The spectrum policy reform paving the way to cognitive radio enabled spectrum sharing

Telecommunications Policy 37 (2013) 87–95

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Telecommunications Policy URL: www.elsevier.com/locate/telpol

The spectrum policy reform paving the way to cognitive radio enabled spectrum sharing Annalisa Durantini n, Mauro Martino Autorita per le Garanzie nelle Comunicazioni, Via Isonzo 21/b, Rome 00198, Italy

a r t i c l e i n f o

abstract

Available online 9 February 2013

The increasing amount of data and video traffic carried by mobile networks has recently risen the demand for enhanced network capacity, more efficient use and more effective management of spectrum. Cognitive radio technologies candidate to respond to these urgent needs by allowing a near simultaneous band sharing. The regulation plays a crucial role in promoting the adoption of these technologies, in order to overcome the traditional paradigms of authorizations for exclusive spectrum usage. The article outlines spectrum management regimes where the implementation of frequency sharing technologies, including cognitive technologies, is foreseeable and brings them back to a comprehensive taxonomy of dynamic spectrum access and sharing models, in the effort to reconcile partially diverging approaches and nomenclatures suggested in literature. Theoretic analysis is supported by a number of illustrations and practical experiments with shared spectrum usage. Based on suggested taxonomy, the research aims at showing the evolutionary path toward the introduction and spreading of cognitive and other spectrum sharing technologies, pointing out relevant trends and instruments made available by the reform of EU Telecom Package, as well as at outlining the status of regulation, policy and standardization in Europe. & 2013 Elsevier Ltd. All rights reserved.

Keywords: Cognitive radio Spectrum Sharing Access Regulation Standardization

1. Introduction In the latest years, demand for wireless networks capacity has considerably grown due to the increasing amount of transmitted data traffic. According to a recent forecast (Cisco, 2011), global mobile data traffic will increase 26-fold between 2010 and 2015. It will grow at a compound annual growth rate (CAGR) of 92 percent, reaching 6.3 exabytes per month by 2015. In particular, two-thirds of the world’s mobile data traffic will be video by 2015. The amount of mobile machine-to-machine (M2M) data traffic in 2015 (295 petabytes per month) will be approximately equal to the total amount of global mobile data traffic in 2010 (242 petabytes per month). On the other hand, existing wireless communication and broadcasting systems stably use large parts of the radio spectrum and, in particular, the ITU UHF band (300–3000 MHz), that is the most valuable for technological and propagation reasons. However, for part of the time and of the geographical areas, these systems inefficiently use the allocated spectrum, which is proved by many experimental studies in literature, as well as by some demonstrative measurement campaigns (D’Itri & McHenry, 2008; Erpek, Steadman, & Jones, 2007; FCC-02-135, 2002; Islam et al., 2008; Valenta, Fedra, Marsalek, Baudoin, & Villegas, 2009). As a consequence of both effects, it is largely believed that the available spectrum is not sufficient to meet the future needs of wireless networks and it is also agreed that spectrum management should considerably evolve1. The policy of ‘‘Fixed Spectrum Allocation’’ (FSA), with its origins in the regulatory practices consolidated throughout the

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Corresponding author. Tel.: þ39 0669644162; fax: þ 39 0669644368. E-mail address: [email protected] (A. Durantini). 1 Both principles are well enshrined in the recently approved EU Radio Spectrum Policy Program (RSPP), Decision of the European Parliament and Council 243/2012/EU of 14 March 2012. 0308-5961/$ - see front matter & 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.telpol.2012.10.003

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twentieth century, should give ground to innovative forms of dynamic use, cumulatively referred to as ‘‘Dynamic Spectrum Access’’ (DSA), which could enable the sharing of the scarce resource and hence its more efficient use. Among the various technological enablers theoretically available to create a dynamic and flexible use of spectrum, today cognitive radio (CR) technology, first presented by J. Mitola III in its seminal paper (Mitola & Maguire, 1999) in 1999, candidates as one of the most promising solutions. A cognitive radio transceiver operates according to a cognitive Observe-Orient-Decide-Act (OODA) loop based on stimuli coming from the environment, continually observed and interpreted. In order to dynamically manage the spectrum, CR main functions are: continuous monitoring and detection of unused spectrum portions (spectrum sensing); dynamic use of the best free part of spectrum (spectrum management); timely release of spectrum when a primary user starts to be active (spectrum mobility). CR as well as other spectrum sharing technologies can be foreseen in various frequency bands, where different spectrum use authorization schemes apply and heterogeneous access arrangements are in force. Specific regulation is required and the role of the spectrum management differs according to the concerned model. On this topic, debate in literature appears so far to lack clarity. There are no complete taxonomies for authorization models and spectrum access paradigms, pointing out where frequency sharing is allowed and CR devices and networks are envisaged to operate, with reference both to traditional models and innovative schemes. Interesting hints for discussion have recently been suggested by Barrie, Delaere, Anker, and Ballon (2012), that focuses on the identification of economic scenarios for CR, based on parameters such as the ownership, the exclusivity and the tradability of licenses. These criteria have been also taken into account in this paper, which intends to contribute to the debate providing an overview of authorization regimes and access policy options that can be facilitated by means of spectrum sharing technologies, in particular CR technologies. The paper also discusses on how spectrum policy is evolving both at European and at a national level in such a way to support and promote the shared use of the spectral resource and to achieve allocative and technical efficiency in spectrum management. The rest of the paper is organized as follows. In Section 2 the main dynamic spectrum access models currently in use or presented in literature are reviewed and the spectrum sharing mechanisms in particular based on CR technologies are brought forward and reconciled to a comprehensive taxonomy. Hence, within the scope of pointing out measures that can be conducive to the actual implementation of spectrum sharing mechanisms, relevant trends in the reform of EU Telecom Package are set out in Section 3, while the current status of European regulation, policy and standardization is outlined in Section 4. A deeper insight is provided in Section 5 for regulatory activity in Italy, as an example of the role of regulation in defining authorization models for spectrum usage rights suitable to foster spectrum sharing. Finally, in Section 6 some conclusions are drawn.

2. A taxonomy of dynamic spectrum access techniques In the light of recent technological progresses that are increasingly reducing the risks of harmful interference, and taking into account the need to fully exploit the social and economic value of spectrum, regulation should aim at facilitating the access to radiofrequency resources by market players. Innovative types of authorizations could be introduced that allow for a shared use of spectrum and provide means for coexistence between existing and new services, so easing innovation. From this perspective, it is worthwhile considering scenarios currently being examined for spectrum sharing by standardization bodies both at European and international level, and discussing on authorization models, regulatory measures and interventions for promoting cognitive radio and other dynamic spectrum sharing technologies. To this aim a comprehensive understanding is needed of all cases where CR fits within the range of options available to be implemented, in scenarios where a certain spectrum access approach and authorization scheme are in force. Hence, it is necessary to define and make reference to a taxonomy of modes for the general concept of ‘‘Dynamic Spectrum Access’’. A classification of DSA techniques2 was provided in 2007 by Zhao and Swami (2007), which categorizes relevant approaches under three regulatory models: ‘‘Dynamic Exclusive Use Model’’, ‘‘Spectrum Commons Model’’ and ‘‘Hierarchical Access Model’’, based on the licensing regime in force. However, a number of works have been presented in literature introducing partially different nomenclature (Faulhaber & Farber, 2003; Freyens, 2009; Lehr & Crowcroft, 2005; Pogorel, 2007; RSPG08-244, 2008). Based on Zhao and Swami taxonomy we suggest some changes to make the model reflective of new access arrangements enabled by progress in technology and regulation. Hence, in order to identify relevant regulatory models benefiting from cognitive radio and other spectrum sharing technologies, we introduce a modified taxonomy, as shown in Fig. 1 (spectrum usage regimes where CR technologies can be profitably introduced are reported in shadowed boxes). Suggested taxonomy, graphically represented by a tree structure, is framed around several policy dimensions: at the first hierarchical level of the tree, the authorization models for spectrum usage currently applied by the regulatory authorities or still under consideration at the legislative level are pointed out and grouped according to the ownership of the spectrum 2 The expression ‘‘dynamic spectrum access’’ is used as the opposite of a static spectrum management policy, with the broad connotation of encompassing various approaches to spectrum reform, presented at the first IEEE symposium on new Frontiers in dynamic spectrum access networks (DySPAN), held in November 2005.

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Fig. 1. A taxonomy of Dynamic Spectrum Access techniques.

rights of use and the degree of exclusivity of the frequency band assignments; at the second level of the hierarchy, the spectrum access approaches are listed. Finally, technology used to share the spectrum is specified at the third level of the tree. As suggested in Zhao and Swami (2007), a ‘‘Dynamic Exclusive Use Model (DEUM)’’ (node A in Fig. 1) provides that spectrum bands are allocated to certain services and assigned to licensed users, although a dynamic and flexible access by third parties is guaranteed to a certain extent by administrative and market-based spectrum access methods, in order to improve spectrum efficiency. Two approaches have been identified under this model: ‘‘Spectrum Property Rights’’ (Coase, 1959; Hatfield & Weiser, 2005) and ‘‘Dynamic Spectrum Allocation’’ (Xu et al., 2000). The spectrum property rights regime (node A.1) allows licensees to trade and lease spectrum and to freely select technology. Spectrum efficiency is improved by introducing flexibility in spectrum assignment and technology neutrality. Nevertheless this method, defined as above, only achieves long-term access dynamics in making spectrum access available, since it is unable to address simultaneous spectrum sharing among multiple users. The other approach, dynamic spectrum allocation (node A.2), allocates frequencies to services for exclusive use limited to certain geographical areas and time periods, and it improves spectrum efficiency by allowing spectrum sharing over space and time among heterogeneous radio-access networks (such as cellular and broadcast networks). However, this model cannot gain from instantaneous spectrum opportunities since it exploits temporally and spatially averaged information on the availability of spectrum unused by primary users, regardless of the stochastic instantaneous and local status of the primary users activity pattern. In compliance with this model, coexisting radio services share spectrum based on a pre-scheduled, time and space-dependent, allocation strategy, according to which the amount of spectrum allocated to each sharing system can vary over region and time-of-day. Increased efficiency of spectrum usage can be achieved by means of cognitive radio and other spectrum sharing technologies that exploit information about the statistical bursty nature of wireless traffic, in frequency bands covered by a ‘‘Collective Use of Spectrum’’ (CUS) model (node B in Fig. 1) as well as in spectrum bands where property rights are assigned with easements3, according to an ‘‘Eased Property Rights’’ (EPR) regime (node C in Fig. 1). A continuity can be highlighted, however, among the latter approaches, targeting a more and more dynamic access to spectrum, and the former ones (afferent to the DEUM model), as they pursue the same objectives, though meeting the target to a different extent. According to the CUS model (Lehr & Crowcroft, 2005; RSPG08-244, 2008), an undetermined number of independent users and/or devices is allowed to access spectrum in the same bands, at the same time and in a particular geographic area under a certain pre-determined set of conditions aimed to avoid harmful interference (node B). The model encompasses various spectrum use authorization modes, entailing different regulation, such as open access and common property models. Specifically CUS includes license-exempt use, light licensing and private commons. While according to the first two approaches the regulator is responsible for defining conditions to access the band, in the latter case the licensee entity is assigned this task. Two schemes can be identified for allowing devices to access and share spectrum under CUS regime, that are ‘‘Dedicated Unlicensed’’ (node B.1) and ‘‘Hierarchical Access Model (HAM)’’ (node B.2). The latter can be implemented by means of either ‘‘underlay’’ or ‘‘overlay’’ spectrum sharing technologies.

3 This model was presented by Faulhaber and Farber (2003) in the following terms: ‘‘In this regime, spectrum would be owned but subject to an easement that any and all users that did not meaningfully interfere with the owner’s right to spectrum could not be excluded from using the spectrum. In effect, this easement creates a commons at all frequencies and in all locations of a special type: non-interfering uses only.’’

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Under a HAM approach (node B.2), secondary unlicensed users can work (in an overlay or underlay mode) in frequency bands assigned to primary licensed users, provided that they fulfill operative technical conditions defined in advance by the regulator to avoid harmful interference4. In particular, cognitive radio operation can be envisaged under a HAM model, to implement an ‘‘overlay’’ paradigm (node B.2.2), that allows the secondary users to access the locally and instantaneously available spectrum, the so-called ‘‘spectrum opportunities’’, provided that they back off when the primary users are active. This approach, also referred to as ‘‘Vertical Sharing’’ or ‘‘Opportunistic Spectrum Access (OSA)’’, is proved to be the most performing solution in terms of achievable throughput (Zhao & Swami, 2007). It does not require severe constrains on the transmission power of secondary users, but it rather requires cognitive technologies that account for the state of transmission of the existing users in order to identify ‘‘white spaces’’ at a given location and time and to track the rapidly varying spectrum opportunities. As an example, Radio Local Area Network (RLAN) could work in the 5 GHz band provided that pre-cognitive technologies, such as ‘‘Dynamic Frequency Selectivity’’ (DFS), are employed to assure interference-free coexistence with radar system, which occupy spectrum as primary users. On the other hand, some regulators around the world, such as FCC in USA, are investigating on cognitive systems for the use of White Spaces in the UHF bands (FCC-10-174, 2010). In addition international standardization organizations such as IEEE 802 are working on standards that exploit cognitive technologies in White Spaces in the UHF bands to provide both wireless regional area network, WRAN (IEEE 802.22), wireless metropolitan area network, WMAN (IEEE 802.16h), and wireless local area network, WLAN (IEEE 802.11af), services. Finally, in response to a mandate from the European Commission on Ultra-Wideband (UWB), CEPT has been studying on active mitigation techniques and pre-cognitive technologies, such as Detect and Avoid (DAA), in order to accommodate high data rate UWB devices operating as secondary users in compliance with an ‘‘underlay’’ model (node B.2.1), keeping their transmission power below the interference temperature threshold (Xing, Mathur, & Haleem, 2006) of the primary users, and to protect broadband wireless access (BWA) applications such as WiMax systems in the band 3.4–4.2 GHz and radiolocation services operating in the band 3.1–3.4 GHz and 8.5–9 GHz (ECC, 2008). According to a different approach, a specific frequency band can be identified by the regulator to be dedicated to collective usage as ‘‘Dedicate Unlicensed’’ spectrum (node B.1 in Fig. 1), e.g., the industrial, scientific and medical – ISM – band. All unlicensed devices that are allowed to operate in that band share spectrum on a non-discriminatory basis as primary users. They respect restrictions and access conditions set by the regulator, which may require the devices to have cognitive features. According to this type of sharing, also called ‘‘Horizontal Sharing’’, the CR are assigned the same rights and equal chances to access the spectrum and they share the frequency band based on transparent and non-discriminatory conditions. Example of current use of this model are the short range device (SRD) framework, as set by the Commission Decision 2006/771/EC, as last updated, and the accompanying CEPT work. Based on this approach, also multi-radio and cognitive radio technologies have been investigated in order to allow coexistence of 802.11 Wireless LAN and 802.15.4 sensor networks in the ISM unlicensed band5. A variant CUS approach is the so called private commons or club use, where a service provider or broker defines the rules of admission on behalf of the regulator or based on the rules set by the regulator6. As highlighted by some commons advocates (Mitola, 2000), the introduction of CR technology could help to provide guarantees against interference, which constitutes the principal issue of the commons approach. This allows to fully gain benefits, such as low barriers to entry, reduced times to market and high flexibility in spectrum usage. Under the EPR regime (node C in Fig. 1), conditions set by policy makers are attached to the usage rights pursuant to dynamical spectrum sharing based on advanced technologies, including cognitive radio. The model draws on both the DEUM (node A in Fig. 1) and the CUS (node B in Fig. 1) models, combining the potential of advanced sharing technologies with market models (Faulhaber & Farber, 2003; Freyens, 2009; Pogorel, 2007; RSPG08-244, 2008). Spectrum efficiency is increased by easements permitting pooling, overlay, underlay, provided that interference is adequately managed. Cognitive radio operation is envisaged under a HAM model (node C.2), according to an overlay or vertical sharing paradigm (node C.2.2). CRs are only allowed to utilize frequencies within the band as long as the existing primary (licensed) users are not affected, that is the CR must not cause harmful interference to them. The spectrum access and usage conditions to be fulfilled by the CR devices can be set by the licensee within the regulatory framework identified by the rights of spectrum usage. Beyond defining access rules, authorizing trading or leasing of rights of spectrum usage and including, if needed, quality of service requirements, the regulator should assess the result of negotiations among market parties and their effects on competitions. Such an approach can be used to realize real-time spot-market, whereby rights to access the spectrum are traded instantly. Interesting examples of these innovative approaches stems from commercial initiatives such as ASA (authorized shared access)7, whose categorization would also depend on the rules set by the regulator as well as on the business model of the primary licensee. This concept has been further expanded by the Radio

4 Pursuant to Article 2 of directive 2002/21/EC as amended by directive 2009/140/EC, ‘‘harmful interference’’ means interference which endangers the functioning of a radio navigation service or of other safety services or which otherwise seriously degrades, obstructs or repeatedly interrupts a radio communications service operating in accordance with the applicable international, community or national regulations. 5 Task group 2 of IEEE 802.15 addresses the coexistence of wireless personal area networks (WPAN) with other wireless devices operating in unlicensed frequency bands such as wireless local area networks (WLAN). 6 It is noted that not all types of private commons could be considered CUS, since the license holder can set conditions of access the band that limit the number of admissible users, meaning that the number of users may not be ‘‘undetermined’’ as set out in the definition of CUS. 7 Brought forward initially by manufactures such as Qualcomm and Nokia.

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Spectrum Policy Group (RSPG) in its report on ‘‘collective use of spectrum (CUS) and other spectrum sharing approaches’’ (RSPG11-392 Final, 2011), that introduces the ‘‘licensed shared access’’ (LSA) concept defined as ‘‘An individual licensed regime of a limited number of licensees in a frequency band, already allocated to one or more incumbent users, for which the additional users are allowed to use the spectrum (or part of the spectrum) in accordance with sharing rules included in the rights of use of spectrum granted to the licensees, thereby allowing all the licensees to provide a certain level of QoS.’’8 Other than a HAM approach, also the foreseeable development of coordination and mitigation techniques and interference resilience would not rule out horizontal sharing. Under the EPR regime referred to as ‘‘Pooling Access Model’’ (node C.1), a group of licensed owners of a piece of spectrum can be allowed to share frequencies horizontally, by forming a pool of them that can be used by all licensees (RSPG08-244, 2008). This form of spectrum pooling can be employed to match the spectrum resources of the different licensees to their actual demand and it proves to be particularly useful in situations where demand varies in time and/or location. A central entity can be designated to facilitate this solution, such as a spectrum broker or a multilateral agreement among the parties. This kind of spectrum sharing should be endorsed by appropriate regulation. Moreover, minimum technical conditions should be set by the regulator for the blocks of spectrum in pool to be operated, together with appropriate procedures to be applied in case of disputes and interference issues among peers. As an example, such a model can be applied in a femtocell scenario, in order to realize a Collaborative Radio Resource Management (CRRM) for femtocell network deployments. As pointed out in (Mazzenga, Petracca, Pomposini, Vatalaro, & Giuliano 2010) the self-installation nature of femtocells sharing the same frequency band can lead to harmful femto-to-femto interference levels. The possibility for operators to share their licensed spectrum allows femtocells of one operator to exploit the frequency resources of other operators, which optimizes the overall system capacity. Another example could be the one proposed9 at the time by Ofcom, the UK regulator, for the 2.6 GHz band, where a number of concurrent low power users can share a portion of the band, either as dedicated band (node C.1) or in an underlay mode with high power users (node C.2.1). 3. Trends in the EU legislative framework promoting the deployment of cognitive radio A number of recent initiatives have been carried out at EU level could contribute to the use of CR-enabled spectrum sharing. They can be briefly resumed as follows:

 the reform of EU telecom package, specifically the measures envisaged by directive 2009/140/EC of the European  

Parliament and of the Council10 of 25 November 2009, targeting basic principles of any CR-enabled spectrum sharing approach, i.e., service and technology neutrality, and removing the main obstacles to spectrum trading; the establishment of a multiannual RSPP by decision 243/2012/EU of the European Parliament and of the Council, that sets out policy orientations fostering the collective and shared use of spectrum; the issue of a Communication by the European Commission, ‘‘Promoting the shared use of radio spectrum resources in the EU’’, in September 2012 (COM, 2012 478 final, 2012).

The recent reform of the EU Telecom Package, namely the framework directive 2002/21/EC and the authorization directive 2002/20/EC as amended by directive 2009/140/EC, introduces measures aimed to improve the flexibility and the efficiency of spectrum utilization, remove rigidity in spectrum management and deliver easier access to spectrum. In particular, flexibility in spectrum policy is pursued by the introduction of requirements of service neutrality and more emphasis on the principle of technology neutrality in granting rights of use. Technology and service-neutral authorizations ensure that all types of technology and all types of electronic communications services may be provided in the radio frequency bands declared available for electronic communications services in the relevant National Frequency Allocation plans in accordance with Community law 11. Opening some frequency bands to a variety of radio access technologies and services enlarges the scope for coexisting users to share the spectrum, also by means of CR technologies, thus increasing efficiency in its usage. Directive 2009/ 140/EC also reforms the discipline of individual rights to use radiofrequencies, by increasing the possibility to transfer rights between undertakings12. As long as dynamic and temporary license transfers are concerned, rather than permanent ones, CR technologies can be effectively applied by secondary users to detect locally and instantaneous unused spectrum by primary users and use it without causing harmful interference to them. CR could also allow the secondary users to achieve a certain level of quality of service, which is essential in scenarios where market mechanisms are envisaged. Similarly as before, the revision of the legislative framework helps in widening the scope for implementing CR technologies. The described framework principles have been recently translated into a more operative package of strategic objectives and practical provisions by the RSPP, setting out the policy orientations and objectives for the strategic planning and harmonization of the use of radio spectrum to ensure the 8

Further studies on this concept have been announced by the RSPG in his work programme for 2012 and beyond published in February. Ofcom – consultation on assessment of future mobile competition and proposals for the award of 800 MHz and 2.6 GHz spectrum and related issues – March 2011. 10 Directive 2009/140/EC of the European Parliament and of the Council amends directives 2002/21/EC on a common regulatory framework for electronic communications networks and services, 2002/19/EC on access to, and interconnection of, electronic communications networks and associated facilities, and 2002/20/EC on the authorization of electronic communications networks and services. 11 See Article 9(3) and 9(4) of directive 2002/21/EC as amended by directive 2009/140/EC. 12 See Article 9b of directive 2002/21/EC as amended by directive 2009/140/EC. 9

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functioning of the internal market for 2011–2015. It focuses on making spectrum available for wireless broadband services in order to support the Europe 2020 Strategy13 and the Digital Agenda for Europe14. It sets concrete priority initiatives for enhanced coordination, flexibility, and availability of spectrum for wireless broadband communications. In particular, RSPP recommends that Member States, in cooperation with the Commission and where appropriate, foster the collective use of spectrum as well as the shared use of spectrum. Member States are also called to foster the development of current and new technologies, for example, in cognitive radio, including those using ‘white spaces’. To this aim Member States are requested to promote and encourage R&D activities in new technologies such as cognitive technologies and geolocation databases. In line with RSPP, the European Commission published the Communication on ‘‘Promoting the shared use of radio spectrum resources in the internal market’’ (COM, 2012 478 final, 2012). It highlights that a key challenge for NRAs to authorize more shared access to spectrum is managing harmful interference between different co-existing applications in the same range of frequencies. In order to avoid that a serious degradation of respective functions occurs, interference mitigation should be achieved through reliable sharing arrangements based on clear, effective sharing rules and conditions in a band, creating certainty for both incumbent and prospective users. Moreover, the EC Communication stresses the need to create sufficient incentives and safeguards for all interested parties, balancing the impact on the incumbent and the usage constraints on any additional user. Since NRAs need appropriate means to enable suitable sharing arrangements and to foster the shared use of spectrum resources, the Commission proposes to develop two additional tools: an EU approach to identify beneficial sharing opportunities (BSO) in harmonized or non harmonized bands15 ; and the introduction of shared spectrum access rights as regulatory tools to authorize licensed sharing possibilities with guaranteed levels of protection against interference. The new framework then allows regulators a wide new set of instruments to start the introduction of technologies for spectrum sharing, including cognitive technologies. 4. Status of regulation and standardization of cognitive radios in Europe In parallel to the legislative course, relevant activities have been recently carried out by the Radio Spectrum Policy Group, providing the Commission and other EU institutions with advice on high level policy matters in relation to spectrum, as well as by international and European standardization organizations. In particular,

 a number of opinions and reports have been issued by RSPG to create a favorable regulatory playing field and make sharing a new deal in spectrum policy;

 CEPT and ETSI have worked to define technical and operational requirements for CR operation in possible candidate bands. Beyond providing Commission with contributions relevant to the preparation of the RSPP16, RSPG has specifically focused its work on technology based spectrum sharing mechanisms as a mean to improve spectrum efficiency. In February 2010 a first report (RSPG10-306, 2010) was published on cognitive technologies aimed at informing policy makers of the discussions and challenges raised by these technologies. The report highlights that the use of ‘‘white spaces’’ in the UHF broadcasting band can be one of the first applications of CR. As a follow up, an opinion (RSPG10-348, 2011) was published in February 2011 after a public consultation, that addresses possible implications to the EU spectrum policy of the implementation of CR technologies at a community level. RSPG Opinion points out that implementing measures to introduce the CR technologies can be left to Member States as long as border coordination issues are addressed for each band concerned. It also advocates taking into account the works by CEPT, standardization bodies such as ETSI, as well as the RSPG recommendations on functionalities implementing cognitive features17. Finally, in November 2011 RSPG issued a report on ‘‘collective use of spectrum (CUS) and other spectrum sharing approaches’’ (RSPG11-392 Final, 2011), where RSPG concludes that at the moment there is no identified need for more dedicated spectrum to be shared between different applications. Nevertheless, RSPG identifies a need to progress further on appropriate regulatory mechanisms in regard to sharing of spectrum and to foster more efficient use of it, both for the commercial and public sector. To this scope, it introduces the LSA approach, as a promising way to prove new sharing opportunities on a European scale under a licensing regime, while safeguarding national current spectrum usages which cannot be refarmed. 13 The programme supports the Europe 2020 Strategy for smart, sustainable and inclusive growth given the huge potential of wireless services to promote an information-based economy, develop and assist sectors relying on information and communications technologies and overcome the digital divide. 14 Digital Agenda for Europe aims to deliver fast broadband internet in the future network-based knowledge economy, with a target for universal basic broadband by 2013 and an universal broadband at speeds of 30 Mbps or above by 2020. Also by 2020, half of all European households should be subscribed to broadband connections of 100 Mbps. 15 According to COM (2012) 478 final, 2012), ‘‘identifying BSOs in a specific band requires transparency about the sharing arrangement that would be applicable, in particular (i) the sharing conditions, i.e., the technical parameters defined by a NRA that determine the access hierarchy in a shared band; and (ii) the sharing rules, i.e., the common usage provisions that allow sharing, which either could be mandated by a NRA or defined by users on the basis of standards, common protocols, or sharing agreements which comply with competition law’’. 16 The EU Commission initiated the legislative proposal of the RSPP taking into utmost account the opinion of RSPG10-330 (2010). 17 Other relevant RSPG works are: RSPG opinions on the digital dividend (RSPG09-291, RSPG07-161), aspects of a European approach to ‘collective use of spectrum (RSPG08-244), wireless access policy for electronic communications services (WAPECS) (RSPG05-102), and secondary trading of rights to use radio spectrum (RSPG04-54).

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In addition to the studies performed by RSPG, several initiatives concerning CR technologies have been promoted by international and European standardization organization. Also CEPT Electronic Communications Committee (ECC) launched a number of activities on the matter18. A project team from the ECC Spectrum Engineering Working Group (WG SE PT43) is in charge of defining technical and operational requirements for CR operation in the ‘‘white spaces’’ of the UHF broadcasting band (470–790 MHz), to the aim of guaranteeing the protection of incumbent radio systems19. In parallel, the Frequency Management Working Group (WG FM) is responsible to identify possible candidate bands for services implementing CR technologies in cooperation with ETSI (by WG FM). Two categories of bands are under consideration: bands already used by systems evolving towards CR by implementing cognitive functionalities, and bands, already assigned to primary systems, where secondary systems can be introduced provided that harmful interference is avoided by means of cognitive technologies. Finally, it is worthwhile making reference to the work on cognitive radio technologies performed by ETSI (European Telecommunications Standards Institute) within a number of Technical Committees. In particular, ETSI Technical Committee Reconfigurable Radio systems (TC RRS) is in charge of carrying out standardization activities related to reconfigurable radio systems, including both software-defined radio (SDR)20 and CR. The work focuses on the potential regulatory aspects of those systems, the requirements for radio equipment architecture, the functional architecture for the management and control of reconfigurable radio systems and the user requirements for public safety applications. 5. Recent regulatory activity in Italy The issue of optimizing spectrum utilization and allowing a more flexible use of radio frequencies also by means of cognitive technologies has recently been considered by the Italian regulator (Autorita per le garanzie nelle comunicazioni, Agcom) in setting the rules for simultaneous multiple round ascending (SMRA) auction of 255 MHz of spectrum in the 800 MHz, 1800 MHz, 2 GHz (2010–2025 MHz) and 2.6 GHz bands in its decision n. 282/11/CONS21. In particular, the regulator’s decision sets out measures for:

 implementing market-based mechanisms for more efficient sharing of wireless spectrum, such as leasing and trading22.  guaranteeing that, if operators do not use assigned bands directly or indirectly in areas not included in the mandatory



coverage plan after a certain period of time (save impediments not caused by them), they have to fulfill any reasonable request for access to the same frequencies, based on a commercial negotiation, on non-discriminatory and fair conditions23. evaluating the possibility of implementing agreements, that envisage intelligent sharing or shared access of spectrum, based on innovative technologies, such as cognitive radio24.

In its decision, the regulator takes utmost account of the described initiatives promoted at a Community level and it recognizes that the expected development of technology makes it possible to envisage a number of scenarios for frequency band sharing among different users, employing advanced and innovative technologies such as cognitive radio. These technologies can help to enter into intelligent sharing or shared access agreements. However, the NRA considers it premature to introduce an extensive regulation to address the issue of spectrum sharing and cognitive technologies since the relevant technical mechanisms are still to be specified and a deeper consideration of regulatory models is needed. At present, the NRA allows sharing mechanisms such as roaming with frequency sharing, active sharing of frequencies, and frequency pooling25 in areas not included in the mandatory coverage plan. Moreover, in its decision the NRA emphasizes the scope of future regulation. Specifically, in the light of the development of technologies and regulatory models, the NRA reserves the right of introducing conditions and obligations for intelligent spectrum sharing or shared access among different users in bands to be assigned or extended in accordance with its decision, possibly through the 18 CEPT ECC in synergy with ETSI has developed spectrum regulation for pre-cognitive technologies, such as UWB dynamic frequency selection (DFS) – reference FM(07)141- and detect and avoid (DAA) – reference ECC report 120. 19 On the matter, CEPT ECC has already published a report on ‘‘white spaces’’ (CEPT report 24), preliminary evaluating the feasibility of fitting new applications/services into non harmonized spectrum of the digital dividend. 20 The term ‘‘software defined radio’’ was coined in 1991 by Joseph Mitola, who published the first paper on the topic in 1992 (Mitola, 1992; Mitola & Maguire, 1999). Mitola defined software radio as ‘‘a radio whose channel modulation waveforms are defined in software. That is, waveforms are generated as sampled digital signals, converted from digital to analog via a wideband DAC and then possibly up converted from IF to RF. The receiver, similarly, employs a wideband analog to digital converter (ADC) that captures all of the channels of the software radio node. The receiver then extracts, down converts and demodulates the channel waveform using software on a general purpose processor’’. 21 Decision 282/11/CONS concerning ‘‘procedures and rules for the assignment and use of frequencies available in the 800, 1800, 2000 and 2600 MHz bands for electronic communications terrestrial systems and additional rules for fostering effective competition in using other mobile frequencies in the 900, 1800 and 2100 MHz bands’’. 22 See Article 10 of Agcom decision no. 282/11/CONS. 23 See Article 11 of Agcom decision no. 282/11/CONS. 24 See Article 19 of Agcom decision no. 282/11/CONS. 25 See Article 15 of Agcom decision no. 282/11/CONS.

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introduction of sharing mechanisms based on cognitive or equivalent technologies, overlay or underlay sharing, and market mechanisms based on aggregators such as brokers or band managers26. Finally, the decision makes clear27 that no a-priori obstacles should be put forward by licensed operators in the developments of already authorizable technologies such as those under the underlay or more general CUS umbrella. 6. Conclusions Spectrum sharing and cognitive radio technologies have been recently addressed as a promising solution to overcome the issues related to the inefficient usage of radio spectrum and to satisfy the increasing demand for spectrum from bandwidth-hungry and pervasive new services and applications. A consultation held by RSPG has revealed a general consensus that this emerging technology could significantly improve spectrum efficiency and foster the introduction of new services. Nevertheless, a careful approach is advocated by many stakeholders, particularly by broadcasters and mobile operators28 due to related concerns of interference with licensed users. Regulation can play a crucial role in proposing authorization models for spectrum rights of use and strategies for spectrum sharing based on CR technologies. The regulatory authorities are called upon to suggest solutions able to overcome the technical and political issues related to the coexistence of heterogeneous systems, typically operated by different agents. From this perspective, the article contributes to the discussion on CR by drawing a comprehensive taxonomy able to embrace the most significant models suggested in literature for dynamic spectrum access and sharing. We report and discuss illustrations of various regimes and practical experiments with shared spectrum rights. In particular, the article clarifies the terms of debate around technology-based mechanisms for spectrum sharing, highlighting the new opportunities offered by CR. In order to show the evolutionary path toward the implementation of spectrum sharing and CR technologies, the article outlines the current status of European regulation, policy and standardization and it provides a deeper insight of regulatory activity in Italy, specifying the framework that the regulator has created so far to promote and allow the use of spectrum sharing and CR technologies. From the analysis carried out it can be noted that further progress is needed both in the development of these technologies, and regarding the regulatory and authorization regimes most suitable to allow the convergence of all stakeholders’ interests and the sustainability of relevant business models. Interesting opportunities can derive from the use of LSA approach. It seems suitable to overcome the legitimate reluctance of operators to change the traditional assignment models of exclusive rights of use of spectrum and total protection from interference, justified by the need of ensuring adequate quality of service to end users. Because the LSA model is based on the respect for the rights of existing licensees to exploit the use of the band, this approach is a candidate solution suitable to start a paradigm shift in spectrum management towards a dynamic management of the frequency resources. Some regulators have already acted to allow and regulate the operation of specific cognitive devices. That is the case of the English regulator, which considers the use of interleaved spectrum by licence-exempt cognitive devices (OFCOM, 2009), also proposing a number of technical parameters to prevent harmful interference. However, due to the existence of scale and scope economies, a harmonized approach should be pursued by the European regulators. This is in line with the work carried out at the moment particularly by the RSPG, the advisor of the Commission for spectrum issues, the CEPT, for technical harmonization, and by the Commission with the Radio spectrum policy programme. The RSPG announced further work on licensed shared access for the second part of 2012 in its new work programme under Agcom Chairmanship, after the Commission publication of its Communication on the issue (COM, 2012 478 final, 2012). In this context it is reasonable to expect within a short timeframe a number of technical implementing measures and recommendations at EU level which will pave the way for a more massive and harmonized introduction of CR and related businesses in the internal market.

Acknowledgments The authors would like to thank Roberto Viola, Antonio Perrucci and Fulvio Ananasso for promoting the research activity on some issues in the present contribution and for their precious suggestions. The article also benefits from work that has been done in the framework of the RSPG task group in charge of investigating on cognitive radio technologies during the 2010 RSPG Chairmanship of Roberto Viola. The views expressed in the paper are those of the authors and they should not be assumed to represent Agcom position. References Barrie, M., Delaere, S., Anker, P., & Ballon, P. (2012). Aligning technology, business and regulatory scenarios for cognitive radio. Telecommunications Policy Elsevier Science, 36(7), 546–559.

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See Article 19 of Agcom decision no. 282/11/CONS. Same Art. 19. Public consultation on a draft version of the RSPG opinion on ‘‘cognitive technologies’’ was held from 23 November 2010 until 15 January 201. All responses can be found on the RSPG website: http://rspg.groups.eu.int/consultations/index_en.htm. 27 28

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