In multiple-input multiple-output (MIMO) systems, the multiuser MIMO (MU-MIMO) systems have the potential to provide. higher channel capacity owing to multiuser and spatial diversity. Block diagonalization (BD) is one...
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In multiple-input multiple-output (MIMO) systems, the multiuser MIMO (MU-MIMO) systems have the potential to provide. higher channel capacity owing to multiuser and spatial diversity. Block diagonalization (BD) is one of the techniques to realize MU-MIMO systems, where multiuser interference can be completely cancelled and therefore several users can be supported simultaneously. When the number of multiantenna users is larger than the number of simultaneously receiving users, it is necessary to select the users that maximize the system capacity. However, computation complexity becomes prohibitive, especially when the number of multiantenna users is large. Thus simplified user scheduling algorithms are necessary for reducing the complexity of computation. This paper proposes a simplified capacity-based user scheduling algorithm, based on analysis of the capacity-based user selection criterion. We find a new criterion that is simplified by using the properties of Gram-Schmidt orthogonalization (GSO). In simulation results, the proposed algorithm provides higher sum rate capacity than the conventional simplified norm-based algorithm;and when signal-to-noise power ratio (SNR) is high, it provides performance similar to that of the conventional simplified capacity-based algorithm, which still requires high complexity. Fairness of the users is also taken into account. With the proportionally fair (PF) criterion, the proposed algorithm provides better performance (sum rate capacity or fairness of the users) than the conventional algorithms. Simulation results also shows that the proposed algorithm has lower complexity of computation than the conventional algorithms.
IN this study, we propose a novel sum-rate enhance-ment framework for future 6G multi-cell multiple-input multiple -output (MIMO) uplink networks, which exploits the coordi-nated beamforming, power control, and user s...
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IN this study, we propose a novel sum-rate enhance-ment framework for future 6G multi-cell multiple-input multiple -output (MIMO) uplink networks, which exploits the coordi-nated beamforming, power control, and userscheduling (CBPS) technique. The proposed CBPS technique not only significantly mitigates the inter-cell interference in transmit beamforming for users but also eliminates the intra-cell interference among the users in the same cell the receive beamforming at base sta-tions (BSs). Additionally, we propose a user scheduling algorithm that selects the users whose effective channel vectors are mutually orthogonal to each other to increase the spectral efficiency and an interference-aware power control technique for users to further reduce inter-cell interference. It is worth noting that the proposed CBPS framework does not require information exchange among the BSs and operates in a non-iterative and distributed manner based on local channel state information (CSI) at both the BSs and users. Thus, it can be implemented for practical wireless systems with low complexity. Extensive simulation results show that the proposed CBPS framework significantly outperforms conventional techniques in multi-cell environments.
Reconfigurable intelligent surface (RIS) is a promising solution to support a large volume of data traffic and massive connectivity for future wireless mobile networks. Especially, RIS can mitigate the drawbacks in ma...
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Reconfigurable intelligent surface (RIS) is a promising solution to support a large volume of data traffic and massive connectivity for future wireless mobile networks. Especially, RIS can mitigate the drawbacks in massive multiple-input multiple-output (MIMO) systems, such as the blockage caused by obstacles and the signal processing overhead by constructively and passively reflecting the incident wave toward the destination. In this paper, we provide an asymptotic analysis of the distribution of sum rate (SR) in RIS-aided massive MIMO systems. Using the asymptotic distribution of SR, the achievable scheduling gain and the optimal number of users are determined. In addition, we examined the channel hardening effect and outage probability through the achievable scheduling gain, and the optimal number of users is utilized to develop a low-complexity schedulingalgorithm. Simulation results reveal that the SR obtained from our analysis closely aligns with the actual SR. The results also show that the channel hardening effect can vanish with many users thereby achieving the multiuser diversity gain, and an RIS-aided system is more reliable than a conventional massive MIMO system in terms of the outage probability. Furthermore, the proposed schedulingalgorithm is shown to reduce computational complexity compared to the conventional schedulingalgorithm.
The blockage is a tough hurdle for millimetre-wave (mmWave) unmanned aerial vehicle (UAV) communications. In this Letter, the authors propose an angle domain channel transmission scheme for mmWave hybrid UAV communica...
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The blockage is a tough hurdle for millimetre-wave (mmWave) unmanned aerial vehicle (UAV) communications. In this Letter, the authors propose an angle domain channel transmission scheme for mmWave hybrid UAV communication with blockage. Firstly, they investigate the angle domain channel transmission of mmWave UAV communication systems with massive array antennas. Then, they solve the blockage problem through the multi-UAV coordination. Specially, they provide a practical user scheduling algorithm to maximize the achievable sum rates. Finally, simulation results are provided to show the effectiveness of the proposed method.
In this paper, users are selected using an optimal pair-wise semi-orthogonal users selection (SUS) schedulingalgorithm, while uniform channel decomposition (UCD) is applied to allocate appropriate number of per-user ...
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ISBN:
(纸本)9781538623534
In this paper, users are selected using an optimal pair-wise semi-orthogonal users selection (SUS) schedulingalgorithm, while uniform channel decomposition (UCD) is applied to allocate appropriate number of per-user subchannels in order to achieve as higher throughput as possible. Simulation results in the context of IEEE 802.11ac confirm advantage of the proposed combination in term of throughput. Namely, slightly throughput improvement is achieved even for small and moderate signal-to-noise ratios (SNRs), while more significant improvement is realized for very high SNRs.
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