HaCk: Hierarchical acks for efficient wireless medium utilization

Lynne Salameh, Astrit Zhushi, Mark Handley, Kyle Jamieson, Brad Karp

Research output: Chapter in Book/Report/Conference proceedingConference contribution

3 Scopus citations

Abstract

WiFi's physical layer has increased in speed from 802.11b's 11 Mbps to the Gbps rates of emerging 802.11ac. Despite these gains, WiFi's inefficient MAC layer limits achievable end-to-end throughput. The culprit is 802.11's mandatory idle period before each medium acquisition, which has come to dwarf the duration of a packet's transmission. This overhead is especially punishing for TCP traffic, whose every two data packets elicit a short TCP ACK. Even frame aggregation and block link-layer ACKs (introduced in 802.11n) leave significant medium acquisition overhead for TCP ACKs. In this paper, we propose TCP/HACK (Hierarchical ACKnowledgment), a system that applies cross-layer optimization to TCP traffic on WiFi networks by carrying TCP ACKs within WiFi's link-layer acknowledgments. By eliminating all medium acquisitions for TCP ACKs in unidirectional TCP flows, TCP/HACK significantly improves medium utilization, and thus significantly increases achievable capacity for TCP workloads. Our measurements of a real-time, line-speed implementation for 802.11a on the SoRa software-defined radio platform and simulations of 802.11n networks at scale demonstrate that TCP/HACK significantly improves TCP throughput on WiFi networks.

Original languageEnglish (US)
Title of host publicationProceedings of the 2014 USENIX Annual Technical Conference, USENIX ATC 2014
PublisherUSENIX Association
Pages359-370
Number of pages12
ISBN (Electronic)9781931971102
StatePublished - 2019
Externally publishedYes
Event2014 USENIX Annual Technical Conference, USENIX ATC 2014 - Philadelphia, United States
Duration: Jun 19 2014Jun 20 2014

Publication series

NameProceedings of the 2014 USENIX Annual Technical Conference, USENIX ATC 2014

Conference

Conference2014 USENIX Annual Technical Conference, USENIX ATC 2014
CountryUnited States
CityPhiladelphia
Period6/19/146/20/14

All Science Journal Classification (ASJC) codes

  • Computer Science(all)

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  • Cite this

    Salameh, L., Zhushi, A., Handley, M., Jamieson, K., & Karp, B. (2019). HaCk: Hierarchical acks for efficient wireless medium utilization. In Proceedings of the 2014 USENIX Annual Technical Conference, USENIX ATC 2014 (pp. 359-370). (Proceedings of the 2014 USENIX Annual Technical Conference, USENIX ATC 2014). USENIX Association.