WRC-12 Agenda Item 1.19: Software-Defined Radio (SDR) and Cognitive Radio Systems (CRS) - (by Nikolai Vassiliev, Head, Fixed and Mobile Services Division, BR)

Background

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

By the WRC-07, a common concern within ITU-R was the protection of existing services from potential interference from SDR and CRS systems. Consequently, WRC-07 adopted new agenda item 1.19 requiring WRC-12 to consider regulatory measures for the introduction of SDR and CRS.

In this regard, WRC-07 adopted Resolution 956 (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 ITU-R Working Party 1B.

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 radiocommunication service.

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.

It 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 Conference Preparatory 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.

Conclusions

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.
 

BR promotion contact