The Experts below are selected from a list of 306 Experts worldwide ranked by ideXlab platform

Saehwa Kim - One of the best experts on this subject based on the ideXlab platform.

  • Analyzing Event Chains of private branch exchange Systems Modeled with UML 2.0
    2010
    Co-Authors: Saehwa Kim
    Abstract:

    This paper analyzes event chains of private branch exchange (PBX) systems modeled with UML 2.0. UML 2.0 is a de-facto industrial standard as a real-time object-oriented modeling language. Our PBX UML 20 model adopts proxy design pattern and the event chains are derived from a bottom proxy layer that accepts exte rnal inputs. It is critical to correctly analyze event chains for a system to meet any real-time req uirements such as deadlines. This case study is to guide for designing real-time object-oriented models for any other kinds of complex realtime communications systems

  • Real-Time Object-Oriented Modeling of private branch exchange Systems
    2009
    Co-Authors: Saehwa Kim
    Abstract:

    This paper presents a real-time object-oriented model for private branch exchange (PBX) systems servicing cell phones. We selected OMG UML 2.0 as a specific real-time objectoriented modeling language. Our PBX model has high degree of dynamic structures and behavior while having a typical layered structure where the bottom proxy layer accepts external inputs. This case study can be used as a reference model for designing any other kinds of complex real-time communications systems.

  • EUC - Experimental Assessment of Scenario-Based Multithreading for Real-Time Object-Oriented Models: A Case Study with PBX Systems
    Embedded and Ubiquitous Computing, 2004
    Co-Authors: Saehwa Kim, Michael Buettner, Mark Hermeling, Seongsoo Hong
    Abstract:

    This paper presents an experimental evaluation of our scenario-based multithreading for real-time object-oriented models by the use of a case study of a private branch exchange (PBX) system. The PBX system was taken from the industry and exhibits a number of characteristics found in real-world applications such as a highly reconfigurable dynamic structure and a typical layered architecture. The objective of this experimental study is to assess the improvements to 1) the modeling environment in terms of ease of use for designers and 2) the performance of the resultant executables. We show how our toolset was applied to the PBX system to model scenarios, as well as to generate a scenario-based multithreaded executable. The study clearly shows that our method can handle large-scale, complex models and that scenario-based multithreading achieves the performance improvements for a real-world model.

Melichar Ondřej - One of the best experts on this subject based on the ideXlab platform.

  • Asterisk VoIP private branch exchange and its distributions
    Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2018
    Co-Authors: Melichar Ondřej
    Abstract:

    This master’s thesis delves into the possibilities of the open-source private branch exchange Asterisk, elaborates on its features and compares it with several other distros. The term SIP stack is explained here with the mention of two of its representatives. Further in the thesis, the security risks of the VoIP technology are explained, and specific attacks are described and then realized. As a part of the testing process, the possibilities of a custom module and its following implementation are explored, as well as the portability between the individual distros and its proper functioning

  • Asterisk VoIP private branch exchange and its distributions
    Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2018
    Co-Authors: Melichar Ondřej
    Abstract:

    Diplomová práce rozebírá možnosti open-source pobočkové ústředny Asterisk, popisuje její funkce a porovnává ji s několika jejími nástavbami. Je zde vysvětlen i pojem SIP stack a také jsou zde konkrétně uvedeni dva jeho zástupci. Dále jsou v práci vysvětlena bezpečnostní rizika technologie VoIP a jsou popsány a později realizovány jednotlivé možné útoky. V rámci testování je zkoumána i možnost vytvoření a realizace vlastního modulu, jeho následné implementace, přenositelnosti mezi jednotlivými nástavbami a jeho funkce.This master’s thesis delves into the possibilities of the open-source private branch exchange Asterisk, elaborates on its features and compares it with several other distros. The term SIP stack is explained here with the mention of two of its representatives. Further in the thesis, the security risks of the VoIP technology are explained, and specific attacks are described and then realized. As a part of the testing process, the possibilities of a custom module and its following implementation are explored, as well as the portability between the individual distros and its proper functioning.

  • Cross-platform performance testing of open source PBX FreeSWITCH
    Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2016
    Co-Authors: Melichar Ondřej
    Abstract:

    This bachelor’s thesis deals with the open source private branch exchange FreeSWITCH. The thesis describes the process of installation and consecutive configuration of the telephone system on various distributions of platforms Windows and Linux. Emphasis is placed on comparison of the performance between these systems and also the quality of calls as well as transcoding functionality. Specifically, the performance of the telephone system is tested while using the SIP protocol. Thesis also contains an introduction into the subject and a brief description of the FreeSWITCH architecture and its functions and capabilities

  • Cross-platform performance testing of open source PBX FreeSWITCH
    Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2016
    Co-Authors: Melichar Ondřej
    Abstract:

    Tato bakalářská práce se zabývá open source pobočkovou ústřednou FreeSWITCH. V práci je popsán postup instalace a následná konfigurace ústředny na rozdílných distribucích platforem Windows a Linux. Důraz je kladen zejména na srovnání výkonu mezi těmito systémy. Konkrétně je testován výkon ústředny za použití protokolu SIP a také kvalita hovoru či funkce transkódování. Dále také práce obsahuje úvod k problematice a stručný popis architektury a funkcí ústředny FreeSWITCH.This bachelor’s thesis deals with the open source private branch exchange FreeSWITCH. The thesis describes the process of installation and consecutive configuration of the telephone system on various distributions of platforms Windows and Linux. Emphasis is placed on comparison of the performance between these systems and also the quality of calls as well as transcoding functionality. Specifically, the performance of the telephone system is tested while using the SIP protocol. Thesis also contains an introduction into the subject and a brief description of the FreeSWITCH architecture and its functions and capabilities.

Morris Sloman - One of the best experts on this subject based on the ideXlab platform.

  • call management policy specification for the asterisk telephone private branch exchange
    IEEE International Workshop on Policies for Distributed Systems and Networks, 2007
    Co-Authors: G Konstantoulakis, Morris Sloman
    Abstract:

    Both users and administrators need a flexible and easy to use means of specifying call management policies to take advantage of the call handling functionality for selective forwarding, cost based outward call routing, recording calls etc. which are supported by a VoIP PBX. This paper presents a case study of a system for specifying and implementing policies, as well as detecting and resolving policy conflicts for the Asterisk PBX.

  • POLICY - Call Management Policy Specification for the Asterisk Telephone private branch exchange
    Eighth IEEE International Workshop on Policies for Distributed Systems and Networks (POLICY'07), 2007
    Co-Authors: G Konstantoulakis, Morris Sloman
    Abstract:

    Both users and administrators need a flexible and easy to use means of specifying call management policies to take advantage of the call handling functionality for selective forwarding, cost based outward call routing, recording calls etc. which are supported by a VoIP PBX. This paper presents a case study of a system for specifying and implementing policies, as well as detecting and resolving policy conflicts for the Asterisk PBX.

Yi-bing Lin - One of the best experts on this subject based on the ideXlab platform.

  • Implementation and performance evaluation for mobility management of a wireless PBX network
    IEEE Journal on Selected Areas in Communications, 2001
    Co-Authors: Phone Lin, Yi-bing Lin
    Abstract:

    As wireless technology advances, wireless products are integrated with enterprise networking to offer cordless terminal mobility. Most corporations have deployed wireless PBXs at the departmental level. However, the mobility management mechanism that integrates these facilities at the corporation level may not be available. This paper describes a mobility management mechanism for an enterprise wireless telephone network. We show how, to modify the call model of the private branch exchange (PBX) to accommodate mobility management for an enterprise network. Our design was implemented on a commercial PBX product called Jupiter. An analytical model is proposed to evaluate the performance of the implemented system. Our study shows that with a large number of WPBXs and long Internet message delays, the misrouting probability can be limited to within 1%. This performance result is considered satisfactory.

  • PBX based mobility manager for wireless local loop
    International Journal of Communication Systems, 2000
    Co-Authors: Yi-bing Lin
    Abstract:

    SUMMARY In a typical wireless local loop (WLL) system, a user can only access the wireless services at "xed locations. This paper proposes a private branch exchange (PBX) based mobility manager for WLL, which allows users to receive wireless service at any locations within the WLL service area. We show how the mobility manager can be implemented in a PBX environment where the base stations are connected to the PBX using standard line or trunk interfaces. The proposed mobility manager can be tailored to connect wireless system such as DECT or PACS. Copyright ( 2000 John Wiley & Sons, Ltd.

  • Resource Planning for Wireless PBX Systems
    International Journal of Wireless Information Networks, 1998
    Co-Authors: Wei-ru Lai, Yi-bing Lin
    Abstract:

    The wireless private branch exchange (PBX)system offers wireless telephone access in an officeenvironment. In a WPBX, several base stations areconnected to the PBX, and the PBX is connected to thepublic switched telephone network (PSTN). Since onlya small number of telephones are expected to be busy atthe same time, the capacity (number of the externallines) between the PBX and the PSTN is typically smaller than the sum of the capacities (radiochannels) of the individual base stations. It isimportant to determine the capacity of the WPBX tooptimize the performance of the system. This paperproposes an analytic model and a simulation model forWPBX resource planning. Based on the workload to theWPBX, our study provides the guidelines to determine thecapacities of the PBX and the base stations.

  • Resource planning for wireless PBX systems
    Proceedings of IEEE Enterprise Networking Mini-Conference (ENM-97) in conjunction with ICC 97, 1997
    Co-Authors: Wei-ru Lai, Yi-bing Lin
    Abstract:

    The wireless private branch exchange (PBX) system is considered as a wireless extension to enterprise networking. In a WPBX, several base stations are connected to the PBX, and the PBX is then connected to the public switched telephone network (PSTN). Since only a small number of lines are expected to be busy at the same time, the capacity (number of the external lines) between the PBX and the PSTN is typically smaller than the sum of the capacities (radio channels) of the individual base stations. It is important to determine the capacity of the WPBX to optimize the performance of the system. This paper proposes an analytic model for WPBX resource planning. Based on the workload to the WPBX, our model provides the guidelines to determine the capacities of the PBX and the base stations.

G Konstantoulakis - One of the best experts on this subject based on the ideXlab platform.

  • call management policy specification for the asterisk telephone private branch exchange
    IEEE International Workshop on Policies for Distributed Systems and Networks, 2007
    Co-Authors: G Konstantoulakis, Morris Sloman
    Abstract:

    Both users and administrators need a flexible and easy to use means of specifying call management policies to take advantage of the call handling functionality for selective forwarding, cost based outward call routing, recording calls etc. which are supported by a VoIP PBX. This paper presents a case study of a system for specifying and implementing policies, as well as detecting and resolving policy conflicts for the Asterisk PBX.

  • POLICY - Call Management Policy Specification for the Asterisk Telephone private branch exchange
    Eighth IEEE International Workshop on Policies for Distributed Systems and Networks (POLICY'07), 2007
    Co-Authors: G Konstantoulakis, Morris Sloman
    Abstract:

    Both users and administrators need a flexible and easy to use means of specifying call management policies to take advantage of the call handling functionality for selective forwarding, cost based outward call routing, recording calls etc. which are supported by a VoIP PBX. This paper presents a case study of a system for specifying and implementing policies, as well as detecting and resolving policy conflicts for the Asterisk PBX.