A dynamic environment distributed coherent communication carrier synchronization method and device

Abstract

The application discloses a dynamic environment distributed coherent communication carrier synchronization method and device, relates to the distributed coherent communication technology, and comprises the following steps: after time synchronization, time resources of a system are divided according to time slots; in a synchronization time slot T i,1 , a master node sends a synchronization reference signal to all slave nodes; each slave node S n measures the phase change value between two same pilot symbol sequences in a received signal, estimates a frequency offset, and calculates phase and amplitude estimation values; each slave node S n analyzes data symbols obtained from a received synchronization reference waveform signal to obtain a coherent cooperation micro time slot; each slave node S n performs distributed coherent cooperation communication to the master node M in each time slot T i ; the frequency, phase and amplitude of the reference signal are measured respectively; in the synchronization time slot T i,1 and the coherent cooperation time slot T i,j , distributed coherent cooperation communication of multiple slave nodes S n to the master node M is performed. The application can solve the distributed carrier synchronization problem caused by a dynamic environment and improve the adaptive ability of a system to channel state changes.

Description

Technical Field

[0001] This application relates to the field of distributed coherent communication technology, and in particular to a method and apparatus for carrier synchronization in dynamic environment distributed coherent communication. Background Technology

[0002] Existing distributed coherent communication carrier phase synchronization methods are mainly designed for static environments with fixed nodes. They require feeding back parameters such as phase and power estimated by the receiver to the transmitter, which necessitates the construction of a separate feedback link or feedback time slot resources. Furthermore, multiple feedback adjustments are required to reach convergence, resulting in low real-time performance. These methods cannot effectively track channel changes caused by node movement, and the feedback chain consumes a large amount of system resources, limiting system capacity and operating efficiency.

[0003] Distributed coherent communication involves multiple nodes geographically distributed, simultaneously transmitting the same information to a receiver at the same frequency. Their signals are superimposed at the receiver. By ensuring, through technical means, that the resulting composite signal reaching the receiver is coherently superimposed, a significant improvement in received signal amplitude can be achieved. This distributed transmission architecture can use multiple low-power transmitters to achieve the same transmission effect as a single high-power transmitter with a directional antenna, making it particularly suitable for applications with multiple small distributed nodes. The key to achieving distributed coherent communication lies in the synchronization between the communication nodes, including frequency synchronization and phase synchronization.

[0004] Chinese Patent Publication No. CN117834100A discloses a carrier phase synchronization method in distributed coherent communication. This method uses n transmitters that have achieved carrier frequency synchronization. Each of the n transmitters independently and randomly generates an initial value for the carrier phase correction. Each transmitter also independently and randomly generates a phase perturbation value within a certain range, generating two symbols, one of which has a phase perturbation added. The receiver receives the composite signal transmitted by the n transmitters, calculates the average power and the local phase perturbation value, and feeds it back to the transmitter. The transmitter updates its local phase correction value by multiplying it by a step size factor. These steps are repeated until the phase synchronization process converges.

[0005] Chinese Patent Publication No. CN118473534A discloses a multi-node distributed coherent communication method and system for dynamic environments. This method divides a time slot into two sub-time slots: a synchronization time slot and a cooperative communication time slot. In the synchronization time slot, cooperative transmitting nodes, based on a corrected frequency oscillator, measure the relative distance and channel between the cooperative transmitting and receiving nodes. In the cooperative communication phase, each cooperative transmitting node first calculates its own compensation coefficient based on the channel gain matrix between the cooperative transmitting and receiving nodes. After the source node sends the information to be transmitted to the cooperative transmitting node, the cooperative transmitting node first enhances the signal and then performs calculations on the signal using the calculated compensation coefficients. After receiving the coherent signal, the cooperative receiving node transmits the coherent signal to the destination node for signal processing.

[0006] Due to the Doppler effect caused by node motion, the channel coherence time is relatively short. The multiple feedback method in Chinese Patent CN117834100A requires multiple measurements and feedbacks between the transmitter and receiver. If the time required for multiple feedbacks exceeds the channel coherence time, it will cause phase synchronization non-convergence. Furthermore, feeding back the average signal power of two symbols requires a separate feedback link between the transmitter and receiver, resulting in a waste of system resources.

[0007] Chinese patent CN118473534A assumes that the time of a time slot is less than the channel correlation time. However, since the transmission between cooperating nodes is unidirectional, the transmitting and receiving nodes in the synchronization time slot and the cooperative communication time slot are different nodes. This will lead to different channel conditions such as phase change and channel attenuation. In other words, the channel states of the synchronization time slot and the cooperative communication time slot are inconsistent. As a result, the channel attenuation and phase measurement between nodes estimated in the synchronization time slot stage cannot truly reflect the channel state between nodes in the cooperative communication time slot, causing a mismatch in carrier frequency and phase synchronization. This will seriously affect the effect of distributed coherent transmission. Summary of the Invention

[0008] This application provides a method and apparatus for distributed coherent communication carrier synchronization in dynamic environments, which solves the distributed carrier synchronization problem caused by dynamic environments and improves the system's adaptability to changes in channel state.

[0009] This application provides a dynamic environment distributed coherent communication carrier synchronization method, applied to a system including one master node M and N slave nodes S1, S2, ..., S... n, In a distributed coherent communication system where n = 1, 2, ..., N, the master node and slave nodes, and the slave nodes themselves, transmit and receive signals via a wireless channel. The synchronization method includes:

[0010] After time synchronization, the system time resources are divided into time slots;

[0011] In synchronization time slot T i,1 The master node sends a synchronization reference signal to all slave nodes;

[0012] Each slave node S n The frequency offset value is estimated by measuring the phase change value between two identical pilot symbol sequences in the received signal after receiving the signal.

[0013] Each slave node S n By performing correlation operations on the received pilot signal and the locally known pilot signal, the estimated values ​​of phase and amplitude are obtained.

[0014] Each slave node S n The coherently coordinated micro-time slots obtained by analyzing the data symbols in the received synchronization reference waveform signal are used as the current time slot T. i The micro-time slot T of each slave node transmitting coherent cooperative signals i,j ;

[0015] Each slave node S n In each time slot T i The frequency, phase, and amplitude of the reference signal transmitted by the master node M are measured respectively.

[0016] In synchronization time slot T i,1 Coherent collaboration time slot T i,j Within the time interval, based on the measurement results and phase and amplitude estimates, multiple slave nodes S are... n Distributed coherent collaborative communication to master node M.

[0017] This application provides a dynamic environment distributed coherent communication carrier synchronization device, applied to a system including one master node M and N slave nodes S1, S2, ..., S... n, In a distributed coherent communication system with n = 1, 2, ..., N, the master node and slave nodes, and the slave nodes transmit and receive signals through a wireless channel. The master node and slave nodes include a processor and a memory. The memory stores a computer program. When the computer program is executed by the processor, it implements the steps of the dynamic environment distributed coherent communication carrier synchronization method described above.

[0018] The embodiments of this application construct a distributed coherent communication system in an open-loop manner, without the need for a separate feedback link or feedback time slot resources; at the same time, a channel state prediction method is used to solve the distributed carrier synchronization problem caused by dynamic environment, and improve the system's adaptability to changes in channel state.

[0019] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0020] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0021] Figure 1 This is a schematic diagram of the architecture of the distributed coherent communication system according to an embodiment of this application;

[0022] Figure 2 This is a schematic diagram of the overall process of the dynamic environment distributed coherent communication carrier synchronization method in the embodiments of this application;

[0023] Figure 3 This is a schematic diagram of time slot allocation for the dynamic environment distributed coherent communication carrier synchronization method in an embodiment of this application. Detailed Implementation

[0024] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0025] This application provides a method for distributed coherent communication carrier synchronization in a dynamic environment, such as... Figure 1 As shown, this is applied to a system consisting of one master node M and N slave nodes S1, S2, ..., S... n, In a distributed coherent communication system with n = 1, 2, ..., N, the master node and slave nodes, as well as the slave nodes themselves, transmit and receive signals via wireless channels. The system employs time-division multiple access (TDMA) to allocate link resources between the master and slave nodes. For example... Figure 2 As shown, the synchronization method in this application embodiment includes the following steps:

[0026] In step S101, after time synchronization, the system time resources are divided into time slots; in some embodiments, dividing the system time resources into time slots includes:

[0027] Each time slot T is divided iEach time slot has a specified duration, and each time slot is divided into a specified number of micro-time slots. Among these micro-time slots, one fixed micro-time slot is designated as the synchronization time slot, while the other micro-time slots are designated as coherent cooperation time slots. For example... Figure 3 As shown, each time slot T i 10ms long, each time slot T i Divided into 10 micro-time slots T i,1 ,T i,2 ,……,T i,10 Each micro-timeslot is 1 ms long, and one of the 10 micro-timeslots is a fixed timeslot T. i,1 Used as a synchronization time slot, the master node can select one micro-time slot T. i,j j = 2, 3, ..., 10, are used as coherent cooperation time slots, and the remaining micro time slots are used for service transmission between slave nodes and the exchange of coherent cooperation information between slave nodes.

[0028] In step S102, during the synchronization time slot T i,1 The master node sends a synchronization reference signal to all slave nodes. In some embodiments, the synchronization reference signal sent by the master node to all slave nodes includes two or more identical pilot sequence symbols and several data symbols, wherein the pilot sequence symbols and data symbols are QPSK modulated as X(t) = Acos(2πf c t+θ i ), i = 1, 2, 3, 4, 0 ≤ t ≤ T s T s As a symbol interval, based on the aforementioned example of 10 micro-slots, the data symbols carry information about the micro-slot number j, j = 2, 3, ..., 10 used as coherent cooperation slots.

[0029] In step S103, each slave node S n The signal transmitted by the master node M is received, and the frequency offset is estimated by measuring the phase change between two identical pilot symbol sequences in the received signal.

[0030] In step S104, each slave node S n Phase and amplitude estimates are calculated by performing correlation operations on the received pilot signal and the locally known pilot signal.

[0031] In step S105, each slave node S n The coherently coordinated micro-time slots obtained by analyzing the data symbols in the received synchronization reference waveform signal are used as the current time slot T. i The micro-time slot T of each slave node transmitting coherent cooperative signals i,j .

[0032] In step S106, each slave node S n In each time slot T iThe frequency, phase, and amplitude of the reference signal sent by the master node M are measured respectively.

[0033] In step S107, during synchronization time slot T i,1 Coherent collaboration time slot T i,j Within the time interval, based on the measurement results and phase and amplitude estimates, multiple slave nodes S are... n Distributed coherent collaborative communication to master node M.

[0034] In some embodiments, each slave node S n The signal received from the master node M satisfies:

[0035]

[0036] Among them, W n (t) represents additive Gaussian noise;

[0037] The frequency offset is estimated by measuring the phase change between two identical pilot symbol sequences in the received signal.

[0038]

[0039] Where T I T is the pilot sequence interval. P f′ represents the duration of the pilot sequence. n =f′ c +f′ d This comprehensively reflects the carrier frequency offset f′ generated by the crystal oscillator at the transceiver node. c And the Doppler frequency shift f′ caused by motion d .

[0040] In some embodiments, each slave node S n By performing correlation calculations using received pilot signals and locally known pilot signals, the following conditions are met:

[0041]

[0042] The phase and amplitude estimates obtained by performing relevant calculations satisfy the following:

[0043]

[0044] Each slave node S n In each time slot T i The frequency, phase, and amplitude of the reference signal transmitted by the master node M are measured respectively, at the current T i i measurements F are obtained in the time slot. n =[f′ n (1),f′ n (2),……,f′ n(i)], [A n =A′ n (1),A′ n (2),……,A′ n (i)].

[0045] After that, each slave node S n The coherent cooperation micro-slot number j obtained by analyzing the data symbols in the received synchronization reference waveform signal is used as the current time slot T. i The micro-time slot T of each slave node transmitting coherent cooperative signals i,j .

[0046] Next, each slave node S n In each time slot T i The frequency, phase, and amplitude of the reference signal transmitted by the master node M are measured respectively, at the current T i i measurements F have been obtained in the time slot. n =[f′ n (1),f′ n (2),……,f′ n (i)], [A n =A′ n (1),A′ n (2),……,A′ n (i)].

[0047] In synchronization time slot T i,1 Coherent collaboration time slot T i,j During the time interval, the relative motion between nodes causes Doppler frequency shift and relative distance changes, resulting in variations in synchronization time slot T. i,1 The measured frequency f′ n (i,1)=f′ n (i) Phase Amplitude A′ n (i,1)=A′ n (i) The parameter value does not accurately reflect the coherent cooperation time slot T i,j The corresponding parameter value f′ n (i,j) A′ n (i,j). Therefore, it needs to be handled on a case-by-case basis. In some embodiments, during the synchronization time slot T i,1 Coherent collaboration time slot T i,j Within the time interval, based on the measurement results and phase and amplitude estimates, multiple slave nodes S are... n Distributed coherent cooperative communication to master node M includes:

[0048] In the current time slot value T iLess than or equal to the specified value T L In the case of coherent cooperation time slot T i,j Using the current time slot T i Internal synchronization slot T i,1 frequency f′ n (i,j)=f′ n (i,1), phase Amplitude A′ n (i,j)=A′ n The (i,1) measurement value is used as the coherent cooperation time slot T. i,j The launch compensation value;

[0049] In coherent collaboration time slot T i,j Each slave node generates a QPSK modulated transmit signal. Implement multiple slave nodes S n Distributed coherent cooperative communication to the master node M enables the master node to obtain amplitude gain or signal-to-noise ratio gain in the received signal.

[0050] In another scenario, in some embodiments, during synchronization time slot T... i,1 Coherent collaboration time slot T i,j Within the time interval, based on the measurement results and phase and amplitude estimates, multiple slave nodes S are... n Distributed coherent collaborative communication to master node M also includes:

[0051] Current time slot value T i Greater than the specified value T L In the case of each slave node S n The current time slot T was measured using multiple measurements. i Inner coherent cooperation time slot T i,j frequency f′ n (i,j), phase Amplitude A′ n The (i,j) parameters are predicted using a method based on the minimum mean square error (LMS) algorithm, which employs the steepest descent method based on gradients.

[0052] according to The next time slot T is calculated. i+1,1 Frequency prediction value Where the weight vector μ f For the frequency prediction step size factor, vector F n The K most recent values ​​of the frequency are used to obtain the next time slot T. i+1 From node S n Frequency difference f′ between the master node M and the master node M n The predicted value of (i+1,1) Similarly, the LMS algorithm can be used to obtain the next time slot T. i+1 Predicted values ​​of phase and amplitude and

[0053] In some embodiments, during synchronization time slot T i,1 Coherent collaboration time slot T i,j Within the time interval, based on the measurement results and phase and amplitude estimates, multiple slave nodes S are... n Distributed coherent collaborative communication to master node M also includes:

[0054] Based on the next time slot T i+1 The predicted value for the current time slot T i The measured value f′ n (i,1) and the next time slot T i+1 Predicted value Perform interpolation to obtain the current time slot T i Inner coherent cooperation time slot T i,j frequency f′ n (i,j), phase amplitude The predicted value of the difference. Specific interpolation methods can be implemented using existing mature algorithms such as linear interpolation or cubic interpolation.

[0055] In some embodiments, it also includes:

[0056] Based on the obtained coherent cooperation time slot T i,j frequency f′ n (i,j), phase amplitude Predicted values, for each slave node S n During the collaboration time slot T i,j Frequency, phase, and amplitude transmission compensation corrections are performed to generate a QPSK modulated transmission signal. This can further enhance the performance of multiple slave nodes S in the motion environment. n The distributed coherent cooperative communication gain to the master node M.

[0057] The method in this application constructs a distributed coherent communication system in an open-loop manner, eliminating the need for a separate feedback link or feedback time slot resources. It offers good real-time performance, enabling rapid tracking of channel changes without consuming network time slot resources. For dynamic environments with relatively moving nodes, the method comprehensively considers the carrier frequency offset generated by the local crystal oscillator, the Doppler frequency offset caused by node movement, and changes in relative distance. Employing a channel state prediction method, it can quickly track channel changes, improve the distributed coherent transmission performance in dynamic environments, and maximize the strength and signal-to-noise ratio of the received signal.

[0058] The method in this application embodiment can reduce the occupancy rate of synchronization time slots, support flexible configuration of coherent cooperative time slots, and allow the remaining time slot resources to be used for service transmission, thereby improving the system link capacity and enabling the system to accommodate more nodes.

[0059] This application also proposes a dynamic environment distributed coherent communication carrier synchronization device, applied to a system including one master node M and N slave nodes S1, S2, ..., S... n, In a distributed coherent communication system with n = 1, 2, ..., N, the master node and slave nodes, and the slave nodes transmit and receive signals through a wireless channel. The master node and slave nodes include a processor and a memory. The memory stores a computer program. When the computer program is executed by the processor, it implements the steps of the dynamic environment distributed coherent communication carrier synchronization method described above.

[0060] It should be noted that, in the embodiments of this application, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0061] The sequence numbers of the embodiments in this application are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0062] Through the above description of the embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) and includes several instructions to cause a terminal (which may be a mobile phone, computer, server, air conditioner, or network device, etc.) to execute the methods described in the various embodiments of this application.

[0063] The embodiments of this application have been described above with reference to the accompanying drawings. However, this application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of the claims. All of these forms are within the protection scope of this application.

Claims

1. A method for distributed coherent communication carrier synchronization in a dynamic environment, characterized in that, Applicable to a system consisting of one master node M and N slave nodes In a distributed coherent communication system, the master node and slave nodes, and the slave nodes transmit and receive signals through a wireless channel. The synchronization method includes: After time synchronization, the system time resources are divided into time slots; In the synchronization time slot The master node sends a synchronization reference signal to all slave nodes; Each slave node The frequency offset value is estimated by measuring the phase change value between two identical pilot symbol sequences in the received signal after receiving the signal. Each slave node By performing correlation operations on the received pilot signal and the locally known pilot signal, the estimated values ​​of phase and amplitude are obtained. Each slave node The coherently coordinated micro-time slots obtained by analyzing the data symbols in the received synchronization reference waveform signal are used as the current time slot. Micro-time slots for each slave node to send coherent cooperative signals ; Each slave node In each time slot The frequency, phase, and amplitude of the reference signal transmitted by the master node M are measured respectively. In the synchronization time slot and coherent collaboration time slots Within the time interval, based on the measurement results and phase and amplitude estimates, multiple slave nodes are... Distributed coherent collaborative communication to master node M; In the synchronization time slot and coherent collaboration time slots Within the time interval, based on the measurement results and phase and amplitude estimates, multiple slave nodes are... Distributed coherent cooperative communication to master node M includes: In the current time slot value Less than or equal to the specified value In the case of coherent collaboration time slots Use the current time slot Internal synchronization slot frequency Phase Amplitude Measurements as coherent cooperation time slots The launch compensation value; In coherent collaboration time slots Each slave node generates a QPSK modulated transmit signal. To enable multiple slave nodes Distributed coherent collaborative communication to master node M; In the synchronization time slot and coherent collaboration time slots Within the time interval, based on the measurement results and phase and amplitude estimates, multiple slave nodes are... Distributed coherent collaborative communication to master node M also includes: Current time slot value Greater than the specified value In this case, each slave node The current time slot was measured using multiple measurements. Inner coherent cooperation time slot frequency Phase Amplitude Predict parameters; according to Calculate the next time slot Frequency prediction value , where the weight vector , For frequency prediction step size factor, vector The K most recent values ​​of the frequency are used to obtain the next time slot. From node Frequency difference between the master node M and the master node M Predicted value ; In the synchronization time slot and coherent collaboration time slots Within the time interval, based on the measurement results and phase and amplitude estimates, multiple slave nodes are... Distributed coherent collaborative communication to master node M also includes: Based on the next time slot The predicted value for the current time slot Measured values and the next time slot Predicted value Perform interpolation to obtain the current time slot. Inner coherent cooperation time slot frequency Phase Amplitude Predicted value of the difference; Also includes: Based on the obtained coherent cooperation time slots frequency Phase Amplitude Each from node During collaboration time slots Frequency, phase, and amplitude transmission compensation corrections are performed to generate a QPSK modulated transmission signal. .

2. The dynamic environment distributed coherent communication carrier synchronization method as described in claim 1, characterized in that, Dividing system time resources by time slots includes: Each time slot is divided Each time slot is assigned a specified duration, and each time slot is divided into a specified number of micro-time slots. Among the multiple micro-time slots, a fixed micro-time slot is designated as the synchronization time slot, and the other micro-time slots are designated as coherent cooperation time slots.

3. The dynamic environment distributed coherent communication carrier synchronization method as described in claim 1, characterized in that, In the synchronization time slot The synchronization reference signal sent by the master node to all slave nodes includes two or more identical pilot sequence symbols and several data symbols, wherein the pilot sequence symbols and data symbols are QPSK modulated. , The symbol interval is used for symbol spacing.

4. The dynamic environment distributed coherent communication carrier synchronization method as described in claim 1, characterized in that, Each slave node The signal received from the master node M satisfies: in, It is additive Gaussian noise; The frequency offset is estimated by measuring the phase change between two identical pilot symbol sequences in the received signal. in For pilot sequence spacing, The duration of the pilot sequence.

5. The dynamic environment distributed coherent communication carrier synchronization method as described in claim 1, characterized in that, Each slave node By performing correlation calculations using received pilot signals and locally known pilot signals, the following conditions are met: The phase and amplitude estimates obtained by performing relevant calculations satisfy the following: Each slave node In each time slot The frequency, phase, and amplitude of the reference signal transmitted by the master node M are measured respectively. Time slot acquisition Measured values , , .

6. A dynamic environment distributed coherent communication carrier synchronization device, characterized in that, Applicable to a system consisting of one master node M and N slave nodes The distributed coherent communication system, in which the master node and slave nodes, and the slave nodes transmit and receive signals through a wireless channel, wherein the master node and slave nodes include a processor and a memory, and the memory stores a computer program, which, when executed by the processor, implements the steps of the dynamic environment distributed coherent communication carrier synchronization method as described in any one of claims 1 to 5.

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