| Cooperative communication is able to effectively combat multi-path fading across multiple protocol layers in wireless networks. In this technique, sets of terminals relay signals for each other to create a virtual antenna array, trading of the costs-in power, bandwidth, and complexity-for the greater benefits gained by exploiting spatial diversity in the channel. By contrast, classical network architectures only employ point-to-point transmission and thus forego these benefits.In wireless sensor networks, one of the main design challenges is to save severely constrained energy resources and obtain long system lifetime. Low cost of sensors enables us to randomly deploy a large number of sensor nodes. Thus, a potential approach to solve lifetime problem arises. Recently, cooperative routing in Wireless Sensor Networks has gained much interest due to its ability to exploit the broadcast nature of the wireless medium in designing power-efficient routing algorithms.In this dissertation, we propose a cooperation-based angle routing protocol and its corresponding MAC scheme, which makes full use of the cooperative communications. The contributions can be categorized as follows.Sensor connectivity plays a critical role in WSN, while traditional node's communication range R only considers direct transmission, and there is a lack of research on utilizing cooperation to improve R. In this dissertation, cooperative range R_C is utilized in WSN, with R_C and connectivity performance being evaluated by means of analytical techniques, in comparison with direct transmission. With cooperation, 'the communication range is twice of the sensing range' is the sufficient condition to ensure that complete coverage preservation implies connectivity among active nodes if the original network topology (consisting of all the deployed nodes) is connected. Connectivity intensity is presented as performance metric, and simulation results demonstrate that the effectiveness of cooperation. In this sense, cooperative structure is proposed, which is shown as the configuration between flat and hierarchy structure.A novel random forwarding protocol for distributed wireless sensor networks is reported here, and the protocol features the utilization of azimuth angle of the nodes involved and opportunistic selection of the relaying node via contention among neighbors. First, the protocol with precise angle information is discussed and its multi-hop performance is evaluated by means of both simulation and analysis in terms of average number of hops to the sink node. Simulation results show that it performs well especially in network connectivity. As a complement, node mobility is also introduced to evaluate multi-hop performance in real environments. Then, a simple MAC scheme to ensure that the node with the highest angular advantage will be selected as a relay is proposed, and subsequently energy and latency performances based on it are evaluated. It is showed that our protocol can effectively deliver data with half number of active neighbors required in Geographical Random Forwarding (GeRaF). Finally, a practical method is presented to estimate azimuth angle, combined with which, our forwarding protocol is shown to achieve the performance very close to the case with precise angle information.Cooperation have a great effect on WSN, such as the enlargement of communication range, the nonreciprocal link, etc., which require traditional MAC schemes changing a lot. CSMA/CA, BTMA, RTS-CTS handshake are discussed here and variations of them satisfying cooperative WSN are proposed. Finally, a novel MAC scheme for multi-hop WSN with cooperation is presented, featuring opportunistic selection of the relaying node via contention among neighbors.A cooperative angle routing protocol for multi-hop WSN is presented. It exploits the broadcast nature of the wireless channel to enable on-demand cooperative relaying and has an effect as leapfrogging among multi-hop links. The practical method is modified to acclimatize itself to WSN with cooperation.
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