80 research outputs found
Separating the Effect of Independent Interference Sources with Rayleigh Faded Signal Link: Outage Analysis and Applications
We show that, for independent interfering sources and a signal link with
exponentially distributed received power, the total probability of outage can
be decomposed as a simple expression of the outages from the individual
interfering sources. We give a mathematical proof of this result, and discuss
some immediate implications, showing how it results in important
simplifications to statistical outage analysis. We also discuss its application
to two active topics of study: spectrum sharing, and sum of interference powers
(e.g., lognormal) analysis.Comment: Submitted to IEEE Wireless Communications Letter
A QoS-based charging and resource allocation framework for next generation wireless networks
Wireless networks are evolving to include Internet access to interactive multimedia and video conferencing as well as traditional services such as voice, email and web access. These new applications can demand large amounts of network resources, such as bandwidth, to achieve the highest levels of quality (e.g. picture quality). In conjunction with this trend, charging and resource allocation systems must evolve to explicitly consider the trade-off between resource consumption and the Quality of Service (QoS) provided. This paper proposes a novel QoS-based charging and resource allocation framework. The framework allocates resources to customers based on their QoS perceptions and requirements, thereby charging fairly while improving resource allocation efficiency. It also allows the network operators to pursue a wide variety of policy options, including maximizing revenue or using auction or utility-based pricing. Copyrigh
A Prospective Analysis of Factors Associated with Decreased Physical Activity in Patients with Cirrhosis Undergoing Transplant Evaluation
BACKGROUND: Physical activity has been associated with improved recovery time after transplantation. Handgrip strength has been related to post-transplant outcomes.
AIM: To evaluate predictors of physical activity and grip strength in cirrhotic patients undergoing liver transplant evaluation.
METHODS: Single center, prospective analysis.
RESULTS: A hundred patients were evaluated (54% male, mean age 53 ± 9). Common etiologies of liver disease were non-alcoholic hepatitis (27%), hepatitis C (22%), and alcoholic liver disease (21%). Mean MELD score was 13.5. Forty one percent had a history of smoking. Ninety-three patients completed the International Physical Activity Questionnaire. The median total physical activity score of 33 MET-min/weeks. The mean total grip strength was 62.1 ± 22lb. Total grip strength was found to be an independent predictor of low-moderate physical activity (OR 4.7, 95% CI 1.4-16.2, p=0.038) and smoking was the only significant factor associated with reduced grip strength (OR 3.4, 95% CI 1.4-8, p=0.005).
CONCLUSIONS: End-Stage Liver Disease patients undergoing liver transplant evaluation have reduced total physical activity by IPAQ. Total Grip Strength was found to be a significant predictor of low-moderate physical activity in patients with cirrhosis. Smoking is a risk factor for reduced grip strength, an important indicator of muscle wasting in cirrhotics. This article is protected by copyright. All rights reserved
A competitive and dynamic pricing model for secondary users in infrastructure based networks
through Dynamic Spectrum Access (DSA) techniques provides a huge opportunity to the Wireless Service Providers (WSPs) for achieving efficient radio spectrum usage as well as gain additional profits. This paper presents a novel and dynamic SU pricing model for implementation by the WSPs at their Base Stations (BSs) based upon a BS-centric distributed framework, that allows the SU price to vary dynamically with the changing radio spectrum usage at the BS. Assuming high competition among regional WSPs, a non-cooperative competition structure is considered among the WSPs, where neither information nor resources are shared among the WSPs. A simple single cell scenario easily scalable to multiple cells achieving competitive yet dynamic SU pricing among the BSs of two WSPs, is presented in this paper. The final SU price is seen to depend on the spectrum utilization at the BS, the wireless channel, and the price charged by WSPs to their Primary Users (PUs). I
A distributed framework with a novel pricing model for enabling dynamic spectrum access for secondary users
the revenue from their investment in spectrum lease and infrastructure. In this paper, we present a simple model for enabling temporary wireless access for Secondary (unsubscribed) Users (SUs) along with Primary (subscribed) Users (PUs) to the same Base Station (BS), allowing SU access provided there is unutilized spectrum available at the BS after all the PUs have been served. We develop a distributed framework focusing on the efficient utilization of the spectrum leased by a WSP, in contrast to the centralized approach based on spectrum/spectrum information pooling prominent in literature. This paper includes a detailed signaling framework along with a novel Differentiated Service Code Point (DSCP) based mechanism for distinguishing PUs from SUs at the BS. A novel incentive based pricing model for SUs with an inherent property of resource management at the BS is proposed along with a criterion for autonomous network selection at the SU terminal and a SU terminal initiated price based handoff scheme. The distributed approach proposed in this paper, provides a framework for a single WSP to maximize its profits by allowing SU access, without the need for coordination with other WSPs through a centralized mediating entity. I
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