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Joshi, VineetCaching-based Multipath Routing in Mobile Ad Hoc Networks
MS, University of Cincinnati, 2009, Engineering : Computer Science
Mobile ad hoc networks represent a new approach towards computer networking which does not depend on an infrastructure for its operation. This flexibility gives rise to new applications of networks which were not possible with the networks that critically depend on an infrastructure for their operation. However this absence of infrastructure also gives rise to a host of problems with the network operation. Routing data from a source to destination is one such problem. Mobility of the nodes causes frequent topological changes and further complicates the problem. Many protocols have been proposed to help route data in mobile ad hoc networks. A sub class of these protocols makes use of a set of multipath routes to transmit data from the source to the destination. During the course of our research we discovered inefficiencies associated with these routing protocols. We have proposed the reuse of cached routes as a technique to reduce these inefficiencies and improve the performance of mobile ad hoc network along various performance parameters. We have proposed a new multipath routing protocol called CMR that makes use of the technique of reusing cached routes in determining new routes. Through extensive simulation experiments we have been able to analyze the performance of new protocol and demonstrate its advantages.

Committee:

Qing-An Zeng, PhD (Committee Chair); Raj Bhatnagar, PhD (Committee Member); Fred Annexstein, PhD (Committee Member)

Subjects:

Computer Science

Keywords:

Mobile Ad Hoc Networks; Multipath Routing

MADATHIL, DILIP KUTTYA MULTIPATH ROUTING FRAMEWORK FOR UNIFORM RESOURCE UTILIZATION WITH SERVICE DIFFERENTIATION IN WIRELESS SENSOR NETWORKS
MS, University of Cincinnati, 2003, Engineering : Computer Science
Most sensor network applications demand that the network have a long operational lifetime.This requires that energy efficient routing schemes be used while routing sensor data.In traditional routing schemes some nodes are utilized considerably more than the other nodes, which results in these energy constrained nodes becoming bottlenecks, thereby reducing the operational lifetime of the network. In this work we propose a Multipath routing protocol to avoid the creation of these bottleneck nodes. This protocol deterministically distributes the routing load on all nodes in the query region thereby creating a more stable and balanced network where all the nodes are at similar energy levels. Our simulations have shown a significant improvement in the operational lifetime of the sensor network. These networks are expected to find wide applicability and increasing deployment in coming years, as they enable reliable monitoring and analysis of the environment. Users of such a system will expect to get a real time warning when time-critical situations occur in the network and also to be able to retrieve any required information by issuing queries to the network. Our scheme classifies available paths based on their route length, so that time critical queries could be routed through low latency paths. We exploit the knowledge of the nature of queries to determine which path would be most suitable for fulfilling the application specific requirements. The routes assigned to non-critical query traffic are dynamically adapted at run time to balance the excess load generated by the critical queries along minimum delay routes.

Committee:

Dr. Dharma Agrawal (Advisor)

Subjects:

Computer Science

Keywords:

sensor networks; multipath routing; energy efficient; service differentiation; ADHOC wireless

Kaur, JasmanRealizing Connectivity with Independent Trees in DAGs - An Empirical Study
MS, University of Cincinnati, 2012, Engineering and Applied Science: Computer Science

Reliability and fault tolerance are an important part of data gathering at a base station (sink) in a wireless sensor network. Due to the uncertain environments of the network it becomes necessary to have robustness and information security integrated into the routing schemes. Multipath routing using independent trees is an eective way to achieve it. In real world applications, every node of the network does not have homogeneous connectivity to the base station. A more practical approach and a recent research area is having heterogeneous node connectivity with independent trees which are not necessarily spanning. A recent algorithm, referred to as DAG Independent Trees that gives vertex independent trees in heterogeneously connected directed acyclic graphs (DAGs) is discussed.

The problem of realizing the vertex connectivity in independent trees is NP-complete. Therefore, an experimental analysis of the connectivity realized with independent trees given by the algorithm, and vertex connectivity from the nodes to sink is given. The results show that the algorithm nearly satises the condition that all nodes realize at least half the connectivity. A close approximation to the connectivity at more than half the nodes is achieved. In the case, when the algorithm does less than half the connectivity for most of the nodes, an optimization of the algorithm is given. The optimization over all permutations of the sink nodes is presented in the case when it does not fair well.

Committee:

Kenneth Berman, PhD (Committee Chair); Fred Annexstein, PhD (Committee Member); Anca Ralescu, PhD (Committee Member)

Subjects:

Computer Science

Keywords:

Connectivity;Independent trees;DAGs;Multipath Routing;Data gathering;Wireless Sensor Networks;

Mamidisetty, Kranthi KumarContour Guided Dissemination In Regular Multihop Networked Systems
Doctor of Philosophy, University of Akron, 2012, Computer Engineering

The problem of exploiting all the available shortest paths between a source and destination to improve Quality of Service (QoS) is deceptively simple. From prior work it is known that even when multiple shortest paths are available, a straightforward approach to using such paths will result in nodes along one of the paths handling more entities than the nodes along the other shortest paths. This phenomenon, called Loading, limits the QoS and warrants the design of new methods to better utilize the available paths. A contour was defined as the union of all the shortest paths between a source and a destination. It was also shown that contours have an interesting structure that depended on the number of neighbors of each node and the relative location of the source and the destination. This structure characterized the number of corner nodes, the length of the shortest paths, the number of shortest paths, the depth of the expansion region, and depth of the contraction region in graph theoretic terms. The structural characterization of contours was important both for precisely characterizing loading and for designing effective methods to exploit the paths available in the contours. However, several questions remained open.

This dissertation presents a new graph theoretic characterization of the structure of contours in regular mesh connected topologies when each node has three neighbors. This is a particularly interesting structure because it appears to be robust while making efficient use of the available resources. The results show that the structure of contours are severely affected by the relative location of the source and destination. This means that a small change in the location of either the source or the destination can dramatically change the structure of the contours and hence affect the QoS that can be achieved. The results here show that for over two-thirds of the source-destination pairs that are possible, the contours will have a pendant node, i.e., a node that is connected to only one neighbor - and this node is the bottleneck node that limits performance.

For a new application, it is possible to use different kinds of connectivity between the nodes - for example, nodes can have four neighbors, eight neighbors, six neighbors or three neighbors. Each choice has a cost associated with it and the choice critically affect the QoS. This dissertation presents empirical results that offer new insights into the Cost Vs. QoS tradeoffs in the design of mesh connected systems. These results show that the best throughput can be achieved when each node has six neighbors and the best latency is achieved when each node has eight neighbors. This dissertation also presents two applications that demonstrate how the structure of the neighborhoods and the structure of contours can be exploited to improve performance. The first application is in the domain of data aggregation - it is shown that the structure of neighborhoods help to identify cluster heads. The second application demonstrates how the structure of contours can be exploited to improve QoS in a Network-on-Chip that is central to the design of next-generation processors.

The third focus for this dissertation is to understand how to weaken the regularity assumption that was central to the graph theoretic characterizations. Given a system that does not have a regular topology, the discovery of contours is not a significant challenge because simple extensions of the classical shortest path algorithms will discover contours. However, it is difficult to characterize the structure of contours. In the absence of such a characterization, one needs to use a stochastic technique to improve QoS. It is shown that classical machine learning algorithms can effectively exploit the contours to improve QoS. It is first shown empirically that critical parameters that control the performance of the machine learning algorithm, namely the learning rate and feedback interval, depend on the topology. Next it is shown that when multiple contours overlap, the machine learning algorithm effectively spreads entities to improve QoS. Finally, empirical results also show that the machine learning algorithm exploits non-shortest paths to achieve the best possible QoS.

Committee:

Shivakumar Sastry, Dr (Advisor); Nathan Ida, Dr (Committee Member); Hamid Bahrami, Dr (Committee Member); Ali Dhinojwala, Dr (Committee Member); Dane Quinn, Dr (Committee Member)

Subjects:

Electrical Engineering

Keywords:

Multipath Routing; Regular Mesh Topologies; Message Dissemination; Machine Learning

Shukla, ManishTCP Performance With Multipath Routing in Wireless Ad Hoc Networks
MS, University of Cincinnati, 2003, Engineering : Computer Science
Majority of applications on the Internet today use TCP for reliable communication. TCP has been designed for and fine tuned to wired environments, but recent studies have shown that its performance suffers in wireless network environments, particularly in ad hoc networks because of the presence of multiple wireless hops. Routing has been the most focused area of research in recent years in wireless ad hoc networking area. Many on-demand routing protocols have been proposed to improve robustness in the face of link and route failures and facilitate packet transmission. Using multiple paths to route packets is one of them. We examine the performance of the TCP protocol with multiple paths in mobile ad hoc networks (MANETs). We set up multiple routes between the TCP source and destination either manually or using an on-demand multipath routing protocol, and forward packets on both paths to reduce the load on one single path. Ordinarily one would expect the multiple paths to reduce conflict between TCP data and acknowledgement packets thus giving better overall performance. Our results do incidate that TCP performance with multipath routing shows some improvement for long routes; however, shorter routes may experience slight degradation in performance as compared to single path routing. This observation remains true even when contention-based scheduling is used to schedule packets on different paths, or the multiple routes are chosen such that they have a minimum radio interference among themselves. We conclude that the TCP could gain only limited benefits with multipath routing.

Committee:

Dr. Samir R. Das (Advisor)

Keywords:

TCP over wireless; TCP over AD HOC Networks; multipath routing; TCP performance with multipath; multipath in wireless network