| 1. |
- Ammar, Doreid, et al.
(författare)
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Exploring the Usefulness of Machine Learning in the Context of WebRTC Performance Estimation
- 2019
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Ingår i: Proceedings - Conference on Local Computer Networks, LCN. - : IEEE Computer Society. - 9781728110288 ; , s. 406-413
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Konferensbidrag (refereegranskat)abstract
- We address the challenge faced by service providers in monitoring Quality of Experience (QoE) related metrics for WebRTC-based audiovisual communication services. By extracting features from various application-layer performance statistics, we explore the potential of using machine learning (ML) models to estimate perceivable quality impairments and to identify root causes. We argue that such performance-related data can be valuable and informative from a QoE assessment point of view, by allowing to identify the party/parties in a call that is/are experiencing quality impairments, and to trace the origins and causes of the problem. The paper includes case studies of multi-party videoconferencing that are established in a laboratory environment and exposed to various network disturbances and CPU limitations. Our results show that perceivable quality impairments in terms of video blockiness and audio distortions may be estimated with a high level of accuracy, thus proving the potential of exploiting ML models for automated QoE-driven monitoring and estimation of WebRTC performance. © 2019 IEEE.
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| 2. |
- Ammar, Doreid, et al.
(författare)
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Video QoE Killer and Performance Statistics in WebRTC-based Video Communication
- 2016
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Konferensbidrag (refereegranskat)abstract
- In this paper, we investigate session-related performance statistics of a Web-based Real-Time Communication (WebRTC) application called appear. in. We explore the characteristics of these statistics and explore how they may relate to users' Quality of Experience (QoE). More concretely, we have run a series of tests involving two parties and according to different test scenarios, and collected real-time session statistics by means of Google Chrome's WebRTC-internals tool. Despite the fact that the Chrome statistics have a number of limitations, our observations indicate that they are useful for QoE research when these limitations are known and carefully handled when performing post-processing analysis. The results from our initial tests show that a combination of performance indicators measured at the sender's and receiver's end may help to identify severe video freezes (being an important QoE killer) in the context of WebRTC-based video communication. In this paper the performance indicators used are significant drops in data rate, non-zero packet loss ratios, non-zero PLI values, and non-zero bucket delay.
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| 3. |
- Arkoulis, Stamatios, et al.
(författare)
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Misbehaviour Scenarios in Cognitive Radio Networks
- 2010
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Ingår i: Future Internet. - : Future Internet Editorial Office. - 1999-5903. ; 2:3-4, s. 212-237
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Forskningsöversikt (refereegranskat)abstract
- Recent advances in the fields of Cognitive Radio and the proliferation of open spectrum access promise that spectrum-agile wireless communication will be widespread in the near future, and will bring significant flexibility and potential utility improvements for end users. With spectrum efficiency being a key objective, most relevant research focuses on smart coexistence mechanisms. However, wireless nodes may behave selfishly and should be considered as rational autonomous entities. Selfishness, pure malice or even faulty equipment can lead to behavior that does not conform to sharing protocols and etiquette. Thus, there is a need to secure spectrum sharing mechanisms against attacks in the various phases of the sharing process. Identifying these attacks and possible countermeasures is the focus of this work.
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| 4. |
- Arlos, Patrik, et al.
(författare)
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A Distributed Passive Measurement Infrastructure
- 2005
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Konferensbidrag (refereegranskat)abstract
- In this paper we describe a distributed passive measurement infrastructure. Its goals are to reduce the cost and configuration effort per measurement. The infrastructure is scalable with regards to link speeds and measurement locations. A prototype is currently deployed at our university and a demo is online at http://inga.its.bth.se/projects/dpmi. The infrastructure differentiates between measurements and the analysis of measurements, this way the actual measurement equipment can focus on the practical issues of packet measurements. By using a modular approach the infrastructure can handle many different capturing devices. The infrastructure can also deal with the security and privacy aspects that might arise during measurements.
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| 5. |
- Arlos, Patrik, et al.
(författare)
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A Method to Estimate the Timestamp Accuracy of Measurement Hardware and Software Tools
- 2007
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Konferensbidrag (refereegranskat)abstract
- Due to the complex diversity of contemporary Internet applications, computer network measurements have gained considerable interest during the recent years. Since they supply network research, development and operations with data important for network traffic modelling, performance and trend analysis etc., the quality of these measurements affect the results of these activities and thus the perception of the network and its services. One major source of error is the timestamp accuracy obtained from measurement hardware and software. On this background, we present a method that can estimate the timestamp accuracy obtained from measurement hardware and software. The method is used to evaluate the timestamp accuracy of some commonly used measurement hardware and software. Results are presented for the Agilent J6800/J6830A measurement system, the Endace DAG 3.5E card, the Packet Capture Library (PCAP) either with PF_RING or Memory Mapping, and a RAW socket using either the kernel PDU timestamp (ioctl) or the CPU counter (TSC) to obtain timestamps.
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| 6. |
- Arlos, Patrik, et al.
(författare)
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Accuracy Evaluation of Ping and J-OWAMP
- 2006
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Konferensbidrag (refereegranskat)abstract
- Due to the complex diversity of contemporary Internet services, computer network measurements have gained considerable interest during the recent years. Computer network measurements supply network research, development and operations with data important for network traffic modelling, performance and trend analysis etc. Hence, the quality of these measurements affects the results of these activities and thus the perception of the network and its services. Active measurements are performed by injecting traffic into a network and observing the treatment that this traffic receives. Usually, active measurements are perfomed by writing special applications that act at sender and receiver. These applications are usually executed as user processes. This causes some concern since this can have serious implications on the obtained results, as they are affected by the scheduling mechanisms in the operating system. In this paper, we evaluate the accuracy of two active measurement tools, ping and J-OWAMP, by using high accuracy passive measurements. Our results show that ping is quite accurate, to 0.1~ms for Linux and 1~ms for Windows~XP, while J-OWAMP has a discrepancy of 25~ms plus serious time synchronization problems.
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| 7. |
- Arlos, Patrik, et al.
(författare)
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Evaluation of Protocol Treatment in 3G Networks
- 2011
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Konferensbidrag (refereegranskat)abstract
- In this work, we present a systematic study of how the traffic of different transport protocols (UDP, TCP and ICMP) is treated, in three operational Swedish 3G networks. This is done by studying the impact that protocol and packet size have on the one-way-delay (OWD) across the networks. We do this using a special method that allows us to calculate the exact OWD, without having to face the usual clock synchronization problems that are normally associated with OWD calculations. From our results we see that all three protocols are treated similarly by all three operators, when we consider packet sizes that are smaller than 250~bytes and larger than 1100~bytes. We also show that larger packet sizes are given preferential treatment, with both smaller median OWD as well as a smaller standard deviation. It is also clear that, ICMP is given a better performance compared to TCP and UDP.
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| 8. |
- Arlos, Patrik, et al.
(författare)
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Influence of the Packet Size on the One-Way Delay in 3G Networks
- 2010
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Konferensbidrag (refereegranskat)abstract
- We currently observe a rising interest in mobile broadband, which users expect to perform in a similar way as its fixed counterpart. On the other hand, the capacity allocation process on mobile access links is far less transparent to the user; still, its properties need to be known in order to minimize the impact of the network on application performance. This paper investigates the impact of the packet size on the minimal one-way delay for the uplink in third-generation mobile networks. For interactive and real-time applications such as VoIP, one-way delays are of major importance for user perception; however, they are challenging to measure due to their sensitivity to clock synchronization. Therefore, the paper applies a robust and innovative method to assure the quality of these measurements. Results from measurements from several Swedish mobile operators show that applications can gain significantly in terms of one-way delay from choosing optimal packet sizes. We show that, in certain cases, an increased packet size can improve the one-way delay performance at best by several hundred milliseconds.
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| 9. |
- Arlos, Patrik, et al.
(författare)
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Influence of the Packet Size on the One-Way Delay on the Down-link in 3G Networks
- 2010
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Konferensbidrag (refereegranskat)abstract
- The number of mobile broadband users is increasing. Furthermore, these users have high expectations into the capabilities of mobile broadband, comparable to those in fixed networks. On the other hand, the capacity assignment process on mobile access links is far from transparent to the user, and its properties need to be known in order to minimize the impact of the network on application performance. This paper investigates the impact of the packet size on the characteristics of the one-way delay for the down-link in third-generation mobile networks. For interactive and real-time applications such as VoIP, one-way delays are of major importance for user perception; however, they are challenging to measure due to their sensitivity to clock synchronization. Therefore, the paper applies a robust and innovative method to assure the quality of these measurements. We focus on the down-link as this is still the link that carries the most traffic to the user, and the quality of it will have a significant impact on all IP-based services. Results from measurements from several Swedish mobile operators reveal the possibility to partly control one-way delay and its variability by choosing appropriate packet sizes. In particular, packet sizes leading to the use of WCDMA entail significant but hardly varying one-way delays. On the other hand, we also show that HDSPA networks can deliver large amounts of data at rather high speed, but the cost is a huge variability in the one-way delay.
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| 10. |
- Aziz, Hussein Muzahim, et al.
(författare)
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Compressing Video Based on Region of Interest
- 2013
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Konferensbidrag (refereegranskat)abstract
- Real-time video streaming suffer from bandwidth limitation that are unable to handle the high amount of video data. To reduce the amount of data to be streamed, we propose an adaptive technique to crop the important part of the video frames, and drop the part that are outside the important part; this part is called the Region of Interest (ROI). The Sum of Absolute Differences (SAD) is computed to the consecutive video frames on the server side to identify and extract the ROI. The ROI are extracted from the frames that are between reference frames based on three scenarios. The scenarios been designed to position the reference frames in the video frames sequence. Linear interpolation is performed from the reference frames to reconstruct the part that are outside the ROI on the mobile side. We evaluate the proposed approach for the three scenarios by looking at the size of the compressed videos and measure the quality of the videos by using the Mean Opinion Score (MOS). The results show that our technique significantly reduces the amount of data to be streamed over wireless networks with acceptable video quality are provided to the mobile viewers.
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