1. “WOMEN” Project Final Meeting Trento, Feb. 12th, 2008 1 UNITN: Description of Work Fabrizio Granelli DISI – University of Trento granelli@disi.unitn.it

2. “WOMEN” Project Final Meeting Trento, Feb. 12th, 20082 UNITN role in a slide 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.)

3. “WOMEN” Project Final Meeting Trento, Feb. 12th, 2008 3 UNITN: Research Activities

4. “WOMEN” Project Final Meeting Trento, Feb. 12th, 20084 T3.4 “Stream Control” PAC-IP  Concatenate IP packets into a single link layer payload  Share wireless overhead by entire group of packets SenderReceiver Link Physical Network

5. “WOMEN” Project Final Meeting Trento, Feb. 12th, 20085 PAC-IP: Possible Implementations

6. “WOMEN” Project Final Meeting Trento, Feb. 12th, 20086 Evaluation Results Simulation  Ns-2 network simulator No need to change Link or Transport layers Good performance for small (< 750 bytes) packets Testbed  Modified Orinoco Silver card’s driver  Iperf traffic generator Concatenation ON Concatenation OFF

7. “WOMEN” Project Final Meeting Trento, Feb. 12th, 20087 TCP Performance Enhancement: TCP LogWestwood+ Design Objectives  To be more aggressive than Standard TCP to guarantee equal or better throughput and utilization  Fast increase for low window values while accurately approach the available pipe capacity  Small sensitivity with respect to RTT TCP LogWestwood+ combines smart TCP Westwood window decrease with Logarithmic increase function Ref.: D. Kliazovich, F. Granelli, and D. Miorandi, "TCP Westwood+ Enhancements for High-Speed Long- Distance Networks,“ ICC'06.

8. “WOMEN” Project Final Meeting Trento, Feb. 12th, 20088 TCP LogWestwood+ Logarithmic Linear AIMD (Standard TCP) On packet loss (3 dup ACKs)  =  * 2, if W < W max  =  / 2, if W ≥ W max  ≥ 2 (initial value) Window Control during congestion avoidance  Wmax – window size before the last packet loss occurred

9. “WOMEN” Project Final Meeting Trento, Feb. 12th, 20089 TCP LogWestwood+: Performance Window Evolution Physical Capacity Total Capacity (+Buffers) 2 Total Capacity

10. “WOMEN” Project Final Meeting Trento, Feb. 12th, 200810 Quantifying Cross-layer Design Quantifying the effect of potential cross-layer interactions is very important  to systematically relate such interactions to system outcomes  to quantify the decision to take such interactions into account We propose to quantify cross layer interactions by defining factors (parameters) and effects (measurements) across layers  in a way that is common in system science and operations research Ref.: F. Granelli, M. Devetsikiotis, “Designing Cross-Layering Solutions for Wireless Networks: a General Framework and Its Application to a Voice-over-WiFi Scenario,” CAMAD 2006.

11. “WOMEN” Project Final Meeting Trento, Feb. 12th, 200811 Quantifying Cross-layer Design Cross-Layer Sensitivity and Performance Optimization

12. “WOMEN” Project Final Meeting Trento, Feb. 12th, 200812 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 Network Capacity Analysis: goal

13. “WOMEN” Project Final Meeting Trento, Feb. 12th, 200813 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)

14. “WOMEN” Project Final Meeting Trento, Feb. 12th, 200814 Connectivity analysis No. of forwarding nodes * Poisson distribution: λ = n f * → “Optimal Transmission Ranges for Randomly Distributed Packet Radio Terminals”, by Takagi e Kleinrock (March 1984)

15. “WOMEN” Project Final Meeting Trento, Feb. 12th, 200815 Connectivity analysis

16. “WOMEN” Project Final Meeting Trento, Feb. 12th, 200816 Capacity Analysis n i →connected nodes at i-hops distance from the BS

17. “WOMEN” Project Final Meeting Trento, Feb. 12th, 200817 Experimental Results: Capacity Averaged on 50 runs variable n l = 2500 r = 250 Avg. error: 17,53 % Avg. stdev: 22,85 % [kbit/sec]

18. “WOMEN” Project Final Meeting Trento, Feb. 12th, 200818 Conclusions A first model for connectivity and capacity of WMNs was developed and validated Good accuracy Open Points:  Inter-cell interference  Heterogeneous WMN (e.g. WiMAX+WiFi)  Node movement (statistical model)

19. “WOMEN” Project Final Meeting Trento, Feb. 12th, 200819 TCP over Infrastructure WiFi LL-ACKTCP Data Mobile Node (MN) Base Station (BS) Channel Contention LL-ACKTCPACK WiFi (IEEE 802.11) IP Network TCP Data PHY Headers LL Headers TCP ACK PHY Headers LL Headers Legend: Transmitted at Basic rate Transmitted at Data rate Application Data Acknowledgements at different layers

20. “WOMEN” Project Final Meeting Trento, Feb. 12th, 200820 ARQ Proxy - Approach Idea: To substitute the transmission of TCP ACK packets with a short MAC layer request on the radio link for multilayer ARQ overhead reduction

21. “WOMEN” Project Final Meeting Trento, Feb. 12th, 200821 ARQ Proxy - Approach TCP Data PHY/LL Headers LL-ACK Fixed Host (FH) IP Network ARQ Proxy MACARQ ClientMACTCP TCP Data Mobile Node (MN) Base Station (BS) TCP o Access TCP header o Get IP addr, port, etc. o Generate TCP ACK & store o Compute TCP ACK identification index Generate TCP ACK Index TCP DataTCPACK TCP ACK Index

22. “WOMEN” Project Final Meeting Trento, Feb. 12th, 200822 ARQ Proxy - Benefits Performance and System Capacity Increase LL-ACK TCP Data Mobile Node (MN) Base Station (BS) Channel Contention LL-ACK TCPACK WiFi (IEEE 802.11) IP Network TCP Data PHY Headers LL Headers TCP ACK PHY Headers LL Headers Overhead reduction

23. “WOMEN” Project Final Meeting Trento, Feb. 12th, 200823 Evaluation Results Throughput performance Improvement: 20% Improvement: up to 100% VoIP and Multimedia Applications TCP file transfer, Ethernet MTU

24. “WOMEN” Project Final Meeting Trento, Feb. 12th, 200824 Evaluation Results Round Trip Time (RTT) improvement Order of milliseconds

25. “WOMEN” Project Final Meeting Trento, Feb. 12th, 200825 Evaluation Results High error rate tolerance

26. “WOMEN” Project Final Meeting Trento, Feb. 12th, 2008 26 UNITN: Testbed Activities

27. “WOMEN” Project Final Meeting Trento, Feb. 12th, 2008 RoofNet - Main Features:  Wireless Mesh Networking SW developed by MIT (based on Click Modular Router architecture)  Multi-hop transmission  Optimized routing using a specific metric Limitations:  Need for WiFi cards with Atheros chipset  Madwifi driver Goal:  To port RoofNet to any hw/sw platform Testbed Development

28. “WOMEN” Project Final Meeting Trento, Feb. 12th, 2008 RoofNet - Why dedicated HW?  Probe transmission for link quality measurements in broadcast mode at arbitrary rate  BSSID partitioning  Routing metric is calculated by ETT ETT = ETX * S/B (S=data size, B=used bandwidth) Problem:  IEEE 802.11 does not enable arbitrary rate in broadcast signalling Testbed Development

29. “WOMEN” Project Final Meeting Trento, Feb. 12th, 2008  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 flags = 0; power = 60; rssi = 8; rate = 2; retries = 0; “BlankDecap” module settings Roofnet Modifications

30. “WOMEN” Project Final Meeting Trento, Feb. 12th, 200830 Service differentiation in Wi-Fi based Wireless Mesh Networks System architecture Layer 2.5: interposition layer with own headers ToS byte-based IP packet classification Four classes with dedicated buffering modifiedWeighted Round Robin scheme Transmissions scheduled by a modified Weighted Round Robin scheme Software architecture Click modular router Roofnet WMN features Elements added as C++ code from Network Layer to MAC layer Layer 2.5 Routing probes

31. “WOMEN” Project Final Meeting Trento, Feb. 12th, 200831 Experimental validation: results 1 hop 2 hops  UDP noise (diff)  UDP noise (no diff)  TCP hi-priority (no diff)  TCP hi-priority (diff) Data-set C  hi-priority TCP flow in class 4  UDP noise in class 1 at increasing bitrates Figure 1: TCP resistance to UDP noise comparison (1 hop) Figure 2: TCP resistance to UDP noise comparison (2 hops)

32. “WOMEN” Project Final Meeting Trento, Feb. 12th, 200832 Experimental validation: results Issues: 1. Traffic generator issue:  TCP ACKS with ToS not set  differentiation only on the feed-forward and not on the feed-back  ACKS scheduled with the lowest priority 2. Differentiation at Layer 2.5:  Hi priority flows may lose MAC contentions with low priority flows

33. “WOMEN” Project Final Meeting Trento, Feb. 12th, 200833 WOMEN Testbed Implementation

34. “WOMEN” Project Final Meeting Trento, Feb. 12th, 200834 AP3 AP4 AP6 AP5 AP2 AP1 Control Data WOMEN Testbed Implementation

35. “WOMEN” Project Final Meeting Trento, Feb. 12th, 200835 AP5 AP4 AP2 AP1 AP3 X X X XX WOMEN Testbed Implementation

36. “WOMEN” Project Final Meeting Trento, Feb. 12th, 200836 AP6 X WOMEN Testbed Implementation

37. “WOMEN” Project Final Meeting Trento, Feb. 12th, 2008 37 UNITN: Dissemination

38. “WOMEN” Project Final Meeting Trento, Feb. 12th, 200838 Dissemination activities - Project 11th Intenational Workshop on Computer-Aided Modeling, Analysis and Design of Communication Links and Networks (CAMAD 2006, Trento, June 8-9, 2006)  WOMEN leaflet  CAMAD’06 website, dinner ticket  Contribution to organization

39. “WOMEN” Project Final Meeting Trento, Feb. 12th, 200839 Dissemination activities - Papers D. Kliazovich, F. Granelli, G. Pau, and M. Gerla "APOHN: Subnetwork Layering to Improve TCP Performance over Heterogeneous Paths,“ IEEE Next Generation Internet Design and Engineering (NGI), Valencia, Spain, April 2006. D. Kliazovich, F. Granelli, and D. Miorandi "TCP Westwood+ Enhancements for High-Speed Long-Distance Networks,“ IEEE International Conference on Communications (ICC'06), Istanbul, Turkey, June 2006. F. Granelli, M. Devetsikiotis “Designing Cross-Layering Solutions for Wireless Networks: a General Framework and Its Application to a Voice-over-WiFi Scenario,” CAMAD 2006, June 8-9, 2006, pp. 1-7. C.E. Costa, F. Granelli, "Optimal power control for embedded packet video transmission over WiFi“, 1st Workshop on multiMedia Applications over Wireless Networks (MediaWIN 2006), Athens, Greece, April 2nd, 2006.

40. “WOMEN” Project Final Meeting Trento, Feb. 12th, 200840 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. D. Kliazovich, N. Ben Halima, F. Granelli, "Cross-layer error recovery optimization in WiFi networks“, 2007 Tyrrhenian International Workshop on Digital Communications (TIWDC 2007), Island of Ischia, Italy, Sept. 9-12, 2007. R. Riggio, N. Scalabrino, D. Miorandi, F. Granelli, Y. Fang, E. Gregori, I. Chlamtac, "Hardware and Software Solutions for Wireless Mesh Networks Testbeds“ submitted to IEEE Communications Magazine (minor revision requested). D. Kliazovich, F. Granelli, D. Miorandi, "Logarithmic Window Increase for TCP Westwood+ for Improvement in High Speed, Long Distance Networks“, submitted to Computer Networks Journal (minor revision requested).