Apparatus and method for wireless communication synchronization
A dual differential correlator structure addresses synchronization challenges in wireless communication by improving signal-to-noise ratio and reducing power consumption, resulting in more efficient communication.
Patent Information
- Application Number
- CN202510062753.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2024-01-15
- Filing Date
- 2025-01-15
- Publication Date
- 2025-07-15
AI Technical Summary
In wireless communications, especially in battery-powered devices with low current consumption, it is difficult to correctly detect synchronization between the transmitting device and the receiving device under weak carrier noise ratio and possible carrier interference, resulting in excessive retransmission requests, affecting power consumption and communication delays.
Using a dual correlator topology, by adding differential demodulation and correlation calculation, the frame preamble mode detection capability of the wireless communication device is improved, and the signal-to-noise ratio (SNR) is improved in order to better detect wireless symbol sequences and avoid undesirable retransmission requests.
Improves frame synchronization quality, reduces power consumption, reduces communication delay between wireless devices, and enhances synchronization detection capabilities in noise and interference environments.
Smart Images
Figure CN120321082A_ABST
Abstract
Description
Technical Field
[0001] This specification relates to systems, methods, devices, apparatuses, articles of manufacture, and instructions for wireless communication synchronization. Background Art
[0002] Improvements in the field of wireless communication. Summary of the Invention
[0003] According to an example embodiment, a first wireless device includes: a receiver configured to receive a symbol sequence in a wireless communication frame transmitted from a second wireless device; a first demodulator configured to generate a first differential symbol sequence by differencing the received symbol sequence; a first correlator configured to compare the first differential symbol sequence with a first differential synchronization word; wherein the first correlator is configured to generate a first match signal when the first differential symbol sequence substantially matches the first differential synchronization word; a second demodulator configured to generate a second differential symbol sequence by differencing the first differential symbol sequence; a second correlator configured to compare the second differential symbol sequence with a second differential synchronization word; wherein the second correlator is configured to generate a second match signal when the second differential symbol sequence substantially matches the second differential synchronization word; and wherein the first wireless device is configured to establish a link with the second wireless device when both the first match signal and the second match signal are generated.
[0004] In another example embodiment, the symbol sequence is a training sequence.
[0005] In another example embodiment, the training sequence is included in a preamble portion of the wireless communication frame.
[0006] In another example embodiment, the training sequence is a short training sequence (STS).
[0007] In another example embodiment, the first correlator is configured to compare the first differential symbol sequence with the complex conjugate of the first differential synchronization word; and the second correlator is configured to compare the second differential symbol sequence with the complex conjugate of the second differential synchronization word.
[0008] In another example embodiment, further includes a symbol delay circuit configured to phase-align the first match signal from the first correlator with the second match signal from the second correlator.
[0009] In another example embodiment, the symbol delay circuit is configured to compensate for the symbol delay added by the second demodulator.
[0010] In another exemplary embodiment, a vector summing circuit is further included, which is configured to perform vector summation on the complex-valued signal outputs generated by the first correlator and the second correlator.
[0011] In another exemplary embodiment, a peak detection circuit is further included, which is configured to detect peak signals in the vector-summed output from the first correlator and the second correlator.
[0012] In another exemplary embodiment, the peak signal provides an indication of the optimal time to start sampling the wireless communication frame received from the second wireless device.
[0013] In another exemplary embodiment, a frame synchronization, bit-time synchronization, and carrier frequency offset detection circuit is further included, which is configured to calculate the carrier frequency offset, establish frame synchronization, and set the initial bit timing recovery of the established link.
[0014] In another exemplary embodiment, the symbol sequence achieves synchronization of the wireless link between the first wireless device and the second wireless device.
[0015] In another exemplary embodiment, the first wireless device and the second wireless device are configured to exchange another communication frame after the synchronization.
[0016] In another exemplary embodiment, the receiver is configured to detect the symbol sequence in each wireless communication frame transmitted from the second wireless device.
[0017] In another exemplary embodiment, the symbol sequence is modulated using quadrature phase shift keying (QPSK) constellation points.
[0018] In another exemplary embodiment, the symbol sequence is modulated in a differential manner; and the first demodulator and the second demodulator are differential demodulators.
[0019] In another exemplary embodiment, the first device includes a decimator, a DC offset compensation, and a filter circuit.
[0020] According to an example embodiment, a method for synchronizing a first wireless device with a second wireless device includes: receiving a symbol sequence in a wireless communication frame transmitted from the second wireless device; generating a first differential symbol sequence by differentiating the received symbol sequence; comparing the first differential symbol sequence with a first differential synchronization word; generating a first match signal if the first differential symbol sequence matches the first differential synchronization word; generating a second differential symbol sequence by differentiating the first differential symbol sequence; comparing the second differential symbol sequence with a second differential synchronization word; generating a second match signal if the second differential symbol sequence matches the second differential synchronization word; and establishing a link between the first wireless device and the second wireless device if both the first match signal and the second match signal are generated.
[0021] The foregoing discussion is not intended to present every example embodiment or every implementation within the scope of the current or future claim sets. The figures and the detailed description also illustrate various example embodiments.
[0022] Various example embodiments may be more fully understood in view of the following detailed description in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS
[0023] Figure 1 Represents an exemplary single correlator wireless device.
[0024] Figure 2 Represents an exemplary dual correlator wireless device.
[0025] Figure 3 Represents an exemplary dual correlator within the exemplary dual correlator wireless device.
[0026] Figure 4 Represents an exemplary correlator within the dual correlator.
[0027] Figure 5A 、 5B Represents an exemplary comparison between the absolute value signal output from a single correlator wireless device and the absolute value signal output from a dual correlator wireless device when a -100 dBm useful signal is applied in the presence of additive white Gaussian noise.
[0028] Figure 6A 、 6B Represents another exemplary comparison between the absolute value signal output of a single correlator wireless device and the absolute value signal output of a dual correlator wireless device when no useful signal is applied and only additive white Gaussian noise is present.
[0029] Figure 7 Represents an exemplary comparison between the percentages of lost frames for a given useful signal level using a single correlator wireless device or a dual correlator wireless device for various synchronization thresholds.
[0030] Figure 8 Exemplary instruction sets for synchronizing a first wireless device with a second wireless device using a dual-correlator wireless device.
[0031] Although this disclosure admits various modifications and alternative forms, its details have been shown by way of example in the drawings and will be described in detail. However, it should be understood that there may be other embodiments in addition to the specific embodiments described. All modifications, equivalents, and alternative embodiments falling within the spirit and scope of the appended claims are also covered. Detailed Description
[0032] To establish a wireless communication link between a transmitting wireless device and a receiving wireless device, correct preamble detection of a known training sequence (TS) by the receiving device is required.
[0033] Figure 1 Exemplary single-correlator wireless device 100 is shown. The single-correlator wireless device 100 includes an RF receiver 102 and a digital receiver 104.
[0034] The RF receiver 102 includes: an RF and analog front end embedded with an optional LNA; a mixer for downconversion, bandpass or low-pass filtering; and an analog-to-digital converter.
[0035] The digital receiver 104 includes: a decimator, a DC offset compensation and filter circuit 106; a differential demodulator 108; a correlator 110; a differential synchronization word 112; and a frame synchronization, bit time synchronization, carrier frequency offset detection circuit 114.
[0036] The training sequence 116 in the wireless communication frame is received by the RF receiver 102 from a second wireless device (not shown) and passed to the digital receiver 104. The digital receiver 104 first performs decimation, DC offset compensation, and signal filtering using the decimator, DC offset compensation and filter circuit 106.
[0037] The training sequence 116 is known to both the wireless device 100 and the second wireless device (not shown), and is used to identify the start of a wireless frame from a received RF wireless signal including background noise.
[0038] The differential demodulator 108 then demodulates the training sequence 116 to generate a differential training sequence 118. The correlator 110 compares the differential training sequence 118 with the pre-stored differential synchronization word 112. If the correlator 110 matches the differential training sequence 118 to the synchronization word 112, the wireless device 100 generates a match signal 120 and establishes a wireless link with the second wireless device (not shown). After link establishment, various communication frames (e.g., commands, payload data, etc.) can be exchanged between the wireless device 100 and the second wireless device.
[0039] However, wireless communication devices are often battery-powered, and thus, low current consumption is important for usage autonomy and user experience. Low current consumption can be achieved by configuring the transmitting device to operate at the lowest possible transmit power level, thus close to the sensitivity level of the receiving communication device.
[0040] However, this makes it more difficult for the receiving device to correctly detect the preamble training sequence for synchronization between the transmitting device and the receiving device in order to establish a wireless link, because of the weaker carrier-to-noise ratio and possible carrier interference sources.
[0041] The inability to correctly detect this preamble training sequence at the start of a frame causes the receiving device to mark the entire frame with its associated payload data as lost and thus request a retransmission. Excessive retransmissions not only affect power consumption and quality of service, but also delay communication between wireless devices.
[0042] Proper TS synchronization enables communication wireless devices to compensate for carrier frequency offset and establish initial timing recovery.
[0043] Although receiver immunity can be improved by increasing the transmit power level of the transmitting device, this higher power transmission increases the current consumption of the transmitter and is even impossible when reliability constraints on the transmitter's circuitry are limited by semiconductor technology.
[0044] Now discuss a dual-correlator wireless device (e.g., single + dual differential correlation), which increases the ratio (e.g., SNR) of the useful correlation peak compared to the correlation property of (Gaussian white) noise in order to better detect wireless symbol sequences (e.g., the start of a wireless frame, detection of a training sequence for wireless link synchronization, etc.) and avoid unwanted retransmission requests.
[0045] In various example embodiments, adding a second differential demodulator and a second correlator improves the detectability of the frame preamble pattern (e.g., for Bluetooth HDT) of a wireless communication device.
[0046] However, this single + dual differential correlation (i.e., dual-correlator) topology can be applied to any other preamble and / or frame pattern detection to increase the SNR and improve symbol sequence detection.
[0047] Figure 2 Represents an exemplary dual-correlator wireless device 200. The exemplary dual-correlator wireless device 200 includes an RF receiver 202 and a digital receiver 204.
[0048] The RF receiver 202 includes: an RF and analog front end embedded with an optional LNA; a mixer for down-conversion, band-pass or low-pass filtering; and an analog-to-digital converter.
[0049] The digital receiver 204 includes: a decimator, a DC offset compensation and filter circuit 206; a first differential demodulator 208; a second differential demodulator 209; a double correlator 210; a differential synchronization word 212; a twice-differential synchronization word 213; and a frame synchronization, bit time synchronization, carrier frequency offset detection circuit 214.
[0050] The symbol sequence 216 in the wireless communication frame is received by the RF receiver 202 from a second wireless device (not shown) and is passed to the digital receiver 204. The digital receiver 204 first performs decimation, DC offset compensation, and signal filtering using the decimator, DC offset compensation, and filter circuit 206. In some example embodiments, the symbol sequence is modulated using quadrature phase shift keying (QPSK) constellation points.
[0051] The first differential demodulator 208 differentiates the symbol sequence 216 to generate a differential symbol sequence 218 (i.e., the first derivative of the symbol sequence 216).
[0052] The first correlator in the double correlator 210 (see Figure 3 ) compares the differential symbol sequence 218 with the pre-stored differential synchronization word 212. If the first correlator matches the differential symbol sequence 218 to the synchronization word 212, the first correlator generates a first match signal (see Figure 3 ).
[0053] The second differential demodulator 209 differentiates the differential symbol sequence 218 to generate a twice-differential symbol sequence 220 (i.e., the second derivative of the symbol sequence 216).
[0054] The second correlator in the double correlator 210 (see Figure 3 ) compares the twice-differential symbol sequence 220 with the pre-stored twice-differential synchronization word 213. If the second correlator matches the twice-differential symbol sequence 218 to the twice-differential synchronization word 213, the second correlator generates a second match signal (see Figure 3 ).
[0055] If both the first match signal and the second match signal are generated, the wireless device 200 establishes a link with the second wireless device (not shown). After the link is established, various communication frames (e.g., commands, payload data, etc.) can be exchanged between the wireless device 100 and the second wireless device.
[0056] In various example embodiments, the symbol sequence 216 is a training sequence (TS), a short training sequence (STS), or a synchronization word.
[0057] In some example embodiments, the first correlator in the double correlator 210 (see Figure 3) and a second correlator (see Figure 3 ) correlate the differential symbol sequence 218 and the double-differential symbol sequence 220 with the complex conjugates of the differential synchronization word 212 and the double-differential synchronization word 213, respectively.
[0058] Thus, the wireless device 200 implements a dual structure for correlation, which performs correlation calculations based not only on the single-differential demodulated symbol sequence 216 (i.e., the input signal) but also on the double-differential demodulated symbol sequence 216.
[0059] Compared with Figure 1 the single-correlator topology, the increased output level of the dual-correlator topology, especially in the presence of a (weak) useful signal combined with additive white Gaussian noise. The dual-correlator topology thus realizes an increased ability to detect the start of a frame in the presence of noise and / or interfering signals.
[0060] Figure 3 Example 300 of the dual-correlator 210 within the exemplary dual-correlator wireless device 200 is shown. Example 300 illustrates the first correlator 302, the second correlator 304, the first match signal 306, and the second match signal 308 as discussed in Figure 2 .
[0061] Additionally, example 300 of the dual-correlator 210 includes a symbol delay circuit 310, a vector summing circuit 312, and a peak detection circuit 314.
[0062] The symbol delay circuit 310 aligns the phase of the first match signal 306 from the first correlator 302 with the second match signal 308 from the second correlator 304 to compensate for the "symbol delay" added by the second demodulator 209.
[0063] The vector summing circuit 312 performs a vector sum of the complex-valued outputs generated by the first correlator 302 and the second correlator 304.
[0064] The peak detection circuit 314 detects a peak in the vector-summed output. The peak provides an indication of the best / optimal time to start sampling the wireless communication signal from the second device and decoding any commands and / or payload data therein. The angle of the complex number corresponding to the peak is an initial estimate of the carrier frequency offset.
[0065] The frame synchronization, bit time synchronization, carrier frequency offset detection circuit 214 then calculates the carrier frequency offset and establishes frame synchronization and initial bit timing.
[0066] In some example embodiments, the dual-correlator wireless device 200 operates at symbol_rate * OSR (oversampling ratio). The higher the OSR, the higher the precision for better eye diagram opening for synchronization.
[0067] Compared with single differential, double differential introduces symbol period delay. This needs to be considered when combining the two in vector summation 308 by using the symbol delay 306 circuit.
[0068] Although the operation of the double correlator 210 is symbol rate agnostic, in an example embodiment, the synchronization word contains a value for every 2Mbaud symbol, and the differential demodulators 208, 209 perform phase difference with a lag equal to the 2Mbaud symbol duration (expressed in number of samples), and the adder trees of the correlators 302, 304 correlate the content of their input buffer data with the branches that are at a distance at the symbol duration.
[0069] Figure 4 Represents an exemplary correlator 400 within the double correlator 200. The exemplary correlator 400 is an example of one or both of the first correlator 302 and the second correlator 304.
[0070] The exemplary correlator 400 includes a correlator input 402, several signal samples 404, a time series 406, a synchronization word 408, and a correlator output 410.
[0071] The exemplary correlator 400 is a polyphase correlator known to those skilled in the art. Figure 1 、 2 、3 The training sequence (e.g., synchronization word) shown in is represented by constants C(0), c(1), etc. Several input signal samples are represented by the symbol z - 1.
[0072] Figure 5A 、 5B Represents an exemplary comparison 500 between the absolute value signal output 502 from the single correlator wireless device 100 and the absolute value signal output 504 from the double correlator wireless device 200 when a - 100dBm useful signal is applied in the presence of Gaussian white noise.
[0073] In this comparison 500, both the single correlator wireless device 100 and the double correlator wireless device 200 receive a - 100dBm signal including a training sequence in the presence of Gaussian white noise.
[0074] The exemplary comparison 500 is based on an exemplary short synchronization header (e.g., training sequence) for the high data throughput (HDT) mode of low - power Bluetooth (BLE): nine - fold repetition of the short training sequence (STS) [-1 -j j 1] (where j = √-1).
[0075] In some example embodiments, the double correlator wireless device 200 increases the useful correlation peak by about 24% while keeping the useless noise correlation at about the same level, thereby improving the frame synchronization quality.
[0076] Figure 6A 、 6B Represents another exemplary comparison 600 between the absolute value signal output 602 of the single correlator wireless device 100 and the absolute value signal output 604 of the double correlator wireless device 200 when no useful signal is applied and only Gaussian white noise is present.
[0077] In this exemplary comparison 600, only Gaussian white noise is shown without any training sequence. This exemplary comparison 600 shows that using the double correlator wireless device 200 topology basically does not add extra noise.
[0078] Figure 7 Represents an exemplary comparison 700 between the percentages of lost frames for a given useful signal level in the case of using the single correlator wireless device 100 or the double correlator wireless device 200 for various synchronization thresholds.
[0079] The double correlator wireless device 200 provides a receiver performance improvement of about 0.5 to 1 dB.
[0080] Figure 8 Represents an exemplary instruction set 800 for synchronizing a first wireless device with a second wireless device using the double correlator wireless device 200.
[0081] The order in which the instructions are discussed does not limit the order in which other example embodiments implement the instructions, unless otherwise specifically stated. Additionally, in some embodiments, the instructions are implemented simultaneously.
[0082] The exemplary instruction set 800 begins in 802 by receiving a symbol sequence in a wireless communication frame transmitted from the second wireless device. Next, in 804, a first differential symbol sequence is generated by differentiating the received symbol sequence. Subsequently, in 806, the first differential symbol sequence is compared with a first differential synchronization word.
[0083] Next, in 808, if the first differential symbol sequence matches the first differential synchronization word, a first match signal is generated. Subsequently, in 810, a second differential symbol sequence is generated by differentiating the first differential symbol sequence. Next, in 812, the second differential symbol sequence is compared with a second differential synchronization word.
[0084] In 814, if the second differential symbol sequence matches the second differential synchronization word, a second match signal is generated. Subsequently, in 816, if both the first match signal and the second match signal are generated, a link is established between the first wireless device and the second wireless device.
[0085] Various systems such as the dual correlator wireless device 200 discussed above can host these instructions. Such systems can include input / output data interfaces, processors, storage devices, and non-transitory machine-readable storage media. The machine-readable storage media includes instructions that use the data within the storage device to control how the processor receives input data and how it transforms the input data into output data. In alternative example embodiments, the machine-readable storage media is a non-transitory computer-readable storage media. In other example embodiments, the instruction sets described above can be implemented using logic gates, application specific chips, firmware, and other forms of hardware.
[0086] It will be readily understood that the components of the embodiments generally described herein and illustrated in the figures can be arranged and designed in a wide variety of different configurations. Thus, the detailed description of the various embodiments represented in the figures is not intended to limit the scope of the present disclosure, but merely to represent the various embodiments. Although aspects of the embodiments are presented in the figures, the figures are not necessarily drawn to scale unless specifically stated otherwise.
[0087] The invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. Thus, the scope of the invention is indicated by the appended claims rather than by this detailed description. All changes that come within the meaning and range of equivalency of the claims are to be embraced within their scope.
[0088] References throughout this specification to features, advantages, or similar language do not imply that all of the features and advantages that can be realized with the invention should be present in or in any single embodiment of the invention. On the contrary, the language referring to the features and advantages should be understood to mean that a particular feature, advantage, or characteristic described in connection with an embodiment is included in at least one embodiment of the invention. Thus, the discussions of the features, advantages, and similar language throughout this specification may, but do not necessarily, refer to the same embodiment.
[0089] In addition, the described features, advantages, and characteristics of the invention can be combined in any suitable manner in one or more embodiments. Those skilled in the relevant art will recognize that, given the description herein, the invention can be practiced without one or more of the specific features or advantages of a particular embodiment. In other instances, additional features and advantages may be recognized that may not be present in all embodiments of the invention.
[0090] References throughout this specification to "one embodiment", "an embodiment", or similar language mean that a particular feature, structure, or characteristic described in connection with the indicated embodiment is included in at least one embodiment of the present invention. Thus, the phrases "in one embodiment", "in an embodiment", and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment.
Claims
1. A first wireless device, characterized in that, Comprising: A receiver configured to receive a symbol sequence in a wireless communication frame transmitted from a second wireless device; A first demodulator configured to generate a first differential symbol sequence by differencing the received symbol sequence; A first correlator configured to compare the first differential symbol sequence with a first differential synchronization word; Wherein the first correlator is configured to generate a first match signal when the first differential symbol sequence substantially matches the first differential synchronization word; A second demodulator configured to generate a second differential symbol sequence by differencing the first differential symbol sequence; A second correlator configured to compare the second differential symbol sequence with a second differential synchronization word; Wherein the second correlator is configured to generate a second match signal when the second differential symbol sequence substantially matches the second differential synchronization word; and Wherein the first wireless device is configured to establish a link with the second wireless device when both the first match signal and the second match signal are generated.
2. The first wireless device according to claim 1: Characterized in that, The symbol sequence is a training sequence.
3. The first wireless device according to claim 2: It is characterized in that The training sequence is included in the preamble portion of the wireless communication frame.
4. The first wireless device according to claim 2: It is characterized in that The training sequence is a short training sequence (STS).
5. The first wireless device according to claim 1: It is characterized in that The first correlator is configured to compare the first differential symbol sequence with the complex conjugate of the first differential synchronization word; and Wherein the second correlator is configured to compare the second differential symbol sequence with the complex conjugate of the second differential synchronization word.
6. The first wireless device according to claim 1, characterized in that: Further comprising a symbol delay circuit configured to phase-align the first match signal from the first correlator with the second match signal from the second correlator.
7. The first wireless device according to claim 6: Characterized in that, The symbol delay circuit is configured to compensate for the symbol delay added by the second demodulator.
8. The first wireless device according to claim 1, characterized in that: Further comprising a vector summing circuit configured to perform vector summation on the complex-valued signal outputs generated by the first correlator and the second correlator.
9. The first wireless device according to claim 1, characterized in that: Further comprising a peak detection circuit configured to detect peak signals in the vector-summed output from the first correlator and the second correlator.
10. A method for synchronizing a first wireless device with a second wireless device, characterized in that, Comprising: Receiving a symbol sequence in a wireless communication frame transmitted from the second wireless device; Generating a first differential symbol sequence by differencing the received symbol sequence; Comparing the first differential symbol sequence with a first differential synchronization word; If the first differential symbol sequence matches the first differential synchronization word, generating a first match signal; Generating a second differential symbol sequence by differentiating the first differential symbol sequence; Comparing the second differential symbol sequence with a second differential sync word; If the second differential symbol sequence matches the second differential sync word, generating a second match signal; And If both the first match signal and the second match signal are generated, establishing a link between the first wireless device and the second wireless device.