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Problem statement: As group key management extended into the area of large dynamic networks, complex issues emerged involving the many operations that run over several network topologies. The issues that occurred due to multiple topologies were also compounded by differing views of the network, taken at different time slices or positions within the network. This was especially complex when figuring in mobile, ad-hoc networks. View synchrony is the current operational technique, or assumption, applied to group key exchange protocols. However, before this analysis view synchrony was just that, an assumption and the literature for group key exchange lacked an inquiry into what could happen when view synchrony was removed. Current group key management protocols rely on view synchrony and yet all protocols vary in requisite operational descriptions and performance measures. In this study, a framework for group key management protocol operations and performance measures was defined and examined how that framework could be used to compare and contrast existing protocols with and, more importantly, without view synchrony. Approach: Current literature lacked categories by which to quantify the performance metric of the protocols. This study first defined the dynamic key operations that all protocols share. By these definitions, group key management protocols were directly compared. Once definitions existed, this study assembled a list of costs that every protocol requires to establish and share keys across the dynamic group. These results provided an understanding of view synchrony's role and whether or not it should be solely relied on in these current protocols. Results: The prior conclusion that view synchrony was an integral part of all group key management protocols was shattered, when seen through the lens of communication costs and assumptions in wireless ad-hoc networks. View synchrony, as an assumed part of all group key management was previously inconsistently portrayed. The ability to see this before did not exist because a framework upon which to evaluate the costs did not exist. Now, literature can proceed with clearly defined understandings of what values exist in group key management protocols. Conclusion/Recommendations: Better communication in group key management will be a benefit to the entire field. Now that costs can be analyzed, procedure and security can be improved and protocols can be implemented for wireless ad-hoc networks. In addition, it led two authors of this study to create a new protocol, DTEGK, to maximize the most efficient communication, as view synchrony was hindering the effectiveness of previous protocols. Without the hindrance of view synchrony and a quantitative list of defined communication costs, protocols can also now be extended into the wireless, ad-hoc realm of group key management. Key words: Group key management, cryptography, wireless, ad-hoc networks, INTRODUCTION In 1976, Diffie and Hellman (1976) introduced an implementation of two-party key exchange protocol that allowed two participants to create a private cryptographic key through the use of publicly [...]

A comprehensive framework for mining wireless Ad Hoc Sensor Networks (WASNs) is proposed. Findings reveal the efficiency of the proposed framework.

The optimization of the convergence rate of distributed algorithm by the topology given by the nonbipartite Ramanujan graphs is discussed. Results concluded that Ramanujan graphs could be prepared only for a limited number.

In distributed system, the concept of clustering consists on dividing the geographical area covered by a set of nodes into small zones. In mobile network, the clustering mechanism varied due to the mobility of the nodes any time in any direction. That causes the partitioning of the network or the joining of nodes. Several existing centralized or globalized algorithm have been proposed for clustering technique, in a manner that no one node becomes isolated and no cluster becomes overloaded. A particular node called head cluster or leader is elected, has the role to organize the distribution of nodes in clusters. We propose a distributed clustering and leader election mechanism for Ad-Hoc mobile networks, in which the leader is a mobile node. Our results show that, in the case of leader mobility the time needed to elect a new leader is smaller than the time needed a significant topological change in the network is happens. Key words: Dynamic head cluster, Ad-Hoc networks, mechanism, leader, election algorithm, INTRODUCTION Mobile network is a network in which the location of the nodes is variant with the time. The mobile networks can be configured in two manners, infrastructure network and [...]

Power management in mobile network is an open challenges where the power level in the network influences the network life time. However, there are a trade off between the power consumption and the connectivity in mobile networks. We present a topology control mechanism and a routing protocol for Ad-Hoc wireless networks that chooses the shortest path given the lower power consumption. The power consumption in forwarding a packet in the proposed topology is depends on only two main factors are the number of hops and the packet size. Our analytical results are confirmed by our simulation results where both has give the same results for power consumption in sending a packet taking in consideration only the power consumed in communication. Keywords: Power saving, dynamic tree, dynamic routing protocol, topology discovering for mobile networks., INTRODUCTION In wireless communications networks, energy consumption is a major performance metric, lower is the energy consumption longer is the network life time. Thus, there are an increasing interest in [...]

Mobile ad hoc networks(MANET) represent complex distributed systems that comprise wireless mobile nodes that can freely and dynamically self organize into arbitrary and temporary ad-hoc network topologies, allowing people and devices to seamlessly internet work in areas with no preexisting communication infrastructure e.g., disaster recovery environments. An ad-hoc network is not a new one, having been around in various forms for over 20 years. Traditionally, tactical networks have been the only communication networking application that followed the ad-hoc paradigm. Recently the introduction of new technologies such as Bluetooth, IEEE 802.11 and hyperlan are helping enable eventual commercial MANET deployments outside the military domain. These recent revolutions have been generating a renewed and growing interest in the research and development of MANET. To facilitate communication within the network a routing protocol is used to discover routes between nodes. The goal of the routing protocol is to have an efficient route establishment between a pair of nodes, so that messages can be delivered in a timely manner. Bandwidth and power constraints are the important factors to be considered in current wireless network because multi-hop ad-hoc wireless relies on each node in the network to act as a router and packet forwarder. This dependency places bandwidth, power computation demands on mobile host to be taken into account while choosing the protocol. Routing protocols used in wired network cannot be used for mobile ad-hoc networks because of node mobility. The ad-hoc routing protocols are divided into two classes: table driven and demand based. This paper reviews and discusses routing protocol belonging to each category. Keywords: MANET, Routing Protocol, On-demand, active and reactive protocols, INTRODUCTION Wireless network has become very popular in the computing industry. Wireless network are adapted to enable mobility. There are two variations of mobile network. The first is infra-structured network [...]

The simulations results showed that the overall EABR enhancement, when compared with ABR, in terms of communication overhead was ranging from 36% to 56%. While the overall EABR enhancement in terms of number of operation required to reconstructing the route was ranging from 36% to 55%. These enhancements were contributed to the novel way in route reconstructing introduced by EABR. Keywords: ad-hoc mobile Network, ABR, EABR, Associativity, Simulation, INTRODUCTION In (2) a new method for route reconstruction for the ABR(1) was proposed. The routing table was amended with a Serial No field to enhance the optimization while reconstruction [...]

This paper introduces a new intelligent-based approach for detecting islanding in distributed generation (DG). This approach utilizes and combines various system parameter indices in order to secure the detection of islanding for any possible network topology, penetration level and operating condition of the DG under study. Hence, every parameter index displays characteristics for a given set of events. The proposed technique uses the data-mining technology to extract information from the large data sets of these indices after they are screened off-line via massive event analyses using network simulations. The technique is tested on a typical DG with multiple distributed resources and the results indicate that this technique can successfully detect islanding operations. In addition, this technique can also overcome the problem of setting the detection thresholds inherent in the existing techniques by optimizing their settings. Index Terms--Artificial intelligence, data mining, distributed generation, power system protection, power systems.

This paper proposes a novel framework for developing adaptive and scalable network services. In the proposed framework, a network service is implemented as a group of autonomous agents that interact in the network environment. Agents in the proposed framework are autonomous and capable of simple behaviors (e.g., replication, migration, and death). In this paper, an evolutionary adaptation mechanism is designed using genetic algorithms (GAs) for agents to evolve their behaviors and improve their fitness values (e.g., response time to a service request) to the environment. The proposed framework is evaluated through simulations, and the simulation results demonstrate the ability of autonomous agents to adapt to the network environment. The proposed framework may be suitable for disseminating network services in dynamic and large-scale networks where a large number of data and services need to be replicated, moved, and deleted in a decentralized manner. Index Terms--Adaptive and scalable network services, autonomous agents, evolutionary computation, sell-organization, swarm intelligence.

An efficient parallel implementation of neural networks on mesh-connected SIMD machines is discussed.

An innovative transport-aware Internet protocol (IP) router architecture is described and discussed.

An innovative distributed deadlock mechanism is proposed and discussed.

A pseudo-likelihood approach is proposed for solving network tomography problems.

An algorithm for the gossiping problem, defined over an n processor network, N, where multicasting is allowed,?is described and discussed. ?

An approach is described for for enabling network and Web server clients to evaluate a system's multiclass mechanisms and parameters.

Two distributed and randomized algorithms for initializing single-hop wireless ad hoc networks are described and discussed.

Multihop routing, which is used to minimize the number of wavelengths for?all-to-all broadcasting (gossiping), is examined and discussed.

Routing permutations in a class of switch-based interconnects are examined and discussed.

The genetic algorithm (GA), tabu search (TS), and the ant colony algorithm (ACA) are used to solve the reporting cells planning problem.

Design of a k-fold multicast network is described and discussed.

A fair resource allocation protocol for wireless multimedia networks is described. It relies on a combination of bandwidth reservation and bandwidth borrowing to ensure quality of service (QoS).

Queuing network models for the performance analysis of Single Program Multiple Data (SPMD) applications, running on general-purpose parallel architectures such as multiple Instruction Multiple Data (MIMD) and clusters of workstations, are examined and discussed.

The In-Transit Buffer (ITB) mechanism is discussed as a means of improving the performance of networks with source routing and wormhole switching.

A method is proposed for synthesizing networks that satisfy multiple requirements, such as high reliability, low diameter or good embeddability. The method employs a filtration process that takes a large set of randomly generated graphs as inputs, filtering out those that do not meet specified requirements.

An approach to the design of wireless sensor networks is described that reduces MAC address size.

The architecture and related communications protocols of an innovative processor-to-processor interconnection network, called Gemini, is described and discussed.

The concept of a restricted area for conducting message routing and balancing buffer utilization is proposed. The aim is to minimize traffic congestion.

The In-Transit Buffer (ITB) is proposed as a mechanism for improving performance in networks with source routing and wormhole switching. The mechanism is evaluated using the Myrinet network.

Solutions are found for loading digital subscriber loop (DSL) multicarrier (MC) systems with constraints on overall available energy and maximum energy per carrier. An analytical characterization of the solution for optimal loading that is valid for the general case of concave rate-functions is described, and it is applied to the case where the 'gap analysis' holds.

Topological properties of Optical Transpose Interconnection Systems (OTIS) are investigated. Tools are described for deriving various topological properties for a wide class of OTIS networks.

An innovative scheduling scheme, called Elastic Round Robin, is proposed. The scheme satisfies needs of wormhole switching.

An input queue-based switch architecture called HIPIQS (High-Performance Input-Queued Switch) is described. HIPIQS offers low latency for diverse message sizes, and it provides throughput comparable to that of output queuing techniques.

An all-to-all broadcast algorithm is proposed, for multidimensional all-port mesh and torus networks. A broadcast pattern is described that ensures a balanced traffic load in all of a network's dimensions, allowing the all-to-all broadcast algorithm to achieve near-optimal transmission time.

A single, unified theory is described for design of deadlock-free fully adaptive routing algorithms for all classes of network topologies and all switching procedures. A general theory is proposed that applies to direct and indirect networks, and to regular and irregular networks.

A time-optimal solution is discussed, for any Cayley network. Rings, hypercubes, cube-connected cycles and butterflies are types of Cayley networks that can make use of this solution.

Efficient multicasting with reduced link contention on irregular switch-based cut-through interconnection using up/down (UD) routing and unicast message passing is examined. It is demonstrated that for an arbitrary irregular network with UD routing, it is not possible to create an ordered list of nodes to implement an arbitrary multicast in a link contention-free manner with a minimal number of communication steps. Three multicast algorithms are proposed.

In this paper, we present a novel approach to partitioning pattern spaces using a multiobjective genetic algorithm for identifying (near-)optimal subspaces for hierarchical learning. Our approach of 'learning-follows-decomposition' is a generic solution to complex high-dimensional problems where the input space is partitioned prior to the hierarchical neural domain instead of by competitive learning. In this technique, clusters are generated on the basis of fitness of purpose - that is, they are explicitly optimized for their subsequent mapping onto the hierarchical classifier. Results of partitioning pattern spaces are presented. This strategy of preprocessing the data and explicitly optimizing the partitions for subsequent mapping onto a hierarchical classifier is found both to reduce the learning complexity and the classification time with no degradation in overall classification error rate. The classification performance of various algorithms is compared and it is suggested that the neural modules are superior for learning the localized decision surfaces of such partitions and offer better generalization. Index Terms - Genetic algorithms, neural-network architecture, pattern classification, pattern clustering methods.

We present a theoretical analysis of a new version of the LAPART adaptive inferencing neural network. Our main result is a proof that the new architecture, called LAPART 2, converges in two passes through a fixed training set of inputs. We also prove that it does not suffer from template proliferation. For comparison, Georgiopoulos et al. have proved the upper bound n - 1 on the number of passes required for convergence for the ARTMAP architecture, where n is the size of the binary pattern input space. If the ARTMAP result is regarded as an n-pass, or finite-pass, convergence result, ours is then a two-pass, or fixed-pass, convergence result. Our results have added significance in that they apply to set-valued mappings, as opposed to the usual supervised learning model of affixing labels to classes. Index Terms - Adaptive resonance theory neural networks, classification, inferencing, learning.

Communications research shows that cartesian product graphs meet multiple closure properties in static shortest-path systems for all-to-all communication. Some static systems reduce edge congestion in communication networks. A generic factor-routing scheme is described. Edge congestion of product graphs are discussed and illustrated, together with congestion density.

An analysis of the Nectar project shows that network-based multicomputers using general networks are a practical architecture. They offer the advantages of heterogeneity, system code, reusability of softwares and resource sharing. They also support high bandwidth and low latency communication. The combination of computing power and memory by the applications helps to achieve high-speed program execution in the Nectar systems. Parallelization and porting effort are minimized. Traffic characterization for multicomputing networks is provided.

The Fiber Distributed Data Interface (FDDI)-based reconfigurable network (FBRN) developed from multiple FDDI token rings is suitable for mission-critical applications. A reconfiguration algorithm developed for FBRNs improves the bandwidth availability of FBRN. The algorithm exhibits polynomial time complexity and provides optimal bandwidth for a given fault pattern. The performance analysis of the optimal algorithm leads to an upper bound on the performance of any other reconfiguration algorithm.

A modification of the LRU replacement algorithm for local area network (LAN) remote caching architecture significantly decreases replication and improves performance over a broad range of parameters. The one-copy-heuristic algorithm resorts to buffer partitioning, which works well in a LAN environment. Two versions of the algorithm, in which sites update the LRU stack for local memory references, and in which sites update LRU stacks for global references are examined. The effectiveness of the algorithm is nearly optimal in an environment where performance is memory-limited.

This paper describes a novel architecture that offers the flexibility of implementing widely varying motion-estimation algorithms. To achieve real-time performance, we employ multiple processing elements (PE's) which communicate with multiple memory banks via a multistage interconnection network. Three different block-matching algorithms - full search, three-step search, and conjugate-direction search - have been mapped onto this architecture to illustrate its programmability. We schedule the desired operations and design the required data-flow in such a way that processor utilization is high and memory bandwidth is at a feasible level. The details regarding the flow of the pixel data and the scheduling and allocation of the desired ALU operations (which pixels are processed on which processors in which clock cycles) are described in the paper. We analyze the performance of the proposed architecture for several different interconnection networks and data-memory organizations.

In this paper, we investigate hardware implementation of block matching algorithms (BMA's) for motion estimation of moving sequences. Using systolic arrays, we propose VLSI architectures for the two-stage BMA and full search (FS) BMA. The two-stage BMA using integral projections reduces greatly computational complexity with its performance comparable to that of the FS BMA. The proposed hardware architectures for the two-stage BMA and FS BMA are faster than the conventional hardware architectures with lower hardware complexity. Also, the proposed architecture of the first stage of the two-stage BMA is modeled in VHDL and simulated. Simulation results show the functional validity of the proposed architecture.

We present a technique to construct efficient belief network structures for application areas where large amounts of data are available and information on the ordering of the variables can be obtained from domain experts. We identify classes of networks that are efficient for propagating beliefs. We formulate the problem as one of determining the belief network representation from a given class that best represents the data. We use the I-Divergence measure which is known to have certain desirable properties for evaluating different approximations. We present some theoretical findings that characterize the nature of solutions that are obtained. These theoretical results lead to an efficient solution procedure for finding the best network representation. We also discuss other information that may be reasonably obtained from experts, and show how such information leads to improving the efficiency of the technique to find the best network structure. Index Terms - Belief networks, expert systems, information theory, knowledge acquisition, probabilistic reasoning, scoring rules.

In this paper, we address security in object-oriented database systems for multilevel secure environments. Such an environment consists of users cleared to various security levels, accessing information labeled with varying classifications. Our purpose is three-fold. First, we show how security can be naturally incorporated into the object model of computing so as to form a foundation for building multilevel secure object-oriented database management systems. Next, we show how such an abstract security model can be realized under a cost-effective, viable, and popular security architecture. Finally, we give security arguments based on trusted subjects and a formal proof to demonstrate the confidentiality of our architecture and approach. A notable feature of our solution is the support for secure synchronous write-up operations. This is useful when low level users want to send information to higher level users. In the object-oriented context, this is naturally modeled and efficiently accomplished through write-up messages sent by low level subjects. However, such write-up messages can pose confidentiality leaks (through timing and signaling channels) if the timing of the receipt and processing of the messages is observable to lower level senders. Such covert channels are a formidable obstacle in building high-assurance secure systems. Further, solutions to problems such as these have been known to involve various tradeoffs between confidentiality, integrity, and performance. We present a concurrent computation model that closes such channels while preserving the conflicting goals of confidentiality, integrity, and performance. Finally, we give a confidentiality proof for a trusted subject architecture and implementation and demonstrate that the trusted subject (process) cannot leak information in violation of multilevel security. Index Terms - Multilevel security, secure write-up, object-oriented databases, trusted subject architecture, covert channels, confidentiality proof.