(19)
(11)EP 2 727 260 B1

(12)EUROPEAN PATENT SPECIFICATION

(45)Mention of the grant of the patent:
20.11.2019 Bulletin 2019/47

(21)Application number: 12730774.2

(22)Date of filing:  26.06.2012
(51)International Patent Classification (IPC): 
H04B 7/185(2006.01)
(86)International application number:
PCT/US2012/044266
(87)International publication number:
WO 2013/003382 (03.01.2013 Gazette  2013/01)

(54)

SPECTRUM SHARING BETWEEN AN AIRCRAFT-BASED AIR-TO-GROUND COMMUNICATION SYSTEM AND EXISTING GEOSTATIONARY SATELLITE SERVICES

GEMEINSAME BENUTZUNG DES FREQUENZSPEKTRUMS DURCH EIN FLUGZEUG - BODEN KOMMUNIKATIONSSYSTEM UND EXISTIERENDE GEOSTATIONÄREN SATELLITEN DIENSTE

RÉUTILISATION DE SPECTRE PAR UN SYSTEME DE COMMUNICATION ENTRE AERONEF ET DES STATIONS AU SOL ET UN SYSTÈME EXISTANT DE SATELLITE GÉOSTATIONNAIRE


(84)Designated Contracting States:
AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

(30)Priority: 29.06.2011 US 201113172539

(43)Date of publication of application:
07.05.2014 Bulletin 2014/19

(73)Proprietor: Gogo LLC
Itasca, IL 60143 (US)

(72)Inventors:
  • CRUZ, Joseph M.
    Naperville, Illinois 60565 (US)
  • WALSH, Patrick J.
    Naperville, Illinois 60564 (US)
  • TOBIN, Joseph A.
    Chicago, Illinois 60630 (US)
  • JOYCE, Tim
    Naperville, Illinois 60540 (US)
  • LIU, Yong
    Schaumburg, Illinois 60194 (US)
  • CHARI, Anand K.
    Bartlett, Illinois 60103 (US)
  • KOSTANIC, Ivica
    Palm Bay, Florida 32901 (US)
  • SAROKA, Harold G.
    Ashburn, Virginia 20147 (US)

(74)Representative: Haupt, Christian et al
Bardehle Pagenberg Partnerschaft mbB Patentanwälte, Rechtsanwälte Prinzregentenplatz 7
81675 München
81675 München (DE)


(56)References cited: : 
US-A1- 2006 199 532
US-B1- 6 567 052
US-A1- 2008 274 734
  
  • MASOUD MOHEBBI NIA ET AL: "High altitude platform system(HAPS) and co-existence with fixed satellite service(FSS) in frequency range 5850 7075 MHz", WIRELESS COMMUNICATION, VEHICULAR TECHNOLOGY, INFORMATION THEORY AND AEROSPACE&ELECTRONIC SYSTEMS TECHNOLOGY (WIRELESS VITAE), 2011 2ND INTERNATIONAL CONFERENCE ON, IEEE, 28 February 2011 (2011-02-28), pages 1-6, XP031998300, DOI: 10.1109/WIRELESSVITAE.2011.5940833 ISBN: 978-1-4577-0786-5
  
Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention).


Description

FIELD OF THE INVENTION



[0001] This invention relates to Air-To-Ground (ATG) communications and, in particular, to a communication system that provides communication devices, which are served by a communication network located on an aircraft, with high speed Air-To-Ground communications service by the reuse of the radio frequency spectrum presently used by Geostationary Satellite Services extant in the volume of space in which the aircraft operates.

BACKGROUND OF THE INVENTION



[0002] It is a problem in the field of Air-To-Ground (ATG) communications, such as between aircraft and ATG ground stations, to provide sufficient bandwidth to carry the communications between the communication devices, which are served by a communication network (wired or wireless) located on the aircraft, and ATG ground stations which are connected to terrestrial communication networks. The collection of ATG ground stations used for this purpose implement a traditional cellular network, with each ATG ground station consisting of a "cell site." There are limited choices of spectrum which are available for this purpose, which choices are also limited by the ability to implement the corresponding radio frequency antennas on the aircraft.

[0003] The typical ATG cellular communications network consists of a number of terrestrial (ground) ATG base stations, each of which provides a radio frequency coverage area in a predetermined volume of space, radially arranged around the cell site transmitting and receiving antennas. This terrestrial base station uses antenna patterns which are less sensitive to the reception of ground-originating or ground-reflected signals and which antenna patterns are primarily focused on the area between the horizon and zenith. The terrestrial base stations are geographically distributed, generally following a typical cellular communications network layout. Terrestrial base stations can also be co-located near airports to enable network coverage when aircraft are on the ground; in this case, the antenna patterns are optimized for terrestrially-located aircraft. The boundaries of the coverage area of each terrestrial base station are substantially contiguous with that of neighboring sites so that the composite coverage of all of the terrestrial base stations in the ATG cellular communications network generally provides coverage over the targeted area. Terrestrial base stations may provide either a single omni-cell of coverage using transceiver(s) associated with a single transmit-and-receive antenna system or multiple sectors within the area of coverage of the site, each with associated transceivers and the associated transmit-and-receive antennas. The advantage of the latter arrangement, with multiple sectors per terrestrial base station, is to allow provision of increased call and data traffic handling capacity in the coverage area of that terrestrial base station.

[0004] The present radio frequency spectrum which is available for this purpose limits the total available traffic handling capacity in any single cell. Thus, the radio frequency communications link between the aircraft and the terrestrial base stations of the ATG cellular communications network has limited capacity and, as passengers utilize the aircraft network for Internet browsing and broadband file downloads, the channel capacity becomes exhausted before the demand is served in its entirety. More advantageous spectrum choices are presently unavailable, because they are dedicated for pre-existing uses, such as satellite communications.

[0005] US 2006/0199532 A1 discloses an aeronautical vehicle for use in a first aeronautical communication system to allow communication to and from a land-based station, wherein the land-based station transmits communications using a first low frequency band and receives communications using a second low frequency band in accordance with a second aeronautical communication system. In the first aeronautical communication system, the aeronautical vehicle transmits communications using the first low frequency band and receives communications using the second low frequency band.

[0006] Further prior art is disclosed in Masoud Mohebbi Nia et al. "High altitude platform system(HAPS) and co-existence with fixed satellite service(FSS) in frequency range 5850 7075 MHz", US 6,567,052 B2 and US 2008/274734 A1.

BRIEF SUMMARY OF THE INVENTION



[0007] The above-described problems are solved and a technical advance achieved in the field by the present Spectrum Sharing Between An Aircraft-Based Air-To-Ground Communication System And Existing Geostationary Satellite Services (termed "Spectrum Sharing System" herein) which implements spectrum reuse between aircraft-based Air-To-Ground (ATG) communication systems and Geostationary Satellite Service systems. This is accomplished by managing the radio frequency transmissions in the volume of space in which the aircraft operates, with interference between the Spectrum Sharing System and the Geostationary Satellite Service system being reduced by implementing reversed uplink and downlink radio frequency paths in the common spectrum. The Spectrum Sharing System also avoids interfering with Geostationary Satellite Services' earth stations which are pointed towards the satellites' orbital arc by relying upon a combination of the earth stations' highly directive antenna patterns and the Spectrum Sharing System ground station antenna pattern, and to avoid interfering with satellites in their orbital arc by assuring that power levels radiated in that direction by the Spectrum Sharing System ground stations are below the level that would create interference.

[0008] The present Spectrum Sharing System thereby provides increased bandwidth to provide communication devices, which are served by a communication network located on an aircraft, with high speed Air-To-Ground communications service, since the selected frequencies provide greater bandwidth than those presently in use in ATG communications or can be used to supplement the ATG frequencies presently in use. Interference between the Spectrum Sharing System and the Geostationary Satellite Service system is reduced by implementing reversed uplink and downlink radio frequency paths in the common spectrum. Furthermore, one of the conditions for mitigation of interference between the two systems is that the transmission of the Spectrum Sharing System ground station is outside of the main beams of the Geostationary Satellite Service earth station antennas. This means that, in the Northern Hemisphere, the Spectrum Sharing System ground station needs to be transmitting in a southerly direction into the back lobe of the earth station antenna of the Geostationary Satellite Service system, which is transmitting in a southerly direction toward the Geostationary satellites; and in the Southern Hemisphere, the Spectrum Sharing System ground station needs to be transmitting in the northerly direction into the back lobe of the earth station antenna of the Geostationary Satellite Service system, which is transmitting in a northerly direction toward the Geostationary satellites.

BRIEF DESCRIPTION OF THE DRAWINGS



[0009] 

Figure 1 illustrates a graphic representation of the radio frequency spectrum sharing plan, between Air-To-Ground systems and satellite based systems, which is implemented by the present Spectrum Sharing System;

Figure 2 illustrates, in graphical form, the limit on the aircraft transmit power spectral density in dBm [the power ratio in decibels (dB) of the measured power referenced to one milliwatt (mW)] per 1 MHz (megahertz) of allocated spectrum for the present Spectrum Sharing System, where the power is charted as a function of number of aircraft and desired level of protection for the geo-stationary satellite receivers;

Figure 3 illustrates, in graphical form, the portion of a geostationary arc visible from the location of an earth station;

Figure 4 illustrates, in graphical form, the required conditions for Air-To-Ground transmission outside of the main lobe of earth station antennas;

Figure 5 illustrates the orientation of Shared Spectrum System ground stations and aircraft in relation to Geostationary Satellite Service earth stations; and

Figure 6 illustrates the antenna pointing angle from the Geostationary Satellite Service system is in a southerly direction, ranging from a low azimuth angle for Geostationary Satellite Service earth stations in the northern extent of the coverage area to a high azimuth angle for Geostationary Satellite Service earth stations in the southern extent of the coverage area.


DETAILED DESCRIPTION OF THE INVENTION



[0010] As shown in Figure 5, a satellite 501 in a geostationary orbit appears to be in a fixed position to an earth-based observer. A geostationary satellite 501 revolves around the earth at a constant speed once per day over the equator, thus matching the speed of rotation of the earth and appearing stationary relative to any point on the earth's surface. The geostationary orbit is useful for communications applications because earth station antennas 511, 512, which must be directed toward satellite 501, can operate effectively without the need for expensive equipment to track the satellite's motion. Since geostationary satellites are constrained to operate above the equator, a geostationary satellite appears low on the horizon to the earth station antennas when i) earth stations are near the easternmost or westernmost coverage limits of a satellite; or ii) when earth stations are at high latitudes. For most earth stations operating within the continental US, the geostationary satellite is 20° to 50° above the horizon; and the beam width of antennas is sufficiently narrow (on the order of 2° or less) to avoid ground reflections and interference between satellites.

Radio Frequency Spectrum Sharing Plan



[0011] Figure 1 illustrates a graphic representation of an illustrative embodiment of the radio frequency spectrum sharing plan, between the present Spectrum Sharing System 11 and Geostationary Satellite Service system 13, to provide communications services to communication devices (not shown) which are located onboard aircraft 12. In the present Spectrum Sharing System 11, uplink transmissions from Spectrum Sharing System ground stations 11G to aircraft 12 use an existing satellite downlink frequency band F1 (and optionally the existing satellite uplink frequency band F2 and optionally the existing ATG frequency band), while downlink transmissions from aircraft 12 to Spectrum Sharing System ground stations 11G use an existing satellite uplink frequency band F2 (and optionally the existing ATG frequency band). The two systems (Spectrum Sharing System 11 and Geostationary Satellite Service system 13) are co-spectrum, and there exists a possibility for mutual interference which may be in both the uplink and downlink directions. There are four possibilities for interference:
  1. 1. From the Spectrum Sharing System Aircraft transmitter (not shown, but located in aircraft 12) to the Geostationary Satellite Service system satellite receiver;
  2. 2. From the Spectrum Sharing System ground station transmitter to the Geostationary Satellite Service system earth station receiver;
  3. 3. From the Geostationary Satellite Service system earth station transmitter to the Spectrum Sharing System ground station receiver; and
  4. 4. From the Geostationary Satellite Service system satellite transmitter to the Spectrum Sharing System Aircraft receiver (not shown, but located in aircraft 12).


[0012] Interference from the Spectrum Sharing System 11 to the Geostationary Satellite Service system 13 is more significant than the interference in the opposite direction due to the differences in signal power and the highly directional antenna patterns used in the Geostationary Satellite Service system 13. There are two primary cases of this interference between Spectrum Sharing System 11 and Geostationary Satellite Service system 13 as is illustrated in Figure 1. Case 1 illustrated in Figure 1 is interference from the Spectrum Sharing System aircraft transmitter at frequency F2 to the satellite receiver 13 of the Geostationary Satellite Service system 13, and Case 2 illustrated in Figure 1 is interference from Spectrum Sharing System ground station 11G transmitter at frequency F1 to the Geostationary Satellite Services earth station 13G receiver.

Interference Between Spectrum Sharing System And The Geostationary Satellite Service



[0013] The interference in Case 1, where the aircraft radio frequency transmissions on frequency F2 interfere with the satellite received radio frequency signals, is relatively low. On the ground, Geostationary Satellite Service signals on frequency F1 are extremely weak unless received by an accurately pointed high gain antenna, such as that used by the earth station 13G of the Geostationary Satellite Service system 13. Geostationary Satellite Service earth station antennas are usually high gain antennas that radiate only through a very narrow beam upwardly directed toward the satellite 14 with which the Geostationary Satellite Service earth station 13G communicates. With a minimum precaution in the location of the Spectrum Sharing System ground stations 11G, this interference can be easily avoided.

[0014] Figure 5 illustrates the orientation (but not drawn to scale) of a plurality of Shared Spectrum System ground stations 531-533 (which are but a few of those that are necessary to provide complete coverage of the service area which consists of the region of space 500 between the earth surface and the maximum altitude at which the aircraft are operational) and aircraft 551-553 in relation to Geostationary Satellite Service geo-synchronous satellites 500 and earth stations 511-512. As can be seen from this figure, the antenna beam 521-522 for the Geostationary Satellite Service earth station antennas 511-512 is narrow in extent and upwardly directed at the orbital arc of the selected geosynchronous satellites 500 located above the equator. The antenna pointing angle from the Geostationary Satellite Service system 13 is in a southerly direction, ranging from a low azimuth angle for earth stations 512 in the northern extent of the coverage area to a high azimuth angle for earth stations 511 in the southern extent of the coverage area, as illustrated in Figure 6. In contrast, the Shared Spectrum System antenna beams 541-543, while also upwardly pointing and generally pointing towards just above the horizon, are broad in extent. The primary interference mode constitutes the Shared Spectrum System antenna beams 541-543 being received by the Geostationary Satellite Service earth station 511-512 antennas. Therefore, radio frequency transmission management requires:
  • "Southerly" pointing of the Spectrum Sharing System ground station antennas for signals at low elevation angles, with any northern facing signals at angles well above the horizon. This way, the Spectrum Sharing System ground station transmission is outside of the main beams for the Fixed Satellite Service earth station receiver antennas. The limits of the coverage of the Spectrum Sharing System antennas at any particular latitude are governed by the range of azimuth angles to the orbital arc, as illustrated in Figure 5, with a small additional allowance for the maximum beamwidth of the earth station receive antennas.
  • To maintain low power spectral density on the Spectrum Sharing System ground station transmission, the signal may need to be spread over a large portion of spectrum. Fortunately, several satellites bands provide hundreds of MHz of spectrum, which is sufficient to reduce spectral density to sufficiently low levels while maintaining high data rates from the ground to the aircraft.


[0015] From the interference mitigation standpoint, use of antennas with highly discriminating patterns on both ends of the Spectrum Sharing System spectrum would be highly beneficial. Additional techniques that may be used for interference mitigation are:
  1. 1. Placement of the Spectrum Sharing System ground stations;
  2. 2. Antenna patterns of the Spectrum Sharing System ground stations, including beam forming and beam steering;
  3. 3. Signal spreading;
  4. 4. Power control; and
  5. 5. Active interference cancelation in case of beam steering.

Evaluation Of The Ground Station Transmission To Earth Station Receiver



[0016] As an example, when viewed from the continental US, the orbit of a geostationary satellite is in a southerly direction. All of the Geostationary Satellite Service earth station antennas, therefore, are pointing towards the south. Depending on the latitude of the earth station, only a portion of the geostationary arc of the satellite is visible. The situation is illustrated in Figure 3. For any given geographical location of the earth station, there are two longitudes that limit the visible portion of the geostationary arc, which are labeled as lE and lw . Therefore, the antenna of the earth station always points to some location on the visible portion of this geostationary arc. As the latitude of the earth station increases towards north, the portion of the visible arc becomes smaller. For earth stations that are above ∼80° north, the geostationary orbit is not visible.

[0017] Consider an earth station at the latitude/longitude location given by a pair of coordinates (LES,lES). Coordinate LES is the earth station latitude, while lES is the earth station longitude. Using simple geometry, one can easily demonstrate the following relationships:







where



[0018] Quantities AZE and AZW are azimuth angles from the earth station towards far east and far west points on the visible portion of the geostationary arc. These two angles provide maximum theoretical range of directions where the earth station antenna may point. In practical scenarios, the range is always narrower than what is provided by equations (3) and (4).

[0019] As an illustration, Table 1 provides values for lE, lW, AZE, and AZW for two earth stations. The first one is located in Melbourne, Florida, while the second one is in Chicago, Illinois. In the Melbourne area, the azimuth for the earth station antennas must fall within the range of from 95.51° to 273.49°. For the Chicago earth stations, the pointing range extends from 99.33° to 269.67°.
Table 1. Geostationary Satellite visible from two locations in the continental US
 Melbourne, FloridaChicago, Illinois
Latitude (deg) 28.0628 41.9978
Longitude (deg) 80.6231 87.6831
lE (deg, W) 2.21 11.48
lW (deg, W) 159.04 163.89
Length of the arc (deg) 78.42 76.21
Azimuth to far east point AZE (deg) 95.51 99.33
Azimuth to far west point AZW (deg) 273.49 269.67


[0020] Referring back to the radio frequency reuse scenario presented in Figure 1, it is evident that one of the conditions for mitigation of interference between the two systems is that the radio frequency transmission of the Spectrum Sharing System ground station is outside of the main beams of the earth station antennas. This means that the Spectrum Sharing System ground station needs to be transmitting towards the south within the range of azimuth angles as specified by equations (3) and (4) (with small additional reductions as required to avoid the beamwidth of the earth station antennas). This way, the signal from the Spectrum Sharing System ground stations is in the back lobe of the Geostationary Satellite Service earth station antenna. Figure 4 illustrates, in graphical form, the required conditions for the Spectrum Sharing System uplink transmission outside of the main lobe of the Geostationary Satellite Service earth station antennas.

[0021] The power spectrum density of the interference from the Spectrum Sharing System ground station transmission at the back lobe of the earth station antenna may be calculated as:



[0022] One may assume that the impact of the Spectrum Sharing System ground station transmission becomes negligible when the SI in equation (6) falls below the noise floor by a certain threshold. That is:



[0023] Table 2 is generated using equation (7) and assuming TdB = 3dB. The table specifies the maximum Effective Isotropic Radiated Power (EiRP) per MHz allowed for the ground-to-air transmission. The use of the table is illustrated through a following simple example.

[0024] Consider a Spectrum Sharing System ground station in a location that is 20 km away from the closest Geostationary Satellite Service earth station. The allowed ground station power spectrum density is 23dBm/MHz (i.e., 200mW/MHz). Assuming the Spectrum Sharing System uplink operation is 20MHz of the spectrum, the overall EiRP is 36.04dBm (4W).
Table 2. Limit on the uplink EiRP in dBm/MHz(*)
d [km]Path loss [dB]EiRP/W [dBm/MHz]EiRP [dBm]EiRP [W]
1 113.99 -2.99 10.02 0.01
5 127.97 10.99 24.00 0.25
10 133.99 17.01 30.02 1.00
15 137.51 20.53 33.54 2.26
20 140.01 23.03 36.04 4.02
25 141.95 24.97 37.98 6.28
30 143.53 26.55 39.56 9.04
35 144.87 27.89 40.90 12.31
40 146.03 29.05 42.06 16.08
(*) The EiRP values are calculated assuming 20MHz channel


[0025] Based on Table 2, the allowed power spectral density for Spectrum Sharing System uplink transmission is relatively low. The table assumes that there is no additional attenuation from the back lobe of the earth station antennas. Also, the table is derived assuming no discrimination from the Spectrum Sharing System ground station antenna. In the practical implementation, these additional factors should be evaluated on the basis of required data rates and Spectrum Sharing System cell site link budgets.

[0026] Figure 4 illustrates, in graphical form, the required conditions for Spectrum Sharing System uplink transmissions to be outside of the main lobe of the Geostationary Satellite Service earth station antennas. In particular, Geostationary Satellite Service earth stations 421-436 are shown with their respective antenna beams pointing toward satellites 411-414 of Figure 4. For the Spectrum Sharing System ground stations 401-408 not to transmit into the receiver antennas at the Geostationary Satellite Service earth stations 421-436, their antenna beams should be oriented as shown in Figure 4 to prevent the near-earth surface portion of the beam (i.e. the southern portion of the beam) from being received by the main lobe of the Geostationary Satellite Service earth stations 421-436. This is not unduly limiting, since the antenna pattern generated by the Shared Spectrum System antennas are broad three-dimensional shapes and can be managed to avoid the near-ground portions of the pattern in the direction of any nearby Geostationary Satellite Service earth stations 421-436 that are generally north of the ground stations. This does not affect the upwardly pointing segment of the antenna pattern from the Shared Spectrum System antennas.

Evaluation Of The Interference From Aircraft-Based Transmissions To The Satellite Receiver



[0027] From the standpoint of the satellite receiver, the energy transmitted from the Spectrum Sharing System aircraft adds to the noise temperature of the satellite receiver antenna. The satellite receiver antenna is pointing toward the earth, which has a nominal noise temperature of 290K. Therefore, as long as the power spectrum density produced by the Spectrum Sharing System aircraft transmission is significantly smaller than the power spectrum density of the thermal noise generated by the earth's radiation, the impact of the spectrum sharing is negligible. The power spectral density of the Spectrum Sharing System aircraft transmission depends on the EiRP of the aircraft, the bandwidth of the Spectrum Sharing System service, and the number of aircraft that are operating at any given time within the main beam of the satellite antenna.

[0028] The power spectral density of the thermal noise received by the satellite antenna may be calculated as:



[0029] The power spectral density of the interference to the satellite receiver that is caused by the transmission from the Spectrum Sharing System aircraft may be estimated as:



[0030] Where n is the number of aircraft within the main beam of the satellite antenna, SA is the radiated power spectral density of a single aircraft and the Free Space Path Loss (FSPL) in the linear domain.

[0031] By converting equation (9) into log domain, one obtains:



[0032] Let TdB be a threshold value that specifies the difference between the power spectral densities of thermal noise and the interference caused by operating Spectrum Sharing System aircraft. In other words:



[0033] By combining equations (10) and (11), one obtains the limit on transmit power spectrum density of a single aircraft:



[0034] Equation (12) is used to generate the family of curves presented in Figure 2 which illustrates, in graphical form, the limit on the aircraft transmit power spectral density in dBm per 1 MHz of allocated spectrum for the present Spectrum Sharing System.

Use Of The Curves In Figure 2 Is Illustrated Through A Simple Example



[0035] Consider a case when the Spectrum Sharing System is operating on 1,000 aircraft within the volume of space covered by the satellite receiver antenna. Assume that the protection threshold is set to Tadd = 20dB, and that all of the aircraft are in the main beam of the satellite receiver antenna. According to Figure 2, the transmission of each aircraft has a power spectral density limit of 43dBm/MHz (20 Watts in 1MHz bandwidth).

[0036] One point to note is that the presented analysis is on the worst case side. There are additional factors that would reduce the interference from the Spectrum Sharing System aircraft to the satellite receiver. Some of those factors, which were neglected in the analysis, may be listed as follows:
  1. 1. The analysis assumes that all of the aircraft are transmitting with the maximum power. In operational scenarios, the transmission of the aircraft is under power control and is always below the maximum value.
  2. 2. The analysis assumes that the EiRP of the aircraft is the same towards the serving cells on the ground and towards the satellite antenna. In practical implementation, it is reasonable to assume that the aircraft antenna directs most of the energy towards the ground, and the amount of radiation towards the sky would be significantly lower.
Only Free Space Path Losses are considered. In a practical scenario, additional losses due to atmospheric phenomena add to the attenuation of the aircraft-generated signal.

Summary



[0037] Spectrum sharing between the Spectrum Sharing System and the Geostationary Satellite Service is possible. However, to make the sharing technically feasible, careful management of the interference between the Spectrum Sharing System ground station and the Geostationary Satellite Service earth station receiver side is required.


Claims

1. A system for providing wireless communication services to communication devices that are located in one or more aircraft (12) that are operational in a selected coverage area, wherein at least one geostationary satellite communication system is operational in the selected coverage area and uses a plurality of earth stations (421-435,511,512), each of which transmits a respective first beam (521-522) that is directed upward at an orbital arc of a geostationary satellite
(14,501) constrained to operate above the equator of the earth, and each of which uses the respective first beam to transmit radio frequency signals to the geostationary satellite at a first radio frequency (F2) and receive radio frequency signals from the geostationary satellite at a second radio frequency (F1), the system comprising:

at least one ground station (11G,531,532,533) for creating a radio frequency coverage area that provides radio frequency links to the one or more aircraft (12) that are operational in the radio frequency coverage area, comprising:

a transmitter that generates a radio frequency signal at the second radio frequency (F1) for transmission to the one or more aircraft (12); and

an antenna (531-533) that produces a second beam (541-543) of the radio frequency signal generated at the second radio frequency (F1),

characterized in that the second beam (401-408, 541-543) is broader in extent than the respective first beam and is directed upward outside the main lobes of the earth stations such that the second beam substantially fails to radiate into any respective first beam (521-522) transmitted by the earth stations (421-435, 511-512) of the geostationary satellite communication system.


 
2. The system for providing wireless communication services of claim 1 further comprising:
wherein the one or more aircraft (12) use the first radio frequency (f2) to transmit radio frequency signals to the at least one ground station (11G).
 
3. The system for providing wireless communication services of claim 1 further comprising:
wherein the antenna (531-533) of the at least one ground station (11G) produces the second beam (541-543) that is directed upward, wherein the second beam is managed to avoid near-ground portions in the direction of any nearby earth stations (421-435, 511-512).
 
4. The system for providing wireless communication services of claim 2 wherein the at least one ground station (11G) comprises:
a receiver (11G) which operates at the first radio frequency (F2) to receive radio frequency signals transmitted from the one or more aircraft (12) to the at least one ground station (11G).
 
5. The system for providing wireless communication services of claim 1 further comprising:
wherein each at least one ground station (11G) is located at sites which are outside of a path of the respective first beam (521-522).
 
6. A method for providing wireless communication services to wireless communication devices that are located in one or more aircraft (12) that are operational in a selected coverage area, wherein at least one geostationary satellite communication system is operational in the selected coverage area and uses a plurality of earth stations (421-435,511,512), each of which transmit a respective first beam (521-522) that is directed upward at an orbital arc of a geostationary satellite constrained to operate above the equator of the earth, and each of which uses the respective first beam to transmit radio frequency signals to the geostationary satellite (14) at a first radio frequency (F2) and receive radio frequency signals from the geostationary satellite (14) at a second radio frequency (F1), the method comprising:
operating at least one ground station (11G, 531,532,533) for creating a radio frequency coverage area that provides radio frequency links to the one or more aircraft (12) that are operational in the radio frequency coverage area, comprising:

generating a radio frequency signal at the second radio frequency (F1) for transmission to the one or more aircraft (12); and

operating an antenna (531-533) to produce a second beam (401-408, 541-543) of the radio frequency signal generated at the second radio frequency (F1), characterized in that

the second beam (401-408, 541-543) is broader in extent than the respective first beam and is directed upward outside the main lobes of the earth stations such that the second beam substantially fails to radiate into any respective first beam (521-522) transmitted by the earth stations (421-435, 511-512) of the geostationary satellite communication system.


 
7. The method for providing wireless communication services of claim 6 further comprising:
wherein the one or more aircraft (12) use the first radio frequency (F2) to transmit radio frequency signals to the at least one ground station (11G).
 
8. The method for providing wireless communication services of claim 6 further comprising:
wherein the antenna (531-533) of the at least one ground station (11G) produces a second beam (401-408, 541-543) that is directed upward, wherein the second beam is managed to avoid near-ground portions in the direction of any nearby earth stations (421-435, 511-512).
 
9. The method for providing wireless communication services of claim 6 wherein operating the at least one ground station comprises:
operating a receiver at the first radio frequency (F2) to receive radio frequency signals transmitted from the one or more aircraft (12) to the ground station (11G).
 
10. The method for providing wireless communication services of claim 6 further comprising:
wherein each the ground station (11G) is located at sites which are outside of a path of the respective first beam (521-522).
 


Ansprüche

1. System zum Bereitstellen von drahtlosen Kommunikationsdiensten für Kommunikationsgeräte, welche sich in einem oder mehreren Luftfahrzeugen (12) befinden, welche in einem ausgewählten Abdeckungsgebiet in Betrieb sind, wobei zumindest ein geostationäres Satellitenkommunikationssystem in dem ausgewählten Abdeckungsgebiet in Betrieb ist und eine Vielzahl von Erdstationen (421-435, 511, 512) verwendet, von denen jede einen entsprechenden ersten Strahl (521-522) überträgt, welcher nach oben auf einen orbitalen Bogenabschnitt eines geostationären Satelliten (14, 501) gerichtet ist, der eingeschränkt ist, über dem Erdäquator betrieben zu werden und von denen jede den entsprechenden ersten Strahl verwendet, um Radiofrequenzsignale zu dem geostationären Satelliten auf einer ersten Radiofrequenz (F2) zu übertragen und Radiofrequenzsignale von dem geostationären Satelliten auf einer zweiten Radiofrequenz (F1) zu empfangen, wobei das System aufweist:
Zumindest eine Bodenstation (11G, 531, 532, 533) zum Erzeugen eines Radiofrequenzabdeckungsgebiets, welche Radiofrequenzverbindungen mit dem einen oder den mehreren Luftfahrzeugen (12) bereitstellt, welche in dem Radiofrequenzabdeckungsgebiet in Betrieb sind, aufweisend:

einen Sender, welcher ein Radiofrequenzsignal auf der zweiten Radiofrequenz (F1) zur Übertragung an das eine oder die mehreren Luftfahrzeuge (12) erzeugt; und

eine Antenne (531-533), welche einen zweiten Strahl (541-543) des Radiofrequenzsignals erzeugt, welches auf der zweiten Radiofrequenz (F1) erzeugt wird, dadurch gekennzeichnet, dass

der zweite Strahl (401-408, 541-543) eine breitere Ausdehnung hat als der entsprechende erste Strahl und nach oben gerichtet ist außerhalb der Hauptkeulen der Erdstationen, so dass der zweite Strahl es im Wesentlichen verfehlt, in einen entsprechenden ersten Strahl (521-522) zu strahlen, welcher von den Erdstationen (421-435, 511-512) des geostationären Satellitenkommunikationssystems übertragen wird.


 
2. System zum Bereitstellen von drahtlosen Kommunikationsdiensten nach Anspruch 1, weiter aufweisend:
wobei das eine oder die mehreren Luftfahrzeuge (12) die erste Radiofrequenz (f2) verwenden, um Radiofrequenzsignale an die zumindest eine Bodenstation (11G) zu übertragen.
 
3. System zum Bereitstellen von drahtlosen Kommunikationsdiensten nach Anspruch 1, weiter aufweisend:
wobei die Antenne (531-533) der zumindest einen Bodenstation (11G) den zweiten Strahl (541-543) erzeugt, der nach oben gerichtet ist, wobei der zweite Strahl gesteuert wird, um bodennahe Abschnitte in Richtung jeder nahen Erdstation (421-435, 511-512) zu vermeiden.
 
4. System zum Bereitstellen von drahtlosen Kommunikationsdiensten nach Anspruch 2, wobei die zumindest eine Bodenstation (11G) aufweist:
einen Empfänger (11G), welcher auf der ersten Radiofrequenz (F2) arbeitet, um Radiofrequenzsignale zu empfangen, welche von dem einen oder den mehreren Luftfahrzeugen (12) zu der zumindest einen Bodenstation (11G) übertragen werden.
 
5. System zum Bereitstellen von drahtlosen Kommunikationsdiensten nach Anspruch 1, weiter aufweisend:
wobei sich jede der zumindest einen Bodenstation (11G) an Standorten befindet, welche außerhalb eines Pfads des entsprechenden ersten Strahls (521-522) sind.
 
6. Verfahren zum Bereitstellen von drahtlosen Kommunikationsdiensten für drahtlose Kommunikationsgeräte, welche sich in einem oder mehreren Luftfahrzeugen (12) befinden, welche in einem ausgewählten Abdeckungsgebiet in Betrieb sind, wobei zumindest ein geostationäres Satellitenkommunikationssystem in dem ausgewählten Abdeckungsgebiet in Betrieb ist und eine Vielzahl von Erdstationen (421-435, 511, 512) verwendet, von denen jede einen entsprechenden ersten Strahl (521-522) überträgt, welcher nach oben auf einen orbitalen Bogenabschnitt eines geostationären Satelliten gerichtet ist, der eingeschränkt ist, über dem Erdäquator betrieben zu werden und von denen jede den entsprechenden ersten Strahl verwendet, um Radiofrequenzsignale zu dem geostationären Satelliten (14) auf einer ersten Radiofrequenz (F2) zu übertragen und Signale von dem geostationären Satelliten (14) auf einer zweiten Radiofrequenz (F1) zu empfangen, wobei das Verfahren aufweist:
Betreiben zumindest einer Bodenstation (11G, 531, 532, 533) zum Erzeugen eines Radiofrequenzabdeckungsgebiets, welches Radiofrequenzverbindungen mit dem einen oder den mehreren Luftfahrzeugen (12) bereitstellt, welche in dem Radiofrequenzabdeckungsgebiet in Betrieb sind, aufweisend:

Erzeugen eines Radiofrequenzsignals auf der zweiten Radiofrequenz (F1) zur Übertragung an das eine oder die mehreren Luftfahrzeuge (12); und

Betreiben einer Antenne (531-533), um einen zweiten Strahl (401-408, 541-543) des Radiofrequenzsignals zu erzeugen, welches auf der zweiten Radiofrequenz (F1) erzeugt wird, dadurch gekennzeichnet, dass

der zweite Strahl (401-408, 541-543) eine breitere Ausdehnung hat als der entsprechende erste Strahl und nach oben gerichtet ist außerhalb der Hauptkeulen der Erdstationen, so dass der zweite Strahl es im Wesentlichen verfehlt, in einen entsprechenden ersten Strahl (521-522) zu strahlen, welcher von den Erdstationen (421-435, 511-512) des geostationären Satellitenkommunikationssystems übertragen wird.


 
7. Verfahren zum Bereitstellen von drahtlosen Kommunikationsdiensten nach Anspruch 6, weiter aufweisend:
wobei das eine oder die mehreren Luftfahrzeuge (12) die erste Radiofrequenz (f2) verwenden, um Radiofrequenzsignale an die zumindest eine Bodenstation (11G) zu übertragen.
 
8. Verfahren zum Bereitstellen von drahtlosen Kommunikationsdiensten nach Anspruch 6, weiter aufweisend:
wobei die Antenne (531-533) der zumindest einen Bodenstation (11G) einen zweiten Strahl (401-408, 541-543) erzeugt, der nach oben gerichtet ist, wobei der zweite Strahl gesteuert wird, um bodennahe Abschnitte in Richtung jeder nahen Erdstation (421-435, 511-512) zu vermeiden.
 
9. Verfahren zum Bereitstellen von drahtlosen Kommunikationsdiensten nach Anspruch 6, wobei Betreiben der zumindest einen Bodenstation (11G) aufweist:
Betreiben eines Empfängers auf der ersten Radiofrequenz (F2), um Radiofrequenzsignale zu empfangen, welche von dem einen oder den mehreren Luftfahrzeugen (12) zu der Bodenstation (11G) übertragen werden.
 
10. Verfahren zum Bereitstellen von drahtlosen Kommunikationsdiensten nach Anspruch 6, weiter aufweisend:
wobei sich jede der Bodenstation (11G) an Standorten befindet, welche außerhalb eines Pfads des entsprechenden ersten Strahls (521-522) sind.
 


Revendications

1. Un système pour fournir des services de communication sans fil à des dispositifs de communication qui sont situés dans un ou plusieurs aéronefs (12) qui sont opérationnels dans une zone de couverture sélectionnée, dans lequel au moins un système de communication par satellite géostationnaire est opérationnel dans la zone de couverture sélectionnée et utilise une pluralité de stations au sol (421-435, 511, 512), dont chacune émet un premier faisceau respectif (521-522) qui est dirigé vers le haut vers un arc orbital d'un satellite géostationnaire (14, 501) contraint d'opérer au-dessus de l'équateur de la Terre, et dont chacune utilise le premier faisceau respectif pour émettre des signaux à fréquence radio vers le satellite géostationnaire à une première fréquence radio (F2) et recevoir des signaux à fréquence radio du satellite géostationnaire à une seconde fréquence radio (F1), le système comprenant :

au moins une station au sol (11G, 531, 532, 533) pour la création d'une zone de couverture en fréquence radio qui assure des liaisons à fréquence radio vers les un ou plusieurs aéronefs (12) qui sont opérationnels dans la zone de couverture en fréquence radio, comprenant :

un émetteur qui génère un signal à fréquence radio à la seconde fréquence radio (F1) pour émission vers les un ou plusieurs aéronefs (12) ; et

une antenne (531-533) qui produit un second faisceau (541-543) du signal à fréquence radio généré à la seconde fréquence radio (F1),

caractérisé en ce que le second faisceau (401-408, 541-543) a une étendue plus large que le premier faisceau respectif et est dirigé vers le haut en-dehors des lobes principaux des stations au sol de telle sorte que le second faisceau évite substantiellement de rayonner dans tout premier faisceau respectif (521-522) émis par les stations au sol (421-435, 511-512) du système de communication par satellite géostationnaire.


 
2. Le système pour fournir des services de communication sans fil de la revendication 1, comprenant en outre :
les un ou plusieurs aéronefs (12) qui utilisent la première fréquence radio (F2) pour émettre des signaux à fréquence radio vers la au moins une station au sol (11G).
 
3. Le système pour fournir des services de communication sans fil de la revendication 1, comprenant en outre :
l'antenne (531-533) de la au moins une station au sol (11G) qui produit le second faisceau (541-543) qui est dirigé vers le haut, le second faisceau étant géré pour éviter des parties voisines du sol dans la direction de toute station au sol voisine (421-435, 511-512).
 
4. Le système pour fournir des services de communication sans fil de la revendication 2, dans lequel la au moins une station au sol (11G) comprend :
un récepteur (11G) qui opère à la première fréquence radio (F2) pour recevoir des signaux à fréquence radio émis depuis les un ou plusieurs aéronefs (12) vers la au moins une station au sol (11G).
 
5. Le système pour fournir des services de communication sans fil de la revendication 1, comprenant en outre :
chacune des au moins une station au sol (11G) qui est située en un site qui est en-dehors d'un trajet du premier faisceau respectif (521-522).
 
6. Un procédé pour fournir des services de communication sans fil à des dispositifs de communication sans fil qui sont situés dans un ou plusieurs aéronefs (12) qui sont opérationnels dans une zone de couverture sélectionnée, dans lequel au moins un système de communication par satellite géostationnaire est opérationnel dans la zone de couverture sélectionnée et utilise une pluralité de stations au sol (421-435, 511, 512), dont chacune émet un premier faisceau respectif (521-522) qui est dirigé vers le haut vers un arc orbital d'un satellite géostationnaire (14, 501) contraint d'opérer au-dessus de l'équateur de la Terre, et dont chacune utilise le premier faisceau respectif pour émettre des signaux à fréquence radio vers le satellite géostationnaire (14) à une première fréquence radio (F2) et recevoir des signaux à fréquence radio du satellite géostationnaire (14) à une seconde fréquence radio (F1), le procédé comprenant :
la mise en œuvre d'au moins une station au sol (11G, 531, 532, 533) pour la création d'une zone de couverture en fréquence radio qui assure des liaisons à fréquence radio vers les un ou plusieurs aéronefs (12) qui sont opérationnels dans la zone de couverture en fréquence radio, comprenant :

la génération d'un signal à fréquence radio à la seconde fréquence radio (F1) pour émission vers les un ou plusieurs aéronefs (12) ; et

la mise en œuvre d'une antenne (531-533) qui produit un second faisceau (541-543) du signal à fréquence radio généré à la seconde fréquence radio (F1),

caractérisé en ce que le second faisceau (401-408, 541-543) a une étendue plus large que le premier faisceau respectif et est dirigé vers le haut en-dehors des lobes principaux des stations au sol de telle sorte que le second faisceau évite substantiellement de rayonner dans tout premier faisceau respectif (521-522) émis par les stations au sol (421-435, 511-512) du système de communication par satellite géostationnaire.


 
7. Le procédé pour fournir des services de communication sans fil de la revendication 6, comprenant en outre :
les un ou plusieurs aéronefs (12) qui utilisent la première fréquence radio (F2) pour émettre des signaux à fréquence radio vers la au moins une station au sol (11G).
 
8. Le procédé pour fournir des services de communication sans fil de la revendication 6, comprenant en outre :
l'antenne (531-533) de la au moins une station au sol (11G) qui produit le second faisceau (541-543) qui est dirigé vers le haut, le second faisceau étant géré pour éviter des parties voisines du sol dans la direction de toute station au sol voisine (421-435, 511-512).
 
9. Le procédé pour fournir des services de communication sans fil de la revendication 6, dans lequel la mise en œuvre de la au moins une station au sol comprend :
la mise en œuvre d'un récepteur à la première fréquence radio (F2) pour recevoir des signaux à fréquence radio émis depuis les un ou plusieurs aéronefs (12) vers la au moins une station au sol (11G).
 
10. Le procédé pour fournir des services de communication sans fil de la revendication 6, comprenant en outre :
chacune des au moins une station au sol (11G) qui est située en un site qui est en-dehors d'un trajet du premier faisceau respectif (521-522).
 




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Cited references

REFERENCES CITED IN THE DESCRIPTION



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Patent documents cited in the description