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Doc. : IEEE 11 -03 -0712 -00 -0 wng September 2003 Performance of an 802. 11 Home Network Mesh Testbed September 15, 2003 W. Steven Conner Intel Corporation (w. steven. conner@intel. com) Submission 1 Intel Corporation

Doc. : IEEE 11 -03 -0712 -00 -0 wng September 2003 Outline Overview of 802. 11 ESS Mesh Performance evaluation of a wireless home network testbed Lowering the barriers to 802. 11 mesh deployment Recommendation to start 802. 11 Mesh SG Summary Submission 2 Intel Corporation

Doc. : IEEE 11 -03 -0712 -00 -0 wng September 2003 Overview: 802. 11 Mesh Architectures Peer-to-Peer Mesh (Ad Hoc Mode) Infrastructure ESS with WDS Backhaul WDS Links Ad Hoc Links Hybrid Infrastructure/ Ad Hoc Mesh Ad Hoc Links Ad Hoc or WDS Links Submission 3 Intel Corporation

Doc. : IEEE 11 -03 -0712 -00 -0 wng September 2003 Overview: 802. 11 ESS Mesh is not limited to highly mobile networks with no infrastructure Also has application in many fixed-infrastructure environments Extended range and coverage, without requiring additional wires (convenient deployment, cost) Enhanced redundancy, reliability Potential throughput improvement Example networks where ESS Mesh is useful: Home networks, hotspot networks, etc. Submission 4 Intel Corporation

Doc. : IEEE 11 -03 -0712 -00 -0 wng September 2003 Question: Does it Make Sense to Deploy a Wireless ESS Mesh for a Home Network? 71 70 B 73 A Office Den 72 74 C Back Yard Living Room D 77 Submission 76 75 Lower Level Upper Level 5 Intel Corporation

Doc. : IEEE 11 -03 -0712 -00 -0 wng September 2003 Overview: Experimental evaluation of an 802. 11 b home mesh network 71 70 B 73 A Office Den 72 74 C Back Yard D 77 Living Room 75 76 Lower Level Upper Level Experiments performed in my house (~2000 sq. ft. ) in Hillsboro, OR (August, 2003) Topology: 8 Client Laptops and 4 AP routers In a real home network scenario, some of the laptops would likely be replaced by other 802. 11 enabled devices (e. g. , DVRs, media servers, stereo systems, etc. ) Traffic: Experiments assume network traffic is not limited to Internet surfing on a broadband link Clients share significant amount of data within the home (e. g. , A/V content sharing, photo storage, data backup, etc. ) Submission 6 Intel Corporation

Doc. : IEEE 11 -03 -0712 -00 -0 wng September 2003 Testbed Configurations Configuration 1 Traditional 1 -hop BSS 802. 11 b, auto-rate, 15 m. W BSS emulated with ad-hoc mode All clients communicate directly with AP-A n f ra ge to Ou Configuration 2 Multi-hop ESS Mesh 802. 11 b, 11 Mbps, 15 m. W ESS emulated with ad-hoc mode - Centrally configured minimum-airtimemetric routing (zero overhead) Clients communicate with best AP to join wireless ESS mesh Submission 7 Intel Corporation

Doc. : IEEE 11 -03 -0712 -00 -0 wng September 2003 Individual Node Throughput Non-Mesh BSS Individual Node Throughput Multi-Hop ESS Individual Node Throughput 1. 7 X 3. 1 X Connected! t Ou ra of ng e Submission 8 Intel Corporation

Doc. : IEEE 11 -03 -0712 -00 -0 wng September 2003 Multi-Node Throughput Non-Mesh BSS Aggregate Throughput Multi-Hop ESS Aggregate Throughput 5. 322 1. 3 X 1. 9 X 5. 338 3. 910 2. 878 1. 994 t Ou ra of ng 2. 1 X 3. 880 3. 284 1. 520 e Submission 9 Intel Corporation

Doc. : IEEE 11 -03 -0712 -00 -0 wng September 2003 Multi-Node Throughput cont. Aggregate Throughput with 8 Clients 2. 1 X 3. 709 1. 719 t Ou ra of ng e Submission 10 Intel Corporation

Doc. : IEEE 11 -03 -0712 -00 -0 wng September 2003 Client-to-Client Throughput Non-Mesh BSS Client-to-Client Throughput Multi-Hop ESS Client-to-Client Throughput 3. 4 X 2. 4 X f to ran ge Ou • Note: Direct client-to-client links can help here as well Submission 11 Intel Corporation

September 2003 Network Latency Non-Mesh BSS End-to-End Latency Doc. : IEEE 11 -03 -0712 -00 -0 wng Multi-Hop ESS End-to-End Latency ~ 2 ms increase per hop n f ra ge to Ou • Highly dependent on implementation Submission 12 Intel Corporation

Doc. : IEEE 11 -03 -0712 -00 -0 wng September 2003 Summary of Testbed Results A multi-hop ESS mesh is beneficial, even for a relatively small-scale home network Multi-hop topologies: Can be built with standard 802. 11 hardware Can improve network performance in comparison to traditional 1 -hop BSS networks These experiments used 1 radio on each AP/router; multi-radio per AP/router would allow even better performance (multi-channel) Question: If mesh networking with 802. 11 works today, why do we need additional standards support? Submission 13 Intel Corporation

Doc. : IEEE 11 -03 -0712 -00 -0 wng September 2003 Barriers to 802. 11 Mesh Deployment Interoperability Security Configuration / Management Lack of Hooks for Statistics/Control Radio and metric aware routing MAC Performance Submission 14 Intel Corporation

Doc. : IEEE 11 -03 -0712 -00 -0 wng September 2003 Making Mesh Work Key areas for IEEE Standardization: Interoperability Standardizing over-the-air messaging for mesh Routing: – L 2 mesh subnet for wireless backhaul – Radio and metric-aware path selection (hop-count is not sufficient!) Security: To make it possible to secure a mesh, routers should be able to trust each other Leverage/extend 802. 11 i for mesh Improving Configuration / Management Statistics and Control Hooks need to be exposed between MAC and “mesh layer” Leverage/extend 802. 11 k for mesh Submission 15 Intel Corporation

Doc. : IEEE 11 -03 -0712 -00 -0 wng September 2003 Research indicates 802. 11 MAC performance needs to be optimized for large scale mesh networks A few notable examples: RTS/CTS does not correctly solve hidden terminal problem in a mesh Tends to either sacrifice spatial reuse or allow excessive interference 1 RTS/CTS fails to achieve good schedule in a multi-hop chain RTS/CTS scheduling along a chain cause serious TCP fairness problems and backoff inefficiencies 2 RTS/CTS does not efficiently schedule transmissions in a multihop chain 3 [1] Kaixin Xu, M. Gerla, and Sang Bae, "How effective is the IEEE 802. 11 RTS/CTS handshake in ad hoc networks? " IEEE Globecom'02, 2002, pp. 72 -76. [2] Shugong Xu and Tarek Saadawi – “Does the IEEE 802. 11 MAC Protocol Work Well in Multihop Wireless Ad Hoc Networks? ” IEEE Communications Magazine, June 2001, pp 130 -137. [3] J. Li, C. Blake, D. S. De Couto, H. I. Lee, and R. Morris. Capacity of ad hoc wireless networks. In Proceedings of ACM MOBICOM, pages 61 --69, July 2001. Submission 16 Intel Corporation

Doc. : IEEE 11 -03 -0712 -00 -0 wng September 2003 Enabling Mesh Usage Models Before MAC Enhancements: Home Network Small Office Small Hotspot MAC Enhancements Necessary: Enterprise Large Conference High Performance Home Network Power-users, A/V Submission Multi-hop scheduling/scalability are significant issues 17 Intel Corporation

Doc. : IEEE 11 -03 -0712 -00 -0 wng September 2003 Lowering the Barriers to 802. 11 Mesh Deployment Proposed Parallel Efforts: Standardize Multi-Hop ESS New 802. 11 Mesh Study/Task Group Radio/Metric-Aware L 2 Routing Interoperability Security Configuration / Management Leverage 802. 11 i/k where possible Enhance MAC Performance for Mesh Scalability Scheduling (managing collisions/ interference) Submission 18 Influence current/ future MAC enhancement efforts to improve scalability of 802. 11 for mesh Intel Corporation

Doc. : IEEE 11 -03 -0712 -00 -0 wng September 2003 Recommendation to WNG for Starting a Mesh Study Group Scope: Develop an Infrastructure-Mode 802. 11 ESS AP Mesh that Appears as a Broadcast Ethernet to Higher Layer Protocols Scale: Up to 255 devices (APs and Clients) Security: Include support for trusted set of routers controlled by single entity Routing: Include support for both broadcast and radio/metricaware unicast routing Multiple-radios: Include support for optional multiple-radios per router Usage Models: Initially focus on home and smallscale hotspot networks Submission 19 Intel Corporation

Doc. : IEEE 11 -03 -0712 -00 -0 wng September 2003 Backup Submission 20 Intel Corporation

Doc. : IEEE 11 -03 -0712 -00 -0 wng September 2003 Is IEEE the Right Place to Create a Mesh Standard? IETF/IRTF MANET groups have been working on L 3 mesh standards for years But… radio awareness is out-of-scope, significantly limiting opportunity for efficient use of the wireless channel Major focus on large scale and high mobility (hard problems!) has significantly prolonged the standards process IEEE 802. 11 is a reasonable place to create a L 2 mesh subnet standard Allows tight integration with MAC (radio awareness) Has the advantage of creating a mesh that looks like an ethernet to IP applications Improved hooks/statistics for supporting a L 2 mesh can also be used to improve L 3 mesh implementations IETF L 3 mesh network can be used to interconnect multiple IEEE L 2 mesh subnets There is recent precedent for standardizing mesh support in IEEE 802. 16 a already has explicit mesh support Yes, we need improved standard support for mesh in 802. 11! Submission 21 Intel Corporation

Doc. : IEEE 11 -03 -0712 -00 -0 wng September 2003 Fixing the 802. 11 MAC for Mesh We know there are issues with the current 802. 11 MAC, but what about 802. 11 e? EDCF should improve fairness and efficiency TXOPs Block ACK Direct links between clients Multiple queues allow traffic prioritization What are the implications for mesh? Improving MAC in IEEE: Option 1: Start a new study group/task group focused on MAC support for mesh Option 2: Piggyback on current/future non-mesh MAC enhancement efforts (e. g. , 802. 11 n) Submission 22 Intel Corporation