Abstract
| Original language | English |
|---|---|
| Article number | 8428665 |
| Pages (from-to) | 6630-6644 |
| Journal | IEEE Transactions on Wireless Communications |
| Volume | 17 |
| Issue number | 10 |
| DOIs | |
| Publication status | Published - Oct 2018 |
| MoE publication type | A1 Journal article-refereed |
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Keywords
- downlink performance
- Massive MIMO
- pilot contamination
- staggered pilots
- superimposed pilots
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Downlink performance of superimposed pilots in massive MIMO systems. / Upadhya, Karthik; Vorobyov, Sergiy A.; Vehkapera, Mikko.
In: IEEE Transactions on Wireless Communications, Vol. 17, No. 10, 8428665, 10.2018, p. 6630-6644.Research output: Contribution to journal › Article › Scientific › peer-review
TY - JOUR
T1 - Downlink performance of superimposed pilots in massive MIMO systems
AU - Upadhya, Karthik
AU - Vorobyov, Sergiy A.
AU - Vehkapera, Mikko
PY - 2018/10
Y1 - 2018/10
N2 - In this paper, we investigate the downlink throughput performance of a massive multiple-input multiple-output system that employs superimposed pilots for channel estimation. The component of downlink (DL) interference that results from transmitting data alongside pilots in the uplink (UL) is shown to decrease at a rate proportional to the square root of the number of antennas at the BS when the least-squares channel estimate is employed in a matched-filter precoder. The normalized mean-squared error (NMSE) of the channel estimate is compared with the Bayesian Cramér-Rao lower bound that is derived for the system, and the former is also shown to diminish with increasing number of antennas at the base station. Furthermore, we show that staggered pilots are a particular case of superimposed pilots and offer the downlink throughput of superimposed pilots while retaining the UL spectral and energy efficiency of regular pilots. We also extend the framework for designing a hybrid system, consisting of users that transmit either regular or superimposed pilots, to minimize both the UL and DL interference. The improved NMSE and DL rates of the channel estimator based on superimposed pilots are demonstrated by means of simulations.
AB - In this paper, we investigate the downlink throughput performance of a massive multiple-input multiple-output system that employs superimposed pilots for channel estimation. The component of downlink (DL) interference that results from transmitting data alongside pilots in the uplink (UL) is shown to decrease at a rate proportional to the square root of the number of antennas at the BS when the least-squares channel estimate is employed in a matched-filter precoder. The normalized mean-squared error (NMSE) of the channel estimate is compared with the Bayesian Cramér-Rao lower bound that is derived for the system, and the former is also shown to diminish with increasing number of antennas at the base station. Furthermore, we show that staggered pilots are a particular case of superimposed pilots and offer the downlink throughput of superimposed pilots while retaining the UL spectral and energy efficiency of regular pilots. We also extend the framework for designing a hybrid system, consisting of users that transmit either regular or superimposed pilots, to minimize both the UL and DL interference. The improved NMSE and DL rates of the channel estimator based on superimposed pilots are demonstrated by means of simulations.
KW - downlink performance
KW - Massive MIMO
KW - pilot contamination
KW - staggered pilots
KW - superimposed pilots
UR - http://www.scopus.com/inward/record.url?scp=85051399206&partnerID=8YFLogxK
U2 - 10.1109/TWC.2018.2861770
DO - 10.1109/TWC.2018.2861770
M3 - Article
AN - SCOPUS:85051399206
VL - 17
SP - 6630
EP - 6644
JO - IEEE Transactions on Wireless Communications
JF - IEEE Transactions on Wireless Communications
SN - 1536-1276
IS - 10
M1 - 8428665
ER -