In this paper, a novel queueing analytical framework is proposed to evaluate the performance of IEEE 802.15.6-based carrier-sense multiple access with collision avoidance (CSMA/CA) scheduling in wireless body area net...
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In this paper, a novel queueing analytical framework is proposed to evaluate the performance of IEEE 802.15.6-based carrier-sense multiple access with collision avoidance (CSMA/CA) scheduling in wireless body area networks with joint consideration of instantaneous delay constraints and body shadowing effects. Specifically, we develop an absorbing Markov chain to model the medium access process with error controls that is defined by the IEEE standard and design a random time-limited single vacation to describe the potential body shadowing interruption process. To guarantee the timeliness of received packets and avoid energy waste for transmitting valueless packets, an instantaneous delay constraint is carefully considered, which is then characterized by an overdeadline packet dropping process with a predefined waiting deadline. In our analysis, a Markovian arrival process is also adopted to capture the correlation of arrival traffic, and all other random processes are modeled by phase-type distributions, which make our framework more general and comprehensive. To address the inherent complexity of the original model, based on the transient queueing analysis, we develop a buffer-overflowing queueing principle to approximate the overdeadline packet dropping principle by solving a buffer length optimization problem. After that, we construct a multidimensional discrete-time Markov chain to analyze the stationary distribution through the matrix-geometric method. Performance measures, including the average delay, waiting time distribution, and packet transmission failure probability, are derived. The accuracy of our proposed analyticalframework is validated by extensive simulations.
Cognitive radio (CR) technology has been considered one of the most promising solutions to make the best potential use of the scarce spectrum resources in next generation wireless communication. Because of the stringe...
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Cognitive radio (CR) technology has been considered one of the most promising solutions to make the best potential use of the scarce spectrum resources in next generation wireless communication. Because of the stringent limitations on the utilization of the radio resources in a cognitive radio network (CRN), the available resources are usually scarce and dynamic. Developing appropriate mechanism to construct allocation protocols for CRN that can assign the resources in a fair and efficient manner to diverse users with different features is essential to achieve the promise of the CR technology in reality and worth studying. "The mechanism for resource allocation protocol design in CRN" describes the topic of this research work and the contents of this thesis are organized around it. Before investigating how to design appropriate mechanism for CR resource allocation (RA) protocols, the model of the radio resource and the model of how a CR system utilizes the resource have to be clarified. In this thesis, by a comprehensive study of the relevant literatures, the modeling of critical components of a CR system and the theory behind it are identified and investigated. The existing protocols are also analyzed to address the limitations and gaps in the design of allocation protocols. An important feature, if not the most, that the allocation protocol for the CRN should possess is the ability to adjust the strategy of RA when the circumstances that affect the data transmission of the CR system varies, such as the activity of the license users or the variety of CR users' demands. According to such considerations, the mechanism, namely distribution probability matrix (DPM), is designed to guide and describe the channel allocation protocol quantitatively. To testify how this mechanism works, the protocols based on the DPM, together with reference protocols in a multichannel CRN, are analyzed by a queuing model. The numerical results shows the flexibility and adaptability that t
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