Channel estimation method and device

Abstract

The embodiment of the invention discloses a channel estimation method and device. The method is applied to a transmitting end, and comprises the following steps: the transmitting end determines a plurality of first pilot frequency symbols in a time-frequency domain, the plurality of first pilot frequency symbols are located on different carriers of the same time slot, and one of two first pilot frequency symbols located on adjacent carriers is a positive pulse, and the other one is a negative pulse; and performing channel estimation according to the plurality of first pilot symbols. According to the mode, the inter-carrier interference can be reduced, and the accuracy of channel estimation is improved.

Description

Technical Field

[0001] The present application relates to the field of communication technology, and in particular to a channel estimation method and device. Background Art

[0002] In the future, the communication of highly mobile terminal devices such as drones, autonomous driving, high-speed trains, and low-orbit satellites will have requirements for high data transmission rate and low latency. In order to improve the spectrum efficiency of such highly mobile terminal communications, an orthogonal time-frequency space (OTFS) modulation system is proposed.

[0003] However, in the OTFS system, when high-speed moving terminal devices communicate with each other, Doppler frequency shift still exists, which brings inter-carrier interference (ICI) to the OTFS waveform, thereby affecting the accuracy of channel estimation. Summary of the invention

[0004] The embodiments of the present application provide a channel estimation method and device, which can reduce inter-carrier interference and improve the accuracy of channel estimation.

[0005] In a first aspect, an embodiment of the present application provides a channel estimation method. The method is applied to a transmitting end, and the method includes: the transmitting end determines multiple first pilot symbols in the time-frequency domain, the multiple first pilot symbols are located on different carriers in the same time slot, and one of the two first pilot symbols located on adjacent carriers is a positive pulse and the other is a negative pulse. The transmitting end performs channel estimation based on the multiple first pilot symbols.

[0006] It can be seen that the multiple first pilot symbols used by the transmitting end for channel estimation are located on different carriers in the same time slot, and one of the two first pilot symbols located on adjacent carriers is a positive pulse and the other is a negative pulse. Therefore, the carrier interference between the two first pilot symbols located on adjacent carriers in the same time slot can cancel each other, that is, reduce the inter-carrier interference, and further improve the accuracy of channel estimation.

[0007] In addition, compared with the use of a single-pulse pilot symbol for channel estimation at the transmitting end, the multiple first pilot symbols used by the transmitting end are positive and negative pulse pairs, which can reduce the peak-to-average ratio.

[0008] In an optional implementation, the multiple first pilot symbols are pilot symbols in an orthogonal time-frequency-space (OTFS) system. Thus, the transmitting end can use the multiple first pilot symbols to perform channel estimation on a channel in the OTFS system.

[0009] In an optional implementation, the transmitting end determines multiple first pilot symbols in the time-frequency domain, including: superimposing N delay-Doppler DD domain grids to obtain first information, where N is an integer greater than or equal to 1; performing an inverse symplectic finite Fourier transform ISFFT on the first information to obtain multiple first pilot symbols in the time-frequency domain.

[0010] It can be seen that the multiple first pilot symbols are obtained by performing ISFFT on the first information, and the first information is obtained by superimposing N DD domain grids.

[0011] In an optional implementation, the dimension of each DD domain grid in the N DD domain grids is M×N, where N is equal to the number of blocks included in an orthogonal time-frequency space OTFS frame, and M is equal to the number of OTFS symbols included in each block in an OTFS frame. Each of the N DD domain grids includes N subgrids, and the dimension of each subgrid in the N subgrids is M2×2.

[0012] Among N DD domain grids, each sub-grid in the first DD domain grid satisfies: the first row and the first column are resources occupied by negative pulse pilot symbols; among N DD domain grids, each sub-grid in the Nth DD domain grid satisfies: the first row and the first column are resources occupied by positive pulse pilot symbols; among N DD domain grids, each sub-grid from the second DD domain grid to the N-1th DD domain grid are resources occupied by data symbols.

[0013] In a second aspect, an embodiment of the present application provides a channel estimation device, the device comprising:

[0014] A determining unit, configured to determine a plurality of first pilot symbols in the time-frequency domain, wherein the plurality of first pilot symbols are located on different carriers in the same time slot, and one of two first pilot symbols located on adjacent carriers is a positive pulse and the other is a negative pulse;

[0015] The channel estimation unit is used to perform channel estimation according to the multiple first pilot symbols.

[0016] Optionally, the channel estimation device also includes a communication unit, and the communication unit is used to receive or send data.

[0017] In addition, in this aspect, other optional implementations of the channel estimation device can refer to the relevant content of the first aspect mentioned above, and will not be described in detail here.

[0018] In a third aspect, an embodiment of the present application provides a terminal device, the terminal device comprising a memory and a processor; optionally, the terminal device further comprises a communication interface;

[0019] Memory for storing computer programs;

[0020] Communication interface, used to receive or send data;

[0021] The processor is used to call the program instructions stored in the memory.

[0022] The processor calls a computer program to perform the following operations:

[0023] Determine a plurality of first pilot symbols in the time-frequency domain, wherein the plurality of first pilot symbols are located on different carriers in the same time slot, and one of two first pilot symbols located on adjacent carriers is a positive pulse and the other is a negative pulse;

[0024] Channel estimation is performed according to the multiple first pilot symbols.

[0025] In addition, in this aspect, other optional implementations of the terminal device can refer to the relevant content of the first aspect mentioned above and will not be described in detail here.

[0026] In a fourth aspect, an embodiment of the present application provides a network device, the network device comprising a memory and a processor; optionally, the network device further comprises a communication interface;

[0027] Memory for storing computer programs;

[0028] Communication interface, used to receive or send data;

[0029] The processor is used to call the program instructions stored in the memory.

[0030] The processor calls a computer program to perform the following operations:

[0031] Determine a plurality of first pilot symbols in the time-frequency domain, wherein the plurality of first pilot symbols are located on different carriers in the same time slot, and one of two first pilot symbols located on adjacent carriers is a positive pulse and the other is a negative pulse;

[0032] Channel estimation is performed according to the multiple first pilot symbols.

[0033] In addition, in this aspect, other optional implementations of the network device can refer to the relevant content of the first aspect above, and will not be described in detail here.

[0034] In a fifth aspect, an embodiment of the present application provides a chip, the chip comprising a processor and a communication interface, the communication interface being used to receive or send data;

[0035] The processor is configured to cause the chip to execute:

[0036] Determine a plurality of first pilot symbols in the time-frequency domain, wherein the plurality of first pilot symbols are located on different carriers in the same time slot, and one of two first pilot symbols located on adjacent carriers is a positive pulse and the other is a negative pulse;

[0037] Channel estimation is performed according to the multiple first pilot symbols.

[0038] In addition, in this aspect, other optional implementations of the chip can refer to the relevant content of the first aspect above, and will not be described in detail here.

[0039] In a sixth aspect, an embodiment of the present application provides a module device, the module device comprising a communication module, a power module, a storage module and a chip, wherein:

[0040] The power module is used to provide electrical energy to the module device;

[0041] The storage module is used to store data and instructions;

[0042] The communication module is used for internal communication of the module device, or for communication between the module device and an external device;

[0043] The chip is used to execute any method described in the first aspect above.

[0044] In a seventh aspect, an embodiment of the present application provides a computer-readable storage medium for storing computer software instructions used by the above-mentioned terminal, which includes a program for executing any of the methods described in the above-mentioned first aspect.

[0045] In an eighth aspect, an embodiment of the present application further provides a computer program product, which, when executed on a processor, is used to implement any of the method processes described in the first aspect above. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 A schematic diagram of the structure of a communication system provided in an embodiment of the present application;

[0047] Figure 2 A schematic diagram of mapping DD domain symbols and TF domain symbols provided in an embodiment of the present application;

[0048] Figure 3 A schematic diagram of an OTFS modulation system provided in an embodiment of the present application;

[0049] Figure 4 A schematic diagram of a flow chart of a channel estimation method provided in an embodiment of the present application;

[0050] Figure 5 A schematic diagram of the distribution of multiple first pilot symbols provided in an embodiment of the present application;

[0051] Figure 6a A schematic diagram of a DD domain grid provided in an embodiment of the present application;

[0052] Figure 6b Another DD domain grid schematic diagram provided in an embodiment of the present application;

[0053] Figure 6c A schematic diagram of another DD domain grid provided in an embodiment of the present application;

[0054] Figure 7 A schematic diagram of a frame structure of a system frame under multiple CPs provided in an embodiment of the present application;

[0055] Figure 8 A schematic diagram of a CIR versus Doppler index variation curve provided in an embodiment of the present application;

[0056] Figure 9a A schematic diagram of bit error rate variation provided in an embodiment of the present application;

[0057] Figure 9b Another schematic diagram of bit error rate variation provided in an embodiment of the present application;

[0058] Fig.9c A schematic diagram of another bit error rate variation provided in an embodiment of the present application;

[0059] Fig.10 A schematic diagram of the structure of a channel estimation device provided in an embodiment of the present application;

[0060] Fig.11 A schematic diagram of the structure of a communication device provided in an embodiment of the present application;

[0061] Fig.12 A schematic diagram of the structure of a module device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0062] The embodiments of the present application will be described below in conjunction with the accompanying drawings in the embodiments of the present application.

[0063] The communication system involved in the embodiment of the present application is as follows Figure 1 As shown, the communication system may include but is not limited to a network device and two terminal devices. Figure 1 The number and form of devices shown are for illustrative purposes only and do not constitute a limitation on the embodiments of the present application. In actual applications, more than one network device and more than two terminal devices may be included. Figure 1The communication system shown is explained by taking the network device 101, the terminal device 1021 and the terminal device 1022 as examples. The network device 101 can provide network services to the terminal device 1021 and the terminal device 1022, and the terminal device 1021 and the terminal device 1022 can communicate with each other.

[0064] The terminal device in the embodiment of the present application may also be referred to as a terminal, and may refer to various forms of user equipment (UE), access terminal, user unit, user station, mobile station, mobile station (MS), remote station, remote terminal, mobile device, user terminal, wireless communication device, user agent or user device. The terminal device may also be a cellular phone, a cordless phone, a session initiation protocol (SIP) phone, a wireless local loop (WLL) station, a personal digital assistant (PDA), a handheld device with wireless communication function, a computing device or other processing device connected to a wireless modem, a vehicle-mounted device, a wearable device, a terminal device in a fifth generation mobile communication (5G) network, or a terminal device in a future public land mobile communication network (PLMN), etc., and the embodiment of the present application is not limited to this.

[0065] The network equipment in the embodiment of the present application includes a base station and a base station controller of the access network, and may also include a terminal device.

[0066] The base station (BS) in the embodiment of the present application, which may also be referred to as a base station device, is a device deployed in a wireless access network (RAN) to provide wireless communication functions. For example, the device that provides base station functions in the second generation mobile communication (2G) network includes a base transceiver station (BTS). The device that provides base station functions in the third generation mobile communication (3G) network includes a node B (NodeB). The device that provides base station functions in the fourth generation mobile communication (4G) network includes an evolved NodeB (eNB). In wireless local area networks (WLAN), the device that provides base station functions is an access point (AP). The gNB, a device providing base station functions in 5G new radio (NR), and the evolving Node B (ng-eNB), wherein the gNB and the terminal device communicate using NR technology, and the ng-eNB and the terminal communicate using evolved universal terrestrial radio access (E-UTRA) technology, and both gNB and ng-eNB can be connected to the 5G core network. The base station in the embodiment of the present application also includes a device that provides base station functions in a future new communication system, etc.

[0067] The base station controller in the embodiment of the present application, which may also be referred to as a base station controller device, is a device for managing base stations, for example, a base station controller (BSC) in a 2G network, a radio network controller (RNC) in a 3G network, or a device for controlling and managing base stations in a future new communication system.

[0068] The transmitting end in the embodiment of the present application may be the above-mentioned terminal device or the above-mentioned network device, and the embodiment of the present application is not limited to this.

[0069] The present application can be applicable to 5G communication systems, 4G communication systems, 3G communication systems, and various new communication systems in the future, such as the sixth generation mobile communication (6G), the seventh generation mobile communication (7G), etc., but the embodiments of the present application are not limited to this.

[0070] In order to improve the spectrum efficiency of communication of high-mobility terminal devices such as drones, autonomous driving, high-speed trains, and low-orbit satellites, an orthogonal time-frequency space (OTFS) modulation system is proposed. However, in the OTFS modulation system, when high-speed mobile terminal devices communicate, there is still Doppler frequency shift, which causes inter-carrier interference (ICI) to the OTFS waveform, thereby affecting the accuracy of channel estimation.

[0071] In addition, in order to meet the needs of reliable communication for high-mobility terminals in the future, the Delay-Doppler (DD) domain is introduced in the OTFS modulation system. In the DD domain of the OTFS modulation system, channel estimation includes: the transmitter sends a single high-power pulse, and after the single high-power pulse is mapped by DD resources, the pilot symbol and data symbol are converted to the Delay-Time (DT) domain, and then vectorized to the transmission symbol in the time domain; the receiver estimates the OTFS channel response by setting a reasonable threshold.

[0072] On the one hand, the pilot overhead in the channel estimation scheme is large and will cause a high peak-to-average power ratio (PAPR) to the OTFS system.

[0073] On the other hand, high-power pulse pilots will lead to unbalanced power distribution at each delay index. Assuming that the pulse pilot at a certain delay index undergoes inverse discrete Fourier transform (IDFT), the average power of the DT domain symbol at this delay index will be significantly greater than the average power of the DT domain symbols at other delay indexes, resulting in a higher PAPR. It can be seen that channel estimation in OTFS modulation systems is still a problem that needs to be solved urgently.

[0074] The embodiment of the present application can be applied to a single-input single-output (SISO) OTFS system. The continuous-time orthogonal time-frequency-space OTFS signal is sampled at a sampling frequency fs =B=1 / T s Sampling is performed, where T s is the sampling interval. The OTFS frame in the discrete time domain consists of N blocks (or time slots), each block has M symbols, so an OTFS frame has a total of NM symbols. Therefore, the duration of an OTFS frame is T f =NMT s =NT. Where T = MT s It represents the duration of each block in seconds (s); each block occupies a bandwidth B=MΔf in Hertz (Hz), where Δf=1 / T represents the interval between subcarriers.

[0075] The time axis and frequency axis are sampled at intervals of T and Δf respectively, and the time-frequency (TF) domain plane is discretized into an M×N dimensional point array Ξ={(mΔf,nT),m=0,L,M-1,n=0,L,N-1}, Each point in the point array Ξ represents a discrete TF domain symbol X TF [m,n], m=0,L,M-1, n=0,L,N-1. X TF [m,n] can be mapped to the DD domain through a 2D symplectic finite Fourier transform (SFFT). That is, for X TF [m,n] performs inverse discrete Fourier transform IDFT along the frequency axis and discrete Fourier transform (DFT) along the time axis, which can convert X TF [m,n] is mapped to the DD domain and becomes the DD domain symbol X DD [l,k].

[0076] See also Figure 2 , Figure 2 Figure 1 is a schematic diagram of the mapping between DD domain symbols and TF domain symbols. Figure 2 As shown, X TF [m,n] can be transformed from TF domain to DD domain X through 2DSFFT transformation DD [l,k]. Similarly, X DD [l,k] can be transformed from DD domain to time-frequency domain X through 2D inverse symplectic finite Fourier transform (ISFFT) TF [m,n].

[0077] It can be understood that 1 / (MΔf) and 1 / (NT) are the resolutions of time delay and Doppler frequency shift, respectively. The DD domain plane is discretized into an M×N dimensional point array Each point in the point array Γ represents a discrete DD domain symbol X DD [l,k],l=0,L,M-1,k=0,L,N-1.

[0078] See also Figure 3 , Figure 3 is a schematic diagram of the OTFS modulation system. Figure 3 As shown, the transmitter uses the inverse symplectic finite Fourier transform ISFFT to transform the transmission symbol X in the DD domain DD [l,k] is mapped to the symbol X in the TF domain TF [m,n]; the sender applies the Heisenberg transform to X TF [m,n] to create a time domain signal s(t) transmitted through the wireless channel; the transmitter sends the time domain signal s(t). The receiver maps the time domain signal r(t) to the TF domain through the Wigner transform (the inverse transform of the Heisenberg transform) to obtain the received symbol Y TF [m,n]; the receiving end uses SFFT to receive the symbol Y TF [m,n] demodulated to DD domain Y DD [l,k].

[0079] The maximum delay τ of the terminal device in all propagation paths of the time-varying channel max and the maximum Doppler shift ν max It is determined by the values ​​of N, M and T. Among them, T determines the maximum supportable channel delay τ max <T, Δf determines the maximum supportable Doppler frequency shift ν max <Δf / 2. To support a fixed data rate of NM symbols per frame, a larger T (or smaller Δf) may be chosen depending on the channel conditions, resulting in a smaller N (or larger M), and vice versa.

[0080] Assume that the channel is under-spread, that is, τ max ν max <<1,l max <M, Consider a baseband equivalent channel model with P propagation paths. For the pth path, p = 1, ..., P, the path gain is h p , the actual delay τ p and Doppler shift ν p They can be expressed as:

[0081]

[0082]

[0083] in Represents and τ p and ν p The corresponding delay and Doppler index, is related to τ max The relevant delay index, is with ν max The associated Doppler index. is the delay index set of P paths in the DD domain. The number of channel coefficients P in the delay-Doppler domain is finite, and the DD domain channel response h(τ,ν) is:

[0084]

[0085] Among them, h p represents the channel response of the p-th path, 1≤p≤P, and δ() represents the Dirac delta function.

[0086] When the transmitted signal s(t) is transmitted over a time-varying channel with a delay-Doppler channel response h(τ,ν), the received signal r(t) is expressed as:

[0087]

[0088] Wherein, ω(t) represents additive white Gaussian noise (AWGN).

[0089] Under the rectangular waveform, ignoring the noise term, the relationship between input and output in the TF domain is:

[0090]

[0091]

[0092]

[0093] In formula (5), Indicates other carrier symbols X in the same time slot n TF [m′,n], m′≠m for the current symbol X TF The interference generated by [m,n] is called inter-carrier interference ICI. In other words, It is caused by Doppler frequency shift, which destroys the orthogonality between subcarriers in the frequency domain. Indicates the symbol X in the previous time slot (n-1) TF [m′,n-1] for the current symbol X TFThe interference generated by [m,n] is called inter-symbol interference (ISI). In other words, It is caused by time delay, which destroys the orthogonality in the time domain.

[0094] H TF [m′,n′] is the TF domain integrated channel response including the transmit pulse, channel response and receive pulse; To send pulse g tx (t) and the received pulse g rx (t) between the cross blur functions.

[0095] It can be seen that the subcarrier interference ICI in the above formula (5) is:

[0096]

[0097] Among them, H TF [m′,n], m′≠m, inclusive Independent of n, it can be expressed as:

[0098]

[0099] Since the received signal r(t) is sampled at intervals of T / M (or 1 / (MΔf)), A ICI The calculation is:

[0100]

[0101] According to formula (10) and formula (6), we can get:

[0102]

[0103] In the OTFS system, the value of M is large, and as (m′-m) increases, H TF [m′,n] decreases rapidly. Therefore, it can be seen from formula (11) that the farther the interfering subcarrier is from the current subcarrier, the smaller the subcarrier interference ICI it suffers.

[0104] Let formula (11) be C m,m' , when m′=m, C m,m for:

[0105]

[0106] When m′≠m, C m,m for:

[0107]

[0108] Assuming that the data sent by the transmitter has zero mean and is statistically independent, the carrier to interference ratio (CIR) of subcarrier 0≤m≤M-1 is:

[0109]

[0110] The larger the carrier-to-interference ratio of subcarrier 0≤m≤M-1, the smaller the inter-subcarrier interference. Therefore, in order to reduce the inter-subcarrier interference, the carrier-to-interference ratio of the subcarrier needs to be increased.

[0111] The embodiment of the present application provides a channel estimation method. In the method, a transmitting end determines multiple first pilot symbols in the time-frequency domain, the multiple first pilot symbols are located on different carriers in the same time slot, and one of the two first pilot symbols located on adjacent carriers is a positive pulse and the other is a negative pulse. The transmitting end performs channel estimation based on the multiple first pilot symbols.

[0112] The multiple first pilot symbols used by the transmitting end for channel estimation are located on different carriers in the same time slot, and one of the two first pilot symbols located on adjacent carriers is a positive pulse and the other is a negative pulse. Therefore, the carrier interference between the two first pilot symbols located on adjacent carriers in the same time slot can cancel each other, which can reduce the inter-carrier interference and thus improve the accuracy of channel estimation. In addition, compared with the transmitting end using a single-pulse pilot symbol for channel estimation, the multiple first pilot symbols used by the transmitting end are positive and negative pulse pairs, which can reduce the peak-to-average ratio.

[0113] Based on the above description, the present application embodiment proposes a channel estimation method. Figure 4 Schematic diagram of the flow of a channel estimation method, which includes but is not limited to S101 and S102:

[0114] S101. The transmitting end determines multiple first pilot symbols in the time-frequency domain, where the multiple first pilot symbols are located on different carriers in the same time slot, and one of the two first pilot symbols located on adjacent carriers is a positive pulse and the other is a negative pulse.

[0115] S102. The transmitting end performs channel estimation based on multiple first pilot symbols.

[0116] It can be understood that multiple first pilot symbols are located on different carriers in the same time slot, and one of the two first pilot symbols located on adjacent carriers is a positive pulse and the other is a negative pulse, indicating that: multiple first pilot symbols are interlaced in the form of positive and negative pulse pairs and are located on different carriers in the same time slot. Alternatively, it can be understood that the multiple first pilot symbols determined by the transmitting end are positive and negative pulse pairs placed on adjacent subcarriers in the same time slot. For example, Figure 5 is a schematic diagram of the distribution of multiple first pilot symbols. Figure 5As shown, the plurality of first pilot symbols include pilot symbol 1 to pilot symbol 8, and pilot symbol 1 to pilot symbol 8 are in the form of positive and negative pulse pairs and are staggered on carriers 1 to carriers 8 of time slot a.

[0117] Multiple first pilot symbols are located on different carriers in the same time slot, and one of the two first pilot symbols located on adjacent carriers is a positive pulse and the other is a negative pulse, so that the interference between two subcarriers on adjacent carriers in the same time slot can be offset, thereby reducing inter-carrier interference and improving the accuracy of channel estimation.

[0118] In an optional implementation manner, the multiple first pilot symbols are pilot symbols in an Orthogonal Time-Frequency-Space (OTFS) system. That is, the multiple first pilot symbols determined by the transmitting end can be used for channel estimation in the OTFS system.

[0119] In an optional implementation, the transmitting end determines multiple first pilot symbols in the time-frequency domain, including: superimposing N delay-Doppler DD domain grids to obtain first information, where N is an integer greater than or equal to 1; performing an inverse symplectic finite Fourier transform ISFFT on the first information to obtain multiple first pilot symbols in the time-frequency domain.

[0120] The transmitting end superimposes N DD domain grids, which can be understood as: the transmitting end superimposes symbols at the same position in the N DD domain grids. Therefore, the first information includes the symbol arrangement rule in the DD domain grid after the N DD domain grids are superimposed.

[0121] It can be seen that the multiple first pilot symbols are obtained by the transmitting end performing ISFFT on the first information, and the first information is obtained by the transmitting end superimposing N DD domain grids.

[0122] Among them, the dimension of each DD domain grid in the N DD domain grids is M×N, N is equal to the number of blocks included in an orthogonal time-frequency space OTFS frame, and M is equal to the number of OTFS symbols included in each block in an OTFS frame. Each DD domain grid in the N DD domain grids includes N sub-grids, and the dimension of the sub-grid is M2×2.

[0123] It can be understood that for the i-th (1≤i≤N) DD domain grid among the N DD domain grids, the symbol corresponding to the (l′,k′)-th resource block of each subgrid in the i-th DD domain can be expressed as follows:

[0124] When i=1, that is, for the N subgrids in the first DD domain grid among the N DD domain grids, the first subgrid satisfies:

[0125]

[0126] It can be seen from formula (15) that among the N DD domain grids, each subgrid in the first DD domain grid satisfies: the first row and the first column are resources occupied by the negative pulse pilot symbol. That is, the transmitter places the negative pulse pilot symbol in the first row and the first column of each subgrid in the first DD domain grid, and does not place pilot symbols or data symbols in positions other than the first row and the first column of each subgrid.

[0127] When i=N, that is, for N subgrids in N DD domain grids, the first subgrid satisfies:

[0128]

[0129] It can be seen from formula (16) that among the N DD domain grids, each subgrid in the Nth DD domain grid satisfies: the first row and the first column are resources occupied by the positive pulse pilot symbol. That is, the transmitter places the positive pulse pilot symbol in the first row and the first column of each subgrid in the Nth DD domain grid, and does not place pilot symbols or data symbols in positions other than the first row and the first column.

[0130] When 2≤i≤N-1, that is, for the N subgrids in the 2nd to N-1th DD domain grids in the N DD domain grids, the first subgrid satisfies:

[0131]

[0132] It can be seen from formula (17) that among the N DD domain grids, each sub-grid in the second DD domain grid to the N-1th DD domain grid is a resource occupied by a data symbol. In other words, the transmitter places a data symbol in each sub-grid in the second DD domain grid to the N-1th DD domain grid.

[0133] To summarize, among the N DD domain grids, each sub-grid in the first DD domain grid satisfies: the first row and the first column are resources occupied by negative pulse pilot symbols; each sub-grid in the Nth DD domain grid satisfies: the first row and the first column are resources occupied by positive pulse pilot symbols; each sub-grid in the 2nd DD domain grid to the N-1th DD domain grid are resources occupied by data symbols.

[0134] In addition, for each of the N DD domain grids, the first sub-grid in the DD domain grid can be arranged (or laid out, or repeated) twice along the delay axis after phase rotation, and then the grid arranged (or laid out, or repeated) along the delay axis is arranged (or laid out, or repeated) N2 times along the Doppler axis to obtain an M×N dimensional DD domain grid.

[0135] Then, the transmitted symbol X on the (l,k)th resource block in the i-th M×N dimensional DD domain grid is i DD [l,k] can be expressed as:

[0136]

[0137] in, is the transmitted symbol on the (l′, k′)th resource block in the i-th M / 2×2-dimensional DD domain grid, l=0,…,M-1, k=0,…,N-1, l′=0,…,M / 2-1, k′=0,1, c=0,1, d=0,…,N / 2-1. c represents the number of times the subgrid is arranged (or laid out, or repeated) along the delay axis, and d represents the number of times the grid is arranged (or laid out, or repeated) along the Doppler axis after being arranged (or laid out, or repeated) along the delay axis.

[0138] For example, Figure 6a , Figure 6b and Figure 6c Each of them is a DD domain grid diagram. Detailed, Figure 6a , Figure 6b and Figure 6c In the illustrated DD domain grid, M=N=8. Figure 6a This is a schematic diagram of the first DD domain grid among the eight DD domain grids. Figure 6b This is a schematic diagram of the 8th DD domain grid among the 8 DD domain grids. Figure 6c It is a schematic diagram of the 2nd to 7th DD domain grids among the 8 DD domain grids. Figure 6a , Figure 6b and Figure 6c In the figure, M represents a negative pulse pilot symbol, N represents a positive pulse pilot symbol, a white box represents a no-data symbol, and a no-pilot symbol, and a gray box represents a data symbol.

[0139] like Figure 6a As shown in FIG. 1 , in the first DD domain grid, the first row and first column of each subgrid are resources occupied by negative pulse pilot symbols, and no pilot symbols or data symbols are placed in positions other than the first row and first column. Figure 6b As shown, in the 8th DD domain grid, the first row and first column of each subgrid are resources occupied by positive pulse pilot symbols, and no pilot symbols or data symbols are placed in positions other than the first row and first column. Figure 6c As shown, in the 2nd to 7th DD domain grids, each sub-grid is a resource occupied by a data symbol.

[0140] In addition, if Figure 6aAs described above, the first DD domain grid can be regarded as the first sub-grid arranged (or laid out, or repeated) twice along the delay axis, and then the grid arranged (or laid out, or repeated) along the delay axis is arranged (or laid out, or repeated) N2 times along the Doppler axis. Similarly, Figure 6b and Figure 6c The method for obtaining the DD domain grid shown is similar and will not be repeated here.

[0141] The transmitter superimposes N DD domain grids, and the sum of symbols of the (l,k)th resource block in the superimposed DD domain grid is X DD [l,k] consists of N The superposition composition is:

[0142]

[0143] Therefore, the first information obtained by the transmitting end after superimposing N DD domain grids includes X DD [l,k].

[0144] The sender is X DD [l, k] performs ISFFT to convert the DD domain symbol into the first pilot symbol of the TF domain. The first pilot symbol of the TF domain is expressed as:

[0145]

[0146] Among them, m=0,L,M-1, n=0,L,N-1.

[0147] Thus, the transmitting end obtains multiple first pilot symbols, and the multiple first pilot symbols are located on different carriers at the same time point (same time slot) in the TF domain, and one of the two first pilot symbols located on adjacent carriers is a positive pulse and the other is a negative pulse. In addition, each pulse pilot occupies M / 2 resource blocks at the same time point, and occupies a total of resource blocks at two time points.

[0148] Furthermore, multiple first pilot symbols in the TF domain can be expressed as:

[0149]

[0150] Formula (21) can be expressed as:

[0151] X TF [m,n]=-X TF [m+1,n],m=0,L,M-2,n=0,N / 2 (22)

[0152] It can be seen that after the transmitter converts the DD domain symbol into the first pilot symbol of the TF domain, the data symbol in the DD domain still appears as a data symbol in the 1≤n≤N / 2-1 time slot of the TF domain, but appears as a pilot symbol in the n=0,N / 2 time slot of the TF domain.

[0153] In addition, the multiple first pilot symbols determined by the transmitting end reduce the inter-carrier interference in the above formula (5), but there is still a large inter-symbol interference in formula (5). In order to reduce the inter-symbol interference, the embodiment of the present application applies multiple first pilot symbols to the scenario of multiple cyclic prefixes (CP).

[0154] See also Figure 7 , Figure 7 Figure 1 is a schematic diagram of the frame structure of a system frame under multiple CPs. Figure 7 As shown, the sender adds a length of l before each block of N blocks of data in the OTFS frame. max CP is used to reduce the inter-symbol interference from the previous block caused by channel delay. max is the delay index corresponding to the maximum delay of the block in the OTFS frame. For the receiving end, the N CPs are removed before further processing by the receiving end. The sending end adds a length of l before each block of the OTFS frame. max After the CP, the OTFS frame duration is T f Warp factor γ g =(M+l max )N / (MN)=1+l max / M is expanded so that the delay resolution is from Became This reduces inter-symbol interference.

[0155] Therefore, in a multi-CP scenario, for the receiving end, the received symbol in the TF domain can be expressed as:

[0156]

[0157]

[0158] therefore:

[0159]

[0160] At this time, the carrier-to-interference ratio (CIR) of the received symbol is equal to:

[0161]

[0162] By comparing and analyzing the above formula (14) and formula (26), it can be known that the carrier-to-interference ratio of formula (26) is greater than the carrier-to-interference ratio in formula (14). In other words, using the multiple first pilot symbols determined in the embodiment of the present application to perform channel estimation can reduce the inter-carrier interference between the multiple first pilot signals, thereby improving the accuracy of channel estimation.

[0163] In addition, the receiving end can use the least squares (LS) algorithm to estimate the channel and obtain:

[0164]

[0165] Among them, m=0,2,L,M-2,n=0,N / 2.

[0166] According to the above formulas (14) and (26), a single path is considered, and the delay index When n=0, CIR varies with Doppler index. The change curve is as Figure 8 As shown. Figure 8 It can be seen from the figure that the first pilot signal determined by the method of the embodiment of the present application is There is more than 15dB CIR improvement across the range.

[0167] See also Figure 9a , Figure 9b and Fig.9c , Figure 9a , Figure 9b and Fig.9c All of them are schematic diagrams of bit error rate changes. Figure 9a , Figure 9b and Fig.9c The pilot symbols are respectively a schematic diagram comparing the bit error rate changes of placing positive and negative pulses in the TF domain and placing all positive pulses in the TF domain at speeds of 100km / h, 300km / h, and 500km / h. Figure 9a , Figure 9b and Fig.9c It can be seen that under different speed conditions, the performance of the pilot symbol of placing positive and negative pulses in the TF domain proposed in the embodiment of the present application is better than the performance of placing all-positive pulses in the TF domain. When the speed is 300km / h and the bit error rate (BER) is 0.025, the performance of the pilot signal of placing positive and negative pulses proposed in the embodiment of the present application is about 1dB better than the pilot symbol of placing all-positive pulses. In other words, the higher the speed, the more obvious the ICI, and the more obvious the gain corresponding to the pilot symbol proposed in the embodiment of the present application.

[0168] In the embodiment of the present application, the transmitting end determines a plurality of first pilot symbols and uses the plurality of first pilot symbols for channel estimation. The plurality of first pilot symbols are located on different carriers in the same time slot, and one of the two first pilot symbols located on adjacent carriers is a positive pulse and the other is a negative pulse. Thus, the carrier interference between the two first pilot symbols located on adjacent carriers in the same time slot can cancel each other, which can reduce the inter-carrier interference and thus improve the accuracy of the channel estimation.

[0169] In addition, compared with the use of a single-pulse pilot symbol for channel estimation at the transmitting end, the multiple first pilot symbols used by the transmitting end are positive and negative pulse pairs, which can reduce the peak-to-average ratio.

[0170] See also Fig.10 , Fig.10 1 is a schematic diagram of the structure of a channel estimation device 1000 provided in an embodiment of the present invention. The channel estimation device 1000 can be used in a terminal device or a network device.

[0171] In one implementation, the channel estimation apparatus 1000 may include:

[0172] A determining unit 1001 is configured to determine a plurality of first pilot symbols in a time-frequency domain, wherein the plurality of first pilot symbols are located on different carriers in the same time slot, and one of two first pilot symbols located on adjacent carriers is a positive pulse and the other is a negative pulse;

[0173] The channel estimation unit 1002 is configured to perform channel estimation according to the multiple first pilot symbols.

[0174] In an optional implementation, the multiple first pilot symbols are pilot symbols in an Orthogonal Time-Frequency-Space (OTFS) system.

[0175] In an optional implementation, the determination unit 1001 determines multiple first pilot symbols in the time-frequency domain, and is specifically used to: superimpose N delay-Doppler DD domain grids to obtain first information, where N is an integer greater than or equal to 1; perform an inverse symplectic finite Fourier transform ISFFT on the first information to obtain multiple first pilot symbols in the time-frequency domain.

[0176] In an optional implementation manner, the dimension of each DD domain grid in the N DD domain grids is M×N, the N is equal to the number of blocks included in an orthogonal time-frequency space OTFS frame, and the M is equal to the number of OTFS symbols included in each block in the OTFS frame;

[0177] Each of the N DD domain grids includes N sub-grids, and a dimension of each of the N sub-grids is M / 2×2;

[0178] Among the N DD domain grids, each sub-grid in the first DD domain grid satisfies: the first row and the first column are resources occupied by negative pulse pilot symbols; among the N DD domain grids, each sub-grid in the Nth DD domain grid satisfies: the first row and the first column are resources occupied by positive pulse pilot symbols; among the N DD domain grids, each sub-grid in the second DD domain grid to the N-1th DD domain grid are resources occupied by data symbols.

[0179] Optionally, the channel estimation device 1000 further includes a communication unit 1003, and the communication unit 1003 is used to receive or send data.

[0180] The embodiments of the present application and the above-mentioned method embodiments are based on the same concept, and the technical effects they bring are also the same. For the specific principles, please refer to the description of the above-mentioned method embodiments, which will not be repeated here.

[0181] See also Fig.11 , Fig.11 A schematic diagram of the structure of a communication device 1100 provided in an embodiment of the present application, the communication device 1100 may be a terminal device or a network device. The communication device 1100 may include a memory 1101 and a processor 1102. Optionally, it also includes a communication interface 1103. The memory 1101, the processor 1102 and the communication interface 1103 are connected via one or more communication buses. The communication interface 1103 is controlled by the processor 1102 to send and receive information.

[0182] The memory 1101 may include a read-only memory and a random access memory, and provides instructions and data to the processor 1102. A portion of the memory 1101 may also include a nonvolatile random access memory.

[0183] The communication interface 1103 is used to receive or send data.

[0184] The processor 1102 may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor, or alternatively, the processor 1102 may be any conventional processor, etc. Among them:

[0185] The memory 1101 is used to store program instructions.

[0186] The processor 1102 is used to call the program instructions stored in the memory 1101.

[0187] In an optional implementation manner, when the processor 1102 calls the computer program, it is used to execute:

[0188] Determine a plurality of first pilot symbols in the time-frequency domain, wherein the plurality of first pilot symbols are located on different carriers in the same time slot, and one of two first pilot symbols located on adjacent carriers is a positive pulse and the other is a negative pulse; perform channel estimation based on the plurality of first pilot symbols.

[0189] The embodiments of the present application and the above-mentioned method embodiments are based on the same concept, and the technical effects they bring are also the same. For the specific principles, please refer to the description of the above-mentioned method embodiments, which will not be repeated here.

[0190] The present application also provides a chip that can execute the steps related to the sending end in the above method embodiment. The chip includes a processor and a communication interface, and the communication interface is used to receive or send data;

[0191] In one embodiment, the chip performs the relevant steps in the aforementioned method embodiment:

[0192] The processor is configured to cause the chip to perform the following operations: determine multiple first pilot symbols in the time-frequency domain, wherein the multiple first pilot symbols are located on different carriers in the same time slot, and one of the two first pilot symbols located on adjacent carriers is a positive pulse and the other is a negative pulse; and perform channel estimation based on the multiple first pilot symbols.

[0193] For other implementations of the chip, please refer to the relevant contents of the above method embodiments, which will not be described in detail here.

[0194] The embodiments of the present application and the above-mentioned method embodiments are based on the same concept, and the technical effects they bring are also the same. For the specific principles, please refer to the description of the above-mentioned method embodiments, which will not be repeated here.

[0195] For each device or product applied to or integrated in the chip, each module contained therein can be implemented in the form of hardware such as circuits, or at least some of the modules can be implemented in the form of software programs, which run on a processor integrated inside the chip, and the remaining (if any) modules can be implemented in the form of hardware such as circuits.

[0196] like Fig.12 As shown, Fig.121 is a schematic diagram of a module device provided in an embodiment of the present application. The module device 1200 can execute the relevant steps of the sending end in the aforementioned method embodiment, and the module device 1200 includes: a communication module 1201, a power module 1202, a storage module 1203 and a chip 1204.

[0197] Among them, the power module 1202 is used to provide power to the module device; the storage module 1203 is used to store data and instructions; the communication module 1201 is used for internal communication of the module device, or for the module device to communicate with external devices; the chip 1204 is used to execute the method executed by the terminal device in the above method embodiment.

[0198] The implementation method of the module device can refer to the relevant content of the above method embodiment, which will not be described in detail here.

[0199] The embodiments of the present application and the above-mentioned method embodiments are based on the same concept, and the technical effects they bring are also the same. For the specific principles, please refer to the description of the above-mentioned method embodiments, which will not be repeated here.

[0200] An embodiment of the present application also provides a computer-readable storage medium, in which instructions are stored. When the computer-readable storage medium is executed on a processor, the method flow of the above method embodiment is implemented.

[0201] The embodiment of the present application also provides a computer program product. When the computer program product runs on a processor, the method flow of the above method embodiment is implemented.

[0202] Regarding the various modules / units included in the various devices and products described in the above embodiments, they can be software modules / units, or hardware modules / units, or they can be partially software modules / units and partially hardware modules / units. For example, for various devices and products applied to or integrated in a chip, the various modules / units included therein can all be implemented in the form of hardware such as circuits, or at least some of the modules / units can be implemented in the form of software programs, which run on the integrated processor inside the chip, and the remaining (if any) modules / units can be implemented in the form of hardware such as circuits; for various devices and products applied to or integrated in a chip module, the various modules / units included therein can all be implemented in the form of hardware such as circuits, and different modules / units can be located in the same part of the chip module (such as a chip, circuit module, etc.) or in different components, or at least some of the modules / units can be implemented in the form of software programs. The software programs run on the integrated processor inside the chip, and the remaining (if any) modules / units can be implemented in the form of hardware such as circuits. It can be implemented in the form of a software program, which runs on a processor integrated inside the chip module, and the remaining (if any) modules / units can be implemented in the form of hardware such as circuits; for various devices and products applied to or integrated in the terminal, the modules / units contained therein can all be implemented in the form of hardware such as circuits, and different modules / units can be located in the same component (for example, chip, circuit module, etc.) or in different components in the terminal, or, at least some modules / units can be implemented in the form of a software program, which runs on a processor integrated inside the terminal, and the remaining (if any) modules / units can be implemented in the form of hardware such as circuits.

[0203] It should be noted that, for the aforementioned method embodiments, for the sake of simplicity, they are all expressed as a series of action combinations, but those skilled in the art should be aware that the present application is not limited by the described order of actions, because according to the present application, certain operations can be performed in other orders or simultaneously. Secondly, those skilled in the art should also be aware that the embodiments described in the specification are all preferred embodiments, and the actions and modules involved are not necessarily required by the present application.

[0204] The descriptions of the various embodiments provided in this application can refer to each other, and the descriptions of the various embodiments have different focuses. For parts that are not described in detail in a certain embodiment, refer to the relevant descriptions of other embodiments. For the convenience and simplicity of description, for example, the functions of the various devices and equipment provided in the embodiments of this application and the operations performed can refer to the relevant descriptions of the method embodiments of this application, and the various method embodiments and the various device embodiments can also refer to, combine or quote each other.

[0205] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A channel estimation method, characterized in that: The method comprises: Determine a plurality of first pilot symbols in the time-frequency domain, wherein the plurality of first pilot symbols are located on different carriers in the same time slot, and one of two first pilot symbols located on adjacent carriers is a positive pulse and the other is a negative pulse; Channel estimation is performed according to the multiple first pilot symbols.

2. The method according to claim 1, characterized in that: The multiple first pilot symbols are pilot symbols in an Orthogonal Time-Frequency-Space (OTFS) system.

3. The method according to claim 1 or 2, characterized in that: The determining of a plurality of first pilot symbols in the time-frequency domain comprises: Superimposing N delay-Doppler DD domain grids to obtain first information, where N is an integer greater than or equal to 1; Perform an inverse symplectic finite Fourier transform (ISFFT) on the first information to obtain multiple first pilot symbols in the time-frequency domain.

4. The method according to claim 3, characterized in that The dimension of each DD domain grid in the N DD domain grids is M×N, wherein N is equal to the number of blocks included in an orthogonal time-frequency space OTFS frame, and M is equal to the number of OTFS symbols included in each block in the OTFS frame; Each of the N DD domain grids includes N sub-grids, and the dimension of each sub-grid in the N sub-grids is M2×2; In the N DD domain grids, each subgrid in the first DD domain grid satisfies: the first row and the first column are resources occupied by negative pulse pilot symbols; In the N DD domain grids, each subgrid in the Nth DD domain grid satisfies: the first row and the first column are resources occupied by positive pulse pilot symbols; Among the N DD domain grids, each sub-grid in the 2nd DD domain grid to the N-1th DD domain grid is a resource occupied by a data symbol.

5. A channel estimation device, characterized in that: The device comprises: A determining unit, configured to determine a plurality of first pilot symbols in the time-frequency domain, wherein the plurality of first pilot symbols are located on different carriers in the same time slot, and one of two first pilot symbols located on adjacent carriers is a positive pulse and the other is a negative pulse; The channel estimation unit is used to perform channel estimation according to the multiple first pilot symbols.

6. A terminal device, characterized in that: The terminal device includes a processor and a memory, the processor and the memory are connected to each other, wherein the memory is used to store a computer program, the computer program includes program instructions, and the processor is configured to call the program instructions to execute the method according to any one of claims 1 to 4.

7. A network device, characterized in that: The network device includes a processor and a memory, the processor and the memory are connected to each other, wherein the memory is used to store a computer program, the computer program includes program instructions, and the processor is configured to call the program instructions to execute the method according to any one of claims 1 to 4.

8. A chip, characterized in that: The method comprises a processor and a communication interface, wherein the processor is configured to cause the chip to execute the method according to any one of claims 1 to 4.

9. A module device, characterized in that: The module device includes a communication module, a power module, a storage module and a chip, wherein: The power module is used to provide electrical energy to the module device; The storage module is used to store data and instructions; The communication module is used for internal communication of the module device, or for communication between the module device and an external device; The chip is used to execute the method according to any one of claims 1 to 4.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores computer-readable instructions, and when the computer-readable instructions are executed on a communication device, the communication device executes the method according to any one of claims 1 to 4.

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