Satellite beam tracking of mobile individual terminals

Abstract

Methods, systems, and devices for satellite beam tracking of individual mobile terminals are described. Communication services may be provided to the mobile terminals via beamformed spot beams that track the movement of the mobile terminals. To generate beamformed spot beams, channel state information based on the mobile terminals' positions may be determined based on measurements of signals communicated with the mobile terminals. Beamforming coefficients based on the channel state information may be applied to position the beamformed spot beams at the center of each mobile terminal's position. The beamforming coefficients may be periodically modified so that the beamformed spot beams remain at the center of the mobile terminal's moving position.

Description

Technical Field

[0001] The following generally relates to satellite communication and includes satellite beam tracking of mobile individual terminals.

Background Art

[0002] Communication devices can communicate with each other using wired connections, wireless (e.g., radio frequency (RF)) connections, or both. Wireless communication between devices can be performed using a wireless spectrum designated for a service provider, a wireless technology, or both. In some examples, the amount of information that can be communicated via a wireless communication network is based on the amount of wireless spectrum designated for the service provider and the amount of frequency reuse within the area where the service is provided. In satellite communication, beamforming can be used to establish beams to increase frequency reuse, but there are challenges in achieving a high level of frequency reuse in a satellite communication system that employs beamforming. [[ID=!4]]

Summary of the Invention

[0003] The described technology relates to improved methods, systems, devices, and devices that support satellite beam tracking of mobile individual terminals. For example, communication services can be provided to a mobile terminal via respective beamformed spot beams that track the movement of the mobile terminal. To generate the beamformed spot beams, channel state information based on the position of the mobile terminal can be determined based on measurements of signals communicated with the mobile terminal. Beamforming coefficients based on the channel state information can be applied such that the beamformed spot beams are centered on the position of each mobile terminal. The beamforming coefficients can be changed periodically or when the received signal quality of the spot beam does not meet a threshold so that the beamformed spot beam stays centered on the moving position of the mobile terminal.

Brief Description of the Drawings

[0004] [Figure 1]Figure 1 shows an embodiment of a satellite communication system that supports satellite beam tracking of a mobile individual terminal, according to the embodiments disclosed herein. [Figure 2A] Figure 2A shows an example of resources for a satellite communication system that supports satellite beam tracking of a mobile individual terminal, according to the embodiments disclosed herein. [Figure 2B] Figure 2B shows an example of resources for a satellite communications system that supports satellite beam tracking of a mobile individual terminal, according to the embodiments disclosed herein. [Figure 3] Figure 3 shows an embodiment of a satellite communication system that supports satellite beam tracking of a mobile individual terminal, according to the embodiments disclosed herein. [Figure 4] Figure 4 shows an embodiment of another satellite communications system that supports satellite beam tracking of a mobile individual terminal, according to the embodiments disclosed herein. [Figure 5] Figure 5 shows an example of a timing diagram supporting satellite beam tracking of a mobile individual terminal according to the embodiments disclosed herein. [Figure 6] Figure 6 is a block diagram of a beam manager supporting satellite beam tracking of a mobile individual terminal according to an embodiment disclosed herein. [Figure 7] Figure 7 is a block diagram of a beam manager supporting satellite beam tracking of a mobile individual terminal according to an embodiment disclosed herein. [Figure 8] Figure 8 is a flowchart illustrating a method(s) for supporting satellite beam tracking of a mobile individual terminal according to an embodiment disclosed herein. [Modes for carrying out the invention]

[0005] Inter-beam handoff of mobile terminals can cause disruptions to end users due to packet loss or delay, and changes in beam congestion levels and capabilities. In some satellite communication systems, inter-beam handoff of mobile terminals may be based on the relative position of the mobile terminal within an adjacent fixed beam, and may not take inter-beam interference into account. For example, handoff may occur when a mobile terminal is located within the overlapping edge of the coverage area of ​​an adjacent beam. In such locations, the signal-to-noise ratio (SNR) of the mobile terminal is low (compared to, for example, when the mobile terminal is in the center of the coverage area), and performance degradation may occur. To compensate for this, a lower coding rate with more redundancy may be set. However, this reduces the overall communication speed and is inefficient. Furthermore, all edge portions of the coverage area of ​​one beam must overlap with at least one of the other beams, requiring wide beams and significant beam overlap.

[0006] On mobile terminals traveling at slow speeds, such as automobiles or ships, handoffs may occur relatively infrequently, and the resulting performance degradation or failures may have little overall impact on communications related to the mobile terminals. However, on mobile terminals traveling at high speeds, such as aircraft, inter-beam handoffs occur frequently, leading to performance degradation and failures that can have a greater impact on communications. In any case, reducing the number of inter-beam handoffs and thus the number of associated performance degradations and failures would be beneficial.

[0007] This section describes a technique for tracking individual mobile terminals using separate beams. Beam-based mobile terminal tracking can reduce the number of inter-beam handoffs associated with the mobile terminal. This can reduce the number of performance degradations and interruptions caused by handoffs, which can be particularly beneficial for mobile terminals deployed on high-speed transport vehicles (such as aircraft). Furthermore, by tracking individual mobile terminals, the tracking beams do not always need to overlap, potentially allowing for smaller and narrower beams than current systems. In some cases, the mobile terminal can be positioned in the center of the tracking beam, enabling a higher signal-to-noise ratio (SNR) for the mobile terminal, potentially resulting in higher overall communication speed and efficiency than current systems.

[0008] Furthermore, we will describe a technique for performing beam-to-beam handoffs of mobile terminals based on beam interference levels. This may enable handoffs to occur when the interference level rises to a certain level, such as a threshold, rather than based on relative position, thereby reducing the frequency and number of handoffs associated with mobile terminals.

[0009] The aspects of this disclosure are first described in the context of satellite communication systems. The aspects of this disclosure are further illustrated and described with reference to device diagrams, system diagrams, block diagrams, and flowcharts related to satellite beam tracking of mobile individual terminals.

[0010] Figure 1 shows an embodiment of a satellite communications system 100 that supports satellite beam tracking of individual mobile terminals according to the embodiments described herein. The satellite communications system 100 may include a ground network 135 and a satellite network 101 configured to track one or more mobile terminals 120 and provide communications services.

[0011] The ground network 135 may include a collection of earth stations 170 having access nodes 140 configured to communicate with the satellite network 101 via feeder links 132 (e.g., one or more satellite beams). The access nodes 140 may be coupled to access node transceivers 145 configured to process signals to be received from and transmitted through the corresponding access node 140(s). The access node transceivers 145 may also be configured to interface with, for example, the network 125 (e.g., the Internet) and with network devices 130 (e.g., a network operations center, a satellite and gateway terminal command center, or other central processing center or device) that can provide an interface for communicating with the network 125.

[0012] The terrestrial network may also include a beam manager 175 that tracks the mobile terminal 120 when communication services are provided to the terminal. The beam manager 175 may use beamformed spot beams associated with a reference terminal, as discussed herein. For example, the tracking of the mobile terminal discussed herein may be controlled by the beam manager 175. The beam manager 175 may obtain information (e.g., related to the satellite network 101 and terminal 120) from the satellite network 101 (e.g., via the feeder link 132 and access node 140) to perform control, and may accordingly transmit commands (e.g., via the access node and feeder link) (e.g., to the satellite network 101 and / or terminal 120).

[0013] Although described herein as a single device, the beam manager 175 can alternatively be distributed across various elements of an entire system, e.g., a satellite network and / or a ground network. For example, the beam manager 175 may be incorporated into one or more devices in the ground network (e.g., network device 130 or access node transceiver 145), or one or more devices in the satellite network (e.g., within a single satellite 105 or distributed across multiple satellites), or a combination of devices in the ground and satellite networks. In some embodiments, a first portion of the beam manager 175 may be located in the ground network 135, and a second portion may be located in the satellite network 101.

[0014] Terminal 120 may include various devices configured to communicate signals with the satellite network 101. Although Terminal 120 is illustrated as being mounted on an aircraft, Terminal 120 may include a fixed terminal (e.g., a fixed terminal on the ground), a mobile terminal mounted on a mobile platform (e.g., a boat, aircraft, ground transport, etc.), or a combination of a fixed terminal and a mobile terminal. Terminal 120 may communicate data and information with the access node 140 via the satellite network 101. The data and information may be communicated to destination devices such as network device 130, or to several other devices or distributed servers associated with the network 125.

[0015] The satellite network 101 may include one or more satellites 105 (e.g., a single satellite or a network of satellites) deployed in space orbit (e.g., low Earth orbit, medium Earth orbit, geosynchronous orbit, geostationary orbit, etc.). Each satellite 105 included in the satellite network 101 may have one or more antennas 105 (e.g., a single antenna or an antenna array). In some embodiments, one or more satellites 105 having multiple antennas may each include one or more antenna panels, each including an array of evenly distributed antennas (which may also be called antenna elements). In some embodiments, a satellite may have an antenna array including antennas that are unevenly distributed over a wide area. The ground network 135 may also include access nodes 140, each including multiple antennas or antenna array elements.

[0016] Terminal 120 may include an antenna assembly, which may also include various hardware for mounting the antenna. The antenna assembly may also include circuitry and / or a processor for performing conversions (e.g., frequency conversion, modulation / demodulation, multiplexing / demultiplexing, filtering, forwarding, etc.) between radio frequency (RF) satellite communication signals and satellite terminal communication signals transmitted between the antenna and the satellite terminal receiver. In the case of a mobile terminal, the antenna assembly may be mounted on the outside of the mobile platform (e.g., on the outside of the aircraft fuselage). Furthermore, or alternatively, terminal 120 may include a transceiver, which may be mounted inside or outside the mobile platform, and may include circuitry and / or a processor for performing various RF signal operations (e.g., receiving, frequency conversion, modulation / demodulation, multiplexing / demultiplexing, etc.).

[0017] The satellite network 101 may have a large aperture size that can be widened by an antenna array or multiple satellites of the satellite network 101. The satellite communication system 100 may use one or more satellites to support beamforming techniques within the coverage area 155 of the satellite communication system to increase the utilization rate of resources used for communication. The beam manager 175 may employ beamforming, including the use of multiple-input multiple-output (MIMO) techniques, to improve spectral efficiency by utilizing multipath signal propagation and transmitting or receiving multiple signals over different spatial layers on the same frequency resource. The beam manager 175 may transmit multiple signals by a transmitting device (e.g., satellite 105) through a set of antennas according to a set of weighting coefficients, for example. Similarly, multiple signals may be received by a receiving device (e.g., terminal 120) through a set of antennas according to a set of weighting coefficients. Each of the multiple signals may be associated with a separate spatial stream and may carry bits associated with the same data stream (e.g., the same codeword) or different data streams (e.g., different codewords).

[0018] In some embodiments, some or all of the antenna elements on satellite 105, ground network 135, and / or terminal 120 may be arranged as an array of constitutive receive and / or transmit feed elements that cooperate to enable various examples of onboard beamforming (OBBF), ground-based beamforming (GBBF), end-to-end beamforming, or other types of beamforming. In a GBBF implementation, there may be multiple transmit or receive antennas on the ground system access node(s).

[0019] The beam manager 175 can determine weighting coefficients to apply to a set of antennas. For example, if N spatial layers are formed, the beam manager 175 can utilize an (M × N) MIMO matrix, where M may represent the number of antennas in the set of antennas. In some embodiments, M may be equal to N. The beam manager 175 may also determine the MIMO matrix based on a channel matrix, and the MIMO matrix may be used to separate different spatial layers of a channel. In some embodiments, the beam manager 175 may select weighting coefficients to enhance signals transmitted using different spatial layers while reducing interference from signals transmitted in other spatial layers. Thus, by processing the signals received at each antenna (e.g., signals received in the set of antennas) using the MIMO matrix, it may be possible to output multiple signals, each of which may correspond to one of the spatial layers. In some embodiments, the weighting coefficients used for MIMO communication may be called beam coefficients or beamforming coefficients, and the multiple spatial layers may be called beams or spot beams.

[0020] The beam manager 175 can determine the elements of the MIMO matrix used to form the spatial layers of the channel based on the channel sounding probe. The channel sounding probe may include a reference signal that is periodically transmitted between the satellite network 101 and a device (e.g., terminal 120) coupled to the satellite network. For example, the channel sounding probe may be periodically transmitted from the terminal 120 to the satellite 105, or from the satellite to the terminal, or in both directions, and may include a sequence known to the transceiver (e.g., based on a terminal identifier or other parameters known to the transceiver). The receiving device (e.g., terminal or satellite) can evaluate the connection by correlating the received channel sounding probe with the signal expected for the received channel sounding probe (e.g., determining signal strength, interference, etc.) and make a decision based thereon. Due to the periodicity of the signal, the receiving device can know the timing at which the signal should be received.

[0021] The beam manager 175 can use beamforming techniques to shape or direct a communication beam along the spatial path between one or more satellites and the mobile terminal 120 within a geographical area. The beam manager 175 determines the weighting factors for the antenna elements of the antenna array such that signals propagating in a specific direction with respect to the antenna array undergo constructive interference while other signals undergo destructive interference, thereby forming a communication beam by combining the signals transmitted from the antenna elements or received by the antenna elements. Thus, beamforming can be used to transmit signals having energy focused in the direction of the communication beam and receive signals reaching the direction of communication with increased signal power (relative to the absence of beamforming). The beam manager 175 can use the weighting factors to apply an amplitude offset, a phase offset, or both to the signals carried through the antenna.

[0022] In some embodiments, the weighting coefficients applied to the antennas can be used to form a plurality of beams each associated with a different direction, and the plurality of beams can be used to simultaneously communicate a plurality of signals having the same frequency to different user terminals. This is sometimes referred to as multi-user MIMO. The weighting coefficients used for beamforming can be referred to as beam coefficients, and the plurality of signals can be referred to as beam signals. The resulting beams can be referred to herein as beamformed spot beams, spot beams, or beams.

[0023] The beam manager 175 can calculate the amplitude and phase of each weighting coefficient taking into account the geometry and position of the antenna array and the mirror, and the desired beam position. However, due to inaccuracies (e.g., satellite position, array orientation, geometry, atmospheric scintillation effects, etc.), such an approach may not be practical. Instead, the beam manager 175 can calculate the weighting coefficients using continuous or periodic measurements of the MIMO propagation channel characteristics (e.g., the channel in pairs from each system antenna element to each terminal antenna element), and can adjust the weighting coefficients based on the changing channel characteristics. The measured MIMO channel characteristics can include the gain and phase response in pairs, as well as the noise level, and can be referred to as MIMO channel state information (CSI). When MIMO CSI becomes available, the beam manager 175 can derive the weighting coefficients by solving a set of equations or applying a set of adaptive formulas. Various beamformer calculation and adaptation techniques such as the minimum mean square error (MMSE) beamformer, zero-forcing beamformer, MIMO sphere decoder, etc. can be used.

[0024] MIMO CSI measurements may involve the coordination of at least one terminal for each beam. The situation may differ in the forward link direction (satellite to terminal) and the return link direction (terminal to satellite). In the return link, each terminal may transmit a channel probing signal orthogonal to the channel probing signals of other terminals. The satellite may determine which channel probing signals were transmitted from each terminal and process those signals to estimate the channel parameters of the channel corresponding to that terminal. Thus, MIMO CSI in the return link can be calculated locally on the satellite side for terminals transmitting channel probing signals. In the forward link, on the other hand, the satellite may transmit channel probing signals. Different antenna elements may transmit signals orthogonal to each other. Each terminal assigned the task of calculating MIMO CSI can do this by processing the probing signals corresponding to each transmitting antenna element. Furthermore, each such terminal can send the MIMO CSI back to the satellite using the return link control channel.

[0025] The spot beams thus generated can be adjusted to match the MIMO CSI provided by user terminals, and each beam can illuminate the direction of each such terminal. Each beam has a finite coverage area 160 (e.g., several kilometers in diameter) and can therefore illuminate additional terminals that may be located near the CSI generating terminal. These additional terminals may not provide CSI because they may unnecessarily increase the CSI reporting channel overhead. The terminal used to provide MIMO CSI for each beam can be considered a reference terminal for that beam. In some embodiments, the beam coverage area 160 can be determined based on the carrier wavelength and the aperture diameter. The coverage area 160 may correspond to a footprint where, for example, the beam power level is above a threshold, or the power level drop-off away from the beam center is below a threshold (e.g., 3 decibels (dB) or 6 dB). In some embodiments, the coverage area 160 may be based on the beam width.

[0026] In some embodiments, one or more aircraft-based terminals 120 may be sufficiently far apart from each other and from other aircraft so that the beam manager 605 can use a separate beam for each of the one or more terminals. In some embodiments, two or more terminals 120 may be close together (e.g., at an airport) so that the beam manager 605 can illuminate the terminals with the same beam. In the former case, each terminal may be a reference terminal for its beam, and in the latter case, one of several terminals may be a reference terminal for the beam.

[0027] As the mobile terminal 120 moves through the airspace, the MIMO CSI changes, which may alter the beam's direction. The beam manager 175 may adjust the beam direction based on the altered MIMO CSI to ensure the reference terminal remains at or near the center of the beam. Thus, as the reference terminal moves, the beam may follow its movement, as will be further described herein.

[0028] The beam manager 175 may associate beamformed spot beams with a set of resources in the satellite communication system 100. The set of resources may include, for example, frequency resources, time resources, and polarization resources. For example, a given frequency range of the satellite communication system 100 may include frequency resources or channels, and a given time may include different repetition time slots. For example, the beam manager 175 may use a frequency channel to transmit a signal (e.g., a modulated signal transmitted over the beamformed spot beam) in one of the repetition time slots. In this way, beamformed spot beams can spatially overlap without interference if they are associated with different combinations of frequency / time resources. Furthermore, the beam manager 175 may use multiple polarizations so that two beamformed spot beams can spatially overlap without interference if they are associated with different polarizations. Thus, beamformed spot beams can spatially overlap without interference if they are associated with different combinations of resources (e.g., combinations of frequency channels / time slots / polarization). These different combinations may be known as resource elements that together form a set of resource elements that the beam manager 175 can use to communicate signals over the beam.

[0029] As described herein, the beam manager 175 may adjust the individual coverage areas or footprints of beamformed spot beams (for example, by adjusting weighting coefficients) to track each mobile terminal (e.g., reference terminal) (e.g., move in coordination). This allows communication services associated with a mobile terminal to be provided via the same beamformed spot beam as the mobile terminal moves within the coverage area of ​​the satellite communication system. This can reduce the number of inter-beam handoffs of mobile terminals and mitigate performance degradation and communication failures that may result from inter-beam handoffs. For example, inter-beam handoffs require coordination between the beam handing off the terminal and the beam receiving the terminal, and may require communication across several communication layers to transfer terminal information between access points (e.g., gateways, gateway modems) that serve the beams, and to verify the transfer. This can result in performance degradation and inter-beam communication failures.

[0030] For example, competition can occur between beams tracking a mobile terminal when two movable beam-formed spot beams spatially overlap while using the same resource elements (e.g., the same frequency channel, time slot, and polarization). However, such competition can be resolved using the competition avoidance procedure described here. For example, when such competition occurs (e.g., based on the inter-beam interference metric meeting a threshold), the beam manager 175 may change one of the competing mobile terminals to a different resource element. As a result, there is little to no performance degradation. Also, since competition avoidance only involves a single beam (e.g., without communication between access points providing different beams), there is no communication disruption associated with inter-beam handoff.

[0031] Furthermore, even if the reference terminal moves, it can remain in a central position within the beam's coverage area. This can help maintain a high SNR for the reference terminal, and potentially result in higher overall communication speed and efficiency associated with the reference terminal.

[0032] Figure 2A shows an example of resource 200-a of a satellite communications system supporting satellite beam tracking of a mobile individual terminal, according to the embodiments described herein. Resource 200-a may correspond to frequency division of the satellite communications system. For example, a frequency range 205 (e.g., a frequency band) may consist of a set of different frequency resources or frequency channels 210 (e.g., frequency channel 210-a, frequency channel 210-b, frequency channel 210-c, frequency channel 210-d) that transmit signals between the satellite network and the terminal. Resource 200-a may correspond to a frequency channel 210 of frequency range 205.

[0033] Each frequency channel 210 may transmit a signal associated with a single terminal (for example, at one time). For example, each frequency channel 210 may transmit a single modulated signal. Information (e.g., data, control information) may be modulated into a modulated signal using various single-carrier or multi-carrier modulation techniques (e.g., orthogonal frequency division multiplexing (OFDM), direct sequence spread spectrum (DSSS), linear pre-coded OFDM (LP-OFDM)). A beamformed spot beam may be associated with one or more frequency channels 210 to provide communication and tracking to a mobile terminal (e.g., by a beam manager 175), as discussed herein.

[0034] In the embodiment shown in Figure 2A, resource 200-a may correspond to a frequency channel 210. That is, each frequency channel 210 may be a separate resource 200-a. Since there are no other types of resources, in some embodiments, separate resources can also be resource elements. Thus, in this embodiment, the number of available resource elements may correspond to the number of frequency channels N.

[0035] Figure 2B shows an example of a resource element 250 of a satellite communications system supporting satellite beam tracking of a mobile separate terminal, according to an embodiment described herein. In this embodiment, frequency channel 210 may again be used to transmit signals related to the terminal. Furthermore, frequency channel 210 may be time-multiplexed; that is, each frequency channel 210 may be configured to transmit signals to the terminal in time slots that repeat after a certain period of time. For example, period 215 may consist of sub-periods or time slots t, each having a length 225 (e.g., time slot t1, time slot t2, time slot t3, time slot t m ) can be divided into sets. Each frequency channel 210 may transmit signals to different terminals during each time slot t, although in some cases multiple time slots within a period 215 may be assigned to the same terminal. For example, each frequency channel 210 may transmit a single modulated signal during each time slot t. Information (e.g., data, control information) may be modulated into a modulated signal using various single-carrier or multi-carrier modulation techniques (e.g., OFDM, DSSS, LP-OFDM) to provide and track communications to mobile terminals (e.g., by beam manager 175), as discussed herein.

[0036] When period 215 ends, the process may be repeated so that each frequency channel 210 further transmits signals related to different terminals within the resource period. As a result, the beam manager 175 may use the frequency channel 210 for communication with terminals for one time slot t per period 215. In some embodiments, the beam manager 175 may assign terminals to more than one time slot per time period, and therefore communication with terminals may occur over more than one time slot per period of the frequency channel 210.

[0037] In the embodiment shown in Figure 2B, resource elements 250 may correspond to combinations of frequency channels 210 and time slots t in the period 215. That is, each unique combination of frequency channel 210 and time slot t may be a separate resource element 250. Thus, in this embodiment, the number of available resource elements may correspond to the number of frequency channels × the number of time slots, i.e., N × m. Therefore, this embodiment may provide more resource elements than the embodiment shown in Figure 2A.

[0038] In addition to being multiplexed by time or frequency, different polarizations may be used to define resource elements to assign to the beamformed spot beam. For example, a set of resource elements may include a first subset of resource elements associated with a first polarization and a second subset of resource elements associated with a second orthogonal polarization. The first and second polarizations can be orthogonal polarizations, and can be linear polarization or circular polarization (e.g., right-hand circular polarization (RHCP), left-hand circular polarization (LHCP)). Thus, the set of resource elements available to the beam manager 175 for assignment to the beamformed spot beam may be defined according to frequency resources (e.g., frequency channels), time resources (e.g., sub-periods of resource periods), or polarization resources.

[0039] In some embodiments, the types of resource elements can be combined. For example, in the same system, one or more frequency channels may be divided into time slots (e.g., as shown in Figure 2B), while one or more other frequency channels may be used as separate resource elements without being divided (e.g., as shown in Figure 2A). Other combinations are also possible.

[0040] Figure 3 shows an embodiment of a satellite communications system 300 supporting satellite beam tracking of mobile individual terminals, according to an example disclosed herein. The satellite communications system 300 may be an example or embodiment of the satellite communications system 100 described with reference to Figure 1. The satellite communications system 300 may include a satellite network 101 having one or more satellites 105 configured to generate a beamformed spot beam 150 (e.g., beam 150-a) for communicating with a set of terminals 120 (e.g., terminals 120-a, 120-b, 120-c, 120-d) within the coverage area 155 of the satellite communications system, as directed by a beam manager 175. The beamformed spot beam may be referred to herein as a spot beam or beam.

[0041] Terminal 120 may be located on a mobile platform or on a transport vehicle such as a car, boat, or aircraft, and may therefore be considered a mobile terminal 120. In some embodiments, each transport vehicle may include a single mobile terminal. In other embodiments, one or more transport vehicles may each include two or more mobile terminals. At least some of the mobile terminals 120 may be multi-user mobile terminals, and therefore the satellite communication system 300 may provide communication services to multiple user devices (e.g., smartphones, laptops, tablets) connected via the mobile terminals 120.

[0042] In some embodiments, the satellite communication system 300 may provide communication services to a mobile terminal 120 via a set of movable beamformed spot beams 150 that track the mobile terminal as directed by the beam manager 175 while the mobile terminal is in motion. For clarity, only a single movable beamformed spot beam 150-a associated with a single mobile terminal 120-a is illustrated in Figure 3. Although not shown in Figure 3, a movable beamformed spot beam 150 may be associated with one or more other mobile terminals 120.

[0043] In some embodiments, the beam manager 175 may associate each beamformed spot beam 150 with a different mobile terminal 120. Each mobile terminal 120 associated with its own spot beam may be referred to as a reference terminal 120. Each spot beam 150 may have its own coverage area 160 (e.g., coverage areas 160-a, 160-b, 160-c, 160-d). The coverage areas may correspond to footprints where, for example, the beam's power level is above a threshold, or where the power level drop-off away from the beam center is below a threshold (e.g., 3 dB or 6 dB).

[0044] In some embodiments, the beamformed spot beam associated with a reference terminal may include the physical location of the terminal within the coverage area of ​​the beamformed spot beam. For example, as shown in Figure 3, mobile terminal 120-a, which functions as a reference terminal, may be physically positioned within the coverage area 160-a of the beamformed spot beam 150-a, and mobile terminals 120-b, 120-c, and 120-d may be physically positioned within the coverage areas 160-b, 160-c, and 160-d of their respective beamformed spot beams (not shown). The satellite communication system 300 may provide communication services to mobile terminal 120-a via the beamformed spot beam 150-a (for example, via the beam manager 175).

[0045] In some embodiments, the beam manager 175 may cause the beamformed spot beam to track a moving terminal while a communication service is being delivered to the terminal via the beam. For example, if a moving terminal 120-a physically moves from location A to location B as indicated by arrow 325, the beamformed spot beam 150-a may "move" to track the moving terminal as indicated by arrow 330. In some embodiments, in order to "move" the beamformed spot beam, the beam manager 175 may change the beamforming coefficient associated with the beamformed spot beam and apply it to the signal associated with the beamformed spot beam. This may change the directivity of the beamformed spot beam (e.g., "move" the beam) and change (e.g., "move") the illumination range of the beamformed spot beam.

[0046] To track or follow a mobile terminal, the beamforming coefficient may be modified so that the coverage area of ​​the beamformed spot beam moves to reflect the movement of the mobile terminal (e.g., moves in coordination with the mobile terminal). The beam manager 175 may continuously adjust the coverage area (e.g., by periodically changing the beamforming coefficient to provide continuous coverage) to keep in response to the moving physical position of a moving mobile terminal and thereby track the mobile terminal. For example, as the mobile terminal 120-a moves from position A to position B, the beam manager 175 may move the coverage area 160-a of the beamformed spot beam 150-a (e.g., from coverage area 160-a1 to coverage area 160-a2) to encompass the physical position of the mobile terminal 120-a. This allows communication services associated with the mobile terminal to be provided using the same beamformed spot beam as the mobile terminal moves through the coverage area of ​​the satellite communication system. For example, using the beam manager 175, the satellite communication system can provide continuous communication services to a mobile terminal 120-a via the beamformed spot beam 150-a without handoff when the mobile terminal moves between location A and location B.

[0047] In some embodiments, the beam manager 175 may not change the beamforming coefficient while the moving terminal is stationary, because the coverage area of ​​the beamformed spot beam may already correspond to the physical position of the stationary terminal. In other embodiments, the beam manager 175 may change the beamforming coefficient even when the moving terminal is stationary. For example, in some systems, there may be a set of beamforming coefficients that can generate all beams from all beam signals. In such cases, the beam manager 175 may change the beamforming coefficients used for all terminals, even if only one terminal moves.

[0048] In some embodiments, to track a mobile terminal, the beam manager 175 may adjust the coverage area of ​​the spot beam (e.g., move the spot beam) based on measurements of signals communicated with the mobile terminal. In some embodiments, the terminal periodically provides channel state information to the satellite network, and the beam manager 175 may process this channel state information to calculate appropriate beamforming coefficients so that the beam energy of the beam signal associated with the aircraft is concentrated on that aircraft. As the aircraft moves, the channel state information may change, and subsequently the beam weighting coefficients calculated by the beam manager 175 may change. This beamformer adaptive processing allows the beam center to continuously align with the aircraft's position (to follow the aircraft).

[0049] Alternatively, the beam manager 175 may use an initial estimate of where to move the beam based on the mobile terminal's current speed and direction of travel. In some embodiments, the beam manager 175 may move the spot beam so that the mobile terminal remains centrally located within the coverage area even as the mobile terminal moves. This may help maintain a high SNR for the mobile terminal and also improve the overall communication speed and spectral efficiency associated with the mobile terminal.

[0050] In some embodiments, the beam manager 175 may determine the position of a mobile terminal based on information received from the mobile terminal, such as position coordinates, velocity, direction, or other information related to the mobile terminal (determined, for example, via a positioning system such as GPS). In some embodiments, the beam manager 175 may determine the position of a mobile terminal based on information from outside the mobile terminal, such as based on radar or other signals.

[0051] In some embodiments, the beam manager 175 may provide communication services to one or more mobile terminals via beamformed spot beams associated with the terminals. For example, in Figure 3, the beam manager 175 may establish beamformed spot beams 150 for each of the mobile terminals 120-a, 120-b, 120-c, and 120-d, providing communication services to the terminals and tracking the mobile terminals as they move within the coverage area 155 of the satellite communication system.

[0052] In some embodiments, the beam manager 175 may use initial channel state information to determine the location of a mobile terminal. The beam manager 175 may determine the initial channel state information based on measurements (e.g., signal strength) of an initial signal communicated with (e.g., transmitted to or received from) the mobile terminal. The initial channel state information may be based on the first location of each mobile terminal within the coverage area 155 (e.g., location A of mobile terminal 120-a). In some embodiments, the initial signal may include each initial channel sounding probe communicated with the mobile terminal.

[0053] In some embodiments, to generate beamformed spot beams, the beam manager 175 may apply beamforming coefficients to perform a conversion between a beam signal associated with each beamformed spot beam and component signals associated with multiple antenna elements of a satellite communication system. For example, to generate a spot beam for transmitting information to a mobile terminal, the beam manager 175 may apply beamforming coefficients to a beam signal (containing information) to obtain component signals that can be applied to antenna elements, and to generate a spot beam for receiving information from a mobile terminal, the beam manager 175 may apply beamforming coefficients to component signals received from the mobile terminal at an antenna element to obtain beam signals containing information.

[0054] Multiple antenna elements may be located on one or more satellites 105, or on components of the ground network (not shown) of the satellite communication system 300 (for example, on an access node 140 of the ground network 135, as shown in Figure 1). The beam manager 175 may use beamforming coefficients to form a spot beam 150 beamformed between the satellite 105 and the coverage area 160. The beam manager 175 may base the beamforming coefficients on initial channel state information such that the coverage area 160 of the beam 150 encompasses each of the first locations (e.g., location A) of the associated terminals 120.

[0055] The beamformed spot beam 150 may be a beamformed spot beam for the forward link (e.g., for transmitting information to a mobile terminal) and / or a beamformed spot beam for the return link (e.g., for receiving information from a mobile terminal). For example, the beamforming coefficients may include multiple sets of forward link beamforming coefficients and multiple sets of return link beamforming coefficients.

[0056] The beam manager 175 may, at a first time point, apply a first set of forward link beamforming coefficients to a set of forward link beam signals in order to generate a first set of forward link component signals for transmission to one or more mobile terminals via the antenna element at a first time point. The transmission of the first set of forward link component signals to the mobile terminals via the antenna element may each form a beamformed spot beam of the forward link corresponding to one of the mobile terminals at the first time point.

[0057] The beam manager 175 may, at the second time point, apply a second set of forward link beamforming coefficients to a set of forward link beam signals in order to generate a second set of forward link component signals for transmission to a mobile terminal via an antenna element at the second time point. The transmission of the second set of forward link component signals to the mobile terminal via the antenna element may form a beamformed spot beam of the forward link, each corresponding to the mobile terminal at the second time point. One or more beamformed spot beams of the forward link at the second time point may have moved from their corresponding beamformed spot beams at the first time point in order to track the movement of the corresponding mobile terminal.

[0058] In the return link, the beam manager 175 may, at a first time point, apply a first set of return link beamforming coefficients to the return link component signals received from the mobile terminals via the antenna elements. By applying the first set of return link beamforming coefficients, at the first time point, a return link beamformed spot beam can be formed, each corresponding to one of the mobile terminals.

[0059] The beam manager 175 may apply a second set of return link beamforming coefficients to the return link component signals received from the mobile terminal via multiple antenna elements at a second time point. By applying the second set of return link beamforming coefficients, a return link beamformed spot beam may be formed at the second time point. One or more of the return link beamformed spot beams at the second time point may have moved from the beamformed spot beam of the corresponding return link at the first time point in order to track the movement of the corresponding mobile terminal.

[0060] In some embodiments, the beam manager 175 may use subsequent channel state information to determine the subsequent location of a mobile terminal. The beam manager 175 may determine the subsequent channel state information based on a measurement of the subsequent signal communicated with the mobile terminal (e.g., signal strength). The subsequent channel state information may be based on the second location of each mobile terminal within the coverage area 155 (e.g., location B of mobile terminal 120-a). The difference between the initial channel state information and the subsequent channel state information may be based on the movement of the mobile terminal to each second location.

[0061] In some embodiments, the subsequent signal may include each subsequent channel sounding probe communicated with the mobile terminal. Modification of the beamforming coefficient may be based on each subsequent channel sounding probe. In some embodiments, each initial and subsequent channel sounding probe may be communicated with the mobile terminal in a first cycle, and the beamforming coefficient may be updated in a second cycle based on this.

[0062] In some embodiments, the beam manager 175 may modify the beamforming coefficient and apply it to the conversion between the beam signal and component signals associated with multiple antenna elements of the satellite network. The modified beamforming coefficient may be based on subsequent channel state information such that a new beam coverage area (e.g., coverage area 160-a2) encompasses each of the second positions of the mobile terminal (e.g., position B).

[0063] The subsequent determination of the mobile terminal's position and the subsequent modification of the beamforming coefficient can be repeated by the beam manager 175 as frequently and for as long as desired. In this way, multiple beamformed spot beams 150 can track the movement of the reference terminal 120 across the entire coverage area 155 of the satellite communication system while communication services are being provided to the terminal. In some embodiments, the beam manager 175 may move the beamformed spot beams 150 to track each mobile terminal with sufficient frequency so that the relevant coverage area at the current position overlaps with the coverage area at the previous position. That is, each movement of the beamformed spot beam 150 may move a beam smaller than the diameter of the beamformed spot beam 150 (e.g., radius, or a fraction such as half the radius).

[0064] In some embodiments, the beamforming coefficients (e.g., initial beamforming coefficients and all modified beamforming coefficients) may include a set of beamforming coefficients. Each set of beamforming coefficients may correspond to a different period of a set of beamformed spot beams. In some embodiments, the beamforming coefficients may be modified based on characteristics, attributes, or conditions that satisfy (e.g., match, exceed, and / or fall below) a threshold. For example, the beam manager 175 may modify and apply beamforming coefficients based on the fact that the received signal quality (e.g., measured at a reference terminal or satellite communication system) has fallen below a threshold. This can help maintain high signal quality associated with the mobile terminal, and may also increase the overall communication speed and efficiency associated with the mobile terminal. In some embodiments, the beam manager 175 may determine the received signal quality based on subsequent channel state information.

[0065] In some embodiments, two or more beams may use different resource elements to provide communication services to each mobile terminal. For example, the beam manager 175 may cause each beam to use different resource elements (e.g., different combinations of frequency channel, time slot, and polarization) to provide communication to each mobile terminal while tracking it. By using different resource elements, interference between beams can be reduced or eliminated, even if the mobile terminals may be close to each other.

[0066] In some embodiments, two or more beams may use the same resource elements to provide communication services to each mobile terminal. For example, the beam manager 175 may cause two or more beams to use the same combination of frequency channel, time slot, and polarization, providing communication to each mobile terminal while tracking them. This may be desirable when the mobile terminals are far enough apart that the beams do not interfere with each other. Using the same resource elements allows more beams to be used for a particular set of resources, increasing frequency reuse.

[0067] Figure 4 shows another embodiment of the satellite communication system 400 supporting satellite beam tracking of mobile individual terminals according to the embodiments disclosed herein. The satellite communication system 400 may be an embodiment of the satellite communication system discussed herein, such as the satellite communication system 100 or 300 described with reference to Figure 1 or Figure 3, or embodiments thereof.

[0068] The satellite communication system 400 may include a satellite network 101 having one or more satellites 105 configured to generate movable beamformed spot beams 150 (e.g., beams 150-a and 150-b) for communication with mobile terminals 120 (e.g., mobile terminals 120-a and 120-b) as beamformed spot beams are controlled by a beam manager 175 as discussed herein and track the mobile terminals.

[0069] In some embodiments, each beamformed spot beam 150 may be associated with a different mobile terminal 120. For example, a beam manager 175 may associate a beamformed spot beam 150-a with mobile terminal 120-a and a beamformed spot beam 150-b with mobile terminal 120-b. A beamformed spot beam 150 may have a coverage area 160 (e.g., coverage areas 160-a and 160-b). For clarity, the coverage area 160-a associated with a moving beamformed spot beam 150-a corresponding to mobile terminal 120-a is shown by a solid line, and the coverage area 160-b associated with a moving beamformed spot beam 150-b corresponding to mobile terminal 120-b is shown by a dashed line.

[0070] Figure 4 shows an example where two mobile terminals 120-a and 120-b pass close to each other as they move along their respective paths 460-a and 460-b. The path 460-b corresponding to mobile terminal 120-b is shown as a dashed line, as is the beam 150-b and its corresponding coverage area 160-b. Mobile terminals 120-a and 120-b can move along paths 460-a and 460-b from their respective starting positions represented by A1 and A2 to their respective ending positions represented by G1 and G2. While beams 150-a and 150-b are shown for aircraft, other mobile platforms may also be used. Mobile terminals 120-a and 120-b can each track mobile terminal 120-a and 120-b (for example, by the beam manager 175 coordinating its respective coverage areas 160-a and 160-b in conjunction with the movement of the mobile terminals) and provide communication services as the mobile terminals move along their paths.

[0071] As the mobile terminals 120 approach each other, interference between the associated beams 150 may increase (for example, if the beams use the same resource element). As described herein, the beam manager 175 may switch one or both beams to different resource elements to mitigate interference.

[0072] At points along paths 460-a and 460-b, represented by B1 and B2, the beams may begin to overlap, for example, as mobile terminals move toward each other. As used herein, beams may be considered to overlap based on the relative positions of their respective coverage areas. For example, beams 150-a and 150-b may overlap when their respective coverage areas 160-a and 160-b overlap each other. In some cases, the coverage areas of beams may be centered on the positions of the mobile terminals that the beams are tracking. For example, coverage areas 160-a and 160-b may be centered on the positions of mobile terminals 120-a and 120-b, respectively. In some embodiments, the overlap of coverage areas may be based on the distance between the corresponding mobile terminals.

[0073] Further along paths 460-a and 460-b, mobile terminals 120-a and 120-b may arrive at other points represented by C1 and C2, where one or more mobile terminals may enter the coverage area of ​​a beam that does not support (e.g., does not provide or track) a mobile terminal (e.g., by the mobile terminals continuing to move toward each other). For example, at C1 / C2, mobile terminal 120-a may enter the coverage area 160-b of beam 150-b, and / or mobile terminal 120-b may enter the coverage area 160-a of beam 150-a. At some point before or after this, interference between beams 150-a and 150-b may rise to an unacceptable level. For example, the interference metric between beams may meet a threshold (e.g., match or exceed, or match or exceed). As discussed herein, steps may be taken (e.g., by beam manager 175) to improve the interference (e.g., avoid beam contention).

[0074] Mobile terminals 120-a and 120-b may remain in the coverage areas 160-a and 160-b of both beams 150-a and 150-b until they reach another point along paths 460-a and 460-b, represented by E1 and E2, respectively. At that point, the mobile terminals may no longer be within the coverage area of ​​the other beam (for example, by moving away from each other). For example, in E1 / E2, mobile terminal 120-a may no longer be within the coverage area 160-b of beam 150-b, and mobile terminal 120-b may no longer be within the coverage area 160-a of beam 150-a. The beams may still overlap after each mobile terminal is no longer within the coverage area of ​​the other terminal. For example, in E1 / E2, the coverage areas 160-a and 160-b of beams 150-a and 150-b may still overlap.

[0075] Beams 150-a and 150-b may remain overlapping up to another point along paths 460-a and 460-b, represented by F1 and F2. At that point, beams 150-a and 150-b may no longer overlap (for example, as the mobile terminals continue to move away from each other). From that point to G1 / G2 along paths 460-a and 460-b, beams 150-a and 150-b may remain separate and non-overlapping, as long as the mobile terminals are sufficiently far apart from each other.

[0076] As described with respect to Figures 2A and 2B, the beam manager 175 may use resource elements to provide communication services to mobile terminals via the beamformed spot beams. In some embodiments, if the two beams do not compete (e.g., there is low interference between the two beams), the beams may use the same resource elements to provide communication services to their respective mobile terminals. For example, as long as the respective interference metrics between beams 150-a and 150-b remain below a threshold, beams 150-a and 150-b may use the same resource elements to provide communication to mobile terminals 120-a and 120-b, as discussed herein.

[0077] As mobile terminals 120-a and 120-b approach each other (for example, from A1 / A2 through B1 / B2 and C1 / C2 to D1 / D2), interference between the corresponding beams 150-a and 150-b may increase. Increased interference may mean that communication through separate beams (for example, when using the same resource element) is subjected to too much inter-beam interference. When the interference rises to a certain level (for example, when the inter-beam interference metric meets a threshold), the beam manager 175 may take steps to avoid inter-beam contention (for example, to improve inter-beam interference).

[0078] In some embodiments, the interference metric may correspond to measured interference in one or both beams. For example, the interference metric may correspond to the signal intensity of a beam related to a first terminal as measured at a second terminal. Furthermore, or alternatively, the interference metric may correspond to signal degradation of the beam (e.g., a decrease in SNR), and the threshold may correspond to a specific level of distance or a specific amount of degradation (e.g., a 3 dB or 6 dB SNR loss). In some embodiments, beam interference may be measured at a receiving device of the communication link. For example, beam interference may be measured at a mobile terminal (in the case of a forward link) or a satellite (in the case of a return link).

[0079] In some embodiments, the interference metric may correspond to channel correlation. For example, the interference metric may be based on the correlation of channel state information between two mobile terminals. The interference metric may be frequency-dependent.

[0080] In some embodiments, the interference metric may correspond to estimated interference of one or both beams. For example, the estimated interference may be based on the distance between mobile terminals or on an algorithm that estimates interference related to the relevant beams. In some embodiments, the interference metric may be based on the distance between mobile terminals associated with the beams, and the threshold may correspond to a specific distance. For example, the threshold may correspond to the distance between mobile terminals where the coverage areas of the corresponding beams begin to overlap (e.g., in B1 / B2), or the distance between mobile terminals where one mobile terminal enters the beam coverage area corresponding to the other mobile terminal (e.g., in C1 / C2), or an intermediate distance. Other distances are also possible.

[0081] In some embodiments, a single beam may provide communication services to multiple mobile terminals. For example, a beam manager 175 may assign one of the terminals as a reference terminal for the beam being tracked while providing communication services. The reference terminal is tasked with providing channel status information to the beam manager 175 and may represent terminals in the same or similar locations. Other terminals may also communicate via the beamformed spot beam, which is generated via beamforming coefficients referencing the reference terminal. This can be achieved by sharing resources among the mobile terminals. For example, communication services may be provided to two or more mobile terminals via the same beam, on the same frequency channel, but on different time slots corresponding to the mobile terminals (e.g., beam manager 175). In some embodiments, the same frequency and time slot can be used for mobile terminals by further subdividing the time slots, which may be allocated to different users (e.g., into MAC layer frames).

[0082] In some cases, a unicast message may be communicated to two or more mobile terminals over the same beam. For example, a first unicast message may be sent to a first mobile terminal, and a second unicast message may be sent to a second mobile terminal over the same shared beam. In some cases, a multicast message may be communicated to mobile terminals over the same beam. For example, a multicast message may be sent to the first and second mobile terminals over the same shared beam. Unicast and multicast messages may be communicated to mobile terminals over different beams. Also, unicast and multicast messages may be communicated to mobile terminals over the same beam. For example, if a communication service is provided to multiple mobile terminals over a single beam (e.g., shared by the mobile terminals), a unicast message may be communicated over the beam to each of the mobile terminals using different resources (e.g., different time slots), and a multicast message may be communicated over a shared resource (e.g., using a shared time slot), or vice versa.

[0083] Figure 5 shows an exemplary timing diagram 500 supporting satellite beam tracking for individual mobile terminals, according to the examples disclosed herein. Timing diagram 500 represents beams 150-a and 150-b of Figure 4, which may use different resource elements to provide communication services to mobile terminals 120-a and 120-b in the event of interference between the beams. As discussed with respect to Figures 3 and 4, interference may increase if, for example, the mobile terminals move closer to each other while the same resource elements are being used by the corresponding beams. As shown in timing diagram 500, one of the beams (e.g., beam 150-b) may be switched to a different resource element (e.g., by beam manager 175) to mitigate interference.

[0084] Both beams 150-a and 150-b may have been originally assigned to the same resource element A (for example, by beam manager 175) at or before the start time t1, which may correspond to mobile terminals 120-a and 120-b being located in A1 / A2. Thus, beams 150-a and 150-b may use the same resource element A at the start time t1 to provide communication services to their respective mobile terminals 120-a and 120-b.

[0085] Mobile terminals can be quite far apart from each other at start time t1 so that beams 150-a and 150-b do not compete with each other (e.g., they are assigned to the same resource element A, but interference between beams may be slight, if any). Therefore, the interference metric between beams may be relatively low (e.g., below the threshold). Beams 150-a and 150-b may be quasi-statically assigned to the same resource element A (e.g., by beam manager 175), and each terminal monitors and / or transmits over the same resource element until it receives an instruction to switch resource elements.

[0086] At time t2, the interference between the beams may rise to an unacceptable level (e.g., the interference metric may meet a first threshold). In some embodiments, this may correspond to one of the mobile terminals 120 entering the coverage area of ​​the other beam 150 (e.g., C1 / C2 or its vicinity). In some embodiments, this may correspond to the mobile terminal 120 being between B1 / B2 and C1 / C2. Other locations may also be possible, based on the interference metric value meeting the first threshold. Several potential interference metrics and thresholds are discussed with respect to Figure 4.

[0087] To mitigate interference, one of the beams may be changed to a different resource element (for example, by the beam manager 175). For example, at time t2, in response to the interference metric meeting a first threshold, the beam manager 175 may switch the resource element to beam 150-b (for example, by reassigning beam 150-b to resource element B, which is different from resource element A) in order to provide communication services to the mobile terminal 120-b. This may involve changing one or more of the frequency, time slot, polarization, or other resources (e.g., one or more codes) associated with beam 150-b to be different from those used by beam 150-a. In some embodiments, resource element B may be orthogonal to resource element A.

[0088] Since beam 150-b may be using different resource elements than beam 150-a to provide communication services to the mobile terminal after time t2, interference between beam 150-a and beam 150-b may be significantly reduced or no longer exist. Therefore, the satellite communication system can continue to provide communication services to mobile terminal 120-b without performing an inter-beam handoff.

[0089] At time t3, beams 150-a and 150-b may again use the same resource element. For example, at time t3, beam 150-b may revert to its original resource element (for example, by beam manager 175 reassigning beam 150-b to resource element A) in order to provide communication services to mobile terminal 120-b. Alternatively, beams 150-a and 150-b may continue to use different resource elements. For example, instead of reassigning beam 150-b's resource element to resource element A, beam manager 175 may allow beam 150-b to continue using resource element B after t3.

[0090] Time t3 may correspond to a point in time when beam interference or potential interference is no longer at an unacceptable level (e.g., the interference metric does not meet, exceeds, or falls below the second threshold). The interference metric may be the same as or different from the interference metric used at time t2. Furthermore, if the interference metric is the same as the one used at time t2, the second threshold may be the same as or different from the first threshold used at time t2. In some cases, time t3 may correspond to a point in time when mobile terminals are at a certain distance from each other. Several potential interference metrics and thresholds are discussed with respect to Figure 4.

[0091] After time t3, as long as the inter-beam interference metric remains below a threshold (e.g., a first or second threshold), the satellite communication system may continue to provide communication signals to mobile terminals via beams 150-a and 150-b using the same resource element (e.g., resource element A) at least until time t4. Time t4 may correspond to mobile terminals 120-a and 120-b being in G1 / G2. However, if the inter-beam interference rises again to a level (e.g., the interference metric again meets the first threshold), the beam manager 175 may switch one of the beams (e.g., beam 150-b) to a different resource element than the other beam, and in some embodiments, switch it back. This switching may be performed each time the inter-beam interference rises to that level. As a result, inter-beam handoffs can be avoided.

[0092] Figure 6 shows a beam manager 605 supporting satellite beam tracking of a mobile separate terminal according to an example disclosed herein. The beam manager 605 may be an embodiment of the beam manager 175 of Figure 1. The beam manager 605 may include a bus 625, a terminal tracking device 620, a memory 630, a code 635, a processor 640, a beamformer 645, and a beam signal processor 650, and may be configured to control beam tracking of the mobile terminal via an antenna array 610.

[0093] The beam manager 605 may be located within the ground network (e.g., ground network 135 in Figure 1) or satellite network (e.g., satellite network 101 in Figure 1) of the satellite communication system. Alternatively, the beam manager 605 may be divided between the ground network and the satellite network. In one example (e.g., corresponding to a GBBF configuration), all components of the beam manager 605 may be located in the ground network. In another embodiment (e.g., corresponding to an OBBF configuration), the beamformer 645 may be located in the satellite network (e.g., on one or more satellites), and the remaining components of the beam manager 605 may each be located in either the ground network or the satellite network.

[0094] The antenna array 610 may be an embodiment of the antenna of the satellite network 101 in Figure 1 and may include antenna elements 615. In some embodiments, one or more of the antenna elements 615 may be or may include antenna panels. The spacing of the antenna elements 615 may be evenly distributed across the entire opening of the antenna array 610, or the spacing of the antenna elements 615 may vary across the antenna array 610. In some embodiments, the first antenna array 610 may be contained within a ground segment, and the second antenna array 610 (e.g., one or more antenna arrays coupled together using transponders) may be contained within a space segment.

[0095] Bus 625 may represent an interface where signals can be exchanged between the components of the beam manager 605 and a location (e.g., a central location) that can be used to distribute signals to the signal processing components of the beam manager 605 (e.g., terminal tracker 620, beam signal processor 650, beamformer 645). Bus 625 may include one or more wired interfaces. Furthermore, or alternatively, bus 625 may be a wireless interface used, for example, to wirelessly transmit signals between signal processing components according to a communication protocol. The beamformer 645 may be coupled to the antenna element 615 via one or more wired or wireless interfaces.

[0096] Memory 630 may include volatile memory (e.g., random access memory (RAM)) and / or non-volatile memory (e.g., read-only memory (ROM)). It may also include other types of memory. Memory 630 may store computer-readable and computer-executable code 635. When executed by processor 640, the code may include instructions that cause ground station 605 to perform various functions described herein. Code 635 may be stored in a non-temporary computer-readable medium such as system memory or another type of memory. In some cases, code 635 may not be directly executable by processor 640, but (e.g., when compiled and executed) can cause a computer to perform the functions described herein. In some cases, memory 630 may include a basic I / O system (BIOS) that can control basic hardware or software operations, such as interaction with peripheral components or devices, among other things.

[0097] The processor 640 may include intelligent hardware devices (e.g., general-purpose processors), digital signal processors (DSPs), central processing units (CPUs), microcontrollers, application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), programmable logic devices, discrete gate or transistor logic components, discrete hardware components, or any combination thereof. The processor 640 may be configured to execute computer-readable instructions stored in memory (e.g., memory 630) to cause the ground station 605 to perform various functions (e.g., functions or tasks supporting mobile satellite beam resource allocation). For example, the processor 640 and memory 630 may be configured to perform various functions described herein.

[0098] The beam signal processor 650 may be configured to process (e.g., demodulate, decode) the received beam signal 654 received from the beamformer 645. The beam signal processor 650 may decode the data symbols contained in the received beam signal 654 to obtain a received beam data signal 664. The information (e.g., packets) in the received beam data signal 664 may be passed to a destination device (e.g., via network(s) 125). The beam signal processor 650 may be configured to process (e.g., encode, modulate) the transmitted beam data signal 662 to obtain a transmitted beam signal 652 to be sent to the beamformer 645. The transmitted beam data signal 662 may contain information (e.g., packets) received (e.g., via network(s) 125) for transmission to terminal 120.

[0099] The terminal tracker 620 may be configured to determine information for the beamformer 645 to be used when forming a beamformed spot beam (e.g., the beamformed spot beam 150 in Figure 1) using the antenna element 615. To determine information for forming the beamformed spot beam, the terminal tracker 620 may identify a set of terminals to be assigned as reference terminals (e.g., the mobile terminal 120 in Figure 1) and may determine spatial information associated with the reference terminals. The terminal tracker 620 may determine a set of beamforming coefficients (e.g., phase shift, amplitude component) that the beamformer 645 can use to generate a beamformed spot beam having individual coverage areas directed to the spatial information associated with the reference terminals.

[0100] The terminal tracker 620 may determine a beamforming coefficient to separate signals transmitted through beamformed spot beams from each other by enhancing the signal transmitted within each beamformed spot beam and canceling interference from signals transmitted within other beamformed spot beams. The beamforming coefficient may be contained in an M × N matrix, where the value of M may represent the number of antennas and the value of N may represent the number of space layers, and the value of N may be less than or equal to the value of M.

[0101] For the transmission of a beamformed spot beam through the antenna element 615, the terminal tracker 620 may determine a single set of transmit beamforming coefficients for each of a frequency range or channel (e.g., frequency channel 210 in Figure 2B) and one or more periods (e.g., period 215, time slot t in Figure 2B) to be applied to a set of transmit beam signals 652 associated with the beamformed spot beam. The beamformer 645 may apply the set of transmit beamforming coefficients to a set of transmit beam signals 652 to obtain a component signal 656 for transmission through the antenna element 615.

[0102] For receiving a beamformed spot beam via the antenna element 615, the terminal tracker 620 can determine a single set of received beamforming coefficients for each of a frequency range or channel (e.g., frequency channel 210 in Figure 2B) and one or more periods (e.g., period 215, time slot t in Figure 2B), which can be applied by the beamformer 645 to the component signal 656 in order to obtain a set of received beam signals 654 associated with the beamformed spot beam.

[0103] In some embodiments, the beamforming coefficient may be determined by one or more satellites 105. In some embodiments, the beamforming coefficient may be received by one or more satellites from one or more ground stations (e.g., network device 130 or other stations in the ground network 135) after the terminal tracker 620 has determined the beamforming coefficient.

[0104] In some embodiments, the terminal tracker 620, beamformer 645, beam signal processor 650, or various combinations or components thereof may be implemented in hardware (e.g., in a communication management circuit). The hardware may include a processor, DSP, ASIC, FPGA or other PLD, discrete gate or transistor logic, discrete hardware components, or any combination thereof configured as means for performing the functions described herein, or otherwise supporting them. In some embodiments, the processor and memory coupled to the processor may be configured to perform one or more of the functions described herein (e.g., by the processor executing instructions stored in memory).

[0105] Furthermore, or alternatively, the terminal tracker 620, beamformer 645, beam signal processor 650, or any combination or component thereof, may be implemented in code 635 executed by the central processor 640 (for example, as communication management software or firmware). When implemented in code 635 executed by processor 640, the functions of the terminal tracker 620, beamformer 645, beam signal processor 650, or any combination or component thereof, may be performed by a general-purpose processor, DSP, CPU, ASIC, FPGA, or any combination thereof or other programmable logic device (for example, configured as a means to perform the functions described herein, or otherwise supporting them).

[0106] Figure 7 shows a block diagram 700 of a terminal tracker 720 supporting satellite beam tracking of a mobile individual terminal according to an embodiment disclosed herein. The terminal tracker 720 may be an embodiment of an embodiment of the terminal tracker 620 as described with reference to Figure 6. The terminal tracker 720, or various components thereof, may be an embodiment of means for performing various embodiments of satellite beam tracking of a mobile individual terminal as described herein. For example, the terminal tracker 720 may include a communications manager 725, a terminal assignment manager 730, a channel status information determination manager 735, a receiver 740, a signal quality determination device 745, a beamforming manager 750, a message transmitter 755, or any combination thereof. Each of these components may communicate with each other directly or indirectly (e.g., via one or more buses).

[0107] The communications manager 725 may be configured as a means of providing communications services to a plurality of mobile terminals via a set of beamformed spot beams, as discussed herein, or may otherwise support such means. The communications manager 725 may comprise one or more of the other components of the terminal tracker 720. In some embodiments, the communications manager 725 may comprise a terminal assignment manager 730, a channel status information determination manager 735, a receiver 740, a signal quality determination device 745, a beamforming manager 750, and a message transmitter 755.

[0108] The terminal assignment manager 730 may be configured as a means for assigning a subset of multiple mobile terminals as reference terminals within the coverage area of ​​a satellite communication system, as discussed herein, or may otherwise support such means.

[0109] The channel state information determination manager 735 may be configured as a means for determining channel state information based on measurements of signals communicated with a reference terminal, as discussed herein, or may otherwise support such means. The channel state information may be based on the respective locations of the reference terminals within the coverage area. In some embodiments, the first signal may be a channel sounding probe.

[0110] The beamforming manager 750 may be configured, as discussed herein, as a means for applying beamforming coefficients to convert between beam signals associated with a set of beamformed spot beams and component signals associated with a plurality of antenna elements located on one or more satellites of a satellite communications system, or may otherwise support such means. The beamforming coefficients may be based on channel state information. The beamforming coefficients may be applied periodically.

[0111] The receiver 740 may be configured as a means for communicating each channel sounding probe with a reference terminal, as discussed herein, or may otherwise support such means. Each channel sounding probe may include signals used by the channel state information determination manager 735.

[0112] The signal quality determination device 745 may be configured, as discussed herein, as a means for determining, or otherwise supporting, that the received signal quality at each reference terminal assigned to a beamformed spot beam of a set of beamformed spot beams may not meet a threshold. The determination may be based on channel state information. The application of beamforming coefficients may be based on the determination that the received signal quality of a beamformed spot beam does not meet a threshold.

[0113] In some embodiments, aspects of one or more components of the terminal tracking device 620 may be found in other components of the terminal tracking device 620, or even outside of the terminal tracking device 620. For example, the processor 640 and memory 630 may be used to perform one or more functions related to the components of the terminal tracking device 620.

[0114] Figure 8 is a flowchart illustrating a method 800 for supporting satellite beam tracking of a mobile separate terminal according to embodiments disclosed herein. The operation of method 800 may be carried out by a satellite communication system or a component thereof, as described herein. For example, the operation of method 800 may be carried out by a beam manager, as described with reference to Figures 1 to 7. In some embodiments, a set of instructions may be executed to control the functional elements of a device to perform the functions described. Furthermore, or alternatively, aspects of the functions described may be performed using dedicated hardware.

[0115] In 805, the method may include providing communication services to a plurality of mobile terminals via a set of beamformed spot beams. Operation of 805 may be performed according to embodiments such as those disclosed herein. In some embodiments, the mode of operation of 805 may be performed by a communication manager 725, as described with reference to Figure 7. In some embodiments, the provision of communication services may include the operations of 810, 815, 820, 825, and 830.

[0116] In 810, the method may include assigning a subset of multiple mobile terminals as reference terminals within the coverage area of ​​a satellite communication system. The operation of 810 may be carried out according to embodiments such as those disclosed herein. In some embodiments, the operation of 810 may be carried out by a terminal assignment manager 730, as described with reference to Figure 7.

[0117] In 815, the method may include determining initial channel state information based on a measurement of a first signal communicated with a reference terminal, the initial channel state information being based on the respective first positions of each reference terminal within the coverage area. The operation of 815 may be performed according to embodiments such as those disclosed herein. In some embodiments, the operation of 815 may be performed by a channel state information determination manager 735, as described with reference to Figure 7.

[0118] In 820, the method may include applying a first beamforming coefficient to convert between a beam signal associated with a set of beamformed spot beams and component signals associated with a plurality of antenna elements located on one or more satellites of a satellite communications system, the first beamforming coefficient being based on initial channel state information. Operation of 820 may be performed according to embodiments such as those disclosed herein. In some embodiments, aspects of operation of 820 may be performed by a beamforming manager 750, as described with reference to Figure 7.

[0119] In 825, the method may include determining subsequent channel state information based on measurements of subsequent signals communicated with a reference terminal, wherein the difference between initial channel state information and subsequent channel state information is based on the movement of the reference terminal to each second location within the coverage area. The operation of 825 may be performed according to embodiments such as those disclosed herein. In some embodiments, the operation of 825 may be performed by a channel state information determination manager 735, as described with reference to Figure 7.

[0120] In 830, the method may include applying a second beamforming coefficient to convert between a beam signal associated with a set of beamformed spot beams and a component signal associated with a plurality of antenna elements located on one or more satellites, the second beamforming coefficient being based on subsequent channel state information so that the set of beamformed spot beams tracks the movement of a reference terminal. Operation of 830 may be performed according to embodiments such as those disclosed herein. In some embodiments, the operation of 830 may be performed by a beamforming manager 750, as described with reference to Figure 7.

[0121] In some implementations, the apparatus described herein may perform methods such as method 800. The apparatus may include features, circuits, logic, means, or instructions (e.g., a non-temporary computer-readable medium storing instructions executable by a processor) or any combination thereof for performing the methods.

[0122] These methods illustrate embodiments, and it should be noted that the operation and steps may be reconfigured or otherwise modified to allow for other implementations. In some embodiments, two or more embodiments of the method may be combined. For example, each embodiment of the method may include steps or embodiments of other methods, or other steps or techniques described herein.

[0123] The information and signals described herein may be represented using any of the various different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout this specification may be represented by voltage, current, electromagnetic waves, magnetic fields or particles, optical fields or photons, or any combination thereof.

[0124] The various exemplary blocks and modules described in connection with the disclosure herein may be implemented or run using general-purpose processors, DSPs, ASICs, FPGAs, or other programmable logic devices, discrete gates or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor, but alternatively, a processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices (e.g., a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors combined with a DSP core, or any other such configuration).

[0125] 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 codes on a computer-readable medium. Other embodiments and implementations are within the scope of this disclosure and the accompanying claims. For example, depending on 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 in various locations, including being distributed so that some of the functions are implemented in different physical locations.

[0126] Computer-readable media may include both non-temporary computer storage media and communication media, including any media that facilitate the transfer of computer programs from one location to another. Non-temporary storage media may be any available media accessible from a general-purpose or dedicated computer. For example, but not limited to, non-temporary computer-readable media may include RAM, ROM, electrically erasable programmable read-only memory (EEPROM), flash memory, compact disk read-only memory (CDROM) or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other non-temporary media that can be used to carry or store desired program code means in the form of instructions or data structures, and that are accessible by a general-purpose or dedicated computer or general-purpose or dedicated processor. Any connection may also be appropriately referred to as computer-readable media. For example, if 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 technologies such as infrared, radio, and microwave, then coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of media. Disk and disc, as used herein, include CD, laserdisc, optical disc, digital versatile disc (DVD), floppy disk, and Blu-ray disc, where a disk typically reproduces data magnetically, while a disc reproduces data optically using a laser. Any combination of the above is also included in the scope of computer-readable media.

[0127] When used herein, including in the claims, "or" in a list of items (e.g., a list of items preceded by phrases such as "at least one" or "one or more") indicates a comprehensive list, such as the list of at least one of A, B, or C meaning A or B or C or AB or AC or BC or ABC (i.e., A and B and C). Also, 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, when used herein, the phrase "based on" shall be interpreted in the same way as the phrase "at least partially based on."

[0128] In the attached drawings, similar components or features may have the same reference label. Furthermore, various components of the same type may be distinguished by adding a dash and a second label to differentiate similar components after the reference label. If only the first reference label is used in the description, this description is applicable to any similar component having the same first reference label, regardless of the second reference label or any other subsequent reference labels.

[0129] The descriptions herein, in relation to the accompanying drawings, describe exemplary configurations and do not represent all embodiments that may be implemented or that fall within the claims. The term “exemplary” as used herein means “serving as an example, illustration, or representation,” and not “preferred” or “advantageous over other embodiments.” Detailed descriptions include specific details for the purpose of providing an understanding of the described art. However, these arts may be practiced without these specific details. In some examples, well-known structures and devices are shown in block diagram form to avoid obscuring the concepts of the described embodiments.

[0130] The descriptions herein are provided to enable those skilled in the art to create or use this disclosure. Various modifications to the disclosure will be obvious to those skilled in the art, and the general principles defined herein may be applied to other modifications without departing from the scope of the disclosure. Thus, this disclosure is not limited to the examples and designs described herein, but is given the broadest scope that conforms to the principles and novel features disclosed herein.

Claims

1. A method comprising providing communication services to a plurality of mobile terminals (120) via a set of beam-formed spot beams (150), wherein providing the communication services is Within the coverage area (155) of the satellite communication system (100), a subset of the multiple mobile terminals (120) is assigned as a reference terminal, The process involves determining initial channel state information based on a measurement value of a first signal communicated with the reference terminal, wherein the initial channel state information is determined based on the first position of each of the reference terminals within the coverage area (155). The process involves applying a first beamforming coefficient to convert between beam signals (652, 654) associated with a set of beamformed spot beams (150) and component signals (656) associated with a plurality of antenna elements (615) located on one or more satellites (105) of the satellite communication system (100), wherein the first beamforming coefficient is based on the initial channel state information. The process involves determining subsequent channel state information based on the measured value of a subsequent signal communicated with the reference terminal, wherein the difference between the initial channel state information and the subsequent channel state information is determined based on the movement of the reference terminal to each of the second positions within the coverage area (155). The process involves applying a second beamforming coefficient to convert between the beam signals (652, 654) associated with the set of beamformed spot beams (150) and the component signals (656) associated with the plurality of antenna elements (615) located on one or more satellites (105), wherein the second beamforming coefficient performs the conversion based on the subsequent channel state information such that the set of beamformed spot beams (150) tracks the movement of the reference terminal. Methods that include...

2. The method according to claim 1, wherein the first signal and the subsequent signal are channel sounding probes.

3. The method according to claim 1 or 2, wherein providing the communication service further includes applying a plurality of sets of beamforming coefficients, each set of beamforming coefficients corresponding to a different period of time of the set of beamformed spot beams.

4. The method according to any one of claims 1 to 3, wherein the first signal includes each first channel sounding probe communicated with the reference terminal, and the subsequent signal includes each second channel sounding probe communicated with the reference terminal, and the application of the second beamforming coefficient is based on each second channel sounding probe.

5. Providing the aforementioned communication service further means In the first cycle, each channel sounding probe communicates with the reference terminal, and each channel sounding probe includes the first signal and the subsequent signal. The method according to any one of claims 1 to 4.

6. Applying the second beamforming coefficient described above means In the second cycle, the first beamforming coefficient is updated based on the communication of each channel sounding probe in the first cycle. Applying the updated first beamforming coefficient as the second beamforming coefficient, The method according to claim 5, including the method described in claim 5.

7. Providing the aforementioned communication service further means The process includes determining, based on the subsequent channel state information, that the received signal quality at each of the reference terminals assigned to one of the beamformed spot beams (150) in the set of beamformed spot beams (150) does not meet the threshold, and applying the second beamforming coefficient based on the determination that the received signal quality of the beamformed spot beam (150) does not meet the threshold. The method according to any one of claims 1 to 6.

8. The method according to any one of claims 1 to 7, wherein each coverage area (160) of the set of beam-formed spot beams (150) initially encompasses each of the first positions of the reference terminals.

9. The first mobile terminal (120) among the plurality of mobile terminals is assigned as a reference terminal for the first beam-formed spot beam (150) among the set of beam-formed spot beams. The communication service is provided to the first mobile terminal (120) and the second mobile terminal (120) via the first beamformed spot beam (150). The method according to any one of claims 1 to 8.

10. The method according to claim 9, wherein each coverage area (160) of the first beam-formed spot beam (150) encompasses the respective positions of the first and second mobile terminals (120).

11. The method according to claim 9 or 10, wherein the first and second mobile terminals (120) are located on separate aircraft.

12. The first beam-formed spot beam (150) of the set of beam-formed spot beams is associated with the first reference terminal of the reference terminal, The first beam-formed spot beam (150) has a first coverage area (160) that includes the first position of the first reference terminal when the first reference terminal is in the first position, and a second coverage area (160) that includes the second position of the first reference terminal when the first reference terminal is in the second position. The method according to any one of claims 1 to 11.

13. The method according to claim 12, wherein the second coverage area (160) at least partially overlaps the first coverage area (160).

14. It is a satellite communication system, One or more satellites (105), Multiple antenna elements (615) arranged on one or more satellites, The system comprises a beam manager (175) configured to provide communication services to a plurality of mobile terminals (120) via a set of beam-formed spot beams (150), wherein, in order to provide communication services, the beam manager (175) is configured to provide communication services to the system, Within the coverage area (155) of the satellite communication system (100), a subset of the multiple mobile terminals (120) is assigned as a reference terminal, The initial channel state is determined based on the measured value of the first signal communicated with the reference terminal, wherein the initial channel state information is determined based on the first position of each of the reference terminals within the coverage area (155). The process involves applying a first beamforming coefficient to convert between beam signals (652, 654) associated with the set of beamformed spot beams (150) and component signals (656) associated with the plurality of antenna elements (615) arranged on one or more satellites (105), wherein the first beamforming coefficient is based on initial channel state information. The process involves determining subsequent channel state information based on the measured value of a subsequent signal communicated with the reference terminal, wherein the difference between the initial channel state information and the subsequent channel state information is determined based on the movement of the reference terminal to each of the second positions within the coverage area (155). Applying a second beamforming coefficient to convert between the beam signals (652, 654) associated with the set of beamformed spot beams (150) and the component signals (656) associated with the plurality of antenna elements (615) arranged on one or more satellites (105), wherein the second beamforming coefficient converts based on the subsequent channel state information such that the set of beamformed spot beams (150) tracks the movement of the reference terminal. It is configured to perform the following actions. Satellite communication system.

15. The system according to claim 14, further comprising a ground station (130) configured to communicate with one or more satellites (105) via one or more satellite beams (132).

16. The beam manager (175) provides the system with Applying multiple sets of beamforming coefficients, wherein each set of beamforming coefficients corresponds to a different period of time for the set of beamformed spot beams (150). The system according to claim 14 or 15, configured to perform the following:

17. The system according to any one of claims 14 to 16, wherein the first signal includes each first channel sounding probe transmitted by the reference terminal, the subsequent signal includes each second channel sounding probe communicated with the reference terminal, and the application of the second beamforming coefficient is performed based on each of the second channel sounding probes.

18. In order to provide the aforementioned communication service, the beam manager (175) provides the system In the first cycle, each channel sounding probe communicates with the reference terminal, wherein each channel sounding probe communicates including the first signal and the subsequent signal. The system according to any one of claims 14 to 17, further configured to perform the following:

19. In order to apply the second beamforming coefficient, the beam manager (175) modulates the system, In the second cycle, the beamforming coefficient is updated based on the communication of each channel sounding probe in the first cycle. The updated beamforming coefficient is applied as the second beamforming coefficient, The system according to claim 18, configured to perform the following.

20. In order to provide the aforementioned communication service, the beam manager (175) provides the system The system according to any one of claims 14, further configured to determine, based on the subsequent channel state information, that the received signal quality at each of the reference terminals assigned to one beamformed spot beam (150) of the set of beamformed spot beams does not meet a threshold, and to apply the second beamforming coefficient, based on the determination that the received signal quality of the beamformed spot beam (150) does not meet the threshold.

21. The system according to any one of claims 14, wherein each coverage area (160) of the set of beam-formed spot beams (150) initially encompasses each of the first positions of the reference terminal.

22. Of the aforementioned number of mobile terminals, the first mobile terminal (120) is assigned as a reference terminal for the first beam-formed spot beam (150) of the set of beam-formed spot beams. The system according to any one of claims 14, wherein the beam manager (175) is further configured to cause the system to provide communication services to the first mobile terminal (120) and the second mobile terminal (120) via the first beamformed spot beam (150).

23. The system according to claim 22, wherein each coverage area (160) of the first beam-formed spot beam (150) includes the respective locations of the first and second mobile terminals (150).

24. The system according to claim 22 or 23, wherein the first and second mobile terminals (120) are located on separate aircraft.

25. The system according to any one of claims 14 to 24, wherein a first beam-formed spot beam (150) of the set of beam-formed spot beams is associated with a first reference terminal of the reference terminal, and the first beam-formed spot beam (150) has a first coverage area (160) including the first position of the first reference terminal when the first reference terminal is in the first position, and a second coverage area (160) including the second position of the first reference terminal when the first reference terminal is in the second position.

26. The system according to claim 25, wherein the second coverage area (160) at least partially overlaps the first coverage area (160).

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