9/13/2004 6:32 PM Mesh Networking http://research.microsoft.com/mesh Victor Bahl Senior Researcher Systems and Networking Group Microsoft Research Team Introduction Community Network Executive Sponsor Craig Mundie, CTO & Senior Vice President Microsoft Microsoft Research Victor Bahl (Project Lead), Richard Draves, Jitu Padhye, Lili Qiu, Alec Wolman, Brian Zill The Venice Incubation Jeff Erwin (Project Lead), Pierre De Vries, Ian Ferrell, Jason Ginchereau, Steve Kelly, Alexander Popoff, Karen Community Network Applications Mesh Formation: Problem Internet use increased social contact, public participation and size of Formulation social network. (social capital - access to people, information and resources) Question Example Scenario Keith N. Hampton, MIT (author of “Netville Neighborhood How many homes in the Viable mesh: group of at least 25 Study”) neighborhood have to sign houses that form a connected URL: http://www.asanet.org/media/neville.html up before a viable mesh graph forms? Topology: A North Seattle Shared Broadband Internet Access Answer depends on Neighborhood. 8214 houses, Neighborhood watchdog (e.g. video surveillance) Definition of “viable” 4Km x 4Km Neighborhood TiVO Wireless range Neighborhood topology Wireless range: 50, 100, 200 and 1000 meters Medical & emergency response Probability of participation Distributed backup by a given houshold Houses decide to join at random, Neighborhood eBay, portals independent of each other. We consider 0.1% to 10% Bits produced locally, gets used locally participation rates. Social interaction © 2003-2004 Microsoft Corporation. All rights reserved. This presentation is for informational purposes only. Microsoft makes no warranties, express or implied, in this summary. 1 9/13/2004 6:32 PM Mesh Formation 5-10% subscription rate needed for suburban Suburbia topologies with documented Upper-middle class wireless ranges neighbourhood Houses about 40-120’ apart Once a mesh forms, it is 21 houses covering 7.8 Once a mesh forms, it is acres or ~1/3 acre lots usually well-connected Microwave ovens, cordless i.e. number of outliers are few phones, televisions etc. (most nodes have > 2 neighbors) cause interference Angled sheetrock and concrete walls, hills and Need to investigate other trees absorb signal and create multi-path joining models reflections Not a pleasant place to roll out wireless Business model One reason why cellular considerations will be uses 80’-100’ masts for their cell towers important Increasing range is key for good mesh connectivity 0 20 40 60 80 100120140160 802.11a in a Multihop Network Impact of path length on TCP Throughput 5 GHz: 12000 Bandwidth is good, provided you can get a 10000 mesh to form Published 802.11a ranges led us to believe we could 8000 achieve the yellow circle Measured range from the apartment trial is the red 6000 circle Range is not sufficient to TCP Throughput (Kbps) 4000 bootstrap mesh until installed % is quite high (in this diagram ~50%) 2000 0 01234567 Path Length (Hops) 0 20 40 60 80 100120140160 Round Trip Delay versus Collision between ISM devices Node Density Average RTT avg_rtt = 0.1*curr_sample + 0.9*avg_rtt One sample every 0.5 seconds 0.2 0.18 0.16 0.14 0.12 0.1 0.08 Average RTT 0.06 Phone 0.04 0.02 0 0 20 40 60 80 100 120 140 160 180 Time A new 100Kbps CBR connection starts every 10 seconds, between a new pair of nodes. All nodes hear each other. Panasonic 2.4GHz Spread Spectrum Phone 5m and 1 Wall from receiver © 2003-2004 Microsoft Corporation. All rights reserved. This presentation is for informational purposes only. Microsoft makes no warranties, express or implied, in this summary. 2 9/13/2004 6:32 PM Colliding standards Courtesy: Mobilian Corp. Conclusion Meshes are viable existing technologies are inadequate To make it real Identify and solve key problems build and deploy a mesh prototype Performance worsens when there are large number of short-range radios in the vicinity Problem Space Problem Space (Cont) Range and Capacity [Talk by Jim K; Poster by John D. & Ranveer C.] Smart Spectrum Utilization Electronically steerable directional antenna or MIMO for range enhancement Spectrum Etiquittes Multiple frequency meshes Agile Radios, cognitive radios Multi-radio hardware for capacity enhancement via greater spectrum utilization New data channel MAC for higher throughput Cognitive software & applications Tools for predicting & analyzing network viability & performance Analytical Techniques Multihop Routing [Talk by Rich D.; Poster & Demo by Jitu P. & Brian Z.] Information theoretic tools that predict expected capacity with practical L2.5 on-demand source routing. Routes selected based on link quality constraints, based on experimental data Route selection with multiple radios Digital Rights Management (DRM) Security and Fairness Broadband access will become popular with expanded digital content. Guard against malicious users (and freeloaders) Increase the value proposition for end-users/subscribers EAP-TLS between MeshBoxes, PEAPv2 or EAP-TLS between clients and MeshBoxes Priority based admission control, Secure traceroute Ease of use (Plug and play, HCI) Self Management & Self Healing [Talk by Lili Q.; Poster by AP] Make the user experience pleasant Desirable: avoid network operator - minimal human intervention QoS protocols over wireless meshes to improve content delivery Watchdog mechanism Data cleaning and liar detection Proof of Concept via rapid prototyping and testbed deployments Online simulation based fault isolation and diagnosis Scenario: Neighborhood Wireless Meshes Mesh Routing Functionality Mesh Box Mesh Management Module Configuration ITAP End Device Connects to a Mesh Router Standards Compliant Diagnostics Client Network Interface and Server DLLs TCP / IP S Mesh Router / MeshBox E Link Routes traffic within the C Mesh Connectivity Layer Monitor mesh and to the U (MCL) Module neighborhood Internet R Multi-hop Routing/Bridging Gateway I Radio Selection Metric Serves as access point for T Topology Control End Devices Y Diagnostics Kernel Mesh Router Module Neighborhood Internet Gateway Gateway between the mesh Control Channel nodes and the Internet Data Channel Radio End Device Miniport Driver Radio Miniport driver © 2003-2004 Microsoft Corporation. All rights reserved. This presentation is for informational purposes only. Microsoft makes no warranties, express or implied, in this summary. 3 9/13/2004 6:32 PM Research Results Research Results (cont.) Spectrum Etiquette P. Bahl, A. Hassan, P. Vries, Spectrum Etiquettes for Short Single Radio Mesh Performance Range Wireless Devices Operating in the Unlicensed Band - A R. Draves, J. Padhye, and B. Zill. Comparison of Routing Proposal,,White paper, Spectrum Policy: Property or Commons, Stanford Law School Metrics for Static Multi-Hop Wireless Networks. ACM SIGCOMM 2004 (also Technical Report, MSR-TR-2004-18, March 2004) Multi Radio Meshes A. Adya, P. Bahl, J. Padhye, A. Wolman, and L. Zhou. A Multi-Radio Unification Protocol for IEEE 802.11 Wireless Networks. BroadNets 2004 (also Technical Report, MSR-TR-2003-41, June 2003) Single Radio Mesh Performance R. Draves, J. Padhye, and B. Zill. Routing in Multi-radio, Multi-hop Determining Mesh Capacity Wireless Mesh Networks, To appear in ACM MobiCom 2004 K. Jain, J. Padhye, V. Padmanabhan, and L. Qiu. Impact of Interference on Multi-hop Wireless Network Performance. ACM Mobicom, San Diego, CA, September 2003 Multi Radio Mesh Routing & Performance Mesh Self Management L. Qiu, P. Bahl, A. Rao, and L. Zhou. Fault Detection, Isolation, L. Qiu, P. Bahl, A. Rao, and L. Zhou. Fault Detection, Isolation, and and Diagnosis in Multi-hop Wireless Networks. Technical Diagnosis in Multi-hop Wireless Networks. Technical Report, MSR- Report, MSR-TR-2004-11, December 2003 TR-2004-11, December 2003 Report, MSR-TR-2004-11, December 2003 Capacity Enhancement Capacity Enhancement Problem In current IEEE 802.11 meshes Improve throughput via better utilization of the spectrum Design Constraints Require only a single radio per node Use unmodified IEEE 802.11 protocol Do not depend on existence of control channel Do not depend on existence of control channel Only one of 3 pairs is active @ any given time Assumption With MSR’s SSCH enabled meshes Node is equipped with an omni-direction antenna Ch 1 1 2 1 4 5 4 - MIMO technology is OK Ch 2 Multiple orthogonal channels are available 3 4 5 2 1 6 Channel switching time is 80 usecs. Ch 3 5 6 3 6 3 2 - current speeds 150 microseconds 10 msecs 10 msecs 10 msecs … Performance Mesh Diagnosis Visualization 100 nodes, IEEE 802.11a, 13 channels, every flow is multihop Module Avg. per node Throughput Total System Throughput 4 80 3.5 70 3 60 50 2.5 40 2 30 SSCH IEEE 802.11 1.5 20 Throughput (Mbps) 1 Throughput (Mbps) Throughput SSCH M802.11 10 0.5 0 10 20 30 40 50 0 Number of Flows 10 20 30 40 50 Number of Flows Significant capacity improvement when traffic load is on multiple separate flows © 2003-2004 Microsoft Corporation. All rights reserved. This presentation is for informational purposes only. Microsoft makes no warranties, express or implied, in this summary. 4 9/13/2004 6:32 PM Testbeds Details 201 210 23 to 30 nodes 220 Inexpensive desktops (HP d530 SF) 205 Two radios in each node 203 226 NetGear WAG or WAB, Proxim 204 OriNOCO Cards can operate in a, b or g mode. 227 221 Purpose 207 Verification of the mesh software stack 206 Routing protocol behavior 208 225 211 224 Fault diagnosis and mesh management algorithms 223 Security and privacy architecture 209 Range and robustness @ 5 GHz with