THE DESIGN AND ANALYSIS OF EXPERIMENTS. By Oscar Kempthorne. New York, John Wiley and Sons, Inc., 1952. 631 pp. $8.50. This book by a teacher of statistics (as well as a consultant for \"experimenters\") is a comprehensive study of the philosophical background for the statistical design of experiment. It is necessary to have some facility with algebraic notation and manipulation to be able to use the volume intelligently. The problems are presented from the theoretical point of view, without such practical examples as would be helpful for those not acquainted with mathematics. The mathematical justification for the techniques is given. As a somewhat advanced treatment of the design and analysis of experiments, this volume will be interesting and helpful for many who approach statistics theoretically as well as practically. With emphasis on the \"why,\" and with description given broadly, the author relates the subject matter to the general theory of statistics and to the general problem of experimental inference. MARGARET J. ROBERTSON

The Design and Analysis of Experiments

Delay Tolerant Networks are wireless networks where disconnections may occur frequently due to propagation phenomena, node mobility, and power outages. Propagation delays may also be long due to the operational environment (e.g. deep space, underwater). In order to achieve data delivery in such challenging networking environments, researchers have proposed the use of store-carry-and-forward protocols: there, a node may store a message in its buffer and carry it along for long periods of time, until an appropriate forwarding opportunity arises. Additionally, multiple message replicas are often propagated to increase delivery probability. This combination of long-term storage and replication imposes a high storage overhead on untethered nodes (e.g. handhelds). Thus, efficient buffer management policies are necessary to decide which messages should be discarded, when node buffers are operated close to their capacity. In this paper, we propose efficient buffer management policies for delay tolerant networks. We show that traditional buffer management policies like drop-tail or drop-front fail to consider all relevant information in this context and are, thus, sub-optimal. Using the theory of encounter-based message dissemination, we propose an optimal buffer management policy based on global knowledge about the network. Our policy can be tuned either to minimize the average delivery delay or to maximize the average delivery rate. Finally, we introduce a distributed algorithm that uses statistical learning to approximate the global knowledge required by the the optimal algorithm, in practice. Using simulations based on a synthetic mobility model and real mobility traces, we show that our buffer management policy based on statistical learning successfully approximates the performance of the optimal policy in all considered scenarios. At the same time, our policy outperforms existing ones in terms of both average delivery rate and delivery delay.

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Optimal Buffer Management Policies for Delay Tolerant Networks

The Air Force Institute of Technology

Catastrophic failures of power systems are phenomena which occur with some regularity throughout the world. It is recognized that these cannot be prevented, although with the use of newer developments in power engineering, in communication systems, and in computer engineering it would be possible to reduce their frequency and their impact on society. Analyses of many blackouts point to some salient features which are common to most such events: power systems under stress because of high load levels or outages of important facilities, some initiating event-usually a fault, often followed by cascading effects due to unwanted operation of some protection systems. In particular, the role of hidden failures (HFs) in protection systems in propagating power system disturbances has become clearer with some of the recent research reported in the literature. This paper explores further the issue of HFs of protection systems and possible countermeasures. Regarding the countermeasures, adapting the protection systems so that they would change their operational logic from OR to a VOTING protocol has been discussed in the literature, and is well within the capability of present technology. Other hardware solutions, such as "Hidden Failure Monitoring and Protection Systems," have also been discussed in the literature. Most of these countermeasures will require intensive use of communication networks. Communication infrastructure will be utilized for real-time data transfer, as well as for slower speed data gathering tasks related to the condition of the power system. In this paper, we concentrate on the communication facilities and their applications for providing countermeasures against catastrophic failures of power systems.

/pdf/catastrophic-failures-in-power-systems-causes-analyses-and-1ascnjycaw.pdf

Catastrophic Failures in Power Systems: Causes, Analyses, and Countermeasures

Delay and disruption tolerant networks (DTNs) may experience frequent and long-lived connectivity disruptions. Unlike traditional networks, such as the TCP/IP-based Internet, DTNs are often subject to high latency caused by very long propagation delays (e.g., interplanetary communication) and/or intermittent connectivity. Another feature that sets DTNs apart from conventional networks is that there is no guarantee of end-to-end connectivity between source and destination. Such distinct features pose a number of technical challenges in designing core network functions such as routing and congestion control. In this paper, we survey the state-of-the-art in DTN congestion control. We propose a taxonomy to map the DTN congestion control design space and use it to classify existing DTN congestion control mechanisms.

A survey on congestion control for delay and disruption tolerant networks

Delay tolerant networking (DTN) and more specifically the subset known as intermittently connected networking, is emerging as a solution for supporting asynchronous data transfers in challenging environments where a fully connected end-to-end path between a source and destination may never exist. Message delivery in such networks is enabled via scheduled or opportunistic communication based on transitive local connectivity among nodes influenced by factors such as node mobility. Given the inherently store-and-forward and opportunistic nature of the DTN architecture, the choice of buffer management policies and message forwarding strategies can have a major impact on system performance. In this paper, we propose and evaluate different combinations of queueing policies and forwarding strategies for intermittently connected networks. We show that a probabilistic routing approach along with the correct choice of buffer management policy and forwarding strategy can result in much performance improvements in terms of message delivery, overhead and end-to-end delay.

/pdf/evaluation-of-queueing-policies-and-forwarding-strategies-42cv8y6fgh.pdf

Evaluation of Queueing Policies and Forwarding Strategies for Routing in Intermittently Connected Networks

The integration of various network-level functions, including routing, management, and security, is critical to the efficient operation of a mobile ad hoc network. In this article we focus on network mobility (rather than node mobility), implying the movement of entire subnetworks with respect to one another, while individual users initially associated with one such subnetwork may also move to other domains. One example is a battlefield network that includes ships, aircraft, and ground troops. In this "network of networks", subnets (e.g. shipboard networks) may be interconnected via a terrestrial mobile wireless network (e.g., between moving ships). We discuss the design and implementation of a new ad hoc routing protocol, a suite of solutions for policy-based network management, and approaches for key management and deployment of IPsec in a MANET. These solutions, in turn, are integrated with real-time middleware, a secure radio link, and a topology monitoring tool. We briefly describe each component of the solution, and focus on the challenges and approaches to integrating these components into a cohesive system to support network mobility. We evaluate the effectiveness of the system through experiments conducted in a wireless ad hoc testbed.

/pdf/network-mobility-and-protocol-interoperability-in-ad-hoc-4n8xva6s69.pdf

Network mobility and protocol interoperability in ad hoc networks

Quality of service (QoS) provisioning and management in ad hoc networks remains a challenging task. Policy-Based Network Management (PBNM) is one approach for QoS provisioning and management that h ...

Design and demonstration of policy-based management in a multi-hop ad hoc network

The management of mobile ad hoc networks (MANETs) is a challenging task. Previous work on this topic has focused largely on the monitoring and data collection aspects of network management; literature on the provisioning of devices and protocol support for MANET configuration is scarce. We present a solution suite to extend policy-based management, for the first time, to MANETs. The solution suite consists of four schemes - k-hop clustering, dynamic service redundancy (DynaSeR), policy negotiation, and automated service discovery - each addressing different challenges in managing ad hoc networks. We propose extensions to the standard common open policy service (COPS) protocol for use in MANETs, and evaluate the system performance using simulations.

Protocol support for policy-based management of mobile ad hoc networks

https://luizdasilva.files.wordpress.com/2011/02/computer_communications03.pdf

Kaustubh S. Phanse

Papers

Evaluation of Queueing Policies and Forwarding Strategies for Routing in Intermittently Connected Networks

Network mobility and protocol interoperability in ad hoc networks

Design and demonstration of policy-based management in a multi-hop ad hoc network

Protocol support for policy-based management of mobile ad hoc networks

Addressing the requirements of QoS management for wireless ad hoc networks