CN114615732A

CN114615732A - Downlink communication method under high-speed movement and related device

Info

Publication number: CN114615732A
Application number: CN202210080097.6A
Authority: CN
Inventors: 董辰; 李洁; 许晓东; 王碧舳; 韩书君
Original assignee: Beijing University of Posts and Telecommunications
Current assignee: Beijing University of Posts and Telecommunications
Priority date: 2022-01-24
Filing date: 2022-01-24
Publication date: 2022-06-10

Abstract

The application provides a downlink communication method and a related device under high-speed movement, which are applied to a base station in a rail communication network; the method comprises the following steps: a base station receives a request signal sent by a user; analyzing the request signal to obtain user information, and judging whether the user information of the user is stored in advance; in response to determining that the user information is pre-stored, invoking a pre-stored ZC sequence corresponding to the user information; in response to determining that the user information is not pre-stored, allocating the ZC sequence corresponding to the user information of the user to the user, and storing the user information of the user and the corresponding ZC sequence; grouping the users and performing downlink synchronization by taking the grouping as a basic unit; and carrying out downlink communication transmission with the user based on the downlink synchronization.

Description

Downlink communication method under high-speed movement and related device

Technical Field

The embodiment of the present application relates to the field of communications technologies, and in particular, to a downlink communication method and a related apparatus under high-speed movement.

Background

In the track network communication, as the train running speed is faster and faster, higher requirements are provided for the compatibility, the Doppler resistance and other performances of the track network communication, and how to realize that a user randomly accesses to the track communication network in a high-speed moving state and maintain better communication performance becomes a primary problem to be solved in the track communication technology.

In view of the above, a scheme for realizing efficient and stable communication with a user moving at a high speed, particularly downlink communication, is required.

Disclosure of Invention

In view of the above, an object of the present invention is to provide a downlink communication method under high speed movement and a related apparatus.

Based on the above object, the present application provides a downlink communication method under high-speed mobility, which is applied to a base station in a track communication network, and includes:

a base station receives a request signal sent by a user;

analyzing the request signal to obtain user information, and judging whether the user information of the user is stored in advance;

in response to determining that the user information is pre-stored, invoking a pre-stored ZC sequence corresponding to the user information;

in response to determining that the user information is not pre-stored, allocating the ZC sequence corresponding to the user information of the user to the user, and storing the user information of the user and the corresponding ZC sequence;

grouping the users and performing downlink synchronization by taking the grouping as a basic unit;

and carrying out downlink communication transmission with the user based on the downlink synchronization.

Further, the user information includes a user identification;

the analyzing the request signal to obtain user information, and judging whether the user information of the user is prestored comprises:

the base station analyzes the received request signal to obtain the user identification of the user sending the request signal;

searching the user identification of the user in the stored user information;

in response to that the user identifier of the user is not found in the stored user information, determining that the user information of the user is not stored in advance;

and responding to the user identification of the user found in the stored user information, and determining that the user information of the user is stored in advance.

Further, the user information comprises an access time;

the allocating the ZC sequence corresponding to the user information of the user to the user and storing the user information of the user and the corresponding ZC sequence includes:

analyzing the received request signal to obtain the access time of the user to the rail communication network;

allocating the ZC sequences for the users according to the sequence of the access time;

generating a plurality of leader sequences by utilizing the ZC sequence, distributing the plurality of leader sequences to a plurality of users in the same group, and distributing one leader sequence to each user;

and storing the obtained user identification, the access time, the distributed ZC sequence and the leader sequence.

Further, the allocating the ZC sequence to the user includes:

each ZC sequence is correspondingly allocated to four different users at most.

Further, the generating a plurality of preamble sequences by using the ZC sequence, allocating the plurality of preamble sequences to a plurality of users in the same group, and allocating one preamble sequence to each of the users includes:

taking the ZC sequence as a root sequence, and generating four leader sequences related to the root sequence at most by cyclic shift based on the root sequence;

each of the users having the same ZC sequence is assigned with a different preamble sequence.

Further, the grouping the users and storing the grouping includes:

in the users which do not store the user information in advance, the users with the same ZC sequence are grouped into the same group to obtain a newly increased group;

extracting an original grouping of the user from the user in which the user information is stored in advance;

and storing the original grouping and the newly added grouping together as the grouping of all the users at present.

Further, the performing downlink synchronization includes:

in the downlink, time synchronization and frequency synchronization are performed with the user.

Based on the same inventive concept, the present application further provides a downlink communication apparatus under high-speed movement, including:

a subscriber identity module configured to: a base station receives a request signal sent by a user; analyzing the request signal to obtain user information, and judging whether the user information of the user is stored in advance;

a ZC sequence configuration module configured to: in response to determining that the user information is pre-stored, invoking a pre-stored ZC sequence corresponding to the user information; in response to determining that the user information is not pre-stored, allocating the ZC sequence corresponding to the user information of the user to the user, and storing the user information of the user and the corresponding ZC sequence;

a downlink communication module configured to: grouping the users and performing downlink synchronization by taking the grouping as a basic unit; and carrying out downlink communication transmission with the user based on the downlink synchronization.

Based on the same inventive concept, the present application further provides an electronic device, which includes a memory, a processor, and a computer program stored in the memory and running on the processor, wherein the processor executes the computer program to implement the downlink communication method under high-speed movement as described in any one of the above.

Based on the same inventive concept, the present application also provides a non-transitory computer-readable storage medium storing computer instructions for causing the computer to perform the downlink communication method under high-speed movement as described above.

From the above, it can be seen that the downlink communication method and related apparatus under high-speed movement provided in the present application identify a user as a stored original user or a newly added user newly accessed to a network based on a received request signal, comprehensively consider different situations of the original user and the newly added user, and combine characteristics of ZC sequences to perform grouping of users, so that downlink synchronization with the users can be rapidly achieved by using the ZC sequences according to grouping of users, thereby implementing downlink communication with the users in a downlink.

Drawings

In order to more clearly illustrate the technical solutions in the present application or the related art, the drawings needed to be used in the description of the embodiments or the related art will be briefly introduced below, and it is obvious that the drawings in the following description are only embodiments of the present application, and it is obvious for those skilled in the art that other drawings can be obtained according to these drawings without creative efforts.

Fig. 1 is a flowchart of a downlink communication method under high-speed movement according to an embodiment of the present application;

fig. 2 is a block diagram of a downlink communication device under high-speed movement according to an embodiment of the present application;

FIG. 3 is a schematic diagram illustrating an exploded step according to an embodiment of the present application;

fig. 4 is a schematic structural diagram of an electronic device according to an embodiment of the present application.

Detailed Description

In order to make the objects, technical solutions and advantages of the present application more apparent, the present application is further described in detail below with reference to the accompanying drawings in combination with specific embodiments.

It should be noted that technical terms or scientific terms used in the embodiments of the present application should have a general meaning as understood by those having ordinary skill in the art to which the present application belongs, unless otherwise defined. The use of "first," "second," and similar terms in the embodiments of the present application do not denote any order, quantity, or importance, but rather the terms are used to distinguish one element from another. The word "comprising" or "comprises", and the like, means that the element or item listed before the word covers the element or item listed after the word and its equivalents, but does not exclude other elements or items. "upper", "lower", "left", "right", and the like are used merely to indicate relative positional relationships, and when the absolute position of the object being described is changed, the relative positional relationships may also be changed accordingly.

As described in the background section, the related downlink communication method under high-speed movement also has difficulty in meeting the requirements of the actual communication process.

In the process of implementing the present application, the applicant finds that the related downlink communication method under high-speed movement has the main problems that: since the user is in the train running at high speed, and does not break away from the signal radiation range of the current base station and continuously enters the signal radiation range of the next base station, the user needs to continuously access a new base station and continuously establish uplink synchronization and downlink synchronization with the new base station, and in the uplink and downlink synchronization process and the subsequent communication process, a large amount of channel resources are consumed for performing individual synchronization on each user, and the synchronization efficiency is low.

Further, the applicant has also found in the research that, taking ZC sequences as root sequences, multiple preamble sequences can be generated by cyclic shift, and thus ZC sequences can have auto-correlation and cross-correlation.

The applicant further finds that when users can be grouped according to the above characteristics of ZC sequences and users with the same ZC sequence are grouped into the same group, the efficiency of uplink synchronization and downlink synchronization can be effectively improved and the channel resource loss can be reduced in the synchronization process and the communication process.

It is to be appreciated that the method can be performed by any apparatus, device, platform, cluster of devices having computing and processing capabilities.

Hereinafter, the technical method of the present application will be described in detail by specific examples.

Referring to fig. 1, a downlink communication method under high-speed movement according to an embodiment of the present application includes the following steps:

step S101, a base station receives a request signal sent by a user; analyzing the request signal to obtain user information, and judging whether the user information of the user is stored in advance;

the downlink communication method under high-speed movement in the embodiment of the present application is applied to a base station in a track communication network, and specifically, may be, for example, a communication network of a railway track of a high-speed rail, a track communication network of a subway, and the like.

In this embodiment, the orbital communication network includes a plurality of base stations arranged along an orbit, user equipment communicating with the base stations, and a communication channel established between the user equipment and the base stations.

In the track communication network of the present embodiment, the user device may be simply referred to as a user, and a device used by a passenger in a train traveling at a high speed is used as the user device.

In this embodiment, the signal radiation of each base station has a certain range, and when a user enters the signal radiation range of any base station in the orbital communication network, the signal radiation range is defined as the time when the user accesses the orbital communication network, and the time when the user first enters the signal radiation range of any base station in the orbital communication network is taken as the access time of the user.

Further, the downlink communication in this embodiment is based on the base station, specifically, refers to a communication process in which the base station sends information to the user through a downlink, and in some other embodiments, the downlink communication of the base station may also be used as the uplink communication of the user based on the angle of the user.

In the present embodiment, taking a train traveling at a high speed on a railway track as a specific example, when a user in the train moves rapidly following the train, the user will continuously leave the signal radiation range of the current base station and enter the signal radiation range of the next base station.

In this embodiment, a method for establishing downlink communication of a base station will be described in detail by taking an arbitrary base station as an example.

First, as shown in fig. 3, the base station decomposes step S301, and the base station receives a user request signal.

Specifically, for any base station, a task request signal sent by a user within the signal radiation range of the base station can be received.

Further, the base station executes the decomposition step S302 in fig. 3 to determine whether or not it has been stored.

Specifically, the base station analyzes the received request signal to obtain the user identifier and the access time of the user.

Further, the base station searches the user identification of the user in the stored user information so as to identify the user.

Therefore, in this embodiment, after identifying the user by comparing and searching the user identifier, other contents of the user information belonging to the user may be determined.

If the user identification of the user can be found in the stored user information, the user is identified as a user which does not access the orbit communication network for the first time, and other related user information of the user can be confirmed to be stored in the base station in advance. If the user identification of the user is not found in the stored user information, the user is identified as a user accessing the orbit communication network for the first time, and other related user information of the user can be confirmed to be not stored in advance.

And step S102, in response to the fact that the user information is determined to be stored in advance, calling a pre-stored ancestor hedge sequence corresponding to the user information.

In the embodiment of the present application, as shown in fig. 3, based on the above-mentioned determination of whether the user information is stored in advance, when the determination result is yes, the decomposition step S303, the ZC sequence lookup is further performed.

Specifically, according to the user identifier searched by the comparison, determining the user information to which the user identifier belongs; and acquiring a ZC sequence which corresponds to the user information of the user and belongs to the user from the stored ZC sequence.

Step S103, responding to the fact that the user information is not stored in advance, distributing the ZC sequence corresponding to the user information of the user for the user, and storing the user information of the user and the corresponding ZC sequence.

In the embodiment of the present application, as shown in fig. 3, based on the above-described determination of whether the user information has been stored in advance, when the determination result is no, the decomposition step S304, allocating a ZC sequence and storing it, is further performed.

Specifically, in some embodiments, when a plurality of users each send their respective request signals to the base station, the base station obtains the access time of each user to the orbital communication network through the analysis of each request signal.

Further, each user is assigned a ZC sequence, and at the time of assignment, the assignment may be performed in the order of the access time of the user, for example, the users may be ranked in the order of the access time from the first to the last, and the ZC sequence assignment may be performed on the users one by one according to the ranking, so as to ensure that a plurality of users sharing the same ZC sequence, described below, are adjacent to each other in the access time.

Further, each user has the assigned ZC sequence as a root sequence, and the root sequence may generate a plurality of different preamble sequences through cyclic shift.

Wherein, each ZC sequence is used as a root sequence, and only 4 preamble sequences can be generated at most.

In this embodiment, when the same ZC sequence is allocated to a plurality of users, that is, when a plurality of users share the same ZC sequence, the same ZC sequence can be allocated to only 4 users at most.

Further, among a plurality of users sharing the same ZC sequence, the plurality of generated preamble sequences are allocated to the respective users one by one in the order of the access time, and therefore, the preamble sequences are different among the users having the same root sequence.

Further, for each user, the user identification and the access time of the user are stored as new user information, and the newly allocated ZC sequence and the leader sequence are stored.

Step S104, grouping the users and performing downlink synchronization by taking the grouping as a basic unit; and performing downlink communication transmission with the user based on the downlink synchronization.

In the embodiment of the present application, as shown in fig. 3, based on the ZC sequence determined by the decomposition step S303 and the ZC sequence allocated to the user in the decomposition step S304, the decomposition step S305 is further executed to establish downlink synchronization.

Specifically, firstly, it is necessary to group users and store the group after the group is completed.

In this embodiment, when there is no user newly accessing the orbital communication network among all users that have sent the request signal, it is considered that all users have established downlink synchronization and have completed grouping of users, and the original grouping of these users can be retrieved directly from the stored grouping, and downlink synchronization described below can be performed based on the original grouping.

In this embodiment, if all the users that have received requests include both the user who newly accessed the orbital communication network for the first time and has not been grouped and the user who has accessed the orbital communication network for the first time and has been grouped, only the user who newly accessed the orbital communication network for the first time may be grouped.

When users newly accessing the orbital communication network for the first time are grouped, the users with the same root sequence can be grouped into one group, so that each group of users has the same ZC sequence, each user in the group has different leader sequences generated by the ZC sequence, and the group is used as a new group.

Further, the original grouping and the newly added grouping stored by the base station are stored together as the grouping of all the users.

Further, in the downlink of the base station, according to the grouping of the users, time synchronization and frequency synchronization with the users are performed to establish downlink synchronization.

Specifically, the time deviation and the frequency deviation can be fed back by the signals in the exchange process through signal exchange, and the deviation can be adjusted.

Each group can be used as a basic unit, and all users in the same group are synchronized with the base station together, so that the channel resource loss in the synchronization process is reduced, and the synchronization efficiency is improved.

Further, based on the established downlink synchronization, the decomposition step S306 may be performed to modulate the signal and perform downlink communication.

Specifically, based on the autocorrelation and cross-correlation of ZC sequences, request signals of users in the same group may be modulated by ZC sequences to obtain request contents of each user, and downlink communication may be performed with each user in a downlink according to the request contents.

In the embodiment of the present application, when the train carrying the user moves away from the signal radiation range of the current base station and enters the signal radiation range of the next base station, the decomposition step shown in fig. 3 is performed again to establish downlink synchronization and perform downlink communication.

It can be seen that, in the downlink communication method under high-speed movement according to the embodiment of the present application, the user is identified as a stored original user or a newly added user newly accessed to a network based on the received request signal, different situations of the original user and the newly added user are comprehensively considered, and grouping of the users is performed in combination with characteristics of the ZC sequence, so that downlink synchronization with the users can be quickly achieved by using the ZC sequence according to grouping of the users, thereby implementing downlink communication with the users in a downlink.

It should be noted that the method of the embodiments of the present application may be executed by a single device, such as a computer or a server. The method of the embodiment can also be applied to a distributed scene and completed by the mutual cooperation of a plurality of devices. In such a distributed scenario, one of the devices may only perform one or more steps of the method of the embodiments of the present application, and the devices may interact with each other to complete the method.

It should be noted that the above describes some embodiments of the present application. Other embodiments are within the scope of the following claims. In some cases, the actions or steps recited in the claims may be performed in a different order than in the embodiments described above and still achieve desirable results. In addition, the processes depicted in the accompanying figures do not necessarily require the particular order shown, or sequential order, to achieve desirable results. In some embodiments, multitasking and parallel processing may also be possible or may be advantageous.

Based on the same inventive concept, corresponding to the method of any of the above embodiments, the embodiments of the present application further provide a downlink communication device under high-speed movement.

Referring to fig. 2, the downlink communication apparatus under high-speed movement includes: a subscriber identification module 201, a ZC sequence configuration module 202 and a downlink communication module 203.

The subscriber identification module 201 is configured to receive a request signal sent by a subscriber by a base station; analyzing the request signal to obtain user information, and judging whether the user information of the user is stored in advance.

A ZC sequence configuration module 202 configured to, in response to determining that the user information is pre-stored, retrieve a pre-stored ZC sequence corresponding to the user information; and responding to the fact that the user information is not stored in advance, allocating the ZC sequence corresponding to the user information of the user to the user, and storing the user information of the user and the corresponding ZC sequence.

A downlink communication module 203, configured to group the users and perform downlink synchronization on the group basis unit; and carrying out downlink communication transmission with the user based on the downlink synchronization.

As an optional embodiment, the subscriber identity module 201 is specifically configured to: the base station receives the user request signal, performs the disassembly step S301 as shown in fig. 3, and determines whether it has been stored, at the disassembly step S302.

Specifically, in the present embodiment, taking a train running on a railway track at a high speed as a specific example, when a user in the train moves rapidly following the train, the user will continuously leave the signal radiation range of the current base station and enter the signal radiation range of the next base station.

Specifically, any base station can receive a request signal from a user within its signal radiation range.

If the user identification of the user can be found in the stored user information, the user is identified as a user which does not access the orbit communication network for the first time, and other related user information of the user can be confirmed to be stored in the base station in advance.

If the user identification of the user is not found in the stored user information, the user is identified as a user accessing the orbit communication network for the first time, and other related user information of the user can be confirmed to be not stored in advance.

As an optional embodiment, the ZC sequence configuration module 202 is specifically configured to: the decomposition step S303, as shown in fig. 3, is performed to find ZC sequences, and S304, to allocate ZC sequences and store user information.

Specifically, in the embodiment of the present application, as shown in fig. 3, based on the above-mentioned determination of whether the user information is stored in advance, when the determination result is yes, the decomposition step S303, which is to search for the ZC sequence, is further performed.

Further, each user has the allocated ZC sequence as a root sequence, and the root sequence can generate a plurality of different preamble sequences through cyclic shift.

As an optional embodiment, the downlink communication module 203 is specifically configured to: the decomposition step S305 shown in fig. 3 is performed to establish downlink synchronization, and the decomposition step S306 is performed to modulate signals and perform downlink communication.

Specifically, in the embodiment of the present application, as shown in fig. 3, based on the ZC sequence of the user determined in the decomposition step S303 and the ZC sequence of the user allocated in the decomposition step S304, the decomposition step S305 is further performed to establish downlink synchronization.

Further, the original grouping and the new grouping stored by the base station are stored together as the grouping of the whole sequence.

For convenience of description, the above devices are described as being divided into various modules by functions, and are described separately. Of course, the functionality of the various modules may be implemented in the same one or more pieces of software and/or hardware in practicing embodiments of the present application.

The apparatus in the foregoing embodiment is used to implement the downlink communication method in any of the foregoing embodiments under high-speed movement, and has the beneficial effects of the corresponding method embodiment, which are not described herein again.

Based on the same inventive concept, corresponding to any of the above-mentioned embodiments, the embodiments of the present application further provide an electronic device, which includes a memory, a processor, and a computer program stored in the memory and executable on the processor, and when the processor executes the program, the processor implements the downlink communication method under high-speed movement according to any of the above-mentioned embodiments.

Fig. 4 is a schematic diagram illustrating a more specific hardware structure of an electronic device according to this embodiment, where the electronic device may include: a processor 1010, a memory 1020, an input/output interface 1030, a communication interface 1040, and a bus 1050. Wherein the processor 1010, memory 1020, input/output interface 1030, and communication interface 1040 are communicatively coupled to each other within the device via a bus 1050.

The processor 1010 may be implemented by a general-purpose CPU (Central Processing Unit), a microprocessor, an Application Specific Integrated Circuit (ASIC), or one or more Integrated circuits, and is configured to execute related programs to implement the technical solutions provided in the embodiments of the present Application.

The Memory 1020 may be implemented in the form of a ROM (Read Only Memory), a RAM (Random Access Memory), a static storage device, a dynamic storage device, or the like. The memory 1020 may store an operating system and other application programs, and when the technical solution provided by the embodiment of the present application is implemented by software or firmware, the relevant program codes are stored in the memory 1020 and called to be executed by the processor 1010.

The input/output interface 1030 is used for connecting an input/output module to input and output information. The input/output module may be configured as a component in a device (not shown) or may be external to the device to provide a corresponding function. The input devices may include a keyboard, a mouse, a touch screen, a microphone, various sensors, etc., and the output devices may include a display, a speaker, a vibrator, an indicator light, etc.

The communication interface 1040 is used for connecting a communication module (not shown in the drawings) to implement communication interaction between the present apparatus and other apparatuses. The communication module can realize communication in a wired mode (such as USB, network cable and the like) and also can realize communication in a wireless mode (such as mobile network, WIFI, Bluetooth and the like).

Bus 1050 includes a path that transfers information between various components of the device, such as processor 1010, memory 1020, input/output interface 1030, and communication interface 1040.

It should be noted that although the above-mentioned device only shows the processor 1010, the memory 1020, the input/output interface 1030, the communication interface 1040 and the bus 1050, in a specific implementation, the device may also include other components necessary for normal operation. Furthermore, it will be understood by those skilled in the art that the above-described apparatus may also include only those components necessary to implement the embodiments of the present application, and not necessarily all of the components shown in the figures.

Based on the same inventive concept, corresponding to any of the above-mentioned embodiment methods, the present application also provides a non-transitory computer-readable storage medium storing computer instructions for causing the computer to execute the downlink communication method under high-speed movement according to any of the above embodiments.

Computer-readable media of the present embodiments, including both non-transitory and non-transitory, removable and non-removable media, may implement information storage by any method or technology. The information may be computer readable instructions, data structures, modules of a program, or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), Static Random Access Memory (SRAM), Dynamic Random Access Memory (DRAM), other types of Random Access Memory (RAM), Read Only Memory (ROM), Electrically Erasable Programmable Read Only Memory (EEPROM), flash memory or other memory technology, compact disc read only memory (CD-ROM), Digital Versatile Discs (DVD) or other optical storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other non-transmission medium that can be used to store information that can be accessed by a computing device.

The computer instructions stored in the storage medium of the foregoing embodiment are used to enable the computer to execute the downlink communication method under high-speed movement as described in any of the foregoing embodiments, and have the beneficial effects of corresponding method embodiments, which are not described herein again.

Those of ordinary skill in the art will understand that: the discussion of any embodiment above is meant to be exemplary only, and is not intended to intimate that the scope of the disclosure, including the claims, is limited to these examples; within the context of the present application, features from the above embodiments or from different embodiments may also be combined, steps may be implemented in any order, and there are many other variations of the different aspects of the embodiments of the present application as described above, which are not provided in detail for the sake of brevity.

In addition, well-known power/ground connections to Integrated Circuit (IC) chips and other components may or may not be shown in the provided figures for simplicity of illustration and discussion, and so as not to obscure the embodiments of the application. Furthermore, devices may be shown in block diagram form in order to avoid obscuring embodiments of the application, and this also takes into account the fact that specifics with respect to implementation of such block diagram devices are highly dependent upon the platform within which the embodiments of the application are to be implemented (i.e., specifics should be well within purview of one skilled in the art). Where specific details (e.g., circuits) are set forth in order to describe example embodiments of the application, it should be apparent to one skilled in the art that embodiments of the application can be practiced without, or with variation of, these specific details. Accordingly, the description is to be regarded as illustrative instead of restrictive.

While the present application has been described in conjunction with specific embodiments thereof, many alternatives, modifications, and variations of these embodiments will be apparent to those of ordinary skill in the art in light of the foregoing description. For example, other memory architectures (e.g., dynamic ram (dram)) may use the embodiments discussed.

The embodiments of the present application are intended to embrace all such alternatives, modifications and variances that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, substitutions, improvements, and the like that may be made without departing from the spirit and principles of the embodiments of the present application are intended to be included within the scope of the present application.

Claims

1. A downlink communication method under high-speed movement is applied to a base station in an orbital communication network, and the method comprises the following steps:

a base station receives a request signal sent by a user;

2. The method of claim 1, wherein the user information comprises a user identification;

searching the user identification of the user in the stored user information;

3. The method of claim 2, wherein the user information comprises an access time;

4. The method of claim 3, wherein the allocating the ZC sequence for the user comprises:

each ZC sequence is correspondingly allocated to four different users at most.

5. The method as claimed in claim 1, wherein the generating a plurality of preamble sequences by using the ZC sequence, allocating the plurality of preamble sequences to a plurality of users in a same group, and allocating one preamble sequence to each of the users comprises:

6. The method of claim 1, wherein the grouping the users and storing the grouping comprises:

7. The method of claim 1, wherein the performing downlink synchronization comprises:

8. A downlink communication apparatus under high-speed movement, comprising:

a subscriber identification module configured to: a base station receives a request signal sent by a user; analyzing the request signal to obtain user information, and judging whether the user information of the user is stored in advance;

9. An electronic device comprising a memory, a processor and a computer program stored on the memory and executable by the processor, characterized in that the processor implements the method according to any of claims 1 to 7 when executing the computer program.

10. A non-transitory computer-readable storage medium storing computer instructions for causing a computer to perform the method according to any one of claims 1 to 7.