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ARQ Proxy (for WiFi networks)

Ischia island, Italy Sept. 11, 2007. ARQ Proxy (for WiFi networks). Dzmitry Kliazovich Nadhir Ben Halima Fabrizio Granelli University of Trento, Italy. TCP Data. PHY. LL. TCP Data. Headers. Headers. LL. -. ACK. Legend:. Transmitted at Basic rate. Channel Contention.

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ARQ Proxy (for WiFi networks)

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  1. Ischia island, Italy Sept. 11, 2007 ARQ Proxy(for WiFi networks) Dzmitry Kliazovich Nadhir Ben Halima Fabrizio Granelli University of Trento, Italy

  2. TCP Data PHY LL TCP Data Headers Headers LL - ACK Legend: Transmitted at Basic rate Channel Contention Transmitted at Data rate LL PHY TCP ACK Headers Headers LL - ACK TCP ACK TCP over Infrastructure WiFi WiFi (IEEE 802.11) IP Network Base Station Mobile Node (BS) (MN) Application Data Channel Contention Acknowledgements at different layers Dzmitry Kliazovich (kliazovich@dit.unitn.it)

  3. ARQ Proxy - Approach • Idea: Substitute the transmission of TCP ACK packets with a short MAC layer request on the radio link for multilayer ARQ overhead reduction Dzmitry Kliazovich (kliazovich@dit.unitn.it)

  4. TCP PHY / LL Data Headers TCP Data LL - ACK TCP ACK TCP Data ARQ Proxy - Approach IP Network Fixed Host Base Station Mobile Node ( FH ) (BS) (MN) Proxy ARQ TCP MAC MAC ARQ Client TCP • Access TCP header • Get IP addr, port, etc. • Generate TCP ACK & store Generate TCP ACK TCP ACK Index TCP ACK Index • Compute TCP ACK identification index Dzmitry Kliazovich (kliazovich@dit.unitn.it)

  5. LL - ACK ARQ Proxy – Packet Identification • Frame Sequence Numbers • Hash values PHY LL TCP data Header Header Sequence Address 3 Address 4 Control B15 B0 B3 B4 Fragment Sequence Number Number 4 12 Bits: • Link layer ACK (LL-ACK) or Base Station Mobile Node (BS) (MN) Dzmitry Kliazovich (kliazovich@dit.unitn.it)

  6. TCP Data PHY LL TCP Data Headers Headers LL - ACK Channel Contention LL PHY TCP ACK Headers Headers LL - ACK TCP ACK ARQ Proxy - Benefits • Performance and System Capacity Increase WiFi (IEEE 802.11) IP Network Base Station Mobile Node (BS) (MN) Channel Contention Overhead reduction Dzmitry Kliazovich (kliazovich@dit.unitn.it)

  7. TCP ACK TCP Data ARQ Proxy - Benefits • Reduced RTT (Round Trip Time) IP Network Fixed Host Base Station Mobile Node ( FH ) (BS) (MN) Medium Access + TCP ACK Transmission over wireless channel Dzmitry Kliazovich (kliazovich@dit.unitn.it)

  8. LL- ACK TCP ACK TCP Data ARQ Proxy - Benefits • End-to-end TCP semantics are maintained IP Network Fixed Host Base Station Mobile Node ( FH ) (BS) (MN) Dzmitry Kliazovich (kliazovich@dit.unitn.it)

  9. TCP ACK ARQ Proxy - Benefits • Higher channel error rates tolerance Wired channel(BER = 10-6 to 10-8) Wireless channel(BER = 10-3 to 10-1) IP Network Fixed Host Base Station Mobile Node ( FH ) (BS) (MN) No TCP ACK over wireless channel Dzmitry Kliazovich (kliazovich@dit.unitn.it)

  10. ARQ Proxy - Benefits • Mobility & Incremental deployment No TCP state related information is maintained IP Network Fixed Host Base Station Mobile Node ( FH ) (BS) (MN) Proxy ARQ ARQ Client Dzmitry Kliazovich (kliazovich@dit.unitn.it)

  11. ARQ Proxy - Benefits • Performance and system capacity increase • Reduced RTT (Round Trip Time) • End-to-end TCP semantics are maintained • Higher channel error rates tolerance • Full mobility support • Incremental deployment & Co-existence Dzmitry Kliazovich (kliazovich@dit.unitn.it)

  12. ARQ Proxy - Limitations • TCP ACKs are not substituted: • During connection establishment and connection termination packets (identified by SIN and FIN flags) • For TCP ACK encapsulated into TCP data packet in case of bidirectional data transfer • For Duplicate TCP ACKs • TCP ACK advertising exhausted receive buffer resources (rwnd field) Dzmitry Kliazovich (kliazovich@dit.unitn.it)

  13. Proxy ARQ ARQ Client Evaluation Results • Simulation Setup • Ns2 simulator with ARQ proxy extensions • IEEE 802.11b physical layer, no RTS/CTS • Bottleneck buffer: 700 packets • TCP NewReno flows • Results averaged over 10 runs IEEE 802.11b @ 11 Mb/s 100 Mb/s, 15 ms Fixed Host Base Station Mobile Node Dzmitry Kliazovich (kliazovich@dit.unitn.it)

  14. Evaluation Results • Throughput performance Improvement: 20% Improvement:up to 100% VoIP and MultimediaApplications TCP file transfer, Ethernet MTU Dzmitry Kliazovich (kliazovich@dit.unitn.it)

  15. Evaluation Results • Round Trip Time (RTT) improvement Order of milliseconds Dzmitry Kliazovich (kliazovich@dit.unitn.it)

  16. Evaluation Results • High error rate tolerance Dzmitry Kliazovich (kliazovich@dit.unitn.it)

  17. Motivation for Scenario Choice • Why link layer ARQ as a feedback channel? • Why TCP? • Accounts for more than 85% of Internet traffic* • Why Infrastructure network scenario? • Over 95% of wireless links are on the last mile [*] C. Fraleigh at el. “Packet-level traffic measurements from the Sprint IP backbone,” IEEE Network, vol. 17, no. 6, pp. 6 – 16, Nov.-Dec. 2003. Dzmitry Kliazovich (kliazovich@dit.unitn.it)

  18. . . . Other Operation Scenarios ARQ Proxy • Single-hop Ad hoc network ARQ Proxy • Multi-hop network ARQ Proxy Fixed Source Fixed Network Infrastructure • Infrastructure network with relays Dzmitry Kliazovich (kliazovich@dit.unitn.it)

  19. ARQ Proxy for 3G LTE • 3G Long-Term Evolution (LTE) • Key features • Evolved radio access: OFDM, multiple antenna techniques • Evolved architecture: fewer nodes, reduced latency, low cost • Evolved networking: All-IP architecture, shared resources Dzmitry Kliazovich (kliazovich@dit.unitn.it)

  20. TCP ACK Generation TCP ACK Sniff ARQ Output Client queue TCP ACK Hash value MAC HARQ HARQ ACK + TCP Data ARQ Proxy for 3G LTE • ARQ Proxy: Use Hybrid ARQ (HARQ) feedback to substitute TCP ACK packets on the radio channel • Hash values for packet identification Protocol stack at the receiver Dzmitry Kliazovich (kliazovich@dit.unitn.it)

  21. Evaluation: 3G LTE scenario • Setup • Ns2 with Enhanced UMTS Radio Access Extensions (EURAE) • eNB and RNC are combined into a single node • Rayleigh fading with 300 meters between UE and eNB • Encapsulation overhead: TCP (20 bytes), IP (20 bytes), PDCP (1 byte), RLC (2 bytes), and PHY CRC (2 bytes) • Hash value size: 32 bits • TCP NewReno sources • Metrics • Throughput and Round Trip Time (RTT) performance with different error rates Dzmitry Kliazovich (kliazovich@dit.unitn.it)

  22. Evaluation: 3G LTE scenario • Round Trip Time (RTT) • Hash value errors Dzmitry Kliazovich (kliazovich@dit.unitn.it)

  23. Current Activities and Future Work • ARQ proxy material (Available) • ARQ proxy for WiFi (IEEE 802.11) • ARQ proxy for 3G LTE (Super-3G) • EU patent-pending • D. Kliazovich, F. Granelli, S. Redana and N. Riato, “Cross-Layer Error Control Optimization in 3G LTE,” IEEE Global Communications Conference (GLOBECOM), Washington, DC, U.S.A, December 2007. • D. Kliazovich, F. Granelli, S. Redana, and N. Riato, “Cross-Layer Error Recovery Optimization for 3G LTE Systems,” EP 07425087.9 Dzmitry Kliazovich (kliazovich@dit.unitn.it)

  24. Current Activities and Future Work • ARQ proxy material (Coming soon…) • ARQ proxy for WiMAX (IEEE 802.16) • Adaptation and system level simulations • Proposal to 3GPP standardization group • Under consideration for next generation equipment produced by Nokia Siemens Network (NSN) Dzmitry Kliazovich (kliazovich@dit.unitn.it)

  25. Thank you! Dzmitry Kliazovich (kliazovich@dit.unitn.it)

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