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SPM Articles

Spatial Frequencies and Degrees of Freedom: Their roles in near-field communications

As wireless technology begins to utilize physically larger arrays and/or higher frequencies, the transmitter and receiver will reside in each other’s radiative near field. This fact gives rise to unusual propagation phenomena, such as spherical wavefronts and beam focusing, creating the impression that new spatial dimensions—called degrees of freedom (DOF)—can be exploited in the near field.

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Near-Field Signal Processing: Unleashing the power of proximity

After nearly a century of specialized applications in optics, remote sensing, and acoustics, the near-field (NF) electromagnetic (EM) propagation zone is experiencing a resurgence in research interest. This renewed attention is fueled by the emergence of promising applications in various fields, such as wireless communications, holography, medical imaging, and quantum-inspired systems. 

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Special Issue on Near-Field Signal Processing: Communications, Sensing, and Imaging

Multichannel signal processing technologies are moving toward the deployment of small and densely packed sensors yielding extremely large aperture arrays (ELAAs) in order to provide higher angular resolution and beamforming gain. In particular, technologies are moving beyond the fifth-generation (5G) networks, wherein the adoption of ELAAs or surfaces and the exploitation of higher-frequency bands, e.g., terahertz 

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Neural Kalman Filters for Acoustic Echo Cancellation: Comparison of deep neural network-based extensions

Multichannel acoustic signal processing is a well-established and powerful tool to exploit the spatial diversity between a target signal and nontarget or noise sources for signal enhancement. However, the textbook solutions for optimal data-dependent spatial filtering rest on the knowledge of second-order statistical moments of the signals, which have traditionally been difficult to acquire.

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Microphone Array Signal Processing and Deep Learning for Speech Enhancement: Combining model-based and data-driven approaches to parameter estimation and filtering

Multichannel acoustic signal processing is a well-established and powerful tool to exploit the spatial diversity between a target signal and nontarget or noise sources for signal enhancement. However, the textbook solutions for optimal data-dependent spatial filtering rest on the knowledge of second-order statistical moments of the signals, which have traditionally been difficult to acquire.

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Sensing in Bistatic ISAC Systems With Clock Asynchronism: A signal processing perspective

Integrated Sensing And Communication (ISAC) has been identified as a pillar usage scenario for the impending 6G era. Bi-static sensing, a major type of sensing in ISAC, is promising to expedite ISAC in the near future, as it requires minimal changes to the existing network infrastructure. However, a critical challenge for bi-static sensing is clock asynchronism due to the use of different clocks at far-separated transmitters and receivers.

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Multicarrier ISAC: Advances in waveform design, signal processing, and learning under nonidealities

This paper addresses the topic of integrated sensing and communications (ISAC) in 5G and emerging 6G wireless networks. ISAC systems operate within shared, congested or even contested spectrum, aiming to deliver high performance in both wireless communications and radio frequency (RF) sensing. The expected benefits include more efficient utilization of spectrum, power, hardware (HW) and antenna resources.

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In-Band Full-Duplex Multiple-Input Multiple-Output Systems for Simultaneous Communications and Sensing: Challenges, methods, and future perspectives

In-band full-duplex (FD) multiple-input, multiple-output (MIMO) systems offer a significant opportunity for integrated sensing and communications (ISAC) due to their capability to realize simultaneous signal transmissions and receptions. This feature has been recently exploited to devise spectrum-efficient simultaneous information transmission and monostatic sensing operations, a line of research typically referred to as MIMO FD-ISAC.

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