Signal processing method, device and equipment

Abstract

The embodiment of the invention provides a signal processing method, device and equipment. In the embodiment of the invention, an orthogonal frequency division multiplexing (OFDM) frequency domain signal to be sent can be acquired; based on an interference alignment constraint condition, determining a precoding matrix; wherein the interference alignment constraint condition indicates that a first signal component and a second signal component fall into different signal subspaces, the first signal component comprises intra-symbol interference ICI introduced by a current symbol and a desired signal, and the second signal component comprises inter-symbol interference ISI introduced by a previous symbol; and performing pre-coding processing on the OFDM frequency domain signal to be sent based on the pre-coding matrix, generating a pre-coded frequency domain signal, converting the pre-coded OFDM frequency domain signal into an OFDM time domain signal, and sending the OFDM time domain signal to receiving end equipment.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wireless communication, and in particular to a signal processing method, device and equipment. BACKGROUND

[0002] Orthogonal Frequency Division Multiplexing (OFDM) waveform has been widely used in current Integrated Sensing and Communication (ISAC) systems due to its high spectral efficiency and strong anti-multipath interference capability. In order to resist the Inter-Carrier Interference (ICI) and Inter-Symbol Interference (ISI) caused by multipath effect, the related system considers adding a Cyclic Prefix (CP) at the head of the OFDM symbol, where the length of the CP is often assumed to be greater than the length of the Channel Impulse Response (CIR) to completely eliminate ICI and ISI. However, due to the increasingly complex base station networking and sensing environment, the CIR length of the wireless channel between transceivers gradually expands, and when the CIR length is greater than the CP length, the received signal will introduce ICI and ISI, thereby causing a significant decline in the performance of the system sensing.

[0003] The existing OFDM waveform design and signal processing method for the CP insufficient scene mostly focuses on equivalently expanding the CP of the original system until it is greater than the CIR length by constructing the cyclic shift relationship between the front and back halves of the OFDM symbol and between adjacent OFDM symbols, so as to completely eliminate ICI and ISI. However, such a method often needs to sacrifice a large number of symbol Degrees of Freedom (DoF) to suppress the interference, thereby causing a significant decline in the spectral efficiency of the system.

[0004] Therefore, there is an urgent need to provide a processing method for long-distance ISAC signals with high spectral efficiency and low loss of DoF to solve the above problems in the related art. SUMMARY

[0005] The aspects of the present application provide a signal processing method, device and equipment to solve the problem in the related art that a large number of symbol DoF need to be sacrificed to suppress the interference caused by the multipath effect, thereby causing a significant decline in the spectral efficiency of the system.

[0006] The signal processing method provided by the embodiments of the present application is applied to a sending end device, and includes: obtain an orthogonal frequency division multiplexing, OFDM, frequency domain signal to be sent; determine a precoding matrix based on an interference alignment constraint condition, wherein the interference alignment constraint condition indicates that a first signal component and a second signal component fall into different signal subspaces, the first signal component including intra-symbol interference, ICI, introduced by a current symbol and an expected signal, and the second signal component including inter-symbol interference, ISI, introduced by a previous symbol; perform precoding processing on the OFDM frequency domain signal to be sent based on the precoding matrix, generate a precoded frequency domain signal, and convert the precoded OFDM frequency domain signal into an OFDM time domain signal and send the OFDM time domain signal to a receiving end device.

[0007] Embodiments of the present application provide a signal processing method, which is applied to a receiving end device and includes: receive an orthogonal frequency division multiplexing, OFDM, time domain signal, wherein the OFDM time domain signal is a signal processed by a sending end device based on a precoding matrix and transmitted through a channel, and the precoding matrix is determined based on an interference alignment constraint condition and a subcarrier mapping constraint condition; perform time domain channel estimation on the OFDM time domain signal based on a compressed sensing technology, and obtain an estimated value of a channel impulse response, CIR; perform equalization on the OFDM time domain signal based on the estimated value of the CIR using a minimum mean square error, MMSE, criterion, and recover an OFDM frequency domain signal corresponding to the OFDM time domain signal.

[0008] Embodiments of the present application also provide a sending end device, which includes: an obtaining module configured to obtain an orthogonal frequency division multiplexing, OFDM, frequency domain signal to be sent; a determining module configured to determine a precoding matrix based on an interference alignment constraint condition, wherein the interference alignment constraint condition indicates that a first signal component and a second signal component fall into different signal subspaces, the first signal component including intra-symbol interference, ICI, introduced by a current symbol and an expected signal, and the second signal component including inter-symbol interference, ISI, introduced by a previous symbol; a processing module configured to perform precoding processing on the OFDM frequency domain signal to be sent based on the precoding matrix, generate a precoded frequency domain signal, and convert the precoded OFDM frequency domain signal into an OFDM time domain signal and send the OFDM time domain signal to a receiving end device.

[0009] Embodiments of the present application also provide a receiving end device, which includes: receive a Orthogonal Frequency Division Multiplexing, OFDM, time domain signal, the OFDM time domain signal being transmitted from a sending device based on a precoding matrix, the precoding matrix being determined based on an interference alignment constraint and a subcarrier mapping constraint; obtain an estimate of a Channel Impulse Response, CIR, based on the OFDM time domain signal and a compressive sensing technique; equalize the OFDM time domain signal based on the estimate of the CIR and a Minimum Mean Square Error, MMSE, criterion to recover an OFDM frequency domain signal corresponding to the OFDM time domain signal.

[0010] The embodiments of the present application further provide an electronic device, comprising a processor, a memory and a bus, the memory storing machine readable instructions executable by the processor, the processor and the memory communicating through the bus, the machine readable instructions being executed by the processor to perform the steps in the signal processing method provided by the embodiments of the present application.

[0011] The embodiments of the present application further provide a computer readable storage medium storing a computer program, when the computer program is executed by a processor, the processor is caused to implement the steps in the signal processing method provided by the embodiments of the present application.

[0012] The embodiments of the present application further provide a computer program product, the computer program product storing instructions, when the instructions are executed by a computer, the computer implements the steps in the signal processing method provided by the embodiments of the present application.

[0013] The signal processing method applied to the sending device provided by the embodiments of the present application can determine a precoding matrix based on an interference alignment constraint, and perform precoding processing on an OFDM frequency domain signal to be sent, so that the Intra-Symbol Interference, ICI, and the Inter-Symbol Interference, ISI, in the precoding processed frequency domain signal fall into different signal subspaces, without sacrificing time-frequency resources to avoid interference by extending a cyclic prefix, thereby effectively suppressing the ICI and the ISI while maximizing the spectral efficiency and the symbol degree of freedom of the system.

[0014] The signal processing method applied to the receiving end device provided by the embodiment of the present application firstly can receive the OFDM time domain signal transmitted by the sending end device based on the precoding matrix processing and the channel transmission, and the precoding matrix is determined based on the interference alignment constraint condition and the subcarrier mapping constraint condition, which can make the intra-symbol interference ICI and the inter-symbol interference ISI in the frequency domain signal recovered from the OFDM time domain signal fall into different signal subspaces, without sacrificing the time-frequency resource to avoid the interference by extending the cyclic prefix, while effectively suppressing the intra-symbol interference ICI and the inter-symbol interference ISI, the system spectral efficiency and the symbol degree of freedom are maximally reserved. Secondly, the channel estimation method based on the compressed sensing fully utilizes the natural sparse characteristics of the channel impulse response in the time domain, and can reconstruct the channel information with high precision. Finally, the MMSE criterion which can intelligently balance between eliminating the residual interference and suppressing the noise amplification is used for symbol equalization, and the bit error rate performance of the system is effectively improved. BRIEF DESCRIPTION OF DRAWINGS

[0015] The accompanying drawings, which are included to provide a further understanding of the present application, constitute a part of the present application and illustrate the illustrative embodiments of the present application and its description, which are used to explain the present application, and do not constitute improper limitations on the present application. In the drawings: Figure 1 A flowchart of a signal processing method provided for the illustrative embodiment of the present application is shown in the figure; Figure 2 A flowchart of another signal processing method provided for the illustrative embodiment of the present application is shown in the figure; Figure 3 A full flowchart of a signal processing method provided for the illustrative embodiment of the present application is shown in the figure; Figure 4 A structure diagram of a signal processing device provided for the illustrative embodiment of the present application is shown in the figure; Figure 5 A structure diagram of another signal processing device provided for the illustrative embodiment of the present application is shown in the figure; Figure 6 A structure diagram of an electronic device provided for the illustrative embodiment of the present application is shown in the figure. DETAILED DESCRIPTION

[0016] In order to make the purpose, technical scheme and advantages of the present application clearer, the technical scheme of the present application will be described clearly and completely below in combination with the specific embodiments of the present application and the corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0017] The following terms related to the present application are explained: OFDM: Orthogonal Frequency Division Multiplexing. OFDM is actually a kind of MCM (Multi Carrier Modulation). It realizes parallel transmission of high-speed serial data through frequency division multiplexing, has good anti-multipath fading capability, and can support multi-user access. The main idea is to divide the channel into several orthogonal sub-channels, convert the high-speed data signal into parallel low-speed sub-data streams, modulate them on each sub-channel, and transmit them. The orthogonal signals can be separated by using correlation technology at the receiving end, which can reduce the mutual interference (ISI) between sub-channels. The signal on each sub-channel has a bandwidth smaller than the correlation bandwidth of the channel, so it can be considered as a flat fading on each sub-channel, thereby eliminating the inter-symbol interference, and because the bandwidth of each sub-channel is only a small part of the original channel bandwidth, channel equalization becomes relatively easy.

[0018] ICI: Inter-Carrier Interference. In OFDM systems, a high-speed data stream is usually divided into many low-speed data streams, and then each low-speed data stream is modulated on an independent sub-carrier. These sub-carriers are closely arranged in frequency, but in an ideal case, they are "orthogonal" to each other. Orthogonality is the key to understanding ICI. It means that when demodulating a particular sub-carrier, the integral (or dot product) produced by all other sub-carriers at the sampling point of the sub-carrier is exactly zero. It is like in a coordinate system, the X-axis and the Y-axis are orthogonal, and your movement on the X-axis will not affect your coordinates on the Y-axis. ICI refers to the destruction of this ideal orthogonality, resulting in interference from other sub-carrier signals when demodulating a particular sub-carrier.

[0019] ISI: Inter-Symbol Interference. It refers to the overlap of adjacent data symbols in time, causing the receiver to be interfered by previous (or even subsequent) symbols when judging the current symbol.

[0020] CP: Cyclic Prefix. It is a special structure of OFDM symbol in time domain. Its production process includes: first, generate a complete OFDM symbol (containing all sub-carriers, time length T_u, called "useful symbol period"); then, copy the last segment of length T_cp samples at the tail of the OFDM symbol completely; finally, paste the copied segment to the head of the entire OFDM symbol. In this way, a new complete transmission symbol is formed, with a total time length of T_total=T_u+T_cp. The part added to the head and copied from the tail is the cyclic prefix.

[0021] CIR: Channel Impulse Response, which describes the characteristics of a communication channel in time domain. Assuming that an ideal impulse (Dirac delta function) with theoretically infinite short and energy of 1 is input to the channel, the output signal obtained at the output end of the channel is the impulse response of the channel, which is usually represented by h (n) or h (t). h t ) or h τ .

[0022] DoF: Degree of Freedom, which refers to the maximum number of scalar (real or complex) information signals that can be independently and losslessly transmitted in a communication system.

[0023] As described in the background, in order to suppress the ICI and ISI introduced due to the lack of CP, a direct way in the related art is to extend the CP length, however, this method will cause a significant reduction in spectral efficiency. In addition, for some commercial active antenna unit (AAU) devices with underlying physical layer signal processing functions, adding / removing CP and other operations are implemented by hardware and cannot be modified by the device user, so this method is difficult to be compatible with existing communication protocols and hardware architecture. In view of this problem, the related art proposes a half-waveform transmission scheme based on zero-power reference signal, specifically, the scheme activates only half of the subcarriers in the frequency domain in the form of "comb", thereby forming a time-domain waveform with periodicity after inverse fast Fourier transform (IFFT), and then only using the latter half of the OFDM symbol to decode the modulation symbol at the receiving end. Although this method extends the ICI / ISI-free area to 0.5 times the symbol length, however, this method causes the system to lose nearly half of the spectral efficiency.

[0024] ​​Similarly, the related art also proposes a non-ISI / ICI transmission scheme based on multiple consecutive OFDM symbols, specifically, the scheme expands the CP length by designing the frequency domain symbol to make multiple consecutive OFDM symbols sequentially constitute a cyclic shift version of a single OFDM symbol, thereby equivalently expanding the CP length. However, this method actually only carries the valid information of one OFDM symbol within multiple consecutive OFDM symbols, and the system spectral efficiency is low. In order to reduce the loss of spectral efficiency while suppressing ICI and ISI, the related art also proposes a transmit precoding scheme based on the interference alignment theory, however, the precoding method proposed by this scheme only considers the case where the number of communication subcarriers is exactly the same as the number of FFT points of the OFDM system, and cannot be compatible with the existing 5G protocol standard. In addition, there are also related technologies that propose an anti-ICI / ISI method based on signal compensation, the core idea of which is to improve the SINR of the received signal through coherent compensation to optimize the bit error rate performance of the system, however, such a method cannot completely eliminate ICI and ISI, thereby causing a bottleneck in system performance.

[0025] As mentioned earlier, the related art generally has poor standard compatibility, low spectral efficiency, and large loss of degrees of freedom. In view of the shortcomings of the existing scheme, the present application proposes a signal processing method, device and electronic equipment. For the transmitting end, unlike the method of directly expanding the CP length in the related art, the present application performs anti-ICI / ISI precoding on the original frequency domain modulation symbol based on the interference alignment theory, so that the interference signal and the expected signal can cross different subspaces. For the receiving end, first, a time domain channel estimation and target distance extraction scheme based on the compressed sensing theory is proposed; then, a symbol equalization method based on the MMSE criterion is designed based on the channel estimation result. By using the signal processing method provided by the present application, the system ISAC distance can be improved at the cost of a small loss of degrees of freedom, which improves the target detection probability and reduces the communication bit error rate compared with the traditional method.

[0026] Specifically, the OFDM system constructed in the embodiment of the present application defines as the FFT point number, as the OFDM symbol subcarrier number, as the cyclic prefix length, as the number of transmitted OFDM symbols. Assuming that the maximum length of CIR is , the vector representation is: (1) wherein denotes the complex field, denotes the transpose operation. The received time-domain signal vector of the kth (0≤k≤K-1) OFDM symbol can be expressed as: (2) wherein is the time-domain signal vector of the kth symbol, is the time-domain signal vector of the (k-1)th symbol, is a circulant matrix formed by the CIR, and is specifically expressed as: (3) is an ICI matrix, and is specifically expressed as: (4) wherein E=L-V-1. is an ISI matrix, and is specifically expressed as: (5)The specific expression of H I in the formula (3) and (4) is: (6)From the formula (3) and (4), when the cyclic prefix length is greater than the CIR length (i.e. L-1≤V), and are zero matrices, and the received signal does not introduce ICI and ISI, and when the CP length is less than the CIR length (i.e. L-1>V), and are not zero matrices, and the received signal is polluted by ICI and ISI in addition to noise, thereby seriously deteriorating the system performance. In view of this problem, the present application proposes a signal processing method, device and equipment, which can perform precoding processing on the OFDM frequency-domain signal to be transmitted by using the precoding matrix determined based on the interference alignment constraint condition at the sending end equipment side, so that the intra-symbol interference ICI and the inter-symbol interference ISI in the precoding-processed frequency-domain signal fall into different signal subspaces, without sacrificing the time-frequency resources by extending the cyclic prefix to avoid the interference, thereby effectively suppressing the intra-symbol interference ICI and the inter-symbol interference ISI while maximizing the spectral efficiency and the symbol degree of freedom of the system. The technical solutions provided by the embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0027]

[0028] A flowchart of a signal processing method provided by an exemplary embodiment of the present application applied to a sending end equipment is shown in FIG. 1. As shown in FIG. 1, the signal processing method comprises the following steps. Figure 1 Figure 1As shown, the method includes: Step 110: Obtain the frequency domain signal of the Orthogonal Frequency Division Multiplexing (OFDM) to be transmitted.

[0029] The OFDM frequency domain signal to be transmitted is a parallel set of instructions that specifies the amplitude and phase at which each subcarrier should carry information. The OFDM frequency domain signal to be transmitted is a digital vector (a sequence of ordered numbers), where each element corresponds to the information to be transmitted on a subcarrier (a radio wave of a specific frequency). The OFDM frequency domain signal to be transmitted exists before the IFFT (Inverse Fast Fourier Transform) module of the transmitting device and after the FFT (Fast Fourier Transform) module of the receiving device. All data that the transmitting device wants to transmit to the receiving device can be loaded into this OFDM frequency domain signal to be transmitted. Assume the frequency domain vector of the k-th OFDM symbol is... Where 0 ≤ k ≤ K-1, K is the number of transmitted OFDM symbols, and M is the number of OFDM symbol subcarriers. Represents the field of complex numbers. This indicates the transpose operation.

[0030] For example, both the transmitting and receiving devices described in this application can be applied to Integrated Sensing and Communication (ISAC) scenarios where the cyclic prefix length is less than the channel impulse response length. The core idea of ​​ISAC is to enable the same set of wireless network equipment (such as your mobile phone base station) to perform both high-speed communication (making calls and accessing the internet) and, like radar, to sense the surrounding environment (detecting objects, distance, speed, and even shape). ISAC allows communication and radar systems that previously occupied different frequency bands and used different devices to share the same spectrum and the same set of hardware (antennas, chips, etc.), greatly improving resource utilization efficiency and reducing costs and deployment difficulty.

[0031] Step 120: Determine the precoding matrix based on the interference alignment constraint; wherein the interference alignment constraint indicates that the first signal component and the second signal component fall into different signal subspaces, the first signal component includes the intra-symbol interference (ICI) introduced by the current symbol and the desired signal, and the second signal component includes the inter-symbol interference (ISI) introduced by the previous symbol.

[0032] The desired signal is given by equation (2). The first item H in CIRC x k The desired signal refers to the signal that the receiving device wants to obtain and that can be correctly demodulated through simple equalization.

[0033] Assume the precoding matrix is The time domain signal vector of the first OFDM symbol can be expressed as equation (7) as follows: (7) wherein, is an IFFT matrix, and an element of the IFFT matrix is . is a subcarrier mapping matrix. The subcarrier mapping matrix is used to indicate which M subcarriers the M data should be placed in the N subcarriers.

[0034] In some exemplary embodiments, the design criteria of the precoding matrix includes: (i) the intersection between the first signal component and the subspace where the second signal component is located is zero; (ii) the first rank is maximized, the first rank being the rank of the subspace where the first signal component is located; (iii) the second rank is minimized, the second rank being the rank of the subspace where the second signal component is located; (iv) the subcarrier mapping constraint condition is satisfied, the subcarrier mapping constraint condition indicating that the latter half of the OFDM time domain signal generated based on the precoding matrix is zero, and the subcarrier mapping constraint condition being derived from the inequality between the number of system subcarriers and the number of fast Fourier transform (FFT) points.

[0035] In some exemplary embodiments, in order to achieve the premise of satisfying the subcarrier mapping constraint condition while accurately managing the interference with the minimum cost, the embodiments of the present application set the second submatrix to be a zero matrix on the one hand, and set a part of the first submatrix to be a fixed pattern on the other hand, while designing the remaining part of the first submatrix to maximize the use of the remaining entire signal space to carry useful data information in the background where the interference has been successfully isolated. This ensures that while combating interference, the loss of symbol degrees of freedom of the system is minimized, thereby achieving a high spectral efficiency much higher than traditional methods such as extended CP. Specifically, the precoding matrix is determined, including: expressing an equivalent precoding matrix corresponding to the precoding matrix in the form of a block matrix, the equivalent precoding matrix being determined based on the precoding matrix, a subcarrier mapping matrix of the OFDM frequency domain signal to be transmitted, and an inverse fast Fourier transform matrix, the block matrix including a first submatrix corresponding to the first half of the OFDM time domain signal, and a second submatrix corresponding to the second half of the OFDM time domain signal; setting the second submatrix to be a zero matrix to satisfy the subcarrier mapping constraint condition; setting a part of the first submatrix to be a fixed pattern to minimize the rank of the second signal component; ​determining a remaining part of the first sub-matrix, and solving the equivalent precoding matrix satisfying the design criterion based on the remaining part and the fixed pattern part; The precoding matrix is calculated based on the equivalent precoding matrix, a subcarrier mapping matrix of the OFDM frequency domain signal to be transmitted, and an inverse fast Fourier transform matrix.

[0036] Firstly, the equivalent precoding matrix Q is calculated based on a precoding matrix P, a subcarrier mapping matrix I of the OFDM frequency domain signal to be transmitted, and an inverse fast Fourier transform matrix W map IFFT The equivalent precoding matrix Q is determined. For simplifying the symbol representation, the equivalent precoding matrix Q is denoted as formula (8) as follows: (8) Then, the time domain signal vector of the kth symbol can be denoted as formula (9) as follows: (9) Based on the equivalent precoding matrix Q and formula (9), formula (2) can be transformed into formula (10) as follows: (10) If it is defined that then formula (10) can be further transformed into formula (11) as follows: (11) Obviously, the first term in formula (11) contains the desired signal and the ICI component, and the second term contains the ISI introduced by the previous symbol.

[0037] Secondly, the precoding matrix interference alignment constraint condition can be derived.

[0038] Based on the foregoing derivation process, it is known that the embodiment of the application aims to design the equivalent precoding matrix Q so that the "desired signal + ICI component" and the ISI interference span different subspaces, that is, the interference alignment constraint condition is satisfied, which can be denoted as formula (12) as follows: (12) Wherein, span{U} represents a linear space composed of column vectors of the matrix U, and 0 represents a zero vector. At the same time, in order to make the precoding method carry as much communication data as possible and minimize the interference of the ISI on the current symbol, it can be deduced that rank(CQ) is as large as possible, and rank(H ISI Q) is as small as possible, wherein rank(U) represents the rank of the matrix U.

[0039] Then, the subcarrier mapping constraint condition can be derived.

[0040] ​The related art gives an example of precoding matrix satisfying the above requirements, however, the related art only considers the case that the number of active subcarriers M is exactly equal to the number of FFT points N. According to the current 5G New Radio (NR) standard, this assumption often does not hold in practical scenarios. For example, when using a transmission configuration of 30 kHz subcarrier spacing (SCS) and 20 MHz bandwidth, the system subcarrier number is usually designed as M = 12N RB , where N RB = 51 represents the number of resource blocks (RBs). At this time, the FFT point number N is generally set to 1024, 2048 or 4096, obviously M ≠ N. The embodiments of the present application bring additional constraints to the precoding matrix design due to the inequality between the number of subcarriers and the number of FFT points, i.e. the subcarrier mapping constraint condition. Specifically, according to formula (8), the following formula (13) can be obtained: (13) , where, for the sake of simplifying formula (13), define , it can be seen from the above expression that the last row of matrix needs to be a zero matrix (this conclusion comes from the fact that in 5G and other practical systems, not all available subcarriers, i.e. FFT points N, are used for data transmission. The actual number of subcarriers used for data transmission is M, i.e. M < N. This leads to a key result: the last N-M sampling points of the generated time-domain OFDM symbol x k must be zero), i.e. as formula 14: (14) , where, represents the submatrix composed of the first to the first row of matrix . At this point, according to the above discussion, the design criteria of the precoding matrix can be summarized as: (i) , i.e. the intersection between the first signal component and the subspace where the second signal component is located is zero; (ii) , as large as possible, i.e. the first rank is maximized, the first rank is the rank of the subspace where the first signal component is located; (iii) , as small as possible, i.e. the second rank is minimized, the second rank is the rank of the subspace where the second signal component is located; (iv) , i.e. satisfying the subcarrier mapping constraint condition, the subcarrier mapping constraint condition indicates that the latter part of the OFDM time-domain signal generated based on the precoding matrix is zero, and the subcarrier mapping constraint condition is derived from the inequality between the system subcarrier number and the Fast Fourier Transform (FFT) point number.

[0041] Thus, the design criteria (i)~(iv) for the precoding matrix are derived.

[0042] Next, the interference alignment precoding matrix P is determined. Specifically, the equivalent precoding matrix Q corresponding to the precoding matrix P can be expressed in a block matrix form, which includes a first sub-matrix corresponding to the first half of the OFDM time domain signal and a second sub-matrix corresponding to the second half of the OFDM time domain signal.

[0043] Exemplarily, the equivalent precoding matrix Q can be expressed in the following block matrix form: (15) According to the equation (15), the equation (16) can be obtained as follows: (16) The design precoding matrix satisfies the design criterion (iii), as described before, such that is as small as possible, i.e., the second rank is minimized, which can be achieved by According to the equation (15), the following equation (17) can be obtained: (17) And, according to the equation (16), the following equation (18) can be obtained: (18) In some exemplary embodiments, the remaining part of the first sub-matrix is determined, including: determining the null space basis vectors of a matrix associated with the second sub-matrix and the fixed pattern part based on the design criteria (i) and (iv); constructing the remaining part of the first sub-matrix based on the null space basis vectors of the matrix associated with the second sub-matrix and the fixed pattern part.

[0044] Wherein, the null space basis vectors of the matrix associated with the second sub-matrix and the fixed pattern part are determined based on the design criteria (i) and (iv), which can achieve the design of the precoding matrix satisfying both the interference alignment constraint condition and the zero tail constraint condition. And, the remaining part of the first sub-matrix is constructed based on the null space basis vectors of the matrix associated with the second sub-matrix and the fixed pattern part, which can fundamentally satisfy the design criteria (i) and (iv), thereby laying a foundation for maximizing the data carrying capacity.

[0045] Exemplarily, the design precoding matrix satisfies the design criterion (iv). Substituting the equation (15) into the equation (16) can obtain the following equation (19): (19) Wherein, Furthermore, since the time-domain signal must have zero tails, the second submatrix of the equivalent precoding matrix must be a zero matrix. Moreover, to separate interference, the matrix... The column vectors must be located in Within the null space, and the matrix The column vectors must be located in the submatrix Within the null space, therefore, the following equation always holds, i.e. (20) (twenty one) in, Representation matrix The first line to the second line A submatrix formed by rows. According to the above expression, the matrix... The column vectors must be located in Within the null space, and the matrix The column vectors must be located in the submatrix Within the zero space.

[0046] It should be noted that, based on the property that any combination of basis vectors in the null space is naturally orthogonal to the original space, by solving... and The null space basis vectors can be used to determine the null space basis vectors of the matrices associated with the second submatrix and the fixed pattern part, or to fill the null space basis vectors with their linearly independent combinations. and This allows us to construct the remaining part of the first submatrix. At this point, it is easy to verify that the designed equivalent precoding matrix has been successfully constructed. The four design criteria (i) to (iv) of the precoding matrix are satisfied.

[0047] Step 130: Based on the precoding matrix, perform precoding processing on the OFDM frequency domain signal to be transmitted to generate a precoded frequency domain signal, and convert the precoded OFDM frequency domain signal into an OFDM time domain signal and send it to the receiving device.

[0048] Based on the above formula, the precoding matrix can be calculated to obtain: (twenty two) By solving the above equation, the precoding matrix P can be obtained, where, This is a pseudo-inverse operation. Finally, based on the precoding matrix, the OFDM frequency domain signal to be transmitted is precoded to generate the precoded frequency domain signal, and the precoded OFDM frequency domain signal is converted into an OFDM time domain signal and sent to the receiving device. This can be achieved through equations (7) to (9).

[0049] The signal processing method applied to a sending end device provided in the embodiment of the present application can perform precoding processing on the OFDM frequency domain signal to be sent by using the precoding matrix determined based on the interference alignment constraint condition, so that the intra-symbol interference ICI and the inter-symbol interference ISI in the precoding processed frequency domain signal fall into different signal subspaces, without sacrificing the time-frequency resource by extending the cyclic prefix to avoid interference, thereby effectively suppressing the intra-symbol interference ICI and the inter-symbol interference ISI while maximizing the spectral efficiency and symbol degree of freedom of the system.

[0050] Figure 2 A flowchart of a signal processing method provided for the exemplary embodiments of the present application applied to a receiving end device is shown in FIG. 6. As shown in FIG. 6, the method comprises the following steps. Figure 2 Step 210, receiving an orthogonal frequency division multiplexing OFDM time domain signal, the OFDM time domain signal being a signal processed by a sending end device based on a precoding matrix and transmitted through a channel, the precoding matrix being determined based on an interference alignment constraint condition and a subcarrier mapping constraint condition.

[0051] Exemplarily, the sending end device and the receiving end device are applied to an integrated sensing and communication ISAC scenario in which the cyclic prefix length is less than the channel impulse response length.

[0052] After the sending end device performs precoding processing on the original OFDM frequency domain signal based on the interference alignment theory, the interference signal and the expected signal have fallen into different signal subspaces. Correspondingly, the embodiment of the present application first proposes a scheme for extracting the time domain channel estimation and the distance of the sensing target based on the compressed sensing theory at the receiving end device; then, a symbol equalization method based on the MMSE criterion is designed based on the channel estimation result.

[0053] Step 220, performing time domain channel estimation on the OFDM time domain signal based on the compressed sensing technology to obtain an estimated value of the channel impulse response CIR.

[0054] The compressed sensing technology is based on the feature that the signal itself and its transform are sparse, and some random and discontinuous observation samples are performed, and the compressed sensing problem is constructed and solved by using these few and seemingly incomplete observation samples to obtain the estimated value of the CIR.

[0055] First, the received OFDM time domain signal is rewritten, which can be rewritten as formula (23) as follows: (23) Wherein, represents a circulant matrix composed of the data vector , and the specific form is ​(24) The specific form is (25) Wherein, (26) Since the previous symbol of the current symbol (for example, the current symbol is x k or r k , and the corresponding previous symbol is x k-1 or r k-1 ) is unknown, in order to simplify the formula representation, the embodiments of the application combine the ISI and noise parts into one term, and use the symbol to represent.

[0056] In some example embodiments, based on the compressed sensing technology, time domain channel estimation is performed on the OFDM time domain signal to obtain an estimated value of the channel impulse response CIR, including: The time domain vector of the OFDM time domain signal is split into a combined term of the inter-symbol interference ISI and noise part and a product of a cyclic matrix composed of the OFDM time domain signal and the CIR; From the time domain vector of the OFDM time domain signal, a sub-vector from the Lth sampling point to the last sampling point is selected as an observation sample for channel estimation, wherein L is an integer determined based on a compromise between the channel impulse response length and the cyclic prefix length, used to balance the interference suppression and the number of observation samples; The sparse characteristics of the CIR and the vector of the observation sample are used to construct a compressed sensing problem, and the compressed sensing problem is solved to obtain the estimated value of the CIR.

[0057] Specifically, the channel estimation and the distance estimation of the sensing target can be expressed as a compressed sensing problem. According to equations (3) and (4), it is noted that the matrices and only have non-zero elements in the first row to the th row, while the th row to the th row are all zero, that is, the ICI and the ISI only affect the head of the received signal vector . Therefore, a direct channel estimation method is to use only the tail sampling points without ICI / ISI interference for estimation. However, this will reduce the number of available estimation samples, thereby reducing the channel estimation performance. In addition, the upper triangular characteristics of the matrix indicate that the ISI usually gradually weakens over time. In view of this, the embodiments of the application can include sampling points that are less affected by the ISI (which can be determined by simulation effects) in the channel estimation process to improve the channel estimation accuracy. Specifically, there is equation (27) as follows: (27) wherein, , and , the symbol represents the th to the th element of the extraction vector. According to the above analysis, the present embodiment sets to realize the trade-off between the interference power and the number of channel estimation samples, wherein the symbol represents the rounding-up operation. Considering the sparse characteristics of the CIR, the present embodiment introduces the compressive sensing technology to estimate the channel. Specifically, the time-domain channel estimation problem can be expressed as formula (28): (28) wherein and respectively represent the L2 norm and the zero norm of the vector, is a preset channel sparsity level. The sparse signal estimation problem described in formula (27) can be effectively solved by using the orthogonal matching pursuit (OMP) algorithm.

[0058] In addition, in the OFDM-based ISAC system, the radar echo signal model and the communication received signal model are essentially the same. For example, in the mono-static mode, for a target with a distance of d, the echo time delay can be expressed as formula (29): (29) wherein, represents the speed of light.

[0059] In some exemplary embodiments, after obtaining the estimated value of the CIR, the method further comprises: identifying the time-domain index corresponding to one or more non-zero elements in the estimated value of the CIR; converting the time-domain index into a signal propagation time delay based on the system sampling interval; determining the distance of the sensing target based on the mapping relationship between the signal propagation time delay and the distance.

[0060] In this way, it is not necessary to transmit radar signals or design special processing links for the sensing function. It directly "borrows" the intermediate result that will inevitably be produced in the communication process - the channel estimation value (CIR), and can mine the distance of the sensing target from it.

[0061] Specifically, after the discretization processing of the above formula (29), considering that the sampling interval is extremely short in the actual system, it can be assumed that the echo time delay is always approximately an integer multiple of the sampling interval, and then it can be considered that the CIR caused by the target will be in the index (30) The target-induced CIR will present a non-zero element at the position indexed by (29). Wherein, represents a sampling interval. The value of the non-zero element is the echo reflection coefficient. Based on this, the distance of the perceived target can be extracted by recording the non-zero element index in the channel estimation result according to the channel estimation process described above.

[0062] In step 230, based on the estimated value of the CIR, the OFDM time domain signal is equalized using the minimum mean square error (MMSE) criterion to recover the OFDM frequency domain signal corresponding to the OFDM time domain signal.

[0063] In some example embodiments, to solve the problem of stable and accurate signal recovery in a strong interference and noise environment, based on the estimated value of the CIR, the OFDM time domain signal is equalized using the minimum mean square error (MMSE) criterion to recover the OFDM frequency domain signal corresponding to the OFDM time domain signal, including: Based on the estimated value of the CIR, the noise power in the OFDM time domain signal is estimated; The equivalent model after the pre-coding at the transmitting end and the channel transmission is represented as a linear relationship between the equivalent channel matrix and the original frequency domain symbol vector, and a rewritten received signal model is obtained; Based on the equivalent channel matrix and the estimated noise power, an MMSE equalization matrix is constructed, and the processed OFDM time domain signal is operated based on the MMSE equalization matrix to recover the OFDM frequency domain signal corresponding to the OFDM time domain signal.

[0064] Specifically, through the three-level linkage of "accurate noise estimation", "equivalent model reconstruction" and "intelligent MMSE equalization", an adaptive and robust signal recovery closed loop is formed. It effectively converts the anti-interference potential brought by the pre-coding at the transmitting end into real performance gain at the receiving end, and finally realizes high reliable communication and high precision perception in the CP insufficient scene with limited spectrum resources and complex channel environment, providing key receiver technology support for advanced sensing and communication integrated system.

[0065] In some example embodiments, to provide a crucial prior parameter for subsequent high-precision signal processing, based on the estimated value of the CIR, the noise power in the OFDM time domain signal is estimated, including: Based on the observation matrix composed of the observation sample vector, the CIR estimation value and the OFDM time domain signal, the channel estimation residual is determined; Based on the power of the tail sample points of the channel estimation residual, the noise power in the received signal is estimated.

[0066] By exploiting the tail of the least interfered signal after channel estimation, a highly reliable noise power estimate is computed. This estimate is fed as a key "environment sensor" reading to the subsequent MMSE equalizer, enabling it to intelligently adjust its strategy and ultimately achieve optimal, highly reliable signal recovery in a hostile channel full of interference and noise.

[0067] where the residual of channel estimation can be expressed as: (31) Therefore, the noise power can be approximated by the residual: (32) where denotes that the noise power estimate only counts the tail elements of the residual to reduce the impact of ISI on the noise power estimate.

[0068] The received signal model is then rewritten. Specifically, equation (11) can be rewritten as: (33) where denotes the minimum loss of degrees of freedom required for zero-forcing interference. The symbol denotes the 1st column to the column of the matrix.

[0069] Finally, the symbols are equalized based on the MMSE criterion. Let , then according to the MMSE criterion, the symbols can be equalized based on the following equation, i.e. (34) where denotes the average power of the modulation symbols.

[0070] At this point, the method proposed in the present application completes the processes of transmitter anti-ICI / ISI precoding, receiver channel estimation, target distance estimation, and symbol equalization. Figure 3 The full flowchart of the signal processing method provided by the exemplary embodiments of the present application includes: step A deriving a precoding matrix interference alignment constraint condition and deriving a precoding matrix subcarrier mapping constraint condition; step B designing a precoding matrix to satisfy the interference alignment constraint condition and designing a precoding matrix to satisfy the subcarrier constraint condition; and step C acquiring a CIR estimate value based on compressed sensing and acquiring the distance of a sensing target; and step D equalizing symbols based on the MMSE criterion.

[0071] The signal processing method applied to the receiving end device provided in the embodiment of the present application can first receive the OFDM time domain signal transmitted by the sending end device based on the pre-coding matrix processing, and the pre-coding matrix is determined based on the interference alignment constraint condition and the sub-carrier mapping constraint condition, so that the intra-symbol interference ICI and the inter-symbol interference ISI in the frequency domain signal recovered from the OFDM time domain signal fall into different signal subspaces, without sacrificing the time-frequency resources by extending the cyclic prefix to avoid interference, while effectively suppressing the intra-symbol interference ICI and the inter-symbol interference ISI, the spectral efficiency and the symbol degree of freedom of the system are maximally reserved. Secondly, the channel estimation method based on the compressed sensing fully utilizes the natural sparse characteristics of the channel impulse response in the time domain, and can accurately reconstruct the channel information. Finally, the MMSE criterion capable of intelligently balancing the elimination of residual interference and the suppression of noise amplification is used for symbol equalization, effectively improving the bit error rate performance of the system.

[0072] Figure 4 A structure schematic diagram of a sending end device 400 provided for the exemplary embodiment of the present application is shown in the figure. Figure 4 As shown in the figure, the sending end device 400 comprises an acquisition module 410, a determination module 420 and a processing module 430, wherein: The acquisition module 410 is configured to acquire a to-be-sent orthogonal frequency division multiplexing OFDM frequency domain signal. The determination module 420 is configured to determine a pre-coding matrix based on an interference alignment constraint condition, wherein the interference alignment constraint condition indicates that a first signal component and a second signal component fall into different signal subspaces, the first signal component comprises an intra-symbol interference ICI introduced by a current symbol and an expected signal, and the second signal component comprises an inter-symbol interference ISI introduced by a previous symbol. The processing module 430 is configured to perform pre-coding processing on the to-be-sent OFDM frequency domain signal based on the pre-coding matrix, to generate a pre-coded frequency domain signal, and to convert the pre-coded OFDM frequency domain signal into an OFDM time domain signal and send the OFDM time domain signal to a receiving end device.

[0073] The sending end device 400 provided in the embodiment of the present application can perform pre-coding processing on the to-be-sent OFDM frequency domain signal by using the pre-coding matrix determined based on the interference alignment constraint condition, so that the intra-symbol interference ICI and the inter-symbol interference ISI in the pre-coded frequency domain signal fall into different signal subspaces, without sacrificing the time-frequency resources by extending the cyclic prefix to avoid interference, thereby effectively suppressing the intra-symbol interference ICI and the inter-symbol interference ISI, and maximally reserving the spectral efficiency and the symbol degree of freedom of the system.

[0074] Optionally, the design criterion of the pre-coding matrix comprises: (i) the intersection between the subspace of the first signal component and the subspace of the second signal component is zero; (ii) a first rank is maximized, the first rank being the rank of the subspace of the first signal component; (iii) a second rank is minimized, the second rank being the rank of the subspace of the second signal component; (iv) a subcarrier mapping constraint condition is satisfied, the subcarrier mapping constraint condition indicating that the latter half of an OFDM time domain signal generated based on the precoding matrix is zero, the subcarrier mapping constraint condition being derived from the inequality between the number of system subcarriers and the number of fast Fourier transform (FFT) points.

[0075] Optionally, the determining module 420 is specifically configured to: express an equivalent precoding matrix corresponding to the precoding matrix in a form of a block matrix, the equivalent precoding matrix being determined based on the precoding matrix, a subcarrier mapping matrix of the to-be-transmitted OFDM frequency domain signal, and an inverse fast Fourier transform matrix, the block matrix including a first submatrix corresponding to the former half of the OFDM time domain signal and a second submatrix corresponding to the latter half of the OFDM time domain signal; set the second submatrix as a zero matrix to satisfy the subcarrier mapping constraint condition; set a part of the first submatrix as a fixed pattern to minimize the rank of the second signal component; determine a remaining part of the first submatrix, and solve the equivalent precoding matrix satisfying the design criteria based on the remaining part and the fixed pattern part; calculate the precoding matrix based on the equivalent precoding matrix, the subcarrier mapping matrix of the to-be-transmitted OFDM frequency domain signal, and the inverse fast Fourier transform matrix.

[0076] Optionally, the determining module 420 is specifically configured to determine the remaining part of the first submatrix as follows: determine zero space basis vectors of a matrix associated with the second submatrix and the fixed pattern part based on the design criteria (i) and (iv); construct the remaining part of the first submatrix based on the zero space basis vectors of the matrix associated with the second submatrix and the fixed pattern part.

[0077] Optionally, the transmitting end device is applied to an integrated sensing and communication (ISAC) scenario in which a cyclic prefix length is less than a channel impulse response length.

[0078] The transmitting end device 400 can implement Figure 1For details of the method implementation examples, please refer to [link / reference]. Figure 1 The signal processing method of the illustrated embodiment will not be described in detail.

[0079] Figure 5 This is a schematic diagram of the structure of a receiving device 500 provided for an exemplary embodiment of this application. For example... Figure 5 As shown, the receiving device 500 includes: a receiving module 510, an acquisition module 520, and an equalization module 530, wherein: The receiving module 510 is used to receive an orthogonal frequency division multiplexing (OFDM) time-domain signal, wherein the OFDM time-domain signal is a signal processed by the transmitting device based on a precoding matrix and transmitted through a channel, and the precoding matrix is ​​determined based on interference alignment constraints and subcarrier mapping constraints. The acquisition module 520 is used to perform time-domain channel estimation on the OFDM time-domain signal based on compressed sensing technology to obtain the estimated value of the channel impulse response (CIR). The equalization module 530 is used to equalize the OFDM time-domain signal based on the estimated value of the CIR and using the minimum mean square error (MMSE) criterion to recover the OFDM frequency-domain signal corresponding to the OFDM time-domain signal.

[0080] The receiver device 500 provided in this application embodiment firstly receives OFDM time-domain signals transmitted through a channel after the signal is processed by the transmitter device based on a precoding matrix. Since the precoding matrix is ​​determined based on interference alignment constraints and subcarrier mapping constraints, it ensures that intra-symbol interference (ICI) and inter-symbol interference (ISI) in the frequency-domain signal recovered from the OFDM time-domain signal fall into different signal subspaces. This eliminates the need to sacrifice time-frequency resources by extending the cyclic prefix to avoid interference, effectively suppressing ICI and ISI while maximizing the preservation of the system's spectral efficiency and symbol degrees of freedom. Secondly, the channel estimation method based on compressed sensing fully utilizes the natural sparsity of the channel impulse response in the time domain, enabling high-precision reconstruction of channel information. Finally, symbol equalization is performed using the MMSE criterion, which intelligently balances the elimination of residual interference with the suppression of noise amplification, effectively improving the system's bit error rate performance.

[0081] Optionally, when the acquisition module 520 performs time-domain channel estimation on the OFDM time-domain signal based on compressed sensing technology to obtain the estimated value of the channel impulse response (CIR), it is specifically used for: The time-domain vector of the OFDM time-domain signal is split into a product of the cyclic matrix formed by the OFDM time-domain signal and the CIR, as well as a combined term of inter-symbol interference (ISI) and noise. selecting, from a time domain vector of the OFDM time domain signal, a sub-vector from an Lth sampling point to a last sampling point as an observation sample for channel estimation, where L is an integer determined based on a compromise between a channel impulse response length and a cyclic prefix length, for balancing interference suppression and the number of observation samples; constructing a compressed sensing problem by using a sparse characteristic of the CIR and the vector of the observation sample, solving the compressed sensing problem, and obtaining an estimated value of the CIR.

[0082] Optionally, after obtaining the estimated value of the CIR, the apparatus further includes a distance determination module configured to: identify time domain indexes corresponding to one or more non-zero elements in the estimated value of the CIR; convert the time domain indexes into signal propagation time delays based on a system sampling interval; determine a distance of a sensing target based on a mapping relationship between the signal propagation time delays and the distance.

[0083] Optionally, when the equalization module 530 performs equalization on the OFDM time domain signal based on the estimated value of the CIR to recover an OFDM frequency domain signal corresponding to the OFDM time domain signal according to the MMSE criterion, the equalization module 530 is specifically configured to: estimate noise power in the OFDM time domain signal based on the estimated value of the CIR; express an equivalent model after pre-encoding at a sending end and channel transmission as a linear relationship between an equivalent channel matrix and an original frequency domain symbol vector, to obtain a rewritten received signal model; construct an MMSE equalization matrix based on the equivalent channel matrix and the estimated noise power, and perform operation on the processed OFDM time domain signal based on the MMSE equalization matrix to recover the OFDM frequency domain signal corresponding to the OFDM time domain signal.

[0084] Optionally, when the equalization module 530 estimates the noise power in the OFDM time domain signal based on the estimated value of the CIR, the equalization module 530 is specifically configured to: determine a channel estimation residual based on an observation matrix composed of the observation sample vector, the estimated value of the CIR, and the OFDM time domain signal; estimate the noise power in the received signal based on power of tail sampling points of the channel estimation residual.

[0085] Optionally, the receiving end device is applied in an ISAC (Integrated Sensing and Communication) scenario in which a cyclic prefix length is less than a channel impulse response length.

[0086] The receiving end device 500 can implement the method of the method embodiment of Figures 2-3 , and details can be referred to the foregoing method embodiment.Figures 2-3 The signal processing method of the embodiment is not described again.

[0087] Figure 6 A structural schematic diagram of an electronic device is provided for the exemplary embodiments of the present application. As shown, the device includes a memory 61 and a processor 62. Figure 6

[0088] The memory 61 is configured to store computer programs and can be configured to store other various data to support operations on the computing device. Examples of the data include instructions of any application program or method for operating on the computing device, contact data, phonebook data, messages, images, videos, etc.

[0089] The processor 62 is coupled to the memory 61 and is configured to execute the computer programs in the memory 61 to: acquire an orthogonal frequency division multiplexing (OFDM) frequency domain signal to be transmitted; determine a precoding matrix based on an interference alignment constraint condition, wherein the interference alignment constraint condition indicates that a first signal component and a second signal component fall into different signal subspaces, the first signal component includes intra-symbol interference (ICI) introduced by a current symbol and an expected signal, and the second signal component includes inter-symbol interference (ISI) introduced by a previous symbol; perform precoding processing on the OFDM frequency domain signal to be transmitted based on the precoding matrix to generate a precoded frequency domain signal, and convert the precoded OFDM frequency domain signal into an OFDM time domain signal and transmit the OFDM time domain signal to a receiving end device; or receive an OFDM time domain signal, wherein the OFDM time domain signal is a signal processed by a transmitting end device based on a precoding matrix and transmitted through a channel, the precoding matrix is determined based on an interference alignment constraint condition and a subcarrier mapping constraint condition; perform time domain channel estimation on the OFDM time domain signal based on a compressed sensing technology to acquire an estimated value of a channel impulse response (CIR); and perform equalization on the OFDM time domain signal based on the estimated value of the CIR using a minimum mean square error (MMSE) criterion to recover an OFDM frequency domain signal corresponding to the OFDM time domain signal.

[0090] The electronic device provided by the embodiments of the present application can perform precoding processing on the OFDM frequency domain signal to be transmitted based on the precoding matrix determined based on the interference alignment constraint condition, so that the intra-symbol interference (ICI) and the inter-symbol interference (ISI) in the precoded frequency domain signal fall into different signal subspaces, without sacrificing time-frequency resources to avoid interference by extending the cyclic prefix, thereby effectively suppressing the intra-symbol interference (ICI) and the inter-symbol interference (ISI) while maximizing the spectral efficiency and symbol freedom of the system.

[0091] ​The electronic device provided by the embodiments of the present application can first receive an OFDM time domain signal transmitted by a sending device based on a precoding matrix processed signal via a channel. The precoding matrix is determined based on an interference alignment constraint condition and a subcarrier mapping constraint condition, so that the in-symbol interference ICI and the inter-symbol interference ISI in the frequency domain signal recovered from the OFDM time domain signal fall into different signal subspaces. The interference can be avoided without sacrificing time-frequency resources by extending the cyclic prefix. The in-symbol interference ICI and the inter-symbol interference ISI are effectively suppressed, and the spectral efficiency and symbol degree of freedom of the system are maximally reserved. Second, the channel estimation method based on compressed sensing fully utilizes the natural sparse characteristics of the channel impulse response in the time domain, and can accurately reconstruct the channel information. Finally, the MMSE criterion that can intelligently balance the elimination of residual interference and the suppression of noise amplification is used for symbol equalization, effectively improving the bit error rate performance of the system.

[0092] Further, as shown in Figure 6 , the electronic device further includes a communication component 63, a display 64, a power supply component 65, an audio component 66, and other components. Figure 6 Some components are only schematically shown in the electronic device, and it does not mean that the electronic device only includes Figure 6 the components shown. In addition, according to different implementation forms of the traffic playback device, Figure 6 the components in the dashed box are optional components, not mandatory components. For example, when the electronic device is implemented as a terminal device such as a smartphone, a tablet computer, or a desktop computer, it can include Figure 6 the components in the dashed box; when the electronic device is implemented as a server device such as a conventional server, a cloud server, a data center, or a server array, it can not include Figure 6 the components in the dashed box.

[0093] Correspondingly, the embodiments of the present application also provide a computer readable storage medium storing a computer program, which is executed by a processor to enable the processor to implement the steps in the above signal processing method embodiments.

[0094] The communication component in the above Figure 6 is configured to facilitate wired or wireless communication between the device where the communication component is located and other devices. The device where the communication component is located can access a wireless network based on a communication standard, such as WiFi, 2G or 3G, or a combination thereof. In an example embodiment, the communication component receives a broadcast signal or broadcast related information from an external broadcast management system via a broadcast channel. In an example embodiment, the communication component can also include a near field communication (NFC) module, a radio frequency identification (RFID) technology, an infrared data association (IrDA) technology, an ultra wide band (UWB) technology, a Bluetooth (BT) technology, etc.

[0095] The memory in the above-described Figure 6 may be implemented by any class of volatile or nonvolatile storage devices, or a combination thereof, such as a Static Random Access Memory (SRAM), an Electrically Erasable Programmable Read-Only Memory (EEPROM), a flash memory, a Programmable Read-Only Memory (PROM), a Read-Only Memory (ROM), a magnetic storage, a disk or a compact disk.

[0096] The display in the above-described Figure 6 includes a screen, which can include a Liquid Crystal Display (LCD) and a Touch Panel (TP). If the screen includes a touch panel, the screen can be implemented as a touch screen to receive an input signal from a user. The touch panel includes one or more touch sensors to sense a touch, a slide and a gesture on the touch panel. The touch sensor can not only sense a boundary of a touching or a sliding action, but also detect duration and pressure related to the touching or sliding action.

[0097] The power component in the above-described Figure 6 supplies power to various components of the device in which the power component is located. The power component can include a power management system, one or more power sources, and other components associated with generating, managing and distributing power for the device in which the power component is located.

[0098] The audio component in the above-described Figure 6 may be configured to output and / or input audio signals. For example, the audio component includes a microphone (MIC) configured to receive an external audio signal when the device in which the audio component is located is in an operation mode such as a call mode, a recording mode and a voice recognition mode. The received audio signal can be further stored in the memory or transmitted via the communication component. In some embodiments, the audio component also includes a speaker to output audio signals.

[0099] Those skilled in the art will appreciate that embodiments of the present application can be provided as methods, systems or computer program products. Accordingly, the present application can be embodied in the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application can be embodied in the form of a computer program product on one or more computer available storage media (including, but not limited to, disk memory, CD-ROMs, optical storage media, etc.) having computer usable program code embodied therein.

[0100] The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks. Figure 1 one or more flowcharts and / or blocks Figure 1 means for functionally implementing the steps listed in the flowchart block or blocks.

[0101] These computer program instructions can also be stored in a computer readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer readable memory produce an article of manufacture including instructions which implement the function specified in the flowchart block or blocks. Figure 1 one or more flowcharts and / or blocks Figure 1 means for functionally implementing the steps listed in the flowchart block or blocks.

[0102] The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks. Figure 1 one or more flowcharts and / or blocks Figure 1 means for functionally implementing the steps listed in the flowchart block or blocks.

[0103] In one typical configuration, the computing device includes one or more processors (CPUs), input / output interfaces, network interfaces, and memory.

[0104] The memory can include non-persistent memory and / or persistent memory, such as flash memory, read-only memory (ROM), and / or volatile or non-volatile random access memory (RAM), among others. The memory is an example of computer readable media.

[0105] Computer-readable media includes permanent and non-permanent, movable and non-movable media that can implement information storage by any method or technology. The information can be computer-readable instructions, data structures, program modules or other data. Examples of computer storage media include, but are not limited to, phase-change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other categories of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, compact disc read-only memory (CD-ROM), digital versatile disc (DVD) or other optical storage, magnetic cassette, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other non-transmission medium that can be used to store information accessible to a computing device. According to the definition herein, computer-readable media does not include transitory media such as modulated data signals and carriers.

[0106] It should also be noted that the terms "comprising", "containing", or any other variant thereof are intended to cover a non-exclusive inclusion, such that a process, method, article or apparatus that comprises a list of elements does not only include those elements, but can also include other elements not expressly listed or inherent to such process, method, article or apparatus. Without more limitations, the element defined by the statement "comprising a" does not exclude the presence of additional identical elements in the process, method, article or apparatus that includes the element.

[0107] The above only describes the embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. within the spirit and principle of the present application shall be included in the scope of claims of the present application.

Claims

1. A signal processing method, characterized by, The method is applied to a sending end device, and comprises: obtaining an orthogonal frequency division multiplexing (OFDM) frequency domain signal to be sent; determining a precoding matrix based on an interference alignment constraint condition, wherein the interference alignment constraint condition indicates that a first signal component and a second signal component fall into different signal subspaces, the first signal component comprises an inter-symbol interference (ICI) introduced by a current symbol and an expected signal, and the second signal component comprises an inter-symbol interference (ISI) introduced by a previous symbol; performing precoding processing on the OFDM frequency domain signal to be sent based on the precoding matrix to generate a precoded frequency domain signal, and converting the precoded OFDM frequency domain signal into an OFDM time domain signal and sending the OFDM time domain signal to a receiving end device.

2. The method of claim 1, wherein, The design criteria of the precoding matrix comprise: (i) an intersection between the first signal component and the second signal component is zero; (ii) a first rank is maximized, the first rank being a rank of the first signal component; (iii) a second rank is minimized, the second rank being a rank of the second signal component; (iv) a subcarrier mapping constraint condition is satisfied, the subcarrier mapping constraint condition indicating that a latter half of the OFDM time domain signal generated based on the precoding matrix is zero, and the subcarrier mapping constraint condition being derived from a system subcarrier number being different from a fast Fourier transform (FFT) point number.

3. The method of claim 2, wherein, Determining the precoding matrix comprises: expressing an equivalent precoding matrix corresponding to the precoding matrix as a block matrix form, the equivalent precoding matrix being determined based on the precoding matrix, a subcarrier mapping matrix of the OFDM frequency domain signal to be sent, and an inverse fast Fourier transform (IFFT) matrix, the block matrix comprising a first submatrix corresponding to a former half of the OFDM time domain signal and a second submatrix corresponding to a latter half of the OFDM time domain signal; setting the second submatrix as a zero matrix to satisfy the subcarrier mapping constraint condition; setting a part of the first submatrix as a fixed pattern to minimize the rank of the second signal component; determining a remaining part of the first submatrix, and solving the equivalent precoding matrix satisfying the design criteria based on the remaining part and the fixed pattern part; calculating the precoding matrix based on the equivalent precoding matrix, the subcarrier mapping matrix of the OFDM frequency domain signal to be sent, and the inverse fast Fourier transform (IFFT) matrix.

4. The method of claim 3, wherein, Determining the remaining part of the first submatrix comprises: determining zero space basis vectors of a matrix associated with the second submatrix and the fixed pattern part based on the design criteria (i) and (iv); constructing the remaining part of the first submatrix based on the zero space basis vectors of the matrix associated with the second submatrix and the fixed pattern part.

5. A signal processing method characterized by, The method is applied to a receiving end device, and comprises: receiving an orthogonal frequency division multiplexing (OFDM) time domain signal, the OFDM time domain signal being a signal processed by a sending end device based on a precoding matrix and transmitted through a channel, and the precoding matrix being determined based on an interference alignment constraint condition and a subcarrier mapping constraint condition. perform time-domain channel estimation on the OFDM time-domain signal based on a compressed sensing technology to obtain an estimated value of a channel impulse response (CIR); perform equalization on the OFDM time-domain signal based on the estimated value of the CIR by using a minimum mean square error (MMSE) criterion to recover an OFDM frequency-domain signal corresponding to the OFDM time-domain signal.

6. The method of claim 5, wherein, perform time-domain channel estimation on the OFDM time-domain signal based on a compressed sensing technology to obtain an estimated value of a channel impulse response (CIR), including: splitting a time-domain vector of the OFDM time-domain signal into a combined term of a product of a circulant matrix composed of the OFDM time-domain signal and the CIR and an inter-symbol interference (ISI) and noise part; selecting, from the time-domain vector of the OFDM time-domain signal, a sub-vector from an Lth sampling point to a last sampling point as an observation sample for channel estimation, where L is an integer determined based on a compromise between a channel impulse response length and a cyclic prefix length, and is used to balance interference suppression and the number of observation samples; constructing a compressed sensing problem by using a sparse characteristic of the CIR and the observation sample vector, solving the compressed sensing problem, and obtaining the estimated value of the CIR.

7. The method of claim 6, wherein, After obtaining the estimated value of the CIR, the method further includes: identifying time-domain indexes corresponding to one or more non-zero elements in the estimated value of the CIR; converting the time-domain indexes into signal propagation time delays based on a system sampling interval; determining a distance of a sensing target based on a mapping relationship between the signal propagation time delays and distances.

8. The method of claim 5, wherein, perform equalization on the OFDM time-domain signal based on the estimated value of the CIR by using a minimum mean square error (MMSE) criterion to recover an OFDM frequency-domain signal corresponding to the OFDM time-domain signal, including: estimating noise power in the OFDM time-domain signal based on the estimated value of the CIR; expressing an equivalent model after precoding at a sending end and channel transmission as a linear relationship between an equivalent channel matrix and an original frequency-domain symbol vector to obtain a rewritten received signal model; constructing an MMSE equalization matrix based on the equivalent channel matrix and the estimated noise power, and performing operation on the processed OFDM time-domain signal based on the MMSE equalization matrix to recover the OFDM frequency-domain signal corresponding to the OFDM time-domain signal.

9. The method of claim 8, wherein, estimating noise power in the OFDM time-domain signal based on the estimated value of the CIR, including: determining a channel estimation residual based on an observation matrix composed of the observation sample vector, the estimated value of the CIR, and the OFDM time-domain signal; estimating noise power in the received signal based on power of tail sampling points of the channel estimation residual.

10. The method of any one of claims 1-9, wherein, The sending end device and the receiving end device are applied to an integrated sensing and communication (ISAC) scene in which a cyclic prefix length is less than a channel impulse response length.

Images