Defining user perception of distributed multimedia quality

This article presents the results of a study that explored the human side of the multimedia experience. We propose a model that assesses quality variation from three distinct levels: the network, the media and the content levels; and from two views: the technical and the user perspective. By facilitating parameter variation at each of the quality levels and from each of the perspectives, we were able to examine their impact on user quality perception. Results show that a significant reduction in frame rate does not proportionally reduce the user's understanding of the presentation independent of technical parameters, that multimedia content type significantly impacts user information assimilation, user level of enjoyment, and user perception of quality, and that the device display type impacts user information assimilation and user perception of quality. Finally, to ensure the transfer of information, low-level abstraction (network-level) parameters, such as delay and jitter, should be adapted; to maintain the user's level of enjoyment, high-level abstraction quality parameters (content-level), such as the appropriate use of display screens, should be adapted

Modeling and Analysis of an Energy-Efficient Mobility Management Scheme in IP-Based Wireless Networks†

An energy-efficient mobility management scheme in IP-based wireless networks is proposed to reduce the battery power consumption of mobile hosts (MHs). The proposed scheme manages seven MH states, including transmitting, receiving, attention/cell-connected, attention/paging area(PA)-connected, idle, off/attached, and detached states, to efficiently manage battery power, radio resources, and network load. We derive the stationary probabilities and steady state probabilities of the seven MH states for the proposed scheme in IP-based wireless networks in compact form. The effects of various input parameters on MH steady state probabilities and power consumption are investigated in the proposed scheme compared to the conventional scheme. Network costs such as cell updates, PA updates, binding-lifetime-based registrations, and paging messages are analyzed in the proposed and conventional schemes. The optimal values of PA size and registration interval are derived to minimize the network cost of the proposed scheme. The combined network and power costs are investigated for the proposed and conventional schemes. The results provide guidelines to select the proper system parameters in IP-based wireless networks

Scheduling support for multi-tier quality of service (QOS) in continuous media applications

In recent years, continuous video has emerged as an important element of the multimedia technology revolution. Applications such as digital libraries, distance learning, digital broadcasting and virtual conferencing promise to stretch the information technology to its limits. It is widely accepted that the problem of supporting continuous video (either live or stored) with Quality of Service (QoS) will decide the future course of these important applications, and hence that of information technology itself. A major challenge in this problem is providing tiered (involving multiple, disparate users) QoS while maximizing resources utilization, so that each of the applications can be economically offered. Providing QoS in an application server, such as a video server, involves admission control and scheduling. Admission control is a means of deciding whom to admit and what service to offer to maximize the available profit. Given any suitable admission control scheme, it is the task of scheduling to ensure that individual users are provided with acceptable QoS. In this thesis, we present a model and a scheduling algorithm which together provide tiered QoS in continuous video applications. The model captures application QoS requirements in a form suitable for scheduling, and the algorithm performs resource management, such that the individual applications are provided with acceptable QoS. The implementation of the algorithm in a prototype video server and its performance involving MPEG encoded video clips and multiple client streams will be presented. The results indicate that the algorithm, (1) ably meets the disparate QoS requirements of users; (2) simultaneously maximizes the server\u27s ability to support a large number of users, and (3) imposes very little implementation overhead. The proposed model and the algorithm are easily applicable to bundled continuous media, including voice and video. In addition, we present policies for supporting end-to-end deadlines in live video applications. We augment these policies by extending the proposed algorithm to provision multi-tier QoS in a video bridge that facilitates live video teleconferencing involving multiple streams. Simulation results indicate that our approach drastically improves the deadline miss rate and the supportable load for any given deadline miss rate

Random Packet Marking for Differentiated Services

RPM is a packet marking scheme designed to perform marking on the aggregate traffic belonging to a single Assured Forwarding class at the DS domain ingress node. Decision about drop precedence for each packet is based on the comparison between the arrival rate and two prescribed rates, committed information rate (CIR) and peak information rate (PIR), which are specified in the customer-ISP contract. Colors representing drop precedence are assigned randomly with the probability, which is a function of the arrival rate, CIR and PIR. RPM does not require maintaining any per-flow state. The percentage of packets marked as green, yellow and red for each flow is roughly proportional to the flow's share of bandwidth. Marking probability function can also be modified to allow different degree of conformance to the contract