Data transmission method, communication node, and computer-readable storage medium

Abstract

Provided in the present application are a data transmission method, a communication node, and a computer-readable storage medium. The data transmission method comprises: acquiring a first symbol and a rotation angle, wherein the first symbol comprises a pilot symbol and a data symbol; rotating the first symbol on the basis of the rotation angle, so as to obtain a second symbol; and sending the second symbol.

Description

Data transmission method, communication node and computer readable storage medium TECHNICAL FIELD

[0001] The present application relates to the technical field of communication, in particular to a data transmission method, a communication node and a computer readable storage medium. BACKGROUND

[0002] In the face of massive connection scenarios, a data scheduling-free transmission technology is proposed. The scheduling-free transmission can allow terminals to send data autonomously without sending a scheduling request to a base station and waiting for dynamic scheduling of the base station. Therefore, the scheduling-free transmission can reduce signaling overhead and transmission delay, and can also reduce terminal power consumption. In addition, it can be combined with a non-orthogonal multiple access technology to improve the number of access users.

[0003] The scheduling-free transmission includes two schemes, preconfigured scheduling-free and contention scheduling-free. For contention scheduling-free transmission, when a terminal has traffic arrival, it can randomly select transmission-related resources, including time-frequency resources, pilots, spreading sequences, etc. to perform contention access and transmission. Since there is no coordination of the base station, multiple terminals can select the same pilot, i.e., pilot collision occurs, and the base station has difficulty in separating and demodulating the signals of the pilot collision users, resulting in reduced system performance. SUMMARY

[0004] Embodiments of the present application provide a data transmission method, a communication node and a computer readable storage medium.

[0005] In a first aspect, embodiments of the present application provide a data transmission method applied to a first communication node, comprising: obtaining a first symbol and a rotation angle, the first symbol including a pilot symbol and a data symbol; rotating the first symbol according to the rotation angle to obtain a second symbol; and transmitting the second symbol.

[0006] In a second aspect, embodiments of the present application provide a data transmission method applied to a second communication node, comprising: receiving a multi-user superimposed second symbol, the second symbol including a pilot symbol and a data symbol; detecting the data symbol based on the pilot symbol to obtain user data; reconstructing a second symbol of a user based on the user data; and performing interference cancellation on the multi-user superimposed second symbol based on the reconstructed second symbol of the user.

[0007] In a third aspect, embodiments of the present application provide a communication node, comprising: a memory and a processor, the memory storing a computer program, and the processor implementing the data transmission method provided by the first aspect or the second aspect of the embodiments of the present application when executing the computer program.

[0008] In a fourth aspect, an embodiment of the present application provides a computer readable storage medium, the storage medium storing a computer program, and the computer program, when executed by a processor, implements the data transmission method provided in the first aspect or the second aspect of the embodiments of the present application.

[0009] The technical scheme provided by the embodiments of the present application obtains a first symbol and a rotation angle, the first symbol includes a pilot symbol and a data symbol, rotates the first symbol according to the rotation angle to obtain a second symbol, and transmits the second symbol. The first symbol is rotated by the rotation angle, so that it is easier to separate and demodulate the pilot collision user signal, the number of users supported by the scheduling-free transmission system is improved, and the system performance is improved. BRIEF DESCRIPTION OF DRAWINGS

[0010] FIG. 1 is a constellation diagram of a data symbol transmitted by user 1 in a conventional scheme;

[0011] FIG. 2 is a constellation diagram of a data symbol transmitted by user 2 in a conventional scheme;

[0012] FIG. 3 is a constellation diagram of multi-user superimposed data symbols obtained after channel equalization in a conventional scheme;

[0013] FIG. 4 is another constellation diagram of multi-user superimposed data symbols obtained after channel equalization in a conventional scheme;

[0014] FIG. 5 is a constellation diagram of a data symbol transmitted by user 1 according to an embodiment of the present application;

[0015] FIG. 6 is a constellation diagram of a data symbol transmitted by user 2 according to an embodiment of the present application;

[0016] FIG. 7 is a constellation diagram of multi-user superimposed data symbols obtained after channel equalization according to an embodiment of the present application;

[0017] FIG. 8 is a constellation diagram of a data symbol of user 2 after interference cancellation according to an embodiment of the present application;

[0018] FIG. 9 is a flowchart of a data transmission method according to an embodiment of the present application;

[0019] FIG. 10 is another flowchart of a data transmission method according to an embodiment of the present application;

[0020] FIG. 11 is a comparison diagram of simulation results between a data transmission scheme according to an embodiment of the present application and a conventional data transmission scheme;

[0021] FIG. 12 is a structural diagram of a data transmission apparatus according to an embodiment of the present application;

[0022] FIG. 13 is another structure diagram of a data transmission apparatus according to an embodiment of the present application;

[0023] FIG. 14 is a structure diagram of a communication node according to an embodiment of the present application. DETAILED DESCRIPTION

[0024] In the grant-free transmission, when a service arrives, the terminal can randomly select a pilot sequence from a pilot sequence set, and then send the selected pilot sequence together with data to the base station. Since the terminal randomly selects the pilot sequence without the coordination of the base station, multiple terminals can select the same pilot sequence, i.e., pilot collision occurs. Since the base station does not know which users are transmitting data, the base station needs to detect the pilot to identify active users and channel estimation. Due to pilot collision, multiple pilot collision terminals are identified by the base station as only one terminal, so it is difficult to separate and demodulate the data of multiple pilot collision terminals. The terminal can refer to a terminal device, a user, a user equipment (UE), a transmitter, a user terminal, a mobile device, etc. The base station can refer to a base station, a receiver, a relay station or an access point, etc. for communication with the terminal. The pilot can refer to a pilot sequence, a pilot symbol, a reference signal, a preamble or a random access signal, etc.

[0025] In the conventional grant-free transmission scheme, since users are allowed to transmit data on the same time-frequency resource, the multi-user superimposed pilot symbols received by the base station can be represented by the following formula (1):

[0026] where h k represents a wireless channel between user k and the base station, p k represents the pilot symbol transmitted by user k, i.e., the pilot sequence randomly selected by user k from the pilot sequence set P; y p represents the pilot symbol superimposed by K users received by the base station; and n p represents noise, such as additive white Gaussian noise (AWGN).

[0027] The multi-user superimposed data symbols received by the base station can be represented by the following formula (2):

[0028] where s k represents the data symbol transmitted by user k; y d represents the data symbol superimposed by K users received by the base station; and n d represents noise, such as additive white Gaussian noise (AWGN).

[0029] In the grant-free transmission, since the base station does not know which users are currently accessing and transmitting data, the base station can complete active user detection and channel estimation by detecting the pilot, and then perform channel equalization and subsequent multi-user data separation and demodulation. The base station can use a pilot sequence set P to receive the pilot symbol y p to perform active user detection and channel estimation. Assuming ideal channel estimation is adopted, that is, the channel estimation is The data symbol after channel equalization can be represented by the following formula (3):

[0030] If maximum ratio combining (MRC) is adopted, then If minimum mean-square error (MMSE) equalization is adopted, then where σ is the noise variance, and I is the unit matrix; other receiving algorithms or channel equalization algorithms can also be adopted, such as maximum likelihood estimation (MLE) algorithm, zero forcing (ZF) algorithm, etc. Then the base station performs designated processing on to complete multi-user detection. The processing includes at least one of the following: despreading, demapping, demodulation, descrambling, deinterleaving, and decoding, etc.

[0031] Taking MRC combining as an example, considering pilot collision, taking user 1 and user 2 selecting the same pilot sequence p1 as an example, formula (1) can be converted to formula (4): y p = h1p1 + h2p1 + … + h K p K +n p Formula (4)

[0032] Then the ideal channel estimation is that is, the base station obtains the sum channel of user 1 and user 2 as h1+h2. According to formula (3) for channel equalization, the data symbol of user 1 and user 2 superposition is obtained, and the base station may fail to demodulate both user 1 and user 2.

[0033] In order to simplify the analysis, taking 2 pilot collision users transmitting data at the same time as an example. User 1 and user 2 select the same pilot sequence p1, and the base station receives the pilot symbol of user 1 and user 2 superposition as: y p = h1p1 + h2p1 + n p Formula (5)

[0034] The base station receives the superimposed data symbols of user 1 and user 2 as: y d = h1s1 + h2s2 + n d Equation (6)

[0035] Wherein, s1 and s2 are respectively the data symbols sent by user 1 and user 2, i.e. the data symbols obtained after user 1 and user 2 respectively perform a specified processing on the data bits to be sent. The processing includes at least one of the following: encoding, interleaving, scrambling, modulation, mapping and spreading, etc.

[0036] Taking BPSK modulation as an example, the constellation diagram corresponding to the BPSK modulated data symbol s1 sent by user 1 is shown in Fig. 1, and the constellation diagram corresponding to the BPSK modulated data symbol s2 sent by user 2 is shown in Fig. 2. Due to pilot collision, the base station detects the received pilot symbol y p , and can only identify the pilot sequence p1, i.e. the base station considers that there is only one active user, and the ideal channel estimation is The data symbol after channel equalization can be expressed as:

[0037] Wherein, a and b are positive real numbers, and n' represents noise.

[0038] Equation (7) is applicable to MRC combining and MMSE equalization algorithm. In addition, the above description is only an example of ideal channel estimation, and the above scheme is also applicable to actual channel estimation.

[0039] The data symbol after MRC combining can be expressed as:

[0040] Suppose that the channel correlation of user 1 and user 2 is relatively low, i.e. the third and fourth terms of equation (8) are relatively small, and the third and fourth terms are ignored, equation (8) can be approximately expressed as:

[0041] It can be seen that due to pilot collision, the data symbol after channel equalization is the superposition of the data symbols of the pilot collision users.

[0042] Or, the third and fourth terms in equation (8) are regarded as interference terms, i.e. equation (8) can be approximately expressed as:

[0043] Wherein, n represents interference and noise.

[0044] Taking an additive white Gaussian noise channel as an example, if the base station receives data of user 1 and user 2 with equal power, a constellation diagram of superimposed data symbols of user 1 and user 2 after channel equalization is shown in FIG. 3, wherein a grid area in FIG. 3 represents an influence of noise on superimposed constellation points. With the constellation coordinate axis as a boundary, the superimposed constellation points are more likely to cross the boundary after being influenced by the noise, thereby affecting demodulation and decoding. If there is a power difference between user 1 and user 2, i.e., a near-far effect, a constellation diagram of superimposed data symbols of user 1 and user 2 after channel equalization is shown in FIG. 4. As can be seen from FIG. 4, on the one hand, a Euclidean distance between the middle two superimposed constellation points is reduced; on the other hand, the superimposed constellation points are more likely to cross the boundary after being influenced by the noise, which is not conducive to subsequent demodulation and decoding.

[0045] As can be seen from the above analysis, for the pilot collision users, the traditional scheduling-free transmission scheme has problems such as a reduction in a Euclidean distance between superimposed constellation points after channel equalization, a superimposed constellation point being more likely to cross a boundary after being influenced by noise, and the like, thereby affecting the base station in separating and demodulating signals of the pilot collision users and reducing system performance.

[0046] Therefore, the technical scheme provided by the embodiments of the present application aims to solve the above technical problems. Next, the principle of the technical scheme provided by the embodiments of the present application is introduced:

[0047] By observing the superimposed constellation diagrams after channel equalization in FIG. 3 and FIG. 4, the constellation diagram at the transmitting end can be rotated to overcome the problems such as a reduction in a Euclidean distance between superimposed constellation points after multi-user superposition, and a superimposed constellation point being more likely to cross a boundary after being influenced by noise. Taking two pilot collision users as an example, it is assumed that the constellation diagram of user 1 is not rotated, or is rotated by 0 degrees, i.e., a data symbol s1 of user 1 is multiplied by e j0 (or 1) to obtain a rotated data symbol s1e j0 of user 1 for transmission, as shown in FIG. 5; and a data symbol or constellation diagram of user 2 is rotated by 90 degrees (or π / 2), i.e., a data symbol s2 of user 2 is multiplied by (or j) to obtain a rotated data symbol s2e of user 2 for transmission, as shown in FIG. 6.

[0048] The superimposed pilot symbols of user 1 and user 2 received by the base station can be represented by formula (5), and the superimposed data symbols of user 1 and user 2 received by the base station can be represented as:

[0049] It is still assumed that ideal channel estimation is adopted, and the data symbol after MRC combination can be represented as

[0050] The constellation diagram corresponding to the combined data symbol of the MRC is shown in FIG. 7. As shown in FIG. 7, the Euclidean distance between the constellation points in the superimposed constellation diagram of user 1 and user 2 does not decrease, and the constellation points are not prone to border crossing after being affected by noise. When demodulating user 1, the base station can directly demodulate the information of user 1 with the interference of user 2. The constellation diagram shown in FIG. 7 is more likely to correctly demodulate the information of user 1 than the constellation diagrams shown in FIG. 3 and FIG. 4, and then the information of user 1 is removed through interference cancellation to obtain the data symbol of user 2 As shown in FIG. 8. Through the data symbol The rotation angle of user 2 is estimated to be 90 degrees (or π / 2), and the data symbol of user 2 is rotated by -90 degrees (or -π / 2), that is, the data symbol is multiplied by to obtain a conventional BPSK modulation constellation diagram, and the information of user 2 can be demodulated.

[0051] The above is only described by taking 2-pilot collision users as an example. In the same time-frequency resource, the number of users simultaneously transmitting data is not limited, and the number of pilot collision users is also not limited. For example, K (K is greater than or equal to 2) users simultaneously transmit data in the same time-frequency resource, and at least 2 users' pilots collide, and the pilots of the remaining users do not collide. For another example, the pilots of user 1 and user 2 collide, and the pilots of user 3 to user K do not collide, that is, the superimposed pilot symbols of multiple users are shown in formula (4). For another example, the pilots of user 1 and user 2 collide, and the pilots of user 3 and user 4 collide, and the pilots of user 5 to user K do not collide. For another example, the pilots of user 1, user 2 and user 3 collide, and the pilots of user 4 to user K do not collide, and the present application does not limit this.

[0052] Next, the data transmission scheme provided by the present application is specifically introduced, and specifically:

[0053] FIG. 9 is a flowchart of a data transmission method provided by an embodiment of the present application, which is applied to a first communication node. The first communication node can be a data sending end in a network, and can be a node using a contention resource for uplink unscheduled data transmission, such as a user, a UE, a terminal, a transmitter or a mobile device. As shown in FIG. 9, the method can include the following steps:

[0054] S901, obtaining a first symbol and a rotation angle, the first symbol including a pilot symbol and a data symbol.

[0055] In the unscheduled transmission, when there is a service to be sent, the first communication node can perform specified processing on the to-be-sent data bits to form a to-be-sent data symbol. The processing includes at least one of the following: encoding, interleaving, scrambling, modulation, mapping and spreading.

[0056] Optionally, the modulation mode can be a modulation mode with a linear constellation diagram, such as binary phase shift keying (BPSK), M-ary pulse amplitude modulation (PAM), quadrature amplitude modulation (QAM), and the like.

[0057] Optionally, the pilot symbol can be a demodulation reference signal (DMRS), a sparse pilot sequence, a pseudo-random code sequence (PN sequence), an M sequence, a Gold sequence, a Zadoff-Chu sequence, and the like. The first communication node can randomly select a pilot sequence or a pilot symbol from a pilot sequence set.

[0058] The pilot symbol and the data symbol together constitute a first symbol to be sent by the user.

[0059] Optionally, the data to be sent can include at least one of the following: service data, user identification, pilot information, and rotation angle information.

[0060] Optionally, the rotation angle is used to rotate the first symbol, and the rotation angle can be obtained in at least one of the following ways: randomly obtaining a rotation angle from a rotation angle set; and determining a rotation angle from the rotation angle set according to rotation angle information.

[0061] The rotation angle set can include N rotation angles, where N is an integer greater than or equal to 2. Optionally, the value range of the rotation angle set can be [-π / 2, π / 2], [0, π / 2], [-π / 2, 0], or other value ranges, and the embodiments of the present application do not limit the value range of the rotation angle set.

[0062] Optionally, the rotation angle set can be or or or or other rotation angle sets, and the embodiments of the present application do not limit this.

[0063] Optionally, the first communication node can randomly select a rotation angle from the rotation angle set, or determine the index of the rotation angle based on the rotation angle information and determine the rotation angle corresponding to the index from the rotation angle set.

[0064] Optionally, the rotation angle information can be a random number generated by a random number generator. For example, the index of the rotation angle is determined by performing an operation on the random number and N, including but not limited to a remainder operation, a division operation, etc., and the rotation angle corresponding to the index is determined from the rotation angle set. For example, assuming that N is equal to 16, the random number is 1, and 1 modulo 16 is 1 (i.e., the rotation angle index is 1), then the rotation angle with index 1 in the rotation angle set can be selected; if the random number is 18, 18 modulo 16 is 2 (i.e., the rotation angle index is 2), then the rotation angle with index 2 in the rotation angle set can be selected.

[0065] Optionally, the rotation angle information is part of the data to be transmitted. For example, the rotation angle information is binary bits in the data bits to be transmitted, the binary bits are converted into a decimal number, and an operation is performed on the decimal number and N, including but not limited to a remainder operation, a division operation, etc., to determine the index of the rotation angle, and the rotation angle corresponding to the index is determined from the rotation angle set. Wherein, represents rounding up. For example, assuming that N is equal to 16, then 16 can be represented by 4 bits, i.e., 0000-1111 represents 1-16 (or 0-15). The first communication node can determine a decimal number from the 4 bits in the data bits to be transmitted, perform a remainder operation on the decimal number and 16 to obtain the index of the rotation angle, and determine the rotation angle using the index. The 4 bits can be the first 4 bits, the last 4 bits, or some 4 bits in the middle of the data bits to be transmitted. Assuming that the 4 bits are 1111, then the corresponding decimal number is 15, 15 modulo 16 plus 1, and the rotation angle index is 16, so the 16th rotation angle in the rotation angle set can be selected.

[0066] Optionally, the rotation angle information is determined based on a user identifier. The user identifier can be user identity information, such as UE-ID. In a grant-free transmission, since the second communication node (data receiving end) does not know which users / terminals are transmitting data, the first communication node can carry the user identifier in the data to be transmitted. Once the second communication node correctly decodes the user data, the user identity information can be obtained through the user identifier.

[0067] Optionally, the rotation angle information can also be determined by pilot information. Optionally, the pilot information can be a pilot index, which can be a random number, or part of the data to be transmitted or other information. For example, the first communication node can take the pilot index as the rotation angle information, and determine the index of the rotation angle according to the pilot index, and determine the rotation angle corresponding to the index from the set of rotation angles. For example, the pilot index is operated on N to determine the index of the rotation angle, including but not limited to the remainder operation, division operation, etc., to determine the rotation angle corresponding to the index from the set of rotation angles.

[0068] S902, rotating the first symbol according to the rotation angle to obtain a second symbol.

[0069] After determining the rotation angle, the first communication node can multiply the first symbol by e jθ or e -jθ based on the rotation angle to obtain a second symbol. Wherein θ is the determined rotation angle.

[0070] Optionally, the first communication node can rotate at least one of the pilot symbol and the data symbol based on the rotation angle.

[0071] Optionally, rotating the pilot symbol based on the rotation angle includes multiplying the pilot symbol by or Wherein θ1 is the rotation angle of the pilot symbol.

[0072] Optionally, rotating the data symbol based on the rotation angle includes multiplying the data symbol by or Wherein θ2 is the rotation angle of the data symbol.

[0073] Optionally, rotating the pilot symbol and the data symbol based on the rotation angle includes multiplying the pilot symbol by or And multiplying the data symbol by or Wherein θ1 is the rotation angle of the pilot symbol, and θ2 is the rotation angle of the data symbol.

[0074] S903, sending the second symbol.

[0075] After rotating the first symbol based on the rotation angle to obtain the second symbol, the first communication node maps the second symbol to the transmission resource for transmission.

[0076] FIG. 10 is another flow diagram of a data transmission method according to an embodiment of the present application, which is applied to a second communication node, which can be a data receiving end in a network, such as a base station, a receiver, a relay station or an access point, etc. For the grant-free transmission, the second communication node does not know which users are currently transmitting data, and therefore, the second communication node needs to perform blind multi-user detection on the received multi-user superposed second symbol to complete the separation and demodulation of multi-user data. As shown in FIG. 10, the method can specifically include the following steps.

[0077] S1001, receiving a multi-user superposed second symbol, the second symbol including pilot symbols and data symbols.

[0078] S1002, detecting the data symbols based on the pilot symbols to obtain user data.

[0079] For the grant-free transmission, the second communication node does not know which users are currently transmitting data. Therefore, the second communication node can use a pilot sequence set to detect the received multi-user superposed pilot symbols, and detect the data symbols based on the pilot symbol detection result to obtain user data.

[0080] S1003, reconstructing a second symbol of a user based on the user data, and performing interference cancellation on the multi-user superposed second symbol based on the reconstructed second symbol of the user.

[0081] For the correctly decoded user data, the correctly decoded user data can be reprocessed for designation, the second symbol of the user is reconstructed, and the reconstructed second symbol of the user is used to perform interference cancellation on the multi-user superposed second symbol. The processing includes at least one of encoding, interleaving, scrambling, modulation, mapping and spreading, etc.

[0082] Optionally, the process of S1002 can be: performing active user detection and channel estimation based on the pilot symbols to obtain a first channel estimation result; performing channel equalization on the data symbols based on the first channel estimation result to obtain equalized data symbols; and processing the equalized data symbols to obtain user data.

[0083] Specifically, the second communication node can detect the received multi-user superimposed pilot symbols with the pilot sequence set, so as to identify the pilot sequence sent by the user, complete active user detection and channel estimation, and obtain a first channel estimation result. Then, the multi-user superimposed data symbols are equalized with the first channel estimation result, and the equalized data symbols of the active user are obtained. The channel equalization algorithm here can include but is not limited to MRC algorithm, MMSE algorithm, ML algorithm or ZF algorithm, etc. Alternatively, after obtaining the equalized data symbols, the equalized data symbols can also be used to estimate the rotation angle of the active user, such as using the constellation diagram of the equalized data symbols to estimate the rotation angle of the active user, and applying compensation to the equalized data symbols in the opposite direction of the estimated rotation angle. Taking the constellation diagram of the active user shown in FIG. 8 as an example, the rotation angle of the active user can be estimated to be 90 degrees (π / 2) through the constellation diagram, and then the data symbols of the active user can be rotated by -90 degrees (or -π / 2). Then, the active user equalized data symbols or the data symbols after rotation angle compensation are processed, and user data is obtained. The processing includes at least one of the following: despreading, demapping, demodulation, descrambling, deinterleaving, decoding, etc. Alternatively, the cyclic redundancy check can also be used to determine whether the user data is decoded correctly.

[0084] Alternatively, the user data described above can include at least one of the following: service data, user identifier, pilot information and rotation angle information. That is, in addition to carrying service data, the user data can also carry a user identifier, which can be user identity information such as UE-ID. After the second communication node correctly decodes the user data, the user identity information and the data transmitted by the user can be obtained. In addition, the user data can also carry pilot information, such as the index of the pilot, and can also carry rotation angle information or rotation angle.

[0085] Alternatively, the reconstruction of the second symbol of the user based on the user data in S1003 described above can include: generating a first symbol based on the user data, the first symbol including pilot symbols and data symbols; and rotating the first symbol according to the rotation angle to reconstruct the second symbol of the user.

[0086] For the user data decoded correctly, the user data is reprocessed to reconstruct the data symbol of the user, and the pilot symbol of the user is reconstructed according to the pilot information, and the pilot symbol and the data symbol together constitute the first symbol to be sent by the user. Further, the rotation angle is determined according to the rotation angle information, and the first symbol is rotated with the rotation angle to reconstruct the second symbol of the user. The processing includes at least one of the following: encoding, interleaving, scrambling, modulation, mapping, and spreading, etc.

[0087] The process of determining the rotation angle by using the rotation angle information can refer to the description in any of the above embodiments, and the present embodiment will not be described here again.

[0088] Optionally, the interference cancellation of the second symbol superimposed with multiple users based on the second symbol of the reconstructed user in S1003 comprises: reconstructing the second symbol of the user received by the second communication node based on the first channel estimation result or the second channel estimation result and the second symbol of the reconstructed user; and subtracting the reconstructed second symbol of the received user from the second symbol superimposed with multiple users.

[0089] The first channel estimation result can be obtained by the following method: the second communication node detects the received pilot symbol by using the pilot sequence set, identifies the pilot sequence sent by the user, completes the active user detection and channel estimation, and obtains the first channel estimation result.

[0090] The second channel estimation result can be obtained by the following method: the second communication node performs least square channel estimation on the second symbol superimposed with multiple users and the second symbol of the reconstructed user, and obtains the second channel estimation result.

[0091] After obtaining the first channel estimation result or the second channel estimation result, the second symbol of the user received by the second communication node is reconstructed by using the first channel estimation result / second channel estimation result and the second symbol of the reconstructed user (for example, multiplying the first channel estimation result / second channel estimation result and the second symbol of the reconstructed user), and the reconstructed second symbol of the received user is subtracted from the second symbol superimposed with multiple users, so as to realize interference cancellation.

[0092] After obtaining the second symbol after interference cancellation, the process of S1002-S1003 is continued to be executed on the second symbol after interference cancellation, that is, the next round of identification and detection is re-performed until no active user can be identified, or until a specified number of iterations is reached.

[0093] The technical scheme provided by the embodiment of the present application acquires the first symbol and the rotation angle, the first symbol includes pilot symbols and data symbols, rotates the first symbol according to the rotation angle to obtain the second symbol, and transmits the second symbol. By rotating the first symbol according to the rotation angle, it is easier to separate and demodulate the pilot collision user signal, improve the number of users supported by the scheduling-free transmission system, and improve the system performance.

[0094] In order to facilitate the understanding of those skilled in the art, the data transmission scheme provided by the embodiment of the present application will be introduced in detail as follows:

[0095] In one embodiment, only the data symbol is rotated, or the constellation map mapped by the data symbol is rotated, which can improve the demodulation performance of the pilot collision user in the scheduling-free transmission.

[0096] When the user has service data to send, the user specifies the data bits to be sent to form data symbols to be sent, and rotates the data symbols by using a rotation angle randomly selected from a set of rotation angles or by using rotation angle information to determine the rotation angle, to obtain rotated data symbols. Then, the rotated data symbols are mapped to transmission resources together with pilot symbols for sending. The processing includes at least one of encoding, interleaving, scrambling, modulation, mapping, and spreading.

[0097] Still taking the example of 2-pilot collision users, the pilot symbols of the user 1 and the user 2 are not rotated, and the data symbols of the user 1 and the user 2 are rotated. Optionally, rotating the data symbols of the user 1 can be multiplying the data symbols of the user 1 by or Rotating the data symbols of the user 2 can be multiplying the data symbols of the user 2 by or Therefore, the pilot signals of the user 1 and the user 2 superimposed and received by the second communication node are as shown in formula (5), and the data symbols of the user 1 and the user 2 superimposed and received by the second communication node can be represented as:

[0098] Wherein θ1 is the rotation angle randomly selected by the user 1, and θ2 is the rotation angle randomly selected by the user 2. Assuming that ideal channel estimation is used and an MRC combining algorithm is adopted, the data symbols after MRC combination can be represented as:

[0099] It can be found by observing formula (14) that the data symbols after channel equalization can be regarded as the superposition of the data symbols of the user 1 and the user 2 with different rotation angles. The second communication node can first solve the information of the user 1 with the interference of the user 2, then eliminate the information of the user 1 through interference cancellation, and then solve the information of the user 2. Alternatively, the second communication node can first solve the information of the user 2 with the interference of the user 1, then eliminate the information of the user 2 through interference cancellation, and then solve the information of the user 1.

[0100] In the embodiment, the rotation angle of the data symbol can be obtained by the following process: randomly obtaining a rotation angle from a set of rotation angles; and determining the rotation angle from the set of rotation angles according to rotation angle information. The set of rotation angles can include N rotation angles, and N is an integer greater than or equal to 2. Optionally, the set of rotation angles can have a value range of [-π / 2, π / 2], [0, π / 2], [-π / 2, 0], or other value ranges, and the embodiments of the present application do not limit the value range of the set of rotation angles.

[0101] Optionally, the set of rotation angles can be or or or or other sets of rotation angles, which are not limited in the embodiments of the present application.

[0102] Optionally, the first communication node can randomly select a rotation angle from the set of rotation angles, or determine the rotation angle based on the rotation angle information, for example, determine the index of the rotation angle based on the rotation angle information, and determine the rotation angle corresponding to the index from the set of rotation angles.

[0103] Optionally, the rotation angle information can be a random number generated by a random number generator. For example, the index of the rotation angle is determined by performing operations including but not limited to remainder operation, division operation, etc. on the random number and N, and the rotation angle corresponding to the index is determined from the set of rotation angles.

[0104] Optionally, the rotation angle information is part of the data to be transmitted. For example, the rotation angle information is binary bits in the data bits to be transmitted, the binary bits are converted into a decimal number, and operations including but not limited to remainder operation, division operation, etc. are performed on the decimal number and N to determine the index of the rotation angle, and the rotation angle corresponding to the index is determined from the set of rotation angles. Wherein, represents rounding up.

[0105] Optionally, the rotation angle information is determined based on the user identity. The user identity can be the user identity information, such as UE-ID. In the grant-free transmission, since the base station does not know which users / terminals are transmitting data, the first communication node can carry the user identity in the data to be transmitted. Once the second communication node correctly decodes the user data, the user identity information can be obtained through the user identity.

[0106] Optionally, the rotation angle information is determined through pilot information. Optionally, the pilot information can be a pilot index, which can be a random number, or part of the data to be transmitted or other information. For example, the first communication node takes the pilot index as the rotation angle information, and determines the index of the rotation angle according to the pilot index, and determines the rotation angle corresponding to the index from the set of rotation angles. For example, the pilot index is subjected to operations including but not limited to remainder operation, division operation, etc. to determine the index of the rotation angle, and the rotation angle corresponding to the index is determined from the set of rotation angles.

[0107] The simulation results of the block error rate (BLER) of the data transmission scheme provided in the embodiments of the present application and the conventional data transmission scheme are shown in FIG. 11. Compared with the conventional data transmission scheme, the data transmission scheme provided in the embodiments of the present application has a gain of 4 dB when the block error rate is equal to 10 -1 Thus, the demodulation performance of the pilot collision user in the scheduling-free transmission is improved.

[0108] In one embodiment, only the pilot symbol can be rotated without rotating the data symbol, and in this way, the demodulation performance of the pilot collision user signal can also be improved. In the scheduling-free data transmission, the pilot overhead is usually lower than the data overhead, for example, the pilot overhead accounts for 1 / 14, 1 / 7 or 2 / 7 of the entire transmission resource. Thus, the complexity of rotating the pilot symbol is relatively low.

[0109] When the user has service data to be sent, the data bits to be sent are processed to form data symbols to be sent. A pilot sequence is randomly selected from a pilot sequence set as a pilot symbol, and the rotation angle is obtained by using any of the above embodiments. The pilot symbol is rotated by using the rotation angle to obtain a rotated pilot symbol. Further, the rotated pilot symbol and the data symbol are mapped to the transmission resource for transmission. The processing includes at least one of encoding, interleaving, scrambling, modulation, mapping and spreading.

[0110] Still taking the example of two pilot collision users, the pilot symbols of the user 1 and the user 2 are rotated. Optionally, the rotation of the pilot symbol of the user 1 can be multiplying the pilot symbol of the user 1 by Or The rotation of the pilot symbol of the user 2 can be multiplying the pilot symbol of the user 2 by Or The rotation angle of the pilot symbol can be obtained by referring to the rotation angle obtaining process of the data symbol in the above embodiments, which will not be described herein again. The superimposed pilot symbols of the user 1 and the user 2 received by the second communication node can be represented as:

[0111] Wherein, θ1 is the rotation angle randomly selected by the user 1, and θ2 is the rotation angle randomly selected by the user 2.

[0112] In the embodiment, the data symbol to be sent is not rotated, and the superimposed data symbols of the user 1 and the user 2 received by the second communication node can be represented as formula (6). Assuming that the ideal channel estimation and the MRC combining algorithm are used, the ideal channel estimation of the received superimposed pilot symbols is obtained as The data symbol after MRC combination can be expressed as:

[0113] It can be found by observing equation (16) that the data symbol after channel equalization can be regarded as the superposition of the data symbols of user 1 and user 2 with different rotation angles, such as the rotation angle applied to the data symbol of user 1 is -θ1, and the rotation angle applied to the data symbol of user 2 is -θ2. Rotating the pilot symbols of user 1 and user 2 is equivalent to rotating the data symbols to be sent of user 1 and user 2 after channel equalization. Therefore, the second communication node can first solve the information of user 1 with the interference of user 2, then eliminate the information of user 1 through interference cancellation, and then solve the information of user 2. Or, the second communication node can first solve the information of user 2 with the interference of user 1, then eliminate the information of user 2 through interference cancellation, and then solve the information of user 1.

[0114] In an embodiment, the pilot symbols and the data symbols to be sent can also be rotated at the same time, and in this way, the demodulation performance of the pilot collision user signal can also be improved.

[0115] When the user sends service data, the data bits to be sent are processed to form data symbols to be sent. A pilot sequence is randomly selected from a pilot sequence set as a pilot symbol, and a rotation angle is obtained by using any of the above embodiments. Then, the obtained rotation angle is used to rotate the pilot symbol and the data symbol to be sent respectively to obtain a rotated pilot symbol and a rotated data symbol. Further, the rotated pilot symbol and the data symbol are mapped to a transmission resource for transmission together. The processing includes at least one of encoding, interleaving, scrambling, modulation, mapping, spreading, and the like.

[0116] Still taking 2 pilot collision users as an example, the pilot symbols of user 1 and user 2 are rotated, for example, the pilot symbol of user 1 is multiplied by and the pilot symbol of user 2 is multiplied by That is, the pilot symbols of user 1 and user 2 superimposed received by the second communication node can be expressed as:

[0117] In this embodiment, θ1 is the rotation angle applied to the pilot symbol of user 1, and θ3 is the rotation angle applied to the pilot symbol of user 2.

[0118] The data symbols to be sent of user 1 and user 2 are rotated, for example, the data symbol of user 1 is multiplied by and the data symbol of user 2 is multiplied by The superimposed data symbols of user 1 and user 2 received by the second communication node can be expressed as:

[0119] In the embodiment, θ2 is a rotation angle applied to the data symbol of user 1, and θ4 is a rotation angle applied to the data symbol of user 2.

[0120] It is assumed that ideal channel estimation and MRC combining algorithm are adopted, that is, the second communication node performs ideal channel estimation on the received superimposed pilot symbols to obtain The data symbol after MRC combining can be expressed as:

[0121] It can be found by observing formula (19) that the data symbol after channel equalization can be regarded as superimposition of the data symbols of user 1 and user 2 with different rotation angles, such as a rotation angle θ2-θ1 applied to the data symbol of user 1 and a rotation angle θ4-θ3 applied to the data symbol of user 2. At the same time, the pilot symbols and data symbols of user 1 and user 2 are rotated, and after channel equalization, it is equivalent to rotating the data symbols to be sent by user 1 and user 2. Therefore, the second communication node can first solve the information of user 1 with the interference of user 2, then eliminate the information of user 1 through interference cancellation, and then solve the information of user 2. Or the base station can first solve the information of user 2 with the interference of user 1, then eliminate the information of user 2 through interference cancellation, and then solve the information of user 1.

[0122] In the embodiment, the rotation angles of the pilot symbols and data symbols described above can be obtained through the following process: randomly obtaining a rotation angle from a rotation angle set; and determining the rotation angle from the rotation angle set according to the rotation angle information. The rotation angle set can include N rotation angles, and N is an integer greater than or equal to 2. Alternatively, the rotation angle set can be [-π / 2, π / 2], [0, π / 2], [-π / 2, 0] or other value ranges, and the embodiments of the present application do not limit the value range of the rotation angle set.

[0123] Alternatively, the rotation angle set can be or or or or other rotation angle sets, which are not limited by the embodiments of the present application.

[0124] Optionally, the first communication node can randomly select 2 rotation angles from the set of rotation angles as the rotation angles of the pilot symbol and the data symbol respectively, or determine the rotation angles based on the rotation angle information. For example, determine the index of the rotation angle based on the rotation angle information, and determine the rotation angle corresponding to the index from the set of rotation angles.

[0125] Optionally, the rotation angle information can be 2 random numbers generated by a random number generator, which are used to determine the rotation angles of the pilot symbol and the data symbol respectively. For example, determine the index of the rotation angle by performing operations including but not limited to remainder operation, division operation, etc. on the random numbers and N, and determine the rotation angle corresponding to the index from the set of rotation angles.

[0126] Optionally, the rotation angle information is part of the data to be transmitted. For example, the rotation angle information is binary bits in the data bits to be transmitted, which are used to determine the rotation angles of the pilot symbol and the data symbol respectively. Optionally, the binary bits can be converted into decimal numbers, and then operations including but not limited to remainder operation, division operation, etc. are performed on the decimal numbers and N to determine the index of the rotation angle, and the rotation angle corresponding to the index is determined from the set of rotation angles. Wherein, represents rounding up.

[0127] Optionally, the rotation angle information is determined based on the user identifier. The user identifier can be user identity information, such as UE-ID. In the grant-free transmission, since the base station does not know which users / terminals are transmitting data, the first communication node can carry the user identifier in the data to be transmitted. Once the second communication node correctly decodes the user data, it can obtain the user identity information through the user identifier.

[0128] Optionally, the rotation angle information is determined through pilot information. Optionally, the pilot information can be a pilot index, which can be a random number, or part of the data to be transmitted or other information. For example, the first communication node takes the pilot index as the rotation angle information, and determines the index of the rotation angle according to the pilot index, and determines the rotation angle corresponding to the index from the set of rotation angles. For example, determine the index of the rotation angle by performing operations including but not limited to remainder operation, division operation, etc. on the pilot index and N, and determine the rotation angle corresponding to the index from the set of rotation angles. Optionally, the user transmits 2 pilots, and the rotation angle information is the information of the 2 pilots, such as the indexes of the 2 pilots, which are used to determine the rotation angles of the pilot symbol and the data symbol.

[0129] Optionally, the rotation angle information can also be information of one rotation angle, that is, one rotation angle can be determined first, such as one of the rotation angle of the pilot symbol or the rotation angle of the data symbol is obtained by the above-mentioned any embodiment, and the other rotation angle can be determined according to the determined rotation angle. For example, the user determines the rotation angle of the pilot symbol as θ1 according to the rotation angle information, and the rotation angle θ2 of the data symbol can be determined according to the rotation angle θ1 of the pilot symbol, such as θ2 can be obtained by operating θ1, including but not limited to θ2 equal to -θ1, or θ2 equal to θ1 plus or minus an angle, and the like.

[0130] FIG. 12 is a structural schematic diagram of a data transmission device provided by an embodiment of the present application. The device is integrated in a first communication node, as shown in FIG. 12, and can include an acquisition module 1201, a rotation module 1202, and a sending module 1203.

[0131] The acquisition module 1201 is configured to acquire a first symbol and a rotation angle, the first symbol including a pilot symbol and a data symbol; the rotation module 1202 is configured to rotate the first symbol according to the rotation angle to obtain a second symbol; and the sending module 1203 is configured to send the second symbol.

[0132] Optionally, on the basis of the above-mentioned embodiment, the rotation module 1202 is specifically configured to rotate at least one of the pilot symbol and the data symbol according to the rotation angle.

[0133] Optionally, on the basis of the above-mentioned embodiment, the rotation module 1202 is specifically configured to multiply the pilot symbol by or or multiply the data symbol by or or multiply the pilot symbol by or and multiply the data symbol by or wherein θ1 is the rotation angle of the pilot symbol, and θ2 is the rotation angle of the data symbol.

[0134] Optionally, on the basis of the above-mentioned embodiment, the acquisition module 1201 is specifically configured to at least one of the following: randomly acquiring a rotation angle from a rotation angle set; and determining a rotation angle from the rotation angle set according to rotation angle information.

[0135] Optionally, the rotation angle information includes at least one of the following: the rotation angle information is a random number generated by a random number generator; the rotation angle information is part of data in to-be-sent data; the rotation angle information is determined based on a user identifier; and the rotation angle information is determined through pilot information.

[0136] Optionally, the data to be sent comprises at least one of the following: service data; user identifier; pilot information; and rotation angle information.

[0137] FIG. 13 is another structural schematic diagram of a data transmission apparatus provided by an embodiment of the present application. The apparatus is integrated in a second communication node. As shown in FIG. 13, the apparatus can comprise a receiving module 1301, a detecting module 1302, and an interference cancellation module 1303.

[0138] The receiving module 1301 is configured to receive a second symbol superimposed by multiple users, wherein the second symbol comprises pilot symbols and data symbols; the detecting module 1302 is configured to detect the data symbols based on the pilot symbols to obtain user data; and the interference cancellation module 1303 is configured to reconstruct a second symbol of a user based on the user data, and perform interference cancellation on the second symbol superimposed by multiple users based on the reconstructed second symbol of the user.

[0139] Optionally, the detecting module 1302 is specifically configured to perform active user detection and channel estimation based on the pilot symbols to obtain a first channel estimation result; perform channel equalization on the data symbols based on the first channel estimation result to obtain equalized data symbols; and process the equalized data symbols to obtain user data; and the processing comprises at least one of the following: despreading, demapping, demodulation, descrambling, deinterleaving, and decoding.

[0140] Optionally, the detecting module 1302 is further configured to estimate a rotation angle based on the equalized data symbols in the process of processing the equalized data symbols; and apply compensation in a direction opposite to the rotation angle to the equalized data symbols.

[0141] Optionally, the user data comprises at least one of the following: service data; user identifier; pilot information; and rotation angle information.

[0142] Optionally, the interference cancellation module 1303 is further specifically configured to generate a first symbol based on the user data, wherein the first symbol comprises pilot symbols and data symbols; and rotate the first symbol according to a rotation angle to reconstruct a second symbol of a user.

[0143] Optionally, the interference cancellation module 1303 is further specifically configured to reconstruct a received second symbol of the user based on the first channel estimation result or a second channel estimation result and the reconstructed second symbol of the user; and subtract the reconstructed received second symbol of the user from the second symbol superimposed by multiple users.

[0144] Optionally, the second channel estimation result is obtained by the following manner:

[0145] performing least square channel estimation on the second symbol of the multi-user superposition and the second symbol of the reconstructed user to obtain a channel estimation, obtaining a second channel estimation result.

[0146] In an embodiment, a communication node is also provided, which is the first communication node or the second communication node as described in the above embodiments. The internal structure diagram of the communication node can be shown in FIG. 14. The communication node includes a processor, a memory, a network interface and a database connected through a system bus. The processor of the communication node is configured to provide computing and control capabilities. The memory of the communication node includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program and a database. The internal memory provides an environment for the operating system and the computer program in the non-volatile storage medium to run. The database of the communication node is configured to store data generated in the scheduling-free transmission process. The network interface of the communication node is configured to communicate with external terminals through a network connection. The computer program is executed by the processor to implement a data transmission method.

[0147] Those skilled in the art can understand that the structure shown in FIG. 14 is only a block diagram of part of the structure related to the scheme of the present application, and does not constitute a limitation on the communication node to which the scheme of the present application is applied. Specifically, the communication node can include more or fewer components than those shown in the figure, or combine certain components, or have a different component arrangement.

[0148] In an embodiment, a computer readable storage medium is also provided, and the computer readable storage medium stores a computer program. The computer program is executed by a processor to implement: obtaining a first symbol and a rotation angle, the first symbol including a pilot symbol and a data symbol; rotating the first symbol according to the rotation angle to obtain a second symbol; and transmitting the second symbol.

[0149] Alternatively, the computer program is executed by a processor to implement: receiving a second symbol of multi-user superposition, the second symbol including a pilot symbol and a data symbol; detecting the data symbol based on the pilot symbol to obtain user data; reconstructing a second symbol of a user based on the user data; and performing interference cancellation on the second symbol of the multi-user superposition based on the second symbol of the reconstructed user.

[0150] The computer storage medium of the embodiments of the present application can adopt any combination of one or more computer readable media. The computer readable medium can be a computer readable signal medium or a computer readable storage medium. The computer readable storage medium may, for example, but is not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, device or apparatus, or any combination thereof. The computer readable storage medium includes, but is not limited to, a non-exhaustive list: an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an electrically erasable, programmable read-only memory (EPROM), a flash memory, an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination thereof. In the present application, the computer readable storage medium can be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, device or apparatus.

[0151] The computer readable signal medium can include a data signal propagating in a baseband or as part of a carrier wave propagating through a transmission medium, and bearing computer readable program code. Such a propagating data signal can take many forms, including but not limited to electro-magnetic, optical, or any suitable combination thereof. The computer readable signal medium can also be any computer readable medium that is not a computer readable storage medium and that can communicate, propagate or transport program for use by or in connection with an instruction execution system, apparatus or device.

[0152] The program code contained on the computer readable medium can be transmitted by any suitable medium, including but not limited to wireless, wire, optical cable, radio frequency (RF), etc., or any suitable combination thereof.

[0153] Computer program code for carrying out operations of the present disclosure can be written in any combination of one or more programming languages, including an object oriented programming language such as Java, Smalltalk, C++, Ruby, Go, or the like, and conventional procedural programming languages, such as the "C" programming language or similar programming languages. The program code can execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer or server. In the latter scenario, the remote computer can be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or the connection can be made to an external computer (for example, through the Internet using an Internet Service Provider).

[0154] Those skilled in the art will appreciate that the term user terminal encompasses any appropriate type of wireless user equipment, such as a mobile phone, a portable data processing apparatus, a portable web browser, or a vehicle mounted mobile station.

[0155] In general, the various embodiments of the application can be implemented in hardware or special purpose circuits, software, logic or any combination thereof. For example, some aspects can be implemented in hardware, while other aspects can be implemented in

[0156] Embodiments of the application can be implemented by the data processor of a mobile device executing computer program instructions, for example in a processor entity, or by hardware, or by a combination of software and hardware. Computer program instructions can be in assemblies, instruction-set-architecture (ISA) instructions, machine instructions, machine dependent instructions, microcode, firmware instructions, state-setting data, or in any combination of one or more programming languages, executed on one or more computing devices.

[0157] The block diagrams of any logical flow of the present application in the drawings can represent program operations, or can represent interconnecting logical circuits, modules and functions, or can represent a combination of program operations and logical circuits, modules and functions. The computer program can be stored on a memory. The memory can have any type suitable for the local technical environment and can be implemented using any suitable data storage technology, such as, but not limited to, read only memory (ROM), random access memory (RAM), optical storage devices, and systems such as digital versatile disc (DVD) or CD-ROM, and the like. The computer readable media can include non-transitory storage media. The data processor can be of any type suitable for the local technical environment, and can include, but is not limited to, general purpose computers, special purpose computers, microprocessors, digital signal processors (DSP), application specific integrated circuits (ASIC), field programmable gate arrays (FPGA), and processors based on multi-core processor architectures, as examples.

Claims

1. A data transmission method applied to a first communication node, comprising: obtaining a first symbol and a rotation angle, the first symbol comprising a pilot symbol and a data symbol; rotating the first symbol according to the rotation angle to obtain a second symbol; transmitting the second symbol.

2. The method of claim 1, wherein, The rotating the first symbol according to the rotation angle comprises: rotating at least one of the pilot symbol and the data symbol according to the rotation angle.

3. The method of claim 2, wherein, The rotating at least one of the pilot symbol and the data symbol according to the rotation angle comprises: multiplying the pilot symbols by or or multiplying the data symbols by or or multiplying the pilot symbols by or and multiplying the data symbols by or wherein θ1 is a rotation angle of the pilot symbol and θ2 is a rotation angle of the data symbol.

4. The method of claim 1, wherein, The obtaining the rotation angle comprises at least one of: randomly obtaining the rotation angle from a set of rotation angles; determining the rotation angle from a set of rotation angles according to rotation angle information.

5. The method of claim 4, wherein, The rotation angle information comprises at least one of: the rotation angle information being a random number generated by a random number generator; the rotation angle information being part of data to be transmitted; the rotation angle information being determined based on a user identifier; the rotation angle information being determined through pilot information.

6. The method of claim 5, wherein, The data to be transmitted comprises at least one of: service data; a user identifier; pilot information; rotation angle information. 7.A data transmission method applied to a second communication node, comprising: receiving a multi-user superimposed second symbol, the second symbol comprising a pilot symbol and a data symbol; detecting the data symbol based on the pilot symbol to obtain user data; reconstructing a second symbol of a user based on the user data, and performing interference cancellation on the multi-user superimposed second symbol based on the reconstructed second symbol of the user.

8. The method of claim 7, wherein, The detecting the data symbol based on the pilot symbol to obtain user data comprises: performing active user detection and channel estimation based on the pilot symbol to obtain a first channel estimation result; performing channel equalization on the data symbol based on the first channel estimation result to obtain equalized data symbol; processing the equalized data symbol to obtain the user data, the processing comprising at least one of: de-spreading, de-mapping, de-modulating, de-scrambling, de-interleaving and decoding.

9. The method of claim 8, wherein, The processing the equalized data symbol further comprises: estimating a rotation angle using the equalized data symbol; and applying compensation in a direction opposite to the rotation angle to the equalized data symbol.

10. The method of any one of claims 7 to 9, wherein, The user data comprises at least one of: service data; a user identifier; pilot information; rotation angle information.

11. The method of claim 7, wherein, The reconstructing a second symbol of a user based on the user data comprises: generating a first symbol based on the user data, the first symbol comprising a pilot symbol and a data symbol; and rotating the first symbol according to a rotation angle to reconstruct a second symbol of the user.

12. The method of claim 8, wherein, The performing interference cancellation on the multi-user superimposed second symbol based on the reconstructed second symbol of the user comprises: reconstructing a received second symbol of the user based on the first channel estimation result or a second channel estimation result and the reconstructed second symbol of the user. subtracting the reconstructed second symbol of the user from the second symbol of the multi-user superposition.

13. The method of claim 12, wherein, The second channel estimation result is obtained by: performing least square channel estimation on the second symbol of the multi-user superposition and the reconstructed second symbol of the user to obtain the second channel estimation result.

14. A communication node, comprising: a memory storing a computer program, and a processor, wherein the processor executes the computer program to implement the data transmission method in any one of claims 1-13.

15. A computer readable storage medium storing a computer program, wherein the computer program is executed by a processor to implement the data transmission method in any one of claims 1-13.

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