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- Type of Document: M.Sc. Thesis
- Language: Farsi
- Document No: 39241 (19)
- University: Sharif University of Technology
- Department: Computer Engineering
- Advisor(s): Jahangir, Amir Hossein
- Abstract:
- Recent advancement in wireless communications, electronics, low power design and also tendency to use high performance low cost products have led to emergence of Wireless Sensor Networks (WSNs). As the main purpose of a WSN is information gathering and it’s transmission to the sink node, the main problem is to deliver information correctly with minimum energy consumption. Besides, whereas the majority of developed applications for WSNs are event-critical applications, achieving reliable data transfer as the main factor of dependability and quality of service seems vital. However, data transmission is unreliable over multi-hop WSN due to the unreliability of wireless links and node failures. Therefore main challenge and fundamental issue on sensor networks is fast and reliable data transfer. In the present dissertation, we review limitations and challenges that WSN encounter for reliable data transmission, the types of faults and errors on these networks, reliability definitions and the techniques for improving this parameter. Then we present a comprehensive survey from reliability modeling articles and reliability protocols in transport and network layers. We establish a probabilistic fundamental quantitative notion for performance-critical applications on reliable information transfer and propose a new analytical model for calculating the coverage-oriented reliability of cluster-based WSNs. Most of network properties are considered as random variables and a queuing-theory based model is derived. Simulation results are used to validate the proposed model. The simulation results agree very well with the model. Finally, we focus on designing a new general energy efficient, fault tolerant, and highly reliable routing protocol that prolongs the network lifetime; we call it SBRR (Score Based Reliable Routing). As the main objectives of this protocol are the reduction of packet loss and packet error, we select the best quality path of the network for highly reliable data transfer. The routing decision is based on a heuristic parameter derived from the model and named ‘Path Score’, which is a combination of four factors. These factors are relevant to hop count, energy level of sensors, error rate of links, and free buffer size of sensors for each path. We show analytically the reasons behind selecting these factors for each path. Simulation results reveal that the proposed algorithm yields a longer network lifetime, less packet latency, and higher delivery ratio than other existing schemes.
- Keywords:
- Wireless Sensor Network ; Reliability
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