The Effect of the Buffer Size in QoS for Multimedia and bursty Traffic: When an Upgrade Becomes a Downgrade

This work presents an analysis of the buffer features of an access router, especially the size, the impact on delay and the packet loss rate. In particular, we study how these features can affect the Quality of Service (QoS) of multimedia applications when generating traffic bursts in local networks. First, we show how in a typical SME (Small and Medium Enterprise) network in which several multimedia flows (VoIP, videoconferencing and video surveillance) share access, the upgrade of the bandwidth of the internal network may cause the appearance of a significant amount of packet loss caused by buffer overflow. Secondly, the study shows that the bursty nature of the traffic in some applications traffic (video surveillance) may impair their QoS and that of other services (VoIP and videoconferencing), especially when a certain number of bursts overlap. Various tests have been developed with the aim of characterizing the problems that may appear when network capacity is increased in these scenarios. In some cases, especially when applications generating bursty traffic are present, increasing the network speed may lead to a deterioration in the quality. It has been found that the cause of this quality degradation is buffer overflow, which depends on the bandwidth relationship between the access and the internal networks. Besides, it has been necessary to describe the packet loss distribution by means of a histogram since, although most of the communications present good QoS results, a few of them have worse outcomes. Finally, in order to complete the study we present the MOS results for VoIP calculated from the delay and packet loss rate

Unsticking the Wi-Fi Client:Smarter decisions using a software defined wireless solution

This paper presents a novel software-defined wireless network architecture that integrates coordination mechanisms to enhance the capabilities of a set of central managed Wi-Fi access points (APs). The global architecture is presented in detail, where the handoff mechanism is integrated with a set of active and passive monitoring tools and other functionalities, resulting in a solution that is able to provide smart functionalities using low-cost commercial APs. The framework includes a central controller that has all the information available, and is therefore able to make smart decisions about the assignment of clients to APs. This avoids the problem of the "sticky client" that remains connected to the original AP it is associated with, rather than moving to a nearby AP, which would be a better choice. Two different test scenarios are used to compare a proactive and a reactive handoff mechanism in realistic conditions, with different walking speeds. The results illustrate the advantage of the proactive handoff, as it is more scalable and allows a better integration with other functionalities such as load balancing. The delay incurred by the handoff between APs in different channels is measured with three wireless devices, using five values for the inter-beacon time, proving that fast and seamless handoffs are possible in the scenario. The paper shows that these advanced functionalities, usually available in proprietary solutions, can also be achieved using off-the-shelf equipment

Can a Wi-Fi WLAN Support a First Person Shooter?

<p>Jose Saldana, Juan Luis de la Cruz, Luis Sequeira, Julian Fernandez-Navajas, Jose Ruiz-Mas, "Can a Wi-Fi WLAN Support a First Person Shooter?," NetGames 2015, The 14th International Workshop on Network and Systems Support for Games Zagreb, Croatia, December 3-4, 2015.<br> ISBN: 978-1-5090-0067-8</p> <p>This work has been partially ?nanced by the EU H2020 Wi-5 project (Grant Agreement no: 644262), and European Social Fund in collaboration with the Government of Aragon.</p> <p><br> - The file "netgames_2015_in_proc.pdf" contains the paper published in the proceedings of the conference.</p> <p><br> - Support files and results:</p> <p><br> "captures" directory contains the ".pcap" captures made for both tests using Wireshark.</p> <p><br> "files" directory contains the filtered data from the captures or from the D-ITG raw output. The ".log" files are binary. They have been obtained with D-ITG (Distributed Internet Traffic Generator, http://traffic.comics.unina.it/software/ITG/)</p> <p>A. Botta, A. Dainotti, A. Pescapè, "A tool for the generation of realistic network workload for emerging networking scenarios", Computer Networks (Elsevier), 2012, Volume 56, Issue 15, pp 3531-3547. </p> <p> </p> <p>"src" directory contains the ".m" matlab script and functions used for processing the raw data obtained. MATLAB R2013 compatible. It also includes the ".fig" files, to be opened with the same version of MATLAB.</p> <p>NOTE: It is MANDATORY adding the directories to the MATLAB path.</p> <p>Juan Luis de la Cruz, September 2015</p> <p> </p> <p><em>Abstract</em>—In corporate and commercial environments, the deployment of a set of coordinated Wi-Fi APs is becoming a common solution to provide Internet coverage to moving users. In these scenarios, real-time services as online games can also be present. This paper presents a set of experiments developed in a test scenario where an end device moves between different APs while generating game traffic. A WLAN solution based on virtual APs is used, in order to make the handoffs transparent for Layer 3. The results show that it is possible to maintain an acceptable level of subjective quality during the handoff. At the same time, it is set clear that the fact of having a gamer in an AP could be taken into account by radio resource management algorithms, in order to provide a better quality.</p

Building a SDN Enterprise WLAN Based On Virtual APs

In this letter, the development and testing of an open enterprise Wi-Fi solution based on virtual access points (APs), managed by a central WLAN controller is presented. It allows seamless handovers between APs in different channels, maintaining the QoS of real-time services. The potential scalability issues associated to the beacon generation and channel assignment have been addressed. A battery of tests has been run in a real environment, and the results are reported in terms of packet loss and delay