arXiv subjects

Kenan Turbic

Publications and source records attributed to Kenan Turbic.

7 recordsLinked to original sources

arXiv2026

Waveform Design for Simultaneous MIMO Radar Sensing and Multi-User Communication

This paper proposes a novel two-stage joint waveform design framework for multi-antenna Integrated Sensing and Communication (ISAC) systems that simultaneously enable Multiple-Input Multiple-Output (MIMO) radar sensing and Multi-User MIMO communication. First, a transmit waveform covariance matrix is designed by solving a convex matrix nearness problem for beampattern synthesis that simultaneously maximizes transmit power in desired directions and minimizes cross-directional correlations, while accommodating independent antenna power constraints and supporting interference suppression through radiation null steering. Second, a waveform conforming to the designed covariance is synthesized while additionally enforcing inter-user interference suppression via the zero-forcing approach and imposing practical implementation constraints, notably limiting the peak-to-average-power-ratio on the individual antenna elements. Simulation results demonstrate that the approach significantly enhances ISAC waveform design flexibility, performance, and computational efficiency compared to the alternative methods in the literature.

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arXiv2026

ISAC Beamforming Design Based on a Matrix Nearness Formulation With Improved Efficiency

We propose an integrated sensing and communication (ISAC) beamforming method that performs joint multiple-input multiple-output (MIMO) radar sensing and multi-user MIMO communication. Our approach builds on a matrix nearness formulation of the MIMO radar problem and utilizes our recently proposed efficient solver, where the computational complexity is dominated by an eigenvalue decomposition (EVD) evaluation at each iteration. We extend this formulation to an ISAC scenario by incorporating minimum signal-to-noise ratio constraints as communication design criteria, only requiring statistical channel state information knowledge at base station. Furthermore, we propose a method to avoid the burdensome EVD evaluations in certain iterations, reducing the computation time by up to six times in a massive MIMO setting.

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arXiv2026

Transmit Beamformer Design for Beampattern Synthesis in Phased-Array Radar Systems

This paper presents a phased-array transmit beamformer design for beampattern matching and interference suppression. We propose an optimization framework jointly addressing these two objectives. The resulting non-convex problem is solved via alternating minimization, where each subproblem admits a closed-form solution, one of which recovers the classical maximum-gain and null-steering phased-array beamformers. To design an algorithm ensuring theoretical convergence guarantees, the beamformer design is then reformulated as a non-convex set feasibility problem, closely related to the original formulation. This problem is addressed using a provably convergent projected gradient descent method and further enhanced with acceleration techniques that substantially improve empirical convergence. Extensive simulations validate the excellent performance and computational efficiency of the proposed method.

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arXiv2025

On Level Crossings and Fade Durations in von Mises-Fisher Scattering Channels

This paper investigates the second-order statistics of multipath fading channels with von Mises-Fisher (vMF) distributed scatters. Simple closed-form expressions for the mean Doppler shift and Doppler spread are derived as the key spectral moments that capture the impact of mobility and scattering characteristics on level crossings and fade durations. These expressions are then used to analyze the influence of vMF parameters on the Level-Crossing Rate (LCR) and Average Fade Duration (AFD). The results show that isotropic scattering yields the highest LCR and the lowest AFD, while fading dynamics reduce with the decreasing angular spread of scatterers. Moreover, mobile antenna motion parallel to the mean scattering direction results in a lower LCR than the perpendicular motion, with the difference between the two cases increasing with the higher concentration of scatterers.

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arXiv2025

Doppler Power Spectrum in Channels with von Mises-Fisher Distribution of Scatterers

This paper presents an analytical analysis of the Doppler spectrum in von Mises-Fisher (vMF) scattering channels. A simple closed-form expression for the Doppler spectrum is derived and used to investigate the impact of the vMF scattering parameters, i.e., the mean direction and the degree of concentration of scatterers. The spectrum is observed to exhibit exponential behavior for mobile antenna motion parallel to the mean direction of scatterers, while conforming to a Gaussian-like shape for the perpendicular motion. The validity of the obtained results is verified by comparison against the results of Monte Carlo simulations, where an exact match is observed.

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arXiv2024

Correlation Properties in Channels with von Mises-Fisher Distribution of Scatterers

This letter presents simple analytical expressions for the spatial and temporal correlation functions in channels with von Mises-Fisher (vMF) scattering. In contrast to previous results, the expressions presented here are exact and based only on elementary functions, clearly revealing the impact of the underlying parameters. The derived results are validated by a comparison against numerical integration result, where an exact match is observed. To demonstrate their utility, the presented results are used to analyze spatial correlation across different antenna array geometries and to investigate temporal correlation of a fluctuating radar signal from a moving target.

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arXiv2021

From Nano-Communications to Body Area Networks: A Perspective on Truly Personal Communications

This article presents an overview of future truly personal communications, ranging from networking inside the human body to the exchange of data with external wireless devices in the surrounding environment. At the nano- and micro-scales, communications can be realized with the aid of molecular mechanisms, Forster resonance energy transfer phenomenon, electromagnetic or ultrasound waves. At a larger scale, in the domain of Body Area Networks, a wide range of communication mechanisms is available, including smart-textiles, inductive- and body-couplings, ultrasounds, optical and wireless radio transmissions, a number of mature technologies existing already. The main goal of this article is to identify the potential mechanisms that can be exploited to provide interfaces in between nano- and micro-scale systems and Body Area Networks. These interfaces have to bridge the existing gap between the two worlds, in order to allow for truly personal communication systems to become a reality. The extraordinary applications of such systems are also discussed, as they are strong drivers of the research in this area.

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