Tim Ireland, Adam Nyzio, Michael Zink, Jim Kurose

Department of Computer Science

University of Massachusetts Amherst

The Impact of Directional Antenna Orientation, Spacing, and Channel

Separation on Long-distance Multi-hop 802.11g Networks: A Measurement Study

WiNMee’07, April 20th 2007

Motivation

General SurveillanceRain Prediction

ComputationRain Mapping

Multiple 15 dBi directional antennas

• Motivation• Measurement Setup• Antenna Orientation• Antenna Separation• Routing vs. Non-routing• Conclusion and Outlook

Overview

Measurement Setup

Link 3

Node 1 Node 2

Wireless 802.11g link, Distance: 157 meters,

ESSID=“pair1”

Link 1

Node 3 Node 4Wireless 802.11g link, Distance: 265 meters,

ESSID=“pair2”

Link 2

2 meters distancebetween antennas

Node 4

45°

Distance: 172 meters

Node 4

90°

Distance: 197 meters

• Laptops• Proxim 802.11 b/g WLAN• 14.5 dBi Yagi antennas

• TCP-based throughput measurements (Iperf)

• 10 times 30 seconds for each setup

Antenna Orientation

• 10 Mbps increase depending on antenna orientation

• Almost full channel capacity with fully separated channels

• The answer lies in the antenna gain pattern

Antenna Separation

• 8.2 Mbps increase through 2 meters vertical separation

• Throughput increase independent from azimuthal orientation

Top view:

Side view:

Top view:

Side view:

Routing vs. Non-routing

Node 3 Node 4Node 1 Node 2

Link 1 Link 2

Node 3 Node 4Node 1 Node 2

Link 1 Link 2

Routing vs. Non-routing

Conclusions & Future Work• Orientation and separation have significant

impact on throughput• Influence of data handling at the multi-hop node• Antenna beam pattern• Max. throughput for complete channel

separation

• Impact of weather and terrain on link quality• Analysis of MAC layer traces from

measurements• Develop models based on measurement results

CDF

Retransmission Burst

F(x

)