BEAM MANAGEMENT USING SPARSE ANTENNA ARRAYS

Methods, systems, and devices communications are described. A terminal may be identified with a geographic region. First beam coefficients may be determined for an antenna array having interelement spacing of antennas that is different across the antenna array. The first beam coefficients may be used to form a first beam for the terminal, where a coverage area of the first beam may encompass the geographic region. The first beam may be used to communicate with the terminal. Based on a utilization of the first beam exceeding a threshold, second beam coefficients may be determined for the antenna array. The second beam coefficients may be used to form a second beam, where a coverage area of the second beam may be different than the coverage area of the first beam. The second beam may be used to communicate with the terminal.

BACKGROUND

The following relates generally to communications, including beamforming using sparse antenna arrays.

Communications devices may communicate with one another using wired connections, wireless (e.g., radio frequency (RF)) connections, or both. Wireless communications between devices may be performed using wireless spectrum that has been designated for a service provider, wireless technology, or both. In some examples, the amount of information that can be communicated via a wireless communications network is based on an amount of wireless spectrum designated to the service provider, and an amount of frequency reuse within the region in which service is provided. Wireless communications (e.g., cellular communications, satellite communications, etc.) may use beamforming and multiple-input multiple-output (MIMO) techniques for communications between devices to increase frequency reuse, however, providing a high level of frequency reuse in some types of communication systems such as satellite communications presents challenges.

SUMMARY

A terminal may be identified with a geographic region. First beam coefficients may be determined for an antenna array having interelement spacing of antennas that is different across the antenna array. The first beam coefficients may be used to form a first beam for the terminal, where a coverage area of the first beam may encompass the geographic region. The first beam may be used to communicate with the terminal. Based on a utilization of the first beam exceeding a threshold, second beam coefficients may be determined for the antenna array. The second beam coefficients may be used to form a second beam, where a coverage area of the second beam may be different than the coverage area of the first beam. The second beam may be used to communicate with the terminal.

DETAILED DESCRIPTION

A communications system (e.g., a satellite system) may communicate with terminals using wide communication beams (e.g., having coverage areas that span tens of kilometers), narrow communication beams (e.g., having coverage areas that span less than five kilometers), or a combination thereof. In some examples, enhanced techniques (e.g., geometric interpretation, geometrically-informed MIMO, etc.) may be used to form the narrow communication beams. The narrow communication beams may be formed within wide communication beams and may be used to increase a capacity of the communications systems, to increase a signal quality for a terminal, or a combination thereof.

Techniques for supporting using both wide communication beams and narrow communication beams to perform communicate may be established. In some examples, techniques for determining when to activate one or more narrow communication beams may be established—e.g., based on a utilization of a wide communication beam exceeding a threshold. Also, techniques for repositioning (e.g., centering) a beam coverage area of a narrow communication beam to increase (e.g., maximize) a quality of signals transmitted by a terminal using the narrow communication beam may be established, as well as techniques for maintaining (e.g., by moving) the beam coverage area of the narrow communication beam in a preferred position as the terminal moves. Additionally, techniques for forming additional narrow communication beams to service terminals that are left by a moving beam coverage area of a narrow communication beam may be established.

FIG.1shows an example of a satellite communications system100that supports beam management using sparse antenna arrays in accordance with examples described herein. Satellite communications system100may include a ground system135, terminals120, and satellite system101. The ground system135may include a network of access nodes140that are configured to communicate with the satellite system101. The access nodes140may be coupled with access node transceivers145that are configured to process signals received from and to be transmitted through corresponding access node(s)140. The access node transceivers145may also be configured to interface with a network125(e.g., the Internet)—e.g., via a network device130(e.g., a network operations center, satellite and gateway terminal command centers, or other central processing centers or devices) that may provide an interface for communicating with the network125.

Terminals120may include various devices configured to communicate signals with the satellite system101, which may include fixed terminals (e.g., ground-based stationary terminals) or mobile terminals such as terminals on boats, aircraft, ground-based vehicles, and the like. A terminal120may communicate data and information with an access node140via the satellite system101. The data and information may be communicated with a destination device such as a network device130, or some other device or distributed server associated with a network125.

The satellite system101may include a single satellite, or a network of satellites that are deployed in space orbits (e.g., low earth orbits, medium earth orbits, geostationary orbits, etc.). One or more satellites included in satellite system101may be equipped with multiple antennas (e.g., one or more antenna arrays). In some examples, the one or more satellites equipped with multiple antennas may each include one or more antenna panels that include an array of evenly distributed antennas (which may also be referred to as antenna elements). In some examples, a satellite may be equipped with an antenna array including antennas that are unevenly distributed across a large region. In some examples, the antennas may be connected to a central entity via wired or wireless links. Deploying the antennas over the large region may increase an aperture size of the antenna array of the satellite relative to an antenna array that includes evenly distributed antennas (e.g., due to limitations associated with manufacturing and deploying a large antenna array with evenly distributed antennas). In some examples, a set of satellites, each including an antenna, are unevenly distributed across the large region, where each satellite may communicate with a central entity (e.g., a central server or ground station). In such cases, the antennas of the set of satellites may be used to form an antenna array. In some examples, a set of satellites, each including an antenna subarray, are unevenly distributed across the large region, where each satellite may communicate with a central entity (e.g., a central server or ground station) and where the antenna subarrays may include an array of evenly distributed antennas. In such cases, the antenna subarrays of the set of satellites may be used to form an antenna array.

The satellite system101may use the one or more satellites to support multiple-input multiple-output (MIMO) techniques to increase a utilization of frequency resources used for communications—e.g., by enabling wireless spectrum to be reused, in time and frequency, in different geographic regions of a geographic area. Similarly, the satellite system101may use the one or more satellites to support beamforming techniques to increase a utilization of frequency resources used for communications.

MIMO techniques may be used to exploit multipath signal propagation and increase spectral efficiency by transmitting or receiving multiple signals via different spatial layers. The multiple signals may, for example, be transmitted by a transmitting device (e.g., a satellite system) via a set of antennas in accordance with a set of weighting coefficients. Likewise, the multiple signals may be received by a receiving device (e.g., a satellite system) via a set of antennas in accordance with a set of weighting coefficients. Each of the multiple signals may be associated with a separate spatial stream and may carry bits associated with the same data stream (e.g., the same codeword) or different data streams (e.g., different codewords). MIMO techniques include single-user MIMO (SU-MIMO), where multiple spatial layers are used to communicate with one device, and multiple-user MIMO (MU-MIMO), where multiple spatial layers are used to communicate with multiple devices.

To determine weighting coefficients to apply to the set of antennas such that the N spatial layers are formed, an (M×N) MIMO matrix may be formed, where M may represent the quantity of antennas of the set of antennas. In some examples, M may be equal to N. The MIMO matrix may be determined based on a channel matrix and used to isolate the different spatial layers of the channel. In some examples, the weighting coefficients are selected to emphasize signals transmitted using the different spatial layers while reducing interference of signals transmitted in the other spatial layers. Accordingly, processing signals received at each antenna with the set of antennas (e.g., a signal received at the set of antennas) using the MIMO matrix may result in multiple signals being output, where each of the multiple signals may correspond to one of the spatial layers. The elements of the MIMO matrix used to form the spatial layers of the channel may be determined based on channel sounding probes received at a satellite system101—e.g., from one or more devices. In some examples, the weighting coefficients used for MIMO communications may be referred to as beam coefficients, and the multiple signals or spatial layers may be referred to as beam signals.

Beamforming techniques may be used to shape or steer a communication beam along a spatial path between a satellite system101and a geographic area. A communication beam may be formed by determining weighting coefficients for antenna elements of antenna array that result in the signals transmitted from or received at the antenna elements being combined such that signals propagating in a particular orientation with respect to an antenna array experience constructive interference while others experience destructive interference. Thus, beamforming may be used to transmit signals having energy that is focused in a direction of a communication beam and to receive signals that arrive in a direction of the communication with increased signal power (relative to the absence of beamforming). The weighting coefficients may be used to apply amplitude offsets, phase offsets, or both to signals carried via the antennas. In some examples, the weighting coefficients applied to the antennas may be used to form multiple beams associated with multiple directions, where the multiple beams may be used to communicate multiple signals having the same frequency at the same time. The weighting coefficients used for beamforming may be referred to as beam coefficients, and the multiple signals may be referred to as beam signals.

In some examples, beamforming techniques may be used by a satellite system101to form spot beams that are tiled (e.g., tessellated) across a geographic area. In some examples, the wireless spectrum used by a satellite system101may be reused across sets of the spot beams for communications between terminals120and the satellite system. In some examples, the wireless spectrum can be reused in spot beams that do not overlap, where a contiguous geographic region can be covered by overlapping spot beams that each use orthogonal resources (e.g., orthogonal time, frequency, or polarization resources).

To support an increased quantity of users within a geographic area, an antenna array (which may be referred to as a large, sparse antenna array) having antennas with inter-element spacing that is different across the antenna array may be used to increase a resolution of beamforming techniques. That is, the large, sparse antenna array may be used (e.g., in combination with respective beam coefficients) to form communication beams with small coverage areas (e.g., less than 10 kilometers in diameter). A large, sparse antenna array, such as antenna array105, may include multiple antennas110(e.g., hundreds or thousands of antennas) that are unevenly distributed across an area—e.g., in space. In some examples, each antenna110is, or is installed on, an individual satellite. In other examples, the antennas110are installed on a single satellite, where each antenna110is tethered to a central location e.g., via a physical connection.

Additionally, the distance between the antennas110may be greater than a distance associated with a wavelength of signals supported for communication by the large, sparse antenna array—e.g., the distance between the antennas110may be greater than a distance associated with the wavelength. In some examples, the distance between the antennas110may be greater than ten times the wavelength. In some examples, a first distance (d1) between a first antenna of the antennas110and a second antenna of the antennas110may be different than a second distance (d2) between the second antenna and a third antenna of the antennas110, and so on throughout antenna array105. In some examples, a large, sparse antenna array includes multiple antenna subarrays115(e.g., tens or hundreds of antenna subarrays) that are unevenly distributed across the area. In some examples, the antenna subarrays may each include a group of the antennas110. In some examples, the antenna subarrays115may each include antennas110(which may also be referred to as antenna elements) that are evenly distributed across a corresponding antenna subarray115. In some examples, in addition to being large and sparse, the antenna array105may be random or semi-random such that the distances between the antennas110of the antenna array105may be uncontrolled or partially controlled (e.g., unconstrained in one or more dimensions, or allowed to drift in one or more dimensions relative to other antennas110).

To form the small communication beams, geometric relationships between a geographic region and the antennas110of the large, sparse antenna array105may be used. In some examples, the geometric relationships between a geographic region and the antennas110of the large, sparse antenna array105may also be used to simplify the processing used for massive-MIMO techniques—e.g., based on the limited directions of signal incidence, location information known for the terminals, or any combination thereof.

In some examples, to support communicating using communication beams117with small coverage areas, a large, sparse antenna array105may be used (e.g., in combination with respective beam coefficients) to form discovery beams119within a geographic area150, where each discovery beam119may be formed by a corresponding set of antennas110of the antenna array105and may cover a discovery area155within the geographic area150. For example, each antenna subarray115may form a discovery beam119, and the discovery beams may be tiled across the geographic area150. Preambles118transmitted from terminals120within a discovery area155of a discovery beam119may be detected using the large, sparse antenna array105(e.g., each antenna subarray115may detect preambles118transmitted from within a corresponding discovery area155). Based on detecting a preamble118using a discovery beam119, a presence of a terminal120in a discovery area155of the discovery beam119may be determined.

In some examples, based on detecting the presence of the terminal120within a discovery area155, one or more antennas110(e.g., an antenna subarray115or a group of antennas110) may be selected to perform communications with the terminal120. In some cases, the set of antennas110and a corresponding set of beamforming coefficients are used to form a wide communication beam that has a wide coverage area including a position of the terminal120. In some examples, a size of the wide coverage area may be similar to a size of a discovery area155.

In some examples, based on detecting the presence of the terminal120, a second set of antennas110(e.g., antennas from more than one antenna subarray115, a substantial portion of antennas110, a majority of antennas110, or all of the antennas110) of the antenna array105and corresponding beam coefficients may be selected to form a communication beam117(e.g., a small or narrow beam) having a beam coverage area160within the discovery area155that includes a position of the terminal120. The second set of antennas may include a larger quantity of antennas than the one or more antennas used to form the wide communication beam. Subsequently, signals detected at the antenna array105may be processed according to the beam coefficients used to form the narrow communication beam117, resulting in a beam signal for the narrow communication beam117. In some examples, the beam signal may include one or more signals transmitted from one or more terminals positioned within the beam coverage area160.

In some examples, antenna array105includes multiple antenna subarrays115, where each antenna subarray115may be used to form a discovery beam119associated with a corresponding discovery area155. Preambles from a set of terminals120may be detected using a subset of the discovery beams119. Based on detecting the terminals using the subset of the discovery beams119, communication beams117may be formed (e.g., using geometric interpretation or MIMO-based techniques) within the corresponding discovery areas155, where beam coverage areas160of the communication beams117may encompass the detected terminals120. Communications may be performed between the antenna array105and detected terminals120using the communication beams117, where at least a subset of the communication beams117may reuse common time, frequency, and polarization resources.

In some examples, techniques for supporting communications using wide and narrow communication beams may be used. For example, techniques for determining when to use a wide communication beam, narrow communication beams117, or a combination thereof, may be used. For instance, narrow communication beams117within a wide coverage area of a wide communication beam may be activated based on a utilization of the wide communication beam reaching a threshold (e.g., greater than 80% of the capacity of the wide communication beam). In some examples, techniques for adjusting a beam coverage area160of a narrow communication beam117to increase a quality of signals received from a terminal120that is used as a reference for the narrow communication beam117may be used. Also, techniques for maintaining the beam coverage area160of the narrow communication beam117focused on a position of the reference terminal120(which may be referred to as “beam tracking”) may be used. Additionally, techniques for adjusting a size of beam coverage areas160of narrow communication beams117(or for forming additional narrow communication beam117) to accommodate other terminals may be used.

FIG.2shows an example of a communications network200that supports beam management using sparse antenna arrays in accordance with examples described herein.

Communications network200depicts a system for communicating using one or more of MIMO techniques, geometric interpretation techniques, and geometrically-informed MIMO techniques. Communications network200may include antenna array205, bus215, beam manager220, signal detector240, positioning component245, processor247, communications manager250, and memory255. At least a portion (e.g., all) of communications network200may be located within a space segment of communications network200(e.g., in a satellite system). In some examples, a portion of communications network200that is not included in the space segment may be located within a ground segment of communications network200(e.g., in a ground system). For example, antenna array205, beam manager220, signal detector240, positioning component245, processor247, and memory255may be included in a space segment of communications network200, while communications manager250may be included in a ground segment of communications network200. In another example, antenna array205may be included in a space segment of communications network200, while beam manager220, signal detector240, positioning component245, processor247, memory255, and communications manager250may be included in a ground segment of communications network200.

Antenna array205may be an example of the antenna array ofFIG.1and may include antennas210. The antennas210may be examples of the antennas110described with reference toFIG.1. In some examples, one or more of the antennas210may be or include an antenna subarray, similar to the antenna subarray115described with reference toFIG.1. The spacing between the antennas210may be different across antenna array205. In some examples, a distance (e.g., an average distance) between the antennas210is greater than a distance associated with a wavelength of signals communicated using antenna array205. In some examples, a distance (e.g., an average distance) between the antennas210is greater than a distance associated with ten times the wavelength of the signals communicated using antenna array205.

Bus215may represent an interface over which signals may be exchanged between antenna array205and a central location that may be used to distribute the signal to the signal processing components of communications network200(e.g., beam manager220, signal, signal detector240, and positioning component245. Bus215may include a collection of wires that connect to each of the antennas. Additionally, or alternatively, bus215may be a wireless interface that is used to wirelessly communicate signaling between antenna array205and the signal processing components—e.g., in accordance with a communication protocol.

Beam manager220may be configured to form beams, including discovery beams, communication beams, geometric interpretation-based beams, MIMO-based beams, and the like. In some examples, beam manager220may be configured to form one or more discovery beams (e.g., the discovery beams that cover the discovery areas155ofFIG.1) within a geographic area (e.g., geographic area150ofFIG.1) that is covered by the antenna array205. To form the discovery beams, native antenna patterns of sets of the antennas210may be used, or may be combined with beamforming techniques, MIMO techniques, or a combination thereof.

Beam manager220may also be configured to form one or more communication beams (e.g., the communication beams that form the beam coverage areas160ofFIG.1). To form the communication beams, geometric interpretation-based beamforming techniques, MIMO techniques, or geometrically-informed MIMO techniques may be used. Beam manager220may include geometric component225, MIMO component230, refinement component232, and tracking component234.

Geometric component225may be configured to use a geometric relationship between a position of a terminal and a set (e.g., up to and including all) of the antennas210of antenna array205to form small communication beams (e.g., communication beams that have a diameter that is less than ten (10) km, or less than five (5) km). In some examples, geometric component225may determine beam coefficients (e.g., phase shifts, amplitude components) that may be used to align in time signals detected at different antennas210so that the signals may be summed together according to the spatial location of the terminal, increasing the signal strength of a transmitted signal associated with each of the detected signals. In some examples, geometric component225may determine a first set of beam coefficients associated with a first beam coverage area, a second set of beam coefficients associated with a second beam coverage area, and so on. Accordingly, geometric component225may independently determine and apply multiple sets of beam coefficients to signals received from antenna array205, each set of beam coefficients associated with a different beam coverage area.

MIMO component230may be configured to use multipath signal propagation to form MIMO-based beams. In some examples, MIMO component230may receive channel sounding probes from a set of transmitters (e.g., terminals), where the structure of the channel sounding probes may be known to MIMO component230and where the channel sounding probes transmitted from different transmitters may be orthogonal to one another. MIMO component230may use the channel sounding probes to estimate the channel between antenna array205and the transmitters. Based on the estimated channel, MIMO component230may determine beam coefficients (e.g., amplitude and phase shifts) that may be used to reveal the spatial layers of the channel. In some examples, MIMO component230may determine beam coefficients that may be used to isolate signals transmitted over the spatial layers from one another—e.g., by, in each spatial layer, emphasizing the signals transmitted within the spatial layer and canceling interference from signals transmitted within other spatial layers. MIMO component230may determine a single set of beam coefficients that is applied to the signals detected at a set (e.g., all) of the antennas210at antenna array205. The beam coefficients may be included in an M×N matrix, where a value of M may indicate the quantity of antennas210and a value of N may indicate the quantity of spatial layers, where the value of N may be less than or equal to the value of M.

Refinement component232may be configured to refine the positioning of beam coverage areas relative to reference terminals. For example, for a narrow communication beam, refinement component232may be configured to reposition the beam coverage area of the narrow communication beam to increase (e.g., maximize) a quality of signals received from a terminal for which the narrow communication beam was formed—e.g., by dithering the coverage area of the communication beam, sweeping the coverage area of the communication beam across a geographic region, etc.

Tracking component234may be configured to maintain the beam coverage areas over the terminals for which the corresponding narrow communication beams were formed. For example, for a narrow communication beam formed with reference to a terminal, tracking component234may be configured to move the beam coverage area with the movement of the terminal—e.g., keeping the terminal in a high-SNR area of the beam coverage area, such as the center of the beam coverage area.

Signal detector240may be configured to detect preambles transmitted from one or more terminals. In some examples, the preambles include repetitions of a waveform and are used to indicate the presence of a transmitting terminal. The preambles may also include positioning information (e.g., GPS coordinates). In some examples, the preamble is encoded and difficult to spoof—e.g., by using spreading codes, encrypted data, etc. In some examples, the preambles may be two-part preambles. For example, the preamble may include a first part used for detection of the preamble (e.g., the repetitions of the waveform) and a second part including the position information. In some examples, a first part of the preamble including the repetitions is transmitted first and the second part of the preamble including the positioning data is transmitted after a response from the communications network200acknowledging detection of the first part of the preamble is received.

Positioning component245may be configured to determine a position of one or more terminals that are detected within a geographic region—e.g., based on detecting the corresponding one or more preambles. In some examples, positioning component245determines the position of the one or more terminals based on positioning information received in the preamble. Additionally, or alternatively, positioning component245may determine the position of the one or more terminals based on dithering a beam coverage area of communication beam to determine a position of the beam coverage area that maximizes the signal quality for a terminal, where the terminal may be centered in the beam coverage area.

Positioning component245may be further configured to determine a position of the antennas210. In some examples, positioning component245may determine the position of the antennas based on signals transmitted from transmitters at known geographic locations and geometric relationships between the transmitters and antenna array205. In some examples, the transmitters may be located on the ground, in space, on a satellite including antenna array205, on the antennas210, or a combination thereof.

Communications manager250may be configured to process beam signals received from beam manager220. Communications manager250may decode data symbols included in the beam signals. In some examples, communications manager250may configure different modes at beam manager220. For example, communications manager250may configure a first mode at beam manager220that is used for discovering terminals in a geographic area. While the first mode is configured, beam manager220may use beamforming and/or MIMO techniques to form discovery areas. Communications manager250may also configure a second mode at beam manager220that is used for communication with terminals in the geographic area using small beams. While the second mode is configured, beam manager220may use geometric interpretation to form beam coverage areas for communicating with discovered terminals. In some examples, the first mode and the second mode may be simultaneously configured at beam manager220. Thus, antenna array205may be used to simultaneously form discovery beams and communication beams. In the case where discovery beams and communication beams are formed concurrently, communication beams within a discovery beam may use different frequency, time, or polarization resources. Communications manager250may also configure a third mode at beam manager220that is used for communication with terminals in the geographic area using small beams. While the third mode is configured, beam manager220may use geometrically-informed MIMO to form beam coverage areas for communicating with discovered terminals. In some examples, the first mode and the third mode are configured simultaneously, and the second mode and the third mode are configured alternatively at beam manager220.

In some examples, communications manager250may be configured to direct beam manager220to activate narrow communication beams to provide service to a geographic region. In some cases, the narrow communication beams may be used simultaneously with a wide communication beam to provide communication services to the geographic region. In other cases, the narrow communication beams may be used instead of the wide communication beam to provide communication services to the geographic region e.g., while a set of communication resources within the geographic region may be reserved for control signaling, such as preamble transmissions. In some examples, communications manager250may be configured to direct beam manager220to adjust a size of a narrow communication beam—e.g., to accommodate a terminal within a beam coverage area of the narrow communication beam.

Processor247may include an intelligent hardware device (e.g., a general-purpose processor, a digital signal processor (DSP), a central processing unit (CPU), a microcontroller, an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA), a programmable logic device, a discrete gate or transistor logic component, a discrete hardware component, or any combination thereof). The processor247may be configured to execute computer-readable instructions stored in a memory (e.g., memory255) to cause the communications network200to perform various functions (e.g., functions or tasks supporting beam management using sparse antenna arrays). For example, the communications network200or a component of the communications network200may include a processor247and memory255coupled to the processor247that are configured to perform various functions described herein.

The memory255may include random access memory (RAM) and/or read-only memory (ROM). The memory255may store code that is computer-readable and computer-executable. The code may include instructions that, when executed by the processor247, cause the communications network200to perform various functions described herein. The code260may be stored in a non-transitory computer-readable medium such as system memory or another type of memory. In some cases, the code260may not be directly executable by the processor247but may cause a computer (e.g., when compiled and executed) to perform functions described herein. In some cases, the memory255may contain, among other things, a basic I/O system (BIOS) which may control basic hardware or software operation such as the interaction with peripheral components or devices.

Additionally, or alternatively, beam manager220, signal detector240, positioning component245, communications manager250, or various combinations or components thereof, may be implemented in code260(e.g., as communications management software or firmware), executed by processor247. If implemented in code260executed by processor247, the functions of beam manager220, signal detector240, positioning component245, communications manager250, or various combinations or components thereof may be performed by a general-purpose processor, a DSP, a central processing unit (CPU), an ASIC, an FPGA, or any combination of these or other programmable logic devices (e.g., configured as or otherwise supporting a means for performing the functions described in the present disclosure).

FIG.3shows an example of a communications subsystem300that supports beam management using sparse antenna arrays in accordance with examples described herein. Communications subsystem300depicts communications between antenna array305and terminals320that are processed using geometric relationships between the antennas310of antenna array305and the terminals320. In some examples, a first set of signals325are transmitted between first terminal320-1and antenna array305, and a second set of signals330are transmitted between second terminal320-2and antenna array305. In some examples, the first set of signals325may be associated with a single signal (e.g., a preamble or data signal) transmitted from first terminal320-1to antenna array305, where the first set of signals325may be components (e.g., multipath components) of the signal transmitted from first terminal320-1. In other examples, the first set of signals325may be associated with a single signal (e.g., a preamble response or data signal) obtained at antenna array305for transmission to first terminal320-1, where the first set of signals325may be components (e.g., elements) of the signal transmitted from antenna array305. Similarly, the second set of signals330may be associated with a single signal (e.g., a preamble or data signal) transmitted from second terminal320-2to antenna array305or a single signal (e.g., a preamble response or data signal) obtained at antenna array305for transmission to second terminal320-2.

In some examples, a first set of the antennas310and first beam coefficients are used to form discovery beam319having discovery area355. Signals received at antenna array305using the first set of the antennas310and the first beam coefficients may be analyzed to determine whether a preamble indicating the presence of a terminal is included in the signals. In some examples, the presence of first terminal320-1is detected based on first terminal320-1transmitting a preamble, where the first set of signals325may be signal components of the preamble transmission. The preamble may include a repeating waveform. In some examples, the waveform may be modulated with a spreading code before transmission or may include encoded data to increase a difficulty associated with spoofing the preamble. The preamble may also include positioning information—e.g., in a second part of the preamble.

In some examples, a position of first terminal320-1may be determined based on positioning information included in the preamble. Additionally, or alternatively, the position of first terminal320-1may be determined based on dithering a beam coverage area around discovery area355after detecting the presence of first terminal320-1. The position of first terminal320-1may be determined based on a signal quality associated with first beam coverage area360-1satisfying a threshold, being higher than signal qualities associated with other beam coverage areas covered by the dithering operation, or both. The presence and position of second terminal320-2may similarly be detected based on a preamble transmitted from second terminal320-2, where the second set of signals330may be signal components of the preamble transmission.

Second beam coefficients may be determined for first terminal320-1based on the position of first terminal320-1. The second beam coefficients may also be determined based on a position of the antennas310relative to first terminal320-1. The second beam coefficients, along with a second set of the antennas310, may be used in the formation of first communication beam317-1having first beam coverage area360-1. The second beam coefficients may be used to apply timing shifts (e.g., phase shifts) or amplitude weighting to signals detected at different antennas of the second set of the antennas310, such that signals transmitted within first beam coverage area360-1are distinguishable from signals transmitted within adjacent beam coverage areas. In some examples, the second beam coefficients may be represented using an M1×1 vector, where M1may represent the quantity of antennas (e.g., 100 antennas, 1000 antennas, etc.) of the second set of the antennas310. In some cases, the M1×1 vector may include coefficients for all of antennas310, where some coefficients may be zero coefficients (e.g., the second set of antennas310that contribute to the first communication beam317-1may be a subset of the antennas310).

Third beam coefficients may similarly be determined for second terminal320-2. In some examples, the third beam coefficients may be represented using an M2×1 vector, where M2may represent the quantity of antennas (e.g., 100 antennas, 1000 antennas, etc.) of a third set of the antennas310. In some examples, the third set of the antennas310and the second set of the antennas310are overlapping (e.g., partially or completely).

In some examples, the first set of the antennas310associated with discovery beam319may detect the first set of signals325within discovery area360and the second beam coefficients used to form first communication beam317-1may be determined. Based on the determining, the second beam coefficients may be applied to a subsequent set of detected signals (e.g., corresponding to a subsequent data signal transmitted by first terminal320-1) that is output by the second set of the antennas310associated with first communication beam317-1. In some examples, the second set of the antennas310includes most (e.g., greater than 50%, 60%, 70%, 80%, or 90%) of the antennas310at antenna array305. In some cases, the second set of antennas310may include a portion (or all) of the first set of antennas310associated with discovery beam319, where the second set of antennas310may include a larger quantity of the antennas310than the first set of antennas310.

The first set of antennas310associated with discovery beam319may also detect the second set of signals330within discovery area360and the third beam coefficients used to form second communication beam317-2may be determined. Based on the determining, the third beam coefficients may be applied to a subsequent set of detected signals (corresponding to a subsequent data signal transmitted by second terminal320-2) that is output by the third set of the antennas310associated with second communication beam317-2. The third set of antennas310may be overlapping with the second set of antennas310e.g., may include a portion of or be the same as the second set of antennas310. The second set of antennas310may also include most (e.g., greater than 50%, 60%, 70%, 80%, or 90%) of the antennas310at antenna array305.

Signal diagram301depicts a first set of element signals335detected at the second set of antennas310associated with first communication beam317-1and a second set of element signals340detected at the third set of antennas310associated with second communication beam317-2. Signal diagram301also depicts time delays associated with when the first set of element signals335and second set of element signals340are detected at respective antennas. The first set of element signals335may correspond to the first set of signals325, and the second set of element signals340may correspond to the second set of signals330. In some examples, the first set of element signals335and the first set of signals325may be associated with a data signal transmitted from first terminal320-1. And the second set of element signals340and the second set of signals330may be associated with a data signal transmitted from second terminal320-2.

Signal diagram301also depicts a result of applying first beam coefficients364-1(which may correspond to the second beam coefficients used to form first communication beam317-1) to the first set of element signals335to obtain resulting element signals365. In some examples, each beam coefficient of first beam coefficients364-1may be applied to a respective antenna of the second set of the antennas310. Each beam coefficient of first beam coefficients364-1may be used to apply a time delay (e.g., a phase shift) or an amplitude weight, or both, to a signal received at a respective antenna element such that the resulting element signals365are aligned in time and can be combined (e.g., summed via summing component366) with one another to form first beam signal375-1for first communication beam317-1, where an SNR value of first beam signal375-1may be proportional to the quantity of element signals365. In some examples, summing component366may include separate summing components that are used to sum the element signals obtained for respective communication beams.

Second beam coefficients364-2(which may correspond to the third beam coefficients used to form second communication beam317-2) may similarly be applied to the second set of element signals340and the resulting element signals370may be combined (e.g., summed via summing component366) to obtain second beam signal375-2for second communication beam317-2. Accordingly, the beam coefficients used to form the communication beams317may be independently determined and applied to signals received at antennas310.

In some examples, the transmission of the associated data signal from first terminal320-1and the associated data signal from second terminal320-2may overlap (e.g., partially or fully) with one another in time. In such cases, the first set of element signals335and the second set of element signals340may be superimposed, forming a composite signal. Also, in such cases, first beam coefficients364-1may be applied to the composite signals to obtain resulting element signals365and second beam coefficients364-2may be applied to the composite signal to obtain resulting element signals370. In such cases, the undesired signals in the composite signals may result in noise in the resulting beam signal375and may approach being canceled for a large number of elements signals.

In some examples, the following equation may be used for determining beam signals received from multiple communication beams317:

where AiSignal corresponds to the signal received at the ith antenna of a set of antennas, f0is the frequency of the signal, t is the current time, tpropi|phySRFis the time at which the signal is received at the ith antenna, tpropi|EstSRFis a quantized estimate of the time delay between the signal received at the ith antenna and the earliest signal received at the set of antennas, and Ø is the phase of the signal. The time delay between the signal recited at the ith antenna and the earliest signal received at the set of antennas represents the delay spread across the array at each ith antenna. Subtracting the individual delay may bring all signal samples into alignment—e.g., as if they were all co-located at the “earliest signal” arrival location.

FIG.4shows an example of a communications subsystem400that supports beam management using sparse antenna arrays in accordance with examples described herein. Communications subsystem400depicts communications between antenna array405and terminals420that are processing using MIMO processing or geometrically-informed MIMO processing. In some examples, first terminal420-1is an example of first terminal320-1ofFIG.3, and second terminal420-2is an example of second terminal320-2ofFIG.3.

The communication paths between the terminals420and antenna array405may be referred to as a channel. The channel may be composed of multiple spatial layers, where the multiple antennas410of antenna array405(along with a set of beam coefficients) may be used to expose the spatial layers of the channel. In some examples, the set of beam coefficients (which may also be referred to as MIMO coefficients) are selected to expose a first spatial layer of the channel that encompasses first terminal420-1(which may also be referred to as a communication beam or MIMO beam) and a second spatial layer of the channel that encompasses second terminal420-2.

In some examples, the beam coefficients are determined based on channel sounding probes transmitted from the terminals420. The channel sounding probes may have signal patterns that are known to the communications network and that can be used to adapt the beam coefficients to ensure that the spatial layers are focused on respective terminals (or groups of terminals). The channel sounding probes may also be orthogonal to one another. Estimation techniques, such as maximum ratio combining (MRC), minimum mean square error (MMSE), zero forcing, successive interference cancellation, maximum likelihood estimation, or neural network MIMO detection techniques, may be used to estimate the channel between antenna array405and the terminals420, as well as to determine the beam coefficients. Because the beam coefficients are formed using channel sounding probes received from multiple terminals, the resulting beam coefficients may be dependent on channel sounding probes transmitted in different spatial layers. That is, the beam coefficients may be determined to decrease interference from the channel sounding probes on each other and changes to one beam coefficient may result in changes to other beam coefficients. Accordingly, the beam coefficients may be included in a single MIMO matrix (e.g., a M×N matrix, where M may represent the quantity of antennas410and N may represent the quantity of spatial streams), where the elements of the matrix may be dependent on one another.

In some examples, operations for determining the beam coefficients use high levels of processing and are highly complex. The amount of processing and complexity may increase as the quantity of antennas increases and as the quantity of spatial streams increases. In some examples, geometric relationships between terminals420and antennas410may be used to simplify the operations for determining the beam coefficients—e.g., by constraining the channel matrix, reducing the set of possible beam coefficients, or both. In some examples, the channel sounding probes may experience less scattering based on the relative positions of the terminals420and antenna array405. Accordingly, the channel estimated using the channel sounding probes may be constrained, which may reduce a complexity associated with determining the beam coefficients.

The geometric relationships between terminals420and antennas410may enable the set of possible beam coefficients to be reduced for one or more of the following reasons the position of the antennas in space may reduce the amount of scattering and multipath components that are taken into consideration in a terrestrial application; the position of the antennas in space may reduce the angles from which the signals transmitted from terminals420may arrive; the time delays at the different antennas410may be utilized to determine spatial information that facilitates determining the beam coefficients, etc.

Signal diagram401may depict a first set of element signals435received at antenna array405, where each element signal435may be received at a respective antenna e.g., first element signal435-1may correspond to a first antenna of the antennas410. Each element signal435may receive signal components related to signals transmitted from first terminal420-1and second terminal420-2(and, in some examples, from other terminals), including direct path and multipath signals.

MIMO matrix440may be applied to the element signals435, where the elements of MIMO matrix440may be previously determined using channel sounding probes transmitted from a set of terminals. After MIMO matrix440is applied to element signals435, a set of beam signals475may be output, where the beam signals475may be associated with respective spatial layers of the channel that are exposed by MIMO matrix440.

FIG.5shows an example coverage diagram500for beam management using sparse antenna arrays in accordance with examples described herein. Coverage diagram500depicts a pattern of coverage areas formed by a set of beams, where the coverage areas include wide coverage areas565and beam coverage areas560. The beam coverage areas560may be examples of beam coverage areas described with reference toFIGS.1and3. In some examples, wide coverage areas565may have similar diameters as the discovery areas described with reference toFIGS.1and3. Also, in some examples, wide coverage areas565may be used to receive discovery signals, such as preambles transmitted by a terminal to indicate a presence of the terminal.

In some examples, a communications network uses the wide coverage areas565to communicate with terminals within geographic area550. Communications using the wide coverage areas565may use less power than communications using the beam coverage areas560. While performing communications using a wide coverage area565, the communications network may determine that a utilization of a wide communication beam used to form the wide coverage area565has exceeded a threshold (e.g., 80% or 90% of the capacity of the wide communication beam). Thus, the communications network may determine that the wide beam is (or may become) congested for providing communication services to the terminals within the corresponding wide coverage area565.

In some examples, to increase the quantity of terminals or demand from the terminals that may be served within the corresponding wide coverage area565, the communications network may form narrow communication beams that cover beam coverage areas560within the wide coverage areas565. In some examples, the narrow communication beams may be formed so that corresponding beam coverage areas560cover a highly populated area (e.g., a city, metropolitan area, popular tourist or recreational areas, etc.). In some examples, the boundaries of the beam coverage areas560may be determined based on the position of one or more reference terminals and may change with time.

As depicted inFIG.5, a set of narrow communication beams may be used to form a set of beam coverage areas560—e.g., using geometric interpretation or geometrically-informed MIMO. The beam coverage areas560may be focused on a populated area within a wide coverage area565. In some examples, communications may be simultaneously performed using the wide communication beams and the narrow communications beams. For example, the communications network may receive first signals using a wide communication beam corresponding to second wide coverage area565-2and second signals using the narrow communications beams used to form the beam coverage areas560within second wide coverage area565-2. The first signals may be associated with transmitters positioned in rural areas while the second signals may be associated with transmitters positioned in more populated areas.

In some examples, positions of the beam coverage areas560may be fixed—e.g., beam coverage areas560covering high density areas. Beam coverage areas560that are fixed may be linked to a specific geographic area—e.g., relative to the boundaries of a county or city. In other cases, positions of one or more of the beam coverage areas560may be adjusted e.g., beam coverage areas560covering low density areas. Beam coverage areas560that are adjustable may be linked to a position of a particular terminal (which may be referred to as a reference terminal), and thus may move as the reference terminal moves. By contrast, beam coverage areas560that are fixed may be independent of the movement of terminals within their boundaries.

However, in some cases, communications using the narrow communication beams may excessively interfere with simultaneous communications using the wide communication beams. In some examples, communications using narrow communication beams interfere with communications using wide communication beams when a large quantity of narrow communication beams are formed within a wide coverage area, such as first wide coverage area565-1. In some examples, communications using narrow communication beams interfere with communications using wide communication beams when a large quantity of the narrow communication beams overlap with one another—e.g., because more orthogonal communication resources (e.g., time, frequency, polarity) may be used to support the overlapping narrow communication beams, limiting the use of such communication resources for a wide communication beam.

In some examples, the communications network may use only the narrow communication beams when the narrow communication beams interfere with communications using the wide communication beams. In other examples, the communications network may reserve communication resources when the narrow communication beams interfere with communications using the wide communication beams such that communications may be performed in the wide communication beams using the reserved communication resources. In some examples, the reserved communication resources are designated for control signaling, such as preambles used to indicate a presence of a terminal within a wide coverage area565.

FIG.6Ashows a communications subsystem that supports beam management using sparse antenna arrays in accordance with examples described herein.

Communications subsystem600-adepicts communications between antenna array605and terminals620using narrow communication beams, where the narrow communication beams may be formed using geometric interpretation, geometrically-informed MIMO, or both. Communications subsystem600-aalso depicts techniques for positioning a coverage area of a communication beam to increase a quality of signals received from a terminal using the communication beam.

In some examples, a communications network may use antenna array605to form a wide communication beam619having wide coverage area665and a communication beam617having beam coverage area660-a. Communication beam617may be an example of a communication beam as described with reference toFIGS.1and3and may have a beam coverage area as described with reference toFIGS.1,3, and5. The wide communication beam619may be formed using MIMO or beamforming techniques and may be an example of a wide communication beam used to form a wide coverage area565as described with reference toFIG.5. The communication beam617may be formed using geometric interpretation or geometrically-informed MIMO techniques and may be an example of a narrow communication beam used to form a beam coverage area560as described with reference toFIG.5.

In some examples, the communications network may identify a presence of a terminal based on a received preamble, where the preamble may be received within the boundaries of a wide coverage area—e.g., via a discovery beam. In some examples, the communications network determines a position (e.g., a rough position) of the terminal based on the preamble transmission. In some examples, the communications network may further refine the determined position for the terminal by dithering a coverage area of a communication beam across a geographic region and identifying a coverage area that results in a highest quality (e.g., SNR, SINR, etc.) for signals received from the terminal.

For example, the communications network may receive a preamble from first terminal620-1. Based on receiving the preamble, the communications network may use antenna array605to form communication beam617. In some examples, the coverage area of the communication beam617encompasses first terminal620-1—e.g., based on positioning information determined for first terminal620-1using the preamble. That said, in some cases, the determined positioning information provides a rough estimate of the position of first terminal620-1. In such cases, a quality of the signals received from first terminal620-1may be increased by repositioning the coverage area of communication beam617—e.g., the quality of signals transmitted from first terminal620-1via communication beam617may be increased when first terminal620-1is centered within a coverage area of communication beam617.

To determine a preferred position over the coverage area of communication beam617, the communications network may adjust the coverage area of communication beam617across a geographic region—e.g., by using different sets of beam coefficients for communication beam617corresponding to different coverage areas for communication beam617. In some cases, the communication beam617may dither the coverage area of communication beam617around a determined position of first terminal620-1. In other cases, the communications network may adjust the coverage area of communication beam across most (or all) of wide coverage area665. In some examples, dithering or adjusting the coverage area of communication beam617includes covering a discrete quantity of coverage areas and measuring a quality of signals received from first terminal620-1in each of the coverage areas. In some examples, dithering or adjusting the coverage area of communication beam617may be performed on a same set of signals received at antenna array605. That is, a communication beam signal may be generated based on applying a current set of beamforming coefficients to component signals from antenna array605for communication beam617, and additional sets of beamforming coefficients may be applied to stored versions of the component signals from antenna array605to determine an updated set of beamforming coefficients (e.g., used for determining subsequent communication beams signals). In some examples, the communications network determines that the quality of the signals received from first terminal620-1is highest within beam coverage area660-a. Accordingly, the communications network may configure the beam coefficients used to form communication beam617so that communication beam617covers beam coverage area660-a.

In some examples, second terminal620-2may be positioned within beam coverage area660-a. In such cases, the communications network may also communicate with second terminal620-2using communication beam617—e.g., using different time or frequency resources than first terminal620-1. Second terminal620-2may be separated from first terminal620-1by a distance, which may be referred to as d.

In some examples, the communications network may communicate with second terminal620-2using communication beam617based on identifying a position of second terminal620-2within beam coverage area660-arather than a different beam coverage area established within wide coverage area665—e.g., based on a preamble received from second terminal620-2. In some examples, after detecting second terminal620-2, beam coverage area660-a may be adjusted to increase (e.g., maximize) an average quality of signals received from both first terminal620-1and second terminal620-2—e.g., based on centering the beam coverage area660over a common point between first terminal620-1and second terminal620-2. In such cases, the quality of signals received from first terminal620-1may decrease while the quality of signals received from second terminal620-2may increase relative to a prior position of the beam coverage area660(e.g., the position of beam coverage area660-a). In some examples, the communications network may similarly dither the position of beam coverage area660to identify a preferred positioning of beam coverage area660that achieves a threshold signal quality from both first terminal620-1and second terminal620-2.

FIG.6Bshows a communications subsystem that supports beam management using sparse antenna arrays in accordance with examples described herein.

Communications subsystem600-adepicts techniques for adjusting a coverage area of a communication beam based on a changing position of a terminal using the communication beam. In some examples, the communications network adjusts the coverage area of communication beam617based on the position of first terminal620-1changing, which may be referred to as beam tracking. In some examples, based on a change in the position of first terminal620-1(e.g., by more than a threshold distance), the communications network may determine updated beam coefficients for communication beam617, which may result in communication beam617having beam coverage area660-b. Beam coverage area660-bmay encompass the latest position of first terminal620-1and signals received from first terminal using communication beam617may be receiving using the updated beam coefficients.

In some examples, first terminal620-1may periodically transmit channel sounding probes. The communications network may use the channel sounding probes to keep track of a position of first terminal620-1. In some examples, the communications network may use the tracked position of first terminal620-1to determine when to update a coverage area of communication beam617and for determining the updated set of beam coefficients.

In some examples, the adjusted coverage area of communication beam617may no longer encompass a second terminal that was previously encompassed by the original coverage area of communication beam617—e.g., based on communication beam617being used to track first terminal620-1, which may be referred to as a reference terminal. For example, beam coverage area660-bmay not encompass second terminal620-2. In other examples, a terminal within the original coverage area of communication beam617may move outside of the original coverage area. Techniques for managing communications with terminals that leave a coverage area of a communication beam or are left by the coverage area of the communication beam are described in more detail herein.

FIG.7Ashows a communications subsystem that supports beam management using sparse antenna arrays in accordance with examples described herein.

Communications subsystem700-adepicts techniques for adjusting a coverage area of a communication beam based on a changing position of a terminal using the communication beam. In some examples, the communications network adjusts the coverage area of communication beam717based on the position of second terminal720-2changing.

In some examples, second terminal720-2may move outside of an original coverage area of communication beam717. In some examples, the communications network may determine that second terminal720-2has moved outside of the original coverage area and may adjust a size of the coverage area of communication beam717to continue providing service to second terminal720-2. In some examples, the communications network determines updated beam coefficients that increase a coverage area of communication beam717, resulting in beam coverage area760-athat includes the position of first terminal720-1and second terminal720-2.

Despite increasing the coverage area of communication beam717to encompass second terminal720-2, communication beam717may stay focused on and track the position of first terminal720-1, which may be referred to as the reference terminal for communication beam717. Accordingly, in some examples, adjustments for the coverage area of communication beam717may be limited based on movements of other terminals, such as second terminal720-2, to maintain an acceptable service level for first terminal720-1.

FIG.7Bshows a communications subsystem that supports beam management using sparse antenna arrays in accordance with examples described herein.

Communications subsystem700-bdepicts techniques for adjusting a coverage area of a communication beam based on a changing position of a terminal using the communication beam. In some examples, the communications network adjusts the coverage area of communication beam717based on the position of second terminal720-2changing. In some examples, second terminal720-2may move outside of an original coverage area (e.g., first beam coverage area760-b-1) of communication beam717. In some examples, the communications network may determine that second terminal720-2has moved outside of the original coverage area and form second communication beam717-2having second beam coverage area760-b-2.

In some examples, second terminal720-2may be the reference terminal for second communication beam717-2, while first terminal720-1may be the reference terminal for communication beam717. Accordingly, in some examples, the communications network may adjust the coverage area of second communication beam717-2based on the current position of second terminal720-2—e.g., using beam tracking techniques.

Additionally, or alternatively, communications subsystem700-bmay depict techniques for adjusting a coverage area of a communication beam based on the utilization of the communication beam exceeding a threshold. In some examples, based on determining that the utilization of communication beam717has exceeded a threshold, the communications network may identify second terminal720-2as a reference terminal for a new communication beam, second communication beam717-2. Based on forming second communication beam717-2, the communications network may center communication beam717over first terminal720-1and may center second communication beam717-2over second terminal720-2.

In other examples, based on determining that the utilization of wide communication beam719has reached a threshold, the communications network may identify second terminal720-2as a reference terminal for a new communication beam—e.g., to further increase the capacity of the communications system for servicing the geographic region covered by wide coverage area765.

In some examples, when second communication beam717-2is formed, the communications network may manage the resources assigned to the different communication beams. For example, the communications network may allocate communication resources to second communication beam717-2that are orthogonal to the resources assigned to communication beam717—e.g., if second beam coverage area760-b-2overlaps with first beam coverage area760-b-1. Or the communications network may change the resources allocated to communication beam717to be orthogonal to the communication resources allocated to second communication beam717-2. In some examples, if the second beam coverage area760-b-2moves a certain distance away from first beam coverage area760-b-1(e.g., such that the beam coverage areas are no longer overlapping), overlapping resources may be assigned to communication beam717and second communication beam717-2.

FIG.8shows an example set of operations for beam management using sparse antenna arrays in accordance with examples described herein.

Flowchart800may be performed by a communications network (e.g., a satellite network), which may be examples of a communications system or subsystem described above with reference toFIGS.1through8. In some examples, flowchart800illustrates an exemplary sequence of operations performed to support beam management using sparse antenna arrays. For example, flowchart800depicts operations for activating narrow communication beams based on capacity parameters, for tracking terminals using communication beams, and for adjusting communication beams based on terminal movement.

One or more of the operations described in flowchart800may be performed earlier or later in the process, omitted, replaced, supplemented, or combined with another operation. Also, additional operations described herein may be included in flowchart800.

At820, the communications network may identify a presence of one or more terminals within one or more wide coverage areas of one or more wide communication beams. In some examples, the communications network identifies the presence of the one or more terminals based on preambles transmitted from the one or more terminals. The preambles may be received using one or more discovery beams. In some examples, the discovery areas of the discovery beams overlap with the coverage areas of the wide communication beams having similar boundaries. In other examples, the discovery areas of the discovery beams are different than the coverage areas of the wide communication beams e.g., having different diameters, different patterns, etc. In some examples, the communications network may determine a position (e.g., a rough position) of the terminals based on receiving the preambles using the discovery beams—e.g., based on positioning information included in the preambles, the boundaries of the discovery beam used to receive the preamble, etc.

At825, the communications network may communicate with the one or more terminals using the one or more wide communication beams. Within each wide communication beam, the communications network may communicate with multiple terminals. In some examples, the communications network determines which wide communications beams to use to communicate with which terminals based on the positioning information determined for the terminals. For example, the communications network may use a wide communication beam having a wide coverage area with boundaries that overlap with the boundaries of the discovery area of the discovery beam used to receive the preamble.

At830, the communications network may determine that a utilization of one or more wide communication beams has reached a threshold (e.g., greater than 80% or 90% capacity)—e.g., based on a quantity of terminals within the wide coverage area, service levels of the terminals within the wide coverage area, historical usage by the terminals within the wide coverage area, or a combination thereof.

At835, the communications network may form one or more narrow communication beams within the one or more wide communications beams that have reached a capacity threshold. In some examples, the communications network forms one or more narrow communication beams within a wide communication beam, such that centers of the beam coverage areas of the one or more narrow communication beams are within the boundaries of a wide coverage area of the wide communication beam. In some examples, the one or more narrow communication beams may be region-specific (e.g., formed to cover regions of high density of terminals), terminal-specific (e.g., formed to track a specific terminal), or some combination thereof. In some examples, the time, frequency, and polarization resources of the narrow beams within a wide communication beam are orthogonal to the time, frequency, and polarization resources of the wide communication beam. In some examples, the communications network simultaneously operates a wide communication beam and one or more narrow communication beams within the wide communication beam, the one or more narrow communication beams supplementing the capacity of the wide communication beam. In other examples, the communications network alternatively operates (e.g., in time) the wide communication beam or the one or more narrow communication beams to serve the geographic region covered by the wide coverage area. Thus, the communications network may reserve a set of communication resources (e.g., time, frequency, or polarization resources) across the wide coverage area for control signaling, such as preamble transmissions, channel sounding probe transmission, etc.

In some examples, forming the one or more narrow communication beams includes positioning the one or more narrow communications beams so that a quality of signals received from reference terminals associated with the one or more narrow communication beams are increased. For example, the communications system may dither a narrow communication beam around a rough position of a reference terminal for the narrow communication beam and select a beam coverage area for the narrow communication beam that is associated with signals received from the reference terminal having a highest quality.

At840, the communications network may adjust the narrow communication beam based on the position of the reference terminals within the one or more wide coverage areas. In some examples, the communications network may adjust the beam coverage areas of the one or more narrow communication beams based on movements of the corresponding reference terminals. For example, for a narrow communication beam that corresponds to a reference terminal, the communications network may adjust the coverage area of the communication beam to accommodate for movements by the reference terminal—e.g., using beam tracking techniques, such as enlarging the narrow communication beam, moving the narrow communication beam, etc.

Additionally, or alternatively, the communications network may form additional narrow communication beams based on the changing position of the reference terminals. The additional narrow communication beams may be linked with additional reference terminals.

FIG.9shows an example set of operations for beam management using sparse antenna arrays in accordance with examples described herein. Method900may be performed by components of an antenna array, ground system, or a combination thereof, which may be examples of a communications network (or components thereof) described with reference toFIGS.1and2. In some examples, a communications network may execute a set of instructions to control the functional elements of the communications network to perform the described functions. Additionally, or alternatively, the communications network may perform aspects of the described functions using special-purpose hardware.

At905, method900may include identifying a terminal within a geographic area. The operations of905may be performed in accordance with examples as disclosed herein. In some examples, aspects of the operations of905may be performed by a signal detector, as described herein and with reference toFIG.2.

At910, method900may include determining, for an antenna array, first beam coefficients to form a first beam for the terminal, a coverage area of the first beam encompassing the geographic area, wherein inter-element spacing of antennas of the antenna array is different across the antenna array. The operations of910may be performed in accordance with examples as disclosed herein. In some examples, aspects of the operations of910may be performed by a beam manager, as described as described herein and with reference toFIG.2.

At915, method900may include communicating with the terminal using the first beam. The operations of915may be performed in accordance with examples as disclosed herein. In some examples, aspects of the operations of915may be performed by a communications manager, as described as described herein and with reference toFIG.2.

At920, method900may include determining a utilization of the first beam has exceeded a threshold. The operations of920may be performed in accordance with examples as disclosed herein. In some examples, aspects of the operations of920may be performed by a beam manager, communications manager, or both, as described as described herein and with reference toFIG.2.

At925, method900may include determining, for the antenna array and based at least in part on the utilization of the first beam exceeding the threshold, second beam coefficients of a second beam, a coverage area of the second beam being different than the coverage area of the first beam. The operations of925may be performed in accordance with examples as disclosed herein. In some examples, aspects of the operations of925may be performed by a beam manager, as described as described herein and with reference toFIG.2.

At930, method900may include communicating with the terminal using the second beam. The operations of930may be performed in accordance with examples as disclosed herein. In some examples, aspects of the operations of930may be performed by a communications manager, as described as described herein and with reference toFIG.2.

In some examples, an apparatus as described herein may perform a method or methods, such as the method900. The apparatus may include, features, circuitry, logic, means, or instructions (e.g., a non-transitory computer-readable medium storing instructions executable by a processor) for identifying a terminal within a geographic region; determining, for an antenna array, first beam coefficients to form a first beam for the terminal, a coverage area of the first beam encompassing the geographic region, wherein inter-element spacing of antennas of the antenna array is different across the antenna array; communicating with the terminal using the first beam; determining a utilization of the first beam has exceeded a threshold; determining, for the antenna array and based at least in part on the utilization of the first beam exceeding the threshold, second beam coefficients of a second beam, a coverage area of the second beam being different than the coverage area of the first beam; and communicating with the terminal using the second beam.

In some examples, the apparatus may include, features, circuitry, logic, means, or instructions for forming the first beam based at least in part on the first beam coefficients, wherein the coverage area of the second beam has a center that is within the coverage area of the first beam.

In some examples, the apparatus may include, features, circuitry, logic, means, or instructions for identifying a plurality of terminals within the geographic region, the plurality of terminals comprising the terminal; and communicating with the plurality of terminals using the first beam, wherein the utilization of the first beam is determined as exceeding the threshold based at least in part on communicating with the plurality of terminals.

In some examples, a gain of the first beam is lower than a gain of the second beam.

In some examples, the apparatus may include, features, circuitry, logic, means, or instructions for identifying a plurality of terminals within the geographic region, the plurality of terminals comprising the terminal; and determining, for the antenna array, a plurality of beam coefficients to form a plurality of beams for the plurality of terminals having respective coverage areas with respective centers within the coverage area of the first beam, wherein the respective coverage areas of the plurality of beams correspond to respective positions of the plurality of terminals, and wherein the plurality of beam coefficients comprises the second beam coefficients.

In some examples, the apparatus may include, features, circuitry, logic, means, or instructions for reserving communication resources in the first beam for identifying additional terminals within the geographic region.

In some examples, the coverage area of the second beam corresponds to a position of the terminal, and the apparatus may include, features, circuitry, logic, means, or instructions for identifying a second terminal within the geographic region; and determining, for the antenna array, third beam coefficients to form a third beam for the second terminal, a coverage area of the third beam corresponding to a position of the second terminal.

In some examples, the apparatus may include, features, circuitry, logic, means, or instructions for receiving first positioning information for the terminal and second positioning information for the second terminal based at least in part on identifying the terminal and the second terminal, wherein the second beam coefficients and the third beam coefficients are determined based at least in part on the first positioning information and the second positioning information.

In some examples, the apparatus may include, features, circuitry, logic, means, or instructions for receiving first reference signals from the terminal and second reference signals from the second terminal based at least in part on identifying the terminal and the second terminal, wherein the second beam coefficients and the third beam coefficients are determined based at least in part on the first reference signals and the second reference signals.

In some examples, the apparatus may include, features, circuitry, logic, means, or instructions for communicating with the second terminal using the third beam, wherein communicating with the terminal using the second beam and with the second terminal using the third beam comprises: detecting a signal at the antenna array, the detected signal comprising respective components of a first signal transmitted from the terminal and detected at the antenna array and respective components of a second signal transmitted from the second terminal and detected at the antenna array; and applying the second beam coefficients to the detected signal to obtain a first beam signal for the terminal and the third beam coefficients to the detected signal to obtain a second beam signal for the second terminal.

In some examples, the apparatus may include, features, circuitry, logic, means, or instructions for determining a position of the antennas of the antenna array based at least in part on a first signal received from a first transmitter, a second signal received from a second transmitter, the position of the first transmitter, and the position of the second transmitter.

In some examples, the coverage area of the second beam corresponds to a position of the terminal, and the apparatus may include, features, circuitry, logic, means, or instructions for determining, for the antenna array and based at least in part on forming the second beam, third beam coefficients to adjust the coverage area of the second beam, an adjusted coverage area of the second beam corresponding to a second position of the terminal.

In some examples, the coverage area of the second beam has a first size based at least in part on the second beam coefficients and the adjusted coverage area of the beam has a second size based at least in part on the third beam coefficients.

In some examples, the apparatus may include, features, circuitry, logic, means, or instructions for identifying a second terminal within the coverage area of the second beam, wherein a position of the terminal is a first distance from a position of the second terminal; and determining, for the antenna array and based at least in part on identifying the second terminal, third beam coefficients associated with an adjusted coverage area of the second beam that is based at least in part on the position of the second terminal.

In some examples, the apparatus may include, features, circuitry, logic, means, or instructions for identifying a second terminal within the coverage area of the second beam, wherein a position of the terminal is a first distance from a position of the second terminal; determining a change in a distance between the position of the terminal and the position of the second terminal; and determining, for the antenna array, third beam coefficients that adjust a size of the coverage area of the second beam based at least in part on the change in the distance.

In some examples, the apparatus may include, features, circuitry, logic, means, or instructions for identifying a second terminal within the coverage area of the second beam, wherein a position of the terminal is a first distance from a position of the second terminal; determining a change in a distance between the position of the terminal and the position of the second terminal; determining, for the antenna array, third beam coefficients to form a third beam for the second terminal, a coverage area of the third beam corresponding to the position of the second terminal.

In some examples, the apparatus may include, features, circuitry, logic, means, or instructions for identifying a second terminal within the coverage area of the second beam; and communicating with the second terminal using the second beam.

In some examples, the apparatus may include, features, circuitry, logic, means, or instructions for applying, to a signal detected at the antenna array based at least in part on determining the first beam coefficients, a plurality of sets of beam coefficients, wherein a plurality of coverage areas are formed for the second beam in accordance with the plurality of sets of beam coefficients, each coverage area of the plurality of coverage areas covering a different geographic region, wherein the plurality of coverage areas comprises the coverage area of the second beam and the plurality of sets of beam coefficients comprises the second beam coefficients; determining, for each coverage area of the plurality of coverage areas, a signal quality of a signal transmitted from the terminal and received in respective beam signals associated with the plurality of sets of beam coefficients; and selecting the second beam coefficients based at least in part on the signal quality of the signal received according to the second beam coefficients relative to the signal quality of the signal received according to other sets of beam coefficients of the plurality of sets of beam coefficients.

In some examples, the signal quality of the signal is determined based at least in part on bit error rates of the signal, signal-to-noise ratios of the signal, signal-to-interference-plus-noise ratios of the signal, or a combination thereof.

In some examples, a system as described herein may perform a method or methods, such as the method900. The system may include a signal detector configured to identify a terminal within a geographic region; a beam manager determine, for an antenna array, first beam coefficients to form a first beam for the terminal, a coverage area of the first beam encompassing the geographic region, wherein inter-element spacing of antennas of the antenna array is different across the antenna array; a communications manager configured to communicate with the terminal using the first beam and determine a utilization of the first beam has exceeded a threshold, wherein the beam manager is further configured to determine, for the antenna array and based at least in part on the utilization of the first beam exceeding the threshold, second beam coefficients, and the communications manager is further configured to communicate with the terminal using the second beam.

In some examples of the system, the beam manager is further configured to form the first beam based at least in part on the first beam coefficients, wherein the coverage area of the second beam has a center that is within the coverage area of the first beam.

In some examples of the system, the signal detector is further configured to identify a plurality of terminals within the geographic region, the plurality of terminals comprising the terminal, and the communications manager is further configured to communicate with the plurality of terminals using the first beam, wherein the utilization of the first beam is determined as exceeding the threshold based at least in part on communicating with the plurality of terminals.

In some examples of the system, the signal detector is further configured to identify a plurality of terminals within the geographic region, the plurality of terminals comprising the terminal, and the beam manager is further configured to determine, for the antenna array, a plurality of beam coefficients to form a plurality of beams for the plurality of terminals having respective coverage areas with respective centers within the coverage area of the first beam, wherein the respective coverage areas of the plurality of beams correspond to respective positions of the plurality of terminals, and wherein the plurality of beam coefficients comprises the second beam coefficients.

In some examples of the system, the communications manager is further configured to reserve communication resources in the first beam for identifying additional terminals within the geographic region.

In some examples of the system, the coverage area of the second beam corresponds to a position of the terminal, the signal detector is further configured to identify a second terminal within the geographic region, and the beam manager is further configured to determine, for the antenna array, third beam coefficients to form a third beam for the second terminal, a coverage area of the third beam corresponding to a position of the second terminal.

In some examples, the system includes a positioning component configured to determine a position of the antennas of the antenna array based at least in part on a first signal received from a first transmitter, a second signal received from a second transmitter, the position of the first transmitter, and the position of the second transmitter.

In some examples of the system, the coverage area of the second beam corresponds to a position of the terminal, and the beam manager is further configured to determine, for the antenna array and based at least in part on forming the second beam, third beam coefficients to adjust the coverage area of the second beam, an adjusted coverage area of the second beam corresponding to a second position of the terminal.

In some examples of the system, the signal detector is further configured to identify a second terminal within the coverage area of the second beam, wherein a position of the terminal is a first distance from a position of the second terminal, and the beam manager is further configured to determine, for the antenna array and based at least in part on identifying the second terminal, third beam coefficients associated with an adjusted coverage area of the second beam that is based at least in part on the position of the second terminal.

In some examples of the system, the signal detector is further configured to identify a second terminal within the coverage area of the second beam, wherein a position of the terminal is a first distance from a position of the second terminal. The system may also include a positioning component configured to determine a change in a distance between the position of the terminal and the position of the second terminal, wherein the beam manager is further configured to determine, for the antenna array, third beam coefficients that adjust a size of the coverage area of the second beam based at least in part on the change in the distance.

In some examples of the system, the signal detector is further configured to identify a second terminal within the coverage area of the second beam, wherein a position of the terminal is a first distance from a position of the second terminal. The system may also include a positioning component configured to determine a change in a distance between the position of the terminal and the position of the second terminal, wherein the beam manager is further configured to determine, for the antenna array, third beam coefficients to form a third beam for the second terminal, a coverage area of the third beam corresponding to the position of the second terminal.

In some examples of the system, the signal detector is further configured to identify a second terminal within the coverage area of the second beam; and the communications manager is further configured to communicate with the second terminal using the second beam.

In some examples of the system, the beam manager is further configured to apply, to a signal detected at the antenna array based at least in part on determining the first beam coefficients, a plurality of sets of beam coefficients, wherein a plurality of coverage areas are formed for the second beam in accordance with the plurality of sets of beam coefficients, each coverage area of the plurality of coverage areas covering a different geographic region, wherein the plurality of coverage areas comprises the coverage area of the second beam and the plurality of sets of beam coefficients comprises the second beam coefficients; the signal detector is further configured to determine, for each coverage area of the plurality of coverage areas, a signal quality of a signal transmitted from the terminal and received in respective beam signals associated with the plurality of sets of beam coefficients; and the beam manager is further configured to select the second beam coefficients based at least in part on the signal quality of the signal received according to the second beam coefficients relative to the signal quality of the signal received according to other sets of beam coefficients of the plurality of sets of beam coefficients.

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