Otfs embedded sequence pilot signal and channel estimation method and receiving end based on the same

Abstract

The application discloses an OTFS embedded sequence pilot signal and a channel estimation method and a receiving end based on the same. The pilot signal comprises a one-dimensional ZC sequence group extended along a Doppler domain, a zero protection zone and a time delay protection zone, and the one-dimensional ZC sequence group comprises at least one ZC sequence with the same placement position. By placing the at least one ZC sequence at the same position along the Doppler domain instead of extending along the time delay domain, the pilot signal provided by the application can realize MIMO technology and multiple access technology, and can also avoid problems such as narrow application range, more resource consumption and difficult channel equalization caused by extension in the time delay domain; and the ZC sequences with the same placement position can also avoid the problem of signal interference between pilots.

Description

Technical Field

[0001] This invention belongs to the field of wireless communication technology, specifically relating to an OTFS embedded sequence pilot signal and a channel estimation method and receiver based thereon. Background Technology

[0002] With the large-scale deployment and application of high-speed rail, satellites, and high-speed and even hypersonic aircraft, wireless communication in high-latency, strong Doppler channel environments faces significant challenges. In such environments, traditional Orthogonal Frequency Division Multiplexing (OFDM) systems are severely affected by strong Doppler, leading to a sharp decline in system performance. In recent years, the development of Orthogonal Time Frequency Space (OTFS) technology has provided a feasible method for addressing these problems.

[0003] Unlike OFDM systems, which modulate signals in the time-frequency domain, OTFS extends the signal distribution to the time-delay Doppler domain through a two-dimensional transformation and transmits the symbols in the time-frequency domain. This approach allows the receiver to process the signal in the time-delay-Doppler domain, resulting in excellent performance in fast time-varying channels.

[0004] Currently, there are two types of pilot methods used in OTFS channels: superimposed pilots and embedded pilots. Superimposed pilots add the pilot signal to the traffic signal, thus requiring interference elimination between the pilot and traffic signals during channel estimation, making the signal processing relatively complex. Embedded pulse pilots are simpler, requiring zero protection around the pulse. However, the currently popular pulse embedded pilot method cannot implement MIMO or multiple access technologies, and the embedded pilot method extending along the time delay domain can interfere with the data domain signal, making channel estimation and equalization difficult.

[0005] Therefore, current pilot signals are either difficult and complex to process, or they cannot implement MIMO and multiple access technologies when performing channel estimation. Summary of the Invention

[0006] This invention provides an OTFS embedded sequence pilot signal and a channel estimation method and receiver based thereon, which can solve the problems that current pilot signals are either difficult and complex to process, or cannot implement MIMO and multiple access technologies when performing channel estimation.

[0007] In a first aspect, an OTFS embedded sequence pilot signal provided by an embodiment of the present invention includes:

[0008] A one-dimensional ZC sequence group extended along the Doppler domain, wherein the one-dimensional ZC sequence group includes at least one ZC sequence placed in the same position;

[0009] The zero protection zone includes a first zero protection zone and a second zero protection zone, which are respectively set before and after the one-dimensional ZC sequence group along the time delay domain.

[0010] The time delay protection zone is set up along the time delay domain before the first zero protection zone.

[0011] Secondly, embodiments of the present invention provide a channel estimation method based on OTFS embedded sequence pilot signals, including:

[0012] The received signal is obtained by performing a Fourier transform along the Doppler domain on the extended region of the received signal.

[0013] The received signal is the transmitted signal that has been transmitted through the channel. The transmitted signal includes OTFS embedded sequence pilot signals and user signals. The OTFS embedded sequence pilot signals include: a one-dimensional ZC sequence group extended along the Doppler domain, a zero-protection zone, and a time delay protection zone. The one-dimensional ZC sequence group includes at least one ZC sequence placed in the same position. The ZC sequence corresponds one-to-one with the user signal and is used to identify the user signal. The zero-protection zone includes a first zero-protection zone and a second zero-protection zone, which are respectively set before and after the one-dimensional ZC sequence group along the time delay domain. The time delay protection zone is set before the first zero-protection zone along the time delay domain. The extended area of ​​the received signal includes the ZC sequence group and the second zero-protection zone.

[0014] The frequency domain estimation result is obtained by performing frequency domain estimation on the transformed received signal.

[0015] The impulse response of the pilot signal is obtained by performing an inverse Fourier transform on the frequency domain estimation results.

[0016] Thirdly, embodiments of the present invention provide a receiving end, including:

[0017] The Fourier transform module is used to perform a Fourier transform on the extended region of the received signal along the Doppler domain to obtain the transformed received signal.

[0018] The received signal is the transmitted signal received through the channel. The transmitted signal includes OTFS embedded sequence pilot signals and user signals. The OTFS embedded sequence pilot signals include: a one-dimensional ZC sequence group extended along the Doppler domain, a zero-protection zone, and a time delay protection zone. The one-dimensional ZC sequence group includes at least one ZC sequence placed in the same position, and the number of ZC sequences corresponds one-to-one with the user signals to identify the user signals. The zero-protection zone includes a first zero-protection zone and a second zero-protection zone, which are respectively set before and after the one-dimensional ZC sequence group along the time delay domain. The time delay protection zone is set before the first zero-protection zone along the time delay domain. The extended area of ​​the received signal includes the ZC sequence group and the second zero-protection zone.

[0019] The frequency domain estimation module is used to perform frequency domain estimation on the transformed received signal to obtain the frequency domain estimation result.

[0020] The Fourier transform module is also used to perform inverse Fourier transform on the frequency domain estimation results to obtain the impulse response of the pilot signal.

[0021] The beneficial effects of the embodiments of the present invention compared with the prior art are as follows: by placing at least one ZC sequence in the same position along the Doppler domain instead of extending it along the time delay domain, the pilot signal provided by the present invention can realize MIMO technology and multiple access technology, and can avoid the problems of narrow applicability, high resource consumption and difficulty in channel equalization caused by extending it in the time delay domain; the ZC sequences placed in the same position can also avoid the problem of signal interference between pilots. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of an embedded pilot signal for a single antenna;

[0023] Figure 2 This is a schematic diagram of an embedded pilot signal with multiple antennas.

[0024] Figure 3 This is a schematic diagram of a multi-antenna pilot signal that extends along the time delay domain;

[0025] Figure 4 A schematic diagram of an OTFS embedded sequence pilot signal provided in an embodiment of the present invention;

[0026] Figure 5 This is a schematic diagram of cyclic compensation for a pilot signal provided in an embodiment of the present invention;

[0027] Figure 6 A schematic diagram of a transmission signal based on an OTFS embedded sequence pilot signal provided by the present invention;

[0028] Figure 7This is a schematic diagram of a ZC sequence orthogonal transmission signal provided in an embodiment of the present invention;

[0029] Figure 8 A schematic diagram illustrating the implementation process of a channel estimation method based on OTFS embedded sequence pilot signals provided in an embodiment of the present invention;

[0030] Figure 9 A schematic diagram illustrating a channel estimation method provided in an embodiment of the present invention;

[0031] Figure 10 This is a schematic diagram of a receiving end provided in an embodiment of the present invention;

[0032] Figure 11 This is a schematic diagram of the pulse response of a pilot signal provided in an embodiment of the present invention. Detailed Implementation

[0033] Figure 1 The diagram shown is a schematic of an embedded pilot signal for a single antenna.

[0034] In one example, see Figure 1 Traditional embedded pulse pilot methods place pulse pilot symbols in the time-delay-Doppler domain and maintain zero protection around them. The transmitted signal at the transmitting end includes, for example... Figure 1 The pilot signal shown in (a) is transmitted through a time-frequency dual-dispersion channel, and the received signal at the receiving end includes, for example, the pilot signal. Figure 1 The pilot signal shown in (b) is an example. The pulse pilot signal spreads as it travels through the channel. The receiver uses either the least squares method or the least mean square error method for channel estimation in the time-delay-Doppler domain.

[0035] For example, the pilot signal in the received signal can satisfy the following formula:

[0036]

[0037] Where ZDD is the pilot signal in the received signal, PDD is the pilot signal in the transmitted signal, and HDD is the equivalent channel matrix. This is the equivalent noise matrix.

[0038] For example, the channel estimation result obtained by the least squares method It can satisfy:

[0039]

[0040] For example, the channel estimation results obtained by the least mean square error method. The following formula can be satisfied:

[0041]

[0042] in, Let I be the noise variance, and I be the identity matrix.

[0043] The pilot signal of this single antenna cannot be applied to multiple-input multiple-output (MIMO) technology and multiple access technology, resulting in low communication efficiency.

[0044] Figure 2 The diagram shown is a schematic of an embedded pilot signal with multiple antennas.

[0045] For example, see Figure 2 Embedded pilot signals with multiple antennas are generally used in MIMO and multiple access technologies, where multiple antennas operate on the same channel.

[0046] A conventional multi-antenna pilot signal places pulse pilots at intervals in the time-delay-Doppler domain, see [link to relevant documentation]. Figure 2 (a) shows the signal frame structure of a 2×2 MIMO-OTFS system based on pulse pilots, where the red and green boxes represent the pilot and zero-guard regions of each transmit antenna, respectively. Different pulse pilots are aligned along the time delay domain. The receiver performs corresponding channel estimation based on the extension positions corresponding to different antennas at the transmitter. However, this pilot structure is not suitable for systems with higher Doppler extension or systems with more antennas, as signal interference may occur in the pilots of the received signals corresponding to different antennas.

[0047] Therefore, another method is to align the pilot signals corresponding to different antennas along the Doppler domain and arrange them in the time delay domain, see [link to relevant documentation]. Figure 2 (b) In this method, it can be applied to systems with high Doppler extension, but the time and frequency resources required will also increase, and the greater the time delay extension or the more antennas, the more resources will be consumed.

[0048] Another method involves extending the pilot signals corresponding to different antennas along both the Doppler and time-delay domains, see [link to relevant documentation]. Figure 2 (c) However, this method suffers from the disadvantages of both methods mentioned above: signal interference occurs between different pilots and resource consumption is relatively high.

[0049] Figure 3 The example shown is a multi-antenna pilot signal that extends along the time delay domain.

[0050] For example, a multi-antenna pilot signal extended along the time delay domain places a Zadoff Chu (ZC) sequence with a cyclic prefix added in the time delay domain, while retaining zero-guard regions on both sides of the sequence. Similarly, Figure 3 (a) in the diagram represents the pilot signal in the transmitted signal. Figure 3 (b) in the diagram represents the pilot signal in the received signal. See also... Figure 3 In the extended region of the received signal, valid information that can be used for channel estimation is retained. The receiver can extract the pulse pilot within the extended region. Due to the circular convolution characteristic of the two-dimensional transformation between the time-delay-Doppler domain and the time-frequency domain, the receiver can use the least squares or least mean square error method to perform channel estimation on the extracted pilot in the time-delay-Doppler domain.

[0051] Because the ZC sequence has a constant envelope, this method can significantly reduce the peak-to-average power ratio (PAPR) of the pilot signal. However, since this method extends the signal in the time delay domain, it requires the channel to be a linear time-invariant channel within the pilot delay.

[0052] Therefore, single-antenna pilot signals in current pulse embedded pilot signals cannot realize MIMO and multiple access technologies; multi-antenna pilot signals either consume more resources, or there is signal interference between pilots, or the applicable range of the signal is narrow and there are special requirements for the channel.

[0053] In view of this, the present invention provides an OTFS embedded sequence pilot signal. By placing at least one ZC sequence in the same position along the Doppler domain instead of extending it along the time delay domain, it can realize MIMO technology and multiple access technology, and avoid the problems of narrow applicability, high resource consumption and difficulty in channel equalization caused by extending it in the time delay domain. The ZC sequences placed in the same position can also avoid the problem of signal interference between pilots.

[0054] The present invention will be further described in detail below with reference to specific embodiments, but the implementation of the present invention is not limited thereto.

[0055] Example 1

[0056] Figure 4 The diagram shown is a structural schematic of an OTFS embedded sequence pilot signal provided in an embodiment of the present invention.

[0057] See, as an example rather than a limitation. Figure 4 The pilot signal may include a one-dimensional ZC sequence group 1 extended along the Doppler domain, a zero protection zone 2, and a time delay protection zone 3.

[0058] In some embodiments, see Figure 4 In (a) of the transmitted signal, the one-dimensional ZC sequence group 1 may include at least one set of ZC sequences placed in the same position (only one is shown here). The ZC sequences extend along the Doppler domain to fill the Doppler domain.

[0059] The zero-protection zone 1 may include a first zero-protection zone 21 and a second zero-protection zone 22. The first zero-protection zone 21 may be set along the time delay domain before the one-dimensional ZC sequence group 1 to prevent the time delay Doppler spread of the preceding signal after passing through the channel from interfering with the pilot signal. The second zero-protection zone 22 may be set along the time delay domain after the one-dimensional ZC sequence group 1, so that the pilot signal can have spread space after passing through the channel, retaining the spread information, while ensuring that it will not interfere with the subsequent signal part.

[0060] The delay protection zone 3 can be set before the first zero protection zone along the delay domain to prevent interference from the previous transmitted signal.

[0061] Optionally, the lengths of the first zero protection zone 21 and the second zero protection zone 22 in the time delay domain need to be at least greater than the maximum time delay spread of the channel.

[0062] For example, when a one-dimensional ZC sequence group is transmitted through a channel, due to channel time dispersion, the ZC sequence will appear in the grid after the time delay; due to channel frequency dispersion, the sequence will be shifted along the Doppler domain. Therefore, see Figure 4 In (b) of the received signal, the one-dimensional ZC sequence group 1 will be extended in the time delay domain and Doppler domain in the part of the second zero protection zone, and the signal in the extended region 4 can be extracted for channel estimation.

[0063] Due to the two-dimensional cyclic property of the symmetric Fourier transform, Figure 4 The portion of the data that extends beyond the Doppler domain will appear in the corresponding part of its loop; see [link to relevant documentation]. Figure 5 Because ZC sequences have two-dimensional circular convolution properties, the integer Doppler shift of each ZC sequence along the Doppler domain can be estimated using this property during channel estimation.

[0064] In one possible implementation, when implementing multiple access and MIMO technologies, the pilot portion corresponding to each user signal in the transmitted signal needs to have a certain degree of differentiation; therefore, when a one-dimensional ZC sequence group includes multiple ZC sequences, every two ZC sequences are orthogonal to each other.

[0065] For example, a ZC sequence can satisfy the following formula:

[0066] xu(i)=e-jπui(i+1) / L RA i = 0, 1, ..., LRA-1

[0067] Where xu(i) is the i-th element in the ZC sequence with root index u, and LRA is the root index length of the ZC sequence (i.e., the length of the ZC sequence).

[0068] For example, the ZC sequence is a discrete complex sequence with good properties, often used in random access to generate preamble sequences. Two important parameters of the ZC sequence are the physical root index *u*, which can be obtained by looking up the logical root index in a table; and the length of the ZC sequence is generally odd, often a prime number. By selecting the root index of each ZC sequence according to a certain rule, and inputting the different selected root indexes into the above formula, different ZC sequences with orthogonality can be obtained.

[0069] In one possible implementation, due to the periodicity of the ZC sequence, the ZC sequence can be cyclically shifted to obtain a ZC sequence with a certain degree of distinguishability. A one-dimensional ZC sequence group is generated from multiple cyclically shifted ZC sequences, thereby realizing multiple access technology and MIMO technology.

[0070] For example, the cyclically shifted ZC sequence can satisfy the following formula:

[0071] x(u,k)(i)=e-jπu(i+k)(i+k+1) / L RA i = 0, 1, ..., LRA-1

[0072] Here, x(u,k)(i) is the i-th element in the ZC sequence with root index u and cyclic shift number k. By changing the value of k, ZC sequences with different cyclic shifts can be generated to avoid interference between ZC sequences.

[0073] In one example, to minimize the interference probability of channel estimation results between adjacent ZC sequences in the Doppler domain, their channel responses need to be as far apart as possible in the time-delay Doppler domain. Therefore, when selecting ZC sequences with different cyclic shifts, the cyclic shift difference between two adjacent ZC sequences can be equal to... N is the number of ZC sequences. For example, when there are two ZC sequences, one of the sequences needs to be cyclically shifted by L. RA / 2 points. Since the ZC sequences are placed in the same position, in a one-dimensional ZC sequence set, this is represented by a cyclic shift difference between every two ZC sequences being greater than or equal to 2.

[0074] Because this invention uses at least one ZC sequence with the same placement position that is extended only in the Doppler domain to generate pilot signals, instead of extending pulse pilots along the time delay domain, communication using the pilot signals provided by this invention can realize MIMO technology and multiple access technology, while avoiding the problems of narrow applicability, high resource consumption, and difficulty in signal equalization caused by extension in the time delay domain; the ZC sequences with the same placement position can also avoid the problem of signal interference between pilots.

[0075] Example 2

[0076] Figure 6 The diagram shown is a schematic of a transmission signal based on an OTFS embedded sequence pilot signal provided by the present invention.

[0077] In one possible implementation, see Figure 6 The header of the transmitted signal may include the OTFS embedded sequence pilot signal provided in Embodiment 1 of the present invention. The one-dimensional ZC sequence group in the pilot signal shows three ZC sequences placed in the same position. The load portion of the pilot signal may contain the specific information to be transmitted.

[0078] In one example, see Figure 7 When a ZC sequence group comprises multiple ZC sequences, the signal can be divided into different resource blocks along the time delay domain; alternatively, it can be divided along the Doppler domain (excluding the pilot signal), or a hybrid division can be used, with each region carrying data (i.e., user signals) transmitted to different users. One ZC sequence can correspond to one user signal, used to identify the corresponding user signal; different user signals have different target receivers. The receiver can perform frequency domain equalization on the extended region of the received signal to perform channel estimation, obtaining the impulse response of the pilot signal, thereby determining whether any of these user signals are targeted at its own user signal.

[0079] For example, see Figure 7 ZC sequence 1 corresponds to user signal 1, ZC sequence 2 corresponds to user signal 2, and ZC sequence 3 corresponds to user signal 3.

[0080] Optionally, when the ZC sequences are orthogonal to each other, the specific position and magnitude of the user signal in the received signal can be indicated by other methods. When the ZC sequence is a sequence with a cyclic shift difference, the channel pulse position of the ZC sequence at the receiving end itself contains some information, which can be used to carry the position and magnitude information of each user signal.

[0081] Example 3

[0082] Figure 8 The diagram illustrates the implementation flow of a channel estimation method based on OTFS embedded sequence pilot signals according to an embodiment of the present invention. As an example and not a limitation, method 800 can be applied to a receiver. Method 800 may include steps S801-S803, which are described below.

[0083] S801 performs a Fourier transform along the Doppler domain on the extended region of the received signal to obtain the transformed received signal.

[0084] In one example, see Figure 9Taking a ZC sequence as an example, the ZC sequence in the extended region of the received signal can be extracted, corresponding to the 901 part in the transmitted signal; then, it is processed by an N-point Fourier Transform (FFT) along the Doppler domain to transform it into the frequency domain of the Doppler domain to obtain the transformed received signal.

[0085] For example, the extended region includes the location of the one-dimensional ZC sequence set and the second zero protection zone.

[0086] For example, the received signal may be the transmitted signal received through the channel in Embodiment 2.

[0087] S802 performs frequency domain estimation on the transformed received signal to obtain the frequency domain estimation result.

[0088] In one example, the frequency domain estimation result can be obtained by performing frequency domain estimation on the transformed received signal based on the local ZC sequence using the Least Squares Method (LS) or the Minimum Mean Squared Error (MMSE) method.

[0089] S803 performs an inverse Fourier transform on the frequency domain estimation results to obtain the impulse response of the pilot signal.

[0090] For example, see Figure 9 After performing an inverse fast fourier transform (IFFT) on the frequency domain estimation results, the input can be obtained. Figure 9 The impulse response shown in Figure 902.

[0091] If the one-dimensional ZC sequence group in the pilot signal of the transmitted signal contains only one ZC sequence, the receiver can directly identify whether the user signal corresponding to the pilot signal is its own target user signal based on the impulse response of the pilot signal. If it contains multiple ZC sequences, step S804 is also required.

[0092] S804 separates and identifies the ZC sequence based on the impulse response of the pilot signal to determine whether the target user signal exists in the user signal.

[0093] In one example, if the transmitting and receiving ends are a MIMO system, a system model can be established. In the system model, each transmit antenna to each receive antenna has a corresponding channel response. Therefore, after the cyclic prefix of the signal, the relationship between the transmitting and receiving ends can be established using a time-domain channel matrix.

[0094] For example, a MIMO system model can satisfy the following formula:

[0095]

[0096] Where r(r) is the signal received by the r-th receiving antenna at the receiver, nT is the number of transmitting antennas at the transmitter, G(r,t) is the channel response between the r-th receiving antenna and the t-th transmitting antenna, s(t) is the transmitted signal of the t-th transmitting antenna, and w(r) is the received noise of the r-th receiving antenna.

[0097] For example, the input-output relationship of a 2×2 MIMO system can be expressed as:

[0098]

[0099] Similarly, an equivalent MIMO system model can be established in the time-delay Doppler domain:

[0100]

[0101] Where rm(r) is the signal received by the r-th receiving antenna at the receiver in the time-delay Doppler domain MIMO system. The equivalent channel response of the r-th receiving antenna and the t-th transmitting antenna on the l-th path in the time-delay Doppler domain. For the transmitted signal of the t-th transmit antenna in a time-delayed Doppler domain MIMO system, Let be the received noise of the r-th receiving antenna in a time-delay Doppler domain MIMO system.

[0102] The ZC sequence can be separated and identified by using the time-delay Doppler domain MIMO system model, thereby determining whether the target user signal of the receiver is present in the user signal.

[0103] Because this invention uses at least one ZC sequence with the same placement position that is extended only in the Doppler domain to generate pilot signals, instead of extending pulse pilots along the time delay domain, the channel estimation method provided by this invention can avoid the complex calculation of superimposed pilots, realize MIMO technology and multiple access technology, and avoid the problems of narrow applicability and high resource consumption caused by extension in the time delay domain. The ZC sequence with the same placement position can also avoid the problem of signal interference between pilots, thereby ensuring estimation performance.

[0104] Example 4

[0105] Figure 10 The diagram shown is a schematic representation of a receiver provided in an embodiment of the present invention.

[0106] As an example and not a limitation, the receiver may include a Fourier transform module 101 and a frequency domain estimation module 102.

[0107] The Fourier transform module 101 is used to perform Fourier transform on the extended region of the received signal along the Doppler domain to obtain the transformed received signal.

[0108] The received signal is the transmitted signal, as in Example 2, that has been received and transmitted through the channel.

[0109] The frequency domain estimation module 102 is used to perform frequency domain estimation on the transformed received signal to obtain the frequency domain estimation result;

[0110] The Fourier transform module 101 is also used to perform an inverse Fourier transform on the frequency domain estimation results to obtain the impulse response of the pilot signal.

[0111] In one possible implementation, if a one-dimensional ZC sequence group comprises multiple ZC sequences, then these ZC sequences are mutually orthogonal.

[0112] In another possible implementation, if the one-dimensional ZC sequence group includes multiple ZC sequences, then these ZC sequences have different cyclic shifts.

[0113] In one example, the cyclic shift difference between any two ZC sequences is greater than or equal to the quotient of the length of the ZC sequence and the number of ZC sequences.

[0114] To better illustrate the beneficial effects of the present invention, the following simulation experiments were conducted:

[0115] Simulation Experiment 1

[0116] The transmitter selects two ZC sequences with the same root index but different cyclic shifts to generate pilot signals. The simulated channel environment is a non-line-of-sight (NLos) channel. The root index u = 1 for the ZC sequences, the sequence length LRA = 128, the cyclic shift of sequence 1 is 32 points, and the cyclic shift of sequence 2 is 96 points.

[0117] For example, sequence 1 and sequence 2 satisfy the formulas: x(1,32)(i)=e-jπ(i+32)(i+33) / 128,i=0,1,...,127 and x(1,96)(i)=e-jπ(i+96)(i+96) / 128,i=0,1,...,127, respectively.

[0118] Figure 11 The diagram shown is a schematic representation of the pulse response of a pilot signal provided in an embodiment of the present invention.

[0119] For example, the receiver can sequentially extract the ZC sequence within the extended region of the received signal along the Doppler domain for channel estimation. The local sequence is estimated in the frequency domain using x(1,0)(i), i=0,1,...,127, as shown below. Figure 11 The diagram shows the impulse response of the pilot signal, where Doppler represents the Doppler domain and Delay represents the time delay domain.

[0120] See Figure 11 According to the number of cyclic shift points of the ZC sequence in the pilot signal, Figure 11 The impulse response in the Doppler domain is separated at point 64. The impulse responses shown in the red and green boxes are used as the channel estimation results for the two transmitting antennas.

[0121] As can be seen from the figure, the Doppler spread is small in the simulated channel environment (the Doppler spread of the channel in the simulation is ±4 points), and there is no mutual influence between adjacent estimation results. If the Doppler spread of the channel exceeds the estimation region, it will have a significant impact on adjacent estimation results, and this cyclic shift sequence cannot be used.

[0122] Compared to pulse pilots, the channel estimation method provided by this invention can directly distinguish whether data is being sent to the local receiver by different ZC sequences. Furthermore, using this method to implement MIMO and multiple access technologies does not conflict with pulse pilots, and it saves more resources and offers greater flexibility. For example, different shifts of the same sequence can be used to implement MIMO, and orthogonal sequences can be used to distinguish multiple users.

[0123] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0124] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

Claims

1. A channel estimation method based on OTFS embedded sequence pilot signals, characterized in that, The method is applied at the receiving end, and the method includes: The received signal is obtained by performing a Fourier transform along the Doppler domain on the extended region of the received signal. The received signal is a transmitted signal received through the channel. The transmitted signal includes an OTFS embedded sequence pilot signal and a user signal. The OTFS embedded sequence pilot signal includes: a one-dimensional ZC sequence group extended along the Doppler domain, a zero-protection zone, and a time delay protection zone. The one-dimensional ZC sequence group includes at least one ZC sequence placed in the same position, and the ZC sequence corresponds one-to-one with the user signal to identify the user signal. The zero-protection zone includes a first zero-protection zone and a second zero-protection zone, which are respectively set before and after the one-dimensional ZC sequence group along the time delay domain. The time delay protection zone is set before the first zero-protection zone along the time delay domain. The extended region of the received signal includes the ZC sequence group and the second zero-protection zone. The frequency domain estimation is performed on the transformed received signal to obtain the frequency domain estimation result; The frequency domain estimation result is subjected to inverse Fourier transform to obtain the impulse response of the pilot signal; The one-dimensional ZC sequence group includes multiple ZC sequences placed in the same position and orthogonal to each other; or, the one-dimensional ZC sequence group includes multiple ZC sequences placed in the same position but with different cyclic shifts, and the cyclic shift difference between any two ZC sequences is greater than or equal to the quotient of the length of the ZC sequence and the number of ZC sequences.

2. The method according to claim 1, characterized in that, The method further includes: The ZC sequence is separated and identified based on the impulse response of the pilot signal to determine whether a target user signal exists in the user signal.

3. A receiving end, characterized in that, include: The Fourier transform module is used to perform a Fourier transform on the extended region of the received signal along the Doppler domain to obtain the transformed received signal. The received signal is a transmitted signal received through the channel. The transmitted signal includes an OTFS embedded sequence pilot signal and a user signal. The OTFS embedded sequence pilot signal includes: a one-dimensional ZC sequence group extended along the Doppler domain, a zero-protection zone, and a time delay protection zone. The one-dimensional ZC sequence group includes at least one ZC sequence placed in the same position, and the ZC sequence corresponds one-to-one with the user signal to identify the user signal. The zero-protection zone includes a first zero-protection zone and a second zero-protection zone, which are respectively set before and after the one-dimensional ZC sequence group along the time delay domain. The time delay protection zone is set before the first zero-protection zone along the time delay domain. The extended region of the received signal includes the ZC sequence group and the second zero-protection zone. A frequency domain estimation module is used to perform frequency domain estimation on the transformed received signal to obtain a frequency domain estimation result. The Fourier transform module is also used to perform an inverse Fourier transform on the frequency domain estimation result to obtain the impulse response of the pilot signal; The one-dimensional ZC sequence group includes multiple ZC sequences placed in the same position and orthogonal to each other; or, the one-dimensional ZC sequence group includes multiple ZC sequences placed in the same position but with different cyclic shifts, and the cyclic shift difference between any two ZC sequences is greater than or equal to the quotient of the length of the ZC sequence and the number of ZC sequences.

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