EP4646801A1

EP4646801A1 - Mobile satellite beam capacity compensation

Info

Publication number: EP4646801A1
Application number: EP23706148.6A
Authority: EP
Inventors: Nicholas G. BERNDSEN; James E. Petranovich; Brian T. Sleight; Michail K. Tsatsanis; Anton Hoffman
Original assignee: Viasat Inc
Current assignee: Viasat Inc
Priority date: 2023-01-17
Filing date: 2023-01-17
Publication date: 2025-11-12
Also published as: IL322095A; KR20250134672A; AU2023424461A1; WO2024155271A1; CN120937272A

Abstract

The described techniques relate to improved methods, systems, devices, and apparatuses that support mobile satellite beam capacity compensation. A communication service may be provided to mobile terminals via respective beamformed spot beams that track movement of the mobile terminals. A beam manager may perform resource element allocation of the beams. The beam manager may compensate for link impairments associated with the resource elements associated with the beams by changing one or more characteristics associated with the resource elements. The beam manager may determine the presence of link impairments associated with the resource elements and allocate more power for the associated beams and/or assign the beams to additional resource elements based thereon. The beam manager may determine the presence or absence of link impairments and compensate for them during repeating time periods.

Description

MOBILE SATELLITE BEAM CAPACITY COMPENSATION

HELD OF TECHNOLOGY

[0001] The following relates generally to communications, including mobile satellite beam capacity compensation.

BACKGROUND

[0002] Communications devices may communicate with one another using wired connections, wireless (e.g., radio frequency (RF)) connections, or both. Wireless communications between devices may be performed using a wireless spectrum that has been designated for a service provider, wireless technology, or both. In some examples, the amount of information that can be communicated via a wireless communications network is based on an amount of wireless spectrum designated to the service provider, and an amount of frequency reuse within the region in which service is provided. Satellite communications may use beamforming to establish beams to increase frequency reuse. However, providing a high level of frequency reuse in satellite communication systems employing beamforming presents challenges.

SUMMARY

[0003] The described techniques relate to improved methods, systems, devices, and apparatuses that support mobile satellite beam capacity compensation. For example, a communication service may be provided to mobile terminals via respective beamformed spot beams that track movement of the mobile terminals. A beam manager may perform resource element allocation of the beams. The beam manager may compensate for link impairments associated with resource elements associated with the mobile terminals by changing one or more characteristics associated with the resource elements. The beam manager may determine the presence of link impairments associated with the resource elements and allocate more power for the associated beams and/or assign the beams to additional resource elements based thereon. The beam manager may determine the presence or absence of link impairments and compensate for them during repeating time periods.

BRIEF DESCRIPTION OF THE DRAWINGS

[0004] FIG. 1 shows an example of a satellite communication system that supports mobile satellite beam capacity compensation in accordance with examples described herein. [0005] FIGs. 2A and 2B show examples of resources and resource elements for a satellite communication system that support mobile satellite beam capacity compensation in accordance with examples described herein.

[0006] FIG. 3 illustrates an example of a satellite communication system that supports mobile satellite beam capacity compensation in accordance with examples as disclosed herein.

[0007] FIGs. 4A and 4B various examples showing possible link impairments and mitigation strategies that support mobile satellite beam capacity compensation in accordance with examples as disclosed herein.

[0008] FIGs. 5A and 5B illustrate timing diagrams of example mitigation strategies that support mobile satellite beam capacity compensation in accordance with examples as disclosed herein.

[0009] FIG. 6 shows a block diagram of a beam manager that supports mobile satellite beam capacity compensation in accordance with examples as disclosed herein.

[0010] FIG. 7 shows a block diagram of a beam compensation manager that supports mobile satellite beam capacity compensation in accordance with examples as disclosed herein.

[0011] FIGs. 8 and 9 show flowcharts illustrating methods that support mobile satellite beam capacity compensation in accordance with examples as disclosed herein.

DETAILED DESCRIPTION

[0012] Link impairments associated with mobile terminals occur regularly and can be a source of performance degradation and disruption to end-users due to lost or delayed packets or changes in beam congestion levels or capabilities. In some satellite communication systems, a lower coding rate is instituted when a link impairment occurs. This provides more redundancy, which may reduce the number of disruptions that may otherwise occur.

However, the redundancy reduces the overall communication speed of the terminal, which results in user performance degradation and inefficiency.

[0013] Techniques are described for compensating for link impairments — with less or no performance degradation — associated with resource elements associated with beamformed spot beams to which moving mobile terminals are assigned. The techniques may allow communication service to be provided to mobile terminals via respective beamformed spot beams that track movement of the mobile terminals. The beam manager may compensate for the link impairments. In some cases, the beam manager may change one or more characteristics associated with the resource elements associated with the spot beams to compensate for a link impairment. In some cases, an additional resource element may be associated with a beam to compensate for a link impairment associated with a mobile terminal assigned to the beam. In some cases, the beam may be allocated additional power to compensate for the link impairment. In some cases, the mobile terminal may be switched to a different coverage region having more capability to compensate for the link impairment. Using additional resource elements or additional power or switching to a different coverage region may increase the capability of the beam. This may allow the beam to handle the link impairment while providing at least a same level of capability (e.g., communication speed) for the user as the beam did before the link impairment, thereby lessening or preventing performance degradation during the link impairment.

[0014] In some cases, resource element allocation and/or power allocation may be performed by determining when a link impairment associated with a mobile terminal is present, determining to increase a power and/or a number of resource elements to associate with the beam associated with the mobile terminal, and allocating more power for the beam and/or assigning the spot beam to an additional resource element based thereon. In some cases, the presence or absence of a link impairment may be determined during repeating time periods.

[0015] The discussion herein generally refers to link impairments as being “associated with” resource elements. The link impairments may alternatively be considered to be “associated with” the beamformed spot beams to which the resource elements are associated, or the mobile terminals assigned to the beamformed spot beams. Thus, when a link impairment is referred to herein as being associated with a resource element, the link impairment may also be considered to be associated with the beamformed spot beam and/or the mobile terminal associated with the resource element. Similarly, the resource element, the beamformed spot beam, and the mobile terminal may be considered to be associated with the link impairment.

[0016] The discussion herein may refer to resource elements being assigned to beamformed spot beams or the beamformed spot beams being assigned to the resource elements. As used herein, these phrases may be considered to be interchangeable. That is, a resource element being assigned to a beamformed spot beam may be considered to be the same as the beamformed spot beam being assigned to the resource element. Similarly, assigning a resource element to a beamformed spot beam may be used interchangeably with assigning the beamformed spot beam to the resource element.

[0017] Aspects of the disclosure are initially described in the context of satellite communication systems. Aspects of the disclosure are further illustrated by and described with reference to apparatus diagrams, system diagrams, block diagrams, and flowcharts that relate to mobile satellite beam capacity compensation.

[0018] FIG. 1 shows an example of a satellite communication system 100 that supports mobile satellite beam capacity compensation in accordance with examples described herein. Satellite communication system 100 may include a ground network 135 and a satellite network 101 configured to track and provide communication service to one or more mobile terminals 120.

[0019] 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 a feeder link 132 (e.g., one or more satellite beams). The access nodes 140 may be coupled with access node transceivers 145 that are configured to process signals received from and to be transmitted through corresponding access node(s) 140. The access node transceivers 145 may also be configured to interface with a network 125 (e.g., the Internet) — e.g., via a network device 130 (e.g., a network operations center, satellite and gateway terminal command centers, or other central processing centers or devices) that may provide an interface for communicating with the network 125.

[0020] The ground network may also include a beam manager 175 for controlling the tracking of mobile terminals as communication service is provided to the mobile terminals via beamformed spot beams, coordinating resource elements used by the beams, and compensating for link impairments of the mobile terminals, as discussed herein. Beam manager 175 may retrieve information (e.g., associated with the satellite network 101 and the terminals 120) from the satellite network 101 (e.g., via feeder link 132 and an access node 140) for performing the controlling, coordinating, and compensating, and may send commands (e.g., to the satellite network 101 and/or the terminals 120) accordingly (e.g., via the access node and feeder link). [0021] In some examples, beam manager 175 may be a single device. Alternatively, beam manager 175 may be distributed throughout the system, e.g., in two or more elements of the satellite network and/or the ground network. For example, beam manager 175 may be incorporated into one or more devices of the ground network (e.g., a network device 130 or an access node transceiver 145), or one or more devices of the satellite network (e.g., in a single satellite 105 or distributed among multiple satellites), or a combination of devices in the ground network and the satellite network. In some examples, a first portion of beam manager 175 may be located in ground network 135 and a second portion may be located in satellite network 101.

[0022] In some examples, beam manager 175 may determine when a link impairment associated with a mobile terminal is present, determine to increase a power and/or a number of resource elements to associate with the beam associated with the mobile terminal to compensate for the link impairment, and then increase the power and/or number of resource elements associated with the beam. In some examples, the beam manager may determine when a link impairment is present by determining the presence or absence of a link impairment during repeating time periods.

[0023] Terminals 120 may include various devices configured to communicate signals with the satellite network 101. Although terminals 120 are illustrated as being on aircraft, terminals 120 may include fixed terminals (e.g., ground-based stationary terminals) or mobile terminals mounted on mobile platforms (e.g., boats, aircraft, ground-based vehicles, and the like), or a combination of fixed and mobile terminals. A terminal 120 may communicate data and information with an access node 140 via the satellite network 101. The data and information may be communicated with a destination device such as a network device 130, or some other device or distributed server associated with a network 125.

[0024] A variety of physical layer transmission modulation and coding techniques may be used by access nodes 140, and terminals 120, and components of the satellite network 101 (e.g., satellites) for the communication of signals.

[0025] The satellite network 101 may include one or more satellites 105 (e.g., a single satellite 105 or a network of satellites) that are deployed in space orbits (e.g., low earth orbits, medium earth orbits, geosynchronous orbits, geostationary orbits, etc.). Each satellite 105 included in satellite network 101 may be equipped with one or more antennas (e.g., a single antenna or an antenna array). In some examples, the one or more satellites 105 equipped with multiple antennas may each include one or more antenna panels that include an array of evenly distributed antennas (which may also be referred to as antenna elements). In some examples, a satellite may be equipped with an antenna array including antennas that are unevenly distributed across a large region. The ground network 135 may also contain access nodes 140 with multiple antenna array elements.

[0026] Terminals 120 may include an antenna assembly which may also include various hardware for mounting an antenna. An antenna assembly may also include circuits and/or processors for converting (e.g., performing frequency conversion, modulating/demodulating, multiplexing/demultiplexing, filtering, forwarding, etc.) between radio frequency (RF) satellite communication signals, and satellite terminal communications signals transmitted between the antenna and a satellite terminal receiver. For mobile terminals, the antenna assembly may be mounted on the outside of the mobile platform (e.g., outside of the fuselage of an aircraft). Additionally, or alternatively, the terminal 120 may include a transceiver, which may be mounted on the inside or outside of the mobile platform and may include circuits and/or processors for performing various RF signal operations (e.g., receiving, performing frequency conversion, modulating/demodulating, multiplexing/demultiplexing, etc.).

[0027] The satellite network 101 may have a large aperture size, which may be spanned by the antenna arrays or multiple satellites of the satellite network 101. Beam manager 175 may use the one or more satellites to support beamforming techniques within the coverage area 155 of the satellite communication system to increase a utilization of resources used for communications. Beam manager 175 may employ beamforming, including using multipleinput multiple-output (MIMO) techniques, to exploit multipath signal propagation and increase spectral efficiency by transmitting or receiving multiple signals via different spatial layers over the same frequency resources. Beam manager 175 may cause multiple signals, for example, to be transmitted by a transmitting device (e.g., a satellite 105) via a set of antennas in accordance with a set of weighting coefficients. Likewise, the multiple signals may be received by a receiving device (e.g., a satellite terminal 120) via a set of antennas in accordance with 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). [0028] In some examples, some or all of the antenna elements on the satellites 105, the ground network 135, and/or the terminals 120 may be arranged as an array of constituent receive and/or transmit feed elements that cooperate to enable various examples of on-board beamforming (OBBF), ground-based beamforming (GBBF), end-to-end beamforming, or other types of beamforming. In the GBBF implementation, there may be multiple transmit or receive antennas on the ground network access node(s).

[0029] Beam manager 175 may determine weighting coefficients to apply to the set of antennas. For example, for N spatial layers to be formed, beam manager 175 may utilize an (M N) MIMO matrix, where M may represent the quantity of antennas of the set of antennas. In some examples, M may be equal to N. Beam manager 175 may determine the MIMO matrix based on a channel matrix and may use the MIMO matrix to isolate the different spatial layers of the channel. In some examples, beam manager 175 may select the weighting coefficients to emphasize signals transmitted using the different spatial layers while reducing interference of signals transmitted in the other spatial layers. Accordingly, processing signals received at each antenna of the set of antennas (e.g., a signal received at the set of antennas) using the MIMO matrix may result in multiple signals being output, where each of the multiple signals may correspond to one of the spatial layers. In some examples, the weighting coefficients used for MIMO communications may be referred to as beam coefficients or beamforming coefficients, and the multiple spatial layers may be referred to as beams or spot beams.

[0030] Beam manager 175 may determine the elements of the MIMO matrix used to form the spatial layers of the channel based on channel sounding probes. Channel sounding probes may include reference signals transmitted periodically between satellite network 101 and a device (e.g., a terminal 120) coupled with the satellite network. For example, a channel sounding probe may be periodically transmitted from a terminal 120 to a satellite 105, or from the satellite to the terminal, or both, and may include a sequence that is 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., the terminal or the satellite) may use the received channel sounding probe to evaluate the connection by correlating the received channel sounding probe to the expected signal for the channel sounding probe (e.g., to determine a signal strength, an interference, etc.) and make decisions based thereon. Due to the periodicity of the signal, the receiving device may know when the signal should be received. [0031] Beam manager 175 may use beamforming techniques to shape or steer a communication beam along a spatial path between one or more satellites and a mobile terminal 120 within a geographic area. Beam manager 175 may cause a communication beam to be formed by determining weighting coefficients for antenna elements of an antenna array that result in the signals transmitted from or received at the antenna elements being combined such that signals propagating in a particular orientation with respect to an antenna array experience constructive interference while others experience destructive interference. Thus, beamforming may be used to transmit signals having energy that is focused in a direction of a communication beam and to receive signals that arrive in a direction of the communication with increased signal power (relative to the absence of beamforming). Beam manager 175 may use the weighting coefficients to apply amplitude offsets, phase offsets, or both to signals carried via the antennas.

[0032] In some examples, beam manager 175 may apply the weighting coefficients to the antennas to form multiple beams, each associated with a different direction, where the multiple beams may be used to communicate multiple signals having the same frequency at the same time to different user terminals. This may be referred to as Multiuser 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 beams may be referred to herein as beamformed spot beams, spot beams, or beams.

[0033] Beam manager 175 may calculate the amplitude and phase of each weighting coefficient given the antenna array and reflector geometry and location and the desired beam locations. However, due to inaccuracies (e.g., in the satellite locations, array orientation, geometry, atmospheric scintillation effects, etc.), such an approach may be impractical. Instead, beam manager 175 may calculate the weighting coefficients using continuous or periodic measurements of the MIMO propagation channel characteristics (e.g., pairwise channels from each system antenna element to each terminal antenna element) and adjusting the weighting coefficients based on the changing channel characteristics. The measured MIMO channel characteristics may include pairwise gain and phase response and noise level and may be referred to as MIMO channel state information (CSI). Once the MIMO CSI is available, beam manager 175 may derive the weighting coefficients by solving a set of equations or applying a set of adaptation formulas. Various beamformer calculation and adaptation techniques may be used, including minimum mean square (MMSE) beamformer, zero forcing beamformer, MIMO sphere decoder, and others. [0034] The measurement of MIMO CSI may include the collaboration of at least one terminal for each beam. The situation may be different for the forward link direction (from the satellites to the terminals) versus the return link direction (from the terminals to the satellites). In the return link, each terminal may transmit a channel probing signal that may be orthogonal to probing signals of the other terminals. The satellites may determine which channel probing signal is transmitted from each terminal and may process the signal to estimate the channel parameters of the channel corresponding to that terminal. As such, the MIMO CSI on the return link may be computed locally on the satellite side for terminals that transmit channel probing signals. In contrast, on the forward link, the satellites may transmit channel probing signals. Different antenna elements may transmit signals that are orthogonal to each other. Each terminal tasked to compute MIMO CSI may do so by processing the probing signal corresponding to each transmit antenna element. Further, each such terminal may transmit the MIMO CSI back to a satellite using a return link control channel.

[0035] The spot beams generated that way may be tailored to the MIMO CSI provided by the user terminals and each beam may illuminate the direction of each such terminal. Each beam has a finite coverage area 160 (e.g., several km diameter) and may therefore illuminate additional terminals that may be in the vicinity of the CSI generating terminal. These additional terminals may not provide CSI, as this may unnecessarily increase the CSI reporting channel overhead. The terminal that is used to provide MIMO CSI per beam may be considered the reference terminal for that beam. A reference terminal may be a mobile terminal. In some examples, the coverage area 160 of a beam may be determined based on the wavelength of the carrier wave and the diameter of the aperture. The coverage area 160 may correspond, e.g., to a footprint where the power level of the beam is above a threshold, or where the power level drop-off away from the center of the beam is less than a threshold amount (e.g., 3 decibels (dB) or 6 dB). In some examples, the coverage area 160 may be based on a beam width of the beam.

[0036] In some examples, one or more aircraft-based terminals 120 may be sufficiently separated in distance from each other and from the other aircraft, so that beam manager 175 may use a separate beam for each of the one or more terminals. In some examples, two or more of the terminals 120 may be in close proximity (e.g., at an airport) such that beam manager 175 may illuminate the terminals by a same beam. In the former case, each terminal on an aircraft may be a reference terminal for its beam, while in the latter case, one of several terminals on aircraft may serve as a reference terminal for the beam. [0037] As the mobile terminal 120 moves in the airspace, the MIMO CSI may change, causing the direction of the beam to change. Beam manager 175 may adjust the beam direction based on the changed MIMO CSI so that the reference terminal may remain at or near the center of the beam. Therefore, as the reference terminal moves, the beam may follow its movement, as further explained herein.

[0038] Beam manager 175 may associate the beamformed spot beams with a set of resources of the satellite communication system 100. The set of resources may include, e.g., frequency resources, time resources, and polarization resources. For example, a given frequency range for the satellite communication system 100 may comprise frequency resources or channels, and a given amount of time may comprise different recurring time slots. For example, beam manager 175 may use a frequency channel to carry a signal (e.g., a modulated signal carried in a beamformed spot beam) on one of the recurring time slots. By doing this, beamformed spot beams may overlap spatially without interfering if they are associated with different frequency/time resource combinations. In addition, beam manager 175 may use multiple polarizations such that two beamformed spot beams may overlap spatially without interfering if they are associated with different polarizations.

[0039] Thus, beamformed spot beams may overlap spatially without interfering if they are associated with different combinations of the resources (e.g., different frequency channel/time slot/polarization combinations). The different combinations may be known as resource elements that together form a set of resource elements that may be used by beam manager 175 for communicating signals over a beam. Beam manager 175 may control the association of the beams with the resource elements and determine when to assign the beams to one or more of the resource elements, as discussed herein. Beam manager 175 may also control the amount of power to allocate for each beam and when to adjust the power for each beam, as discussed herein.

[0040] Beam manager 175 may adjust the individual coverage areas or footprints of the beamformed spot beams (e.g., by adjusting the weighting coefficients) so as to track (e.g., move in concert with) the respective mobile terminals. As discussed herein, as the beamformed spot beams track the mobile terminals, beam manager 175 may compensate for link impairments by changing one or more characteristics associated with resource elements associated with the spot beams. For example, when a link impairment associated with a mobile terminal arises, beam manager 175 may assign the spot beam associated with the mobile terminal to an additional resource element or allocate more power for the spot beam. Alternatively, beam manager 175 may switch the mobile terminal to a different coverage region. Changing the one or more characteristics may increase the capabilities of the beam, allowing the beam to handle the link impairment while providing at least a same level of capability (e.g., communication speed) for the user as the beam did before the link impairment. This may compensate for (e.g., reduce or prevent) performance degradation and communication disruptions that can result during link impairments and allow communication service associated with the mobile terminal to continue at a high level despite the link impairment as the mobile terminal moves through the coverage area of the satellite communication system.

[0041] FIG. 2A shows an example of resources 200 for a satellite communication system that support mobile satellite beam capacity compensation in accordance with examples described herein. Resources 200 may correspond to frequency divisions of a satellite communication system. For example, a frequency range 205 (e.g., a frequency band) may comprise 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 the terminals. The resources 200 may correspond to the frequency channels 210 of the frequency range 205.

[0042] Each frequency channel 210 may carry signals associated with a single terminal (e.g., at a time). For example, each frequency channel 210 may carry a single modulated signal. Information (e.g., data, control information) may be modulated onto the modulated signal using a variety of single-carrier or multi-carrier modulation techniques (e.g., Orthogonal Frequency Division Multiplexing (OFDM), Direct Sequence Spread Spectrum (DSSS), linearly pre-coded OFDM (EP-OFDM)). A beamformed spot beam may be associated with one or more frequency channels 210 (e.g., by beam manager 175), to provide communication to and track mobile terminals as discussed herein.

[0043] In the example of FIG. 2A, the resources 200 may correspond to the frequency channels 210. That is, each frequency channel 210 may be a separate resource 200. As there are no other types of resources, the separate resources may also be resource elements in some examples. As such, in this example the number of available resource elements may correspond to the number of frequency channels, N. [0044] FIG. 2B shows an example of resource elements 250 for a satellite communication system that support mobile satellite beam capacity compensation in accordance with examples described herein. In this example, frequency channels 210 may again be used to carry signals associated with the terminals. In addition, the frequency channels 210 may be time multiplexed. That is, each frequency channel 210 may be configured to carry signals to the terminals in time slots that repeat after a period of time. For example, a time period 215 may be divided into a set of sub-periods or time slots t (e.g., time slot ti, time slot t2, time slot t3, time slot t_m) each having a length 225. Each frequency channel 210 may carry a signal to a different terminal during each time slot t, although in some cases multiple time slots within a time period 215 may be allocated 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 onto the modulated signal using a variety of single-carrier or multi-carrier modulation techniques (e.g., OFDM, DSSS, EP-OFDM) to provide communication to and track mobile terminals (e.g., by beam manager 175), as discussed herein.

[0045] At the completion of the time period 215, the process may repeat such that each frequency channel 210 may carry further signals associated with the different terminals in a resource period. As a result, beam manager 175 may use the frequency channel 210 for communication with the terminal during one time slot t per time period 215. In some examples, beam manager 175 may assign a terminal to more than one time slot per time period, and thus communication with a terminal may occur over more than one time slot per time period for the frequency channel 210.

[0046] In the example of FIG. 2B, the resource elements 250 may correspond to the combinations of frequency channels 210 and time slots t in a time period 215. That is, each unique combination of frequency channel 210 and time slot t may be a separate resource element 250. As such, in this example the number of available resource elements may correspond to the number of frequency channels times the number of time slots, or N x m. Thus, this example may provide more resource elements than the example of FIG. 2A.

[0047] In addition to being multiplexed in time or frequency, different polarizations may be used to define the resource elements for assignment to beamformed spot beams. For example, a set of resource elements may include a first sub-set of resource elements associated with a first polarization and a second sub-set of resource elements associated with a second, orthogonal, polarization. The first and second polarizations may be orthogonal polarizations, and may be linearly polarized or circularly polarized (e.g., a right-hand circular polarization (RHCP), a left-hand circular polarization (LHCP)). Thus, a set of resource elements available to beam manager 175 for assignment to beamformed spot beams may be defined according to frequency resources (e.g., frequency channels), time resources (e.g., sub-periods of resource periods), or polarization resources.

[0048] In some examples, the types of resource elements may be combined. For example, in the same system, one or more frequency channels may be divided into time slots (e.g., as in FIG. 2B) and one or more other frequency channels may be used, undivided (e.g., as in FIG. 2A), as separate resource elements. Other combinations are also possible.

[0049] FIG. 3 illustrates an example of a satellite communication system 300 that supports mobile satellite beam capacity compensation in accordance with examples as disclosed herein. The satellite communication system 300 may be an example of satellite communication system 100 as described with reference to FIG. 1 or aspects thereof. Satellite communication system 300 may include a satellite network 101 having one or more satellites 105 configured to generate beamformed spot beams 150 (e.g., beam 150-a) for communicating with a set of terminals 120 (e.g., terminals 120-a, 120-b, 120-c, 120-d) within a coverage area 155 of the satellite communication system, as directed by a beam manager 175. Beamformed spot beams may be referred to herein as spot beams or beams.

[0050] The terminals 120 may be located on movable platforms or vehicles, such as automobiles, boats, or aircraft, and thus may be considered to be mobile terminals 120. In some examples, each vehicle may include a single mobile terminal. In other examples, one or more vehicles may each include two or more mobile terminals. At least some of mobile terminals 120 may be multi-user mobile terminals, and thus the satellite communication system 300 may provide a communication service to multiple user devices (e.g., smartphones, laptops, tablets) connected via the mobile terminals 120.

[0051] In some examples, the satellite communication system 300 may provide communication service to the mobile terminals 120 via a set of movable beamformed spot beams 150 that track the mobile terminals, as controlled by beam manager 175, during movement of the mobile terminals. For the sake of clarity, only a single movable beamformed spot beam 150-a is illustrated in FIG.3 associated with a single mobile terminal 120-a. Although not illustrated in FIG. 3, movable beamformed spot beams 150 may also be associated with one or more of the other mobile terminals 120.

[0052] In some examples, 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 also be considered to be a reference terminal. Each spot beam 150 may have a respective coverage area 160 (e.g., coverage areas 160-a, 160-b, 160-c, 160-d). The coverage area may correspond, for example, to a footprint where the power level of the beam is above a threshold, or where the power level drop-off away from the center of the beam is less than a threshold amount (e.g., 3dB or 6dB).

[0053] In some examples, a beamformed spot beam associated with a reference terminal may be formed (e.g., as controlled by beam manager 175) to include the terminal’s physical location within the coverage area of the beamformed spot beam. For example, as shown in FIG. 3, mobile terminal 120-a, acting as a reference terminal, may be physically located within the coverage area 160-a of 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 service (e.g., via beam manager 175) to mobile terminal 120-a via beamformed spot beam 150-a.

[0054] In some examples, beam manager 175 may cause a beamformed spot beam to track a moving mobile terminal while communication service is provided to the terminal via the beam. For example, as mobile terminal 120-a physically moves from location A to location B, as indicated by arrow 325, beamformed spot beam 150-a may “move” so as to track the mobile terminal, as indicated by arrow 330. In some examples, to “move” a beamformed spot beam, beam manager 175 may change and apply the beamforming coefficients associated with the beamformed spot beam to the signal associated with the beamformed spot beam. This may change the directionality of the beamformed spot beam (e.g., “move” the beam) so that the coverage area of the beamformed spot beam changes (e.g., “moves”).

[0055] To follow or track a mobile terminal, the beamforming coefficients may be changed by beam manager 175 such that the coverage area of the beamformed spot beam may move to reflect the movement of (e.g., may be moved in concert with) the mobile terminal. Beam manager 175 may continually adjust the coverage area (e.g., by periodically changing the beamforming coefficients to provide continuous coverage) to continue to correspond with the moving physical location of the moving mobile terminal and thereby track the mobile terminal. For example, beam manager 175 may move the coverage area 160-a of beamformed spot beam 150-a (e.g., from coverage area 160-al to coverage area 160-a2) so as to encompass the physical location of mobile terminal 120-a as mobile terminal 120-a moves from location A to location B. This may allow communication service associated with the 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. For example, beam manager 175 may provide continuous communication service to mobile terminal 120-a via beamformed spot beam 150-a without a handoff as the mobile terminal moves between location A and location B.

[0056] In some examples, beam manager 175 may refrain from changing the beamforming coefficients associated with a mobile terminal while the mobile terminal is stationary because the coverage area of the beamformed spot beam may already correspond with the physical location of the stationary terminal. In other examples, beam manager 175 may change the beamforming coefficients even when a mobile terminal is stationary. For example, in some systems there may be a set of beamforming coefficients that may generate all of the beams from all of the beam signals. In those cases, even if only one terminal moves, beam manager 175 may change the beamforming coefficients used for all terminals.

[0057] In some examples, to track the mobile terminal, beam manager 175 may adjust the coverage area of the spot beam (e.g., move the spot beam) based on measurements of signals communicated with the mobile terminal. In some examples, the terminal may provide channel state information back to the satellite network on a regular and periodic basis, and beam manager 175 may process this channel state information to compute appropriate beamforming coefficients such that the beam energy for the beam signal associated with an aircraft is focused on that aircraft. As the aircraft moves, the channel state information may change, which in turn may induce changes in the beam weight coefficients computed by beam manager 175. Through this beamformer adaptation process, the beam center may be co-located with the aircraft location continuously (may follow the aircraft).

[0058] Alternatively, beam manager 175 may use an initial estimate of where to move the beam based on the latest speed and direction of travel of the mobile terminal. In some examples, beam manager 175 may move the spot beam in such a manner that as the mobile terminal moves, the mobile terminal may remain centrally positioned within the coverage area. This may allow the SNR of the mobile terminal to remain high so that overall communication speed and spectral efficiency associated with the mobile terminal may also be high.

[0059] In some examples, beam manager 175 may determine the position of the mobile terminal based on information received from the mobile terminal, such as location coordinates (e.g., determined via a positioning system such as GPS), a speed, a direction or other information associated with the mobile terminal. In some examples, beam manager 175 may determine the position of the mobile terminal based on information external to the mobile terminal, such as based on radar or other signals.

[0060] In some examples, the satellite communication system may provide the communication service to one or more mobile terminals via beamformed spot beams associated with the terminals. For example, in FIG. 3, beam manager 175 may establish beamformed spot beams 150 (e.g., beamformed spot beams 150-a, 150-b, 150-c, and 150-d) for each of mobile terminals 120-a, 120-b, 120-c, and 120-d, and may provide the communication service to the terminals and track the mobile terminals as the mobile terminals move within the coverage area 155 of the satellite communication system.

[0061] In some examples, beam manager 175 may use initial channel state information to determine the locations of the mobile terminals. Beam manager 175 may determine the initial channel state information based on measurements (e.g., signal strengths) of initial signals communicated with (e.g., transmitted to or received from) the mobile terminals. The initial channel state information may be based on respective first locations (e.g., location A for mobile terminal 120-a) of the mobile terminals within the coverage area 155. In some examples, the initial signals may include respective initial channel sounding probes communicated with the mobile terminals.

[0062] In some examples, to generate the beamformed spot beams, 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 a plurality of antenna elements of the satellite communication system. For example, to generate a spot beam for transmitting information to a mobile terminal, beam manager 175 may apply beamforming coefficients to beam signals (that contain the information) to obtain component signals that may be applied to the antenna elements; and to generate a spot beam for receiving information from a mobile terminal, beam manager 175 may apply beamforming coefficients to component signals received from the mobile terminal at the antenna elements to obtain beam signals that contain the information. The beam manager may also determine power levels to allocate for the spot beams. In general, a beam may have a greater capability (e.g., data speed) at higher power levels.

[0063] The plurality of antenna elements may be positioned on one or more of the satellites 105 or may be positioned on components of a ground network (not shown) of the satellite communication system 300 (e.g., access nodes 140 of ground network 135 as shown in FIG. 1). Beam manager 175 may use the beamforming coefficients to form the beamformed spot beams 150 between the satellites 105 and the coverage areas 160. Beam manager 175 may base the beamforming coefficients on the initial channel state information so that the coverage areas 160 of the beams 150 may encompass the respective first locations (e.g., location A) of the associated terminals 120.

[0064] The beamformed spot beams 150 may be forward-link beamformed spot beams (e.g., for transmitting information to the mobile terminals) and/or return-link beamformed spot beams (e.g., for receiving information from the mobile terminals). For example, the beamforming coefficients may include a plurality of sets of forward- link beamforming coefficients and a plurality of sets of return-link beamforming coefficients.

[0065] Beam manager 175 may apply a first set of the forward-link beamforming coefficients at a first time to a set of forward-link beam signals to generate a first set of forward-link component signals for transmission to one or more mobile terminals via the antenna elements at the first time. Transmission of the first set of forward-link component signals to the mobile terminals via the antenna elements may form forward-link beamformed spot beams, each corresponding to one of the mobile terminals for the first time.

[0066] Beam manager 175 may apply a second set of the forward-link beamforming coefficients at a second time to the set of forward-link beam signals to generate a second set of forward-link component signals for transmission to the mobile terminals via the antenna elements at the second time. Transmission of the second set of forward-link component signals to the mobile terminals via the antenna elements may form the forward-link beamformed spot beams, each corresponding to the mobile terminals for the second time. One or more of the forward-link beamformed spot beams at the second time may have moved from the corresponding forward-link beamformed spot beams at the first time to track movement of corresponding mobile terminals.

[0067] On the return link, beam manager 175 may apply a first set of the return- link beamforming coefficients at a first time to return-link component signals received from the mobile terminals via the antenna elements at the first time. Applying the first set of the return-link beamforming coefficients may form return-link beamformed sport beams, each corresponding to one of the mobile terminals, for the first time.

[0068] Beam manager 175 may apply a second set of the return- link beamforming coefficients at a second time to return-link component signals received from the mobile terminals via the plurality of antenna elements at the second time. Applying the second set of the return-link beamforming coefficients may form the return-link beamformed spot beams for the second time. One or more of the return-link beamformed spot beams at the second time may have moved from the corresponding return-link beamformed spot beams at the first time to track movement of the corresponding mobile terminals.

[0069] In some examples, beam manager 175 may use subsequent channel state information to determine subsequent locations of the mobile terminals. Beam manager 175 may determine the subsequent channel state information based on measurements (e.g., signal strengths) of subsequent signals communicated with the mobile terminals. The subsequent channel state information may be based on respective second locations (e.g., location B for mobile terminal 120-a) of the mobile terminals within the coverage area 155. Differences between the initial channel state information and the subsequent channel state information may be based on movement of the mobile terminals to the respective second locations.

[0070] In some examples, the subsequent signals may include respective subsequent channel sounding probes communicated with the mobile terminals. The revisions made to the beamforming coefficients may be based on the respective subsequent channel sounding probes. In some examples, the respective initial and subsequent channel sounding probes may be communicated with the mobile terminals at a first periodicity and the beamforming coefficients may be updated at a second periodicity based thereon.

[0071] In some examples, beam manager 175 may revise the beamforming coefficients and apply them to convert between the beam signals and the component signals associated with the plurality of antenna elements of the satellite network. The revised beamforming coefficients may be based on the subsequent channel state information so that the new coverage areas (e.g., coverage area 160-a2) of the beams may encompass the respective second locations (e.g., location B) of the mobile terminals.

[0072] The determination of subsequent locations of the mobile terminals and the revisions of the beamforming coefficients based thereon may be repeated by beam manager 175 as often and as long as desired. In this manner, the plurality of beamformed spot beams 150 may track movement of the reference terminals 120 throughout the coverage area 155 of the satellite communication system while communication service is provided to the terminals.

[0073] In some examples, the beamforming coefficients (e.g., initial beamforming coefficients and the revised beamforming coefficients) may include sets of beamforming coefficients. Each set of beamforming coefficients may correspond to a different time period for the set of beamformed spot beams. In some examples, the beamforming coefficients may be revised based on a characteristic, attribute, or condition satisfying (e.g., meeting, exceeding, and/or falling below) a threshold. For example, beam manager 175 may revise and apply beamforming coefficients based on a received signal quality (e.g., measured at the mobile terminal or at the satellite communication system) falling below a threshold (e.g., due to a link impairment associated with the mobile terminal). For example, the beamforming coefficients may be revised so that a power for the beam may increase. This may allow the signal quality associated with the mobile terminal to remain high so that overall communication speed and efficiency associated with the mobile terminal may also be high. In some examples, beam manager 175 may determine the received signal quality based on the subsequent channel state information.

[0074] In some examples, two or more beams may use different resource elements for providing communication services to the respective mobile terminals. For example, beam manager 175 may cause each beam to use a different resource element (e.g., a different combination of frequency channel, time slot, and polarization) to provide communications to its respective mobile terminal while tracking the mobile terminal. By using different resource elements, interference between the beams may be reduced or eliminated, even when the mobile terminals may be close to each other.

[0075] In some examples, two or more beams may use a same resource element for providing communication services to the respective mobile terminals. For example, beam manager 175 may cause two or more beams to use a same combination of frequency channel, time slot, and polarization to provide communications to respective mobile terminals while tracking the mobile terminals. This may be desirable when the mobile terminals are far enough apart so that the respective beams do not interfere with each other. By using the same resource elements, more beams may be used with a particular set of resources, thereby increasing frequency reuse.

[0076] FIGs. 4A and 4B illustrate various examples 410 (e.g., examples 410-a through 410-f) showing possible link impairments and mitigation strategies that support mobile satellite beam capacity compensation in accordance with examples as disclosed herein. In each example 410, each mobile terminal 120 is assigned to its own beam 150. Further, for each example 410 affected by a link impairment (examples 410-b, 410-c, 410-d, and 410-f), the example is shown after mitigation has been performed to compensate for the link impairment, as discussed herein. That is, the example is illustrated after beam manager 175 has performed the compensation to ameliorate the interference.

[0077] To simplify discussion, for all of the mobile terminals 120 in the examples 410, the spot beams associated with the mobile terminals would each use a single resource element at a power equal to 1 to provide the communication to its respective mobile terminal if the mobile terminal was unimpaired. Thus, for examples 410-a and 410-e, which correspond to examples in which no link impairment was detected associated with the corresponding mobile terminals 120-a and 120-e, the number of resource elements and the power are both shown as being equal to one. Further, the spot beams would each be assigned to a first coverage region, if more than one coverage region is available.

[0078] Some link impairments may be static. For purposes of this application, a static link impairment signifies a link impairment that may be known ahead of time, without receiving current impairment information from the mobile terminal or associated spot beam. Examples 410-b, 410-c, and 410-d of FIG. 4A represent examples of static link impairments.

[0079] One example of a static link impairment may include an impairment that occurs as a result of a type of the mobile terminal. Example 410-d corresponds to this type of link impairment. In some examples, the type of the mobile terminal may be based on characteristics of the antennas corresponding to the mobile terminal. In some examples, the type of the mobile terminal may be based on receiver performance corresponding to the mobile terminal. [0080] In some examples, the type of the mobile terminal may be based on different capabilities for the terminal's equipment (e.g., the antenna, high-power amplifier, and/or low- noise amplifier). In some examples, the type of the mobile terminal may be based on information from prior communication sessions. For example, the type of the mobile terminal may be based on channel performance metrics, such as those discussed herein, associated with the mobile terminal, but determined from one or more prior communication sessions. In another example, the type of the mobile terminal may be based on historic satellite calibration measurements associated with the mobile terminal or associated spot beam, and/or the performance of the satellite.

[0081] Another example of a static link impairment may include an impairment that occurs as a result of the mobile terminal being a disadvantaged mobile terminal. Example 410-b corresponds to this type of link impairment. A disadvantaged mobile terminal may be one that is known to have slower speeds associated with transmitting and/or receiving signals via its associated spot beam. This may be due to the mobile terminal having a smaller antenna than other mobile terminals or a worse noise figure, or having a problem with an antenna or any other portion of the communication link, that causes the link impairment. There may be overlap between the disadvantaged terminals and types of terminals. That is, a disadvantaged terminal may also be considered a particular type of terminal.

[0082] Beam manager 175 may determine the presence of many types of static link impairments based on the known information associated with the mobile terminals. For example, beam manager 175 may determine the presence of an impairment associated with a mobile terminal based on the mobile terminal being disadvantaged or of a known particular type.

[0083] Another example of a static link impairment may include an impairment that occurs as a result of the location of the mobile terminal. Example 410-c corresponds to this type of link impairment. This qualifies as a static link impairment because the location of a mobile terminal may be determined without receiving impairment information from the mobile terminal. In one example, an impairment may occur as a result of the mobile terminal nearing the edge of the coverage area of the satellite communication system (e.g., high scan angle for a phased array antenna). In another example, a reflector associated with the mobile terminal may be associated with a phased array and an impairment may occur as a result of the mobile terminal nearing the edge of the coverage region corresponding to the reflector.

Other examples of static link impairments may also be found.

[0084] Beam manager 175 may determine the presence of these type of static link impairments based on the locations of the mobile terminals. For example, beam manager 175 may determine the presence of an impairment associated with a mobile terminal based on the mobile terminal nearing the edge of the coverage area of the satellite communication system or a coverage region associated with the mobile terminal.

[0085] In some examples, to determine the presence of a link impairment based on the mobile terminal nearing the edge of the coverage area of the satellite communication system or the coverage region associated with the mobile terminal, beam manager 175 may determine that the mobile terminal is within a threshold distance of the edge of the coverage area of the satellite communication system or the coverage region associated with the mobile terminal. In some examples, the threshold distance may be based on a scan angle of one or more spot beams from the center of the coverage area of the satellite communication system or the coverage region associated with the mobile terminal.

[0086] Some link impairments may be dynamic. For purposes of this application, a dynamic link impairment signifies a link impairment that may not be known ahead of time; impairment information is received from the mobile terminal or associated spot beam and used to determine when a link impairment is present. Examples 410-f of FIG. 4B represents an example of a dynamic link impairment.

[0087] One example of a dynamic link impairment may include an impairment that occurs as a result of rain fade. Example 410-f corresponds to this type of link impairment. Rain fade may refer to an impairment that occurs due to rain (or other weather phenomena) between a mobile terminal and its associated spot beam. Other examples of dynamic link impairments may also be found.

[0088] Beam manager 175 may determine the presence of dynamic link impairments based on impairment information received from the mobile terminals or associated spot beams. For example, beam manager 175 may determine the presence of a dynamic link impairment associated with a mobile terminal based on one or more channel performance metrics associated with the mobile terminal. In some examples, the channel performance metrics may include one or more of a channel gain, a receiver gain, a noise level, an interference level (e.g., signal to interface-and-noise ratio (SINR)), or the like, associated with the mobile terminal.

[0089] In some examples, beam manager 175 may receive a channel performance metric and determine the presence of an impairment when the channel performance metric satisfies a threshold. For example, as illustrated in FIG. 4B, beam manager 175 may receive channel performance metrics (e.g., SINRs) associated with one or more mobile terminals (e.g., mobile terminals 120-e, 120-f) and compare the channel performance metrics with a threshold value (e.g., threshold SINR). To initiate this, beam manager 175 may cause the mobile terminals to transmit their respective channel performance metrics to beam manager 175. Beam manager 175 may determine a presence of a link impairment if the channel performance metric associated with the mobile terminal satisfies the threshold value. For example, in the example of FIG. 4B, beam manager 175 may receive a high SINR from mobile terminal 120-e associated with beamformed spot beam 150-e and a low SINR from mobile terminal 120-f associated with beamformed sport beam 150-f. If the threshold SINR is between the low and high SINRs, then beam manager 175 may determine that a link impairment is present associated with mobile terminal 120-f and a link impairment is not present associated with mobile terminal 120-e.

[0090] Steps may be taken to mitigate or compensate for link impairments. For example, upon determining the presence of a link impairment associated with one or more mobile terminals, beam manager 175 may change a characteristic associated with resource elements associated with the mobile terminals.

[0091] In some examples, mitigating or compensating for link impairments may include assigning a beamformed spot beam to an additional resource element. For example, beam manager 175 may assign an additional resource element (e.g., additional unique combination of time slot, frequency channel, polarization) to the beam associated with a mobile terminal associated with a link impairment. Example 410-b shows an example in which beam manager 175 has assigned a second resource element to spot beam 150-b to compensate for a link impairment associated with mobile terminal 120-b.

[0092] In some examples, mitigating or compensating for link impairments may include increasing power allocated to a resource element by increasing power for a beamformed spot beam. For example, beam manager 175 may increase power to the beam associated with a mobile terminal that has a link impairment. Example 410-c shows an example in which beam manager 175 has increased the power to spot beam 150-c to compensate for a link impairment associated with mobile terminal 120-c. In some examples, beam manager 175 may increase the power by transmitting a signal to the mobile terminal that represents an adjustment to be made to the transmitting power associated with the mobile terminal. The power of the beam may be adjusted accordingly using the beamforming coefficients and/or by adjusting transmit power from one or more antenna elements.

[0093] In some examples, mitigating or compensating for link impairments may include switching a mobile terminal to a different coverage region. For example, a satellite network may include multiple antenna arrays (e.g., multiple phased array antennas on one or more satellites). In some examples, each of the multiple antenna arrays may be a phased array fed reflector. Beam manager 175 may switch a mobile terminal associated with a link impairment from the coverage region presently associated with the mobile terminal to one of the other coverage regions that has more favorable characteristics for the mobile terminal. For example, beam manager 175 may switch the mobile terminal from a reflector having a coverage region where the mobile terminal is near the edge of the coverage region to a different reflector having an overlapping coverage region where the mobile terminal may not be near the edge of the coverage region. Example 410-d shows an example in which beam manager 175 has switched beamformed spot beam 150-d associated with mobile terminal 120-d to a different coverage region to compensate for a link impairment associated with mobile terminal 120-d.

[0094] In some examples, two or more steps may be performed in conjunction with each other to compensate for a link impairment. For example, the quantity of resource elements and the power associated with a beam may be used in conjunction with each other. Example 410-f shows an example in which beam manager 175 has assigned a second resource element to spot beam 150-f and increased the power for spot beam 150-f to compensate for a link impairment associated with mobile terminal 120-f.

[0095] FIGs. 5A and 5B illustrate timing diagrams 500 and 550 of example mitigation strategies that support mobile satellite beam capacity compensation in accordance with examples as disclosed herein. The mitigation strategies may be used to compensate for link impairments associated with mobile terminals (e.g., mobile terminals 120 of FIGs. 4A and 4B) via associated spot beams (e.g., spot beams 150 of FIGs. 4A and 4B) using a beam manager (e.g., beam manager 175). [0096] Timing diagrams 500 and 550 may consist of multiple time periods 510 (e.g., time periods 510-a through 510-g). For example, a first time period 510-a may extend from a time ti to a time t2, a second time period 510-b may extend from time t2 to a time t3, and so forth. In some examples, the durations of the time periods 510 are equal. During each time period 510, communication service may be provided to the mobile terminal via the associated spot beam as the spot beam tracks the movement of the mobile terminal, as controlled by the beam manager. The communication service may be provided to the mobile terminal by the spot beam during each time period using respective resource elements at respective power levels.

[0097] Timing diagram 500 corresponds to an example mitigation strategy associated with a dynamic link impairment. At time ti, the beam may use a single resource element at a normal beam power level (e.g., equal to Power 1 in FIGs 4A and 4B) for providing communication service to the mobile terminal.

[0098] During each time period 510, the mobile terminal may transmit impairment information (e.g., a channel performance metric) to the beam manager via the spot beam, as represented by window 515 in time period 510-a. During a second window 520 of the time period, the spot beam may use the impairment information to determine if an impairment associated with the mobile terminal is present (e.g., by comparing the channel performance metric with a threshold). This transmitting and comparing may be repeated during each time period 510.

[0099] During each time period 510, if the beam manager determines that an impairment is present (e.g., by determining that the performance metric satisfies the threshold), the beam manager may compensate for the impairment by allocating more power for the spot beam, or assigning the spot beam to an additional resource element, or both.

[0100] For example, during time period 510-b, the beam manager may determine that a link impairment is present by determining that the performance metric received from the mobile terminal during time period 510-b satisfies the threshold. To compensate for the link impairment, the beam manager may allocate more power for the beam and/or assign the beam to an additional resource element starting at the beginning of the next time period 510- c. If, during subsequent time periods (e.g., time periods 510-c and 510-d), the beam manager determines that the link impairment is still present, the beam manager may cause the beam to maintain the use of the increased power and/or the additional resource element. [0101] If during a subsequent time period (e.g., time period 510-e), the beam manager determines that the link impairment is no longer present (e.g., by determining that the performance metric no longer satisfies the threshold), the beam manager may cause the beam to no longer use the increased power and/or additional resource element (e.g., starting at the next time period 510-f).

[0102] Timing diagram 550 corresponds to an example mitigation strategy associated with a static link impairment. Timing diagram 550 is similar to timing diagram 500 except for a few differences. Similar to the mitigation strategy of timing diagram 500, the beam manager may determine whether an impairment is present during each time period 510 as represented by window 520. But because the impairment is a static impairment, the beam manager may determine the presence or absence of the impairment without using impairment information transmitted by the mobile terminal. For example, the beam manager may determine the presence or absence of a static impairment associated with the mobile terminal by using the position of the mobile terminal, which the beam manager may already know from determining beam coefficients for steering the beam to track the mobile terminal.

[0103] Similar to the mitigation strategy of timing diagram 500, if the beam manager determines, during a time period (e.g., time period 510-b), that an impairment is present (e.g., by determining that the mobile terminal is within a threshold distance to the edge of the coverage area of the satellite communication system or the coverage region associated with the mobile terminal), the beam manager may compensate for the impairment by allocating more power for the spot beam and/or assigning the spot beam to an additional resource element starting at the first of the next time period (e.g., time period 510-c). Also similar to the mitigation strategy of timing diagram 500, if the beam manager determines during a subsequent time period (e.g., time period 510-e) that the link impairment is no longer present (e.g., by determining that the mobile terminal is no longer within the threshold distance to the edge of the coverage area or the coverage region), the beam manager may cause the beam to no longer use the increased power and/or additional resource element (e.g., starting at the next time period 510-f).

[0104] FIG. 6 shows a block diagram 600 of a beam manager 605 that supports mobile satellite beam capacity compensation in accordance with examples as disclosed herein. Beam manager 605 may be an example of beam manager 175 of FIG. 1. Beam manager 605 may include a bus 625, a beam compensation manager 670, a memory 630, code 635, a processor 640, a beamformer 645, and a beam signal processor 650, and may be configured to control beam tracking of mobile terminals (e.g., mobile terminals 120); and resource allocation and deconfliction of beamformed spot beams (e.g., beamformed spot beams 150) via an antenna array 610.

[0105] Beam manager 605 may be located within a ground network (e.g., ground network 135 of FIG. 1) or a satellite network (e.g., satellite network 101 of FIG. 1) of the satellite communications system. Alternatively, beam manager 605 may be divided between the ground network and the satellite network. In one example (e.g., corresponding to a GBBF configuration), all of the components of beam manager 605 may be located in the ground network. In another example (e.g., corresponding to an OBBF configuration), the beamformer 645 may be located in the satellite network (e.g., in one or more of the satellites) and the rest of the components of beam manager 605 may each be located in either the ground network or the satellite network. In some examples, a distributed implementation may be used. For example, one or more components or portions thereof of beam manager 605 may reside on different servers (e.g., hosted in the cloud). In some examples, beam manager 605 may be located at a single entity.

[0106] Antenna array 610 may be an example of the antennas of the satellite network 101 of FIG. 1 and may include antenna elements 615. In some examples, one or more of the antenna elements 615 may be or include an antenna panel. The spacing between antenna elements 615 may be evenly distributed across an aperture of antenna array 610, or the spacing of antenna elements 615 may be different across antenna array 610. In some examples, a first antenna array 610 may be included within the ground segment and a second antenna array 610 (e.g., one or more antenna arrays coupled with each other using transponders) may be included within the space segment.

[0107] Bus 625 may represent an interface over which signals may be exchanged between components of beam manager 605 and a location (e.g., a central location) that may be used to distribute the signals to the signal processing components of beam manager 605 (e.g., beam compensation manager 670, beam signal processor 650, beamformer 645). Bus 625 may include one or more wired interfaces. Additionally, or alternatively, bus 625 may be a wireless interface that is used to wirelessly communicate signaling between the signal processing components — e.g., in accordance with a communication protocol. Beamformer 645 may be coupled with antenna elements 615 via one or more wired or wireless interfaces. [0108] The 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. The memory 630 may store code 635 that is computer- readable and computer-executable. The code may include instructions that, when executed by processor 640, cause beam manager 605 to perform various functions described herein. The code 635 may be stored in a non- transitory computer-readable medium such as system memory or another type of memory. In some cases, the code 635 may not be directly executable by processor 640 but may cause a computer (e.g., when compiled and executed) to perform functions described herein. In some cases, the memory 630 may contain, among other things, a basic I/O system (BIOS) which may control basic hardware or software operation such as the interaction with peripheral components or devices.

[0109] Processor 640 may include an intelligent hardware device (e.g., a general-purpose processor), a digital signal processor (DSP), a central processing unit (CPU), a microcontroller, an application- specific integrated circuit (ASIC), a field programmable gate array (FPGA), a programmable logic device (PLD), a discrete gate or transistor logic component, a discrete hardware component, or any combination thereof. Processor 640 may be configured to execute computer-readable instructions stored in a memory (e.g., memory 630) to cause beam manager 605 to perform various functions (e.g., functions or tasks supporting mobile satellite beam resource allocation). For example, processor 640 and memory 630 may be configured to perform the various functions described herein.

[0110] Beam signal processor 650 may be configured to process (e.g., demodulate, decode) receive beam signals 654 received from beamformer 645. Beam signal processor 650 may decode data symbols included in the receive beam signals 654 to obtain receive beam data signals 664. Information (e.g., packets) in receive beam data signals 664 may be passed (e.g., via network(s) 125) to a destination device. Beam signal processor 650 may also be configured to process (e.g., encode, modulate) transmit beam data signals 662 to obtain transmit beam signals 652 to send to beamformer 645. Transmit beam data signals 662 may include information (e.g., packets) received (e.g., via network(s) 125) for transmission to terminals 120.

[0111] Beam compensation manager 670 may be configured to determine the presence or absence of link impairments associated with mobile terminals that are being tracked by respective spot beams, determine power level and resource element changes for the spot beams based on the presence or absence of the link impairments, and direct the execution of those changes. Beam compensation manager 670 may include a terminal tracker 620 and an impairment compensator 675.

[0112] Terminal tracker 620 may be configured to determine information for beamformer 645 to use in forming beamformed spot beams (e.g., beamformed spot beams 150 of FIG. 1) using antenna elements 615. To determine the information for forming the beamformed spot beams, terminal tracker 620 may identify a set of terminals (e.g., mobile terminals 120 of FIG. 1) to be assigned as reference terminals, and may determine spatial information associated with the reference terminals. Terminal tracker 620 may determine a set of beamforming coefficients (e.g., phase shifts, amplitude components) that beamformer 645 may use to generate beamformed spot beams having individual coverage areas directed to the spatial information associated with the reference terminals.

[0113] Terminal tracker 620 may determine the beamforming coefficients to isolate signals transmitted over beamformed spot beams from one another — e.g., by, for each beamformed spot beam, emphasizing the signals transmitted within the beamformed spot beam and canceling interference from signals transmitted within other beamformed spot beams. The beamforming coefficients may be included in an M x N matrix, where a value of M may indicate the quantity of antennas and a value of N may indicate the quantity of spatial layers, where the value of N may be less than or equal to the value of M.

[0114] In some examples, the beamforming coefficients may be determined at the one or more satellites 105. In some examples, the beamforming coefficients may be received by the one or more satellites from one or more ground stations (e.g., network devices 130 or other stations of ground network 135) after terminal tracker 620 determines the beamforming coefficients

[0115] Impairment compensator 675 may be configured to perform beam resource allocation, including coordinating resource elements used by the beams. For example, impairment compensator 675 may determine, for allocation of each beamformed spot beam: one or more frequency ranges or channels (e.g., a frequency channel 210 of FIG. 2B); one or more time periods and/or time slots (e.g., time period 215, time slot t of FIG. 2B); and/or a polarity. Impairment compensator 675 may be configured to allocate a number of resource elements to beams based on link impairments associated with the mobile terminals associated with the beams. To allocate the beams to the determined resource elements, impairment compensator 675 may include various components, such as frequency converters, schedulers, and polarization components.

[0116] Impairment compensator 675 may be further configured to allocate power to the beams. For example, impairment compensator may allocate power to the beams based on link impairments associated with the mobile terminals associated with the beams.

[0117] In some examples, for transmission of beamformed spot beams via antenna elements 615, impairment compensator 675 may determine frequency ranges or channels, time slots, and power level for applying to a set of transmit beam signals 652 associated with the beamformed spot beams. Beamformer 645 may apply, based on the frequency ranges or channels, and the power level, the set of transmit beamforming coefficients to the set of transmit beam signals 652 to obtain component signals 656 for transmission via antenna elements 615.

[0118] In some examples, for reception of beamformed spot beams via antenna elements 615, terminal tracker 620 may determine a set of receive beamforming coefficients, based on frequency ranges or channels and power levels determined by impairment compensator 675, to obtain a set of component signals 656. The frequency ranges or channels and time slots may be applied to the component signals 656 by impairment compensator 675 or beamformer 645 to obtain a set of receive beam signals 654 associated with the beamformed spot beams.

[0119] In some examples, terminal tracker 620, impairment compensator 675, beamformer 645, beam signal processor 650, or various combinations or components thereof, may be implemented in hardware (e.g., in communications management circuitry). The hardware may include a processor, a DSP, an ASIC, an FPGA or other PLD, a discrete gate or transistor logic, discrete hardware components, or any combination thereof configured as or otherwise supporting a means for performing the functions described in the present disclosure. In some examples, a processor and memory coupled with the processor may be configured to perform one or more of the functions described herein (e.g., by executing, by the processor, instructions stored in the memory).

[0120] Additionally, or alternatively, terminal tracker 620, impairment compensator 675, beamformer 645, beam signal processor 650, or various combinations or components thereof, may be implemented in code 635 (e.g., as communications management software or firmware), executed by processor 640. If implemented in code 635 executed by processor 640, the functions of terminal tracker 620, impairment compensator 675, beamformer 645, beam signal processor 650, or various combinations or components thereof may be performed by a general-purpose processor, a DSP, a CPU, an ASIC, an FPGA, or any combination of these or other programmable logic devices (e.g., configured as or otherwise supporting a means for performing the functions described in the present disclosure).

[0121] FIG. 7 shows a block diagram 700 of a beam compensation manager 720 that supports mobile satellite beam capacity compensation in accordance with examples as disclosed herein. Beam compensation manager 720 may be an example of aspects of beam compensation manager 670 as described with reference to FIG. 6. Beam compensation manager 720, or various components thereof, may be an example of means for performing various aspects of mobile satellite beam capacity compensation as described herein. For example, beam compensation manager 720 may include a communications manager 725, an assignment director 730, a beamforming manager 735, an impairment determiner 740, a terminal subset determiner 745, a resource element subset determiner 750, an impairment compensation manager 755, or any combination thereof. Each of these components may communicate, directly or indirectly, with one another (e.g., via one or more buses).

[0122] The communications manager 725 may be configured as or otherwise support a means for providing a communication service to a plurality of mobile terminals via a set of beamformed spot beams of a satellite communication system using a set of resource elements, as discussed herein. Each mobile terminal may be assigned to a beamformed spot beam. In some examples, the communications manager 725 may comprise one or more of the other components of beam compensation manager 720. In some examples, the communications manager 725 may comprise the assignment director 730, the beamforming manager 735, the impairment determiner 740, the terminal subset determiner 745, the resource element subset determiner 750, and the impairment compensation manager 755.

[0123] The assignment director 730 may be configured as or otherwise support a means for assigning mobile terminals to beamformed spot beams and beamformed spot beams to resource elements, as discussed herein. In some examples, assignment director 730 may be configured as or otherwise support a means for assigning resource elements to beamformed spot beams and/or beamformed spot beams to mobile terminals. In some examples, the assignment director 730 may be configured as or otherwise support a means for assigning a beamformed spot beam to which a mobile terminal of the subset of mobile terminals is assigned, to an additional resource element. In some examples, the assignment director 730 may be configured as or otherwise support a means for unassigning the beamformed spot beam from the additional resource element.

[0124] The beamforming manager 735 may be configured as or otherwise support a means for adjusting respective coverage areas of beamformed spot beams to track movement of respective mobile terminals of the plurality of mobile terminals within a coverage area of the satellite communication system, as discussed herein. The adjusting may be performed over a plurality of time periods. In some examples, the beamforming manager 735 may be configured as or otherwise support a means for increasing power allocated to a resource element by increasing power to a beamformed spot beam associated with the resource element.

[0125] The impairment determiner 740 may be configured as or otherwise support a means for determining a presence of link impairments associated with one or more mobile terminals, as discussed herein. The determining may be performed for one or more time periods. In some examples, the impairment determiner 740 may be configured as or otherwise support a means for determining that one or more of the link impairments are no longer present. In some examples, the impairment determiner 740 may be configured as or otherwise support a means for receiving feedback from a mobile terminal. The feedback may include a channel performance metric. In some examples, the impairment determiner 740 may be configured as or otherwise support a means for determining that a channel performance metric of the mobile terminal satisfies a threshold. In some examples, the impairment determiner 740 may be configured as or otherwise support a means for determining that the mobile terminal is within a threshold distance of an edge of the coverage area of the satellite communication system or an edge of the coverage region associated with the mobile terminal. In some examples, the impairment determiner 740 may be configured as or otherwise support a means for determining the presence of a link impairment based at least in part on the determination that the mobile terminal is within the threshold distance of the edge of the coverage area of the satellite communication system or the coverage region associated with the mobile terminal.

[0126] The terminal subset determiner 745 may be configured as or otherwise support a means for determining a subset of mobile terminals associated with the link impairments, as discussed herein. The determining may be performed for each time period for which the presence of a link impairment has been determined.

[0127] The resource element subset determiner 750 may be configured as or otherwise support a means for determining a subset of resource elements associated with the link impairments, as discussed herein. The determining may be performed for each time period for which the presence of a link impairment has been determined.

[0128] The impairment compensation manager 755 may be configured as or otherwise support a means for compensating for link impairments, as discussed herein. The compensating may include changing a characteristic associated with a subset of resource elements. The compensating may be performed for each time period for which the presence of a link impairment has been determined. In some examples, the impairment compensation manager 755 may be configured as or otherwise support a means for switching the mobile terminal to a different coverage region. In some examples, the impairment compensation manager 755 may be configured as or otherwise support a means for directing the assignment director 730 to assign a beamformed spot beam to an additional resource element. In some examples, the impairment compensation manager 755 may be configured as or otherwise support a means for directing the beamforming manager 735 to increase power to a beamformed spot beam associated with a mobile terminal.

[0129] In some examples, aspects of one or more components of beam compensation manager 670 or 720 may be found in other components of the beam compensation manager or even outside of the beam compensation manager. For example, processor 640 and memory 630 may be used in performing one or more functions associated with the components of beam compensation manager 720.

[0130] FIG. 8 shows a flowchart illustrating a method 800 that supports mobile satellite beam capacity compensation in accordance with examples as disclosed herein. The operations of method 800 may be implemented by a satellite communication system or its components as described herein. For example, the operations of the method 800 may be performed by a beam manager as described with reference to FIGs. 1 through 7. In some examples, a processor may execute a set of instructions to control the functional elements of the beam manager to perform the described functions. Additionally, or alternatively, the beam manager may perform aspects of the described functions using special-purpose hardware. [0131] At 805, the method may include providing a communication service to a plurality of mobile terminals via a set of beamformed spot beams of a satellite communication system using a set of resource elements. The operations of 805 may be performed in accordance with examples as disclosed herein. In some examples, aspects of the operations of 805 may be performed by a communications manager 725 as described with reference to FIG. 7. In some examples, providing the communication service may include the operations of 810, 815, 820, 825, 830, and 835.

[0132] At 810, the method may include assigning each mobile terminal of the plurality of mobile terminals to a beamformed spot beam of the set of beamformed spot beams, wherein the beamformed spot beam is associated with a resource element of the set of resource elements. The operations of 810 may be performed in accordance with examples as disclosed herein. In some examples, aspects of the operations of 810 may be performed by an assignment director 730 as described with reference to FIG. 7.

[0133] At 815, the method may include adjusting respective coverage areas of the set of beamformed spot beams over a plurality of time periods to track movement of respective mobile terminals of the plurality of mobile terminals within a coverage area of the satellite communication system. The operations of 815 may be performed in accordance with examples as disclosed herein. In some examples, aspects of the operations of 815 may be performed by a beamforming manager 735 as described with reference to FIG. 7.

[0134] At 820, the method may include determining, for one or more time periods of the plurality of time periods, a presence of one or more link impairments for a subset of the set of resource elements associated with a subset of the set of beamformed spot beams to which a subset of the plurality of mobile terminals are assigned. The operations of 820 may be performed in accordance with examples as disclosed herein. In some examples, aspects of the operations of 820 may be performed by an impairment determiner 740 as described with reference to FIG. 7.

[0135] At 825, the method may include compensating, for each of the one or more time periods for which the presence of a link impairment has been determined, for the one or more link impairments associated with the subset of resource elements for the one or more time periods. The operations of 825 may be performed in accordance with examples as disclosed herein. In some examples, aspects of the operations of 825 may be performed by an impairment compensation manager 755 as described with reference to FIG. 7. [0136] FIG. 9 illustrates a flowchart showing a method 900 that supports mobile satellite beam capacity compensation in accordance with examples as disclosed herein. The operations of the method 900 may be implemented by a beam manager or its components as described herein. For example, the operations of the method 900 may be performed by a beam manager as described with reference to FIGs. 1 through 7. In some examples, a processor may execute a set of instructions to control the functional elements of the beam manager to perform the described functions. Additionally, or alternatively, the beam manager may perform aspects of the described functions using special-purpose hardware.

[0137] At 905, the method may include providing a communication service to a mobile terminal via a beamformed spot beam of a satellite communication system using a set of resource elements. The operations of 905 may be performed in accordance with examples as disclosed herein. In some examples, aspects of the operations of 905 may be performed by a communications manager 725 as described with reference to FIG. 7. In some examples, providing the communication service may include the operations of 910, 915, 920, and 925.

[0138] At 910, the method may include assigning the mobile terminal to a beamformed spot beam associated with a resource element of the set of resource elements. The operations of 910 may be performed in accordance with examples as disclosed herein. In some examples, aspects of the operations of 910 may be performed by an assignment director 730 as described with reference to FIG. 7.

[0139] At 915, the method may include adjusting a coverage area of the beamformed spot beam to track movement of the mobile terminal within a coverage area of the satellite communication system. The operations of 915 may be performed in accordance with examples as disclosed herein. In some examples, aspects of the operations of 915 may be performed by a beamforming manager 735 as described with reference to FIG. 7.

[0140] At 920, the method may include determining, during a first time period, a presence of a link impairment associated with the resource element. The operations of 920 may be performed in accordance with examples as disclosed herein. In some examples, aspects of the operations of 920 may be performed by an impairment determiner 740 as described with reference to FIG. 7.

[0141] At 925, the method may include compensating, for a second time period, for the link impairment associated with the resource element. The operations of 925 may be performed in accordance with examples as disclosed herein. In some examples, aspects of the operations of 925 may be performed by an impairment compensation manager 755 as described with reference to FIG. 7.

[0142] In some examples, an apparatus as described herein may perform a method or methods, such as method 800 and/or method 900. The apparatus may include features, circuitry, logic, means, or instructions (e.g., a non-transitory computer-readable medium storing instructions executable by a processor), or any combination thereof for performing the method or methods.

[0143] It should be noted that these methods describe examples of implementations, and that the operations and the steps may be rearranged or otherwise modified such that other implementations are possible. In some examples, aspects from two or more of the methods may be combined. For example, aspects of each of the methods may include steps or aspects of the other methods, or other steps or techniques described herein.

[0144] Information and signals described herein may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout the description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

[0145] The various illustrative blocks and modules described in connection with the disclosure herein may be implemented or performed with a general-purpose processor, a DSP, an ASIC, an FPGA, or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices (e.g., a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration).

[0146] The functions described herein may be implemented in hardware, software executed by a processor, firmware, or any combination thereof. If implemented in software executed by a processor, the functions may be stored on or transmitted over as one or more instructions or code on a computer readable medium. Other examples and implementations are within the scope of the disclosure and appended claims. For example, due to the nature of software, functions described herein can be implemented using software executed by a processor, hardware, firmware, hardwiring, or combinations of any of these. Features implementing functions may also be physically located at various positions, including being distributed such that portions of functions are implemented at different physical locations.

[0147] Computer readable media includes both non-transitory computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. A non-transitory storage medium may be any available medium that can be accessed by a general purpose or special purpose computer. By way of example, and not limitation, non-transitory 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-transitory medium 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 special purpose computer, or a general purpose or special purpose processor. Also, any connection is properly termed a computer readable medium. For example, if the software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium. Disk and disc, as used herein, include CD, laser disc, optical disc, digital versatile disc (DVD), floppy disk and Blu ray disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above are also included within the scope of computer readable media.

[0148] As used herein, including in the claims, “or” as used in a list of items (e.g., a list of items prefaced by a phrase such as “at least one of’ or “one or more of’) indicates an inclusive list such that, for example, a list of at least one of A, B, or C means A or B or C or AB or AC or BC or ABC (i.e., A and B and C). Also, as used herein, the phrase “based on” shall not be construed as a reference to a closed set of conditions. For example, an exemplary step that is described as “based on condition A” may be based on both a condition A and a condition B without departing from the scope of the present disclosure. In other words, as used herein, the phrase “based on” shall be construed in the same manner as the phrase “based at least in part on.” [0149] In the appended figures, similar components or features may have the same reference label. Further, various components of the same type may be distinguished by following the reference label by a dash and a second label that distinguishes among the similar components. If just the first reference label is used in the specification, the description is applicable to any one of the similar components having the same first reference label irrespective of the second reference label, or other subsequent reference label.

[0150] The description set forth herein, in connection with the appended drawings, describes example configurations and does not represent all the examples that may be implemented or that are within the scope of the claims. The term “exemplary” used herein means “serving as an example, instance, or illustration,” and not “preferred” or “advantageous over other examples.” The detailed description includes specific details for the purpose of providing an understanding of the described techniques. These techniques, however, may be practiced without these specific details. In some instances, well known structures and devices are shown in block diagram form in order to avoid obscuring the concepts of the described examples.

[0151] The description herein is provided to enable a person skilled in the art to make or use the disclosure. Various modifications to the disclosure will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other variations without departing from the scope of the disclosure. Thus, the disclosure is not limited to the examples and designs described herein but is to be accorded the broadest scope consistent with the principles and novel features disclosed herein.

Claims

What is claimed is:

1. A method comprising: providing a communication service to a plurality of mobile terminals (120) via a set of beamformed spot beams (150) of a satellite communication system (100) using a set of resource elements, wherein providing the communication service comprises: assigning each mobile terminal (120) of the plurality of mobile terminals to a beamformed spot beam (150) of the set of beamformed spot beams, wherein the beamformed spot beam is associated with a resource element of the set of resource elements; adjusting respective coverage areas (160) of the set of beamformed spot beams (150) over a plurality of time periods (510) to track movement of respective mobile terminals (120) of the plurality of mobile terminals within a coverage area (155) of the satellite communication system (100); determining, for one or more time periods (510) of the plurality of time periods, a presence of one or more link impairments for a subset of the set of resource elements associated with a subset of the set of beamformed spot beams (150) to which a subset of the plurality of mobile terminals (120) are assigned; and compensating, for each of the one or more time periods (510) for which the presence of a link impairment has been determined, for the one or more link impairments associated with the subset of resource elements for the one or more time periods.

2. The method of claim 1, wherein compensating for the one or more link impairments comprises changing a characteristic associated with the subset of resource elements for the one or more time periods (510).

3. The method of any one of claims 1 or 2, wherein compensating for the one or more link impairments comprises: increasing power allocated to a resource element of the subset of resource elements by increasing power to a beamformed spot beam associated with the resource element for the one or more time periods (510).

4. The method of any one of claims 1 through 3, wherein compensating for the one or more link impairments comprises: assigning a beamformed spot beam (150) of the subset of beamformed spot beams to an additional resource element.

5. The method of any one of claims 1 through 4, wherein the coverage area (155) of the satellite communication system (100) comprises a plurality of coverage regions having different characteristics, and wherein compensating for the one or more link impairments comprises: switching a mobile terminal (120) of the subset of mobile terminals to a different coverage region.

6. The method of any one of claims 1 through 5, wherein the one or more link impairments comprises one or more of a static link impairment or a dynamic link impairment.

7. The method of any one of claims 1 through 6, wherein the one or more link impairments comprises an impairment based on a disadvantaged mobile terminal.

8. The method of any one of claims 1 through 7, wherein the one or more link impairments comprises a rain fade.

9. The method of any one of claims 1 through 8, wherein determining the presence of one or more link impairments comprises: receiving a channel performance metric associated with a mobile terminal (120) of the plurality of mobile terminals; determining that the channel performance metric associated with the mobile terminal (120) satisfies a threshold; and determining that a link impairment is present associated with the resource element associated with the beamformed spot beam (150) to which the mobile terminal (120) is assigned, based at least in part on the determination that the channel performance metric associated with the mobile terminal (120) satisfies the threshold.

10. The method of claim 9, wherein the channel performance metric comprises one or more of a channel gain, a receiver gain, an interference level, or a noise level associated with the mobile terminal (120).

11. The method of claim 9, wherein the channel performance metric comprises a signal to interface-and-noise ratio (SINR) associated with the mobile terminal (120).

12. The method of any one of claims 1 through 11, wherein determining the presence of one or more link impairments comprises: determining that a mobile terminal (120) of the plurality of mobile terminals is within a threshold distance of an edge of the coverage area (155) of the satellite communication system (100); and determining that a link impairment is present that is associated with the resource element associated with the beamformed spot beam (150) to which the mobile terminal (120) is assigned, based at least in part on the determination that the mobile terminal (120) is within the threshold distance of the edge of the coverage area (155) of the satellite communication system (100).

13. The method of claim 12, wherein the threshold distance is based at least in part on a scan angle of one or more beamformed spot beams (150) of the set of beamformed spot beams from a center of the coverage area (155) of the satellite communication system (100).

14. The method of any one of claims 1 through 13, wherein determining the presence of one or more link impairments is based at least in part on channel performance metrics of the plurality of mobile terminals (120).

15. The method of any one of claims 1 through 14, wherein determining the presence of one or more link impairments is based at least in part on a type of a mobile terminal (120) of the plurality of mobile terminals.

16. The method of claim 15, wherein the type of the mobile terminal (120) is based at least in part on characteristics of respective antennas corresponding to the mobile terminal.

17. The method of claim 15, wherein the type of the mobile terminal (120) is based at least in part on receiver performance corresponding to the mobile terminal.

18. The method of any one of claims 1 through 17, wherein: assigning each mobile terminal to a beamformed spot beam comprises assigning a first mobile terminal (120) to a first beamformed spot beam (150) associated with a first resource element; adjusting respective coverage areas of the set of beamformed spot beams to track movement of the respective mobile terminals comprises adjusting the coverage area (160) of the first beamformed spot beam (150) to track movement of the first mobile terminal (120); determining a presence of one or more link impairments comprises determining, during a first time period (510), a presence of a first link impairment associated with the first resource element; and compensating for the one or more link impairments comprises compensating, for a second time period (510), for the first link impairment associated with the first resource element.

19. The method of claim 18, wherein compensating for the first link impairment comprises: changing a characteristic of the first resource element.

20. The method of claim 19, wherein providing the communication service further comprises: determining, during a third time period (510), that the first link impairment is no longer present; and resetting, for a fourth time period (510), the characteristic of the first resource element.

21. The method of any one of claims 18 through 20, wherein compensating for the first link impairment comprises: increasing power allocated to the first resource element by increasing power to the first beamformed spot beam (150).

22. The method of any one of claims 18 through 21, wherein compensating for the first link impairment comprises: assigning the first beamformed spot beam (150) to an additional resource element of the set of resource elements.

23. The method of claim 22, wherein providing the communication service further comprises: determining, during a third time period (510), that the first link impairment is no longer present; and unassigning, for a fourth time period (510), the first beamformed spot beam (150) from the additional resource element.

24. The method of any one of claims 18 through 23, wherein the coverage area (155) of the satellite communication system (100) comprises a plurality of coverage regions having different characteristics, and wherein compensating for the first link impairment comprises: switching the first mobile terminal (120) to a different coverage region.

25. The method of any one of claims 18 through 24, wherein the first link impairment comprises a static link impairment or a dynamic link impairment.

26. The method of any one of claims 18 through 25, wherein the first link impairment comprises an impairment based on the first mobile terminal (120) being a disadvantaged mobile terminal.

27. The method of any one of claims 18 through 25, wherein the first link impairment comprises a rain fade.

28. The method of any one of claims 18 through 27, wherein determining the presence of the first link impairment comprises: determining that a channel performance metric of the first mobile terminal (120) satisfies a threshold.

29. The method of claim 28, wherein providing the communication service further comprises: receiving feedback from the first mobile terminal (120) during the first time period (510), wherein the feedback comprises the channel performance metric.

30. The method of any one of claims 28 or 29, wherein providing the communication service further comprises: determining, during a third time period (510), that the first link impairment is no longer present, wherein determining that the first link impairment is no longer present comprises: determining that the channel performance metric of the first mobile terminal (120) fails to satisfy the threshold.

31. The method of any one of claims 18 through 30, wherein determining the link impairment is based at least in part on the adjusting the coverage area (160) of the first beamformed spot beam (150).

32. The method of any one of claims 18 through 31, wherein determining the presence of the first link impairment is based at least in part on terminal and satellite calibration measurements of the first mobile terminal (120).

33. The method of any one of claims 18 through 32, wherein determining the presence of the first link impairment comprises: determining that the first mobile terminal (120) is within a threshold distance of an edge of the coverage area (155) of the satellite communication system (100); and determining that the first link impairment is present based at least in part on the determination that the first mobile terminal (120) is within the threshold distance of the edge of the coverage area (155) of the satellite communication system (100).

34. The method of claim 33, wherein the threshold distance is based at least in part on a scan angle of the first beamformed spot beam (150) from a center of the coverage area (155) of the satellite communication system (100).

35. An apparatus, comprising: a beam manager (175) associated with a memory device, wherein the beam manager (175) is configured to cause the apparatus to: provide a communication service to a plurality of mobile terminals

(120) via a set of beamformed spot beams (150) of a satellite communication system (100) using a set of resource elements, wherein providing the communication service comprises: assign each mobile terminal (120) of the plurality of mobile terminals to a beamformed spot beam (150) of the set of beamformed spot beams, wherein the beamformed spot beam is associated with a resource element of the set of resource elements; adjust respective coverage areas (160) of the set of beamformed spot beams (150) over a plurality of time periods (510) to track movement of respective mobile terminals (120) of the plurality of mobile terminals within a coverage area (155) of the satellite communication system (100); determine, for one or more time periods (510) of the plurality of time periods, a presence of one or more link impairments for a subset of the set of resource elements associated with a subset of the set of beamformed spot beams (150) to which a subset of the plurality of mobile terminals (120) are assigned; and compensating, for each of the one or more time periods (510) for which the presence of a link impairment has been determined, for the one or more link impairments associated with the subset of resource elements for the one or more time periods (510).

36. The apparatus of claim 35, wherein compensating for the one or more link impairments is configured to cause the apparatus to: change a characteristic associated with the subset of resource elements for the one or more time periods (510).

37. The apparatus of any one of claims 35 or 36, wherein compensating for the one or more link impairments is configured to cause the apparatus to: increase power allocated to a resource element of the subset of resource elements by increasing power to a beamformed spot beam (150) associated with the resource element for the one or more time periods (510).

38. The apparatus of any one of claims 35 through 37, wherein compensating for the one or more link impairments is configured to cause the apparatus to: assign a beamformed spot beam (150) of the subset of beamformed spot beams to an additional resource element.

39. The apparatus of any one of claims 35 through 38, wherein the coverage area (155) of the satellite communication system (100) comprises a plurality of coverage regions having different characteristics, and wherein compensating for the one or more link impairments is further configured to cause the apparatus to: switch a mobile terminal (120) of the subset of mobile terminals to a different coverage region.

40. The apparatus of any one of claims 35 through 39, wherein the one or more link impairments comprises one or more of a static link impairment or a dynamic link impairment.

41. The apparatus of any one of claims 35 through 40, wherein the one or more link impairments comprises an impairment based on a disadvantaged mobile terminal.

42. The apparatus of any one of claims 35 through 41, wherein the one or more link impairments comprises a rain fade.

43. The apparatus of any one of claims 35 through 42, wherein determining the presence of one or more link impairments is configured to cause the apparatus to: receive a channel performance metric associated with a mobile terminal (120) of the plurality of mobile terminals; determine that the channel performance metric associated with the mobile terminal (120) satisfies a threshold; and determine that a link impairment is present associated with the resource element associated with the beamformed spot beam (150) to which the mobile terminal (120) is assigned, based at least in part on the determination that the channel performance metric associated with the mobile terminal (120) satisfies the threshold.

44. The apparatus of claim 43, wherein the channel performance metric comprises one or more of a channel gain, a receiver gain, an interference level, or a noise level associated with the mobile terminal (120).

45. The apparatus of claim 43, wherein the channel performance metric comprises a signal to interface-and-noise ratio (SINR) associated with the mobile terminal (120).

46. The apparatus of any one of claims 35 through 45, wherein determining the presence of one or more link impairments is configured to cause the apparatus to: determine that a mobile terminal (120) of the plurality of mobile terminals is within a threshold distance of an edge of the coverage area (155) of the satellite communication system (100); and determine that a link impairment is present that is associated with the resource element associated with the beamformed spot beam (150) to which the mobile terminal (120) is assigned, based at least in part on the determination that the mobile terminal (120) is within the threshold distance of the edge of the coverage area (155) of the satellite communication system (100).

47. The apparatus of claim 46, wherein the threshold distance is based at least in part on a scan angle of one or more beamformed spot beams (150) of the set of beamformed spot beams from a center of the coverage area (155) of the satellite communication system (100).

48. The apparatus of any one of claims 35 through 47, wherein determining the presence of one or more link impairments is based at least in part on channel performance metrics of the plurality of mobile terminals (120).

49. The apparatus of any one of claims 35 through 48, wherein determining the presence of one or more link impairments is based at least in part on a type of a mobile terminal (120) of the plurality of mobile terminals.

50. The apparatus of claim 49, wherein the type of the mobile terminal is based at least in part on characteristics of respective antennas corresponding to the mobile terminal (120).

51. The apparatus of claim 49, wherein the type of the mobile terminal is based at least in part on receiver performance corresponding to the mobile terminal (120).

52. The apparatus of any one of claims 35 through 51, wherein: assigning each mobile terminal to a beamformed spot beam is configured to cause the apparatus to assign a first mobile terminal (120) to a first beamformed spot beam (150) associated with a first resource element; adjusting respective coverage areas of the set of beamformed spot beams to track movement of the respective mobile terminals is configured to cause the apparatus to adjust the coverage area (160) of the first beamformed spot beam (150) to track movement of the first mobile terminal (120); determining a presence of one or more link impairments is configured to cause the apparatus to determine, during a first time period (510), a presence of a first link impairment associated with the first resource element; and compensating for the one or more link impairments is configured to cause the apparatus to compensate, for a second time period (510), for the first link impairment associated with the first resource element.

53. The apparatus of claim 52, wherein compensating for the first link impairment is configured to cause the apparatus to: change a characteristic of the first resource element.

54. The apparatus of claim 53, wherein providing the communication service is further configured to cause the apparatus to: determine, during a third time period (510), that the first link impairment is no longer present; and resetting, for a fourth time period (510), the characteristic of the first resource element.

55. The apparatus of any one of claims 52 through 54, wherein compensating for the first link impairment is configured to cause the apparatus to: increase power allocated to the first resource element by increasing power to the first beamformed spot beam (150).

56. The apparatus of any one of claims 52 through 55, wherein compensating for the first link impairment is configured to cause the apparatus to: assign the first beamformed spot beam (150) to an additional resource element of the set of resource elements.

57. The apparatus of claim 56, wherein providing the communication service is further configured to cause the apparatus to: determine, during a third time period (510), that the first link impairment is no longer present; and unassign, for a fourth time period (510), the first beamformed spot beam (150) from the additional resource element.

58. The apparatus of any one of claims 52 through 57, wherein the coverage area (155) of the satellite communication system (100) comprises a plurality of coverage regions having different characteristics, and wherein compensating for the first link impairment is configured to cause the apparatus to: switch the first mobile terminal (120) to a different coverage region.

59. The apparatus of any one of claims 52 through 58, wherein the first link impairment comprises a static link impairment or a dynamic link impairment.

60. The apparatus of any one of claims 52 through 59, wherein the first link impairment comprises an impairment based on the first mobile terminal (120) being a disadvantaged mobile terminal.

61. The apparatus of any one of claims 52 through 59, wherein the first link impairment comprises a rain fade.

62. The apparatus of any one of claims 52 through 61, wherein determining the presence of the first link impairment is configured to cause the apparatus to: determine that a channel performance metric of the first mobile terminal (120) satisfies a threshold.

63. The apparatus of claim 62, wherein providing the communication service is further configured to cause the apparatus to: receive feedback from the first mobile terminal (120) during the first time period (510), wherein the feedback comprises the channel performance metric.

64. The apparatus of any one of claims 62 or 63, wherein providing the communication service is further configured to cause the apparatus to: determine, during a third time period (510), that the first link impairment is no longer present, wherein determining that the first link impairment is no longer present is configured to cause the apparatus to: determine that the channel performance metric of the first mobile terminal (120) fails to satisfy the threshold.

65. The apparatus of any one of claim 52 through 64, wherein determining the link impairment is based at least in part on the adjusting the coverage area (160) of the first beamformed spot beam (150).

66. The apparatus of any one of claims 52 through 65, wherein determining the presence of the first link impairment is based at least in part on terminal and satellite calibration measurements of the first mobile terminal (120).

67. The apparatus of any one of claims 52 through 66, wherein determining the presence of the first link impairment is configured to cause the apparatus to: determine that the first mobile terminal (120) is within a threshold distance of an edge of the coverage area (155) of the satellite communication system (100); and determine that the first link impairment is present based at least in part on the determination that the first mobile terminal (120) is within the threshold distance of the edge of the coverage area (155) of the satellite communication system (100).

68. The apparatus of claim 67, wherein the threshold distance is based at least in part on a scan angle of the first beamformed spot beam (150) from a center of the coverage area (155) of the satellite communication system (100).