Kevin M. McNeill

Arizona Telemedicine Program: implementing a statewide health care network.

The Arizona Telemedicine Program was established in July 1996 by the Arizona state legislature. The organizational center for the program is the Arizona Health Sciences Center in Tucson. Key goals for the program include increased access to specialty services for rural, underserved populations; development of cost-effective telemedicine services; and expansion of opportunities for education of health professionals in rural areas. The program provides several levels of services based on both store-and-forward and real-time interactive applications. The telecommunication infrastructures is provided by two methods: The first is a private asynchronous transfer mode network established and operated by program personnel. The second is dial-up access via the public switched telephone network. After an extensive period of organization and vendor evaluations, most of the private network was implemented between June and December 1997. This paper describes experiences establishing the asynchronous transfer mode network.

An overview of network-aware applications for mobile multimedia delivery

Network-aware applications are a promising new concept in which applications are aware of network conditions and thus can adapt to the varying environment to achieve acceptable and predictable performance. This paper reviews the current research on network-aware applications, with a focus on their appliance on mobile multimedia applications. First, different frameworks or architectures of network-aware applications are introduced. Research issues and activities are then discussed in detail from two basic aspects of network-aware applications: network awareness and network adaptation. After the discussion about network-aware applications in general network environments, special problems and requirements of mobile multimedia applications are summarized, and different network-aware application approaches for mobile multimedia delivery are compared with respect to these requirements. Finally, we provide some suggestions to network-aware mobile multimedia application developers and identify current challenges in this area.

Evaluation of the ACR-NEMA standard for communications in digital radiology

An implementation and evaluation of a prototype multivendor communications system which complies with the American College of Radiology (ACR) and the National Electrical Manufacturers Association (NEMA) standard for communications in digital radiology is discussed. The system allows communications between interfaces from different manufacturers within a networked environment. The implementation includes network software compatible with the International Standards Organizations Open Systems Interconnect standard. The experience of the implementation effort and the evaluation of the system provide the basis for a critique of the ACR-NEMA standard. It is concluded that the ACR-NEMA standard is not well suited for application to the networked environment of picture archiving and communications systems. Two possible solutions are recommended for this problem. The first is a major revision of the existing standard. The second is the development of a family of network communications standards for digital radiology.

High-volume teleradiology service: focus on radiologist satisfaction.

In 1998 we surveyed our radiologists on teleradiology satisfaction. Results were generally positive. In 2002 we experienced a sevenfold case increase in teleradiology volume. The present study surveyed the radiologists again. The hypothesis was that, with increased case volume and radiologist experience with the system, ratings would increase. Image quality was excellent/good, although plain film and ultra sound (US) had more fair/poor ratings. Monitors, navigation, image processing, and Web-based reporting were rated as excellent/good. The voice-recognition system was rated poorly. Diagnostic confidence was about the same as for film. Exceptions were magnetic resonance imaging (MRI) US, and plain film. Up to 10% of cases are unreadable because of poor image quality, not enough images, or inadequate patient history. Overall, the radiologists are satisfied, although some improvements can be made.

An Adaptive Jitter Buffer Play-Out Scheme to Improve VoIP Quality in Wireless Networks

Extension of the infrastructure supporting network-centric operations to the tactical edge relies primarily on wireless communications. The nature of these communications ensures that the channel will vary dramatically due to environmental and propagation effects, as well as potential interferers. Tactical operations introduce additional impairment due to mobility. With convergence to Internet protocol (IP) centric networking, voice communications at the tactical edge will be increasingly dependent on voice over IP (VoIP). In a packet-based protocol such as IP, two critical factors affecting latency sensitive applications such as VoIP are end-to-end delay and packet loss. Making a tradeoff between these two factors is of prime consideration in designing the jitter buffer playout scheme. Since voice packets are delayed in the network randomly, the jitter buffer is required to maintain consistently spaced playout of voice samples. A deep buffer protects against packet loss due to late arrival of packets. However, a deep buffer introduces mouth-to-ear delay that ultimately degrades the perceived voice quality. We describe an algorithm for dynamically estimating network delay using time series models. This enables the VoIP application to manage the jitter buffer to maintain a minimum playout buffer, while keeping the packet loss rate above a minimal threshold to maintain consistent voice quality. Our proposed algorithm limits sensitivity to short-term delay jitter and is very reactive to bursty network traffic. Simulation results show an improvement of 11% to 15% using metrics based on the subjective ITU E-model (R-factor) when compared against currently used playout methods. The improvement gain from the proposed method may be of particular significance for the challenges of supporting bursty dynamic changing wireless communication channel.

Hardware and software-in-the-loop techniques using the OPNET modeling tool for JTRS developmental testing

This paper describes the continuation of the hardware-in-the-loop (HITL) project started by the U.S. Army Information Systems Engineering Command (ISEC) in FY 2000. The paper describes the design and implementation of a hardware-in-the-loop (HITL) and software-in-the-loop (SITL) methods using the discrete-event modeling package, OPNET modeler. The project objective is to develop a capability to evaluate performance of large and complex army communications networks and network-centric systems by combining virtual models with real networks. HITL and SITL methods have been developed that allow virtual models to communicate real IP traffic with real applications in real networks. A generic reference model for HITL and SITL use has been proposed for use in DoD systems. This paper proposes use of the HITL and SITL techniques for developmental testing for JTRS Cluster 1. Potential DoD programs that require developmental testing may be JTRS clusters, WIN-T, and FCS. The U.S. Army Information Systems Engineering Command (ISEC), Technology Integration Center (TIC), Fort Huachuca, AZ, and BAE SYSTEMS, CNIR, Reston, VA sponsored this research in the Computer Engineering Research Laboratory (CERL) at the University of Arizona.

Design of Low-Sidelobe Linear Arrays With High Aperture Efficiency and Interference Nulls

This letter focuses on the design of linear array antennas having distributions with low sidelobes and aperture efficiency constraints on the specified peak amplitude and effective radiated voltage. An adaptive parameter genetic algorithm is used to explore how interference nulls impact antenna performance when low sidelobes and aperture efficiency are also required.

Patterns of use and satisfaction with a university-based teleradiology system

The Radiology Department at the University of Arizona has been operating a teleradiology program for almost 2 years. The goal of this project was to characterize the types of cases reviewed, to assess radiologists’ satisfaction with the program, and to examine case turnaround times. On average, about 50 teleradiology cases are interpreted each month. Computed tomography (CT) cases are the most common type of case, constituting 65% of the total case volume. Average turnaround time (to generate a “wet read” once a case is received) is about 1.3 hours. Image quality was rated as generally good to excellent, and the user interface as generally good. Radiologists’ confidence in their diagnostic decisions is about the same as reading films in the clinical environment. The most common reason for not being able to read teleradiology images is poor image quality, followed by lack of clinical history and not enough images.

A PMP-Friendly MANET Networking Approach for WiMAX/IEEE 802.16/sup TM/

WiMAX Forum certifiedtrade broadband wireless equipment is now available to military users and consumers alike. This equipment is based on the IEEE 802.16/sup TM/-2004 and IEEE 802.16e/sup TM/-2005 standards. This commercial off-the-shelf (COTS) equipment promises to greatly reduce the cost of broadband wireless access and lead to cost-effective solutions for the military. However, existing COTS equipment has performance deficiencies when considered for military and national security operational scenarios. One deficiency is the lack of mobile ad-hoc and mesh networking capabilities compatible with the currently fielded point-to-multipoint (PMP) mode. While the IEEE 802.16-2004 standard includes a mesh capability, it does not interoperate with the PMP mode, and is not being considered for implementation. The IEEE 802.16e-2005 amendment addresses subscriber mobility but does nothing to address the ad-hoc and mesh shortcomings in WiMAX and IEEE 802.16-2004. This paper reviews some current and planned capabilities of WiMAX, and recommends extensions to the IEEE 802.16 standard to facilitate mobile ad-hoc and mesh networking protocols that can interoperate with planned WiMAX deployments

Development Of A High Resolution X-Ray Imaging Device For Use In Coronary Angiography

This paper describes a high resolution x-ray imaging device which is being developed through NIH sponsorship by the University of Arizona. It consists of an external modular x-ray sensor, a proximity focussed image intensifier and six CCDs coupled to the output of the image intensifier via six fiber optic tapers. The tapers are joined at the large ends to form a coplanar fiber optic taper assembly. The spatial resolution is expected to be determined by the external sensor up to the Nyquist frequency of the CCD which is (after magnification by the tapers) 3.9 1p/mm. The intended application is coronary angiography.