Quality of Service Monitoring for Video Streaming in Mobile Ad-Hoc Networks
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UNIVERSITY OF OSLO Department of Informatics Quality of Service Monitoring for Video Streaming in Mobile Ad-hoc Networks Master’s thesis Magnus Engh Halvorsen 1st February 2008 Abstract This thesis work is done in the context of a recently launched research project on delay-tolerant streaming, where the vision is to provide a video streaming solution capable of performing in a dy- namic, wireless, mobile environment without the presence of a fixed infrastructure. There are situations where regular wireless communication net- works are not accessible or the connectivity is limited. Examples of such situations are emergency and rescue operations, where commu- nications infrastructure may be non-existent or destroyed. The use of mobile devices connected using mobile ad-hoc network (MANET) technology and operating independently of any existing infrastructure, can help overcome these difficulties and provide connectivity despite large-scale disasters. Also, a lot of information cannot be commu- nicated through conventional systems, such as phones or radio. The ability to transmit streaming multimedia data could potentially save lives in an emergency situation. Multimedia streaming is a topic that has not received much at- tention in MANET research. Furthermore, most of the research and experiences with MANETs in general are based on work done in sim- ulated environments. However, in contrast to most prior MANET research, this thesis uses a practical approach. We present a working solution for serving and consuming streaming video using the Nokia 770 Internet Tablet that can serve as a starting point for future work on video streaming in mobile ad-hoc networks. The solution is based entirely on open-source software, and can thus be freely used and modified for future research. We also demonstrate how we were able to perform cross-layer mon- itoring of the video streaming solution through a strategy of combin- ing hardware resource monitoring and different network measurement methods. In addition, we show how to set up a small-scale, real-world testbed for mobile ad-hoc networks to perform such monitoring. Using this testbed, we the evaluated the performance of video streaming on the Nokia 770 in a mobile ad-hoc network environment. Our main finding is that to avoid degrading the normal operation of the devices or the network during streaming, conservation of CPU re- sources must be a priority when designing a video streaming solution for mobile ad-hoc networks. We also investigated the wireless link data reported by the Nokia 770 wireless interface drivers, and found that the reported values have serious limitations compared to the values reported by other wireless devices. 2 Acknowledgements I want to thank everyone who have given their time, assistance and patience so generously throughout the past two years. First and foremost, I would like to express my utmost gratitude to my supervisors, Thomas Plagemann and Matti Siekkinen, for their invaluable guidance and constructive comments throughout the course of my thesis work. Without your support and expertise, this work would not have been possible. I would also like to thank the participants of the Delay-Tolerant Streaming Project and the people in the DMMS research group at the University of Oslo for their helpful feedback and assistance on various matters. In particular, I want to thank Sergio Cabrero, for taking the time to explain their work on designing protocols for delay-tolerant streaming, and for assisting me with the initial configuration and software installation on the Nokia 770. Finally, I would like express my thanks to those of my friends who spent several hours of their valuable time proofreading this thesis. Your efforts and feedback helped much in improving its quality. 4 Contents I Background and concepts 14 1 Introduction 14 1.1 Background ............................ 14 1.2 Motivation and problem description . 15 1.3 Goalsandmethods ........................ 16 1.4 Contributions ........................... 16 1.5 Technicalchallenges. 17 1.6 Relatedwork ........................... 18 1.7 Outline............................... 20 2 Mobile ad-hoc networks 21 2.1 Characteristics .......................... 21 2.2 MANETApplications . 22 2.3 RoutinginMANETs ....................... 22 2.3.1 Single-channel vs. multi-channel . 22 2.3.2 Uniformvs. non-uniform . 23 2.3.3 Topology based vs. destination based . 23 2.3.4 Proactivevs. reactiveprotocols . 23 2.4 Examples of MANET routing protocols . 23 2.4.1 Optimized Link State Routing (OLSR) . 24 2.4.2 Ad-hoc On-demand Distance Vector Routing (AODV) 24 3 Multimedia streaming 26 3.1 Introduction............................ 26 3.2 Quality of Service (QoS) requirements . 26 3.3 Transportprotocols. 27 3.3.1 Transmission Control Protocol (TCP) . 28 3.3.2 UserDatagramProtocol(UDP) . 29 3.3.3 Real-Time Transport Protocol (RTP) . 29 3.4 Controlprotocols ......................... 29 3.4.1 Hypertext Transfer Protocol (HTTP) . 29 3.4.2 Session Initiation Protocol (SIP) . 30 3.4.3 Real-Time Streaming Protocol (RTSP) . 30 3.5 Multimedia streaming issues MANETs . 30 3.5.1 Wirelessmedium . 31 3.5.2 Resourceconstraints . 31 3.5.3 Heterogeneity . .. .. 32 6 3.5.4 Lackoffixedinfrastructure . 32 3.5.5 Topologychanges . 32 3.5.6 Maliciousnodes. 32 3.5.7 Transportprotocoldesignissues . 33 4 Measuring Quality of Service 34 4.1 Measurements at the network level . 34 4.2 Linkquality ............................ 35 4.2.1 Received Signal Strength Indicator (RSSI) . 35 4.2.2 Signal-to-NoiseRatio(SNR) . 36 4.2.3 Expected Transmission Count (ETX) . 36 4.2.4 Expected Transmission Time (ETT) . 36 4.3 Routequality ........................... 37 4.3.1 Expected Transmission Count (ETX) . 37 4.3.2 Weighted Cumulative ETT (WCETT) . 37 4.3.3 Routestability . .. .. 37 4.4 Measurements at the media level . 38 4.4.1 Subjective vs. objective measurement methods . 38 4.4.2 MeanSquareError(MSE) . 39 4.4.3 Peak Signal-to-NoiseRatio(PSNR) . 39 4.4.4 Relative Peak Signal-to-Noise Ratio (rPSNR) . 39 4.4.5 Summary of measurement methods . 40 4.5 QoS measurement in MANETs . 40 II Experiments 41 5 The Nokia 770 Internet Tablet 41 5.1 Aboutthedevice ......................... 41 5.2 Basicsoftware........................... 42 5.2.1 Operatingsystem . 43 5.2.2 xterm ........................... 43 5.2.3 SSH2server ........................ 43 5.2.4 WirelessTools. .. .. 43 5.2.5 NTPclient ........................ 44 5.2.6 OLSRdaemon ...................... 44 5.3 Networkmeasurements . 44 5.3.1 The proc filesystem (procfs) .............. 44 5.3.2 ifconfig........................... 45 5.3.3 netstat........................... 46 5.3.4 LinuxWirelessTools . 46 7 5.3.5 The sys filesystem (sysfs) ............... 50 5.3.6 ConnectionManager . 51 5.3.7 OLSRdaemon ...................... 52 5.4 The Nokia 770 multimedia architecture . 55 5.4.1 GStreamer......................... 55 5.4.2 The digital signal processor (DSP) . 56 5.4.3 Videostreaming. 58 5.5 Videostreamingsoftware. 59 5.5.1 gst-launch(GStreamer). 60 5.5.2 Flumotion......................... 60 5.5.3 HelixDNAServer. 60 5.5.4 Icecast........................... 61 5.5.5 FFmpeg .......................... 61 5.5.6 VideoLAN......................... 62 5.5.7 VideoPlayer ....................... 63 5.5.8 MPlayer .......................... 63 5.5.9 Xine ............................ 64 5.6 Resourcemonitoring . 64 5.6.1 The /proc filesystem ................... 64 5.6.2 ps ............................. 65 5.6.3 top............................. 65 5.6.4 sysstat........................... 65 5.7 Othersoftware .......................... 66 5.7.1 Mediautils......................... 66 5.7.2 MediaConverter. 67 5.7.3 VidConvert ........................ 67 5.7.4 RTPTools ......................... 67 5.7.5 LIVE555testprograms. 67 6 Wireless monitoring experiment 68 6.1 Motivationandpurpose . 68 6.2 Experimentsetup ......................... 69 6.3 Measurements with laptop and Nokia 770 . 70 6.4 Measurements with two Nokia 770s . 79 6.5 Lessonslearned .......................... 82 7 Video streaming experiment 88 7.1 Networkmonitoring. 88 7.1.1 Kismet........................... 88 7.1.2 tcpdump.......................... 88 7.1.3 mmdump ......................... 89 8 7.1.4 Wireshark ......................... 89 7.2 Experimentsetup ......................... 90 7.2.1 Choiceofstreamingserver . 90 7.2.2 Choice of video player . 91 7.2.3 Choiceofvideo ...................... 91 7.2.4 Choice of resource monitoring software . 95 7.2.5 Wirelesstestbed. 95 7.3 Performingtheexperiment . 99 7.3.1 Scenario1: Localplayback . 99 7.3.2 Scenario2: Node-to-node . .108 7.3.3 Scenario3:MANET . .121 7.4 Lessonslearned ..........................129 7.5 PlaybackontheNokiaN800 . .129 7.5.1 AbouttheNokiaN800 . .130 7.5.2 Performing the measurements . 130 7.5.3 Results...........................131 7.5.4 Lessonslearned . .136 8 Conclusions 137 8.1 Summary .............................137 8.2 Criticalevaluation . .138 8.3 Openproblemsandfuturework . 138 A Configuration of software 144 A.1 FlashingthelatestNokiaimage . 144 A.2 Gaininglocalrootaccess ontheNokia770 . 144 A.3 SettingupScratchbox . .145 A.4 Compiling and running FFserver . 146 A.5 Softwarerepositories . .147 B Source code 148 B.1 wlantest.sh.............................148 B.2 generate plotdata.py .......................150 B.3 generate all plots.sh........................152 B.4 resourcelogger.sh . .153 B.5 networklogger.sh . .155 B.6 wlanmonitor.sh . .. .. .157 B.7 start ffserver.sh ..........................158 B.8 start olsrd.sh