“new approaches to licensing” oliver holland, king’s college london arturo basaure, aalto...
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“New Approaches to Licensing”
Oliver Holland, King’s College LondonArturo Basaure, Aalto University
Numerous other authors, e.g., in SIG-PL, etc.
Workshop on Cognitive Radio Policy and RegulationVilnius, Lithuania, April 2014
StructureIntroductionNew Approaches to Licensing
Light LicensingAuthorised Shared AccessLicensed Shared AccessOther Developments
Our Proposal: Pluralistic LicensingConclusion
Introduction
The Past: License ExemptSimple basic rules to access of spectrum freely,
such as transmission power limit, spectrum mask requirements, etc. Assessed at device certification.
Pros:A hot-bed of innovation in wireless field—created a plethora
of novel applications and wireless uses.An entry point for “free” wireless services.Led to the development of popular standards such as WiFi,
Bluetooth and ZigBee.Spill-over of related innovation to other bands.Rich eco-system.
Cons: Interference/coexistence concerns, coverage issues, others.
The Past: LicensedUsers have to obtain a license to access the spectrum,
again with some rules attached by the regulator. Devices again assessed at certification, as well as means being enforced for ensuring that license is adhered to.
Pros:Reliable services:
Near-ubiquitous voice connectivity in public land mobile. Early data services. High-quality broadcast services. Guaranteed clean spectrum for critical services.
Cons:There are efficiency concerns of such bands .
Parallel need for more spectrum, mobile data growth, etc.
The Present: Stalled Innovation?Opportunistic/dynamic spectrum access (OSA/DSA), enabled
by cognitive radio key impetus of wireless research & innovation.
Barriers:Extremely onerous technical requirements to protect
incumbents.Nascent markets.Geolocation database access and location determination
challenges.Lack of appropriate spectrum.Resistance of incumbents due to “fairness factor”.Severe and yet to be defined certification requirements.Difficulty to scale from test & trial licensing incentives (low cost)
to commercial deployment (extremely high cost): Costs – e.g. nationwide, long-term licence. Deployment band & conditions of usage are usually different than the wireless
test & trial scheme used to test the new technology/service.
The mobile/wireless telecommunication market expected to continue growing extremely rapidly in the next decade.
Presents many challenges:Provision of spectrum.
Both a problem and solution.QoS guarantee for the given data rate.Energy efficiency.Sufficient (quality) spectrum for new players in the
market—competition concerns.Numerous others…
Moving into the Future: Data Growth
Moving into the Future: Data Growth
M2M
Moving into the Future: Data GrowthCooper’s Law, Edholm’s Law, etc.
illustration courtesy of IEEE Spectrum
Moving into the Future: Data Growth Capacity provision. Solution is to increase:
Rate per bandwidth (radio interface performance / spectral efficiency). Overall bandwidth (amount of spectrum). Densification (frequency reuse).
Shannon limit challenging, and already being reached (if systems are tested in idealistic scenarios). “Densification” presents severe challenge (among others) of there being a vast increase in access points—latent energy consumption, securing of sites, management issues, etc.
Increase of spectrum is an appealing solution to address such issues – can be done (usually) with the same sites, (in some cases) similar equipment, lesser implications in terms of energy consumption, etc.
Need for new Licensing SchemesSpectrum sharing is key means for provision of more spectrum.Many services do not use all of their spectrum.
In time. In space. In a spectral sense, e.g., channels within a band allocation.
Technical means exist that enable the reuse of spectrum. Temporally. Spatially. Spectrally (e.g., reuse of channels).
Appropriate safeguards can usually be implemented in allowing sharing.
Regulation is the biggest challenge for spectrum sharing technologies.
Can be extrapolated to licenses as issued by regulators not allowing spectrum sharing and related technologies such as CR. Licenses that permit reuse of unused spectrum of an incumbent in a controlled manner, guaranteeing no harmful interference to the incumbent, needed.
New Approaches to Licensing
Light Licensing(Sort of) new. Has long been the case that spectrum is
allocated (though different priorities) on a spatially varying or individual basis. But novel light licensing models are big advancement, with appropriate safeguards, accelerating regulator-authorised sharing among (co-)primary systems.
Such solutions can nevertheless often still imply a workload for the regulator or associated entity, due to the process of allocating the license, calculating implications, etc.
One model (for infrastructure-based scenario).Small fee for non-exclusive use of the spectrum in general.Additional license fee for each deployed base station.Client devices are not required to pay a fee, but must
receive an enabling signal from a licensed base station before transmitting.
Light LicensingAlso subject to alternative
understandings/implementations, anywhere between the following extremes.
One extreme:Individual authorisation (e.g., per-BS deployment is
example): Individual frequency planning/coordination. Simplified procedure compared with typical procedure of
individual authorisation. Likely limitations on the number of users.
Other extreme:A form of general authorisation characterized by:
No individual frequency planning/coordination. A requirement for registration and/or notification that allows
controlling the deployment and use of the application, but does not restrict it.
Light LicensingBeing suggested for deployment (or being
deployed) in various prominent contexts. Just a few examples here.
IEEE 802.11y:High powered data transfer equipment to
operate on a co-primary basis in the 3.65 to 3.7 GHz band in the United States.
Other potential bands 4.9-5GHz, even IMT-Advanced bands.
Other services (e.g., WiMAX) in 3.65 to 3.7 GHz band.
E-band 71-76 and 81-86 GHz, “pencil beam” communications.
Light Licensing“Second digital dividend” in ITU region 1.
Mobile broadband and broadcasting on co-primary basis in 694MHz-790MHz (lower bound and general rules to be determined in WRC 2015).
Could be candidate for light licensing type agreements? Will be clearer after WRC 2015, and after result national
regulatory decisions.FCC’s 3.5 GHz small cells (“General Authorized
Access”).5.8 GHz spectrum to allow other services
coexistence.Professional PMSE equipment.Amateur services.
E.g., Ofcom business radio licensing.
Authorised Shared Access (ASA)Scheme proposed by Qualcomm and Nokia in a joint response to
an RSPG consultation on cognitive technologies in January 2011.Subsequently refined in report and presentation to ECC meeting
in March 2011, and in a May 2011 in a report to the CEPT Working Group on Frequency Management.
Based on the use of cognitive radio techniques to determine channel availability.
Bilateral negotiated and regulator recognized agreements between new and incumbent users to set the conditions for frequency access. Might include compensation to the incumbent(s) for agreeing to
share.Newcomer, in return, would gain an assured amount of spectrum
availability in the form of a guaranteed minimum amount of spectrum use time in certain geographic areas; advance warning if access will be suspended.
See, e.g., http://www.qualcomm.com/media/documents/files/wireless-networks-1000x-more-spectrum-especially-for-small-cells.pdf
Authorised Shared Access (ASA)Proposed in context of reuse by mobile systems, but not
limited to that.
Image courtesy of Qualcomm
Licensed Shared Access (LSA)As defined by the Radio Spectrum Policy Group:
“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.”
Translated (!!):Framework for limited number of additional licensees to
obtain access to spectrum that is already allocated. Licensed users (“incumbents”) share spectrum with one or more new users (“incoming users”) in accordance with conditions defined by regulation (based on agreement of both “licensed” and “opportunistic” parties).
These conditions may be “static” (e.g., an exclusion zone, with a restricted time for operation) or more “dynamic” (e.g., geographic / time sharing, on-demand authorisation).
LSA vs. ASADistinction between ASA and LSA not widely defined, even often (in
a number of high profile publications) taken to be one and the same thing.
LSA is at least an attempt to codify ASA at the regulatory/policymakers level, and debatably somewhat more than that.
LSA brings licensing up-front in that it makes it clear that the opportunistic LSA/ASA spectrum user is also issued a license, etc.
LSA takes negotiated agreements concept between both parties on guaranteed minimum QoS.
But considers any new agreement on temporary transfer of frequency use rights as a “change of use” for an exclusive assignment. Therefore, has the “sharing rules included in the rights of use of spectrum granted to the licensees”. I.e., the “sharing rules” negotiated by the licensees must be approved by the regulator and incorporated in their licence conditions as amendments or replacement licenses.
LSA seems to be moving away from incorporation of “cognitive radio ” approaches in the spectrum reuse by the ASA licensee.
Other Developments There are numerous other developments here. Pertinent examples:
White space rules per se, although these generally are expressed as appropriate conditions/rules for the “unlicensing” of white space equipment1, 2.
FCC “small cell” three-tiered access in 3.5GHz. Resonances with ASA/LSA, light licensing approaches, and white spaces database approaches 3.
FCC “interference limits policy” approach. Means to greatly enhance the efficiency of spectrum access, given knowledge of implied interference at the receiver, rather than transmitter-side (e.g., power limit)4. Licenses instead based on interference limits…?! Second incarnation of this concept, after initial suggestion some 10 years ago. Associated efforts to characterise receiver-side, e.g., rejection of adjacent band
interference, etc.
1 FCC Second Memorandum and Order, “, Additional Spectrum for Unlicensed Devices Below 900 MHz and in the 3 GHz Band” September 23, 2010 (see also the third MO&O from August 2012!!)
2 Ofcom, “A Consultation on White Space Devices Requirements,” (and related consumtations linked to therein), http://stakeholders.ofcom.org.uk/consultations/whitespaces
3 FCC NPRM and Order, “Enabling Innovative Small Cell Use In 3.5 GHZ Band NPRM & Order,” March 20134 FCC Public Notice:, “Office of Engineering and Technology Invites Comments on Technological Advisory
Council (TAC) While Paper and Recommendations for Improving Receiver Performance,” June 2013
Our Proposal:PluralisticLicensing
Pluralistic Licensing“Award of licenses under the assumption that opportunistic
secondary spectrum access will be allowed, and that interference may be caused to the primary with parameters and rules that are known to the primary at the point of obtaining the license”. Primary will choose from a range of offered “pluralistic licenses” each
with associated fees, and each specifying alternative opportunistic secondary spectrum access rules with known interference characteristics.
Objective is to incentivize the primary to obtain this type of license through means such as a reduced license fee, whereby the opportunistic secondary spectrum access will use “cognitive radio” mechanisms to avoid causing interference to the primary or to otherwise keep interference within known parameters.
Better secondary design can also be incentivised, e.g., through reduced certification fee (however, not a core objective of the concept).Novel means for spectrum licensing which is fair to both
primary and secondary users and takes into account requirements of both parties.
Pluralistic LicensingWhy not combine best of the licensed/licence-exempt
worlds?
Pluralistic licensing
Licensed access:
Reduced fee compared with conventional license;accepts
opportunistic access
Opportunistic access:
Low or zero fee; must meet requirements for awareness of primary
users
See, e.g., O. Holland, L. De Nardis, K. Nolan, A. Medeisis, P. Anker, L. Minervini, F. Velez, M. Matinmikko, J. Sydor, "Pluralistic Licensing," IEEE DySPAN 2012, Bellevue, WA, USA, October 2012
Pluralistic LicensingBenefits:
Encourages more robust or better design of primary systems, leading to the ability to cope with increased degree/risk of interference among other benefits. Greatly improves spectrum usage efficiency and fairness. Possible pricing mechanisms for secondary systems (e.g., at
certification stage?) might also lead to the better design of secondary systems—e.g., incorporating sensing for secondary-secondary awareness (better secondary coexistence).
Allows opportunistic spectrum use while providing any level of protection desired by the primary.
Highly flexible dependent on the case-by-case deployment context (e.g., intended primary service), even so far as allowing solutions such as spectrum sensing and primary beacon transmissions which would otherwise not be practical or desirable, while defaulting to safe mechanisms such as a geolocation database in cases where a lower interference variance is required.
Pluralistic LicensingBenefits:
Reduced challenge for secondary coping with inefficiencies of legacy primary systems (particularly in “green-field” deployment scenarios). In obtaining the license, primary users implicitly accept rules of the band
hence will be designed and manufactured with better technical capabilities that are able to cope with those rules—better rejection of adjacent channel interference, better robustness to short-lived interference increases, better sensitivity, etc.
Highly scalable to progressive deployment in more spectrum bands. Rules for each deployed band (e.g., the use of spectrum sensing, the
geolocation database, or potentially even a beaconing mechanism being employed by the primary) being determined based on the intended context for that band (e.g., the expected primary services(s), expected burden on the primary, etc.).
Lends well to progressive deployment of primary transmitters as a network invests, for example, using a licensing regime similar to light-licensing.
Could even be (carefully) deployed in legacy bands. Incentivises the primary to make more efficient use of spectrum,
and to make unused spectrum available.
Licence-exempt
Light-licensing
Authorised / licensed shared access
Exclusive
Pluralistic licensing
A good, adaptable balance between exclusive use and license-exempt access.
Primary interference and license fee based on primary/secondary services.
e.g. ISM, short range devices
Registration with regulator, e.g., low power in-building system
e.g.,GSM/UMTS/HSPA/LTE
e.g., mobile broadband/ 2.3GHz
Interference License fee
Dual-priority broadband Primary broadcast; secondary mobile broadband services
Pluralistic Licensing
more interference
less interference
Burden on primary License fee
Beacon messages sent by primary to ward off secondary
Primary registered in geolocation database only
Pluralistic Licensing
Burden on secondary Fee paid by secondary
Low quality sensing (e.g., energy detection)
High quality sensing (e.g., feature detection), for secondary politeness
Proactive primary mechanisms and pricing.
Possible pricing example for secondary (relevant to secondary-secondary coexistence; could be relevant also to primary-secondary).
No sensing (only refers to geolocation database)
Pluralistic LicensingExample considerations in choosing/configuring
PL.Fixed vs. mobile (primary and secondary)
Strongly affects interference dynamic need to monitor/adapt, etc.Packet-data or not (primary)
Packet-data usually more robust.Simplex vs. duplex (primary)
Duplex usually implies feedback channel: ability to adapt to changing situation in terms of interference or channel quality.
Analogue vs. digital (primary). Increasingly rarely a concern nowadays, but usually digital is more
robust.Selection of, or scope for variation of base–level primary
characteristics to mitigate interference, e.g., even simplex could be more robust if the coding rate were higher.
COST-TERRA STSMs (Arturo Basaure, Aalto University, visiting KCL in May 2013 and April 2014.
Analytically and through simulation assess the effects of changes in rules (e.g., TV white space) on the primary, and map to means for compensating the primary for the change in performance, investigate rules for different scenarios (e.g., different types of primary/secondary systems).
Simulation system been created, and parameters/scenarios changed to gauge effects.
Assessment of the Concept
Assessment of the ConceptPrimary users: LTE-like
FDD networkSecondary users: P2P
communicationPerformance for primary
users connected to the ”central” (pink) base station in the above assessed
Performance of secondary users and achievement for the spectrum as a whole also assessed
Assessment of the ConceptFCC Rules: Effects on SINRs and total number of supported
users of changing the distance moved after which secondaries must check again with the geolocation database whether they are allowed to transmit (e.g., useful for vehicular scenarios).
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SIN
R (
ave
rag
e va
lues
)
Primary base station power (dBm)
primary SINR (100m)secondary SINR (100m)primary SINR (200m)secondary SINR (200 m)primary SINR (300m)secondary SINR (300m)
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dBm
Total number of users
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Primary base station power (dBm)
Assessment of the Concept - ProfitsUtility functions: mapping SINR to value
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p(SINR)
SINR (dBm)
User utility functions
real time
not real time
strict real time
Assessment of the Concept - Profits
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Profits (USD)
BS transmission power (dBm)
A. Real-time primary / not real-time secondary *
Rp
Rs
Rp + Rs - C
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Rp + Rs
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Profits (USD)
BS transmission power (dBm)
B. Not real-time primary / real-time secondary *
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Profits (USD)
BS transmission power (dBm)
C. Real-time primary and secondary *
Rp
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Rp + Rs - C
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Rp + Rs
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Profits (USD)
leasing distance (m)
D. Strict real-time primary / not real-time secondary **
primary profits
secondary profits
total profits
Assessment of the Concept - Profits
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100 200 300
Profits (USD)
leasing distance (m)
D. Strict real-time primary / not real-time secondary **
primary profits
secondary profits
total profits
Primary ~70 USD loss
Secondary ~150 USD gain – can more than
compensate primary and still make very healthy
profit
Increase in value of spectrum
Primary selecting from many possible licenses as it would require, embodied in a well-defined/automated mechanism. Incentive scaling to primary based on implied interference.
LSA implies that “secondary” is licensed, Pluralistic Licensing implies no license for secondary – simpler/quicker to implement.Although there are numerous definitions/understandings of
ASA/LSA, the direction seems to be toward LSA not including “cognitive” approaches—PL opportunistic access is as flexible as primary would like so does include option of such approaches.
Could lead to very spatially/temporally dynamic primary license situation – should be twinned with database that secondary will check for rules in area. This could be extension of TVWS geolocation database.
What’s New? –And Implications
We argue that “pluralistic licensing” should become the de facto form of license awarded in newly designated bands.
Should also be offered to the primary as a licensing option in existing bands in cases where interference to legacy devices that might exist in the band can be avoided.
Under such an approach, opportunistic secondary spectrum access can be realised today.
Our Suggestion
Conclusion
Increased spectrum sharing is necessary, e.g., to satisfy future capacity demands.
Current licensing schemes cannot sufficiently realise spectrum sharing and associated facilitating technologies.There is a need for novel licensing schemes.
There is considerable progress to these ends but further work needed in a number of areas.
Have presented some of the key developments here, also our proposal for “Pluralistic Licensing”.
Numerous concerns must be addressed, e.g., fairness to incumbents of spectrum sharing (multi-faceted problem), motivations for existing and new stakeholders, etc.
Conclusion
AcknowledgmentsThis work has been prepared in the framework of
and supported by COST IC0905 “TERRA”, www.cost-terra.org, and has also been supported by the ICT-ACROPOLIS Network of Excellence, FP7 project number 257626, www.ict-acropolis.eu, and ICT-SOLDER, FP7 project number 619687, www.ict-solder.eu
Many thanks to other contributors to the Pluralistic Licensing concept: Keith Nolan, Luca De Nardis, Arturas Medeisis, Peter Anker , Leo Fulvio Minervini, John Sydor, Marja Matinmikko, Fernando Velez, Vania Goncalves, Raul Chavez-Santiago (list not exhaustive)