scholarly journals Analytical Blind Beamforming for a Multi-Antenna UAV Base-Station Receiver in Millimeter-Wave Bands

Sensors ◽  
2021 ◽  
Vol 21 (19) ◽  
pp. 6561
Author(s):  
Pingchuan Liu ◽  
Kuangang Fan ◽  
Yuhang Chen
Keyword(s):  
Channel Estimation ◽  
Millimeter Wave ◽  
Antenna Arrays ◽  
Base Station ◽  
Base Stations ◽  
Signal Recovery ◽  
Constant Modulus ◽  
Signal Space ◽  
Target User ◽  
Blind Beamforming

Over the last decade, unmanned aerial vehicles (UAVs) with antenna arrays have usually been employed for the enhancement of wireless communication in millimeter-wave bands. They are commonly used as aerial base stations and relay platforms in order to serve multiple users. Many beamforming methods for improving communication quality based on channel estimation have been proposed. However, these methods can be resource-intensive due to the complexity of channel estimation in practice. Thus, in this paper, we formulate an MIMO blind beamforming problem at the receivers for UAV-assisted communications in which channel estimation is omitted in order to save communication resources. We introduce one analytical method, which is called the analytical constant modulus algorithm (ACMA), in order to perform blind beamforming at the UAV base station; this relies only on data received by the antenna. The feature of the constant modulus (CM) is employed to restrict the target user signals. Algebraic operations, such as singular value decomposition (SVD), are applied to separate the user signal space from other interferences. The number of users in the region served by the UAV can be detected by exploring information in the measured data. We seek solutions that are expressible as one Kronecker product structure in the signal space; then, the beamformers that correspond to each user can be successfully estimated. The simulation results show that, by using this analytically derived blind method, the system can achieve good signal recovery accuracy, a reasonable system sum rate, and acceptable complexity.

scholarly journals A Monte Carlo Analysis of Actual Maximum Exposure From a 5G Millimeter-Wave Base Station Antenna for EMF Compliance Assessments

2022 ◽  
Vol 9 ◽  
Author(s):  
Bo Xu ◽  
David Anguiano Sanjurjo ◽  
Davide Colombi ◽  
Christer Törnevik
Keyword(s):  
Monte Carlo ◽  
Millimeter Wave ◽  
Near Field ◽  
Multiple Input Multiple Output ◽  
Monte Carlo Analysis ◽  
Base Station ◽  
Base Stations ◽  
Far Field ◽  
Wave Radio ◽  
Maximum Exposure

International radio frequency (RF) electromagnetic field (EMF) exposure assessment standards and regulatory bodies have developed methods and specified requirements to assess the actual maximum RF EMF exposure from radio base stations enabling massive multiple-input multiple-output (MIMO) and beamforming. Such techniques are based on the applications of power reduction factors (PRFs), which lead to more realistic, albeit conservative, exposure assessments. In this study, the actual maximum EMF exposure and the corresponding PRFs are computed for a millimeter-wave radio base station array antenna. The computed incident power densities based on near-field and far-field approaches are derived using a Monte Carlo analysis. The results show that the actual maximum exposure is well below the theoretical maximum, and the PRFs similar to those applicable for massive MIMO radio base stations operating below 6 GHz are also applicable for millimeter-wave frequencies. Despite the very low power levels that currently characterize millimeter-wave radio base stations, using the far-field approach can also guarantee the conservativeness of the PRFs used to assess the actual maximum exposure close to the antenna.

scholarly journals Power density of rectangular microstrip patch antenna arrays for 5G indoor base station

2020 ◽  
Vol 19 (3) ◽  
pp. 1367
Author(s):  
Nor Adibah Ibrahim ◽  
Tharek Abd Rahman ◽  
Razali Ngah ◽  
Omar Abd Aziz ◽  
Olakunle Elijah
Keyword(s):  
Power Density ◽  
Antenna Arrays ◽  
Base Station ◽  
Small Cell ◽  
Base Stations ◽  
System Capacity ◽  
High Data ◽  
Communication Devices ◽  
Set Up ◽  
Cell Base

The fifth-generation (5G) network has been broadly investigated by many researchers. The capabilities of 5G include massive system capacity, incredibly high data rates everywhere, very low latency and the most important point is that it is exceptionally low device cost and low energy consumption. A key technology of 5G is the millimeter wave operating at 28 GHz and 38 GHz frequency bands which enable massive MIMO and small cell base station densification. However, there has been public concern associated with human exposure to electromagnetic fields (EMF) from 5G communication devices. Hence, this paper studies the power density of a 5G antenna array that can be used for the indoor base station. The power density is the amount of power or signal strength absorbed by a receiver such as the human body located a distance from the base station. To achieve this, the design of array antennas using CST software at 28 GHz, fabrication and measurement were carried out in an indoor and hallway environment. The measurement processes were set up at IC5G at UTM Kuala Lumpur in which the distance of the transmitter to receiver where 1 m, 4 m, 8 m, and 10 m. In this study, the measured power density is found to be below the set limit by ICNIRP and hence no health implication is feared. Regardless, sufficient act of cautionary has to be applied by those staying close to small cell base stations and more studies are still needed to ensure the safety of use of 5G base stations.

scholarly journals Evaluation of Interference in Ultra-Dense 5G Radio Access Networks with Beamforming

Telecom IT ◽  
2020 ◽  
Vol 8 (4) ◽  
pp. 35-59
Author(s):  
G. Fokin
Keyword(s):  
Radiation Pattern ◽  
Antenna Arrays ◽  
Access Network ◽  
Beam Width ◽  
Base Station ◽  
Access Networks ◽  
Base Stations ◽  
Radio Access Network ◽  
Radio Access Networks ◽  
Radio Access

In this paper, we investigate the dependence of the level of intersystem interference on the beam width of the adaptively formed antenna radiation pattern and the territorial separation of neighboring devices in ultra-dense 5G radio access networks. The results of simulation modeling of a radio access network based on 19 base stations with the parameterization of the antenna array gain by the width of the radiation pattern in the horizontal plane show that when the base station beam is di-rected to the user device and narrowed from 360° to 5°, the level of intrasystem interference decreases by 15 dB compared with the case of omnidirectional antennas. The results of simulation of a radio access network based on 19 three-sector base stations with planar antenna arrays of 64 elements illustrate a significant reduction in the level of interference in comparison with the case of omnidirectional antennas and, in order to obtain zones of a positive signal-to-noise ratio, confirm the need for a territorial separation of neighboring devices by 10–20 % of the range of radio coverage.

scholarly journals Angular Domain Data-Assisted Channel Estimation for Pilot Decontamination in Massive MIMO

2017 ◽  
Vol 2017 ◽  
pp. 1-9
Author(s):  
Yihenew Beyene ◽  
Kalle Ruttik ◽  
Riku Jäntti
Keyword(s):  
Channel Estimation ◽  
Antenna Arrays ◽  
Mean Squared Error ◽  
Mimo Systems ◽  
Mimo System ◽  
Base Station ◽  
Pilot Contamination ◽  
Angular Domain ◽  
Matrix Estimation ◽  
Minimum Mean Squared Error

Massive Multiple-Input-Multiple-Output (M-MIMO) system is a promising technology that offers to mobile networks substantial increase in throughput. In Time-Division Duplexing (TDD), the uplink training allows a Base Station (BS) to acquire Channel State Information (CSI) for both uplink reception and downlink transmission. This is essential for M-MIMO systems where downlink training pilots would consume large portion of the bandwidth. In densely populated areas, pilot symbols are reused among neighboring cells. Pilot contamination is the fundamental bottleneck on the performance of M-MIMO systems. Pilot contamination effect in antenna arrays can be mitigated by treating the channel estimation problem in angular domain where channel sparsity can be exploited. In this paper, we introduce a codebook that projects the channel into orthogonal beams and apply Minimum Mean-Squared Error (MMSE) criterion to estimate the channel. We also propose data-aided channel covariance matrix estimation algorithm for angular domain MMSE channel estimator by exploiting properties of linear antenna array. The algorithm is based on simple linear operations and no matrix inversion is involved. Numerical results show that the algorithm performs well in mitigating pilot contamination where the desired channel and other interfering channels span overlapping angle-of-arrivals.

scholarly journals GAMP-SBL-based channel estimation for millimeter-wave MIMO systems

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Jianfeng Shao ◽  
Xianpeng Wang ◽  
Xiang Lan ◽  
Zhiguang Han ◽  
Ting Su
Keyword(s):  
Channel Estimation ◽  
Millimeter Wave ◽  
Mimo Systems ◽  
Learning Algorithm ◽  
Mimo System ◽  
Estimation Algorithm ◽  
Mimo Channel ◽  
Estimation Methods ◽  
Estimation Accuracy ◽  
Signal Recovery

AbstractBased on the finite scattering characters of the millimeter-wave multiple-input multiple-output (MIMO) channel, the mmWave channel estimation problem can be considered as a sparse signal recovery problem. However, most traditional channel estimation methods depend on grid search, which may lead to considerable precision loss. To improve the channel estimation accuracy, we propose a high-precision two-stage millimeter-wave MIMO system channel estimation algorithm. Since the traditional expectation–maximization-based sparse Bayesian learning algorithm can be applied to handle this problem, it spends lots of time to calculate the E-step which needs to compute the inversion of a high-dimensional matrix. To avoid the high computation of matrix inversion, we combine damp generalized approximate message passing with the E-step in SBL. We then improve a refined algorithm to handle the dictionary matrix mismatching problem in sparse representation. Numerical simulations show that the estimation time of the proposed algorithm is greatly reduced compared with the traditional SBL algorithm and better estimation performance is obtained at the same time.

scholarly journals USE OF ADAPTIVE ANTENNA ARRAYS FOR INCREASE THE THROUGHPUT IN LTE-A

2021 ◽  
pp. 17-25
Author(s):  
D. O. Makoveenko ◽  
S. V. Siden ◽  
V. V. Pyliavskyi
Keyword(s):  
Antenna Array ◽  
Antenna Arrays ◽  
Noise Analysis ◽  
Mobile Network ◽  
Base Station ◽  
Base Stations ◽  
Adaptive Antenna ◽  
Adaptive Antenna Arrays ◽  
Useful Signal ◽  
Antenna Systems

Context. The aim of the article is to analyze the throughput of the LTE-A mobile network on the uplink using an adaptive linear equidistant antenna array. Objective. Suggestions have been made for the possibility of using adaptive antenna arrays to increase bandwidth in LTE-A mobile networks and analyze the benefits of its use compared to the standard type of base station antenna Method. To achieve this result, a computer model of noise analysis of the mobile network in the form of a flat regular hexagonal antenna array consisting of 7 three-sector cells was developed. To estimate the benefit from the use of adaptive antenna arrays, two options were analyzed: when using a standard antenna array of the LTE-A network, and an adaptive linear equidistant antenna array. During the simulation, 100 random placements of subscribers of useful and interference signals were performed and the minimum, maximum and average gain from the use of adaptive antenna arrays was calculated. The average value of the gain for the adaptive antenna array in the direction of the subscriber station, which generates a useful signal of 5.69 dB more than the standard antenna array of the LTE-A network. At the same time, there is a significant reduction in the gain of the adaptive antenna in the direction of the interference subscriber stations, namely, for those with the highest interference level, the gain is 32.84 dB and 28.33 dB, respectively. To clearly show the gain in the qualitative characteristics of the network, a bandwidth analysis was performed for different types of antennas. The bandwidth distribution (transport block size) for 50 resource blocks using an adaptive equidistant linear antenna array compared to a standard antenna array is presented. Results. It is shown that due to the use of adaptive antenna systems, the average bandwidth increases from 11 Mbit/s to 35 Mbit / s for all types of distribution considered channels. Conclusions. The article proposes the use of adaptive antenna arrays to increase the bandwidth of the LTE-A network. The simulation of bandwidth for 50 resource blocks showed that in the presence of internal system interference when using standard antennas of base stations, the average bandwidth is from 11.2 Mbps to 12.3 Mbps. At the same time, due to the use of adaptive antenna systems, the average bandwidth increases from 11 Mbit/s to 35 Mbit/s for all types of multipath channels considered.

scholarly journals Wideband Beamspace Channel Estimation for Millimeter-Wave MIMO Systems Relying on Lens Antenna Arrays

2019 ◽  
Vol 67 (18) ◽  
pp. 4809-4824 ◽  
Author(s):  
Xinyu Gao ◽  
Linglong Dai ◽  
Shidong Zhou ◽  
Akbar M. Sayeed ◽  
Lajos Hanzo
Keyword(s):  
Channel Estimation ◽  
Millimeter Wave ◽  
Antenna Arrays ◽  
Mimo Systems ◽  
Lens Antenna

scholarly journals Performance Evaluation of 5G Millimeter-Wave Cellular Access Networks Using a Capacity-Based Network Deployment Tool

2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
Michel Matalatala ◽  
Margot Deruyck ◽  
Emmeric Tanghe ◽  
Luc Martens ◽  
Wout Joseph
Keyword(s):  
Communication Networks ◽  
Millimeter Wave ◽  
Antenna Arrays ◽  
Access Networks ◽  
Base Stations ◽  
Reference Network ◽  
Wireless Access Networks ◽  
5G Networks ◽  
Data Intensive ◽  
Data Intensive Applications

The next fifth generation (5G) of wireless communication networks comes with a set of new features to satisfy the demand of data-intensive applications: millimeter-wave frequencies, massive antenna arrays, beamforming, dense cells, and so forth. In this paper, we investigate the use of beamforming techniques through various architectures and evaluate the performance of 5G wireless access networks, using a capacity-based network deployment tool. This tool is proposed and applied to a realistic area in Ghent, Belgium, to simulate realistic 5G networks that respond to the instantaneous bit rate required by the active users. The results show that, with beamforming, 5G networks require almost 15% more base stations and 4 times less power to provide more capacity to the users and the same coverage performances, in comparison with the 4G reference network. Moreover, they are 3 times more energy efficient than the 4G network and the hybrid beamforming architecture appears to be a suitable architecture for beamforming to be considered when designing a 5G cellular network.

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