Distributed CSMA with pairwise coding

We consider distributed strategies for joint routing, scheduling, and network coding to maximize throughput in wireless networks. Network coding allows for an increase in network throughput under certain routing conditions. We previously developed a centralized control policy to jointly optimize for routing and scheduling combined with a simple network coding strategy using max-weight scheduling (MWS) [9]. In this work we focus on pairwise network coding and develop a distributed carrier sense multiple access (CSMA) policy that supports all arrival rates allowed by the network subject to the pairwise coding constraint. We extend our scheme to optimize for packet overhearing to increase the number of beneficial coding opportunities. Simulation results show that the CSMA strategy yields the same throughput as the optimal centralized policy of [9], but at the cost of increased delay. Moreover, overhearing provides up to an additional 25% increase in throughput on random topologies.United States. Dept. of Defense. Assistant Secretary of Defense for Research & EngineeringUnited States. Air Force (Air Force Contract FA8721-05-C-0002

Practical algorithms for distributed network control

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, 2013.Cataloged from PDF version of thesis.Includes bibliographical references (pages 135-138).Optimal routing and scheduling algorithms have been studied for decades, however several practical issues prevent the adoption of these network control policies on the Internet. This thesis considers two distinct topics in distributed network control: (i) maximizing throughput in wireless networks using network coding, and (ii) deploying controllable nodes in legacy networks. Network coding is a relatively new technique that allows for an increase in throughput under certain topological and routing conditions. The first part of this thesis considers jointly optimal routing, scheduling, and network coding strategies to maximize throughput in wireless networks. We introduce a simple network coding strategy and fully characterize the region of arrival rates supported. We propose a centralized dynamic control policy for routing, scheduling, and our network coding strategy, and prove this policy to be throughput optimal subject to our coding constraint. We further propose a distributed control policy based on random access that optimizes for routing, scheduling, and pairwise coding, where pairwise coding captures most of the coding opportunities on random topologies. We prove this second policy to also be throughput optimal subject to the coding constraint. Finally, we reduce the gap between theory and practice by identifying and solving several problems that may occur in system implementations of these policies. Throughput optimal policies typically require every device in the network to make dynamic routing decisions. In the second part of this thesis, we propose an overlay routing architecture such that only a subset of devices (overlay nodes) need to make dynamic routing decisions, and yet maximum throughput can still be achieved. We begin by formulating an optimization problem that searches for the minimum overlay node placement that achieves maximum throughput. We devise an efficient placement algorithm which solves this problem optimally for networks not subject to interference constraints. Then we propose a heuristic control policy for use at overlay nodes, and show by simulation that this policy performs optimally in all studied scenarios.by Nathaniel Matthew Jones.Ph. D

Wireless Network Coding: Analysis, Control Mechanisms, and Incentive Design

The access to information anywhere and anytime is becoming a necessity in our daily life. Wireless technologies are expected to provide ubiquitous access to information and to support a broad range of emerging applications, such as multimedia streaming and video conferencing. The need to support the explosive growth in wireless traffic requires new tools and techniques that maximize the spectrum efficiency, as well as minimize delays and power consumption. This dissertation aims at novel approaches for the design and analysis of efficient and reliable wireless networks. We plan to propose efficient solutions that leverage user collaboration, peer-to-peer data exchange, and the novel technique of network coding. Network coding improves the performance of wireless networks by exploiting the broadcast nature of the wireless spectrum. The new techniques, however, pose significant challenges in terms of control, scheduling, and mechanism design. The proposed research will address these challenges by developing novel network controllers, packet schedulers, and incentive mechanisms that would encourage the clients to collaborate and contribute resources to the information transfer. Our contributions can be broadly divided into three research thrusts: (1) stochastic network coding; (2) incentive mechanism design; (3) joint coding and scheduling design. In the first thrust we consider a single-relay network and propose an optimal controller for the stochastic setting as well as a universal controller for the on-line setting. We prove that there exist an optimal controller for the stochastic setting which is stationary, deterministic, and threshold type based on the queue length. For the on-line setting we present a randomized algorithm with the competitive ratio of e/(e-1). In the second thrust, we propose incentive mechanisms for both centralized and distributed settings. In the third thrust, we propose joint coding and scheduling algorithms for time-varying wireless networks. The outcomes of our research have both theoretical and practical impact. We design and validate efficient algorithms, as well as provide insights on the fundamental properties of wireless networks. We believe these results are valuable for the industry as they are instrumental for the design and analysis of future wireless and cellular networks that are more efficient and robust