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Title:Performance of wireless off-road vehicular networks
Author(s):Wilcox, Timothy A.
Advisor(s):Hansen, Alan C.
Department / Program:Engineering Administration
Discipline:Agricultural Engineering
Degree Granting Institution:University of Illinois at Urbana-Champaign
Vehicular Communication
Wireless Communications
Abstract:Advances in wireless technology and an increasing demand for new applications that require in-field communication are generating more interest in off-road vehicular networks than ever before. Current on-road and off-road vehicular networking technologies are either cost prohibitive, bandwidth limited, or exhibit too much latency. 802.11 standard networks are a low-cost, readily available technology that have the potential of integrating effectively with current off road equipment software and hardware. The main objective of this research was to develop a baseline for the performance of an 802.11b/g wireless network in a realistic in-field agricultural environment. While recognizing there are many external factors that can degrade the performance and reliability of such a system, this research was focused on identifying and measuring the performance effects of varying parameters that can be controlled, in particular the data rate, packet size, and the choice of 802.11b versus 802.11g protocols. The performance of the system was measured by recording packets at both the transmitting and receiving devices and calculating the percentage of packets received at varying distances between the nodes. A simple two node network between two tractors was constructed for performance testing, and an application was written that used personal computers on each tractor to generate and log network traffic simultaneously. A series of 18 tests were executed with varying data rates, protocols, and packet sizes in realistic in-field conditions. Data were then post-processed so that they could be easily analyzed with the aid of Microsoft ExcelTM. The 802.11b network performed much better in the outdoor environment by transmitting data more reliably and farther than the 802.11g network. 802.11g networks exhibited a high reliability region, usually at small distances between nodes, and a region with less reliability, at larger distances between nodes. Increasing 802.11g data rates decreased the distance over which the network would reliably transmit, but increasing 802.11b data rates had little effect on maximum transmission distance, although they decreased the overall reliability of the network. For packets between 15 and 1400 bytes in length, small but statistically significant decreases in reliability were observed with increasing packet size. For the largest packet size of 2200 bytes, more notable reliability decreases were observed. The network performance was influenced by the angle of the transmitted wave relative to the tractor orientation. Finally, performance degradation due to signal reflections off the soil surface could be observed at distinct distances between nodes.
Issue Date:2011-01-21
Rights Information:Copyright 2010 Timothy A. Wilcox
Date Available in IDEALS:2011-01-21
Date Deposited:2010-12

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