| Wireless ad hoc network is a self-organized and easily-deployed wireless network, which has no fixed infrastructure. In a wireless ad hoc network, each terminal node acts as both router and host, and end-to-end communications rely on cooperations between the nodes and generally go through multiple hops. Wireless ad hoc networks are characterized by bandwidth-constraned, energy-constrained, variable quality of links and dynamic topologies. Therefore, how to improve the utilization of bandwidth and energy resources, while ensuring the reliability of data transmission, is an important issue in wireless ad hoc networks.Using network coding technique, intermediate nodes no longer directly forward packets, but process the incoming packets before forwarding them. Many studies have shown that network coding can not only improve network throughput of wireless ad hoc networks, but also bring some other benefits, such as energy efficiency and transmission reliability enhancement. In this dissertation, we investiage the interaction of network coding technique and three important resource management schemes:power control, routing and rate adaptation. The main inventive works and contributions of this dissertation are listed as follows:1) Utility-based Unicast Routing Joint with Network Coding and Power ControlEnergy saving and high delivery reliability are two essential metrics in wireless ad hoc networks. In this dessertation, we propose a joint power control and network coding (PCNC) scheme which regulates the transmission power to reduce the overall energy usage and uses network coding to improve reliability by reducing the number of packet retransmissions. To evaluate the performance of PCNC, we adopt expected utility as a single metric, which integrates power cost, reliability and benefit value (reflecting the trade-off between power cost and reliability). Based on the utility metric, we first derive the utility calculation model for a unicast path, and then propose a utility maximization PCNC scheme and a utility optimization unicast routing algorithm based on PCNC. Results from simulations demonstrate that our proposed schemes improve the performance in terms of expected utility compared with existing techniques.2) Utility-based Multicast Routing Joint with Network Coding and Power ControlSince multicast is also frequently used in wireless ad hoc networks, this dissertation further studied the problem of multicast routing based on PCNC. Our goal is that for a given multicast request, how to build a multicast tree to maximize the reliability of data transmission, while minimizing energy consumption. Based on the expected utility metric, we first derive the utility calculation model for a multicast tree. For scenario with a given multicast tree, we propose a utility-maximization PCNC scheme. The multicast routing problem is proved to be NP-hardness and then a heuristic solution is proposed. Results from simulations demonstrate that our proposed schemes based PCNC improves the performance in terms of expected utility compared with existing techniques.3) Rate Selection Joint with Intra-and Inter-session Network CodingA recent study shows that the throughput of lossy wireless ad hoc networks can be further improved via combining intra-and intersession network coding (I2NC). The main idea of I2NC is to protect against packet loss by introducing additional redundancy via intra-session coding. However, the amount of lost packets depends on the quality of overhearing links, which are related to the transmission rates used at sender nodes. This dissertation studies the joint rate selection and I2NC problem in a wireless star network, so as to maximize the network throughput. We formulate this problem and prove it to be NP-hard. Then, we propose a heuristic approach to perform joint transmission rate selection and inter-session network coding policy. Extensive simulations showed that our proposed schemes are effective to increase network throughput. |
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