Characterizing Usage in Wireless Networks: OutlineUnderstand user’s behavior mobility Utilization of APs Applications used in wireless networks www, VoIP, p2p application, streaming media Wireless devices usedCharacterizing wireless use is important Providers: provision the network Designers: standard features for high-throughput Software developers: wireless-aware applications Changes in usage is expected New wireless devices: PDAs, printers, audio players New applications: real-time multimediaThe Changing Usage of a Mature Campus-wide Wireless NetworkCampus-wide usage studyExtensive data set collectionsData decomposition and analysisClient usage trends from 2001 to 2004AP utilization trendsTraffic trends from 2001 to 2004Application changesSpecific applications: VoIP trendsSpecific applications: P2P trendsSpecific applications: streaming trendsMobility trends: Users are not very mobileCharacterizing Mobility and Network Usage in a Corporate Wireless Local-Area NetworkGoal of the paperExperiment DataPopulation characteristicsUtilization of APsUsers and loadMobility characteristicsPrevalenceSlide 24PersistenceSummary1Characterizing Usage in Wireless Networks: OutlineIntroductionMotivationCampus-wide usage studyCorporate mobility and usage studySummary2Understand user’s behaviormobilityUtilization of APsApplications used in wireless networkswww, VoIP, p2p application, streaming mediaWireless devices usedCharacterizing Usage in Wireless Networks3Characterizing wireless use is importantProviders: provision the network Designers: standard features for high-throughputSoftware developers: wireless-aware applicationsChanges in usage is expectedNew wireless devices: PDAs, printers, audio playersNew applications: real-time multimediaWhy important?4The Changing Usage of a Mature Campus-wide Wireless NetworkTristan Henderson, David Kotz, Ilya AbyzovDartmouth College5Campus-wide usage studyExtensive data collection at Dartmouth college over 17 weeksNovember 2003 – February 2004190 buildings on 200 acres5500 students / 1200 faculty•3200 – 3300 undergraduate students•required to own a computer (97% laptops)6Extensive data set collections4 sources of data consisting of over32 million syslog messages (1 sec resolution)16 million SNMP polls (5 min interval)4.6 TB of packets sniffed5.16 GB Call detail records (CDRs) for VoIP7Data decomposition and analysisMain goal: Understand user's behavior8Client usage trends from 2001 to 2004Behaviors that remain the sameUsage is still diurnalSame proportion of heavy users Same busiest buildingsBehaviors that have changed# of cards increased linearlyRoaming increasedAP utilization increased9AP utilization trendsFall/Winter 2003/4Fall 2001Avg = 66.4%Avg = 76.4%Approx 2.5x increase10Traffic trends from 2001 to 2004Traffic behavior changesOverall traffic increased by approximately 3xApplications changedDestination reversal (now more on-campus traffic)Traffic behavior constantsResidences generate the most traffic11Application changesReported proportionswww decreased from 62.9% to 28.6%P2P increased from 5.2% to 19.3%filesystems increased from 5.3% to 21.5%streaming increased from 0.9% to 4.6%Fall/Winter 2003/4Fall 200112Specific applications: VoIP trendsVoIP usage behaviorsUsage is diurnalNumber of devices does not grow muchUsers made short callsWireless users made few callsmedian call: 42 secmedian wireless: 31 sec13Specific applications: P2P trendsFiles were downloaded and uploadedTraffic was predominantly internal (72.7%)Few users responsible for most traffic147 cards (2%) saw over 1MB traffic10 cards (6.8% of the 2%) saw over 50% of recorded traffic14Specific applications: streaming trendsMost streaming was inboundOutbound itunes traffic represent music sharingMost traffic was within campus (79.6%)Streaming for teaching purposes produces large files15Mobility trends: Users are not very mobile50% of users spent 98.7% of time at homeespecially in residential, academic, and administration buildingsHigher than Castro paper50% of users spent nearly 10 minat single APLonger than Castro paper16Characterizing Mobility and Network Usage in a Corporate Wireless Local-Area NetworkMagdalena Balazinska – MITPaul Castro – IBM Research17Goal of the paperPrevious studies analyze usage of wireless networks in:University Building (Tang and Baker)University Campus (Kotz and Essien)Large Auditorium (Balachandran et al.)Metropolitan area network (Tang and Baker)Evaluate results from data collected in a Corporate Wireless Local-area NetworkFocus: Population characteristics, load distribution across APs, users level of activity, user mobility18Experiment DataThree Corporate buildingsOne Large (LBldg): 131 AP, ~10 miles away from the other two buildingsOne Medium (MBldg): 36 APOne Small (SBldg): 10 APMBldg and SBldg are adjacentTopology: 1 AP per corridor, extra in highly used rooms (i.e. customer lab in SBldg)Number of users = Number of MAC addressesData collected every 5 minutes, for 30 days, using SNMP19Population characteristics1366 distinct users seen: 796 mainly in LBldg, 437 in MBldg, 133 in SBldgSimilar results to working campus locations, different from dormitories or metropolitan networksPatterns in the population reflect patterns in n. of users20Utilization of APsGood coverage implies partial usage of APs21Users and loadAP throughput: amount of bytes that an access point forwards for any user in either direction in a given period of timeNumber of users and load of a specific AP are weakly dependent22Mobility characteristicsFew users visit all three buildingsDifferent mobility among usersMost of the time spent at one (home) locationUsers have higher activity on guest locations23PrevalencePrevalence: amount of time a user spends with a given APPrevalence matrixPrevalence distribution24Prevalence5 categories of users: Highly mobile, Somewhat Mobile, Regular, Occasionally Mobile, Stationary25PersistencePersistence: amount of time a user that a user stay associated w/ an AP before moving to another AP26SummaryUsage characterizationNumber of wireless cards; utilization of APsSpecific applications•VoIP, P2P, streaming mediaMobility•Prevalence, persistenceWork is