Multi-user pilot resource allocation method, multi-user channel estimation method and device

Abstract

The embodiment of the application provides a multi-user pilot resource allocation method, a multi-user channel estimation method and device, and relates to the technical field of wireless communication. The multi-user pilot resource allocation method comprises the following steps: dividing a delay-Doppler domain into a data area and a pilot area, and respectively allocating corresponding data sub-areas and pilot sub-areas to a plurality of users; and issuing control signaling to each user, wherein the control signaling carries a resource allocation result, so that the user places a known pilot symbol at a predefined reference position in the corresponding pilot sub-area, and all other positions in the pilot sub-area are placed with zero symbols. The method is beneficial to avoiding pilot-to-pilot interference, reducing pilot overhead, and thus improving resource utilization.

Description

Technical Field

[0001] This application relates to the field of wireless communication technology, and in particular to a multi-user pilot resource allocation method, a multi-user channel estimation method, and an apparatus. Background Technology

[0002] In communication between base stations and user terminals, the channel exhibits significant delay spread and Doppler shift. Orthogonal Time-Frequency-Space (OTFS) modulation technology, due to its signal processing in the Delay-Doppler (DD) domain, effectively combats the Doppler effect and is considered one of the key technologies for 6G mobile communication. OTFS modulation technology effectively handles highly dynamic channels by mapping the signal to the DD domain, but its channel estimation in multi-user scenarios suffers from low resource utilization. Summary of the Invention

[0003] This application provides a multi-user pilot resource allocation method, a multi-user channel estimation method, and an apparatus to improve resource utilization.

[0004] In a first aspect, this application provides a multi-user pilot resource allocation method, applied to a base station, the method comprising:

[0005] The delay-Doppler domain is divided into a data region and a pilot region;

[0006] In the data area and the pilot area, corresponding data sub-areas and pilot sub-areas are allocated to multiple users respectively;

[0007] Control signaling is sent to each of the users, the control signaling carrying resource allocation results, so that the user places a known pilot symbol at a predefined reference position in the corresponding pilot sub-region, and places zero symbols at other positions in the pilot sub-region.

[0008] In one possible implementation, the allocation of corresponding data sub-regions and pilot sub-regions for multiple users in the data region and the pilot region respectively includes:

[0009] The data region is divided into multiple data sub-regions along the time delay axis and assigned to different users;

[0010] The pilot region is divided into multiple pilot sub-regions along the Doppler axis and assigned to different users.

[0011] In one possible implementation, for the u-th user and the (u+1)-th user whose pilot sub-regions are adjacent on the Doppler axis among the plurality of users, the free resources between the upper boundary of the pilot sub-region of the u-th user and the lower boundary of the pilot sub-region of the (u+1)-th user belong to the protection interval shared by the two users.

[0012] In one possible implementation, an anti-interference protection interval is further included between the pilot sub-region of the u-th user and the pilot sub-region of the (u+1)-th user, and the symbol width of the anti-interference protection interval is a preset width.

[0013] In one possible implementation, the method further includes:

[0014] Get the largest integer Doppler index;

[0015] Based on preset constraints, the total number of users that the base station can currently support is determined according to the maximum integer Doppler index and the Doppler dimension of the delay-Doppler domain.

[0016] User scheduling is performed based on the total number of users.

[0017] Secondly, this application provides a multi-user channel estimation method applied to a base station, the method comprising:

[0018] Acquire the received signal of any one of multiple users;

[0019] A two-layer iterative structure is adopted. Based on the data sub-region and pilot sub-region allocated to the user and the user's received signal, channel estimation is performed on the user. During the channel estimation process, total interference is removed to obtain the target channel estimate. The total interference refers to the total interference caused to the user's received signal by other users among the multiple users besides the user. The data sub-region and pilot sub-region allocated to the user are determined based on the multi-user pilot resource allocation method as described in the first aspect and / or any one of the first aspects.

[0020] In one possible implementation, the two-layer iterative structure is adopted, which performs channel estimation for the user based on the data sub-region and pilot sub-region allocated to the user and the user's received signal, and removes total interference during the channel estimation process to obtain a target channel estimate, including:

[0021] Execute multiple double-layer iterations sequentially until the iteration stopping condition is met; each double-layer iteration includes an inner iteration and an outer iteration, and specifically includes the following operations:

[0022] In the inner iteration: based on the data sub-region and pilot sub-region allocated to the user, multiple effective paths are separated from the user's received signal to obtain a coarse channel estimate;

[0023] In the outer iteration:

[0024] Based on the coarse channel estimates of other users besides the user mentioned above, the total interference caused by other users to the received signal of the user is determined, and the difference between the received signal of the user and the total interference is determined as the clean received signal; multiple effective paths are separated from the clean received signal of the user to obtain the target channel estimate.

[0025] In one possible implementation, the step of separating multiple effective paths from the user's received signal based on the data sub-region and pilot sub-region allocated to the user to obtain a coarse channel estimate includes:

[0026] Multiple effective path searches are performed on the user's received signal until the search stopping condition is met, in order to separate multiple effective paths and obtain a coarse channel estimate; wherein each effective path search includes the following operations:

[0027] In the user's pilot sub-region, search for the energy peak value of the received signal in this valid path search;

[0028] If the energy peak exceeds the adaptive threshold, the delay index corresponding to the energy peak is determined to be a valid delay index;

[0029] Centered on the location of the energy peak, within a preset Doppler range, a step-size search is performed by autocorrelation operation with the pilot sequence to obtain the fractional Doppler frequency shift and channel gain;

[0030] The effective path is determined based on the effective delay index, fractional Doppler frequency shift, and channel gain.

[0031] The received signal for the next valid path search is determined based on the valid path.

[0032] In one possible implementation, determining the received signal for the next valid path search based on the valid path includes:

[0033] The contribution value of the effective path to the received signal is reconstructed based on the effective path.

[0034] The contribution value is subtracted from the received signal of the current effective path search to obtain the received signal of the next effective path search.

[0035] Thirdly, this application provides a multi-user pilot resource allocation device integrated in a base station, the device comprising:

[0036] The allocation module is used to divide the delay-Doppler domain into a data region and a pilot region;

[0037] The allocation module is further configured to allocate corresponding data sub-regions and pilot sub-regions to multiple users in the data region and the pilot region, respectively.

[0038] The sending module is used to send control signaling to each of the users. The control signaling carries resource allocation results so that each user places a known pilot symbol at a predefined reference position in the corresponding pilot sub-region, and places zero symbols at other positions in the pilot sub-region. The allocation of corresponding data sub-regions and pilot sub-regions to multiple users in the data region and the pilot region includes: dividing the data region into multiple data sub-regions along the time delay axis and allocating them to different users; dividing the pilot region into multiple pilot sub-regions along the Doppler axis and allocating them to different users.

[0039] Fourthly, this application provides a multi-user channel estimation apparatus integrated in a base station, the apparatus comprising:

[0040] The acquisition module is used to acquire the received signal of any one of multiple users;

[0041] The channel estimation module employs a two-layer iterative structure to perform channel estimation for the user based on the data sub-region and pilot sub-region allocated to the user and the user's received signal. During the channel estimation process, total interference is removed to obtain a target channel estimation value. The total interference refers to the total interference caused to the user's received signal by other users among the multiple users besides the user mentioned above. The data sub-region and pilot sub-region allocated to the user are determined based on the multi-user pilot resource allocation device as described in the third aspect.

[0042] Fifthly, this application provides a base station, including: a processor and a memory communicatively connected to the processor;

[0043] The memory stores computer-executed instructions;

[0044] The processor executes computer execution instructions stored in the memory, causing the processor to perform the first aspect and / or various possible implementations of the first aspect, or the second aspect and / or various possible implementations of the second aspect.

[0045] In a sixth aspect, this application provides a computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, are used to implement the first aspect and / or various possible implementations of the first aspect, or the second aspect and / or various possible implementations of the second aspect.

[0046] In a seventh aspect, this application provides a computer program product, including a computer program that, when executed by a processor, implements the first aspect and / or various possible implementations of the first aspect, or the second aspect and / or various possible implementations of the second aspect.

[0047] The multi-user pilot resource allocation method, multi-user channel estimation method, and apparatus provided in this application achieve orthogonal isolation of resources among multiple users by dividing the data region and pilot region in the delay-Doppler domain during pilot resource allocation, and allocating non-overlapping data sub-regions and pilot sub-regions to each user. The base station issues control signaling to instruct users to place only one known pilot symbol at a predefined reference position in their respective pilot sub-regions and set the rest to zero, which helps to avoid inter-pilot interference, reduce pilot overhead, and thus improve resource utilization. Attached Figure Description

[0048] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0049] Figure 1 This is a schematic diagram of the network topology of this application;

[0050] Figure 2 A flowchart illustrating the multi-user pilot resource allocation method provided in this application;

[0051] Figure 3 This application provides a schematic diagram of multi-user pilot resource allocation.

[0052] Figure 4 A flowchart illustrating the multi-user channel estimation method provided in this application. Figure 1 ;

[0053] Figure 5 A flowchart illustrating the multi-user channel estimation method provided in this application. Figure 2 ;

[0054] Figure 6 A flowchart illustrating the multi-user channel estimation method provided in this application. Figure 3 ;

[0055] Figure 7 A schematic diagram illustrating the channel estimation performance under the multi-user pilot design provided in this application;

[0056] Figure 8 A schematic diagram of the multi-user pilot resource allocation device provided in this application;

[0057] Figure 9 A schematic diagram of the structure of the multi-user channel estimation device provided in this application;

[0058] Figure 10 This is a schematic diagram of the base station structure provided in this application.

[0059] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0060] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0061] With the development of 5G-Advanced and 6G mobile communication technologies, scenarios such as satellite communication, vehicle-to-everything (V2X), and industrial automation have placed extremely high demands on reliable multi-user communication under high-speed mobility. OTFS technology is a key candidate technology to address this challenge.

[0062] In related technologies, one or more known pilot symbols are embedded for a single user within a two-dimensional resource grid in the Delay-Doppler (DD) domain. To avoid interference from data symbols to pilot symbols, and to mitigate the impact of channel delay and Doppler spread on pilot symbols, a sufficiently large guard interval must be set around the pilot symbols. In multi-user scenarios, each user is typically allocated an independent pilot resource block containing a complete guard interval. After receiving a signal, the receiver (e.g., a base station) uses the received values ​​at known pilot locations to estimate the channel impulse response. Channel estimation algorithms are typically based on simple threshold decision methods, compressed sensing algorithms utilizing channel sparsity, or iterative peak search algorithms, etc.

[0063] In multi-user scenarios, to avoid pilot interference between users, relevant technical requirements necessitate configuring independent pilot resources with a large guard interval for each user.

[0064] For example, in a typical , DD field, maximum latency index Maximum Doppler Index In an 8-user system, the traditional embedded pilot scheme has low DD domain mesh utilization, with some pilot resources wasted on guard intervals. It is the number of resource grids in the Doppler domain (also known as the total length of the Doppler dimension). It is the number of resource grids in the time-delay domain (also known as the total length of the time-delay dimension).

[0065] This application aims to address the problem of low pilot resource utilization in channel estimation scenarios of OTFS in multi-user applications, and provides a solution that balances high pilot resource efficiency and high estimation accuracy. It can be widely used in network equipment such as base stations and satellite ground stations in next-generation mobile communication systems.

[0066] This application belongs to the field of wireless communication technology, specifically relating to an OTFS modulation system in high-speed mobile and multi-user communication scenarios.

[0067] Figure 1 This is a schematic diagram of the network topology of this application, as shown below. Figure 1 As shown, the network topology includes a base station 10 and multiple user terminals 20.

[0068] This application is applied to multi-user uplink communication scenarios, where a central receiving node, such as base station 10, is responsible for resource allocation and management.

[0069] Uplink transmission uses OTFS modulation, and its signal processing is performed in the DD domain. The DD domain is divided into a region containing... A two-dimensional plane of resource grids, wherein, The total length of the delay dimension. This represents the total length of the Doppler dimension. This application uses a single resource grid as the smallest unit for resource allocation. Resource Grid It refers to any resource grid in the DD domain.

[0070] The multi-user pilot resource allocation method provided in this application is implemented by a multi-user pilot resource allocation device, which is integrated into the base station, such as... Figure 1 The base station 10 shown is an example. Similarly, the execution entity of the multi-user channel estimation method provided in this application is a multi-user channel estimation device, which is integrated into the base station, such as... Figure 1 Base station 10 is shown.

[0071] The technical solution of this application and how the technical solution of this application solves the above-mentioned technical problems are described in detail below with specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments. The embodiments of this application will now be described with reference to the accompanying drawings.

[0072] Figure 2 A flowchart illustrating the multi-user pilot resource allocation method provided in this application is shown below. Figure 2 As shown, the method includes:

[0073] S201. Divide the delay-Doppler domain into a data region and a pilot region.

[0074] The data region refers to a sub-region in the delay-Doppler domain specifically used for transmitting user data symbols. The pilot region refers to a sub-region in the delay-Doppler domain specifically used for transmitting pilot symbols (with a known reference signal).

[0075] For example, Figure 3 This application provides a schematic diagram of multi-user pilot resource allocation, such as... Figure 3 As shown, the base station divides the entire DD domain grid into data areas. and pilot region .

[0076] Among them, the data area : Pilot region : .

[0077] in, For Doppler indexing, For delay index, The length of the Doppler dimension. The total length of the delay dimension. , It is the estimated maximum integer delay index (also known as the maximum delay index).

[0078] This division ensures that, on the delay axis, the energy of any data symbol will not leak into the pilot region due to channel delay spread.

[0079] In this application, the pilot region is placed in the high-delay part of the DD domain. However, in actual implementation, the pilot region can also be placed in the middle or other positions of the DD domain, as long as there is sufficient delay axis protection interval between it and the data region. This application does not limit this.

[0080] S202. In the data area and pilot area, allocate corresponding data sub-areas and pilot sub-areas to multiple users respectively.

[0081] In this context, "user" refers to a user terminal that communicates with the base station. In a multi-user system, there are multiple users accessing the system simultaneously. It should be noted that in the following embodiments, "user" refers to a user terminal.

[0082] The data sub-region and pilot sub-region are resource blocks allocated separately for each user, located within the overall data region and pilot region, respectively. Each user has a non-overlapping sub-region to avoid interference between users.

[0083] In one optional implementation, step S202 specifically includes: dividing the data region into multiple data sub-regions along the time delay axis and assigning them to different users; dividing the pilot region into multiple pilot sub-regions along the Doppler axis and assigning them to different users.

[0084] In this application, it is assumed that the total number of users is [number missing]. .

[0085] This step will cover the entire data area. Slice along the time delay axis and assign to different users. For example, the first... The data sub-area for each user is Similarly, this step will cover the entire pilot region. Slices are taken along the Doppler axis and assigned to different users. For example, the first... The pilot sub-region for each user is .

[0086] Among them, the A user refers to any one of multiple users, and .

[0087] For example, the Pilot sub-region for each user The coordinate range is:

[0088]

[0089] in, For Doppler indexing, For delay index, The total length of the delay dimension. , It is the estimated maximum integer delay index. It is the estimated largest integer Doppler index (also known as the largest Doppler index).

[0090] S203. Send control signaling to each user. The control signaling carries the resource allocation result so that the user places a known pilot symbol at a predefined reference position in the corresponding pilot sub-region, and places zero symbols at other positions in the pilot sub-region.

[0091] Control signaling is an instruction sent by the base station to the user, and it includes the specific location of resource allocation (such as coordinates in a delay-Doppler grid), modulation method, power, etc. The user determines which resource units they should transmit data or pilot signals on based on this control signaling.

[0092] The pilot symbol is a pre-agreed, known complex value that is transmitted by the user at a designated location. The base station uses the received pilot symbol to compare with a local copy to estimate the channel response.

[0093] The reference location is the placement of the pilot symbol agreed upon in advance by the base station and the user. The specific location can be set according to actual needs, and this application does not limit it.

[0094] Optionally, the reference position is the center of the pilot sub-region. By placing the pilot symbol at the center of the pilot sub-region, the user pilot position can be uniquely identified, facilitating base station identification. Furthermore, by utilizing the local diffusion characteristics of the channel response in the delay-Doppler domain, such as the energy diffusion of a path to neighboring grids, placing the pilot symbol at the center can maximize the capture of the user's channel support set.

[0095] In all locations within the pilot sub-region except for the predefined reference position, the user forces a value of 0 (i.e., no energy is transmitted). The purpose of this is to isolate the pilots, avoid inter-pilot interference, and simplify channel estimation to take advantage of the channel's sparsity in the delay-Doppler domain.

[0096] This application achieves orthogonal isolation of resources among multiple users by dividing the data region and pilot region in the delay-Doppler domain and allocating non-overlapping data sub-regions and pilot sub-regions to each user. The base station issues control signaling to instruct users to place a known pilot symbol only at a predefined reference position in their respective pilot sub-regions and set the rest to zero, which helps to avoid inter-pilot interference, reduce pilot overhead, and thus improve resource utilization.

[0097] In one possible implementation, for the u-th user and the (u+1)-th user whose pilot sub-regions are adjacent on the Doppler axis, the free resources between the upper boundary of the pilot sub-region of the u-th user and the lower boundary of the pilot sub-region of the (u+1)-th user belong to the protection interval shared by the two users. Here, free resources refer to the positions in the pilot sub-regions where zero symbols are placed, i.e., all positions other than the predefined reference positions.

[0098] Specifically, such as Figure 3 As shown, the pilot sub-regions of User 1 and User 2 are adjacent on the Doppler axis. The free resources between the upper boundary of User 1's pilot sub-region and the lower boundary of User 2's pilot sub-region ( Figure 3 (represented by white-filled squares), which are shared by two users, and can therefore be regarded as a reused protective interval.

[0099] In traditional schemes, each user must exclusively occupy a complete protection interval (i.e., protection resources cannot be shared), resulting in a linear increase in the number of protection intervals with the number of users and consuming a significant amount of pilot area resources. This application sets up shared protection intervals for adjacent users along the Doppler axis, allowing multiple users to share protection resources that were originally configured independently. This breaks the limitation of each user exclusively occupying complete protection resources in traditional schemes, achieving the reuse of protection resources and reducing the total number of protection intervals or total overhead. Since the protection interval is part of the pilot area, its reuse directly saves resources within the pilot area, allowing more users to be accommodated within the same pilot area, or reducing pilot overhead when supporting the same number of users. Therefore, under the premise of unchanged total pilot area, it is beneficial to increase the effective resource ratio of actual pilot symbols (rather than protection).

[0100] In one possible implementation, an anti-interference protection interval is further included between the pilot sub-region of the u-th user and the pilot sub-region of the (u+1)-th user, and the symbol width of the anti-interference protection interval is a preset width.

[0101] The preset width can be set according to actual needs, and this application does not limit it. For example, an additional protection interval of one symbol width is designed between two adjacent pilot sub-regions, such as... Figure 3 The anti-interference protection interval is indicated in the middle. This interval is used to suppress interference leakage between users under extreme conditions (such as symmetrical maximum Doppler shift), ensuring robustness.

[0102] To ensure isolation performance under resource reuse, this application configures an additional dedicated anti-interference protection interval with a preset width for adjacent users, in addition to the shared protection interval. This "shared + dedicated" composite protection interval design is key to maximizing pilot resource efficiency while ensuring robustness.

[0103] This application significantly improves pilot resource efficiency at the physical level through a DD domain pilot structure design for resource reuse; and based on this structure, this application also defines a system management method adapted to the channel environment: the base station needs to dynamically adjust its internal user scheduling strategy according to the real-time or semi-static channel environment.

[0104] In one alternative embodiment, the channel environment specifically refers to the estimated maximum integer Doppler index. Accordingly, the user scheduling strategy specifically includes: obtaining the largest integer Doppler index; determining the total number of users that the base station can currently support based on preset constraints, according to the largest integer Doppler index and the Doppler dimension of the delay-Doppler domain; and performing user scheduling based on the total number of users.

[0105] For example, the preset constraint relationship is as follows:

[0106]

[0107] in, Total number of users The total length of the Doppler dimension. The largest integer Doppler index.

[0108] In this embodiment, the base station internally according to Perform user scheduling and use dedicated control signaling to ultimately connect with... The resource allocation results related to the value, such as the specific coordinates of the pilot sub-region assigned to each user, are sent to the scheduled user. The user does not need to know... The upper limit only requires sending pilots at the specified resource location based on the allocation results.

[0109] This application establishes a direct correlation and adaptive adjustment mechanism between physical layer channel characteristics and system layer user capacity. The dimensions of the aforementioned pilot structure are related to the maximum Doppler frequency shift. Closely correlated, this means that the maximum user capacity is no longer a fixed value, but a function of the channel environment. This application proposes that the base station should adjust the capacity based on real-time or semi-static data. This involves proactively and dynamically managing the number of accessible users to ensure the effectiveness of the pilot design. This is a key concept in transforming static resource configuration into dynamic adaptive system management.

[0110] Therefore, this application provides a pilot resource allocation method for solving the problems of multi-user interference and pilot resource efficiency, as well as a method for dynamically managing user access according to the channel environment.

[0111] Based on the above embodiments, this application also provides a multi-user channel estimation method. The method will be described in detail below.

[0112] Figure 4 A flowchart illustrating the multi-user channel estimation method provided in this application. Figure 1 ,like Figure 4 As shown, the method includes:

[0113] S401: Obtain the received signal of any one of the multiple users.

[0114] The received signal refers to the signal received by the base station from a specific user. This signal may be mixed with interference and noise from other users, therefore channel estimation is required for this signal.

[0115] S402. Based on the data sub-region and pilot sub-region allocated to the user and the user's received signal, perform channel estimation for the user to obtain the target channel estimate.

[0116] The data sub-region and pilot sub-region are resource blocks specifically allocated to this user in the delay-Doppler domain, used for transmitting data symbols and pilot symbols, respectively; the locations of these regions are pre-allocated by the base station and communicated to the user. See the above for the specific allocation process. Figure 2 The embodiments shown are not described in detail here.

[0117] Channel estimation refers to the process by which a base station infers the characteristics of a user's wireless channel based on received signals and known resource allocation information, and outputs a target channel estimate.

[0118] The target channel estimate is the final channel estimate used for subsequent data demodulation.

[0119] This application combines the data sub-region and pilot sub-region allocated to the user with their received signals to perform channel estimation, enabling the channel estimation process to accurately obtain the target channel estimate based on the user's exclusive resource location information.

[0120] In one optional embodiment, step S402 is implemented by employing a two-layer iterative structure. Based on the data sub-region and pilot sub-region allocated to the user and the user's received signal, channel estimation is performed on the user. Total interference is removed during the channel estimation process to obtain a target channel estimate. The total interference refers to the total interference caused to the user's received signal by other users besides the user among multiple users. Specifically, multiple two-layer iterations are performed sequentially until the iteration stopping condition is met. Each two-layer iteration includes an inner iteration and an outer iteration.

[0121] Iteration refers to repeatedly performing a set of operations, improving the current estimate each time using the result of the previous iteration. The stopping condition for iteration can be reaching the maximum number of iterations or estimation convergence. Estimation convergence means that the target channel estimates obtained from two consecutive two-level iterations converge. Convergence can be understood as the difference between the target channel estimates obtained from two consecutive two-level iterations being sufficiently small, for example, less than a preset convergence threshold. Convergence means that the channel estimate no longer changes significantly with increasing iteration count, and it can be considered that a stable and reliable channel estimate has been found.

[0122] The following is through Figure 5 The illustrated embodiment provides a detailed explanation of the two-layer iteration.

[0123] Figure 5 A flowchart illustrating the multi-user channel estimation method provided in this application. Figure 2 ,like Figure 5 As shown, a two-level iteration includes the following steps S501-S503.

[0124] S501. Based on the data sub-region and pilot sub-region allocated to the user, multiple effective paths are separated from the received signal of the user to obtain a coarse channel estimate.

[0125] An effective path refers to the non-zero response component of the user channel in the delay-Doppler domain that is identified from the received signal, i.e., the actual multipath component that exists.

[0126] The coarse channel estimate is the channel response initially extracted from the received signal based solely on the pilot and data sub-regions of the user, without eliminating interference from other users.

[0127] Step S501 belongs to the inner iteration. In one optional implementation, the inner iteration includes multiple effective path searches. Specifically, the specific implementation process of separating multiple effective paths from the user's received signal to obtain a coarse channel estimate includes: performing multiple effective path searches on the user's received signal until the search stopping condition is met, so as to separate multiple effective paths and obtain a coarse channel estimate.

[0128] Each valid path search includes the following operations (1)-(4).

[0129] (1) In the user's pilot sub-region, search for the energy peak of the received signal in this effective path search.

[0130] For example, in the pilot sub-region of the u-th user, the base station searches for the energy peak of the received signal for each possible time delay index. .

[0131] in, For fractional Doppler frequency shift, This represents the starting position (i.e., the reference delay index) of the pilot sub-region for the u-th user on the time delay axis. To offset from the start time delay of the pilot region The specific delay index is used to traverse possible multipath delay locations. Not the original received signal, but the pilot sub-region of the u-th user at coordinates DD ( The received signal value observed at point () is used for energy comparison to determine whether there is a valid path. The energy peak value is the absolute value of the received signal value.

[0132] After obtaining the energy peak, determine whether the energy peak exceeds the adaptive threshold.

[0133] (2) If the energy peak exceeds the adaptive threshold, determine the time delay index corresponding to the energy peak as the valid time delay index.

[0134] If the energy peak exceeds the adaptive threshold Then determine the delay. Valid, recorded as .

[0135] Optionally, adaptive threshold The calculation formula is as follows:

[0136]

[0137] in, The imaginary unit, Let be the standard deviation of additive white Gaussian noise in the DD domain. Pilot signal-to-noise ratio in dB. The total length of the Doppler dimension. Total number of users For the summation formula, and Used for values ​​from 1 to The terms are summed up to compensate for capability leakage caused by fractional Doppler in multi-user scenarios.

[0138] It should be noted that the energy peak value can also be replaced with the modulus peak value.

[0139] (3) Taking the location of the energy peak as the center, within the preset Doppler range, perform step size search by autocorrelation operation with the pilot sequence to obtain fractional Doppler frequency shift and channel gain.

[0140] The size of the preset Doppler range can be set according to actual needs, and this application does not limit it.

[0141] For example, centered on the detected peak location, within a small Doppler range (such as...) (using a grid of points), a refined step-size search is performed through autocorrelation calculations with the pilot sequence to accurately estimate the fractional Doppler frequency shift. and the corresponding channel gain .

[0142] The pilot sequence is a reference signal known at both the transmitting and receiving ends.

[0143] (4) Determine the effective path based on the effective delay index, fractional Doppler frequency shift and channel gain.

[0144] For example, the latency index estimated in the above steps Fractional Doppler frequency shift and the corresponding channel gain Form the strongest effective path .

[0145] (5) Determine the received signal for the next valid path search based on the valid path.

[0146] In one optional implementation, the specific process of determining the received signal for the next valid path search based on the valid path includes: reconstructing the contribution value of the valid path to the received signal based on the valid path; subtracting the contribution value from the received signal of the current valid path search, and the remaining signal obtained is the received signal for the next valid path search.

[0147] After the current valid path search is completed, if the search stopping condition is met, the search is stopped and the coarse channel estimate obtained from the current valid path search is output; if the search stopping condition is not met, step (5) is executed, and the next valid path search is performed based on the received signal of the next valid path search. This process is repeated multiple times until the search stopping condition is met.

[0148] Optionally, the search stopping condition can be that no energy in the received signal of the current valid path search exceeds an adaptive threshold. The effective path or the maximum number of preset paths.

[0149] It should be noted that if there is no energy in the received signal exceeding the adaptive threshold... If a valid path is not found, the search should be stopped as the path is invalid.

[0150] When a user's signal traverses multiple physical paths, and these paths have the same integer delay index in the DD domain but very similar fractional Doppler shifts, their responses will alias into a single peak in the received signal. If this superposition of multiple paths cannot be distinguished, it can lead to missed path detections and severe channel estimation bias. To address this problem, this application proposes an effective path search scheme that performs multiple effective path searches on the user's received signal until a search stopping condition is met, thereby separating multiple effective paths.

[0151] S502. Based on the coarse channel estimates of other users besides the user, determine the total interference caused by other users to the user's received signal, and determine the difference between the user's received signal and the total interference as the clean received signal.

[0152] Total interference refers to the superimposed interference introduced into the signal received by the current user by all users other than the current user due to reasons such as non-perfect orthogonality of resources or signal leakage.

[0153] A clean received signal refers to the received signal obtained by subtracting the estimated total interference from the original received signal, which is closer to the received signal containing only the current user signal.

[0154] For each of the multiple users, step S501 can be executed separately to obtain a coarse channel estimate for each user. After obtaining the coarse channel estimates for all users, an outer iteration is performed, which includes step S502. Specifically, for each user, the... Taking a user as an example, the base station utilizes, except for the first user... All users other than that user The coarse estimate of the channel is used to calculate the values ​​of all other users. Together on the first The total interference caused by the received signals of each user. Then, from the first... Subtracting the total interference from the original received signal of each user yields a clean received signal. .

[0155] For example, step S502 can be implemented by the following formula:

[0156]

[0157] in, For the base station received, belonging to the first The original received signal of each user in the DD domain The value at that location, For indexes of other users, satisfy , For the first The user is located at the center of its pilot subregion in the DD domain. Known pilot symbols emitted at that location, For the first The central index of each user pilot subregion on the Doppler axis (i.e., the Doppler coordinates of its pilot symbol) For the first The reference index of each user pilot sub-region on the time delay axis is the starting time delay of the pilot region. The total length of the Doppler dimension. For the first The number of effective paths estimated in each user channel. For the first A coarse estimate of the channel gain for the i-th path of a user. No. Doppler frequency shift estimate for the i-th path of a user It is the known response function (or pulse shaping / spreading function) of the pilot signal in the Doppler domain, used to describe the energy diffusion characteristics of a single pilot symbol in the Doppler dimension. To represent the contribution of the Doppler shift caused by path i to the signal at point k, To sum the variables, iterate through the entire Doppler dimension (0 ≤ 0 ≤ 1). ≤ -1), used for circular convolution or coupling effects on the Doppler axis. The total length of the delay dimension. The phase rotation factor caused by Doppler-time delay coupling. Defined as:

[0158]

[0159] in, The imaginary unit is exp, which represents an exponential function.

[0160] Most pilot design and channel estimation algorithms in related technologies are designed under single-user or weak interference assumptions, lacking effective suppression mechanisms for pilot interference between multiple users. Under high user density, the pilot signal energy of one user can leak and interfere with the channel estimation process of other users, leading to a significant decrease in estimation accuracy. This application addresses this problem by providing a channel estimation scheme that removes interference from other users, thereby improving estimation accuracy.

[0161] S503. Separate multiple effective paths from the user's clean received signal to obtain the target channel estimate.

[0162] The outer iteration also includes step S503, which is executed after step S502. Specifically, for each user, the base station uses the user's clean received signal as new input and re-applies the above-described effective path search method to perform channel estimation for that user, in order to separate multiple effective paths and obtain a more accurate channel estimation result, i.e., the target channel estimation value. Since the clean received signal removes pilot interference from other users compared to the original received signal, the effective paths separated from the clean received signal are more accurate, thereby improving the accuracy of channel estimation.

[0163] It should be noted that multiple users can execute the above channel estimation process in parallel, which is a two-level iteration.

[0164] In this embodiment, steps S501-S503 represent one double-layer iteration. The double-layer iteration is repeated, that is, multiple double-layer iterations are performed sequentially until the iteration stopping condition is met. For example, the iteration stopping condition is reaching a preset maximum number of iterations or estimation convergence. After completing one double-layer iteration, if the iteration stopping condition is met, the double-layer iteration is stopped, and the target channel estimate obtained in this double-layer iteration is regarded as the final channel estimate. If the iteration stopping condition is not met, the clean received signal obtained in this double-layer iteration is used as the new received signal, and the next double-layer iteration is performed.

[0165] It is understood that this embodiment adopts a two-layer iterative structure and can run on the central processor of the base station.

[0166] This application employs a combination of iterative interference cancellation and channel refinement for channel estimation. First, in each iteration, a coarse estimate of the channel (i.e., a coarse channel estimate) is extracted from the received signal using the known data sub-region and pilot sub-region of the user. Interference from other users is not considered at this stage. Next, using the coarse channel estimates of other users, the total interference they cause to the current user's received signal is reconstructed and calculated. This total interference is then subtracted from the received signal to obtain a clean received signal. Subsequently, based on this clean received signal and the user's resource region, the effective path is re-separated to obtain a more accurate channel estimate. Through multiple iterations, inter-user interference is gradually suppressed, allowing the channel estimate to continuously approach the true channel. Finally, the target channel estimate is output when the iteration stopping condition is met. The entire process relies on the known allocation information of each user's resource region and improves the channel estimation accuracy through cross-user interference estimation and cancellation.

[0167] For example, Figure 6 A flowchart illustrating the multi-user channel estimation method provided in this application. Figure 3 ,like Figure 6 As shown, the channel estimation process is a two-level iterative structure. The inputs are the received signal, the maximum number of iterations, the maximum number of paths, and the adaptive threshold, and the output is the target channel estimate.

[0168] This application separates and estimates indistinguishable multipath signals for a single user by eliminating serial interference. Based on this, multi-user joint iteration—that is, using coarse channel estimates from all users—reconstructs and eliminates interference between multiple users at the base station. Then, a more accurate single-user channel estimate is performed on the purified signal, thus improving channel estimation accuracy.

[0169] For example, Figure 7 The schematic diagram of channel estimation performance under multi-user pilot design provided in this application is as follows: Figure 7As shown, when the channel estimation algorithm (two-layer iterative joint optimization) of this application is adopted, the channel estimation accuracy is improved. For example, at a signal-to-noise ratio (SNR) of 30 dB, the normalized mean squared error (NMSE) performance is 6 dB to 14 dB lower than that of the traditional scheme. The traditional scheme is exemplified by iterative peak search and the limited-memory Broyden–Fletcher–Goldfarb–Shanno (L-BFGS) method.

[0170] This application also provides a multi-user pilot resource allocation device, which is integrated in a base station.

[0171] Figure 8 A schematic diagram of the structure of the multi-user pilot resource allocation device provided in this application is shown below. Figure 8 As shown, the multi-user pilot resource allocation device 80 includes:

[0172] The allocation module 801 is used to divide the delay-Doppler domain into a data region and a pilot region;

[0173] The allocation module 801 is also used to allocate corresponding data sub-regions and pilot sub-regions to multiple users in the data area and pilot area respectively;

[0174] The sending module 802 is used to send control signaling to each user. The control signaling carries the resource allocation result so that the user can place a known pilot symbol at a predefined reference position in the corresponding pilot sub-region, and place zero symbols at other positions in the pilot sub-region.

[0175] In one possible implementation, the allocation module 801 is used for:

[0176] The data area is divided into multiple data sub-areas along the time delay axis and assigned to different users;

[0177] The pilot region is divided into multiple pilot sub-regions along the Doppler axis and assigned to different users.

[0178] In one possible implementation, for the u-th user and the (u+1)-th user whose pilot sub-regions are adjacent on the Doppler axis among multiple users, the free resources between the upper boundary of the pilot sub-region of the u-th user and the lower boundary of the pilot sub-region of the (u+1)-th user belong to the protection interval shared by the two users.

[0179] In one possible implementation, an anti-interference protection interval is also included between the pilot sub-region of the u-th user and the pilot sub-region of the (u+1)-th user, and the symbol width of the anti-interference protection interval is a preset width.

[0180] In one possible implementation, the multi-user pilot resource allocation device 80 further includes a user scheduling module, used for:

[0181] Get the largest integer Doppler index;

[0182] Based on preset constraints, the total number of users that the base station can currently support is determined according to the maximum integer Doppler index and the Doppler dimension of the delay-Doppler domain.

[0183] User scheduling is based on the total number of users.

[0184] The multi-user pilot resource allocation device 80 provided in this embodiment can execute the method provided in the above method embodiment. Its implementation principle and technical effect are similar, and will not be described in detail here.

[0185] This application also provides a multi-user channel estimation apparatus, which is integrated in a base station.

[0186] Figure 9 A schematic diagram of the multi-user channel estimation device provided in this application is shown below. Figure 9 As shown, the multi-user channel estimation device 90 includes:

[0187] Acquisition module 901 is used to acquire the received signal of any one of multiple users;

[0188] The channel estimation module 902 is used to perform channel estimation for the user based on the data sub-region and pilot sub-region allocated to the user and the user's received signal using a two-layer iterative structure. During the channel estimation process, total interference is removed to obtain the target channel estimation value. Total interference refers to the total interference caused to the user's received signal by other users among multiple users excluding the user itself.

[0189] The data sub-regions and pilot sub-regions allocated to users are based on, for example... Figure 8 The multi-user pilot resource allocation device provided in the illustrated embodiment is determined.

[0190] In one possible implementation, the channel estimation module 902 is used for:

[0191] Execute multiple double-layer iterations sequentially until the iteration stopping condition is met; each double-layer iteration includes an inner iteration and an outer iteration, and specifically includes the following operations:

[0192] In the inner iteration: based on the data sub-region and pilot sub-region allocated to the user, multiple effective paths are separated from the user's received signal to obtain a coarse channel estimate;

[0193] In the outer iteration:

[0194] Based on the coarse channel estimates of users other than the user, the total interference caused by users other than the user to the user's received signal is determined, and the difference between the user's received signal and the total interference is determined as the clean received signal;

[0195] Multiple effective paths are separated from the user's clean received signal to obtain the target channel estimate.

[0196] In one possible implementation, the channel estimation module 902, when separating multiple effective paths from the user's received signal based on the data sub-region and pilot sub-region allocated to the user to obtain a coarse channel estimate, is used to:

[0197] Multiple effective path searches are performed on the user's received signal until the search stopping condition is met, in order to separate multiple effective paths and obtain a coarse channel estimate; wherein each effective path search includes the following operations:

[0198] Within the user's pilot sub-region, search for the peak energy of the received signal in this valid path search;

[0199] If the energy peak exceeds the adaptive threshold, the delay index corresponding to the energy peak is determined as the valid delay index;

[0200] Centered on the location of the energy peak, within a preset Doppler range, a step-size search is performed by autocorrelation operation with the pilot sequence to obtain the fractional Doppler frequency shift and channel gain;

[0201] The effective path is determined based on the effective delay index, fractional Doppler frequency shift, and channel gain.

[0202] The received signal for the next valid path search is determined based on the valid path.

[0203] In one possible implementation, the channel estimation module 902, when determining the received signal for the next effective path search based on the effective path, is used to:

[0204] The contribution of the effective path to the received signal is reconstructed based on the effective path.

[0205] The contribution value is subtracted from the received signal of the current valid path search to obtain the received signal of the next valid path search.

[0206] The multi-user channel estimation device 90 provided in this embodiment can execute the method provided in the above method embodiment. Its implementation principle and technical effect are similar, and will not be described in detail here.

[0207] Figure 10 This is a schematic diagram of the base station structure provided in this application. Figure 10 As shown, the base station 10 provided in this embodiment includes a processor 101 and a memory 102 that is communicatively connected to the processor 101.

[0208] Optionally, the base station 10 also includes a communication component 103. The processor 101, memory 102, and communication component 103 are connected via a bus.

[0209] In the specific implementation process, the processor 101 executes the computer execution instructions stored in the memory 102, causing the processor 101 to perform the above-described method.

[0210] The specific implementation process of processor 101 can be found in the above method embodiments, and its implementation principle and technical effect are similar. It will not be repeated here.

[0211] In the above embodiments, it should be understood that the processor can be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), etc. The general-purpose processor can be a microprocessor or any conventional processor. The steps of the method disclosed in this invention can be directly implemented by a hardware processor, or implemented by a combination of hardware and software modules within the processor.

[0212] The memory may include random access memory (RAM) and may also include non-volatile memory (NVM), such as at least one disk storage device.

[0213] Buses can be Industry Standard Architecture (ISA) buses, Peripheral Component Interconnect (PCI) buses, or Extended Industry Standard Architecture (EISA) buses, etc. Buses can be categorized into address buses, data buses, control buses, etc.

[0214] This application also provides a computer program product, including a computer program that, when executed by a processor, implements the above-described method.

[0215] This application also provides a computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, implement the above-described method.

[0216] The aforementioned readable storage medium can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as read-only memory (ROM), static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), magnetic storage, flash memory, magnetic disk, or optical disk. The readable storage medium can be any available medium accessible to a general-purpose or special-purpose computer.

[0217] An exemplary readable storage medium is coupled to a processor, enabling the processor to read information from and write information to the readable storage medium. Of course, the readable storage medium can also be a component of the processor. The processor and the readable storage medium can reside in an application-specific integrated circuit (ASIC). Alternatively, the processor and the readable storage medium can exist as discrete components in the device.

[0218] The division of units is merely a logical functional division; in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be indirect coupling or communication connection through some interfaces, devices, or units, and may be electrical, mechanical, or other forms.

[0219] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0220] In addition, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0221] If a function is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium.

[0222] Finally, it should be noted that other embodiments of this application will readily conceive of by those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein, and is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and alterations may be made without departing from its scope. The scope of this application is limited only by the appended claims.

Claims

1. A multi-user pilot resource allocation method, characterized in that, Applied to a base station, the method includes: The delay-Doppler domain is divided into a data region and a pilot region; In the data area and the pilot area, corresponding data sub-areas and pilot sub-areas are allocated to multiple users respectively; Control signaling is sent to each of the users, the control signaling carrying resource allocation results, so that the user places a known pilot symbol at a predefined reference position in the corresponding pilot sub-region, and places zero symbols at other positions in the pilot sub-region; The process of allocating corresponding data sub-regions and pilot sub-regions for multiple users in the data region and the pilot region respectively includes: The data region is divided into multiple data sub-regions along the time delay axis and assigned to different users; The pilot region is divided into multiple pilot sub-regions along the Doppler axis and assigned to different users.

2. The method according to claim 1, characterized in that, For the u-th user and the (u+1)-th user whose pilot sub-regions are adjacent on the Doppler axis among the multiple users, the idle resources between the upper boundary of the pilot sub-region of the u-th user and the lower boundary of the pilot sub-region of the (u+1)-th user belong to the protection interval shared by the two users.

3. The method according to claim 2, characterized in that, An anti-interference protection interval is also included between the pilot sub-region of the u-th user and the pilot sub-region of the (u+1)-th user, and the symbol width of the anti-interference protection interval is a preset width.

4. The method according to claim 1, characterized in that, The method further includes: Get the largest integer Doppler index; Based on preset constraints, the total number of users that the base station can currently support is determined according to the maximum integer Doppler index and the Doppler dimension of the delay-Doppler domain. User scheduling is performed based on the total number of users.

5. A multi-user channel estimation method, characterized in that, Applied to a base station, the method includes: Acquire the received signal of any one of multiple users; A two-layer iterative structure is adopted. Based on the data sub-region and pilot sub-region allocated to the user and the user's received signal, channel estimation is performed on the user. During the channel estimation process, total interference is removed to obtain the target channel estimation value. The total interference refers to the total interference caused to the user's received signal by other users among multiple users besides the user. The data sub-region and pilot sub-region allocated to the user are determined based on the multi-user pilot resource allocation method as described in any one of claims 1-4.

6. The method according to claim 5, characterized in that, The method employs a two-layer iterative structure, performing channel estimation for the user based on the data sub-region and pilot sub-region allocated to the user, as well as the user's received signal. Total interference is removed during the channel estimation process to obtain the target channel estimate, including: Execute multiple double-layer iterations sequentially until the iteration stopping condition is met; each double-layer iteration includes an inner iteration and an outer iteration, and specifically includes the following operations: In the inner iteration: based on the data sub-region and pilot sub-region allocated to the user, multiple effective paths are separated from the user's received signal to obtain a coarse channel estimate; In the outer iteration: Based on the coarse channel estimates of other users besides the user, the total interference caused by other users to the received signal of the user is determined, and the difference between the received signal of the user and the total interference is determined as the clean received signal; Multiple effective paths are separated from the user's clean received signal to obtain the target channel estimate.

7. The method according to claim 6, characterized in that, The step of separating multiple effective paths from the user's received signal based on the data sub-region and pilot sub-region allocated to the user to obtain a coarse channel estimate includes: Multiple effective path searches are performed on the user's received signal until the search stopping condition is met, in order to separate multiple effective paths and obtain a coarse channel estimate; wherein each effective path search includes the following operations: In the user's pilot sub-region, search for the energy peak value of the received signal in this valid path search; If the energy peak exceeds the adaptive threshold, the delay index corresponding to the energy peak is determined to be a valid delay index; Centered on the location of the energy peak, within a preset Doppler range, a step-size search is performed by autocorrelation operation with the pilot sequence to obtain the fractional Doppler frequency shift and channel gain; The effective path is determined based on the effective delay index, fractional Doppler frequency shift, and channel gain. The received signal for the next valid path search is determined based on the valid path.

8. The method according to claim 7, characterized in that, The step of determining the received signal for the next valid path search based on the valid path includes: The contribution value of the effective path to the received signal is reconstructed based on the effective path. The contribution value is subtracted from the received signal of the current effective path search to obtain the received signal of the next effective path search.

9. A multi-user pilot resource allocation device, characterized in that, Integrated in a base station, the device includes: The allocation module is used to divide the delay-Doppler domain into a data region and a pilot region; The allocation module is further configured to allocate corresponding data sub-regions and pilot sub-regions to multiple users in the data region and the pilot region, respectively. The sending module is used to send control signaling to each of the users. The control signaling carries resource allocation results so that the user places a known pilot symbol at a predefined reference position in the corresponding pilot sub-region, and places zero symbols at other positions in the pilot sub-region. The process of allocating corresponding data sub-regions and pilot sub-regions for multiple users in the data region and the pilot region respectively includes: The data region is divided into multiple data sub-regions along the time delay axis and assigned to different users; The pilot region is divided into multiple pilot sub-regions along the Doppler axis and assigned to different users.

10. A multi-user channel estimation device, characterized in that, Integrated in a base station, the device includes: The acquisition module is used to acquire the received signal of any one of multiple users; The channel estimation module is used to perform channel estimation for the user based on the data sub-region and pilot sub-region allocated to the user and the user's received signal, using a two-layer iterative structure. During the channel estimation process, total interference is removed to obtain a target channel estimation value. The total interference refers to the total interference caused to the user's received signal by other users among multiple users besides the user mentioned above. The data sub-region and pilot sub-region allocated to the user are determined based on the multi-user pilot resource allocation device as described in claim 9.

11. A base station, characterized in that, include: A processor and a memory communicatively connected to the processor; The memory stores computer-executed instructions; The processor executes computer execution instructions stored in the memory, causing the processor to perform the multi-user pilot resource allocation method as described in any one of claims 1-4 or the multi-user channel estimation method as described in any one of claims 5-8.

12. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer-executable instructions, which, when executed by a processor, are used to implement the multi-user pilot resource allocation method as described in any one of claims 1-4 or the multi-user channel estimation method as described in any one of claims 5-8.

13. A computer program product, characterized in that, It includes a computer program that, when executed by a processor, implements the multi-user pilot resource allocation method as described in any one of claims 1-4 or the multi-user channel estimation method as described in any one of claims 5-8.

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