scholarly journals Orbit Angular Momentum MIMO with Mode Selection for UAV-Assisted A2G Networks

Sensors ◽  
2020 ◽  
Vol 20 (8) ◽  
pp. 2289
Author(s):  
Tao Hu ◽  
Yang Wang ◽  
Bo Ma ◽  
Jie Zhang
Keyword(s):  
Angular Momentum ◽  
High Speed ◽  
Degrees Of Freedom ◽  
Channel Model ◽  
Mimo Systems ◽  
Mode Selection ◽  
Multiple Input Multiple Output ◽  
Base Stations ◽  
Spectrum Efficiency ◽  
Ms Scheme

As an emerging solution for line-of-sight (LOS) wireless communications, in air-to-ground (A2G) channels, the unmanned aerial vehicle (UAV), and allowing the dynamic and flexible network deployments enables the supplement or/and replacement of the terrestrial base stations (BSs). However, in conventional multiple-input-multiple-output (MIMO) systems, high-speed communications are significantly limited by channel crosstalks and spectrum scarcities. An orbit angular momentum (OAM) wireless network, allowing co-existence of multiple physical channels within the same frequency band, offers new degrees of freedom to address this dilemma. In this paper, we investigate the UAV-based A2G radio vortex wireless networks and study its channel model. Then we propose a branch and bound search-based mode selection (BBS-MS) scheme, which uses the spatial distribution characteristics of vortex beams to optimize the spectrum efficiency (SE). Theoretical derivations and numerical results demonstrate that our developed BBS-MS scheme can obtain the optimal performance, which outperforms conventional OAM-based MIMO systems. Also, it possesses a lower complexity compared with exhaustive searches.

scholarly journals A Semiempirical MIMO Channel Model in Obstructed Viaduct Scenarios on High-Speed Railway

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Tao Zhou ◽  
Cheng Tao ◽  
Liu Liu ◽  
Zhenhui Tan
Keyword(s):  
High Speed ◽  
Channel Model ◽  
Mimo Systems ◽  
Multiple Input Multiple Output ◽  
Time Correlation ◽  
Time Correlation Function ◽  
Mimo Channel ◽  
High Speed Railway ◽  
Single Input Single Output ◽  
Single Output

A semiempirical multiple-input multiple-output (MIMO) channel model is proposed for high-speed railway (HSR) viaduct scenarios. The proposed MIMO model is based on the combination of realistic single-input single-output (SISO) channel measurement results and a theoretical geometry-based stochastic model (GBSM). Temporal fading characteristics involvingK-factor and Doppler power spectral density (PSD) are derived from the wideband measurement under an obstructed viaduct on Zhengzhou-Xi’an HSR in China. The GBSM composed of a one-ring model and an elliptical model is employed to describe the entire propagation environment. Environment-related parameters in the GBSM are determined by the measured temporal fading properties. And a close agreement is achieved between the model results and measured data. Finally, a deterministic simulation model is established to perform the analysis of the space-time correlation function, the space-Doppler PSD, and the channel capacity for the measured scenario. This model is more realistic and particularly beneficial for the performance evaluation of MIMO systems in HSR environments.

An Efficient Distributed Single-hop Relay Supporting (EDSRS) MAC Protocol for Wireless Sensor Networks

2019 ◽  
Vol 9 (2) ◽  
pp. 153-164
Author(s):  
Arvind Kakria ◽  
Trilok Chand Aseri
Keyword(s):  
Energy Efficiency ◽  
Cooperative Communication ◽  
Mimo Systems ◽  
Mac Protocol ◽  
Multiple Input Multiple Output ◽  
Relay Node ◽  
Base Stations ◽  
Destination Node ◽  
Distributed Coordination ◽  
Hardware Complexity

Background & Objective: Wireless communication has immensely grown during the past few decades due to significant demand for mobile access. Although cost-effective as compared to their wired counterpart, maintaining good quality-of-service (QoS) in these networks has always remained a challenge. Multiple-input Multiple-output (MIMO) systems, which consists of multiple transmitter and receiver antennas, have been widely acknowledged for their QoS and transmit diversity. Though suited for cellular base stations, MIMO systems are not suited for small-sized wireless nodes due to their hardware complexity, cost, and increased power requirements. Cooperative communication that allows relays, i.e. mobile or fixed nodes in a communication network, to share their resources and forward other node’s data to the destination node has substituted the MIMO systems nowadays. To harness the full benefit of cooperative communication, appropriate relay node selection is very important. This paper presents an efficient single-hop distributed relay supporting medium access control (MAC) protocol (EDSRS) that works in the single-hop environment and improves the energy efficiency and the life of relay nodes without compensating the throughput of the network. Methods: The protocol has been simulated using NS2 simulator. The proposed protocol is compared with energy efficient cooperative MAC protocol (EECOMAC) and legacy distributed coordination function (DCF) on the basis of throughput, energy efficiency, transmission delay and an end to end delay with various payload sizes. Result and Conclusion: The result of the comparison indicates that the proposed protocol (EDSRS) outperforms the other two protocols.

scholarly journals Statistical Beamforming for Massive MIMO Systems with Distinct Spatial Correlations

Sensors ◽  
2020 ◽  
Vol 20 (21) ◽  
pp. 6255
Author(s):  
Taehyoung Kim ◽  
Sangjoon Park
Keyword(s):  
Massive Mimo ◽  
Degrees Of Freedom ◽  
Mimo Systems ◽  
Mimo System ◽  
Multiple Input Multiple Output ◽  
High Signal ◽  
Spatial Correlations ◽  
Channel Correlation ◽  
Low Correlation ◽  
Noise Ratio

In this paper, we propose a novel statistical beamforming (SBF) method called the partial-nulling-based SBF (PN-SBF) to serve a number of users that are undergoing distinct degrees of spatial channel correlations in massive multiple-input multiple-output (MIMO) systems. We consider a massive MIMO system with two user groups. The first group experiences a low spatial channel correlation, whereas the second group has a high spatial channel correlation, which can happen in massive MIMO systems that are based on fifth-generation networks. By analyzing the statistical signal-to-interference-plus-noise ratio, it can be observed that the statistical beamforming vector for the low-correlation group should be designed as the orthogonal complement for the space spanned by the aggregated channel covariance matrices of the high-correlation group. Meanwhile, the spatial degrees of freedom for the high-correlation group should be preserved without cancelling the interference to the low-correlation group. Accordingly, a group-common pre-beamforming matrix is applied to the low-correlation group to cancel the interference to the high-correlation group. In addition, to deal with the intra-group interference in each group, the post-beamforming vector for each group is designed in the manner of maximizing the signal-to-leakage-and-noise ratio, which yields additional performance improvements for the PN-SBF. The simulation results verify that the proposed PN-SBF outperforms the conventional SBF schemes in terms of the ergodic sum rate for the massive MIMO systems with distinct spatial correlations, without the rate ceiling effect in the high signal-to-noise ratio region unlike conventional SBF schemes.

scholarly journals Design and VLSI Implementation of a Reduced-Complexity Sorted QR Decomposition for High-Speed MIMO Systems

Electronics ◽  
2020 ◽  
Vol 9 (10) ◽  
pp. 1657
Author(s):  
Lu Sun ◽  
Bin Wu ◽  
Tianchun Ye
Keyword(s):  
Communication Systems ◽  
High Speed ◽  
Mimo Systems ◽  
Multiple Input Multiple Output ◽  
Cmos Technology ◽  
Qr Decomposition ◽  
Time Sharing ◽  
Hardware Complexity ◽  
Givens Rotation ◽  
Hardware Efficiency

In this article, a low-complexity and high-throughput sorted QR decomposition (SQRD) for multiple-input multiple-output (MIMO) detectors is presented. To reduce the heavy hardware overhead of SQRD, we propose an efficient SQRD algorithm based on a novel modified real-value decomposition (RVD). Compared to the latest study, the proposed SQRD algorithm can save the computational complexity by more than 44.7% with similar bit error rate (BER) performance. Furthermore, a corresponding deeply pipelined hardware architecture implemented with the coordinate rotation digital computer (CORDIC)-based Givens rotation (GR) is designed. In the design, we propose a time-sharing Givens rotation structure utilizing CORDIC modules in idle state to share the concurrent GR operations of other CORDIC modules, which can further reduce hardware complexity and improve hardware efficiency. The proposed SQRD processor is implemented in SMIC 55-nm CMOS technology, which processes 62.5 M SQRD per second at a 250-MHz operating frequency with only 176.5 kilo-gates. Compared to related studies, the proposed design has the best normalized hardware efficiency and achieves a 6-Gbps MIMO data rate which can support current high-speed wireless communication systems such as IEEE 802.11ax.

scholarly journals Design Issues and Challenges in Indoor MIMO Antenna Systems

2020 ◽  
Vol 8 (6) ◽  
pp. 3842-3846
Keyword(s):  
High Speed ◽  
Mimo Systems ◽  
Mimo System ◽  
Multiple Input Multiple Output ◽  
Research Work ◽  
Antenna System ◽  
Design Parameters ◽  
Future Research ◽  
Design Issues ◽  
Mimo Antenna

The promising solution for next generation wireless communication system is multiple input multiple output (MIMO) system. It can transmit and receive data from different channels simultaneously without any need of additional frequency band. In this paper the design issues and challenges in MIMO antenna system for different applications have been reviewed. The major applications of MIMO systems include Wi-Fi, High Speed Packet Access, LTE, WiMAX (4G), and also MIMO has been used in power line communication. Implementation of MIMO antenna system is dependent on important parameters such as: Peak gain, Average Gain, Mutual Coupling, Envelop Correlation Coefficient (ECC), Total Active Reflection Coefficient (TARC), Signal polarization and Miniaturization of antenna system. Hence an optimal MIMO antenna design to suit for communication applications in an indoor environment is a challenging task. This paper proposes comparative study for the different MIMO antenna parameters. The different modeling techniques for MIMO antenna system are surveyed and areas for future research work in line with tradeoffs between different design parameters are suggested.

scholarly journals Parametric codebook design for efficient signal transmission using uniform circular arrays

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Junsik Shin ◽  
Junyeub Suh ◽  
Sangchun Park ◽  
Wonjin Sung
Keyword(s):  
Antenna Arrays ◽  
Channel Model ◽  
Mimo Systems ◽  
Signal Transmission ◽  
Multiple Input Multiple Output ◽  
Base Station ◽  
Step Size ◽  
Codebook Design ◽  
Construction Methods ◽  
Planar Array

AbstractIn order to improve the quality of the received signal and system spectral efficiency, accurate beamforming using a given antenna array is essential for multiple-input multiple-output (MIMO) systems. To obtain desired MIMO transmission performance, construction of codebooks which are composed of matching beamforming vectors to the array structure is important. To effectively cover different types of mobile traffic, the base station for 5G new radio employs antenna arrays in various sizes and shapes. Nevertheless, the codebooks adopted by the 3GPP standard so far are based on the uniform linear array and the uniform planar array, necessitating design techniques for a wider class of antenna arrays. In this paper, we propose codebook construction methods for the uniform circular array with parameters to flexibly set the initial phase and step size based on the channel characteristics of the user equipment (UE). When tested over the 3GPP spatial channel model, the proposed codebooks show a substantial amount of gain over the conventional codebooks in all UE locations within the cell.

scholarly journals A novel method for joint- PAPR mitigation in OFDM-based massive MIMO downlink systems

2018 ◽  
Vol 7 (3) ◽  
pp. 1185 ◽  
Author(s):  
Padarti Vijaya Kumar ◽  
Venkateswara Rao Nandanavanam
Keyword(s):  
Massive Mimo ◽  
High Speed ◽  
Degrees Of Freedom ◽  
Multiple Input Multiple Output ◽  
Average Power ◽  
Data Communication ◽  
Multiple Input ◽  
Input Multiple Output ◽  
High Speed Data ◽  
Mimo Downlink

Massive MIMO has gained much attention with the increase in the high speed data communication. The problem of peak-to-average power ratio (PAPR) is considered, the detrimental aspects in OFDM based massive multiple-input multiple-output (MIMO) downlink systems. The previous works done in reduction of PAPR problem using convex optimization are computationally inefficient. We considered Bayesian approach to mitigate PAPR by utilizing the redundant degrees of freedom (DOF) of the transmit array, which effectively reduced the level of PAPR. The performance or numerical results indicate the applied algorithm achieved a good improvement over the existing techniques in terms of the PAPR reduction.  

scholarly journals Sum Rate Analysis of MU-MIMO with a 3D MIMO Base Station Exploiting Elevation Features

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Xingwang Li ◽  
Lihua Li ◽  
Fupeng Wen ◽  
Junfeng Wang ◽  
Chao Deng
Keyword(s):  
Channel Model ◽  
Mimo Systems ◽  
Multiple Input Multiple Output ◽  
Three Dimensional ◽  
Base Station ◽  
Rate Performance ◽  
High Rise ◽  
Rate Analysis ◽  
Input Multiple Output ◽  
Sum Rate

Although the three-dimensional (3D) channel model considering the elevation factor has been used to analyze the performance of multiuser multiple-input multiple-output (MU-MIMO) systems, less attention is paid to the effect of the elevation variation. In this paper, we elaborate the sum rate of MU-MIMO systems with a 3D base station (BS) exploiting different elevations. To illustrate clearly, we consider a high-rise building scenario. Due to the floor height, each floor corresponds to an elevation. Therefore, we can analyze the sum rate performance for each floor and discuss its effect on the performance of the whole building. This work can be seen as the first attempt to analyze the sum rate performance for high-rise buildings in modern city and used as a reference for infrastructure.

scholarly journals Effective Power Allocation Using for Transmit Source In MIMO Relay Communication

2021 ◽  
Vol 5 (3) ◽  
Author(s):  
Hoai Trung Tran
Keyword(s):  
Channel Capacity ◽  
Communication Systems ◽  
High Speed ◽  
Mimo Systems ◽  
Multiple Input Multiple Output ◽  
Optimization Method ◽  
Radio Communication ◽  
Second Derivatives ◽  
Multiple Input ◽  
Input Multiple Output

The Multiple Input Multiple Output (MIMO) systems using relays are of interest for high-speed radio communication systems. Currently, most of the articles are interested in the model of three nodes with purposes such as increasing the channel capacities (mutual information) or reducing the minimum mean square of error. This paper extends to more than one relay and is concerned with the maximum channel capacity. It is assumed that the channel matrices between source and relay as well as relay and receiver are random matrices; the relay precoders are also assumed to be random and known at the receiver. The article proposes that the Lagrange multiplier finding algorithm using the Newton – Raphson optimization method is more straightforward than the traditional finding algorithm using the first and second derivatives but still gives a higher channel capacity.

scholarly journals Optimal Topology Formation and Adaptation of Integrated Access and Backhaul Networks

2021 ◽  
Vol 1 ◽  
Author(s):  
Meryem Simsek ◽  
Murali Narasimha ◽  
Oner Orhan ◽  
Hosein Nikopour ◽  
Wei Mao ◽  
...  
Keyword(s):  
Cellular Networks ◽  
High Speed ◽  
Random Sequence ◽  
Multiple Input Multiple Output ◽  
Optimal Solution ◽  
Network Capacity ◽  
Base Stations ◽  
Optimal Topology ◽  
Wireless Backhaul ◽  
Topology Formation

With the increasing densification of cellular networks, it has become exceedingly difficult to provide traditional fiber backhaul access to each cell site, which is especially true for small cell base stations (SBSs). The increasing maturity of millimeter wave (mmWave) communication coupled with multiple-input-multiple-output (MIMO) and beamforming technologies has opened up the possibility of providing high-speed wireless backhaul to such cell sites. The third-generation partnership project (3GPP) is defining an integrated access and backhaul (IAB) architecture for the fifth-generation (5G) cellular networks, in which the same infrastructure and spectral resources are used for both the access and the backhaul. In IAB networks, SBSs, so-called IAB nodes, act either as relay nodes carrying the traffic through multiple hops from a macrocell to an end user and vice versa or as access points to serve user equipments (UEs) in their proximity. To this end, the topology of such IAB networks is essential to enable efficient traffic flow and minimize congestion or increase robustness to backhaul link failure. In this paper, we propose a topology formation algorithm together with methodologies to implement it in real networks and compare it with a standard random sequence approach as well as with an optimal topology obtained using dynamic programming. Our simulation results demonstrate that the proposed algorithm outperforms the random sequence approach by 26% on average in terms of lower bound of the network capacity and is up to 99.7% close to the optimal solution, while being significantly less complex.

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