Florin Dobrian, V. Sekar, Asad Awan, I. Stoica, D. Joseph, Aditya Ganjam, Jibin Zhan, Hui Zhang
{"title":"Understanding the impact of video quality on user engagement","authors":"Florin Dobrian, V. Sekar, Asad Awan, I. Stoica, D. Joseph, Aditya Ganjam, Jibin Zhan, Hui Zhang","doi":"10.1145/2018436.2018478","DOIUrl":"https://doi.org/10.1145/2018436.2018478","url":null,"abstract":"As the distribution of the video over the Internet becomes main- stream and its consumption moves from the computer to the TV screen, user expectation for high quality is constantly increasing. In this context, it is crucial for content providers to understand if and how video quality affects user engagement and how to best invest their resources to optimize video quality. This paper is a first step towards addressing these questions. We use a unique dataset that spans different content types, including short video on demand (VoD), long VoD, and live content from popular video con- tent providers. Using client-side instrumentation, we measure quality metrics such as the join time, buffering ratio, average bitrate, rendering quality, and rate of buffering events. We quantify user engagement both at a per-video (or view) level and a per-user (or viewer) level. In particular, we find that the percentage of time spent in buffering (buffering ratio) has the largest impact on the user engagement across all types of content. However, the magnitude of this impact depends on the content type, with live content being the most impacted. For example, a 1% increase in buffering ratio can reduce user engagement by more than three minutes for a 90-minute live video event. We also see that the average bitrate plays a significantly more important role in the case of live content than VoD content.","PeriodicalId":350796,"journal":{"name":"Proceedings of the ACM SIGCOMM 2011 conference","volume":"46 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114130474","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Strider: automatic rate adaptation and collision handling","authors":"Aditya Gudipati, S. Katti","doi":"10.1145/2018436.2018455","DOIUrl":"https://doi.org/10.1145/2018436.2018455","url":null,"abstract":"This paper presents the design, implementation and evaluation of Strider, a system that automatically achieves almost the optimal rate adaptation without incurring any overhead. The key component in Strider is a novel code that has two important properties: it is rateless and collision-resilient. First, in time-varying wireless channels, Strider's rateless code allows a sender to effectively achieve almost the optimal bitrate, without knowing how the channel state varies. Second, Strider's collision-resilient code allows a receiver to decode both packets from collisions, and achieves the same throughput as the collision-free scheduler. We show via theoretical analysis that Strider achieves Shannon capacity for Gaussian channels, and our empirical evaluation shows that Strider outperforms SoftRate, a state of the art rate adaptation technique by 70% in mobile scenarios and by upto 2.8× in contention scenarios.","PeriodicalId":350796,"journal":{"name":"Proceedings of the ACM SIGCOMM 2011 conference","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132185736","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"A content propagation metric for efficient content distribution","authors":"Ryan S. Peterson, B. Wong, E. G. Sirer","doi":"10.1145/2018436.2018474","DOIUrl":"https://doi.org/10.1145/2018436.2018474","url":null,"abstract":"Efficient content distribution in large networks comprising datacenters, end hosts, and distributed in-network caches is a difficult problem. Existing systems rely on mechanisms and metrics that fail to effectively utilize all available sources of bandwidth in the network. This paper presents a novel metric, called the Content Propagation Metric (CPM), for quantitatively evaluating the marginal benefit of available bandwidth to competing consumers, enabling efficient utilization of the bandwidth resource. The metric is simple to implement, imposes only a modest overhead, and can be retrofitted easily into existing content distribution systems. We have designed and implemented a high-performance content distribution system, called V-Formation, based on the CPM. The CPM guides V-Formation toward a global allocation of bandwidth that maximizes the aggregate download bandwidth of consumers. Results from a PlanetLab deployment and extensive simulations show that V-Formation achieves high aggregate bandwidth and that the CPM enables hosts to converge quickly on a stable allocation of resources in a wide range of deployment scenarios.","PeriodicalId":350796,"journal":{"name":"Proceedings of the ACM SIGCOMM 2011 conference","volume":"87 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133759442","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
D. López-Pérez, Xiaoli Chu, A. Vasilakos, H. Claussen
{"title":"Minimising cell transmit power: towards self-organized resource allocation in OFDMA femtocells","authors":"D. López-Pérez, Xiaoli Chu, A. Vasilakos, H. Claussen","doi":"10.1145/2018436.2018494","DOIUrl":"https://doi.org/10.1145/2018436.2018494","url":null,"abstract":"With the introduction of femtocells, cellular networks are moving from the conventional centralised architecture to a distributed one, where each network cell should make its own radio resource management decisions, while providing inter-cell interference mitigation. However, realising this distributed cellular network architecture is not a trivial task. In this paper, we first introduce a simple self-organisation rule under which a distributed cellular network is able to converge into an efficient resource allocation pattern, then propose a novel resource allocation model taking realistic resource allocation constraints into account, and finally evaluate the performance of the proposed self-organisation rule and resource allocation model using system-level simulations.","PeriodicalId":350796,"journal":{"name":"Proceedings of the ACM SIGCOMM 2011 conference","volume":"210 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132856208","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Towards scalable and realistic node models for network simulators","authors":"Stein Kristiansen, T. Plagemann, V. Goebel","doi":"10.1145/2018436.2018498","DOIUrl":"https://doi.org/10.1145/2018436.2018498","url":null,"abstract":"Network simulators typically do not include node models. Our studies show that in networks such as mobile networks, the impact of nodes on performance can be significant. Existing techniques to simulate nodes' are not scalable for network simulations, and require a too large modelling effort to be feasible for network research. In this paper, we propose to capture flexible per-protocol performance profiles from real, running systems using instrumentation and traffic benchmarking techniques. By using the obtained profiles as input into an extended scheduler simulator, the behaviour of the node can be accurately reproduced. Since the processing overhead is represented statistically, we preserve scalability and a low modelling overhead.","PeriodicalId":350796,"journal":{"name":"Proceedings of the ACM SIGCOMM 2011 conference","volume":"41 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132918659","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Eduard Goma Llairo, M. Canini, Alberto López Toledo, Nikolaos Laoutaris, Dejan Kostic, P. Rodriguez, R. Stanojevic, Pablo Yagüe Valentin
{"title":"Insomnia in the access: or how to curb access network related energy consumption","authors":"Eduard Goma Llairo, M. Canini, Alberto López Toledo, Nikolaos Laoutaris, Dejan Kostic, P. Rodriguez, R. Stanojevic, Pablo Yagüe Valentin","doi":"10.1145/2018436.2018475","DOIUrl":"https://doi.org/10.1145/2018436.2018475","url":null,"abstract":"Access networks include modems, home gateways, and DSL Access Multiplexers (DSLAMs), and are responsible for 70-80% of total network-based energy consumption. In this paper, we take an in-depth look at the problem of greening access networks, identify root problems, and propose practical solutions for their user- and ISP-parts. On the user side, the combination of continuous light traffic and lack of alternative paths condemns gateways to being powered most of the time despite having Sleep-on-Idle (SoI) capabilities. To address this, we introduce Broadband Hitch-Hiking (BH2), that takes advantage of the overlap of wireless networks to aggregate user traffic in as few gateways as possible. In current urban settings BH2 can power off 65-90% of gateways. Powering off gateways permits the remaining ones to synchronize at higher speeds due to reduced crosstalk from having fewer active lines. Our tests reveal speedup up to 25%. On the ISP side, we propose introducing simple inexpensive switches at the distribution frame for batching active lines to a subset of cards letting the remaining ones sleep. Overall, our results show an 80% energy savings margin in access networks. The combination of B2 and switching gets close to this margin, saving 66% on average.","PeriodicalId":350796,"journal":{"name":"Proceedings of the ACM SIGCOMM 2011 conference","volume":"205 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114148850","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Automatic inference of movements from contact histories","authors":"Pengcheng Wang, Zhaoyu Gao, Xinhui Xu, Yujiao Zhou, Haojin Zhu, Kenny Q. Zhu","doi":"10.1145/2018436.2018481","DOIUrl":"https://doi.org/10.1145/2018436.2018481","url":null,"abstract":"This paper introduces a new security problem in which individuals movement traces (in terms of accurate routes) can be inferred from just a series of mutual contact records and the map of the area in which they roam around. Such contact records may be obtained through the bluetooth communication on mobile phones. We present an approach that solve the trace inference problem in reasonable time, and analyze some properties of the inference algorithm.","PeriodicalId":350796,"journal":{"name":"Proceedings of the ACM SIGCOMM 2011 conference","volume":"53 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116264071","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"A protocol for disaster data evacuation","authors":"T. Rabl, F. Stegmaier, M. Döller, The Thong Vang","doi":"10.1145/2018436.2018514","DOIUrl":"https://doi.org/10.1145/2018436.2018514","url":null,"abstract":"Data is the basis of the modern information society. However, recent natural catastrophes have shown that it is not possible to definitively secure a data storage location. Even if the storage location is not destroyed itself the access may quickly become impossible, due to the breakdown of connections or power supply. However, this rarely happens without any warning. While floods have hours or days of warning time, tsunamis usually leave only minutes for reaction and for earthquakes there are only seconds. In such situations, timely evacuation of important data is the key challenge. Consequently, the focus lies on minimizing the time to move away all data from the storage location whereas the actual time to arrival remains less (but still) important. This demonstration presents the dynamic fast send protocol (DFSP), a new bulk data transfer protocol. It employs striping to dynamic intermediate nodes in order to minimize sending time and to utilize the sender's resources to a high extent.","PeriodicalId":350796,"journal":{"name":"Proceedings of the ACM SIGCOMM 2011 conference","volume":"77 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124435781","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Designing a testbed for large-scale distributed systems","authors":"Christof Leng, Max Lehn, R. Rehner, A. Buchmann","doi":"10.1145/2018436.2018488","DOIUrl":"https://doi.org/10.1145/2018436.2018488","url":null,"abstract":"Different evaluation methods for distributed systems like prototyping, simulation and emulation have different tradeoffs. We present a testbed for Internet applications that supports real-network prototypes and multiple simulators with unchanged application code. To ensure maximum portability between runtimes, a compact but flexible system interface is defined.","PeriodicalId":350796,"journal":{"name":"Proceedings of the ACM SIGCOMM 2011 conference","volume":"108 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126980092","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"DOF: a local wireless information plane","authors":"S. Hong, S. Katti","doi":"10.1145/2018436.2018463","DOIUrl":"https://doi.org/10.1145/2018436.2018463","url":null,"abstract":"The ability to detect what unlicensed radios are operating in a neigh borhood, their spectrum occupancies and the spatial directions their signals are traversing is a fundamental primitive needed by many applications, ranging from smart radios to coexistence to network management to security. In this paper we present DOF, a detector that in a single framework accurately estimates all three parameters. DOF builds on the insight that in most wireless protocols, there are hidden repeating patterns in the signals that can be used to construct unique signatures, and accurately estimate signal types and their spectral and spatial parameters. We show via experimental evaluation in an indoor testbed that DOF is robust and accurate, it achieves greater than 85% accuracy even when the SNRs of the detected signals are as low as 0 dB, and even when there are multiple interfering signals present. To demonstrate the benefits of DOF, we design and implement a preliminary prototype of a smart radio that operates on top of DOF, and show experimentally that it provides a 80% increase in throughput over Jello, the best known prior implementation, while causing less than 10% performance drop for co-existing WiFi and Zigbee radios.","PeriodicalId":350796,"journal":{"name":"Proceedings of the ACM SIGCOMM 2011 conference","volume":"67 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114922913","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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