Terahertz frequency band subcarrier distribution method and system

Abstract

The invention relates to the technical field of wireless communication, and provides a terahertz frequency band subcarrier distribution method and system, and the method comprises the steps: determining a beam splitting range under a terahertz frequency band in an MIMO system which comprises K single antenna users, is equipped with a base station of Nt uniform linear array antennas, and employs M subcarriers to transmit signals; within the beam splitting range, calculating normalized gains of each user at different subcarriers; and according to the normalized gain of each user at different subcarriers, carrying out preferential division and selection on all the subcarriers to obtain a subcarrier distribution result of each user. According to the invention, each subcarrier can be adapted to the optimal user in the direction according to the beam direction deviation caused by beam splitting, the problem of low communication performance quality of the edge user under the beam splitting condition is effectively overcome, the resource utilization rate and the overall performance of the base station are improved, the transmission rate of the system is improved, and the user experience is improved. And the power consumption of the whole system is reduced.

Description

Technical Field

[0001] The present invention relates to the field of wireless communication technology, and more specifically, to a terahertz frequency band subcarrier allocation method and system. Background Art

[0002] With the improvement of 5G technology and the development of 6G technology, terahertz (THz) communication is considered to be a promising technology to meet 6G's needs for higher data transmission rates, higher energy efficiency, lower latency and diversified users, and to further improve communication performance. Terahertz refers to electromagnetic waves with a frequency of 100GHz-10THz and a wavelength between 30μm-3mm. At present, terahertz communication can support extremely high data rates in future 6G wireless communications, and the bandwidth of the terahertz band has increased 10 times compared to the existing millimeter wave (mmWave) band, and has the advantages of high noise resistance, high transmission stability, and transient performance.

[0003] As the carrier frequency increases, the terahertz signal will be more severely attenuated, which is an important issue that cannot be ignored in terahertz communication. Different from millimeter wave communication, the beam splitting caused by the terahertz frequency band cannot be ignored. The performance loss of its edge subcarriers is proportional to the center frequency f. c =100GHz, bandwidth B = 5GHz, for example, the performance loss of the most edge subcarrier is approximately 80%. However, there are often differences in user distribution. In dense urban environments, the channel conditions of users in different locations may vary greatly, especially for users at the edge of the subcarrier, and effective resource allocation cannot be achieved. For the above situation, especially for the problem of subcarrier performance degradation caused by beam splitting, it is necessary to redevelop a new subcarrier allocation strategy to optimize the resource utilization efficiency of the base station and ensure that all users can get a good communication experience.

[0004] The existing hybrid precoding MIMO structure will produce serious beam splitting in the THz frequency band, resulting in a serious mismatch between the edge subcarrier and the beam designed according to the center subcarrier, resulting in performance degradation. At present, a time-phase hybrid analog precoding analog architecture with two layers of delays and phase shifters has been proposed to alleviate beam splitting. Although this technology can alleviate the low gain of the edge subcarrier caused by beam splitting, it will not only increase the complexity of the hardware, but also increase the complexity and time of the calculation. Summary of the invention

[0005] The present invention provides a terahertz frequency band subcarrier allocation method and system to overcome the defects of decreased subcarrier performance and low resource utilization efficiency caused by beam splitting in the terahertz frequency band.

[0006] In order to solve the above technical problems, the technical solution of the present invention is as follows:

[0007] A terahertz frequency band subcarrier allocation method comprises the following steps:

[0008] For K single-antenna users, equipped with N t In a MIMO system having a base station with a uniform linear array (ULA) antenna and using M subcarriers to transmit signals, determining a beam splitting range;

[0009] Calculating the normalized gain of each user at different subcarriers within the beam splitting range;

[0010] According to the normalized gain of each user at different subcarriers, all subcarriers are optimally divided and selected to obtain the subcarrier allocation result of each user.

[0011] Furthermore, the present invention also proposes a terahertz frequency band subcarrier allocation system, which is applied to K single-antenna users equipped with N t A MIMO system in which a base station has a uniform linear array antenna and uses M subcarriers to transmit signals, including:

[0012] A beam splitting range calculation module is used to calculate the beam splitting range of the current MIMO system;

[0013] A gain calculation module, used to calculate the normalized gain of each user at different subcarriers within the beam splitting range;

[0014] The subcarrier allocation module is used to preferentially divide and select all subcarriers according to the normalized gain of each user at different subcarriers, and output the subcarrier allocation result of each user.

[0015] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0016] The present invention aims to effectively improve communication efficiency and reliability by optimizing subcarrier resource allocation within the beam splitting range without adding any hardware; specifically, by determining the beam splitting range of the MIMO system in the terahertz frequency band, calculating the normalized gains of multiple users at different positions within the beam splitting range, and preferentially allocating based on the user with the largest gain at a subcarrier, ensuring that each subcarrier corresponds to the optimal user, and generating a subcarrier allocation result;

[0017] The present invention enables each subcarrier to adapt to the best user in that direction according to the beam direction deviation caused by beam splitting, effectively overcomes the problem of low communication performance quality of edge users under beam splitting conditions, improves the resource utilization and overall performance of the base station, increases the transmission rate of the system, and reduces the power consumption of the overall system. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The figure is a flow chart of a method for allocating subcarriers in a terahertz frequency band according to an embodiment of the present invention.

[0019] Figure 2 The figure is a schematic diagram of achievable rates for different numbers of users under different signal-to-noise ratio conditions according to an embodiment of the present invention.

[0020] Figure 3 The figure is a schematic diagram showing the relationship between the number of users and the achievable rate under different signal-to-noise ratio conditions according to an embodiment of the present invention.

[0021] Figure 4 The figure is a schematic diagram showing the relationship between the number of subcarriers and the achievable rate under different signal-to-noise ratio conditions according to an embodiment of the present invention.

[0022] Figure 5 The figure is a schematic diagram of a terahertz frequency band subcarrier allocation system according to an embodiment of the present invention. DETAILED DESCRIPTION

[0023] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, the same numbers in different drawings represent the same or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Instead, they are merely examples of devices and methods consistent with some aspects of the present invention as detailed in the appended claims.

[0024] The terms used in the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The singular forms "a", "the" and "the" used in the present invention and the appended claims are also intended to include plural forms unless the context clearly indicates other meanings. It should also be understood that the term "and / or" used herein refers to and includes any or all possible combinations of one or more associated listed items.

[0025] It should be understood that although the terms first, second, third, etc. may be used in the present invention to describe various information, these information should not be limited to these terms. These terms are only used to distinguish the same type of information from each other. For example, without departing from the scope of the present invention, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Depending on the context, the word "if" as used herein may be interpreted as "at the time of" or "when" or "in response to determining".

[0026] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0027] Example 1

[0028] This embodiment proposes a terahertz frequency band subcarrier allocation method, such as Figure 1 FIG. 1 is a flow chart of the terahertz frequency band subcarrier allocation method of this embodiment.

[0029] The terahertz frequency band subcarrier allocation method proposed in this embodiment includes the following steps:

[0030] S1, for K single-antenna users, equipped with N t In a MIMO system with a base station having a uniform linear array antenna and using M subcarriers to transmit signals, determining a beam splitting range in a terahertz frequency band;

[0031] S2. Calculate the normalized gain of each user at different subcarriers within the beam splitting range;

[0032] S3. According to the normalized gain of each user at different subcarriers, all subcarriers are preferentially divided and selected to obtain the subcarrier allocation result of each user.

[0033] This embodiment effectively improves communication efficiency and reliability by optimizing subcarrier resource allocation within the beam splitting range without adding any hardware. Specifically, by determining the beam splitting range of the MIMO system in the terahertz frequency band, calculating the normalized gains of multiple users at different positions within the beam splitting range, and preferentially allocating the user with the largest gain at a subcarrier, a subcarrier allocation result is generated, which can effectively overcome the problem of low communication performance quality of edge users under beam splitting conditions, improve the resource utilization and overall performance of the base station, improve the transmission rate of the system, and reduce the power consumption of the overall system.

[0034] In the traditional hybrid precoding MIMO structure, all subcarriers under the current bandwidth are used to serve the communication of a single central user, so that the actual beam pointing on the edge subcarrier deviates from the user, and the performance is reduced. In comparison, this embodiment determines the user with the largest gain at each subcarrier through refined multi-user subcarrier allocation, so that each subcarrier can adapt to the best user in that direction according to the beam direction deviation caused by beam splitting, thereby effectively improving the average achievable rate of users.

[0035] In an optional embodiment, in step S1, determining the beam splitting range of the MIMO system in the terahertz frequency band includes the following steps:

[0036] Based on the MIMO system, a steering vector of a receiving end at a primary user is determined. Its expression is:

[0037]

[0038] Among them, f c is the center frequency, θ c is the main user location, represents the distance between antennas; c is the speed of light; (.) T represents transpose;

[0039] Determine the channel model H of the mth subcarrier of the hybrid precoding structure m ; Its expression is:

[0040]

[0041] Among them, g l represents the gain of path l, τ l represents the delay of path l; f n represents the carrier frequency of the mth subcarrier, B is the bandwidth; L is the total number of channel paths;

[0042] The entire beam splitting range Θ is determined according to the frequency, bandwidth, number of subcarriers and the position of the primary user; its expression is:

[0043] Θ=ξ m *θ c

[0044]

[0045] Among them, ξ m Indicates the relative frequency of the mth subcarrier.

[0046] In an optional embodiment, in step S2, calculating the normalized gain of each user at different subcarriers includes:

[0047] According to the beam splitting range Θ, the steering vector of each user receiving end within the beam splitting range Θ is updated; its expression is:

[0048]

[0049] Among them, k,m represents the steering vector of user k at the mth subcarrier; represents the distance between antennas; f m represents the carrier frequency of the mth subcarrier, c is the speed of light; θ k represents the position of the kth user within the beam splitting range Θ; (.) T represents transpose;

[0050] Based on the steering vector of each user within the beam splitting range, the normalized gain of each user at different subcarriers is calculated, and its expression is:

[0051]

[0052] Among them, η k,m represents the normalized gain of user k at the mth subcarrier; represents the steering vector al at the receiving end of the primary user c The conjugate transpose of . Then the normalized gain of all users at all subcarriers is expressed as

[0053] In an optional embodiment, in step S3, all subcarriers are preferentially divided and selected according to the normalized gain of each user at different subcarriers, including:

[0054] Traverse all subcarriers, and for the mth subcarrier, allocate it to the user with the largest gain based on the normalized gain of each user at the current subcarrier until the allocation of M subcarriers is completed; its expression is:

[0055]

[0056] Among them, φ idx represents the subcarrier code assigned to the idx user, that is, the code of the m-th subcarrier; idx∈{1,2,…,K} is the user number with the largest normalized gain at the m-th subcarrier;

[0057] According to the allocation results of all subcarriers, the set of subcarrier codes allocated to K users is output as Φ = [φ1, φ2, …, φ K ].

[0058] In this embodiment, when determining the normalized gains of all subcarriers of all users After that, according to the normalized gain η 1:K,1:M Screen the subcarriers and determine the user η with the largest gain under the mth subcarrier idx,m , traverse the M subcarriers in turn, thus completing the allocation of M subcarriers to K users. idx,m =[φ idx ,idx] represents the user allocation scheme for the mth subcarrier. Specifically, the assigned user number is idx, and the assigned subcarrier code is φ idx .

[0059] Exemplarily, the execution process is expressed as:

[0060] Input: User position θ = [θ1, θ2, …θ K ], initialization: Φ=[φ1,φ2,…,φ K ],in Represents the empty set.

[0061] Output: Subcarrier allocation result Φ = φ1, φ2, ..., φ K ;

[0062] The pseudo code is as follows:

[0063]

[0064] The final result returned is the subcarrier allocation result, that is, the set Φ of subcarrier numbers allocated to each of the K users after allocation.

[0065] Furthermore, in an optional embodiment, the method further includes:

[0066] S4. Calculate the steering vector and channel of each user receiving end based on the subcarrier allocation result, compare the average achievable rate after multi-user subcarrier allocation with the average achievable rate of a single user in the traditional hybrid precoding, and evaluate the subcarrier allocation effect.

[0067] Among them, the steering vector after the kth user reallocates subcarriers is It is expressed as:

[0068]

[0069] The channel of the kth user after allocating subcarriers It is expressed as:

[0070]

[0071] where φ k Indicates the subcarrier set allocated to the kth user;

[0072] By traversing the subcarrier set φ after the kth user is assigned m , solve for the subcarrier set φ m The average achievable rate of the kth user corresponding to each subcarrier in Its expression is:

[0073]

[0074] in, represents the channel on the i-th allocated subcarrier of the k-th user, and i∈φ k .

[0075] As an exemplary illustration, in a specific implementation process, for the hybrid precoding MIMO structure, in the simulation experiment, it is assumed that the transmitter is equipped with a uniform linear array of 256 antenna elements, with a center frequency f c =100GHz, bandwidth is B=5GHz. The simulation results are as follows Figures 2 to 4 shown.

[0076] like Figure 2 As shown, it is a schematic diagram of the achievable rate under different signal-to-noise ratio conditions for different numbers of users, where the case where the number of users is 1 coincides with the traditional hybrid precoding structure solution.

[0077] like Figure 3 As shown in Figure 1, it is a schematic diagram of the relationship between the number of users and the achievable rate under different signal-to-noise ratio conditions. Figure 2 , 3 It can be seen that in the subcarrier allocation method described in this embodiment, the greater the number of users K, the better the performance.

[0078] like Figure 4 As shown in FIG. 1 , it is a schematic diagram of the relationship between the number of subcarriers and the achievable rate under different signal-to-noise ratio conditions. As can be seen from the figure, when the number of subcarriers M increases, the achievable rate is also improved.

[0079] Therefore, it can be seen from the above simulation results that the subcarrier allocation method described in this embodiment can effectively overcome the effect of low user gain caused by beam splitting in the terahertz frequency band.

[0080] Example 2

[0081] This embodiment proposes a terahertz frequency band subcarrier allocation system, such as Figure 5 , which is an architecture diagram of the terahertz frequency band subcarrier allocation system of this embodiment.

[0082] The terahertz frequency band subcarrier allocation system proposed in this embodiment is applied to K single-antenna users equipped with N t A MIMO system is provided in which a base station has a uniform linear array antenna and M subcarriers are used to transmit signals, wherein the subcarrier allocation system includes:

[0083] A beam splitting range calculation module is used to calculate the beam splitting range of the current MIMO system;

[0084] A gain calculation module, used to calculate the normalized gain of each user at different subcarriers within the beam splitting range;

[0085] The subcarrier allocation module is used to preferentially divide and select all subcarriers according to the normalized gain of each user at different subcarriers, and output the subcarrier allocation result of each user.

[0086] In an optional embodiment, the beam splitting range calculation module performs the following steps when calculating the beam splitting range of the current MIMO system:

[0087] Based on the MIMO system, the steering vector a1 of the receiving end at the primary user is determined. c ; Its expression is:

[0088]

[0089] Among them, fc c is the center frequency, θ c is the main user location, represents the distance between antennas; c is the speed of light; (.) T represents transpose;

[0090] Determine the channel model H of the mth subcarrier of the hybrid precoding structure m ; Its expression is:

[0091]

[0092] Among them, g l represents the gain of path l, τ l represents the delay of path l; f m represents the carrier frequency of the mth subcarrier, B is the bandwidth; L is the total number of channel paths;

[0093] The entire beam splitting range Θ is determined according to the frequency, bandwidth, number of subcarriers and the position of the primary user; its expression is:

[0094] Θ=ξ m *θ c

[0095]

[0096] Among them, ξ m Indicates the relative frequency of the mth subcarrier.

[0097] In an optional embodiment, the gain calculation module performs the following steps when calculating the normalized gain of each user at different subcarriers:

[0098] According to the beam splitting range Θ, the steering vector of each user receiving end within the beam splitting range Θ is updated; its expression is:

[0099]

[0100] Among them, k,m represents the steering vector of user k at the mth subcarrier; represents the distance between antennas; f m represents the carrier frequency of the mth subcarrier, c is the speed of light; θ k represents the position of the kth user within the beam splitting range Θ; (.) T represents transpose;

[0101] Based on the steering vector of each user within the beam splitting range, the normalized gain of each user at different subcarriers is calculated, and its expression is:

[0102]

[0103] Among them, η k,m represents the normalized gain of user k at the mth subcarrier; represents the steering vector al at the receiving end of the primary user c The conjugate transpose of .

[0104] In an optional embodiment, the subcarrier allocation module performs the following steps when preferentially dividing and selecting all subcarriers according to the normalized gains of each user at different subcarriers:

[0105] Traverse all subcarriers, and for the mth subcarrier, allocate it to the user with the largest gain based on the normalized gain of each user at the current subcarrier until the allocation of M subcarriers is completed; its expression is:

[0106]

[0107] Among them, φ idx represents the subcarrier code assigned to the idx user, that is, the code of the m-th subcarrier; idx∈{1,2,…,K} is the user number with the largest normalized gain at the m-th subcarrier;

[0108] According to the allocation results of all subcarriers, the set of subcarrier codes allocated to K users is output as Φ = [φ1, φ2, …, φ K ].

[0109] In an optional embodiment, the system further includes an evaluation module for evaluating the subcarrier allocation effect; wherein:

[0110] Based on the subcarrier allocation results, the steering vector and channel of each user's receiving end are calculated. The average achievable rate after multi-user subcarrier allocation is compared with the average achievable rate of a single user in traditional hybrid precoding to evaluate the subcarrier allocation effect.

[0111] It can be understood that the system of this embodiment corresponds to the method of the above-mentioned embodiment 1, and the options in the above-mentioned embodiment 1 are also applicable to this embodiment, so they will not be described repeatedly here.

[0112] Example 3

[0113] This embodiment proposes a computer device, including a memory and a processor, wherein the memory stores computer-readable instructions, and when the computer-readable instructions are executed by the processor, the processor executes all or part of the steps of the terahertz frequency band subcarrier allocation method proposed in Example 1.

[0114] Example 4

[0115] This embodiment proposes a storage medium on which computer-readable instructions are stored, wherein the computer-readable instructions, when executed by a processor, implement all or part of the steps of the terahertz frequency band subcarrier allocation method proposed in Embodiment 1.

[0116] Exemplarily, the storage medium includes, but is not limited to, a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk, and other media that can store program codes.

[0117] Exemplarily, the instructions, programs, code sets or instruction sets may be implemented using conventional programming languages.

[0118] Exemplarily, the processor includes but is not limited to a smart phone, a personal computer, a server, a network device, etc., and is used to execute all or part of the steps of the terahertz frequency band subcarrier allocation method described in Example 1.

[0119] Each embodiment of the present invention is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the device embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment. The device embodiment described above is merely exemplary, in which the modules described as separate components may or may not be physically separated, and the functions of each module can be implemented in the same or one or more software and / or hardware when implementing the scheme of the present invention. It is also possible to select some or all of the modules according to actual needs to achieve the purpose of the scheme of this embodiment.

[0120] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A terahertz frequency band subcarrier allocation method, characterized in that: The following steps are involved: For K single-antenna users, equipped with N t In a MIMO system with a base station having a uniform linear array antenna and using M subcarriers to transmit signals, determining a beam splitting range in a terahertz frequency band; Calculating the normalized gain of each user at different subcarriers within the beam splitting range; According to the normalized gain of each user at different subcarriers, all subcarriers are optimally divided and selected to obtain the subcarrier allocation result of each user.

2. The terahertz frequency band subcarrier allocation method according to claim 1, characterized in that: Determine the beam splitting range of the MIMO system in the terahertz frequency band, The following steps are involved: Based on the MIMO system, the steering vector a1 of the receiving end at the primary user is determined. c ; Its expression is: Among them, f c is the center frequency, θ c is the main user location, represents the distance between antennas; c is the speed of light; (.) T represents transpose; Determine the channel model H of the mth subcarrier of the hybrid precoding structure m ; Its expression is: Among them, g l represents the gain of path l, τ l represents the delay of path l; f m represents the carrier frequency of the mth subcarrier, m = 1, 2, ..., M; B is the bandwidth; L is the total number of channel paths; The entire beam splitting range Θ is determined according to the frequency, bandwidth, number of subcarriers and the position of the primary user; its expression is: Θ=ξ m *i c Among them, ξ m Indicates the relative frequency of the mth subcarrier.

3. The terahertz frequency band subcarrier allocation method according to claim 1, characterized in that: The calculating the normalized gain of each user at different subcarriers includes: According to the beam splitting range Θ, the steering vector of each user receiving end within the beam splitting range Θ is updated; its expression is: Among them, al k,m represents the steering vector of user k at the mth subcarrier; represents the distance between antennas; f m represents the carrier frequency of the mth subcarrier, c is the speed of light; θ k represents the position of the kth user within the beam splitting range Θ; (.) T represents transpose; Based on the steering vector of each user within the beam splitting range, the normalized gain of each user at different subcarriers is calculated, and its expression is: Among them, η k,m represents the normalized gain of user k at the mth subcarrier; represents the steering vector al at the receiving end of the primary user c The conjugate transpose of .

4. The terahertz frequency band subcarrier allocation method according to claim 3, characterized in that: The method of preferentially dividing and selecting all subcarriers according to the normalized gains of each user at different subcarriers includes: Traverse all subcarriers, and for the mth subcarrier, allocate it to the user with the largest gain based on the normalized gain of each user at the current subcarrier until the allocation of M subcarriers is completed; its expression is: Among them, φ idx represents the subcarrier code assigned to the idx user, that is, the code of the m-th subcarrier; idx∈{1,2,…,K} is the user number with the largest normalized gain at the m-th subcarrier; According to the allocation results of all subcarriers, the set of subcarrier codes allocated to K users is output as Φ = [φ1, φ2, …, φ K ].

5. The terahertz frequency band subcarrier allocation method according to any one of claims 1 to 4, characterized in that: The method further comprises: Based on the subcarrier allocation results, the steering vector and channel of each user's receiving end are calculated. The average achievable rate after multi-user subcarrier allocation is compared with the average achievable rate of a single user in traditional hybrid precoding to evaluate the subcarrier allocation effect.

6. A terahertz frequency band subcarrier allocation system, applied to K single-antenna users equipped with N t A MIMO system in which a base station has a uniform linear array antenna and uses M subcarriers to transmit signals, characterized in that: include: A beam splitting range calculation module is used to calculate the beam splitting range of the current MIMO system; A gain calculation module, used to calculate the normalized gain of each user at different subcarriers within the beam splitting range; The subcarrier allocation module is used to preferentially divide and select all subcarriers according to the normalized gain of each user at different subcarriers, and output the subcarrier allocation result of each user.

7. The terahertz frequency band subcarrier allocation system according to claim 6, characterized in that: In the beam splitting range calculation module, when calculating the beam splitting range of the current MIMO system, the following steps are performed: Based on the MIMO system, the steering vector a1 of the receiving end at the primary user is determined. c ; Its expression is: Among them, f c is the center frequency, θ c is the main user location, represents the distance between antennas; c is the speed of light; (.) T represents transpose; Determine the channel model H of the mth subcarrier of the hybrid precoding structure m ; Its expression is: Among them, g l represents the gain of path l, τ l represents the delay of path l; f m represents the carrier frequency of the mth subcarrier, m = 1, 2, ..., M; B is the bandwidth; L is the total number of channel paths; The entire beam splitting range Θ is determined according to the frequency, bandwidth, number of subcarriers and the position of the primary user; its expression is: Θ=ξ m *i c Among them, ξ m Indicates the relative frequency of the mth subcarrier.

8. The terahertz frequency band subcarrier allocation system according to claim 6, characterized in that: When calculating the normalized gain of each user at different subcarriers, the gain calculation module performs the following steps: According to the beam splitting range Θ, the steering vector of each user receiving end within the beam splitting range Θ is updated; its expression is: Among them, al k,m represents the steering vector of user k at the mth subcarrier; represents the distance between antennas; f m represents the carrier frequency of the mth subcarrier, c is the speed of light; θ k represents the position of the kth user within the beam splitting range Θ; (.) T represents transpose; Based on the steering vector of each user within the beam splitting range, the normalized gain of each user at different subcarriers is calculated, and its expression is: Among them, η k,m represents the normalized gain of user k at the mth subcarrier; represents the steering vector al at the receiving end of the primary user c The conjugate transpose of .

9. The terahertz frequency band subcarrier allocation system according to claim 7, characterized in that: The subcarrier allocation module performs the following steps when preferentially dividing and selecting all subcarriers according to the normalized gains of each user at different subcarriers: Traverse all subcarriers, and for the mth subcarrier, allocate it to the user with the largest gain based on the normalized gain of each user at the current subcarrier, until the allocation is completed for M subcarriers; Its expression is: Among them, φ idx represents the subcarrier code assigned to the idx user, that is, the code of the m-th subcarrier; idx∈{1,2,…,K} is the user number with the largest normalized gain at the m-th subcarrier; According to the allocation results of all subcarriers, the set of subcarrier codes allocated to K users is output as Φ = [φ1, φ2, …, φ K ].

10. The terahertz frequency band subcarrier allocation system according to any one of claims 6 to 9, characterized in that: The system also includes an evaluation module for evaluating the subcarrier allocation effect; wherein: Based on the subcarrier allocation results, the steering vector and channel of each user's receiving end are calculated. The average achievable rate after multi-user subcarrier allocation is compared with the average achievable rate of a single user in traditional hybrid precoding to evaluate the subcarrier allocation effect.

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