Mobility Agent Advertisement Mechanism for Supporting Mobile IP in Ad Hoc Networks
Mobile IP has been proposed to solve the problem of how a mobile node may roam from its network and still maintain connectivity to the internet. Another emerging wireless architecture, mobile ad hoc networks (MANET), can be flexibly deployed in most environments without the need for infrastructure base stations. Integrating Mobile IP and MANET will facilitate the current trend of moving to an all-IP wireless environment. In this paper we propose an architecture of integrating Mobile IP and MANET based on the on-demand routing protocols. The proposed architecture employs two agent advertisement mechanisms, Mobility Agent Advertisement Mechanism (MAAM) and Aggregation-based Mobility Agent Advertisement Mechanism (AMAAM). In both mechanisms the mobility agent uses periodic beaconing of agent advertisement messages with on-demand routing protocols. Despite its architectural advantage, MAAM has some performance issues to be tackled because it incurs excessive generation of registration request messages of mobile nodes. AMAAM is an enhancement of MAAM for reducing the overhead of the beaconing by aggregating the reply messages of the agent advertisement. The simulation results show that AMAAM can effectively reduce the overhead of periodic agent advertisement and registration process.

title: Mapping Cooperating GRID Applications by Affinity for Resource Characteristics
abstract: The Computational Grid, distributed and heterogeneous collections of computers in the Internet, has been considered a promising platform for the deployment of various high-performance computing applications. One of the crucial issues in the Grid is how to discover, select and map possible Grid resources in the Internet for meeting given applications. The general problem of statically mapping tasks to nodes has been shown to be NP-complete. In this paper, we propose a mapping algorithm for cooperating Grid applications by the affinity for the resources, named as MACA. The proposed algorithm utilizes the general affinity of Grid applications for certain resource characteristics such as CPU speeds, network bandwidth, and input/output handling capability. To show the effectiveness of the proposed mapping algorithm, we compare the performance of the algorithm with some previous mapping algorithms by simulation. The simulation results show that the algorithm could effectively utilize the affinity of Grid applications and shows good performance.

title: Efficient distributed simulation of hierarchical DEVS models: transforming model structure into a non-hierarchical one
abstract: The Discrete Event Systems Specification (DEVS) formulism specifies a discrete event system in a hierarchical, modular form. This paper presents a distributed simulation methodology for models specified by the DEVS formalism. The methodology transforms a hierarchical DEVS model into a nonhierarchical one. This transformation can eliminate the overheads incurred during conventional hierarchical simulation, and make ease the synchronization of distributed simulation, thereby increasing the stability of the simulation engine. To show the effectiveness of the proposed methodology, we realize the simulation scheme in Visual C++, and conduct a benchmark simulation for a large-scale logistics system. The performance result shows that the proposed methodology works correctly and performs better than the previous approaches.

title: A Web Services-Based Distributed Simulation Architecture for Hierarchical DEVS Models
abstract: The Discrete Event Systems Specification (DEVS) formalism specifies a discrete event system in a hierarchical, modular form. This paper presents a web-services-based distributed simulation architecture for DEVS models, named as DEVSCluster-WS. DEVSCluster-WS is actually an enhanced version of DEVSCluster by employing the web services technology, thereby retaining the advantages of the non-hierarchical distributed simulation compared to the previous hierarchical distributed simulations. By employing the web services technologies, it describes models by WSDL and utilizes SOAP and XML for inter-node communication. Due to the standardized nature of the web service technology, DEVSCluster-WS can effectively be embedded in the Internet without adhering to specific vendors and languages. To show the effectiveness of DEVSCluster-WS, we realize it in Visual C++ and SOAPToolkit, and conduct a benchmark simulation for a large-scale logistics system. We compare the performance of DEVSCluster-WS with DEVSCluster-MPI, the MPI-based implementation of DEVSCluster. The performance result shows that the proposed architecture works correctly and could achieve tolerable performance.

title: Performance of Service Location Protocols in MANET Based on Reactive Routing Protocols
abstract: Automatic service discovery, the problem of discovering service providers by specifying desired properties of services, is an important and necessary component for collaboration in the ubiquitous computing environment such as MANET. This paper investigates the effects of the on-demand route discovery on the performance of service location protocols in MANET based on on-demand routing protocols. We first design a service discovery architecture in MANET based on AODV and evaluate both the distributed and centralized versions of the architecture by simulation. For evaluating the performance, we examine such performance metrics as service hit ratio, service discovery time, and control message overheads. The results show that the distributed scheme outperforms the centralized scheme in most simulation scenarios because of the on-demand routing overheads.

title: A Resilient Multipath Routing Protocol for Wireless Sensor Networks
abstract: Wireless sensor networks should be self-configuring, highly scalable, redundant, and robust in dealing with shifting topologies due to node failure and environment changes. The energy of a sensor node is the most important system resource, and one of the best ways of conserving energy is to distribute the routing load across all sensor nodes as much equally as possible. Considering the load balance for conserving energy, multipath routing protocols have been employed in sensor networks. In this paper we present a resilient multipath routing protocol based on AODV, named as RMRP, for wireless sensor networks. RMRP is an AODV-based multipath routing protocol in which sensor nodes setup double routing paths toward sink nodes in an AODV fashion and select one of them randomly for forwarding a packet. RMRP proposes a resilient route maintenance scheme which repairs broken links by utilizing localized information around neighbor nodes of the broken link, thereby reducing the flooding range of control messages. To show the effectiveness of the proposed route maintenance scheme, we evaluate the performance enhancement of the proposed scheme by ns2-based simulation.

title: Multicriteria Fuzzy Control Using Evolutionary Programming
abstract: In this paper, we propose a multicriteria fuzzy control (MFC) using evolutionary programming (EP) by which its λ-fuzzy measure is optimized. Basically the MFC is an extended version of the existing fuzzy logic controller to obtain the proper weights of the fuzzy rules for the fine tuning control. The MFC is designed by three steps: first, the attributes of the system output response are selected, second, the partial evaluations from the viewpoints of the attributes are assigned to the fuzzy rules, and third, the fuzzy integral is employed to aggregate the partial evaluation and the user's fuzzy measure about the consideration degree of each attribute for the proper weight value. EP is used to optimize the λ-fuzzy measure for the linear tuning property of the MFC. Computer simulations indicate that the proposed scheme has excellent performance.

title: Analysis of the competition between wired, DSL and wireless users in an access network
abstract: This paper analyzes the performance of a large population composed of several classes of long lived TCP flows experiencing packet losses due to random transmission errors and to congestion created by the sharing of a common tail-drop or RED bottleneck router. Each class has a different transmission error rate. This setting is used to analyze the competition between wired and wireless users in an access network, where one class (the wired class) has no or small (like BER in DSL) transmission error losses whereas the other class has higher transmission error losses, or the competition between DSL flows using different coding schemes. We propose a natural and simple model for the joint throughput evolution of several classes of TCP flows under such a mix of losses. Two types of random transmission error losses are considered: one where losses are Poisson and independent of the rate of the flow, and one where the losses are still Poisson but with an intensity that is proportional to the rate of the source. We show that the large population model where the population tends to infinity has a threshold (given in closed form) below which there are no congestion losses at all in steady state, and above which there is a stationary limiting regime in which we can compute both the mean value and the distribution of the rate obtained by each class of flow. We also show that the maximum mean value for the aggregated rate is achieved at the threshold.

title: Background Updating for Visual Surveillance
abstract: Scene changes such as moved objects, parked vehicles, or opened/closed doors need to be carefully handled so that interesting foreground targets can be detected along with the short-term background layers created by those changes. A simple layered modeling technique is embedded into a codebook-based background subtraction algorithm to update a background model. In addition, important issues related to background updating for visual surveillance are discussed. Experimental results on surveillance examples, such as unloaded packages and unattended objects, are presented by showing those objects as short-term background layers.

title: Projection-Based Registration Using Color and Texture Information for Virtual Environment Generation
abstract: In this paper, we propose a registration method for 3D data which uses color and texture data acquired from a multi-view camera for virtual environment generation. In general, most registration methods depend on 3D data acquired by precise optical sensors. However, as for a multi-view camera, depth errors are relatively large and depths in homogeneous areas are not measurable. We propose a projection-based registration method to cope with these limitations. First, we perform initial registration by establishing relationship between multi-view cameras through inter-camera calibration. Then, by applying color and texture descriptors to projected images, fine registration is accomplished. Finally, by exploiting adaptive search ranges, color selection is attained. Even if the accuracy of 3D data is relatively low, the proposed method can effectively register 3D data. In addition, an effective color selection can be done by setting up adaptive search ranges based on depth. Through this method, we can generate a virtual environment that supports user interaction or navigation.

title: Real-time foreground-background segmentation using codebook model
abstract: We present a real-time algorithm for foreground-background segmentation. Sample background values at each pixel are quantized into codebooks which represent a compressed form of background model for a long image sequence. This allows us to capture structural background variation due to periodic-like motion over a long period of time under limited memory. The codebook representation is efficient in memory and speed compared with other background modeling techniques. Our method can handle scenes containing moving backgrounds or illumination variations, and it achieves robust detection for different types of videos. We compared our method with other multimode modeling techniques. In addition to the basic algorithm, two features improving the algorithm are presented-layered modeling/detection and adaptive codebook updating. For performance evaluation, we have applied perturbation detection rate analysis to four background subtraction algorithms and two videos of different types of scenes.