Channel Estimation and Uplink Achievable Rates in One-Bit Massive MIMO Systems

This paper considers channel estimation and achievable rates for the uplink of a massive multiple-input multiple-output (MIMO) system where the base station is equipped with one-bit analog-to-digital converters (ADCs). By rewriting the nonlinear one-bit quantization using a linear expression, we first derive a simple and insightful expression for the linear minimum mean-square-error (LMMSE) channel estimator. Then employing this channel estimator, we derive a closed-form expression for the lower bound of the achievable rate for the maximum ratio combiner (MRC) receiver. Numerical results are presented to verify our analysis and show that our proposed LMMSE channel estimator outperforms the near maximum likelihood (nML) estimator proposed previously.Comment: 5 pages, 2 figures, the Ninth IEEE Sensor Array and Multichannel Signal Processing Worksho

Understanding the Hydrodynamics in a 2-Dimensional Downer by CFD-DEM Simulation

The gas-solid flows in a 2-dimensional downer were simulated using a CFD-DEM method. The predicted macro-scale flow structure had good agreement with the experiments. The distinct clustering phenomena at meso-scale were revealed throughout the downer. Influences of the collision properties of the wall and the particles on the hydrodynamics in downer were investigated

Giant circular dichroism and negative refractive index of chiral metamaterial Progress

Abstract-In this paper, a double-layer split-ring resonator structure chiral metamaterial was proposed which could exhibit pronounced circular dichroism (CD) effect and negative refractive index at microwave frequencies. Experiment and simulation calculations are in good agreement. The retrieved effective electromagnetic parameters indicate that the lower frequency CD effect is associated with the negative refractive index property of the left circularly polarized (LCP) wave, and the upper one is to the right circularly polarized (RCP) wave. The mechanism of the giant CD effect could be further illustrated by simulated surface current and power loss density distributions

Analysis of an Upper Bound on the Effects of Large Scale Attenuation on Uplink Transmission Performance for Massive MIMO Systems

Massive multiple-input multiple-output (MIMO) is a potential candidate key technology for the 5G of wireless communication systems. In research to date, different power loss and shadowing effects on different antenna elements across the large arrays have been neglected. In this paper, based on an idealized propagation model, a new large scale attenuation (LSA) model is proposed, by which the large scale losses (path loss and shadowing effect) over the antenna array can be considered when establishing a massive MIMO channel model. By using this model, the spectral efficiency (in terms of bits/s/Hz sum-rate) of the maximum ratio combining (MRC) detector is derived for the uplink. The spectral efficiency performance of the zero forcing (ZF) detector also can be derived in the same manner. It can be found that the sumrate performance (MRC and ZF) of our proposed channel model (assuming independent shadowing on all elements of the array) exceeds that of the conventional model (where the LSA effect is not included). Based upon our theoretical and simulation analysis, we have found that the spectral efficiency gap is mainly from the mean value of different shadowing effects across different elements, and the different path losses experienced by different antenna elements provide negligible contribution. This LSA model and the derived performance results could be beneficial and informative for the research, design and evaluation of the next generation of wireless communication system employing a massive MIMO configuration

Analysis of an Upper Bound on the Effects of Large Scale Attenuation on Uplink Transmission Performance for Massive MIMO Systems

Massive multiple-input multiple-output (MIMO) is a potential candidate key technology for the 5G of wireless communication systems. In research to date, different power loss and shadowing effects on different antenna elements across the large arrays have been neglected. In this paper, based on an idealized propagation model, a new large scale attenuation (LSA) model is proposed, by which the large scale losses (path loss and shadowing effect) over the antenna array can be considered when establishing a massive MIMO channel model. By using this model, the spectral efficiency (in terms of bits/s/Hz sum-rate) of the maximum ratio combining (MRC) detector is derived for the uplink. The spectral efficiency performance of the zero forcing (ZF) detector also can be derived in the same manner. It can be found that the sumrate performance (MRC and ZF) of our proposed channel model (assuming independent shadowing on all elements of the array) exceeds that of the conventional model (where the LSA effect is not included). Based upon our theoretical and simulation analysis, we have found that the spectral efficiency gap is mainly from the mean value of different shadowing effects across different elements, and the different path losses experienced by different antenna elements provide negligible contribution. This LSA model and the derived performance results could be beneficial and informative for the research, design and evaluation of the next generation of wireless communication system employing a massive MIMO configuration

New prefabricated support structure for TBM tunneling in complex strata of coal mines: engineering practice

Tunnel Boring Machines (TBMs) have been successfully applied in the excavation of deep shaft roadways in coal mines, yielding substantial socio-economic benefits. However, technical bottlenecks remain that hinder their further promotion and application. In response to the challenge of current support structures and techniques failing to simultaneously meet the requirements of support efficiency, strength, and construction costs, which impedes the full utilization of TBM speed advantages, a research team has developed a novel steel pipe segment assembly support structure. Large-scale model tests of the new prefabricated support structure were conducted to ascertain the deformation and failure patterns under loaded conditions, and the support structure was optimized based on the test results. Numerical simulations were performed to evaluate the reliability of the new support structure under TBM tunneling conditions. Industrial trials were subsequently conducted to field-test the feasibility of the new steel pipe segment support structure for TBM-excavated roadways in coal mines. The test results indicate that the maximum tensile strain of the surrounding rock is 803 με, and the deformation of the steel pipe support structure is less than 1 mm. The new support structure can be installed quickly, with the installation of one ring of segments (1.5 m) completed within 90 minutes, significantly enhancing the support strength in TBM-excavated roadways and the adaptability to strata conditions. This research provides a technical reference for further increasing the tunneling speed of coal mine roadways and ensuring the continuity of coal mining operations

Biosensing strategies for amyloid‐like protein aggregates

Protein aggregate species play a pivotal role in the pathology of various degenerative diseases. Their dynamic changes are closely correlated with disease progression, making them promising candidates as diagnostic biomarkers. Given the prevalence of degenerative diseases, growing attention is drawn to develop pragmatic and accessible protein aggregate species detection technology. However, the performance of current detection methods is far from satisfying the requirements of extensive clinical use. In this review, we focus on the design strategies, merits, and potential shortcomings of each class of detection methods. The review is organized into three major parts: native protein sensing, seed amplification, and intricate program, which embody three different but interconnected methodologies. To the best of our knowledge, no systematic review has encompassed the entire workflow, from the molecular level to the apparatus organization. This review emphasizes the feasibility of the methods instead of theoretical detection limitations. We conclude that high selectivity does play a pivotal role, while signal compilation, multilateral profiling, and other patient-oriented strategies (i.e. less invasiveness and assay speed) are also important

Design guidelines for the SPICE parameters of waveform-selective metasurfaces varying with the incident pulse width at a constant oscillation frequency

In this study, we numerically demonstrate how the response of recently reported circuit-based metasurfaces is characterized by their circuit parameters. These metasurfaces, which include a set of four diodes as a full wave rectifier, are capable of sensing different waves even at the same frequency in response to the incident waveform, or more specifically the pulse width. This study reveals the relationship between the electromagnetic response of such waveform-selective metasurfaces and the SPICE parameters of the diodes used. First, we show that reducing a parasitic capacitive component of the diodes is important for realization of waveform-selective metasurfaces in a higher frequency regime. Second, we report that the operating power level is closely related to the saturation current and the breakdown voltage of the diodes. Moreover, the operating power range is found to be broadened by introducing an additional resistor into the inside of the diode bridge. Our study is expected to provide design guidelines for circuit-based waveform-selective metasurfaces to select/fabricate optimal diodes and enhance the waveform-selective performance at the target frequency and power level.Comment: 9 pages, 9 figure

Characteristics and Formation Mechanism of Multiscale Storage Spaces in Ancient Deep Tight Reservoirs: Examples from the Cambrian Yurtus Formation in the Northern Tarim Basin, China

AbstractUnder the background of complicated diagenetic fluids, high-temperature pressure in superimposed basin, the pore-forming and pore-preserving effects of deep tight reservoirs are complex, and the formation mechanism of high-quality reservoirs has always been the core issue. With the discovery of oil and gas in ultradeep drilling in Tarim Basin, the most unconventional tight reservoir of Lower Cambrian Yuertus Formation in Tabei area began to receive attention. Based on the research of typical field outcrops in Tabei area, the lithofacies, reservoir space differences, and reservoir formation mechanism are systematically analyzed. (1) The stratum has undergone complex multistage diagenetic fluid transformation, and the rock types are diverse with great differences; siliceous rock and dolomite are the main rock types, often in thin-medium layered distribution. (2) After long-term deep burial transformation, siliceous rock and dolomite can still retain a large number of effective storage spaces; hydrothermal dissolution pores, organic acid dissolution pores, atmospheric freshwater dissolution pores, and intercrystalline pores are the main pore types, which provide main storage spaces. Multiscale pores are developed in siliceous rock and dolomite, with good connectivity and good pore structure. (3) The large-scale storage spaces mainly come from the effective maintenance of primary pores, organic matter, and hydrothermal dissolution. The siliceous minerals and dolomite have stable properties and strong resistance to compaction and can effectively maintain the early pores. (4) The large-scale reservoir space was formed in the early diagenetic stage; the pressure-solution and cementation are the two most important diagenetic processes for reducing storage spaces; however, under the pore-forming and pore-preserving effects of early silicification and dolomitization, various types of dissolution, and oil charging, the tight lithology can still maintain effective storage spaces. The related research has important theoretical and practical significance for studying the formation mechanism of tight reservoirs in deep ancient strata and predicting high-quality reservoirs