Lenzing using low-orbit repeaters

Abstract

Methods, systems, and devices for communication operations are described. A first satellite may be in a first orbit, and a set of second satellites may be in second orbits lower than the first orbit. The second satellites may detect signal components of a signal originating from a geographical area and relay their respective signal components to the first satellite. A beamformer coupled with the first satellite may form a beam associated with the geographical area. The beamformer may also acquire a beam signal based on their respective signal components and a return channel, wherein the return channel includes at least a channel component between the geographical area and the set of second satellites.

Description

Technology Field

[0001] The following concerns communication in general, and more specifically, signal detection.

[0002] An antenna array on a satellite in geostationary orbit can illuminate a geographical area associated with the satellite's coverage area. In some examples, the satellite may be used to support communication between access node terminals and user terminals within the coverage area. The satellite may also be used to detect signals emitted within the satellite's coverage area. In some examples, the detection resolution of the satellite may be limited, for instance, by the distance from the satellite's target geographical area. For instance, the satellite may not be able to detect signals transmitted or emitted within the geographical area at low power levels, or signals that are not intentionally directed toward the satellite.

[0003] The described techniques relate to improved methods, systems, devices, and apparatuses that support lensing using lower earth orbit repeaters. A first satellite may be in a first orbit, and a set of second satellites may be in second orbits lower than the first orbit. The second satellites may detect signal components of a signal originating from a geographical area within the coverage area of ​​the first satellite. The second satellites may relay their respective signal components to the first satellite. A beamformer coupled with the first satellite may form a beam associated with the geographical area. The beamformer may also acquire a beam signal based on the respective signal components forming the beam and a return channel. The return channel may include at least a channel between the geographical area and the set of second satellites. Brief explanation of the drawing

[0004] FIG. 1a illustrates a diagram of a communication system supporting Lenzing using low orbit repeaters according to examples as disclosed in this specification. FIG. 1b illustrates components of satellites supporting lenzing using low-orbit repeaters according to examples as disclosed in this specification. FIG. 2 illustrates an example of a coverage diagram supporting Lenzing using low orbit repeaters according to examples as disclosed in this specification. FIG. 3 illustrates a set of exemplary operations supporting Lenzing using low-orbit repeaters according to examples as disclosed in this specification. FIG. 4 illustrates an example of a constellation diagram supporting Lenzing using low orbit repeaters according to examples as disclosed in this specification. FIG. 5 illustrates a block diagram of a signal analyzer supporting Lenzing using low orbit repeaters according to examples as disclosed in this specification. FIG. 6 illustrates a diagram of a communication device that supports Lenzing using low orbit repeaters, according to examples as disclosed in this specification. FIG. 7 illustrates a flowchart illustrating a method for supporting Lenzing using low orbit repeaters according to examples as disclosed in this specification. Specific details for implementing the invention

[0005] A satellite communication system may include satellites in geostationary Earth orbits (GEO), which may be referred to as GEO satellites, and satellites in non-GEO Earth orbits, which may be referred to as non-GEO satellites. In some examples, non-GEO satellites are at a lower altitude than GEO satellites. Some examples of non-GEO satellites include satellites in intermediate Earth orbits (MEO), which may be referred to as MEO satellites, and satellites in low Earth orbits (LEO), which may be referred to as LEO satellites. Satellites (e.g., GEO, MEO, or LEO satellites) may be used to detect signals emitted from stationary or moving sources on land, water, or in the air. In some examples, a satellite network operator may use the detected signals to determine whether a known or unknown emitter is located in a geographical area.

[0006] GEO satellites can be used to detect known and unknown signal emitters within a geographic area. In some examples, the resolution of a GEO satellite associated with surveying specific geographic areas may be limited based on the size of the antenna array on the GEO satellite. Therefore, in the case of a GEO satellite, the 3dB boundary of the beam used to survey a geographic area of ​​interest may be excessively large compared to the boundary of the geographic area of ​​interest.

[0007] According to the various embodiments described herein, a number of non-GEO satellites may be used to survey a large geographic area with increased resolution, for example, based on a number of non-GEO satellites having an aperture larger than that of a single satellite. In some examples, a relay link may be established between a first satellite (e.g., GEO satellite) in a first orbit (e.g., GEO) and one or more second satellites (e.g., non-GEO satellites) in one or more second orbits (e.g., one or more non-GEO satellites). Using one or more second satellites as relay satellites for the first satellite may allow the second satellites to have relatively lower complexity (e.g., lower cost, smaller size, etc.) compared to fully functional satellites having high-power transponders and high-gain tracking antenna systems for transmitting signals directly to ground stations. One or more second satellites may each have one or more antennas illuminated by at least a portion of one or more geographic regions and may each detect signal components of one or more signals emitted from one or more geographic regions. One or more second satellites may relay their respective signal components of one or more signals to the first satellite. In some examples, when ground-based beamforming is used, the first satellite may transmit signal components or representations of signal components to the ground system as one or more signals. In some examples, the ground system may determine beamforming weights and apply them to one or more signals received from the first satellite to obtain one or more beam signals corresponding to the signals detected in one or more geographic regions.

[0008] In other examples, when on-board beamforming is used, the first satellite can process signal components to determine beamforming weights and apply them to the signal components to acquire one or more beam signals corresponding to signals detected from one or more geographic regions. In these cases, the first satellite can transmit representations of one or more beam signals to a ground system. By using signal components detected from one or more second satellites, post-processing can be performed to effectively increase the detection resolution of the first satellite by enabling the processing system to focus on one or more geographic regions with enhanced sensitivity.

[0009] In some examples, in addition to the respective signal components received from one or more second satellites, the first satellite may detect additional signal components of one or more signals in one or more geographic regions, for example, via a direct path. In these cases, the second satellites may effectively increase the aperture of the first satellite. In some examples, the first satellite may transmit the additional signal components of one or more signals, or a representation of the detected additional signal components of one or more signals, to a ground system. The ground system may use the additional signal components to obtain representations of one or more signals detected in one or more geographic regions. In other examples, the first satellite may use the additional signal components to obtain representations of one or more signals. By supplementing the direct signal components received by the first satellite with the signal components received from one or more second satellites, the quality of the signal detected by the first satellite may be improved compared to the case where only the direct signal components are used to detect the signal (e.g., the signal strength may be increased).

[0010] First, aspects of the present disclosure are described in the context of a satellite communication system. Subsequently, specific examples are described by coverage diagrams, process flows, and constellation diagrams. Aspects of the present disclosure are further illustrated by and described by reference to device diagrams and flowcharts related to Lenzing using low-orbit repeaters.

[0011] FIG. 1a illustrates a diagram of a communication system supporting Lenzing using low-orbit repeaters according to examples as disclosed herein. A satellite communication system (100) may include a network of satellites including a first satellite (105) and second satellites (115). A satellite communication system (100) may also include a ground system (130) including one or more gateways (135). One or more gateways (135) may include a beamformer (155) (or otherwise may be combined with it). In some examples, the beamformer (155) may be included in a ground station processor (153). The ground station processor (153) may use the beamformer (155) to determine beam coefficients. The ground station processor (153) may also be configured to demodulate (and, in some examples, decode) beam signals generated by the beamformer (155).

[0012] A satellite (e.g., a first satellite (105) or a second satellite (115)) may be configured to support wireless communication between one or more access node terminals (e.g., within a ground system (130)) and user terminals located in a coverage area (e.g., a coverage area (150)). The satellite may also be configured to detect signals emitted within the coverage area (150). In some examples, the satellite may include an antenna assembly having one or more antenna feed elements. Each of the antenna feed elements may also include a radio frequency (RF) signal transducer, a low noise amplifier (LNA), or a power amplifier (PA), or otherwise be coupled with them, and may be coupled with one or more transponders within the satellite.

[0013] In some examples, some or all antenna feed elements in the satellite may be arranged as an array of receiving and / or transmitting antenna feed elements that are cooperative components to enable various examples of beamforming, such as ground-based beamforming (GBBF), on-board beamforming (OBBF), end-to-end (E2E) beamforming, or other types of beamforming. In the case of OBBF, the satellite It may include several transmitters, The beam weight matrix It can be used to generate multiple user beams. Similarly, in the case of GBBF, the satellite is It may include transmitters, corresponding to each transmitter in the satellite (e.g., frequency division multiplexed) from one or more access node terminals Can receive signals. One or more access node terminals By applying the beam weight matrix It can generate multiple user beams. In the case of E2E beamforming, the satellite It can include several transponders. N transponders may be used to receive signals from M access node terminals, wherein the received signals are weighted before transmission by the access node terminals (e.g., for each set of one or more access node terminals (Weighting each of the beam signals) Beamforming can be supported for user beams. While these examples describe forward links, it should be noted that similar arrangements can be made for backward links.

[0014] Satellites can be launched into different orbits—GEO orbits or non-GEO orbits. Satellites within GEO may be referred to as GEO satellites. Non-GEO orbits may include MEOs, LEOs, low equatorial orbit (ELEO), etc. Satellites within MEO may be referred to as MEO satellites, satellites within LEO may be referred to as LEO satellites, and so on. GEO satellites can orbit the Earth at a speed matching the Earth's rotation speed and thus remain in a single position relative to a specific point on Earth. LEO satellites can orbit the Earth at a speed exceeding the Earth's rotation speed (e.g., relative to the ground), and thus the satellite's position relative to a specific point on Earth may change as it travels through LEO. LEO satellites can be launched with low gradients (e.g., ELEOs) or high gradients (e.g., polar orbits) to provide different types of coverage and revisit times for given areas of the Earth. MEO satellites can also orbit the Earth at speeds exceeding the Earth's rotation speed, but they can be at higher altitudes than LEO satellites. HEO satellites can orbit the Earth in an elliptical pattern, where the satellite moves closer to and further away from the Earth across the entire HEO.

[0015] In some examples, GEO satellites may be more expensive and structurally more complex than non-GEO satellites (e.g., may include more repeaters, antenna elements, transponders, etc.). Despite the increased complexity of GEO satellites, networks of non-GEO satellites can provide services and survey the Earth with greater granularity than GEO satellites (e.g., based on being more numerous and closer to Earth). In some examples, GEO satellites and non-GEO satellites operate independently of each other. In some examples, the first satellite (105) may be a GEO satellite. The second satellites (115) may include LEO satellites, MEO satellites, or a combination thereof.

[0016] In some examples, a satellite network may be used to survey at least a portion of the Earth for signals emitted from known and unknown transmitters. For example, the satellite network may use a first satellite (105) to detect signals originating from a geographical area (e.g., a geographical area included by a coverage area (150)). In some examples, the first satellite (105) may transmit the detected signal energy to a ground system (130) (e.g., one or more gateways (135)) to process the detected signal energy (e.g., determine and apply beamforming coefficients) to acquire one or more signals, for example, when ground-based beamforming is used. In other examples, the first satellite (105) may process the detected signal energy (e.g., determine and apply beamforming coefficients therefor) and transmit one or more signals to the ground system (130), for example, when on-board beamforming is used.

[0017] GEO satellites can be used to detect known and unknown signal emitters within a geographic area. In some examples, the resolution of a GEO satellite associated with surveying specific geographic areas may be limited based on the size of the antenna array on the GEO satellite and the distance from the point of interest of the GEO satellite. Therefore, in the case of a GEO satellite, the 3dB boundary of the beam used to survey a geographic area of ​​interest may be excessively large compared to the boundary of the geographic area of ​​interest.

[0018] According to the various embodiments described herein, a plurality of non-GEO satellites may be used to survey a large geographic area with increased resolution, for example, based on a plurality of non-GEO satellites having an aperture larger than that of a single satellite (e.g., GEO, MEO, or LEO satellite). In some examples, a relay link may be established between a first satellite (105) (e.g., GEO satellite) in a first orbit (e.g., GEO) and one or more second satellites (115) (e.g., non-GEO satellites) in one or more second orbits (e.g., one or more non-GEO satellites). Each of the one or more second satellites (115) may have one or more antennas that illuminate at least a portion of one or more geographic areas (140) and may each detect signal components (125) of one or more signals emitted from one or more geographic areas. According to the various embodiments described herein, one or more antennas of the second satellites (115) are described as being illuminated (instead of illuminating) by a portion of one or more geographical regions (140). It is worth noting that these terms may be used interchangeably to describe that one or more antennas of the second satellites (115) can be used to transmit signals to or detect signals from one or more geographical regions (140).

[0019] One or more second satellites (115) may relay their respective signal components (125) of one or more signals to the first satellite (105). In some examples, when ground-based beamforming is used, the first satellite (105) may transmit signal components or representations of signal components as one or more signals to the ground system (130). In some examples, the ground system (130) may determine beamforming weights and apply them to one or more signals received from the first satellite (105) to obtain one or more beam signals corresponding to one or more signals detected in one or more geographic areas (140).

[0020] In other examples, when on-board beamforming is used, the first satellite (105) can process relayed signal components (110) to determine beamforming weights and apply them to the signal components to obtain one or more beam signals corresponding to one or more signals. In these cases, the first satellite (105) can transmit representations of one or more beam signals to a ground system (130). By using signal components detected by one or more second satellites (115), post-processing can be performed to effectively increase the detection resolution of the first satellite (105) by enabling the processing system to focus on one or more geographic areas (140) with enhanced sensitivity.

[0021] In some examples, in addition to the respective signal components relayed from one or more second satellites (115), the first satellite (105) may detect additional signal components (e.g., direct signal components (120)) of one or more signals in one or more geographical areas, for example, via a direct path. In these cases, the second satellites may effectively increase the aperture of the first satellite. In some examples, the first satellite (105) may use additional signal components to obtain representations of one or more signals. In other examples, the first satellite (105) may transmit additional signal components of one or more signals, or representations of detected additional signal components of one or more signals, to the ground system (130). The ground system (130) may use additional signal components to obtain representations of one or more signals detected in one or more geographical areas (140). By supplementing the direct signal component (120) received from the first satellite (105) with signal components received from one or more second satellites (115), the quality of the signal detected by the first satellite (105) can be improved compared to the case where only the direct signal component (120) is used to detect the signal (e.g., the signal strength can be increased).

[0022] As RF signal energy is emitted from an emitter (e.g., a transmitter or a thermal energy emitter), each second satellite (115) detects components of the signal (e.g., having their respective phase shifts or amplitude fluctuations due to different channels between the emitter and each second satellite (115)). When used in combination with the first satellite (105) to detect signal components in geographical areas (140) corresponding to the location of the emitter (e.g., emitter (145)), the second satellites (115) may be referred to as relay satellites (115). The geographical areas (140) may be located within the coverage area (150) of the first satellite (105). For example, the first relay satellite (115-1) may receive a first detected signal component (125-1) based on the signal emitted from the emitter (145) within the first geographical area (140-1). In some of these examples, the first relay satellite (115-1) is the first return channel (this is The first detected signal component (125-1) is received through a channel (which may be referred to as), and the second relay satellite (115-2) receives the first detected signal component (125-1) and the second return channel (this is This includes receiving a second detected signal component through a (which may be referred to as ). In some examples, the return channels between the relay satellites (115) and the first geographical area (140-1) are a combined return channel matrix (which is It may be included in (which may be referred to as ). Relay satellites (115) can similarly receive signal components detected from other geographical regions (140) (including the Pth geographical region (140-P)).

[0023] In some examples, the return channels between the relay satellite (115) and the set of geographical regions (140) are a combined return channel matrix ( Can be included in ). Matrix( ) may include a quantity of repeaters included in the relay satellites (115), a quantity of rows based on the quantity of relay satellites (115), and a quantity of columns based on the quantity of geographical areas (140) monitored by the relay satellites (115). For example, if S relay satellites (115) include Q repeaters and are used to monitor P geographical areas (140), The matrix is It can have rows and P columns.

[0024] Relay satellites (115) can relay detected signal components (125) (or expressions of detected signal components) to the first satellite (105). In some examples, relaying the detected signal components (125) may include frequency-shifting the detected signal components, amplifying the detected signal components, or both, before the detected signal components are relayed to the first satellite (105).

[0025] FIG. 1b illustrates components of satellites supporting Lenzing using low-orbit repeaters according to examples as disclosed herein. As illustrated in FIG. 1b, the relay satellite (115) may include one or more repeaters (160) used to amplify and / or frequency shift the detected signal before relaying the detected signal to the first satellite (105). The repeater (160) may be a non-processing repeater. That is, the repeater (160) may perform operations such as interpreting or reformatting data within the signal waveform. For example, the repeater (160) may not digitize, demodulate, decode, apply beamforming weights, or reformatt the detected signals before relaying the detected signals to the first satellite (105). The repeater (160) may include a frequency converter (165), an amplifier (170), or both. A frequency converter (165) may be configured to shift the frequency of a detected signal (e.g., by mixing the detected signal with another frequency). In some examples, frequency converters (165) within different relay satellites (115) may be configured to apply different frequency shifts to the detected signals. An amplifier (170) may be configured to amplify the detected signal before relaying the amplified signal to the first satellite (105).

[0026] In some examples, the first relay satellite (115-1) can transmit the first relayed signal component (110-1) (which may correspond to an amplified version of the first detected signal component (125-1)) to the first satellite (105). In some of these examples, the first relay satellite (115-1) has a first return channel (which The first relayed signal component (110-1) is transmitted to the first satellite (105) through a channel (which may be referred to as), and the second relay satellite (115-2) transmits the first relayed signal component (110-1) to the first satellite (105), and the second relay satellite (115-2) transmits the second return channel (this is The second transmitted signal component is transmitted through a (which may be referred to as ). The return channels between the relay satellites (115) and the first satellite (105) are a second combined return channel matrix (which is It may be included in the relay satellites (115) which can be referred to as the second combination return channel ( Signal components detected from other geographical regions (140) (including the Pth geographical region (140-P)) can be transmitted through ).

[0027] procession( ) may include a quantity of rows based on the quantity of uplink / downlink transponder paths in the first satellite (105), a quantity of relay satellites (115), and a quantity of columns based on the quantity of repeaters included in the relay satellites (115). For example, if the first satellite (105) has L uplink / downlink transponder paths and there are S relay satellites (115) having Q repeaters, A matrix has L rows and It can have several columns.

[0028] Accordingly, the return channel between the geographical regions (140) and the first satellite (105) has a number of components, namely the first channel component between the relay satellites (115) and the geographical regions (140) (this is (which can be expressed as) and a second channel component between the relay satellites (115) and the first satellite (105) (this is It may be a composite return channel including (which can be expressed as). In some examples, the composite return channel between the geographical areas (140) and the first satellite (105) is It can be represented as a matrix. In some examples, when the first satellite (105) includes L uplink / downlink transponder paths and P geographic areas (140) are monitored, A matrix can have L rows and P columns.

[0029] In some examples, the first satellite (105) may receive signal components directly from one or more of the geographical regions (140). For example, the first satellite (105) may have a direct return channel between the first satellite (105) and the first geographical region (140-1) (this A signal component (120) can be received directly from the emitter (145) through a (which can be expressed as). In some examples, return channels between geographical areas (140), relay satellites (115), and the first satellite (105) are combined with direct return channels to form a composite return channel matrix (which It can form (which can be expressed as), and here is. Matrix( ) may include a quantity of rows based on the quantity of uplink / downlink transponder paths included in the first satellite (105), and a quantity of columns based on the quantity of geographical areas (140) monitored by the relay satellites (115). For example, if the first satellite (105) includes L uplink / downlink transponder paths and is used to monitor P geographical areas (140), It can have L rows and P columns.

[0030] Similarly, the entire return channel between the geographical areas (140) and the ground system (130) may be a composite return channel comprising a number of components. In some examples, the entire return channel is between the geographical areas (140) and the first satellite (105) (this also Channel components between (which can be expressed as); channel components within the first satellite (105) between uplink and downlink transponders in the first satellite (105) (this is a matrix It can be expressed as); and the channel component between the first satellite (105) and the ground system (130) (this is a matrix Includes (can be expressed as).

[0031] As illustrated in FIG. 1b, the first satellite (105) may include one or more transponders (175) used to amplify and / or frequency shift the detected signal before transmitting the received signal to the first satellite (105). The transponder (175) may include a frequency converter (165), an amplifier (170), or both. The frequency converter (180) may be configured to shift the frequency of the received signal (e.g., by mixing the detected signal with another frequency). The amplifier (185) may be configured to amplify the received signal before transmitting the amplified signal to the ground system (130). In some examples, the transponder (175) may be combined with on-board processing components such as a beamformer (190), a demodulator, a decoder, a reformatting component, or a combination thereof. In some examples, the on-board processing components may be included in an on-board processor (187). In some examples, when the beamformer (190) is included in the first satellite (105), the ground system (130) may not use the beamformer (155) to process signals received from the first satellite (105).

[0032] In some examples, the channel components within the first satellite (105) are based on paths through the transponders of the first satellite (105), where a matrix ( ) may include a number of rows and columns based on the number of transponders included in the first satellite (105). For example, if the first satellite (105) includes L transponders, A matrix can contain L rows and L columns.

[0033] In addition, the channel component between the first satellite (105) and the ground system (130) (represented as a matrix) may be based on the number of ground stations included in the ground system (130) and the number of repeaters included in the first satellite (105). For example, if the ground system includes M ground stations (e.g., gateways) and the first satellite (105) includes L uplink / downlink transponder paths, A matrix can contain M rows and L columns.

[0034] In some examples, the entire return channel between the geographical areas (140) and the ground system (130) is a matrix ( It can be expressed as ), where is. In some examples, where the ground system (130) includes M ground stations and P geographical areas (140) are monitored, A matrix can have M rows and P columns.

[0035] In some examples, the ground system (130) receives signals from known emitters located within the coverage area (150) and the entire return channel ( ) can be estimated. The ground system (130) can determine return channels associated with the received signals using signals received from known emitters, and can estimate return channels between geographic areas (140) and the ground system (130) by interpolating the determined return channels. In some examples, the ground system (130) can estimate a portion of the total return channel components using the received signals. For example, the ground system (130) Signals can be used to estimate the channel components associated with the channel, where other channel components can be estimated based on reference signals communicated between devices to support channel estimation.

[0036] The ground system (130) uses the estimated channel components to return the covariance (which is a matrix It can determine (which can be expressed as ). In some examples, the ground system may use the estimated channel component to determine the return covariance between signals received from different geographic regions (140) at M different ground stations, where is, is a noise term associated with the downlink (which may also be referred to as the forward link); is a noise term associated with the uplink (which may also be referred to as the reverse link); silver It is the identity matrix. In some examples, the return covariance may also include the covariance caused by interfering user traffic (e.g., for J interferers). In these cases, and, here, It can be a channel between the interferers and the ground system. and Both matrices can have M rows and M columns.

[0037] The ground system (130) can determine beam coefficients to apply to signals received through the entire return channel using the estimated total return channel and the estimated return covariance. In some examples, the beam coefficients are matrix ( It is expressed by ), where is. Matrix( ) may include a quantity of rows based on the quantity of monitored geographical areas (140), and a quantity of columns based on the quantity of ground stations of the ground system (130). For example, for P geographical areas and M ground stations, a matrix ( ) may include P rows and M columns. Thus, the beamformed channel between the ground system (130) and one or more geographic regions (140) It can be expressed as, where am.

[0038] In some examples, the first satellite (105) may apply similarly determined beam coefficients to signals received from relay satellites (115) instead of applying beam coefficients to signals received from the ground system (130). In such examples, the first satellite (105) may transmit a composite signal to the ground system (130) that includes a representation of the signals detected in each monitored geographical area (140). When beamforming is performed at the first satellite (105), The matrix is ​​the identity matrix (e.g., It can be the identity matrix (where M can be 1).

[0039] In some examples, instead of transmitting the signal components detected by the relay satellites (115) to the first satellite (105), the relay satellites (115) may transmit the detected signal components directly to the ground system (130). In addition to the signal components transmitted to the ground system (130), the first satellite (105) may transmit signal components directly to the ground system (130). In these cases, the signal components of the signal detected by the relay satellites (115) may complement the direct signal components of the signal detected by the first satellite (105).

[0040] Although generally described in relation to detecting signals originating from geographical areas (140) within a coverage area (150), similar techniques may be used to transmit signals to user terminals having geographical areas (140) on a forward link. In these cases, the forward channel between the ground system (130) and the geographical areas (140) may similarly include a plurality of channel components, including a channel component between the ground system (130) and the first satellite (105), a channel component between the first satellite (105) and the relay satellites (115), and a channel component between the relay satellites (115) and the geographical areas (140). In these cases, the ground system (130) may similarly estimate the forward channel (and in some examples, one or more of the forward channel components may be estimated individually). Additionally, the ground system (130) may determine beam coefficients and apply them to signals to be transmitted to different geographical areas, for example, by applying a first set of beam coefficients to a first signal so that relay satellites (115) focus the transmission of the first signal within a first geographical area (140-1), and by applying a second set of beam coefficients to a second signal so that relay satellites (115) focus the transmission of the second signal within a second geographical area. In such examples, the first satellite (105) may transmit different components of the signal to the relay satellites (115), the relay satellites (115) may transmit different signal components, and the different signal components may be consistently combined within a desired geographical area (140). In some examples, the relay satellites (115) may reduce the transmission power of different signal components to comply with signal strength thresholds on Earth (e.g., set by a regulatory body).

[0041] FIG. 2 illustrates an example of a coverage diagram supporting lenzing using low-orbit repeaters according to examples as disclosed in this specification. The coverage diagram (200) illustrates a coverage area of ​​a GEO satellite using a first satellite (e.g., a GEO satellite, the first satellite (105) of FIG. 1) and one or more second satellites (e.g., LEO satellites, MEO satellites, LEO and MEO satellites, the relay satellites (115) of FIG. 1) to focus on a geographical area.

[0042] In some examples, the antenna array at the first satellite is associated with a coverage area (250). The boundaries of the coverage area (250) may indicate points where signals received at the antenna array have a signal strength at the 3dB point. In some cases, the coverage area (250) may represent a coverage area for a beamformed beam to be transmitted or received through the coverage area (250) via the first satellite. In some examples, the first satellite may process signals received within the coverage area (250). However, regarding the detection of signals within the coverage area (250), the first satellite may not be able to determine where the signal originated within the coverage area (250). As described in this specification, in order to increase the detection resolution of the first satellite (and, in some examples, to effectively increase the aperture), one or more second satellites (orbiting lower than the first satellite) may be used to detect signals originating from geographical areas within the coverage area (250).

[0043] In some examples, each of the second satellites may have a smaller coverage area (205) than the first satellite. Similar to the coverage area (250), the boundaries of the coverage areas (205) may indicate 3dB points for detecting signals originating within the coverage area (205). For example, for a first focused coverage area (205-1), the corresponding second satellite may detect signals originating from the geographical area corresponding to the first focused coverage area (205-1), but may not be able to detect signals originating within the coverage area (250) but originating outside the first focused coverage area (205-1). In some examples, energy from within the overlapping coverage areas (205) of the second satellites may be combined and focused on specific geographical areas (240). For example, the second satellites may be used to focus on the first geographical area (240-1).

[0044] In some examples, the second satellites may be used to focus (e.g., simultaneously) within a number of geographical regions (240) within the coverage area (250) for the detection of signals. For example, in addition to focusing on the first geographical region (240-1), the second satellites may be used to focus on other geographical regions (e.g., the first geographical region (240-1), the Pth geographical region (240-P)). The different geographical regions (240) monitored using the second satellites may not overlap or may overlap. In some examples, the second satellites may similarly be used to focus on one or more geographical regions within the coverage area (250) for the transmission of signals to user devices within one or more geographical regions.

[0045] FIG. 3 illustrates a set of exemplary operations supporting lenzing using low-orbit repeaters according to examples as disclosed herein. The process flow (300) may be performed by the second satellites (303), the first satellite (305), and the ground system (307), which may be examples of the second satellites (115), the first satellite (105), and the ground system (130) as described in FIG. 1. In some examples, the process flow (300) illustrates an exemplary sequence of operations performed to support the use of low-orbit repeaters. For example, the process flow (300) illustrates operations for detecting signals transmitted from geographical areas within the coverage area of ​​the GEO satellite.

[0046] It is understood that one or more of the operations described in the process flow (300) may be performed early or later in the process, or may be omitted, replaced, supplemented, or combined with other operations. Additionally, additional operations described herein that are not included in the process flow (300) may be included.

[0047] In arrow (315), the emitter (301) may emit a signal while located within a geographical area. In some examples, the emitter (301) emits a signal while communicating wirelessly with a device other than the second satellites (303) or the first satellite (305). In other examples, the emitter (301) emits a signal involuntarily (e.g., the emitter (301) may be a rocket, and the signal may be associated with a flare generated by the rocket). One or more of the second satellites (303) may detect the signal. That is, the signal may be radiated from the emitter (301), and each of the second satellites (303) may detect a different signal component associated with the emitted signal. In some examples, in addition to being detected by the second satellites (303), a direct signal component of the emitted signal may be detected by the first satellite (305).

[0048] In the arrows (320), the second satellites (303) can relay the detected signal components (or representations of the received signal components) to the first satellite (305). In some examples, the second satellites (303) may be applied to one or more repeaters used to relay the detected signal components to the first satellite (305). The repeaters may be used to amplify the detected signal components (or a combination thereof), apply a frequency shift, or apply a phase shift to them before transmission to the first satellite (305). In some examples, the first satellite (305) may receive the signal components from one or more antenna elements. The first satellite (305) may also receive the signal components directly from one or more antenna elements.

[0049] In arrow (325), the first satellite (305) can transmit a representation of a signal emitted by the emitter (301) to the ground system (307). The first satellite (305) can transmit signal components (in some examples including direct signal components) to the ground system (307). In some examples, the first satellite (305) transmits signal components to the ground system (307) via one or more beams to one or more ground stations. The ground system (307) can receive the signal transmitted from the first satellite (305). In some examples, the ground system (307) can receive the signal transmitted from the first satellite (305) at one or more ground stations.

[0050] In block (330), the ground system (307) based on the received signals, the channel between the ground system (307) and the emitter (301) (which may be referred to as a return channel) (which may be indicated as) can be estimated. In some examples, the ground system (307) can also estimate the channel based on signals received from known transmitters located within or around a geographical area containing the emitter (301) (e.g., the geographical area (140) of FIG. 1 or the geographical area (240) of FIG. 2). In some examples, signals received from known transmitters may be transmitted simultaneously with signals detected by the second satellites (303). In some examples, signals received from known transmitters may be transmitted before the signals are detected by the second satellites (303), and in some cases, the signals may be received by a set of second satellites different from the second satellites (303). That is, channel estimation for relay by a given set of second satellites may be made using information on signals from known transmitters relayed by a different set of second satellites (e.g., non-overlapping, partially overlapping).

[0051] In some examples, to estimate the return channel, the ground system (307) estimates a portion of the return channel between the emitter (301) and the second satellites (303) (this is (This can be expressed as), a part of the return channel between the second satellites (303) and the first satellite (305) (this is (This can be expressed as), a part of the return channel between the uplink and downlink transponders within the first satellite (305) (this is (which can be expressed as), and a part of the return channel between the first satellite (305) and the ground system (307) (this is (which can be expressed as) can be estimated. When the first satellite also receives a direct signal component, the ground system can estimate a portion of the return channel between the emitter (301) and the first satellite (305) (this is It can be estimated that) can be expressed as

[0052] In some examples, the ground system (307) is based on interpolating signals transmitted by known transmitters near a set of monitored geographical areas to form a channel between the emitter and the second satellite (303). ) estimates the channel between the second satellites (303) and the ground system (307) based on reference signals transmitted from known transmitters in a set of monitored geographical areas (e.g., , and ) is estimated. In other examples, the components of the channel are estimated individually. For example, the channel between the second satellites (303) and the first satellite (305) ) can be estimated (e.g., by the first satellite (305)) based on reference signals transmitted between the second satellites (303) and the first satellite (305). The first satellite ( The return channels of the transponders of ) can also be estimated by the first satellite (305). The first satellite (305) can present the estimated channels to the ground system (307). And the channel between the first satellite (305) and the ground system (307) ) can be estimated based on reference signals transmitted between the first satellite (305) and the ground system (307) (e.g., by the ground system (307)).

[0053] In block (335), the ground system (307) may estimate a covariance associated with the return channel based, for example, on the estimated return channel / components of the estimated return channel. The covariance may provide information regarding interference between transmissions of signal components detected in different geographical regions to the ground system (307) and interference from other communications with the ground system (307). In some examples, interference between signal components from different geographical regions is It can be expressed as. Also, interference between J users is It can be expressed as. And, the combined covariance is It can be expressed as.

[0054] In block (340), the ground system (307) can determine beam coefficients to apply to signals received from the first satellite (305) using the estimated return channel and the estimated return covariance. In some examples, the beam coefficients are matrix ( It can be expressed as ), where silver It may be. In some examples, the beam coefficients and the return channel are determined based on the same time period, where the received signals to estimate the channel may be used to determine the beam coefficients. In some examples, the ground system (307) may continuously update the estimated return channel and beam coefficients based on the received signals (e.g., every millisecond). For example, the ground system (307) may process a first set of signals to estimate the return channel and process the first set of signals again based on the estimated return channel to determine the beam coefficients.

[0055] In block (345), the ground system (307) may apply beam coefficients to a signal received from the first satellite (305) to obtain one or more beam signals corresponding to one or more geographic regions. In some examples, one or more beam signals correspond to representations of one or more signals emitted from geographic regions. One or more beam signals may include a beam signal that is a representation of a signal emitted by an emitter (301) in a geographic region. In some examples, when digital beamforming is used, applying beam coefficients may include applying beam coefficients to a digital representation of a signal, for example, by multiplying a beam coefficient matrix by a matrix representing the signal. In other examples, applying beam coefficients may include combining components of an analog signal received by the ground system (307) to obtain an analog beam signal.

[0056] In block (350), the ground system (307) can process (e.g., filtering, analysis, demodulation, decoding) one or more beam signals to determine whether a signal has been detected in a geographical area of ​​interest. In some examples, the ground system (307) determines the type of signal detected in the geographical area of ​​interest (e.g., a communication signal, a signal associated with a rocket, etc.).

[0057] As suggested above, the order of operations of the process flow (300) may be changed. In some examples, operations to estimate the return channel and the covariance associated with the return channel and to determine the beam coefficients may be performed by the ground system (307) before the representation of the signal emitted by the emitter (301) is received from the first satellite (305).

[0058] In some examples, operations of the process flow (300) may be performed by different devices. For example, operations for estimating the return channel and the covariance associated with the return channel, determining the beam coefficients, and applying the beam coefficients may be performed by the first satellite (305) (e.g., when the first satellite is configured to perform OBBF). In these cases, the first satellite (305) may transmit one or more beam signals corresponding to the signal emitted by the emitter (301) to the ground system (307). The ground system (307) may process the received one or more beam signals as described herein.

[0059] Although described in the context of using the second satellites (303) to detect signals through return channels associated with geographical areas within the coverage area of ​​the first satellite (305), similar operations may be performed to use the second satellites (303) to estimate forward channels associated with geographical areas and relay signals to user devices within the geographical areas.

[0060] FIG. 4 illustrates an example of a constellation diagram supporting lenzing using low-orbit repeaters according to examples as disclosed herein. The constellation diagram (400) illustrates a set of second satellites (e.g., LEO satellites, MEO satellites, relay satellites (115) of FIG. 1, etc.) that can be used in combination with a first satellite (e.g., GEO satellite of FIG. 1, first satellite (105)), etc., to increase the detection resolution of the first satellite for detecting signals within a coverage area (and, in some examples, to effectively increase the aperture). In some examples, the coverage areas of the second satellites (415) may correspond to their respective focused coverage areas (205) described in FIG. 2.

[0061] The constellation diagram (400) may include S second satellites (415), where S may be 9. Sets of second satellites (415) may be located on different orbital planes (405) (e.g., K orbital planes). In some examples, the second satellites (415) are distributed among three orbital planes (405), where the first orbital plane (405-1) may have a slope of -5 degrees, the second orbital plane (405-2) may have a slope of 0 degrees, and the third orbital plane (405-3) may have a slope of 5 degrees. In some examples, the second satellites (415) may be evenly distributed among three orbital planes (405) such that three of the second satellites (415) are included in each of the orbital planes. In some examples, second satellites (415) included in the same orbital plane (405) may be separated from each other based on the degree of separation. For example, the degree of separation between second satellites (415) included in the same orbital plane (405) may be 5 degrees (or approximately 5 degrees).

[0062] FIG. 5 illustrates a block diagram of a signal analyzer supporting lensing using low-orbit repeaters according to examples as disclosed herein. The signal analyzer (520) may be an example of an embodiment of a first satellite or ground station as described with reference to FIG. 1a. The signal analyzer (520) or various components thereof may be examples of means for carrying out various embodiments of a lens using low-orbit repeaters as described herein. For example, the signal analyzer (520) may include a channel estimator (525), a beamformer (530), a signal manager (535), a covariance estimator (540), a demodulator (545), a decoder (550), or any combination thereof. Each of these components may communicate directly or indirectly with one another (e.g., through one or more buses).

[0063] The signal analyzer (520) may support communication according to examples as disclosed herein. The beamformer (530) may be configured as a means for forming a beam associated with a geographical area to obtain beam coefficients of a beam associated with a geographical area based at least partially on an estimated return channel comprising a first channel component between a geographical area and a plurality of second satellites and a second channel component between a plurality of second satellites and a first satellite; and to obtain a beam signal based at least partially on the beam coefficients and a plurality of signal components of a signal originating from the geographical area and relayed to the first satellite by a plurality of second satellites, or otherwise support such a beamformer.

[0064] In some examples, the channel estimator (525) may be configured as a means for estimating a return channel from a geographic area, or otherwise support such, and the return channel comprises a first channel component between a first satellite and a plurality of second satellites and a second channel component between the plurality of second satellites and the geographic area. In some examples, to support estimating a return channel of a geographic area, the channel estimator (525) may be configured as a means for determining a plurality of return channels based at least partially on one or more other signals received from known geographic locations, or otherwise support such. In some examples, one or more other signals include one or more reference signals transmitted by transmitters at known geographic locations. In some examples, to support estimating a return channel of a geographic area, the channel estimator (525) may be configured as a means for interpolating the characteristics of a plurality of return channels to estimate the characteristics of the return channel, or otherwise support such.

[0065] In some examples, the signal manager (535) may be configured as a means for obtaining a representation of a plurality of signal components relayed by a plurality of second satellites and a representation of a direct signal component of a signal received from a first satellite from a geographical area, or otherwise support such a beam signal is determined at least partially based on the representation of the plurality of signal components and the representation of the direct signal component.

[0066] In some examples, the covariance estimator (540) may be configured as a means for estimating the return covariance associated with a geographic area based at least partially on the return channel, or otherwise support this. In some examples, the beamformer (530) may be configured as a means for determining the beam coefficients of the beam based at least partially on the return channel and the return covariance, or otherwise support this.

[0067] In some examples, to support acquiring a beam signal, the beamformer (530) may be configured as a means for applying beam coefficients of a beam to a representation of a plurality of signal components of a signal to acquire one or more beam signals, or otherwise support this.

[0068] In some examples, the channel estimator (525) may be configured as a means for estimating a plurality of return channels from a plurality of geographical regions, or otherwise support such, the plurality of return channels include return channels, and the plurality of geographical regions include geographical regions. In some examples, the covariance estimator (540) may be configured as a means for estimating the return covariance based at least partially on a plurality of return channels, or otherwise support such. In some examples, the beamformer (530) may be configured as a means for determining a plurality of beam coefficients of a plurality of beams based at least partially on a plurality of return channels and the return covariance, or otherwise support such.

[0069] In some examples, the beamformer (530) may be configured as a means for applying a plurality of beam coefficients of a plurality of beams to representations of a plurality of signal components associated with a plurality of signals originating from a plurality of geographical regions in order to acquire one or more beam signals, or otherwise support such, and one or more beam signals include a beam signal.

[0070] In some examples, the demodulator (545) may be configured as a means for demodulating a beam signal or otherwise support it. In some examples, the decoder (550) may be configured as a means for decoding a demodulated beam signal or otherwise support it.

[0071] FIG. 6 illustrates a diagram of a communication device that supports Lenzing using low-orbit repeaters according to examples as disclosed herein. The communication device (605) may be an example of or include components of a first satellite (105) (e.g., a geosynchronous satellite supporting on-board beamforming) or a ground system (130) as described herein. The communication device (605) may include components for processing signals, such as an input / output (I / O) controller (610), a transceiver (615), an antenna (625), a signal analyzer (620), a memory (630), a code (635), and a processor (640). These components may communicate electronically through one or more buses (e.g., a bus (645)) or otherwise may be coupled (e.g., operablely, communically, functionally, electronically, electrically).

[0072] The I / O controller (610) can manage input and output signals for the communication device (605). The I / O controller (610) can also manage peripherals that are not integrated into the communication device (605). In some cases, the I / O controller (610) may represent a physical connection or port to an external peripheral. In some cases, the I / O controller (610) may utilize an operating system such as iOS®, ANDROID®, MS-DOS®, MS-WINDOWS®, OS / 2®, UNIX®, LINUX®, or other known operating systems. Additionally or alternatively, the I / O controller (610) may represent or interact with a modem, keyboard, mouse, touchscreen, or similar device. In some cases, the I / O controller (610) may be implemented as part of a processor such as the processor (640). In some cases, the user can interact with the communication device (605) through the I / O controller (610) or through hardware components controlled by the I / O controller (610).

[0073] In some cases, the antenna (625) may be a single antenna. In some other cases, the antenna (625) may include multiple antennas (or antenna elements) capable of simultaneously transmitting or receiving multiple wireless transmissions. The transceiver (615) may communicate bidirectionally through one or more antennas (625), wired, or wireless links as described herein. For example, the transceiver (615) may represent a wireless transceiver and may communicate bidirectionally with another wireless transceiver. The transceiver (615) may also include a modem for modulating packets, providing the modulated packets to one or more antennas (625) for transmission, and demodulating packets received from one or more antennas (625).

[0074] Memory (630) may include random access memory (RAM) and / or read-only memory (ROM). Memory (630) may store code (635). Code (635) may be computer-readable and computer-executable code and may include instructions that, when executed by a processor (640), cause a communication device (605) to perform various functions described herein. Code (635) may be stored in a non-transient computer-readable medium, such as system memory or other types of memory. In some cases, code (635) may not be directly executable by a processor (640), but may cause a computer to perform functions described herein (e.g., when compiled and executed). In some cases, memory (630) may include a basic input / output system (BIOS) capable of controlling basic hardware or software operations, such as interactions with peripheral components or devices, among other things.

[0075] The processor (640) may include intelligent hardware devices (e.g., general-purpose processor, DSP, CPU, microcontroller, ASIC, FPGA, programmable logic device, discrete gate or transistor logic component, discrete hardware component, or any combination thereof). In some cases, the processor (640) may be configured to operate a memory array using a memory controller. In some other cases, the memory controller may be integrated within the processor (640). The processor (640) may be configured to execute computer-readable instructions stored in memory (e.g., memory (630)) to enable the communication device (605) to perform various functions (e.g., functions or tasks that support reporting angle offsets over a frequency range). For example, a communication device (605) or a component of the communication device (605) may include a processor (640) and a memory (630) coupled to the processor (640), and the processor (640) and the memory (630) are configured to perform various functions described herein. The processor (640) may include a ground station processor (153) or an on-board processor (187) (or may be an example thereof).

[0076] The signal analyzer (620) may support signal analysis at a first satellite (e.g., a geosynchronous satellite) or a ground station according to examples as disclosed herein. For example, the signal analyzer (620) may be configured as a means for obtaining beam coefficients of a beam associated with a geographical area based at least partially on an estimated return channel comprising a first channel component between a geographical area and a plurality of second satellites and a second channel component between a plurality of second satellites and a first satellite. The signal analyzer (620) may be configured as a means for forming a beam associated with a geographical area to obtain a beam signal based at least partially on beam coefficients and a plurality of signal components of a signal originating from the geographical area and relayed to the first satellite by a plurality of second satellites, or may not be supported.

[0077] In some examples, the signal analyzer (620) may be configured to perform various operations (e.g., receiving, monitoring, transmitting) using or otherwise cooperating with the transceiver (615), one or more antennas (625), or any combination thereof. Although the signal analyzer (620) is exemplified as a separate component, in some examples, one or more functions described with reference to the signal analyzer (620) may be supported or performed by the processor (640), memory (630), code (635), or any combination thereof. For example, the code (635) may include instructions executable by the processor (640) to enable the communication device (605) to perform various modes of reporting angle offsets over a frequency range as described herein, or the processor (640) and memory (630) may otherwise be configured to perform or support these operations.

[0078] Fig. 7The present specification illustrates a flowchart illustrating a method for supporting lenzing using low-orbit repeaters according to examples as disclosed herein. Operations of the method may be implemented by components of a first satellite (e.g., a geosynchronous satellite supporting on-board beamforming) or a ground station as described herein. In some examples, the first satellite or ground station may execute a set of instructions to control functional elements of the first satellite or ground station to perform the described functions. Additionally or alternatively, the first satellite or ground station may perform aspects of the described functions using special-purpose hardware.

[0079] In 705, the method may include the step of obtaining beam coefficients of a beam associated with a geographic area based at least partially on an estimated return channel comprising a first channel component between the geographic area and a plurality of second satellites and a second channel component between the plurality of second satellites and the first satellite. The operations of 705 may be performed according to examples as disclosed herein. In some examples, aspects of the operations of 705 may be performed by a channel estimator (525) as described with reference to FIG. 5.

[0080] In 710, the method may include the step of forming a beam associated with a geographical area to acquire a beam signal based at least partially on beam coefficients and a plurality of signal components of a signal originating from the geographical area and relayed to the first satellite by a plurality of second satellites. The operations of 710 may be performed according to examples as disclosed herein. In some examples, aspects of the operations of 710 may be performed by a beamformer (530) as described with reference to FIG. 5.

[0081] In some examples, an apparatus as described herein may perform a method or methods such as method (700). The apparatus may include features, circuits, logic, means, or instructions (e.g., a non-transient computer-readable medium storing instructions executable by a processor) for forming a beam associated with a geographical area to obtain beam coefficients of a beam associated with a geographical area based at least partially on an estimated return channel comprising channel components between a geographical area and a plurality of second satellites, and to obtain a beam signal based at least partially on the beam coefficients and a plurality of signal components associated with a signal originating from the geographical area.

[0082] Some examples of the method (700) and apparatus described herein may further include operations, features, means or instructions for receiving a representation of a plurality of signal components, and the beam signal is obtained at least partially based on applying beam coefficients of the beam to a representation of a plurality of signal components.

[0083] Some examples of the method (700) and apparatus described herein may further include operations, features, means, or instructions for estimating a return channel from a geographical area, wherein the return channel includes a first channel component between a first satellite and a plurality of second satellites and a second channel component between the plurality of second satellites and a geographical area.

[0084] In some examples of the method (700) and apparatus described herein, estimating a return channel of a geographic area may include operations, features, circuits, logic, means, or instructions for determining a plurality of return channels based at least partially on one or more other signals received from known geographic locations, and for interpolating the characteristics of the plurality of return channels to estimate the characteristics of the return channels.

[0085] In some examples of the method (700) and apparatus described in this specification, one or more other signals include one or more reference signals transmitted by transmitters at known geographical locations.

[0086] Some examples of the method (700) and apparatus described herein may further include operations, features, means or instructions for obtaining a representation of a plurality of signal components relayed by a plurality of second satellites and a representation of a direct signal component of a signal received from a first satellite in a geographical area, and the beam signal may be determined at least partially based on the representation of the plurality of signal components and the representation of the direct signal component.

[0087] Some examples of the method (700) and apparatus described herein may further include operations, features, means, or instructions for estimating a return covariance associated with a geographic area based at least partially on a return channel, and determining beam coefficients of a beam based at least partially on the return channel and the return covariance.

[0088] In some examples of the method (700) and apparatus described herein, acquiring a beam signal may include operations, features, circuits, logic, means, or instructions for applying beam coefficients of a beam to a representation of a plurality of signal components of a signal in order to acquire one or more beam signals.

[0089] Some examples of the method (700) and apparatus described herein may further include operations, features, means, or instructions for estimating a plurality of return channels from a plurality of geographical regions—where the plurality of return channels include return channels and the plurality of geographical regions include geographical regions—estimating a return covariance based at least partially on the plurality of return channels, and determining a plurality of beam coefficients of a plurality of beams based at least partially on the plurality of return channels and the return covariance.

[0090] Some examples of the method (700) and apparatus described herein may further include operations, features, means, or instructions for applying a plurality of beam coefficients of a plurality of beams to representations of a plurality of signal components associated with a plurality of signals originating from a plurality of geographical regions in order to acquire one or more beam signals, and one or more beam signals include beam signals.

[0091] A system for communication is described. The system comprises a first satellite in a first orbit, a plurality of second satellites in second orbits lower than the first orbit—each of the second satellites is configured to detect their respective signal components of a signal originating from a geographical area and relay their respective signal components to the first satellite—and a beamformer configured to form a beam associated with the geographical area to acquire a beam signal based at least partially on their respective signal components and estimated return channels, wherein the estimated return channels include channel components between the geographical area and the plurality of second satellites.

[0092] In some examples of the system, the first satellite includes a plurality of transponders, and in order to transmit a representation of a signal to a ground system, each transponder of the plurality of transponders may be configured to receive their respective signal components relayed by a plurality of second satellites and to transmit a representation of their respective signal components to the ground system.

[0093] In some examples of the system, each of the plurality of second satellites includes at least one repeater, and in order to relay their respective signal components to the first satellite, the repeaters of the plurality of second satellites may be configured to amplify their respective detected signal components and transmit their respective amplified signal components to the first satellite. In some examples of the system, at least one repeater may be a non-processing repeater.

[0094] In some examples of the system, repeaters of multiple second satellites may be configured to transmit their respective amplified signal components at the same frequency as their respective signal components detected in the repeaters.

[0095] In some examples of the system, repeaters of multiple second satellites may be configured to transmit their respective amplified signal components at different frequencies from the respective signal components detected at the repeaters.

[0096] In some examples of the system, each of the repeaters of the plurality of second satellites may be configured to transmit their respective amplified signal components at their respective frequencies of the plurality of frequencies.

[0097] In some examples of the system, each signal component detected by a plurality of second satellites can be detected through a first channel between the plurality of second satellites and a geographical area, each signal component can be relayed to a first satellite through a second channel between the plurality of second satellites and a first satellite, and the first satellite can be configured to transmit a representation of each signal component to a ground system through a third channel between the first satellite and a ground system.

[0098] In some examples of the system, the beamformer may be further configured to estimate the return covariance associated with the estimated return channel, determine the beam coefficients of the beam based at least partially on the estimated return channel and return covariance, and apply the beam coefficients to their respective signal components to acquire the beam signal.

[0099] In some examples, the system may include a ground system comprising a plurality of gateways configured to receive representations of their respective signal components, and a beamformer, wherein the beamformer may be coupled to the plurality of gateways and configured to apply beam coefficients of the beam to the representations of their respective signal components to acquire a beam signal.

[0100] In some examples of the system, the first satellite may include a beamformer and be further configured to transmit a beam signal to a ground system.

[0101] In some examples of the system, a plurality of second satellites may be configured to detect a plurality of respective signal components of a plurality of signals originating from a plurality of geographical regions, the plurality of signals include signals, and the plurality of geographical regions include geographical regions, and a beamformer may be configured to form a plurality of beams associated with the plurality of geographical regions to acquire a plurality of beam signals based at least partially on a plurality of respective signal components and a plurality of estimated return channels, and the plurality of estimated return channels include estimated return channels.

[0102] In some examples of the system, the beamformer may be further configured to estimate return covariance associated with multiple geographic regions, determine beam coefficients of a beam based at least partially on the estimated return channel and return covariance, and apply the beam coefficients of a beam to multiple respective signal components to acquire multiple beam signals.

[0103] In some examples of the system, the first satellite may be configured to detect the direct signal component of the signal.

[0104] In some examples of the system, the beamformer may be further configured to acquire a beam signal based at least partially on the direct signal component.

[0105] In some examples of the system, the beamformer may be further configured to estimate a return channel estimated based at least partially on other signals received from one or more different geographic areas. In some examples of the system, the other signals include one or more reference signals transmitted by transmitters at known locations.

[0106] In some examples of the system, a plurality of second satellites include a first set of satellites in the first orbital plane of the second orbits. In some examples of the system, a plurality of second satellites include a second set of satellites in the second orbital plane of the second orbits.

[0107] In some examples, the system includes a processor configured to demodulate a beam signal. In some examples, the system includes a processor including a beamformer. In some examples of the system, the first trajectory may be a stationary trajectory.

[0108] A communication device is described. The communication device includes a processor, a memory coupled to the processor and containing instructions executable by the processor, the instructions cause the communication device to estimate a return channel from a geographical area—the return channel includes a first channel component between a first satellite and a plurality of second satellites and a second channel component between the plurality of second satellites and the geographical area—and to acquire a beam signal at least partially based on a plurality of signal components associated with a signal originating from the geographical area, wherein the plurality of signal components are relayed by each of the plurality of second satellites.

[0109] In some examples of communication devices, instructions for estimating return channels may be further executable by a processor to determine multiple return channels based at least partially on one or more other signals received from known geographic locations, and to interpolate the characteristics of the multiple return channels to estimate the characteristics of the return channels.

[0110] In some examples of communication devices, instructions may be further executable by a processor to obtain a representation of a plurality of signal components relayed by a plurality of second satellites and a representation of a direct signal component of a signal received from a first satellite from a geographic area, and a beam signal may be determined at least partially based on the representation of the plurality of signal components and the representation of the direct signal component.

[0111] In some examples of communication devices, instructions may be further executable by a processor to estimate the return covariance associated with a geographic area based at least partially on the return channel, and to determine the beam coefficients of the beam based at least partially on the return channel and the return covariance.

[0112] In some examples of communication devices, instructions for acquiring a beam signal may be further executable by a processor to apply beam coefficients of a beam to a representation of multiple signal components of a signal in order to acquire one or more beam signals.

[0113] In some examples of communication devices, instructions may be further executable by a processor to estimate a plurality of return channels from a plurality of geographic regions—where the plurality of return channels include return channels and the plurality of geographic regions include geographic regions—estimate return covariance at least partially based on the plurality of return channels, and determine a plurality of beam coefficients of a plurality of beams at least partially based on the plurality of return channels and return covariance.

[0114] In some examples of communication devices, instructions may be further executable by a processor to apply multiple beam coefficients of multiple beams to representations of multiple signal components associated with multiple signals originating from multiple geographical regions in order to acquire one or more beam signals, and one or more beam signals include beam signals.

[0115] It should be noted that these methods describe examples of implementation, and that operations and steps may be rearranged or otherwise modified to enable other implementations. In some examples, aspects from two or more methods may be combined. For example, each aspect of the methods may include steps or aspects of other methods, or other steps or techniques described herein.

[0116] The information and signals described in this specification may be represented using any of the various different technologies and techniques. For example, data, instructions, instructions, information, signals, bits, symbols, and chips that may be mentioned throughout this description may be represented by voltages, currents, electromagnetic waves, magnetic fields or magnetic particles, optical fields or particles, or any combination thereof.

[0117] The various exemplary blocks and modules described in connection with the disclosures in this specification may be implemented or performed using a general-purpose processor, a DSP, an ASIC, an FPGA or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described in this specification. A general-purpose processor may be a microprocessor, but in an alternative example, the processor may be any conventional processor, controller, microcontroller, or state machine. The processor may also be implemented as a combination of computing devices (e.g., a combination of a digital signal processor (DSP) and a microprocessor, multiple microprocessors, one or more microprocessors associated with a DSP core, or any other such configuration).

[0118] The functions described herein may be implemented in hardware, software executed by a processor, firmware, or any combination thereof. When implemented in software executed by a processor, the functions may be stored or transmitted as one or more instructions or code on a computer-readable medium. Other examples and embodiments are within the scope of this disclosure and the appended claims. For example, due to the nature of the software, the functions described herein may be implemented using software executed by a processor, hardware, firmware, hardwiring, or any combination thereof. Features implementing the functions may also be physically located at various locations, including distributed so that parts of the functions are implemented at different physical locations.

[0119] Computer-readable media include both non-transient computer storage media and communication media, including any medium that facilitates the transfer of a computer program from one place to another. Non-transient storage media may be any available medium that can be accessed by a general-purpose or special-purpose computer. By example, not limiting, non-transient computer-readable media may include RAM, ROM, electrically erasable programmable ROM (EEPROM), flash memory, compact disc read-only memory (CDROM), or other optical disc storage, magnetic disc storage, or other magnetic storage devices, or any other non-transient media, which can be used to carry or store desired means of program code in the form of instructions or data structures and can be accessed by a general-purpose or special-purpose computer or a general-purpose or special-purpose processor. Additionally, any connection is appropriately referred to as a computer-readable medium. For example, where software is transmitted from a website, server, or other remote source using coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technology such as infrared, radio, and microwave, coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technology such as infrared, radio, and microwave is included in the definition of the medium. As used herein, disk and disc include CD, laser disc, optical disc, digital versatile disc (DVD), floppy disk, and Blu-ray disc, wherein disk typically plays data magnetically, whereas disc plays data optically with a laser.Combinations of the above are also included within the category of computer-readable media.

[0120] As used herein, including in the claims, the word “or” as used in a list of items (e.g., a list of items followed by phrases such as “at least one of” or “one or more of”) indicates a comprehensive list such that, for example, a list of at least one of A, B, or C means A or B or C or AB or AC or BC or ABC (i.e., A, B, and C). Furthermore, as used herein, the phrase “based on” should not be interpreted as a reference to a closed set of conditions. For example, an exemplary step described as “based on condition A” may be based on both condition A and condition B without departing from the scope of this disclosure. In other words, as used herein, the phrase “based on” should be interpreted in the same way as the phrase “at least partially based on”.

[0121] In the attached drawings, similar components or features may have the same reference label. Additionally, various components of the same type may be distinguished by having a second label and a dash following the reference label to distinguish similar components. Where only the first reference label is used in this specification, the description may apply to any one of the similar components having the same first reference label, regardless of the second reference label or any other subsequent reference label.

[0122] The descriptions provided herein in connection with the attached drawings describe exemplary configurations and do not represent all examples that may be implemented or fall within the scope of the claims. The term “exemplary” as used herein means “serving as an example, case, or example,” rather than “preferred” or “advantageous over other examples.” The detailed description includes specific details for the purpose of providing an understanding of the described techniques. However, these techniques may be practiced without such specific details. In some instances, well-known structures and devices are illustrated in block diagram form to avoid obscuring the concepts of the described examples.

[0123] The description in this specification is provided to enable those skilled in the art to make or use the present disclosure. Various modifications to the present disclosure will be obvious to those skilled in the art, and the general principles defined in this specification may be applied to other variations without departing from the scope of the present disclosure. Accordingly, the present disclosure is not limited to the examples and designs described in this specification, but should be given the broadest scope corresponding to the principles and novel features as disclosed in this specification.

Claims

Claim 1 As a system for communication, a first satellite (105) in a first orbit; a plurality of second satellites (115) in second orbits lower than the first orbit - the plurality of second satellites (115) each have antennas that illuminate each part of a geographical area (140), and are configured to detect each signal component (125) of a signal originating from the geographical area (140) and transmit each relayed signal component (110) obtained from each signal component (125) to the first satellite (105) -; A system comprising a beamformer (155, 190) located on a ground system (130) or the first satellite (105), wherein the beamformer (155, 190) is configured to form a beam associated with the geographical area (140) to acquire a beam signal based at least partially on the respective relayed signal components (110) and an estimated return channel, wherein the estimated return channel comprises channel components between the geographical area (140) and the plurality of second satellites (115). Claim 2 A system according to claim 1, wherein the beamformer (155) is located in the ground system (130), and the first satellite (105) comprises a plurality of transponders (175), each transponder (175) of the plurality of transponders (175) is configured to receive the respective relayed signal components (110) transmitted by the plurality of second satellites (115) and to transmit a representation of the respective relayed signal components (110) to the ground system (130), and the beamformer (155) is further configured to form the beam signal at least partially based on the representation of the respective relayed signal components (110) which is at least partially based on the respective relayed signal components (110). Claim 3 A system according to claim 1 or 2, wherein each of the plurality of second satellites (115) comprises at least one repeater (160), and the repeaters (160) of the plurality of second satellites (115) are configured to amplify the detected respective signal components (125) to obtain the respective relayed signal components (110) in order to transmit the respective relayed signal components (110) to the first satellite (105). Claim 4 In paragraph 3, the system is such that at least one repeater (160) is a non-processing repeater. Claim 5 A system according to paragraph 3, wherein the repeaters (160) of the plurality of second satellites (115) are configured to transmit their respective relayed signal components (110) at the same frequency as the respective signal components (125) detected by the repeaters (160). Claim 6 A system according to paragraph 3, wherein the repeaters (160) of the plurality of second satellites (115) are configured to transmit their respective relayed signal components (110) at a frequency different from the respective signal components (125) detected at the repeaters (160). Claim 7 In paragraph 3, a system in which each of the repeaters (160) of the plurality of second satellites (115) is configured to transmit their respective relayed signal components at their respective frequencies of the plurality of frequencies. Claim 8 In claim 1, the beamformer (155) is located in the ground system (130), and the respective signal components (125) detected by the plurality of second satellites (115) are detected through a first channel between the plurality of second satellites (115) and the geographical area (140), and the respective relayed signal components (110) are transmitted to the first satellite (105) through a second channel between the plurality of second satellites (115) and the first satellite (105), and the first satellite (105) is configured to transmit a representation of the respective relayed signal components (110) to the ground system (130) through a third channel between the first satellite (105) and the ground system (130), and the beamformer (155) is configured to form the beam signal at least partially based on the representation of the respective relayed signal components (110) which is at least partially based on the respective relayed signal components (110). A system that is configured. Claim 9 A system according to claim 1, wherein the beamformer (155, 190) is further configured to estimate a return covariance associated with the estimated return channel; and to determine beam coefficients of the beam based at least partially on the estimated return channel and the return covariance. Claim 10 In claim 1, the beamformer (155) is located in the ground system (130), and the system further comprises the ground system (130), wherein the ground system (130) comprises at least one gateway (135) configured to receive a representation of each relayed signal component (110); and the beamformer (155), wherein the beamformer (155) is coupled to the at least one gateway (135) and configured to apply beam coefficients of the beam to the representation of each relayed signal component (110) in order to acquire the beam signal, and the representation of each relayed signal component (110) is at least partially based on each relayed signal component (110). Claim 11 A system according to claim 1, wherein the beamformer (190) is positioned on the first satellite (105) and estimates the return covariance associated with the estimated return channel; determines the beam coefficients of the beam based at least partially on the estimated return channel and the return covariance; and further configured to apply the beam coefficients to the respective relayed signal components (125) to obtain the beam signal. Claim 12 In paragraph 11, the system is configured such that the first satellite (105) transmits the beam signal to the ground system (130). Claim 13 In claim 1, the beamformer (190) is positioned on the first satellite (105); the plurality of second satellites (115) are configured to detect a plurality of signal components (125) of a plurality of signals originating from a plurality of geographical regions (140) and to transmit a plurality of relayed signal components (110) obtained from the respective signal components (125) to the first satellite (105), wherein the plurality of signals include the signal, and the plurality of geographical regions (140) include the geographical region (140); the beamformer (190) is configured to form a plurality of beams associated with the plurality of geographical regions (140) to obtain a plurality of beam signals based at least partially on the plurality of relayed signal components (110) and a plurality of estimated return channels, wherein the plurality of beams include the beam, the plurality of beam signals include the beam signal, and the plurality of estimated return channels include the estimated return channels, a system. Claim 14 In paragraph 13, the beamformer (155, 190) is further configured to estimate the return covariance associated with the plurality of geographical regions (140); and to determine the beam coefficients of the beam based at least partially on the estimated return channel and the return covariance. Claim 15 In claim 1, the system is configured such that the first satellite (105) detects the direct signal component (120) of the signal. Claim 16 In claim 15, the system is further configured such that the beamformer (155, 190) acquires the beam signal at least partially based on the direct signal component (120). Claim 17 A system according to claim 1, wherein the beamformer (155, 190) is further configured to determine the estimated return channel based at least partially on other signals received from one or more other geographical areas (140). Claim 18 In paragraph 17, the system comprises one or more reference signals transmitted by transmitters at known locations, wherein the other signals are other signals. Claim 19 In claim 1, the plurality of second satellites (115) comprises a first set of satellites in the first orbital plane (405-1) of the second orbits, in a system. Claim 20 In claim 19, the system further comprises a second set of satellites of the second orbit plane (405-2) of the plurality of second satellites (115). Claim 21 A system according to claim 1, further comprising a processor (153, 187) configured to demodulate the beam signal. Claim 22 A system according to claim 1, further comprising a processor (153, 187) including the beamformer (155, 190). Claim 23 A system according to claim 1, wherein the first orbit is a geostationary orbit. Claim 24 As a method for communication, the method comprises the step of obtaining beam coefficients of a beam associated with the geographical area (140) based at least partially on an estimated return channel comprising a first channel component between the geographical area (140) and a plurality of second satellites (115) and a second channel component between the plurality of second satellites (115) and a first satellite (105) - wherein the plurality of second satellites are in a second orbit lower than the first orbit of the first satellite (105) and each have antennas that illuminate their respective parts of the geographical area (140) -; A method comprising the step of forming a beam associated with the geographical area (140) to obtain a beam signal at least partially based on each relayed signal component (110) obtained from a plurality of signal components (125) of a signal originating from the geographical area (140) by a beamformer (155, 190) located in the ground system (130) or the first satellite (105), wherein each relayed signal component (110) is obtained from the plurality of signal components (125) by each of the plurality of second satellites (115) and transmitted to the first satellite (105) by each of the plurality of second satellites (115). Claim 25 In paragraph 24, the beamformer (190) is positioned on the first satellite (105), and the method further comprises the step of receiving each of the relayed signal components (110) from the plurality of second satellites (115), wherein the beam signal is obtained at least partially based on applying the beam coefficients to each of the relayed signal components (110). Claim 26 In claim 24, the beamformer (155) is located in the ground system (130), and the method further comprises the steps of: receiving each of the relayed signal components (110) from the plurality of second satellites (115) by the first satellite (105); and transmitting a representation of each of the relayed signal components (110) to the ground system (130), wherein the beamformer (155) forms the beam at least partially based on the representation of each of the relayed signal components (110) which is at least partially based on each of the relayed signal components (110). Claim 27 A method according to claim 24, further comprising the step of receiving each of the relayed signal components (110) from the plurality of second satellites (115). Claim 28 In paragraph 27, the method wherein each of the relayed signal components (110) is received from the plurality of second satellites (115) at the same frequency as the signal originating from the geographical area (140) is detected at the plurality of second satellites (115). Claim 29 In paragraph 27, the method wherein each of the relayed signal components (110) is received from the plurality of second satellites (115) at one or more frequencies different from the signal originating from the geographical area (140) detected at the plurality of second satellites (115). Claim 30 A method comprising, in any one of claims 24 to 29, further a step of estimating the return channel from the geographical area (140) to obtain the estimated return channel. Claim 31 In claim 30, the step of estimating the return channel of the geographical area (140) comprises: determining a plurality of return channels based at least partially on one or more other signals received from known geographical locations; and interpolating the characteristics of the plurality of return channels to estimate the characteristics of the return channels. Claim 32 In paragraph 31, the method comprises one or more other signals including one or more reference signals transmitted by transmitters at the known geographical locations. Claim 33 A method according to any one of claims 24 or 27 through 29, wherein the beamformer (155) is located in the ground system (130), and the method further comprises the step of obtaining a representation of each relayed signal component (110) transmitted by the plurality of second satellites (115) and a representation of the direct signal component (120) of the signal received from the first satellite (105) in the geographical area (140), wherein the beamformer (155) forms the beam at least partially based on the representation of each relayed signal component (110) which is at least partially based on each relayed signal component (110) and the representation of the direct signal component (120) which is at least partially based on the direct signal component (120). Claim 34 A method according to claim 24, further comprising the steps of: estimating a return covariance associated with the geographical area (140) based at least partially on the return channel; and determining the beam coefficients of the beam based at least partially on the return channel and the return covariance. Claim 35 In claim 26, the step of acquiring the beam signal comprises the step of applying the beam coefficients of the beam to the representation of the respective relayed signal components (110) of the signal in order to acquire the beam signal. Claim 36 A method according to claim 24, further comprising the step of estimating a plurality of return channels from a plurality of geographical regions (140) - wherein the plurality of return channels include the return channels and the plurality of geographical regions (140) include the geographical regions (140) -; and the step of estimating a return covariance based at least partially on the plurality of return channels. Claim 37 In claim 24, the beamformer is located in the ground system (130), and the method comprises: a step of estimating a plurality of return channels from a plurality of geographical regions (140) - the plurality of return channels include the return channels, and the plurality of geographical regions (140) include the geographical regions (140) -; a step of estimating a return covariance based at least partially on the plurality of return channels; a step of determining a plurality of beam coefficients of a plurality of beams based at least partially on the plurality of return channels and the return covariance - the plurality of beam coefficients include the beam coefficients, and the plurality of beams include the beams -; A method further comprising the step of applying the plurality of beam coefficients of the plurality of beams to expressions of each of the relayed signal components (110) associated with a plurality of signals originating from the plurality of geographical regions (140) in order to obtain one or more beam signals, wherein the one or more beam signals include the beam signal, and the expressions of each of the relayed signal components (110) are at least partially based on each of the relayed signal components (110). Claim 38 A ground system (130) comprises a beamformer (155), wherein the beamformer (155) obtains beam coefficients of a beam associated with the geographical area (140) based at least partially on an estimated return channel comprising a first channel component between the geographical area (140) and a plurality of second satellites (115) and a second channel component between the plurality of second satellites (115) and a first satellite (105) - wherein the plurality of second satellites are in a second orbit lower than the first orbit of the first satellite (105) and each have antennas illuminating their respective parts of the geographical area (140) -; A ground system (130) configured to form a beam associated with the geographical area (140) to obtain a beam signal based at least partially on each relayed signal component (110) obtained from a plurality of signal components (125) of a signal originating from the geographical area (140), wherein each relayed signal component (110) is obtained from the plurality of signal components (125) by each of the plurality of second satellites (115) and transmitted to the first satellite (105) by each of the plurality of second satellites (115). Claim 39 In paragraph 38, the ground system (130) is further configured to receive a representation of each of the relayed signal components (110) from the first satellite (105), and the beamformer (155) is further configured to form the beam signal at least partially based on the representation of each of the relayed signal components (110) which is at least partially based on each of the relayed signal components (110), the ground system (130). Claim 40 In claim 38 or 39, the ground system (130) is further configured such that the beamformer (155) estimates the return channel from the geographical area (140) to obtain the estimated return channel. Claim 41 In paragraph 40, to estimate the return channels, the beamformer (155) determines a plurality of return channels based at least partially on one or more other signals received from known geographic locations; and the ground system (130) is further configured to interpolate the characteristics of the plurality of return channels to estimate the characteristics of the return channels. Claim 42 In claim 38, the beamformer (155) is further configured to obtain a representation of each of the relayed signal components (110) transmitted by the plurality of second satellites (115) and a representation of the direct signal component (120) of the signal received from the first satellite (105) in the geographical area (140), and the beamformer (155) is further configured to form the beam signal at least partially based on the representation of each of the relayed signal components (110) and at least partially based on the representation of the direct signal component (120). Claim 43 In paragraph 38, the beamformer (155) is further configured to estimate the return covariance associated with the geographic area (140) based at least partially on the return channel; and to determine the beam coefficients based at least partially on the return channel and the return covariance, the ground system (130). Claim 44 In paragraph 39, the beamformer (155) is further configured to apply the beam coefficients to the representation of the respective relayed signal components (110) of the signal in order to acquire the beam signal, the ground system (130). Claim 45 In paragraph 39, the beamformer (155) is further configured to estimate a plurality of return channels from a plurality of geographical regions (140)—the plurality of return channels include the return channels, and the plurality of geographical regions (140) include the geographical regions (140)—; estimate a return covariance based at least partially on the plurality of return channels; and determine a plurality of beam coefficients of a plurality of beams based at least partially on the plurality of return channels and the return covariance, wherein the plurality of beam coefficients include the beam coefficients, and the plurality of beams include the beams, ground system (130). Claim 46 In paragraph 45, the beamformer (155) is further configured to apply the plurality of beam coefficients to expressions of the respective relayed signal components (110) associated with the plurality of signals originating from the plurality of geographical areas (140) in order to acquire one or more beam signals, and the one or more beam signals include the beam signal, ground system (130). Claim 47 A first satellite (105) comprises a beamformer (190), wherein the beamformer (190) obtains beam coefficients of a beam associated with the geographical area (140) based at least partially on an estimated return channel comprising a first channel component between the geographical area (140) and a plurality of second satellites (115) and a second channel component between the plurality of second satellites (115) and the first satellite (105) - wherein the plurality of second satellites are in a second orbit lower than the first orbit of the first satellite (105) and each have antennas illuminating their respective parts of the geographical area (140) -; A first satellite (105) configured to form a beam associated with the geographical area (140) to obtain a beam signal based at least partially on each relayed signal component (110) obtained from each of the signal components (125) of the signal originating from the above beam coefficients and the geographical area (140), wherein each of the relayed signal components (110) is obtained from the plurality of signal components (125) by each of the plurality of second satellites (115) and transmitted to the first satellite (105) by each of the plurality of second satellites (115). Claim 48 In paragraph 47, the beamformer (190) is configured to estimate the return channel from the geographical area (140) in order to obtain the estimated return channel, the first satellite (105). Claim 49 In claim 47, to estimate the return channels, the beamformer (190) determines a plurality of return channels based at least partially on one or more other signals received from known geographical locations; and the first satellite (105) is configured to interpolate the characteristics of the plurality of return channels to estimate the characteristics of the return channels. Claim 50 In paragraph 47, the beamformer (190) is configured to estimate the return covariance associated with the geographical area (140) based at least partially on the return channel; and to determine the beam coefficients based at least partially on the return channel and the return covariance, the first satellite (105). Claim 51 In paragraph 47, the beamformer (190) estimates a plurality of return channels from a plurality of geographical regions (140) - the plurality of return channels include the return channels, and the plurality of geographical regions (140) include the geographical region (140) -; and the first satellite (105) is configured to estimate the return covariance based at least partially on the plurality of return channels. Claim 52 In claim 47, the first satellite (105) further comprises a transponder (175), said transponder (175) configured to receive each of the relayed signal components (110) from the plurality of second satellites (115), said beam signal obtained at least partially based on applying the beam coefficients to each of the relayed signal components (110). Claim 53 In claim 47, a first satellite (105) further comprises a transponder (175), said transponder (175) configured to receive each of the relayed signal components (110) from the plurality of second satellites (115). Claim 54 In paragraph 53, the transponder (175) is further configured to receive the respective relayed signal components (110) from the plurality of second satellites (115) at one or more frequencies different from the signal originating from the geographical area (140) detected at the plurality of second satellites (115). Claim 55 In paragraph 53, the transponder (175) is further configured to receive the respective relayed signal components (110) from the plurality of second satellites (115) at the same frequency as the signal originating from the geographical area (140) is detected at the plurality of second satellites (115).

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