| Mobile ad hoc networks (MANETs) are self-organizing, infrastructureless networks that provide flexibility and convenience in setting up a dynamic network. Since the 1970's, MANETs have attracted a great deal of research aimed at improving their basic performance. However, with the development of real-time applications, incorporating Quality of Service (QoS) into the network architecture becomes essential.; My thesis is that supporting QoS in MANETs necessitates more harmonious collaboration among network layers, requiring a design that supports cross-layer interactions rather than a traditional independent layered network architecture. The work described in this dissertation enables this goal by proposing a general architecture that supports cross-layer interactions, as well as by designing protocols at several layers of the stack that can exploit this cross-layer information to improve the QoS performance.; Specifically, we begin by developing a QoS architecture for cross-layer information sharing, defining explicitly what information must be shared among the layers to provide support for QoS in terms of bandwidth and packet delivery rate. Using this architecture, we develop protocols for the transport, network and MAC layers that can improve QoS performance. At the transport layer, we develop a User Data Protocol (UDP) with Congestion Control (UDPC), in which network status is monitored using feedback sent by destination hosts, and this status is passed to real-time applications to adjust their transmission coding rate. This approach avoids wasting capacity and energy on data packets that cannot eventually be transmitted to the destination. In order to support QoS in the routing layer, we propose a bandwidth estimation based QoS-aware routing protocol with admission and adaptation schemes, which considerably improves packet delivery ratio, decreases transmission latency, and reduces energy consumption without impacting overall throughput. Finally, we investigate current distributed MAC protocols and develop a dual-channel MAC (DMAC) protocol to improve QoS at the MAC layer. We present the design considerations and show that using DMAC improves fairness. Using these different techniques that exploit cross-layer information sharing greatly improves QoS for mobile ad hoc networks. |
