Research On Rate Control And Channel-Switching In Multi-channel Wireless Ad Hoc Networks

The connatural characteristics, such as self-organizing, self-setup, dynamic topology and multi-hop routing, makes wireless ad hoc network have an expansive forefront in the field of military and civil applications. With the rapid popularization of wireless communication devices, wireless channel becomes a type of increasingly rare nature resource. Thus, the combination of wireless ad hoc network and multi-channel technology has gain more and more attention from academy and industry. Combined with multi-channel technology, wireless ad hoc network can do well in the environment of dynamic wireless channels and dynamic network topology, thus it can improve wireless channel utilization and efficiency of communication. As an important type of next generation network, quality of service, energy-efficient design and multi-channel access are the most basic problems. This thesis carries a deep study on new techniques of wireless ad hoc networks and puts emphasis on multi-channel rate control and multi-channel switching.First of all, the problem of node power-constrained multi-channel link rate control is presented. The signal-to-interference in one channel and node's power limit are comprised in the model. By using network utility maximization method, the problem of power-constrained multi-channel link rate control is formulated as a utility problem and then is separated into two sub-problems, one is power control in physical layer and the other is link rate control in link layer. By solving the problem, we get a distributed algorithm, which can get a global convergence for network.Secondly, this thesis proposed a model of end-to-end delay-constrained data transmission rate control for multi-channel wireless ad hoc network. The idea of network utility maximization is proposed to force cooperation between nodes, and the design of multi-channel wireless ad hoc network is formulated as a nonlinear optimization problem. By using dual decomposition method, the primal nonlinear problem is separated into several sub-problems, and then derived a price-based distributed algorithm. The algorithm optimizes the data rate on all the channels of each data source node and the delay on all the channel of each link.Third, the problem of multi-channel switching in multi-channel wireless ad hoc networks is analyzed. A simple and general channel switching scheme by extending the IEEE 802.11 MAC to a multi-channel MAC is proposed, and then a three-dimensional Markov chain model is provided to analyze the performance of the channel switching MAC and evaluate the effect of two major parameters, namely the number of retransmission on one channel and the number of switching channels. The analytical model supports both access methods: basic and RTS/CTS. The simulation results show that the model can predict the saturation throughput of the system, and the performance is improved with the increasing number of retransmission, but is not always with the increasing number of switching channel.The work in this thesis has been supported by the National Science Foundation of China "Information Processing and Transmission on Reconstructible MIMO-based Wireless Sensor Networks" (No.60572049), "Research on Key Issues on Cognitive Radio Networks" (No.60602029), "Research on Wireless Sensor Networks based on Network Utility Maximization" (No.60772088) and the Foundation of Hubei Provincial Key Laboratory of Smart Internet Technology under Grant No.HSIT200605 respectively.