Salameh, L;
Zhushi, A;
Handley, M;
Jamieson, K;
Karp, B;
(2014)
HACK: Hierarchical ACKs for Efficient Wireless Medium Utilization.
In: Gibson, G and Zeldovich, N, (eds.)
Proceedings of USENIX ATC ’14: 2014 USENIX Annual Technical Conference.
(pp. pp. 359-370).
USENIX Association
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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 signifi- cant 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.
| Type: | Proceedings paper |
|---|---|
| Title: | HACK: Hierarchical ACKs for Efficient Wireless Medium Utilization |
| Event: | USENIX ATC ’14, USENIX Annual Technical Conference, 19-20 June 2014, Philadelphia, USA |
| ISBN-13: | 9781931971102 |
| Open access status: | An open access version is available from UCL Discovery |
| Publisher version: | https://www.usenix.org/conference/atc14/technical-... |
| Language: | English |
| Additional information: | This is the published version of record. For information on re-use, please refer to the publisher’s terms and conditions. |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Computer Science |
| URI: | https://discovery.ucl.ac.uk/id/eprint/1452481 |
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