A phase estimation method and device based on statistical average

Abstract

The application provides a phase estimation method and device based on statistical average, which comprises the following steps: inserting pilot symbols into an input sequence at a sending end, and performing MSK modulation on the input sequence after the pilot symbols are inserted; storing a pilot sequence corresponding to the input sequence after the pilot symbols are inserted at the sending end, and performing MSK modulation; at a receiving end, performing correlation calculation on pilot positions corresponding to a plurality of optimal sampling points in the modulated pilot sequence and a received sequence, so as to determine correlation values of the optimal sampling points; and determining a corresponding phase offset value based on average values of the plurality of optimal sampling points. In the correlation process between the received sequence and the local pilot sequence, only the correlation values of the pilot symbol optimal sampling point positions are calculated, so that the calculation amount is reduced compared with a traditional algorithm, and the phase offset estimation performance is better under a low signal-to-noise ratio condition.

Description

Technical Field

[0001] This invention relates to the field of wireless signal technology, and in particular to a phase estimation method and apparatus based on statistical averaging. Background Technology

[0002] Phase offset estimation techniques are applied in fields such as digital signal processing, communication systems, and modulation techniques. In digital communication, signals may be affected by phase offset during transmission through the transmission medium, causing a change in the phase of the received signal. The goal of phase offset estimation is to estimate the magnitude and impact of the phase offset by analyzing the received signal.

[0003] In communication systems, phase offset estimation is crucial for ensuring the accuracy and reliability of data transmission. In modulation techniques, phase offset estimation is primarily used to demodulate signals and recover the original data. Common phase offset estimation methods include the minimum mean square error method, the maximum likelihood method, the pilot method, and signal spatial domain analysis. These methods, based on different mathematical models and statistical properties, are used to estimate and compensate for or correct the phase offset in a signal. By accurately estimating and compensating for the phase offset, signal quality and reliability can be improved, thereby enhancing the performance of the communication system.

[0004] However, the complex and ever-changing wireless environment causes signals to be subjected to various interferences during propagation, resulting in significant changes in the amplitude, phase, and frequency of the signal by the time it reaches the receiver. The purpose of phase offset estimation is to minimize the estimation error and to recover the transmitted signal as accurately as possible at the receiver.

[0005] In the phase estimation process of a binary constant envelope distributed pilot communication system, it is necessary to calculate the correlation results of all sampling points of the pilot positions between the received sequence and the local pilot sequence. This process is computationally complex and introduces significant system errors. Furthermore, under low signal-to-noise ratio conditions, the estimation performance is poor, the bit error rate is high, and it is difficult to accurately recover the transmitted signal. Summary of the Invention

[0006] The technical problem to be solved by the present invention is how to reduce the amount of computation and achieve better phase offset estimation performance under low signal-to-noise ratio conditions; in view of this, the present invention provides a phase estimation method and apparatus based on statistical averaging.

[0007] The technical solution adopted in this invention is a phase estimation method based on statistical averaging, comprising:

[0008] Pilot symbols are inserted into the input sequence at the transmitting end, and MSK modulation is performed on the input sequence after the pilot symbols are inserted.

[0009] The pilot sequence corresponding to the input sequence after the insertion of pilot symbols is stored locally and then MSK modulation is performed, specifically including:

[0010] Insert pilot symbols corresponding to the positions in the input sequence into the pilot sequence;

[0011] The pilot sequence after inserting pilot symbols is differentially encoded to form two code elements representing odd and even positions respectively. The inserted pilot symbols are all located in the odd code elements, and the position of the pilot symbol is determined as the optimal sampling point.

[0012] The two symbols are multiplied by the carrier wave respectively to complete MSK modulation;

[0013] At the receiving end, the correlation calculation is performed between the received sequence and the pilot positions corresponding to multiple optimal sampling points in the modulated pilot sequence to determine the correlation value of each optimal sampling point;

[0014] The corresponding phase offset value is determined based on the average value of multiple optimal sampling points.

[0015] In one embodiment, inserting pilot signals into the input sequence at the transmitting end and performing MSK modulation on the input sequence after inserting pilot symbols includes:

[0016] In the 16-bit input sequence, four pilot symbols are inserted at positions 2, 6, 10, and 14, respectively.

[0017] The input sequence after inserting pilot symbols is differentially encoded to form two code elements representing odd and even positions respectively, wherein the inserted pilot symbols are all located in the odd code elements;

[0018] The two symbols are multiplied by the carrier wave to complete MSK modulation.

[0019] In one implementation, determining the corresponding phase offset value based on the average of multiple optimal sampling points includes:

[0020] The phase offset value was calculated using the Cordic algorithm based on the average value of multiple optimal sampling points.

[0021] Another aspect of the present invention provides a phase estimation device based on statistical averaging, comprising:

[0022] The first modulation unit is configured to insert pilot symbols into the input sequence at the transmitting end and to perform MSK modulation on the input sequence after inserting the pilot symbols.

[0023] The second modulation unit is configured to locally store the pilot sequence corresponding to the input sequence after the pilot symbols are inserted, and to perform MSK modulation, specifically configured as follows:

[0024] Insert pilot symbols corresponding to the positions in the input sequence into the pilot sequence;

[0025] The pilot sequence after inserting pilot symbols is differentially encoded to form two code elements representing odd and even positions respectively. The inserted pilot symbols are all located in the odd code elements, and the position of the pilot symbol is determined as the optimal sampling point.

[0026] The two symbols are multiplied by the carrier wave respectively to complete MSK modulation;

[0027] The correlation value calculation unit is configured to perform correlation calculation at the receiving end between the received sequence and the pilot positions corresponding to multiple optimal sampling points in the modulated pilot sequence, so as to determine the correlation value of each optimal sampling point;

[0028] The phase value calculation unit is configured to determine the corresponding phase offset value based on the average value of multiple optimal sampling points.

[0029] In one embodiment, the first modulation unit is further configured as follows:

[0030] In the 16-bit input sequence, four pilot symbols are inserted at positions 2, 6, 10, and 14, respectively.

[0031] The input sequence after inserting pilot symbols is differentially encoded to form two code elements representing odd and even positions respectively, wherein the inserted pilot symbols are all located in the odd code elements;

[0032] The two symbols are multiplied by the carrier wave to complete MSK modulation.

[0033] In one embodiment, the phase value calculation unit is further configured to:

[0034] The phase offset value was calculated using the Cordic algorithm based on the average value of multiple optimal sampling points.

[0035] Another aspect of the present invention provides an electronic device comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the computer program, when executed by the processor, implements the steps of the phase estimation method based on statistical averaging as described in any of the preceding claims.

[0036] Another aspect of the present invention provides a computer storage medium storing a computer program that, when executed by a processor, implements the steps of the phase estimation method based on statistical averaging as described in any of the preceding claims.

[0037] By adopting the above technical solution, the present invention has at least the following advantages:

[0038] Based on the characteristics of modulation schemes such as MSK and GMSK and distributed pilots, this invention only calculates the correlation value of the optimal sampling point position of the pilot symbol during the correlation process between the received sequence and the local pilot sequence. Compared with traditional algorithms, this reduces the amount of computation and has better phase offset estimation performance under low signal-to-noise ratio conditions. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the phase estimation method based on statistical averaging according to an embodiment of the present invention;

[0040] Figure 2 This is a flowchart of the phase estimation method based on statistical averaging according to an embodiment of the present invention;

[0041] Figure 3 This is a schematic diagram of MSK modulation.

[0042] Figure 4 A schematic diagram of the real and imaginary parts of the local pilot sequence after MSK modulation;

[0043] Figure 5 A comparison chart of estimation error results when SNR=8 (unit: °);

[0044] Figure 6 A comparison chart of estimation error results when SNR=10 (unit: °);

[0045] Figure 7 A comparison chart of estimation error results when SNR=12 (unit: °);

[0046] Figure 8 This is a structural diagram of a phase estimation device based on statistical averaging according to an embodiment of the present invention;

[0047] Figure 9 This is a schematic diagram of an electronic device structure according to an embodiment of the present invention. Detailed Implementation

[0048] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the present invention will be described in detail below with reference to the accompanying drawings and preferred embodiments.

[0049] In the accompanying drawings, the thickness, size, and shape of the objects have been slightly exaggerated for ease of illustration. The drawings are for illustrative purposes only and are not drawn to scale.

[0050] It should also be understood that the terms "comprising," "including," "having," "containing," and / or "comprising," when used in this specification, indicate the presence of the stated features, integrals, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or combinations thereof. Furthermore, when expressions such as "at least one of..." appear after a list of listed features, they modify the entire listed feature, not individual elements in the list. Additionally, when describing embodiments of this application, the word "may" is used to mean "one or more embodiments of this application." And the term "exemplary" is intended to refer to an example or illustration.

[0051] As used herein, the terms “basically,” “approximately,” and similar terms are used as terms of approximation rather than terms of degree, and are intended to describe inherent biases in measured or calculated values ​​that will be recognized by those skilled in the art.

[0052] Unless otherwise specified, all terms used herein (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. It should also be understood that terms (e.g., those defined in common dictionaries) shall be interpreted as having the meaning consistent with their meaning in the context of the relevant art and shall not be interpreted in an idealized or overly formal sense unless expressly so specified herein.

[0053] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0054] For ease of understanding, in the binary constant envelope communication system of this invention, let x n Given the baseband signal at the transmitting end, when there is a carrier phase offset φ, the received signal at the receiving end is r. n =e jφ x n +w n , where w n It is Gaussian white noise.

[0055] Ignoring the effects of Gaussian white noise, if the received local contains x n Pilot sequences x of the same length n ′, for the received sequence r n With local pilot sequence x n By performing correlation, we can obtain:

[0056]

[0057] The carrier phase offset value can then be estimated.

[0058] φ = angle(ph / N)

[0059] Based on the above principles, the first embodiment of the present invention provides a phase estimation method based on statistical averaging, such as... Figure 1 As shown, it includes the following steps:

[0060] Step S1: Insert pilot symbols into the input sequence at the transmitting end, and perform MSK modulation on the input sequence after inserting pilot symbols;

[0061] Step S2 involves locally storing the pilot sequence corresponding to the input sequence after inserting the pilot symbols, and performing MSK modulation, specifically including:

[0062] Insert pilot symbols corresponding to the positions in the input sequence into the pilot sequence;

[0063] The pilot sequence after inserting pilot symbols is differentially encoded to form two code elements representing odd and even positions respectively. The inserted pilot symbols are all located in the odd code elements, and the position of the pilot symbol is determined as the optimal sampling point.

[0064] The two symbols are multiplied by the carrier wave respectively to complete MSK modulation;

[0065] Step S3: At the receiving end, the correlation calculation is performed between the received sequence and the pilot positions corresponding to the multiple optimal sampling points in the modulated pilot sequence to determine the correlation value of each optimal sampling point.

[0066] Step S4: Determine the corresponding phase offset value based on the average value of multiple optimal sampling points.

[0067] refer to Figure 2 The method provided in this embodiment will be described in detail step by step below.

[0068] Step S1: Insert pilot symbols into the input sequence at the transmitting end, and perform MSK modulation on the input sequence after inserting the pilot symbols.

[0069] The input sequence at the sending end is x n ={x0,x1,x2,x3,…x 13 ,x 14 ,x 15}, insert pilot symbols d1, d2, d3, and d4 at positions 2, 6, 10, and 14 respectively, resulting in the following input sequence after pilot insertion:

[0070] x n ′={x0,d1,x2,x3,x4,d2,x6,x7,x8,d3,x 10 ,x11 ,x 12 ,d4,x 14 ,x 15}

[0071] For x n MSK modulation is performed, with an oversampling factor of 16 and a sampling frequency of 80 MHz. The specific modulation process is as follows: Figure 3 ;

[0072] baseband code x n After differential encoding, the code is converted from serial to parallel and split into I and Q paths. The I and Q path symbols are the symbols at the odd and even positions of the relative code after differential encoding, respectively. The I path corresponds to the odd positions, and the Q path corresponds to the even positions.

[0073] x I ={x -1 ,d1,d1,x3,x3,d2,d2,x7,x7,d3,d3,x 11 ,x 11 ,d4,d4,x 15};

[0074] x Q ={x0,x0,x2,x2,x4,x4,x6,x6,x8,x8,x 10 ,x 10 ,x 12 ,x 12 ,x 14 ,x 14}

[0075] As can be seen above, the inserted pilot symbols are all distributed in path I. (The last part, "x", appears to be a typo and can be omitted.) I With x Q The MSK modulation process is completed by multiplying each component with the carrier wave.

[0076] Step S2: Store the pilot sequence corresponding to the input sequence after inserting the pilot symbols locally, and perform MSK modulation.

[0077] The corresponding pilot sequence d is stored locally. n ={0,d1,0,0,0,d2,0,0,0,d3,0,0,0,d4,0,0} undergoing the same MSK modulation to obtain d n The steps are the same as above. During the serial-to-parallel conversion of the pilot sequence:

[0078] d I ={0,d1,d1,0,0,d2,d2,0,0,d3,d3,0,0,d4,d4,0}

[0079] d Q={0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0}

[0080] Modulation result d n 'like Figure 4 As shown, the pilot symbol is at the optimal sampling point position of the I channel, corresponding to an ideal value of 0 for the Q channel.

[0081] Step S3: At the receiving end, the correlation calculation is performed between the received sequence and the pilot positions corresponding to the multiple optimal sampling points in the modulated pilot sequence to determine the correlation value of each optimal sampling point.

[0082] Specifically, at the receiving end, the received sequence r n With the local known pilot sequence d n Correlation calculations are performed, where only the correlation results of the optimal sampling point are calculated for each pilot position, i.e., only the correlation values ​​of the four sampling points 33, 97, 161, and 225 are calculated, where N = 4, n = 33, 97, 161, and 225.

[0083]

[0084] Step S4: Determine the corresponding phase offset value based on the average value of multiple optimal sampling points.

[0085] In other words, the correlation values ​​obtained from the above four sampling points are averaged, and the phase offset value is calculated using the Cordic algorithm.

[0086] φ = angle(ph / N)

[0087] To further illustrate the superiority of this invention in a binary constant envelope pilot distributed communication system, a comparative simulation was conducted between the traditional algorithm and the algorithm proposed in this invention. The SNR was set to 8, 10, and 12, respectively. The estimation error comparison results are as follows: Figure 5 , 6 As shown in Figure 7, the comparison results show that the correlation algorithm based on the optimal sampling point of the pilot position has better phase estimation performance, thereby improving the signal quality and reliability and enhancing the performance of the communication system.

[0088] As can be seen above, when a binary constant envelope communication system uses a distributed pilot insertion method, the pilot symbols are distributed across the I and Q paths during the serial-to-parallel conversion of MSK, GMSK, and other modulation methods. When a pilot symbol is located on the I path, the corresponding locally known pilot symbol is also located on the I path, but at this time, the values ​​of the Q path sampling points of that pilot symbol are mostly unknown. Therefore, during the correlation process, one of the pilot positions on the I or Q path will always be locally unknown, which can easily introduce large system errors.

[0089] This invention proposes a phase estimation method based on the characteristics of modulation schemes such as MSK and GMSK, where the optimal sampling point position of the I-path bits corresponds to an ideal value of 0 in the Q-path. By setting the pilot insertion positions to either an even or odd number of bits, the pilot symbols are distributed across either the I-path or the Q-path. Therefore, during the correlation between the received sequence and the local pilot sequence, for any pilot symbol, the optimal sampling point position of the I-path pilot symbol corresponds to an ideal value of 0 in the Q-path (or vice versa). Thus, the values ​​of both the I and Q-path pilot positions are locally known, enabling a more accurate estimation of the carrier phase.

[0090] In summary, in a binary constant envelope communication system with pilot distributed insertion, phase estimation is performed by calculating the correlation values ​​of only the optimal sampling points of the pilot symbols. This results in smaller estimation errors and lower computational complexity, which is more beneficial for the receiver to recover the transmitted signal. Simulation comparisons show that this correlation algorithm has better phase estimation performance under low signal-to-noise ratio conditions, thus improving the overall receiving performance of the system.

[0091] The second embodiment of the present invention, corresponding to the first embodiment, introduces a phase estimation device based on statistical averaging, such as... Figure 8 As shown, it includes the following components:

[0092] The first modulation unit is configured to insert pilot symbols into the input sequence at the transmitting end and to perform MSK modulation on the input sequence after inserting the pilot symbols.

[0093] The second modulation unit is configured to locally store the pilot sequence corresponding to the input sequence after the pilot symbols are inserted, and to perform MSK modulation, specifically configured as follows:

[0094] Insert pilot symbols corresponding to the positions in the input sequence into the pilot sequence;

[0095] The pilot sequence after inserting pilot symbols is differentially encoded to form two code elements representing odd and even positions respectively. The inserted pilot symbols are all located in the odd code elements, and the position of the pilot symbol is determined as the optimal sampling point.

[0096] The two symbols are multiplied by the carrier wave respectively to complete MSK modulation;

[0097] The correlation value calculation unit is configured to perform correlation calculation at the receiving end between the received sequence and the pilot positions corresponding to multiple optimal sampling points in the modulated pilot sequence, so as to determine the correlation value of each optimal sampling point;

[0098] The phase value calculation unit is configured to determine the corresponding phase offset value based on the average of multiple optimal sampling points.

[0099] In this embodiment, the first modulation unit is further configured as follows:

[0100] In the 16-bit input sequence, four pilot symbols are inserted at positions 2, 6, 10, and 14, respectively.

[0101] The input sequence after inserting pilot symbols is differentially encoded to form two code elements representing odd and even positions respectively, wherein the inserted pilot symbols are all located in the odd code elements;

[0102] The two symbols are multiplied by the carrier wave to complete MSK modulation.

[0103] In this embodiment, the phase value calculation unit is further configured to calculate the phase offset value using the Cordic algorithm based on the average value of multiple optimal sampling points.

[0104] A third embodiment of the present invention provides an electronic device, such as... Figure 9 As shown, it can be understood as a physical device, including a processor and a memory storing processor-executable instructions. When the instructions are executed by the processor, the following operations are performed:

[0105] Step S1: Insert pilot symbols into the input sequence at the transmitting end, and perform MSK modulation on the input sequence after inserting pilot symbols;

[0106] Step S2 involves locally storing the pilot sequence corresponding to the input sequence after inserting the pilot symbols, and performing MSK modulation, specifically including:

[0107] Insert pilot symbols corresponding to the positions in the input sequence into the pilot sequence;

[0108] The pilot sequence after inserting pilot symbols is differentially encoded to form two code elements representing odd and even positions respectively. The inserted pilot symbols are all located in the odd code elements, and the position of the pilot symbol is determined as the optimal sampling point.

[0109] The two symbols are multiplied by the carrier wave respectively to complete MSK modulation;

[0110] Step S3: At the receiving end, the correlation calculation is performed between the received sequence and the pilot positions corresponding to the multiple optimal sampling points in the modulated pilot sequence to determine the correlation value of each optimal sampling point.

[0111] Step S4: Determine the corresponding phase offset value based on the average value of multiple optimal sampling points.

[0112] In the fourth embodiment of the present invention, the flow of the phase estimation method based on statistical averaging is the same as that of the first, second, or third embodiments. The difference lies in the engineering implementation: this embodiment can be implemented using software plus necessary general-purpose hardware platforms. While hardware implementation is also possible, the former is often a better approach. Based on this understanding, the method of the present invention can be embodied in the form of a computer software product stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk), including several instructions to cause a device to execute the method described in the embodiments of the present invention.

[0113] Through the description of specific embodiments, a more in-depth and specific understanding should be gained of the technical means and effects adopted by the present invention to achieve the intended purpose. However, the accompanying drawings are only provided for reference and illustration and are not intended to limit the present invention.

Claims

1. A phase estimation method based on statistical averaging, characterized in that, include: Pilot symbols are inserted into the input sequence at the transmitting end, and MSK modulation is performed on the input sequence after the pilot symbols are inserted. The pilot sequence corresponding to the input sequence after the insertion of pilot symbols is stored locally and then MSK modulation is performed, specifically including: Insert pilot symbols corresponding to the positions in the input sequence into the pilot sequence; The pilot sequence after inserting pilot symbols is differentially encoded to form two code elements representing odd and even positions respectively. The inserted pilot symbols are all located in the odd code elements, and the position of the pilot symbol is determined as the optimal sampling point. The two symbols are multiplied by the carrier wave respectively to complete MSK modulation; At the receiving end, the correlation calculation is performed between the received sequence and the pilot positions corresponding to multiple optimal sampling points in the modulated pilot sequence to determine the correlation value of each optimal sampling point; The corresponding phase offset value is determined based on the average value of multiple optimal sampling points.

2. The phase estimation method based on statistical averaging according to claim 1, characterized in that, The step of inserting pilot signals into the input sequence at the transmitting end and performing MSK modulation on the input sequence after inserting pilot symbols includes: In the 16-bit input sequence, four pilot symbols are inserted at positions 2, 6, 10, and 14, respectively. The input sequence after inserting pilot symbols is differentially encoded to form two code elements representing odd and even positions respectively, wherein the inserted pilot symbols are all located in the odd code elements; The two symbols are multiplied by the carrier wave to complete MSK modulation.

3. The phase estimation method based on statistical averaging according to claim 1, characterized in that, The step of determining the corresponding phase offset value based on the average of multiple optimal sampling points includes: The phase offset value was calculated using the Cordic algorithm based on the average value of multiple optimal sampling points.

4. A phase estimation device based on statistical averaging, characterized in that, include: The first modulation unit is configured to insert pilot symbols into the input sequence at the transmitting end and to perform MSK modulation on the input sequence after inserting the pilot symbols. The second modulation unit is configured to locally store the pilot sequence corresponding to the input sequence after the pilot symbols are inserted, and to perform MSK modulation, specifically configured as follows: Insert pilot symbols corresponding to the positions in the input sequence into the pilot sequence; The pilot sequence after inserting pilot symbols is differentially encoded to form two code elements representing odd and even positions respectively. The inserted pilot symbols are all located in the odd code elements, and the position of the pilot symbol is determined as the optimal sampling point. The two symbols are multiplied by the carrier wave respectively to complete MSK modulation; The correlation value calculation unit is configured to perform correlation calculation at the receiving end between the received sequence and the pilot positions corresponding to multiple optimal sampling points in the modulated pilot sequence, so as to determine the correlation value of each optimal sampling point; The phase value calculation unit is configured to determine the corresponding phase offset value based on the average of multiple optimal sampling points.

5. The phase estimation device based on statistical averaging according to claim 4, characterized in that, The first modulation unit is further configured as follows: In the 16-bit input sequence, four pilot symbols are inserted at positions 2, 6, 10, and 14, respectively. The input sequence after inserting pilot symbols is differentially encoded to form two code elements representing odd and even positions respectively, wherein the inserted pilot symbols are all located in the odd code elements; The two symbols are multiplied by the carrier wave to complete MSK modulation.

6. The phase estimation device based on statistical averaging according to claim 5, characterized in that, The phase value calculation unit is further configured as follows: The phase offset value was calculated using the Cordic algorithm based on the average value of multiple optimal sampling points.

7. An electronic device, characterized in that, The electronic device includes: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the computer program, when executed by the processor, implements the steps of the phase estimation method based on statistical averaging as described in any one of claims 1 to 3.

8. A computer storage medium storing a computer program that, when executed by a processor, implements the steps of the phase estimation method based on statistical averaging as described in any one of claims 1 to 3.

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