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Analytical Modeling for Wireless Mesh Networks Performance Enhancement

This project focuses on developing an analytical model to enhance the performance of Wireless Mesh Networks. Key research activities include capacity analysis and connectivity validation. Experimental results and conclusions highlight the accuracy and future considerations for network improvements.

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Analytical Modeling for Wireless Mesh Networks Performance Enhancement

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  1. UNITN Research Unit Status of the Work – First Year Fabrizio Granelli DIT – University of Trento granelli@dit.unitn.it “WOMEN” Project Meeting Rome, Jan. 19th, 2007

  2. Ongoing activities UNITN role in the project • Goal: “Performance Enhancement of Wireless Mesh Networks and Testbed Implementation” • WP1 • WP3 • T3.4 Stream Control • WP4 • T4.5 Network Capacity Analysis • WP5 (Resp.) • T5.6 (Testbed) (Resp.) • T5.7 (Trials) (Resp.) “WOMEN” Project Meeting Rome, Jan. 19th, 2007

  3. Network Capacity Analysis: goal • To define and validate an analytical model for connectivity and capacity of Wireless Mesh Networks, given design parameters n,r, l. • Traffic from/to mesh base station ≠ ad-hoc scenario E. Miorando, F. Granelli, “On Connectivity and Capacity of Wireless Mesh Networks”, ICC 2007, accepted “WOMEN” Project Meeting Rome, Jan. 19th, 2007

  4. Problem Statement n → # nodes (random distribution) S → squared area of dimension l x l m → # access points r → comm range nn → # neighbor nodes nf → # forwarding nodes “WOMEN” Project Meeting Rome, Jan. 19th, 2007

  5. Problem Statement • Single-cell analysis • → squared area • → m = 1 • → interfering nodes • Traffic to/from BS • Hyp.:→ IEEE 802.11 CSMA/CA – RTS/CTS* • → MFR routing • → r = 250 [m] * → “Performance Analysis of the IEEE 802.11 Distributed Coordination Function”, by G. Bianchi (JSAC, March 2000) “WOMEN” Project Meeting Rome, Jan. 19th, 2007

  6. Connectivity analysis No. offorwarding nodes* Poisson distribution: λ = nf * → “Optimal Transmission Ranges for Randomly Distributed Packet Radio Terminals”, by Takagi e Kleinrock (March 1984) “WOMEN” Project Meeting Rome, Jan. 19th, 2007

  7. Connectivity analysis “WOMEN” Project Meeting Rome, Jan. 19th, 2007

  8. Capacity analysis G G G G G G G G 1 2 3 4 5 6 7 8 G 2G 3G 4G 5G 6G 7G 8G • Bottleneck* • Bottleneck collision domain* * → “The Nominal Capacity of Wireless Mesh Networks”, by Jun e Sichitiu (Oct. 2003) “WOMEN” Project Meeting Rome, Jan. 19th, 2007

  9. Capacity Analysis ni→ connected nodes at i-hops distance from the BS “WOMEN” Project Meeting Rome, Jan. 19th, 2007

  10. Validation of the Approach • NS-2 simulator (v. 2.29) → C++ e OTcl • No WMN support → WiFi@11Mbps set tcp [new Agent/TCP] $tcp set class_ 2 set sink [new Agent/TCPSink] $ns_ attach-agent $node_(11) $tcp $ns_ attach-agent $node_(19) $sink $ns_ connect $tcp $sink set ftp [new Application/FTP] $ftp attach-agent $tcp $ns_ at 100.0 "$ftp start" “WOMEN” Project Meeting Rome, Jan. 19th, 2007

  11. Experimental Results: pconn • Averaged on 50 runs • variable n l = 2500 r = 250 • Max error: 2,25 % • Avg. stdev: 8,15 % “WOMEN” Project Meeting Rome, Jan. 19th, 2007

  12. Experimental Results: Capacity • Averaged on 50 runs • variable n l = 2500 r = 250 • Avg. error: 17,53 % • Avg. stdev: 22,85 % [kbit/sec] “WOMEN” Project Meeting Rome, Jan. 19th, 2007

  13. Experimental Results: Capacity • Averaged on 20 runs • variable n l = 2500 r = 250 • Avg. error: 6,37 % • Avg. stdev: 17,55 % • Averaged on 20 runs • variable n l = 2500 r = 250 • Avg. error: 15,51 % • Avg. stdev: 22,15 % [kbit/sec] “WOMEN” Project Meeting Rome, Jan. 19th, 2007

  14. Conclusions • A first model for connectivity and capacity of WMNs was developed and validated • Good accuracy • Points to consider: • Inter-cell interference • Heterogeneous WMN (e.g. WiMAX+WiFi) • Node movement (statistical model) “WOMEN” Project Meeting Rome, Jan. 19th, 2007

  15. UNITN / CREATE-NET testbed “WOMEN” Project Meeting Rome, Jan. 19th, 2007

  16. Testbed: where are we? • Started from Roofnet, making it device-agnostic: • Monitor mode  ad hoc mode • Link quality evaluation using ETX • Roofnet on laptops works! • Roofnet patch available on WOMEN website “WOMEN” Project Meeting Rome, Jan. 19th, 2007

  17. Testbed: where are we? • Software porting to openwrt successful • Automatic Gateway Discovery working • Meraki (Roofnet spin-off) openwrt platform freely available • Click in userspace running on 200MHz CPUs • 802.11 working in b mode “WOMEN” Project Meeting Rome, Jan. 19th, 2007

  18. Preamble management in Click Click modules: • Read RSSI, noise, bitrate, etc. from incoming packet • Translate ingoing IEEE 802.11 packet into a Ethernet frame • Set rate and transmission power of the outgoing packet “WOMEN” Project Meeting Rome, Jan. 19th, 2007

  19. Roofnet Modifications • Change from monitor mode to ad-hoc mode (supported by any IEEE 802.11 NIC) • Introduction of an element for static setting of preamble parameters • link-quality evaluation using ETX “BlankDecap” module settings flags = 0; power = 60; rssi = 8; rate = 2; retries = 0; “WOMEN” Project Meeting Rome, Jan. 19th, 2007

  20. SCHEDULER prototypes • First prototype - COMPLETED: • Priority scheduling based (WRR) • Works for TCP/UDP (2 hops test) • Second prototype – WORK IN PROGRESS: • TRADE-OFF UTILIZATION/FAIRNESS • Priority scheduling based (WRR) • RED queuing policies (avoid drop-tail) ? • Fairness idea: use deficit queues (one for each service class) which provides FQ fairness • Channel awareness ? • Channel measurements -> long implementation • proper temporal scale to avoid fading and multipath phenomena “WOMEN” Project Meeting Rome, Jan. 19th, 2007

  21. Measurement platform (completed) • Set of bash scripts for: • Automatic ssh key distribution among nodes • Tcp and udp bi-directional distributed measurements (iperf) • Throughput • Jitter • delay • Results collection and post-processing • Can launch arbitrary unix commands on remote nodes “WOMEN” Project Meeting Rome, Jan. 19th, 2007

  22. Dissemination activities - Papers • E. Miorando, and F. Granelli"On Connectivity and Capacity of Wireless Mesh Networks,“IEEE International Conference on Communications (ICC’07), Glasgow, Scotland, June 2007 (accepted). • D. Kliazovich, F. Granelli and D. Miorandi“Logarithmic Window Increase for TCP Westwood+ Improvement in High Speed, Long Distance Networks,”Computer Networks (submitted). “WOMEN” Project Meeting Rome, Jan. 19th, 2007

  23. UNITN Research UnitFuture Activities Fabrizio Granelli DIT – University of Trento granelli@dit.unitn.it “WOMEN” Project Meeting Rome, Jan. 19th, 2007

  24. Activities in the 2nd Year • Finalization of Network Capacity Analysis • Testbed Design: • Partially @CreateNet, partially @UniTN + WiMAX-like long distance link • Frequency allocation @UniTN • Testbed Implementation: • Second prototype design and programming • Testbed deployment • Tests on testbed • Results collection and analysis “WOMEN” Project Meeting Rome, Jan. 19th, 2007

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