Signal Steering and Beamforming for Drone Communications

Beamforming for unmanned aerial vehicles (UAVs) that uses the UAV's and remote station's locations and the UAV's rotation to determine the beamforming direction without channel characterization. The UAV determines the direction based on its own location, rotation, and the remote station's location. It then beams data to that direction without channel feedback or training. This allows dynamic beamforming without the overhead and complexity of frequent channel characterization as the UAV moves.

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In this paper, we investigate a simultaneous transmitting and reflecting reconfigurable intelligent surface (STAR-RIS)-assisted non-orthogonal multiple access (NOMA) communication system where the STAR-RIS is mounted on an unmanned aerial vehicle (UAV) with adjustable altitude. Due to severe blockages in urban environments, direct links from base station (BS) users are assumed unavailable, signal transmission realized via STAR-RIS. We formulate joint optimization problem that maximizes sum rate by jointly optimizing UAVs altitude, BS beamforming vectors, phase shifts, while considering Rician fading channels altitude-dependent factors. To tackle maximum achievable problem, adopt block-wise framework employ semidefinite relaxation gradient descent methods. Simulation results show proposed scheme achieves up 22% improvement significant reduction bit error (BER) compared benchmark schemes, demonstrating its effectiveness integrating UAV NOMA networks.

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Multi-Beam frequency scanning leaky-wave antennas (FBS-LWAs) offer a viable solution for hardware miniaturization in direction-of-arrival (DOA) estimation systems. However, the presence of multiple spatial harmonics results responses directions given incident source, introducing ambiguity and significantly challenging accurate DOA estimation. Moreover, due to nonlinear response FBS-LWA, its matrix does not satisfy Vandermonde structure, which renders common rank-recovery techniques ineffective processing coherent signals. As result, sources using multi-beam FBS-LWAs remains an open problem. To address this issue, paper proposes novel method signals based on antennas. First, received are transformed into domain via fast Fourier transform (FFT) construct signal data from covariance is computed.Then, conventional beamforming (CBF) employed obtain initial estimate angle set, will be further refined by smaller grid form candidate set. Finally, maximum likelihood algorithm stochastic principle (Sto-ML) used suppress interference parasitic select final estimates Simulation show that propose... Read More

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The development of beyond 5G (B5G) future wireless communication networks (FWCN) needs novel solutions to support high-speed, reliable, and low-latency communication. Unmanned aerial vehicles (UAVs) reconfigurable intelligent surfaces (RISs) are promising techniques that can enhance connectivity in urban environments where tall buildings block line-of-sight (LoS) links. However, existing UAV-assisted strategies do not fully address key challenges like mobility management, handover failures (HOFs), path disorders dense environments. This paper introduces a deep deterministic policy gradient (DDPG)-based UAV-RIS framework overcome these limitations. proposed jointly optimizes UAV trajectories RIS phase shifts improve throughput, energy efficiency (EE), LoS probability while reducing outage (OP) HOF. A modified K-means clustering algorithm is used efficiently partition the ground users (GUs) considering newly added GUs as well. DDPG algorithm, based on reinforcement learning (RL), adapts positioning configurations continuous action space. Simulation results show approach significantly r... Read More

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This article considers a multi-cell wireless network comprising of conventional user equipment (UE), sensor devices and unmanned aerial vehicles (UAVs) or drones. UAVs are used to assist base station, e.g., improve coverage collect data from devices. The problem at hand is optimize the (i) sub-carrier assigned cell (ii) position each UAV, (iii) transmit power following nodes: stations UAVs. We outline two-stage approach maximize fairness-aware sum-rate UE In first stage, genetic algorithm (GA)-based assign sub-band all cells determine location UAV. Then, in second linear program results demonstrate that our proposed achieves approximately 97.43% optimal obtained via brute-force search. It also attains on average 98.78% performance computationally intensive benchmark requires over 478% longer run-time. Furthermore, it outperforms GA-based allocation heuristic by 221.39%.

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In this paper, we study an unmanned aerial vehicle (UAV)-enabled maritime communication system, where a single rotary-wing UAV is dispatched to communicate with multiple moving vessel users. We formulate the energy efficiency optimization problem propulsion consumption model by jointly considering transmit power, flight trajectory, and velocity. The non-convex fractional programming problem, which makes it difficult obtain optimal solution. To solve propose efficient algorithm utilizing successive convex approximation techniques Dinkelbach (SCAD) algorithm. particular, divide original into three involved sub-problems that can be solved adopting alternate optimization. order satisfy constraint of maximum velocity, modified trajectory matching positions. Numerical results demonstrate effectiveness proposed scheme effectively improves for communication. Meanwhile, SCAD shows outstanding performance in terms long-duration flight.

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Wideband extremely large array antenna system and an OFDM-based hybrid beamforming method for improving data rate by maximizing signal strength in wideband MIMO systems with a large number of antennas. The method involves separate analog and baseband beamforming steps. The analog beamforming is designed using oblique projection matrices to decompose the hybrid field into orthogonal near-field and far-field components. A common analog beamforming matrix is then extracted by finding dominant eigenvectors from the decomposed matrices. Baseband beamforming is done separately for each subcarrier to maximize data rate on the effective channels.

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Abstract The present work investigates hierarchical beamforming strategies for millimeterwave communication systems, focusing on amplitude tapering and subarray approaches. research addresses key challenges in Angle of Arrival (AoA) estimation beam management, essential nextgeneration wireless networks. taperingbased method, implemented a 4element linear array, demonstrated precise beamwidth sidelobe control, enabling search with reduced implementation effort. Experimental validation confirmed its effectiveness identifying transmission directions under lineofsight conditions; however, reliance fullarray activation made it less energyefficient more sensitive to multipathinduced errors reflective environments. Conversely, the approach, applied an 8element showcased enhanced robustness against multipath effects quantifiable power savings. By activating only subset elements at each level, this method achieved estimated 42% reduction average per configuration significantly fewer evaluations than exhaustive search. Its adaptability supported efficient AoA b... Read More

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ABSTRACT Fifthgeneration (5G) and beyond communication systems, supported by Intelligent Reflecting Surfaces (IRS), frequently face challenges like less reliable communication, increased energy consumption, high latency. Passive beamforming at the reflecting surfaces is essential to enhance received signal quality, coverage, overall performance of system. Implementing passive in IRSaided systems poses vehicular environments, particularly with roadside IRS units fastmoving users. This paper proposes an efficient moderately lowcomplexity algorithm for highvelocity using mmWave networks. The optimizes reflection coefficients proposed Successive Convex Approximation based Interior Point Method (SCAIPM). iteratively linearizes objective function constraints, incorporates a barrier stability, uses Newton's method updates. efficiently handles nonconvex optimization problems improves quality dynamic IRSbased systems. simulation results show that delivers higher data rate signaltonoise ratio (SNR), low system complexity.

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Millimeter wave non-orthogonal multiple access beam management for multi-drone networks. The method involves optimizing beamforming for a master drone and multiple slave drones using channel information. It groups the slaves based on angle and solves analog and digital beamforming vectors to align beams. This enables accurate and quick beam management in high-dynamic multi-drone systems.

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Enhancing wireless communication for unmanned aerial vehicles (UAVs) using directional antennas and flight path information. The directional antennas mitigate interference by redirecting the main beam towards base stations while minimizing interference from other sources. Flight path information is used to optimize handover and interference mitigation for UAVs by leveraging the predictable aerial channel environment. This allows tailoring network parameters like handover triggers and reporting sets for different flight regions.

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Beamforming technique to improve wireless communication links between airspace network base stations and aerial vehicles like urban air mobility (UAM) aircraft. The base stations select optimal beam directions based on the known flight paths of UAM vehicles to focus the signal towards them. This mitigates interference effects specific to the airspace network environment and improves link performance compared to omnidirectional transmission.

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IRS-assisted high-speed multi-UAV communication system beam tracking to enable reliable and effective communication between ground base stations and multiple high-speed moving UAVs. The method involves using intelligent reflecting surfaces (IRS) to help align beams between the base station and UAVs. It involves predicting the UAV spatial angles, optimizing base station and IRS beamforming matrices to maximize edge UAV SNR, and aligning dual beams using the predicted angles. This improves UAV performance by leveraging IRS to compensate for mobility and external factors.

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Relay forwarding method and system for unmanned aerial vehicles (UAVs) with integrated sensing capabilities to improve millimeter wave (mmWave) relay performance. The method involves using the UAV's sensing data to accurately form mmWave beams at the user position. This mitigates errors from integrated sensing. First, the user broadcasts a centimeter wave signal, the base station feeds back confirmation, and the user selects the strongest one. Then, the UAV flies to a position with line-of-sight to both. The UAV adjusts its mmWave reflector angles based on sensed user location to form a beam. By combining centimeter feedback and sensing, the UAV finds the angles with max mmWave power at the user.

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Adaptive beam tracking method for unmanned aerial vehicle (UAV) communication that improves efficiency and performance by dynamically adjusting training frequency based on UAV motion state and optimizing beam width using a layered codebook. The steps are: 1) Estimate UAV motion state, 2) Adjust training frequency based on motion state (higher for fast motion), 3) Optimize beam width using a layered codebook, 4) Select optimal beam width based on motion state, 5) Update codebook and weights with feedback. This adapts to UAV motion and terrain for better tracking and reduces training vs fixed methods. However, it requires motion estimation and energy for adaptation.

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Sparse array of unmanned aerial vehicles (UAVs) for beamforming in three-dimensional space. The array has sparsely distributed UAVs with arbitrary spacing between them. Each UAV has an antenna. The UAVs communicate wirelessly. This allows flexible, adaptive beamforming by controlling the UAV positions and antenna phases. It enables efficient, cooperative beamforming in complex 3D environments with discontinuous spaces due to obstructions.

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Beamforming method for unmanned aerial vehicle (UAV) communications that allows rapid and accurate beam alignment between a command UAV and a mission UAV. The method uses geographic information system (GIS) data from the mission UAV to enable the command UAV to generate narrow beams pointing directly at the mission UAV. This improves tracking accuracy, UAV endurance, and data rate compared to existing beamforming techniques. The mission UAV periodically sends its GIS location to the command UAV, which uses that data to steer beams precisely at the mission UAV.

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Efficient beamforming technique for radar-communication combined systems in drones. The technique allows drones with radar and communication capabilities to operate effectively in close proximity. It involves optimizing the radar and communication beam patterns using a common design based on signal-to-noise ratio (SNR) and transmit power. This enables simultaneous radar and communication using the same beams from the drone's beamforming device.

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Multi-front switching beamforming method for active antenna arrays covering the entire airspace. It compensates for phase differences between antenna arrays when switching between fronts to maintain phase consistency for beamforming. This avoids phase jitter issues during multi-front array switching that can lead to phase inconsistency. The phase compensation algorithm is applied to the steering vectors of each front to adjust them based on the relative phase differences between the antenna arrays.

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Unmanned aerial vehicle (UAV) measurement and control method using intelligent antennas to improve UAV communication quality, range, and reliability. The method involves using an intelligent antenna array on the UAV that can adaptively steer beams in real-time based on signal analysis. This allows the UAV to dynamically align the antenna beams with ground stations and base stations to improve link quality, reduce interference, and mitigate multipath issues. The method aims to provide stable, high-quality UAV communication links using intelligent antennas.

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