Intelligent distributed routing under constraints and imprecise state information

The goal of quality-of-service (QoS) routing is to find a network path which has sufficient resources to satisfy certain constraints on delay, bandwidth and/or other metrics. The network state information maintained at every node is often imprecise in a dynamic environment because of nonnegligible propagation delay of state messages, periodic updates due to overhead concern, and hierarchical state aggregation. The information imprecision makes QoS routing difficult. The traditional shortest-path routing algorithm does not provide satisfactory performance with imprecise state information. We propose a distributed routing scheme, called ticket-based probing, which searches multiple paths in parallel for a satisfactory one. The scheme is designed to work with imprecise state information. It allows the dynamic trade-off between the routing performance and the overhead. The state information of intermediate nodes is collectively used to guide the routing messages along the most appropriate paths in order to maximize the success probability. The proposed algorithm consider not only the QoS requirements but also the cost optimality of the routing path. Extensive simulations show that our algorithm achieve high call-admission ratio and low-cost routing paths with modest overhead. The algorithm can tolerate high degree of information imprecision.

Since the nodes in mobile ad hoc network act as a router and host, the routing protocol is the primary issue and has to be supported before any applications can be deployed for ad hoc wireless network. In recent years much work has been done on routing in ad hoc networks. But most of them couldn't provide the quality-of-service (QoS). Considering the characters of dynamic topology and the imprecise state information in mobile ad hoc network, we propose an extension QoS routing algorithm based on dynamic source routing (DSR) protocol while adopting fuzzy logic to select the appropriate QoS routing in multiple paths which are searched in parallel. The algorithm can tolerate a high degree of information imprecision by adding the fuzzy logic module which integrates the QoS requirements of application and the routing QoS parameters to determine the most qualified one in every node. This scheme considers not only the bandwidth and end-to-end delay of routing, but also the cost of the path. So it also may improve the network performance. On the other hand the merit of using fuzzy logic is that it can be implemented by hardware. This makes the realization of the scheme easier and faster. However our algorithm is based on DSR, the maximal hop count should be less than 10, i.e., the scale of mobile ad hoc network should not be very large.

To provide ubiquitous services and the same real-time services as those available on the wired networks for mobile users, this paper proposes an efficient and intelligent QoS-aware mobility scheme, coined dynamic point forwarding scheme under mobility scenario in future all-IP wireless networks. Considering dynamic channel characteristics and user mobility in wireless networks, the proposed scheme takes advantage of both the point forwarding scheme in mobility management and dynamic RSVP (DRSVP) in QoS guarantee. Moreover, in order to overcome deficiencies in conventional point forwarding scheme, we develop a new decision criterion for performing forwarding chain update, which achieves a better trade-off between network resource consumed by routing path and signaling load for forwarding chain updates. Based on the performance analyses, our proposed scheme can substantially reduce more resource reservation than the conventional pointer forwarding scheme, thus it can achieve efficient resource utilization and guarantee QoS requirements of multimedia applications in the future wireless all-IP networks.

In this paper, we extend the previously presented QoS routing scheme called pre-computation based selective probing (PCSP) to the practical environment where the state information available for the routing decision is not precise. This extended PCSP algorithm pre-computes the QoS variations as well as the cost and QoS metrics of the least-cost and best-quality paths, taking into account the impreciseness of state information. The pre-computed information enables to strictly limit the set of neighbor nodes involved in the probing process, thereby reducing the message complexity without sacrificing cost optimality. This extended PCSP scheme encompasses the original PCSP scheme as a special case where the variation of state information reduces to zero. Computer simulation reveals that the extended PCSP scheme maintains low message complexity and high success ratio with guaranteed optimal search.

This study proposes a structural model for defaultable options in a fuzzy environment. The proposed model is capable of dealing with market state variables, including firm value and fractional recovery rate, which are uncertain factors that differ from probabilistic essence and exhibit difficulty in determining precise price values exactly, namely they are market variables about which investors have only imprecise information. Since the unavailability of reliable accounting data makes the true value of firm assets unobservable, this study takes the advantage of fuzzy logic and adds a source of uncertainty to the classical stochastic default model, such as that of Klein (1996), to improve model performance. To show the robustness of the proposed model, some daily data of call options price are used to investigate its reliability. The empirical results demonstrate that the proposed fuzzy logic model has significantly better performance than previous structural form models and is indeed a useful means to manage prices risk for both option buyers and writers. This study is provided with the aim of offering insights into future research on defaultable options pricing under imprecise market information.

Supporting transmission of stream media over wireless mobile networks is often difficult because packets may be lost due to the rerouting of packets during handoff, and also because bursts of packet loss may occur during handoff due to the disparity in the amount of available bandwidth among different cells. In this paper, we propose an end-to-end multipath handoff scheme that provides smooth handoff for stream media in wireless networks with different amounts of available bandwidth from cell to cell. In the proposed scheme, multiple paths are established during handoff to reach a mobile destination node. The stream media sources are equipped with an adaptive multilayer encoder, and important layers in the encoded video stream are duplicated and transmitted over multiple paths during handoff. The effectiveness of the proposed multipath handoff scheme is verified and compared with existing schemes through extensive simulations. The simulation results show that the proposed scheme provides higher throughput and better quality for stream media.

Estimation models in software engineering are used to predict some important attributes of future entities such as software development effort, software reliability and programmers productivity. Among these models, those estimating software effort have motivated considerable research in recent years. Estimation by analogy is one of the attractive techniques in software effort estimation field. However, the procedure used in estimation by analogy is not yet able to handle correctly categorical data. In this paper, we propose a new approach based on reasoning by analogy, fuzzy logic and linguistic quantifiers to estimate effort when the software project is described either by categorical or numerical data. Fuzzy logic-based cost estimation models are more appropriate when vague and imprecise information is to be accounted for. Fuzzy systems try to behave just like the processes of the brain with a rule base. In our proposed method the effort and the cost can be estimated using the Fuzzy logic based analogy method and the cost can be calculated. The performance of the proposed system is calculated using MARE (Mean Absolute Relative Error).

Presently, the wireless mobile networks and devices are becoming increasingly popular to provide users the access anytime and anywhere. The mobile systems are based on cellular approach and the area is covered by cells that overlap each other. Many handover algorithms are proposed in the literature. However, to make a better handover and keep the QoS in wireless networks is very difficult. In this paper, we propose a new handover system based on fuzzy logic. We consider the case of handover enforcement and verify that the proposed system makes the necessary handovers for all simulations.KeywordsMobile StationFuzzy Logic ControllerRandom Walk ModelFuzzy Rule BaseVertical HandoffThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

This study evaluates a time changed Levy model for European call options under a fuzzy environment. The proposed model is characterized by high frequency jumps, stochastic volatility, and stochastic volatility with the jumps, existing in the returns process of financial assets. Moreover, to consider imperfect and unpredictable accounting information, this study uses fuzzy logic to account for the impreciseness of the accounting information, which can not be described in extant models, and provides reasonable reference instruments for future research on option pricing under a jump diffusion model with imprecise market information. Our empirical results also show that the fuzzy time changed Levy model has better fitting performance when compared with the time changed Levy and the Black and Scholes model when using S&P 500 index option data.

In this work, we propose a cross-layer optimized multipath video streaming system over heterogeneous wireless networks. The proposed system uses multiple paths over wireless mobile networks in order to satisfy the quality-of-service requirements for seamless high-quality video streaming services and adopts fountain codes to handle the effect of lost packets over wireless networks efficiently. Moreover, a cross-layer approach is used to determine the code rate of fountain codes efficiently. Finally, the proposed system is implemented and tested in real environments.

: In this paper, we examine network architecture issues and protocols for applicability to mobile and dynamic wireless communication networks. Our focus is on networking technology to provide heterogeneous support and interoperability with existing and planned internetworking infrastructures and applications. First, we discuss engineering issues and technology components across a broad range of mobile networking system elements. Second, we focus in detail on a number of critical technology areas relating to mobility support and interoperability with the Internet Protocol (IP) suite. Our goal is to highlight important issues, provide guidance in examining architectural and protocol tradeoffs and help assess the maturity of technology components for near term deployment of network systems and further experimentation in ongoing mobile network projects. Since there is not a definitive one size fits all solution space to the design components involved in mobile networking, a future follow-on study is planned to provide more project-specific recommendations for specific wireless networking technology architectures and requirements-e.g. Interoperable Networks for Secure Communications (lNSC).

One of the challenging tasks of current generation wireless networks consist of supporting service continuity when users roam around different networks such as Wi-Fi, Bluetooth, and Cellular networks. This happens especially when dealing with applications such as multimedia streaming that distribute time continuous data with stringent Quality of Service (QoS) requirements like bandwidth, jitter, delay and packet loss. Session handover can solve this problem by ensuring service continuity through minimization of flow interruptions when users are mobile. Building upon a new Bayesian Belief framework, this paper proposes a context-aware handoff decision process that uses a multi-criteria decision making model to support QoS-based mobility in wireless networks. Using the widely deployed Hugin Expert Bayesian belief support tool, we illustrate its deployment in a network environment where mobility decisions are taken to roam around Wi-Fi or Bluetooth networks.

In this paper, we revisit two classes of mobility models which are widely used to represent users' mobility in wireless networks: random waypoint (RWP) and random direction (RD). For both models, we obtain systems of partial differential equations which describe the evolution of the users' distribution. For the RD model, we show how the equations can be solved analytically both in the stationary and transient regime, adopting standard mathematical techniques. Our main contributions are 1) simple expressions which relate the transient duration to the model parameters and 2) the definition of a generalized random direction model whose stationary distribution of mobiles in the physical space corresponds to an assigned distribution.

A fuzzy expert system for the design of machining operations

: Based on analogues from physical systems and science, we have investigated, developed, and evaluated prediction and control strategies for assured operation in high data rate, mobile wireless networks. The dynamic wireless networks, and their optimization, were analyzed by methods used in molecular dynamics. A significant outcome of this research is an application for a patent as follows: Systems, Methods, Devices, and Computer Program Products for Control and Performance Prediction in Wireless Networks. We considered wired as well as wireless networks, and we addressed the fundamental problems of how information should be fused over a network. In addition, we studied the performance and tradeoffs of integration of cooperative communication with network coding for assurance of information transfer.