SHARING OF SPECTRUM USED BY SATELLITE SYSTEMS

Transcription

1 SHARING OF SPECTRUM USED BY SATELLITE SYSTEMS HOW SATELLITE SYSTEMS SHARE SPECTRUM AMONG THEMSELVES, AND WITH TERRESTRIAL SYSTEMS Jose Albqerqe Chief, Satellite Division FCC May 17, 2017 Jly 20, 2015

2 Sharing Scenarios Sharing Between GSO FSS Satellite Networks (Directional Earth Station Antennas) Sharing Between NGSO FSS Satellite Systems (Directional Earth Station Antennas) Sharing Between GSO or NGSO Satellite Systems (Non-Directional Antennas) Co-Freqency Operation of GSO and NGSO FSS Satellite Systems (Directional Earth Station Antennas) Sharing Between Satellite Systems (Earth-to-Space) and Terrestrial Systems Sharing Between Satellite Systems (Space-to-Earth) and Terrestrial Systems

3 Geostationary Orbit (GSO) Satellites Commnicating with Directional Earth Station Antennas Applicable to most GSO fixed-satellite service (FSS) satellites Space stations are athorized on a first-come-first-served basis and have to accommodate late comers that are at least two degrees apart in the geostationary orbit The two-degree policy, adopted in 1983 and refined in 2015, strikes a balance between maintaining flexibility to early comers and maximizing opportnities to late comers Compatibility of satellite networks with space stations separated by two degrees is ensred by limiting radiation from earth stations toward adjacent satellites and downlink e.i.r.p. density or power-flx density generated by space stations Limits can be exceeded if coordinated with neighboring space stations

4 FCC Two-Degree Policy verss ITU Framework There has been a lot of discssion between the two reglatory regimes, inclding in the comments and reply comments preceding the December 2015 Part 25 Order The ITU framework is generally based on a first-come-firstserved principle, bt differs from the FCC two-degree approach in some key points, e.g. A late-coming ITU filing is accepted even if incompatible with an earlier filing; an FCC application that is incompatible with a license is dismissed nless the incompatibility has been eliminated throgh coordination In the ITU, an earlier filer is expected to accommodate a late comer, bt there is no definition of how mch accommodation is reqired; the FCC rles also allow coordination between the parties, bt, in the absence of an agreement, emission limits associated with the two-degree policy clearly define the rights and obligations of the early comer

5 Non-Geostationary Orbit (NGSO) Satellites Commnicating with Directional Earth Station Antennas Applicable to some NGSO fixed-satellite service (FSS) satellites An application that comports with existing rles and is compatible with previos athorizations and applications will be pt on pblic notice and triggers a processing rond (applications competing for the se of the same freqencies can be sbmitted ntil a specific date) All applications that meet all reqirements in the rles are granted for all the reqested spectrm If two or more space stations of different systems are aligned with an earth station of one of these systems (or within a certain angle, as measred from the earth station), an in-line event occrs and there is potential for interference between the systems involved Dring in-line events, se of the overlapping portions of the spectrm assigned to the systems involved has to be coordinated by the parties; in the absence of a coordination agreement the overlapping spectrm is divided eqally among the parties involved

6 FCC verss ITU Framework The ITU framework is again based on a first-come-first-served principle and the earlier filer is expected to accommodate a late comer, withot a definition of how mch accommodation is reqired The FCC processing rond approach places several applicants on eqal gronds and mandates an eqal split of the overlapping spectrm in the absence of a coordination agreement that addresses the periods of time when there is a potential for interference (this contrasts with the lack of defined operating parameters as a fallback in the ITU environment when there is no agreement between the parties) One challenge in the FCC approach is how to deal with applications that may come in the ftre, after a processing rond has already been condcted These applications have to be considered on a case-by-case basis and options range from, on one extreme, reqiring the new system to protect all previosly filed systems to, on the other extreme, giving the new system the same treatment given to the previosly filed systems

7 NGSO or GSO Satellites Commnicating with Non-Directional Earth Station Antennas In this scenario the rles prescribe a processing rond and, if the available spectrm is not enogh to meet the reqests of all applications that comport with existing rles and are compatible with previos athorizations, spectrm is eqally divided among the applicants (band segmentation) Althogh the crrent Big Leo licensees (Iridim and Globalstar) were athorized before the adoption of the modified processing rond regime in 2003, sharing has been achieved throgh band segmentation (except for 0.95 MHz that are shared between the two licensees)

8 Co-Freqency Operation of NGSO and GSO FSS Satellites Commnicating with Directional Earth Station Antennas In the ITU framework NGSO systems cannot case nacceptable interference to or claim protection from GSO satellite networks In certain portions of C-band, K-band and Ka-band, the ITU has developed eqivalent power flx-density (epfd) limits that, if met by a NGSO FSS system, ensre that this system has flfilled the reqirements of not casing nacceptable interference to GSO FSS satellite networks epfd applicable to NGSO FSS satellite emissions ensre the protection of GSO FSS earth stations epfd applicable to emissions from earth stations of a NGSO FSS system ensre the protection of GSO FSS satellites In the FCC rles there is no widely applicable obligation imposed on NGSO systems, bt the same epfd limits developed by the ITU for portions K-band have been incorporated in the rles (epfd limits applicable to C-band and Kaband freqencies are not in the FCC rles bt have been sed in FCC grants on an ad hoc basis)

9 Exception for the Reqirement of NGSO FSS Systems Having to Protect GSO FSS Networks In the ITU framework NGSO FSS systems and GSO FSS networks have eqal stats in the freqency bands GHz ( ) and GHz ( ) In these freqency bands the ITU first-come-first-served principle applies and, as in the case of GSO satellite networks, the early comer has to accommodate the late comer, with no clear definition of the level of accommodation reqired In the FCC rles, the freqency bands GHz ( ) and GHz ( ) are designated for NGSO FSS se GSO FSS operation in the band GHz can only be athorized on a secondary basis GSO FSS operation in the band GHz can only be athorized on a noninterference-non-protected basis throgh a waiver of the U.S. Table of Freqency Allocations

10 Sharing Between Satellite Systems and Terrestrial Systems (FS & MS): Spectrm Allocated to Earth-to-Space Transmissions (1) Interference is from terrestrial stations to satellite receivers This interference mechanism has been traditionally addressed by limiting e.i.r.p., reqiring directional antennas, and imposing constraints on pointing intended to protect GSO satellites In most sitations, this interference mechanism has not been a concern becase aggregate interference is not significant Aggregation becomes a concern when there is potential for massive terrestrial deployment Some historic examples are: ITU Resoltion on WAS and RLANs in 5 GHz; extensive discssions arond deployment of UWB systems in the U.S. More recently, concerns reappeared in connection with 5G terrestrial deployment (e.g. discssions related to 5G mobile service in GHz) Controlling aggregate interference throgh e.i.r.p. limitations on individal terrestrial stations is challenging (ndly limiting deployment vs. not protecting satellite receivers) Setting a limit for aggregate interference brings the challenge of enforcing this limit

11 Sharing Between Satellite Systems and Terrestrial Systems (FS & MS): Spectrm Allocated to Earth-to-Space Transmissions (2) Interference is from satellite earth stations to terrestrial station receivers If earth stations and terrestrial stations have eqal stats and are individally athorized, a first-come-first-served regime is appropriate and late comers have to show compatibility with early comers throgh coordination triggered when pre-determined interference thresholds are exceeded (e.g. 5,925-6,425 MHz) If earth stations or terrestrial stations can be deployed anywhere (blanket licensed earth stations or terrestrial stations athorized in a given geographic area), the two types of stations cannot have the same stats If terrestrial stations have a higher stats, earth stations can be deployed: with a secondary stats and may have to cease operations in order to protect ftre terrestrial deployments (concerns with widespread deployment and potential difficlties in stopping transmissions from existing sers of the satellite service); or in a way that will preclde terrestrial deployment in very limited areas If earth stations have a higher stats, terrestrial stations might be deployed on an opportnistic basis (concerns with widespread deployment and potential difficlties in dealing with interference to existing sers of the terrestrial service)

12 Sharing Between Satellite Systems and Terrestrial Systems (FS & MS): Spectrm Allocated to Space to-earth Transmissions (1) Interference from terrestrial stations to earth station receivers If earth stations and terrestrial stations have eqal stats and are individally athorized, a first-come-first-served regime is appropriate and late comers have to show compatibility with early comers throgh coordination triggered when pre-determined interference thresholds are exceeded (e.g. 3,700-4,200 MHz) If earth stations or terrestrial stations can be deployed anywhere (blanket licensed earth stations or terrestrial stations athorized in a given geographic area), the two types of stations cannot have the same stats If terrestrial stations have a higher stats, earth stations can be deployed: with a secondary stats and have to operate on a non-protected basis (concerns with widespread deployment and potential difficlties in dealing with interference to existing sers of the satellite service); or in a way that will preclde terrestrial deployment in very limited areas If earth stations have a higher stats, terrestrial stations might be deployed with a secondary stats and may have to cease operations in order to protect ftre earth stations (concerns with widespread deployment and potential difficlties in stopping transmissions from existing sers of the terrestrial service)

13 Sharing Between Satellite Systems and Terrestrial Systems (FS & MS): Spectrm Allocated to Space to-earth Transmissions (2) Interference from satellite transmitters to terrestrial stations receivers This interference mechanism has been traditionally addressed by setting limits to the spectral power flx-density (pfd) that satellite transmissions can generate on the srface of the Earth When applying these pfd limits to NGSO constellations, two isses have to be addressed The pfd generated by a NGSO constellation at any given point on the grond varies with time and in this context it might be appropriate to define a pfd that is exceeded only for a certain percentage of the time rather than a pfd that can never be exceeded (developing an epfd limit may also be an option bt this wold have to be associated with a certain collection of terrestrial station antennas) The crrent FCC and ITU rles establish pfd limits per space station while for NGSO constellations the aggregate pfd shold be limited (crrently only in the freqency band GHz there is a correction factor to take into accont the nmber of satellites in the constellation and even this correction factor is not appropriate for larger constellations)