A carrier recursive estimation method and device based on frequency dynamic partitioning

Abstract

The application discloses a carrier recursive estimation method and device based on frequency dynamic partitioning, and belongs to the technical field of communication signal processing. The method comprises the following steps: a modulation signal is generated by a sending end, and Mth power demodulation processing is performed on a received signal by a receiving end; initial frequency partitioning is performed within a given frequency offset range, the period amplitudes corresponding to the end points of each partition are calculated, and the end points corresponding to the maximum and the second maximum are selected as the search range of the next recursion; the frequency offset estimation interval is narrowed through multiple recursions, finally, the frequency offset estimation value is obtained by using the end point corresponding to the maximum period amplitude of the last recursion, and the phase offset estimation value is obtained by using the phase information thereof; and finally, carrier compensation is performed on the received signal. Through dynamic frequency partitioning and recursive search, high-precision frequency offset and phase offset estimation in a high-dynamic and low-latency scene are realized, and the method has the advantages of fast estimation speed, high precision and low complexity.

Description

Technical Field

[0001] This invention belongs to the field of communication signal processing technology, specifically relating to a carrier recursive estimation method and apparatus based on frequency dynamic partitioning. Background Technology

[0002] Low-Earth orbit (LEO) satellite internet, as a crucial component of future 6G networks, boasts advantages such as wide coverage, high speed, and strong anti-interference capabilities, making it a key technology for achieving integrated space-air-ground global coverage. However, the significant Doppler frequency shift and its dynamic changes caused by the high-speed motion of LEO satellites place higher demands on carrier synchronization technology. Simultaneously, the increasing demand from users for high-speed data transmission necessitates systems supporting larger bandwidth applications, further increasing the difficulty of achieving high-precision, low-latency carrier synchronization.

[0003] Carrier synchronization is a crucial process for ensuring the receiver accurately recovers the carrier frequency and phase from the transmitter, and its performance directly affects the signal demodulation quality. Existing carrier synchronization methods mainly fall into two categories: closed-loop carrier synchronization based on phase-locked loop (PLL) technology and open-loop carrier synchronization based on parameter estimation. Closed-loop methods, such as decision feedback loops and Costas loops, rely on PLL technology. Their locking time and phase noise performance are limited by the loop filter, resulting in poor adaptability to rapidly changing frequency offsets, insufficient stability and noise immunity, making it difficult to meet the requirements of high-dynamic, low-latency communication. Open-loop methods, such as Fitz, M&M, and L&R algorithms, while offering lower latency, still suffer from challenges in balancing frequency offset estimation range and accuracy, and high algorithm complexity.

[0004] Therefore, existing methods are insufficient to simultaneously achieve wide frequency offset range, high estimation accuracy, and low computational complexity in high-dynamic scenarios such as low-Earth orbit satellites. A novel carrier synchronization method is urgently needed to address these technical bottlenecks. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a carrier recursive estimation method and apparatus based on frequency dynamic partitioning. For a given frequency offset variation range, several frequency partitions are divided. The two partition endpoints with the largest corresponding period amplitudes are calculated and selected to form the frequency range for the next estimation. After several recursive operations, the frequency offset estimate is obtained by using the partition endpoints corresponding to the largest period amplitude in the last recursive search. The phase information contained therein is used to obtain the phase offset estimate.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A carrier recursive estimation method based on frequency dynamic partitioning, the method comprising:

[0008] Step 1: The transmitting end generates the original information sequence and modulates it to obtain the digital baseband signal;

[0009] Step 2: The receiving end receives the digital baseband signal as a received information sequence and processes it to obtain a demodulated signal sequence;

[0010] Step 3: For the demodulated signal sequence, perform frequency partitioning within the initial frequency offset range, calculate the period amplitude at the endpoints of each partition, and select the endpoints with the largest and second largest period amplitudes as the search range for the next recursive estimation.

[0011] Step 4: Dynamically update the current recursive frequency offset search interval and partition endpoints to gradually narrow the frequency offset estimation range;

[0012] Step 5: After the recursion is completed, calculate the frequency offset estimate and phase offset estimate based on the partition endpoints corresponding to the final maximum period amplitude.

[0013] Step 6: Perform carrier compensation on the received information sequence based on the frequency offset estimate and phase offset estimate.

[0014] On the other hand, the present invention provides a carrier recursive estimation apparatus based on frequency dynamic partitioning, comprising:

[0015] The modulation module is used by the transmitting end to generate the original information sequence and modulate it to obtain a digital baseband signal;

[0016] The processing module is used to receive the digital baseband signal as a received information sequence at the receiving end, and process it to obtain a demodulated signal sequence;

[0017] The calculation module is used to divide the frequency into partitions within the initial frequency offset range for the demodulated signal sequence, calculate the periodic amplitude at the endpoints of each partition, and select the endpoints with the largest and second largest periodic amplitudes as the search range for the next recursive estimation.

[0018] The update module is used to dynamically update the current recursive frequency offset search interval and partition endpoints, gradually narrowing the frequency offset estimation range;

[0019] The estimation module is used to calculate the frequency offset estimate and phase offset estimate based on the partition endpoints corresponding to the final maximum period amplitude after the recursion is completed.

[0020] The compensation module is used to perform carrier compensation on the received information sequence based on the frequency offset estimate and the phase offset estimate.

[0021] Thirdly, the present invention provides an electronic device, comprising: one or more processors; and a memory for storing one or more programs; wherein, when the one or more programs are executed by the one or more processors, the one or more processors implement the aforementioned carrier recursive estimation method based on frequency dynamic partitioning.

[0022] Fourthly, the present invention provides a computer-readable storage medium having executable instructions stored thereon, which, when executed by a processor, enable the processor to implement the aforementioned carrier recursive estimation method based on frequency dynamic partitioning.

[0023] The beneficial effects of this invention are as follows:

[0024] First, this invention dynamically divides the frequency range for frequency offset estimation through a recursive process. Each recursion only requires simple complex multiplication and addition operations. When an appropriate number of partitions is set, it can achieve fast frequency offset search with very few recursions, effectively adapting to application scenarios with high dynamics and large frequency offset ranges, and significantly reducing estimation latency.

[0025] Secondly, this invention innovatively utilizes the phase information directly carried by the period amplitude obtained during the frequency offset search process to calculate the phase offset estimate, eliminating the need for an independent phase estimation process, thereby achieving high-precision joint frequency offset and phase offset estimation with extremely low latency.

[0026] Finally, based on the maximum likelihood estimation criterion, this invention does not require pilot assistance. It removes modulation information by performing M-th power operations on the MPSK signal and improves estimation accuracy by using multi-symbol accumulation. While ensuring high-precision performance, it significantly reduces algorithm complexity and implementation cost. Attached Figure Description

[0027] Figure 1 This is a flowchart of a carrier recursive estimation method based on frequency dynamic partitioning according to the present invention.

[0028] Figure 2 This is a schematic diagram of the frequency offset estimation process;

[0029] Figure 3 This is a simulation comparison diagram of the estimation accuracy performance of the present invention and existing technical methods for binary phase shift keying received signals.

[0030] Figure 4 This diagram illustrates a comparison of the algorithm complexity and performance of the present invention and existing technologies for receiving binary phase shift keying signals. Detailed Implementation

[0031] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0032] like Figure 1 As shown, this invention provides a carrier recursive estimation method based on dynamic frequency partitioning. Each recursive estimation process calculates the periodic amplitude at each partition endpoint based on the maximum likelihood criterion to determine the frequency range for the next estimation. This allows for rapid acquisition of frequency offset estimation accuracy close to the theoretical limit with fewer recursive iterations. The phase offset estimate is directly obtained from the phase information contained in the maximum periodic amplitude, resulting in low estimation delay and high estimation accuracy. The method includes the following steps:

[0033] Step 1: The transmitting end generates the original information sequence and modulates it to obtain the digital baseband signal.

[0034] The transmitting end generates the original information sequence of multi-level phase shift keying modulation. ,in, It is the nth symbol in the transmitted information sequence, and its expression is shown in equation (1):

[0035] (1)

[0036] in, The symbol phase of the multi-level phase-shift keying modulation of the nth symbol. M is the modulation order. For the carrier frequency of the transmitted signal, The initial phase of the transmitted signal is given, with a symbol period of . Each frame of information sequence contains N symbols, where j is the imaginary unit.

[0037] Step 2: The receiving end receives the digital baseband signal as the received information sequence and performs an M-th power operation to obtain the demodulation signal sequence.

[0038] by This represents the received information sequence, where It is the nth symbol in the received information sequence. As shown in equation (2):

[0039] (2)

[0040] in, as well as These are the residual frequency offset and residual phase offset of the received information sequence, respectively. With a mean of 0 and a variance of Complex Gaussian white noise.

[0041] For received information sequences with residual frequency offset Perform M-power processing to remove modulation information and obtain the demodulated signal sequence. ,in It is the nth symbol of the demodulated information sequence, as shown in equation (3):

[0042] (3)

[0043] in, The noise signal carried by the demodulated signal sequence.

[0044] Step 3: For the demodulated signal sequence, perform frequency partitioning within the initial frequency offset range, calculate the period amplitude at the endpoints of each partition, and select the endpoints with the largest and second largest period amplitudes as the search range for the next recursive estimation.

[0045] Define the demodulation signal sequence Regarding frequency points periodic amplitude The expression is as follows:

[0046] (4)

[0047] Given frequency offset variation range ( The maximum number of recursions is The number of frequency partitions is V. The median frequency of the k-th recursive search region. For the k-th recursive search partition endpoints ( ), Let be the size of each partition in the k-th recursion. The endpoint of the partition corresponding to the maximum periodic amplitude in the k-th recursion. This is the endpoint of the partition corresponding to the second-largest periodic amplitude in the k-th recursion.

[0048] Initialize the median frequency points of the first recursive estimation partition size The vth partition endpoint Calculate the corresponding endpoints of each partition according to equation (4). ,in ,Pick The partition endpoints corresponding to the median maximum and second-highest maximum values , ,Right now:

[0049] (5)

[0050] Step 4: Based on the search range obtained from the previous recursion, dynamically update the frequency offset search interval and partition endpoints of the current recursion, calculate the period amplitude of each new partition endpoint, and recursively perform the selection operation to gradually narrow the frequency offset estimation range.

[0051] like Figure 2 As shown, starting from the k-th (k≥2) recursive estimation, the median frequency of the k-th recursive search is determined based on the search result of the previous recursion, i.e., the (k-1)-th recursive search. partition size The vth partition endpoint Calculate the corresponding endpoints of each partition according to equation (4). ,in ,Pick The partition endpoints corresponding to the median maximum and second-highest maximum values , ,Right now:

[0052] (6)

[0053] Step 5: After the recursion is completed, calculate the frequency offset estimate and phase offset estimate based on the partition endpoints corresponding to the final maximum period amplitude.

[0054] Repeat step 4 until the maximum number of recursions is reached, i.e. , obtain the received information sequence Final frequency offset valuation As shown in equation (7):

[0055] (7)

[0056] Received information sequence Final phase bias valuation As shown in equation (8):

[0057] (8)

[0058] Step 6: Perform carrier compensation on the received information sequence based on the frequency offset estimate and phase offset estimate.

[0059] For the received information sequence Carrier compensation is performed as shown in equation (9):

[0060] (9)

[0061] This invention achieves high-precision, low-delay carrier frequency offset search in the frequency domain using a partitioned recursive search method based on the maximum likelihood estimation criterion, according to the given frequency offset variation range, through the above six steps. Furthermore, it utilizes the phase information carried by the periodic diagram to achieve rapid estimation of carrier phase offset, and finally performs carrier compensation on the received information, thus realizing accurate and rapid carrier synchronization suitable for high-dynamic, high-throughput communication scenarios of low-Earth orbit satellites.

[0062] like Figure 3 The diagram shows a simulation comparison of the estimation accuracy performance of the carrier recursive estimation method and device based on dynamic frequency partitioning of the present invention with that of the Kay algorithm, L&R algorithm, Fitz algorithm, Rife algorithm and M&M algorithm for binary phase shift keying received signals.

[0063] like Figure 4The diagram shows a comparison of the algorithm complexity and performance of the carrier recursive estimation method and apparatus based on dynamic frequency partitioning of the present invention with the Kay algorithm, L&R algorithm, Fitz algorithm, Rife algorithm and M&M algorithm for binary phase shift keying received signals.

[0064] On the other hand, the present invention provides a carrier recursive estimation device based on frequency dynamic partitioning, which includes modules capable of implementing the steps of the aforementioned method, specifically including:

[0065] The modulation module is used by the transmitting end to generate the original information sequence and modulate it to obtain a digital baseband signal;

[0066] The processing module is used to receive the digital baseband signal as a received information sequence at the receiving end, and process it to obtain a demodulated signal sequence;

[0067] The calculation module is used to divide the frequency into partitions within the initial frequency offset range for the demodulated signal sequence, calculate the periodic amplitude at the endpoints of each partition, and select the endpoints with the largest and second largest periodic amplitudes as the search range for the next recursive estimation.

[0068] The update module is used to dynamically update the current recursive frequency offset search interval and partition endpoints, gradually narrowing the frequency offset estimation range;

[0069] The estimation module is used to calculate the frequency offset estimate and phase offset estimate based on the partition endpoints corresponding to the final maximum period amplitude after the recursion is completed.

[0070] The compensation module is used to perform carrier compensation on the received information sequence based on the frequency offset estimate and the phase offset estimate.

[0071] Thirdly, the present invention provides an electronic device, comprising: one or more processors; and a memory for storing one or more programs; wherein, when the one or more programs are executed by the one or more processors, the one or more processors implement the aforementioned carrier recursive estimation method based on frequency dynamic partitioning.

[0072] Fourthly, the present invention provides a computer-readable storage medium having executable instructions stored thereon, which, when executed by a processor, enable the processor to implement the aforementioned carrier recursive estimation method based on frequency dynamic partitioning.

[0073] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A carrier recursive estimation method based on frequency dynamic partitioning, characterized in that, The method includes: Step 1: The transmitting end generates the original information sequence and modulates it to obtain the digital baseband signal; Step 2: The receiving end receives the digital baseband signal as a received information sequence and processes it to obtain a demodulated signal sequence; Step 3: For the demodulated signal sequence, perform frequency partitioning within the initial frequency offset range, calculate the period amplitude at the endpoints of each partition, and select the endpoints with the largest and second largest period amplitudes as the search range for the next recursive estimation; wherein, the period amplitude is the magnitude obtained by multiplying each symbol in the demodulated signal sequence with a complex exponential sequence at different frequency points and summing the results. Step 4: Dynamically update the current recursive frequency offset search interval and partition endpoints to gradually narrow the frequency offset estimation range; Step 5: After the recursion is completed, calculate the frequency offset estimate and phase offset estimate based on the partition endpoints corresponding to the final maximum period amplitude. Step 6: Perform carrier compensation on the received information sequence based on the frequency offset estimate and phase offset estimate.

2. The carrier recursive estimation method based on frequency dynamic partitioning according to claim 1, characterized in that, In step 1, the modulation method is multi-level phase shift keying modulation, and the modulation order is M.

3. The carrier recursive estimation method based on frequency dynamic partitioning according to claim 1, characterized in that, In step 2, the processing includes performing an M-th power operation on the received information sequence to eliminate modulation phase information.

4. The carrier recursive estimation method based on frequency dynamic partitioning according to claim 1, characterized in that, In step 4, the dynamic update of the search interval is achieved by using the endpoints of the largest and second largest period amplitudes obtained from the previous recursion as the new search boundaries.

5. The carrier recursive estimation method based on frequency dynamic partitioning according to claim 1, characterized in that, In step 5, the frequency offset estimate is obtained by directly using the partition endpoint frequency corresponding to the final recursive maximum period amplitude as the estimate, and the phase offset estimate is obtained by calculating the phase angle corresponding to the complex value of the final maximum period amplitude.

6. The carrier recursive estimation method based on frequency dynamic partitioning according to claim 1, characterized in that, In step 6, the carrier compensation is achieved by multiplying the received information sequence with a complex exponential signal, the frequency and phase of which are determined by the frequency offset estimate and the phase offset estimate, respectively.

7. A carrier recursive estimation device based on frequency dynamic partitioning, characterized in that, include: The modulation module is used by the transmitting end to generate the original information sequence and modulate it to obtain a digital baseband signal; The processing module is used to receive the digital baseband signal as a received information sequence at the receiving end, and process it to obtain a demodulated signal sequence; The calculation module is used to divide the frequency range of the demodulated signal sequence into frequency partitions, calculate the period amplitude of each partition endpoint, and select the endpoints with the largest and second largest period amplitudes as the search range for the next recursive estimation; wherein, the period amplitude is the magnitude obtained by multiplying each symbol in the demodulated signal sequence with a complex exponential sequence at different frequency points and summing the results. The update module is used to dynamically update the current recursive frequency offset search interval and partition endpoints, gradually narrowing the frequency offset estimation range; The estimation module is used to calculate the frequency offset estimate and phase offset estimate based on the partition endpoints corresponding to the final maximum period amplitude after the recursion is completed. The compensation module is used to perform carrier compensation on the received information sequence based on the frequency offset estimate and the phase offset estimate.

8. An electronic device, characterized in that, include: One or more processors; Memory, used to store one or more programs; When one or more programs are executed by the one or more processors, the one or more processors implement the carrier recursive estimation method based on frequency dynamic partitioning as described in any one of claims 1-6.

9. A computer-readable storage medium, characterized in that, It stores executable instructions that, when executed by a processor, enable the processor to implement the carrier recursive estimation method based on frequency dynamic partitioning as described in any one of claims 1-6.

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