Geosphere: Consistently turning MIMO capacity into throughput

Konstantinos Nikitopoulos, Juan Zhou, Ben Congdon, Kyle Jamieson

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

12 Scopus citations

Abstract

This paper presents the design and implementation of Geosphere, a physical- and link-layer design for access point-based MIMO wireless networks that consistently improves network throughput. To send multiple streams of data in a MIMO system, prior designs rely on a technique called zero-forcing, a way of "nulling" the interference between data streams by mathematically inverting the wireless channel matrix. In general, zero-forcing is highly effective, significantly improving throughput. But in certain physical situations, the MIMO channel matrix can become "poorly conditioned," harming performance. With these situations in mind, Geosphere uses sphere decoding, a more computationally demanding technique that can achieve higher throughput in such channels. To overcome the sphere decoder's computational complexity when sending dense wireless constellations at a high rate, Geosphere introduces search and pruning techniques that incorporate novel geometric reasoning about the wireless constellation. These techniques reduce computational complexity of 256-QAM systems by almost one order of magnitude, bringing computational demands in line with current 16- and 64-QAM systems already realized in ASIC. Geosphere thus makes the sphere decoder practical for the first time in a 4 x 4 MIMO, 256-QAM system. Results from our WARP testbed show that Geosphere achieves throughput gains over multi-user MIMO of 2x in 4 x 4 systems and 47% in 2 x 2 MIMO systems.

Original languageEnglish (US)
Title of host publicationSIGCOMM 2014 - Proceedings of the 2014 ACM Conference on Special Interest Group on Data Communication
PublisherAssociation for Computing Machinery
Pages631-642
Number of pages12
ISBN (Print)9781450328364
DOIs
StatePublished - Jan 1 2014
Externally publishedYes
Event2014 ACM Conference on Special Interest Group on Data Communication, SIGCOMM 2014 - Chicago, IL, United States
Duration: Aug 17 2014Aug 22 2014

Publication series

NameSIGCOMM 2014 - Proceedings of the 2014 ACM Conference on Special Interest Group on Data Communication

Other

Other2014 ACM Conference on Special Interest Group on Data Communication, SIGCOMM 2014
CountryUnited States
CityChicago, IL
Period8/17/148/22/14

All Science Journal Classification (ASJC) codes

  • Computer Science Applications

Keywords

  • MIMO
  • distributed MIMO
  • sphere decoder

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  • Cite this

    Nikitopoulos, K., Zhou, J., Congdon, B., & Jamieson, K. (2014). Geosphere: Consistently turning MIMO capacity into throughput. In SIGCOMM 2014 - Proceedings of the 2014 ACM Conference on Special Interest Group on Data Communication (pp. 631-642). (SIGCOMM 2014 - Proceedings of the 2014 ACM Conference on Special Interest Group on Data Communication). Association for Computing Machinery. https://doi.org/10.1145/2619239.2626301