Spread spectrum communication system and method based on orthogonal pilots

Abstract

This disclosure provides a spread spectrum communication system and method based on orthogonal pilots, comprising: a transmitter for spreading the spectrum using a first pseudo-random spreading code sequence and a fixed pilot sequence to obtain pilot branch signals and pilot pseudo-code phase information; spreading the spectrum using a second pseudo-random spreading code sequence and the original data sequence to obtain a data branch signal; orthogonally combining the pilot branch signals and the data branch signals to obtain a baseband signal; and a receiver for processing the baseband signal using a third pseudo-random spreading code sequence and a local carrier to obtain carrier frequency phase information and synchronization pseudo-code phase information; determining a demodulation carrier based on the carrier frequency phase information; demodulating the baseband signal using the demodulation carrier to obtain a demodulated data signal; performing phase adjustment on a fourth pseudo-random spreading code sequence based on the synchronization pseudo-code phase information; and despreading the demodulated data signal based on the phase adjustment result to obtain a target data sequence. This improves the efficiency of spread spectrum communication.

Description

Technical Field

[0001] The embodiments of this disclosure relate to the field of satellite communication technology, and more specifically, to a spread spectrum communication system and method applicable to orthogonal pilot-based systems. Background Technology

[0002] Spread spectrum communication, with its excellent anti-interference capability, long-distance transmission performance, and multiple access characteristics, is widely used in multi-user communication modes of relay satellite systems. With the diversification of user services, communication requirements are evolving from fixed rates to multi-level variable rates, posing serious challenges to the system's acquisition sensitivity, synchronization stability, and rate adaptive capability.

[0003] In existing technologies, traditional spread spectrum communication systems mainly employ incoherent acquisition and tracking techniques. Their acquisition and tracking performance is limited by the signal-to-noise ratio and symbol rate, and their performance deteriorates sharply under low-speed, weak signal conditions. More importantly, existing systems lack a continuous and stable reference standard, making it difficult to maintain reliable synchronization during rate switching. This restricts their application in advanced variable-rate scenarios, resulting in low efficiency in spread spectrum communication. Summary of the Invention

[0004] The embodiments described herein provide a spread spectrum communication system and method based on orthogonal pilots that overcomes the aforementioned problems.

[0005] In a first aspect, according to the present disclosure, a spread spectrum communication system based on orthogonal pilots is provided, comprising: a transmitter and a receiver; The transmitting end is used to spread the spectrum using a generated first pseudo-random spreading code sequence and a locally generated fixed pilot sequence to obtain pilot branch signals and pilot pseudo-code phase information; after performing code transformation on the user-input original data sequence, it spreads the original data sequence using a generated second pseudo-random spreading code sequence to obtain a data branch signal; it synchronizes the phase of the data branch signal according to the pilot pseudo-code phase information to ensure that the data branch signal and the pilot branch signal are in the same phase; it modulates the pilot branch signal in the pilot branch and the data branch signal in the data branch, and performs orthogonal combining of the pilot branch signal and the data branch signal to obtain a baseband signal; and it transmits the baseband signal to the receiving end through a radio frequency channel. The receiving end is configured to acquire and track the baseband signal using the generated third pseudo-random spreading code sequence and a local carrier, to obtain carrier frequency phase information and synchronization pseudo-code phase information synchronized with the pilot branch of the baseband signal; determine the demodulation carrier synchronized with the data branch of the baseband signal based on the carrier frequency phase information; demodulate the baseband signal using the demodulation carrier to obtain a demodulated data signal; perform phase adjustment on the generated fourth pseudo-random spreading code sequence based on the synchronization pseudo-code phase information, and despread the demodulated data signal based on the phase adjustment result to obtain a target data sequence.

[0006] Secondly, according to the content of this disclosure, a spread spectrum communication method based on orthogonal pilots is provided, comprising: The transmitting end performs spread spectrum using a generated first pseudo-random spreading code sequence and a locally generated fixed pilot sequence to obtain pilot branch signals and pilot pseudo-code phase information. After performing code transformation on the user-input original data sequence, it spreads the original data sequence using a generated second pseudo-random spreading code sequence to obtain data branch signals. The data branch signals are then phase-synchronized according to the pilot pseudo-code phase information to ensure they are in the same phase as the pilot branch signals. The pilot branch signals are modulated in the pilot branch, and the data branch signals are modulated in the data branch. The pilot branch signals and the data branch signals are then orthogonally combined to obtain a baseband signal. This baseband signal is then transmitted to the receiving end through a radio frequency channel. The receiving end uses the generated third pseudo-random spreading code sequence and the local carrier to acquire and track the baseband signal, obtaining carrier frequency phase information and synchronization pseudo-code phase information synchronized with the pilot branch of the baseband signal; based on the carrier frequency phase information, it determines the demodulation carrier synchronized with the data branch of the baseband signal; it demodulates the baseband signal using the demodulation carrier to obtain the demodulated data signal; it performs phase adjustment on the generated fourth pseudo-random spreading code sequence based on the synchronization pseudo-code phase information, and despreads the demodulated data signal based on the phase adjustment result to obtain the target data sequence.

[0007] The spread spectrum communication system based on orthogonal pilots provided in this application includes: a transmitter and a receiver; the transmitter is used to spread the spectrum using a generated first pseudo-random spreading code sequence and a locally generated fixed pilot sequence to obtain pilot branch signals and pilot pseudo-code phase information; after performing code transformation on the user-input original data sequence, it spreads the spectrum using a generated second pseudo-random spreading code sequence and the original data sequence to obtain a data branch signal; it performs phase synchronization of the data branch signal according to the pilot pseudo-code phase information to ensure that the data branch signal and the pilot branch signal are in the same phase; it performs modulation processing on the pilot branch signal and on the data branch signal, and also performs modulation processing on the pilot branch signal. The baseband signal is obtained by orthogonally combining the pilot and data branch signals. This baseband signal is then transmitted to the receiver via a radio frequency channel. At the receiver, the generated third pseudo-random spreading code sequence and the local carrier are used to acquire and track the baseband signal, obtaining carrier frequency phase information and synchronization pseudo-code phase information synchronized with the pilot branch of the baseband signal. Based on the carrier frequency phase information, the demodulation carrier synchronized with the data branch of the baseband signal is determined. The baseband signal is demodulated using the demodulation carrier to obtain the demodulated data signal. The phase of the generated fourth pseudo-random spreading code sequence is adjusted based on the synchronization pseudo-code phase information, and the demodulated data signal is despread based on the phase adjustment result to obtain the target data sequence. Thus, through parallel processing of the pilot and data branches, pilot information can be accurately extracted at the receiver to achieve carrier synchronization and pseudo-code synchronization. This effectively improves the anti-interference capability and data transmission accuracy of the spread spectrum communication system in complex channel environments, ensuring that the target data sequence can be accurately recovered, and greatly improving the efficiency of spread spectrum communication.

[0008] The above description is merely an overview of the technical solutions of the embodiments of this application. In order to better understand the technical means of the embodiments of this application and to implement them in accordance with the contents of the specification, and to make the above and other objects, features and advantages of the embodiments of this application more obvious and understandable, specific implementation methods of this application are described below. Attached Figure Description

[0009] To more clearly illustrate the technical solutions of the embodiments of this disclosure, the accompanying drawings of the embodiments will be briefly described below. It should be understood that the drawings described below only relate to some embodiments of this disclosure and are not intended to limit this disclosure, wherein: Figure 1 This is a schematic diagram of a spread spectrum communication system based on orthogonal pilots provided in this disclosure.

[0010] Figure 2 This is a schematic diagram of another spread spectrum communication system based on orthogonal pilots provided in this disclosure.

[0011] Figure 3This is a schematic diagram of a generator structure for a 10th-order GOLD code provided in this disclosure.

[0012] Figure 4 This is a flowchart illustrating a spread spectrum communication method based on orthogonal pilots provided in this disclosure.

[0013] It should be noted that the elements in the attached diagram are schematic and not drawn to scale. Detailed Implementation

[0014] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this disclosure. All other embodiments obtained by those skilled in the art based on the described embodiments of this disclosure without creative effort are also within the scope of protection of this disclosure.

[0015] Unless otherwise defined, 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 subject matter pertains. It will be further understood that terms such as those defined in commonly used dictionaries shall be interpreted as having the meaning consistent with their meaning in the context of the specification and in the relevant art, and shall not be interpreted in an idealized or overly formal form unless otherwise explicitly defined herein. As used herein, the statement of “connecting” or “coupling” two or more parts together shall mean that these parts are directly joined together or joined through one or more intermediate components.

[0016] The term "embodiment" as used herein means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of the phrase "embodiment" in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0017] In this document, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can mean: A exists, A and B exist simultaneously, or B exists. Additionally, the character " / " generally indicates that the preceding and following related objects have an "or" relationship. Terms such as "first" and "second" are only used to distinguish one component (or part of a component) from another component (or another part of a component).

[0018] In the description of this application, unless otherwise stated, "multiple" means two or more (including two), and similarly, "multiple groups" means two or more (including two groups).

[0019] This invention, based on the traditional orthogonal QPSK (Quadrature Phase Shift Keying) structure, introduces an independent pilot branch orthogonal to the data signal, constructing a highly reliable coherent reference channel and effectively improving the system's acquisition and tracking performance under low signal-to-noise ratio conditions. Simultaneously, the continuous existence of the pilot branch provides a stable phase and frequency reference for the system, ensuring a continuous and reliable link in multi-rate communication. Furthermore, both the transmitting and receiving ends can formulate a pilot-driven closed-loop rate control mechanism based on the link status measurement results of the pilot branch, achieving adaptive adjustment of the communication rate and effectively improving the system's spectrum resource utilization.

[0020] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings.

[0021] Figure 1 This is a schematic diagram of a spread spectrum communication system based on orthogonal pilots provided in an embodiment of this disclosure, as shown below. Figure 1 As shown, the low-orbit satellite data communication system includes: a transmitter 110 and a receiver 120.

[0022] Transmitter 110 is used to spread the spectrum using a generated first pseudo-random spreading code sequence and a locally generated fixed pilot sequence to obtain pilot branch signals and pilot pseudo-code phase information; after performing code transformation on the user-input original data sequence, it spreads the spectrum using a generated second pseudo-random spreading code sequence and the original data sequence to obtain data branch signals; it synchronizes the phase of the data branch signals according to the pilot pseudo-code phase information to ensure that the data branch signals and pilot branch signals are in the same phase; it modulates the pilot branch signals in the pilot branch and the data branch signals in the data branch, and performs orthogonal combining of the pilot branch signals and the data branch signals to obtain baseband signals; and it transmits the baseband signals to receiver 120 through the radio frequency channel.

[0023] like Figure 2 As shown, the transmitter 110 includes: a first pseudo-code generation module 1101, a pilot generation module 1102, a data generation and spread spectrum module 1103, and a data modulation module 1104.

[0024] The first pseudo-random code generation module 1101 is used to generate a first pseudo-random spreading code sequence and a second pseudo-random spreading code sequence, and send the first pseudo-random spreading code sequence to the spreading generation module 1102 and the second pseudo-random spreading code sequence to the data generation and spreading module 1103.

[0025] The first pseudo-random spreading code sequence is provided to the pilot generation module 1102 for spreading the pilot signal; the second pseudo-random spreading code sequence is provided to the data generation and spreading module 1103 for spreading the data signal. The pseudo-code type can be GOLD code. Figure 3 This is a schematic diagram of a generator for a 10th-order GOLD code, which produces a pseudocode sequence of length 1023.

[0026] The pilot generation module 1102 is used to spread the spectrum according to the first pseudo-random spreading code sequence and the locally generated fixed pilot sequence to obtain the pilot branch signal and the pilot pseudo-code phase information; and to send the pilot pseudo-code phase information to the data generation and spreading module 1103, and to send the pilot branch signal to the data modulation module 1104.

[0027] The pilot branch signal is the pilot signal obtained by spreading the locally generated fixed pilot sequence. The locally generated fixed pilot data can usually be set to "constant 1" or "constant 0". The pilot pseudocode phase information must correspond to the pseudocode code length, which corresponds to the code length of 1023 in the example mentioned above. The range of the pilot pseudocode phase information is 1~1023. The spread pilot signal rate can be 3.069Mbps, 9.6Mbps, etc.

[0028] The data generation and spreading module 1103 is used to perform code transformation on the original data sequence input by the user, spread the original data sequence and the second pseudo-random spreading code sequence to obtain the data branch signal; synchronize the phase of the data branch signal according to the pilot pseudo-code phase information so that the data branch signal and the pilot branch signal are in the same phase; and send the data branch signal to the data modulation module 1104.

[0029] This can be achieved by transforming the original data sequence input by the user, then performing channel coding, and finally spreading the spectrum based on the original data sequence and the second pseudo-random spreading code sequence.

[0030] The data sequence rate can range from 200 bps to 256 Kbps. Code transformations can include NRZ-L, NRZ-M, NRZ-S, etc. Channel coding includes convolutional coding, LDPC coding, etc., with a coding rate typically of 1 / 2. The spread spectrum data signal rate should be consistent with the spread spectrum pilot signal rate, and can be 3.069 Mbps, 9.6 Mbps, etc.

[0031] The data modulation module 1104 is used to modulate the pilot branch signal in the pilot branch, modulate the data branch signal in the data branch, and perform orthogonal combining of the pilot branch signal and the data branch signal to obtain the baseband signal; and transmit the baseband signal to the receiver 120 through the radio frequency channel.

[0032] In some embodiments, the data modulation module 1104 is specifically used to: allocate different powers to the intermediate frequency carrier signal generated by the transmitting local oscillator through a power divider to obtain a pilot adjustment signal and a data modulation signal; modulate the pilot branch signal according to the pilot adjustment signal; and after shifting the data modulation signal through a phase shifter, modulate the data branch signal according to the data modulation signal.

[0033] In some embodiments, the data modulation module 1104 is specifically used to: use the pilot branch signal as an in-phase component and the data branch signal as a quadrature component; or, use the data branch signal as an in-phase component and the pilot branch signal as a quadrature component; and use a quadrature combiner to vector synthesize the in-phase component and the quadrature component according to the amplitude and phase information corresponding to the in-phase component and the amplitude and phase information corresponding to the quadrature component to obtain the baseband signal.

[0034] The system employs QPSK modulation to receive the spread-spectrum pilot branch signal and pilot data signal, respectively, and modulates them in the pilot and data branches. After orthogonal combining, the baseband signal is output. The intermediate frequency (IF) carrier signals used for both signals originate from the same source, generated by the transmit local oscillator through an IF carrier generation module. Different powers are then allocated by a power divider. One signal is directly output and modulated with the spread-spectrum pilot sequence, while the other signal undergoes a 90° phase shift via a 90° phase shifter before being output and modulated with the spread-spectrum data sequence.

[0035] The modulator may include a shaping filter stage, which may employ a square root raised cosine roll-off filter. The pilot branch is a QPSK modulated I branch, and the data branch is a QPSK modulated Q branch; or, the data branch is a QPSK modulated I branch, and the pilot branch is a QPSK modulated Q branch.

[0036] The local oscillator frequency can be 10MHz, etc. An intermediate frequency (IF) carrier signal can be generated based on the IF frequency through frequency multiplication, mixing, etc., and the IF carrier frequency can be 70MHz, 1200MHz, etc. The power divider can allocate the power ratio between the pilot branch and the data branch at a fixed ratio, for example, 1:9, preferably with the pilot branch power accounting for no more than 15%.

[0037] A 90° phase shifter can perform a 90° phase shift on the carrier signal, making its output carrier signal orthogonal to the carrier signal, that is, orthogonal to the IQ branch of QPSK. A quadrature combiner can superimpose and combine mutually orthogonal pilot branch signals and data branch signals before outputting the result.

[0038] This enables the pilot branch and the data branch to achieve orthogonal transmission within the same carrier frequency band, avoiding the competition for spectrum resources between traditional pilots and data, and effectively improving spectrum utilization.

[0039] The receiver 120 is used to acquire and track the baseband signal using the generated third pseudo-random spreading code sequence and the local carrier, to obtain carrier frequency phase information and synchronization pseudo-code phase information synchronized with the pilot branch in the baseband signal; to determine the demodulation carrier synchronized with the data branch in the baseband signal based on the carrier frequency phase information; to demodulate the baseband signal using the demodulation carrier to obtain the demodulated data signal; to perform phase adjustment on the generated fourth pseudo-random spreading code sequence based on the synchronization pseudo-code phase information, and to despread the demodulated data signal based on the phase adjustment result to obtain the target data sequence.

[0040] like Figure 2 As shown, the receiver 120 includes: a second pseudocode generation module 1201, a pilot acquisition and tracking module 1202, and a data demodulation module 1203.

[0041] The second pseudo-random code generation module 1201 is used to generate a third pseudo-random spreading code sequence and a fourth pseudo-random spreading code sequence, and send the third pseudo-random spreading code sequence to the pilot acquisition and tracking module 1202, and send the fourth pseudo-random spreading code sequence to the data demodulation module 1203.

[0042] The third pseudo-random spreading code sequence is identical to the first pseudo-random spreading code sequence, and the fourth pseudo-random spreading code sequence is identical to the second pseudo-random spreading code sequence. The third pseudo-random spreading code sequence is provided to the pilot acquisition and tracking module 1202 for despreading the pilot signal; the fourth pseudo-random spreading code sequence is provided to the data demodulation module 1203 for despreading the data signal.

[0043] The pilot acquisition and tracking module 1202 is used to acquire and track the baseband signal using the third pseudo-random spreading code sequence and the local carrier, to obtain the carrier frequency phase information and synchronization pseudo-code phase information synchronized with the pilot branch in the baseband signal; and to send the carrier frequency phase information and synchronization pseudo-code phase information to the data demodulation module 1203.

[0044] Among them, the carrier frequency information is the carrier frequency offset, corresponding to the Doppler frequency offset and the fixed crystal oscillator frequency offset; the specific data can be determined according to the application scenario. The carrier phase information is the carrier phase offset, ranging from 0 to 360°. The synchronization pseudocode phase information must correspond to the pseudocode length, which corresponds to the example code length of 1023 mentioned above. The pilot pseudocode phase information ranges from 1 to 1023.

[0045] In some embodiments, the pilot acquisition and tracking module 1202 is specifically used to: perform coherent acquisition calculation on the baseband signal based on the local carrier generated by the received local oscillator and the third pseudo-random spreading code sequence to obtain initial tracking state information; the initial tracking state information includes: initial tracking carrier frequency information and initial tracking pseudo-code phase information; based on the initial tracking carrier frequency information and initial tracking pseudo-code phase information, perform coherent tracking calculation on the baseband signal based on the local carrier generated by the received local oscillator and the third pseudo-random spreading code sequence to obtain carrier frequency phase information and synchronization pseudo-code phase information synchronized with the pilot branch in the baseband signal.

[0046] Among them, stable carrier frequency phase information and pseudocode phase information are obtained by capturing and tracking the received baseband signal.

[0047] Specifically, the baseband signal is input to the acquisition unit. The acquisition unit uses the local carrier generated by the receiving local oscillator through the carrier generation module and the third pseudo-random spreading code sequence to perform coherent acquisition calculation on the pilot signal and outputs the initial tracking state information. The initial tracking state includes the initial tracking carrier frequency information and the initial tracking pseudo-code phase information.

[0048] After acquisition, the tracking and link quality detection unit uses the initial tracking status information provided by the acquisition unit as a reference, and uses the local carrier generated by the receiving local oscillator through the carrier generation module and the third pseudo-random spreading code sequence to perform coherent tracking calculation on the pilot signal. It outputs in real time the carrier frequency phase information and synchronization pseudo-code phase information synchronized with the baseband signal pilot branch, as well as the pilot branch link quality information. The pilot branch link quality information can provide support for the information rate closed-loop control of the subsequent system.

[0049] The pilot tributary link quality information can be the link SNR status. The transmitting and receiving ends can formulate a closed-loop rate control mechanism based on this information to achieve adaptive adjustment of the communication rate and effectively improve the system's spectrum resource utilization.

[0050] The carrier generation module can generate a carrier signal based on the received local oscillator through frequency multiplication, mixing, etc. The intermediate frequency carrier frequency is consistent with that of the transmitter, typically 70MHz, 1200MHz, etc. The acquisition unit can adopt an FFT parallel coherent acquisition algorithm structure. The tracking and link quality detection unit can include a pseudo-code tracking unit, a carrier tracking unit, and a link quality estimation unit. The pseudo-code tracking unit can adopt a DLL tracking algorithm structure, the carrier tracking unit can adopt a Costas tracking algorithm structure, and the link quality estimation unit can adopt a joint loop SNR estimation algorithm structure. The acquisition unit, tracking and link quality detection unit are matched with the transmitter and designed with a pre-formed filtering stage, such as a square root raised cosine roll-off filter.

[0051] The data demodulation module 1203 is used to determine the demodulation carrier synchronized with the data branch in the baseband signal according to the carrier frequency phase information; demodulate the baseband signal through the demodulation carrier to obtain the demodulated data signal; perform phase adjustment on the fourth pseudo-random spreading code sequence according to the synchronization pseudo-code phase information; and despread the demodulated data signal according to the phase adjustment result to obtain the target data sequence.

[0052] The data demodulation module 1203 performs carrier synchronization, pseudocode synchronization, demodulation, despreading, and data recovery processing on the data branch signals in the baseband signal.

[0053] Specifically, based on the carrier frequency phase information and referencing the receiving local oscillator, the carrier generation and adjustment module generates and shifts the phase of the carrier signal through a 90° phase shifter, outputting a demodulated carrier synchronized with the data branch in the baseband signal. This demodulates the received baseband signal to obtain the demodulated data signal.

[0054] The carrier generation and adjustment module can generate a carrier signal by frequency multiplication, mixing, etc. based on the received local oscillator, and adjust the carrier signal according to the carrier frequency and phase information to make it consistent with the carrier state of the pilot branch of the received baseband signal. The carrier fundamental frequency is consistent with the transmitter, which is generally 70MHz, 1200MHz, etc.

[0055] The 90° phase shifter performs a 90° phase shift on the carrier signal output by the carrier generation and adjustment module, so that the output demodulation carrier is orthogonal to the pilot branch carrier, that is, it is consistent with the state of the data branch carrier of the received baseband signal.

[0056] In some embodiments, the data demodulation module 1203 is specifically used for: performing phase adjustment on the fourth pseudo-random spreading code sequence according to the phase information of the synchronization pseudo-code to obtain the demodulation pseudo-code sequence; despreading the demodulated data signal through the demodulation pseudo-code sequence to obtain the despread data sequence; and decoding the despread data sequence to obtain the target data sequence.

[0057] Specifically, based on the pseudo-code phase information provided by the pilot demodulation and tracking module 1202, the fourth pseudo-random spreading code sequence can be phase-adjusted by the pseudo-code phase adjustment module to obtain the demodulated pseudo-code sequence. The demodulated data signal can then be despread to obtain the despread data sequence, which is then decoded to generate the final data sequence, i.e., the target data sequence.

[0058] The pseudocode phase adjustment module can adjust the phase of the fourth pseudo-random spreading code sequence according to the pseudocode phase information, so that it is consistent with the pseudocode phase state of the received baseband signal.

[0059] The decoding module corresponds to the transmitter 110 and may include Viterbi decoding, LDPC decoding, etc.

[0060] This embodiment provides a spread spectrum communication system based on orthogonal pilots, comprising: a transmitter and a receiver; the transmitter is used to spread the spectrum using a generated first pseudo-random spreading code sequence and a locally generated fixed pilot sequence to obtain pilot branch signals and pilot pseudo-code phase information; after performing code transformation on the user-input original data sequence, it spreads the original data sequence using a generated second pseudo-random spreading code sequence to obtain data branch signals; it synchronizes the phase of the data branch signals according to the pilot pseudo-code phase information to ensure that the data branch signals and pilot branch signals are in the same phase; it modulates the pilot branch signals in the pilot branch and the data branch signals in the data branch, and also modulates the pilot branch signals... The pilot and data branch signals are orthogonally combined to obtain the baseband signal. This baseband signal is then transmitted to the receiver via the radio frequency channel. At the receiver, the generated third pseudo-random spreading code sequence and the local carrier are used to acquire and track the baseband signal, obtaining carrier frequency phase information and synchronization pseudo-code phase information synchronized with the pilot branch in the baseband signal. Based on the carrier frequency phase information, the demodulation carrier synchronized with the data branch in the baseband signal is determined. The baseband signal is demodulated using the demodulation carrier to obtain the demodulated data signal. The phase of the generated fourth pseudo-random spreading code sequence is adjusted based on the synchronization pseudo-code phase information, and the demodulated data signal is despread based on the phase adjustment result to obtain the target data sequence. Thus, through parallel processing of the pilot and data branches, pilot information can be accurately extracted at the receiver to achieve carrier synchronization and pseudo-code synchronization. This effectively improves the anti-interference capability and data transmission accuracy of the spread spectrum communication system in complex channel environments, ensuring that the target data sequence can be accurately recovered, and greatly improving the efficiency of spread spectrum communication.

[0061] Figure 4 This embodiment provides a flowchart illustrating a spread spectrum communication method based on orthogonal pilots. The spread spectrum communication method based on orthogonal pilots may include: S410: The transmitter uses the generated first pseudo-random spreading code sequence and the locally generated fixed pilot sequence to spread the spectrum, obtaining the pilot branch signal and pilot pseudo-code phase information; after performing code transformation on the user-input original data sequence, it uses the generated second pseudo-random spreading code sequence to spread the spectrum with the original data sequence, obtaining the data branch signal; it performs phase synchronization of the data branch signal according to the pilot pseudo-code phase information, so that the data branch signal and the pilot branch signal are in the same phase; it performs modulation processing on the pilot branch signal and modulation processing on the data branch signal, and performs orthogonal combining of the pilot branch signal and the data branch signal to obtain the baseband signal; it transmits the baseband signal to the receiver through the radio frequency channel.

[0062] The transmitting end provides two pseudo-code sequences (i.e., the first pseudo-random spreading code sequence and the second pseudo-random spreading code sequence) generated by the first pseudo-code generation module to the pilot generation module and the data generation and spreading module. The pilot generation module forms and outputs the spread spectrum signal based on the first pseudo-random spreading code sequence, and simultaneously provides the pilot pseudo-code phase to the data generation and spreading module to achieve pseudo-code alignment. The data generation and spreading module receives the input data sequence, encodes, spreads, and synchronizes the data to obtain the spread spectrum data signal. The modulation module uses two mutually orthogonal amplitude-controlled carriers to modulate the spread spectrum pilot signal and the spread spectrum data signal, and obtains the baseband signal through orthogonal synthesis. Finally, the baseband signal is transmitted to the receiving end through the radio frequency channel.

[0063] S420: The receiver uses the generated third pseudo-random spreading code sequence and the local carrier to acquire and track the baseband signal, obtaining carrier frequency phase information and synchronization pseudo-code phase information synchronized with the pilot branch in the baseband signal; based on the carrier frequency phase information, it determines the demodulation carrier synchronized with the data branch in the baseband signal; it demodulates the baseband signal using the demodulation carrier to obtain the demodulated data signal; it performs phase adjustment on the generated fourth pseudo-random spreading code sequence based on the synchronization pseudo-code phase information, and despreads the demodulated data signal based on the phase adjustment result to obtain the target data sequence.

[0064] The receiving end performs frequency conversion processing on the received radio frequency signal to obtain the baseband signal, which is then input into the pilot acquisition and tracking module and the data demodulation module. The pilot acquisition and tracking module uses the local carrier generated by the local oscillator and the local pseudocode generated by the second pseudocode generation module to acquire and track the pilot branch signal in the baseband signal, obtaining the carrier frequency phase and pseudocode phase, and calculating the link quality information of the pilot branch; the carrier frequency phase and pseudocode phase are used as coherent reference inputs to the data demodulation module. The data demodulation module uses the pilot tracking results to perform coherent demodulation, thereby recovering the output data sequence.

[0065] Thus, by processing the pilot branch and the data branch in parallel, pilot information can be accurately extracted at the receiving end to achieve carrier synchronization and pseudocode synchronization, effectively improving the anti-interference capability and data transmission accuracy of the spread spectrum communication system in complex channel environments, ensuring that the target data sequence can be accurately recovered, and greatly improving the efficiency of spread spectrum communication.

[0066] It should be noted that the specific implementation principle of the corresponding method in this embodiment is the same as the implementation method given by the functional limitation of the corresponding module shown in the system of this embodiment, and will not be repeated here.

[0067] In summary, this embodiment employs an independent pilot branch to support long-term coherent integration under extremely low signal-to-noise ratios, significantly improving acquisition sensitivity and tracking accuracy; the continuously existing pilot provides the system with a phase and frequency reference unaffected by data rate changes, ensuring link continuity in variable-rate communication; the continuously existing pilot provides both communicating parties with a precise means of monitoring link status, creating the core conditions for subsequent dynamic rate adaptive adjustment.

[0068] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of modules or units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0069] In the various embodiments of this application, the functional units or modules can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0070] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) or processor to execute all or part of the steps of the methods of the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0071] In the claims, any reference signs placed between parentheses should not be construed as limiting the claims. The word "comprising" as described in this application does not exclude the presence of elements or steps not listed in the claims. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. This application can be implemented by means of hardware comprising several different elements and by means of a suitably programmed computer. In the unit claims listing several means, several units of these means may be embodied by the same item of hardware. The use of "first," "second," and "third," etc., does not indicate any order and these words should be interpreted as names. Unless otherwise specified, the steps in the above embodiments should not be construed as limiting the order of execution.

[0072] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A spread spectrum communication system based on orthogonal pilots, characterized in that, include: Transmitter and receiver; The transmitting end is used to spread spectrum using the generated first pseudo-random spreading code sequence and the locally generated fixed pilot sequence to obtain pilot branch signals and pilot pseudo-code phase information; After performing code transformation on the original data sequence input by the user, the generated second pseudo-random spreading code sequence is used to spread the original data sequence to obtain the data branch signal; The data branch signal is phase-synchronized according to the pilot pseudocode phase information so that the data branch signal and the pilot branch signal are in the same phase. The pilot branch signal is modulated in the pilot branch, the data branch signal is modulated in the data branch, and the pilot branch signal and the data branch signal are orthogonally combined to obtain the baseband signal. The baseband signal is transmitted to the receiving end via the radio frequency channel; The receiving end is used to capture and track the baseband signal using the generated third pseudo-random spreading code sequence and local carrier, to obtain carrier frequency phase information and synchronization pseudo-code phase information synchronized with the pilot branch in the baseband signal; and to determine the demodulation carrier synchronized with the data branch in the baseband signal based on the carrier frequency phase information. The baseband signal is demodulated by the carrier wave to obtain the demodulated data signal; The phase of the generated fourth pseudo-random spreading code sequence is adjusted according to the phase information of the synchronization pseudo-code, and the demodulated data signal is despread according to the phase adjustment result to obtain the target data sequence.

2. The system according to claim 1, characterized in that, The transmitting end includes: a first pseudo-code generation module, a pilot generation module, a data generation and spread spectrum module, and a data modulation module; The first pseudo-random code generation module is used to generate a first pseudo-random spreading code sequence and a second pseudo-random spreading code sequence, and send the first pseudo-random spreading code sequence to the pilot generation module and send the second pseudo-random spreading code sequence to the data generation and spreading module. The pilot generation module is used to spread the spectrum according to the first pseudo-random spreading code sequence and the locally generated fixed pilot sequence to obtain pilot branch signals and pilot pseudo-code phase information; and to send the pilot pseudo-code phase information to the data generation and spreading module, and to send the pilot branch signals to the data modulation module. The data generation and spreading module is used to perform code transformation on the user-input raw data sequence, spread the raw data sequence and the second pseudo-random spreading code sequence to obtain a data branch signal; synchronize the data branch signal with the pilot pseudo-code phase information so that the data branch signal and the pilot branch signal are in the same phase; and send the data branch signal to the data modulation module. The data modulation module is used to modulate the pilot branch signal in the pilot branch, modulate the data branch signal in the data branch, and perform orthogonal combining of the pilot branch signal and the data branch signal to obtain a baseband signal; and transmit the baseband signal to the receiving end through the radio frequency channel.

3. The system according to claim 2, characterized in that, The data modulation module is specifically used for: The intermediate frequency carrier signal generated by the transmitting local oscillator is distributed with different powers by a power divider to obtain the pilot adjustment signal and the data modulation signal; The pilot branch signal is modulated according to the pilot adjustment signal; after the data modulation signal is shifted by a phase shifter, the data branch signal is modulated according to the data modulation signal.

4. The system according to claim 2, characterized in that, The data modulation module is specifically used for: The pilot branch signal is used as the in-phase component, and the data branch signal is used as the quadrature component; or, the data branch signal is used as the in-phase component, and the pilot branch signal is used as the quadrature component. By using an orthogonal combiner, the in-phase component and the orthogonal component are vector-synthesized according to the amplitude and phase information corresponding to the in-phase component and the quadrature component to obtain the baseband signal.

5. The system according to claim 1, characterized in that, The receiving end includes: a second pseudocode generation module, a pilot acquisition and tracking module, and a data demodulation module; The second pseudo-random code generation module is used to generate a third pseudo-random spreading code sequence and a fourth pseudo-random spreading code sequence, and send the third pseudo-random spreading code sequence to the pilot acquisition and tracking module, and send the fourth pseudo-random spreading code sequence to the data demodulation module; The pilot acquisition and tracking module is used to acquire and track the baseband signal using the third pseudo-random spreading code sequence and the local carrier, to obtain carrier frequency phase information and synchronization pseudo-code phase information that are synchronized with the pilot branch in the baseband signal; and to send the carrier frequency phase information and the synchronization pseudo-code phase information to the data demodulation module. The data demodulation module is used to determine a demodulation carrier synchronized with the data branch in the baseband signal according to the carrier frequency phase information; demodulate the baseband signal through the demodulation carrier to obtain a demodulated data signal; perform phase adjustment on the fourth pseudo-random spreading code sequence according to the synchronization pseudo-code phase information; and despread the demodulated data signal according to the phase adjustment result to obtain a target data sequence.

6. The system according to claim 5, characterized in that, The pilot acquisition and tracking module is specifically used for: The initial tracking state information is obtained by performing coherent acquisition calculation on the baseband signal based on the local carrier generated by the received local oscillator and the third pseudo-random spreading code sequence. The initial tracking status information includes: initial tracking carrier frequency information and initial tracking pseudocode phase information; Based on the initial tracking carrier frequency information and the initial tracking pseudocode phase information, coherent tracking calculations are performed on the baseband signal according to the local carrier generated by the received local oscillator and the third pseudo-random spreading code sequence to obtain carrier frequency phase information and synchronization pseudocode phase information synchronized with the pilot branch in the baseband signal.

7. The system according to claim 5, characterized in that, The data demodulation module is specifically used for: The fourth pseudo-random spreading code sequence is phase-adjusted according to the phase information of the synchronization pseudo-code to obtain the demodulation pseudo-code sequence; the demodulated data signal is despread using the demodulation pseudo-code sequence to obtain the despread data sequence. The despread data sequence is decoded to obtain the target data sequence.

8. The system according to claim 1, characterized in that, The pilot branch is a QPSK modulated I branch, and the data branch is a QPSK modulated Q branch; or, the data branch is a QPSK modulated I branch, and the pilot branch is a QPSK modulated Q branch.

9. The system according to claim 1, characterized in that, The third pseudo-random spreading code sequence is the same as the first pseudo-random spreading code sequence, and the fourth pseudo-random spreading code sequence is the same as the second pseudo-random spreading code sequence.

10. A spread spectrum communication method based on orthogonal pilots, characterized in that, include: The transmitting end uses the generated first pseudo-random spreading code sequence and the locally generated fixed pilot sequence to spread the spectrum, thereby obtaining the pilot branch signal and pilot pseudo-code phase information; After performing code transformation on the original data sequence input by the user, the generated second pseudo-random spreading code sequence is used to spread the original data sequence to obtain the data branch signal; The data branch signal is phase-synchronized according to the pilot pseudocode phase information so that the data branch signal and the pilot branch signal are in the same phase. The pilot branch signal is modulated in the pilot branch, the data branch signal is modulated in the data branch, and the pilot branch signal and the data branch signal are orthogonally combined to obtain the baseband signal. The baseband signal is transmitted to the receiving end via the radio frequency channel; The receiving end uses the generated third pseudo-random spreading code sequence and local carrier to capture and track the baseband signal, and obtains carrier frequency phase information and synchronization pseudo-code phase information that are synchronized with the pilot branch in the baseband signal; based on the carrier frequency phase information, it determines the demodulation carrier that is synchronized with the data branch in the baseband signal. The baseband signal is demodulated by the carrier wave to obtain the demodulated data signal; The phase of the generated fourth pseudo-random spreading code sequence is adjusted according to the phase information of the synchronization pseudo-code, and the demodulated data signal is despread according to the phase adjustment result to obtain the target data sequence.

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