CN-121984820-A - Sampling frequency offset compensation method, processor, system and storage medium

CN121984820ACN 121984820 ACN121984820 ACN 121984820ACN-121984820-A

Abstract

The application relates to the technical field of information and communication, in particular to a sampling frequency offset compensation method, a processor, a system and a storage medium, which comprise the steps of acquiring a plurality of OFDM symbols in real time; the method comprises the steps of determining a sampling frequency offset estimation value based on a plurality of pilot frequency subcarriers in each OFDM symbol, normalizing the sampling frequency offset estimation value to a first phase rotation correction amount corresponding to a unit OFDM symbol period, calculating a second phase rotation correction amount corresponding to a current symbol period when an mth OFDM symbol period arrives, superposing the second phase rotation correction amount to a corresponding balanced phase factor, generating a total phase rotation correction factor for a single subcarrier in m OFDM symbol periods, and carrying out reverse phase rotation on a target subcarrier frequency domain signal based on the total phase rotation correction factor. The application realizes effective compensation of sampling frequency deviation between communication nodes by enabling the compensation quantity of the receiving end of the OFDM system to be precisely matched with the actual frequency deviation accumulation quantity experienced by the receiving end.

Inventors

HUANG JIANXIONG
WANG JIANFENG
LI HAISONG
YANG JING
GAO LIJUN
WANG BIN

Assignees

西安微电子技术研究所

Dates

Publication Date: 20260505
Application Date: 20260130

Claims (10)

1. The sampling frequency offset compensation method is applied to a receiving end of an OFDM system and is characterized by comprising the following steps: acquiring a plurality of OFDM symbols in real time; determining a sampling frequency offset estimation value based on a plurality of pilot frequency subcarriers in each OFDM symbol; Normalizing the sampling frequency offset estimation value into a first phase rotation correction amount corresponding to a unit OFDM symbol period, and calculating a second phase rotation correction amount corresponding to a current symbol period based on the first phase rotation correction amount when an mth OFDM symbol period arrives, so as to superimpose the second phase rotation correction amount into a corresponding balanced phase factor, and generating a total phase rotation correction factor in m OFDM symbol periods for a single subcarrier; and performing reverse phase rotation on the target subcarrier frequency domain signal based on the total phase rotation correction factor.
2. The method of sampling frequency offset compensation according to claim 1, wherein said determining a sampling frequency offset estimate based on a plurality of active subcarriers within each of said OFDM symbols comprises: performing FFT (fast Fourier transform) on each OFDM symbol, and performing OFDM pilot frequency processing to obtain pilot frequency data and pilot frequency control information, wherein the pilot frequency data at least comprises first pilot frequency data corresponding to a first pilot frequency subcarrier and second pilot frequency data corresponding to a second pilot frequency subcarrier; Sampling frequency offset estimation is carried out based on the pilot frequency data and the pilot frequency control information, and sampling frequency offset estimation values based on the first pilot frequency sub-carrier and the second pilot frequency sub-carrier are obtained; And summing the sampling frequency deviation estimation values of the pilot frequency subcarriers to obtain an average value, and obtaining the sampling frequency deviation estimation value.
3. The method for compensating for sampling frequency offset according to claim 2, wherein said performing sampling frequency offset estimation based on said pilot data and said pilot control information to obtain a sampling frequency offset estimation value based on said first pilot subcarrier and said second pilot subcarrier comprises: Constructing pilot frequency comparison data pairs of the same pilot frequency subcarrier in two adjacent OFDM symbols through delay operation, wherein the pilot frequency comparison data pairs comprise current symbol pilot frequency data and delayed pilot frequency data, and the two adjacent OFDM symbols are a kth OFDM symbol and a (k+1) th OFDM symbol; Conjugation is carried out on the delayed pilot frequency data to obtain conjugated data, and after the conjugated data is multiplied with the current symbol pilot frequency data, sampling frequency deviation estimated values based on the first pilot frequency sub-carrier and the second pilot frequency sub-carrier in a single symbol period are obtained through inverse tangent operation; the method comprises the following steps: formula I; A second formula; formula III; Formula IV; a fifth formula; A formula six; In the formula, For the first pilot sub-carrier In the first place Pilot data of one OFDM symbol, For the first pilot sub-carrier Pilot data at the k+1th OFDM symbol; as a transfer function related to the channel transmission characteristics, Is the first The number of carrier symbols is one, Is the first Carrier symbols; For the first pilot sub-carrier In the first place Pilot data of one OFDM symbol, For the first pilot sub-carrier In the first place Pilot data of the individual OFDM symbols; Is the first The phase of the individual pilots is chosen so that, Is the first The phases of the individual pilots; Is that Is used for the conjugation of (a), Is that Conjugation of (2); In order for the time-to-time deviation to be present, For the time interval between the first pilot subcarrier and the second pilot subcarrier, A sampling frequency deviation estimated value; the sampling frequency deviation estimation values of the pilot frequency subcarriers are summed and averaged to obtain the sampling frequency deviation estimation value The method specifically comprises the following steps: ; In the formula, Indicating the number of pilot sub-carriers, And the frequency offset estimation value is sampled.
4. The method of sampling frequency offset compensation according to claim 1, wherein prior to acquiring a plurality of OFDM symbols in real time, the method further comprises: receiving OFDM time domain signal flow in real time; And separating and obtaining a plurality of continuous time domain aligned OFDM symbols from the OFDM time domain signal.
5. The method of sampling frequency offset compensation according to claim 3, wherein normalizing the sampling frequency offset estimation value to a first phase rotation correction amount corresponding to a unit OFDM symbol period comprises: Converting the sampling frequency offset estimation value into a first phase rotation correction amount adapted to each pilot frequency subcarrier, specifically: ; In the formula, A first phase rotation correction amount; The frequency offset estimation value is sampled; for OFDM symbol periods, i.e. ; Is a subcarrier sequence number; The calculating, when the mth OFDM symbol period arrives, a second phase rotation correction amount corresponding to the current symbol period based on the first phase rotation correction amount includes: when the mth OFDM symbol arrives, determining that the sequence number is based on the subcarrier sequence number of the mth OFDM symbol The second phase rotation correction amount after the subcarriers of m OFDM symbol periods is specifically: ; In the formula, For the second phase rotation correction amount, For the sequence number of the current symbol period, For the first phase rotation correction amount.
6. The method of sampling frequency offset compensation according to claim 1, wherein the method further comprises: In the digital logic design stage of the OFDM system, calculating clock frequency deviation of a crystal oscillator, and determining an upper limit of crystal oscillator stability meeting the sampling precision requirement of the OFDM system based on the clock frequency deviation after frequency multiplication; And finishing crystal oscillator type selection based on the upper limit of the crystal oscillator stability.
7. The method of sampling frequency offset compensation according to claim 6, further comprising evaluating a longest data frame length that can be transmitted by the OFDM system during a digital logic design phase of the OFDM system.
8. A processor configured to perform the sampling frequency offset compensation method of any one of claims 1-7.
9. An OFDM system, the system comprising: A channel; the transmitting end is used for transmitting an originating signal through the channel; The method comprises the steps of receiving an initial signal, acquiring a plurality of OFDM symbols based on the initial signal in real time, determining a sampling frequency offset estimation value based on a plurality of pilot subcarriers in each OFDM symbol, normalizing the sampling frequency offset estimation value to a first phase rotation correction amount corresponding to a unit OFDM symbol period, calculating a second phase rotation correction amount corresponding to a current symbol period based on the first phase rotation correction amount when an mth OFDM symbol period arrives, so as to add the second phase rotation correction amount to the corresponding equalization phase factor, generating a total phase rotation correction factor for a single subcarrier in m OFDM symbol periods, and carrying out reverse phase rotation on a target subcarrier frequency domain signal based on the total phase rotation correction factor, and the processor according to claim 8.
10. A computer readable storage medium having stored thereon a computer program, which when executed by a processor implements the steps of the sampling frequency offset compensation method of any of claims 1 to 7.

Description

Sampling frequency offset compensation method, processor, system and storage medium Technical Field The present application relates to the field of information and communication technologies, and in particular, to a sampling frequency offset compensation method, a processor, a system, and a storage medium. Background In a communication system typified by power line carrier communication and a hundred mega1553 bus, modulation and demodulation of baseband signals generally employ an orthogonal frequency division multiplexing OFDM technology. In order to exert the advantages of OFDM technology, to ensure reliable modulation and demodulation of OFDM symbols, it is necessary to maintain the orthogonality of OFDM symbols, and avoid the influence of inter-symbol interference ISI and inter-subcarrier interference ICI on demodulation accuracy caused by the damage of the orthogonality. In the prior art, in order to improve the accuracy of OFDM symbol receiving detection, a synchronization head is added at the front end of an OFDM symbol to ensure that a receiving end can accurately judge that an effective OFDM symbol is received when receiving signal detection is carried out, and accurately identify the starting time of OFDM effective data transmission, thereby avoiding influence on FFT processing caused by symbol desynchronization. However, ISI and ICI problems and spectrum leakage problems caused by sampling frequency deviations still remain. Particularly, in the receiving and detecting process of connecting a plurality of OFDM symbols, the reliability of the receiving and detecting of the continuous plurality of OFDM symbols is more easily affected by the sampling frequency deviation due to the accumulated effect of the sampling frequency deviation. Disclosure of Invention In order to solve the above problems, the application provides a sampling frequency offset compensation method, a processor, a system and a storage medium, which can effectively reduce message transmission error rate caused by sampling frequency deviation in the process of carrying out message communication with different lengths between different nodes by enabling the compensation quantity of a receiving end of an OFDM system to be precisely matched with the actual frequency offset accumulation quantity of the receiving end of the OFDM system, thereby realizing effective compensation of the sampling frequency deviation between communication nodes. In order to achieve the purpose of the application, the application provides the following technical scheme: in a first aspect, the present application provides a sampling frequency offset compensation method, applied to a receiving end of an OFDM system, including: acquiring a plurality of OFDM symbols in real time; determining a sampling frequency offset estimation value based on a plurality of pilot frequency subcarriers in each OFDM symbol; Normalizing the sampling frequency offset estimation value into a first phase rotation correction amount corresponding to a unit OFDM symbol period, and calculating a second phase rotation correction amount corresponding to a current symbol period based on the first phase rotation correction amount when an mth OFDM symbol period arrives, so as to superimpose the second phase rotation correction amount into a corresponding balanced phase factor, and generating a total phase rotation correction factor in m OFDM symbol periods for a single subcarrier; and performing reverse phase rotation on the target subcarrier frequency domain signal based on the total phase rotation correction factor. The invention further improves the method, which comprises the steps of determining sampling frequency offset estimation values based on a plurality of effective subcarriers in each OFDM symbol, carrying out FFT conversion on each OFDM symbol, carrying out OFDM pilot frequency processing to obtain pilot frequency data and pilot frequency control information, wherein the pilot frequency data at least comprises first pilot frequency data corresponding to a first pilot frequency subcarrier and second pilot frequency data corresponding to a second pilot frequency subcarrier, carrying out sampling frequency offset estimation based on the pilot frequency data and the pilot frequency control information to obtain sampling frequency offset estimation values based on the first pilot frequency subcarrier and the second pilot frequency subcarrier, and summing and averaging the sampling frequency offset estimation values of the plurality of pilot frequency subcarriers to obtain the sampling frequency offset estimation values. The invention further improves that the sampling frequency offset estimation is carried out based on the pilot frequency data and the pilot frequency control information to obtain the sampling frequency deviation estimation value based on the first pilot frequency subcarrier and the second pilot frequency subcarrier, which comprises the steps of constructing pilot frequ