Research On Resource Allocation And Cross-layer Technology In Mobile Ad Hoc Networks

Mobile ad hoc networks represent autonomous distributed systems that are infrastructure-less, fully distributed, and multi-hop in nature. There is considerable interest in designing and implementing such networks to provide services in a variety of diverse applications, e.g., disaster relief and temporary meetings. Recently, due to increasing popularity of multimedia applications, QoS support in mobile ad hoc networks has become an important yet challenging objective. However, due to the limited bandwidth, the conflict between the limited wireless resource and QoS requirements of multimedia service grows increasingly. How to design an effective resource allocation is the key to support QoS.The main objective of this dissertation is to develop an effective resource allocation scheme for mobile ad hoc networks under limited bandwidth conditions. It can guarantee satisfactory end-to-end QoS to multimedia applications according to certain QoS measures such as delay, bandwidth or packet loss, while achieving efficient network resource utilization. In this dissertation, resource allocation model and algorithm in mobile ad hoc network is firstly studied. Secondly, the network-layer resource allocation technique is studied. Thirdly, the MAC-layer resource allocation technique is studied. Finally, the cross-layer resource allocation with joint design of network layer and MAC layer is studied.The main research contributions of this dissertation are as follows:(1) With detailed analysis of the contest characteristics of ad hoc network's information flow, a new price-based resource allocation algorithm of mobile ad hoc network is proposed. Firstly, a resource allocation model of mobile ad hoc network is presented by converting the optimization problem to the Lagrangian dual problem. Secondly, price is introduced to measure resource allocation. Price query is done with the route discovery and price feedback is done with the route reply. It can eliminate the inconsistency of distributed prediction. Finally, long-range dependence can be converted into short-range dependence and the network traffic can be predicted with wavelet. An improved resource allocation algorithm is proposed. The simulation results show that the resource allocation algorithm has good convergence and it improves the resource utility compared to other algorithms.(2) In the network-layer resource allocation, new routing algorithms are proposed. In mobile ad hoc networks main routing metrics are hops, delay and energy etc, which lead to overload of central nodes and can cause network congestion. An on-demand routing protocol based on price awareness is proposed to deal with the problem. This protocol chooses price as routing metric and uses layered architecture. The method can obtain the same view of the whole network. The simulation results show that it improves the packet delivery fraction and reduces the average end-to-end delay and has good stability. Then, based on the analysis of the dynamic MANET on-demand (DYMO) routing protocol, a novel QoS-aware multi-path DYMO (QA-DYMO) protocol is proposed to provide QoS. QA-DYMO establishes and utilizes multiple routes of link-disjoint paths to send data packets concurrently. It can adapt to the dynamic changes of ad hoc network and support QoS better.(3) In the MAC-layer resource allocation, new backoff algorithm and analytical model are proposed. Firstly, based on the analysis of the traditional IEEE 802.11 DCF protocol, multi-priority backoff algorithm and inter-frame space are designed. A differentiated distributed coordination function (D-DCF) is proposed to support differentiated service. Then, a four-dimensional Markov chain model is proposed to modeling D-DCF. The model can effectively evaluate the network performance of saturated and non-saturated conditions. Theory and simulation results show that D-DCF performs better than 802.11 DCF considering throughput and average packet delay and it can support three kinds of priority of differentiated service.(4) With the cross-layer technique, a cross-layer resource allocation algorithm CL-QARA is proposed, which is jointly designed between network layer and MAC layer. Resource allocation schemes which are purely based on MAC layer or network layer can not meet QoS requirements of the dynamic ad hoc networks. But if the cross-layer technique is used in resource allocation, it can provide a variety of QoS applications. The key idea of CL-QARA algorithm is to introduce price and QoS bandwidth to measure resource allocation. The dynamic resource allocation information in network layer is combined with the CSMA/CA admission control in MAC layer to improve the backoff algorithm. A new backoff algorithm and call admission control algorithm is designed to implement the cross-layer technique between MAC layer and network layer. The QoS-aware resource allocation algorithm is cooperated with the cross-layer technique to provide QoS guarantee. Simulation results show that CL-QARA has good convergence and stability. Compared to other algorithms. CL-QARA provides better QoS guarantee and improves the network utility and performance.