Ultrawideband sidelobe suppression using complementary golay pair transmission

Abstract

A method is provided for ultrawideband sidelobe suppression using complementary Golay pair transmissions. Transmitting an ultrawideband (UWB) Multi-Millisecond Ranging Sequence (MMRS) signal includes repeatedly transmitting a first Golay pair that includes a first code and a second code, and repeatedly transmitting a second Golay pair, where the second Golay pair includes the first code and minus the second code.

Description

Attorney Docket No.: 62306.202W001ULTRA WIDEBAND SIDELOBE SUPPRESSION USING COMPLEMENTARY GOLAY PAIR TRANSMISSION RELATED APPLICATIONS

[0001] The present application claims the benefit of U.S. Provisional Application No. 63 / 754,266, filed February 05, 2025, which is incorporated herein by reference in its entirety TECHNICAL FIELD

[0002] The subject matter described herein relates to devices, systems, and methods for suppressing ultrawideband transmission sidelobes via the transmission of alternating, complementary Golay pair symbols. This complementary Golay pair sidelobe suppression system has particular but not exclusive utility for ultrawideband communications and ranging.BACKGROUND

[0003] Ultrawideband (UWB) communications, using short pulses of radio waves across a very wide bandwidth, are increasingly important for military and civilian applications. UWB ranging is a wireless positioning technology based on the Institute for Electrical and Electronics Engineers (IEEE) 802.15.4ab standard, that uses time-of-flight for radio pulses to allow devices to measure the distance between one another with accuracy in the centimeter range. Multi -millisecond (MMS) ranging occurs when a signal is broken into N fragments, transmitted at one-millisecond intervals until all N fragments have been transmitted.

[0004] In a UWB MMS ranging operation, each Ranging Sequence Fragment (RSF) may consist of a repetition of a Multi-Millisecond Ranging Sequence (MMRS) symbol with a strong autocorrelation peak, to aid in synchronizing the receiver to the transmitted signal pulses. There is a continual need for MMRS symbols that are designed with reduced autocorrelation sidelobes to increase first path detection sensitivity, particularly in cluttered environments, and reducing false first path detections.

[0005] The information included in this Background section of the specification, including any references cited herein and any description or discussion thereof, is included for technical reference purposes only and is not to be regarded as subject matter by which the scope of the disclosure is to be bound.Attorney Docket No.: 62306.202W001SUMMARY

[0006] Disclosed is a complementary Golay pair sidelobe suppression system that, instead of broadcasting repetitions of a single Golay pair AGBG, defines a complementary Golay pair AGCG, where C = -B, and alternates the pairs AGBG and ACGC to increase the zero correlation zone of the MMRS. The complementary Golay pair sidelobe suppression system disclosed herein has particular, but not exclusive, utility for ultrawideband communications and ranging.

[0007] A system of one or more computers can be configured to perform particular operations or actions by virtue of having software, firmware, hardware, or a combination of them installed on the system that in operation causes or cause the system to perform the actions. One or more computer programs can be configured to perform particular operations or actions by virtue of including instructions that, when executed by data processing apparatus, cause the apparatus to perform the actions. One general aspect includes a method for transmitting an ultrawideband (UWB) multi-millisecond ranging sequence (MMRS) signal. The method includes repeatedly transmitting a first Golay pair that includes a first code and a second code, and repeatedly transmitting a second Golay pair, where the second Golay pair includes the first code and minus the second code. Other embodiments of this aspect include corresponding computer systems, apparatus, and computer programs recorded on one or more computer storage devices, each configured to perform the actions of the methods.

[0008] Implementations may include one or more of the following features. In some embodiments, repeatedly transmitting the second Golay pair is sequential with repeatedly transmitting the first Golay pair. In some embodiments, repeatedly transmitting the second Golay pair is interleaved with repeatedly transmitting the first Golay pair. In some embodiments, repeatedly transmitting the first Golay pair and the second Golay pair occurs within a single multi-millisecond ranging sequence (MMRS). In some embodiments, repeatedly transmitting the first Golay pair occurs within a first MMRS, and repeatedly transmitting the second Golay pair occurs within a second MMRS. In some embodiments, repeatedly transmitting the first Golay pair and the second Golay pair occurs within a single ranging sequence fragment (RSF). In some embodiments, repeatedly transmitting the first Golay pair occurs within a first RSF, and repeatedly transmitting the second Golay pair occurs within a second RSF. In some embodiments, repeatedly transmitting the first Golay pair and the second Golay pair results in fewer sidelobes than repeatedly transmitting only theAttorney Docket No.: 62306.202W001first Golay pair or repeatedly transmitting only the second Golay pair. In some embodiments, the first Golay pair is transmitted an equal number of times as the second Golay pair.Implementations of the described techniques may include hardware, a method or process, or computer software on a computer-accessible medium.

[0009] One general aspect includes transmitter circuitry that includes a processor configured to transmit an ultrawideband (UWB) multi-millisecond ranging sequence (MMRS) signal including: repeatedly transmitting a first Golay pair may include a first code and a second code; and repeatedly transmitting a second Golay pair, where the second Golay pair may include the first code and minus the second code. Other embodiments of this aspect include corresponding computer systems, apparatus, and computer programs recorded on one or more computer storage devices, each configured to perform the actions of the methods.

[0010] Implementations may include one or more of the following features. In some embodiments, repeatedly transmitting the second Golay pair is sequential with repeatedly transmitting the first Golay pair. In some embodiments, repeatedly transmitting the second Golay pair is interleaved with repeatedly transmitting the first Golay pair. In some embodiments, repeatedly transmitting the first Golay pair and the second Golay pair occurs within a single multi-millisecond ranging sequence (MMRS) or ranging sequence fragment (RSF). In some embodiments, repeatedly transmitting the first Golay pair occurs within a first MMRS or RSF, and repeatedly transmitting the second Golay pair occurs within a second MMRS or RSF. In some embodiments, the first Golay pair is transmitted an equal number of times as the second Golay pair. Implementations of the described techniques may include hardware, a method or process, or computer software on a computer-accessible medium.

[0011] One general aspect includes an ultrawideband transmitter that includes a memory. The transmitter also includes ultrawideband base band transmitter circuitry. The transmitter also includes a processor configured to read the memory and control the ultrawideband base band transmitter circuitry to: repeatedly transmit a first Golay pair that includes a first code and a second code; and repeatedly transmit a second Golay pair, where the second Golay pair includes the first code and minus the second code, such that the first Golay pair is transmitted an equal number of times as the second Golay pair. The transmitter also includes a radio frequency front end. The transmitter also includes an antenna. Other embodiments of this aspect include corresponding computer systems, apparatus, and computer programs recorded on one or more computer storage devices, each configured to perform the actions of the methods.Attorney Docket No.: 62306.202W001

[0012] Implementations may include one or more of the following features. In some embodiments, repeatedly transmitting the second Golay pair is sequential with repeatedly transmitting the first Golay pair. In some embodiments, repeatedly transmitting the second Golay pair is interleaved with repeatedly transmitting the first Golay pair. In some embodiments, repeatedly transmitting the first Golay pair and the second Golay pair occurs within a single multi-millisecond ranging sequence (MMRS) or ranging sequence fragment (RSF). In some embodiments, repeatedly transmitting the first Golay pair occurs within a first MMRS or RSF, and repeatedly transmitting the second Golay pair occurs within a second MMRS or RSF. Implementations of the described techniques may include hardware, a method or process, or computer software on a computer-accessible medium.

[0013] This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to limit the scope of the claimed subject matter. A more extensive presentation of features, details, utilities, and advantages of the complementary Golay pair sidelobe suppression system, as defined in the claims, is provided in the following written description of various embodiments of the disclosure and illustrated in the accompanying drawings.BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Illustrative embodiments of the present disclosure will be described with reference to the accompanying drawings, of which:

[0015] Figure 1 is a diagram illustrating a two-way ranging-based localization system that uses UWB communications, in accordance with at least one embodiment of the present disclosure.

[0016] Figure 2 illustrates an exemplary transmission frame that may be used for ranging, in accordance with at least one embodiment of the present disclosure.

[0017] Figure 3 illustrates an exemplary set of transmissions that may be used for ranging, in accordance with at least one embodiment of the present disclosure.

[0018] Figure 4 illustrates, in block diagram form, a mobile device for generating multiple timing and carrier slices, in accordance with at least one embodiment of the present disclosure.

[0019] Figure 5 is a time -domain graph showing a typical Channel Impulse Response (CIR) of an additive white Gaussian noise (AWGN) channel when channel sounding isAttorney Docket No.: 62306.202W001obtained using a Golay pair, in accordance with at least one embodiment of the present disclosure.

[0020] Figure 6 is a time-domain graph showing the Channel Impulse Response (CIR) of Figure 5, but in a multipath environment where the primary signal path is attenuated (e.g., partially blocked by an obstacle), and where the signal reflects off of multiple objects at different positions before arriving at the receiver, in accordance with at least one embodiment of the present disclosure.

[0021] Figure 7 is a time-domain graph showing the periodic auto-correlation functions of AGBG 702 and AGCG 704, where A is code 1 and B = -C = code 2, in accordance with at least one embodiment of the present disclosure.

[0022] Figure 8 is a time-domain graph showing the auto-correlation function of the original Golay pair and the combination of complementary Golay pairs, in accordance with at least one embodiment of the present disclosure.

[0023] Figure 9 is a schematic, diagrammatic representation, in flow diagram form, of an example complementary Golay pair sidelobe suppression method, in accordance with at least one embodiment of the present disclosure.

[0024] Figure 10 is a schematic diagram of a processor circuit, in accordance with at least one embodiment of the present disclosure.DETAILED DESCRIPTION

[0025] A Golay pair may refer to two binary sequences whose aperiodic autocorrelations sum to zero in all out-of-phase positions. Golay pairs have been used in many digital communication systems, including radar, optical time domain reflectometry, and medical ultrasound, and are useful for synchronization of transmitted signals by a receiver. However, the periodic autocorrelations only sum to zero within a zero-correlation zone (ZCZ), outside of which, sidelobes may occur.

[0026] In many cases, the MMRS consists of two codes which form a Golay pair, A and B. These Golay pairs may for example be derived using recursive logic functions that are known in the art. A ten-bit example Golay pair is A = (+1, +1, -1, +1, -1, +1, -1, -1, +1, + 1) and B = (+1, +1, -1, +1, +1, +1, +1, +1, -1, -1), with their autocorrelation functions being (10, -3, 0, -1, 0, 1,-2, -1, 2, 1) and (10, 3, 0, 1, 0, -1, 2, 1, -2, -1), respectively. An optional gap G may be inserted after both A and B. In some embodiments, the resultant code AGBG is then spread by a spreading factor of, e.g., L=4 to generate the symbol.Attorney Docket No.: 62306.202W001

[0027] However, the periodic auto-correlation function of the symbol AGBG contains sidelobes that can be as high as -13.2 dB relative to the signal power. When the signal’s time-of-flight exceeds the Golay Pair’s zero correlation zone, these strong sidelobes may mask early attenuated first path signals, especially in a multipath environment with strong delayed reflections. This can complicate the process of calculating the arrival time of the transmitted signal. Accordingly, a need exists for improved UWB MMRS ranging methods that address the forgoing and other concerns.

[0028] In accordance with at least one embodiment of the present disclosure, a complementary Golay pair sidelobe suppression system is provided which removes sidelobes that otherwise may mask early attenuated first path signals. Consequently, the proposed technique increases the First Path (FP) detection sensitivity in cluttered environments and reduces false FP detections, improving overall performance. Instead of MMRS symbols consisting only of repetitions of AGBG, the symbols instead alternate AGBG with and AGCG, where A is code 1 and B = -C = code 2. Codes B and C may be referred to as the additive inverses of each other, such that B+C=0. For example, C may be referred to as an additive inverse of B, or a negative of B, or an opposite of B, or minus B, as is known in the art. The periodic and non-periodic autocorrelation sidelobes of AGCG are inverted with respect to those of AGBG, and can thus be cancelled by the disclosed method, allowing a longer zero-correlation zone (ZCZ) and the use of one additional symbol in the CIR estimation. Combined AGBG and AGCG symbols for channel sounding can thus be used to obtain a combined auto-correlation function without sidelobes,

[0029] According to the IEEE 802.15.4z standard, the multi -millisecond ranging sequence (MMRS) may be repeated at least 32 times to form a single ranging sequence fragment (RSF). Because any AGBG symbol is complementary to any AGCG symbol, sidelobe cancellation is effective regardless of AGBG / AGCG distribution within the ranging sequence fragment (RSF), if they are in the same number. For example, the first half of the RSF could transmit AGBG symbols and the second half AGCG symbols. In this way, the transmitter and receiver devices must change the Golay pair configuration only once per fragment. However, it may be beneficial for some applications to provide 16 AGBG AGCG pairs, or to have one entire RSF consist of AGBG and the next RSF consist of AGCG, so long as AGBG and AGCG appear in equal numbers. In any of the above cases, the aperiodic autocorrelation functions sum to zero, thus producing a waveform without sidelobes, except that the cross-correlation between AGBG and AGCG is not perfect (e.g., it has sidelobes). Therefore, at each interface between AGBG and AGCG, the system may remove 1 symbolAttorney Docket No.: 62306.202W001(at least in the receiver) to remove these sidelobes. When the pattern is 16 AGBG + 16 AGCG, there is only one interface (very small sidelobes) so the system can keep the central symbol. AGBG and AGCG are a new (longer) Golay pair. This extends the ZCZ (from 64+2G to 128+4G), but it does not remove the sidelobes close to the extremes of the CIR, because of the 16 interfaces.

[0030] When AGBG is repeated, the central window (what's relevant for CIR estimation) of the aperiodic autocorrelation of the final sequence [AGBG AGBG AGBG ...J is a scaled version of the periodic autocorrelation of AGBG. The present disclosure aids substantially in ultrawideband (UWB) multi-millisecond (MMS) ranging operations, by improving the waveform of the transmitted multi-millisecond ranging sequence (MMRS), and thus reducing the chances that an attenuated primary signal peak will be confused with a sidelobe of a reflected peak arriving at the receiver at a later time. Implemented on an ultrawideband transmitter in communication with a processor, the complementary Golay pair sidelobe suppression system disclosed herein provides practical improvements in UWB communications and ranging. This improved method transforms an MMRS with periodic and aperiodic autocorrelation sidelobes into one without sidelobes, without the normally routine need to remove the sidelobes by filtering according to the arrival times of multipath peaks or to reduce the CIR length. This unconventional approach improves the functioning of the UWB transmitter, by generating signals that are easier for a UWB receiver to synchronize.

[0031] These descriptions are provided for exemplary purposes only, and should not be considered to limit the scope of the complementary Golay pair sidelobe suppression system. Certain features may be added, removed, or modified without departing from the spirit of the claimed subject matter.

[0032] For the purposes of promoting an understanding of the principles of the present disclosure, reference will now be made to the embodiments illustrated in the drawings, and specific language will be used to describe the same. It is nevertheless understood that no limitation to the scope of the disclosure is intended. Any alterations and further modifications to the described devices, systems, and methods, and any further application of the principles of the present disclosure are fully contemplated and included within the present disclosure as would normally occur to one skilled in the art to which the disclosure relates. In particular, it is fully contemplated that the features, components, and / or steps described with respect to one embodiment may be combined with the features, components, and / or steps described with respect to other embodiments of the present disclosure. For the sake ofAttorney Docket No.: 62306.202W001brevity, however, the numerous iterations of these combinations will not be described separately.

[0033] Figure 1 is a diagram illustrating a two-way ranging-based localization system 100 that uses UWB communications, in accordance with at least one embodiment of the present disclosure. The system 100 includes at least two devices capable of UWB communication using MMS fragments, such as device 102 and device 104. Device 102 may initiate a ranging communication with a first communication, such as one or more messages, as shown, and Device 104 may respond with one or more messages as shown. Two-way ranging is based determining distance using time-of-flight between two devices. The time of flight in this example is the total time 120 between transmission and reception less some measure of response delay 130 at device 104. As understood by one of skill in the art, ranging techniques may be based on communication, such as communication 110 and / or communication 112 to estimate time of flight.

[0034] Either of the devices 102 or 104 may include a cellular telephone, a smartphone, a laptop computer, a tablet, a personal digital assistant (PDA), a computing device, wearable devices (e.g., a smart watch, or the like), a device that can be attached to an object to use for location tracking or determination of the object, or any other mobile device having wireless connection capability.

[0035] Before continuing, it should be noted that the examples described above are provided for purposes of illustration, and are not intended to be limiting. Other devices and / or device configurations may be utilized to carry out the operations described herein.

[0036] Figures 2 and 3 illustrate transmissions that may occur in a UWB system, such as system 100, for assisting in determining the location of a device, such as device 102. In some embodiments, one or both of the devices 102 or 104 include the components illustrated in Figure 4 and implement one or more of the techniques described herein. For example, in an embodiment, device 102 may transmit UWB fragments as part of the communication 110, and device 104 may receive these UWB fragments and transmit other fragments as part of the communication 112. The timing may be used as part of ranging to determine the time of flight of messaging within 110 and communicated to device 102 via communication, such as 112, to perform ranging.

[0037] Figure 2 illustrates an exemplary transmission frame 200 that may be used for ranging, in accordance with at least one embodiment of the present disclosure. In this embodiment, the frame 200 includes one or more initial transmissions 210 followed by MMS fragments 220. MMS transmissions (e.g., an MMS packet) may include a series of fragmentsAttorney Docket No.: 62306.202W001220, transmitted at most one per millisecond. In MMS methods, it may be beneficial to have a short fragment (for example lasting 32 microseconds (ps) to 256 ps) per millisecond, transmitted at high TX power, rather than continuous low-TX-power transmission spreading over multiple milli-seconds. Each symbol is approximately Ips, and the MMRS symbol repetitions (MSR) G {32, 40, 48, 64, 128, 256}. This relaxes carrier frequency offset (CFO) estimation accuracy requirements in the receiver, since with short fragments each fragment can be accumulated separately, as well as reducing the over-the-air (OTA) time and interference (e.g., fewer collisions). The MMS fragments 220 may be used for ranging applications involving UWB wireless devices.

[0038] Figure 3 illustrates an exemplary set of transmissions 300 that may be used for ranging, in accordance with at least one embodiment of the present disclosure. According to some aspects, the transmissions 300 include MMS fragments, categorized as Ranging Sequence Fragments (RSFs) 320, followed by Ranging Integrity Fragments (RIFs) 300. As shown, each RSF 320 may include a number (N_MSR) of repetitions of multi-millisecond ranging sequence (MMRS) symbols, and each RIF 330 may include a Scrambled Timestamp Sequence (STS). In an embodiment, a fragment (of the RSFs 320 or RIFs) may be transmitted per millisecond (ms). Blind parallel processing of the fragments 320 / 330 may be used to combine energy over multiple milliseconds, yielding improved link margin. The information gleaned from fragments 320 / 330 may also be used for ranging applications involving wireless devices.

[0039] In an example, there may be 32 MMRS, where first 16 MMRS consist of the AGBG sequence and the second 16 MMRS consist of the AGCG sequence. In other cases, the first MMRS may be the AGBG sequence, the second MMRS may be the AGCG sequence, the third may be the AGBG sequence, and so forth. In still other examples, RSF 1 may consist entirely of AGBG repetitions, while RSF 2 consists entirely of AGCG repetitions. Other combinations are possible, so long as the AGBG and AGCG symbols occur in equal numbers overall, and such combinations fall explicitly within the scope of the present disclosure.

[0040] The same MMRS shall be used for all RSFs in an MMS packet, with the length of each RSF defined by the number of MMRS symbol repetitions (MSR) used for the fragment. Each RSF in the MMS packet shall employ the same MSR, where this MSR G {32, 40, 48, 64, 128, 256}. One Golay pair (+gap -i-spreading E) is one MMRS symbol. The total time depends on the number of symbols per fragment (max 256) and the number of fragments (max 16). It is noted that at the time of this writing, the most current draft of the IEEEAttorney Docket No.: 62306.202W001802.15.4 standard does not include the possibility of changing the sequence AGBG to AGCG between fragments, as disclosed herein.

[0041] Figure 4 illustrates, in block diagram form, a mobile device 400 for generating MMRS transmissions, in accordance with at least one embodiment of the present disclosure. As shown, the device 400 includes an antenna 470 producing UWB radio signals 480, and radio frequency front-end circuitry 460, such as conventional filter(s) and an upconverter as is typically used in RF transmitters. The device 400 also includes UWB base band transceiver circuitry 430, which is controlled by a processor 450 connected to a memory 440. For example, the mobile device 400 may be configured to transmit and / or receive the MMRS transmissions discussed with respect to Figures 2 and 3 and also as discussed below.

[0042] In various embodiments, functions / operations may be stored as one or more instructions or code in memory 440, such as on a computer-readable storage medium, such as random access memory (RAM), read-only memory (ROM), FLASH, or disc drive, and executed by processor 450. Mobile device 400 may also include software components (e.g., located within memory 440), including, for example, an operating system, device drivers, executable libraries, and / or other executable code, such as one or more application programs. The application programs may include computer programs, stored in memory 440, executed by processor 450 to implement various functions under the control of the operating system. The computer programs may have been pre-packaged with mobile device 400 or may have been downloaded by a user into memory 440 of the mobile device 400.

[0043] Block diagrams are provided herein for exemplary purposes; a person of ordinary skill in the art will recognize myriad variations that nonetheless fall within the scope of the present disclosure. Similarly, block diagrams may show a particular arrangement of components, modules, services, steps, processes, or layers, resulting in a particular flow of data, signal, or power. It is understood that some embodiments of the systems disclosed herein may include additional components, that some components shown may be absent from some embodiments, and that the arrangement of components may be different than shown, resulting in different data, signal, or power flows while still performing the methods described herein.

[0044] Figure 5 is a time-domain graph 500 showing a typical Channel Impulse Response (CIR) of an additive white Gaussian noise (AWGN) channel when channel sounding is obtained using a Golay pair, in accordance with at least one embodiment of the present disclosure. The CIR simulates what a receiver sees when a Golay pair is delivered byAttorney Docket No.: 62306.202W001the transmitter. The Y-axis represents intensity of the autocorrelation, while the X- axis represents time. Although the units are not material, the X-axis in this case is in nanoseconds

[0045] The peak 530 represents the first path of the CIR. However, the weak peaks 540 on the left and right are not real paths but are due to the sidelobes of the autocorrelation function of the Golay pair used. Analysis of the CIR may thus require additional processing to distinguish sidelobes from real signals, e.g., in a multipath environment. It is an object of the present disclosure to minimize or eliminate the need for such processing.

[0046] Figure 6 is a time-domain graph 600 showing the Channel Impulse Response (CIR) of Figure 5, but in a multipath environment where the primary signal path is attenuated (e.g., partially blocked by an obstacle), and where the signal reflects off of multiple objects at different positions before arriving at the receiver, in accordance with at least one embodiment of the present disclosure.

[0047] The problem is more challenging in a multipath environment, where the sidelobes of a strong delayed path may be very close to the first path. Open outdoor channels may have up to 400 ns delay between the early energy pack and a later one. All Golay pairs of the current IEEE 802.15.4z standard have only 256 ns of sidelobe-free precursor area when the gap G=0, which cannot guarantee a sidelobe-free window in front of the early energy pack. Figure 6 shows a realistic model of an outdoor environment.

[0048] As can be seen in the graph 600, a number of peaks 630 arrive between 600 and 800 nanoseconds, and it may be difficult to tell which (if any) of these represents the primary path, which are reflections, and which are left sidelobes of a late reflection. A number of sidelobes 640 also occur, which are well spaced from the peaks 630. However, there are also a number of ambiguous peaks 650, which may be delayed / attenuated reflections, or which may be right sidelobes of an early but highly attenuated primary peak 660. Such ambiguity makes it difficult for the receiver to identify the real first path. The first signal to arrive is the direct path and indicates the distance between the devices. It can be attenuated by obstacles. Reflections might be stronger, but they arrive later because they travelled a longer distance. It is an object of the present disclosure to minimize or eliminate the sidelobes 640, such that it is easier to determine which peak represents the primary path and thus the range between the transmitter and the receiver.

[0049] Figure 7 is a time-domain graph 700 showing the periodic auto-correlation functions of AGBG 702 and AGCG 704, where A is code 1 and B = -C = code 2, in accordance with at least one embodiment of the present disclosure. The Y -axis 710 represents correlation in percent, and the X-axis 720 represents the correlation delays inAttorney Docket No.: 62306.202W001“taps”. For any Golay pair 702 and any gap length, a complementary Golay pair 704 can be defined with equal and opposite sidelobes 740. The new Golay pair is obtained by signflipping the second code in the pair, as shown in Figure 7. The non-periodic autocorrelation sidelobes 740 are also inverted and can be cancelled by the disclosed method, allowing the use of one additional symbol in the CIR estimation if the 2-fragment implementation is used. If AGBG and AGCG are used in the same fragment, the system may need to remove the central symbol (or keep it, but minimal sidelobes remain). Thus, combining the AGBG and AGCG symbols for channel sounding obtains a combined auto-correlation function without sidelobes. Also visible are the periodic peaks 730.

[0050] Figure 8 is a time-domain graph 800 showing the auto-correlation function of the original Golay pair 802 and the combination of complementary Golay pairs 804, in accordance with at least one embodiment of the present disclosure. The Y-axis 810 represents correlation on a scale of 0 to 1, and the Y-axis 820 represents time in “taps”. As can be seen, the Golay pair 802 generates significant sidelobes 840, whereas the combined code 804 does not. Thus, the disclosed method combines AGBG and AGCG symbols for channel sounding to obtain a combined auto-correlation function without sidelobes, as shown in Figure 8.POSSIBLE EMBODIMENTS

[0051] Although the sign inversion of the second code in the Golay pair is discussed in this document, the same results would still apply if the first code is inverted instead.

[0052] According to the IEEE 802.15.4ab standard, the MMRS may be repeated at least 32 times. Because any AGBG symbol is complementary to any AGCG symbol, sidelobe cancellation is effective regardless of AGBG / AGBG distribution within the RSF, if they are in the same number. For example, the first half of the RSF could transmit the AGBG symbols and the second half could transmit the AGCG symbols. In this way, the transmitter and receiver devices must change the Golay pair configuration only once per fragment.

[0053] More advanced schemes could involve sign flipping of both A and B codes to extend the sidelobes -free area, or zero-correlation zone (ZCZ), and obtain a longer CIR estimation. One strategy to recursively double the ZCZ is to repeat the current sequence where the second half is inverted. Using this method, if [A, B] guarantees a ZCZ of 64 taps, a sequence x32 as long can be constructed to guarantee a ZCZ (and a CIR) of 2048 taps. For example, the sequence [A, B, A, -B, A, B, -A, B] allows a CIR estimation length of 128. Similar considerations are valid if a gap G is present. Furthermore, if the AGBG and AGCGAttorney Docket No.: 62306.202W001sequences are unequal in number, small sidelobes may appear, but the system may still be usable for sidelobe reduction overall. For example, if each ranging sequence fragment (RSF) has 32 symbols, then the equal number is 16x AGBG and 16x AGCG. It is noted that even an unequal number would still substantially reduce the sidelobes if the difference is small (like 15 instances of AGBG and 16 instances of AGCG). For puiposes of this document, the term “approximately equal” shall mean values within 10% of one another.

[0054] In an alternative embodiment, when at least two ranging sequence fragments (RSFs) are present, each RSF comprises repetitions of the same symbol, and complementary symbols are used in different fragments. For example, odd fragments could use the AGBG symbol and even fragments the AGCG symbol. Myriad other arrangement are possible, and fall explicitly within the scope of the present disclosure. The final CIR is obtained by coherently combining the CIRs obtained from each fragment.

[0055] According to the IEEE 802.15.4 standard, the number of ranging sequence fragments (RSFs) can be up to 16, spanning over a total of 16 ms. The carrier frequency offset (CFO) estimation error may make the coherent combining of 16 fragments challenging. In this case, a hybrid combining is possible, where fragment pairs 1+2, 3+4, and so on... are combined coherently, and the groups are added non-coherently. The CIR of each pair is sidelobe-free if complementary symbols are used in the two fragments of the pair.

[0056] Figure 9 is a schematic, diagrammatic representation, in flow diagram form, of an example complementary Golay pair sidelobe suppression method 900, in accordance with at least one embodiment of the present disclosure. It is understood that the steps of method 900 may be performed in a different order than shown in Figure 9, additional steps can be provided before, during, and after the steps, and / or some of the steps described can be replaced or eliminated in other embodiments. One or more of steps of the method 900 can be carried by one or more devices and / or systems described herein, such as components of the system 100, system 400, and / or processor circuit 1050.

[0057] In step 910, the method 900 includes transmitting the first Golay pair, AGBG, N times, where N is any number from 1 to half the number of symbols in one fragment (MRS), and G is a gap length between 0 and 256 nanoseconds. Execution then proceeds to step 920.

[0058] In step 920, the method 900 includes transmitting the second Golay pair, AGCG, N times.

[0059] Steps 910 and 920 may be repeated M times, where M is any value between 1 and half the number of symbols in one fragment.Attorney Docket No.: 62306.202W001

[0060] Flow diagrams are provided herein for exemplary purposes; a person of ordinary skill in the art will recognize myriad variations that nonetheless fall within the scope of the present disclosure. For example, any of the steps described herein may optionally include an output to a user of information relevant to the step, and may thus represent an improvement in the user interface over existing art by providing information (whether static or dynamically updated) that is not otherwise available.

[0061] Similarly, the logic of flow diagrams may be shown as sequential. However, similar logic could be parallel, massively parallel, object oriented, real-time, event-driven, cellular automaton, or otherwise, while accomplishing the same or similar functions. In order to perform the methods described herein, a processor may divide each of the steps described herein into a plurality of machine instructions, and may execute these instructions at the rate of several hundred, several thousand, several million, or several billion per second, in a single processor or across a plurality of processors. Such rapid execution may be necessary in order to execute the method in real time as described herein. For example, in order to alternate the primary Golay code AGBG with the complementary Golay code AGCG within a single ranging sequence fragment with a spreading factor of 4, the processor may need to command radio pulses that are 4 nanoseconds apart or less.

[0062] Figure 10 is a schematic diagram of a processor circuit 1050, in accordance with at least one embodiment of the present disclosure. The processor circuit 1050 may be implemented in the system 100 or 400, or other devices or workstations (e.g., third-party workstations, network routers, etc.), or on a cloud processor or other remote processing unit, as necessary to implement the method. As shown, the processor circuit 1050 may include a processor 1060, a memory 1064, and a communication module 1068. These elements may be in direct or indirect communication with each other, for example via one or more buses.

[0063] The processor 1060 may include a central processing unit (CPU), a digital signal processor (DSP), an ASIC, a controller, or any combination of general-purpose computing devices, reduced instruction set computing (RISC) devices, application-specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), or other related logic devices, including mechanical and quantum computers. The processor 1060 may also comprise another hardware device, a firmware device, or any combination thereof configured to perform the operations described herein. The processor 1060 may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.Attorney Docket No.: 62306.202W001

[0064] The memory 1064 may include a cache memory (e.g., a cache memory of the processor 1060), random access memory (RAM), magnetoresistive RAM (MRAM), readonly memory (ROM), programmable read-only memory (PROM), erasable programmable read only memory (EPROM), electrically erasable programmable read only memory (EEPROM), flash memory, solid state memory device, hard disk drives, other forms of volatile and non-volatile memory, or a combination of different types of memory. In an embodiment, the memory 1064 includes a non-transitory computer-readable medium. The memory 1064 may store instructions 1066. The instructions 1066 may include instructions that, when executed by the processor 1060, cause the processor 1060 to perform the operations described herein. Instructions 1066 may also be referred to as code. The terms “instructions” and “code” should be interpreted broadly to include any type of computer-readable statement(s). For example, the terms “instructions” and “code” may refer to one or more programs, routines, sub-routines, functions, procedures, etc. “Instructions” and “code” may include a single computer-readable statement or many computer-readable statements.

[0065] The communication module 1068 can include any electronic circuitry and / or logic circuitry to facilitate direct or indirect communication of data between the processor circuit 1050, and other processors or devices. In that regard, the communication module 1068 can be an input / output (TO) device. In some instances, the communication module 1068 facilitates direct or indirect communication between various elements of the processor circuit 1050 and / or the system 100 or 400. The communication module 1068 may communicate within the processor circuit 1050 through numerous methods or protocols. Serial communication protocols may include but are not limited to United States Serial Protocol Interface (US SPI), Inter-Integrated Circuit (I2C), Recommended Standard 232 (RS-232), RS-485, Controller Area Network (CAN), Ethernet, Aeronautical Radio, Incorporated 429 (ARINC 429), MODBUS, Military Standard 1553 (MIL-STD-1553), or any other suitable method or protocol. Parallel protocols include but are not limited to Industry Standard Architecture (ISA), Advanced Technology Attachment (ATA), Small Computer System Interface (SCSI), Peripheral Component Interconnect (PCI), Institute of Electrical and Electronics Engineers 488 (IEEE-488), IEEE-1284, and other suitable protocols. Where appropriate, serial and parallel communications may be bridged by a Universal Asynchronous Receiver Transmitter (UART), Universal Synchronous Receiver Transmitter (USART), or other appropriate subsystem.

[0066] External communication (including but not limited to software updates, firmware updates, preset sharing between the processor and central server, etc.) may be accomplishedAttorney Docket No.: 62306.202W001using any suitable wireless or wired communication technology, such as a cable interface such as a universal serial bus (USB), micro USB, Uightning, or FireWire interface, Bluetooth, Wi-Fi, ZigBee, Li-Fi, or cellular data connections such as 2G / GSM (global system for mobiles) , 3G / UMTS (universal mobile telecommunications system), 4G, long term evolution (LTE), WiMax, or 5G. For example, a Bluetooth Low Energy (BLE) radio can be used to establish connectivity with a cloud service, for transmission of data, and for receipt of software patches. The controller may be configured to communicate with a remote server, or a local device such as a laptop, tablet, or handheld device, or may include a display capable of showing status variables and other information. Information may also be transferred on physical media such as a USB flash drive or memory stick.

[0067] As will be readily appreciated by those having ordinary skill in the art after becoming familiar with the teachings herein, the complementary Golay pair sidelobe suppression system advantageously expands the zero correlation zone (ZCZ) of ultrawideband transmissions that may be used for multi-millisecond ranging operations. Accordingly, it can be seen that the complementary Golay pair sidelobe suppression system fills a need in the art, by suppressing sidelobes, and thus making it easier to distinguish the primary path from the sidelobes of later secondary paths.

[0068] A number of variations are possible on the examples and embodiments described above. For example, the gap for the AGBG and AGCG sequences can be anywhere from 0 to 256 nanoseconds. The AGBG and AGCG sequences may be alternated within an MMRS, between MMRSes, within an RSF, or between RSFs, without departing from the spirit of the present disclosure.

[0069] The technology described herein may be applied to both communication and ranging.

[0070] Accordingly, the logical operations making up the embodiments of the technology described herein are referred to variously as operations, steps, objects, elements, components, or modules. Furthermore, it should be understood that these may occur, or be performed or arranged, in any order, unless explicitly claimed otherwise or a specific order is inherently necessitated by the claim language.

[0071] All directional references e.g., upper, lower, inner, outer, upward, downward, left, right, lateral, front, back, top, bottom, above, below, vertical, horizontal, clockwise, counterclockwise, proximal, and distal are only used for identification purposes to aid the reader’s understanding of the claimed subject matter, and do not create limitations, particularly as to the position, orientation, or use of the complementary Golay pair sidelobeAttorney Docket No.: 62306.202W001suppression system. Connection references, e.g., attached, coupled, connected, joined, or “in communication with’’ are to be construed broadly and may include intermediate members between a collection of elements and relative movement between elements unless otherwise indicated. As such, connection references do not necessarily imply that two elements are directly connected and in fixed relation to each other. The term “or” shall be interpreted to mean “and / or” rather than “exclusive or.” The word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. Unless otherwise noted in the claims, stated values shall be interpreted as illustrative only and shall not be taken to be limiting.

[0072] The above specification, examples and data provide a complete description of the structure and use of exemplary embodiments of the complementary Golay pair sidelobe suppression system as defined in the claims. Although various embodiments of the claimed subject matter have been described above with a certain degree of particularity, or with reference to one or more individual embodiments, those skilled in the art could make numerous alterations to the disclosed embodiments without departing from the spirit or scope of the claimed subject matter.

[0073] Still other embodiments are contemplated. It is intended that all matter contained in the above description and shown in the accompanying drawings shall be interpreted as illustrative only of particular embodiments and not limiting. Changes in detail or structure may be made without departing from the basic elements of the subject matter as defined in the following claims.

Claims

Attorney Docket No.: 62306.202W001CLAIMSWhat is claimed is:

1. A method for transmitting an ultrawideband (UWB) signal, the method comprising:repeatedly transmitting a first Golay pair comprising a first code and a second code; andrepeatedly transmitting a second Golay pair, wherein the second Golay pair comprises the first code and minus the second code.

2. The method of claim 1, wherein repeatedly transmitting the second Golay pair is sequential with repeatedly transmitting the first Golay pair.

3. The method of claim 1, wherein repeatedly transmitting the second Golay pair is interleaved with repeatedly transmitting the first Golay pair.

4. The method of claim 1, wherein repeatedly transmitting the first Golay pair and the second Golay pair occurs within a single Multi-Millisecond Ranging Sequence (MMRS).

5. The method of claim 1, wherein repeatedly transmitting the first Golay pair occurs within a first MMRS, and repeatedly transmitting the second Golay pair occurs within a second MMRS.

6. The method of claim 1, wherein repeatedly transmitting the first Golay pair and the second Golay pair occurs within a single Ranging Sequence Fragment (RSF).

7. The method of claim 1, wherein repeatedly transmitting the first Golay pair occurs within a first RSF, and repeatedly transmitting the second Golay pair occurs within a second RSF.

8. The method of claim 1, wherein repeatedly transmitting the first Golay pair and the second Golay pair results in fewer sidelobes than repeatedly transmitting only the first Golay pair or repeatedly transmitting only the second Golay pair.Attorney Docket No.: 62306.202W0019. The method of claim 1 , wherein the first Golay pair is transmitted an equal number of times as the second Golay pair.

10. Transmitter circuitry comprising a processor, a memory, and a base band transmitter, wherein the transmitter circuitry is configured to:transmit an ultrawideband (UWB) signal comprising:repeatedly transmitting a first Golay pair comprising a first code and a second code; andrepeatedly transmitting a second Golay pair, wherein the second Golay pair comprises the first code and minus the second code.

11. The transmitter circuitry of claim 10, wherein repeatedly transmitting the second Golay pair is sequential with repeatedly transmitting the first Golay pair.

12. The transmitter circuitry of claim 10, wherein repeatedly transmitting the second Golay pair is interleaved with repeatedly transmitting the first Golay pair.

13. The transmitter circuitry of claim 10, wherein repeatedly transmitting the first Golay pair and the second Golay pair occurs within a single Multi-Millisecond Ranging Sequence (MMRS) or Ranging Sequence Fragment (RSF).

14. The transmitter circuitry of claim 10, wherein repeatedly transmitting the first Golay pair occurs within a first MMRS or RSF, and repeatedly transmitting the second Golay pair occurs within a second MMRS or RSF.

15. The transmitter circuitry of claim 10, wherein the first Golay pair is transmitted an equal number of times as the second Golay pair.

16. An ultrawideband transmitter comprising:a memory;ultrawideband base band transmitter circuitry;a processor configured to read the memory and control the ultrawideband base band transmitter circuitry to:Attorney Docket No.: 62306.202W001repeatedly transmit a first Golay pair comprising a first code and a second code; andrepeatedly transmit a second Golay pair, wherein the second Golay pair comprises the first code and minus the second code,such that the first Golay pair is transmitted an equal number of times as the second Golay pair;a radio frequency front end; andan antenna.

17. The ultrawideband transmitter of claim 16, wherein repeatedly transmitting the second Golay pair is sequential with repeatedly transmitting the first Golay pair.

18. The ultrawideband transmitter of claim 16, wherein repeatedly transmitting the second Golay pair is interleaved with repeatedly transmitting the first Golay pair.

19. The ultrawideband transmitter of claim 16, wherein repeatedly transmitting the first Golay pair and the second Golay pair occurs within a single Multi-Millisecond Ranging Sequence (MMRS) or Ranging Sequence Fragment (RSF).

20. The ultrawideband transmitter of claim 16, wherein repeatedly transmitting the first Golay pair occurs within a first MMRS or RSF, and repeatedly transmitting the second Golay pair occurs within a second MMRS or RSF.

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