Diversity combining method and system based on mixer phase shift adjustment

Abstract

The invention relates to the technical field of diversity combining, and particularly discloses a diversity combining method and system based on mixer phase shift adjustment, and the method comprises the following steps: setting at least two radio frequency front-end links to receive signals at the same time, and combining the at least two paths of received signals before an analog-to-digital converter to obtain a mixed signal; enabling the mixed signal to pass through an analog-to-digital converter, and carrying out phase estimation on the mixed signal in a digital domain; and feeding back a phase estimation result to a frequency mixer of at least one radio frequency front-end link so as to control the phase shift of the frequency mixer of the at least one radio frequency front-end link, and realizing the phase shift operation required by diversity combination while receiving signal down-conversion by the link. According to the diversity combining method based on mixer phase shift adjustment, phase adjustment is carried out on signals of different phases, combination of the signals is optimized, the overall quality of received signals is improved, and the reliability of signal transmission is further improved.

Description

Technical Field

[0001] The present invention relates to the technical field of diversity combining, and in particular to a diversity combining method and system based on mixer phase shift adjustment. Background Art

[0002] Diversity combining is a signal processing technique used in wireless communication systems to improve the reliability and quality of received signals by combining multiple copies of the same signal transmitted via different paths. To achieve diversity combining, the receiver needs to be equipped with multiple antennas to receive signal copies from different paths.

[0003] The basic principle of diversity is to receive multiple copies of the same information via multiple channels (in time, frequency, or space). Due to the different transmission characteristics of these channels, the fading of these multiple copies of the signal will vary. The receiver can use the information contained in these multiple copies to more accurately recover the original transmitted signal. To use diversity combining, the receiver must have two or more antennas and be able to receive signals from each of these antennas. Due to the different distances between the transmitter and each antenna, these signals may arrive at different phases. These phase differences can cause interference and fading, thereby reducing the quality of the received signal.

[0004] In existing technologies, because these signals may have different phases due to path length differences, directly combining them can cause interference and signal quality degradation. By adjusting the phases of signals received from different antennas with different phases, the receiver can optimize the signal combination to improve the overall quality of the received signal. Therefore, it is necessary to design a diversity combining method based on mixer phase shift adjustment to achieve phase optimization of signals with different phases, thereby further improving the overall quality of the received signal. Summary of the Invention

[0005] The object of the present invention is to provide a diversity combining method based on mixer phase shift adjustment to solve the above technical problems.

[0006] The purpose of the present invention can be achieved through the following technical solutions: S1: Setting at least two RF front-end links to simultaneously receive signals, and combining at least two received signals before an analog-to-digital converter to obtain a mixed signal; S2: The mixed signal passes through an analog-to-digital converter and performs phase estimation on the mixed signal in the digital domain; S3: Feedback the phase estimation result to the mixer of at least one RF front-end link, thereby controlling the phase shift of the mixer of the at least one RF front-end link, and realizing the phase shift operation required for diversity combining while down-converting the received signal of the link.

[0007] As a further solution of the present invention: the steps S1-S3 are performed in the synchronization field portion of the received frame, and the subsequent received signal maintains the mixer phase shift obtained in step S3 unchanged.

[0008] As a further solution of the present invention: S2 comprises the following steps: S21: Calculate the channel parameters of the mixed signal, adjust the mixed signal according to the phase shift value A+na, output the corresponding phase shift value when the intensity of the mixed signal reaches a peak value and record it as the ideal phase shift value, where A is a preset initial phase shift value, a is a preset change gradient, and n=1, 2, 3, ...; S22: applying the ideal phase shift value to the mixed signal to obtain a corrected mixed signal, and combining the corrected mixed signals to generate a multi-channel combined signal.

[0009] As a further solution of the present invention: in the step S1, the mixed signal is obtained from the synchronization field portion of the received frame.

[0010] As a further solution of the present invention: in step S21, the method for adjusting the mixed signal specifically includes: Generate a waveform corresponding to the mixed signal in a two-dimensional coordinate system, preset a reference point and obtain the signal strength of the mixed signal at the reference point, move the waveform corresponding to the mixed signal by A+na unit distance, and stop moving when the signal strength of the mixed signal at the reference point reaches a peak.

[0011] As a further solution of the present invention: in step S1, the mixed signal is also used to achieve time and frequency synchronization with the transmitter.

[0012] As a further solution of the present invention: in step S2, when generating the mixed signal, the two signals are assigned different analog gains.

[0013] As a further solution of the present invention: in the step S2, the blind phase estimation gradually narrows the search range by adopting the dichotomy method to ensure that the phase difference between at least two signals is within 120 degrees, which can have diversity gain, and then adopts a smaller phase difference value.

[0014] As a further solution of the present invention: in step S2, the mixed signal includes more than one version, and each version corresponds to a different analog gain combination of the two signals.

[0015] An analog diversity combining system based on mixer phase shift adjustment includes: at least two radio frequency front-end links, each having a corresponding receiving antenna, and the at least two radio frequency front-end links sharing a local oscillator and an analog-to-digital converter; the at least two radio frequency front-end links are configured to simultaneously receive signals, and the at least two received signals are combined before the analog-to-digital converter to obtain a mixed signal; Phase estimation module: configured to perform phase estimation in the digital domain on the mixed signal passing through the analog-to-digital converter; Adjustment module: controls the phase shift of the mixer of at least one RF front-end link according to the phase estimation result, so that the phase shift operation required for diversity combining is achieved while down-converting the received signal of the link.

[0016] As a further solution of the present invention: an analog diversity combining system based on mixer phase shift adjustment is configured to receive pulse ultra-wideband signals.

[0017] Beneficial effects of the present invention: The present invention designs a diversity combining method based on mixer phase shift adjustment, which optimizes the phase of signals with different phases received from different antennas and optimizes the combination of signals to improve the overall quality of the received signal and further improve the reliability of signal transmission. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The present invention will be further described below with reference to the accompanying drawings.

[0019] Figure 1 It is a flow chart of a diversity combining method and system based on mixer phase shift adjustment of the present invention; Figure 2 It is the basic framework of a diversity combining method and system based on mixer phase shift adjustment of the present invention; Figure 3 This is the basic architecture of a dual-antenna receiver of a diversity combining method and system based on mixer phase shift adjustment of the present invention; Figure 4 The present invention is a basic architecture of a multi-antenna receiver based on a diversity combining method and system for adjusting mixer phase shift; Figure 5 It is a vector operation diagram of a diversity combining method and system for mixer phase shift adjustment according to the present invention; Figure 6 This is a schematic diagram of a dichotomy method for reducing the phase difference range based on a diversity combining method and system for mixer phase shift adjustment according to the present invention; Figure 7 It is the actual basic framework of the diversity combining method and system based on mixer phase shift adjustment of the present invention. DETAILED DESCRIPTION

[0020] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0021] See also Figure 1 As shown, the present invention is a diversity combining method based on mixer phase shift adjustment, comprising the following steps: S1: Setting at least two RF front-end links to simultaneously receive signals, and combining at least two received signals before an analog-to-digital converter to obtain a mixed signal; S2: The mixed signal passes through an analog-to-digital converter and performs phase estimation on the mixed signal in the digital domain; S3: Feedback the phase estimation result to the mixer of at least one RF front-end link, thereby controlling the phase shift of the mixer of the at least one RF front-end link, and realizing the phase shift operation required for diversity combining while down-converting the received signal of the link.

[0022] It should be noted that the signal loss in the transmission path and the signal strength of the antenna are two key factors that directly affect the quality and accuracy of information transmission.

[0023] First, the signal loss along the transmission path needs to be calculated based on the distance between the transmitter and the antenna. From a physical perspective, signals gradually attenuate as distance increases during propagation, and this attenuation is primarily affected by the distance between the transmitter and the antenna. Specifically, when a transmitter transmits a signal, the signal diffuses into the surrounding space in the form of a spherical wave. As the propagation distance increases, the area of ​​the sphere continues to expand, while the signal energy is evenly distributed across this expanding sphere. Due to the law of conservation of energy, the signal energy received per unit area decreases accordingly, resulting in a decrease in signal strength, which is the result of path loss.

[0024] like Figure 2 The figure below shows the basic framework of the entire system, representing the working principle of receiver diversity combining. The transmitter transmits a signal, which travels through different channels as multiple copies reaching the receiver's multiple antennas. The receiver simultaneously receives the different copies of the signal through multiple antennas and combines them. This reduces or overcomes signal fading caused by multipath propagation and shadowing in the wireless channel, thereby improving received signal quality and communication system reliability. Common combining techniques include selective combining, equal gain combining, and maximum ratio combining.

[0025] in, Figure 3 and Figure 4These are the basic architectures for dual-antenna and multi-antenna receivers, respectively. The advantage of these architectures lies in the minimal modification of the analog circuitry and the digital computational complexity, as they control diversity combining by adjusting the mixer phase shift. This is because only one mixed signal enters the DSP, eliminating the need for parallel processing of multiple digital signals. The mixer itself is an essential module in the receive chain. By controlling its phase, downconversion can be achieved simultaneously, while applying different phase shifts to different signals. This avoids the need for additional modules in the signal chain, further reducing implementation complexity and power consumption.

[0026] Next, we need to calculate the antenna's signal strength. Antenna signal strength is a key indicator of signal quality, reflecting the actual strength of the signal when it reaches the antenna after traveling through the transmission path. Signal strength depends not only on the transmitter's power and transmission path losses, but also on antennas with higher gain, which can more effectively focus and receive signals, thereby improving received signal strength. Antennas with strong directivity can better receive signals in a specific direction, minimizing the impact of interference from other directions.

[0027] It is worth noting that the present invention ignores obstacles in the transmission path when calculating signal transmission path loss and antenna signal strength, thereby simplifying the calculation process. In actual wireless communication environments, signals often encounter various obstacles during propagation. Obstacles can reflect, refract, and scatter signals, causing the signal propagation path to become complex and diverse. Reflection can cause some signal energy to change its propagation direction and return to the original propagation path, where it may overlap or cancel out other signals. However, through this simplified processing, preliminary evaluation and analysis of signal transmission characteristics can be performed more quickly and efficiently.

[0028] In advanced wireless communication receiving systems, multiple antennas are then used to receive the same signal to obtain corresponding signal copies.

[0029] After acquiring these signal replicas, each signal replica is mixed with a pre-set standard signal to produce the corresponding mixed signal. This mixing process is equivalent to vector operations, involving the comprehensive consideration of multiple key parameters such as the signal amplitude and phase.

[0030] Compare the signal strengths of the two signals. If the signal strength of the mixed signal is greater than that of the duplicate mixed signal, repeat the above steps. Figure 5As shown, signal superposition is equivalent to vector operations. If the phase difference between the two signals is 180 degrees (π radians), destructive interference will occur at the receiver (RX), causing the signals to cancel each other out. However, if the phase difference is within 120 degrees, the combined signal will be stronger, achieving greater antenna gain. Using two signals, hierarchical combining can achieve a gain of up to 2-3dB, which is very beneficial when the received signal is weak (e.g., long distance between TX and RX). Figure 5 What is shown is the merge operation between vectors; Figure 6 In the present invention, considering the actual usage scenario, the phase difference between two (or multiple) received signals is uncertain. When it is impossible to use a known signal for phase estimation, the present invention proposes to control the phase shifter as follows: gradually narrow the search range by adopting a binary search method, such as first using a 180-degree phase shift and comparing the sizes of the front and back mixed signals to ensure that the phase difference between at least two signals is within 120 degrees to achieve diversity gain; then use a smaller phase difference value for further adjustment. Figure 6 Two cases are shown. In the example on the left, when a 180-degree phase shift is applied to RX2, the new mixed signal RX_m becomes smaller than the original mixed signal RXm, so it can be inferred that the phase difference between the received signal on RX1 and the original received signal on RX2 is less than 120 degrees. In the example on the right, on the contrary, when a 180-degree phase shift is applied to RX2, the new mixed signal RX_m becomes larger than the original mixed signal RXm, so it can be inferred that the phase difference between the received signal on RX1 and the original received signal on RX2 is greater than 120 degrees. This helps to quickly lock the blind search range.

[0031] In another preferred embodiment of the present invention, steps S1-S3 are performed in the synchronization field portion of the received frame, and the subsequent received signal maintains the mixer phase shift obtained in step S3 unchanged.

[0032] It is worth noting that adjusting the synchronization field of the received frame requires minimal changes to the analog circuitry and minimal computational effort in the digital circuitry, as only one mixed signal enters the DSP, eliminating the need for parallel processing of multiple digital signals. The mixer itself is an essential module in the receive chain. By controlling its phase, it simultaneously achieves downconversion and applies different phase shifts to different signals, avoiding the need for additional modules in the signal chain, further reducing implementation complexity and power consumption. In another preferred embodiment of the present invention, the following steps are included: S21: Calculate the channel parameters of the mixed signal, adjust the mixed signal according to the phase shift value A+na, output the corresponding phase shift value when the intensity of the mixed signal reaches a peak value and record it as the ideal phase shift value, where A is a preset initial phase shift value, a is a preset change gradient, and n=1, 2, 3, ...; S22: applying the ideal phase shift value to the mixed signal to obtain a corrected mixed signal, and combining the corrected mixed signals to generate a multi-channel combined signal.

[0033] It is worth noting that a method for adjusting and optimizing a mixed signal is described, specifically an adjustment strategy based on a phase shift value. The preset initial phase shift value and the change gradient provide a flexible way to adjust the phase shift value. By changing these parameters, it is possible to adapt to different signal characteristics and requirements, thereby achieving the best signal adjustment effect. Combining the corrected mixed signals to generate a multi-channel combined signal can further improve the quality and reliability of the signal. The multi-channel combined signal can provide a higher signal-to-noise ratio and stronger anti-interference ability, thereby improving the performance of the communication system. By optimizing the phase shift value of the mixed signal, the interference effect of the signal can be improved, thereby reducing signal distortion and noise. This helps to improve the efficiency of the communication system and the data transmission rate.

[0034] In another preferred embodiment of the present invention, the mixed signal is obtained in the synchronization field portion of the received frame.

[0035] It's worth noting that the receive frame, as the basic unit of data transmission, typically consists of multiple distinct fields, each carrying specific information. The synchronization field plays a crucial role. When a sender and receiver communicate, the sender inserts a synchronization field at a specific location within the data. This field contains crucial information for synchronization between the two ends. By capturing mixed signals within the synchronization field of the receive frame, the receiving device can accurately understand the rhythm and logic of data transmission, laying a solid foundation for subsequent signal processing and data recovery. This mechanism of capturing mixed signals at specific locations fully leverages the structural characteristics of the receive frame and the identifying function of the synchronization field, ensuring the efficiency and reliability of the communication system and enabling accurate data transmission from sender to receiver even in complex communication environments.

[0036] In another preferred embodiment of the present invention, the method for adjusting the mixed signal specifically includes: Generate a waveform corresponding to the mixed signal in a two-dimensional coordinate system, preset a reference point and obtain the signal strength of the mixed signal at the reference point, move the waveform corresponding to the mixed signal by A+na unit distance, and stop moving when the signal strength of the mixed signal at the reference point reaches a peak.

[0037] It should be noted that according to Figure 5As mentioned above, signal superposition is equivalent to vector operations. If the phase difference between the two signals is 180 degrees (π radians), destructive interference will occur at the receiver (RX), causing the signals to cancel each other out. However, if the phase difference is within 120 degrees, the combined signal will have higher strength, achieving antenna gain. Using two signals, hierarchical combining can achieve a gain of up to 2-3 dB, which is particularly beneficial when the received signal is weak (e.g., when the TX-RX distance is long). Diversity combining is controlled by adjusting the mixer phase shift, requiring minimal changes to the analog circuitry and minimal digital computation. This is because only one mixed signal enters the DSP, eliminating the need for parallel processing of multiple digital signals. The mixer itself is an essential module in the receive chain. By controlling its phase, it can simultaneously downconvert and apply different phase shifts to different signals, eliminating the need for additional modules in the signal chain, further reducing implementation complexity and power consumption.

[0038] In another preferred embodiment of the present invention, the mixed signal is also used to achieve time and frequency synchronization with the transmitter.

[0039] It should be noted that in the actual communication process, the receiver needs to maintain highly precise synchronization with the transmitter in terms of time and frequency to ensure that data can be transmitted and received accurately.

[0040] From a time synchronization perspective, the mixed signal contains specific time-related information. By accurately parsing and processing the received mixed signal, the receiver can obtain the time reference information used by the transmitter. For example, in some digital communication systems, the mixed signal may embed a specific clock signal or timestamp information. By identifying and extracting this information, the receiver can calibrate its own clock to synchronize it with the transmitter's clock. This time synchronization is crucial for accurate data transmission, as even the slightest time deviation can cause errors or confusion in data transmission, impacting the overall performance of the communication system.

[0041] In another preferred embodiment of the present invention, when generating the mixed signal, the two signals are assigned different analog gains.

[0042] It's important to note that by assigning different analog gains to the two signals, the difference in their strength can be effectively balanced, ensuring that during the subsequent mixing process, the overall quality and effect of the final mixed signal will not be affected by the excessive or insufficient strength of one signal. From a technical perspective, this involves precise control of the signal amplification circuit and the appropriate adjustment of relevant parameters. This allows the two signals to be mixed in a more compatible state after analog gain processing, thereby providing a high-quality, stable mixed signal for numerous application scenarios such as audio processing and communication systems, meeting the stringent signal processing requirements of different scenarios.

[0043] In another preferred embodiment of the present invention, blind phase estimation gradually narrows the search range by using a binary method to ensure that the phase difference between at least two signals is within 120 degrees to achieve diversity gain, and then uses a smaller phase difference value.

[0044] It should be noted that according to Figure 6 It can be seen that when the phase difference between the two received signals is an uncertain value, it is impossible to use a known signal for phase estimation. The present invention proposes to control the phase shifter as follows: gradually narrow the search range by adopting a binary search method, such as first using a 180-degree phase shift and comparing the sizes of the front and back mixed signals to ensure that the phase difference between at least the two signals is within 120 degrees to achieve diversity gain; then use a smaller phase difference value for further adjustment. Figure 6 Two cases are shown. In the example on the left, when a 180-degree phase shift is applied to RX2, the new mixed signal RX_m becomes smaller than the original mixed signal RXm, so it can be inferred that the phase difference between the received signal on RX1 and the original received signal on RX2 is less than 120 degrees. In the example on the right, on the contrary, when a 180-degree phase shift is applied to RX2, the new mixed signal RX_m becomes larger than the original mixed signal RXm, so it can be inferred that the phase difference between the received signal on RX1 and the original received signal on RX2 is greater than 120 degrees. This helps to quickly lock the blind search range.

[0045] In another preferred embodiment of the present invention, the mixed signal includes more than one version, and each version corresponds to a different analog gain combination of the two signals.

[0046] It's worth noting that in certain application scenarios, when it's necessary to emphasize the high-frequency component of one signal while attenuating the low-frequency interference of another, a higher analog gain is set for the former to increase the proportion of its high-frequency components in the mixed signal; while a relatively lower analog gain is configured for the latter to reduce the impact of its low-frequency components on the overall mixed signal. This diverse analog gain combination allows for the creation of multiple versions of mixed signals, each with unique advantages tailored to specific application requirements.

[0047] An analog diversity combining system based on mixer phase shift adjustment, comprising: At least two radio frequency front-end links, each having a corresponding receiving antenna, and the at least two radio frequency front-end links share a local oscillator and an analog-to-digital converter; the at least two radio frequency front-end links are configured to simultaneously receive signals, and the at least two received signals are combined before the analog-to-digital converter to obtain a mixed signal; Phase estimation module: configured to perform phase estimation in the digital domain on the mixed signal passing through the analog-to-digital converter; Adjustment module: controls the phase shift of the mixer of at least one RF front-end link according to the phase estimation result, so that the phase shift operation required for diversity combining is achieved while down-converting the received signal of the link.

[0048] Pulse ultra-wideband (UWB) technology is a popular technology for precise positioning and tracking applications. It uses short-duration radio wave pulses that can penetrate walls and other obstacles. This makes it ideal for applications such as ranging, location tracking, asset tracking, and high-speed wireless data transmission.

[0049] The analog diversity combining system based on mixer phase shift adjustment can be configured to receive pulse ultra-wideband signals, thereby further improving the performance of the ultra-wideband communication system.

[0050] In another preferred embodiment of the present invention, an analog diversity combining system based on mixer phase shift adjustment is configured to receive pulse ultra-wideband signals.

[0051] The above is a detailed description of an embodiment of the present invention. However, the content described is only a preferred embodiment of the present invention and should not be considered to limit the scope of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. A diversity combining method based on mixer phase shift adjustment, characterized in that: The method is applicable to a low-cost receiver having at least two radio frequency front-end chains, each of which has a corresponding receiving antenna, and the at least two radio frequency front-end chains share a local oscillator and an analog-to-digital converter. The method includes the following steps: S1: Setting at least two RF front-end links to simultaneously receive signals, and combining at least two received signals before an analog-to-digital converter to obtain a mixed signal; S2: The mixed signal passes through an analog-to-digital converter and performs phase estimation on the mixed signal in the digital domain; S3: Feedback the phase estimation result to the mixer of at least one RF front-end link, thereby controlling the phase shift of the mixer of the at least one RF front-end link, and realizing the phase shift operation required for diversity combining while down-converting the received signal of the link.

2. The diversity combining method based on mixer phase shift adjustment according to claim 1, characterized in that: The steps S1-S3 are performed in the synchronization field portion of the received frame, and the subsequent received signal maintains the mixer phase shift obtained in step S3 unchanged.

3. The diversity combining method based on mixer phase shift adjustment according to claim 1, characterized in that: The S2 comprises the following steps: S21: Calculate the channel parameters of the mixed signal, adjust the mixed signal according to the phase shift value A+na, output the corresponding phase shift value when the intensity of the mixed signal reaches a peak value and record it as the ideal phase shift value, where A is a preset initial phase shift value, a is a preset change gradient, and n=1, 2, 3, ...; S22: applying the ideal phase shift value to the mixed signal to obtain a corrected mixed signal, and combining the corrected mixed signals to generate a multi-channel combined signal.

4. The diversity combining method based on mixer phase shift adjustment according to claim 1, characterized in that: In step S1, a mixed signal is obtained in the synchronization field portion of a received frame.

5. The diversity combining method based on mixer phase shift adjustment according to claim 3, characterized in that: In step S21, the method for adjusting the mixed signal specifically includes: Generate a waveform corresponding to the mixed signal in a two-dimensional coordinate system, preset a reference point and obtain the signal strength of the mixed signal at the reference point, move the waveform corresponding to the mixed signal by A+na unit distance, and stop moving when the signal strength of the mixed signal at the reference point reaches a peak.

6. The diversity combining method based on mixer phase shift adjustment according to claim 1, characterized in that: In step S1 , the mixed signal is also used to achieve time and frequency synchronization with the transmitter.

7. The diversity combining method based on mixer phase shift adjustment according to claim 1, characterized in that: In step S2, when generating the mixed signal, the two signals are assigned different analog gains.

8. The diversity combining method based on mixer phase shift adjustment according to claim 1, characterized in that: In step S2, the blind phase estimation gradually narrows the search range by using a dichotomy method to ensure that the phase difference between at least two signals is within 120 degrees to achieve diversity gain, and then uses a smaller phase difference value.

9. The diversity combining method based on mixer phase shift adjustment according to claim 1, characterized in that: In step S2, the mixed signal includes more than one version, and each version corresponds to a different analog gain combination of the two signals.

10. An analog diversity combining system based on mixer phase shift adjustment, characterized in that: include: At least two radio frequency front-end links, each having a corresponding receiving antenna, and the at least two radio frequency front-end links share a local oscillator and an analog-to-digital converter; The at least two RF front-end links are configured to receive signals simultaneously, and the at least two received signals are combined before the analog-to-digital converter to obtain a mixed signal; Phase estimation module: configured to perform phase estimation in the digital domain on the mixed signal passing through the analog-to-digital converter; Adjustment module: controls the phase shift of the mixer of at least one RF front-end link according to the phase estimation result, so that the phase shift operation required for diversity combining is achieved while down-converting the received signal of the link.

11. The analog diversity combining system based on mixer phase shift adjustment according to claim 10, configured to receive pulse ultra-wideband signals.

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