Wireless Mesh Networks: Analysis and Future Projects Stephanie Liese Daniel Wu Prasant Mohapatra

Agenda Experimental Characterization of a Wireless Mesh Network Quail Ridge Reserve Wireless Mesh Network

Experimental Characterization of an b Wireless Mesh Network

Why Mesh Networks? Wireless Community Networks Provider Coverage Extension Enterprise Networking Building/Home Automation © Adobe Cinema & Automation © MIT Roofnet

Motivation for Experiment Need for accurate physical characterization of mesh environment Lack of mesh testbeds without background traffic and interference Account for physical layer issues not addressed in simulation Need for topological trade-off assessment: radios per node, hops, channel assignment, communication flows, antenna proximity

Experimental Setup IEEE b ORiNOCO AP-2000 ORiNOCO Classic Gold PC Cards 8 Laptops running Fedora Core 3 Wireless Distribution System running between access points Experiments performed in an interference free environment Goodput calculated with the average of five 20 second TCP bulk data transfers from end to end

Experimental Setup 4 Access Points in a linear topology Multi-Channel, Multi- Hop Tests 5 dBi gain antennas elevated 4 ft and separated 4 ft 100 ft between APs

Experiments 1 Channel Assignment and Resource Contention Two Cards Multiple Channels (TCMC) Two Cards One Channels (TCOC) One Card One Channel (OCOC)

Results 1

Experiments 2 Effect of Multiple Communication Flows 1 Flow 2 Flows 3 Flows

Results 2

Experiments 3 Effect of WDS Path on Performance Two Cards Two Channels (TCTC)

Results 3

Experiments 4 Parking Lot Scenario (Gambiroza et al.) Two Cards Multiple Channels (TCMC) One Card One Channel (OCOC)

Results 4

Experiments 5 Effect of RTS/CTS –TCMC with RTS/CTS on for all nodes and APs Antenna Proximity –Horizontal difference between adjacent antennas varied between 0-4ft

Results 5

Inferences Use Multiple non-overlapping channels whenever possible Aggregate goodput remains roughly the same even when number of users increase RTS/CTS decreases the goodput and increases RTT of the network Multiple hops need to use multiple channels

Inferences Limit the number of hops needed for each flow in the wireless network Antenna placement is very very important Round Trip Time (RTT) generally decreases when using multiple channels

Quail Ridge Reserve Wireless Mesh Network

Objective Help out the ecological studies within Quail Ridge Design new MAC protocols over for long haul links Create a testbed for running experiments

Topology Rough terrain Varied elevation Overgrowth of trees and vegetation Varied weather conditions Long link distances Lack of onsite power (solar)

Network 10 – 15 Access Point sites Sensor Networks at various locations Need QoS for multimedia streaming T1 link at base Field Station Directional bottleneck link from T1 to Mesh Network Directional/Omni Antennas used

Hardware Soekris net4826 –2 miniPCI slots –64 MB of Flash Memory –128 MB of RAM –266 MHZ AMD Geode SC1100 Wireless Cards –400mW Atheros b/g cards

Current Testing First link between Field Station and Fish and Game Hill (1.2 miles) gets 22Mbps consistently (directional to directional antenna) Omni to directional antenna gets 6 Mbps

Future Work Software customization for differing applications Tool development for Wireless Mesh maintenance and monitoring Deploy more access points to cover the whole quail ridge