Caching algorithm for fast handoff using AP graph with multiple vehicles for VANETs

Secure algorithm for cloud computing and its applications

Abstract: Cloud computing is a rising technology that is still unclear to many security issues. The most challenging issue today in cloud servers is to ensure data security and privacy of the users. The proposed schema presents HE-RSA or hybrid encryption RSA along with Advanced Encryption Standard or AES to ensure efficiency, consistency and trustworthiness in cloud servers. The goal of this paper is to use various cryptography concepts during communication along with its application in cloud computing and to enhance the security of ciphertext or encrypted data in cloud servers along with minimizing the consumption of time, cost and memory size during encryption and decryption.

A framework for data security and storage in Cloud Computing

Abstract: Cloud Computing is a rising field in the history of computing. It is a way to maximise the capacity and capabilities without spending a lot to buy a new infrastructure and software. When users are online, they can get faster access to their data due to the massive storage. Although Cloud computing has many advantages due to large number of organizations moving towards it, it comes up with lots of security issues and breaches faced by both cloud service providers and users which are addressed in this paper. An efficient framework is devised for dealing with such issues. Proposed framework can protect data while transferring, sharing and storing in data centers using classification of data, Hashed Message Authentication codes and Index Building. The data is divided into three sections and accordingly the user is asked for authentication. User is provided the digital signature which can be verified with cloud directory. Using indexing, search can be made on the encrypted data.

Design of Seamless Handoff Control Based on Vehicular Streaming Communications

Abstract: Because vehicles run in high speed environments, it is difficult to establish the topology of the network. Moreover, data transmission may be interrupted by the handoff of various APs. This study established the network of roadside-to-vehicle (R2V) environment, and used the DSRC (dedicated short range communication) to achieve seamless handoff control on a streaming service. To achieve this goal, this study first used the GPS (global positioning system) to collect vehicular information (e.g., speed, direction, and location), and subsequently exchanged the parameter of vehicular information at both ends by DSRC. Therefore, the computer in the vehicle can predict the link expiration time (LET) between two mobile nodes. Furthermore, this study used two cases of handoff in vehicular networks. One case was non-overlapping handoff, and the other case was overlapping handoff. A simple formula was designed to calculate vehicular total buffer size in these two cases, and to adjust the data flow to the receiver. Finally, this study used the network simulator to simulate the actual situation of vehicular motion and network transmission. This study proved the accuracy and feasibility of mechanism through the simulation result. This study achieved the streaming of seamless handoff control in the network of R2V.

Betweenness centrality updation and community detection in streaming graphs using incremental algorithm

Abstract: Centrality measures have perpetually been helpful to find the foremost central or most powerful node within the network. There are numerous strategies to compute centrality of a node however in social networks betweenness centrality is the most widely used approach to bifurcate communities within the network, to find out the susceptibility within the complex networks and to generate the scale free networks whose degree distribution follows the power law. In this paper, we've computed betweenness centrality by identifying communities lying within the network. Our algorithm efficiently updates the centrality of the nodes whenever any edge or vertex addition or deletion takes place within the dynamic network by modifying solely a subset of vertices. For the vertex addition, Incremental Algorithm has been used in which Streaming graphs has also been considered. Brandes approach is the most widely used approach for finding out the betweenness centrality however it's still expensive for growing networks since it takes O(mn+n2logn) amount of time and O(n+m) space however our approach efficiently updates the centrality of the nodes by taking O(|S|n+|S|nlogn) amount of time where |S| is the subset of the vertices,m is the number of edges, n is the number of vertices and |S|≤n holds true.

IntersectionCast: approximation algorithm for multi-directional broadcast storm in VANETs

Abstract: We formulate a multi-directional broadcast (MDB) storm problem arising in dense vehicular ad-hoc networks (VANETs) when the multiple nodes (moving in multiple directions) forward broadcast packets meet at the road intersections, resulting in severe packet collisions inducing delays at medium access control. In this work, we have proposed a mechanism for partitioning the graph of vehicles in an intersection into multiple bipartite directional sub-graphs, such that each sub-graph aggregates messages using short range communication and make one long range communication of aggregated message. The k balanced graph partitioning problem contains partitions of size ≤ |V|/k nodes. For a graph G = (V, E), a partitioning P, is (k, 1 + e) balanced if V is partitioned into k disjoint subsets each containing at most (1 + e)n/k vertices. Our proposed approximation algorithm for intersection-cast problem uses a balanced partition with Θ (log^2 n) approximation for balance constant, v > 1. We have given simulation results for the performance analysis of our intersection-cast protocol compared to the existing competitive schemes and found improvement in terms of broadcast success rate, reachability and message overhead in the networks.

Introduction to Algorithms

Abstract: From the Publisher: The updated new edition of the classic Introduction to Algorithms is intended primarily for use in undergraduate or graduate courses in algorithms or data structures. Like the first edition,this text can also be used for self-study by technical professionals since it discusses engineering issues in algorithm design as well as the mathematical aspects. In its new edition,Introduction to Algorithms continues to provide a comprehensive introduction to the modern study of algorithms. The revision has been updated to reflect changes in the years since the book's original publication. New chapters on the role of algorithms in computing and on probabilistic analysis and randomized algorithms have been included. Sections throughout the book have been rewritten for increased clarity,and material has been added wherever a fuller explanation has seemed useful or new information warrants expanded coverage. As in the classic first edition,this new edition of Introduction to Algorithms presents a rich variety of algorithms and covers them in considerable depth while making their design and analysis accessible to all levels of readers. Further,the algorithms are presented in pseudocode to make the book easily accessible to students from all programming language backgrounds. Each chapter presents an algorithm,a design technique,an application area,or a related topic. The chapters are not dependent on one another,so the instructor can organize his or her use of the book in the way that best suits the course's needs. Additionally,the new edition offers a 25% increase over the first edition in the number of problems,giving the book 155 problems and over 900 exercises thatreinforcethe concepts the students are learning.

Introduction to Algorithms, third edition

Abstract: If you had to buy just one text on algorithms, Introduction to Algorithms is a magnificent choice. The book begins by considering the mathematical foundations of the analysis of algorithms and maintains this mathematical rigor throughout the work. The tools developed in these opening sections are then applied to sorting, data structures, graphs, and a variety of selected algorithms including computational geometry, string algorithms, parallel models of computation, fast Fourier transforms (FFTs), and more. This book's strength lies in its encyclopedic range, clear exposition, and powerful analysis. Pseudo-code explanation of the algorithms coupled with proof of their accuracy makes this book is a great resource on the basic tools used to analyze the performance of algorithms.

An empirical analysis of the IEEE 802.11 MAC layer handoff process

Abstract: IEEE 802.11 based wireless networks have seen rapid growth and deployment in the recent years. Critical to the 802.11 MAC operation, is the handoff function which occurs when a mobile node moves its association from one access point to another. In this paper, we present an empirical study of this handoff process at the link layer, with a detailed breakup of the latency into various components. In particular, we show that a MAC layer function - probe is the primary contributor to the overall handoff latency. In our study, we observe that the latency is significant enough to affect the quality of service for many applications (or network connections). Further we find variations in the latency from one hand-off to another as well as with APs and STAs used from different vendors. Finally, we discuss optimizations on the probe phase which can potentially reduce the probe latency by as much as 98% (and a minimum of 12% in our experiments). Based on the study, we draw some guidelines for future handoff schemes.

SyncScan: practical fast handoff for 802.11 infrastructure networks

Abstract: Wireless access networks scale by replicating base stations geographically and then allowing mobile clients to seamlessly "hand off" from one station to the next as they traverse the network. However, providing the illusion of continuous connectivity requires selecting the right moment to handoff and the right base station to transfer to. Unfortunately, 802.11-based networks only attempt a handoff when a client's service degrades to a point where connectivity is threatened. Worse, the overhead of scanning for nearby base stations is routinely over 250 ms - during which incoming packets are dropped - far longer than what can be tolerated by highly interactive applications such as voice telephony. In this paper we describe SyncScan, a low-cost technique for continuously tracking nearby base stations by synchronizing short listening periods at the client with periodic transmissions from each base station. We have implemented this SyncScan algorithm using commodity 802.11 hardware and we demonstrate that it allows better handoff decisions and over an order of magnitude improvement in handoff delay. Finally, our approach only requires trivial implementation changes, is incrementally deployable and is completely backward compatible with existing 802.11 standards.