One of the main issues in the developing of 5G communications is the limited amount of an available spectrum. The industry is trying to find solutions to ease this problem.
Among multiple methods to cope with scarcity of available spectrum, two directions seem very promising. They are:
- Intensification of utilization already occupied spectrum windows
- Identification and utilization of vacant (or almost vacant) spectrum windows.
This report addresses only the second approach; and particular it concentrates on the following technologies:
- Optical Wireless Communications (OWC)a) VLC - Visible Light Communicationb) FSF - Free Space Fiber
- CR/SDR – Cognitive/Software Defined Radio
- TV White Space Communications (TVWSC)
- E-band Radio.
OWC includes VLC and FSF. Both these technologies utilize - free (or more precisely, very lightly occupied) frequency spectrum.
OWC is widely recognized as superior to radio frequency transmission for several use cases. Visible and invisible optical wireless links solve first/last mile connectivity problems, serve for signal distribution inside of premises, and provide secure, jam-free communication. OWC is license-free and can potentially deliver high-speed data rates in the order of tens Gb/s. Its advantages have fostered significant research efforts aimed at utilizing optical wireless communication, e.g. VLC, for high-speed, secure, indoor/outdoor communication under the IEEE 802.15.7 and other standards; as well as FSF for indoor and outdoor communications.
Both technologies are using free space as a communications medium; though they utilize such a medium in different ways and have both similar and specific communications channel properties.
Cognitive/Software Defined Radio allows the analysis of spectrum occupancy in a particular area and particular time. Based on such an analysis, cognitive engine can adjust frequency bands on SDR (together with other parameters) in such a way that transmission will fill up unoccupied windows (if they exist).
TVWSC is an example of one of the first commercial applications of CR/SDR.
E-band radios attract attention of the 5G community due to their features, such as “light” licensing, lightly occupied spectrum and the range of several kilometers together with multi-gigabit per second speed of transmission.
The report surveys the industries, addresses technical and marketing specifics of all mentioned technologies and concentrates on their standardization.
Attachments present the survey of resent patents related to TVWS, IEEE802.22 and IEEE 802.11af, and IEEE802.15.7.
The report was developed for a wide audience of engineers and managers that are working with advanced communications technologies.