CN-122027413-A - Satellite communication frequency offset direction judging method, storage medium and satellite communication terminal

CN122027413ACN 122027413 ACN122027413 ACN 122027413ACN-122027413-A

Abstract

The application relates to the technical field of satellite communication, in particular to a satellite communication frequency offset direction judging method, a storage medium and a satellite communication terminal, wherein the method comprises the steps of executing Turbo decoding on a received signal adopting an initial frequency offset compensation value; the method comprises the steps of synchronously monitoring to the Nth iteration in the decoding process and capturing a first path soft output metric, generating a frequency offset search trigger signal based on the captured first path soft output metric if CRC (cyclic redundancy check) fails, re-compensating a received signal by adopting a first frequency offset compensation value, capturing a second path soft output metric, calculating a soft output difference according to the second path soft output metric and the first path soft output metric, and judging a frequency offset direction based on the soft output difference. The application realizes event driving, process controllability and information inheritance of satellite communication terminal frequency offset search, thereby greatly reducing power consumption and shortening time delay.

Inventors

CHEN NING
YU TIANKUN

Assignees

素泰智能科技(上海)有限公司

Dates

Publication Date: 20260512
Application Date: 20260318

Claims (10)

1. The satellite communication frequency offset direction judging method is characterized by being applied to a satellite communication system and comprising the following steps of: Performing complete Turbo decoding on a received signal adopting an initial frequency offset compensation value f (0) , wherein the complete Turbo decoding is performed for M times of preset total iteration times, synchronously monitoring to the nth iteration in the decoding process and capturing a first path soft output metric lambda (0) ; Responding to the frequency offset searching trigger signal, re-compensating the received signal by adopting a first frequency offset compensation value f (1) , starting Turbo decoding and monitoring to capture a second path soft output metric lambda (1) when the Nth iteration is completed; and a direction judging step of calculating a soft output difference delta lambda according to the first path soft output metric and the second path soft output metric, and judging the frequency offset direction based on the soft output difference delta lambda.
2. The method as recited in claim 1, further comprising: And buffering an external information vector Wa (1) corresponding to the initial frequency offset compensation value, multiplexing the external information vector Wa (1) to start Turbo decoding when the received signal is compensated again in the compensation attempting step.
3. The method of claim 1, wherein the determining the direction of the frequency offset based on the soft output difference ΔΛ comprises: If DeltaΛ >0 and f (1) > f (0) , determining that the true frequency offset is in a higher frequency band, and generating a direction maintaining instruction; If DeltaΛ >0 and f (1) < f (0) , determining the search direction as a decreasing direction and generating a direction maintaining instruction; If the delta lambda is less than or equal to 0, the current frequency deviation try direction is judged to be wrong.
4. The method of claim 2, wherein the direction reversal instruction is generated when the current frequency offset direction error is determined; Responding to the direction reversal instruction, forcibly terminating the current Turbo decoding process, and discarding the decoding result; Adjusting a frequency offset compensation value to a second frequency offset compensation value f (2) according to the direction reversal instruction, multiplexing at least part of the external information vector Wa (1) , and starting a new decoding round, wherein f (2) = f (0) -delta; And controlling the forced termination response time within a preset clock period, directly resetting a component decoder state machine of the Turbo decoder through a hard interrupt signal, resetting an iteration counter and closing a branch metric calculation unit, wherein the forced termination operation is executed in parallel with the external information vector multiplexing operation.
5. The method of claim 4, wherein the step of determining the position of the first electrode is performed, The multiplexing coefficient λ of the extrinsic information vector Wa (1) is determined by an absolute value |f (1) -f (0) | of a difference between the second frequency offset compensation value and the initial frequency offset compensation value, satisfying λ=max (0, 1- |f (2) - f (0) |/δ_max), where δ_max is an allowable maximum frequency offset adjustment boundary.
6. The method of claim 1, wherein the initial frequency offset compensation value f (0) is a residual frequency offset estimate of a preceding carrier tracking loop output in the satellite communication system , The residual frequency offset estimation value meets the constraint condition of the absolute value of normalized frequency offset |DeltafT| <0.01, wherein T is a symbol period, and Deltaf=f real - F real is the true frequency offset value of the received signal; The value of the preset step delta is more than or equal to 1/(4 KT) and less than or equal to 1/KT, wherein K is the burst frame length, T is the symbol period, and N is 5.
7. The method of claim 1 wherein each captured path soft output metric Λ (m) is extracted from a cumulative path metric register at the completion of the nth iteration of the Turbo decoder when the extrinsic information i_e has entered the linear growth area and is not saturated, the path soft output metric Λ (m) being calculated as: , Where K is the burst frame length, α and β are the forward and backward recursion metrics, γ is the branch metric, and s is the state of the recursive convolutional encoder in the component decoder of the Turbo decoder.
8. The method of claim 1, further comprising a step-size adaptive adjustment step: At ΔΛ >0 and soft output difference of two consecutive attempts |ΔΛ|/Λ (1) <0.05, the subsequent step is shrunk as follows: , Wherein μ is an attenuation coefficient, the value range is 0.5-1.0, k is an index of the number of attempts, and when k=1, the compensation attempt step is represented; After the direction is determined to be correct, continuously generating a subsequent frequency offset compensation value f (k+1) =f (k) -/+δ k along the correct direction by a preset step delta or an adaptive step delta k , and repeatedly executing the steps of compensation, turbo decoding, CRC (cyclic redundancy check) and step length adaptive adjustment in sequence until any one of the following termination conditions appears: the current attempt CRC check passes; The soft output difference of two consecutive attempts, |Λ (k+1) -Λ (k) |/Λ (k) < epsilon, and the step delta k < delta_min, |epsilon, is a preset value; the number of attempts K reaches a preset maximum number of attempts k_max; the current frequency offset compensation value exceeds the allowable maximum frequency offset boundary |f (k) - |>Δf_max; If all attempts fail the CRC check, declaring the decoding failure of the current burst frame and discarding the current burst frame, and no subsequent processing is performed.
9. A satellite communication terminal, comprising: At least one processor; And a memory communicatively coupled to the at least one processor; Wherein the memory has stored therein a computer program which, when executed by the at least one processor, implements the satellite communication frequency offset estimation and synchronization method of any one of claims 1 to 8.
10. A computer readable storage medium having stored therein a plurality of program codes, wherein the program codes are adapted to be loaded and executed by a processor to perform the satellite communication frequency offset estimation and synchronization method of any one of claims 1 to 8.

Description

Satellite communication frequency offset direction judging method, storage medium and satellite communication terminal Technical Field The application relates to the technical field of satellite communication, in particular to a satellite communication frequency offset direction judging method, a storage medium and a satellite communication terminal. Background The existing satellite communication frequency offset estimation technology has three core pain points in practical application, and the pain points severely restrict the energy efficiency ratio and response speed of the satellite Internet of things terminal: First, blind searching results in inefficient energy consumption. The traditional technology adopts a periodic forced search strategy no matter the quality of the channel. For example, in a satellite internet of things terminal, the channel condition is good for more than 70% of working time, no frequency offset adjustment is needed, but the traditional method still executes a complete search flow according to the office, so that a large amount of invalid calculation is caused. The policy of 'one-cut' increases the overall power consumption of the terminal by more than 50%, and seriously affects the endurance of battery-powered equipment. Second, the decoding black box causes resource waste. The conventional method regards the Turbo decoder as a black box which cannot be observed, and the frequency offset adjustment effect can be evaluated after the Turbo decoder has to wait for all iterative calculations (usually 8 to 12 times) to be completed and a final hard decision result to be obtained. When the actual frequency offset direction is opposite to the attempt direction, the whole decoding process is completely wasted, the energy consumption wasted by a single error attempt exceeds 60%, and the consumed time cannot be recovered, so that the communication delay is obviously increased. Third, empirical zero clearing compromises convergence speed. After each frequency offset adjustment, the conventional method completely resets the decoder state, and the valid soft information (external information) accumulated in the previous attempt is discarded. This is like forgetting the obtained clues after each failure in solving the puzzle, and the reasoning must be restarted from zero, resulting in repeated labor and resource waste. This "forget" mechanism slows the re-decoding convergence and the search inefficiency. Disclosure of Invention The application is proposed to solve or at least partially solve the technical problems of energy consumption inefficiency caused by searching and resource waste caused by decoding black boxes. According to one aspect of the present invention, there is provided a satellite communication frequency offset direction determining method, which is applied to a satellite communication system, and may include the steps of: Performing complete Turbo decoding on a received signal adopting an initial frequency offset compensation value f (0), wherein the complete Turbo decoding is performed for M times of preset total iteration times, synchronously monitoring to the Nth iteration in the decoding process and capturing a first path soft output metric; Responding to the frequency offset searching trigger signal, re-compensating the received signal by adopting a first frequency offset compensation value f (1), starting Turbo decoding and monitoring to capture a second path soft output metric lambda (1) when the Nth iteration is completed; and a direction judging step of calculating a soft output difference delta lambda according to the first path soft output metric and the second path soft output metric, and judging the frequency offset direction based on the soft output difference delta lambda. In the above technical solution, the method for determining a satellite communication frequency offset direction may further include: And buffering an external information vector Wa (1) corresponding to the initial frequency offset compensation value, multiplexing the external information vector Wa (1) to start Turbo decoding when the received signal is compensated again in the compensation attempting step. In any of the above solutions, the determining the frequency offset direction based on the soft output difference ΔΛ includes: If DeltaΛ >0 and f (1) > f(0), determining that the true frequency offset is in a higher frequency band, and generating a direction maintaining instruction; If DeltaΛ >0 and f (1) < f(0), determining the search direction as a decreasing direction and generating a direction maintaining instruction; If the delta lambda is less than or equal to 0, the current frequency deviation try direction is judged to be wrong. In any of the above technical solutions, when determining that the current frequency offset direction is wrong, generating a direction reversal instruction; Responding to the direction reversal instruction, forcibly terminating the current Turbo decoding p