Source: https://patents.google.com/patent/US20060252368A1/en
Timestamp: 2019-04-24 18:59:23+00:00

Document:
2006-07-28 Assigned to MOBILE SATELLITE VENTURES, LP reassignment MOBILE SATELLITE VENTURES, LP ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: KARABINIS, PETER D.
2008-04-18 Assigned to BANK OF NEW YORK, THE reassignment BANK OF NEW YORK, THE SECURITY AGREEMENT Assignors: MOBILE SATELLITE VENTURES LP, MSV FINANCE CO.
A satellite radiotelephone system can include a space-based component and a plurality of ancillary terrestrial components. The space-based component is configured to provide wireless radiotelephone communications over a satellite radiotelephone frequency band. The plurality of ancillary terrestrial components are configured to terrestrially reuse at least one of the satellite radiotelephone frequencies, at least some of the ancillary terrestrial components terrestrially reusing the at least one of the satellite radiotelephone frequencies in a staggered sectorization. Related methods are also discussed.
This application claims the benefit of priority as a continuation-in-part application from U.S. application Ser. No. 10/353,308 filed Jan. 29, 2003, which claims the benefit of priority from provisional Application No. 60/393,287, filed Jul. 2, 2002, entitled Staggered Sectorization For Terrestrial Reuse Of Satellite Frequencies. U.S. application Ser. No. 10/353,308 also claims the benefit of priority as a continuation-in-part application from application Ser. No. 10/074,097, filed Feb. 12, 2002, entitled Systems and Methods for Terrestrial Reuse of Cellular Satellite Frequency Spectrum which claims the benefit of priority from provisional Application No. 60/322,240, filed Sep. 14, 2001, entitled Systems and Methods For Terrestrial Re-Use of Mobile Satellite Spectrum. U.S. patent application Ser. No. 10/353,308 also claims the benefit of priority as a continuation-in-part application from application Ser. No. 10/180,281, filed Jun. 26, 2002, entitled Spatial Guardbands for Terrestrial Reuse of Satellite Frequencies, which claims priority from Provisional Application No. 60/347,173, filed Jan. 9, 2002, entitled Spatial Guardbands for Terrestrial Reuse of Satellite Frequencies. The present application thus claims the benefit of priority from U.S. application Ser. No. 10/353,308 filed Jan. 29, 2003, from U.S. Application No. 60/393,287 filed Jul. 2, 2002, from U.S. application Ser. No. 10/074,097 filed Feb. 12, 2002, from U.S. Application No. 60/322,240 filed Sep. 14, 2001, from application Ser. No. 10/180,281 filed Jun. 26, 2002, and from Provisional Application No. 60/347,173 filed Jan. 9, 2002. All of these applications are assigned to the assignee of the present application, the disclosures of all of which are hereby incorporated herein by reference in their entirety as if set forth fully herein.
According to some embodiments of the present invention, a satellite radiotelephone system may include a space-based component configured to provide communications using frequencies of a satellite frequency band, and a plurality of ancillary terrestrial components. The plurality of ancillary terrestrial components may be configured to provide communications over a service region using at least one first frequency of the satellite frequency band in a staggered sectorization pattern. Moreover, the space-based component may not provide communications over the service region using the at least one first frequency, and an aggregate power radiated by the plurality of ancillary terrestrial components at the at least one first frequency in any direction may be less than a total power radiated by the plurality of ancillary terrestrial components at the at least one first frequency.
The space-based component may be configured to provide communications over a service region including the plurality of ancillary terrestrial components using at least one second frequency of the satellite frequency band that is different from the at least one first frequency. Moreover, the space-based component may be configured to provide down-link communications over the service region using the at least one second frequency. The space-based component may be configured to provide communications over a second service region not including the plurality of ancillary terrestrial components using the at least one first frequency.
The at least one first frequency may be used by ancillary terrestrial components to provide down-link communications. Each of the plurality of ancillary terrestrial components may include n directional sectors and the at least one first frequency may be used by the plurality of ancillary terrestrial components so that an aggregate radiated power transmitted by the plurality of ancillary terrestrial components at the at least one first frequency in a direction may be limited to approximately 1/n of a total radiated power transmitted by the plurality of ancillary terrestrial components at the at least one first frequency. The at least one first frequency may be further used by radiotelephones to provide up-link communications, and n may be equal to 3. The plurality of ancillary terrestrial components may also include a plurality of frequency reuse clusters, and each frequency reuse cluster may use the at least one first frequency no more than once.
According to some other embodiments of the present invention, a satellite radiotelephone system may include a space-based component that is configured to provide communications using frequencies of a satellite frequency band, and a plurality of ancillary terrestrial components. The plurality of ancillary terrestrial components may include a plurality of frequency reuse clusters. A first frequency reuse cluster may transmit at least one first frequency of the satellite frequency band in a first direction, and a second frequency reuse cluster may transmit the at least one first frequency of the satellite frequency band in a second direction. The space-based component may not provide communications over a service region including the plurality of ancillary terrestrial components using the at least one first frequency and an aggregate power radiated by the plurality of ancillary terrestrial components at the at least one first frequency in any direction may be less than a total power radiated by the plurality of ancillary terrestrial components at the at least one first frequency.
The space-based component may be configured to provide communications over a service region including the plurality of ancillary terrestrial components using at least one second frequency of the satellite frequency band that is different from the at least one first frequency of the satellite frequency band. The space-based component may be configured to provide down-link communications over the service region using the at least one second frequency. The space-based component may be configured to provide communications over a second service region not including the plurality of ancillary terrestrial components, and the space-based component may provide communications over the second service region using the at least one first frequency.
The at least one first frequency may be used by ancillary terrestrial components to provide down-link communications. Moreover, each of at least some of the plurality of ancillary terrestrial components may include n directional sectors and an aggregate radiated power transmitted by the at least some of the plurality of ancillary terrestrial components at the at least one first frequency in a direction may be no greater than approximately 1/n of a total radiated power transmitted by the at least some of the ancillary terrestrial components at the at least one first frequency. More particularly, n may be equal to 3, and/or each frequency reuse cluster may use the at least one first frequency no more than once.
According to some more embodiments of the present invention, a method of operating a satellite radiotelephone system may include providing communications from a space-based component using frequencies of a satellite frequency band. In addition, communications may be provided from a plurality of ancillary terrestrial components over a service region using at least one first frequency of the satellite frequency band in a staggered sectorization pattern. The space-based component may not provide communications over the service region using the at least one first frequency and an aggregate power radiated by the plurality of ancillary terrestrial components at the at least one first frequency in any direction may be less than a total power radiated by the plurality of ancillary terrestrial components at the at least one first frequency.
Providing communications from a space-based component using frequencies of a satellite frequency band may further include providing communications over a service region including the plurality of ancillary terrestrial components using at least one second frequency of the satellite frequency band that is different from the at least one first frequency of the satellite frequency band. Providing communications from a space-based component using frequencies of a satellite frequency band may further include providing down-link communications over the service region using the at least one second frequency. Providing communications from a space-based component using frequencies of a satellite frequency band may further include providing communications over a second service region not including the plurality of ancillary terrestrial components using the at least one first frequency.
The at least one first frequency may be used by ancillary terrestrial components to provide down-link communications. Moreover, each of the plurality of ancillary terrestrial components may include n directional sectors and the at least one first frequency may be transmitted by the plurality of ancillary terrestrial components so that an aggregate radiated power transmitted by the plurality of ancillary terrestrial components at the at least one first frequency in a direction may be no greater than approximately 1/n of a total radiated power transmitted by the plurality of ancillary terrestrial components at the at least one first frequency. The at least one first frequency may be further used by radiotelephones to provide up-link communications. Moreover, n may be equal to 3, and/or the plurality of ancillary terrestrial components may include a plurality of frequency reuse clusters wherein each frequency reuse cluster uses the at least one first frequency no more than once.
According to some additional embodiments of the present invention, a method of operating a satellite radiotelephone system may include providing communications from a space-based component using frequencies of a satellite frequency band. Communications may be provided from a plurality of ancillary terrestrial components including a plurality of frequency reuse clusters. A first frequency reuse cluster may transmit at least one first frequency of the satellite frequency band in a first direction, and a second frequency reuse cluster may transmit the at least one first frequency of the satellite frequency band in a second direction. The space-based component may not provide communications over a service region including the plurality of ancillary terrestrial components using the at least one first frequency and an aggregate power radiated by the plurality of ancillary terrestrial components at the at least one first frequency in any direction may be less than a total power radiated by the plurality of ancillary terrestrial components at the at least one first frequency.
The at least one first frequency may be used by ancillary terrestrial components to provide down-link communications. Each of at least some of the plurality of ancillary terrestrial components may include n directional sectors, and the at least one first frequency may be used by the plurality of frequency reuse clusters so that an aggregate radiated power transmitted by the plurality of frequency reuse clusters at the at least one first frequency in a direction is no greater than approximately 1/n of a total radiated power transmitted by the plurality of frequency reuse clusters at the at least one first frequency. In addition, n may be equal to 3, and/or each frequency reuse cluster may use the at least one first frequency no more than once.
According to yet other embodiments of the present invention, a radiotelephone system may include a plurality of terrestrial components including a plurality of frequency reuse clusters. At least one terrestrial component of each frequency reuse cluster may include a plurality of directional sectors, and at least first and second frequency reuse clusters may provide communications by transmitting at least one first frequency of a satellite frequency band in respective first and second directions. A space-based component may provide communications using frequencies of the satellite frequency band and may refrain from providing communications over a service region that includes the plurality of terrestrial components using the at least one first frequency. In addition, an aggregate power radiated by the plurality of terrestrial components at the at least one first frequency in any direction may be less than a total power radiated by the plurality of ancillary terrestrial components at the at least one first frequency.
The at least one first frequency of the satellite frequency band may be used by terrestrial components to provide down-link communications. Each of at least some of the plurality of terrestrial components may include n directional sectors, and the at least one first frequency of the satellite frequency band may be used so that an aggregate radiated power transmitted by the at least some of the plurality of terrestrial components at the at least one first frequency of the satellite frequency band in a direction may be no greater than approximately 1/n of a total power transmitted by the at least some of the plurality of terrestrial components at the at least one first frequency of the satellite frequency band. In addition, n may be equal to 3, and each frequency reuse cluster may use the at least one first frequency of the satellite frequency band no more than once. The at least one first frequency of the satellite frequency band may be further used by radiotelephones to provide up-link communications.
According to additional embodiments of the present invention, a method of operating a radiotelephone system may include using a radiotelephone frequency by a plurality of terrestrial components to provide radiotelephone communications. The plurality of terrestrial components may include a plurality of frequency reuse clusters with at least one terrestrial component of each frequency reuse cluster transmitting from a plurality of directional sectors. A first frequency reuse cluster may transmit the radiotelephone frequency in a first direction, and a second frequency reuse cluster may transmit the radiotelephone frequency in a second direction that is randomly oriented relative to the first.
The radiotelephone frequency may be used by terrestrial components to provide down-link communications. Each of at least some terrestrial components transmitting from a plurality of directional sectors may include n directional sectors, and the radiotelephone frequency may be used by the plurality of frequency reuse clusters so that an aggregate radiated power transmitted by the plurality of frequency reuse clusters at the radiotelephone frequency in a direction may be no greater than approximately 1 In of a total radiated power transmitted by the plurality of frequency reuse clusters at the radiotelephone frequency. In addition, n may be equal to 3. Each frequency reuse cluster may use the radiotelephone frequency no more than once, and/or the radiotelephone frequency used by the plurality of frequency reuse clusters may be within a band of satellite frequencies transmitted by a space-based component.
According to still more embodiments of the present invention, a method of providing communications may include using a radiotelephone frequency by a plurality of terrestrial components to provide radiotelephone communications for a plurality of terminals. Use of the radiotelephone frequency by the plurality of terrestrial components may be randomized.
The plurality of terrestrial components may include a plurality of frequency reuse clusters with at least one terrestrial component of each frequency reuse cluster including a plurality of directional sectors. Moreover, randomizing use of the radiotelephone frequency may include using the radiotelephone frequency in no more than one directional sector of a frequency reuse cluster and in different directions over respective different frequency reuse clusters. Randomizing use of the radiotelephone frequency in no more than one directional sector of a frequency reuse cluster may include using the radiotelephone frequency so that a direction of at least two directional sectors using the radiotelephone frequency is staggered therebetween. The radiotelephone frequency may be used by terrestrial components to provide down-link communications, and/or the radiotelephone frequency used among the plurality of terrestrial components may be within a band of satellite frequencies transmitted by a space-based component.
According to yet more embodiments of the present invention, a communications system may include means for using a radiotelephone frequency among a plurality of terrestrial components to provide radiotelephone communications for a plurality of mobile terminals. In addition, means for randomizing use of the radiotelephone frequency among the plurality of terrestrial components may be provided.
The plurality of terrestrial components may be grouped into clusters of terrestrial components with at least one terrestrial component of each cluster transmitting over a plurality of directional sectors, and the means for randomizing use of the radiotelephone frequency may include means for using the radiotelephone frequency in no more than one directional sector of a cluster of terrestrial components. The means for randomizing use of the radiotelephone frequency in no more than one directional sector of a cluster of terrestrial components may include means for using the radiotelephone frequency so that a direction of at least two directional sectors using the radiotelephone frequency is staggered therebetween.
The radiotelephone frequency may be used by terrestrial components to provide down-link communications. The radiotelephone frequency used among the plurality of terrestrial components may be within a band of satellite frequencies transmitted by a space-based component. Moreover, the radiotelephone frequency may be further used by radiotelephones to provide up-link communications.
According to yet more embodiments of the present invention, a satellite radiotelephone system may include a space-based component configured to provide wireless radioterminal communications using frequencies of a set of frequencies authorized for space-based communications. A plurality of ancillary terrestrial components may be configured to communicate with radioterminals by terrestrially using frequencies of the set of frequencies authorized for space-based communications. At least some of the ancillary terrestrial components may terrestrially use at least one frequency that is authorized for space-based communications in a staggered sectorization pattern.
FIG. 15 schematically illustrates staggered sectorization for terrestrial reuse of satellite frequencies according to some embodiments of the present invention.
FIG. 1 is a schematic diagram of cellular satellite radiotelephone systems and methods according to embodiments of the invention. As shown in FIG. 1, these cellular satellite radiotelephone systems and methods 100 include at least one Space-Based Component (SBC) 110, such as a satellite. The space-based component 110 is configured to transmit wireless communications to a plurality of radiotelephones 120 a, 120 b in a satellite footprint comprising one or more satellite radiotelephone cells 130-130″″ over one or more satellite radiotelephone forward link (downlink) frequencies fD. The space-based component 110 is configured to receive wireless communications from, for example, a first radiotelephone 120 a in the satellite radiotelephone cell 130 over a satellite radiotelephone return link (uplink) frequency fU. An ancillary terrestrial network, comprising at least one ancillary terrestrial component 140, which may include an antenna 140 a and an electronics system 140 b (for example, at least one antenna 140 a and at least one electronics system 140 b), is configured to receive wireless communications from, for example, a second radiotelephone 120 b in the radiotelephone cell 130 over the satellite radiotelephone uplink frequency, denoted f′U, which may be the same as fU. Thus, as illustrated in FIG. 1, radiotelephone 120 a may be communicating with the space-based component 110 while radiotelephone 120 b may be communicating with the ancillary terrestrial component 140. As shown in FIG. 1, the space-based component 110 also undesirably receives the wireless communications from the second radiotelephone 120 b in the satellite radiotelephone cell 130 over the satellite radiotelephone frequency f′U as interference. More specifically, a potential interference path is shown at 150. In this potential interference path 150, the return link signal of the second radiotelephone 120 b at carrier frequency f′U interferes with satellite communications. This interference would generally be strongest when f′U=fU, because, in that case, the same return link frequency would be used for space-based component and ancillary terrestrial component communications over the same satellite radiotelephone cell, and no spatial discrimination between satellite radiotelephone cells would appear to exist.
As is known to those skilled in the art, GPS receivers may be extremely sensitive since they are designed to operate on very weak spread-spectrum radionavigation signals that arrive on the earth from a GPS satellite constellation. As a result, GPS receivers may to be highly susceptible to in-band interference. ATCs that are configured to radiate L-band frequencies in the forward satellite band (1525 to 1559 MHz) can be designed with very sharp out-of-band emissions filters to satisfy the stringent out-of-band spurious emissions requirements of GPS.
To increase or maximize forward link throughput in data mode, data mode TDD carriers according to embodiments of the invention may use a more spectrally efficient modulation and/or protocol, such as the EDGE modulation and/or protocol, on the forward link slots. The return link slots may be based on a less spectrally efficient modulation and/or protocol such as the GPRS (GMSK) modulation and/or protocol. The EDGE modulation/protocol and the GPRS modulation/protocol are well known to those having skill in the art, and need not be described further herein. Given an EDGE forward/GPRS return TDD carrier strategy, up to ( 384/2)=192 kbps may be supported on the forward link while on the return link the radiotelephone may transmit at up to ( 115/2)≈64 kbps.
In other embodiments, it also is possible to allocate six time slots of an eight-slot frame for the forward link and only two for the return link. In these embodiments, for voice services, given the statistically symmetric nature of voice, the return link vocoder may need to be comparable with quarter-rate GSM, while the forward link vocoder can operate at full-rate GSM, to yield six full-duplex voice circuits per GSM TDD-mode carrier (a voice capacity penalty of 25%). Subject to this non-symmetrical partitioning strategy, data rates of up to (384)( 6/8)=288 kbps may be achieved on the forward link, with up to (115)( 2/8)≈32 kbps on the return link.
is a monotonically decreasing function of the independent variable p. Consequently, in some embodiments, as the maximum ATC power increases, the carrier frequency that the ATC uses to establish and/or maintain the communications link decreases. FIG. 8 illustrates an embodiment of a piece-wise continuous monotonically decreasing (stair-case) function. Other monotonic functions may be used, including linear and/or nonlinear, constant and/or variable decreases. FACCH or Slow Associated Control CHannel (SACCH) messaging may be used in embodiments of the invention to facilitate the mapping adaptively and in substantially real time.
Thus, according to embodiments of FIG. 9, if a radiotelephone is being served within the outer-most ring of the cell, that radiotelephone is being served via frequency fO. This radiotelephone, being within the furthest area from the ATC, has (presumably) requested maximum (or near maximum) power output from the ATC. In response to the maximum (or near maximum) output power request, the ATC uses its a priori knowledge of power-to-frequency mapping, such as a three-step staircase function of FIG. 8. Thus, the ATC serves the radiotelephone with a low-value frequency taken from the lowest portion of the mobile L-band forward link frequency set, for example, from as close to 1525 MHz as possible. This, then, can provide additional safeguard to any GPS receiver unit that may be in the vicinity of the ATC.
According to other embodiments of the invention, embodiments of FIGS. 8-10 can be combined with embodiments of FIG. 11. Furthermore, according to other embodiments of the invention, if an fI carrier of FIG. 9 or 10 is underutilized, because of the relatively small footprint of the inner-most region of the cell, it may be used to support additional traffic over the much larger outermost region of the cell.
Other embodiments may be based on operating the ATC entirely in reverse frequency mode compared to the SBC. In these embodiments, an ATC transmits over the satellite return link frequencies while radiotelephones respond over the satellite forward link frequencies. If sufficient contiguous spectrum exists to support CDMA technologies, and in particular the emerging Wideband-CDMA 3G standard, the ATC forward link can be based on Wideband-CDMA to increase or maximize data throughput capabilities. Interference with GPS may not be an issue since the ATCs transmit over the satellite return link in these embodiments. Instead, interference may become a concern for the radiotelephones. Based, however, on embodiments of FIGS. 11-12, the radiotelephones can be configured to transmit GSM since ATC return link rates are expected, in any event, to be lower than those of the forward link. Accordingly, the ATC return link may employ GPRS-based data modes, possibly even EDGE. Thus, return link carriers that fall within a predetermined frequency interval from the GPS band-edge of 1559 MHz, can be under loaded, per embodiments of FIG. 11 or 12, to satisfy GPS interference concerns.
By providing a spatial guardband, some terrestrial reuse of satellite frequencies may be obtained. Moreover, an interference reducer, such as the interference reducer of FIG. 1 or 2, may not need to be used. The complexity of the system therefore may be reduced. Alternatively, when interference reducers according to embodiments of the invention are used, a satellite radiotelephone frequency also can be used terrestrially within the very same satellite cell, with reduced or no interference, but at the potential expense of system complexity.
In some embodiments, in response to the received signal levels and/or the information content of the satellite BCCH carriers, the ancillary terrestrial component serving a given geographic area, or a subset of the ancillary terrestrial components, can determine the satellite band frequencies that they may deploy with reduced or minimum interference impact to the satellite communications. In some embodiments, satellite band frequencies that are associated with the weakest satellite BCCH carrier that is received, may be deployed by the ancillary terrestrial components with highest priority, followed by those corresponding to the next weakest BCCH carrier, etc. Thus, the entire ancillary terrestrial network that may be serving a particular geographic area may configure and reconfigure its frequency plan and, in some embodiments, in real time, in response to monitoring of the satellite network BCCH emissions.
According to some embodiments of the invention that were described above, satellite frequencies may be terrestrially reused, and various embodiments may be used for reducing, minimizing or eliminating interference by the terrestrially reused satellite frequencies with the satellite frequencies that are used for satellite communications. Embodiments of the present invention that will now be described can be used separately or in connection with any of the above-described embodiments, to allow further reduction, minimization or elimination of interference by terrestrially reused satellite frequencies. These embodiments also may be used in conventional cellular radiotelephone systems to reduce, minimize or eliminate interference with other radio systems.
In particular, FIG. 15 illustrates a frequency reuse pattern by an ancillary terrestrial network comprising a network of ancillary terrestrial components (ATC). FIG. 15 may be contrasted with FIGS. 13 and 14, which illustrate satellite frequency reuse plans. Thus, in some embodiments, the network of ATCs shown in FIG. 15 may all be included within a satellite radiotelephone cell. In other embodiments, the network of ATCs may be spread over a plurality of satellite radiotelephone cells. It also will be understood that fewer or more ATCs may be used. Moreover, the network of ATCs shown in FIG. 15 may be used in the absence of a satellite radiotelephone cell. In addition, the network of ATCs shown in FIG. 15 may be included within a satellite radiotelephone cell such that one or more frequencies used by the ATCs shown in FIG. 15 are not used by the satellite system in the satellite radiotelephone cell in which the ATCs of FIG. 15 are located. For example, one or more frequencies used by the ATCs shown in FIG. 15 may be used by the satellite system in other satellite radiotelephone cells not including the ATCs shown in FIG. 15.
FIG. 15 illustrates an ancillary terrestrial network of ATCs that uses a four-cell frequency reuse pattern, wherein the ancillary terrestrial network reuses the satellite frequencies that are used in a geographically overlapping and/or non-geographically overlapping satellite radiotelephone cell. It will be understood that, although FIG. 15 illustrates a four-cell frequency reuse pattern 1510, smaller or larger cell frequency reuse patterns may be used. The four-cell frequency reuse pattern 1510 is outlined in a thick line in FIG. 15.
As also shown in FIG. 15, each ATC may distribute its terrestrially reused frequencies in its geographical area of coverage in a plurality of sectors, similar to the sectorization that is used in the base stations of conventional cellular radiotelephone networks. In FIG. 15, each ATC comprises three 120° sectors labeled 1, 2 and 3. The use of sectors in a radiotelephone base station, for example, is discussed in U.S. Pat. No. 6,311,074 entitled Base Station And Method For Covering A Cell Of A Cellular Mobile Radiotelephone System, and in U.S. Pat. No. 5,432,780 entitled High Capacity Sectorized Cellular Communication System, the disclosures of which are hereby incorporated herein in their entirety by reference. It will also be understood that fewer or more sectors also may be used, and/or that a number of sectors at each ATC within a network may be the same or different.
As shown in FIG. 15, according to some embodiments of the invention, staggered sectorization is used. Thus, over the plurality of four-cell reuse clusters of FIG. 15, frequency reuse of a particular frequency or set of frequencies, for example a frequency or set of frequencies F1, is staggered over different ATC sectors as it is reused over different four-cell clusters. More particularly, staggered sectorization for the frequency or set of frequencies F1 may be provided such that the use of the frequency or set of frequencies F1 in different reuse clusters may be staggered in different directions using directional sector antennas as shown in FIG. 15.
In particular, referring to FIG. 15, ATC 1520 a reuses a particular frequency or set of frequencies in sector 2, as shown by arrow 1530 a. ATC 1520 b reuses the same frequency or frequencies in sector 3, as shown by arrow 1530 b. ATC 1520 c reuses this same frequency or frequencies in sector 1, as shown by arrow 1530 c. Finally, ATC 1520 d reuses the same frequency or frequencies in sector 3, as shown by arrow 1530 d. Other staggered sectorizations of the same frequency are shown by other arrows in FIG. 15, but are not labeled for the sake of clarity.
When viewed globally from the perspective of a device, such as an airplane and/or other airborne vehicle, in any given direction, only one third of the total deployed reuses of a particular frequency or set of frequencies are radiating maximum or nearly maximum power in the given direction. Accordingly, the effective energy that is radiated by the ancillary terrestrial network at a given frequency in any given direction may be reduced. A given airborne device will therefore be exposed to only approximately one third the radiated power in the given frequency than may otherwise be the case if sectorization was maintained uniform across the ancillary terrestrial network.
It will be understood that in some embodiments of the invention, not all of the ATCs may need to stagger the reuse of a given satellite frequency or frequencies. In particular, in some embodiments, only some ATCs may stagger a reused frequency. Moreover, in other embodiments, staggering may be performed for some satellite radiotelephone frequencies but not for other satellite radiotelephone frequencies. Finally, as was already noted, staggered sectorization may be used in the base stations of conventional cellular radiotelephone systems, for example in a manner shown in FIG. 15.
According to embodiments of the present invention illustrated in FIGS. 13-15, a satellite radiotelephone system can include a space-based component(s), such as one or more satellites, configured to provide wireless radiotelephone communications over a satellite radiotelephone frequency band. The space-based component(s) can provide communications for a plurality of satellite radiotelephone cells (also referred to as coverage areas) such as illustrated, for example, in FIG. 13 or FIG. 14. More particularly, the satellite radiotelephone cells can be used to provide reuse of satellite radiotelephone frequencies so that the space-based component(s) reuses the same radiotelephone frequency or frequencies for radiotelephone communications in different geographic areas while reducing interference therebetween. As discussed above, FIG. 13 illustrates a seven cell reuse pattern of satellite radiotelephone frequencies in satellite radiotelephone cells, and FIG. 14 illustrates a nine cell reuse pattern of satellite radiotelephone frequencies in satellite radiotelephone cells.
A plurality of ancillary terrestrial components can be configured to provide an ancillary terrestrial network with each ancillary terrestrial component providing terrestrial radiotelephone communications for a respective terrestrial network cell. Moreover, the plurality of terrestrial components may be configured to terrestrially reuse at least one of the satellite radiotelephone frequencies within the satellite radiotelephone frequency band used by the space-based component, and the at least one of the satellite radiotelephone frequencies reused terrestrially may be reused in a staggered sectorization within the cells of the ancillary terrestrial network.
As discussed above, a satellite radiotelephone cell may have a diameter on the order of hundreds of kilometers, while an ancillary terrestrial network cell may have a diameter on the order of ten kilometers or less. A satellite radiotelephone cell, for example, may thus provide satellite radiotelephone communications over a relatively broad geographic area including a plurality of cities, while each city within the satellite radiotelephone cell may be serviced by a different terrestrial network with each terrestrial network including a respective plurality of ancillary terrestrial components such as base stations. Stated in other words, a plurality of separate ancillary terrestrial networks (with an example of a single ancillary terrestrial network being illustrated in FIG. 15) may provide terrestrial radiotelephone communications within a single satellite radiotelephone cell of a satellite communications network including a plurality of satellite radiotelephone cells such as illustrated, for example, in FIGS. 13 and 14.
More particularly, the satellite radiotelephone network may provide reuse of satellite radiotelephone frequencies within the satellite radiotelephone frequency band such that adjacent satellite radiotelephone cells do not use the same satellite radiotelephone frequencies. Moreover, components of an ancillary terrestrial network within a satellite radiotelephone cell may use satellite radiotelephone frequencies within the satellite radiotelephone frequency band other than frequencies used by the satellite radiotelephone cell for satellite communications within which the ancillary terrestrial network is located. Moreover, satellite radiotelephone frequencies used by the ancillary terrestrial network can be used by the space-based component to provide radiotelephone communications in other satellite radiotelephone cells not including the ancillary terrestrial network. Accordingly, interference between ancillary terrestrial networks and satellite radiotelephone cells using frequencies within the same satellite radiotelephone frequency band can be reduced and/or eliminated.
With a satellite communications network, such as illustrated in FIG. 13 or FIG. 14, one satellite radiotelephone frequency or a set of satellite radiotelephone frequencies can be reused in commonly numbered satellite radiotelephone cells. For example, a first set of satellite radiotelephone frequencies from the satellite radiotelephone frequency band can be reused by each of the satellite radiotelephone cells identified by reference number 1 in FIG. 13 to provide radio links for transmissions to/from a space-based component from/to radiotelephones in the satellite radiotelephone cells identified by reference number 1. A second set of satellite radiotelephone frequencies from the satellite radiotelephone frequency band can be reused by ancillary terrestrial components of an ancillary terrestrial network located within one of the satellite radiotelephone cells identified by the reference number 1 in FIG. 13.
The ancillary terrestrial network of FIG. 15, for example, can be located within one of the satellite radiotelephone cells identified by reference number 1 in FIG. 13. More particularly, the first and second sets of satellite radiotelephone frequencies can be mutually exclusive so that interference between transmissions to/from the space-based component in the satellite radiotelephone cell and transmissions to/from ancillary terrestrial components of the ancillary terrestrial network in the satellite radiotelephone cell can be reduced and/or eliminated. Moreover, satellite radiotelephone frequencies of the second set can be reused to provide transmissions to/from the space-based component in satellite radiotelephone cells other than the satellite radiotelephone cell(s) including an ancillary terrestrial network(s) using the second set of satellite radiotelephone frequencies.
In an alternative, a satellite radiotelephone system may be authorized to use a set of satellite frequencies, and the set of satellite frequencies may be partitioned into first and second substantially mutually exclusive (non-overlapping) sub-sets. The first sub-set of satellite frequencies may be allocated for use by ancillary terrestrial components of the ancillary terrestrial network, and the second sub-set may be allocated for use by one or more space based components (such as one or more satellites) providing satellite radiotelephone cells. The sub-set of satellite frequencies used by the ancillary terrestrial network may be used according to a staggered sectorization pattern as discussed above with respect to FIG. 15.
An example of reuse of one or a set of the satellite radiotelephone frequencies of the second set used by the ancillary terrestrial network is illustrated with the arrows of FIG. 15. As shown, at least a portion of the ancillary terrestrial components can be divided into n directional sectors and one or more of the radiotelephone frequencies of the second set can be reused by the ancillary terrestrial network m times. Moreover, the ancillary terrestrial components can be grouped into reuse clusters or patterns indicated by the thick lines defining the reuse patterns 1510 discussed above. The arrows represent the reuse of one or a set of the radiotelephone frequencies no more than once in one directional sector of one ancillary terrestrial component in each reuse cluster. Moreover, the directions of the arrows are staggered to reduce an aggregate power of reused frequencies transmitted by the ancillary terrestrial network in any one direction.
As shown in FIG. 15, for example, a portion of the ancillary terrestrial components can be divided into 3 directional sectors (i.e. n=3), and one or a set of the radiotelephone frequencies can be reused 18 times as indicated by the 18 arrows (i.e. m=18). Moreover, the radiotelephone frequencies are shown as being reused 6 times in directional sectors pointing to X degrees, 6 times in directional sectors pointing to X+120 degrees, and 6 times in sectors pointing to X+240 degrees. In other words, an aggregate of radiated power transmitted by the ancillary terrestrial network at the reused frequency or frequencies in any direction in the example of FIG. 15 is no greater than approximately 1/n of a total radiated power transmitted by the ancillary terrestrial network at the reused frequency. As the directional sectors may not necessarily be aligned from ancillary terrestrial component to ancillary terrestrial component within an ancillary terrestrial network, an aggregate of radiated power transmitted in any direction may actually be less (or more) than 1/n of a total radiated power transmitted by the ancillary terrestrial network at the reused frequency or frequencies.
Additional reductions of aggregate radiated power in a particular direction may also be obtained by selectively rotating orientations of the ancillary terrestrial components such that directional sectors of ancillary terrestrial components are intentionally misaligned. In an ancillary terrestrial network including ancillary terrestrial components divided into three 120 degree sectors, for example, a first half of the ancillary terrestrial components may be aligned so that the directional sectors point to 90 degrees, 210 degrees, and 330 degrees, and a second half of the ancillary terrestrial components may be aligned so that the directional sectors point to 30 degrees, 150 degrees, and 270 degrees.
It also will be understood that techniques other than sectorization may be used to obtain randomization of the direction of frequency reuse and/or directional diversity in at least portions of the ancillary terrestrial network. For example, beam forming techniques may be used to randomize the direction of frequency reuse for beams that are reused in a given sector of the ancillary terrestrial network. Moreover, directions of frequency reuse may be randomized in ancillary terrestrial systems with terrestrial components divided into different numbers of sectors. For example, not every terrestrial component in terrestrial networks according to embodiments of the present invention must be divided into sectors, and those that are divided into sectors may be divided into different numbers of sectors.
According to embodiments of the present invention, providing communications can include reusing a radiotelephone frequency among a plurality of terrestrial components to provide radiotelephone communications for a plurality of mobile terminals. Moreover, reuse of the radiotelephone frequency can be randomized among the plurality of terrestrial components. In addition, the plurality of terrestrial components can be grouped into clusters of terrestrial components with at least one terrestrial component of each cluster transmitting to a plurality of directional sectors, and randomizing reuse of the radiotelephone frequency can include reusing the radiotelephone frequency in no more than one directional sector of a cluster of terrestrial components. Moreover, the clusters of terrestrial components may comprise clusters of adjacent terrestrial components.
Randomizing reuse of the radiotelephone frequency in no more than one directional sector of a cluster of terrestrial components can further include reusing the radiotelephone frequency so that a direction of the directional sectors reusing the radiotelephone frequency is staggered. As discussed above, the radiotelephone frequency can be used to provide downlinks from respective terrestrial components to receiving radiotelephones. In addition, the radiotelephone frequency reused among the plurality of terrestrial components can be within a band of satellite frequencies transmitted by a space-based component. Stated in other words, the radiotelephone frequency reused by the terrestrial components can also be used for satellite radiotelephone communications.
Similarly, a communications system can include means for reusing a radiotelephone frequency among a plurality of terrestrial components to provide radiotelephone communications for a plurality of mobile terminals, and means for randomizing reuse of the radiotelephone frequency among the plurality of terrestrial components. The plurality of terrestrial components can be grouped into clusters of terrestrial components with at least one terrestrial component of each cluster transmitting to a plurality of directional sectors, and the means for randomizing reuse of the radiotelephone frequency can include means for reusing the radiotelephone frequency in no more than one directional sector of a cluster of terrestrial components.
The means for randomizing reuse of the radiotelephone frequency in no more than one directional sector of a cluster of terrestrial components can also include means for reusing the radiotelephone frequency so that a direction of the directional sectors reusing the radiotelephone frequency is staggered. The radiotelephone frequency can also be used to provide down-links from respective terrestrial components to receiving radiotelephones.
a plurality of ancillary terrestrial components configured to provide communications over a service region using at least one first frequency of the satellite frequency band in a staggered sectorization pattern, wherein the space-based component does not provide communications over the service region using the at least one first frequency and an aggregate power radiated by the plurality of ancillary terrestrial components at the at least one first frequency in any direction is less than a total power radiated by the plurality of ancillary terrestrial components at the at least one first frequency.
2. A satellite radiotelephone system according to claim 1 wherein the space-based component is configured to provide communications over a service region including the plurality of ancillary terrestrial components using at least one second frequency of the satellite frequency band, wherein the at least one second frequency is different than the at least one first frequency.
3. A satellite radiotelephone system according to claim 2 wherein the space-based component is configured to provide down-link communications over the service region using the at least one second frequency.
4. A satellite radiotelephone system according to claim 2 wherein the space-based component is configured to provide communications over a second service region not including the plurality of ancillary terrestrial components using the at least one first frequency.
5. A satellite radiotelephone system according to claim 1 wherein the at least one first frequency is used by ancillary terrestrial components to provide down-link communications.
6. A satellite radiotelephone system according to claim 1 wherein each of at least some of the plurality of ancillary terrestrial components comprises n directional sectors and the at least one first frequency is used by the plurality of ancillary terrestrial components so that an aggregate power radiated by the plurality of ancillary terrestrial components at the at least one first frequency in a direction is limited to approximately 1/n of a total radiated power transmitted by the plurality of ancillary terrestrial components at the at least one first frequency.
7. A satellite radiotelephone system according to claim 5 wherein the at least one first frequency is further used by radiotelephones to provide up-link communications.
8. A satellite radiotelephone system according to claim 6 wherein n=3.
9. A satellite radiotelephone system according to claim 1 wherein the plurality of ancillary terrestrial components comprise a plurality of frequency reuse clusters, wherein each frequency reuse cluster uses the at least one first frequency no more than once.
a plurality of ancillary terrestrial components comprising a plurality of frequency reuse clusters, wherein a first frequency reuse cluster transmits at least one first frequency of the satellite frequency band in a first direction and a second frequency reuse cluster transmits the at least one first frequency of the satellite frequency band in a second direction, wherein the space-based component does not provide communications over a service region including the plurality of ancillary terrestrial components using the at least one first frequency and an aggregate power radiated by the plurality of ancillary terrestrial components at the at least one first frequency in any direction is less than a total power radiated by the plurality of ancillary terrestrial components at the at least one first frequency.
11. A satellite radiotelephone system according to claim 10 wherein the space-based component is configured to provide communications over a service region including the plurality of ancillary terrestrial components using at least one second frequency of the satellite frequency band, wherein the at least one second frequency is different than the at least one first frequency.
12. A satellite radiotelephone system according to claim 11 wherein the space-based component is configured to provide down-link communications over the service region including the plurality of ancillary terrestrial components using the at least one second frequency.
13. A satellite radiotelephone system according to claim 11 wherein the space-based component is configured to provide communications over a second service region not including the plurality of ancillary terrestrial components, wherein the space-based component provides communications over the second service region using the at least one first frequency.
14. A satellite radiotelephone system according to claim 10 wherein the at least one first frequency is used by ancillary terrestrial components to provide down-link communications.
15. A satellite radiotelephone system according to claim 10 wherein each of at least some of the plurality of ancillary terrestrial components comprises n directional sectors and an aggregate power radiated by the at least some of the plurality of ancillary terrestrial components at the at least one first frequency in a direction is no greater than approximately 1/n of a total power radiated by the at least some of the ancillary terrestrial components at the at least one first frequency.
16. A satellite radiotelephone system according to claim 15 wherein n=3.
17. A satellite radiotelephone system according to claim 15 wherein each frequency reuse cluster uses the at least one first frequency no more than once.
providing communications from a plurality of ancillary terrestrial components over a service region using at least one first frequency of the satellite frequency band in a staggered sectorization pattern, wherein the space-based component does not provide communications over the service region using the at least one first frequency and an aggregate power radiated by the plurality of ancillary terrestrial components at the at least one first frequency in any direction is less than a total power radiated by the plurality of ancillary terrestrial components at the at least one first frequency.
19. A method according to claim 18 wherein providing communications from a space-based component using frequencies of a satellite frequency band further comprises providing communications over a service region including the plurality of ancillary terrestrial components using at least one second frequency of the satellite frequency band, wherein the at least one second frequency is different than the at least one first frequency.
20. A method according to claim 19 wherein providing communications from a space-based component using frequencies of a satellite frequency band further comprises providing down-link communications over the service region including the plurality of ancillary terrestrial components using the at least one second frequency.
21. A method according to claim 19 wherein providing communications from a space-based component using frequencies of a satellite frequency band further comprises providing communications over a second service region not including the plurality of ancillary terrestrial components using the at least one first frequency.
22. A method according to claim 18 wherein the at least one first frequency is used by ancillary terrestrial components to provide down-link communications.
23. A method according to claim 18 wherein each of at least some of the plurality of ancillary terrestrial components comprises n directional sectors and the at least one first frequency is transmitted by the plurality of ancillary terrestrial components so that an aggregate power radiated by the plurality of ancillary terrestrial components at the at least one first frequency in a direction is no greater than approximately 1/n of a total power radiated by the plurality of ancillary terrestrial components at the at least one first frequency.
24. A method according to claim 22 wherein the at least one first frequency is further used by radiotelephones to provide up-link communications.
25. A method according to claim 23 wherein n=3.
26. A method according to claim 23 wherein the plurality of ancillary terrestrial components comprise a plurality of frequency reuse clusters wherein each frequency reuse cluster uses the at least one first frequency no more than once.
providing communications from a plurality of ancillary terrestrial components comprising a plurality of frequency reuse clusters, wherein a first frequency reuse cluster transmits at least one first frequency of the satellite frequency band in a first direction and a second frequency reuse cluster transmits the at least one first frequency of the satellite frequency band in a second direction, wherein the space-based component does not provide communications over a service region including the plurality of ancillary terrestrial components using the at least one first frequency and an aggregate power radiated by the plurality of ancillary terrestrial components at the at least one first frequency in any direction is less than a total power radiated by the plurality of ancillary terrestrial components at the at least one first frequency.
28. A method according to claim 27 wherein providing communications from a space-based component using frequencies of a satellite frequency band further comprises providing communications over a service region including the plurality of ancillary terrestrial components using at least one second frequency of the satellite frequency band, wherein the at least one second frequency is different than the at least one first frequency.
29. A method according to claim 28 wherein providing communications from a space-based component using frequencies of a satellite frequency band further comprises providing down-link communications over the service region using the at least one second frequency.
30. A method according to claim 28 wherein providing communications from a space-based component using frequencies of a satellite frequency band further comprises providing communications over a second service region not including the plurality of ancillary terrestrial components using the at least one first frequency.
31. A method according to claim 27 wherein the at least one first frequency is used by ancillary terrestrial components to provide down-link communications.
32. A method according to claim 27 wherein each of at least some of the plurality of ancillary terrestrial components comprises n directional sectors and the at least one first frequency is used by the plurality of frequency reuse clusters so that an aggregate power radiated by the plurality of frequency reuse clusters at the at least one first frequency in a direction is no greater than approximately 1/n of a total power radiated by the plurality of frequency reuse clusters at the at least one first frequency.
33. A method according to claim 32 wherein n=3.
34. A method according to claim 32 wherein each frequency reuse cluster uses the at least one first frequency no more than once.
a plurality of terrestrial components comprising a plurality of frequency reuse clusters, at least one terrestrial component of each frequency reuse cluster comprising a plurality of directional sectors, wherein at least a first and second frequency reuse clusters provide communications by transmitting at least one first frequency of a satellite frequency band in respective first and second directions, a space-based component provides communications using frequencies of the satellite frequency band and refrains from providing communications over a service region that includes the plurality of terrestrial components using the at least one first frequency and wherein an aggregate power radiated by the plurality of terrestrial components at the at least one first frequency in any direction is less than a total power radiated by the plurality of terrestrial components at the at least one first frequency.
36. A radiotelephone system according to claim 35 wherein the at least one first frequency of the satellite frequency band is used by terrestrial components to provide down-link communications.
37. A radiotelephone system according to claim 35 wherein each of at least some of the plurality of terrestrial components comprises n directional sectors and the at least one first frequency of the satellite frequency band is used so that an aggregate power radiated by the at least some of the plurality of terrestrial components at the at least one first frequency in a direction is no greater than approximately 1/n of a total power radiated by the at least some of the plurality of terrestrial components at the at least one first frequency.
38. A radiotelephone system according to claim 37 wherein n=3.
39. A radiotelephone system according to claim 37 wherein each frequency reuse cluster uses the at least one first frequency of the satellite frequency band no more than once.
40. A radiotelephone system according to claim 36 wherein the at least one first frequency of the satellite frequency band is further used by radiotelephones to provide up-link communications.
using a radiotelephone frequency by a plurality of terrestrial components to provide radiotelephone communications wherein the plurality of terrestrial components comprise a plurality of frequency reuse clusters with at least one terrestrial component of each frequency reuse cluster transmitting from a plurality of directional sectors and wherein a first frequency reuse cluster transmits the radiotelephone frequency in a first direction and a second frequency reuse cluster transmits the radiotelephone frequency in a second direction that is randomly oriented relative to the first.
42. A method according to claim 41 wherein the radiotelephone frequency is used by terrestrial components to provide down-link communications.
43. A method according to claim 41 wherein each of at least some terrestrial components transmitting from a plurality of directional sectors comprises n directional sectors and the radiotelephone frequency is used by the plurality of frequency reuse clusters so that an aggregate power radiated by the plurality of frequency reuse clusters at the radiotelephone frequency in a direction is no greater than approximately 1/n of a total power radiated by the plurality of frequency reuse clusters at the radiotelephone frequency.
44. A method according to claim 43 wherein n=3.
45. A method according to claim 43 wherein each frequency reuse cluster uses the radiotelephone frequency no more than once.
46. A method according to claim 41 wherein the radiotelephone frequency used by the plurality of frequency reuse clusters is within a band of satellite frequencies transmitted by a space-based component.
randomizing use of the radiotelephone frequency by the plurality of terrestrial components.
48. A method according to claim 47 wherein the plurality of terrestrial components comprise a plurality of frequency reuse clusters with at least one terrestrial component of each frequency reuse cluster comprising a plurality of directional sectors wherein randomizing use of the radiotelephone frequency comprises using the radiotelephone frequency in no more than one directional sector of a frequency reuse cluster and in different directions over respective different frequency reuse clusters.
49. A method according to claim 48 wherein randomizing use of the radiotelephone frequency in no more than one directional sector of a frequency reuse cluster comprises using the radiotelephone frequency so that a direction of at least two directional sectors using the radiotelephone frequency is staggered therebetween.
50. A method according to claim 47 wherein the radiotelephone frequency is used by terrestrial components to provide down-link communications.
51. A method according to claim 47 wherein the radiotelephone frequency used among the plurality of terrestrial components is within a band of satellite frequencies associated with a space-based component.
means for randomizing use of the radiotelephone frequency among the plurality of terrestrial components.
53. A communications system according to claim 52 wherein the plurality of terrestrial components are grouped into clusters of terrestrial components with at least one terrestrial component of each cluster transmitting over a plurality of directional sectors wherein the means for randomizing use of the radiotelephone frequency comprises means for using the radiotelephone frequency in no more than one directional sector of a cluster of terrestrial components.
54. A communications system according to claim 53 wherein the means for randomizing use of the radiotelephone frequency in no more than one directional sector of a cluster of terrestrial components comprises means for using the radiotelephone frequency so that a direction of at least two directional sectors using the radiotelephone frequency is staggered therebetween.
55. A communications system according to claim 52 wherein the radiotelephone frequency is used by terrestrial components to provide down-link communications.
56. A communications system according to claim 55 wherein the radiotelephone frequency used among the plurality of terrestrial components is within a band of satellite frequencies associated with a space-based component.
57. A communications system according to claim 56 wherein the radiotelephone frequency is further used by radiotelephones to provide up-link communications.
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FR2956745A1 (en) * 2010-02-19 2011-08-26 Thales Sa coating process of a signal from a set of satellite signals collections.

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