Dear Colleagues,

Millimeter-wave (mmWave) communication is gaining ever-increasing attention as a promising technology for satisfying future demand for multi-gigabit-per-second mobile, imaging, and multimedia applications. The idea behind mmWave communication is to exploit the huge and unused bandwidth available up to 300 GHz. However, in this spectrum portion, signals are highly susceptible to blockages from large-size structures in the radio paths, e.g., buildings, and they are severely attenuated by the presence of small-size objects, e.g., human bodies and foliage. Such problems become more pronounced in dense urban environments due to the highly dynamic nature of the radio environment. A possible approach to circumventing the unreliability of high-frequency channels is artificially creating additional routes between the source and destination. Along this line, a viable strategy is based on the deployment of relay sensors that capitalize on the concept of distributed cooperative diversity.

Relaying can be performed by infrastructure relays, which provide enhanced coverage and capacity at cell edges, with the disadvantages, however, of a reduced network energy efficiency, an increased network complexity, and the requirement for a larger capital expenditure for deployment. An attractive alternative may be represented by opportunistic relays, connecting the source and destination through a device-to-device (D2D) link, i.e., D2D relays. This solution is interesting because it does not require dramatic changes to network topology or infrastructure.

From a different perspective, in order to maintain low power consumption and radio wave emission, a viable alternative to relaying is using reconfigurable intelligent surfaces (RIS), i.e., planar or spherical surfaces able to shape radio waves in a controlled manner, providing energy-focusing, data-transmission, and terminal-positioning capabilities.

This Special Issue is seeking high-quality submissions that highlight emerging applications and address recent breakthroughs in the design and implementation of advanced cooperative approaches in the context of mmWave communication.

The topics of interest include, but are not limited to, the following:

- Cooperative communications in 5G networks;

- Device-to-device (D2D) relaying;

- Cooperative MIMO;

- Cooperative communications in optical wireless communications;

- Cooperative communications in acoustic wireless communications;

- Backscattering-based cooperative communications;

- Cooperative communications based on reconfigurable intelligent surfaces;

- Machine-learning algorithms for cooperative communications;

- Physical-layer security for cooperative networks;

- Simulation tools, benchmarks and testbeds for cooperative systems.

Dr. Donatella Darsena
Prof. Dr. Francesco Verde
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Sensors is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.