A study of coherent gain degradation due to node vibrations in open loop coherent distributed arrays

Chatterjee, Pratik; Nanzer, Jeffrey A.

doi:10.1109/usnc-ursi.2017.8074924

Cited by 12 publications

(4 citation statements)

References 3 publications

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“…In practice, however, there are several major factors that can lead to severe degradation of the incoherent radiation pattern. These include the relative frequency offset and phase error of the oscillators on each array element, the relative timing offset, the drone positional estimation errors, the channel delays from each node to the destination, and element's tilt angle [15], [33]. To account for the practical application requirements, a uniform distributed random noise ∆ with a maximum amplitude of ∆ max is added to the beamformer weights for each array element by…”

Section: Element Phase Errormentioning

confidence: 99%

Unmanned Aerial Vehicles Swarm-Based Distributed Phased Arrays for Grating Lobe Mitigation and Collision Avoidance

Diao

2022

IEEE Open J. Antennas Propag.

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Distributed phased arrays based on unmanned aerial vehicle (UAV) swarm with small antenna elements on each micro-UAV are expected to achieve much better performance than the traditional phased arrays due to a large amount of swarm mobile individuals and deployment flexibility. To avoid the possible collisions of the flying UAVs, a large separation distance between UAVs is required, but grating lobes can appear when the array element spacing is larger than one-half wavelength. To solve this issue, array antennas with aperiodic element placement are normally used to mitigate the grating lobes, while suffering from a high collision risk for UAVs due to the reduced array element separation in the aperiodic array. This paper proposes a novel 3-D aperiodic array design by adding an additional degree of freedom in the optimization of array configuration. The sidelobe levels can be largely reduced from the planar periodic arrays. In addition, the collision risk for UAVs represented by the minimum separation distance between array elements can be largely decreased from the planar aperiodic arrays. This work provides a feasible strategy for the design and optimization of the UAV swarm-based phased arrays for practical applications.

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Section: Element Phase Errormentioning

confidence: 99%

Unmanned Aerial Vehicles Swarm-Based Distributed Phased Arrays for Grating Lobe Mitigation and Collision Avoidance

Diao

2022

IEEE Open J. Antennas Propag.

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“…[2]) or remote sensing from an array of UAVs (e.g. [26]- [29]); operating at a frequency of 100 MHz, the domain represents a 30m×30m space, within which it is certainly feasible to locate nodes within half of a wavelength (1.5m). Figs.…”

Section: Syntonization (Frequency Alignment) In Coherent Distributed ...mentioning

confidence: 99%

Decentralized Frequency Alignment for Collaborative Beamforming in Distributed Phased Arrays

Ouassal¹,

Yan²,

Nanzer³

2019

Preprint

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A new approach to distributed syntonization (frequency alignment) for the coordination of nodes in open loop coherent distributed antenna arrays to enable distributed beamforming is presented. This approach makes use of the concept of consensus optimization among nodes without requiring a centralized control. Decentralized frequency consensus can be achieved through iterative frequency exchange among nodes. We derive a model of the signal received from a coherent distributed array and analyze the effects on beamforming of phase errors induced by oscillator frequency drift. We introduce and discuss the average consensus protocol for frequency transfer in undirected networks where each node transmits and receives frequency information from other nodes. We analyze the following cases: 1) undirected networks with a static topology; 2) undirected networks with dynamic topology, where connections between nodes are made and lost dynamically; and 3) undirected networks with oscillator frequency drift. We show that all the nodes in a given network achieve average consensus and the number of iterations needed to achieve consensus can be minimized for a given cluster of nodes. Numerical simulations demonstrate that the consensus algorithm enables tolerable errors to obtain high coherent gain of greater that 90% of the ideal gain in an errorfree distributed phased array.

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“…• In distributed phased arrays, the electrical states of the nodes are updated with smaller update intervals, usually on the order of milli-second (ms), to avoid large oscillator drifts [26] and to correct the residual phase errors due to the platform vibrations [27]. However, it was shown in [11] that at such update intervals, the residual phase error of a consensus algorithm is usually higher when no filtering is used at the nodes, which deters an accurate coherent operation.…”

Section: Introductionmentioning

confidence: 99%

Online Expectation-Maximization Based Frequency and Phase Consensus in Distributed Phased Arrays

Rashid¹,

Nanzer²

2022

Preprint

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Distributed phased arrays are comprised of separate, smaller antenna systems that coordinate with each other to support coherent beamforming towards a destination. However, due to the frequency drift and phase jitter of the oscillators on each node, as well as the frequency and phase estimation errors induced at the nodes in the process of synchronization, there exists a decoherence that degrades the beamforming process. To this end, a decentralized frequency and phase consensus (DFPC) algorithm was proposed in prior work for undirected networks in which the nodes locally share their frequencies and phases with their neighboring nodes to reach a synchronized state. Kalman filtering (KF) was also integrated with DFPC, and the resulting KF-DFPC showed significant reduction in the total residual phase error upon convergence. One limitation of DFPC-based algorithms is that, due to relying on the average consensus protocol which requires undirected networks, they do not converge for directed networks. Since directed networks can be more easily implemented in practice, we propose in this paper a push-sum based frequency and phase consensus (P s FPC) algorithm which converges for such networks. The residual phase error of P s FPC upon convergence is theoretically derived in this work.Kalman filtering is also integrated with P s FPC and the resulting KF-P s FPC algorithm shows significant Manuscript received 2022.

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A study of coherent gain degradation due to node vibrations in open loop coherent distributed arrays

Cited by 12 publications

References 3 publications

Unmanned Aerial Vehicles Swarm-Based Distributed Phased Arrays for Grating Lobe Mitigation and Collision Avoidance

Unmanned Aerial Vehicles Swarm-Based Distributed Phased Arrays for Grating Lobe Mitigation and Collision Avoidance

Decentralized Frequency Alignment for Collaborative Beamforming in Distributed Phased Arrays

Online Expectation-Maximization Based Frequency and Phase Consensus in Distributed Phased Arrays

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