scholarly journals Optimal UAV Deployment and Resource Management in UAV Relay Networks

Sensors ◽  
2021 ◽  
Vol 21 (20) ◽  
pp. 6878
Author(s):  
Sang Ik Han ◽  
Jaeuk Baek
Keyword(s):  
Resource Allocation ◽  
Three Dimensional ◽  
Optimal Solution ◽  
Relay Node ◽  
Base Station ◽  
Computational Effort ◽  
Relay Network ◽  
Relay Location ◽  
Aerial Vehicle ◽  
A Cell

UAV equipped three-dimensional (3D) wireless networks can provide a solution for the requirements of 5G communications, such as enhanced Mobile Broadband (eMBB) and massive Machine Type Communications (mMTC). Especially, the introduction of an unmanned aerial vehicle (UAV) as a relay node can improve the connectivity, extend the terrestrial base station (BS) coverage and enhance the throughput by taking advantage of a strong air-to-ground line of sight (LOS) channel. In this paper, we consider the deployment and resource allocation of UAV relay network (URN) to maximize the throughput of user equipment (UE) within a cell, while guaranteeing a reliable transmission to UE outside the coverage of BS. To this end, we formulate joint UAV deployment and resource allocation problems, whose analytical solutions can be hardly obtained, in general. We propose a fast and practical algorithm to provide the optimal solution for the number of transmit time slots and the UAV relay location in a sequential manner. The transmit power at BS and UAV is determined in advance based on the availability of channel state information (CSI). Simulation results demonstrate that the proposed algorithms can significantly reduce the computational effort and complexity to determine the optimal UAV location and transmit time slots over an exhaustive search.

scholarly journals Three-Dimensional Resource Allocation in D2D-Based V2V Communication

Electronics ◽  
2019 ◽  
Vol 8 (9) ◽  
pp. 962 ◽  
Author(s):  
Usman Ali Khan ◽  
Sang Sun Lee
Keyword(s):  
Resource Allocation ◽  
Three Dimensional ◽  
Relay Node ◽  
Cellular Phone ◽  
User Equipment ◽  
Moving Vehicle ◽  
3 Dimensional ◽  
V2v Communication ◽  
3Rd Generation Partnership Project

Device-to-Device (D2D) communication is the major enabler of Vehicle-to-Everything communication in 3rd Generation Partnership Project (3GPP) Release 14. The user equipment/device can engage either in direct communication with the infrastructure, use a relay node, or it can communicate directly with another device with or without infrastructure support. The user equipment can be either a hand-held cellular device or a moving vehicle. The coexistence of cellular user equipment with the vehicular user equipment imposes different Quality of Service (QOS) requirements due to the rapid mobility of the vehicles and interference. Resource allocation is an important task by which the user equipment is allocated the required resources based on different QOS parameters. In this paper, we introduced the case of three types of users which share uplink resources: two types of vehicular users, and a third user that acts as a handheld cellular phone, which is nearly static. By keeping in mind, the differential QOS requirements for the three types of users, we have calculated the optimum power and then applied a 3-dimensional graph-based matching and hypergraph coloring based resource block (RB) allocation.

scholarly journals Demonstration and application of diffusive and ballistic wave propagation for drone-to-ground and drone-to-drone wireless communications

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Peter J. Burke
Keyword(s):  
Wave Propagation ◽  
Electromagnetic Wave ◽  
Path Loss ◽  
Base Station ◽  
Physical Models ◽  
Mapping Technology ◽  
Aerial Vehicle ◽  
A Cell ◽  
Independent Path ◽  
The Waves

Abstract In order to determine how an electromagnetic wave propagates from a base station to a cell phone or a wirelessly connected device, we use a novel Unmanned Aerial Vehicle (UAV) mapping technology to map the cellular network coverage at various altitudes in various terrains (flat, hilly, mountainous). For the flat terrains, the waves are shown to propagate ballistically: They have an altitude independent path loss consistent with minimal scatter in the propagation from transmitter to (aerial) receiver. In mountainous terrain, the waves are shown to propagate in the diffuse regime, and demonstrate a 10 dB increase in received signal intensity per 100′ of altitude gain, up to 400′. In the intermediate case, evidence of coherent wave interference is clearly observed in altitude independent interference patterns. These general observations can be used to build a physical or empirical model for drone-to-ground and drone-to-drone propagation, for which existing models are shown to fail. While important for building physical models of wave propagation in wireless networks, this method can be used more generally to determine the magnitude and phase of an electromagnetic wave at every point in space, as well as usher in the era of drone-to-ground and drone-to-drone communications.

scholarly journals Resource Allocation for Vertical Sectorization in LTE-Advanced Systems

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Lei Song ◽  
Mugen Peng ◽  
Yan Li
Keyword(s):  
Resource Allocation ◽  
Interference Cancellation ◽  
Multiple Input Multiple Output ◽  
Three Dimensional ◽  
Base Station ◽  
System Level ◽  
System Level Simulation ◽  
Lte Advanced ◽  
Input Multiple Output ◽  
Resource Allocation Scheme

Massive multiple input multiple output (MIMO) technology has been discussed widely in the past few years. Three-dimensional MIMO (3D MIMO) can be seen as a promising technique to realize massive MIMO to enhance the performance of LTE-Advanced systems. Vertical sectorization can be introduced by means of adjusting the downtilt of transmitting antennas. Thus, the radiowave from a base station (BS) to a group of user equipments (UE) can be divided into two beams which point at two different areas within a cell. Intrasector interference is inevitable since the resources are overlapped. In this paper, the influence of intrasector interference is analyzed and an enhanced resource allocation scheme for vertical sectorization is proposed as a method of interference cancellation. Compared with the conventional 2D MIMO scenarios, cell average throughput of the whole system can be improved by vertical sectorization. System level simulation is performed to evaluate the performance of the proposed scheme. In addition, the impacts of downtilt parameters and intersite distance (ISD) on spectral efficiency and cell coverage are presented.

scholarly journals Resource allocation for energy harvesting assisted D2D communications underlaying OFDMA cellular networks

2021 ◽  
Author(s):  
Shuo Yu ◽  
Ling Guan
Keyword(s):  
Resource Allocation ◽  
Energy Harvesting ◽  
Cellular Networks ◽  
Time Slot ◽  
Optimal Solution ◽  
Base Station ◽  
Multiple Time ◽  
Time Cost ◽  
D2d Communications ◽  
Transmission Process

D2D communications underlaying cellular networks has become very popular recently. Inter- ference between cellular users and D2D users is one of the tricky issues we need to solve. Another challenging issue is limited battery lives. In this thesis, we address these two issues together by introducing an energy harvesting (EH) assisted D2D model where the whole transmission process is divided into multiple time slots. At the beginning of every time slot, each D2D user will update the remaining energy level to the base station (BS) and the BS will then decide whether the D2D user should harvest energy or transmit data. The objective is to maximize sum throughput for all D2D users. To solve the problem, we first adopt the NOMAD algorithm, then propose a heuristic algorithm as sub-optimal solution. Numerical results show that our proposed algorithm can achieve almost the same sum throughput at a significantly smaller time cost.

scholarly journals A Synthesizable VHDL Model of the Exact Solution for Three-dimensional Hyperbolic Positioning System

VLSI Design ◽  
2002 ◽  
Vol 15 (2) ◽  
pp. 507-520 ◽  
Author(s):  
Ralph Bucher ◽  
D. Misra
Keyword(s):  
Exact Solution ◽  
Three Dimensional ◽  
Base Station ◽  
Time Of Arrival ◽  
Positioning System ◽  
Worst Case ◽  
Accuracy And Precision ◽  
A Cell ◽  
Bit Vector ◽  
Hyperbolic Positioning

This paper presents a synthesizable VHDL model of a three-dimensional hyperbolic positioning system algorithm. The algorithm obtains an exact solution for the three-dimensional location of a mobile given the locations of four fixed stations (like a global positioning system [GPS] satellite or a base station in a cell) and the signal time of arrival (TOA) from the mobile to each station. The detailed derivation of the steps required in the algorithm is presented. A VHDL model of the algorithm was implemented and simulated using the IEEE numeric_std package. Signals were described by a 32-bit vector. Simulation results predict location of the mobile is off by 1 m for best case and off by 36 m for worst case. A C + + program using real numbers was used as a benchmark for the accuracy and precision of the VHDL model. The model can be easily synthesized for low power hardware implementation.

Optimal Beamforming and Performance Analysis of Wireless Relay Networks with Unmanned Aerial Vehicle

Frequenz ◽  
2015 ◽  
Vol 69 (3-4) ◽  
Author(s):  
Jian Ouyang ◽  
Min Lin
Keyword(s):  
Performance Analysis ◽  
Unmanned Aerial Vehicle ◽  
Large Scale ◽  
Path Loss ◽  
Base Station ◽  
Relay Network ◽  
Rician Fading ◽  
Amplify And Forward ◽  
Aerial Vehicle ◽  
Optimal Beamforming

AbstractIn this paper, we investigate a wireless communication system employing a multi-antenna unmanned aerial vehicle (UAV) as the relay to improve the connectivity between the base station (BS) and the receive node (RN), where the BS–UAV link undergoes the correlated Rician fading while the UAV–RN link follows the correlated Rayleigh fading with large scale path loss. By assuming that the amplify-and-forward (AF) protocol is adopted at UAV, we first propose an optimal beamforming (BF) scheme to maximize the mutual information of the UAV-assisted dual-hop relay network, by calculating the BF weight vectors and the power allocation coefficient. Then, we derive the analytical expressions for the outage probability (OP) and the ergodic capacity (EC) of the relay network to evaluate the system performance conveniently. Finally, computer simulation results are provided to demonstrate the validity and efficiency of the proposed scheme as well as the performance analysis.

scholarly journals Resource allocation for energy harvesting assisted D2D communications underlaying OFDMA cellular networks

2021 ◽  
Author(s):  
Shuo Yu ◽  
Ling Guan
Keyword(s):  
Resource Allocation ◽  
Energy Harvesting ◽  
Cellular Networks ◽  
Time Slot ◽  
Optimal Solution ◽  
Base Station ◽  
Multiple Time ◽  
Time Cost ◽  
D2d Communications ◽  
Transmission Process

D2D communications underlaying cellular networks has become very popular recently. Inter- ference between cellular users and D2D users is one of the tricky issues we need to solve. Another challenging issue is limited battery lives. In this thesis, we address these two issues together by introducing an energy harvesting (EH) assisted D2D model where the whole transmission process is divided into multiple time slots. At the beginning of every time slot, each D2D user will update the remaining energy level to the base station (BS) and the BS will then decide whether the D2D user should harvest energy or transmit data. The objective is to maximize sum throughput for all D2D users. To solve the problem, we first adopt the NOMAD algorithm, then propose a heuristic algorithm as sub-optimal solution. Numerical results show that our proposed algorithm can achieve almost the same sum throughput at a significantly smaller time cost.

scholarly journals Aerial Cooperative Jamming for Cellular-Enabled UAV Secure Communication Network: Joint Trajectory and Power Control Design

Sensors ◽  
2019 ◽  
Vol 19 (20) ◽  
pp. 4440 ◽  
Author(s):  
Hanming Sun ◽  
Bin Duo ◽  
Zhengqiang Wang ◽  
Xiaochen Lin ◽  
Changchun Gao
Keyword(s):  
Communication Networks ◽  
Secure Communication ◽  
Optimal Solution ◽  
Base Station ◽  
Convex Constraints ◽  
Secrecy Rate ◽  
Worst Case ◽  
Cooperative Jamming ◽  
Mission Period ◽  
Aerial Vehicle

To improve the secrecy performance of cellular-enabled unmanned aerial vehicle (UAV) communication networks, this paper proposes an aerial cooperative jamming scheme and studies its optimal design to achieve the maximum average secrecy rate. Specifically, a base station (BS) transmits confidential messages to a UAV and meanwhile another UAV performs the role of an aerial jammer by cooperatively sending jamming signals to oppose multiple suspicious eavesdroppers on the ground. As the UAVs have the advantage of the controllable mobility, the objective is to maximize the worst-case average secrecy rate by the joint optimization of the two UAVs’ trajectories and the BS’s/UAV jammer’s transmit/jamming power over a given mission period. The objective function of the formulated problem is highly non-linear regarding the optimization variables and the problem has non-convex constraints, which is, in general, difficult to achieve a globally optimal solution. Thus, we divide the original problem into four subproblems and then solve them by applying the successive convex approximation (SCA) and block coordinate descent (BCD) methods. Numerical results demonstrate that the significantly better secrecy performance can be obtained by using the proposed algorithm in comparison with benchmark schemes.

scholarly journals Energy-Efficient Resource Allocation in Uplink Multiuser Massive MIMO Systems

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Ying Hu ◽  
Baofeng Ji ◽  
Yongming Huang ◽  
Fei Yu ◽  
Luxi Yang
Keyword(s):  
Resource Allocation ◽  
Antenna Arrays ◽  
Energy Efficient ◽  
Mimo Systems ◽  
Optimal Solution ◽  
Base Station ◽  
Green Communications ◽  
Resource Allocation Algorithm ◽  
Efficient Resource ◽  
Energy Efficient Resource Allocation

Energy-efficient communications, namely, green communications, has attracted increasing attention due to energy shortage and greenhouse effect. Motivated by this, we consider the uplink energy-efficient resource allocation in multiuser massive multiple-input multiple-output (MIMO) systems. Specifically, we consider that both the number of antenna arrays at the base station (BS) and the transmit data rate at UE are adjusted adaptively to maximize the energy efficiency. Firstly, we demonstrate the existence of a unique resource allocation solution that is globally optimal by exploiting the properties of objective function. Then we develop an iterative algorithm to solve it. By transforming the originally fractional optimization problem into an equivalent subtractive form using the properties of fractional programming, we develop another efficient iterative resource allocation algorithm. Simulation results have validated the effectiveness of the proposed two algorithms and have shown that both algorithms can fast converge to a near-optimal solution in a small number of iterations.

Fair Deployment of an Unmanned Aerial Vehicle Base Station for Maximal Coverage

2019 ◽  
Vol E102.B (10) ◽  
pp. 2014-2020
Author(s):  
Yancheng CHEN ◽  
Ning LI ◽  
Xijian ZHONG ◽  
Yan GUO
Keyword(s):  
Unmanned Aerial Vehicle ◽  
Base Station ◽  
Aerial Vehicle
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