CN116886148A - Beam searching method, terminal and base station - Google Patents

Abstract

The application discloses a beam searching method, a terminal and a base station. The beam searching method applied to the terminal comprises the following steps: receiving beam heat information of a plurality of coarse beams sent by a base station; determining a high-heat coarse beam according to the beam heat information; the most spectrally efficient first beamlets are determined within the high heat coarse beam. The beam searching method applied to the base station comprises the following steps: counting beam heat information of a plurality of coarse beams in the covered cell, and determining high-heat coarse beams in the plurality of coarse beams according to the beam heat information; transmitting a synchronous signal block to a terminal through a high-heat coarse beam; when the terminal searches the first thin beam in the high-heat coarse beam, determining the high-heat coarse beam as the optimal coarse beam with the lowest searching time delay when the actual access time of the terminal accessing the physical random access channel is the same as the target access time preset in the synchronous signal block. The application solves the technical problem that the related beam searching technology is difficult to meet the low-delay requirement in a large-scale MIMO scene.

Description

Beam searching method, terminal and base station

Technical Field

The present application relates to the field of communications, and in particular, to a beam searching method, a terminal, and a base station.

Background

With the popularity of fourth Generation mobile communication (Fourth Generation, 4G) networks and terminals, there is a higher desire and demand for capacity and transmission rate of Fifth Generation mobile communication (5G) systems. In the current situation, the frequency spectrum with the frequency lower than 10GHz is very crowded, so millimeter wave high-frequency communication with the characteristics of high bandwidth, directional narrow beam, good security and the like is widely focused in the industry.

Because the millimeter wave band has higher loss, in the B5G (Beyond 5G, the latter 5 generation mobile communication) and 6G (sixth generation mobile communication) scenes, the communication system needs to rely on deploying a very large-scale MIMO (Multiple-Inputand Multiple-Output) antenna array to obtain enough beam forming gain to resist the path loss caused by the high frequency band. After the ultra-large-scale antenna array is deployed, the base station and the terminal use narrow beams to communicate, and the more the number of antennas is, the narrower the beam width is, which means that the base station and the terminal need to find the best or better beam pair to communicate when communicating, so that the spectrum efficiency is higher (visual perception is that the uplink and downlink rates are higher).

However, the operating frequency band of the communication system may be increased to above 52.6GHz in the B5G period, and the number of antennas deployed at the base station side will be increased more and more, and even reach more than a thousand antennas. In this scenario, since the beam for communication between the base station and the terminal will be thinner (the directional degree of communication is higher) and the time for determining the optimal communication thin beam is longer, if the existing beam searching scheme is used when deploying large-scale and ultra-large-scale MIMO, the searching complexity/time delay is relatively higher, and the requirement of low time delay of the actual system in the large-scale MIMO scenario cannot be met.

In view of the above problems, no effective solution has been proposed at present.

Disclosure of Invention

The embodiment of the application provides a beam searching method, a terminal and a base station, which at least solve the technical problem that the related beam searching technology is difficult to meet the low-delay requirement in a large-scale MIMO scene.

According to an aspect of an embodiment of the present application, there is provided a beam searching method, applied to a terminal, including: receiving beam heat information of a plurality of coarse beams sent by a base station, wherein the beam heat information of each coarse beam is used for reflecting the number of terminals under the coverage area of the coarse beam; determining a high-heat coarse beam in the plurality of coarse beams according to the beam heat information, wherein the number of terminals under the coverage area of the high-heat coarse beam is not less than a preset threshold value; the most spectrally efficient first beamlets are determined within the high heat coarse beam.

Optionally, receiving beam heat information of a plurality of coarse beams sent by the base station, including: and receiving the beam heat information of a plurality of coarse beams sent by the base station according to a receiving strategy corresponding to the information type of the beam heat information, wherein the information type comprises the following steps: detailed heat information or reduced heat information.

Optionally, receiving the first beam heat information of the plurality of coarse beams sent by the base station according to a receiving policy corresponding to an information type of the beam heat information, including: when the information type of the beam heat information is detailed heat information, acquiring the detailed heat information of each coarse beam according to the target position of a synchronous signal block sent by a base station through the coarse beam on a time-frequency domain; when the information type of the beam heat information is reduced heat information, the reduced heat information of each coarse beam is obtained through a synchronous signal block sent by a receiving base station through the coarse beam, wherein the synchronous signal block at least comprises: the reduced heat information for the coarse beam.

Optionally, determining a high heat coarse beam of the plurality of coarse beams according to the beam heat information includes: when the information type of the beam heat information is detailed heat information, determining a high heat coarse beam in a plurality of coarse beams according to first information content in the detailed heat information, wherein the first information content at least comprises: the beam serial numbers of the various coarse beams and the beam heat degree of each coarse beam in a cell covered by the base station are ordered; when the information type of the beam heat information is reduced heat information, determining a high heat coarse beam in a plurality of coarse beams according to second information content in the reduced heat information, wherein the second information content at least comprises: a radio signal indicating whether each coarse beam is a high heat beam.

Optionally, determining a high heat coarse beam of the plurality of coarse beams according to the first information content within the detailed heat information includes: determining whether beam heat ordering of each coarse beam is positioned at the first M bits of K coarse beams in a cell covered by a base station based on first information content, wherein M is more than or equal to 1 and less than or equal to K; when the beam hotness of the coarse beam is ordered in the first M bits in the cell, determining that the coarse beam is a high-hotness coarse beam; when the beam hotness ordering of the coarse beam is not in the first M bits within the cell, it is determined that the coarse beam is not a hotness beam.

Optionally, determining a high heat coarse beam of the plurality of coarse beams according to the second information content within the reduced heat information includes: determining the coarse beam as a high heat beam when the radio signal is 1; when the radio signal is 0, it is determined that the coarse beam is not a high heat beam.

Optionally, after determining the first thin beam with the highest spectral efficiency in the high-heat coarse beam, the method further includes: when the base station determines that the high-heat coarse beam is the optimal coarse beam with the lowest searching time delay according to the first fine beam, the first fine beam and the second fine beam which is in the high-heat coarse beam and has the same propagation direction as the first fine beam are used as the optimal fine beam with the lowest searching time delay.

According to another aspect of the embodiment of the present application, there is also provided a beam searching method, applied to a base station, including: counting beam heat information of a plurality of coarse beams in a covered cell, and determining high-heat coarse beams in the plurality of coarse beams according to the beam heat information, wherein the beam heat information of each coarse beam is used for reflecting the number of terminals in the coverage area of the coarse beam, and the number of the terminals under the coverage area of the high-heat coarse beam is not less than a preset threshold; transmitting a synchronization signal block to the terminal through the high-heat coarse beam, wherein the synchronization signal block at least comprises: indicating a target access time of the terminal to access the physical random access channel; when the terminal obtains a first thin beam with the lowest search time delay in the high-heat coarse beam, judging whether the actual access time of the terminal accessing the physical random access channel is the same as the target access time, and determining the high-heat coarse beam as the optimal coarse beam with the lowest search time delay when the actual access time is the same as the target access time.

According to another aspect of the embodiment of the present application, there is also provided a terminal including: receiving beam heat information of a plurality of coarse beams sent by a base station, wherein the beam heat information of each coarse beam is used for reflecting the number of terminals under the coverage area of the coarse beam; determining a high-heat coarse beam in the plurality of coarse beams according to the beam heat information, wherein the number of terminals under the coverage area of the high-heat coarse beam is not less than a preset threshold value; the most spectrally efficient first beamlets are determined within the high heat coarse beam.

According to another aspect of the embodiment of the present application, there is also provided a base station, including: counting beam heat information of a plurality of coarse beams in a covered cell, and determining high-heat coarse beams in the plurality of coarse beams according to the beam heat information, wherein the beam heat information of each coarse beam is used for reflecting the number of terminals in the coverage area of the coarse beam, and the number of the terminals under the coverage area of the high-heat coarse beam is not less than a preset threshold; transmitting a synchronization signal block to the terminal through the high-heat coarse beam, wherein the synchronization signal block at least comprises: indicating a target access time of the terminal to access the physical random access channel; when the terminal obtains a first thin beam with the lowest search time delay in the high-heat coarse beam, judging whether the actual access time of the terminal accessing the physical random access channel is the same as the target access time, and determining the high-heat coarse beam as the optimal coarse beam with the lowest search time delay when the actual access time is the same as the target access time.

In the embodiment of the application, the beam heat information of a plurality of coarse beams sent by a base station is received, wherein the beam heat information of each coarse beam is used for reflecting the number of terminals under the coverage area of the coarse beam; determining a high-heat coarse beam in the plurality of coarse beams according to the beam heat information, wherein the number of terminals under the coverage area of the high-heat coarse beam is not less than a preset threshold value; the most spectrally efficient first beamlets are determined within the high heat coarse beam. Therefore, the optimal fine beam is searched in the high-heat coarse beams in the plurality of coarse beams at the base station side, the beam searching complexity and searching time are reduced, and the technical problem that the related beam searching technology is difficult to meet the low-time delay requirement in a large-scale MIMO scene is solved.

Drawings

The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description serve to explain the application and do not constitute a limitation on the application. In the drawings:

FIG. 1 is a flow chart of an alternative beam search method according to an embodiment of the present application;

FIG. 2 is a schematic diagram of coarse and fine beams in an alternative DFT codebook according to an embodiment of the present application;

FIGS. 3a and 3b are diagrams of spectral efficiency of searching for an optimal communication beam in an alternative non-line-of-sight communication scenario, respectively, according to embodiments of the present application;

FIG. 4 is a flow chart of another alternative beam search method according to an embodiment of the present application;

FIG. 5 is a schematic diagram of an alternative transceiver of an embodiment of the present application;

fig. 6 is a flow chart of an alternative communication between a base station and a terminal in accordance with an embodiment of the present application;

FIG. 7 is a comparison chart of simulation results under a multi-terminal non-uniform distribution scenario provided by an embodiment of the present application;

fig. 8 is a schematic structural view of an alternative beam searching apparatus according to an embodiment of the present application

Fig. 9 is a schematic structural view of another alternative beam searching apparatus according to an embodiment of the present application.

Detailed Description

In order that those skilled in the art will better understand the present application, a technical solution in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in which it is apparent that the described embodiments are only some embodiments of the present application, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present application without making any inventive effort, shall fall within the scope of the present application.

It should be noted that the terms "first," "second," and the like in the description and the claims of the present application and the above figures are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged where appropriate such that the embodiments of the application described herein may be implemented in sequences other than those illustrated or otherwise described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.

In addition, the related information (including but not limited to user equipment information, user personal information, etc.) and data (including but not limited to data for presentation, analyzed data, etc.) related to the present application are information and data authorized by the user or sufficiently authorized by each party. For example, an interface is provided between the system and the relevant user or institution, before acquiring the relevant information, the system needs to send an acquisition request to the user or institution through the interface, and acquire the relevant information after receiving the consent information fed back by the user or institution.

Example 1

Currently, massive Multiple-Input Multiple-Output (Massive MIMO) is gradually becoming a fundamental means for improving the communication rate of the 5G system, however, due to the limitation of the hardware structure and the antenna field mode characteristics, the following two problems still need to be solved before the practical application of the technology:

the first problem is the limitation of the hardware structure. The current process of a Radio Frequency (RF) unit is complex. Conventional pure digital domain beamforming, with a separate RF link for each antenna, has the advantage of providing sufficient degrees of freedom to improve the performance of the communication system. However, with the rapid increase in the number of antennas, the analog-to-digital conversion of large-scale signals causes a large amount of energy consumption (particularly for high-frequency devices), and the complexity of digital signal processing increases with the increase in RF links. The traditional pure analog domain beam forming is opposite, and all antenna units are connected to the same RF link through phase shifters respectively, so that the device has the advantages of simple structure and easy realization, and reduces the energy consumption of the device. However, since there is only one RF link, the degree of freedom of communication is greatly reduced, resulting in a decrease in system performance. Combining the advantages of both structures, a digital-to-analog hybrid transmitter/receiver architecture is a focus of academic and industrial attention. The large-scale RF antenna units are connected to a small number of RF links by means of full connections (each RF link is connected to all antenna units) or partial connections (a fixed sub-array structure, each RF link is connected to only a portion of the antenna units), the whole signal path within the transceiver can be divided into two parts: an RF link section (analog front end of large-scale antenna) and a digital processing section (digital back end of small number of RF units). The combination of the analog and the digital ensures that the system only needs a small number of digital-analog conversion units, thereby greatly reducing the conversion energy consumption and the processing complexity of the digital domain. Most millimeter wave massive antenna communication system solutions have focused on hybrid beamforming structures based on full connectivity. In terms of hardware implementation complexity, a large-scale antenna system of a full-connection mode is not realistic in a millimeter wave frequency band, and the structural change makes an algorithm applicable to the full-connection architecture not applicable to a part of the connection subarray architecture any more, so that a new solution is required.

The second problem is the limitation of the radiation pattern characteristics of the antenna. When the millimeter wave frequency band deploys massive MIMO, the antenna radiation mode of the base station is similar to the shape of a wave beam, and the orientation degree of communication between the base station and the terminal is increased. In this scenario, since the beam for communication between the base station and the terminal will be thinner (the directional degree of communication is higher), the time for determining the optimal communication beamlets is longer, and the normal communication of the terminal will be affected in a non-negligible way. Therefore, when the scheme is used in the process of deploying large-scale and ultra-large-scale MIMO, the searching complexity/time delay is relatively high, the requirement of low time delay of an actual system in a large-scale MIMO scene cannot be met, and a new solution is required to be found.

In summary, in a massive/ultra-massive MIMO scenario, the hybrid beamforming system architecture has become an alternative to increasing the system communication rate. Digital beamforming is based on the beam determined by analog beamforming, so that the analog beamforming technique is critical in the hybrid beamforming technique. In addition, since the digital beam forming technology is relatively perfect, after the analog beam forming technology is applied, more digital beam forming schemes can be selected, and designing an analog beam searching scheme which is based on partial connection subarrays and has lower complexity is one of important problems to be solved in future communication.

In order to solve the above technical problems, the embodiments of the present application provide a beam searching method, the execution subject of which is a terminal, and it should be noted that the steps illustrated in the flowchart of the drawings may be performed in a computer system such as a set of computer executable instructions, and although a logic order is illustrated in the flowchart, in some cases, the steps illustrated or described may be performed in an order different from that herein.

Fig. 1 is a flow chart of an alternative beam searching method according to an embodiment of the present application, as shown in fig. 1, the method at least includes steps S102-S106, in which:

step S102, receiving beam heat information of a plurality of coarse beams sent by a base station.

In the technical solution provided in step S102, a communication connection is established between a base station and a terminal, and the terminal may receive beam heat information of a plurality of coarse beams on the base station side sent by the base station. In the embodiment of the application, the concept of beam heat is introduced, and the beam heat information is used for reflecting the number of terminals under the coverage area of the coarse beam.

In addition, the concept of coarse beam and fine beam is introduced in the embodiment of the present application. Here, the concept of coarse and fine beams will be described by taking the base station side as an example. Since the accuracy of the beam used by the base station in communication is related to the number of antennas used by the base station, the base station can adjust the number of antennas used (turn on or off the antennas) to achieve the purpose of adjusting the accuracy of the communication beam (thickness of the beam). Thus, the greater the number of antennas used by a base station, the greater the accuracy of the beams it can communicate with, and the finer the individual beams and vice versa. The terminal side is the same. The coarse and fine beams may be determined by comparing correlations of codewords in the coarse and fine beam codebooks. From the viewpoint of signal coverage, a coarse beam includes a plurality of beamlets, and as shown in fig. 2, it is not difficult to see that the coarse beam includes 4 beamlets.

Step S104, determining a high-heat coarse beam in the plurality of coarse beams according to the beam heat information.

In the technical solution provided in step S104, since the beam heat information may reflect the number of terminals under the coverage area of each coarse beam, the coarse beams may be classified into two categories according to the above-defined concept of beam heat: and the high-heat coarse beam and the low-heat coarse beam are defined according to the size relation between the number of terminals under the coverage range of the coarse beam and a preset threshold value.

Taking the spectrum efficiency diagram after searching the best communication beams of the base station beam and all terminals in the coverage area as an example in the non-line-of-sight communication scene of the base station and the terminals shown in fig. 3a and 3b, when the number of terminals in a certain beam coverage area is greater than or equal to X (i.e. a preset threshold), it is indicated that the higher the beam heat, the higher the heat corresponding to the base station beam in the shallow coverage color in fig. 3a and 3b is; if the number of terminals in a certain beam coverage area is lower than X, it means that the lower the beam heat is, the lower the heat corresponding to the base station beam in fig. 3a and 3b where the coverage color is darker is the low heat beam. It should be noted that, here, X may be set according to the actual situations of different scenes in different regions.

Step S106, determining the first thin beam with highest spectrum efficiency in the high-heat coarse beam.

In the technical scheme provided in step S106, the terminal determines the high-heat coarse beam according to the beam heat information sent by the base station, so that the beam search is not required to be performed on the whole beam of the base station, and only the beam search is required to be performed in the coverage area of the high-heat coarse beam. Therefore, the scheme adopted by the embodiment of the application can reduce the beam searching time and the searching complexity and realize the rapid beam searching.

Based on the schemes defined in the above steps S102 to S106, it may be known that, in an embodiment, the beam heat information of a plurality of coarse beams sent by the base station is received, where the beam heat information of each coarse beam is used to reflect the number of terminals under the coverage area of the coarse beam; determining a high-heat coarse beam in the plurality of coarse beams according to the beam heat information, wherein the number of terminals under the coverage area of the high-heat coarse beam is not less than a preset threshold value; the most spectrally efficient first beamlets are determined within the high heat coarse beam.

Therefore, through the technical scheme of the embodiment of the application, the purpose of quickly searching the beam is achieved, and the technical effects of reducing the beam searching time and the searching complexity are realized, so that the technical problem that the related beam searching technology is difficult to meet the low-delay requirement in a large-scale MIMO scene is solved.

The above-described method of this embodiment is further described below.

As an optional implementation manner, in the technical solution provided in step S102, the method may include: and receiving the beam heat information of the plurality of coarse beams sent by the base station according to a receiving strategy corresponding to the information type of the beam heat information.

The information type includes: detailed heat information or reduced heat information.

In this embodiment, the beam heat information can be classified into two categories according to the details of the beam heat information: detailed heat information or reduced heat information. Because the beam information carried in each type of beam heat information is different, the receiving strategy of the terminal for receiving each type of beam heat information from the base station is also different.

Alternatively, beam heat information of the coarse beam may be received according to the following rules, respectively, including: when the information type of the beam heat information is detailed heat information, acquiring the detailed heat information of each coarse beam according to the target position of a synchronous signal block sent by a base station through the coarse beam on a time-frequency domain; when the information type of the beam heat information is reduced heat information, the reduced heat information of each coarse beam is obtained through a synchronous signal block sent by a receiving base station through the coarse beam, wherein the synchronous signal block at least comprises: the reduced heat information for the coarse beam.

Specifically, for the reduced heat information, the beam information included in the reduced heat information is less, and the information can be stored directly by the existence of one space bit in the synchronizing signal block, so that the base station can directly transmit the reduced heat information to the terminal through the synchronizing signal block, and the terminal can directly correspond to the beam heat information of the transmitted coarse beam through the synchronizing signal block; for the detailed heat information, more beam information is included, and cannot be stored by the synchronization signal block, so that the terminal can periodically obtain the detailed beam heat information of the coarse beam according to the position (i.e. the corresponding frequency band) of the synchronization signal block sent by the base station through the coarse beam on the time-frequency domain, and it can be understood that the terminal can periodically obtain the detailed beam heat information in the fixed frequency band.

As an optional implementation manner, in the technical solution provided in step S104, since contents included in the beam heat information are different, determining the beam with high heat may be divided into two types according to the information type of the beam heat information, including:

when the information type of the beam heat information is detailed heat information, determining a high heat coarse beam in a plurality of coarse beams according to first information content in the detailed heat information, wherein the first information content at least comprises: the beam serial numbers of the various coarse beams and the beam heat degree of each coarse beam in a cell covered by the base station are ordered;

When the information type of the beam heat information is reduced heat information, determining a high heat coarse beam in a plurality of coarse beams according to second information content in the reduced heat information, wherein the second information content at least comprises: a radio signal indicating whether each coarse beam is a high heat beam.

Specifically, when the information type of the beam heat information is detailed heat information, since the first information content includes the beam serial numbers of the coarse beams and the beam heat of each coarse beam in the coverage cell of the base station, the terminal may determine the high heat coarse beam in the plurality of coarse beams according to the following method: determining whether beam heat ordering of each coarse beam is positioned at the first M bits of K coarse beams in a cell covered by a base station based on first information content, wherein M is more than or equal to 1 and less than or equal to K; when the beam hotness of the coarse beam is ordered in the first M bits in the cell, determining that the coarse beam is a high-hotness coarse beam; when the beam hotness ordering of the coarse beam is not in the first M bits within the cell, it is determined that the coarse beam is not a hotness beam.

Wherein, the M, K is a positive integer greater than or equal to 1.

That is, the method orders the beam heat information of each coarse beam under the coverage of the base station, and uses the M bits ranked at the top as the coarse beam with high heat, and uses the rest coarse beams as coarse beams with low heat. For example, the base station side has 8 coarse beams, the number of terminals under the coverage area of each beam can be ranked, the coarse beam with the top 3 rank is regarded as a high-heat coarse beam, and the remaining 5 coarse beams are regarded as low-heat coarse beams.

Specifically, when the information type of the beam heat information is reduced heat information, since the second information content includes only a radio signal indicating whether the coarse beam is a high heat beam, the terminal may determine a high heat coarse beam among a plurality of coarse beams as follows: determining the coarse beam as a high heat beam when the radio signal is 1; when the radio signal is 0, it is determined that the coarse beam is not a high heat beam.

As an alternative embodiment, after determining the first beamlets that are most spectrally efficient within the high heat coarse beam, the method further comprises: when the base station determines that the high-heat coarse beam is the optimal coarse beam with the lowest searching time delay according to the first fine beam, the first fine beam and the second fine beam which is in the high-heat coarse beam and has the same propagation direction as the first fine beam are used as the optimal fine beam with the lowest searching time delay.

In this embodiment, after the terminal determines the first thin beam with highest spectral efficiency in the high-heat coarse beam, the actual access time of the random physical channel in the first thin beam is fed back to the base station, and the base station can match the actual access time with the predefined target access time in the synchronization signal block, if the actual access time is the same, the high-heat coarse beam is the optimal coarse beam with the lowest search delay at the base station side, and then the terminal further selects the second thin beam with the same or similar propagation direction as the first thin beam as the optimal thin beam in the optimal high-heat coarse beam. In general, the beam directions of two beams adjacent to the first beamlets are closest, and therefore, the first beamlets and the two beamlets on the left and right sides of the first beamlets are taken as the optimal beamlets for directional reception.

Alternatively, the terminal may also directly select a plurality of beamlets with higher spectral efficiency from the high-heat coarse beam, and use the beamlets as the optimal beamlets of the terminal, so that the terminal may communicate with the base station by using the plurality of optimal beamlets to receive the pilot signal.

Based on any one of the foregoing embodiments, an embodiment of the present application further provides a beam searching method, where an execution body is a base station. Fig. 4 is a flow chart of an alternative beam searching method according to an embodiment of the present application, as shown in fig. 4, the method at least includes steps S402-S406, wherein:

step S402, counting beam heat information of a plurality of coarse beams in the covered cell, and determining high heat coarse beams in the plurality of coarse beams according to the beam heat information.

In the technical solution provided in step S402, the base station counts beam heat information of a plurality of coarse beams in the cell covered by the base station. In the embodiment of the application, the concept of beam heat is introduced, wherein the beam heat information is used for reflecting the number of terminals in the coverage area of the coarse beam, so that the high-heat coarse beam can be determined according to the size relation between the number of terminals in the coverage area of each coarse beam and a preset threshold.

Since the beam heat information may reflect the number of terminals under each coarse beam coverage, in the embodiment of the present application, coarse beams may be classified into two types according to the concept of beam heat defined above: and the high-heat coarse beam and the low-heat coarse beam are respectively defined according to the size relation between the number of terminals under the coverage range of the coarse beam and a preset threshold value.

Optionally, when the number of terminals in a coverage area of a certain beam is greater than or equal to X (i.e., a preset threshold), it is indicated that the higher the beam heat is, the corresponding base station beam is a high heat coarse beam; if the number of terminals in a certain beam coverage area is lower than X, the lower the beam heat is, the corresponding base station beam is a low heat beam.

And step S404, transmitting the synchronous signal block to the terminal through the high-heat coarse beam.

In the technical solution provided in step S404, the base station sends the synchronization signal block to the terminal through the high-heat coarse beam to perform clock synchronization and channel estimation, so as to ensure that the terminal can correctly decode and process the signal received from the base station, and therefore, the synchronization signal block at least includes: and indicating the target access time of the terminal to access the physical random access channel.

Step S406, when the terminal obtains the first thin beam with the lowest searching time delay in the high-heat coarse beam, judging whether the actual access time of the terminal accessing the physical random access channel is the same as the target access time, and determining that the high-heat coarse beam is the optimal coarse beam with the lowest searching time delay when the actual access time is the same as the target access time.

In the technical solution provided in step S406, when the terminal obtains the first thin beam with the lowest search delay in the high-heat coarse beam, according to whether the actual access time of the terminal to the physical random access channel is the same as the target access time, if so, the clocks of the base station and the terminal are synchronous, and at this time, the high-heat beam can be determined to be the optimal coarse beam with the lowest search delay at the base station side.

According to the embodiment of the application, the optimal fine beam search at the terminal side can be realized only in the high-heat coarse beam, the beam search complexity and time are greatly reduced, and the problem that normal communication cannot be performed due to low system spectrum efficiency when the terminal in the high-heat beam coverage area is paired with the low-heat base station beam can be effectively avoided, so that the communication uncertainty between the base station and the terminal is effectively improved.

That is, after the terminal determines the optimal beamlets, the optimal beamlets are reported to the base station, and after the base station receives the optimal beamlets of the terminal, the beam search of the RF link is completed. To this end, the beamlets used by the first RF link of the base station and the terminal have been determined, i.e. the RF (analog) precoding matrix F has been determined _RF Combiner W with RF (analog) _RF The codeword used by the first subarray (first RF link).

Then, the base station and the terminal respectively open a second RF link, and determine an RF (analog) precoding matrix F according to the above method _RF Combiner W with RF (analog) _RF A codeword used by a second sub-array (second RF link).

And so on until the base station and the terminal determine the RF (analog) precoding matrix F _RF Combiner W with RF (analog) _RF Codewords for all subarrays of (F) _RF And W is equal to _RF And after the determination is finished, all beam searching is finished.

The method of any of the above embodiments is further described below with a specific example:

fig. 5 is a schematic structural diagram of an alternative transceiver according to an embodiment of the present application, and as shown in fig. 5, the embodiment of the present application may be applied to an analog-digital hybrid processing downlink single-cell system in which both transceivers use a partial connection structure. The partial connection structure means that each radio frequency link is connected with a partial radio frequency antenna unit in the analog beam forming part, that is, each radio frequency link is not connected with only one antenna, but one radio frequency link can be connected with a plurality of antennas.

Specifically, the base station at the transmitting end mainly comprises a digital pre-coding part at the rear end of the radio frequency link and an analog pre-coding part at the front end of the radio frequency link, so that multi-stream communication can be performed; the receiving end user is mainly composed of an analog merging part at the front end of the radio frequency link and a digital merging part at the rear end of the radio frequency link, and can carry out single-stream communication. Wherein, N deployed at the base station side of the transmitting end _BS The base station antennas are connected to K radio frequency links (i.e. every N) by means of fixed subarrays (i.e. each antenna is connected to a phase shifter) _MASK The root antenna serves one user and is connected to one radio frequency link), the receiving end deploys K users, and each user is provided with N _MS The antennas are also connected to a radio frequency link by means of fixed sub-arrays (one phase shifter for each antenna). Therefore, in the transceiver structure, the number of radio frequency links at the base station side is equal to the number of users, and K is equal to the number of users, i.e. one radio frequency link serves one user.

On the receiving end user side, the kth user receives the signal model sent by the sending end base stationCan be expressed as:

where ρ represents the average transmit power,a transmission vector representing the kth user, < +.>Digital precoding matrix representing the kth user of the transmitting end, >Representing the analog precoding matrix of the transmitting end,complex-valued channel matrix representing kth user, for example>Analog merge matrix representing kth user, < ->A digital combining matrix representing the kth user, n _k Additive white gaussian noise representing the kth user subject to a mean of 0 and a variance of sigma ² Complex gaussian distribution, sigma ² Representing the noise power. Removing F _RF The other matrices are all related dimensions by taking the kth user as an illustration, and then the dimensions, the relation between the whole transceiving matrix and the kth user transceiving matrix are illustrated again for each matrix from the perspective of the whole communication system.

From the overall point of view of the transmitting end base station of the communication system,representing the base station transmit signal, which can be written as a concatenation of K user transmit signal data streams, i.e. s= [ s ] ₁ ^T ,…,s _K ^T ] ^T And the transmission power is required to satisfy the following relationshipRepresenting the digital precoding matrix used by the base station, which can be written as a concatenation of K user digital precoding matrices, i.e. F _BB ＝[F _BB,1 ,…,F _BB,K ]. In addition, F can also be _RF Denoted as->It should be noted that K refers to the number of radio frequency links at the base station side of the transmitting end instead of the number of users, and->The precoding vector used by the kth radio frequency link of the transmitting end is shown and is irrelevant to the kth user. From the following components In the power limitation, each element in the precoding vector of the kth radio frequency link of the transmitting base station needs to satisfy + ->

From the overall point of view of the receiving end user of the communication system,representing the received signal for the entirety of K users.Complex-valued channel matrix representing the entirety of K users, which can be represented as h= [ H ] by the channels of each of the K users ₁ ^T ,…,H _K ^T ] ^T 。/>A simulation merge matrix representing the entirety of the K users, which may be represented as +.>In addition, due to power limitation, W _RF,k Each element of (3) is required to satisfy +.>A digital combining matrix representing the entirety of the K users, which can be represented as +.>

The hybrid beam shaper consists of the digital precoding matrix F of the baseband _BB Digital combining matrix W _BB And an analog precoding matrix F at the radio frequency end _RF Analog combining matrix W _RF The composition is formed. The design of the hybrid beamformer generally adopts the idea of "two steps", i.e. the originating analog precoding matrix F is first designed according to the actual channel H _RF And receiving end simulation merging matrix W _RF However, it isThen according to the equivalent baseband channelDesign of originating digital precoding matrix F _BB And receiving end digital merging matrix W _BB . In the above communication system, the equivalent baseband channel of the kth user +. >

Analog precoding matrix F _RF Merging matrix W with simulation _RF Is typically implemented using a codebook-based beam search method. The simplest method is that the analog precoder and the combiner respectively traverse a predetermined set of beamforming codebooks, and select the best beamforming vector combination and the best combining vector combination that can maximize spectral efficiency to respectively construct an analog precoding matrix and an analog combining matrix. The beam forming codebook adopted by the embodiment of the application is a discrete Fourier transform (Discrete Fourier Transform, DFT) codebook, and the weighting coefficient Q of the nth antenna in the mth code word in the codebook _m,n Given by the formula:

wherein M represents the number of codewords, N represents the number of antennas connected by each radio frequency link, and the codebook set is a set containing all codewords of the codebook. Codebook sharing N at base station side _MASK The code words are N in the codebook of the user side _MS And code words.

Under the system architecture described above, the overall performance of the communication system may be represented by the rate R. The index is the sum of the frequency spectrum efficiency of K users so as to effectively reflect the communication rate of the whole communication system, and the specific calculation formula is as follows:

the numerator in the above formula is the power of the kth user useful signal, and the denominator is the sum of the powers of other user interference and additive white gaussian noise.

Due to the digital precoding matrix F _BB Merging matrix W with numbers _BB The method can be realized by adopting the baseband BD technology which is mature at present, so that the difficulty of beam searching is how to determine the analog beam forming matrix (namely the analog precoding and analog combining matrix), and the analog beam forming matrix can be rapidly determined by the technical scheme of the embodiment of the application.

Fig. 6 is a communication flow chart of an alternative base station and terminal according to an embodiment of the present application, and as shown in fig. 6, the main communication flow of the base station and the terminal is mainly divided into two phases: an initial access stage and a beam refinement stage. In the initial access stage, the base station periodically transmits a reference signal synchronization signal block SSB by using the coarse beam, and the terminal determines a first fine beam with highest frequency spectrum efficiency to be searched in the high-heat coarse beam according to the beam heat information of the coarse beam. And then the terminal accesses the system according to the related flow in the 5G NR protocol, and in the access process, the base station can determine the optimal transmitting coarse wave beam, and the coarse wave beam is the optimal transmitting coarse wave beam known by the channel diversity. In the beam refinement stage, the base station and the terminal both turn on all antennas of the first RF link, the base station firstly randomly selects a fine beam from the best transmitted coarse beam to transmit pilot signals to the terminal, and the terminal also randomly selects an initial fine beam from the best received fine beam to receive. To this end. After receiving, the terminal determines the optimal receiving and transmitting beam pair for the next iteration through the Adam algorithm, feeds back the beam to the base station for the next optimal transmission, and gradually determines the analog precoding/analog combining matrix by taking the Adam algorithm as a core.

The frequency spectrum efficiency of the simplified heat information scheme, the detailed heat information scheme and the traversal search scheme in the embodiment of the application is respectively simulated, the simulation considers a super-large-scale MIMO scene, specifically, 512 antennas are deployed in a base station, 8 radio frequency links are provided, each RF link is connected with 64 antennas, 8 coarse beams are provided at the base station side, and each coarse beam comprises 8 fine beams; a total of 8 users in the system, and each user deploys 8 antennas. In addition, among 8 coarse beams of the base station, 3 beams are low-heat beams, 5 beams are high-heat beams, and 1 user is in the coverage area of the low-heat beams.

As described above, the detailed heat information carries the beam heat ranking of each coarse beam in the coverage cell of the base station, and therefore, the terminal performs beam search only in the high heat coarse beams ranked 1 to 3; the reduced heat information only carries information whether the coarse beam is a high heat beam or not, so that the terminal can search the beams in all the high heat coarse beams. FIG. 7 is a graph comparing simulation results under a multi-terminal non-uniform distribution scenario, wherein the abscissa in the graph is the signal-to-noise ratio in decibels; the ordinate is spectral efficiency, units bits per second per hertz. As shown in fig. 7.

In the simplified heat information scheme, all terminals only search in the high heat coarse beam, so that unnecessary searching times and time are reduced, and the performance is very close to that of the optimal scheme. Due to the limitation of hardware calculation force, only 8 users can be simulated, but in theory, when more terminals are in a cell, the user ratio under the low-heat beam can be reduced, the performance of the scheme can be further improved, namely, when the number of the terminals in the cell is increased, the communication rate of all the terminals in the cell can be further improved.

In the detailed heat information scheme, the performance is close to that of the optimal scheme, but slightly lower than that of the simplified heat information scheme, because 5 high-heat beams are arranged in the simulation, and all terminals only allow searching in the high-heat beams ordered as 1-3, the method has the advantages of lower searching complexity, faster searching time, suitability for time-sensitive scenes and higher flexibility. If all terminals are set in the detailed heat scheme to search in the high heat beams ordered 1-5, namely all high heat beams, the algorithm performance is the same as that of the reduced heat information scheme. Next, table 1 shows the scheme complexity of the above three search schemes, as shown in table 1.

TABLE 1

Search scheme	Complexity of the scheme
		Simplified heat information scheme	N HOT_BS ×N MS K +N MASK K ×3 K
Detailed heat information scheme	N DETAILED_BS ×N MS K +N MASK K ×3 K
		Traversing search schemes	N CB_BS ×N MS K +N MASK K ×N MS K

Wherein N in the above Table 1 _{CB_BS} For the base station coarse wave beam number value is 8, N _MS Is 8, K is 8, N _MASK Is 64, N _{HOT_BS} The value of the high-heat wave beam of the base station is 5 and N _{DETAILED_BS} The high-heat beam number value obtained when searching is carried out on all the terminals and the high-heat beams of the base station set in the simulation is 3.

According to the above-mentioned value, the number of times of traversing the search scheme is 4.7224 ×10 ²¹ The detailed heat information scheme is slightly different from the simplified heat information scheme in searching times, but the complexity of the scheme is reduced by 99.996% compared with that of the traversing search scheme, and the effectiveness of the scheme is demonstrated. If more radio frequency links are deployed at the base station side (the search complexity level of beam search is mainly determined by the search complexity at the base station side, and the influence is limited when the number of the side antennas and the radio frequency links is small at the terminal side), the number of the terminals is moreThe complexity of the solution of this patent is even more advantageous.

Example 2

Based on embodiment 1 of the present application, an embodiment of a terminal is further provided, which is configured to execute the beam searching method with the execution subject as the terminal in any of the foregoing embodiments, and specific steps of executing, by the terminal provided in this embodiment, the beam searching scheme with the execution subject as the terminal in the foregoing certain embodiment are the same as those of the foregoing corresponding embodiments, and are not repeated herein.

In addition, based on embodiment 1 of the present application, there is also provided an embodiment of a beam searching apparatus, which executes the beam searching method of the foregoing execution subject of the foregoing embodiment as a terminal when running. Fig. 8 is a schematic structural diagram of an alternative beam searching apparatus according to an embodiment of the present application, where, as shown in fig. 8, the beam searching apparatus includes at least a receiving module 81, a first determining module 82 and a first searching module 83, where:

a receiving module 81, configured to receive beam heat information of a plurality of coarse beams sent by a base station, where the beam heat information of each coarse beam is used to reflect the number of terminals under a coverage area of the coarse beam;

a first determining module 82, configured to determine a high-heat coarse beam from the plurality of coarse beams according to the beam heat information, where the number of terminals under the coverage area of the high-heat coarse beam is not less than a preset threshold;

a first search module 83 is configured to determine a first beamlets that is most spectrally efficient within the high heat coarse beam.

It should be noted that, each module in the beam searching apparatus in the embodiment of the present application corresponds to each implementation step of the beam searching method with the implementation subject being the terminal in embodiment 1, and since detailed description has been made in embodiment 1, details not shown in part in this embodiment may refer to embodiment 1, and will not be repeated here.

Example 3

Based on embodiment 1 of the present application, a base station is further provided, which is configured to execute the beam searching method with the execution subject being the base station in any of the foregoing embodiments, and specific steps of executing the beam searching scheme with the execution subject being the base station in the foregoing certain embodiment by using the base station provided in this embodiment are the same as those of the foregoing corresponding embodiments, and are not repeated herein.

In addition, based on embodiment 1 of the present application, there is also provided an embodiment of a beam searching apparatus, which executes the beam searching method of the foregoing execution subject of the foregoing embodiment as a base station when running. Fig. 9 is a schematic structural diagram of an alternative beam searching apparatus according to an embodiment of the present application, where, as shown in fig. 9, the beam searching apparatus includes at least a second determining module 91, a sending module 92, and a second searching module 93, where:

a second determining module 91, configured to count beam heat information of a plurality of coarse beams in the covered cell, and determine a high-heat coarse beam in the plurality of coarse beams according to the beam heat information, where the beam heat information of each coarse beam is used to reflect the number of terminals in the coverage area of the coarse beam, and the number of terminals under the coverage area of the high-heat coarse beam is not less than a preset threshold;

A sending module 92, configured to send a synchronization signal block to the terminal through the high-heat coarse beam, where the synchronization signal block at least includes: indicating a target access time of the terminal to access the physical random access channel;

the second searching module 93 is configured to determine whether an actual access time of the terminal to access the physical random access channel is the same as a target access time when the terminal obtains a first fine beam with the lowest searching delay in the high-heat coarse beam, and determine that the high-heat coarse beam is an optimal coarse beam with the lowest searching delay when the actual access time is the same as the target access time.

It should be noted that, each module in the beam searching apparatus in the embodiment of the present application corresponds to each implementation step of the beam searching method with the implementation subject being the base station in embodiment 1, and since the detailed description has been already made in embodiment 1, part of details not shown in this embodiment may refer to embodiment 1, and will not be repeated here.

Example 4

According to an embodiment of the present application, there is also provided a nonvolatile storage medium having a program stored therein, wherein when the program runs, a device in which the nonvolatile storage medium is controlled to execute the beam searching method in embodiment 1 in which the execution subject is a terminal and to execute the beam searching method in which the execution subject is a base station.

Optionally, the device where the nonvolatile storage medium is located performs the following steps by running the program: receiving beam heat information of a plurality of coarse beams sent by a base station, wherein the beam heat information of each coarse beam is used for reflecting the number of terminals under the coverage area of the coarse beam; determining a high-heat coarse beam in the plurality of coarse beams according to the beam heat information, wherein the number of terminals under the coverage area of the high-heat coarse beam is not less than a preset threshold value; the most spectrally efficient first beamlets are determined within the high heat coarse beam.

Optionally, the device where the nonvolatile storage medium is located performs the following steps by running the program: counting beam heat information of a plurality of coarse beams in a covered cell, and determining high-heat coarse beams in the plurality of coarse beams according to the beam heat information, wherein the beam heat information of each coarse beam is used for reflecting the number of terminals in the coverage area of the coarse beam, and the number of the terminals under the coverage area of the high-heat coarse beam is not less than a preset threshold; transmitting a synchronization signal block to the terminal through the high-heat coarse beam, wherein the synchronization signal block at least comprises: indicating a target access time of the terminal to access the physical random access channel; when the terminal obtains a first thin beam with the lowest search time delay in the high-heat coarse beam, judging whether the actual access time of the terminal accessing the physical random access channel is the same as the target access time, and determining the high-heat coarse beam as the optimal coarse beam with the lowest search time delay when the actual access time is the same as the target access time.

The foregoing embodiment numbers of the present application are merely for the purpose of description, and do not represent the advantages or disadvantages of the embodiments.

In the foregoing embodiments of the present application, the descriptions of the embodiments are emphasized, and for a portion of this disclosure that is not described in detail in this embodiment, reference is made to the related descriptions of other embodiments.

In the several embodiments provided in the present application, it should be understood that the disclosed technology may be implemented in other manners. The above-described embodiments of the apparatus are merely exemplary, and the division of the units, for example, may be a logic function division, and may be implemented in another manner, for example, a plurality of units or components may be combined or may be integrated into another system, or some features may be omitted, or not performed. Alternatively, the coupling or direct coupling or communication connection shown or discussed with each other may be through some interfaces, units or modules, or may be in electrical or other forms.

The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

In addition, each functional unit in the embodiments of the present application may be integrated in one processing unit, or each unit may exist alone physically, or two or more units may be integrated in one unit. The integrated units may be implemented in hardware or in software functional units.

The integrated units, if implemented in the form of software functional units and sold or used as stand-alone products, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present application may be embodied in essence or a part contributing to the related art or all or part of the technical solution, in the form of a software product stored in a storage medium, including several instructions for causing a computer device (which may be a personal computer, a server or a network device, etc.) to perform all or part of the steps of the method according to the embodiments of the present application. And the aforementioned storage medium includes: a U-disk, a Read-Only Memory (ROM), a random access Memory (RAM, random Access Memory), a removable hard disk, a magnetic disk, or an optical disk, or other various media capable of storing program codes.

The foregoing is merely a preferred embodiment of the present application and it should be noted that modifications and adaptations to those skilled in the art may be made without departing from the principles of the present application, which are intended to be comprehended within the scope of the present application.

Claims (10)

1. A beam search method, applied to a terminal, comprising:

receiving beam heat information of a plurality of coarse beams sent by a base station, wherein the beam heat information of each coarse beam is used for reflecting the number of terminals under the coverage area of the coarse beam;

determining a high-heat coarse beam in the plurality of coarse beams according to the beam heat information, wherein the number of terminals under the coverage area of the high-heat coarse beam is not less than a preset threshold;

and determining the first thin beam with highest spectral efficiency in the high-heat coarse beam.

2. The method of claim 1, wherein receiving beam heat information for a plurality of coarse beams transmitted by a base station comprises:

and receiving the beam heat information of a plurality of coarse beams sent by the base station according to a receiving strategy corresponding to the information type of the beam heat information, wherein the information type comprises the following steps: detailed heat information or reduced heat information.

3. The method of claim 2, wherein receiving the first beam heat information of the plurality of coarse beams transmitted by the base station according to a reception policy corresponding to an information type of the beam heat information, comprises:

when the information type of the beam heat information is the detailed heat information, acquiring the detailed heat information of each coarse beam according to the target position of the synchronous signal block sent by the base station through the coarse beam on a time-frequency domain;

when the information type of the beam heat information is the simplified heat information, acquiring the simplified heat information of each coarse beam by receiving a synchronous signal block sent by the base station through the coarse beam, wherein the synchronous signal block at least comprises: and simplifying heat information of the coarse beam.

4. The method of claim 2, wherein determining a high heat coarse beam of the plurality of coarse beams from the beam heat information comprises:

when the information type of the beam heat information is the detailed heat information, determining a high heat coarse beam in a plurality of coarse beams according to first information content in the detailed heat information, wherein the first information content at least comprises: the beam serial numbers of the coarse beams and the beam heat degree ordering of each coarse beam in a cell covered by the base station;

When the information type of the beam heat information is the reduced heat information, determining a high heat coarse beam in the plurality of coarse beams according to second information content in the reduced heat information, wherein the second information content at least comprises: a radio signal for indicating whether each of the coarse beams is a high heat beam.

5. The method of claim 4, wherein determining a high heat coarse beam of the plurality of coarse beams based on a first information content within the detailed heat information comprises:

determining whether beam heat ordering of each coarse beam is positioned at the first M bits of K coarse beams in a cell covered by the base station based on the first information content, wherein M is more than or equal to 1 and less than or equal to K;

when the beam hotness of the coarse beam is ordered in the first M bits in the cell, determining that the coarse beam is a high-hotness coarse beam;

when the beam heat ordering of the coarse beam is not in the first M bits within the cell, it is determined that the coarse beam is not a high heat beam.

6. The method of claim 4, wherein determining a high heat coarse beam of the plurality of coarse beams based on a second information content within the reduced heat information comprises:

Determining that the coarse beam is a high heat beam when the radio signal is 1;

when the radio signal is 0, it is determined that the coarse beam is not a high heat beam.

7. The method of claim 1, wherein after determining the first beamlets within the high heat coarse beam that are most spectrally efficient, the method further comprises:

and when the base station determines that the high-heat coarse beam is the optimal coarse beam with the lowest searching time delay according to the first fine beam, the first fine beam and the second fine beam which is in the high-heat coarse beam and has the same propagation direction as the first fine beam are used as the optimal fine beam with the lowest searching time delay.

8. A beam search method, applied to a base station, comprising:

counting beam heat information of a plurality of coarse beams in a covered cell, and determining high-heat coarse beams in the plurality of coarse beams according to the beam heat information, wherein the beam heat information of each coarse beam is used for reflecting the number of terminals in the coverage area of the coarse beam, and the number of terminals under the coverage area of the high-heat coarse beam is not less than a preset threshold;

And sending a synchronization signal block to the terminal through the high-heat coarse beam, wherein the synchronization signal block at least comprises: indicating a target access opportunity of the terminal to access a physical random access channel;

when the terminal obtains a first thin beam with the lowest search time delay in the high-heat coarse beam, judging whether the actual access time of the terminal accessing the physical random access channel is the same as the target access time, and determining that the high-heat coarse beam is the optimal coarse beam with the lowest search time delay when the actual access time is the same as the target access time.

9. A terminal, comprising:

receiving beam heat information of a plurality of coarse beams sent by a base station, wherein the beam heat information of each coarse beam is used for reflecting the number of terminals under the coverage area of the coarse beam;

determining a high-heat coarse beam in the plurality of coarse beams according to the beam heat information, wherein the number of terminals under the coverage area of the high-heat coarse beam is not less than a preset threshold;

and determining the first thin beam with highest spectral efficiency in the high-heat coarse beam.

10. A base station, comprising:

Counting beam heat information of a plurality of coarse beams in a covered cell, and determining high-heat coarse beams in the plurality of coarse beams according to the beam heat information, wherein the beam heat information of each coarse beam is used for reflecting the number of terminals in the coverage area of the coarse beam, and the number of terminals under the coverage area of the high-heat coarse beam is not less than a preset threshold;

and sending a synchronization signal block to the terminal through the high-heat coarse beam, wherein the synchronization signal block at least comprises: indicating a target access opportunity of the terminal to access a physical random access channel;

when the terminal obtains a first thin beam with the lowest search time delay in the high-heat coarse beam, judging whether the actual access time of the terminal accessing the physical random access channel is the same as the target access time, and determining that the high-heat coarse beam is the optimal coarse beam with the lowest search time delay when the actual access time is the same as the target access time.