Distributed beam sidelobe suppression method under static condition

Abstract

The invention relates to a distributed beam sidelobe suppression method under a static condition, which comprises the following steps that: before an iterative feedback process starts, random phase disturbance is introduced to each transmitting node, and after the phase disturbance is added to a currently known optimal transmitting phase, each transmitting node transmits a signal; then, the receiving node analyzes the received signal strength, and if the received signal strength of a target receiving node corresponding to the transmitting node is increased through the added phase disturbance, and the received signal strength of a non-target receiving node is reduced at the same time; if yes, reflecting the signal strength change conditions of the target receiving node and the non-target receiving node through single-bit feedback information, and updating the optimal sending phase according to the feedback information; the optimal sending phase is found step by step through continuous iteration, and signal sending is carried out by using the sending phase so as to reduce interference of side lobes on a target receiving node to the greatest extent.

Description

Technical Field

[0001] The present invention relates to the field of wireless communication technology, and mainly relates to a distributed beam sidelobe suppression method under static conditions, which is suitable for distributed beam sidelobe suppression based on feedback iteration under static conditions. Background Art

[0002] In distributed beamforming, the position of the transmitting node is randomly selected. The randomly distributed nodes can form a stable main beam that is approximately independent of the node position in the desired direction by adjusting the initial phase of the transmitted signal, generating different beam patterns. Although the main beam is almost independent of the node position, the sideband area of ​​the formed beam pattern is completely determined by the node position. Sidelobes with large peaks may cause interference to other node clusters or base stations. Therefore, controlling the sidelobes of distributed beams is of great significance to increasing the capacity of the network and the spatial availability of the wireless channel.

[0003] At present, there are three main algorithms for distributed sidelobe suppression: the first is an iterative algorithm based on feedback iteration, including 1-bit feedback sidelobe suppression and node selection sidelobe suppression. The node selection method focuses on finding the best location for node placement in the distributed array or selecting a suitable node cluster to participate in the distributed beamforming process to reduce the sidelobe. This is not feasible when the user has no autonomy over the location of the node or the number of nodes is not large enough. The second method is an estimation algorithm that uses local information to estimate global information. This method requires obtaining global channel state information and selecting nodes with the largest channel gain amplitude and the smallest possible phase difference of all channels for transmission. The last one is a direct algorithm that uses distributed computing using information shared between nodes, such as a sidelobe suppression method based on QR decomposition, which solves the weight vector by distributed computing QR decomposition. The latter two methods rely on high-precision synchronization between nodes. Each node must collect location and channel information from all other nodes, which greatly increases the corresponding overhead in the network. Summary of the invention

[0004] The purpose of the present invention is to provide a distributed beam sidelobe suppression method under static conditions to overcome the problem that traditional beam sidelobe suppression methods usually rely on dynamically adjusting beam parameters, but these methods may not provide ideal suppression effects under static conditions.

[0005] In order to achieve the above tasks, the present invention adopts the following technical solutions:

[0006] A distributed beam sidelobe suppression method under static conditions, comprising:

[0007] Before the start of the iterative feedback process, a random phase disturbance is introduced for each transmitting node. After the phase disturbance is added to the currently known optimal transmission phase, each transmitting node sends a signal; then the receiving node analyzes the received signal strength. If the phase disturbance added this time increases the received signal strength of the target receiving node corresponding to the transmitting node and decreases the received signal strength of the non-target receiving node, a single-bit feedback information is used to reflect the signal strength changes of the target receiving node and the non-target receiving node, and the optimal transmission phase is updated according to the feedback information; the optimal transmission phase is gradually found through continuous iteration, and the transmission phase is used to send signals.

[0008] Furthermore, the system model of the method is:

[0009]

[0010] There are N transmitting nodes and K receiving nodes in the communication system. The N transmitting nodes are randomly distributed in a circular area with a radius of R, and the K receiving nodes are randomly distributed in the far field. Each transmitting node S n There is only a single omnidirectional antenna, and each transmitting node S n The useful information to be sent is m(t); the baseband signal received by the receiving node will have an unknown phase offset γ n ,n=1,2,...,N; use represents the nth transmitting node S n To receiving node B k The complex channel gain of n ≥0 indicates the transmitting node S n To receiving node B k The amplitude gain of the channel, ψ nk represents the phase offset of the channel, e is a natural constant, j is an imaginary unit, θ n Indicates the phase, The mean is 0 and the variance is The complex Gaussian white noise, then the kth receiving node B k Received signal strength RSS k for:

[0011]

[0012] In the formula, RSS k Used to measure the distributed beamforming effect; Φ n =γ n +θ n +ψ nk represents the kth receiving node B k Received from the nth transmitting node S nThe total phase shift.

[0013] Furthermore, before the iterative feedback process starts, a random phase disturbance is introduced to each transmitting node, and after the phase disturbance is added to the currently known optimal transmission phase, each transmitting node sends a signal, including:

[0014] Step 2.1, when the number of iterations is i, each transmitting node S n Independently generate a perturbation phase δ n [i], where δ n [i] The value of equal probability is +δ 0 or -δ 0 , δ 0 =π / M is the preset value, M is a positive integer;

[0015] Step 2.2, each transmitting node S n The disturbance phase δ generated by each n [i] Add to the currently known optimal transmission phase θ n [i], a new phase value φ is obtained n [i] = θ n [i]+δ n [i]; Each transmitting node S n With this new phase value φ n [i] Conduct collaborative sending;

[0016] The optimal transmission phase θ n [i] is the transmitting node S n In the previous i-1 iterations, the corresponding target receiving node B 0 The signal strength at the location is the largest, while making the remaining non-target receiving nodes B k′ ,k′=1,2,...,the phase where the signal strength is the smallest at K-1.

[0017] Further, the receiving node analyzes the received signal strength. If the phase disturbance added this time increases the received signal strength of the target receiving node corresponding to the transmitting node, and the received signal strength of the non-target receiving node decreases, a single-bit feedback information is used to reflect the signal strength change of the target receiving node and the non-target receiving node, including:

[0018] Step 2.3, each receiving node B k ,k=1,2,...,K receives data from all transmitting nodes S n After each signal is sent, use Calculate the received signal strength RSS of this iteration k [i], where Φ nk [i] = γn +ψ nk +φ n [i];

[0019] Then the transmitting node S n The corresponding target receiving node B 0 The received signal strength RSS of this node 0 [i] and the maximum received signal strength value RSS obtained in the previous i-1 iterations best,0 For comparison, if RSS 0 [i]>RSS best,0 , then the target receiving node will feedback 1 bit of information "b" to each transmitting node 0 [i]=1", and the maximum received signal strength RSS at the target node best,0 Updates to RSS 0 [i]; If RSS 0 [i]≤RSS best,0 , then the target receiving node B 0 It will give each transmitting node feedback 1 bit of information "b 0 [i]=0", and do not update RSS best,0 ;

[0020] Similarly, each non-target receiving node B k′ The received signal strength RSS obtained in this measurement will also be k [i] and the minimum received signal strength value RSS obtained in the previous i-1 iterations min,k For comparison; if RSS k [i]<RSS min,k , each non-target receiving node will feedback 1 bit of information "b k [i]=1", and the minimum received signal strength RSS min,k Updates to RSS k [i]; If RSS k [i]≥RSS min,k , then each non-target receiving node will feedback 1 bit of information "b k [i]=0", and maintain the minimum received signal strength RSS at the interfering node min,k constant.

[0021] Further, updating the optimal transmission phase according to the feedback information includes:

[0022] Step 2.4, each transmitting node S n After receiving all receiving nodes B in the i-th iteration k After receiving the feedback information, update the phase value used in the i+1th iteration:

[0023] When each transmitting node S n Received all receiving Node B k Feedback k After the signal [i] = 1”, each transmitting node retains the random perturbation phase added for the i-th time and updates the optimal transmission phase θ n [i+1]=φ n [i] = θ n [i]+δ n [i]; As long as there is a feedback signal "b k [i]=0”, each node will discard the random perturbation phase added for the i-th time, that is, θ n [i+1]=θ n [i];

[0024] At this point, the i-th iteration process is completed, and the n-th transmitting node S n The optimal transmission phase is given by θ n [i] Update to θ n [i+1], start the i+1th iteration; keep repeating the above steps until the received signal strength values ​​of all receiving nodes meet the threshold value expected by the system and the iteration stops.

[0025] A communication system comprises a transmitting node and a receiving node; the communication system adopts the distributed beam sidelobe suppression method under static conditions to perform sidelobe suppression.

[0026] A terminal device comprises a processor, a memory and a computer program stored in the memory; when the processor executes the computer program, the distributed beam sidelobe suppression method under static conditions is implemented.

[0027] A computer-readable storage medium stores a computer program; when the computer program is executed by a processor, the distributed beam sidelobe suppression method under static conditions is implemented.

[0028] Compared with the prior art, the present invention has the following technical features:

[0029] 1. The present invention avoids the problem of solving the distributed beamforming weights and the global channel estimation problem, and instead uses a random optimization method to "search" for the optimal weights during the interaction between the receiving node and the transmitting node, thereby greatly reducing the complexity of the algorithm.

[0030] 2. The effect of the present invention is to significantly reduce the sidelobe level of the distributed beam system, improve the detection performance of the target signal, and have scalability, high efficiency, robustness and adaptability. This will have a positive impact on the beamforming technology in the fields of distributed communications, radar, wireless sensor networks, etc., and improve the performance and reliability of the system.

[0031] 3. The present invention provides a reliable way to increase the capacity of the network and the spatial availability of wireless channels in military and civilian long-distance communications, and effectively reduces the interference caused by the random position of the transmitting node in distributed beamforming to other node clusters or base stations. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 Schematic diagram of the distributed sidelobe suppression system model in the present invention;

[0033] Figure 2 A schematic diagram of improving RSS using the feedback sidelobe suppression algorithm in the present invention;

[0034] Figure 3 It is the algorithm flow chart of the present invention;

[0035] Figure 4 For different δ in the present invention 0 The following is the change of RSS of the target receiving end with the number of iterations, where (a) is the target receiving node, (b) is the first non-target receiving node, (c) is the second non-target receiving node, and (d) is the third non-target receiving node. DETAILED DESCRIPTION

[0036] In many communication and radar applications, beam sidelobe is a common problem that can cause signal interference and misjudgment; traditional beam sidelobe suppression methods usually rely on dynamically adjusting beam parameters, but under static conditions, these methods may not provide ideal suppression effects. The present invention aims to provide a method for suppressing distributed beamforming sidelobes under static conditions to achieve effective beam sidelobe suppression; the method uses a single-bit feedback information to continuously adjust the transmission phase of each transmitting node to increase the received signal strength of the target receiving end and reduce the signal strength of the non-target receiving end, thereby reducing the interference of the sidelobe on the non-target receiving end.

[0037] The present invention provides a distributed beam sidelobe suppression method under static conditions, comprising the following steps:

[0038] Before the start of the iterative feedback process, a random phase disturbance is introduced for each transmitting node. After the phase disturbance is added to the currently known optimal transmission phase, each transmitting node sends a signal; then the receiving node analyzes the received signal strength. If the phase disturbance added this time increases the received signal strength of the target receiving node corresponding to the transmitting node, and at the same time reduces the received signal strength of the non-target receiving node, a single-bit feedback information is used to reflect the signal strength changes of the target receiving node and the non-target receiving node, and the optimal transmission phase is updated according to the feedback information; the optimal transmission phase is gradually found through continuous iteration, and the transmission phase is used to send signals to minimize the interference of side lobes on the target receiving node.

[0039] The specific implementation process of the present invention is described in detail below with reference to the accompanying drawings.

[0040] Step 1: First, establish the transmitting and receiving system model.

[0041] Assume that there are N transmitting nodes and K receiving nodes in the communication system. The N transmitting nodes are randomly distributed in a circular area with a radius of R, and the K receiving nodes are randomly distributed in the far field. Each transmitting node S n There is only a single omnidirectional antenna, and each transmitting node S n The useful information that needs to be sent is m(t); since each transmitting node S n An independent oscillator is used to generate the RF signal, so even after synchronization processing, the phase deviation cannot be completely eliminated, which causes the baseband signal received by the receiving node to have an unknown phase offset γ n ,n=1,2,...,N; use represents the nth transmitting node S n To receiving node B k The complex channel gain of n ≥0 indicates the transmitting node S n To receiving node B k The amplitude gain of the channel, ψ nk represents the phase offset of the channel, then the kth receiving node B k Received from the transmitting node S n The baseband signal r k (t) is expressed as:

[0042]

[0043] Among them, e is a natural constant, j is an imaginary unit, θ n Indicates the phase, The mean is 0 and the variance is The complex Gaussian white noise, then the kth receiving node B kReceived signal strength RSS k (Receivedsignal strength,RSS) is:

[0044]

[0045] In the formula, RSS k Used to measure the distributed beamforming effect; Φ n =γ n +θ n +ψ nk represents the kth receiving node B k Received from the nth transmitting node S n The total phase shift.

[0046] Step 2: Each transmitting node adds a random phase disturbance and starts an iterative feedback process, so that the received signal strength of the target receiving node increases continuously and the received signal strength of the non-target receiving node decreases continuously.

[0047] Step 2.1, when the number of iterations is i, each transmitting node S n Independently generate a perturbation phase δ n [i], where δ n [i] The value of equal probability is +δ 0 or -δ 0 , δ 0 =π / M is the preset value, M is a positive integer; Figure 4 In one embodiment of the present invention, 0 Simulation results for different values.

[0048] Step 2.2, each transmitting node S n The disturbance phase δ generated by each n [i] Add to the currently known optimal transmission phase θ n [i], a new phase value φ is obtained n [i] = θ n [i]+δ n [i]; Each transmitting node S n With this new phase value φ n [i] Collaborative sending.

[0049] The optimal transmission phase θ n [i] is the transmitting node S n In the previous i-1 iterations, the corresponding target receiving node B 0 The signal strength at the location is the largest, while making the remaining non-target receiving nodes B k′ ,k′=1,2,...,K-1 where the signal strength is the smallest; where at the first iteration θn [i] Take θ n .

[0050] Step 2.3, each receiving node B k ,k=1,2,...,K receives data from all transmitting nodes S n After each signal is sent, use Calculate the received signal strength RSS of this iteration k [i], where Φ nk [i] = γ n +ψ nk +φ n [i];

[0051] Then the transmitting node S n The corresponding target receiving node B 0 The received signal strength RSS of this node 0 [i] and the maximum received signal strength value RSS obtained in the previous i-1 iterations best,0 For comparison, if RSS 0 [i]>RSS best,0 , indicating that for the target receiving node B 0 Assume that the random perturbation phase added in step 2.1 is successful, then the target receiving node will feedback 1 bit of information "b" to each transmitting node. 0 [i]=1", and the maximum received signal strength RSS at the target node best,0 Updates to RSS 0 [i]; If RSS 0 [i]≤RSS best,0 , indicating that for the target receiving node B 0 For example, the random perturbation phase added this time failed and reduced the signal gain at the receiving end. Then the target receiving node B 0 It will give each transmitting node feedback 1 bit of information "b 0 [i]=0", and do not update RSS best,0 ;

[0052] Similarly, each non-target receiving node B k′ The received signal strength RSS obtained in this measurement will also be k [i] and the minimum received signal strength value RSS obtained in the previous i-1 iterations min,k For comparison; if RSS k [i]<RSS min,k , each non-target receiving node will feedback 1 bit of information "b k [i]=1", and the minimum received signal strength RSS min,kUpdates to RSS k [i]; If RSS k [i]≥RSS min,k , indicating that the random perturbation phase added this time is a failure, but it enhances the signal gain at the non-desired node. Then each non-target receiving node will feedback 1 bit of information "b" to each transmitting node. k [i]=0", and maintain the minimum received signal strength RSS at the interfering node min,k constant.

[0053] Step 2.4, each transmitting node S n After receiving all receiving nodes B in the i-th iteration k After receiving the feedback information, update the phase value used in the i+1th iteration:

[0054] When each transmitting node S n Received all receiving Node B k Feedback k After the signal [i] = 1”, each transmitting node retains the random perturbation phase added for the i-th time and updates the optimal transmission phase θ n [i+1]=φ n [i] = θ n [i]+δ n [i]; As long as there is a feedback signal "b k [i]=0”, each node will discard the random perturbation phase added for the i-th time, that is, θ n [i+1]=θ n [i].

[0055] At this point, the i-th iteration process is completed, and the n-th transmitting node S n The optimal transmission phase is given by θ n [i] Update to θ n [i+1], start the i+1th iteration; keep repeating the above steps until the received signal strength values ​​of all receiving nodes meet the threshold value expected by the system and the iteration stops.

[0056] Example:

[0057] In one embodiment of the present invention, it is assumed that there are 10 transmitting nodes and 4 receiving nodes in a distributed system, one of which is a target receiving end and the other three are non-target receiving ends. The transmitting nodes are evenly distributed in a circular area with a radius of 10m, and the direction angle of the target receiving end is φ 0 =0°, the direction angles of the non-target receiving end are φ 1 =-30°, φ 2 =30° and φ 0=90°. Each transmitting node has only a single omnidirectional antenna. Assume that each node needs to send useful information m(t) = 1, a n ≥0 indicates the amplitude gain of the channel from each transmitting node to the receiving node, a n =1; the test results of this embodiment are as follows Figure 4 shown.

[0058] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A distributed beam sidelobe suppression method under static conditions, characterized in that: include: Before the start of the iterative feedback process, a random phase disturbance is introduced for each transmitting node. After the phase disturbance is added to the currently known optimal transmission phase, each transmitting node sends a signal; then the receiving node analyzes the received signal strength. If the phase disturbance added this time increases the received signal strength of the target receiving node corresponding to the transmitting node and decreases the received signal strength of the non-target receiving node, a single-bit feedback information is used to reflect the signal strength changes of the target receiving node and the non-target receiving node, and the optimal transmission phase is updated according to the feedback information; the optimal transmission phase is gradually found through continuous iteration, and the transmission phase is used to send signals.

2. The distributed beam sidelobe suppression method under static conditions according to claim 1, characterized in that: The system model of the method is: There are N transmitting nodes and K receiving nodes in the communication system. The N transmitting nodes are randomly distributed in a circular area with a radius of R, and the K receiving nodes are randomly distributed in the far field. Each transmitting node S n There is only a single omnidirectional antenna, and each transmitting node S n The useful information to be sent is m(t); the baseband signal received by the receiving node will have an unknown phase offset γ n ,n=1,2,...,N; use represents the nth transmitting node S n To receiving node B k The complex channel gain of n ≥0 indicates the transmitting node S n To receiving node B k The amplitude gain of the channel, ψ nk represents the phase offset of the channel, e is a natural constant, j is an imaginary unit, θ n Indicates the phase, The mean is 0 and the variance is The complex Gaussian white noise, then the kth receiving node B k Received signal strength RSS k for: In the formula, RSS k Used to measure the distributed beamforming effect; Φ n =γ n +θ n +ψ nk represents the kth receiving node B k Received from the nth transmitting node S n The total phase shift.

3. The distributed beam sidelobe suppression method under static conditions according to claim 1, characterized in that: The step of introducing a random phase disturbance to each transmitting node before the iterative feedback process starts, and adding the phase disturbance to the currently known optimal transmission phase, and then each transmitting node transmits a signal, comprising: Step 2.1, when the number of iterations is i, each transmitting node S n Independently generate a perturbation phase δ n [i], where δ n [i] The value of equal probability is +δ0 or -δ0, δ0 = π / M is the preset value, and M is a positive integer; Step 2.2, each transmitting node S n The generated disturbance phase δ n [i] Add to the currently known optimal transmission phase θ n [i], a new phase value φ is obtained n [i] = θ n [i]+δ n [i]; Each transmitting node S n With this new phase value φ n [i] Conduct collaborative sending; The optimal transmission phase θ n [i] is the transmitting node S n In the previous i-1 iterations, the signal strength at the corresponding target receiving node B0 is maximized, and the signal strength at the remaining non-target receiving nodes B k′ ,k′=1,2,...,the phase where the signal strength is the smallest at K-1.

4. The distributed beam sidelobe suppression method under static conditions according to claim 1, characterized in that: The receiving node analyzes the received signal strength. If the phase disturbance added this time increases the received signal strength of the target receiving node corresponding to the transmitting node, and the received signal strength of the non-target receiving node decreases, a single-bit feedback information is used to reflect the signal strength change of the target receiving node and the non-target receiving node, including: Step 2.3, each receiving node B k ,k=1,2,...,K receives data from all transmitting nodes S n After each signal is sent, use Calculate the received signal strength RSS of this iteration k [i], where Φ nk [i] = γ n +ψ nk +φ n [i]; Then the transmitting node S n The corresponding target receiving node B0 combines the received signal strength RSS0[i] of this node with the maximum received signal strength value RSS obtained in the previous i-1 iterations best,0 For comparison, if RSS0[i]>RSS best,0 , then the target receiving node will feedback 1 bit of information "b0[i] = 1" to each transmitting node, and at the same time, the maximum received signal strength RSS at the target node best,0 Update to RSS0[i]; if RSS0[i]≤RSS best,0 , then the target receiving node B0 will feedback 1 bit of information "b0[i] = 0" to each transmitting node and will not update the RSS best,0 ; Similarly, each non-target receiving node B k′ The received signal strength RSS obtained in this measurement will also be k [i] and the minimum received signal strength value RSS obtained in the previous i-1 iterations min,k For comparison; if RSS k [i]<RSS min,k , each non-target receiving node will feedback 1 bit of information to each transmitting node k [i]=1", and the minimum received signal strength RSS min,k Updates to RSS k [i]; If RSS k [i]≥RSS min,k , then each non-target receiving node will feedback 1 bit of information to each transmitting node"b k [i]=0", and maintain the minimum received signal strength RSS at the interfering node min,k constant.

5. The distributed beam sidelobe suppression method under static conditions according to claim 1, characterized in that: Updating the optimal transmission phase according to the feedback information includes: Step 2.4, each transmitting node S n After receiving all receiving nodes B in the i-th iteration k After receiving the feedback information, update the phase value used in the i+1th iteration: When each transmitting node S n Received all receiving Node B k Feedback k After the signal [i] = 1”, each transmitting node retains the random perturbation phase added for the i-th time and updates the optimal transmission phase θ n [i+1]=φ n [i] = θ n [i]+δ n [i]; As long as there is a feedback signal "b k [i]=0”, each node will discard the random perturbation phase added for the i-th time, that is, θ n [i+1]=θ n [i]; At this point, the i-th iteration process is completed, and the n-th transmitting node S n The optimal transmission phase is given by θ n [i] Update to θ n [i+1], start the i+1th iteration; keep repeating the above steps until the received signal strength values ​​of all receiving nodes meet the threshold value expected by the system and the iteration stops.

6. A communication system, comprising a transmitting node and a receiving node; characterized in that: The communication system performs sidelobe suppression using the distributed beam sidelobe suppression method under static conditions according to any one of claims 1 to 5.

7. A terminal device, comprising a processor, a memory and a computer program stored in the memory; characterized in that: When the processor executes the computer program, it implements the distributed beam sidelobe suppression method under static conditions according to any one of claims 1 to 5.

8. A computer-readable storage medium, wherein a computer program is stored in the medium; characterized in that: When the computer program is executed by a processor, the distributed beam sidelobe suppression method under static conditions according to any one of claims 1 to 5 is implemented.

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