The demand for wireless capacity, coverage, reliability and multiple access in a crowded environment requires the advancement of traditional networking infrastructures to meet the needs of future deployments and services. The evolution considers higher frequencies with new spectrum including the millimeter-wave and the optical range of the spectrum. However, the vast majority of research efforts so far have been dedicated to the performance analysis and optimization of standalone deployments of radio, millimeter and optical wireless communication networks. Toward providing high quality of service and experience over a diverse spectrum, there is a rapidly growing interest in coexisting radio and optical wireless technologies. The development of a cognitive radio-optical paradigm can significantly enhance data rates, communication range, reliability and operation under interference and congestion, where the radio-optical environment is continuously monitored and performance of individual links is continuously optimized. In such cognitive radio-optical deployments and time varying scenarios, the system can detect available channels, determine the quality of individual channels and adaptively change parameters including waveform, operating frequency, protocols, and networking. Thus, the performance can be optimized according to a combination of user requirements, operational limitations, and regulatory constraints.

According to the distance between the transmitter and receiver, such radio-optical systems can be classified into long-range systems for outdoor deployments and short-range systems for both outdoor and indoor environments. For the design of such systems, indoor and outdoor propagation environments are inherently different from each other and pose unique challenges which need to be carefully taken into account. The distinct features of cognitive radio-optical systems can add to future wireless standards, with the possibility of a future terminal having a number of wireless interfaces. In particular, optical air interfaces can be incorporated to terminals in addition to the radio-based ones. The 5G networks and beyond will be highly heterogeneous, offering a good opportunity for the wider adoption of such networks. However, considerable work is still needed to fully exploit the clear advantages of cognitive radio-optical deployments, as well as developing low-cost subsystems and components to implement them. Hybrid radio-optical systems poses several challenges that have to be overcome before widespread deployment of such networks. Consequently, the field of cognitive radio-optical wireless deployments promises enormous opportunities for basic and applied research and development.

The proposed special issue will capture the current state of the art for research and new efficient schemes, techniques and protocols to address fundamental and practical challenges in enabling cognitive radio-optical networks. Coexisting Radio and Optical Wireless Deployments, or CROWD networks, are of high interest as we look for new ways to accommodate the demand that will be placed on next generation wireless networks and beyond. This special issue will bring together leading researchers and developers from both industry and academia to present state-of-the-art research and current trends related to CROWD networks and associated cognitive operations. Prospective authors are invited to submit original manuscripts on topics including, but not limited to:

• RF-FSO and RF-VLC systems
• Modulation and coding techniques
• MIMO transmission
• Load balancing
• Backhauls
• Mixed relay systems
• Multiple-access techniques
• Resource allocation and aggregation methods
• Coverage, mobility and reliability
• Interference management
• Network layout and architecture
• Cross-layer optimization
• Quality of service and experience
• Devices and hardware integration
• Information theory
• Experimental demonstrations, tests, and performance characterizations

Submission Guidelines

Prospective authors should submit their manuscripts following the IEEE TCCN Guidelines. Authors should submit a PDF version of their complete manuscript to Manuscript Central according to the following schedule:

Important Dates

Manuscript Due: 30 January 2019
First Reviews Complete: 15 February 2019
Revision Due: 31 March 2019
Final Review Decision: 15 May 2019
Final Manuscript Due: 15 June 2019
Publication: September 2019

Guest Editors

Prof. Mohamed-Slim Alouini
King Abdullah University of Science and Technology (KAUST), KSA

Prof. Hany Elgala
University at Albany, State University of New York (SUNY), USA

Prof. Harald Haas
The University of Edinburgh, Scotland

Prof. Michael, Rahaim
University of Massachusetts Boston, USA

Prof. Hina Tabassum
York University, Canada

Prof. Takashi Watanabe
Osaka University, Japan