EPON is an emerging local subscriber access network that consists of low-cost point-to-multipoint fiber infrastructure with Ethernet. Because several ONUs use a single shared medium in EPON, it is important to control upstream traffic. An EPON allocates upstream bandwidth to ONUs using a request/permit mechanism. In this paper, we proposed a new DBA algorithm supporting multiple priority queues and evaluated its performance. The key performance of proposed algorithm through simulation is described and the simulation results show the algorithm is fair and feasible.
EPON is an emerging local subscriber access network that consists of low-cost point-to-multipoint fiber infrastructure with Ethernet. Because several ONUs use a single shared medium in EPON, it is important to control upstream traffic. An EPON allocates upstream bandwidth to ONUs using a request/permit mechanism. In this paper, we proposed a new DBA algorithm supporting multiple priority queues and evaluated its performance. From the simulation result, we have confirmed that our proposed DBA algorithm can reduce the average queue length in comparison to that of ETRI's DBA algorithm.
Most rural clinics across the country have limited facilities to provide state-of-the-art medical services. The availability of enabling technologies, such as telecommunication networks, multimedia workstations, and telemedicine systems which provide medical services to patients without requiring them to travel from their cities represents a great step in patient care. In previous work, we have developed a distributed software for remote consultation and diagnosis (RCD) in a Global PACS environment over the Internet. The RCD system has been designed and tested on DEC and SUN workstations. In this paper, we present a Unix-PC based platform to implement the RCD over a standard telephone line and Serial Line Internet Protocol (SLIP). The Unix-PC platform offers an inexpensive option for telemedicine workstations in rural clinics, where no Internet is available. If an Internet connection is available at the rural clinic, full RCD multimedia services are possible. The Unix-PC platform has been developed by using Linux, a Unix-like operating system available from several public sites over the Internet. We call the system PC-PACS. The PC-PACS workstation has been tested from different rural sites by connecting the Unix-PC system to the Internet through SLIP. Once the system is connected, RCD sessions have been performed between the Unix- PC platform and SUN workstations. The tests have included diagnosis on radiology and pathology images. A separate telephone line for voice communications during the RCD session is required. This paper describes performance tests for the PC-based workstation and the RCD system over SLIP and Ethernet interfaces. Results show acceptable performance of the workstation and the RCD software.
In this paper, we present our approach to developing global picture archiving and communication system (PACS) remote consultation and diagnosis (RCD) application using the Open Software Foundation (OSF) Distributed Computing Environment (DCE) services and toolkits. The current RCD system now uses programming services similar to those offered by OSF DCE, the Cell Directory Service, the Distributed Time Service, the Security Service, the RPC Facility, and the Threads Facility. In this research we have formally applied OSF DCE services to the Global PACS RCD software. The use of OSF DCE services for Global PACS enables us to develop a robust distributed structure and new user services which feature reliability and scalability for Global PACS environments.
KEYWORDS: Picture Archiving and Communication System, Internet, Video, Image processing, Imaging systems, Databases, Telecommunications, Medical imaging, Signal processing, Surgery
A Global PACS is a medical imaging system which enables the doctors to capture, archive, and retrieve medical images over wide area networks. In previous work, we have developed a distributed software for remote consultation and diagnosis in a Global PACS environment over the Internet or NSFNET. The doctors are able to interactively perform a remote consultation with basic image annotation commands. In this paper, we present a new mechanism for adding voice to this scenario and performing synchronization of voice and image annotation in a remote consultation and diagnosis session.
In this paper, we present our approach to developing Global Picture Archiving and Communication System (GPACS) applications using the Open Software Foundation (OSF) Distributed Computing Environment (DCE) services and toolkits. The OSF DCE services include remote procedure calls, naming service, threads service, time service, file management services, and security service. Several OSF DCE toolkits are currently available from computer and software vendors. Designing distributed Global PACS applications using the OSF DCE approach will feature an open architecture, heterogeneity, and technology independence for GPACS remote consultation and diagnosis applications, including synchronized image annotation, and system privacy and security. The applications can communicate through various transport services and communications networks in a Global PACS environment. The use of OSF DCE services for Global PACS will enable us to develop a robust distributed structure and new user services which feature reliability and scalability for Global PACS environments.
A Global PACS is a national network which interconnects several PACS networks at medical and hospital complexes using a national backbone network. A Global PACS environment enables new and beneficial operations between radiologists and physicians, when they are located in different geographical locations. One operation allows the radiologist to view the same image folder at both Local and Remote sites so that a diagnosis can be performed. The paper describes the user interface, database management, and network communication software which has been developed in the Computer Engineering Research Laboratory and Radiology Research Laboratory. Specifically, a design for a file management system in a distributed environment is presented. In the remote consultation and diagnosis operation, a set of images is requested from the database archive system and sent to the Local and Remote workstation sites on the Global PACS network. Viewing the same images, the radiologists use pointing overlay commands, or frames to point out features on the images. Each workstation transfers these frames, to the other workstation, so that an interactive session for diagnosis takes place. In this phase, we use fixed frames and variable size frames, used to outline an object. The data pockets for these frames traverses the national backbone in real-time. We accomplish this feature by using TCP/IP protocol sockets for communications. The remote consultation and diagnosis operation has been tested in real-time between the University Medical Center and the Bowman Gray School of Medicine at Wake Forest University, over the Internet. In this paper, we show the feasibility of the operation in a Global PACS environment. Future improvements to the system will include real-time voice and interactive compressed video scenarios.
A global PACS is a national network which interconnects several PACS networks at medical and hospital complexes using a national backbone network. A global PACS environment enables new and beneficial operations between radiologists and physicians, when they are located in different geographical locations. This paper presents three user scenarios which enable remote consultation and diagnosis between radiologists at a local PACS site and a remote PACS site. One scenario, called remote consultation, allows the radiologist to view the same image folder at both local and remote sites so that a diagnosis can be performed. We present performance date based on tests between these two sites and show the feasibility of the operation in a global PACS environment. Future improvements to the system will include real- time voice and interactive compressed video scenarios. This work is sponsored by the National Science Foundation and Toshiba Medical Systems Division.
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