Feedback bit allocation for large distributed antenna systems in indoor WLAN

Q. Wang, D. Debbarma, A. Lo, I.G.M.M. Niemegeers, S. M. Heemstra De Groot

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Samenvatting

Massive MIMO is a key technique for next generation wireless networks due to its potential for significant capacity improvement. To achieve good performance, accurate channel state information (CSI) is needed, especially at the transmitter, to calculate the beamforming matrices. This problem exists for traditional MIMO systems and becomes more challenging for Massive MIMO as the number of antennas is much larger. In this paper, we focus on Massive MIMO with distributed antenna system (DAS) architecture, which we refer as large DAS. In a large DAS, a large number of remote antenna units (RAUs), each equipped with a small antenna array, are distributed over the service area, cooperatively working for beamforming. Due to the large separation of the RAUs, the large scale fading factors of the RAUs for a given mobile station (STA) is different. This effect can be utilized for optimizing the feedback bit allocation considering that more bits should be allocated to dominant signal paths. So we propose two bit allocation algorithms, one that adaptively allocates different bits to the RAUs according to the large scale fading, termed adaptive allocation; and the other that allocates equal bits to a set of RAUs, termed equal allocation. They are applied for centralized and de-centralized zero-forcing beamforming (C- and D-ZFBF) respectively. The results show that with a proper bit allocation, the data rates can approximate that of perfect CSI with limited feedback rate. For C-ZFBF, adaptive allocation performs better than equal allocation with medium feedback rates, and similarly for low and high feedback rates. For D-ZFBF, adaptive allocation and equal allocation offer similar results.

Originele taal-2Engels
Titel2015 IEEE Symposium on Communications and Vehicular Technology in the Benelux, SCVT 2015, 24 November 2015, Luxembourg, Luxembourg
Plaats van productiePiscataway
UitgeverijInstitute of Electrical and Electronics Engineers
Pagina's1-6
ISBN van elektronische versie978-1-4673-9907-4
DOI's
StatusGepubliceerd - 6 jan 2016
Evenement22nd IEEE Symposium on Communications and Vehicular Technology in the BeNeLux (IEEE SCVT 2015) - Luxembourg, Luxemburg
Duur: 24 nov 201524 nov 2015
Congresnummer: 22

Congres

Congres22nd IEEE Symposium on Communications and Vehicular Technology in the BeNeLux (IEEE SCVT 2015)
Verkorte titelSCVT 2015
LandLuxemburg
StadLuxembourg
Periode24/11/1524/11/15

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Wang, Q., Debbarma, D., Lo, A., Niemegeers, I. G. M. M., & Heemstra De Groot, S. M. (2016). Feedback bit allocation for large distributed antenna systems in indoor WLAN. In 2015 IEEE Symposium on Communications and Vehicular Technology in the Benelux, SCVT 2015, 24 November 2015, Luxembourg, Luxembourg (blz. 1-6). [7374230] Piscataway: Institute of Electrical and Electronics Engineers. https://doi.org/10.1109/SCVT.2015.7374230