Bilal Khan

Opportunistic Channel Selection Strategy for Better QoS in Cooperative Networks with Cognitive Radio Capabilities

Mission-oriented MANETs are characterized by implicit common group objectives which make inter-node cooperation both logical and feasible. We propose new techniques to leverage two optimizations for cognitive radio networks that are specific to such contexts: opportunistic channel selection and cooperative mobility. We present a new formal model for MANETs consisting of cognitive radio capable nodes that are willing to be moved (at a cost). We develop an effective decentralized algorithm for mobility planning, and powerful new Altering and fuzzy based techniques for both channel estimation and channel selection. Our experiments are compelling and demonstrate that the communications infrastructure-specifically, connection bit error rates-can be significantly improved by leveraging our proposed techniques. In addition, we find that these cooperative/opportunistic optimization spaces do not trade-off significantly with one another, and thus can be used simultaneously to build superior hybrid schemes. Our results have significant applications in high-performance mission-oriented MANETs, such as battlefield communications and domestic response & rescue missions.

A Dynamic Route Optimization Mechanism for AODV in MANETs

In reactive routing protocols, active routes for connections retain their topological structure even when node movements over time make the route sub-optimal (in terms of path length). In AODV, for example, a connection route is recomputed only when one of its constituent links suffers catastrophic failure-at which point repair is initiated, often requiring global route discovery and introducing significant control traffic overhead. In this paper, we propose extensions to AODV which perform continuous route optimization. The objective of our proposed extension is to ensure connection path lengths are topologically efficient in spite of node mobility. Our experiments indicate that in many typical operational regimes, this objective is achieved successfully by our proposed scheme. The proposed mechanism has been implemented and tested in ns2 as an extension to AODV.

Network Modeling and Simulation: A Practical Perspective

Preface. Acknowledgements. 1 Basic Concepts and Techniques. 1.1 Why Is Simulation Important? 1.2 What Is a Model? 1.3 Performance Evaluation Techniques. 1.4 Development of Systems Simulation. 1.5 Summary. Recommended Reading. 2 Designing and Implementing a Discrete-Event Simulation Framework. 2.1 The Scheduler. 2.2 The Simulation Entities. 2.3 The Events. 2.4 Tutorial 1: Hello World. 2.5 Tutorial 2: Two-Node Hello Protocol. 2.6 Tutorial 3: Two-Node Hello through a Link. 2.7 Tutorial 4: Two-Node Hello through a Lossy Link. 2.8 Summary. Recommended Reading. 3 Honeypot Communities: A Case Study with the Discrete-Event Simulation Framework. 3.1 Background. 3.2 System Architecture. 3.3 Simulation Modeling. 3.4 Simulation Execution. 3.5 Output Analysis. 3.6 Summary. Recommended Reading. 4 Monte Carlo Simulation. 4.1 Characteristics of Monte Carlo Simulations. 4.2 The Monte Carlo Algorithm. 4.3 Merits and Drawbacks. 4.4 Monte Carlo Simulation for the Electric Car Charging Station. 4.5 Summary. Recommended Reading. 5 Network Modeling. 5.1 Simulation of Networks. 5.2 The Network Modeling and Simulation Process. 5.3 Developing Models. 5.4 Network Simulation Packages. 5.5 OPNET: A Network Simulation Package. 5.6 Summary. Recommended Reading. 6 Designing and Implementing CASiNO: A Network Simulation Framework. 6.1 Overview. 6.2 Conduits. 6.3 Visitors. 6.4 The Conduit Repository. 6.5 Behaviors and Actors. 6.6 Tutorial 1: Terminals. 6.7 Tutorial 2: States. 6.8 Tutorial 3: Making Visitors. 6.9 Tutorial 4: Muxes. 6.10 Tutorial 5: Factories. 6.11 Summary. Recommended Reading. 7 Statistical Distributions and Random Number Generation. 7.1 Introduction to Statistical Distributions. 7.2 Discrete Distributions. 7.3 Continuous Distributions. 7.4 Augmenting CASiNO with Random Variate Generators. 7.5 Random Number Generation. 7.6 Frequency and Correlation Tests. 7.7 Random Variate Generation. 7.8 Summary. Recommended Reading. 8 Network Simulation Elements: A Case Study Using CASiNO. 8.1 Making a Poisson Source of Packets. 8.2 Making a Protocol for Packet Processing. 8.3 Bounding Protocol Resources. 8.4 Making a Round-Robin (De)multiplexer. 8.5 Dynamically Instantiating Protocols. 8.6 Putting It All Together. 8.7 Summary. 9 Queuing Theory. 9.1 Introduction to Stochastic Processes. 9.2 Discrete-Time Markov Chains. 9.3 Continuous-Time Markov Chains. 9.4 Basic Properties of Markov Chains. 9.5 Chapman-Kolmogorov Equation. 9.6 Birth-Death Process. 9.7 Littles Theorem. 9.8 Delay on a Link. 9.9 Standard Queuing Notation. 9.10 The M/M/ 1 Queue. 9.11 The M/M/m Queue. 9.12 The M/M/ 1 /b Queue. 9.13 The M/M/m/m Queue. 9.14 Summary. Recommended Reading. 10 Input Modeling and Output Analysis. 10.1 Data Collection. 10.2 Identifying the Distribution. 10.3 Estimation of Parameters for Univariate Distributions. 10.4 Goodness-of-Fit Tests. 10.5 Multivariate Distributions. 10.6 Selecting Distributions without Data. 10.7 Output Analysis. 10.8 Summary. Recommended Reading. 11 Modeling Network Traffic. 11.1 Introduction. 11.2 Network Traffic Models. 11.3 Traffic Models for Mobile Networks. 11.4 Global Optimization Techniques. 11.5 Particle Swarm Optimization. 11.6 Optimization in Mathematics. 11.7 Summary. Recommended Reading. Index.

ON POSITIVE THEORIES OF GROUPS WITH REGULAR FREE LENGTH FUNCTIONS

In this paper we discuss a general approach to positive theories of groups. As an application we get a robust description of positive theories of groups with regular free Lyndon length function. Our approach combines techniques of infinite words (see [17, 3]), cancellation diagrams introduced in [14], and Merzlyakovs method [15].

NIS05-6: A Non-Commutative Generalization of ElGamal Key Exchange using Polycyclic Groups

In this paper, we propose a non-commutative key-exchange scheme which generalizes the classical ElGamal Cipher to polycyclic groups. We describe the criteria for groups which would provide good candidates for such cryptosystems, we also examine the complexity of the decision problems related to these key exchange.

A reexamination of connectivity trends via exponential random graph modeling in two IDU risk networks.

Patterns of risk in injecting drug user (IDU) networks have been a key focus of network approaches to HIV transmission histories. New network modeling techniques allow for a reexamination of these patterns with greater statistical accuracy and the comparative weighting of model elements. This paper describes the results of a reexamination of network data from the SFHR and P90 data sets using Exponential Random Graph Modeling. The results show that “transitive closure” is an important feature of IDU network topologies, and provides relative importance measures for race/ethnicity, age, gender, and number of risk partners in predicting risk relationships.

Hepatitis C virus infection among HIV-positive men who have sex with men: protocol for a systematic review and meta-analysis

BackgroundOutbreaks of hepatitis C virus (HCV) infection have been reported in HIV-positive men who have sex with men (MSM) in North America, Europe and Asia. Transmission is believed to be the result of exposure to blood during sexual contact. In those infected with HIV, acute HCV infection is more likely to become chronic, treatment for both HIV and HCV is more complicated and HCV disease progression may be accelerated. There is a need for systematic reviews and meta-analyses to synthesize the epidemiology, prevention and methods to control HCV infection in this population.Methods/designEligible studies will include quantitative empirical data related to sexual transmission of HCV in HIV-positive MSM, including data describing incidence or prevalence, and associations between risk factors or interventions and the occurrence or progression of HCV disease. Care will be taken to ensure that HCV transmission related to injection drug use is excluded from the incidence estimates. Scientific databases will be searched using a comprehensive search strategy. Proceedings of scientific conferences, reference lists and personal files will also be searched. Quality ratings will be assigned to each eligible report using the Newcastle–Ottawa scale. Pooled estimates of incidence rates and measures of association will be calculated using random effects models. Heterogeneity will be assessed at each stage of data synthesis.DiscussionHIV-positive MSM are a key HCV-affected population in the US and other high-income countries. This review seeks to identify modifiable risk factors and settings that will be the target of interventions, and will consider how to constitute a portfolio of interventions to deliver the greatest health benefit. This question must be considered in relation to the magnitude of HCV infection and its consequences in other key affected populations, namely, young prescription opioid users who have transitioned to illicit opiate injection, and older injection drug users among whom HCV prevalence and incidence are extremely high. This review is part of a series of systematic reviews and meta-analyses that will synthesize the evidence across all these population groups and develop recommendations and decision tools to guide public health resource allocation.Trial registrationPROSPERO registration number: CRD42013006462

Current Rural Drug Use in the US Midwest

The nature and challenge of illicit drug use in the United States continues to change rapidly, evolving in reaction to myriad social, economic, and local forces. While the use of illicit drugs affects every region of the country, most of our current information about drug use comes from large urban areas. Data on rural drug use and its harms justify greater attention. Record overdose rates, unexpected outbreaks of HIV, and a dearth of treatment facilities point to a rapidly worsening health situation. While health sciences have made considerable progress in understanding the etiology of drug use and uncovering the link between drug use and its myriad associated harms, this promising scientific news has not always translated to better health outcomes. The scope of the problem in the Central Plains of the US is growing, and can be estimated from available sources. Clear remedies for this rising level of abuse are available, but few have been implemented. Suggestions for short-term policy remedies are discussed.

Out on the Land: Income, Subsistence Activities, and Food Sharing Networks in Nain, Labrador

In recent Inuit ethnography, a major concern has been how and to what extent contemporary Inuit participate in and depend on subsistence activities, particularly in the context of increasing wage employment and growing participation in the cash economy. This paper provides an analysis of these activities in the predominately Inuit community of Nain, Labrador. Using social network data and demographic information collected between January and June 2010, we examine the interconnections between subsistence activities—obtaining “country food” through activities such as hunting, fishing, and collecting—with access to the means of obtaining subsistence resources (such as snow mobiles, cabins, and boats), employment status, and income. Our data indicate that individuals with higher employment status and income tend to be more central to the network of subsistence food sharing, but not because they have greater access to hunting tools or equipment (they do not). We conclude that those individuals who play the most central role in the network are those who are financially able to do so, regardless of access to hunting tools/means.

Two Approaches for Aggregation of Peer Group Topology in Hierarchical PNNI Networks

ABSTRACTWe propose two methods for aggregation of peer group topology in hierarchical ATM networks. Both proposed aggregation methods transform a given peer group into a star graph representation. Our first approach optimally preserves, in a least square sense, the original costs of routing through the peer group. Our second approach assigns a weighted vector to the nucleus of the Logical Group Node, which quantifies the error in the compact representation. The two schemes are dual, in the sense that the first is best suited for peergroups where traffic patterns are unpredictable, and the second is suited for peergroups where traffic patterns can be characterized. Both the proposed schemes are practical: For peer groups with nodes V, links E, and n border nodes B ⊂ V, the approaches run in O(n|V|log|V| + n|E|+ poly(n)) time. The size of the final representation is small (linear in the number of border nodes) and can be computed efficiently. The scalability of the proposed algorithms makes them well-suited...