Over twelve years ago,
WRC-97 introduced the definition of adaptive systems
in the Radio Regulations. Such systems were limited to the medium and high
frequency bands where propagation conditions vary significantly. Adaptive
systems were capable of modifying their parameters, including frequency and
power, in order to improve the quality of reception.
WRC-97 adopted Resolution 729 on the “Use of frequency adaptive systems in
the MF and HF bands”, which called for further studies on the issue with their
results to be reported to a future WRC. The resolution introduced regulatory
elements for adaptive systems, prohibiting their operation in the bands used by
safety services as well as by the radio astronomy, radiodetermination, amateur
and broadcasting services.
Further technological developments enlarged the capabilities of adaptive
systems. In this respect, an important role is played by software, which makes
it possible to analyse the radio environment and adjust system characteristics
to specific operational situations. Such a combination of radio equipment and
software offers new solutions for resolving the problem of frequency congestion
and improves the overall efficiency of spectrum use. Following these
technological advances, the two new concepts of software-defined radio (SDR) and
cognitive radio systems (CRS) were created.
Need for regulatory solutions
common concern within ITU-R was the protection of existing services from
potential interference from SDR and CRS systems. Consequently, WRC-07 adopted
agenda item 1.19
consider regulatory measures for the introduction of SDR and CRS.
In this regard, WRC-07 adopted
(WRC-07), inviting ITU-R to study the need for regulatory measures
related to the application of SDR and CRS. The resolution also resolved that
WRC-12 should consider the results of the studies and take the appropriate
actions. The task of conducting the necessary studies was assigned to
Results of ITU-R studies
By April 2010, Working Party 1B had reached common views on many related
issues. It was recognized that SDR and CRS are technologies and not
radiocommunication services. These technologies can be used in any
SDR and CRS are to comply with the provisions of the
Radio Regulations applicable to the service under which they operate.
In addition, Working Party 1B established the definitions for
these two technologies, which are given (over) in a simplified form.
was also emphasized that the introduction of SDR and CRS should not impose
additional constraints on other services sharing the same frequency band.
• Software-defined radio (SDR): radio equipment
employing a technology, which allows the setting or changing of technical
parameters, including frequency range, modulation type and power, depending on
the electromagnetic environment.
• Cognitive radio systems (CRS): a radio system employing a technology,
which makes it possible to obtain knowledge of its operational environment,
policies and internal state, to dynamically adjust its parameters and protocols
according to the knowledge obtained and to learn from the results obtained.
Methods to satisfy WRC-12 agenda item 1.19
The analysis of the results of the studies and methods proposed for WRC-12
agenda item 1.19 have been reflected in draft text of the
Meeting (CPM) and could be found in
Annex 7 to Document 1B/210.
With respect to SDR, it was concluded that no changes to the Radio Regulations
are necessary in order to introduce this technology. The current regulations can
encompass the implementation of SDR. Technical and operational considerations
related to SDR will be addressed in ITU-R Recommendations and Reports.
The situation regarding CRS is different. Three methods are proposed for
resolving agenda item 1.19. The first method consists in making no change to the
Radio Regulations and developing relevant ITU-R Recommendations and Reports.
Under the second method it is proposed to develop a WRC Resolution calling for
studies on CRS with special emphasis on sharing issues. Based on those studies,
ITU-R Recommendations and Reports would be developed.
The third method proposes the development of a WRC Resolution calling for
studies on CRS. The resolution would also exclude the operation of CRS in some
bands, for example those used by space services (space-to-Earth) or radio
astronomy, until the studies have been completed. In addition, the resolution
would oblige CRS to avoid operations in the bands used by safety services. This
third method reflects the concerns expressed by some ITU-R working parties that
CRS, which dynamically search for a free channel, may not be capable of
detecting low-power signals of other services or sporadic operation of some
radio links and cause harmful interference.
Despite divergent views on CRS, agenda item 1.19 does not appear to
represent a difficult issue for WRC-12. Some interesting and lively discussions
are nevertheless expected at CPM-11-2 and at the Conference itself, which will
open a regulatory 'door' for the introduction of two of the most state-of-the-art
technologies: software defined radio and cognitive radio systems.
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