UBC Theses and Dissertations
Mitigating the effect of propagation impairments on higher layer protocols and algorithms in wireless sensor networks Abouzar , Pooyan
Wireless sensor networks (WSNs) range from body area networks (BANs) that involve a relatively small number of nodes, short paths and frequent update rates to precision agriculture wireless sensor networks (PAWSNs) that involve a relatively large number of nodes, long paths and infrequent update rates. They are distinguished from wireless access networks by: 1) their mesh architecture and reliance on higher layer protocols and algorithms to perform routing, scheduling, localization, and node placement, 2) their need to operate for long periods of time with only limited access to battery or scavenged power. Energy conservation has long been an important goal for developers of WSNs and the potential for reducing energy consumption in such networks by reducing the strength and/or frequency of transmission has long been recognized. Although the impact of propagation impairments on the physical and media access control layers of WSNs has long been considered, few previous studies have sought to assess their impact on higher layer protocols and algorithms and devise schemes for mitigating or accounting for such impacts. Here, we present four case studies that demonstrate how higher layer protocols and algorithms can be devised to achieve greater energy efficiency by accounting for the nature of the propagation impairments experienced. In the first two case studies, we focus on BANs and: 1) propose a routing protocol that uses linear programming techniques to ensure that all nodes expend energy at a similar rate and thereby maximize network lifetime and 2) propose a scheduling algorithm that accounts for the periodic shadowing observed over many BAN links and thereby reduce the transmit power required to transfer information and thereby maximize network lifetime. In the second two case studies, we focus on PAWSNs and 3) propose an efficient localization algorithm based on the Bayesian model for information aggregation and 4) demonstrate that path loss directionality observed in sites such as high density apple orchards greatly affects WSN connectivity and, therefore, energy consumption and must be considered when designing node placement in agricultural fields.
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