Climatology of gravity waves over Poker Flat, Alaska for 1983

An analysis of short-period wind fluctuations over Poker Flat, Alaska, obtained using the Poker Flat mesosphere-stratosphere-troposphere radar is presented. Results are shown for the troposphere and lower stratosphere as well as for the upper mesosphere and lower thermosphere. Contours depict various levels of wind variance (m2s-2). These results pertain only to wind fluctuation periods lying between one and six hours. These particular fluctuations are generally considered to arise primarily from atmospheric gravity waves. Insofar as this is true, the figure thus describes a general climatology of gravity waves at high latitudes

Implementation of 5G beamforming techniques on cylindrical arrays

In this paper we study the performance of a Uniform Cylindrical Array for a 5G base station working in the mmW region. Conventional and Capon beamforming design are considered. A comparison against a base station equipped with three Uniform Planar Arrays, one per sector, is presented. Average per-user achievable rate results are provided with different system configuration in terms of network loading and number of antennas, showing that Uniform Cylindrical Array could represent an interesting solution for 5GmmW networks

Assessment of MU-MIMO schemes with cylindrical arrays under 3GPP 3D channel model for B5G networks

Beyond 5G technologies promise groundbreaking advances on the performance of cellular networks, by taking advantage of Massive MIMO in mmWave scenarios. The aim of this study is to analyze and test the performance of a 5G cell site equipped with large antenna arrays. It is of particular interest the comparison between the typical trisector cell design with a planar array for each sector, and the less investigated cylindrical array, able to maintain a constant pattern through the whole azimuthal range. To validate our analysis, we adopt the latest 3GPP-compliant 3D channel model and we evaluate the performance of multi-user and multi-layer precoding and combining schemes. Several MIMO configurations are taken into account, and we show that cylindrical arrays can improve the overall system performance, both in terms of achievable per-user rate and outage probability

Smart Tools for Smart Applications: New Insights into Inorganic Magnetic Systems and Materials

This Special Issue, consisting of four reviews and three research articles, presents some of the recent advances and future perspectives in the field of magnetic materials and systems, which are designed to meet some of our current challenge

Implementation of Deep-Learning-Based CSI Feedback Reporting on 5G NR-Compliant Link-Level Simulator

Advances in machine learning have widened the range of its applications in many fields. In particular, deep learning has attracted much interest for its ability to provide solutions where the derivation of a rigorous mathematical model of the problem is troublesome. Our interest was drawn to the application of deep learning for channel state information feedback reporting, a crucial problem in frequency division duplexing (FDD) 5G networks, where knowledge of the channel characteristics is fundamental to exploiting the full potential of multiple-input multiple-output (MIMO) systems. We designed a framework adopting a 5G New Radio convolutional neural network, called NR-CsiNet, with the aim of compressing the channel matrix experienced by the user at the receiver side and then reconstructing it at the transmitter side. In contrast to similar solutions, our framework is based on a 5G New Radio fully compliant simulator, thus implementing a channel generator based on the latest 3GPP 3-D channel model. Moreover, realistic 5G scenarios are considered by including multi-receiving antenna schemes and noisy downlink channel estimation. Simulations were carried out to analyze and compare the performance with current feedback reporting schemes, showing promising results for this approach from the point of view of the block error rate and throughput of the 5G data channel

Tropospheric gravity waves observed by three closely spaced ST radars

Clear-air radar experiments were carried out on the southern coast of France during the (ALPEX) Alpine experiment program vertically directed stratosphere-troposphere-radars were set up with spacings of about 5 to 6 km. The temporal and spectral characteristics of the vertical velocity fluctuations were examined. The horizontal and vertical properties of gravity waves in the lower atmosphere were analyzed. The techniques used and the first results from this wave study are described

Sensing of DVB-T signals for white space cognitive radio systems

In cognitive radio networks, systems operating in digital television white spaces are particularly interesting for practical applications. In this paper, we consider single- antenna and multi-antenna spectrum sensing of real DVB-T signals under different channel conditions. Some of the most important algorithms are considered and compared, including energy detection, eigenvalue based techniques and methods exploiting OFDM signal knowledge. The obtained results show the algorithm performance and hierarchy in terms of ROC and detection probability under fixed false alarm rate, for different channel profiles in case of true DVB-T signals

Peer-to-Peer Cooperative Positioning Part I: GNSS Aided Acquisition

To improve the performance of GNSS receivers in hostile environments, we consider a Cooperative Positioning approach, where receivers exchange data and information with their neighbors. We focus on unstructured P2P networks, without a control or fusion center. We show that a significant reduction of the acquisition time can indeed by achieved when GNSS aiding quantities like Doppler, satellite Carrierto-Noise ratio and secondary code delay are provided by some aiding peers. The approach is clearly similar to that of Assisted GNSS, but does not require a fixed infrastructure and may better take into account the local environment. Since, in the near future, multi-standard devices will be more and more inter-connected, GNSS Cooperative Positioning may soon become an alternative or a complement to fixed augmentation system