Towards a virtualized Internet for computer networking assignments

By combining virtualization technologies, virtual private network techniques and parameterization of network scenarios it is possible to enhance a networking laboratory, typically carried out in university laboratory premises using equipment located there, by interconnecting it to virtual networks running on the students own personal computers. This paper describes some experiences applying this model to create hands-on assignments for a large group of students in computer networking education

A model to evaluate MBSFN and AL-FEC techniques in a multicast video streaming service

This procceding of: 10th International Conference on Wireless and Mobile Computing, Networking and Communications (WiMob). Took place 2014, October 08-10, in Lanarca (Chipre). The event Web site of http://conferences.computer.org/wimob2014/ .In a multicast video streaming service over a cellular network, the same content is sent to a mass audience using a common channel. However, users belonging to the same multicast channel perceive different characteristics of the radio channel. Moreover, in wireless environments, the radio interface introduces an important level of interference and noise, resulting in a high rate of transmission errors. Therefore, a protection of the information is needed at each receiver using Forward Error Correction (FEC) schemes, which allow the recovery of the lost packets sending redundancy together with the payload. FEC solutions can be used in combination with other techniques to overcome the existing limitations of the mobile network, in particular, the use of a single-frequency network to prevent the effect of destructive signal interference. This paper analyzes the performance of a video streaming service comparing different FEC schemes, Raptor and RaptorQ codes, where some system parameters can be tuned in a single-frecuency network.This work was supported in part by the Spanish Ministry of Economy and Competitiveness, National Plan for Scientific Research, Development and Technological Innovation (INNPACTO subprogram), LTExtreme project (IPT-2012-0525-430000).Publicad

Supporting handover between LTE video broadcasting and unicast streaming

The heterogeneity of the network poses new challenges on the paradigm of multimedia content distribution. Nowadays, different access technologies coexist in user terminals, so it is possible to improve the performance or avoid coverage problems by switching from one to another. This process is known as handover. In this work we have focused on vertical handover, which is the process of switching between different access technologies without losing connectivity. If a handover happens during a video streaming session, the session will need to adapt to the different channel conditions. This paper discusses the proposal of a new mechanism at the application level to support a handover between a unicast video streaming session and a video session based on LTE broadcasting

DASH Adaptation Algorithm Based on Adaptive Forgetting Factor Estimation

The wide adoption of multimedia service-capable mobile devices, the availability of better networks with higher bandwidths, and the availability of platforms offering digital content has led to an increasing popularity of multimedia streaming services. However, multimedia streaming services can be subject to different factors that affect the quality perceived by the users, such as service interruptions or quality oscillations due to changing network conditions, particularly in mobile networks. Dynamic Adaptive Streaming over HTTP (DASH), leverages the use of content-distribution networks and the capabilities of the multimedia devices to allow multimedia players to dynamically adapt the quality of the media streaming to the available bandwidth and the device characteristics. While many elements of DASH are standardized, the algorithms providing the dynamic adaptation of the streaming are not. The adaptation is often based on the estimation of the throughput or a buffer control mechanism. In this paper, we present a new throughput estimation adaptation algorithm based on a statistical method named Adaptive Forgetting Factor (AFF). Using this method, the adaptation logic is able to react appropriately to the different conditions of different types of networks. A set of experiments with different traffic profiles show that the proposed algorithm improves video quality performance in both wired and wireless environments

A virtualized platform for analyzing LTE broadcast services

Nowadays, users are demanding access to video content anytime and anywhere. LTE broadcast services and video streaming services can reduce the resources used by telecommunication companies to give access to video content and open up new business opportunities. In this context, testbeds and simulation tools can help in the analysis of the different parameters that need to be considered in the deployment of video services based on LTE. In this paper, we describe the design and implementation of an open-source virtualized platform that supports both LTE broadcast services and video streaming services. The testbed is being used both over real LTE networks and LTE network emulations to analyze the performance of video streaming services and to validate new proposals

Effects of once-weekly exenatide on cardiovascular outcomes in type 2 diabetes

BACKGROUND: The cardiovascular effects of adding once-weekly treatment with exenatide to usual care in patients with type 2 diabetes are unknown. METHODS: We randomly assigned patients with type 2 diabetes, with or without previous cardiovascular disease, to receive subcutaneous injections of extended-release exenatide at a dose of 2 mg or matching placebo once weekly. The primary composite outcome was the first occurrence of death from cardiovascular causes, nonfatal myocardial infarction, or nonfatal stroke. The coprimary hypotheses were that exenatide, administered once weekly, would be noninferior to placebo with respect to safety and superior to placebo with respect to efficacy. RESULTS: In all, 14,752 patients (of whom 10,782 [73.1%] had previous cardiovascular disease) were followed for a median of 3.2 years (interquartile range, 2.2 to 4.4). A primary composite outcome event occurred in 839 of 7356 patients (11.4%; 3.7 events per 100 person-years) in the exenatide group and in 905 of 7396 patients (12.2%; 4.0 events per 100 person-years) in the placebo group (hazard ratio, 0.91; 95% confidence interval [CI], 0.83 to 1.00), with the intention-to-treat analysis indicating that exenatide, administered once weekly, was noninferior to placebo with respect to safety (P<0.001 for noninferiority) but was not superior to placebo with respect to efficacy (P=0.06 for superiority). The rates of death from cardiovascular causes, fatal or nonfatal myocardial infarction, fatal or nonfatal stroke, hospitalization for heart failure, and hospitalization for acute coronary syndrome, and the incidence of acute pancreatitis, pancreatic cancer, medullary thyroid carcinoma, and serious adverse events did not differ significantly between the two groups. CONCLUSIONS: Among patients with type 2 diabetes with or without previous cardiovascular disease, the incidence of major adverse cardiovascular events did not differ significantly between patients who received exenatide and those who received placebo

Cardiovascular Efficacy and Safety of Bococizumab in High-Risk Patients

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