Millimeter-Wave Massive MU-MIMO Performance Analysis for Private Underground Mine Communications

In this article, a performance analysis of millimeter wave (mmWave) massive multiuser multiple-input and multiple-output (MU-MIMO) channel within an underground mine is performed. The analysis is based on channel measurements conducted at 28 GHz using a base station of 64 virtual antenna elements serving multiple users. Channel characteristics such as large-scale path loss, time dispersion, coherence bandwidth and sum-rate capacity are reported and evaluated. The results indicate that multislope path loss model is better suited for precise prediction of path loss across various propagation segments within the mining gallery. The time dispersion analysis reveals that the underground mine channel does not cause significant time dispersion, as 90% of the root-mean-square (rms) delay spreads are below 4 ns. In addition, it was found that the rms delay spread is not dependent on the propagation distance. The study on sum-rate capacity highlights the potential of employing massive MIMO technology to improve the channel’s spectral efficiency. The analysis reveals that the capacity, with eight active users, can reach up to 33.54 bit/s/Hz. The outcomes of this article offer valuable insights into the propagation properties of underground mine environment, which is characterized by rich-scattering and irregular topology

A review: Simultaneous localization and mapping algorithms

Simultaneous Localization and Mapping (SLAM) involves creating an environmental map based on sensor data, while concurrently keeping track of the robot’s current position. Efficient and accurate SLAM is crucial for any mobile robot to perform robust navigation. It is also the keystone for higher-level tasks such as path planning and autonomous navigation. The past two decades have seen rapid and exciting progress in solving the SLAM problem together with many compelling implementations of SLAM methods. In this paper, we will review the two common families of SLAM algorithms: Kalman filter with its variations and particle filters. This article complements other surveys in this ?eld by reviewing the representative algorithms and the state-of-the-art in each family. It clearly identifies the inherent relationship between the state estimation via the KF versus PF techniques, all of which are derivations of Bayes rule

Compact Multiband Handset Antenna Design for Covering 5G Frequency Bands

New multiband antenna array structure with high gain is proposed for 5G communication handheld systems (700MHz/3.5 GHz and 28/38 GHz). The designed structure is proposed using a combination of sub-6GHz and mm-Wave antenna arrays. The antenna is based on S-shaped strip etched on the top side to operate at 700 MHz. On the other hand, the 3.5GHz band is generated by coupling a meander line to an inverted-C strip on the bottom side. Finally, the mm-Wave antenna array is based on four quadrupole elements with a 1:4 microstrip power divider. This configuration ensures that all four quadrupole antennas receive in-phase feeding power. Obtained results confirm that the designed antenna array achieves gains of 4.6 dBi, 10.5 dBi, at sub-6 GHz and mm-Wave band, respectively. Owing to its simplicity and compactness, the proposed handset antenna is a good candidate for 5G multiband applications

2D feature extraction in sensor coordinates for laser range finder

This paper describes an algorithm for feature extraction from measurements collected by laser range finder. The features are straight lines and corners present in the environment. The measurements are processed in the sensor coordinate system to identify an invariant parameter for the present straight lines that indicate their position and orientation. A second parameter is needed to determine the slopes of the straight lines as well as the values of the intersection angles between the consecutive lines which can be considered as corners in the case of right angles. A log-Hough transformation is used to find the equations of the straight lines. All the computations are carried out in the sensor coordinate system which leads to a fast and robust algorithm of feature extraction. Practical examples are presented to evaluate the efficiency of the algorithm