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Geosphere: an Exact Depth-First Sphere Decoder Architecture Scalable to Very Dense Constellations

Georgis, Georgios, Nikitopoulos, Konstantinos and Jamieson, K (2017) Geosphere: an Exact Depth-First Sphere Decoder Architecture Scalable to Very Dense Constellations IEEE Access, 5. pp. 4233-4249.

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This paper presents the algorithmic design, experimental evaluation, and VLSI implementation of Geosphere, a depth-first sphere decoder able to provide the exact maximumlikelihood solution in dense (e.g., 64) and very dense (e.g., 256, 1024) QAM constellations by means of a geometrically inspired enumeration. In general, linear detection methods can be highly effective when the MIMO channel is well-conditioned. However, this is not the case when the size of the MIMO system increases and the number of transmit antennas approaches the number of the receive antennas. Via our WARP testbed implementation we gather indoor channel traces in order to evaluate the performance gains of sphere detection against zero-forcing and MMSE in an actual indoor environment. We show that Geosphere can nearly linearly scale performance with the number of user antennas; in 4 × 4 multi-user MIMO for 256-QAM modulation at 30 dB SNR there is a 1.7× gain over MMSE and 2.4× over zeroforcing and a 14% and 22% respective gain in 2 × 2 systems. In addition, by using a new node labeling based enumeration technique, low-complexity integer arithmetic and fine-grained clock gating, we implement for up to 1024-QAM constellations and compare in terms of area, delay, power characteristics, the Geosphere VLSI architecture and the best-known best-scalable exact ML sphere decoder. Results show that Geosphere is twice as area-efficient and 70% more energy efficient in 1024-QAM. Even for 16-QAM Geosphere is 13% more area efficient than the best-known implementation for 16-QAM and it is at least 80% more area efficient than state-of-the-art K-best detectors for 64-QAM.

Item Type: Article
Subjects : Electronic Engineering
Divisions : Faculty of Engineering and Physical Sciences > Electronic Engineering
Authors :
Jamieson, K
Date : 20 March 2017
Funders : Engineering and Physical Sciences Research Council (EPSRC)
DOI : 10.1109/ACCESS.2017.2684706
Copyright Disclaimer : This work is licensed under a Creative Commons Attribution 3.0 License. For more information, see Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works.
Uncontrolled Keywords : Wireless Communication; MIMO; Application Specific Integrated Circuits; Sphere Decoding; VLSI Implementation
Depositing User : Symplectic Elements
Date Deposited : 31 Mar 2017 15:15
Last Modified : 11 Dec 2018 11:23

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