NOMA-Aided Cell-Free Massive MIMO Systems

Li, Yikai; Baduge, Gayan Amarasuriya Aruma

doi:10.1109/lwc.2018.2841375

Cited by 101 publications

(80 citation statements)

References 9 publications

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“…As mentioned before, the investigation of CF massive MIMO-NOMA systems has been sparse, except for [20]- [22]. In fact [20] is the first paper to study the design of such systems. It considers single-antenna APs that use conjugate beamforming precoders.…”

Section: Previous Contributions On Cf Massive Mimo-nomamentioning

confidence: 99%

“…This phenomenon is referred to as "channel hardening" which substantially reduces the effective channel gain fluctuations; thereby rendering the use of downlink pilot training unnecessary [8], [36]. To apply power domain NOMA, we thus assume that the users in the nth cluster are ordered based on the mean of the effective channel gains as follows [20], [21]:…”

Section: Downlink Data Transmission Modelmentioning

confidence: 99%

“…Remark 6. For a fixed number of clusters N , if the number of antennas at each AP tends to infinity (L → ∞), the SINR for both the MRT and fpZF precoding (20) and (24) can be approximated as…”

Section: B Full-pilot Zf Beamformingmentioning

confidence: 99%

See 2 more Smart Citations

Rate Analysis of Cell-Free Massive MIMO-NOMA With Three Linear Precoders

Rezaei

Tellambura

Tadaion

et al. 2020

IEEE Trans. Commun.

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Although the hybrid of cell-free (CF) massive multiple-input multiple-output (MIMO) and non-orthogonal multiple access (NOMA) promises massive spectral efficiency gains, the type of precoders employed at the access points (APs) impacts the gains. In this paper, we thus comprehensively evaluate the system performance with maximum ratio transmission (MRT), fullpilot zero-forcing (fpZF) and modified regularized ZF (mRZF) precoders. We derive their closed-form sum rate expressions by considering Rayleigh fading channels, the effects of intra-cluster pilot contamination, inter-cluster interference, and imperfect successive interference cancellation (SIC). Our results reveal that this system supports significantly more users simultaneously at the same coherence interval compared to its OMA equivalent. However, intra-cluster pilot contamination and imperfect SIC degrade the system performance when the number of users is low. Moreover, with perfect SIC, mRZF and fpZF significantly outperform MRT. Also, we show that this system with either mRZF or fpZF precoding outperforms OMA systems with MRT. The analytical findings are verified by numerical results.Index Terms-NOMA, cell-free massive MIMO, MRT, fpZF, modified RZF, achievable sum rate.

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Section: Previous Contributions On Cf Massive Mimo-nomamentioning

confidence: 99%

Section: Downlink Data Transmission Modelmentioning

confidence: 99%

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Rate Analysis of Cell-Free Massive MIMO-NOMA With Three Linear Precoders

Rezaei

Tellambura

Tadaion

et al. 2020

IEEE Trans. Commun.

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“…The analysis in [20] shows that pilot contamination tends to significantly reduce the performance of cell-free massive MIMO. On the other hand, the short coherence time does not allow the system to support a large number of users in cell-free massive MIMO, as demonstrated in [39].…”

Section: Introductionmentioning

confidence: 99%

“…A practical combination of the aforementioned techniques is training-based massive MIMO aided NOMA [11], [39]. In [11], Cheng et al investigate the effect of NOMA in collocated massive MIMO systems, where the users are paired based on their distance from the base station.…”

Section: Introductionmentioning

confidence: 99%

On the Performance of Cell-Free Massive MIMO Relying on Adaptive NOMA/OMA Mode-Switching

Bashar

Cumanan

Burr

et al. 2020

IEEE Trans. Commun.

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The downlink (DL) of a non-orthogonal-multipleaccess (NOMA)-based cell-free massive multiple-input multipleoutput (MIMO) system is analyzed, where the channel state information (CSI) is estimated using pilots. It is assumed that the users are grouped into multiple clusters. The same pilot sequences are assigned to the users within the same clusters whereas the pilots allocated to all clusters are mutually orthogonal. First, a user's bandwidth efficiency (BE) is derived based on his/her channel statistics under the assumption of employing successive interference cancellation (SIC) at the users' end with no DL training. Next, the classic max-min optimization framework is invoked for maximizing the minimum BE of a user under peraccess point (AP) power constraints. The max-min user BE of NOMA-based cell-free massive MIMO is compared to that of its orthogonal multiple-access (OMA) counter part, where all users employ orthogonal pilots. Finally, our numerical results are presented and an operating mode switching scheme is proposed based on the average per-user BE of the system, where the mode set is given by Mode = { OMA, NOMA }. Our numerical results confirm that the switching point between the NOMA and OMA modes depends both on the length of the channel's coherence time and on the total number of users.

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A Novel Combining Method for NOMA and OMA in Cell-Free Massive MIMO System

Sui

Zhang

2022

Wireless and Satellite Systems

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NOMA-Aided Cell-Free Massive MIMO Systems

Cited by 101 publications

References 9 publications

Rate Analysis of Cell-Free Massive MIMO-NOMA With Three Linear Precoders

Rate Analysis of Cell-Free Massive MIMO-NOMA With Three Linear Precoders

On the Performance of Cell-Free Massive MIMO Relying on Adaptive NOMA/OMA Mode-Switching

A Novel Combining Method for NOMA and OMA in Cell-Free Massive MIMO System

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