Impact of DSA on Current Regulatory Regimes∗

Ahmed Gad and Fadel Digham

National Telecom Regulatory Authority (NTRA)B4 Smart Village, K28, Desert Alex Road

Cairo, EgyptE-mails: {agad,fdigham}@tra.gov.eg

Abstract— A new paradigm shift in spectrum access is theso-called dynamic spectrum access (DSA) by which spectrumis allocated on a dynamic basis in response to changes in theoperational environment exemplified by spectrum demand, typeof service, and regulatory constraints. Consequently, this newparadigm has many impacts on current regulatory regimes,which naturally affect other telecom market players. This paperanalyzes these impacts and evaluates the strengths, weaknesses,opportunities, and threats (SWOT) associated with the DSA trendand then highlights the enabling mechanisms for DSA.

I. INTRODUCTION

The growing demand for wireless services and applica-tions shows no sign of slowing down. However, the currentcommand-and-control regulatory approach for licensing spec-trum has been unable to cope with the ever-increasing growthdemands of the wireless industry. This traditional approachis conservative in the sense that it is concerned only withthe interference issue and not with other factors includingeconomic welfare and social impact. This has given rise toan ’artificial scarcity’ of usable spectrum, resulting in higherprices for spectrum licenses precluding many small to mediumsize businesses from entering the wireless market.

It has been shown that several spectral bands (below 3GHz) are highly underutilized [1]. Numerous studies have thusbegun to examine how licensed spectrum is actually used, withthe goal of not only updating the spectrum licensing regimebut also opening certain underutilized ’prime’ spectrum tounlicensed and licensed secondary usage.

Recently, the new concept of Dynamic Spectrum Allocation(DSA) is being investigated by network and radio engineers,policy makers, lawyers, and economists. In DSA, spectrumwill be allocated dynamically according to current frequencyutilization and users’ demands in a time and space variantmanner. DSA holds a great promise in dealing with the para-dox that spectrum is scarce but underutilized. One realizationof the DSA concept is what is known as cognitive radios. Acognitive radio (CR) is a device that can sense spectrum, detectopportunities, adapt its parameters and configuration, andultimately learn from past experiences [2][3]. The CR in its fullpower should be built on top of a software-defined radio (SDR)structure [4]. SDR implies a common hardware supporting amultitude of waveforms and transmission parameters that can

∗ The ideas expressed in this paper do not represent the NTRA of Egyptor any known institution other than the authors.

be controlled by software to accommodate different services,standards, and applications.

New technologies and developments such as SDRs and CRsenjoy a great deal of smartness and independency as theycan autonomously handle interference issues and dynamicallyaccess available spectrum. This in turn sparks a new movetowards dynamic spectrum sharing and/or spectrum tradingin a way revolutionizing the existing administrative commandand control regime and overcoming the inefficiencies with thecurrent regulatory model.

Sharing spectrum between primary and secondary users mayexist in two variants: cooperative DSA and noncooperativeDSA [5]. In cooperative DSA, a secondary user may onlyuse a band with permission of the primary rights holder ofthat band. Normally, the parties will enter into a contractinvolving payment for access rights. In noncooperative DSA,the secondary user does not require permission from theprimary rights holder. By analogy to property law, easementscreated by regulatory authorities specify the conditions andrequirements for noncooperative spectrum access in a givenband. Low power ultra wideband (UWB) devices are anexample of non-cooperative spectrum sharing via an easement.Spectrum access rights are traded in a secondary spectrummarket. What is traded may include primary (exclusive use)rights; “secondary” in this context refers to trading subsequentto the initial assignment of rights by regulators. In noncooper-ative DSA, secondary access opportunities are discovered andexploited rather than traded, but it is still useful to consider itas a spectrum market subject to supply and demand behaviors.

In this paper we analyze the strengths, weaknesses, op-portunities, and threats (SWOT) associated with the DSAconcept and CR technology. Capitalizing on the outcome ofthis analysis, we propose key enablers for DSA/CR to getadopted and implemented.

The rest of this paper is organized as follows. The nextsection presents the SWOT analysis for DSA/CR. Section IIIthen identifies the DSA enabling factors. Our conclusions arefinally provided in Section IV.

II. SWOT ANALYSIS

This section examines the interlinked technical and eco-nomic issues of markets for DSA-based wireless services withthe aid of the SWOT analysis leading eventually to technicaland policy recommendations supporting the commercial suc-cess of the DSA technology. In this analysis, DSA and/or CR

978-1-4244-2017-9/08/$25.00 ©2008 IEEE 1

will be referred to where applicable (recall that CR is onemanifestation of the DSA concept).

A. Strengths

• Support of decentralized spectrum management: DSAreduces the need for centralized (command and control-style) spectrum management. It rather allows terminalsand network elements to take part in the spectrum man-agement process, thereby reducing the artificial spectrumscarcity resulting in part due to the centralized conserva-tive command and control approach.

• Situation awareness: The embedded sensing capabilityin CRs enables them to draw maps for the surround-ing environment [6] well describing the real world andnavigating multi-dimensions of interest. For example,upon sensing, CR should be partially or fully aware ofthe temporal/spatial band utilization, type of transmittedsignals, level of transmitted powers, etc. The availabilityof such maps and sensing information by itself is ofparamount importance in many applications.

• Higher spectral efficiency: CR can detect transmissionopportunities in vacant temporal/spatial channels (whitespaces) and then enhances the spectrum utilization. Re-cent test results has reported a 70 percent white space fillfactor [7] (the percentage of time that modem air time isactually available to a CR modem to transmit (or receive)its data).

• Learning capability: Based on past knowledge, patternsand observations -available mainly via sensing- coupledwith the knowledge of the current situation, CR canpredict future behaviors and can act accordingly targetingmore effective modes of communication [2]. In otherwords, CRs are leveraging many of the machine learningcapabilities and are acting in a way similar to thatexhibited by robots.

• Polite coexistence: CR can share the band with other userseither on a primary/secondary basis or a shared-spectrumbasis. More importantly, it can coexist politely, i.e., ona non-interfering basis by virtue of advanced techniquessuch as smart and directive antennas or adhering to apredefined etiquette.

• Frequency agility [8]: the ability to operate over a widerange of frequencies and switch between them in near-real time. Two types of agile radios may exist:

– Type 1: hopping on holes while using fixed band-width, e.g., current WLANs (bandwidth = 20 MHz)

– Type 2: variable bandwidth, e.g., turning OFDMcarriers ”on” and ”off”.

• Prioritized services: A key strength attained by CRs andDSA is the ability to prioritize the offered services andshorten/stretch the available bandwidth. This in turn isof paramount importance, especially in emergency timessuch as natural disasters or wars.

• Smartness and independence: CR is smart enough tochoose the best for its user while collaborating with othersusing advanced schemes such as smart antennas, gametheory, optimal resource allocation, machine learning, etc.

It can also act autonomously in cases of emergency, e.g.,being aware of its location, CR can autonomously contactthe nearest public safety agency or switch mode ofoperation and initiate an SoS call on a nearby commercialnetwork.

• SDR-based: As CR is typically built on an SDR structure,it naturally inherits SDR features such as interoperability,seamless roaming, multi-standard support as well as fasterand cheap rollout of new technologies and services.

• Legal precedents: The availability of legal precedents toDSA technologies is an enabling asset which eases theintroduction of DSA. Such precedents include [9]:

– WiFi: a typical Wi-Fi (IEEE 802.11) card supportsenvironment sensing (through listen-before-talk andchannel sounding) and can adapt the operationalfrequency parameters (within a set of channels).

– Trunking: is the technique of pooling channels andthen allowing users to temporarily draw from thepool to carry conversations on an as-needed basis.

– Dynamic Frequency Selection (DFS), IEEE 802.11h:Unlicensed national information infrastructure de-vices are permitted to operate in the 5 GHz bandwithout causing interference to existing radio fre-quency operations (government radars).

– Digital Enhanced Cordless Telecommunications(DECT) system: autonomously selects the least in-terference radio channel and scans the frequencyallocation as a background activity.

• Global interest: DSA and CRs are receiving growing at-tention worldwide from different organizations. To namea few:

– E2R: In 2004, the EU Information Society Technolo-gies (IST) initiated the End-to-End Reconfigurability(E2R) project on adaptability of the nodes along thecommunication path, encompassing equipment (ter-minals, base-stations, access points, gateways) andpotentially impacting all OSI layers. Phase II of theproject started in 2006 and comprised a consortiumof 12 manufacturers, 3 operators, 14 academics, and3 regulators.

– XG: In 2002, the Defense Advanced ResearchProjects Agency (DARPA) initiated the neXt Gener-ation (XG) communications program to investigatethe usage of opportunistic spectrum access (OSA).

– White spaces: an IEEE 802.22 standard [10] is beingdeveloped as the first CR standard allowing existenceof CRs as secondary users in the TV band wheredigital TV and wireless microphones are the primaryusers. Such an effort was supported by FCC.

B. Weaknesses

• Hardware limitations: SDR features are not yet fully ex-ploited. Some challenges precluding this full exploitationinclude the need for wideband components (e.g., antennasand amplifiers) and high-speed A/D and D/A conversions.

• Detection capability: To fully recognize and detect asignal, a matched filter approach has to be implemented.

2

This approach, however, can not be used by a CR as it isbased on the premise of knowing the transmitted signalwhich is typically not the case in the CR setup. There-fore, one has to resort to suboptimal methods includingenergy detection and feature extractions. Energy detectionattempts to calculate the energy attained in the receivedwaveform and compares it to a predefined threshold todeclare whether or not a signal exists. Feature extractionlies in between the two extremes of just detecting energyand recognizing the full signal. It extracts some usefulinformation about the signal given some a priori partialknowledge, e.g., cyclostationary detection. Other detec-tion problems include the hidden node problem and thedetection of low power signals.

• Coordination and management: Among the key charac-teristics of DSA or CR are decentralization, distribution,and adaptation. This naturally creates many challengesand difficulties pertinent to synchronization, allocation ofcontrol channels, and access etiquettes.

• No immediate band evacuation: The concept of DSAallows some users to access spectrum on a secondarybasis by utilizing the unused portions of spectrum whilecausing no harmful interference to spectrum primaryholders. However, despite the various protection levels,interference caused by secondary/opportunistic users cannot be totally avoided. As nodes can not receive/sensewhile in transmission, immediate evacuation of the bandonce a primary user shows up seems infeasible.

• Unguaranteed policy conformance: DSA capability im-plies that devices should be both frequency and policy-agile. A spectrum-agile device can operate over a widerange of frequencies. A policy-agile device understandsthe constraints under which it operates: which frequenciesare available, and the rules for opportunistically usingthose frequencies. As these rules change with locationand time according to decisions of policy makers andprimary users, a radio, especially a mobile radio, must beable to shift from one set of policies to another easily andquickly which may not be guaranteed in all cases [11].

• Possible security failures: The more openness spectrumaccess is, the more susceptible to security failures. Cur-rent systems still lack strong security and authenticationmeasures.

• Disruptive technology: Although DSA and CR technolo-gies have legal precedents as indicated in the strengthsabove, CR in particular is considered as a disruptivetechnology as it needs dramatic spectrum policy reforms.

• Unguaranteed quality of service (QoS): In some cases,especially for the opportunistic mode of access, QoSprovided by CR may not be guaranteed.

C. Opportunities

• Digital dividend refers to the freed up spectrum in the700 MHz bands upon switching to digital broadcasting.This newly available spectrum can then be used fornew applications including homeland security, mobileInternet, mobile TV, and terrestrial HDTV. DSA-basedapplications may have a chance in as well.

• FCC issued the TV band notice of proposal rule mak-ing (NPRM) [12] allowing license-exempted radios (orsecondary users) to operate in the TV band providedno harmful interference is caused to incumbent users (orTV receivers). First standardization for CRs is being nowdeveloped to allow existence of CRs as secondary users inthe TV band while digital TV and wireless microphonesare the primary ones. This move has the potential tohelp regulators achieve their universal service mandate(i.e., providing means of communications to underservedareas) due to the superior propagation characteristics andwide area coverage exploited via transmission in the TVband.

• This era is marked by “convergence” that is takingplace at all levels, namely convergence of services (e.g.,voice and data), networks (e.g., all-IP), or devices (e.g.,a cell phone with WiFi access). This naturally willcall for new licensing regimes and will cause servicesdefinition and resources allocation to be more dynamicand flexible. Such a move can well be supported withinthe DSA/CR/SDR framework due to its dynamic natureand ability to fully integrate technologies, services, andfrequency dimensions.

• Issues pertinent to the DSA concept and the implementa-tion of the CR technology are projected naturally ontodifferent dimensions including technology, regulation,economics, and law. This then creates the opportunityfor partnerships and interdisciplinary collaboration atdifferent levels between these involved parties in a waynever observed in other system designs beforehand. TheDySPAN conference is one obvious example for integra-tion between policy and technical tracks.

• Current standardized systems can enjoy an added-on CRlayer or engine leveraging the full power of CR features,e.g., CR on WiFi and CR on WiMAX [13].

• By virtue of CR capabilities, fragmented narrowbandchunks of spectrum can be grouped as one broadbandsegment promoting broadband communications.

• A key feature offered by CRs is what is called policy-based radios [11][14]. As the name implies, this featurewill enable regulators to control the behavior of radios ona dynamic basis according to newly imposed rules andpolicies. Per instance, at times of disaster, public safetyradios can acquire more bandwidth that commercial ra-dios will be forced to free.

• DSA shall entail new spectrum auctioning schemes. Perinstance, it offers the regulators the option to considerissuance of co-primary licenses, as a step forward alongthe line of current practices of secondary/secondary (un-licensed) and primary/secondary (white spaces) licensingschemes. One variant of this co-primary licensing schemeis the issuance of primary service providers a minimumportion of spectrum each, in return of a fixed fee. Thenupon online demand, new allocations can be awarded toeach provider for other dynamic fees.

• New value chains and market incentives should grow uparound the new features of DSA radios.

• As a result of increased spectrum trading and sharing

3

attained by DSA, spectrum access is expected to getcheaper opening the door for new entrants and con-sequently more competition proliferating the types ofoffered services and driving service prices down.

• DSA allows new services to replace legacy ones moregracefully. A new entrant can begin with inexpensivecapital and limited spectrum access rights, then scaleits usage rights to match its capacity needs as businessgrows.

• DSA will stimulate innovation in wireless communica-tions even from operators who do not exploit it.

• DSA technologies can change our use of spectrum assetsthe way the IP protocol changed our use of traditionalswitching communications networks [15].

• New types of intermediaries may emerge to exploit newopportunities, including a mobile virtual network operator(MVNO) that operates a service in multiple bands andspectrum brokers that specialize in managing the trans-ference of access rights in secondary markets [5].

• There will be strong incentives for device manufacturersto acquire and reuse etiquette implementations. Thiswill promote the componentization or modularization ofradio system design. Software radio technology, which isdistinct from DSA but is likely to be used to support DSAsystems, also promotes the vertical disintegration of tra-ditional vertically-integrated equipment industry [1][16].

D. Threats

• Lack of awareness about DSA and CR technology andassociated economic and social benefits coupled withunavailability of supporting commercial devices makesit unlikely to adopt this technology in the near future.

• The bulk of existing wireless devices does not supportDSA/CR features and functions and needs to be replacedby a new wave of DSA-enabled devices.

• Existing policies and spectrum management schemesneed a reformation in order to comply with and maximizethe benefits hold by DSA.

• Primary license holders are expected to object to tradetheir rights with secondary users.

• Spectrum sharing and dynamic imposed policies may putregulators’ and other stakeholders’ goals and require-ments at risk due to vulnerable security measures anddelay in conforming to new policies [11].

• In many countries (especially developing ones), em-powered governmental organizations (e.g., defense andintelligence) are expected to resist to the DSA conceptmainly due to security issues.

• The property rights model associated with DSA and CRsis still a matter of debate and is not yet known whenand how it may be resolved. Factors contributing to thisdebate are determinations of an interference metric, aliable entity in case of failure, and possible kinds ofcompensation.

• It is difficult to identify the authorized users. Rolesand standard procedures must be established to clarifyrights and allocate responsibilities for secondary spectrumtransactions among the multiple rights holders.

• DSA can be looked at as a disruptive technology whichwill reshape the radio services market and existing indus-try value chain as well as clash with existing technologies.

• The market mechanism still needs to experience whicharrangements of the value chain and new intermediariesmake the most sense.

• The dynamic transactions offered by the DSA marketshall entail more complex models for interconnectionagreements between different market players.

• The current type approval process for authorizing andcertifying equipments and devices needs be changed tomatch the dynamic operations of devices. Such a changeseems difficult to realize. In addition, new monitoringschemes to assure compliance with regulatory rules needalso be developed.

III. DSA ENABLING FACTORS

In this section, we address some factors that can potentiallypave the way for embracement of the DSA concept.

A. Pilot Demonstration

The perceived risk of potential interference due to DSA-based radio operation must be put into context. This canbest be achieved through real demonstrations or pilot projects,initially deployed in low-risk bands.

B. Market Potential

The value of services offered by DSA radios must bestimulated, in order to support the pricing of leases in thesecondary spectrum market, and/or provide economic justifi-cation for regulatory supportive actions. Initially, the perceivedvalue is likely to be lower than its eventual equilibrium level,due to concerns about the quality of service that can bedelivered without guaranteed spectrum rights and due to theaggressive competition from existing market players. It is alsorecommended that trading of spectrum rights be for shorttime blocks and small bands with defined regions and specificpurposes, at least in the beginning.

C. Customer Demand

The next enabler for success of DSA-based wireless ser-vices is sufficient customer demand in the secondary accessspectrum market. Initial customers in the secondary spectrummarket could be companies whose products depend on DSAtechnologies, whether equipment vendors (e.g. manufacturersof WiFi access points), service providers, or carriers. Overtime, as DSA-enabled devices become more successful, weexpect end-user to begin acquiring spectrum access directly.Examples include a special event application where a hotelmight expand the capacity of its wireless network whenhosting a convention, through temporarily acquiring secondaryaccess to additional spectrum; or, a community of users mightacquire spectrum as needed to support a broadband localaccess mesh.

4

D. QoS

The level of demand by customers in the secondary spec-trum market is highly dependent on the QoS vs. price tradeoffachievable by DSA. That is, a communications service withlower QoS may still generate significant end-user demand ifit is cheap enough and maintained within the acceptable per-ceptual quality level. Such price/QoS tradeoffs are a hallmarkof competitive markets. It appears that DSA-based serviceswould have a strictly lower QoS than basic wireless servicesthat enjoy guaranteed spectrum access. However, it is betterto say that DSA-based services will offer a different QoS,one that is more desirable for some applications, in the sameway that the Internet telephony offers a different QoS fromtraditional telephone networks.

E. Regulatory Actions

Successful implementation of DSA-based technologies re-quires a great deal of cooperation between the regulatoryagencies, incumbent users, equipment manufacturers, andthe equipment certification laboratories. Regulators currentlyadopt the principle of sharing at different scales includinginfrastructure sharing, business-sharing regulation, end-usersharing, as well as policy and regulatory harmonization [17].In continuation to this practice, regulators (or spectrum author-ities) should devise recommended actions to promote spectrumsharing. These actions should cover the following four mainaspects:

1) Technology: A spectrum authority agency could assign aspectrum portion to enable researchers to test techniquesand equipment. This should include both laboratory andfield testing.

2) Standardization: As we have seen before (with GSM,3G, 802.11, etc.) standardization is critical to ensur-ing that devices work globally, thereby enabling theeconomies of scale. Standardization of the interfacesbetween CR components and of data inputs (spectrumdata and policies) is required as well. It is recommendedthat regulators have a role in the standardization processof DSA-based technologies due to the special natureof the DSA concept which is highly affecting currentregulatory models. Such a participation shall yield abetter standard which takes into account both regulatoryand technical aspects.

3) Resources: There is mainly a need for:• ensuring that adequate spectrum is available to

meet demand for deployment of fixed and mobilebroadband networks across; and

• recovering and “reforming” previously assignedspectrum that is unused or underutilized in orderto accommodate new services.

4) Regulatory framework: An appropriate regulatory frame-work is essential for CR to be able to deliver thebenefits to users whilst minimizing the impact on legacyusers and other CR users. In order to stimulate allstakeholders to adopt the frequency sharing concept,regulators should revise their existing frameworks byseveral manners:

• identification of bands in which DSA/CR should beallowed with corresponding transmit rights;

• spectrum allocations in proper amounts according toactual users’ needs, market conditions, and emerg-ing technologies while guaranteeing efficient andfair competition among spectrum users [18];

• moving toward establishment of market-based ex-clusive spectrum rights (i.e. the ability to buy, sell,lease spectrum holdings) and the elimination ofbarriers to the development of spectrum secondarymarkets (to effectively manage the exclusive-rightsregime, it is significant to define the tradable us-age rights and obligations, permit various forms oftrading of these rights, allow more flexibility oflicense use, and establish and clarify enforcementmechanisms);

• certification of equipment taken into account thedynamic nature of behaviors;

• reviewing both current license fees (to correct feeimbalances that may exist among service providers)and the application of market-based pricing ap-proaches for non-auctioned licenses;

• streamlining and standardizing licensing processes;• continuing the use of regulatory approaches to in-

crease the opportunity for consumers to have anexpanded choice of service providers;

• modifying regulatory policies to allow nontradi-tional value chains to occur and evolve, and notto artificially bias the market towards choosing onevalue chain structure over another;

• developing new models for the interconnectionregime between different market players in a stepsupporting this emerging technology and removingcurrent market barriers to entry; and

• establishing modern monitoring schemes to assurecompliance with regulatory rules.

IV. CONCLUSIONS

Dynamic spectrum access (DSA) holds great promise inoffering the ever-sought flexibilities in managing spectrum ona dynamic basis. By exploiting temporal and spatial vacantbands, DSA assures best utilization of spectrum and thereuponentails higher spectral efficiencies. From another perspective,it encourages new market entrants due to different flexibilitiesand low entry cost and shall stimulate the development of newservices and applications. Emergence of new technologies andapplications is highly contingent upon spectrum availabilitywhich, by virtue of DSA, can become feasible using eitherspectrum commons (i.e., spectrum sharing) or real-time spec-trum trading.

Supporting technologies such as cognitive radios (CRs) arebeing developed and standardized. Thanks to DSA and CRs,the new era will be marked by more healthy competition,more innovations, more access opportunities, and a varietyof services. New value chains are expected to emerge andthe lifecycle of products and businesses is likely to speedup. To enable such an environment, regulatory policies need

5

to be reformed shifting away from traditional command andcontrol mechanisms toward more market-based mechanisms.This means increased reliance on industry driven rather thangovernment mandated standardization, and lightweight regu-latory rules that clearly specify the property rights of primaryand secondary users.

On the downside, openness of spectrum is being facedwith many challenges pertinent to definition of appropriateinterference metrics, security issues, property rights, universalregulatory harmonization, and maturity of supporting tech-nologies. What is clear now is that fundamental change mustbe made to how spectrum is allocated and used. Not tomiss this unique chance of liberalizing spectrum access andregulatory policies, all stakeholders have to integrate theirefforts so as to perfectly assess this new trend of DSA andcollectively pave the way for it once it proves efficient andrealizable.

REFERENCES

[1] W. Lehr, “Dedicated Lower-Frequency Unlicensed Spectrum: The Eco-nomic Case for Dedicated Unlicensed Spectrum below 3 GHz,” NewAmerica Foundation, Spectrum Policy Program, Spectrum Series WorkingPaper No. 9, May 2004.

[2] J. Mitola, “Cognitive Radio: An integrated agent architecture for softwaredefined radio,” PhD dissertaion, Royal Institute of Technology, 2000.

[3] S. Haykin, “Cognitive Radio: Brain-empowered Wireless Communica-tions,” in IEEE JSAC , vol.23, no.2, Feb 2005.

[4] M. Dillinger, “Software Defined Radio: Architectures, Systems, andFunctions,” Wiley, 2003.

[5] W. Lehr, “Cognitive Radios for Dynamic Spectrum Access - The Pathto Market Success for Dynamic Spectrum Access Technology,” IEEECommunications Magazine, May 2007.

[6] Y. Zhao, L. Morales, J. Gaeddert, K. Bae, J. Um, and J. Reed, “Ap-plying Radio Environment Maps to Cognitive Wireless Regional AreaNetworks,” Proc. of IEEE Dyspan 2007, Dublin, Ireland, April 2007.

[7] M. McHenry, E. Livsics, T. Nguyen, and N. Majumdar, “XG DynamicSpectrum Sharing Field Test Results,” Proc. of IEEE Dyspan 2007,Dublin, Ireland, April 2007.

[8] S. Shankar, C. Chou, K. Challapali, and S. Mangold, “Spectrum agileradio: capacity and QoS of dynamic spectrum assignment,” Proc. ofGlobecom05., St. Louis, MO, USA, Nov 2005.

[9] J. Bernthal, T. Brown, D. Hatfield, D. Sicker, P. Tenhula, and P. Weis,“Trends and Precedents Favoring a Regulatory Embrace of Smart RadioTechnologies,” Proc. of IEEE Dyspan 2007, Dublin, Ireland, April 2007.

[10] IEEE 802.22 Working Group on Wireless Regional Area Networks,www.ieeee802.org/22.

[11] F. Perich, “Policy-based Network Management for NeXt GenerationSpectrum Access Control,” Proc. of IEEE Dyspan 2007, Dublin, Ireland,April 2007.

[12] Federal Communications Commission (FCC), “Notice of Proposed RuleMaking,” ET Docket no. 04-113, May 25, 2004.

[13] X. Jiang and D. Raychaudhuri, “Spectrum co-existence of IEEE 802.11band 802.16a networks using the CSCC etiquette protocol”, Proc. of IEEEDyspan 2005, Baltimore, Maryland, USA, Nov. 2005.

[14] G. Denker, D. Elenius, R. Senanayake, M Stehr, and D. Wilkins, “APolicy Engine For Spectrum Sharing,” Proc. of IEEE Dyspan 2007,Dublin, Ireland, April 2007.

[15] F. Seelig, “A Description of the August 2006 XG Demonstrations atA.P. Hill,” Proc. of IEEE Dyspan 2007, Dublin, Ireland, April 2007.

[16] B. Glover and M. Nekovee, “Dynamic Spectrum: Going Full Circle,”Proc. of IEEE Dyspan 2007, Dublin, Ireland, April 2007.

[17] Global Symposium for Regulators 2008 (GSR08), Pattaya, Thailand,11-13 March 2008.

[18] H-Y Yoon, “Techno-Economic Analysis for Future Dynamic SpectrumPolicy,” Proc. of Wold Telecommunications Congress, Budapest, Hungary,May 2006.

6