Patent Grant
10892549
The present disclosure relates generally to communications, and specifically to a phased-array antenna system.
Modern wireless communications implement a variety of different physical arrangements for associated antennae for transmitting and receiving wireless beams. One example is arranged as a phased-array antenna that includes an array of antenna elements. Each of the antenna elements can be configured to propagate (e.g., transmit or receive) a portion of the wireless beam, with the portion of the wireless beam being associated with time delay and amplitude of the wireless beam to provide beam steering of the wireless beam. For a received wireless beam, the received wireless beam portions can be combined and processed to determine a resultant wireless beam that can be digitized and processed (e.g., to determine data modulated therein). For a transmitted wireless beam, a digital beam can be generated and can be decomposed into respective analog portions that are provided to the antenna elements at the respective time delay and amplitude for transmission of the wireless beam. The process of transitioning between the digital beam and the wireless beam portions is called beamforming, which is typically performed by a beamforming processor that is coupled to the antenna elements by a large fan-out of conductors.
A phased-array antenna system includes antenna elements of an RF front-end that each propagate a wireless beam portion. A digital beamforming system generates a digital beam corresponding to the wireless beam that is transmitted or received from the phased-array antenna system. Digital beamforming processors are each associated with a proper subset of the antenna elements. The digital beamforming processors can be collectively configured to iteratively process digital beam portions of the digital beam in a plurality of iteration levels comprising a lowest iteration level associated with lowest-level digital beam portions corresponding to the respective wireless beam portions at each of the respective antenna elements and a highest iteration level associated with the digital beam. Each digital beam portion associated with a given iteration level includes a sum of lesser and relatively time-delayed digital beam portions from a next lower iteration level.
Another example includes a method for receiving a wireless beam via a phased-array antenna system. The method includes receiving a portion of the wireless beam at each of a plurality of antenna elements arranged in an array and associated with an RF front-end. The method also includes converting the portion of the wireless beam associated with each of the antenna elements to a respective lowest-level digital beam portion via a respective plurality of analog-to-digital converters (ADC). The method also includes adding the lowest-level digital beam portion associated with each of a plurality of proper subsets of the antenna elements via each of a plurality of digital beamforming processors to generate a plurality of digital beam portions at a lowest iteration level of an iterative processing of the wireless beam. The method also includes iteratively adding the digital beam portions via the digital beamforming processors in a plurality of iteration levels comprising the lowest iteration level and a highest iteration level. Each digital beam portion associated with a given iteration level includes a sum of lesser and relatively time-delayed digital beam portions from a next lower iteration level of the iterative processing. The method further includes adding the digital beam portions associated with the highest iteration level to generate a digital beam corresponding to the wireless beam.
Another example includes a method for transmitting a wireless beam via a phased-array antenna system. The method includes generating a digital beam corresponding to a wireless beam to be transmitted from the phased-array antenna system. The method includes distributing digital beam portions from the digital beam at a highest iteration level of a plurality of iteration levels of an iterative processing of the digital beam via a plurality of digital beamforming processors. The method also includes iteratively distributing the digital beam portions via the digital beamforming processors in a plurality of iteration levels comprising the highest iteration level and a lowest iteration level. Each digital beam portion associated with a given iteration level is distributed from the given iteration level as a plurality of lesser digital beam portions with relatively different time-delays to a next lower iteration level of the iterative processing with the lesser digital beam portions being equal in aggregate to the respective digital beam portion. The method also includes distributing a plurality of digital beam portions to generate a plurality of lowest-level digital beam portions associated with each of a plurality of antenna elements via each of the plurality of digital beamforming processors the lowest iteration level of the iterative processing of the digital beam. The method further includes converting the lowest-level digital beam portions to wireless beam portions associated with each of the respective antenna elements via a respective plurality of digital-to-analog converters (DAC), and transmitting the wireless beam portions from each of the respective plurality of antenna elements as the wireless beam.
The present disclosure relates generally to communications, and specifically to a phased-array antenna system. The phased-array antenna system can be implemented in any of a variety of communications applications that implement beam steering or multi-directional signal receipt. The phased-array antenna system includes a radio frequency (RF) front-end that includes an array of antenna elements that can each be configured to propagate a wireless beam portion. As described herein, the term “propagate” with respect to the wireless beam and to wireless beam portions is intended to refer to either signal transmission or receipt, such that the phased-array antenna system can both transmit and receive wireless beams. The wireless beam portions can thus have different phase and/or amplitude components that can correspond to beamforming of the wireless beam, such as for transmitting the wireless beam in a predetermined direction from the phased-array antenna system or for processing a source from which the wireless beam was received by the phased-array antenna system.
The phased-array antenna system also includes a digital beamforming system that is configured to generate a digital beam. As an example, the digital beam can include modulated data therein. The digital beam can correspond to the wireless beam that is transmitted from or received at the RF front-end, and can be generated to have the corresponding time delay and amplitude components that can be associated with the beamforming of the wireless beam. The phased-array antenna system also includes a digital signal conditioner system that is configured to provide signal conditioning and analog/digital conversion of the respective digital beam/wireless beam. For example, the signal conditioning can include tuning, filtering, decimation, and/or time-alignment of portions of the digital beam, and can also include analog-to-digital converters (ADCs) to convert a received analog wireless beam to the digital beam and digital-to-analog converters (DACs) to convert the digital beam to the analog wireless beam for transmission.
In addition, the digital beamforming system includes a plurality of digital beamforming processors. The digital beamforming processors can be distributed across the array of antenna elements, such that each of the digital beamforming processors can be associated with a proper subset of the antenna elements. Therefore, each of the digital beamforming processors can be communicatively coupled to a portion of the antenna elements to process a lowest-level digital beam portion associated with each of the corresponding antenna elements in the proper subset. As described herein, the term “process” refers to additive combination (e.g., for a received wireless beam) or distribution (e.g., for a transmitted wireless beam) of digital beam portions of the digital beam at each of a plurality of iteration levels, between the lowest-level digital beam portions associated with each of the respective antenna elements and the digital beam that is an aggregate of all of the lowest-level digital beam portions. At each iteration level, time-delay information can be applied to the respective digital beam portion for each of the iterative groups of antenna elements to perform iterative beamforming.
For example, as described in greater detail herein, the application of time-delay in the receive direction is related to time-delaying a given lower-iteration level digital beam portion to be time-aligned to at least one of the other lower-iteration level digital beam portions (e.g., to the digital beam portion most delayed in arrival based on the beam direction of the received wireless beam) that form a given next higher-iteration level digital beam portion. As a result, for example, the digital beam portion of a set of digital beam portions that is most time-delayed corresponds to the portions of the antenna array that are closest in direction to a source from which the received wireless beam was transmitted. Similarly, as also described in greater detail herein, the application of time-delay in the transmit direction is related to separately time-delaying each lower-iteration level digital beam portion relative to each other. As a result, for example, the digital beam portion of a set of digital beam portions that is most time-delayed corresponds to the portions of the antenna array that are closest in direction to a direction to which the wireless beam is to be transmitted. As another example, time-delays associated with the lowest-level digital beam portions at the antenna element level can be accomplished with phase-shifts of the digital or analog signals associated with the antenna elements relative to each other, such as to approximate a time-delay over a limited frequency range. Additionally, while the examples of applying time-delay above can correspond to processing a flat plane wave at the digital beamforming system, it is to be understood that the time-delays of digital beam portions can be provided in a variety of different ways for the purpose of beamforming. While a relative time-delay is described herein throughout, it is also to be understood that amplitude information can also be applied to each of the digital beam portions in each of the iteration levels. As described herein, the term “distribute” and forms thereof refer to portioning a given digital beam portion associated with a given iteration level from a digital beamforming processor as multiple digital beam portions to respective different digital beamforming processors.
As described in greater detail herein, the digital beamforming processors can collectively iteratively process the digital beam portions of the digital beam in a plurality of iteration levels. The iteration levels can include a lowest iteration level associated with the lowest-level digital beam portions associated with each of the respective antenna elements, can include a highest iteration level associated with the digital beam itself, and can include at least one iteration level therebetween. Each digital beam portion associated with a given iteration level can therefore include a sum of lesser digital beam portions from a next lower iteration level. By providing the iterative processing of the digital beam portions associated with the digital beam, the phased-array antenna system can therefore more efficiently provide beamforming for the digital beam, as opposed to distributing the beamforming component signals to one processor from each individual antenna element.
In the example of
The phased-array antenna system 10 also includes a digital beamforming system 16 that is configured to generate a digital beam, demonstrated in the example of
The phased-array antenna system 10 also includes a digital signal conditioner system 18 that is configured to provide signal conditioning and analog/digital conversion between the respective digital beam DB and the wireless beam WB. In the example of
In addition, the digital signal conditioner system 18 includes a plurality of digital beamforming processors (“DBF PROCESSORS”) 22. For example, the digital beamforming processors 22 can be configured as any of a variety of processing devices, such as processors, application specific integrated circuit (ASICs), field-programmable gate arrays (FPGAs), or other types of processing devices. The digital beamforming processors 22 can be distributed in an array across the array of antenna elements 14, such that each of the digital beamforming processors 22 can be associated with a proper subset of the antenna elements 14. Therefore, each of the digital beamforming processors 22 can be communicatively coupled to a portion of the antenna elements 14 to process a respective lowest-level digital beam portion associated with each of the corresponding antenna elements 14 in the proper subset. As described in greater detail herein, the digital beamforming processors 22 can collectively iteratively process digital beam portions of the digital beam DB in a plurality of iteration levels. The iteration levels can include a lowest iteration level associated with the lowest-level digital beam portions corresponding to each of the respective antenna elements 14, can include a highest iteration level associated with the digital beam DB, and can include at least one iteration level therebetween.
Each digital beam portion associated with a given iteration level can include an aggregate of lesser digital beam portions from a next lower iteration level. For example, each digital beam portion is associated with a plurality of lowest-level digital beam portions corresponding to a subset of the antenna elements 14. Therefore, the digital beam portion associated with a given iteration level includes a subset of the antenna elements 14 that is greater than the subset of the antenna elements 14 associated with the next lower iteration level of the iterative processing. Additionally, at each iteration level, the digital beamforming processors 22 can add or apply time-delay information to the respective digital beam portion for each of the successive iterative groups of antenna elements 14 to perform iterative beamforming. Such iterative application of time-delay in each of the iteration levels provides for efficient processing by the digital beamforming processors based on the time-delay being relatively very close in value for physically proximal antenna elements 14, as opposed to time-delay values for relatively distal antenna elements 14. In other words, for any given beam direction, the required amount of time-delay for the digital beamforming is similar for the antenna elements 14 that are physically close to each other, while the delay difference is the greatest for antenna elements 14 that are physically far apart. By providing the iterative processing of the digital beam portions associated with the digital beam DB, the phased-array antenna system 10 can therefore more efficiently provide beamforming for the digital beam DB, as opposed to distributing the beamforming component signals from one processor to each individual antenna element 14.
Furthermore, the digital signal conditioner system 18 can include a plurality of separate frequency channels that are each associated with a separate respective frequency. Each of the frequency channels can be coupled to each of the plurality of digital beamforming processors 22, such that the iterative beamforming described herein can be concurrently implemented on multiple different signals each having a separate respective frequency. For example, the digital beam portions DBP from the highest iteration level or the lowest-level digital beam portions LDBP from the lowest iteration level can be frequency converted to different frequency bands, and a different time-delay can be applied for each antenna element 14. Additionally or alternatively, the phased-array antenna system 10 can be configured to concurrently process multiple wireless beams WB having similar or the same frequency bands that can be provided towards or received from different directions based on the wireless beam portions WBP having different time delay and/or amplitude components for each antenna element 14. For example, the different signals may be at the same or different frequency bands, and the separate wireless beams WB can be distributed to each of the respective antenna elements 14, at which each resultant wireless beam portion WBP can have a different delay at any one antenna element 14. The delayed wireless beam portions WBP for the separate wireless beams WB can be summed prior to being output through each respective one antenna element 14, with different delays for the separate respective wireless beam portions WBP of the separate respective wireless beams WB. Furthermore, the phased-array antenna system 10 can be configured to iteratively process the digital beam portions for both transmitted and received wireless beams, respectively, in a concurrent manner based on the conductive connections between the digital beamforming processors 22, as described in greater detail herein.
The diagram 50 demonstrates a plurality N of iteration levels of iterative processing, where N is a positive integer greater than or equal to two. The iteration levels include a first iteration level 54, demonstrated as “LEVEL 1 ARRAY PROCESSING”, a second iteration level 56, demonstrated as “LEVEL 2 ARRAY PROCESSING”, and an Nth iteration level 58, demonstrated as “LEVEL N ARRAY PROCESSING”. It is to be understood that the digital beamforming processors 52 can implement additional iteration levels between the second iteration level 56 and the Nth iteration level 58. In the example of
As an example, for a received wireless beam WB, each of the antenna elements 14 can provide a respective wireless beam portion that is associated with the amplitude and relative time-delay of the respective wireless beam WB. The wireless beam portions can each be digitized (e.g., via the ADCs 20 associated with the digital signal conditioner system 18) to generate lowest-level digital beam portions LDBP that are digital equivalents of the wireless beam portions. The digital beamforming processors 52 can thus apply a respective time-delay between the lowest-level digital beam portions LDBP of a given set of antenna elements 14 and add each of the lowest-level digital beam portions LDBP of the plurality of sets of lowest-level digital beam portions LDBP in the first iteration level 54 to generate first iteration level digital beam portions DBP1. As an example, a relative time-delay can be assigned to each of the first iteration level digital beam portions DBP1, such as corresponding to a lowest time-delay of the individual antenna elements 14 of the set of antenna elements 14 associated with the respective first iteration level digital beam portion DBP1. Each of the first iteration level digital beam portions DBP1 can correspond to a sum of the lowest-level digital beam portions LDBP associated with a given proper subset of the antenna elements 14. For example, each of the digital beamforming processors 52 is configured to generate a respective first iteration level digital beam portion DBP1. As another example, each of the proper subsets of the antenna elements 14 can be approximately equal with respect to a quantity of antenna elements 14.
In the example of
The digital beamforming processors 52 can thus continue to iteratively apply respective time-delays to digital beam portions DBPX and add successive digital beam portions DBPX, where X corresponds to a given iteration level. For example, a different set of the digital beamforming processors 52 can be configured to add the digital beam portions DBPX from a given iteration level relative to the other iteration levels, such that a given one of the digital beamforming processors 52 does not generate digital beam portions DBP from more than two separate iteration levels (e.g., the first iteration level 54 and one other iteration level). In the example of
The digital beam DB can be provided to the digital beamforming system 16 to process the digital beam DB corresponding to the wireless beam WB. For example, the digital beamforming system 16 can process the data associated with the digital beam DB to provide the time delay and amplitude information associated with the wireless beam portions WBP associated with each of the antenna elements 14. Therefore, the beamforming information associated with the digital beam DB, as determined by the digital beamforming system 16 can facilitate demodulation of the data in the digital beam DB, such as in the receive direction for signal detection, signal characterization, radar image processing, and/or other receiver applications. Additionally, as described previously, the digital beam portions at each of the iteration levels can correspond to beamforming of multiple digital beams DB each having a separate respective frequency, such as for concurrent transmission, reception, or a combination of transmission and reception of multiple respective wireless beams.
As an example, the iterative processing of the digital beamforming processors 52 can be substantially reversed for transmitting the wireless beam WB. For example, the digital beamforming system 16 can generate the digital beam DB based on desired beamforming characteristics associated with a desired direction of wireless beam WB to be transmitted. The digital beam DB can therefore be provided to one of the digital beamforming processors 52 that is configured to distribute the digital beam portions DBPN-1 from the digital beam DB in the Nth iteration level 58. For example, the digital beamforming processors 52 can distribute the digital beam portions DBPN-1 and can apply relatively different time delays to each of the digital beam portions DBPX in each of the successive iteration levels for steering the wireless beam WB in a desired direction. In the example of transmission of multiple wireless beams WB from the phased-array antenna system 10, the digital beamforming processors 52 can receive the digital beam portions DBPN-1 for each of multiple digital beams DB for different transmission directions, apply multiple time delays associated with the different directions and different antenna elements 14, and sum the time-delayed wireless beam portions WBP that ultimately are provided to a particular antenna element 14.
Each of the digital beam portions DBPN-1 are provided to a separate one of the digital beamforming processors 52 to implement processing in the N-1 iteration layer. The digital beamforming processors 52 can thus continue to iteratively distribute successive digital beam portions DBPX with a different set of the digital beamforming processors 52 for distributing the digital beam portions DBPX from a given iteration level relative to the other iteration levels. For example, at each successive iteration level, the digital beamforming processors 52 can apply a different relative time-delay to each of the different digital beam portions DBPX, such as a lowest time-delay associated with a given one of the antenna elements 14 relative to the other antenna elements 14 in the respective corresponding sets of antenna elements 14 of the respective digital beam portions DBPX. At the first iteration level 54, the respective lowest-level digital beam portions LDBP can be distributed from each of the digital beam portions DBP1 by each of the respective digital beamforming processors 52, with each of the lowest-level digital beam portions LDBP having a respective relative time-delay for transmission of the respective corresponding wireless beam portions WBP. The lowest-level digital beam portions LDBP can be converted to the analog wireless beam portions (e.g., by the DACs 20 in the example of
The iterative level processing between the digital beam DB and the lowest-level digital beam portions LDBP, as described in the example of
The example of
The example of
In the example of receiving the wireless beam WB, in the lowest iteration level of the example of
Similarly, in the example of transmitting the wireless beam WB, in the lowest iteration level of the example of
The example of
In the example of receiving the wireless beam WB, in the second iteration level of the example of
Similarly, in the example of transmitting the wireless beam WB, in the second iteration level of the example of
The example of
In the example of receiving the wireless beam WB, in the third iteration level of the example of
Similarly, in the example of transmitting the wireless beam WB, in the third iteration level of the example of
The example of
In the example of receiving the wireless beam WB, in the third iteration level of the example of
Similarly, in the example of transmitting the wireless beam WB, in the fourth iteration level of the example of
The iterative processing of the examples of
By shifting the burden of processing of the digital beam DB to the digital beamforming processors 52, instead of providing all of the processing of the digital beam DB at the digital beamforming system 16, the operation of the digital beamforming processors 52 provides a more efficient manner of processing the digital beam DB for transmission or receipt of the wireless beam WB. Accordingly, the processing of the digital beam DB by the digital beamforming processors 52 can substantially mitigate a potential processing bottleneck that is provided by the digital beamforming system 16. Additionally, by implementing the digital beamforming processors 52 as distributed across the RF front-end 12 with respect to the antenna elements 102, the phased-array antenna system 10 can have a significantly more efficient design by mitigating the interconnects between the digital beamforming system 16 and each of the individual antenna elements 102, as is provided in typical phased-array antenna systems.
Furthermore, the digital beamforming system 16 can communicate with one or more of the digital beamforming processors 52, such as associated with processing some of the higher iteration levels of the iterative processing. Thus, the digital beamforming system 16 can effectively monitor the iterative processing to determine sufficiency of a given digital beam DB (e.g., in response to receiving a wireless beam WB). For example, the digital beamforming system 16 can monitor a higher iteration level (e.g., at one or more of the respective digital beamforming processors 52) to determine if a given received wireless beam WB satisfies certain predetermined criteria. If the digital beam DB is not determined to satisfy the predetermined criteria at the given iteration level, and is therefore not a signal of interest to the phased-array antenna system 10, then the digital beamforming system 16 can cease processing of the digital beam DB, such as to conserve bandwidth and/or processing overhead of the digital beamforming processors 52.
As another example, at the higher levels of iteration, the digital beamforming processors 52 may implement the time-delays with larger resolution (e.g., less precision), which can be implemented at a lower digital sample rate. As a result, each physical delay element can implement a larger delay with fewer memory elements. At the lower iteration levels, the sample rate may be increased, or possibly only the lowest iteration level will have a higher sample rate, to achieve a fine resolution for the time-delay. As yet another example, instead of increasing the sample rate at that lowest iteration level, the lowest iteration could use a phase shift (e.g., as an approximation for a time-delay for a narrow frequency band). Accordingly, the beamforming system could implement hybrid phase-shifts (e.g., at lowest iteration level) and time-delays (e.g., at higher iteration levels) to efficiently implement the beam-steering. Accordingly, for these reasons described herein, the phased-array antenna system 10 can provide for a more efficient and effective design for beamforming of a wireless beam WB.
In the example of
In the example of
In the example of
As a result of the conductive coupling of the most proximal digital beamforming processors 52 with respect to each other, the digital beamforming processors 52 are configured to provide digital beam portions to most proximal digital beamforming processors 52 for a most proximal digital beamforming processor 52 to perform a next iteration level processing of the iterative processing. Additionally, some digital beamforming processors 52 can be communicatively coupled to another digital beamforming processor 52 to pass a processed digital beam portion (e.g., distributed or added) to the other digital beamforming processor 52 to perform a next iteration level processing. In the example of
The digital beamforming processors in the diagram 400 are demonstrated as having a designation “DBF-PN_M”, where “N” corresponds to which of the sets of digital beamforming processors 402, 412, 422, and 432 that the digital beamforming processor belongs and “M” corresponds to an individual designation within the respective set of digital beamforming processors. Each of the digital beamforming processors in the diagram 400 can be associated with a respective proper subset of antenna elements. For example, each of the digital beamforming processors in the diagram 400 can be communicatively coupled to four separate antenna elements 102 of the array of antenna elements, such that each of the digital beamforming processors can be associated with one of the proper subsets 152 in the example of
In the example of
In a second iteration level corresponding to a next iteration level of the iterative processing, some of the first iteration level digital beam portions are added together to generate second iteration level digital beam portions. In the example of
In a third iteration level corresponding to a next iteration level of the iterative processing, some of the second iteration level digital beam portions are added together to generate third iteration level digital beam portions. In the example of
In a fourth iteration level corresponding to a next iteration level of the iterative processing, some of the third iteration level digital beam portions are added together to generate fourth iteration level digital beam portions. In the example of
In a fifth iteration level corresponding to a next iteration level of the iterative processing, some of the fourth iteration level digital beam portions are added together to generate a fifth iteration level digital beam portion. In the example of
Therefore, the example of
In view of the foregoing structural and functional features described above, example methods will be better appreciated with reference to
What has been described above are examples. It is, of course, not possible to describe every conceivable combination of components or methodologies, but one of ordinary skill in the art will recognize that many further combinations and permutations are possible. Accordingly, the disclosure is intended to embrace all such alterations, modifications, and variations that fall within the scope of this application, including the appended claims. As used herein, the term “includes” means includes but not limited to, the term “including” means including but not limited to. The term “based on” means based at least in part on. Additionally, where the disclosure or claims recite “a,” “an,” “a first,” or “another” element, or the equivalent thereof, it should be interpreted to include one or more than one such element, neither requiring nor excluding two or more such elements.
The invention was made under Government Contract. Therefore, the US Government has rights to the invention as specified in that contract.
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