物件導向軟體之架構(Object-Oriented Software Construction)探討

The term ‘‘Internet-of-Things’’ is used as an umbrella keyword for covering various aspects related to the extension of the Internet and the Web into the physical realm, by means of the widespread deployment of spatially distributed devices with embedded identification, sensing and/or actuation capabilities. Internet-of-Things envisions a future in which digital and physical entities can be linked, by means of appropriate information and communication technologies, to enable a whole new class of applications and services. In this article, we present a survey of technologies, applications and research challenges for Internetof-Things.

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Internet of things: Vision, applications and research challenges

A mobile ad hoc network consists of wireless hosts that may move often. Movement of hosts results in a change in routes, requiring some mechanism for determining new routes. Several routing protocols have already been proposed for ad hoc networks. This report suggests an approach to utilize location information (for instance, obtained using the global positioning system) to improve performance of routing protocols for ad hoc networks.

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Location-aided routing (LAR) in mobile ad hoc networks

Praise for the Third Edition: "This is one of the best books available. Its excellent organizational structure allows quick reference to specific models and its clear presentation . . . solidifies the understanding of the concepts being presented."IIE Transactions on Operations EngineeringThoroughly revised and expanded to reflect the latest developments in the field, Fundamentals of Queueing Theory, Fourth Edition continues to present the basic statistical principles that are necessary to analyze the probabilistic nature of queues. Rather than presenting a narrow focus on the subject, this update illustrates the wide-reaching, fundamental concepts in queueing theory and its applications to diverse areas such as computer science, engineering, business, and operations research.This update takes a numerical approach to understanding and making probable estimations relating to queues, with a comprehensive outline of simple and more advanced queueing models. Newly featured topics of the Fourth Edition include:Retrial queuesApproximations for queueing networksNumerical inversion of transformsDetermining the appropriate number of servers to balance quality and cost of serviceEach chapter provides a self-contained presentation of key concepts and formulae, allowing readers to work with each section independently, while a summary table at the end of the book outlines the types of queues that have been discussed and their results. In addition, two new appendices have been added, discussing transforms and generating functions as well as the fundamentals of differential and difference equations. New examples are now included along with problems that incorporate QtsPlus software, which is freely available via the book's related Web site.With its accessible style and wealth of real-world examples, Fundamentals of Queueing Theory, Fourth Edition is an ideal book for courses on queueing theory at the upper-undergraduate and graduate levels. It is also a valuable resource for researchers and practitioners who analyze congestion in the fields of telecommunications, transportation, aviation, and management science.

Fundamentals of Queueing Theory

Parallel discrete event simulation (PDES), sometimes called distributed simulation, refers to the execution of a single discrete event simulation program on a parallel computer. PDES has attracted a considerable amount of interest in recent years. From a pragmatic standpoint, this interest arises from the fact that large simulations in engineering, computer science, economics, and military applications, to mention a few, consume enormous amounts of time on sequential machines. From an academic point of view, parallel simulation is interesting because it represents a problem domain that often contains substantial amounts of parallelism (e.g., see [59]), yet paradoxically, is surprisingly difficult to parallelize in practice. A sufficiently general solution to the PDES problem may lead to new insights in parallel computation as a whole. Historically, the irregular, data-dependent nature of PDES programs has identified it as an application where vectorization techniques using supercomputer hardware provide little benefit [14].A discrete event simulation model assumes the system being simulated only changes state at discrete points in simulated time. The simulation model jumps from one state to another upon the occurrence of an event. For example, a simulator of a store-and-forward communication network might include state variables to indicate the length of message queues, the status of communication links (busy or idle), etc. Typical events might include arrival of a message at some node in the network, forwarding a message to another network node, component failures, etc.We are especially concerned with the simulation of asynchronous systems where events are not synchronized by a global clock, but rather, occur at irregular time intervals. For these systems, few simulator events occur at any single point in simulated time; therefore parallelization techniques based on lock-step execution using a global simulation clock perform poorly or require assumptions in the timing model that may compromise the fidelity of the simulation. Concurrent execution of events at different points in simulated time is required, but as we shall soon see, this introduces interesting synchronization problems that are at the heart of the PDES problem.This article deals with the execution of a simulation program on a parallel computer by decomposing the simulation application into a set of concurrently executing processes. For completeness, we conclude this section by mentioning other approaches to exploiting parallelism in simulation problems.Comfort and Shepard et al. have proposed using dedicated functional units to implement specific sequential simulation functions, (e.g., event list manipulation and random number generation [20, 23, 47]). This method can provide only a limited amount of speedup, however. Zhang, Zeigler, and Concepcion use the hierarchical decomposition of the simulation model to allow an event consisting of several subevents to be processed concurrently [21, 98]. A third alternative is to execute independent, sequential simulation programs on different processors [11, 39]. This replicated trials approach is useful if the simulation is largely stochastic and one is performing long simulation runs to reduce variance, or if one is attempting to simulate a specific simulation problem across a large number of different parameter settings. However, one drawback with this approach is that each processor must contain sufficient memory to hold the entire simulation. Furthermore, this approach is less suitable in a design environment where results of one experiment are used to determine the experiment that should be performed next because one must wait for a sequential execution to be completed before results are obtained.

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Parallel discrete event simulation

In Wireless Access in Vehicular Environment (WAVE), the WAVE Short Messages (WSMs) are broadcasted from the Roadside Unit (RSU) to the Onboard Units (OBUs). On the other hand, WAVE does not specify how to provide WSM-based unicast service to an OBU. In this paper, we devise location tracking procedure so that an OBU can be tracked and receive unicast messages. We also investigate the effect of vehicle traffic on the location tracking mechanism.

Location Tracking for WAVE Unicast Service

This paper studies the \\priority call service\" for personal communication service such as GSM cellular networks. With this service, a priority call request is buuered in a waiting queue if no free channel is available. The buuered request can be served as soon as free channels become available. We develop an analytic model to evaluate the performance for the priority call service. In addition , computer simulations are conducted to verify the analytic model. The results indicate that priority calls experience very low new call blocking probability as well as low call incompletion probability at the cost of increasing the force-termination probability.

Priority call service on PCS networks

In a public switched telephone network (PSTN), the control information is exchanged among the network elements by signaling. The early telephone system used circuit associated signaling or inband signaling where the same transmission channel was shared by both signaling and user information (voice or data). Another signaling method is common channel signaling (CCS). Unlike the circuit associated signaling, CCS uses a separate out-of-band signaling network to carry signaling messages. CCS consists of supervisory functions, addressing, and providing call information. A CCS channel conveys messages to initiate and terminate calls, check on the status of some part of the network, and control the amount of traffic allowed. Signaling System No. 7 (SS7) is a CCS system developed to satisfy the telephone operating companies' requirements for an improvement to the earlier inband signaling systems. The advantages of CCS are listed.

Signaling System Number 7

Personal Number (PN) service or Follow-me service allows a user to access telecommunication services with any terminal (e.g., fixed telephones or mobile phones) in any location within the service area. To provide this feature, the PN user needs to manually register with a phone number every time he/she enters a new location. If the user forgets to register the new phone number, the incoming calls will be misrouted. To provide user-friendly follow-me service, this paper proposes an automatic follow-me service (AFS) approach that automatically updates the PN records in the Follow-me database. The significance of our approach is that AFS can be integrated with existing Follow-me databases to automate PIN services offered by different PSTN service providers. We show how AFS can be implemented by using the Voice over IP and Bluetooth technologies. Then, we propose an analytic model to investigate the performance of AFS. The analytic results are validated by simulation experiments. Our study suggests how to select polling frequency to optimize the AFS performance.

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Implementing automatic location update for follow-me database using VoIP and bluetooth technologies

Peer-to-peer communications is a major trend in wireless Internet. In a P2P system, the calling peer must identify the network address of the called peer before establishing a P2P connection. This article proposes iP2P, a hybrid P2P system for mobile devices. iP2P utilizes the short message service as the control protocol to identify the address of the called peer. Our approach provides an efficient identification mechanism without the requirement for the maintenance of a centralized registrar server in a hybrid P2P system. We also show how iP2P can integrate effectively with the existing network address translation traversal mechanisms to solve the private IP address issue.

https://ir.nctu.edu.tw:443/bitstream/11536/7454/1/000265487000005.pdf

Yi-Bing Lin

Papers

Location Tracking for WAVE Unicast Service

Priority call service on PCS networks

Signaling System Number 7

Implementing automatic location update for follow-me database using VoIP and bluetooth technologies

IP2P: a peer-to-peer system for mobile devices