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Berkeley ELENG 228A - Lecture 2 Research Topics

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EECS228a – Lecture 2Research TopicsPravin VaraiyaShyam Parekhwww.eecs.berkeley.edu/~varaiyaWalrand EECS 228a 52OutlineEconomics of Networks802.11 WLANs Sensor NetworksCongestion ControlTraffic ModelsWalrand EECS 228a 53Economics of NetworksOutlineHangoverPricing of ServicesCompetition of UsersCompetition of ProvidersSuggested Readings: http://www-inst.eecs.berkeley.edu/~228a/papers/telecomRevolution.htm http://info.isoc.org/internet-history/ http://www.sims.berkeley.edu/resources/infoecon/Networks.htmlWalrand EECS 228a 54Economics of NetworksHangoverBubble: WiredWalrand EECS 228a 55Economics of NetworksHangoverBubble: WirelessWalrand EECS 228a 56Economics of NetworksHangoverOver-Investment Based on unrealistic growth forecast Overcapacity: Fiber  5x100 in three years Too many companies competing for same marketDebt Wireless: Expensive spectrum licenses Fibers IT in companies: PCs, Servers, NetworksFraudulent Claims WorldCom, Global Crossing, EnronWalrand EECS 228a 57EconomicsKey IdeasValue of services to users: externality, QoS, CoSMarket segmentationFlat rate pricing; congestion pricing; Paris metro pricing; time-of-day pricingIncentive compatibilityInter-ISP settlements; Peering agreementsInternet as a public goodWalrand EECS 228a 58EconomicsValue of ServicesExternality: KazaaValue per bit: email vs. fax vs. pictureValue of bit rate: video stream vs. radioValue of low latency: video stream vs. video conferenceValue of low response time: browsing with DSL vs. browsing with 56kQoS affects value and usageValue of QoS depends on application, userQuestion: How do you define/measure value?Walrand EECS 228a 59EconomicsMarket SegmentationBusinesses vs. Residential CustomersNetwork Application Providers vs. public Web SitesPrinciple: Charge more users with higher utilityQuestion: What makes segmentation possible? What limits it?Walrand EECS 228a 60EconomicsDifferentiated PricingExamples:  First Class & Economy in plane: More space but much more expensive Paris Metro: More expensive  Fewer Users  Better Service (e.g., Stanford vs. Berkeley?)Suggests Class of Service:  Better service by mechanism: e.g., priority  Better service by fewer users: e.g., expensive network; congestion pricing (e.g., packet marking); time-of-dayAlternative: QoS: You know what you pay for Service Level Agreement (implementation?) QoS of accepted calls: end-to-end testQuestion: How would you price a product whose quality varies statistically?Walrand EECS 228a 61EconomicsIncentive CompatibilityHow to discover the user’s willingness to pay?Examples: California Electricity: Providers offer bids and CA buys cheaper first  prices escalate Highest bidder auction: Spectrum auctions Highest gets but two highest pay Second highest price: Incentive compatible Question: Is TCP incentive-compatible?Walrand EECS 228a 62EconomicsCompetitionBasic supply and demand: More capacity than traffic  prices drop and providers go bankrupt; recovering fixed costsInternet traffic doubles every year instead of every 100 days …. Quality service is still rare and valuable:  Businesses use video conference over ISDN  Users pay a lot for CATV and pay-per-view T1 service expensive: demand existsQuestion: What is the role of state regulation?Walrand EECS 228a 63EconomicsGame TheoryFramework to analyze result of interaction of self-interested agentsSuggests strategies for  Pricing services Peering agreements Routing QoS definitions Evolution of industry (e.g., consolidation vs. specialization)Two parts: Games & Mechanism DesignWalrand EECS 228a 64802.11 Wireless LANsWe will explore Physical Layer Medium Access Control Security Issues Quality of Service IssuesWalrand EECS 228a 65802.11 Wireless LANsOverviewSometimes referred to as Wireless Ethernet or Wi-Fi networksFactors such as cost of deployment/maintenance and end-user flexibility are fueling phenomenal growth2003199919991997Year2.4 GHz11 Mbps802.11b2.4 GHz54 Mbps802.11g5 GHz54 Mbps802.11a2.4 GHz2 Mbps802.11SpectrumMax RateKey StandardsWalrand EECS 228a 66802.11 Wireless LANsPhysical Layer: Key technologies are Frequency Hopping Spread Spectrum Direct Sequence Spread Spectrum Orthogonal Frequency Division MultiplexingMedium Access Control (MAC) Based on Carrier Sense Multiple Access (CSMA)/Congestion Avoidance (CA)Walrand EECS 228a 67802.11 Wireless LANsSecurity Issues Basic security using the Wired Equivalent Privacy (WEP) standard based on Symmetric Key cryptology 802.1x attempted to rectify the serious flaws of WEP using stronger authenticationQuality of Service How to introduce QoS notions in an inherently non-guaranteed service? Basic idea: Service prioritization using different length of medium access deferral for different classesWalrand EECS 228a 68802.11 Wireless LANsResearch issues of interest in this courseAnalytic and simulation based modeling for Parameter tuning Performance prediction Impact of specific protocol featuresPerformance offered to upper layer protocols (e.g., TCP)QoS differentiation and impact on various data, voice, and video applications Investigate 802.11e (standardization in progress)Evaluation of various fairness criteriaWalrand EECS 228a 69Sensor NetworksAd hoc multihop networksSensor nodes perform Sense local environment Communicate own observations Relay messages from othersWalrand EECS 228a 70Sensor NetworksResearch issues of interest in this courseEvaluation of various routing schemes Scalability with number of nodes Convergence time Robustness to topology changes including failures Energy efficiency Application level performanceLocalization, failure detectionApplication-specific Sensor Network strategies (e.g., PEDAMACS)Walrand EECS 228a 71Congestion ControlOutlineMotivationExamplesIssuesWalrand EECS 228a 72Congestion ControlMotivationAt user level: Issues with QoSAt network level: Losses, inefficiency, unfairnessAt switch level: Scalability problemsWalrand EECS 228a 73Congestion ControlExamplesTCPCongestion in routersCall Admission ControlWalrand EECS 228a 74Congestion ControlIssuesFairness vs. OptimalitySimplicityRobustnessWalrand EECS 228a 75Traffic ModelsOutlineWhy bother?TransactionsPacket flowsWalrand EECS 228a 76Traffic ModelsWhy Bother?Network should be robust; not based on detailed traffic assumptionsTraffic characteristics impact Effectiveness of multiplexing


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Berkeley ELENG 228A - Lecture 2 Research Topics

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