BUILDING CYBERINFRASTRUCTURE IN DEEP WOODS AND REMOTE WATERSHEDS Gayatri Venkatesh, Kuang-Ching Wang Department of Electrical and Computer Engineering

The Intelligent River TM Pilot Sites Over Woods & Hills To campus In Woods & Ditches To campus In the Woods AT&T Data Coverage Along the River

Challenges and Objectives Wireless networking challenges – Deep woods – impedes wireless communication range – Lack of cellular coverage – Hilly terrains – absolute blockage, often over long distances – Recurring cost and limited bandwidth of cellular/satellite service Wireless networking objectives – A methodology for building wireless network infrastructure for current and future Intelligent River TM sites that provides adequate and reliable bandwidth scales to a large area physically and economically

Clemson Forest and Hunnicut Creek Explore higher bandwidth, lower cost technologies – Clemson Forest Long range Wi-Fi (fixed direction) : IEEE a & b/g Wi-Fi mesh network : IEEE b/g Zigbee sensor network : IEEE – Hunnicut Creek Long range Wi-Fi (steerable direction) : IEEE b/g Wi-Fi mesh network : IEEE b/g Zigbee sensor network : IEEE

Forest and Hunnicut Network Overview

Long Distance Transit Links To overcome long distance, forests, hills – Radio placement on high structure on both ends – High gain directional antenna and power amplifiers – Potential control parameters Radio transmit power Antenna direction Antenna gain Radio layer 2 and 3 protocol parameters

Clemson Forest Sensor Network Zigbee Long range Transit Link Sensor Cluster Data Short range Wireless Communication:  ISM 2.4 GHz operating frequency.  1 mW (+0 dBm) power output.  Up to 120m range.  Supports up to 16 simultaneous channels.

Steerable Directional Antenna Radio Potentially higher bandwidth at substantially longer distance Software controls radio to focus one direction at a time – Fidelity Comtech Phocus System (tested 15 miles line-of-sight range) – Potential use as 1) forest mesh routers and 2) long range gateways

Measurement Studies of the Links Long Range Links IPERF – Bandwidth measurement tool used for the performance studies Laptop connected to the a radio on the fire tower ran as Iperf server and the laptop connected to radio on clemson campus ran as Iperf Client. Observation: The long range line-of-sight link stayed connected for about 30° with a throughput insensitive to transmit power changes. Iperf server Iperf client Long range link: Throughput v.s. signal strength v.s. antenna direction Long range link: Signal strength v.s. transmit power Measurement setup

Measurement Studies of the Links Forest Mesh Links Two Linksys routers with manufacturer default omni-directional antennas were placed in a wooded area with roughly uniformly grown trees. It was found that the received signal strength decreased consistently with distance. Throughput remained steady for over 120 ft and had an unexpected rise afterwards before losing connectivity. Increasing transmit power did not increase the received signal strength and throughput in this environment. Forest mesh link: Throughput v.s. signal strength v.s. distance in forest

Measurement Studies of the Links Steerable Antenna Links Two Fidelity routers with phased array directional antennas were placed 525 ft a part on an empty parking lot. The antenna beam width was configured to be 35 vertical and 43 horizontal. Starting from line of sight (0), one antenna rotated away in 22.5 steps until reaching 180 (facing away from the other antenna). Throughput v.s. signal strength v.s. antenna direction The short range directional antenna link’s angular range of connection depended sensitively on transmit power. Throughput was stable when connected but dropped steeply at the edge

Future Work Clemson Forest and Hunnicut networks ready for integration – Sensor packets pushed to server successfully (server integration TBD) – Video camera to be installed in Clemson forest – Mesh routers ready for larger scale deployment Reliability and controllability are key concerns for a large scale sensing system – Further measurement studies to develop forest model for studying wireless network performance and design – Further studies on assessment and control techniques for wireless network performance and reliability – Further studies on developing large scale wireless network management techniques and software

Acknowledgements Dan Schmiedt, CCIT Chief Network Engineer Knight Cox, Clemson Forest Manager CCIT Intelligent River Project Team Clemson Public Services Activities Team Cisco Systems Inc.