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. 2023 Jun 2;23(11):5285.
doi: 10.3390/s23115285.

A Left-Null-Space-Based Massive Access Method for Cell-Free Massive MIMO IoT Systems

Yang Wang  1 , Die Hu  1
Affiliations

A Left-Null-Space-Based Massive Access Method for Cell-Free Massive MIMO IoT Systems

Yang Wang et al. Sensors (Basel). .

Abstract

Cell-free massive multiple-input multiple-output (MIMO) is a promising technology for the Internet of Things (IoT) because it can increase connectivity and provide considerable energy efficiency (EE) and spectral efficiency (SE). However, pilot contamination caused by pilot reuse severely limits the performance of the system. In this paper, we propose a left-null-space-based massive access method that can significantly reduce interference among users. The proposed method includes three stages: initial orthogonal access, left-null-space-based opportunistic access and data detection of all accessed users. The simulation results show that the proposed method can achieve much higher spectral efficiency than the existing massive access methods.

Keywords: MIMO; cell-free massive multi-input multi-output; interference; left-null-space; massive access; pilot contamination; spectral efficiency.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
A cell-free massive MIMO IoT system.
Figure 2
Figure 2
The proposed massive access method.
Figure 3
Figure 3
Comparison of different user selection schemes in Stage 1 under K = 40 and U = 100.
Figure 4
Figure 4
Comparison of different massive access methods under K = 40 and U = 100.
Figure 5
Figure 5
Average SE of three massive access methods under different the number of users K.
Figure 6
Figure 6
The CDF of the sum SE under different massive access methods under K = 40 and U = 100.
Figure 7
Figure 7
Sum SE of three massive access methods under different the number of users K.
See this image and copyright information in PMC

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References

    1. Al-Fuqaha A., Guizani M., Mohammadi M., Aledhari M., Ayyash M. Internet of Things: A Survey on Enabling Technologies, Protocols, and Applications. IEEE Commun. Surv. Tuts. 2015;17:2347–2376. doi: 10.1109/COMST.2015.2444095. - DOI
    1. Misra N.N., Dixit Y., Al-Mallahi A., Bhullar M.S., Upadhyay R., Martynenko A. IoT, Big Data, and Artificial Intelligence in Agriculture and Food Industry. IEEE Internet Things J. 2022;7:6305–6324. doi: 10.1109/JIOT.2020.2998584. - DOI
    1. Yan H., Ashikhmin A., Yang H. A Scalable and Energy-Efficient IoT System Supported by Cell-Free Massive MIMO. IEEE Internet Things J. 2021;8:14705–14718. doi: 10.1109/JIOT.2021.3071781. - DOI
    1. Ngo H.Q., Ashikhmin A., Yang H., Larsson E.G., Marzetta T.L. Cell-Free Massive MIMO Versus Small Cells. IEEE Trans. Wirel. Commun. 2017;16:1834–1850. doi: 10.1109/TWC.2017.2655515. - DOI
    1. Zhang J., Chen S., Lin Y., Zheng J., Ai B., Hanzo L. Cell-Free Massive MIMO: A New Next-Generation Paradigm. IEEE Access. 2019;7:99878–99888. doi: 10.1109/ACCESS.2019.2930208. - DOI

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