Windows Streaming Media Windows Streaming Media Performance Analysis on a Performance Analysis on a IEEE 802.11g Residential IEEE 802.11g Residential

NetworkNetwork

The Seventh International Conferences The Seventh International Conferences on Wireless and Optical on Wireless and Optical CommunicationsCommunicationsMontreal, Canada, May 30 – June 1, Montreal, Canada, May 30 – June 1, 2007 2007

Travis Grant, Saurabh Gupta,Travis Grant, Saurabh Gupta,Harshal Pandya and Robert KinickiHarshal Pandya and Robert Kinicki

Worcester Polytechnic InstituteWorcester Polytechnic InstituteWorcester, MA, 01609 USAWorcester, MA, 01609 USA

PresenterPresenter - - Bob KinickiBob Kinickirek@cs.wpi.edurek@cs.wpi.edu

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OutlineOutline

• MotivationMotivation• Previous WorkPrevious Work• ExperimentsExperiments• Results and AnalysisResults and Analysis• ConclusionsConclusions

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MotivationMotivation• One objective is to anticipate support for One objective is to anticipate support for HD HD

videovideo on demand (VOD)on demand (VOD) over residential over residential Wireless Local Area Networks (WLANs) via Wireless Local Area Networks (WLANs) via IPTV and broadband services.IPTV and broadband services.

• We investigate a current off-the-shell We investigate a current off-the-shell streaming server’s (streaming server’s (Windows Streaming Windows Streaming MediaMedia) delivery of high quality video over a ) delivery of high quality video over a residential WLAN under the assumption residential WLAN under the assumption there are no special administrative there are no special administrative adjustments by the customer .adjustments by the customer .

• Experimental measurements can provide Experimental measurements can provide insight into streaming application insight into streaming application performance behavior when wireless errors performance behavior when wireless errors are encountered in the are encountered in the 802.11g MAC802.11g MAC layer. layer.

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OutlineOutline

• MotivationMotivation• Previous WorkPrevious Work• ExperimentsExperiments• Results and AnalysisResults and Analysis• Conclusions Conclusions

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Measurement Studies of Measurement Studies of 802.11802.11

• [Bai and Williamson 04] “The Effects of Mobility on Wireless [Bai and Williamson 04] “The Effects of Mobility on Wireless Media Streaming Performance”Media Streaming Performance”– Create their own AP device to vary queue size.– Downstream measurements of UDP videos show WLAN supports

easily two fixed clients receiving 1Mbps video clips with AP queue less than 30 buffers.

– When one client becomes mobile, it goes through “bad” locations and frames get discarded, rate adaptation moves to 1 Mbps, AP queue backlogs and overflows!!

– When one client fixed and one client mobile, mobile client kills performance of fixed client because the MAC-layer queue fills with frames from poorly-connected client. The AP queue is the bottleneck.

• [Yarvis et al. 05] “Characteristics of 802.11 Wireless [Yarvis et al. 05] “Characteristics of 802.11 Wireless Networks”Networks”– Consider: transmission rate, transmission power, node location,

house type.– Conduct measurements in three homes with link layer

retransmissions disabled.– Discover: wireless performance can be quite asymmetric, node

placement can be a key factor, no correlation with physical distance.

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Measurement Studies of Measurement Studies of 802.11802.11

• [F. Li et al. 05] “Application, Network and Link [F. Li et al. 05] “Application, Network and Link Layer Measurements of Streaming Video over a Layer Measurements of Streaming Video over a Wireless Campus Network”Wireless Campus Network”– Both papers involve clients at good and bad locations.– TCP versus UDP streaming matters at a bad location.– Multi-encoded versus single encoded matters at a bad

location.• [Gretarsson et al. 05] “Performance Analysis of [Gretarsson et al. 05] “Performance Analysis of

the Intertwined Effects between Network Layers the Intertwined Effects between Network Layers for 802.11g Transmissions”for 802.11g Transmissions”– A single TCP download only managed 18.8 Mbps!– Application behavior impacts WLAN performance of

concurrent applications.– AP queuing strategy can impact performance beyond the

802.11 performance anomaly.

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OutlineOutline

• MotivationMotivation• Previous WorkPrevious Work• ExperimentsExperiments• Results and AnalysisResults and Analysis• ConclusionsConclusions

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Experimental ConfigurationExperimental Configuration

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Measurement ToolsMeasurement Tools

• WRAPI and MediaTracker collect WRAPI and MediaTracker collect data on the client.data on the client.

• See our Web page for free See our Web page for free WLAN measurement tools WLAN measurement tools http://http://perform.wpi.eduperform.wpi.edu/tools//tools/..

• Other data was collected using Other data was collected using Etheral on the wireless sniffer.Etheral on the wireless sniffer.

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Three Test VideosThree Test Videos

1.1. HD 60 sec, 8.1 Mbps singly-HD 60 sec, 8.1 Mbps singly-encoded HD sample video from encoded HD sample video from Microsoft Web site.Microsoft Web site.

2.2. SD 120 sec, 5.1 Mbps CBR video SD 120 sec, 5.1 Mbps CBR video that exceeded SD that exceeded SD

quality.quality.

3.3. LowRes 126 sec, 1.1 Mbps videoLowRes 126 sec, 1.1 Mbps video

* * While streams were sent using both While streams were sent using both TCP and UDP, only TCP results are TCP and UDP, only TCP results are reported in this paper.reported in this paper.

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OutlineOutline

• MotivationMotivation• Previous WorkPrevious Work• ExperimentsExperiments• Results and AnalysisResults and Analysis• ConclusionsConclusions

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Good versus Bad LocationGood versus Bad Location

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

Good Bad Neighbor's AP

µ 54.4 MbpsChannel 11

µ 11 MbpsChannel 6

µ 5.5 MbpsChannel 11

Signal Strength of Visible APs

OnlyGood resultsreported inthis paper.

Received Signal Strength (RSSI) can impactMAC layer rate adaptation algorithms.

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HD Video CPU UtilizationHD Video CPU Utilization

Videostalls

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HD Video TestsHD Video Tests

Actual versus Observed Play Duration

0

20

40

60

80

100

120

140

1 2 3 4 5 6 7 8 9 10

Test Run Number

Tim

e (s

econ

ds)

Actual Play Duration (Ideal) Observed Play Duration

High Definition Video Actual Playback Times on 802.11g

FrequentAudio/Video

stallsoccurred!

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SD and LowRes VideosSD and LowRes Videos

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SD Video TestSD Video Test

SD Videostreams

successfully

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LowRes VideoLowRes Video

HighError

Counts

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SD Video MeasurementsSD Video Measurements

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Conclusions and Conclusions and ConjecturesConjectures

• HD video did not successfully stream over HD video did not successfully stream over residential WLAN. Possible reasons are:residential WLAN. Possible reasons are:– Restrictions within the WMS server configuration force

playout buffer induced stalls.– Only one encoded level for HD video limits Intelligent

Streaming adjustments.– MAC layer rate adaptation when MAC frame loss count is

high negatively impacts Intelligent Streaming.– MAC layer retries cause problems for application

bandwidth estimation probes.

• 5.1 SD video and LowRes video did 5.1 SD video and LowRes video did successfully stream over WLAN.successfully stream over WLAN.

• {Future Work} {Future Work} What happens when there What happens when there are other concurrent flows?are other concurrent flows?

Windows Streaming Media Windows Streaming Media Performance Analysis on a Performance Analysis on a IEEE 802.11g Residential IEEE 802.11g Residential

NetworkNetwork

Travis Grant, Saurabh Gupta,Harshal Pandya and Robert KinickiWPI Computer Science Department

Worcester, MA, 01609 USArek@cs.wpi.edu

Thank You!

Questions ??