Techniques for end-to-end beamforming for multiple zones with simultaneous user coverage

Abstract

A satellite communication system and method of operation provide service to multiple user terminals in multiple non-overlapping user coverage areas based on performing ground-based end-to-end beamforming simultaneously with respect to the multiple user coverage areas. A satellite communication system and method of operation provide service to multiple user terminals in multiple non-overlapping user coverage areas based on performing ground-based end-to-end beamforming simultaneously with respect to the multiple user coverage areas. The system provides multiple simultaneous beams in either forward or reverse direction, and control of beam allocation to respective user coverage areas determines capacity allocation for the respective user coverage areas. Multiple transmit / receive paths onboard the satellite in the system support the end-to-end beamforming, and control of beam allocation is based on controlling allocation of such paths to the respective user coverage areas.

Description

Technical Field

[0001] The disclosed technology uses end-to-end beamforming to simultaneously beamform into non-overlapping geographic coverage areas via end-to-end relays (such as satellites). Background Technology

[0002] Wireless communication systems, such as satellite communication systems, provide a way to transmit information, including audio, video, and various other types of data, from one location to another using communication satellites. Communication satellites typically include one or more antenna assemblies for communicating with various ground-based target devices, which may include ground-based access node terminals or user terminals, either of which can be fixed (e.g., installed at a permanent installation site, moved from one fixed installation site to another, etc.) or mobile (e.g., installed in vehicles, ships, aircraft, handheld devices, etc.).

[0003] One or more antenna assemblies of a communications satellite may be configured to transmit downlink signals (e.g., forward link signals directed to a user terminal or return link signals directed to an access node) and / or receive uplink signals (e.g., forward link signals from an access node or return link signals from a user terminal). One or more antenna assemblies may be associated with a service coverage area in which communication services can be provided to devices via the antenna assemblies.

[0004] In some cases, a communications satellite may be a geostationary satellite, in which case its orbit may be synchronized with the Earth's rotation to maintain the service coverage area substantially stationary relative to the Earth. In other cases, a communications satellite may use a different orbit (e.g., around the Earth), causing the service coverage area to shift above the Earth's surface as the satellite moves laterally along its orbital path.

[0005] Some communication satellites can be positioned at fixed locations to cover a single spot beam area. However, these satellites may not have the ability to move the spot beam to adapt to changes in the service coverage area. Furthermore, such satellite communication architectures essentially provide a uniformly distributed capacity over the service coverage area. For example, the capacity per spot beam is closely related to the allocated bandwidth for each spot beam, which can be predetermined for each spot beam, and therefore allows for virtually no flexibility or configurability.

[0006] While these satellite communication architectures can be valuable when the desired service coverage area is well-known and the capacity demand is evenly distributed across that area, their inflexibility can limit certain applications. For example, communication satellites may be reassigned or deployment conditions (e.g., orbital positions) may change. Additionally, satellite communication services may be aware of changes in user demand (e.g., fixed versus mobile users).

[0007] While signal processing techniques such as beamforming offer some capabilities to adapt to the arrangement of spot beams or service coverage areas, additional flexibility in adapting service coverage areas and spot beam arrangements may be desired. For example, it may be desirable for satellite communication systems and corresponding communication satellites to flexibly and dynamically adjust the location and size of service coverage areas based on factors such as the positioning of user terminals and access node terminals, the spatial distribution of communication service capacity, and the allocation of communication service capacity. Furthermore, it may be desirable for satellite communication systems and corresponding communication satellites to flexibly and dynamically allocate communication resources between different service coverage areas, for example, shifting higher-throughput services to different coverage areas based on dynamically changing conditions. Summary of the Invention

[0008] Methods, systems, and apparatus for end-to-end beamforming with multiple areas covered by users simultaneously are described.

[0009] Further scope of the applicability of the described methods and apparatus will become apparent from the following detailed description, claims, and drawings. The detailed description and specific examples are given by way of illustration only, as various changes and modifications made within the scope of this specification will become apparent to those skilled in the art. Attached Figure Description

[0010] A further understanding of the nature and advantages of the embodiments of this disclosure can be achieved by referring to the following accompanying drawings. In the drawings, similar parts or features may have the same reference numerals. Furthermore, various parts of the same type can be distinguished by a dash following the reference numeral and a second numeral for differentiation among similar parts. If only the first reference numeral is used in the specification, the description applies to any similar components having the same first reference numeral but unrelated to the second reference numeral.

[0011] Figure 1 This invention demonstrates a satellite communication system that supports end-to-end beamforming with simultaneous user coverage of multiple areas, according to various aspects of this disclosure.

[0012] Figure 2 This disclosure demonstrates a satellite communication system configuration that supports end-to-end beamforming with simultaneous user coverage of multiple areas.

[0013] Figure 3 An example diagram is shown illustrating a forward link satellite antenna switching scheme that supports end-to-end beamforming of multiple areas with simultaneous user coverage, according to various aspects of this disclosure.

[0014] Figure 4 An illustration of an example forward signal path supporting end-to-end beamforming with simultaneous user coverage of multiple areas is shown according to various aspects of this disclosure.

[0015] Figure 5 An example diagram is shown illustrating a return-link satellite antenna switching scheme that supports end-to-end beamforming with simultaneous user coverage of multiple areas, according to various aspects of this disclosure.

[0016] Figure 6 An illustration of an example return signal path is shown, demonstrating support for end-to-end beamforming with simultaneous user coverage of multiple areas according to various aspects of this disclosure.

[0017] Figure 7 A block diagram of an end-to-end communication processor supporting end-to-end beamforming with simultaneous user coverage of multiple areas is shown according to various aspects of this disclosure.

[0018] Figure 8 A block diagram of a controller supporting end-to-end beamforming with multiple areas simultaneously covered by users, according to various aspects of this disclosure, is shown.

[0019] Figure 9 A flowchart illustrating an example method for supporting end-to-end beamforming with multiple areas simultaneously covered by users, according to various aspects of this disclosure, is shown. Detailed Implementation

[0020] like Figure 1 The depicted satellite communication system 10 (“System”) provides services to multiple user terminals 12 in multiple non-overlapping user coverage areas 14 (e.g., a first user coverage area 14-1 and a second user coverage area 14-2) by simultaneously performing ground-based end-to-end beamforming relative to multiple user coverage areas 14. Hereinafter, unless otherwise indicated or obvious from the context, the term “beamforming” refers to ground-based end-to-end beamforming, and reference numerals with suffixes are discussed only where suffixes are necessary for clarity.

[0021] Figure 1The details of beamforming in the forward direction (towards user terminal 12) are highlighted, and several simplifications are used to simplify the discussion and maintain clarity. The primary simplification is the depiction of a single user terminal 12-1 in the first user coverage area 14-1 and a single user terminal 12-2 in the second user coverage area 14-2, where the corresponding forward beam 16-1 serves the first user terminal 12-1 and the corresponding forward beam 16-2 serves the second user terminal 12-2. "Serving" implies the fact that one or more forward user signals 18-1 intended for user terminal 12-1 are transmitted in forward beam 16-1. Similarly, forward beam 16-2 transmits forward user signals 18-2 intended for user terminal 12-2.

[0022] The operation of system 10 involves simultaneously forming a potential plurality of forward beams 16 in a first user coverage area 14-1 and a second user coverage area 14-2. Each forward beam 16 serves one or more user terminals 12, for example, each forward beam 16 serves multiple user terminals 12, which are “clustered” in the sense that they are all located within the same beam coverage area 20. Figure 1 For example, beam coverage area 20-1 can be depicted as the ground "footprint" of forward beam 16-1, and beam coverage area 20-2 can be depicted as the ground footprint of forward beam 16-2. User terminal 12 within the footprint of forward beam 16-1 can be served by that beam, and similarly, user terminal 12 within the footprint of forward beam 16-2 can be served by that beam.

[0023] Consider an example approach where, from a system design perspective, each user coverage area 14 is logically divided into multiple beam coverage areas 20, i.e., beam coverage areas 20 of a predetermined pattern, which are based on the known or expected size of the beam footprint 20 and provide forward coverage over the entire user coverage area 14. Serving the user coverage area 14 does not need to simultaneously form as many forward beams 16 as the predefined beam coverage areas 20. Instead, a time-division multiplexing (TDM) pattern can be used, where a smaller number of forward beams 16 are used to illuminate different subsets of the predefined beam coverage areas 20 at different times.

[0024] Forming any given forward beam 16 to illuminate a specific geographic area (i.e., a forward beam 16 whose beam coverage area 20 is located at a desired location within the entire user coverage area 14) requires channel estimation describing the transmission channels from each access node 22, each of which participates in beamforming directed towards a receiver located at or near the geographic center of the desired beam center. Beamforming requires the use of multiple geographically distributed access nodes 22, which form a portion of the ground segment 24 of the system 10.

[0025] In practice, for each forward beam 16 formed, system 10 obtains a channel estimate relative to a user terminal 12 served by that forward beam 16 and located at or near a geographic location designated as the beam center. Such a user terminal 12 may be referred to as a reference user terminal (RUT) or a designated user terminal (DUT). Thus, for a given cluster of user terminals 12 all served by the same forward beam 16, the central one of these user terminals acts as the RUT for estimating the end-to-end channel used to form the forward beam 16. Specifically, satellite communication system 10 uses channel “probing” relative to the RUT associated with each forward beam 16 to determine the end-to-end channel from each access node 22 to the RUT. “Probing” refers to the transmission of a known reference signal used to estimate the channel between the RUT and each access node 22. Probing can be performed periodically, for example, to adapt beamforming weights in response to changing atmospheric conditions.

[0026] Each channel between the RUT and a corresponding one of the access nodes 22 is a multipath channel, wherein the satellite 26 of system 10 serves as an end-to-end relay between the ground segment 24 and the user terminal 12. Here, multipath induction is intentional and arises from the existence of multiple forward signal paths relative to each access node 22 traversing the satellite 26. To understand the induced multipath, consider each access node 22 transmitting a forward uplink signal 28, which is received by some or all of the feeds 30 of the feed link array 32 mounted on the satellite 26. The feed link array 32 may be referred to as a feed link antenna subsystem, where each feed 30 is called a feed link component configured to illuminate the access node region to receive multiple composite input forward signals.

[0027] Each feed 30 receives a superposition of forward uplink signals 28, that is, a superimposed signal 34 consisting of individual forward uplink signals 28 from two or more access nodes 22. The superimposed signal 34 at each feed 30 is unique and depends on the channel between the feed 30 and each access node in the access nodes 22, which may also be referred to as a "satellite access node" or SAN. The superimposed signal 34 may also be referred to as a composite input forward signal.

[0028] Therefore, each feed 30 receives the composite input forward signal 34 and provides it as a received composite input forward signal 36, which is applied to the input of a transponder 38 mounted on the satellite 26. Each transponder 38 can be considered as a signal path within the satellite 26 for transmitting a corresponding one of the received composite input forward signals 36. The number of feeds 30 can be large, for example, five hundred or more, and the satellite 26 includes a transponder 38 for each feed 30. Additional spare transponders 38 may also be present as replacements for failed transponders 38.

[0029] Each repeater 38 provides an unprocessed signal path, meaning it does not perform signal demodulation and remodulation relative to the composite input forward signal 36. However, in one or more embodiments, the repeater 38 includes filters, amplifiers, and frequency shifters to offset from the uplink frequency to the downlink frequency. This operation converts the received composite input forward signal 36 input to each repeater 38 into a corresponding forward composite downlink signal 40, which is transmitted from a corresponding feed 42 in either the first subscriber link feed array 44-1 or the second subscriber link feed array 44-2 as the transmitted forward composite downlink signal 46. The first subscriber link feed array 44-1 serves a first subscriber coverage area 14-1, and the second subscriber link feed array 44-2 serves a second subscriber coverage area 14-2.

[0030] Controlling the number of forward beams 16 allocated to the first user coverage area 14-1 and the number of forward beams 16 allocated to the second user coverage area 14-2 is related to controlling the transponder connectivity within the satellite 26 (i.e., controlling how many transponders 38 are allocated to the first user link feed array 44-1 and how many transponders 38 are allocated to the second user link feed array 44-2). To understand this arrangement, consider simultaneously forming a total of M forward beams 16 based on K access nodes 22 cooperating in beamforming, where there are N feeds 30 in the feed link array 32, N transponders 38 mounted on the satellite 26, and up to N feeds 42 in each of the user link feed arrays 44-1 and 44-2. As a non-limiting example, K equals 512, and M equals N equals K. Assume that each user link feed array 44-1 or 44-2 includes N feeds 42, and the switching circuit system 48 on the satellite 26 is operable to switch the output of each transponder 38 to the first user link feed array 44-1 or the second user link feed array 44-2.

[0031] Switching the outputs of all N transponders 38 to the corresponding feeds of the N feeds 42 in the first user link feed array 44-1 can be understood as allocating all K forward beams 16 to the first user coverage area 14-1. Similarly, switching the outputs of all N transponders 38 to the corresponding feeds of the N feeds 42 in the second user feed link array 44-2 allocates all K forward beams 16 to the second user coverage area 14-2. Switching the outputs of R transponders out of the N transponders 38 to the corresponding feeds of the N feeds 42 in the first user feed link array 44-1, and allocating R forward beams 16 to the first user coverage area 14-1, allows (NR) transponders out of the N transponders 38 to be allocated to form (NR) forward beams 16 for the second user coverage area 14-2.

[0032] In one or more embodiments, each of the first and second user link feed arrays 44-1 includes fewer feeds 42 than the feeds 30 included in the feed link array 32. As a non-limiting example, there are 512 feeds 30 in the feed link array 32, and 358 feeds 42 in the first user link feed array 44-1 and another 358 feeds 42 in the second user link feed array 44-2. This arrangement allows up to seventy percent (358 / 512) of forward capacity to be allocated to either the first user coverage area 14-1 or the second user coverage area 14-2 at any given time. That is, up to 358 feeds 30 and corresponding transponders 38 can be connected to either the first user coverage area 14-1 or the second user coverage area 14-2 at any given time. Of course, satellite 26 can change capacity allocation across time slots or other scheduling intervals, and the seventy percent example is non-limiting.

[0033] The greatest allocation flexibility occurs in embodiments where each repeater 38 can be assigned to either the first user link feed array 44-1 or the second user link feed array 44-2. This flexibility comes at the cost of additional switching or splitting circuitry, and the number of dynamically assignable repeaters 38 may be less than the total.

[0034] In at least one embodiment, each subscriber link feed array 44-1 and 44-2 includes more than N / 2 feeds 42, allowing more than half of the N transponders 38 to be assigned to the corresponding one of the subscriber coverage areas 14-1 or 14-2 at any given time. For example, each subscriber link feed array 44 includes 2N / 3 feeds 42, thereby allowing up to two-thirds of the transponders 38 to be assigned to one selected from subscriber link feed arrays 44-1 or 44-2. In practice, the number of feeds 42 included in each subscriber link feed array 44 does not need to be the same in all subscriber link feed arrays 44, but the number of feeds 42 included in each subscriber link feed array 44 imposes an upper limit on the number of forward beams 16 that can be assigned to the subscriber coverage area 14 served by that subscriber link feed array 44.

[0035] The switching circuitry system 48 operates as a "selector subsystem" and determines which repeaters 38 and how many repeaters are switchable between the first subscriber link feed array 44-1 and the second subscriber link feed array 44-2. For example, it controls the connectivity (allocation) of the repeaters 38 in response to control signals output from the control circuitry system 50. The control circuitry system 50 then includes or is associated with a storage device 52 (e.g., one or more types of memory circuitry) that stores a schedule for controlling the dynamic allocation of capacity between subscriber coverage areas 14, for example, between the first subscriber coverage area 14-1 and the second subscriber coverage area 14-2. The schedule can be dynamically determined or updated, for example, based on uploaded control information determined by the ground segment 24 according to dominant conditions such as different capacity requirements between subscriber coverage areas 14.

[0036] Forward capacity allocation refers to how the total number of forward beams 16 are split (allocated) among the corresponding user coverage areas 14. In one or more embodiments, a corresponding subset of repeaters 38 may be dedicated to a corresponding user coverage area within the user coverage area 14, while other repeaters in the entire set of repeaters 38 may be dynamically switched between user coverage areas 14 to account for varying capacity requirements in the corresponding service areas.

[0037] To further understand beamforming based on the above details, consider user data streams 62 received from one or more external networks 60 into the ground segment 24 of the satellite communication system 10. Examples of external networks include any one or more of the Internet or other packet data networks (PDNs), public land mobile networks (PLMNs), public switched telephone networks (PSTNs), etc. Each user data stream 62 targets a corresponding user terminal 12 in one of the user coverage areas 14 served by the satellite 26. One or more network devices 64 included in the ground segment 24 receive the user data streams 62 and, for each user data stream 62, determine the target user terminal 12 and determine a forward beam 16 for serving the target user terminal 12. User data streams 62 assigned to the same forward beam 16 are used to form a corresponding forward beam signal 66.

[0038] Multiple forward beam signals 66 are provided to a beamformer 68 included in the ground segment 24. A beamweight generator 70 generates beamforming weights 72, and the beamformer 68 uses the beamforming weights 72 to generate corresponding forward access node signals 74 for transmission as forward uplink signals 28 by the corresponding access nodes 22 cooperating in beamforming. The forward access node signals 74 are synchronized to support the end-to-end beamforming process.

[0039] Beamforming weight 72 is based on the end-to-end channel determined between each access node 22 and the RUT associated with each forward beam 16. That is, beamforming weight 72 takes into account the end-to-end channel from each access node 22 to each RUT, including the uplink channel from each access node 22 to each of the feed 30s in the feed link array 32, the multipath channel through the satellite 26, and the downlink channel from each of the feed 42s in the user link feed array 44 to the RUT.

[0040] As a detailed example based on the presence of M access nodes 22 and K forward beams 16, beamformer 68 replicates each of the K forward beam signals 66 into M sets of K forward beam signals 66. Beamformer 68 includes forward weighting and summing modules (not shown) for each of the M access nodes, and each such module receives one set from the M sets of K forward beam signals 66. Beamweight generator 70 generates an M×K forward beamweight matrix based on an estimated channel matrix for the end-to-end forward gain for each of the K×M end-to-end forward multipath channels.

[0041] The first weighted summation module within the beamformer 68 applies weights equal to the values ​​of the 1,1 elements of the M×K forward beamweight matrix to the first of the K forward beam signals 66. Weights equal to the values ​​of the 1,2 elements of the M×K forward beamweight matrix are applied to the second of the K forward beam signals 66. The other weights of this matrix are applied similarly to the Kth forward beam signal 66, which is weighted with values ​​equal to the 1,K elements of the M×K forward beamweight matrix. Then, each of the K weighted forward beam signals 66 is summed, and the result is output from the first weighted summation module as... Figure 1 The corresponding one of the forward access node signals 74 described herein. The forward access node signal 74 output by the first weighted summation module can be time-adjusted for synchronization of transmissions across multiple access nodes 22. Similarly, each of the other weighted summation modules (not shown) in the beamformer 68 receives a corresponding set of its replicated K forward beam signals 66 and performs a weighted summation of that set using corresponding elements of the M×K forward beam weight matrix. As part of forming / providing the forward access node signal 74, the outputs from each of the M weighted summation modules can be adjusted for timing (e.g., delays and jitter).

[0042] Because beam weighting is applied at ground segment 24 by beamformer 68, the forward uplink signal 28 transmitted from access node 22 to / through satellite 26 forms a forward beam 16. Satellite 26 acts as an end-to-end relay in this beamforming context. The size and location of the formed forward beam 16 can be related to the number of access nodes 22 deployed, the number and antenna pattern of relay antenna elements (feeds 30 and 42) through which the signal passes, the location of satellite 26, and / or the geographical spacing of access nodes 22.

[0043] Figure 2 Beamforming in the return direction (i.e., from user terminal 12 toward access node 22) is shown. The return user beam (not shown) is digitally formed within ground segment 24 rather than in free space. Return beamforming provides isolation or interference reduction between uplink signals transmitted by user terminals 12 located in adjacent beam coverage areas 20.

[0044] Consider the example scenario where user terminal 12-1 in beam coverage area 20-1 of the first user coverage area 14-1 transmits uplink signal 80-1, for example, an uplink signal containing user data destined for one or more external networks 60. Simultaneously, user terminal 12-3 in the adjacent beam coverage area 20-3 within the first user coverage area 14-1 transmits uplink signal 80-3. Similarly, user terminal 12-2 in beam coverage area 20-2 of the second user coverage area 14-2 transmits uplink signal 80-2, for example, an uplink signal containing user data destined for one or more external networks 60. Simultaneously, user terminal 12-4 in the adjacent beam coverage area 20-4 within the overall second user coverage area 14-2 transmits uplink signal 80-4. Beamforming in the return direction reduces interference between such signals, which facilitates frequency reuse on the corresponding beam coverage area 20.

[0045] To understand return beamforming, consider that each feed 84 in the first subscriber link feed array 86-1 receives a superimposed signal 82, which is a unique superposition of the uplink signal 80 transmitted by the subscriber terminal 12 in the corresponding subscriber coverage area 14-1. Similarly, each feed 84 in the second subscriber link feed array 86-2 receives a superimposed signal 82, which is a unique superposition of the uplink signal 80 transmitted by the subscriber terminal 12 in the corresponding subscriber coverage area 14-2. This also applies to the corresponding additional subscriber coverage area 14, provided that another subscriber coverage area 14 exists.

[0046] Each feed 82 outputs a composite return uplink signal 90, which is switched by switching circuitry 88 to a corresponding transponder 92. Similar to beamforming in the forward direction, the number of transponders 92 allocated to the first user link feed array 86-1 and the number of transponders 92 allocated to the second user link feed array 86-2 determines how many return beams are allocated to the first user coverage area 14-1 and the second user coverage area 14-2. In one or more embodiments, the configuration and allocation of the return beams (not shown) are matched to the configuration and allocation of the forward beams 16.

[0047] Each transponder 92 outputs a return composite return downlink signal 94 transmitted from the corresponding feed 96 in the feed link antenna subsystem 98. The transmission pattern of each return composite return downlink signal 94 is shown in the figure as a transmitted signal 100. Correspondingly, each access node 22 receives a superimposed signal 102, which is a unique superposition of the transmitted signal 100, and provides a corresponding return composite signal 104 to the beamformer 68. The return composite signals 104 can be time-synchronized for coherence, and the beamformer 68 applies beamforming weights 108 to shape a return beam represented by the return beam signal 106 in the digital domain.

[0048] Beamforming weights 108 include a K×M return beamweight matrix based on information stored in a channel data storage area, which is filled by a channel estimator implemented in or associated with beamformer 68. The derivation of beamforming weights 108 in beamweight generator 70 relies on channel estimation, such as end-to-end channel estimation based on return link signals transmitted from the RUT in the corresponding user coverage area 14. These return link end-to-end channel estimates take into account the multipath return link channels between each RUT and each access node 22.

[0049] For return beamforming, beamformer 68 has a beam weight input through which it receives the return beam weight matrix—beamforming weights 108—from beam weight generator 70. Each of the return composite signals 104 is coupled to one of the M splitters and weighting modules (not shown) within beamformer 68.

[0050] Each splitter and weighting module splits the time-aligned return composite signal 104 into K copies. Each splitter and weighting module weights each of the K copies using the k,m elements of a K×M return beam weighting matrix. The set of each of the K weighted composite return signals is then coupled to a combining module (not shown), which combines the k-th weighted composite return signal output from each splitter and weighting module to output the k-th return beam signal 106. Each of the K return beam signals 106 includes a sample of communication signals from all user terminals 12 active in the corresponding beam coverage area.

[0051] Considering the details of the above example, the satellite communication system 10 includes a satellite 26 for providing communication between a plurality of access nodes 22 and a plurality of user terminals 12. The plurality of access nodes 22 are geographically distributed within corresponding access node areas, and the plurality of user terminals 12 are geographically distributed within a first user coverage area 14-1 and a second user coverage area 14-2. In other words, some of the user terminals 12 are located within the first user coverage area 14-1, and some of the user terminals 12 are located within the second user coverage area 14-2.

[0052] When mounted on satellite 26, the feed link array 32 can be referred to as feed link antenna subsystem 32, wherein the feed source 30 is referred to as multiple feed link components 30 of feed link antenna subsystem 32. Each feed link component 30 is configured to illuminate the access node region to receive a unique superposition of multiple forward uplink signals 28 from multiple access nodes 22 as a composite input forward signal 34.

[0053] Transponder 38 may be referred to as forward signal path 38, and satellite 26 provides multiple forward signal paths 38. Each of the multiple forward signal paths 38 has a corresponding input coupled to a corresponding one of the multiple feed link components 30 to obtain a corresponding one of the multiple composite input forward signals 34 as a received composite input forward input signal 36. Each forward signal path 38 correspondingly provides a corresponding one of the multiple forward composite downlink signals 40 at a corresponding output.

[0054] The first user link array 44-1 of satellite 26 can be referred to as the first user link antenna subsystem 44-1, and the feed 42 of the first user link antenna subsystem 44-1 can be referred to as the first user link component 42, and they are configured to illuminate the first user coverage area 14-1. Similarly, the second user link array 44-2 of satellite 26 can be referred to as the second user link antenna subsystem 44-2, and the feed 42 of the second user link antenna subsystem 44-2 can be referred to as the second user link component 42, which is configured to illuminate the second user coverage area 14-2. The second user coverage area 14-2 does not overlap with the first user coverage area 14-1.

[0055] The switching circuit system 48 may include a switch matrix with fully cross-switching connectivity between any switch matrix input and any switch matrix output, and may be referred to as the selector subsystem 48. The selector subsystem 48 may be reconfigured in response to control signals to dynamically allocate multiple forward signal paths 38 between the first subscriber link antenna subsystem 44-1 and the second subscriber link antenna subsystem 44-2. Specifically, in a first configuration of the selector subsystem 48, the corresponding outputs of a first subset of the multiple forward signal paths 38 are selectively coupled to corresponding first subscriber link components in a first subset of the multiple first subscriber link components 42, and the corresponding outputs of a second subset of the multiple forward signal paths 38 are selectively coupled to corresponding second subscriber link components in a first subset of the multiple second subscriber link components 42.

[0056] In a second configuration of the selector subsystem 48, a third subset of the plurality of forward signal paths 38 has a corresponding output coupled to a corresponding first user link component in a second subset of the plurality of first user link components 42, and a fourth subset of the plurality of forward signal paths 38 has a corresponding output coupled to a corresponding second user link component in a second subset of the second user link components 42. A first subset of the first user link components 42 is a first number of first user link components 42, a second subset of the first user link components 42 is a second number of first user link components 42, and the first number is different from the second number. A first subset of the second user link components 42 is a third number of second user link components 42, a second subset of the second user link components 42 is a fourth number of second user link components 42, and the third number is different from the fourth number. In at least one embodiment, the sum of the first and second numbers is equal to the sum of the third and fourth numbers.

[0057] The first configuration of the selector subsystem 48 defines a first capacity allocation between a first user coverage area 14-1 and a second user coverage area 14-2. The second configuration of the selector subsystem 48 defines a second capacity allocation between the first user coverage area 14-1 and the second user coverage area 14-2, wherein the second capacity allocation differs from the first capacity allocation. The first configuration corresponds to a first beamweight matrix, and the second configuration corresponds to a second beamweight matrix that is different from the first beamweight matrix. (Reference) Figure 1 The beamforming weights 72 depicted in the diagram may exist as different sets of beamforming weights 72 corresponding to different capacity allocations between the first user coverage area 14-1 and the second user coverage area 14-2—different beamforming matrices.

[0058] A first subset of the plurality of first user link components 42 is configured to transmit a first subset of a plurality of forward composite downlink signals 40 generated by a first subset of a plurality of forward signal paths 38, as a transmitted forward composite downlink signal 46. The transmitted first subset of the plurality of forward composite downlink signals 40 is superimposed to facilitate the formation of a first user beam—a first forward beam 16—in the first user coverage area 14-1. A second subset of the plurality of second user link components 42 is configured to transmit a second subset of a plurality of forward composite downlink signals 40 generated by a second subset of a plurality of forward signal paths 38. The transmitted second subset of the plurality of forward composite downlink signals 40 is superimposed to facilitate the formation of a second user beam—a second forward beam 16—in the second user coverage area 14-2.

[0059] Each of the plurality of forward uplink signals 28 facilitates the formation of both a first user beam and a second user beam. The first user beam corresponds to a first user data stream 62 for a first subset of the plurality of user terminals 12 within a first user coverage area 14-1. Similarly, the second user beam corresponds to a first user data stream 62 for a second subset of the plurality of user terminals 12 within a second user coverage area 14-2.

[0060] In one or more embodiments, the selector subsystem 48 includes a plurality of forward link switches coupled to the outputs of a plurality of forward signal paths 38. Each of the plurality of forward link switches is responsive to a control signal applied to the selector subsystem 48 to selectively couple a corresponding output of one of the plurality of forward signal paths 38 to a corresponding one of a plurality of first user link components 42 via a first switch state or to a corresponding one of a plurality of second user link components 42 via a second switch state. Thus, in a first configuration of the selector subsystem 48, a first subset of the plurality of forward link switches coupled to the corresponding outputs of a first subset of the plurality of forward signal paths 38 is in a first switch state, and a second subset of the plurality of forward link switches coupled to the corresponding outputs of a second subset of the plurality of forward signal paths 38 is in a second switch state.

[0061] like Figure 2As shown, satellite 26 also includes multiple return signal paths, as represented by transponders 92 shown in the figure. Each of the multiple return signal paths 92 has a corresponding output coupled to a corresponding feed 96 in the feed link antenna subsystem 98. Switching circuitry 88 responds to control signals from control circuitry 50 to control the connectivity between feeds 84 in the first user link array 86-1 and the second user link array 86-2 and feeds 96 in the feed link antenna subsystem 98. For example, in a first configuration of selector subsystem 88, selector subsystem 88 controls the connectivity between the inputs of transponders 92 and feeds 84 in the first user link array 86-1 and the second user link array 86-2, such that a subset of feeds 84 in the first user link array 86-1 is coupled to the corresponding feeds 96 in the feed link antenna subsystem 98 to support return beamforming relative to the first user coverage area 14-1. Furthermore, a second subset of the feed 84 in the second user link array 86-2 is coupled to a corresponding feed 96 in the feed link antenna subsystem 98 to support return beamforming relative to the second user coverage area 14-2.

[0062] The foregoing can be understood as allocating the first and second subsets of transponders 92 to the first user coverage area 14-1 and the second user coverage area 14-2, respectively, to control the number of return beams for each such user coverage area 14. For the third user coverage area 14, a third subset of transponders 92 can be allocated.

[0063] Certain components mounted on satellite 26 may be shared between forward link communication and return link communication; for example, any reflectors included in the respective antenna subsystems may be shared. In one or more embodiments, the antenna feed may be shared. However, in at least one embodiment, transponder 92 is partially or completely different from transponder 38.

[0064] The objects of interest in ground segment 24 include beamformers, which in Figure 1 and Figure 2 Depicted as beamformer 68. In fact, beamformer 68 may include a forward beamformer and a return beamformer. For forward beamforming, beamformer 68 has a forward beam signal input—see [link to documentation]. Figure 1 The forward beam signal 66 is fed into the beamformer 68. Furthermore, the beamformer 68 has multiple end-to-end beamweighted forward uplink signal outputs that communicate with multiple access nodes 22—see [link to relevant documentation]. Figure 1The forward access node signal 74 is shown in the image. The end-to-end beamweighted forward uplink signal output corresponds to the respective weights of the forward beam signal input based on a set of end-to-end forward beamweights provided by the beamweight generator 70. In one or more embodiments, multiple access nodes 22 pre-calibrate multiple forward uplink signals 74 to compensate for corresponding path delays and phase offsets introduced between the multiple access nodes 22 and the satellite 26.

[0065] In at least one embodiment, the selector subsystem 48 dynamically allocates a plurality of forward signal paths 38 between the first user link antenna subsystem 44-1 and the second user link antenna subsystem 44-2 in order to dynamically allocate capacity between the first user coverage area 14-1 and the second user coverage area 14-2.

[0066] Figure 3 An example implementation of satellite 26 is depicted, wherein satellite 26 includes transponders 38 configured as forward / return signal paths, some or all of which are dynamically allocated between a first user coverage area 14-1 and a second user coverage area 14-2, for example, based on the capacity requirements of user terminals 12 operating in the respective user coverage areas 14-1 and 14-2. Satellite 26 includes a first user link antenna subsystem 44-1 operable to serve user terminals 12 in the first user coverage area 14-1 in both forward and return directions (i.e., transmit and receive). Further, satellite 26 includes a second user link antenna subsystem 44-2 operable to serve user terminals 12 in the second user coverage area 14-2 in both forward and return directions. Even further, satellite 26 includes a feeder link antenna subsystem 32 operable to communicate (transmit and receive) with a plurality of access nodes 22 in access node area 120. The respective areas 14-1, 14-2, and 120 do not overlap.

[0067] Figure 4 Example details regarding forward and return signal paths are shown in an example configuration where satellite 26 supports simultaneous beamforming relative to three user coverage areas 14-1, 14-2, and 14-3. First user link antenna subsystem 44-1 supports beamforming relative to the first user coverage area 14-1, second user link antenna subsystem 44-2 supports beamforming relative to the second user coverage area 14-2, and third user link antenna subsystem 44-3 supports beamforming relative to the third user coverage area 14-3.

[0068] A key terminology point to note is that the connection circuitry between the input of the forward signal path or transponder 38 and the corresponding feed 30 in the feed link antenna subsystem 32 can be referred to as the forward receive path 400. Similarly, the connection circuitry between the output of the forward signal path or transponder 38 and the corresponding feed 42 in the first user link antenna subsystem 14-1, the second user link antenna subsystem 14-2, and the third user link antenna subsystem 14-3 can be referred to as forward transmit paths 404-1, 404-2, and 404-3. Such circuitry can be part of or coupled to the selector circuitry included in the selector subsystem 48. In other words, the various forward receive paths in the forward receive path 400 and / or the various forward transmit paths in the forward transmit paths 404-1, 404-2, and 404-3 can be switched to control whether a transponder 38 is coupled to the feed 42 in the first user link antenna subsystem 14-1, the feed 42 in the second user link antenna subsystem 14-2, or the feed 42 in the third user link antenna subsystem 14-3. It should also be noted that the forward signal path or transponder 38 may include a radio frequency conversion stack (RFCS) group.

[0069] In at least one embodiment, a first subset of transponders 38 is dedicated to a first subscriber link antenna subsystem 44-1 for beamforming relative to a first subscriber coverage area 14-1; a second subset of transponders 38 is dedicated to a second subscriber link antenna subsystem 44-2 for beamforming relative to a second subscriber coverage area 14-2; and a third subset of transponders 38 is dedicated to a third subscriber link antenna subsystem 44-3 for beamforming relative to a third subscriber coverage area 14-3. Each transponder 38 or a group of transponders in another subset of transponders 38 can be allocated to any one of the three subscriber coverage areas 14-1, 14-2, and 14-3 according to the corresponding capacity requirements in the respective subscriber coverage area 14.

[0070] In at least one embodiment, some or all of the transponders 38 may be allocated to any one of the user coverage areas 14 or to a corresponding user coverage area 14 in any desired proportion. As previously noted, there is a trade-off between the allocatability and complexity and weight of the selector subsystem 48, which includes, for example, switches or splitters disposed in corresponding ones of forward receive path 400 and / or forward transmit paths 404-1, 404-2, and 404-3 to control which transponder inputs are switched to which feeds 30 or which transponder outputs are switched to which feeds 42. Thus, although the figure depicts the selector subsystem 48 as a self-contained entity, it may include a distributed set of switches or a switch matrix or a set of splitters that control signal path connectivity within satellite 26 in response to control signals from control circuitry system 50.

[0071] In at least one embodiment, the output of each of the transponders 38, or a subset thereof, can be selectively connected to a feed 42 in any one of the user link antenna subsystems 44. For a dual-polarized feed 42, the selector subsystem 48 can also control which feed port the transponder output is connected to.

[0072] In the example, satellite 26 has N transponders 38 (e.g., the number may be equal to the number of forward receive paths 400), and selector subsystem 48 has N·2 switching outputs, each of which is selectively coupled to a forward transmit path in forward transmit paths 404-1, 404-2, and 404-3. That is, the number of forward transmit paths 404-1, 404-2, and 404-3 may be equal to N·2. For example, forward transmit path 404-1 may include P_1 transmit paths, forward transmit path 404-2 may include P_2 transmit paths, and forward transmit path 404-3 may include P_3 transmit paths, where P_1 + P_2 + P_3 = N·2.

[0073] In some embodiments, the number of forward transmit paths coupled to the respective antenna subsystems may be the same. For example, satellite 26 may have P_1 transmit paths 404-1 coupled to the feed 42 of the first user link antenna subsystem 44-1 and P_2 transmit paths 404-2 coupled to the feed 42 of the second user link antenna subsystem 44-2, and P_1 may be equal to P_2. However, the number of transmit paths coupled to the respective antenna subsystems may be different. For example, satellite 26 may have P_3 forward transmit paths 404-3 coupled to the feed 42 of the third user link antenna subsystem 44-3, and P_3 may not be equal to P_1 or P_2 (e.g., P_3 may be less than P_1 and P_2 in the following cases). In at least one embodiment, the output of one or more of the transponders 38 has a switch for selectively switching the transponder output to one of the selected forward transmit paths 404. Such a switcher can be considered as part of the selector subsystem 48, or as part of the corresponding forward transmission path and operated under the control of the selector subsystem 48.

[0074] In some examples, each of the forward transmit paths pointing to the antenna subsystem can be coupled to a feed source of the same polarization. For example, each of forward transmit paths 404-1, 404-2, and 404-3 can be coupled to a port of a feed source with a single polarization (e.g., RHCP or LHCP). Alternatively, for some antenna subsystems, the forward transmit paths can be coupled to ports of feed sources with more than one polarization.

[0075] In an example considering only two subscriber link antenna subsystems 44-1 and 44-2, forward transmit paths 404-1 and 404-2 can be port-coupled with multi-polarized feeds. For example, a first set (e.g., half or P_1 / 2) of feeds in forward transmit path 404-1 can be coupled to feed 42 of the first subscriber link antenna subsystem 44-1 with a first polarization (e.g., LHCP), and a second set (e.g., half or P_1 / 2) of feeds in forward transmit path 404-2 can be coupled to feed 42 of the first subscriber link antenna subsystem 44-1 with a second polarization (e.g., RHCP). Similarly, the first set (e.g., half or P_2 / 2) of feeds 42 of the forward transmit path 404-2 can be coupled to the feed 42 of the second user link antenna subsystem 42-2 of the first polarization (e.g., LHCP), and the second set (e.g., half or P_2 / 2) of feeds of the transmit path 42-2 can be coupled to the feed 42 of the second user link antenna subsystem 44-2 of the second polarization (e.g., RHCP).

[0076] Considering the example context of satellite 26 carrying three user link antenna subsystems 44-1, 44-2, and 44-3, the individual switches of selector subsystem 48 can be independently configurable (e.g., according to a configuration that can be sent to satellite 26 via control signaling from ground segment 24). Therefore, of the N transponders 38, S of the N transponders 38 can selectively switch to S of the forward transmission path 404-1, L of the N transponders 38 can selectively switch to L of the transmission path 404-2, and T of the N transponders 38 can selectively switch to T of the transmission path 404-3. Here, S is between zero (0) and P_1, L is between zero (0) and P_2, and T is between zero (0) and P_3.

[0077] In some examples, the number of transmit feeds for each of the antennas selected using the selector subsystem 48 can be determined based on the service capacity associated with each of the respective user coverage areas 14. For example, if a relatively high capacity is desired in the first user coverage area 14-1 illuminated by the first user link antenna subsystem 44-1, more transmit paths in forward transmit path 404-1 can be selected or activated, while relatively fewer forward transmit paths in forward transmit paths 404-2 and 404-3 can be selected or activated.

[0078] Alternatively or additionally, the selection of transmission paths within the group or set of selected forward transmission paths 404-1, 404-2, and 404-3 may depend on the beamforming configuration used to provide communication services via the respective user coverage areas 14-1, 14-2, and 14-3. For example, a corresponding beamforming configuration can be determined for providing services to each of the user coverage areas 14, and combinations of specific feeds 30 and corresponding transponders 38 selectively associated with transmission paths 404-1, 404-2, and 404-3 can be analyzed to determine the arrangement of feeds 30 that enhances or optimizes the beamforming configuration (e.g., providing higher signal gain for the desired beamforming configuration while reducing or minimizing the amount of parasitic or undesirable signal power in areas outside the desired beamforming configuration).

[0079] In other words, satellite 26 or system 10 determines, in general, which specific feeds in feed 30 are associated with their counterparts in user link antenna subsystem 14, rather than simply determining how many transponders 38 to allocate to the corresponding user coverage areas 14-1. Certain feed allocation patterns can exist to improve beamforming performance. In some examples, the capacity requirement for the antenna across a given illumination area may be uneven, and therefore the beamforming configuration and the selection of transmit paths can depend on the capacity requirement within a region of the illumination area. For example, if more capacity is needed in a part of the illumination area, more feeds directed to that region can be selected compared to other parts of the illumination area to enhance the capacity in that region. Thus, the feed pattern used for beamforming relative to a specific user coverage area can be based on the distribution of user terminals 12 or the required capacity within the user coverage area.

[0080] In some examples, satellite 26 can be operated according to various configurations of the forward receive path 400 pointing to forward transmit paths 404-1, 404-2, and 404-3 and the transponder 38. For example, in a first configuration, a first subset of transponders 38 may have outputs coupled to a corresponding feed 42 of the first subscriber link antenna subsystem 44-1 (e.g., via selector subsystem 48), and a second subset of transponders 38 may have outputs coupled to a corresponding feed 42 of the second subscriber link antenna subsystem 44-2 (e.g., via selector subsystem 48). Ground segment 24 may apply one or more sets of end-to-end beam weights to the forward uplink signal 28 while operating satellite 26 in the first configuration to provide one or more sets of forward beams 16 associated with the first subscriber link antenna subsystem 44-1, the second subscriber link antenna subsystem 44-2, and the third subscriber link antenna subsystem 44-3.

[0081] In the second configuration, a third subset of transponders 38 may have an output coupled to a corresponding feed 42 of the first subscriber link antenna subsystem 44-1 (e.g., via selector subsystem 48), and a fourth subset of transponders 38 may have an output coupled to a corresponding feed 42 of the second subscriber link antenna subsystem 44-2 (e.g., via selector subsystem 48). Similarly, the terrestrial network 24 may apply one or more sets of end-to-end beam weights to the forward uplink signal 28 while operating satellite 26 in the second configuration to provide one or more sets of forward link subscriber beams associated with the first subscriber link antenna subsystem 44-1, the second subscriber link antenna subsystem 44-2, or the third subscriber link antenna 44-3. In some cases, the sum of the number of transponders 38 in the first and second subsets of transponders 38 may be equal to the sum of the number of transponders in the third and fourth subsets of transponders 38.

[0082] In some cases, the configuration of transponder 38 can be associated with a single polarization for each antenna. For example, for a first configuration, a first subset of transponders can be selected from transponder 38 that is port-coupled (e.g., via selector subsystem 48) to a feed 42 associated with a first polarization in the first subscriber link antenna subsystem 44-1. Similarly, for the first configuration, a second subset of transponders can be selected from transponder 38 that is port-coupled (e.g., via selector subsystem 48) to a feed 42 associated with a first polarization in the second subscriber link antenna subsystem 44-2. Alternatively, for the first configuration, a second subset of transponders can be selected from transponder 38 that is port-coupled (e.g., via selector subsystem 48) to a corresponding feed 42 associated with a second polarization in the second subscriber link antenna subsystem 44-2.

[0083] In some cases, the configuration of transponder 38 can be associated with more than one polarization for at least one antenna. For example, for a first configuration, a first subset of transponders 38 may include transponders coupled (e.g., via selector subsystem 48) to corresponding feeds associated with the first and second polarizations of the first antenna. Similarly, for a second configuration, a second subset of transponders 38 may include transponders coupled (e.g., via selector subsystem 48) to corresponding feeds associated with the first and second polarizations of the second antenna. Furthermore, although shown and described with selector subsystem 48, selector subsystem 48 may include signal divider elements instead of a subset or all of the described switchers. Thus, the output of at least one subset of transponders 38 can be divided to concurrently provide to more than one feed for more than one antenna.

[0084] Figure 4Example details of the return signal path or transponder 92 providing signal flow in the return direction in satellite 26 are also shown. Return receive paths 410-1, 410-2, and 410-3 couple feeds 84 in the respective user link antenna subsystems 86-1, 86-2, and 86-3 to the input of transponder 92. The output of transponder 92 is coupled to a corresponding feed 96 in the feed link antenna subsystem 98. As noted, at least some of the antenna-related elements mounted on satellite 26 can be shared for forward and return communication; for example, the same reflectors can be used in the antenna subsystems used in the forward and return link directions.

[0085] The switching circuitry 88 operates as a selector subsystem that controls the connectivity between feed 84 in the user link antenna subsystem 86 and feed 96 in the feed link antenna subsystem 98 based on a currently configured capacity allocation, which can be updated on a scheduling or command basis. Switching on a per-feed / per-path basis can be individually controlled, as described above for the forward direction, and the same-polarization-based connectivity described for the forward direction can be applied to the return direction. Therefore, there can be N return transmit paths 412 coupling the return signal path or transponder 92 to the corresponding feed 96 in the feed link antenna subsystem 98, and N or fewer paths can exist in each of the return receive paths 410-1, 410-2, and 410-3. The selector subsystem 88 includes or controls a switcher or splitter that controls the connectivity between the return signal path or repeater 92 and the return receiving paths 410-1, 410-2, and 410-3, meaning that the number and / or pattern of feeds 96 for serving each of the user coverage areas 14-1, 14-2, and 14-3 in the return direction can be dynamically controlled according to capacity requirements or other considerations.

[0086] Figure 5 An example forward signal path 500, also referred to as a forward link transponder 500, is shown. According to various aspects of this disclosure, a satellite 26 carrying multiple such forward signal paths 500 supports end-to-end beamforming with simultaneous user coverage of multiple areas. The forward signal path 500 is an example implementation of any of the transponders 38 discussed above.

[0087] Example forward signal path 500 traverses from feed 532 to one of feed 512 or feed 522. Feed 532 is one of a plurality of feeds 530 corresponding to feeds 30 in feed link antenna subsystem 32. Feed 512 is one of a first plurality of feeds 510 and corresponds to feed 42 in first subscriber link antenna subsystem 44-1. Feed 522 is one of a second plurality of feeds 520 and corresponds to feed 42 in second subscriber link antenna subsystem 44-2.

[0088] The connection between the input of the forward signal path 500 and the feed source 532 can be considered as Figure 4 One of the forward receiving paths 400 shown in the figure. Similarly, the switching connection from the output of the forward signal path 500 to the feed 512 can be regarded as one of the forward transmitting paths 404-1, and the switching connection from the output of the forward signal path 500 to the feed 522 can be regarded as one of the forward transmitting paths 404-2.

[0089] Feeds 510 and 520 are used to transmit forward downlink signals to user terminals 12 in user coverage areas 14-1 and 14-2, and feed 530 is used to receive forward uplink signals from multiple access nodes 22. Therefore, by controlling which of feeds 512 or 522 is coupled to the output of the forward signal path 500, the forward signal path 500 can be assigned to either the first user coverage area 14-1 or the second user coverage area 14-2. This connectivity is controlled by a switch 556 included in the selector subsystem 544. Feeds 532, 512, and 522 can be polarized (one or both of LHCP and RHCP), and the selector subsystem 544 can include connectivity control for selected one or more polarizations from / to feeds 532, 512, and 522.

[0090] The forward signal path 500 has an LNA 541 that forms the input of the forward signal path 500. The forward signal path 500 further includes a frequency converter and associated filter 542, a channel amplifier 543, a phase shifter 545, a power amplifier 546 (e.g., a traveling wave tube amplifier (TWTA), a solid-state power amplifier (SSPA), etc.), and a harmonic filter 547. Some implementations may have more or fewer components. For example, the frequency converter and associated filter 542 can be useful when the uplink and downlink frequencies are different. As an example, each forward signal path 500 may accept input in a first frequency range and output in a second frequency range.

[0091] In one or more embodiments, the forward signal path 500 can be coupled to any polarization combination, and different sets of forward signal paths 500 mounted on satellite 26 can be coupled to different polarizations. For example, a first set of forward signal paths 500 may have inputs coupled to ports of feed 532 of a first polarization (e.g., RHCP) and outputs selectively coupled (e.g., via switch 556) to ports of feed 512, 522 of the same polarization. A second set of forward signal paths 500 may have inputs coupled to ports of feed 532 associated with a first polarization (e.g., RHCP) and outputs coupled (e.g., via switch 556) to ports of feed 512, 522 associated with different polarizations (e.g., LHCP).

[0092] In some cases, satellite 26 may carry more than two sets of forward signal paths 500. For example, multiple forward signal paths 500 may couple their inputs to a port of a first polarization (e.g., RHCP), and different groups may have different polarization assignments to the ports of feed 512 and 522. For example, various configurations for each group include two groups, three groups, or four groups, where each group has a different set of polarizations (e.g., {RHCP,RHCP}, {RHCP,LHCP}, {LHCP,RHCP}, or {LHCP,LHCP}). Furthermore, in the case where switch 556 has more than two outputs, additional configurations for each group are possible, including arbitrary polarization combinations for each set of forward signal paths 500.

[0093] Figure 6 This demonstrates an example return signaling path 600, also known as a return link repeater 600. Return signaling path 600 can be understood as being for... Figure 2 An example implementation of the corresponding transponder 92 is depicted. According to various aspects of this disclosure, satellite 26 carrying multiple such return signal paths 600 supports end-to-end beamforming in the return direction relative to multiple areas simultaneously covered by users.

[0094] Example return signal path 600 couples one of feed 612 or feed 620 to feed 632. Feed 612 is one of a plurality of feeds 610 and corresponds to a given feed 84 included in the first subscriber link antenna subsystem 86-1. Feed 622 is one of a plurality of feeds 610 and corresponds to a given feed 84 included in the second subscriber link antenna subsystem 86-2. Feed 632 is one of a plurality of feeds 630 and corresponds to a given feed 96 included in the feed link antenna subsystem 98. In other words, return signal path 600 can be assigned to either the first subscriber link antenna subsystem 86-1 serving the first subscriber coverage area 14-1 or the second subscriber link antenna subsystem 86-2 serving the second subscriber coverage area 14-2.

[0095] Then, in Figure 6 In this context, feeds 610 and 620 are used to receive return uplink signals from user terminals 12 in user coverage areas 14-1 and 14-2, and feed 630 is used to transmit return downlink signals to multiple access nodes 22. By controlling which of feeds 612 or 622 is coupled to the input of the illustrated return link repeater 640, the return signal path 600 can be assigned to either the first user coverage area 14-1 or the second user coverage area 14-2. This connectivity is controlled by switcher 656. Although shown as part of the return signal path 600, switcher 656 can be considered as part of the selector subsystem 644, for example, as... Figure 2 It is part of the switching circuit system 88 introduced in the middle.

[0096] Feeds 612 and 622 may be polarized and may provide one or both of LHCP or RHCP, and the selector subsystem 644 may include connectivity control for one or more polarizations selected from feeds 612 and 622, for example, along the lines described above for the forward signal path 500. The return link transponder 600 includes a frequency conversion and filtering circuitry system 642, a channel amplifier 643, a phase shifter 645, a power amplifier 646 (e.g., a traveling wave tube amplifier (TWTA), a solid-state power amplifier (SSPA), etc.), and a harmonic filter 647. Some implementations may have more or fewer components. For example, the frequency converter and associated filter 642 may be useful when the uplink and downlink frequencies are different. As an example, each return link transponder 600 may accept input in a first frequency range and output in a second frequency range.

[0097] Return to reference Figure 4The connectivity between the input of the return link repeater 600 and the feeds 612 and 622 can be understood as the corresponding return receive paths in return receive paths 410-1 and 410-2. Similarly, the connectivity between the output of the return link repeater 600 and the feed 632 can be understood as one of the return transmit paths 612.

[0098] Figure 7 This is a block diagram of an end-to-end communication processor 705 supporting end-to-end beamforming with simultaneous user coverage of multiple areas, according to various aspects of this disclosure. The end-to-end communication processor 705 may include a beam signal interface 710, an end-to-end beamforming processor 720, an end-to-end relay configuration manager 730, and an end-to-end beamforming matrix generator 740. Each of these modules may communicate directly or indirectly with each other (e.g., via one or more buses). The end-to-end communication processor 705 may demonstrate... Figure 1 The network device 64 described in the text.

[0099] The end-to-end communication processor 705 can be configured to provide communication between an access node cluster and multiple user terminals 12 via a satellite 26 that acts as an end-to-end relay including multiple receive / transmit signal paths. The access node cluster can include multiple access nodes 22 geographically distributed within an access node area 120. The multiple user terminals 12 can be geographically distributed across a first user coverage area 14-1 illuminated by a first user link antenna subsystem 44-1 of the satellite 26 and a second user coverage area 14-2 illuminated by a second user link antenna subsystem 44-2 of the satellite 26. The satellite 26 has multiple forward signal paths, such as forward signal paths 500, wherein at least some of the forward signal paths 500 can be dynamically assigned to either the first user coverage area 14-1 or the second user coverage area 14-2, for example, to control how many of the K forward beams 16 are assigned to the first user coverage area 14-1 and how many of the K forward beams 16 are assigned to the second user coverage area 14-2. Of course, there can be three or more user coverage areas 14, and beam distribution control can be performed across three or more user coverage areas 14.

[0100] For forward link communication, the beam signal interface 710 can receive a forward link beam signal 715 (in which the forward link user data stream 62 is transmitted to the user terminal 12) including the forward link beam signal 715. Figure 1 (Shown as beam signal 66). Beam signal interface 710 can transmit forward link beam signals to end-to-end beamforming processor 720 in beam signaling 725.

[0101] The end-to-end relay configuration manager 730 can manage the configuration of the satellite 26 for end-to-end relay. For example, the end-to-end relay configuration manager 730 can configure the satellite 26 with multiple antennas and multiple receive / transmit signal paths, which can be individually and selectively coupled to one of the multiple antennas for providing communication services to multiple geographic areas in parallel. The end-to-end relay configuration manager 730 can configure the end-to-end relay according to one of a variety of configurations. For example, for a first configuration of the forward link, a first subset of the multiple receive / transmit signal paths of the end-to-end relay can be selectively coupled between a first subset of the feeds of the first antenna and a corresponding feed in the first subset of the feeds of the second antenna, and a second subset of the multiple receive / transmit signal paths of the end-to-end relay can be selectively coupled between a second subset of the feeds of the first antenna and a corresponding feed in the first subset of the feeds of the third antenna. For the second configuration of the forward link, a third subset of the multiple receive / transmit signal paths of the end-to-end relay can be selectively coupled between a third subset of the feed of the first antenna and a corresponding feed in the second subset of the feed of the second antenna, and a fourth subset of the multiple receive / transmit signal paths of the end-to-end relay can be selectively coupled between a fourth subset of the feed of the first antenna and a corresponding feed in the second subset of the feed of the third antenna.

[0102] The end-to-end relay configuration manager 730 can configure the end-to-end relay by sending control signaling 765 to the end-to-end relay of the configuration selector subsystem. The end-to-end relay configuration manager 730 can determine the distribution of multiple receive / transmit signal paths selectively coupled to a first antenna and a second antenna for the end-to-end relay, for example, based at least in part on the relative throughput requirements of the first user coverage area and the second user coverage area. Alternatively or additionally, the end-to-end relay configuration manager 730 can determine the distribution of multiple receive / transmit signal paths selectively coupled to a first antenna and a second antenna for the end-to-end relay, for the first configuration, based at least in part on the throughput capacity of the access node cluster. The end-to-end relay configuration manager 730 can configure the selector subsystem to switch between multiple configurations. For example, the end-to-end relay configuration manager 730 can configure the end-to-end relay in a second configuration in which a third subset of the multiple receive / transmit signal paths of the end-to-end relay is selectively coupled between the ports of the third subset of the feed of the third antenna and the ports of the second subset of the feed of the first antenna, and a fourth subset of the multiple receive / transmit signal paths of the end-to-end relay is selectively coupled between the ports of the fourth subset of the feed of the third antenna and the ports of the second subset of the feed of the second antenna.

[0103] In a first configuration, a first subset of the feed sources of the first antenna can have a first number of feed sources, and a first subset of the feed sources of the second antenna can have a second number of feed sources. In a second configuration, a second subset of the feed sources of the first antenna can have a third number of feed sources, and a second subset of the feed sources of the second antenna can have a fourth number of feed sources. In some examples, the sum of the first number of feed sources and the second number of feed sources is equal to the sum of the third number of feed sources and the fourth number of feed sources. A selector subsystem can be used to select multiple polarization configurations. For example, in the first configuration, each of the first and second antennas can be used to transmit a forward link signal having the same polarization as the signal received via the third antenna. That is, ports of the first subset of the feed sources of the third antenna and ports of the first subset of the feed sources of the second antenna can be associated with the first polarization, and ports of the second subset of the feed sources of the third antenna and ports of the first subset of the feed sources of the second antenna can be associated with the first polarization.

[0104] Alternatively, in the first configuration, one or more of the first antenna or the second antenna can be used to transmit a forward link signal having a different polarization than the signal received via the third antenna. For example, ports of a first subset of the feed of the third antenna and ports of a first subset of the feed of the first antenna can be associated with a first polarization, and ports of a second subset of the feed of the third antenna can be associated with the first polarization, while ports of a first subset of the feed of the second antenna can be associated with a second polarization.

[0105] Similarly, for the second configuration, each of the first and second antennas can be used to transmit a forward link signal with the same polarization as the signal received via the third antenna, or one or more of the first or second antennas can be used to transmit a forward link signal with a different polarization than the signal received via the third antenna. Additionally or alternatively, for either the first or second configuration, either or both of the first or second antennas can be used to transmit a forward link signal with multiple polarizations. For example, for either the first or second configuration, a subset of the receive / transmit signal paths coupled to the first or second antenna can be coupled to the port of the feed of a multi-polarized antenna. Therefore, communication services can be provided using a single polarization on the forward uplink, where each of the antennas illuminating in parallel coverage areas for the forward downlink has one or more polarizations.

[0106] The end-to-end relay configuration manager 730 can also configure a selector subsystem to switch between multiple return link configurations. For example, for a first return link configuration, a third subset of the multiple receive / transmit signal paths of the end-to-end relay can be selectively coupled between ports of a second subset of the feed of the first antenna and ports of a third subset of the feed of the third antenna, and a fourth subset of the multiple receive / transmit signal paths of the end-to-end relay can be selectively coupled between ports of a second subset of the feed of the second antenna and ports of a fourth subset of the feed of the third antenna. One or more additional return link configurations may include inputs to different subsets of the multiple receive / transmit signal paths selectively coupled between different arrangements of the feeds of the first, second, and third antennas of the end-to-end relay.

[0107] In some examples, the end-to-end relay configuration manager 730 may determine the distribution of multiple receive / transmit signal paths selectively coupled to the first and second antennas for the end-to-end relay based at least in part on the relative throughput requirements for the first and second user coverage areas, for a first configuration (e.g., for the forward or return link). In some examples, the end-to-end relay configuration manager 730 may determine the distribution of multiple receive / transmit signal paths selectively coupled to the first and second antennas for the end-to-end relay based at least in part on the throughput capacity of the access node cluster for the first configuration. In some examples, the capacity requirements for antennas across a given illumination area may be non-uniform, and therefore the beamforming configuration and the selection of transmit paths may depend on the capacity requirements within a region of the illumination area. For example, if more capacity is required in a portion of the illumination area, more feeds directed to that region compared to other parts of the illumination area may be selected to enhance the capacity in that region. The end-to-end relay configuration manager 730 may provide the end-to-end beamforming matrix generator 740 with the configuration of the receive / transmit signal paths 735. The configuration of the receive / transmit signal path 735 may include, for example, a first forward link beamweight matrix for a first configuration and a second forward link beamweight matrix for a second configuration.

[0108] The end-to-end beamforming matrix generator 740 can generate a beamforming matrix 745 for communication via forward and return links of an end-to-end relay having multiple antennas illuminating multiple coverage areas in parallel. For example, for a first configuration, the end-to-end beamforming matrix generator 740 can identify a first forward link beamweight matrix for end-to-end beamforming of transmissions from multiple access nodes to multiple user terminals via the end-to-end relay. The end-to-end beamforming matrix generator 740 can identify additional forward link beamweight matrices for the first configuration. For example, the end-to-end beamforming matrix generator 740 can identify a first set of forward link beamweight matrices for the first configuration, and the end-to-end beamforming processor 720 can apply one or more forward link beamweight matrices from the first set of forward link beamweight matrices (e.g., by iterating through at least one subset of the first set of forward link beamweight matrices, or by selecting one or more forward link beamweight matrices from the first set of forward link beamweight matrices based on factors such as requirements within each beam). Furthermore, for the second configuration, the end-to-end beamforming matrix generator 740 can identify a second forward link beamweight matrix for end-to-end beamforming of transmissions from multiple access nodes to multiple user terminals via end-to-end relays. Forward and return link beamforming matrices can be generated based on the configuration determined by the end-to-end relay configuration manager 730 of the receive / transmit signal path 735 (e.g., forward link or return link). The end-to-end beamforming matrix generator 740 can identify additional forward or return link beamweight matrices for the second configuration. For example, the end-to-end beamforming matrix generator 740 can identify a second set of forward link beamweight matrices for a second configuration, and the end-to-end beamforming processor 720 can apply one or more forward link beamweight matrices from the second set of forward link beamweight matrices (e.g., looping through at least one subset of the second set of forward link beamweight matrices, or selecting one or more forward link beamweight matrices from the second set of forward link beamweight matrices based on factors such as requirements within each beam). The end-to-end relay configuration manager 730 can determine additional configurations for multiple receive / transmit signal paths of the end-to-end relay, and the end-to-end beamforming matrix generator 740 can identify additional sets of forward or return link beamweight matrices for additional configurations.

[0109] The end-to-end beamforming processor 720 can receive a beamforming matrix 745 and apply the beamforming matrix 745 to forward and return link signals to obtain or process access node-specific signals 755. For example, the end-to-end beamforming processor 720 can generate a first set of corresponding access node-specific forward link signals for transmission by a plurality of access nodes, each of the corresponding access node-specific forward link signals comprising a composite of corresponding forward link beam signals from at least a subset of the first set of forward link beam signals weighted by corresponding forward beamforming weights according to a first forward link beamweight matrix for a first configuration. The end-to-end beamforming processor 720 can use the same or different beamforming matrices for the first configuration to apply beamforming matrices to the forward and return link signals for a duration of additional time. Furthermore, the end-to-end beamforming processor 720 can generate a second set of corresponding access node-specific forward link beam signals for transmission by multiple access nodes, each of the second set of corresponding access node-specific forward link signals comprising a composite of the corresponding forward link beam signals in the second set of forward link beam signals weighted by corresponding forward link beamforming weights according to a second forward link beam weight matrix for a second configuration.

[0110] Furthermore, the end-to-end beamforming processor 720 can apply a return link beamweight matrix to the corresponding return link signals received at multiple access nodes to obtain corresponding return link data streams associated with first and second subsets of multiple user terminals. The end-to-end beamforming processor 720 can use the same or different beamforming matrices for a second configuration to apply beamforming matrices to the forward and return link signals for a duration of additional time. Each of the corresponding return link signals may include a composite of signals relayed by at least one receive / transmit signal path in a third subset of multiple receive / transmit signal paths relayed end-to-end and at least one receive / transmit signal path in a fourth subset of multiple receive / transmit signal paths relayed end-to-end.

[0111] Figure 8 This is a block diagram of a controller 800 according to an example embodiment. According to various aspects of this disclosure, the controller 800 supports an end-to-end beamforming system with multiple areas simultaneously covered by users. The controller 800 may include an end-to-end communication processor 805, a processor 810, a memory 815, and a communication interface 840. Each of these components may communicate directly or indirectly with each other via one or more buses 835. The controller 800 may be implemented in one of the network devices 64 of ground segment 24, or in satellite 26, or distributed between ground segment 24 and satellite 26.

[0112] Memory 815 may include random access memory (RAM) and / or read-only memory (ROM). Memory 815 may store an operating system (OS) 820 (e.g., built on a Linux or Windows kernel). Memory 815 may also store computer-readable, computer-executable code 825 including instructions configured, when executed, to cause processor 810 to perform the various functions described herein related to providing communication services according to different local antenna patterns. Alternatively, code 825 may not be directly executable by processor 810, but is configured to cause controller 800 (e.g., when compiled and executed) to perform one or more of the functions described herein.

[0113] The controller 800 may include an end-to-end communications processor 805, which can manage one or more aspects of the communications satellite to support end-to-end beamforming with multiple areas of simultaneous user coverage, as described herein. Communications services may be provided, for example, via communications interface 840.

[0114] Controller 800, including an end-to-end communication service processor 805, processor 810, memory 815, and / or communication interface 840 operating as a communication service manager, may be implemented or executed using a general-purpose processor, digital signal processor (DSP), application-specific integrated circuit (ASIC), field-programmable gate array (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. The general-purpose processor may be a microprocessor, but alternatively, the processor may be any conventional processor, controller, microcontroller, or state machine. Controller 800 may also be implemented as a combination of computing devices, such as a DSP and microprocessor, multiple microprocessors, one or more microprocessors combined with a DSP core, integrated memory, discrete memory, or any other combination of such configurations.

[0115] Figure 9 This is a flowchart of an example method 900 supporting end-to-end beamforming with simultaneous user coverage of multiple areas according to various aspects of this disclosure. Operation of method 900 can be implemented by a controller of a communications satellite comprising multiple antennas or components thereof, as described herein. In some instances, the controller can execute a set of instructions for controlling the functional elements of the controller to perform the functions described below. Alternatively or additionally, the controller can use dedicated hardware to perform aspects of the functions described below.

[0116] Method 900 can provide communication between an access node cluster and multiple user terminals via an end-to-end relay comprising multiple receive / transmit signal paths, wherein the access node cluster comprises multiple access nodes geographically distributed within an access node area, the multiple user terminals are geographically distributed in a first user coverage area illuminated by a first antenna and a second user coverage area illuminated by a second antenna, and the multiple receive / transmit signal paths of the end-to-end relay have inputs coupled to a feed of a third antenna illuminating the access node area and outputs that can be individually selected between the first antenna and the second antenna.

[0117] At 905, the controller can obtain a first set of forward link beam signals, including forward link user data streams for transmission to multiple user terminals.

[0118] At 910, for the first configuration, the controller can configure a first subset of multiple receive / transmit signal paths of the end-to-end relay to selectively couple between ports of a first subset of the feed of the third antenna and ports of a first subset of the feed of the first antenna, and configure a second subset of the multiple receive / transmit signal paths of the end-to-end relay to selectively couple between ports of a second subset of the feed of the third antenna and ports of a first subset of the feed of the second antenna. Ports of the first subset of the feed of the third antenna and ports of the first subset of the feed of the second antenna can be associated with a first polarization, and ports of the second subset of the feed of the third antenna and ports of the first subset of the feed of the second antenna can be associated with a first polarization. Alternatively, ports of the first subset of the feed of the third antenna and ports of the first subset of the feed of the first antenna can be associated with a first polarization, and ports of the second subset of the feed of the third antenna can be associated with a first polarization, and ports of the first subset of the feed of the second antenna can be associated with a second polarization.

[0119] The distribution of multiple receive / transmit signal paths selectively coupled to the first and second antennas in the end-to-end relay can be determined at least in part based on the relative throughput requirements of the first and second user coverage areas. The distribution of multiple receive / transmit signal paths selectively coupled to the first and second antennas in the end-to-end relay can also be determined at least in part based on the throughput capacity of the access node cluster for the first configuration.

[0120] At 915, for the first configuration, the controller can identify a first forward link beamweight matrix for end-to-end beamforming of transmissions from multiple access nodes via end-to-end relays to multiple user terminals. The controller can identify an additional forward link beamweight matrix for the first configuration.

[0121] At 920, the controller can generate a first set of corresponding access node-specific forward link signals for transmission by multiple access nodes. Each of the corresponding access node-specific forward link signals includes a composite of corresponding forward link beam signals from at least a subset of the first set of forward link beam signals weighted by corresponding forward beamforming weights according to a first forward link beamweight matrix for a first configuration. The controller can use the first forward link beamweight matrix or an additional forward link beamweight matrix to generate an additional set of corresponding access node-specific forward link signals for an additional time period.

[0122] At point 925, multiple access nodes can transmit a first set of their respective access node-specific forward link signals to an end-to-end relay. The receive / transmit signal path of the end-to-end relay can relay the first set of the respective access node-specific forward link signals to form beams in parallel within the first and second user coverage areas.

[0123] Therefore, method 900 can support end-to-end beamforming with multiple areas simultaneously covered by users. It should be noted that method 900 discusses exemplary embodiments, and the operation of method 900 can be rearranged or otherwise modified to make other embodiments possible. For example, some described operations can be optional (e.g., operations enclosed by dashed boxes, operations described as optional, etc.), wherein optional operations can be performed when certain criteria are met, performed based on configuration, omitted intermittently, omitted completely, etc.

[0124] The various illustrative blocks and components described herein can be implemented or executed using a general-purpose processor, DSP, ASIC, FPGA or other programmable logic device, discrete gate or transistor logic, discrete hardware component, or any combination thereof designed to perform the functions described herein. The general-purpose processor may be a microprocessor, but alternatively, the processor may be any conventional processor, controller, microcontroller, or state machine. The processor may also be implemented as a combination of computing devices, such as a DSP and a microprocessor, multiple microprocessors, a microprocessor combined with a DSP core, or any other combination of such configurations.

[0125] The detailed description above, taken in conjunction with the accompanying drawings, describes exemplary embodiments and does not represent only embodiments that can be practiced within the scope of the claims or are within the scope of the claims. Throughout this specification, the term "example" means "serving as an example," "instance," or "illustration," and not "preferred" or "superior to other embodiments." The detailed description includes specific details to provide an understanding of the described techniques. However, these techniques can be practiced without these specific details. In some instances, well-known structures and apparatuses are shown in block diagram form to avoid obscuring the concepts of the described embodiments.

[0126] The information and signals described herein can be represented using any of a variety of different techniques and skills. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout the above description can be represented by voltage, current, electromagnetic waves, magnetic fields or magnetic particles, light fields or light particles, or any combination thereof.

[0127] The function described herein can be implemented in various ways, with different materials, features, shapes, sizes, etc. Other examples and embodiments are within the scope of this disclosure and the appended claims. Features implementing the function can also be physically located in various places, including distributed such that the parts of the function are implemented in different physical locations. Moreover, as used herein, the word "or" used in the list of items contained in the claims (e.g., a list of items beginning with phrases such as "at least one of" or "one or more of") indicates a disjoint list, such that a list such as "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).

[0128] As used herein, when referring to electrical signal paths or nodes, the term “coupled” means an electrical connection, whether direct or indirect. Additionally, when referring to electrical signal paths or nodes, the term “selectively coupled” means a node connected directly or indirectly via one or more selectable elements (such as switches) that couple the “selectively coupled” signal path or node and may isolate one or more of the nodes from alternative nodes or signal paths.

[0129] Computer-readable media includes both computer storage media and communication media, with communication media encompassing any media that facilitates the transfer of a computer program from one place to another. Storage media can be any available media accessible by a general-purpose or special-purpose computer. By way of example, and not limitation, computer-readable media can include RAM, ROM, EEPROM, flash memory, CD-ROM or other optical disc storage devices, magnetic disk storage devices or other magnetic storage devices, or any other media that can be used to carry or store desired program code in the form of instructions or data structures and is accessible by a general-purpose or special-purpose computer or a general-purpose or special-purpose processor. Furthermore, any connection is appropriately referred to as computer-readable media. For example, if software is transmitted from a website, server, or other remote source using coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, then such coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of media. As used in this article, disks and optical discs include compact optical discs (CDs), laser discs, optical discs, digital versatile discs (DVDs), floppy disks, and Blu-ray discs. Disks typically reproduce data magnetically, while optical discs reproduce data optically using lasers. Combinations of these are also included within the scope of computer-readable media.

[0130] This disclosure is provided to enable those skilled in the art to make or use the subject matter claimed herein. Various modifications to this disclosure will be readily apparent to those skilled in the art, and the general principles defined herein can be applied to other variations without departing from the scope of this disclosure. Therefore, this 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

1. A method for operating via a satellite communication system, the satellite communication system comprising a plurality of geographically distributed access nodes and satellites having a plurality of forward signal paths, the method comprising: Transmission is made from the plurality of access nodes to the satellite during each of two or more scheduled intervals, each access node transmitting a corresponding one of a plurality of forward uplink signals, wherein a corresponding superposition of the plurality of forward uplink signals is relayed in each forward signal path as a corresponding forward downlink signal, and wherein the superposition of the plurality of forward downlink signals forms a plurality of simultaneous forward beams according to a beam weighting matrix for forming the plurality of forward uplink signals, the beam weighting matrix including end-to-end forward beam weights; as well as For each scheduling interval: A forward signal path allocation is determined relative to non-overlapping first and second user coverage areas, the forward signal path allocation assigning a non-zero first subset of the forward signal paths to the first user coverage area and assigning a non-zero second subset of the forward signal paths to the second user coverage area. According to the forward signal path allocation control for the connectivity of the plurality of forward signal paths, wherein the output of the first subset of the forward signal paths is switched to be connected to a corresponding feed of a first user link array configured to illuminate the first user coverage area, and wherein the output of the second subset of the forward signal paths is switched to be connected to a corresponding feed of a second user link array configured to illuminate the second user coverage area. as well as The beam weight matrix used during the scheduling interval is calculated based on the end-to-end forward channel corresponding to the forward signal path allocation.

2. The method of claim 1, wherein each user coverage area is divided into beam coverage areas of a predetermined pattern, and wherein calculating the beam weight matrix for use during each scheduling interval includes calculating the beam weight matrix based on which beam coverage areas are to be illuminated in each user coverage area during the scheduling interval.

3. The method of claim 2, wherein each beam coverage area encompasses a geographic location representing the desired beam center, wherein the satellite communication system receives probe signals from a corresponding reference user terminal (RUT) located at or near the corresponding geographic location, and wherein the method includes estimating the end-to-end forward channel from the received probe signals.

4. The method of claim 1, wherein each forward signal path has an input connected to a corresponding feed in a feed link array, wherein the output of each forward signal path is switchable between a corresponding feed in the first user link array and a corresponding feed in the second user link array, and wherein determining the forward signal path allocation includes determining which feed modes to use for simultaneous beamforming into the first and second user coverage areas based on the corresponding distribution of user terminals in the first and second user coverage areas, the feed modes indicating which of the forward signal paths are included in the first subset and which of the forward signal paths are included in the second subset.

5. The method of claim 1, wherein the forward signaling path allocation varies over two or more periods in the scheduling interval based on the determination of the capacity requirement between the first user coverage area and the second user coverage area.

6. The method of claim 1, wherein controlling the connectivity of the plurality of forward signal paths according to the forward signal path allocation includes providing the satellite with a schedule indicating the forward signal path allocation for the plurality of scheduled intervals, and wherein the satellite has a loaded switching circuitry system operable to switch the output of the forward signal path according to the schedule.

7. The method of claim 1, wherein controlling the connectivity of the plurality of forward signal paths according to the forward signal path allocation includes transmitting a command to the satellite to control a switching circuit system of the satellite, the switching circuit system being operable to switch the output of the forward signal path.

8. A satellite communication system, the satellite communication system comprising: The satellite has multiple forward signal paths; Multiple geographically distributed access nodes, comprising a ground segment of a satellite communication network, are configured to transmit to the satellite during each of two or more scheduled intervals. Each access node transmits a corresponding one of a plurality of forward uplink signals, wherein a corresponding superposition of the plurality of forward uplink signals is relayed in each forward signal path as a corresponding forward downlink signal, and wherein the superposition of the plurality of forward downlink signals forms a plurality of simultaneous forward beams according to a beam weighting matrix for forming the plurality of forward uplink signals, the beam weighting matrix including end-to-end forward beam weights. as well as A controller, further included in the ground segment of the satellite communication network, the controller including a communication interface and one or more processors, the one or more processors being configured to: A forward signal path allocation is determined relative to each scheduling interval, the forward signal path allocation in each scheduling interval being determined relative to non-overlapping first and second user coverage areas, and a non-zero first subset of the forward signal paths is allocated to the first user coverage area, and a non-zero second subset of the forward signal paths is allocated to the second user coverage area. The connectivity of the forward signal path is controlled according to the beam allocation determined for each scheduling interval, such that, relative to the first and second subsets of the forward signal path determined for each scheduling interval, the output of the first subset of the forward signal path is switched to be connected to a corresponding feed of a first user link array configured to illuminate the first user coverage area, and the output of the second subset of the forward signal path is switched to be connected to a corresponding feed of a second user link array configured to illuminate the second user coverage area. as well as The beam weight matrix used during each scheduling interval is calculated based on the end-to-end forward channel corresponding to the forward signal path allocation determined for each scheduling interval.

9. The satellite communication system of claim 8, wherein each user coverage area is divided into beam coverage areas of a predetermined pattern, and wherein the controller is configured to calculate the beam weight matrix for use in each scheduling interval based on which beam coverage areas are to be illuminated in each user coverage area during the scheduling interval.

10. The satellite communication system of claim 9, wherein each beam coverage area encompasses a geographic location representing a desired beam center, wherein the satellite communication system receives probe signals from a corresponding reference user terminal (RUT) located at or near the corresponding geographic location, and wherein the controller is configured to estimate the end-to-end forward channel from the received probe signals.

11. The satellite communication system of claim 8, wherein each forward signal path has an input connected to a corresponding feed in a feed link array, wherein the output of each forward signal path is switchable between a corresponding feed in the first user link array and a corresponding feed in the second user link array, and wherein, as part of determining the forward signal path allocation, the controller is configured to determine which feed modes to use for simultaneous beamforming into the first and second user coverage areas based on the corresponding distribution of user terminals in the first and second user coverage areas, and wherein the feed modes indicate which of the forward signal paths are included in the first subset and which of the forward signal paths are included in the second subset.

12. The satellite communication system of claim 8, wherein the forward signal path allocation varies over two or more periods in the scheduling interval based on a change in the determination of capacity requirements between the first user coverage area and the second user coverage area.

13. The satellite communication system of claim 8, wherein the controller is configured to control the connectivity for the plurality of forward signal paths based on a schedule provided to the satellite indicating the allocation of the forward signal paths for a plurality of scheduled intervals, and wherein the satellite has a loaded switching circuitry system operable to switch the output of the forward signal paths according to the schedule.

14. The satellite communication system of claim 8, wherein the controller is configured to control the connectivity of the forward signal path by transmitting commands to the satellite to control a switching circuit system of the satellite, the switching circuit system being operable to switch the output of the forward signal path according to the commands.

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