Harmonic channel access in wireless adhoc networks

The motivation of our work is to develop medium access control (MAC) protocols that address and solve issues specific to wireless ad hoc networks and provide a framework that integrates routing protocols with the underlying MAC schemes with the ultimate goal of increasing the feasibility of wireless networks. Our initial works on MAC protocols attempt a paradigm shift from schemes that are derivatives of wired networks taking into account the multifarious challenges in a wireless ad-hoc network. This is followed by a complete framework taking the higher layers of the protocol stack into account with a focus on the ability of the networks to support different application traffic. Specifically, in this dissertation, we present our novel approaches to media access scheduling and routing in wireless ad-hoc networks based on node ID, connectivity and GPS coordinates. Transmitting packets successfully over a network involves dynamically building fair and reliable transmission schedules at the nodes and building routes for the packets to traverse to the destination. The MAC schedules constructed using node identifiers in traditional networks lead to long neighbor discovery and convergence times. MAC protocols that do not use scheduling lead to coupon collector's problem and long end-to-end delays for QoS sensitive applications. The traditional node identifiers used in Routing protocols lead to flooding in the network for route maintenance and are independent of the scheduling decisions at the MAC layer. Our approach to establish schedules and routes emphasizes on the efficient use of different types of virtual coordinates. The schedules thus created are harmonic, in that the nodes get to access the medium at deterministic intervals depending on the neighborhood size of the particular node. We propose to apply this concept of virtual coordinates to address the issues of flooding, coupon-collector's problem and fairness that is faced by networks that use traditional node identifiers for MAC and routing.;The first part of the research consists of different MAC protocols that were developed for harmonic distributed scheduling. Each of the MAC protocols achieves this scheduling by using unique node identifiers, GPS coordinates or virtual coordinates based on connectivity. The second part of the research presents a cross-layer framework for effective dissemination of both real-time and elastic traffic that can provide end-to-end application delay guarantees. It consists of a flow-based queueing and traffic management system that coordinates with the scheduling protocol to guarantee channel allocations in response to application requirements. (Abstract shortened by UMI.).