Slide 1Slide 2Slide 3Slide 4Slide 5Variable Hop Length Experiments ResultsSlide 7Slide 8Hidden Terminal Experiments ConfigurationHidden Terminal Experiments ResultsRing Experiment ConfigurationRing Experiment Results802.11 FairnessSlide 14Grid Experiment Configuration (Cont’d)Slide 16Slide 17Bluetooth Experiments Gerla, M et al, Tyrrenia Conf, sept 2000Slide 19Exp # 1:TCP throughput in Bluetooth (single piconet)Exp #2:TCP Throughput in WaveLAN vs BT (multiple piconets)Exp #2 (cont): Throughput of TCP flowsTCP and IP TelephonyExp #3: Bluetooth; TCP + VoIPSlide 25Exp #3: WaveLan : TCP + VoIPSlide 27Simulation: what have we learned?Fair Sharing of MAC under TCP in Wireless Ad Hoc NetworksMario GerlaComputer Science DepartmentUniversity of California, Los AngelesLos Angeles, CA 90095http://www.cs.ucla.edu/NRL/wirelessUCLA DARPA Domains ProjectOutline•Overview of CSMA, FAMA and IEEE 802.11.•MAC performance with TCP.Variable Hop Length Experiments.Hidden Terminal Experiments.Ring Experiments.Grid Experiments.•Static.•Mobility.UCLA DARPA Domains ProjectSimulation Using GloMoSim•Detailed model of the protocol stack.•Allows investigation of TCP and MAC layer interactions.•Capability to simulate large number of nodes.•GloMoSim web page.http://pcl.cs.ucla.edu/projects/domains/glomosim.htmlUCLA DARPA Domains ProjectMAC Layer Protocols•CSMARequires carrier sensing before transmission.If the channel is free, the packet is transmitted immediately.Otherwise, it is rescheduled after a random timeout.•FAMABuilds on CSMA.Uses the RTS (Request To Send) and CTS (Clear To Send) exchange to prepare the floor for data transmission.•802.11Uses carrier sensing and RTS/CTS, similar to FAMA.Utilizes link-level ACKs.Collision Avoidance scheme.UCLA DARPA Domains ProjectVariable Hop Length Experiments Configuration0 1 2 543•Each node is 10 meters apart from its neighbors.•Each node has a radio power range of 10 meters.•2Mbps channel bandwidth.•FTP traffic.•TCP window size varies from 1 to 16 packet size.•Variable number of hops (single connection).i.e., FTP connection 0-1, 0-2, 0-3, 0-4, 0-5 (one at a time).UCLA DARPA Domains ProjectVariable Hop Length Experiments ResultsVariable Hop Length Experiments ResultsVariable Number of Hops Experiment (CSMA)05000001000000150000020000001 2 3 4 5Number of HopsThroughput (bps)W = 1W = 2W = 4W = 8W = 16UCLA DARPA Domains ProjectVariable Hop Length Experiments Results (Cont’d)Variable Hop Length Experiments Results (Cont’d)Variable Number of Hops Experiment (FAMA)05000001000000150000020000001 2 3 4 5Number of HopsThroughput (bps)W = 1W = 2W = 4W = 8W = 16UCLA DARPA Domains ProjectVariable Hop Length Experiments Results (Cont’d)Variable Hop Length Experiments Results (Cont’d)•CSMA and FAMA degrades with window size > 1 pkt.Collisions between TCP data and ACKs.•802.11 performs the same no matter the window size.Link-level ACKs combat collisions. Variable Number of Hops Experiment (802.11)05000001000000150000020000001 2 3 4 5Number of HopsThroughput (bps)W = 1W = 2W = 4W = 8W = 16UCLA DARPA Domains ProjectHidden Terminal Experiments ConfigurationHidden Terminal Experiments Configuration•FTP traffic•Connections from node 0 to node 1 and from node 2 to node 1.•Node 0 and node 2 cannot hear each other.012UCLA DARPA Domains ProjectHidden Terminal Experiments ResultsHidden Terminal Experiments Results•CSMA suffers from hidden terminal.•FAMA and 802.11 performs well due to RTS/CTS exchange.0500000100000015000002000000Throughput (bps)CSMA FAMA 802.11MAC ProtocolHidden Terminal Experiment0-12-1UCLA DARPA Domains ProjectRing Experiment ConfigurationRing Experiment Configuration•FTP traffic•Multiple single hop connections.i.e., 0-1, 1-2, 2-3, 3-4, 4-5, 5-6, 6-7, 7-0 (at the same time).01654327UCLA DARPA Domains ProjectRing Experiment ResultsRing Experiment Results•FAMA best in both fairness and aggregate throughput.•802.11 unfairness due to timers.0100200300400500600Throughput (Kbps)CSMA FAMA 802.11MAC Protocol0-11-22-33-44-55-66-77-0UCLA DARPA Domains Project802.11 Fairness802.11 Fairness•Yield time.Time a node yields after transmitting a frame.0100200300400500600Throughput (Kbps)802.11 (Standard) 802.11 (YieldTime)MAC Protocol0-11-22-33-44-55-66-77-0UCLA DARPA Domains ProjectGrid Experiment Configuration•Each node is 10 meters apart from its horizontal and vertical neighbors.•Each node has a radio power range of 30 meters.•FTP connections are established between node 18 to node 26, node 36 to node 44, node 54 to node 62, node 2 to node 74, node 4 to node 76 and node 6 to node 78. 01 1098 2 19 1817 112074 7372268034 13125 22 21 14237776756 157 24 162579782728 373635 29 443830314039324133423443 46 45475349485051525455 646362 56 7165575867665968606961 70UCLA DARPA Domains ProjectGrid Experiment Configuration (Cont’d)Grid Experiment Configuration (Cont’d)•2Mbps channel bandwidth.•Nodes move at a rate of 10 meters per second in a random direction with a probability of 0.5.•When mobility is not considered, static routing is used.•When mobility is introduced, Bellman-Ford routing is utilized with routing table updates occurring once every second.UCLA DARPA Domains ProjectGrid Experiments Results (No Mobility)•Without mobilityCSMA performs poorly due to interference by neighboring streams and by intersecting streams.FAMA fair due to RTS/CTS and less aggressive yield time.802.11 exhibits capture.050000100000150000200000250000Throughput (bps)CSMA FAMA 802.11MAC ProtocolNo Mobility18-2636-4454-622-744-766-78UCLA DARPA Domains ProjectGrid Experiments Results (With Mobility)CSMA and FAMA collapse with mobility due to lack of fast loss recovery facilities.802.11 still operational.•Link level ACKs help recover from loss caused by transient nodes.•Capture exists.050000100000150000200000Throughput (bps)CSMA FAMA 802.11MAC ProtocolWith Mobility18-2636-4454-622-744-766-78UCLA DARPA Domains ProjectBluetooth Experiments Gerla, M et al, Tyrrenia Conf, sept 2000Bluetooth Experiments Gerla, M et al, Tyrrenia Conf, sept 2000•Experiment #!: TCP throughput in a single piconet. Throughput versus the no. of TCP connections. Each TCP connection starts from a different slave on the common piconet, and goes through the access point (BT master). •Experiment #2: TCP throughput when multiple piconets are used in parallel. Each piconet here supports