor Acoustic Characteristics Free field (< 5 ft) & inverse square law Free field (< 5 ft) & inverse square law Reverberant field: reflection, diffusion, diffraction Reverberant field: reflection, diffusion, diffraction Sound absorbing treatment Sound absorbing treatment

Opportunistic Multiaccess Synchronization/Channel Estimation Synchronization/Channel Estimation Opportunistic Uplink Transmission Opportunistic Uplink Transmission

Required Functions

Sensor Block Diagram State Machine Sound Sensing Power (Ext., Battery) NCO Beacon Detector RSSI TX AnalogRX Analog Uplink Access Protocol ALTERA PLD DAC EPROM MIC

O-ALOHA Implementation EPROM (Threshold Table) Random Number Generator - + Beacon Signal All rights reserved. ACSP TX Decision Quant- izer RSSIAddress

Mobile Access Point MATLABTCP client WLAN AP TCP server Control INTERNET O- ALOHA

Mobile Access Control Panel

Demo Clip 1 Target trajectory finding 1.Data collection with no target 2.Appearance of target 3.Detection by sensors 4.New data collection

Related Research Issues Fundamental Research –Scalability of large scale random sensor networks –Energy constrained sensor communications and networking –Detection, estimation, imaging in large random sampled sensor field –Energy constrained sensors, devices, and computing. Potential Applications –Monitoring: water, air, forest, home, etc. –National security: explosive/narcotic detection border control border control