Avoiding mobile satellite beam conflicts per link

Abstract

Methods, systems, and devices for avoiding mobile satellite beam conflict on a per-link basis are disclosed. Communication services may be provided to a mobile terminal via the forward and return links of each beamformed spot beam that tracks the movement of the mobile terminal. If a conflict occurs between the forward and / or return links of two or more beams, one of the conflicting forward or return links may be switched to a different resource element without changing the resource elements of the other forward and return links of the two or more beams, so that communication services can continue to be provided to the associated mobile terminal via the forward and return links.

Description

Technical Field

[0001] The following generally relates to communications including per-link mobile satellite beam interference avoidance.

Background Art

[0002] Communication devices may communicate with each other using wired connections, wireless (e.g., radio frequency (RF)) connections, or both. Wireless communication between devices may be performed using a wireless spectrum designated for a service provider, a wireless technology, or both. In some embodiments, 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 may be used to establish beams to increase frequency reuse, but providing a high level of frequency reuse in a satellite communication system using beamforming presents challenges.

Summary of the Invention

[0003] [[ID=十八]] The described technology relates to improved methods, systems, devices, and apparatuses that support per-link mobile satellite beam interference avoidance. For example, communication services may be provided to a mobile terminal as a spot beam formed by beamforming tracks the movement of the mobile terminal via the forward link and return link of each beamformed spot beam. When interference occurs between the forward links or return links of two or more beams, one of the interfering forward links or return links may be switched to a different resource element without changing the resource elements of the forward links and return links of the other two or more beams so that communication services can continue to be provided to the associated mobile terminal via the forward link and return link.

Brief Description of the Drawings

[0004] [Figure 1]Figure 1 shows an example of a satellite communications system that supports link-by-link mobile satellite beam conflict avoidance according to the embodiments described herein. [Figure 2A] Figure 2A shows an example of resources for a satellite communications system that supports mobile satellite beam interference avoidance, according to the embodiments described herein. [Figure 2B] Figure 2B shows an example of resources for a satellite communications system that supports mobile satellite beam interference avoidance, according to the embodiments described herein. [Figure 3] Figure 3 illustrates an example of a satellite communications system that supports link-by-link mobile satellite beam conflict avoidance according to the embodiments disclosed herein. [Figure 4] Figure 4 illustrates another embodiment of a satellite communications system that supports link-by-link mobile satellite beam conflict avoidance according to the embodiments disclosed herein. [Figure 5A] Figure 5A illustrates an exemplary timing diagram supporting link-by-link mobile satellite beam conflict avoidance according to the embodiments disclosed herein. [Figure 5B] Figure 5B illustrates an exemplary timing diagram supporting link-by-link mobile satellite beam conflict avoidance according to the embodiments disclosed herein. [Figure 6] Figure 6 shows a block diagram of a beam manager that supports link-by-link mobile satellite beam conflict avoidance according to the embodiments disclosed herein. [Figure 7] Figure 7 shows a block diagram of a terminal tracking device that supports link-by-link mobile satellite beam interference avoidance according to an embodiment disclosed herein. [Figure 8] Figure 8 shows a flowchart illustrating a method for supporting link-by-link mobile satellite beam conflict avoidance according to the embodiments disclosed herein. [Modes for carrying out the invention]

[0005] Beam handoff to a terminal in a satellite communication system is typically performed simultaneously for both the forward and return links to the terminal. However, the forward and return links often have different constraints and objectives that can influence allocation and contention avoidance decisions. By not considering individual links, resource element allocation / reallocation may occur more frequently than necessary, or less frequently than necessary. In either case, resources and / or time can be wasted when performing resource element allocation and beam contention avoidance.

[0006] Techniques are described for independently allocating resource elements to the forward and return links of a spot beam, and for independently determining conflict avoidance for forward and return link connections. Different resource elements may be used for the forward and return links of a spot beam. Resource element allocation and conflict avoidance can be determined independently for the forward and return links of the beam. Thus, forward link resource elements can be changed without changing return link resource elements, and vice versa. Independently allocating resource elements based on link type can provide better service and use limited satellite resources more efficiently.

[0007] 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 by reference to device diagrams, system diagrams, block diagrams, and flowcharts relating to link-by-link mobile satellite beam interference avoidance.

[0008] Figure 1 shows an embodiment of a satellite communications system 100 that supports link-by-link mobile satellite beam interference avoidance 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 them with communications services.

[0009] 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(s) 140. The access node transceivers 145 may also be configured to interface with the network 125 (e.g., the Internet) via 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.

[0010] The ground network may also include a beam manager 175 that tracks the mobile terminal 120 as communication services are provided to the terminal. The beam manager 175 may use beamformed spot beams associated with a reference terminal, as considered herein. For example, performing mobile terminal tracking and conflict avoidance between associated beams, as considered herein, may be controlled by the beam manager 175 using beams. The beam manager 175 may retrieve 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) to the satellite network 101 and / or terminal 120.

[0011] Although described herein as a single device, the beam manager 175 can alternatively be distributed across various elements of the entire system, e.g., the satellite network and / or the 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.

[0012] 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 ground-based fixed terminal), a mobile terminal mounted on a mobile platform (e.g., a boat, aircraft, ground-based vehicle, 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.

[0013] 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 be equipped with one or more antennas (e.g., a single antenna or an antenna array). In some embodiments, one or more satellites 105 equipped with multiple antennas may each include one or more antenna panels, each containing an array of evenly distributed antennas (which may also be called antenna elements). In some embodiments, a satellite may be equipped with an antenna array containing antennas that are unevenly distributed over a wide area. The ground network 135 may also accommodate access nodes 140, each containing multiple antenna array elements.

[0014] 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 processors for converting between radio frequency (RF) satellite communication signals and satellite terminal communication signals transmitted between the antenna and the satellite terminal receiver (e.g., performing frequency conversion, modulation / demodulation, multiplexing / demultiplexing, filtering, forwarding, etc.). 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 an aircraft fuselage). Additionally or alternatively, terminal 120 may include a transceiver, which may be mounted inside or outside the mobile platform, and may include circuitry and / or processors for performing various RF signal operations (e.g., receiving, performing frequency conversion, modulation / demodulation, multiplexing / demultiplexing, etc.).

[0015] The beam manager 175 may use one or more satellites to support beamforming techniques within the coverage area 155 of a satellite communication system, thereby increasing the utilization 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 leveraging 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) via a set of antennas according to, for example, a set of weighting coefficients. Similarly, multiple signals may be received by a receiving device (e.g., terminal 120) via 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).

[0016] 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).

[0017] The beam manager 175 can determine weighting coefficients to apply to the 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 emphasize signals transmitted using different spatial layers while reducing interference from signals transmitted in other spatial layers. Thus, processing the signals received at each antenna in the set of antennas (e.g., signals received at the set of antennas) using the MIMO matrix may result in the output of 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.

[0018] 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 (e.g., via the return link), or from the satellite to the terminal (e.g., via the forward link), or in both directions, and may include a sequence known to the transmitter and receiver (e.g., based on a terminal identifier or other parameters known to the transmitter and receiver). The receiving device (e.g., terminal or satellite) can use the received channel sounding probe to evaluate the connection by correlating the received channel sounding probe with the signal expected for the received channel sounding probe (e.g., to determine signal strength, interference, etc.) and make a decision based thereon. Due to the periodicity of the signal, the receiving device can know when to receive the signal.

[0019] The beam manager 175 can use beamforming techniques to shape or direct a communication beam along a spatial path between one or more satellites and the mobile terminal 120 within a geographic area. The beam manager 175 can form a communication beam by determining weighting factors for the antenna elements of the antenna array such that signals transmitted from or received by the antenna elements are combined in a way that results in constructive interference for signals propagating in a particular direction with respect to the antenna array while other signals experience destructive interference. Thus, beamforming can be used to transmit signals with energy focused in the direction of the communication beam and receive signals that reach 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 via the antenna.

[0020] In some embodiments, the beam manager 175 may apply weighting coefficients to the antenna to form multiple beams, each associated with a different direction, and these multiple beams may be used to simultaneously communicate multiple signals having the same frequency to different terminals (e.g., mobile terminals, ground stations). This may be referred to as multi-user MIMO. The weighting coefficients used for beamforming may be referred to as beam coefficients, and the multiple signals may be referred to as beam signals. The resulting beam may, as herein, be referred to as a beamformed spot beam, spot beam, or beam.

[0021] The beam manager 175 can calculate the amplitude and phase of each weighting coefficient, taking into account the geometric shape and location of the antenna array and reflectors, and the desired beam location. However, due to inaccuracies (e.g., satellite location, array orientation, geometric shape, atmospheric scintillation effect, etc.), such an approach may not be practical. Instead, the beam manager 175 can calculate the weighting coefficients using continuous or periodic measurements of MIMO propagation channel characteristics (e.g., pairwise channels from each system antenna element to each terminal antenna element) and adjust the weighting coefficients based on the changing channel characteristics. The measured MIMO channel characteristics may include pairwise gain and phase responses, as well as noise levels, and may be referred to as MIMO channel state information (CSI). Once MIMO CSI is available, the beam manager 175 can derive the weighting coefficients by solving a set of equations or by applying a set of adaptive formulas. Various beamformer computation and adaptation techniques can be used, including least-mean-squares (MMSE) beamformers, zero-forcibly-forced beamformers, and MIMO spherical decoders.

[0022] The measurement of MIMO CSI may include the cooperation of at least one terminal for each beam. The situation may be different in the forward link direction (from satellite to terminal) and the return link direction (from terminal to satellite). In the return link, each terminal may transmit a channel probing signal that can be orthogonal to the probing signals of other terminals. The satellite may determine which channel probing signal is transmitted from each terminal, process the signal, and estimate the channel parameters of the channel corresponding to that terminal. Thus, the MIMO CSI of the return link can be locally calculated on the satellite side for the terminal that transmits the channel probing signal. On the other hand, in the forward link, the satellite may transmit a channel probing signal. 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 signal corresponding to each transmitting antenna element. Furthermore, each such terminal can send back the MIMO CSI to the satellite using the return link control channel.

[0023] The spot beam generated in this way can be adjusted according to the MIMO CSI provided by the terminal, and each beam can illuminate the direction of each such terminal. Each beam has a finite coverage area 160 (e.g., a few kilometers in diameter), and thus can illuminate additional terminals that may be present in the vicinity of the CSI generation terminal. Since this can unnecessarily increase the CSI reporting channel overhead, these additional terminals may not provide CSI. The terminals used to provide MIMO CSI for each beam can be regarded as the reference terminals for that beam. In some embodiments, the coverage area 160 of the beam can be determined based on the wavelength of the carrier wave and the diameter of the aperture. The coverage area 160 can correspond, for example, to the footprint where the power level of the beam is higher than a threshold or the power level drop-off away from the center of the beam is less than a threshold (e.g., 3 decibels (dB) or 6 dB). In some embodiments, the coverage area 160 can be based on the beam width of the beam.

[0024] 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 175 can use separate beams for each of the one or more terminals. In some embodiments, two or more of the terminals 120 may be close together (e.g., at an airport) so that the beam manager 175 can illuminate the terminals with the same beam. In the former case, each terminal on the aircraft may be a reference terminal for its beam, and in the latter case, one of several terminals on the aircraft may be a reference terminal for the beam.

[0025] As the mobile terminal 120 moves through the airspace, the MIMO CSI changes, which may alter the beam direction. The beam manager 175 can adjust the beam direction based on the altered MIMO CSI so that the reference terminal remains at or near the center of the beam. Thus, as the reference terminal moves, the beam can follow its movement, as will be further described herein.

[0026] The beam manager 175 may associate a beamformed spot beam 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 carry a signal (e.g., a modulated signal carried on the forward or return link of the beamformed spot beam) in one of the repetition time slots. In this way, the forward or return links of the beamformed spot beams may spatially overlap without interference if they are associated with different combinations of frequency / time resources. In addition, the beam manager 175 may use multiple polarizations so that two forward or return links of the beamformed spot beams may spatially overlap without interference if they are associated with different polarizations. Thus, forward or return links of beamformed spot beams can spatially overlap without interference if they relate to different combinations of resources (e.g., frequency channel / time slot / polarization combinations). These different combinations may be known as resource elements, which together form a set of resource elements that the beam manager 175 can use to communicate signals over the links. The beam manager 175 can control the association of links with resource elements and when reassigning resource elements, as discussed herein.

[0027] The discussion herein refers to the assignment of resource elements to the forward and return links of a beamformed spot beam; alternatively, it may be said that the forward and return links are assigned to resource elements. These terms may be considered synonymous herein. That is, the assignment of a resource element to a forward or return link may be considered equivalent to the assignment of a forward or return link to a resource element. Similarly, the assignment of a resource element to a forward or return link may be considered equivalent to the assignment of a forward or return link to a resource element.

[0028] As discussed 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 may enable communication services associated with a mobile terminal to be provided via the same beamformed spot beam as the mobile terminal moves through the coverage area of ​​the satellite communication system. This may reduce the number of inter-beam handoffs of mobile terminals and mitigate the performance degradation and communication interruptions that may result from inter-beam handoffs. For example, inter-beam handoffs may require the beam handing off the terminal to coordinate with the beam receiving the terminal, which may require communication across several communication layers to transfer terminal information between access points (e.g., gateways, gateway modems) serving the beams and to verify the transfer. This can result in performance degradation and inter-beam communication interruptions.

[0029] Two movable beamformed spot beams may sometimes experience inter-beam competition when tracking mobile terminals, such as when the corresponding forward or return links spatially overlap while using the same resource elements (e.g., the same frequency channel, time slot, and polarization combination). However, these competitions can be resolved using the competition avoidance procedures discussed herein. For example, when such competition occurs (e.g., based on the inter-link interference metric meeting a threshold), the beam manager 175 may change one of the competing mobile terminals to a different resource element for communication over the forward or return link. As a result, there is little to no performance degradation. Furthermore, since it may involve only a single link of the beam (e.g., without communication between access points serving different beams), it is possible to avoid the communication interruption associated with inter-beam handoffs while still using the same resource elements for the other link of the beam.

[0030] Furthermore, as the reference terminal moves, it can remain at a central position within the beam's coverage area. This can potentially maintain a high SNR for the reference terminal, resulting in higher overall communication speed and efficiency associated with the reference terminal.

[0031] Figure 2A shows an embodiment of resource 200-a for a satellite communications system supporting mobile satellite beam interference avoidance, according to the embodiments described herein. Resource 200-a may correspond to frequency division of a satellite communications system. For example, frequency range 205 (e.g., frequency band) may include 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 carry signals between the satellite network and terminals. Resource 200-a may correspond to frequency channels 210 of frequency range 205.

[0032] 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 carry a single modulated signal. Information (e.g., data, control information) may be modulated on the modulated signal using various single-carrier or multi-carrier modulation techniques (e.g., orthogonal frequency division multiplexing (OFDM), direct sequence spread spectrum (DSSS), linear precode OFDM (LP-OFDM)). As considered herein, each link of beamformed spot beams may be associated with one or more frequency channels 210 (e.g., by a beam manager 175) to provide communication to a mobile terminal while the mobile terminal is being tracked.

[0033] 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 no other types of resources exist, 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.

[0034] Figure 2B shows an embodiment of a resource element 250 for a satellite communications system that supports link-by-link mobile satellite beam conflict avoidance, according to an embodiment described herein. In this embodiment, frequency channel 210 may be used again to carry signals related to the terminal. In addition, frequency channel 210 may be time-multiplexed. That is, each frequency channel 210 may be configured to carry signals to and from 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 carry signals to and from 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 carry a single modulated signal during each time slot t. Information (e.g., data, control information) may be modulated on the modulated signal using various single-carrier or multi-carrier modulation techniques (e.g., OFDM, DSSS, LP-OFDM) (e.g., by beam manager 175) to provide communication to the mobile terminal (e.g., via forward and return links) while the mobile terminal is being tracked, as considered herein.

[0035] When period 215 ends, the process may be repeated so that each frequency channel 210 further carries signals associated with different terminals within the resource period. As a result, the beam manager 175 may use the frequency channel 210 for communication with terminals during one time slot t for each period 215. In some embodiments, the beam manager 175 may assign terminals two or more time slots per period, and therefore communication with terminals may occur over two or more time slots per period for frequency channel 210.

[0036] 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.

[0037] In addition to being multiplexed by time or frequency, different polarizations may be used to define resource elements to be assigned to a 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 a 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.

[0038] 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.

[0039] Figure 3 illustrates an embodiment of a satellite communications system 300 that supports link-by-link mobile satellite beam conflict avoidance according to an embodiment disclosed herein. The satellite communications system 300 may be an embodiment 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., beamformed spot 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.

[0040] Terminal 120 may be located on a mobile platform or vehicle, such as an automobile, boat, or aircraft, and may therefore be considered a mobile terminal 120. In some embodiments, each vehicle may include a single mobile terminal. In other embodiments, one or more 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.

[0041] 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 while the mobile terminal is in motion, controlled by a beam manager 175. For clarity, only a single movable beamformed spot beam 150-a is illustrated in Figure 3, associated with a single mobile terminal 120-a. Although not illustrated in Figure 3, a movable beamformed spot beam 150 may also be associated with one or more other mobile terminals 120.

[0042] 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. Each beamformed 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, for example, to footprints where 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).

[0043] In some embodiments, a beamformed spot beam associated with a reference terminal may be formed (e.g., controlled by a beam manager 175) to include the physical location of the terminal within the coverage area of ​​the beamformed spot beam. For example, as shown in Figure 3, a mobile terminal 120-a acting as a reference terminal may be physically located 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 located 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 the mobile terminals via the beam links. For example, a forward link may be used to transmit information to the mobile terminals, and a return link may be used to receive information from the mobile terminals associated with the beamformed spot beams. In the embodiment shown in Figure 3, the forward link 310 and return link 315 of the beamformed spot beam 150-a may be used to transmit information to and receive information from the mobile terminal 120-a via the beamformed spot beam 150-a, respectively, as controlled by the beam manager 175.

[0044] In some embodiments, the beam manager 175 may cause a 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 mobile 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 mobile terminal as indicated by arrow 330. In some embodiments, 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.

[0045] To track or follow a mobile terminal, the beamforming coefficient may be modified by the beam manager 175 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 touch with the moving physical location of the moving mobile terminal and thereby track the mobile terminal. For example, as the mobile terminal 120-a moves from location A to location 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 location of the mobile terminal 120-a. This may enable communication services associated with the mobile terminal to be provided through the same beamformed spot beam as the mobile terminal moves through the coverage area of ​​the satellite communication system. For example, the beam manager 175 can provide continuous communication services to the mobile terminal 120-a via the forward link 310 and return link 315 of the beamformed spot beam 150-a without handoff as the mobile terminal moves between location A and location B.

[0046] In some embodiments, the beam manager 175 may not change the beamforming coefficient associated with the mobile terminal 120 while the mobile terminal is stationary, because the coverage area 160 of the beamformed spot beam 150 may already correspond to the physical location of the stationary terminal. In other embodiments, the beam manager 175 may change the beamforming coefficient even when the mobile 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 coefficient used for all terminals, even if only one terminal moves.

[0047] In some embodiments, to track a mobile terminal 120, the beam manager 175 may adjust the spot beam coverage area 160 based on measurements of signals communicated with the mobile terminal via forward and return links (e.g., moving the spot beam). In some embodiments, the terminal 120 periodically provides channel state information to the satellite network 101 (e.g., via the return link), 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, which may subsequently induce a change in the beam weighting coefficients calculated by the beam manager 175. This beamformer adaptive processing allows the beam center to be continuously identical to the aircraft's location (to follow the aircraft).

[0048] 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 in such a manner that the mobile terminal remains at a central position within the coverage area as it moves. This may allow for maintaining a high SNR for the mobile terminal, which may also result in higher overall communication speed and efficiency associated with the mobile terminal.

[0049] In some embodiments, the beam manager 175 may determine the location of a mobile terminal based on information received from the mobile terminal, such as location coordinates (determined via a positioning system such as GPS), speed, direction, or other information associated with the mobile terminal. This information may be received from the mobile terminal via a return link. In some embodiments, the beam manager 175 may determine the location of a mobile terminal based on information from outside the mobile terminal, such as based on radar or other signals.

[0050] In some embodiments, a satellite communication system may provide communication services to one or more mobile terminals via beamformed spot beams associated with the terminals. For example, in Figure 3, a 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 them as they move within the coverage area 155 of the satellite communication system.

[0051] 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) a mobile terminal (e.g., using a forward link and / or return link). 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 (e.g., via a forward link) and / or by the mobile terminal (e.g., via a return link).

[0052] In some embodiments, to generate beamformed spot beams, the beam manager 175 may apply beamforming coefficients to convert between beam signals associated with each of the beamformed spot beams and component signals associated with multiple antenna elements of a satellite communication system. For example, to generate a forward link for transmitting information to a mobile terminal, the beam manager 175 may apply beamforming coefficients to the beam signal (containing information) to obtain component signals that can be applied to the antenna elements, and to generate a return link for receiving information from the mobile terminal, the beam manager 175 may apply beamforming coefficients to the component signals received from the mobile terminal at the antenna elements to obtain beam signals containing information.

[0053] 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 beamformed spot beam 150 between the satellite 105 and the coverage area 160. The beam manager 175 may base the beamforming coefficients on initial channel state information so that the coverage area 160 of the beam 150 can encompass each of the first locations (e.g., location A) of the associated terminals 120.

[0054] For example, the beamforming coefficient may include multiple sets of forward-link beamforming coefficients and multiple sets of return-link beamforming coefficients.

[0055] The beam manager 175 may apply a first set of forward link beamforming coefficients in the first time 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 in the first time. The transmission of the first set of forward link component signals to the mobile terminals via the antenna element may form a beamformed spot beam of the forward link, each corresponding to one of the mobile terminals in the first time.

[0056] The beam manager 175 may apply a second set of forward link beamforming coefficients in the second time 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 the antenna element in the second time. The transmission of the second set of forward link component signals to the mobile terminal via the antenna element may form a forward link of beamformed spot beams, each corresponding to a mobile terminal in the second time. One or more of the beamformed spot beams in the second time may have moved from their corresponding beamformed spot beams in the first time in order to track the movement of the corresponding mobile terminal.

[0057] In the return link, the beam manager 175 may apply a first set of return link beamforming coefficients for the first time to the return link component signals received from the mobile terminals via the antenna elements in the first time. By applying the first set of return link beamforming coefficients, a return link of beamformed spot beams can be formed for the first time, each corresponding to one of the mobile terminals.

[0058] The beam manager 175 may apply a second set of return link beamforming coefficients in the second time to the return link component signals received from the mobile terminal via multiple antenna elements in the second time. By applying the second set of return link beamforming coefficients, a beamformed spot beam return link can be formed for the second time. One or more of the beamformed spot beams in the second time may have moved from their corresponding beamformed spot beams in the first time in order to track the movement of the corresponding mobile terminal.

[0059] 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 each second location of the 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.

[0060] In some embodiments, the subsequent signal may include each subsequent channel sounding probe communicated with the mobile terminal (e.g., via a forward link) and / or by the mobile terminal (e.g., via a return link). 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.

[0061] In some embodiments, the beam manager 175 may modify beamforming coefficients and apply them to convert between the beam signal and component signals associated with multiple antenna elements of the satellite network. The modified beamforming coefficients may be based on subsequent channel state information so that a new beam coverage area (e.g., coverage area 160-a2) can encompass each of the second locations of the mobile terminal (e.g., location B).

[0062] The determination of the subsequent location of a mobile terminal and the subsequent modification of the beamforming coefficient can be repeated by the beam manager 175 as desired, in terms of frequency and duration. In this way, multiple beamformed spot beams 150 can track the movement of a reference terminal 120 across the entire coverage area 155 of the satellite communication system while communication services are being provided to the terminals via forward and return links. In some embodiments, the beam manager 175 may move the beamformed spot beams 150 so as to adequately track each mobile terminal of the beamformed spot beam 150, such that the relevant coverage area at the current location overlaps with the coverage area at the previous location. That is, each movement of the beamformed spot beam 150 may move the beam by a fraction of the diameter of the beamformed spot beam 150 (e.g., radius, or a fraction such as half the radius).

[0063] 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 the beamforming coefficients based on the received signal quality (e.g., forward link signal quality measured at a reference terminal, or return link signal quality measured at a satellite communication system) falling below a threshold. This may make it possible to maintain high signal quality associated with the mobile terminal, which may also result in higher 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.

[0064] In some embodiments, the beam manager 175 may cause the beam's forward and return links to use different resource elements to provide communication services to mobile terminals while tracking them. For example, the beam's forward link may use a different combination of frequency channel, time slot, and polarization than the beam's return link.

[0065] In some embodiments, the beam manager 175 may cause two or more beam forward links or return links to use different resource elements to provide communication services to each mobile terminal while tracking the mobile terminals. For example, the forward link of the first beam may use a different combination of frequency channel, time slot, and polarization than the forward link of the second beam, or the return link of the first beam may use a different combination of frequency channel, time slot, and polarization than the return link of the second beam. By using different resource elements, interference between the forward links of separate beams, or between the return links of separate beams, can be reduced or eliminated, even if the mobile terminals may be in close proximity to each other.

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

[0067] In some embodiments, when two beamformed spot beams use the same resource element for their forward or return links, the beam manager 175 may independently change one of the beam's forward or return links to a different resource element based on interference between the beam's forward or return links (e.g., an interference metric between the forward or return links that satisfies a threshold). As a result, per-link beam contention avoidance can be performed independently by the beam manager 175. Furthermore, because the beam's forward and return links may use different resource elements, the beam manager 175 may allow a forward or return link to continue using its resource element even if the beam manager 175 assigns a different resource element to the other link.

[0068] Figure 4 illustrates another embodiment of the satellite communication system 400 that supports link-by-link mobile satellite beam conflict avoidance according to the embodiments disclosed herein. The satellite communication system 400 may be an embodiment of the satellite communication system considered herein, such as the satellite communication system 100 or 300 described with reference to Figure 1 or Figure 3, or embodiments thereof.

[0069] 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., beamformed spot beams 150-a and 150-b) for communication with mobile terminals 120 (e.g., mobile terminals 120-a and 120-b) as the beamformed spot beams track the mobile terminals. Each beamformed spot beam 150 may include a forward link 310 for transmitting information to the mobile terminals 120 and a return link 315 for receiving information from the mobile terminals 120. For example, beamformed spot beam 150-a may include forward link 310-a and return link 315-a, and beamformed spot beam 150-b may include forward link 310-b and return link 315-b.

[0070] In some embodiments, each beamformed spot beam 150 may be associated with a different mobile terminal 120. For example, the beam manager 175 may associate a beamformed spot beam 150-a with mobile terminal 120-a (so that information can be transmitted to and received from mobile terminal 120-a via the forward link 310-a), and the beam manager 175 may associate a beamformed spot beam 150-b with mobile terminal 120-b (so that information can be transmitted to and received from mobile terminal 120-b via the forward link 310-b). The beamformed spot beam 150 may have a coverage area 160 (e.g., coverage areas 160-a and 160-b). For clarity, the moving beamformed spot beam 150-a and associated coverage area 160-a corresponding to mobile terminal 120-a are shown with solid lines, and the moving beamformed spot beam 150-b and corresponding coverage area 160-b corresponding to mobile terminal 120-b are shown with dashed lines.

[0071] Figure 4 shows an embodiment in which two mobile terminals 120-a and 120-b pass close to each other as they travel along their respective paths 460-a and 460-b. The path 460-b corresponding to mobile terminal 120-b, as well as beam 150-b and its corresponding coverage area 160-b, are shown as dashed lines. Mobile terminals 120-a and 120-b can travel along paths 460-a and 460-b from their respective starting points, represented by A1 and A2, to their respective ending points, represented by G1 and G2. The beamformed spot beams 150-a and 150-b are shown as being on an aircraft, but other mobile platforms may also be used. The beamformed spot beams 150-a and 150-b can track mobile terminals 120-a and 120-b, respectively, while communication services can be provided to the mobile terminals through these beams as the mobile terminals move along the route (for example, by the beam manager 175 coordinating the respective coverage areas 160-a and 160-b of the beamformed spot beams 150-a and 150-b in conjunction with the movement of the mobile terminals).

[0072] As the mobile terminals 120 approach each other, interference between the forward or return links of the associated beamformed spot beams 150 may increase (for example, when the forward or return links of the beam, or both, use the same resource element). As discussed herein, the beam manager 175 may cause one or more of the links to switch to different resource elements in order to mitigate interference.

[0073] 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, beamformed spot beams 150-a and 150-b may overlap when their respective coverage areas 160-a and 160-b overlap. 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.

[0074] Further along paths 460-a and 460-b, mobile terminals 120-a and 120-b may arrive at another point represented by C1 and C2, where one or more of the mobile terminals may enter the coverage area of ​​a beam that does not support (e.g., does not provide or track communication services) the mobile terminals (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 the beamformed spot beam 150-b, and / or mobile terminal 120-b may enter the coverage area 160-a of the beamformed spot beam 150-a. At some point before or after this, interference between any of the links of the beamformed spot beam 150-a and beam 150-b (e.g., forward links 310-a and 310-b, return links 315-a and 315-b) may rise to an unacceptable level. For example, the interference metric between the forward link or the return link may meet a threshold (e.g., match or exceed). As discussed herein, steps may be taken (e.g., by the beam manager 175) to improve the interference (e.g., to avoid competition between the forward link or the return link of the beam).

[0075] Mobile terminals 120-a and 120-b may remain within the coverage areas 160-a and 160-b of both beamformed spot 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 beamformed spot beam 150-b, and mobile terminal 120-b may no longer be within the coverage area 160-a of beamformed spot beam 150-a. The beams may still overlap even 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 the beamformed spot beams 150-a and 150-b may still overlap.

[0076] The beamformed spot 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, the beamformed spot 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, the beamformed spot beams 150-a and 150-b may remain separated and non-overlapping, as long as the mobile terminals remain sufficiently far apart from each other.

[0077] As considered with respect to Figures 2A and 2B, the beam manager 175 may use resource elements to provide communication services to mobile terminals via the forward and return links of the beamformed spot beams. In some embodiments, if the forward links of two beams do not conflict (e.g., low interference between the forward links), the forward links may use the same resource elements to transmit communication signals to their respective mobile terminals. For example, as long as the respective interference metrics between the forward links 310-a and 310-b of the beamformed spot beams 150-a and 150-b remain below a threshold, the beam manager 175 may use the same resource elements to provide communication to mobile terminals 120-a and 120-b via the forward links 310-a and 310-b, as considered herein.

[0078] In some embodiments, if the return links of two beams do not conflict (e.g., there is low interference between the return links), the return links may use the same resource elements to receive communication signals from their respective mobile terminals. For example, as long as the respective interference metrics between the return links 315-a and 315-b of the beamformed spot beams 150-a and 150-b remain below a threshold, the beam manager 175 may use the same resource elements to receive communications from mobile terminals 120-a and 120-b via the return links 315-a and 315-b, as considered herein.

[0079] In some embodiments, if the forward link of one beam and the return link of another beam do not conflict (e.g., low interference between links), the links may use the same resource elements to communicate signals to and from their respective mobile terminals. For example, as long as the respective interference metrics between the forward link 310-a and the return link 315-b of the beamformed spot beams 150-a and 150-b remain below a threshold, the beam manager 175 may use the same resource elements to transmit communication signals to and from mobile terminal 120-a via the forward link 310-a and the return link 315-b, as considered herein.

[0080] As mobile terminals 120-a and 120-b approach each other (e.g., from A1 / A2 through B1 / B2 and C1 / C2 to D1 / D2), interference between the corresponding beam links may increase. Increased interference may mean that communication over the forward and / or return links of separate beams (e.g., when using the same resource elements) is subjected to excessive inter-beam interference. When the interference rises to a certain level (e.g., the interference metric between the forward and / or return links of the beams meets a threshold), the beam manager 175 may take steps to avoid link contention (e.g., improve inter-link interference), as discussed herein.

[0081] In some embodiments, the interference metric may correspond to measured interference in one or both forward and / or return links of the beam. For example, the interference metric may correspond to the signal intensity of the forward or return link of the beam associated with the first terminal, as measured at a second terminal. Additionally or alternatively, the interference metric may correspond to signal degradation (e.g., SNR reduction) of the beam (e.g., associated with the forward or return link), and the threshold may correspond to a specific level of the metric or a specific amount of degradation (e.g., 3 dB or 6 dB SNR loss). In some embodiments, interference may be measured at a receiving device of the communication link. For example, 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).

[0082] In some embodiments, the interference metric may correspond to channel correlation. For example, the interference metric may be based on the correlation between channel state information of two mobile terminals. The interference metric may be frequency-dependent.

[0083] In some embodiments, the interference metric may correspond to the estimated interference of one or both of the forward and return links. For example, the estimated interference may be based on the distance between the mobile terminals, or an algorithm that estimates the interference between the forward or return links of the associated beams. In some embodiments, the interference metric may be based on the distance between the 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.

[0084] In some embodiments, a single beam may be used to provide communication services to two or more mobile terminals. For example, the beam manager 175 may assign one of the terminals to be a reference terminal that the beam tracks, while providing communication services over the forward and return links. The reference terminal may be 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 over a beamformed spot beam generated via beamforming coefficients referencing the reference terminal. This can be achieved by sharing forward and return link resources among the mobile terminals. For example, communication services may be provided over the same beam to two or more mobile terminals on the same frequency channel, but on different time slots corresponding to the mobile terminals (e.g., by the beam manager 175). In some embodiments, the same frequency and time slot may be used for mobile terminals by further subdividing the time slots, which may be allocated to different users, (e.g., into MAC layer frames).

[0085] 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 forward link of the 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 forward link of the same shared beam. In some cases, unicast and multicast messages may be communicated to mobile terminals over different beams. In other cases, unicast and multicast messages may be communicated to mobile terminals over the same beam. For example, if a communication service is provided to two or more 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.

[0086] Figures 5A and 5B show exemplary timing diagrams 500 and 550 that support link-by-link mobile satellite beam conflict avoidance according to embodiments disclosed herein. Timing diagrams 500 and 550 represent the forward link 310 and return link 315 of beamformed spot beams 150-a and 150-b in 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 links. As considered with respect to Figures 3 and 4, increased interference may occur if mobile terminals move closer to each other while the same resource elements are being used by the forward link or return link of the corresponding beam. As shown in timing diagrams 500 and 550, one of the forward links (e.g., forward link 310-b) or one of the return links (e.g., return link 315-b) may be switched to a different resource element (e.g., by beam manager 175) to mitigate interference.

[0087] Timing diagram 500 shows an embodiment in which the forward links 310-a and 310-b of the beamformed spot beam 150 interfere with each other, and timing diagram 550 shows an embodiment in which the return links 315-a and 315-b of the beamformed spot beam 150 interfere with each other. For simplification, other links (i.e., the return links 315-a and 315-b in timing diagram 500, and the forward links 310-a and 310-b in timing diagram 550) are depicted as not interfering, so that the avoidance of conflict between the forward links and the avoidance of conflict between the return links can be considered independently.

[0088] As shown in timing diagram 500, the same resource element A may originally be assigned to both forward links 310-a and 310-b, while different resource elements C and D may be assigned to return links 315-a and 315-b (e.g., by beam manager 175). The original assignment may be performed at or earlier than start time t1, which may correspond to mobile terminals 120-a and 120-b being in A1 / A2. Thus, both forward links 310-a and 310-b may use the same resource element A at start time t1 for the satellite communication system to transmit communication information to their respective mobile terminals 120-a and 120-b.

[0089] Mobile terminals can be at a considerable distance from each other at start time t1 so that the beamformed spot beams 150-a and 150-b do not compete with each other (for example, even if the same resource element A is assigned to the forward link 310-a and the return link beam 310-b, interference between the forward link 310-a and the return link beam 310-b may be slight, if any). Thus, the interference metric between the forward links 310 can be relatively low (e.g., below the threshold). In some embodiments, the same resource element A can be semi-statically assigned to the forward links 310-a and 310-b (e.g., by the beam manager 175) so that each terminal receives and monitors communication signals through the same resource element until it receives an instruction to switch its forward link to a different resource element.

[0090] At time t2, interference between forward links 310-a and 310-b may rise to an unacceptable level (e.g., the interference metric may satisfy a first threshold). In some embodiments, this may correspond to one of the mobile terminals 120 entering the coverage area of ​​the other beamformed spot 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 when the interference metric value satisfies a first threshold. Several potential interference metrics and thresholds are considered with respect to Figure 4.

[0091] To improve interference, one of the beam's forward links may be changed to a different resource element. For example, at time t2, in response to the interference metric meeting a first threshold, the beam manager 175 may cause the forward link 310-b of the beamformed spot beam 150-b to switch the resource element for the satellite communication system to transmit communication signals to the mobile terminal 120-b (for example, by assigning resource element B to forward link 310-b instead of resource element A). This may involve changing one or more of the frequency channels, time slots, polarizations, or other resources (e.g., one or more codes) associated with forward link 310-b to be different from those used by forward link 310-a. In some embodiments, resource element B may be orthogonal to resource element A.

[0092] Many factors can be used to determine which of the interfering spot beams should be changed to a different resource element. In some embodiments, the decision may be based on the priority of the mobile terminals associated with the interfering beams. For example, a spot beam associated with the mobile terminal with the lowest priority among competing mobile terminals may be changed to a different resource element. For instance, a mobile terminal associated with beamformed spot beam 150-b may have a lower priority than a mobile terminal associated with beamformed spot beam 150-a.

[0093] In some embodiments, the decision may be based on the demand of the mobile terminals associated with the interference beam. For example, the spot beam associated with the mobile terminal with the lowest demand among competing mobile terminals may be changed to a different resource element. For example, a mobile terminal associated with beamformed spot beam 150-b may have lower demand than a mobile terminal associated with beamformed spot beam 150-a. In other embodiments, the spot beam associated with the mobile terminal with the highest demand among competing mobile terminals may or may not be changed depending on the throughput of the resource element. For example, a mobile terminal associated with beamformed spot beam 150-b may have higher demand than a mobile terminal associated with beamformed spot beam 150-a, and resource element B may be associated with higher throughput than resource element A.

[0094] In some embodiments, if a resource element is unavailable, a different resource element may be reallocated from another nearby terminal. For example, resource element B may be reallocated from a nearby terminal that may have a lower priority than the terminal associated with the beamformed spot beam 150-b.

[0095] In some embodiments, resource element B may be the same as either resource element used by the beam's return link 315-a or 315-b (for example, resource element B may be the same as resource element C or resource element D). In some embodiments, resource element B may be different from resource elements C and D used by the return link 315-a or 315-b.

[0096] Since communication signals can be transmitted to mobile terminals 120-a and 120-b via forward links 310-a and 310-b using different resource elements after time t2, interference between forward links 310-a and 310-b can be significantly reduced or may no longer exist. Thus, the satellite communication system can continue to transmit communication signals to mobile terminals 120-a and 120-b via forward links 310-a and 310-b without an inter-beam handoff being performed. Furthermore, since return links 315-a and 315-b may be using different resource elements (e.g., resource elements C and D versus resource elements A and B) than those used by forward links 310-a and 310-b, the satellite communication system can also continue to receive communication signals from mobile terminals 120-a and 120-b via return links 315-a and 315-b without any change in the resource elements of the return links.

[0097] At time t3, the beam forward links 310-a and 310-b may again use the same resource element. For example, at time t3, forward link 310-b may revert to its original resource element (for example, by the beam manager 175 reassigning resource element A to forward link 310-b instead of resource element B) in order to transmit a communication signal to mobile terminal 120-b. Alternatively, forward links 310-a and 310-b may continue to use different resource elements. For example, instead of changing the resource element of forward link 310-b back to resource element A, the beam manager 175 may allow beam 310-b to continue using resource element B after t3.

[0098] Time t3 may correspond when interference or potential interference between forward links 310-a and 310-b is no longer at an unacceptable level (for example, when the interference metric does not meet, does not exceed, 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 when the mobile terminals are at a certain distance from each other. Several potential interference metrics and thresholds are considered with respect to Figure 4.

[0099] After time t3, as long as the interference metric between forward links 310-a and 310-b remains below a threshold (e.g., a first or second threshold), the satellite communication system may continue to transmit communication signals to mobile terminals via forward links 310-a and 310-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 interference between forward links 310-a and 310-b rises to that level again (e.g., the interference metric again satisfies the first threshold), the beam manager 175 may cause one of the forward links (e.g., forward link 310-b) of the beam (e.g., beamformed spot beam 150-b) to switch back to a different resource element than the other forward link, and in some embodiments, back again. This switching may be performed each time the interference between the forward links rises to that level. As a result, inter-beam handoffs and changes to the return link can be avoided.

[0100] As shown in timing diagram 550, the same resource element C can originally be assigned to both return links 315-a and 315-b, while different resource elements A and B can be assigned to forward links 310-a and 310-b (e.g., by beam manager 175). Thus, both return links 315-a and 315-b may use the same resource element C at start time t1 for the satellite communication system to receive communication information from their respective mobile terminals 120-a and 120-b.

[0101] At time t1, the beamformed spot beams 150-a and 150-b may not compete with each other (for example, even if the same resource element C is assigned to return links 315-a and 315-b, interference between return links 315-a and 315-b may be slight, if any). Thus, the interference metric between return links 315 may be relatively low (e.g., below the threshold). In some embodiments, the same resource element C may be semi-statically assigned to return links 315-a and 315-b (e.g., by the beam manager 175) so that each terminal transmits communication signals through the same resource element until it receives an instruction to switch its return link to a different resource element.

[0102] At time t2, the interference between return links 315-a and 315-b may rise to an unacceptable level (e.g., the interference metric may meet the first threshold). Several potential interference metrics and thresholds are considered with respect to Figure 4.

[0103] To improve interference, one of the beam's return links may be changed to a different resource element. For example, at time t2, in response to the interference metric meeting a first threshold, the beam manager 175 may cause the return link 315-b of the beamformed spot beam 150-b to switch resource elements (e.g., by assigning a different resource element D to the return link 315-b than resource element C) so that the satellite communication system can receive communication signals from the mobile terminal 120-b. In some embodiments, resource element D may be orthogonal to resource element C.

[0104] In some embodiments, resource element D may be the same as either resource element used by the beam's forward link 310-a or 310-b (for example, resource element D may be the same as resource element A or resource element B). In some embodiments, resource element D may be different from resource elements A and B used by the forward link 310-a or 310-b.

[0105] Since communication signals can be received from mobile terminals 120-a and 120-b via return links 315-a and 315-b after time t2 using different resource elements from each other, interference between return links 315-a and 315-b can be significantly reduced or may no longer exist. Thus, the satellite communication system can continue to receive communication signals from mobile terminals 120-a and 120-b via return links 315-a and 315-b without an inter-beam handoff being performed. Furthermore, since forward links 310-a and 310-b may be using different resource elements (e.g., resource elements A and B versus resource elements C and D) than those used by return links 315-a and 315-b, the satellite communication system can also continue to receive communication signals from mobile terminals 120-a and 120-b via forward links 310-a and 310-b without any change in the resource elements of the forward links.

[0106] At time t3, the beam return links 315-a and 315-b may again use the same resource element. For example, at time t3, return link 315-b may revert to its original resource element (e.g., by beam manager 175 reassigning resource element C to return link 315-b instead of resource element D) in order to receive a communication signal from mobile terminal 120-b. Alternatively, return links 315-a and 315-b may continue to use different resource elements. For example, instead of changing the resource element of return link 315-b back to resource element C, beam manager 175 may, after t3, allow return link 315-b to continue using resource element D.

[0107] Time t3 may correspond to a situation where the interference or potential interference between return links 315-a and 315-b is no longer at an unacceptable level (for example, the interference metric may not meet, exceed, or fall 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 t3, the second threshold may be the same as, or different from, the first threshold used at time t3. In addition, the interference metric and / or interference metric value associated with return link 315 may be the same as, or different from, the one associated with forward link 310.

[0108] After time t3, as long as the interference metric between return links 315-a and 315-b remains below a threshold (e.g., a first or second threshold), the satellite communication system may continue to receive communication signals from mobile terminals via return links 315-a and 315-b using the same resource element (e.g., resource element C) at least until time t4. However, if the interference between return links 315-a and 315-b rises to that level again (e.g., the interference metric again satisfies the first threshold), the beam manager 175 may cause the return link (e.g., return link 315-b) of one of the beams (e.g., beamformed spot beam 150-b) to switch back to a different resource element than the other return link, and in some embodiments, back again. This switching may be performed each time the interference between return links rises to that level. As a result, inter-beam handoffs and forward link changes can be avoided.

[0109] In some cases, due to different characteristics of the forward and return links (e.g., different frequencies, transmit power vs. receive power / sensitivity, etc.), the times associated with the conflict avoidance procedure (e.g., times t2 and t3) may be located on the timing diagram 500 associated with forward link conflict avoidance, relatively different from the timing diagram 550 associated with return link conflict avoidance.

[0110] The methods considered with respect to timing diagrams 500 and 550 can be performed independently at desired frequencies to avoid competition between interfering forward links or interfering return links. In some cases, inter-beam forward link interference and return link interference may occur simultaneously or nearly simultaneously. In those cases, forward link competition avoidance and return link competition avoidance can be performed simultaneously (e.g., in the same competition avoidance cycle) (e.g., by beam manager 605). Alternatively, forward link competition avoidance may occur at a different time than return link competition avoidance.

[0111] In some cases, link interference may involve three or more beams. For example, the first beam may have a forward link that interferes with the forward link of the second beam, and a return link that interferes with the return link of the third beam. In such cases, the avoidance of interference between the interfering forward links (between the first and second beams) and the avoidance of interference between the interfering return links (between the first and third beams) can be performed independently of each other.

[0112] Figure 6 shows a block diagram 600 of a beam manager 605 that supports link-by-link mobile satellite beam conflict avoidance according to an embodiment disclosed herein. The beam manager 605 may be an embodiment of the beam manager 175 in 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 and beam conflict avoidance of mobile terminals via an antenna array 610.

[0113] 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 split between the ground network and the satellite network. In one embodiment (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.

[0114] 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 an antenna panel. 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.

[0115] 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 may be used to distribute signals to the signal processing components of the beam manager 605 (e.g., terminal tracking device 620, beam signal processor 650, beamformer 645). Bus 625 may include one or more wired interfaces. In addition, 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.

[0116] Memory 630 may include volatile memory (e.g., random access memory (RAM)) and / or non-volatile memory (e.g., read-only memory (ROM)). Other types of memory may also be possible. Memory 630 may store computer-readable and computer-executable code 635. When executed by processor 640, the code may include instructions that cause beam manager 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 the 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.

[0117] 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 (PLDs), 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 beam manager 605 to perform various functions (e.g., functions or tasks that support mobile satellite beam conflict avoidance). For example, the processor 640 and memory 630 may be configured to perform various functions described herein.

[0118] 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.

[0119] The terminal tracking device 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 the information for forming the beamformed spot beam, the terminal tracking device 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 the spatial information associated with the reference terminals. The terminal tracking device 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.

[0120] The terminal tracking device 620 may determine beamforming coefficients in each beamformed spot beam to separate signals transmitted through the beamformed spot beams from each other by enhancing the signals transmitted within the beamformed spot beam and canceling out interference from signals transmitted within other beamformed spot beams. The beamforming coefficients 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 spatial layers, and the value of N may be less than or equal to the value of M.

[0121] For the transmission of a beamformed spot beam through the antenna element 615, the terminal tracking device 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.

[0122] For receiving a beamformed spot beam via the antenna element 615, the terminal tracking device 620 may 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.

[0123] 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 tracking device 620 has determined the beamforming coefficient.

[0124] In some embodiments, the terminal tracking device 620, the beamformer 645, the 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 consist of a processor, a DSP, an ASIC, an FPGA or other PLD, discrete gate or transistor logic, discrete hardware components, or any combination thereof that constitutes means for performing the functions described herein, or otherwise support such means. 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).

[0125] Additionally or alternatively, the terminal tracking device 620, beamformer 645, beam signal processor 650, or various combinations or components thereof may be implemented in code 635 executed by processor 640 (for example, as communication management software or firmware). When implemented in code 635 executed by processor 640, the functions of the terminal tracking device 620, beamformer 645, beam signal processor 650, or various combinations or components 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 for performing the functions described herein, or otherwise supporting such means).

[0126] Figure 7 shows a block diagram 700 of a terminal tracking device 720 that supports link-by-link mobile satellite beam conflict avoidance according to an embodiment disclosed herein. The terminal tracking device 720 may be an embodiment of an embodiment of the terminal tracking device 620, as described with reference to Figure 6. The terminal tracking device 720, or various components thereof, may be embodiments of means for performing various embodiments of link-by-link mobile satellite beam conflict avoidance as described herein. For example, the terminal tracking device 720 may include a communications manager 725, a resource element manager 730, a beamforming manager 735, an interference detector 740, or any combination thereof. Each of these components may communicate with each other directly or indirectly (e.g., via one or more buses 715).

[0127] The communications manager 725 may be configured as a means for providing communications services to a plurality of mobile terminals via a set of beamformed spot beams, or may otherwise support such means. In some embodiments, the communications manager 725 may be configured as a means for providing communications services to a first mobile terminal and a second mobile terminal via a first beamformed spot beam and a second beamformed spot beam of a satellite communications system, as considered herein, or may otherwise support such means. The first and second mobile terminals may be assigned to the first and second beamformed spot beams, respectively. In some embodiments, the first and second beamformed spot beams may each include a forward link and a return link. In some embodiments, the communications manager 725 may comprise one or more of the other components of the terminal tracking device 720. In some embodiments, the communications manager 725 may include a resource element manager 730, a beamforming manager 735, and a beam coefficient determiner 740.

[0128] The resource element manager 730 may be configured as a means for assigning resource elements to the forward and return links of beamformed spot beams, or may support this means in a different way. In some embodiments, the resource element manager 730 may be configured, as considered herein, to assign the same first resource element to the forward links of first and second beamformed spot beams, and to assign second and third resource elements to the return links of first and second beamformed spot beams, respectively. The resource element manager 730 may also be configured as a means for assigning the same first resource element to the return links of first and second beamformed spot beams, and to assign second and third resource elements to the forward links of first and second beamformed spot beams, respectively, or may support this means in a different way. The second and third resource elements may be different from one another. The resource element manager 730 may be configured, or may support, a means for assigning a fourth resource element to the forward or return link of a second beamformed spot beam in place of the first resource element. The fourth resource element may differ from the first resource element. The assignment of the fourth resource element may be based on the interference metric between the forward links that were assigned to the first resource element, or between the return links that were assigned to the first resource element.

[0129] In some embodiments, the same first resource element is assigned to the forward links of the first and second beamformed spot beams, the second and third resource elements are assigned to the return links of the first and second beamformed spot beams, respectively, and the interference metric between the forward links of the first and second beamformed spot beams is determined to meet a threshold, at which point a fourth resource element is assigned to the forward link of the second beamformed spot beam.

[0130] In some embodiments, the same first resource element is assigned to the return links of the first and second beamformed spot beams, the second and third resource elements are assigned to the forward links of the first and second beamformed spot beams, respectively, and the interference metric between the return links of the first and second beamformed spot beams is determined to meet a threshold, at which point a fourth resource element is assigned to the return link of the second beamformed spot beam.

[0131] The beamforming manager 735 may also be configured, or otherwise supported, as discussed herein, as a means for adjusting the coverage area of ​​each beamformed spot beam in order to track the movement of a mobile terminal within the coverage area of ​​a satellite communications system.

[0132] The interference detector 740 may be configured as a means for determining whether the interference metric between forward links or return links meets a threshold, or may support this means in a different way. In some embodiments, the interference metric may be determined between forward links to which the same resource element has been assigned, or between return links to which the same resource element has been assigned. In some embodiments, the same resource element is assigned to the forward links so that the interference metric between the forward links meets a threshold. In some embodiments, the same resource element is assigned to the return links so that the interference metric between the return links meets a threshold.

[0133] In some embodiments, embodiments of one or more components of the terminal tracking device 720 or 620 may be found in other components of the terminal tracking device, or even outside the terminal tracking device. For example, the processor 640 and memory 630 of the beam manager 605 may be used to perform one or more functions related to the components of the terminal tracking device 720.

[0134] Figure 8 shows a flowchart illustrating Method 800, which supports link-by-link mobile satellite beam conflict avoidance, according to embodiments disclosed herein. The operation of Method 800 may be implemented by a satellite communications system or its components, as described herein. For example, the operation of Method 800 may be performed by a beam manager, as described with reference to Figures 1-7. In some embodiments, a set of instructions may be executed to control the functional elements of the beam manager to perform the functions described. Additionally or alternatively, the beam manager may perform aspects of the functions described using dedicated hardware.

[0135] In 805, the method may include providing communication services to a first mobile terminal and a second mobile terminal via a first beamformed spot beam and a second beamformed spot beam of a satellite communication system, the first and second mobile terminals being assigned to the first and second beamformed spot beams, respectively, and the first and second beamformed spot beams each including a forward link and a return link. The operation of 805 may be performed according to the embodiments 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, providing communication services may include the operations of 810, 815, 820, and 825.

[0136] In 810, the method may include assigning the same first resource element to the forward links of the first and second beamformed spot beams, and assigning the second and third resource elements to the return links of the first and second beamformed spot beams, respectively, or assigning the same first resource element to the return links of the first and second beamformed spot beams, and assigning the second and third resource elements to the forward links of the first and second beamformed spot beams, respectively, wherein the second resource element is different from the third resource element. The operation of 810 may be performed according to the embodiments disclosed herein. In some embodiments, the operation of 810 may be performed by a resource element manager 730, as described with reference to Figure 7.

[0137] In 815, the method may include adjusting the respective coverage areas of the first and second beamformed spot beams to track the movement of the first and second mobile terminals within the coverage area of ​​the satellite communication system. The operation of 820 may be performed according to the embodiments disclosed herein. In some embodiments, the operation of 820 may be performed by a beamforming manager 735, as described with reference to Figure 7.

[0138] In 820, the method may include determining whether the interference metric between forward links or return links to which the same first resource element was assigned meets a threshold, based on the adjustment of the respective coverage areas of the first and second beamformed spot beams. The operation of 825 may be performed according to the embodiments disclosed herein. In some embodiments, the operation of 825 may be performed by an interference detector 740, as described with reference to Figure 7.

[0139] In 825, the method may include assigning a fourth resource element to the forward or return link of a second beamformed spot beam instead of a first resource element, based on the determination that the interference metric meets a threshold, wherein the fourth resource element is different from the first resource element. The operation of 830 may be performed according to the embodiments disclosed herein. In some embodiments, the operation of 830 may be performed by a resource element manager 730, as described with reference to Figure 7.

[0140] 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.

[0141] These methods illustrate examples of embodiments, and it should be noted that the operations and steps may be reconfigured or otherwise modified to allow for other embodiments. In some embodiments, two or more aspects of the present method may be combined. For example, each aspect of the method may include steps or aspects of other methods, or other steps or techniques described herein.

[0142] The information and signals described herein may be represented using any of the various different techniques and methods. For example, data, instructions, commands, information, signals, bits, symbols, and chips which may be referenced throughout this description may be represented by voltage, current, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

[0143] The various illustrative 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, the processor may be any conventional processor, controller, microcontroller, or state machine. The processor may also be implemented as a combination of computing devices (e.g., a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors combined with a DSP core, or any other such configuration).

[0144] 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 examples 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 arranged in various locations, including being distributed so that parts of the functions are implemented in different physical locations.

[0145] 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 that can be accessed by 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 can be accessed by a general-purpose or dedicated computer or general-purpose or dedicated processor. Any connection is also appropriately referred to as computer-readable media. For example, when software is transmitted from a website, server, or other remote source using coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technology (e.g., infrared, radio, and microwave), coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technology (e.g., infrared, radio, and microwave) are included in the definition of a medium. Disk and disc, as used herein, include CDs, laserdiscs, optical discs, digital multipurpose discs (DVDs), floppy disks, and Blu-ray discs, where a disk typically reproduces data magnetically, and a disc optically reproduces data using a laser. Any combination of the above is also included within the scope of computer-readable media.

[0146] When used herein, “or” in the claims refers to a comprehensive list of items, such that when used in a list of items (e.g., a list of items preceded by phrases such as “at least one” or “one or more”), for example, a list of at least one of A, B, or C means A or B or C or AB or AC or BC or ABC (i.e., A and B and C). Also, when used herein, the phrase “based on” should not be construed as referring to a closed set of conditions. For example, a typical 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” should be construed in the same way as the phrase “at least partially based on.”

[0147] In the attached diagrams, 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 them from similar components after the reference label. Where only the first reference label is used herein, the description is applicable to any one of the similar components having the same first reference label, regardless of the second reference label or any other reference labels that follow it.

[0148] The descriptions provided 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 scope of the claims. The term “exemplary” as used herein means “serving as an example, illustration, or diagram,” and not “preferred” or “advantageous over other embodiments.” Detailed descriptions include specific details intended to provide an understanding of the described art. However, these arts may be implemented 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.

[0149] The descriptions herein are provided to enable those skilled in the art to construct or use the disclosure. Various modifications to the disclosure will be readily apparent 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. Accordingly, the disclosure is not limited to the examples and designs described herein, and should be given the broadest scope that is consistent with the principles and novel features disclosed herein.

Claims

1. It is a method, The provision of communication services to a first mobile terminal (120) and a second mobile terminal (120) via a first beamformed spot beam (150) and a second beamformed spot beam (150) of a satellite communication system (100), wherein the first and second mobile terminals (120) are each assigned to the first and second beamformed spot beams (150), and the first and second beamformed spot beams (150) each include a forward link and a return link, and the provision of the communication services is as follows: Assigning the same first resource element to the forward links of the first and second beamformed spot beams (150), and assigning a second resource element and a third resource element to the return links of the first and second beamformed spot beams (150), respectively; or assigning the same first resource element to the return links of the first and second beamformed spot beams (150), and assigning the second resource element and the third resource element to the forward links of the first and second beamformed spot beams (150), respectively, wherein the second resource element is different from the third resource element. To track the movement of the first and second mobile terminals (120) within the coverage area (155) of the satellite communication system (100), the respective coverage areas (160) of the first and second beamformed spot beams (150) are adjusted, Based on the adjustment of the respective coverage areas (160) of the first and second beamformed spot beams (150), it is determined that the interference metric between the forward links to which the same first resource element was assigned, or between the return links to which the same first resource element was assigned, satisfies a threshold. A method comprising assigning a fourth resource element to the forward link or the return link of the second beamformed spot beam (150) instead of the first resource element, based on the determination that the interference metric satisfies the threshold, wherein the fourth resource element is different from the first resource element.

2. The method according to claim 1, wherein the allocation of the second and third resource elements is performed independently of the allocation of the same first resource element.

3. Providing the aforementioned communication service is The method according to claim 1 or 2, further comprising maintaining the assignment of the second and third resource elements to the forward link of the first and second beamformed spot beams (150) or to the return link of the first and second beamformed spot beams (150) during the assignment of the fourth resource element to the forward link or the return link of the second beamformed spot beam (150).

4. The same first resource element is assigned to the forward link of the first and second beamformed spot beams (150), and the second and third resource elements are assigned to the return links of the first and second beamformed spot beams (150), respectively. The interference metric is determined to satisfy the threshold between the forward links of the first and second beamformed spot beams (150). The method according to any one of claims 1 to 3, wherein the fourth resource element is assigned to the forward link of the second beamformed spot beam (150).

5. The same first resource element is assigned to the return link of the first and second beamformed spot beams (150), and the second and third resource elements are assigned to the forward links of the first and second beamformed spot beams (150), respectively. The interference metric is determined to satisfy the threshold between the return links of the first and second beamformed spot beams (150). The method according to any one of claims 1 to 3, wherein the fourth resource element is assigned to the return link of the second beamformed spot beam (150).

6. The aforementioned interference metric is, The measured interference between the forward link of the first and second beamformed spot beams (150), or the return link of the first and second beamformed spot beams (150), Estimated interference between the forward link of the first and second beamformed spot beams (150), or between the return link of the first and second beamformed spot beams (150), The correlation between channels of the first and second mobile terminals (120), or The method according to any one of claims 1 to 5, based on one or more of the distances between the first mobile terminal (120) and the second mobile terminal (120).

7. The method according to any one of claims 1 to 6, wherein the threshold is based on the beam width of the first and second beamformed spot beams (150).

8. Assigning the fourth resource element to the forward link or return link of the second beamformed spot beam (150) is: The method according to any one of claims 1 to 7, comprising changing at least one of the following: a frequency resource associated with the forward link or the return link of the second beamformed spot beam (150); a time slot associated with the forward link or the return link of the second beamformed spot beam (150); a polarization associated with the forward link or the return link of the second beamformed spot beam (150); or one or more codes associated with the forward link or the return link of the second beamformed spot beam (150).

9. The method according to any one of claims 1 to 8, wherein the respective coverage areas (160) of the first and second beamformed spot beams (150) are adjusted based on measured values ​​of signals communicated with the first and second mobile terminals (120).

10. The method according to any one of claims 1 to 9, wherein each of the first, second, and third resource elements includes a frequency resource and a time slot.

11. The method according to any one of claims 1 to 10, wherein each of the first, second, and third resource elements includes polarization.

12. It is a system for satellite communications, One or more satellites (105), The system comprises a beam manager (175), and the beam manager is The system is configured to provide communication services to a first mobile terminal (120) and a second mobile terminal (120) via a first beamformed spot beam (150) and a second beamformed spot beam (150) of one or more satellites, the first and second mobile terminals (120) being assigned to the first and second beamformed spot beams (150), the first and second beamformed spot beams (150) each including a forward link and a return link, and in order to provide the communication services, the beam manager (175) Assigning the same first resource element to the forward links of the first and second beamformed spot beams (150) and assigning the second resource element and the third resource element to the return links of the first and second beamformed spot beams (150), respectively, or assigning the same first resource element to the return links of the first and second beamformed spot beams (150) and assigning the second resource element and the third resource element to the forward links of the first and second beamformed spot beams (150), respectively, wherein the second resource element is different from the third resource element. To track the movement of the first and second mobile terminals (120) within the coverage area (155) of the satellite communication system (100), the respective coverage areas (160) of the first and second beamformed spot beams (150) are adjusted. Based on the adjustment of the respective coverage areas (160) of the first and second beamformed spot beams (150), it is determined that the interference metric between the forward link to which the same first resource element was assigned, or between the return link to which the same first resource element was assigned, satisfies a threshold, and The system is configured to, based on the determination that the interference metric satisfies the threshold, assign a fourth resource element to the forward link or the return link of the second beamformed spot beam (150) instead of the first resource element, wherein the fourth resource element is different from the first resource element.

13. The system according to claim 12, further comprising a ground station configured to communicate with one or more satellites via one or more satellite beams.

14. The system according to claim 13, wherein the ground station includes a network device or gateway.

15. The beam manager (175) is The system according to any one of claims 12 to 14, configured to allocate the second and third resource elements independently of allocating the same first resource element.

16. In order to provide the aforementioned communication service, the beam manager (175) The system according to any one of claims 12 to 15, further configured to maintain the assignment of the second and third resource elements to the forward link of the first and second beamformed spot beams (150) or to the return link of the first and second beamformed spot beams (150) during the assignment of the fourth resource element to the forward link or the return link of the second beamformed spot beam (150).

17. The same first resource element is assigned to the forward link of the first and second beamformed spot beams (150), and the second and third resource elements are assigned to the return links of the first and first and second beamformed spot beams (150), respectively. The interference metric is determined to satisfy the threshold between the forward links of the first and second beamformed spot beams (150). The system according to any one of claims 12 to 16, wherein the fourth resource element is assigned to the forward link of the second beamformed spot beam (150).

18. The same first resource element is assigned to the return link of the first and second beamformed spot beams (150), and the second and third resource elements are assigned to the forward links of the first and second beamformed spot beams (150), respectively. The interference metric is determined to satisfy the threshold between the return links of the first and second beamformed spot beams (150). The system according to any one of claims 12 to 16, wherein the fourth resource element is assigned to the return link of the second beamformed spot beam (150).

19. The aforementioned interference metric is, The measured interference between the forward link of the first and second beamformed spot beams (150), or the return link of the first and second beamformed spot beams (150), Estimated interference between the forward link of the first and second beamformed spot beams (150), or between the return link of the first and second beamformed spot beams (150), The correlation between channels of the first and second mobile terminals (120), or The system according to any one of claims 12 to 18, based on one or more of the distance between the first mobile terminal (120) and the second mobile terminal (120).

20. The system according to any one of claims 12 to 19, wherein the threshold is based on the beam width of the first and second beamformed spot beams (150).

21. To assign the fourth resource element to the forward link or return link of the second beamformed spot beam (150), the beam manager (175) The system according to any one of claims 12 to 20, further configured to modify at least one of the following: frequency resources associated with the forward link or return link of the second beamformed spot beam (150); time slots associated with the forward link or return link of the second beamformed spot beam (150); polarization associated with the forward link or return link of the second beamformed spot beam (150); or one or more codes associated with the forward link or return link of the second beamformed spot beam (150).

22. The system according to any one of claims 12 to 21, wherein the respective coverage areas (160) of the first and second beamformed spot beams (150) are adjusted based on measured values ​​of signals communicated with the first and second mobile terminals (120).

23. The system according to any one of claims 12 to 22, wherein each of the first, second, and third resource elements includes a frequency resource and a time slot.

24. The system according to any one of claims 12 to 23, wherein each of the first, second, and third resource elements includes polarization.

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