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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 scheduling algorithm. 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 scheduling algorithm is shown to reduce computational complexity compared to the conventional scheduling algorithm.

Cloud point temperature (Tcp) is a thermal index used to define the phase transition of thermoresponsive polymers. In this study, we used electrochemical techniques to obtain an electrochemical cloud point temperature (Tecp) that exhibits the more accurate phase transition temperature and can replace Tcp. Thermoamperometry on an ultramicroelectrode was conducted with a poly(arylene ether sulfone) (PES10) as a model system to obtain a current–temperature (i–T) curve in real time; the Tecpof the PES10was determined from the i–Tcurve. The i–Tcurve shows an unprecedented current decrease in the PES10solution despite increasing temperature; on the other hand, the current increased linearly with increasing temperature in the solution without PES10. This phenomenon was analyzed by considering the characteristics of PES10during phase transition, such as dynamic viscosity, temperature of the solution, and electrode impedance. It was confirmed that the current drops shown in the i–Tcurves were mainly due to the decrease of real electrode area. The comparison of Tecpand Tcpshowed that both depended similarly on the concentrations of the thermoresponsive polymer and the supporting electrolyte. The results reveal that by adjusting the concentration of polymer and electrolyte in an organic solution, Tecp, as a new analytical method, can be used in electric circuit-based energy storage appliances such as Li-ion batteries and supercapacitors.

In this paper, a new channel state information (CSI) feedback scheme based on probability distribution is proposed for massive multiple-input multiple-output (MIMO) systems. In the proposed scheme, the real and imaginary parts of the channel elements are divided into several groups and sorted in ascending order. The sorted channel elements are approximated to a cumulative distribution function of a predefined probability distribution, and parameters representing the probability distributions are obtained for each group. The generated CSI, including the representing parameters and original ordering information, is fed back to the base station (BS). Finally, the channel vectors are reconstructed based on the CSI from the BS. It has been verified that the proposed scheme outperforms the conventional CSI feedback schemes in terms of the sum rate under a similar feedback overhead with low computational complexity.

Neural coding of auditory stimulus frequency is well-documented; however, the cortical signals and perceptual correlates of pitch have not yet been comprehensively investigated. This study examined the temporal patterns of event-related potentials (ERP) in response to single tones of pitch chroma, with an assumption that these patterns would be more prominent in musically-trained individuals than in non-musically-trained individuals. Participants with and without musical training (N = 20) were presented with seven notes on the C major scale (C4, D4, E4, F4, G4, A4, and B4), and whole-brain activities were recorded. A linear regression analysis between the ERP amplitude and the seven notes showed that the ERP amplitude increased or decreased as the frequency of the pitch increased. Remarkably, these linear correlations were anti-symmetric between the hemispheres. Specifically, we found that ERP amplitudes of the left and right frontotemporal areas decreased and increased, respectively, as the pitch frequency increased. Although linear slopes were significant in both groups, the musically-trained group exhibited marginally steeper slope, and their ERP amplitudes were most discriminant for frequency of tone of pitch at earlier latency than in the non-musically-trained group (~ 460 ms vs ~ 630 ms after stimulus onset). Thus, the ERP amplitudes in frontotemporal areas varied according to the pitch frequency, with the musically-trained participants demonstrating a wider range of amplitudes and inter-hemispheric anti-symmetric patterns. Our findings may provide new insights on cortical processing of musical pitch, revealing anti-symmetric processing of musical pitch between hemispheres, which appears to be more pronounced in musically-trained people.

An iterative multihead multitrack detection scheme for bit-patterned media recording is described in this letter. The scheme employs two iterative strategies with multihead, multitrack detection where three tracks are simultaneously processed to accurately estimate the channel with track misregistration (TMR) and effectively detect the data by using intertrack interference (ITI) information with high reliability. The first outer iteration aims to compensate for the TMR effect, and the second inner iteration aims to improve the reliability of the data. In the outer iteration, the TMR effect is compensated by modifying the generalized partial response (GPR) target to a channel that reflects the TMR estimated by a TMR estimator using an expectation and maximization algorithm. In the inner iteration, iterative equalization and decoding (IED) is conducted between the two-dimensional partial response maximum-likelihood detector and the low-density parity check decoder based on the revised GPR target. Since each track has a different channel performance according to the amount of ITI information in the multitrack detection, we design the GPR target and the code rate separately for each track to maximize the overall channel performance. The bit error rate performances of the proposed IED scheme are compared with the conventional IED scheme when the areal density is 2 $\text{Tb/in}^{2}$. Simulation results show that the IED scheme has more than 2 dB gain compared with the conventional IED scheme for 30$\%$ TMR.

New Radio (NR) is a new radio air interface developed by the 3rd Generation Partnership Project for the fifth generation (5G) mobile communications system. With great flexibility, scalability, and efficiency, 5G is expected to address a wide range of use cases including enhanced mobile broadband, ultra-reliable low-latency communications, and massive machine type communications. The physical downlink control channel (PDCCH) in NR carries downlink control information. Understanding how PDCCH operates is key to developing a good understanding of how information is communicated over NR. This article provides an overview of the 5G NR PDCCH by describing its physical layer structure, monitoring mechanisms, beamforming operation, and the carried information. We also share various design rationales that influenced NR standardization.

The Third Generation Partnership Project (has recently published the first series of specifications for the New Radio (NR) standard, which are designed to meet the industry's demand for early commercialization of 5G. The NR standard has been developed to provide not only enhanced mobile broadband services, but also other new services such as ultra-reliable and low-latency communications and massive machine type communications. This article describes new features of the data transmission framework in NR specified to support various services and explains the technical motivation and merits of these features.

New Radio (NR), which is part of Release 15 of Third Generation Partnership Project (3GPP) standards, marks the first fifth generation (5G) standards designed to meet the requirements set forth by the International Telecommunication Union for IMT-2020. This article presents an overview of the NR radio interface and the ongoing work in 3GPP to evolve NR toward 5G-Advanced, allowing it to access new spectrum and support a broader range of vertical services while enhancing its performance beyond what is available today.

Massive multiple-input multiple-output (MIMO) systems have become an essential feature in the fifth-generation (5G) wireless communication networks. Due to the commercialization of 5G mobile communication devices, the number of multi-antenna devices have increased over the years. Therefore, a precoding scheme based on multi-antenna users is an inevitable feature that needs to be analyzed in massive MIMO systems. The asymptotic ergodic sum-rate analysis of block diagonalization (BD) based multiuser MIMO systems is performed in this study. Based on the random matrix theory results derived from the massive base station antenna characteristics, the singular values of the block diagonalized channel are obtained asymptotically, and thereby, the closed-form expression for the BD based sum-rate is derived. The asymptotic sum-rate performance gap between the BD and the zero-forcing beamforming is then analyzed. Moreover, from the derived asymptotic sum-rate, the optimal number of users needed to maximize the ergodic sum-rate is proposed. Simulation results show that the derived asymptotic analyses are closely aligned to the sum-rate obtained by Monte Carlo simulations. In addition, the simulation results prove that the maximum ergodic sum-rate can be achieved by using the proposed number of users.

A novel duplex scheme, region-based division duplex (RDD), is proposed to address the cross-tier interference issue in heterogeneous networks. The proposed RDD leverages the location of the user to select the link direction of a small cell between the forward and reverse duplex modes. Moreover, a coordinated scheduling algorithm is developed where pairing between macro and small cells and the duplex mode of each small cell is jointly decided. Simulation results show that the proposed RDD achieves an approximately 40% gain in network sum capacity compared with conventional TDD-based duplex schemes.

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