OTFS embedded sequence pilot signal, channel estimation method based on OTFS embedded sequence pilot signal and receiving end

Abstract

The invention discloses an OTFS embedded sequence pilot signal, a channel estimation method based on the OTFS embedded sequence pilot signal and a receiving end. The pilot signal comprises a one-dimensional ZC sequence group extending 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. At least one ZC sequence is placed at the same position along a Doppler domain instead of being expanded along a time delay domain, so that the pilot signal provided by the invention not only can realize an MIMO (Multiple Input Multiple Output) technology and a multiple access technology, but also can avoid the problems of narrower application range, more consumed resources, difficulty in balancing channels and the like caused by expansion in the time delay domain; the ZC sequences placed at the same position can also avoid the problem of signal interference between pilot frequencies.

Description

Technical Field

[0001] The present invention belongs to the technical field of wireless communications, and in particular relates to an OTFS embedded sequence pilot signal and a channel estimation method and a receiving end based thereon. Background Art

[0002] With the large-scale deployment and application of high-speed rail, satellites, and high-speed or even ultra-high-speed aircraft, wireless communications in high-latency and strong Doppler channel environments face great challenges. In such channel environments, traditional orthogonal frequency division multiplexing (OFDM) systems will be affected by strong Doppler, resulting in a sharp decline in system performance. In recent years, the introduction and development of orthogonal time-frequency space modulation (OTFS) technology has provided an implementable method to solve these problems.

[0003] Unlike the OFDM system, which modulates the signal in the time-frequency domain, OTFS distributes the signal to the delay-Doppler domain through two-dimensional transformation and converts the symbol to the time-frequency domain for transmission. This method adopted by OTFS allows the receiver to process the signal in the delay-Doppler domain, which also makes OTFS technology have excellent performance in fast time-varying channels.

[0004] There are currently two types of pilot methods used in OTFS channels, one is superimposed pilot and the other is embedded pilot. Superimposed pilot is to superimpose the pilot signal on the service signal. Therefore, it is necessary to eliminate the interference between the pilot signal and the service signal during channel estimation, and the signal processing process is relatively complicated. The embedded pulse pilot processing method is simple and requires zero protection to be retained around the pulse. However, the currently popular pulse embedded pilot method cannot implement MIMO technology or multiple access technology. The embedded pilot method extended along the delay domain will interfere with the data domain signal, making channel estimation and equalization difficult.

[0005] Therefore, the current pilot signal processing process is either difficult and complicated, or the MIMO technology and multiple access technology cannot be implemented when performing channel estimation. Summary of the invention

[0006] The embodiment of the present invention provides an OTFS embedded sequence pilot signal and a channel estimation method and a receiving end based thereon, which can solve the problem that the current pilot signal is either difficult and complicated to process or cannot implement MIMO technology and multiple access technology when performing channel estimation.

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

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

[0009] A zero protection zone, the zero protection zone includes a first zero protection zone and a second zero protection zone, the first zero protection zone and the second zero protection zone are respectively arranged before and after the one-dimensional ZC sequence group along the delay domain;

[0010] A delay protection zone is provided along the delay domain before the first zero protection zone.

[0011] In a second aspect, an embodiment of the present invention provides a channel estimation method based on an OTFS embedded sequence pilot signal, comprising:

[0012] Performing Fourier transform on the extended area of ​​the received signal along the Doppler domain to obtain a transformed received signal;

[0013] The received signal is a received transmission signal transmitted through a channel, and the transmission 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, a zero protection zone, and a delay protection zone extending along a Doppler domain; the one-dimensional ZC sequence group includes at least one ZC sequence placed in the same position, and the ZC sequence corresponds to the user signal one-to-one and is used to identify the user signal; the zero protection zone includes a first zero protection zone and a second zero protection zone, and the first zero protection zone and the second zero protection zone are respectively arranged before and after the one-dimensional ZC sequence group along the delay domain; the delay protection zone is arranged before the first zero protection zone along the delay domain, and the extended area of ​​the received signal includes the ZC sequence group and the second zero protection zone;

[0014] Performing frequency domain estimation on the transformed received signal to obtain a frequency domain estimation result;

[0015] Perform inverse Fourier transform on the frequency domain estimation result to obtain the impulse response of the pilot signal.

[0016] In a third aspect, an embodiment of the present invention provides a receiving end, including:

[0017] A Fourier transform module, which is used to perform Fourier transform on the extended area of ​​the received signal along the Doppler domain to obtain a transformed received signal;

[0018] Among them, the received signal is a received transmission signal transmitted through a channel, and the transmission 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, a zero protection zone and a delay protection zone extended along the Doppler domain; the one-dimensional ZC sequence group includes at least one ZC sequence placed in the same position, and the number of ZC sequences corresponds to the user signal one-to-one, which is used to identify the user signal; the zero protection zone includes a first zero protection zone and a second zero protection zone, and the first zero protection zone and the second zero protection zone are respectively arranged before and after the one-dimensional ZC sequence group along the delay domain; the delay protection zone is arranged before the first zero protection zone along the delay domain, and the extended area of ​​the received signal includes the ZC sequence group and the second zero protection zone;

[0019] A frequency domain estimation module, which is used to perform frequency domain estimation on the transformed received signal to obtain a frequency domain estimation result;

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

[0021] Compared with the prior art, the embodiments of the present invention have the following beneficial effects: by placing at least one ZC sequence at the same position along the Doppler domain instead of extending along the delay domain, the pilot signal provided by the present invention can not only realize MIMO technology and multiple access technology, but also avoid the problems of narrow application scope, high resource consumption, and difficult channel balancing caused by the extension in the delay domain; ZC sequences placed at the same position can also avoid the problem of signal interference between pilots. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0023] Figure 2 is a schematic diagram of a multi-antenna embedded pilot signal;

[0024] Figure 3 is a schematic diagram of a multi-antenna pilot signal extended along a delay domain;

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

[0026] Figure 5 A schematic diagram of cyclic compensation of a pilot signal provided by 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 7A schematic diagram of a ZC sequence orthogonal transmission signal provided by an embodiment of the present invention;

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

[0030] Fig. 9 A schematic diagram of a scenario of a channel estimation method provided by an embodiment of the present invention;

[0031] Fig.10 A schematic diagram of the structure of a receiving end provided by an embodiment of the present invention;

[0032] Fig.11 A schematic diagram of an impulse response of a pilot signal provided by an embodiment of the present invention. DETAILED DESCRIPTION

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

[0034] In one example, see Figure 1 The traditional embedded pulse pilot method is to place the pulse pilot symbol in the delay-Doppler domain and keep zero protection around it. The transmission signal at the transmitter includes Figure 1 The pilot signal shown in (a) in FIG. 1 is transmitted through a time-frequency dual dispersion channel, and the received signal received by the receiving end includes the following: Figure 1 The pilot signal is shown in (b) in Figure 1. The pulse pilot will be expanded when it is transmitted through the channel. The receiving end uses the least square method or the minimum mean square error method to estimate the channel in the delay-Doppler domain.

[0035] Exemplarily, the pilot signal in the received signal may satisfy the following formula:

[0036]

[0037] Among them, ZDD is the pilot signal in the received signal, PDD is the pilot signal in the transmitted signal, HDD is the equivalent channel matrix, is the equivalent noise matrix.

[0038] Exemplary, the channel estimation result obtained by the least squares method is Can satisfy:

[0039]

[0040] Exemplary, the channel estimation result obtained by the minimum mean square error method The following formula can be satisfied:

[0041]

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

[0043] This single-antenna pilot signal cannot be applied to Multiple-Input Multiple-Output (MIMO) technology and multiple access technology, and the communication efficiency is low.

[0044] Figure 2 Shown is a schematic diagram of an embedded pilot signal for multiple antennas.

[0045] For example, see Figure 2 ,The embedded pilot signals of multiple antennas are generally used in MIMO technology and ,multiple access technology, where multiple antennas work in the same channel.

[0046] A conventional multi-antenna pilot signal places pulse pilots at intervals in the delay-Doppler domain, see Figure 2 (a) is the signal frame structure of the 2×2 MIMO-OTFS system based on pulse pilots, where the red and green boxes represent the pilot and zero protection area of ​​each transmitting antenna, respectively, and different pulse pilots are aligned along the delay domain. The receiving end performs corresponding channel estimation according to the extended positions corresponding to different antennas of the transmitting end. However, this pilot structure is not suitable for systems with higher Doppler extension or systems with more antennas, and the pilots in the received signals corresponding to different antennas may interfere with each other.

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

[0048] Another method is to expand the pilot signals corresponding to different antennas along the Doppler domain and the delay domain together, see Figure 2 However, this method has the disadvantages of both methods, signal interference occurs between different pilots and resource consumption is large.

[0049] Figure 3 Shown is a multi-antenna pilot signal spread along the delay domain.

[0050] Exemplarily, a multi-antenna pilot signal extended along the delay domain places a Zadoff Chu (ZC) sequence with a cyclic prefix added in the delay domain, while retaining zero guard regions on both sides of the sequence. Figure 3 (a) in the figure is the pilot signal in the transmitted signal. Figure 3 (b) in the figure is the pilot signal in the received signal. Figure 3 , valid information that can be used for channel estimation will be retained in the extended area of ​​the received signal. The receiving end can extract the pulse pilot in the extended area. Due to the circular convolution characteristics of the two-dimensional transformation between the delay-Doppler domain and the time-frequency domain, the receiving end can use the least squares or minimum mean square error method in the delay-Doppler domain to perform channel estimation on the extracted pilot.

[0051] Since the ZC sequence has the characteristic of constant envelope, this method can significantly reduce the peak-to-average ratio of the pilot signal. However, since this method is extended in the delay domain, it requires that the channel is a linear time-invariant channel within the pilot delay.

[0052] Therefore, the single-antenna pilot signal in the current pulse embedded pilot signal cannot realize MIMO technology and multiple access technology; the multi-antenna pilot signal either consumes more resources, or there is signal interference between pilots, or the signal has a narrow application range and has special requirements for the channel.

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

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

[0055] Example 1

[0056] Figure 4 The figure shows a schematic diagram of the structure of an OTFS embedded sequence pilot signal provided by an embodiment of the present invention.

[0057] By way of example and not limitation, see Figure 4 The pilot signal may include a one-dimensional ZC sequence group 1, a zero protection zone 2 and a delay protection zone 3 extending along the Doppler domain.

[0058] In some embodiments, see Figure 4 In (a), in the pilot signal of the transmitted signal, the one-dimensional ZC sequence group 1 may include at least one group of ZC sequences (only one is shown here) placed in the same position. The ZC sequence extends along the Doppler domain to occupy the entire 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 arranged before the one-dimensional ZC sequence group 1 along the delay domain to prevent the delay Doppler expansion of the previous signal after passing through the channel from interfering with the pilot signal. The second zero protection zone 22 may be arranged after the one-dimensional ZC sequence group 1 along the delay domain, so that the pilot signal can have expansion space after passing through the channel, retain the expansion information, and ensure that it will not interfere with the subsequent signal part.

[0060] The delay protection zone 3 may be arranged before the first zero protection zone along the delay domain to prevent interference from a previously transmitted signal.

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

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

[0063] Due to the two-dimensional cyclic nature of the symplectic Fourier transform, Figure 4 The part outside the Doppler domain will appear in its corresponding part of the cycle, see Figure 5 Since the ZC sequence has a two-dimensional circular convolution characteristic, this characteristic can be used to estimate the integer Doppler of each ZC sequence shifted along the Doppler domain during channel estimation.

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

[0065] Exemplarily, the ZC sequence may satisfy the following formula:

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

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

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

[0069] In a 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 discrimination, and a one-dimensional ZC sequence group is generated by multiple cyclically shifted ZC sequences, thereby realizing multiple access technology and MIMO technology.

[0070] Exemplarily, the cyclically shifted ZC sequence may satisfy the following formula:

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

[0072] Wherein, x(u,k)(i) is the i-th element in the ZC sequence with root index u and cyclic shift point 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, in order to minimize the interference probability of channel estimation results between adjacent ZC sequences in the Doppler domain, it is necessary to make their channel responses as far apart as possible in the 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 two ZC sequences are included, one of the sequences needs to be cyclically shifted by L. RA / 2 points. Since the ZC sequences are placed at the same position, the cyclic shift difference between every two ZC sequences in the one-dimensional ZC sequence group is greater than or equal to

[0074] Since the present invention uses at least one ZC sequence with the same placement position only in the Doppler domain expansion to generate a pilot signal, rather than expanding the pulse pilot along the delay domain; therefore, according to the pilot signal provided by the present invention, communication can not only realize MIMO technology and multiple access technology, but also avoid the problems of narrow application range, high resource consumption, and difficult signal balancing caused by the delay domain expansion; ZC sequences with the same placement position can also avoid the problem of signal interference between pilots.

[0075] Example 2

[0076] Figure 6 Shown is a schematic diagram 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 by Embodiment 1 of the present invention. The one-dimensional ZC sequence group in the pilot signal shows three ZC sequences with the same placement. The payload part in the pilot signal may contain specific information to be transmitted.

[0078] In one example, see Figure 7 When the ZC sequence group includes multiple ZC sequences, the signal can be divided into different resource blocks along the delay domain; it can also be divided along the Doppler domain except for the pilot signal, or mixed division is performed, and each area carries data (i.e., user signals) transmitted to different users. A ZC sequence can correspond to a user signal and is used to identify the user signal corresponding to it. Different user signals have different target receiving ends. The receiving end can perform frequency domain equalization processing on the extended area of ​​the received signal to perform channel estimation on it, and obtain the impulse response of the pilot signal, so as to determine whether there is a target user signal with its own target receiving end among these user signals.

[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 mutually orthogonal, the specific position and size 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 a part of information, and this position information can be used to carry the position and size information of each user signal.

[0081] Example 3

[0082] Figure 8 The figure shows a schematic diagram of an implementation flow of a channel estimation method based on an OTFS embedded sequence pilot signal provided by an embodiment of the present invention. As an example but not a limitation, the method 800 can be applied to a receiving end, and the method 800 can include steps S801-S803, and each step is described below.

[0083] S801, performing Fourier transform on the extended area of ​​the received signal along the Doppler domain to obtain a transformed received signal.

[0084] In one example, see Fig. 9Taking a ZC sequence as an example, the ZC sequence in the extended area of ​​the received signal can be extracted, corresponding to the 901 part in the transmitted signal; then, N-point Fourier transform (Fast Fourier Transformation, FFT) processing is performed on it in sequence along the Doppler domain, and it is converted to the frequency domain of the Doppler domain to obtain the transformed received signal.

[0085] Exemplarily, the extended area includes the location where the one-dimensional ZC sequence group is located and the second zero protection zone.

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

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

[0088] In an 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 through the Least Squares Method (LS) or the Minimum Mean Squared Error (MMSE).

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

[0090] For example, see Fig. 9 After performing inverse Fourier transform (IFFT) on the frequency domain estimation result, we can get the input Fig. 9 The impulse response shown in 902.

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

[0092] S804, separating and identifying the ZC sequence according to the impulse response of the pilot signal to determine whether there is a target user signal in the user signal.

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

[0094] Exemplarily, the MIMO system model may satisfy the following formula:

[0095]

[0096] Where r(r) is the signal received by the rth receiving antenna at the receiving end, nT is the number of transmitting antennas at the transmitting end, G(r,t) is the channel response between the rth receiving antenna and the tth transmitting antenna, s(t) is the transmitted signal of the tth transmitting antenna, and w(r) is the receiving noise of the rth 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 delay-Doppler domain:

[0100]

[0101] Where rm(r) is the signal received by the rth receiving antenna in the MIMO system in the delay-Doppler domain. is the equivalent channel response of the lth path between the rth receiving antenna and the tth transmitting antenna in the delay-Doppler domain, is the transmitted signal of the tth transmitting antenna in the MIMO system in the delay-Doppler domain, is the receiving noise of the rth receiving antenna in the MIMO system in the delay-Doppler domain.

[0102] The MIMO system model in the delay-Doppler domain can be used to separate and identify the ZC sequence, thereby determining whether the target user signal at the receiving end exists in the user signal.

[0103] Since the present invention uses at least one ZC sequence with the same placement position only in the Doppler domain expansion to generate a pilot signal instead of extending the pulse pilot along the delay domain; therefore, according to the channel estimation method provided by the present invention, the complex calculation of superimposed pilots can be avoided to realize MIMO technology and multiple access technology; and the problems of narrow application scope and high resource consumption caused by the delay domain expansion can be avoided; ZC sequences with the same placement position can also avoid the problem of signal interference between pilots, thereby ensuring the estimation performance.

[0104] Example 4

[0105] Fig.10 Shown is a schematic structural diagram of a receiving end provided by an embodiment of the present invention.

[0106] As an example but not limitation, the receiving end 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 area of ​​the received signal along the Doppler domain to obtain a transformed received signal;

[0108] The received signal is the received sending signal transmitted through the channel as in Example 2.

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

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

[0111] In a possible implementation, if the one-dimensional ZC sequence group includes multiple ZC sequences, these ZC sequences are orthogonal to each other.

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

[0113] In an example, the cyclic shift difference between every 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] In order to better illustrate the beneficial effects of the present invention, the following simulation experiments were carried out:

[0115] Simulation experiment 1

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

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

[0118] Fig.11 Shown is a schematic diagram of an impulse response of a pilot signal provided by an embodiment of the present invention.

[0119] For example, the receiving end can sequentially extract the ZC sequence in 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, and the following is obtained: Fig.11 The impulse response of the pilot signal is shown in FIG. 1 , where Doppler represents the Doppler domain and Delay represents the delay domain.

[0120] See also Fig.11 , according to the number of cyclic shift points of the ZC sequence in the pilot signal Fig.11 The impulse responses in are separated at the 64th point along the Doppler domain, and the obtained impulse responses shown in the red and green boxes are used as the channel estimation results of the two transmitting antennas.

[0121] As can be seen from the figure, in the simulated channel environment, the Doppler spread is not large (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 area, it will have a greater impact on the adjacent estimation results, and this cyclic shift sequence cannot be used.

[0122] Compared with pulse pilot, the channel estimation method provided by the present invention can directly distinguish different ZC sequences at the receiving end of different users to distinguish whether the data is sent to the local area. At the same time, there is no conflict in using this method to implement MIMO technology and multiple access technology. Compared with pulse pilot, it can save more resources and have greater flexibility. For example, different shifts of the same sequence can be used to implement MIMO technology, and orthogonal sequences can be used to distinguish multiple users.

[0123] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0124] Those skilled in the art will appreciate that the units and algorithm steps of each example 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 performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

Claims

1. An OTFS embedded sequence pilot signal, It is characterized in that include: A one-dimensional ZC sequence group extending along the Doppler domain, wherein the one-dimensional ZC sequence group includes at least one ZC sequence placed at the same position; A zero protection zone, wherein the zero protection zone comprises a first zero protection zone and a second zero protection zone, wherein the first zero protection zone and the second zero protection zone are respectively arranged before and after the one-dimensional ZC sequence group along a delay domain; A delay protection zone is provided along the delay domain before the first zero protection zone.

2. The OTFS embedded sequence pilot signal according to claim 1, It is characterized in that The one-dimensional ZC sequence group includes a plurality of ZC sequences that are placed at the same position and are orthogonal to each other.

3. The OTFS embedded sequence pilot signal according to claim 1, It is characterized in that The one-dimensional ZC sequence group includes a plurality of ZC sequences with the same placement position and different cyclic shifts.

4. The OTFS embedded sequence pilot signal according to claim 3, It is characterized in that The cyclic shift difference between every two ZC sequences is greater than or equal to the quotient of the length of the ZC sequence and the number of the ZC sequences.

5. A channel estimation method based on OTFS embedded sequence pilot signal, It is characterized in that The method is applied to a receiving end, and the method comprises: Performing Fourier transform on the extended area of ​​the received signal along the Doppler domain to obtain a transformed received signal; The received signal is a received transmission signal transmitted through a channel, the transmission 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, a zero protection zone, and a delay protection zone extended along a Doppler domain; the one-dimensional ZC sequence group includes at least one ZC sequence placed in the same position, the ZC sequence corresponds to the user signal one-to-one, and is used to identify the user signal; the zero protection zone includes a first zero protection zone and a second zero protection zone, the first zero protection zone and the second zero protection zone are respectively arranged before and after the one-dimensional ZC sequence group along the delay domain; the delay protection zone is arranged before the first zero protection zone along the delay domain, and the extended area of ​​the received signal includes the ZC sequence group and the second zero protection zone; Performing frequency domain estimation on the transformed received signal to obtain a frequency domain estimation result; Performing inverse Fourier transform on the frequency domain estimation result to obtain the impulse response of the pilot signal.

6. The method according to claim 5, It is characterized in that The one-dimensional ZC sequence group includes a plurality of ZC sequences that are placed at the same position and are orthogonal to each other.

7. The method according to claim 5, It is characterized in that The one-dimensional ZC sequence group includes a plurality of ZC sequences with the same placement position and different cyclic shifts.

8. The method according to claim 5, It is characterized in that The cyclic shift difference between every two ZC sequences is greater than or equal to the quotient of the length of the ZC sequence and the number of the ZC sequences.

9. The method according to any one of claims 6 to 8, It is characterized in that The method further comprises: The ZC sequence is separated and identified according to the impulse response of the pilot signal to determine whether a target user signal exists in the user signal.

10. A receiving end, It is characterized in that include: A Fourier transform module, wherein the Fourier transform module is used to perform Fourier transform on the extended area of ​​the received signal along the Doppler domain to obtain a transformed received signal; The received signal is a received transmission signal transmitted through a channel, the transmission 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, a zero protection zone and a delay protection zone extended along a Doppler domain; the one-dimensional ZC sequence group includes at least one ZC sequence placed in the same position, the number of the ZC sequences corresponds to the user signal one-to-one, and is used to identify the user signal; the zero protection zone includes a first zero protection zone and a second zero protection zone, the first zero protection zone and the second zero protection zone are respectively arranged before and after the one-dimensional ZC sequence group along the delay domain; the delay protection zone is arranged before the first zero protection zone along the delay domain, and the extended area of ​​the received signal includes the ZC sequence group and the second zero protection zone; A frequency domain estimation module, wherein the 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 further used to perform inverse Fourier transform on the frequency domain estimation result to obtain the impulse response of the pilot signal.

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