Paper Info
Title
Location-aided uplink transmission for user-centric cell-free massive MIMO systems: a fairness priority perspective
Abstract
In this paper, we investigate the uplink transmission for user-centric cell-free massive multiple-input multiple-output (MIMO) systems. The largest-large-scale-fading-based access point (AP) selection method is adopted to achieve a user-centric operation. Under this user-centric framework, we propose a novel inter-cluster interference-based (IC-IB) pilot assignment scheme to alleviate pilot contamination. Considering the local characteristics of channel estimates and statistics, we propose a location-aided distributed uplink combining scheme to balance the relationship among the spectral efficiency (SE), user equipment (UE) fairness and complexity, in which local partial minimum mean-squared error (LP-MMSE) combining is adopted for some APs, while maximum-ratio (MR) combining is adopted for the remaining APs. A corresponding AP selection scheme based on a novel proposed metric representing inter-user interference is proposed. We also propose a new fairness coefficient taking SE performance into account to indicate the UE fairness. Moreover, the performance of the proposed scheme is investigated under fractional power control and max–min fairness (MMF) power control. Simulation results demonstrate that the channel estimation accuracy of our proposed IC-IB pilot assignment scheme outperforms that of the conventional pilot assignment schemes. It is also shown that compared with the benchmark LP-MMSE combining, the proposed location-aided combining trades 13.45 $$\%$$ average SE loss for 26.61 $$\%$$ UE fairness improvement and 28.58 $$\%$$ complexity reduction when $$\gamma = 0.6$$ . And by adjusting the threshold $$\gamma$$ , a good trade-off between the average SE, UE fairness and computational complexity can be provided by the proposed scheme. Furthermore, the proposed scheme with fractional power control can better demonstrate the advantages of trade-off performance than MMF power control and full power transmission.
Year
DOI
Venue
2022
10.1186/s13638-022-02171-x
EURASIP Journal on Wireless Communications and Networking
Keywords
DocType
Volume
User-centric cell-free massive MIMO, Pilot assignment, Location-aided distributed uplink combining, Low complexity, Fairness
Journal
2022
Issue
ISSN
Citations 
1
1687-1499
0
PageRank 
References 
Authors
0.34
22
6
Name
Order
Citations
PageRank
Wei Chen14919.09
Xu Kui200.34
Shen Zhexian300.34
Xia Xiaochen400.34
Xie Wei500.34
Chunguo Li64810.72