Multi-bit spread spectrum signal carrier tracking method based on coherent dispreading judgment

Abstract

The invention discloses a multi-bit spread spectrum signal carrier tracking method based on coherent dispreading judgment, and relates to the technical field of satellite communication, and the method comprises the following steps: S01, carrying out the phase correction of an input signal, and generating a signal after phase correction; s02, inputting the signal after phase correction into a multi-path correlator for joint demodulation and despreading to obtain N paths of correlator outputs; s03, performing maximum value judgment on the real parts output by the N paths of correlators, and determining a judged spread spectrum symbol; and S04, extracting a residual phase error according to the output of the correlator corresponding to the judged spread spectrum symbol, feeding back the residual phase error to the step S01, and providing a next spread spectrum signal for phase correction. According to the method, the phase tracking problem of multi-bit spread spectrum under the low signal-to-noise ratio is solved, a coherent judgment algorithm with high performance can be adopted, and the method is more suitable for a high-dynamic satellite communication scene.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of satellite communication, in particular to a multi-bit spread spectrum signal carrier tracking method based on coherent despreading decision. BACKGROUND

[0002] In the field of satellite communication, there are usually challenges of long transmission delay and multipath fading. By using a sequence with good autocorrelation for spreading, the main path signal can be effectively captured at the receiving end, and the energy of the multipath component can be suppressed, so the spread spectrum technology is widely used in satellite communication, tactical data link and other fields. However, while improving the anti-multipath capability, the spread spectrum will reduce the information transmission rate. Therefore, on the basis of spread spectrum, the cyclic code shift keying (CCSK) carries information through the cyclic shift of the sequence, effectively improves the information rate, and the generated sequence is only a cyclic shift of the original sequence, so the cross-correlation performance and autocorrelation are consistent; moreover, the cyclic shift is simple to implement and has low hardware complexity, which is suitable for resource-limited scenarios such as satellite terminals, so the CCSK multi-bit spread spectrum has gradually become one of the core solutions of the physical layer of satellite communication.

[0003] However, in the process of satellite communication, the high-speed movement of the satellite will cause serious Doppler effect, and the instability of the crystal oscillator between the transceiver will cause the received signal to have obvious carrier frequency offset, which will cause the phase to rotate with time, thereby affecting the demodulation decision result, so it is necessary to recover the carrier of the received signal first. For spread spectrum signals, if the carrier tracking is directly performed on the modulated symbols without despreading, the tracking will often fail due to low signal-to-noise ratio, and the demodulation performance will also be greatly lost under low signal-to-noise ratio, so in practical applications, a joint demodulation and despreading scheme is usually used. However, for multi-bit spread spectrum, multiple correlators are needed at the receiving end, which cannot be directly transmitted. SUMMARY

[0004] In view of the above technical problems, the technical scheme adopted by the present application is a multi-bit spread spectrum signal carrier tracking method based on coherent despreading decision, which comprises the following steps:

[0005] S01, phase correction is performed on the input signal to generate a phase-corrected signal;

[0006] S02, the phase-corrected signal is input into a multi-path correlator for joint demodulation and despreading to obtain N-path correlator outputs;

[0007] S03, maximum value decision is performed on the real parts of the N-path correlator outputs to determine the decision spread spectrum symbol;

[0008] S04, the correlator output corresponding to the decision spread spectrum symbol is extracted and fed back to step S01 after the residual phase error is extracted for phase correction of the next spread spectrum signal.

[0009] As preferred, the input signal in the step S01 is: wherein, is a spread spectrum signal, is a received carrier phase error;

[0010] and the phase-corrected signal is .

[0011] As preferred, the N correlators output in the step S02 are: wherein, represents the nth correlator, is a local signal of the correlator;

[0012] As preferred, the number N of the multiple correlators is equal to the number of bits of the spread spectrum symbol, and the local spread spectrum signal of each correlator is a pre-set orthogonal spread spectrum code sequence.

[0013] As preferred, the maximum value decision in the step S03 is based on a coherent despreading mechanism, and the symbol decision is made by comparing the absolute values of the real parts of the correlator outputs.

[0014] As preferred, the decision spread spectrum symbol in the step S03 is wherein, represents the decision decimal spread spectrum symbol, and the binary spread spectrum bits are obtained by demapping the decision decimal spread spectrum symbol.

[0015] As preferred, the residual phase error in the step S04 is extracted by .

[0016] The present application has at least the following beneficial effects:

[0017] 1. By combining the demodulation and despreading mechanisms with the coherent decision mechanism, the signal phase information is fully utilized, the demodulation and despreading accuracy under low signal-to-noise ratio conditions is significantly improved, the bit error rate is reduced, and the performance loss problem caused by traditional non-coherent decision is solved.

[0018] 2. The real-time feedback mechanism of the residual phase error is used to form a closed-loop carrier tracking system, which can dynamically adjust the phase correction value, effectively suppress the residual frequency offset and phase drift, and enhance the adaptability of the system to time-varying channels, especially in mobile communication or multipath interference scenarios.

[0019] 3. The initial phase estimation is obtained by the pre-pilot signal, which shortens the system startup time, and the dynamic updating mechanism of the closed-loop feedback is combined to ensure the fast convergence and long-term stability of the phase estimation, thereby improving the overall efficiency of the system.

[0020] 4. The multi-correlator design using orthogonal spreading code sequences reduces the influence of inter-symbol interference and multipath interference, and combining with coherent despreading decision, further improves the accuracy of signal separation and the anti-noise performance of the system.

[0021] 5. The design of matching the multi-correlator with the number of spreading symbol bits optimizes the allocation of hardware resources, improves the parallel processing efficiency, supports the efficient implementation of multi-bit spreading system, and expands the adaptability of application scenarios. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0023] Figure 1 A flow chart of a multi-bit spread spectrum signal carrier tracking method based on coherent despreading decision is provided for the first embodiment of the present application.

[0024] Figure 2 A schematic diagram of a multi-bit spread spectrum independent demodulation and despreading receiver is provided for the first embodiment of the present application.

[0025] Figure 3 A schematic diagram of a multi-bit spread spectrum joint non-coherent demodulation and despreading receiver is provided for the first embodiment of the present application.

[0026] Figure 4 A schematic diagram of a multi-bit spread spectrum joint coherent demodulation and despreading receiver is provided for the first embodiment of the present application. DETAILED DESCRIPTION

[0027] The technical solutions in the embodiments of the present application will be described clearly and completely with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0028] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way are interchangeable where appropriate so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations are intended to cover non-exclusive inclusions. For example, a process, method, system, product or server that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0029] Example 1

[0030] This embodiment provides a multi-bit spread spectrum signal carrier tracking method based on coherent despreading judgment, the method comprising the following steps: Figure 1 As shown:

[0031] S01, performing phase correction on an input signal to generate a phase-corrected signal;

[0032] Specifically, such as Figure 2 As shown, the input signal is: ,in, is a spread spectrum signal, is the received carrier phase error. And the phase-corrected signal is .

[0033] As mentioned above, after the carrier phase error of the input signal is estimated, phase compensation is performed through complex multiplication to generate a phase-corrected signal. The initial value of the phase error is obtained by using the preamble. The preamble is a known training sequence.

[0034] S02, input the phase-corrected signal into the multi-channel correlator for joint demodulation and demultiplexing to obtain N-channel correlator output ;

[0035] Specifically, such as Figures 3-4 As shown, in step S02, the N-way correlator outputs ,in, , represents the nth correlator, is the local signal of the correlator. The number of multi-channel correlators N is equal to the number of bits of the spread spectrum symbol, and the local spread spectrum signal of each correlator is is a preset orthogonal spreading code sequence.

[0036] In the above, multiple correlators are used to jointly process the phase-corrected signal, and each correlator matches a local orthogonal spread spectrum code and outputs a correlation value.

[0037] S03, maximum value decision is made on the real part of the N-path correlator output to determine the decision spread symbol ;

[0038] As shown in the above, Figures 3-4 the maximum value decision in step S03 is based on a coherent despreading mechanism, and the symbol decision is made by comparing the absolute values of the real parts of the correlator outputs;

[0039] Secondly, the decision spread symbol in step S03, wherein, the decimal spread symbol is determined, and the binary spread bit is obtained by demapping.

[0040]

[0041] S04, according to the decision spread symbol corresponding correlator output , the residual phase error is extracted feedback to step S01 for the next spread signal for phase correction, and the above-mentioned extraction residual phase error The phase error of the decision result is fed back to the input to realize dynamic phase tracking and form a closed loop.

[0042] The first embodiment of the present application combines demodulation and coherent decision mechanism, fully utilizes the signal phase information, significantly improves the demodulation and despreading accuracy under low signal-to-noise ratio condition, reduces the bit error rate, and solves the performance loss problem caused by traditional non-coherent decision. And using the real-time feedback mechanism of residual phase error, a closed loop carrier tracking system is formed, which can dynamically adjust the phase correction value, effectively suppress the residual frequency offset and phase drift, enhance the adaptability of the system to time-varying channel, especially in mobile communication or multipath interference scene. Secondly, by using the front pilot signal to obtain the initial phase estimation, the system startup time is shortened, and combined with the dynamic updating mechanism of closed loop feedback, the phase estimation is ensured to converge quickly and keep long-term stability, which improves the overall efficiency of the system. Furthermore, the above-mentioned embodiment adopts the design of multiple correlators of orthogonal spread code sequence, which reduces the influence of code interference and multipath interference, and combined with coherent despreading decision, further improves the accuracy of signal separation and the anti-noise performance of the system. Through the design of matching multiple correlators and spread symbol bits, the hardware resource allocation is optimized, the parallel processing efficiency is improved, and the efficient implementation of multi-bit spread system is supported, which expands the adaptability of application scenarios.

[0043] Embodiment two

[0044] An embodiment of the present invention provides a non-transitory computer-readable storage medium, wherein the non-transitory computer-readable storage medium stores at least one instruction or at least one program, and the at least one instruction or at least one program is loaded and executed by a processor to implement the steps:

[0045] performing phase correction on an input signal to generate a phase-corrected signal;

[0046] The phase-corrected signal is input into the multi-channel correlator for joint demodulation and de-spreading to obtain the N-channel correlator output ;

[0047] Output of N-way correlator The real part of the maximum value is judged to determine the spread spectrum symbol of the decision ;

[0048] According to the decision spread spectrum symbol The corresponding correlator output , extract the residual phase error It is then fed back to the initial step for phase correction of the next spread spectrum signal.

[0049] Those skilled in the art will appreciate that all or part of the processes in the above-described method embodiments can be implemented by instructing the relevant hardware using a computer program. The computer program can be stored in a non-volatile computer-readable storage medium. When executed, the computer program can include the processes of the above-described method embodiments. Any reference to memory, storage, database, or other media used in the various embodiments provided herein may include non-volatile and / or volatile memory. Non-volatile memory may include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory may include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in various forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), RAMbus direct RAM (RDRAM), direct RAMbus dynamic RAM (DRDRAM), and RAMbus dynamic RAM (RDRAM).

[0050] Those skilled in the art will clearly understand that for the sake of convenience and brevity in description, only the division of the above-mentioned functional units and modules is used as an example. In actual applications, the above-mentioned functions can be distributed and completed by different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above.

[0051] Example 3

[0052] An embodiment of the present invention provides an electronic device, including a processor and a memory, wherein the memory stores at least one instruction or at least one program, and the at least one instruction or at least one program is loaded and executed by the processor to implement the following steps:

[0053] performing phase correction on an input signal to generate a phase-corrected signal;

[0054] The phase-corrected signal is input into the multi-channel correlator for joint demodulation and de-spreading to obtain the N-channel correlator output ;

[0055] Output of N-way correlator The real part of the maximum value is judged to determine the spread spectrum symbol of the decision ;

[0056] According to the decision spread spectrum symbol The corresponding correlator output , extract the residual phase error It is then fed back to the initial step for phase correction of the next spread spectrum signal.

[0057] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as a preferred embodiment as above, it is not intended to limit the present invention. Any technician familiar with the present profession can make some changes or modifications to equivalent embodiments of the technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A multi-bit spread spectrum signal carrier tracking method based on coherent despreading decision, characterized by, The method comprises the following steps: S01, phase correction is performed on an input signal to generate a phase-corrected signal; S02, the phase-corrected signal is input into a multi-path correlator for joint demodulation and despreading to obtain N-path correlator outputs; S03, maximum value decision is performed on real parts of the N-path correlator outputs to determine a decided spread spectrum symbol; S04, residual phase error is extracted from a correlator output corresponding to the decided spread spectrum symbol and fed back to step S01 for phase correction of a next spread spectrum signal.

2. The method of claim 1, wherein the method is characterized by: The input signal in the step S01 is: wherein, is a spread spectrum signal, is a received carrier phase error; And the phase-corrected signal is .

3. The method of claim 1, wherein the method further comprises: The step S02 in which the N-way correlator outputs wherein, denotes the nth correlator, is the local signal of the correlator.

4. The method of claim 1, wherein the method further comprises: The number N of the multiple correlators is equal to the number of bits of the spread spectrum symbol, and the local spread spectrum signal of each correlator is a pre-set orthogonal spread spectrum code sequence.

5. The method of claim 1, wherein the method further comprises: The maximum value decision in step S03 is based on a coherent despreading mechanism, and a sign decision is made by comparing absolute values of real parts of the correlator outputs.

6. The multi-bit spread spectrum signal carrier tracking method based on coherent despreading decision according to claim 1, characterized in that: The spread spectrum symbol decided in the step S03 wherein denotes the decided decimal spread spectrum symbol, which is de-mapped to binary spread spectrum bits.

7. The method of claim 1, wherein the method further comprises: determining a plurality of correlation values based on the plurality of correlation values and the plurality of decision values; and determining the plurality of decision values based on the plurality of correlation values. The step S04 extracts the residual phase error . 8.A non-transitory computer-readable storage medium having stored therein at least one instruction or at least one piece of program, characterized in that, The at least one instruction or the at least one program is loaded and executed by the processor to implement the steps of the multi-bit spread spectrum signal carrier tracking method based on coherent despreading decision according to any one of claims 1-7.

9. An electronic device, comprising: The processor and the memory are included, and the memory has at least one instruction or at least one program stored therein, and the at least one instruction or the at least one program is loaded and executed by the processor to implement the steps of the multi-bit spread spectrum signal carrier tracking method based on coherent despreading decision according to any one of claims 1-7.

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