Patent Publication Number: US-2022239354-A1

Title: Beamforming-based communication method and network device

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of International Application No. PCT/CN2020/121063, filed on Oct. 15, 2020, which claims priority to Chinese Patent Application No. 201910983536.2, filed on Oct. 16, 2019. The disclosures of the aforementioned applications are incorporated herein by reference in these entireties. 
    
    
     TECHNICAL FIELD 
     The embodiments relate to the field of wireless communication, and in particular, to a beamforming-based communication method and a network device. 
     BACKGROUND 
     A 5th generation (5G) mobile communication technology is a latest cellular mobile communication technology. 5G performance objectives include a high rate, a low latency, and the like. 
     In a beamforming-based communication method, a base station configures a plurality of broadcast beams in fixed directions. The base station sends a broadcast message through beam sweeping. A terminal measures the plurality of broadcast beams to obtain an optimal beam, and then completes synchronization and demodulation of system information based on the optimal beam. 
     During actual application, some base stations are often in a low-load state or a no-load state. In this case, the base station consumes a large amount of electric energy to perform beam sweeping and can be accessed by only a few terminals. Therefore, it is necessary to improve the communication method performed by the base station, to reduce energy consumption of the base station. 
     SUMMARY 
     A beamforming-based communication method may reduce invalid broadcast beams and reduce a waste of resources. 
     According to a first aspect a beamforming-based communication method includes: after obtaining cell information, when the cell information meets a preset low-load condition, dividing, based on the cell information, to-be-processed broadcast messages into a plurality of broadcast message groups; determining, based on a preset correspondence between a broadcast message and a broadcast beam, a broadcast beam group corresponding to each broadcast message group and a broadcast beam for sending no broadcast message in each time window; sending the broadcast message group in each time window by using the broadcast beam group; and shutting down, in each time window, the broadcast beam for sending no broadcast message. 
     The cell information may include but is not limited to downlink resource utilization and/or a quantity of access users, where the quantity of access users is a quantity of users who have established a communication connection with a network device in a cell. The to-be-processed broadcast messages are all broadcast messages to be sent in a time window, each broadcast message group corresponds to one time window, and a length of each time window is equal to a synchronization signal sending periodicity. Shutting down the broadcast beam means that the network device shuts down, in a target slot in which no broadcast message is transmitted, a bias voltage of a power amplifier corresponding to the target slot, to achieve an objective of sending no broadcast beam. The target slot is a slot that is configured to be allowed to transmit the broadcast message. The broadcast beam group is one or more beams used to send the broadcast message in the time window. 
     When the cell information meets the preset low-load condition, the network device divides the to-be-processed broadcast messages into the plurality of broadcast message groups. When the cell information does not meet the preset low-load condition, it indicates that the cell is not in a low-load state or a no-load state. In this way, the network device may send all broadcast messages in one time window, and there is no need to perform the step of dividing, based on the cell information, the to-be-processed broadcast messages into the plurality of broadcast message groups. 
     In this implementation, when the cell information meets the preset low-load condition, all broadcast messages that are originally sent in one time window are divided into a plurality of broadcast message groups, and then the plurality of broadcast message groups are sent in a plurality of time windows. In this way, some broadcast beams are used in each time window to send the broadcast message. Shutting down the broadcast beam for sending no broadcast message may also be understood as shutting down a bias voltage of a power amplifier corresponding to the broadcast beam for sending no broadcast message. In this way, power amplifiers working in each time window can be reduced, to reduce energy consumption of the network device. 
     In a possible implementation, the cell information is the downlink resource utilization; and when the downlink resource utilization is less than a first preset threshold, it is determined that the cell information meets the preset low-load condition. The first preset threshold may be a ratio of a total quantity of slots occupied by the to-be-processed broadcast messages in the time window to a total quantity of downlink slots, or a value that is set based on actual application. In this way, a method for determining whether the cell is in the low-load state is provided. 
     Optionally, the dividing, based on the cell information, to-be-processed broadcast messages into a plurality of broadcast message groups includes: when the downlink resource utilization is less than the first preset threshold and the downlink resource utilization is greater than or equal to a second preset threshold, dividing the to-be-processed broadcast messages into a first quantity of broadcast message groups; and when the downlink resource utilization is less than the second preset threshold, dividing the to-be-processed broadcast messages into a second quantity of broadcast message groups. Both the first quantity and the second quantity are positive integers greater than 1, the first quantity is less than the second quantity, and the second quantity is less than or equal to a total quantity of broadcast beams configured for the cell. In this implementation, higher downlink resource utilization indicates a smaller quantity of broadcast beam groups used to send the broadcast message groups, and a larger quantity of broadcast beams in each broadcast beam group indicates fewer broadcast beams that can be shut down in each time window. Otherwise, more broadcast beams can be shut down in each time window. Therefore, a method for flexibly adjusting a quantity of broadcast message groups based on the downlink resource utilization can not only meet a differentiated requirement for a communication resource, but also can better reduce energy consumption. 
     In another possible implementation, the cell information is the quantity of access users; and when the quantity of access users is less than a first preset user quantity, it is determined that the cell information meets the preset low-load condition. In this way, another method for determining whether the cell is in the low-load state is provided. 
     Optionally, the dividing, based on the cell information, to-be-processed broadcast messages into a plurality of broadcast message groups includes: when the quantity of access users is less than the first preset user quantity and the quantity of access users is greater than or equal to a second preset user quantity, dividing the to-be-processed broadcast messages into a third quantity of broadcast message groups; and when the quantity of access users is less than the second preset user quantity, dividing the to-be-processed broadcast messages into a fourth quantity of broadcast message groups. Both the third quantity and the fourth quantity are positive integers greater than 1, the third quantity is less than the fourth quantity, and the fourth quantity is less than or equal to a total quantity of broadcast beams configured for the cell. 
     In this implementation, a larger quantity of access users indicates a smaller quantity of broadcast beam groups used to send the broadcast message groups, and a larger quantity of broadcast beams in each broadcast beam group indicates fewer broadcast beams that can be shut down in each time window. Otherwise, more broadcast beams can be shut down in each time window. Therefore, a method for flexibly adjusting a quantity of broadcast message groups based on the quantity of access users is provided, to meet a differentiated requirement for a communication resource and better reduce energy consumption. 
     In another possible implementation, the cell information includes the downlink resource utilization and the quantity of access users; and when the downlink resource utilization is less than a first preset threshold and the quantity of access users is less than a first preset user quantity, it is determined that the cell information meets the preset low-load condition. In this way, another method for determining whether the cell is in the low-load state is provided. 
     Optionally, the dividing, based on the cell information, to-be-processed broadcast messages into a plurality of broadcast message groups includes: when the downlink resource utilization falls within a first downlink resource utilization range and the quantity of access users falls within a first user quantity range, dividing the to-be-processed broadcast messages into a fifth quantity of broadcast message groups; and when the downlink resource utilization falls within a second downlink resource utilization range and the quantity of access users falls within a second user quantity range, dividing the to-be-processed broadcast messages into a sixth quantity of broadcast message groups. Both the fifth quantity and the sixth quantity are positive integers greater than 1, the fifth quantity is less than the sixth quantity, and the sixth quantity is less than or equal to a total quantity of broadcast beams configured for the cell. 
     In this implementation, higher downlink resource utilization and a larger quantity of access users indicate a smaller quantity of broadcast beam groups used to send the broadcast message groups, and a larger quantity of broadcast beams in each broadcast beam group indicates fewer broadcast beams that can be shut down in each time window. Otherwise, more broadcast beams can be shut down in each time window. Therefore, a method for flexibly adjusting a quantity of broadcast message groups based on the downlink resource utilization and the quantity of access users is provided, to meet a differentiated requirement for a communication resource and better reduce energy consumption. 
     In any one of the first aspect or the possible implementations of the first aspect, the broadcast message includes at least one of a synchronization signal block, a SIB1 message, OSI, or a paging message. 
     According to a second aspect, a beamforming-based communication method includes: after obtaining cell information, when the cell information meets a preset low-load condition, prolonging, based on the cell information, a sending periodicity of a broadcast message; and sending the broadcast message based on the prolonged sending periodicity. Compared with sending the broadcast message based on preset duration, sending the broadcast message based on the prolonged sending periodicity only requires a smaller quantity of sending times of the broadcast message. In this way, fewer broadcast beams need to be used, thereby reducing energy consumption of a network device. 
     In a possible implementation, the cell information is downlink resource utilization; and when the downlink resource utilization is less than a first preset threshold, it is determined that the cell information meets the preset low-load condition. In this way, a method for determining whether a cell is in a low-load state is provided. 
     Optionally, the prolonging, based on the cell information, a sending periodicity of a broadcast message includes: when the downlink resource utilization is less than the first preset threshold and the downlink resource utilization is greater than or equal to a second preset threshold, adjusting the sending periodicity of the broadcast message from the preset duration to first duration; and when the downlink resource utilization is less than the second preset threshold, adjusting the sending periodicity of the broadcast message from the preset duration to second duration. The second duration is greater than the first duration, and the first duration is greater than the preset duration. In this implementation, there is a negative correlation between the downlink resource utilization and the sending periodicity of the broadcast message. Lower downlink resource utilization indicates a longer sending periodicity of the broadcast message and fewer broadcast beams for sending the broadcast message in each periodicity. In this way, working power amplifiers can be reduced, to reduce more energy consumption. Therefore, a method for flexibly adjusting the sending periodicity of the broadcast message based on the downlink resource utilization is provided, to meet a differentiated requirement for a communication resource and better reduce energy consumption. 
     In a possible implementation, the cell information is a quantity of access users; and when the quantity of access users is less than a first preset user quantity, it is determined that the cell information meets the preset low-load condition. In this way, another method for determining whether the cell is in a low-load state is provided. 
     Optionally, the prolonging, based on the cell information, a sending periodicity of a broadcast message includes: when the quantity of access users is less than the first preset user quantity and the quantity of access users is greater than or equal to a second preset user quantity, adjusting the sending periodicity of the broadcast message from the preset duration to third duration; and when the quantity of access users is less than the second preset user quantity, adjusting the sending periodicity of the broadcast message from the preset duration to fourth duration. The fourth duration is greater than the third duration, and the third duration is greater than the preset duration. It can be understood that there is a negative correlation between the quantity of access users and the sending periodicity of the broadcast message. A smaller quantity of access users indicates a longer sending periodicity of the broadcast message and fewer broadcast beams for sending the broadcast message in each periodicity. In this way, working power amplifiers can be reduced, to reduce more energy consumption. Therefore, a method for flexibly adjusting the sending periodicity of the broadcast message based on the quantity of access users is provided, to meet a differentiated requirement for a communication resource and better reduce energy consumption. 
     In another possible implementation, the cell information includes downlink resource utilization and a quantity of access users; and when the downlink resource utilization is less than a first preset threshold and the quantity of access users is less than a first preset user quantity, it is determined that the cell information meets the preset low-load condition. In this way, another method for determining whether the cell is in a low-load state is provided. 
     Optionally, the prolonging, based on the cell information, a sending periodicity of a broadcast message includes: when the downlink resource utilization falls within a first downlink resource utilization range and the quantity of access users falls within a first user quantity range, adjusting the sending periodicity of the broadcast message from the preset duration to fifth duration; and when the downlink resource utilization falls within a second downlink resource utilization range and the quantity of access users falls within a second user quantity range, adjusting the sending periodicity of the broadcast message from the preset duration to sixth duration. The sixth duration is greater than the fifth duration, and the fifth duration is greater than the preset duration. The first downlink resource utilization range is a range that is less than the first preset threshold and not less than a second preset threshold, and the first user quantity range is a range that is less than the first preset user quantity and not less than a second preset user quantity. The second downlink resource utilization range is a range that is less than the second preset threshold, and the second user quantity range is a range that is less than the second preset user quantity. Therefore, a method for flexibly adjusting the sending periodicity of the broadcast message based on the downlink resource utilization and the quantity of access users is provided, to meet a differentiated requirement for a communication resource and better reduce energy consumption. 
     In any one of the second aspect or the possible implementations of the second aspect, the broadcast message includes at least one of a synchronization signal block, a system information block type 1 SIB1 message, other system information OSI, or a paging message. 
     According to a third aspect, a beamforming-based communication method includes: after receiving, in an on-demand broadcast mode, a broadcast other system information OSI request initiated by a terminal, sending OSI to the terminal based on the broadcast OSI request; when a quantity of periodicities during which broadcast OSI requests sent by the terminal are continuously received in a monitoring window is greater than or equal to a first preset periodicity quantity, adjusting a mode for broadcasting the OSI from the on-demand broadcast mode to a periodic broadcast mode; and periodically broadcasting the OSI in the periodic broadcast mode. In this implementation, in a heavy traffic scenario, UE does not need to send an OSI request to a network device and can directly obtain OSI by periodically monitoring the OSI. Therefore, the network device does not need to receive and process OSI requests of a large quantity of UEs, thereby reducing resource overheads of the OSI requests. 
     In a possible implementation, when a quantity of periodicities for broadcasting the OSI is greater than or equal to a second preset periodicity quantity, the mode for broadcasting the OSI is adjusted from the periodic broadcast mode to the on-demand broadcast mode. 
     According to a fourth aspect, a network device has a function of implementing the beamforming-based communication method in the first aspect. The function may be implemented by hardware or may be implemented by hardware executing corresponding software. The hardware or the software includes one or more modules corresponding to the foregoing function. 
     According to a fifth aspect, a network device has a function of implementing the beamforming-based communication method in the second aspect. The function may be implemented by hardware or may be implemented by hardware executing corresponding software. The hardware or the software includes one or more modules corresponding to the foregoing function. 
     According to a sixth aspect, a network device has a function of implementing the beamforming-based communication method in the third aspect. The function may be implemented by hardware or may be implemented by hardware executing corresponding software. The hardware or the software includes one or more modules corresponding to the foregoing function. 
     According to a seventh aspect, a computer-readable storage medium stores instructions. When the instructions are run on a computer, the computer is enabled to perform the methods in the foregoing aspects. 
     According to an eighth aspect, a computer program product includes instructions. When the computer program product runs on a computer, the computer is enabled to perform the methods in the foregoing aspects. 
     According to a ninth aspect, a communication apparatus may include an entity such as a terminal device or a chip. The communication apparatus includes a processor and a memory. The memory is configured to store instructions, and the processor is configured to execute the instructions in the memory, to enable the communication apparatus to perform the method according to any one of the first aspect, second aspect, or the third aspect. 
     According to a tenth aspect, a chip system includes a processor, configured to support a corresponding device in implementing a function in the foregoing aspects, for example, sending or processing data and/or information in the foregoing method. In a possible implementation, the chip system further includes a memory. The memory is configured to store program instructions and data that are necessary for the corresponding device. The chip system may include a chip or may include a chip and another discrete component. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a schematic diagram of an application scenario; 
         FIG. 2  is a schematic diagram of a structure of a base station; 
         FIG. 3  is a flowchart of a beamforming-based communication method; 
         FIG. 4A  is a schematic diagram of slots occupied by all broadcast messages in a synchronization signal sending periodicity; 
         FIG. 4B  is a schematic diagram of slots occupied by a first broadcast message group when there are two broadcast message groups; 
         FIG. 4C  is a schematic diagram of slots occupied by a second broadcast message group when there are two broadcast message groups; 
         FIG. 4D  is a schematic diagram of a slot occupied by a first broadcast message group when there are four broadcast message groups; 
         FIG. 4E  is a schematic diagram of a slot occupied by a second broadcast message group when there are four broadcast message groups; 
         FIG. 4F  is a schematic diagram of a slot occupied by a third broadcast message group when there are four broadcast message groups; 
         FIG. 4G  is a schematic diagram of a slot occupied by a fourth broadcast message group when there are four broadcast message groups; 
         FIG. 5  is another flowchart of a beamforming-based communication; 
         FIG. 6A  is a schematic diagram of periodically sending a SIB1; 
         FIG. 6B  is another schematic diagram of periodically sending a SIB1; 
         FIG. 6C  is another schematic diagram of periodically sending a SIB1; 
         FIG. 7  is another flowchart of a beamforming-based communication method; 
         FIG. 8  is a schematic diagram of sending OSI in different modes; 
         FIG. 9  is another schematic diagram of a structure of a network device; 
         FIG. 10  is another schematic diagram of a structure of a network device; and 
         FIG. 11  is another schematic diagram of a structure of a network device. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     A beamforming-based communication method may be applied to a 5G communication system in standalone (SA) networking. 
     As shown in  FIG. 1 , a cell in the 5G communication system includes at least one network device  101  and at least one terminal  102 . 
     The network device  101  is a network side device that performs wireless communication with the terminal  102 , for example, a base station (gNB), a micro base station, an access point, or a transmission reception point (TRP) in the 5G communication system. 
     The terminal  102  is a terminal in a 5G network, and is also referred to as an access terminal, a subscriber unit, a subscriber station, a mobile station, a remote terminal, a mobile device, a user terminal, a terminal device, a wireless communication device, or a user apparatus. The terminal  102  may be a cellular phone, a handheld device having a wireless communication function, a computing device, a vehicle-mounted device, a wearable device, or the like. 
     The network device  101  is configured with beams in N directions, and a beam that can be used to send a broadcast message is referred to as a broadcast beam. The network device  101  sequentially transmits wireless signals by using beams in different directions, to complete beam coverage for the cell. A process in which the network device  101  sequentially transmits the wireless signals by using the beams in different directions is also referred to as beam sweeping. 
     As shown in  FIG. 1 , the network device  101  uses eight beams to cover the cell served by the network device  101 . The network device  101  sends the broadcast message through beam sweeping. After measuring broadcast messages that are transmitted by using different beams, the terminal  102  sends a beam measurement report to the network device  101 ; and the network device  101  determines an optimal beam based on the beam measurement report, and the terminal  102  completes synchronization and demodulation of system information based on the optimal beam. 
     The broadcast message includes but is not limited to one or more of a synchronization signal block (SSB), a system information block type 1 (SIB1), other system information (OSI), and a paging message. 
     A synchronization signal (SS) is a signal that provides a same time reference for a device that needs to synchronously process information. The synchronization signal may include a primary synchronization signal (PSS) and a secondary synchronization signal (SSS). 
     An SSB is a resource block including one PSS symbol, one SSS, and two or more physical broadcast channel (PBCH) symbols in new radio (NR). A PSS symbol, an SSS symbol, and a PBCH symbol may be orthogonal frequency division multiplexing (OFDM) symbols, and one PSS, SSS, or PBCH resource block may include one or more OFDM symbols. Positions of the PSS symbol, the SSS symbol, and the PBCH symbol in the synchronization signal block may be adjacent. A plurality of synchronization signal blocks forms a synchronization signal burst (SS burst), and a plurality of synchronization signal bursts forms a synchronization signal burst set (SS burst set). 
     A sending periodicity of the SSB may be 20 milliseconds (ms), 40 ms, 80 ms, or 160 ms. Usually, a periodicity for searching the SSB in an initial cell is set to 20 ms, and transmission is completed within 5 ms. 
     The SIB1 carries information related to cell access and cell selection. The SIB1 is sent through a downlink shared channel (DL-SCH). A sending periodicity of the SIB1 may be within 160 ms, and periodicity duration may be adjusted by the network device. The SIB1 is also referred to as a SIB1 message. 
     The OSI is sent through a physical downlink shared channel (PDSCH). The OSI includes a SIB2 to a SIBn. 
     The paging message may also be denoted as Paging (Pg). 
     An example in which the network device  101  is a base station is used below.  FIG. 2  shows an embodiment of the base station. In this embodiment, the base station  200  includes an antenna  201 , a transmitter circuit  202 , a receiver circuit  203 , a processor  204 , and a memory  205 . 
     The base station  200  includes a plurality of antennas  201 , and the plurality of antennas  201  form an antenna array. There may be one or more transmitter circuits  202 , receiver circuits  203 , processors  204 , and memories  205 . 
     The processor  204  controls an operation of the base station  200 . 
     The memory  205  may include a read-only memory and a random access memory and provides instructions and data for the processor  204 . The memory  205  may store computer program code. A part of the memory  205  may further include a non-volatile random access memory. 
     In addition, a carrier for accommodating the transmitter circuit  202  and the receiver circuit  203  may be included, to allow data transmission and receiving between the base station  200  and a remote position. The transmitter circuit  202  and the receiver circuit  203  may be coupled to the antenna  201 . Components of the base station  200  are coupled together by using a bus system. In addition to a data bus, the bus system further includes a power bus, a control bus, and a status signal bus. 
     A method in the embodiments may be applied to the processor  204  or may be implemented by the processor  204 . The processor  204  includes an integrated circuit chip and has a signal processing capability. 
     In an implementation process, steps in the following method may be implemented by using a hardware integrated logic circuit in the processor  204 , or by using instructions in a form of software. The instructions may be implemented and controlled by cooperating with the processor  204  and are used to perform the method in the embodiments. The processor  204  may be a general-purpose processor, a digital signal processor, an application-specific integrated circuit, a field programmable gate array or another programmable logic device, a discrete gate or a transistor logic device, or a discrete hardware component. The processor may implement or perform methods, steps, and logical block diagrams in the embodiments. The general-purpose processor may be a microprocessor, or the processor may be any conventional processor, decoder, or the like. The steps in the method with reference to the embodiments may be directly performed and completed by a hardware decoding processor or may be performed and completed by using a combination of hardware and software modules in a decoding processor. The software module may be located in a mature storage medium in the art, such as a random access memory, a flash memory, a read-only memory, a programmable read-only memory, an electrically erasable programmable memory, or a register. 
     In a current 5G communication method, a network device sends a broadcast message in each synchronization signal sending periodicity, for access by a terminal. In a scenario with a small quantity of users, continuously sending broadcast messages causes more energy consumption of the network device. For this problem, all broadcast messages sent in one time window are divided into a plurality of broadcast message groups, and then one broadcast message group is sent in each time window, the plurality of broadcast message groups are sent in a plurality of time windows, and a broadcast beam for sending no broadcast message is shut down in each time window. This reduces beams that need to be generated by the network device and reduces energy consumption of the network device in a broadcast process. 
     As shown in  FIG. 3 , an embodiment of a beamforming-based communication method provided includes the following steps. 
     Step  301 . Obtain cell information. 
     In this embodiment, the cell information includes downlink resource utilization and/or a quantity of access users. 
     Step  302 . When the cell information meets a preset low-load condition, divide, based on the cell information, to-be-processed broadcast messages into a plurality of broadcast message groups. 
     When the downlink resource utilization is less than a first preset threshold, the quantity of access users is less than a first preset user quantity, or both the foregoing conditions are met, it may be determined that the cell information meets the preset low-load condition. If the cell information meets the preset low-load condition, it indicates that a cell network is in a low-load state or a no-load state; and if the cell information does not meet the preset low-load condition, it indicates that the cell network is in a high-load state or a normal-load state. 
     The first preset threshold may be a ratio of a total quantity of slots occupied by the to-be-processed broadcast messages in a time window to a total quantity of downlink slots, or a value that is set based on actual application. The value is not limited. A specific value of the first preset user quantity may be set based on a quantity of communication users during actual application, and this is not limited. 
     The to-be-processed broadcast messages are all broadcast messages to be sent in one time window. Each broadcast message group includes one or more broadcast messages, and broadcast messages in different broadcast message groups correspond to different slots. The broadcast message includes at least one of a synchronization signal block, a SIB1 message, OSI, or a paging message. Each broadcast message group corresponds to one time window, and a length of each time window is equal to a synchronization signal sending periodicity. It should be noted that a plurality of time windows corresponding to the plurality of broadcast message groups may be consecutive. 
     Step  303 . Determine, based on a preset correspondence between a broadcast message and a broadcast beam, a broadcast beam group corresponding to each broadcast message group and a broadcast beam for sending no broadcast message in each time window. 
     In one time window, the broadcast beam group includes one or more broadcast beams. In each time window, a broadcast beam used to send the broadcast message and the broadcast beam for sending no broadcast message in the time window may be determined. In the preset correspondence, for each time window, a number of a slot occupied by each broadcast message may be set based on a protocol. For details, refer to the following optional embodiments. 
     Step  304 . Send the broadcast message group in each time window by using the broadcast beam group. 
     One broadcast message may be sent in one slot by using each broadcast beam. It may be understood that different broadcast beams are sent in different time windows, so that a terminal can measure all broadcast beams in the plurality of time windows and then obtain an optimal beam based on a beam measurement report. 
     Step  305 . Shut down, in each time window, the broadcast beam for sending no broadcast message. 
     After determining the broadcast beam for sending no broadcast message, a network device shuts down the broadcast beam for sending no broadcast message. Shutting down the broadcast beam may be understood as shutting down a bias voltage of a power amplifier corresponding to the broadcast beam for sending no broadcast message. All or some of broadcast beams for sending no broadcast message can be shut down. 
     It should be noted that there is no fixed sequence between step  304  and step  305 . In a time window, a broadcast beam for sending no broadcast message may be shut down before the broadcast message group is sent by using the broadcast beam group. 
     In this embodiment, when the cell is in the low-load state or the no-load state, some broadcast beams are sent in each time window for access by users, and other broadcast beams are shut down. In this way, power amplifiers working in each time window can be reduced in a broadcast process, to reduce energy consumption of the network device. 
     The cell information may be the downlink resource utilization and/or the quantity of access users. Based on the foregoing cell information, the to-be-processed broadcast messages may be divided, based on the cell information, into the plurality of broadcast message groups in a plurality of manners. The following provides detailed descriptions. 
     In an optional embodiment, the cell information is the downlink resource utilization. 
     When the downlink resource utilization is less than the first preset threshold and the downlink resource utilization is greater than or equal to a second preset threshold, the to-be-processed broadcast messages are divided into a first quantity of broadcast message groups; and when the downlink resource utilization is less than the second preset threshold, the to-be-processed broadcast messages are divided into a second quantity of broadcast message groups. Both the first quantity and the second quantity are positive integers greater than 1, the first quantity is less than the second quantity, and the second quantity is less than or equal to a total quantity of broadcast beams configured for the cell. 
     In this embodiment, when the downlink resource utilization is greater than or equal to the first preset threshold, it is determined that the cell information does not meet the preset low-load condition. When the downlink resource utilization is less than the first preset threshold, it is determined that the cell information meets the preset low-load condition. 
     The network device presets two downlink resource utilization ranges. A first downlink resource utilization range is [the second preset threshold, the first preset threshold), and a second downlink resource utilization range is [0, the second preset threshold). When the downlink resource utilization falls within the first downlink resource utilization range, the to-be-processed broadcast messages are divided into N1 broadcast message groups. When the obtained downlink resource utilization falls within the second downlink resource utilization range, the to-be-processed broadcast messages may be divided into N2 broadcast message groups. N1 is the first quantity, and N2 is the second quantity. N2 is greater than N1, that is, there is a negative correlation between the downlink resource utilization and a quantity of broadcast message groups. 
     When the downlink resource utilization falls within the second downlink resource utilization range, it indicates that the downlink resource utilization of the cell is at the lowest level. In this case, very few cell resources are occupied. If the to-be-processed broadcast messages are divided into the N1 broadcast message groups, resources are wasted. Compared with a case in which the to-be-processed broadcast messages are divided into the N1 broadcast message groups, after the to-be-processed broadcast messages are divided into the N2 broadcast message groups, each broadcast message group includes fewer broadcast messages, that is, fewer broadcast beams need to be transmitted in each time window, and more broadcast beams can be shut down, thereby reducing a waste of resources and further reducing energy consumption. Therefore, a method for flexibly adjusting a quantity of broadcast message groups based on the downlink resource utilization is provided, to meet a differentiated requirement for a communication resource and better reduce energy consumption. 
     The foregoing describes a case in which the downlink resource utilization falls within the two downlink resource utilization ranges. It may be understood that the network device may alternatively set three or more downlink resource utilization ranges. For example, a first downlink resource utilization range is [the second preset threshold, the first preset threshold), a second downlink resource utilization range is [a third preset threshold, the second preset threshold), and a third downlink resource utilization range is [0, the third preset threshold). In this case, when the downlink resource utilization falls within the first downlink resource utilization range, the to-be-processed broadcast messages are divided into the N1 broadcast message groups; when the downlink resource utilization falls within the second downlink resource utilization range, the to-be-processed broadcast messages are divided into the N2 broadcast message groups; and when the downlink resource utilization falls within the third downlink resource utilization range, the to-be-processed broadcast messages are divided into an N′ broadcast message groups. N1, N2, and N′ are all positive integers greater than 1, N1&lt;N2&lt;N′, and N′ is less than or equal to the total quantity of broadcast beams configured for the cell. By analogy, in a case of more than three ranges, a corresponding quantity of broadcast message groups may be set based on a range within which the downlink resource utilization falls. Therefore, some other specific implementations are provided, to meet a differentiated requirement for a communication resource and reduce energy consumption. 
     In another optional embodiment, the cell information is the quantity of access users. 
     When the quantity of access users is less than the first preset user quantity and the quantity of access users is greater than or equal to a second preset user quantity, the to-be-processed broadcast messages are divided into a third quantity of broadcast message groups; and when the quantity of access users is less than the second preset user quantity, the to-be-processed broadcast messages are divided into a fourth quantity of broadcast message groups. Both the third quantity and the fourth quantity are positive integers greater than 1, the third quantity is less than the fourth quantity, and the fourth quantity is less than or equal to a total quantity of broadcast beams configured for the cell. 
     In this embodiment, when the quantity of access users is less than the first preset user quantity, it is determined that the cell information meets the preset low-load condition; and when the quantity of access users is greater than or equal to the first preset user quantity, it is determined that the cell information does not meet the preset low-load condition. 
     The network device presets two user quantity ranges, which are a first user quantity range and a second user quantity range. The first user quantity range is [the second preset user quantity, the first preset user quantity), and the second user quantity range is [0, the second preset user quantity). When the quantity of access users falls within the first user quantity range, the to-be-processed broadcast messages are divided into N3 broadcast message groups. When the quantity of access users falls within the second user quantity range, the to-be-processed broadcast messages may be divided into N4 broadcast message groups. N3 is the third quantity, and N4 is the fourth quantity. N4 is greater than N3, that is, there is a negative correlation between the quantity of access users and a quantity of broadcast message groups. 
     When the quantity of access users falls within the second user quantity range, it indicates that the quantity of access users in the cell is at the lowest level. In this case, there are very few users in the cell. If the to-be-processed broadcast messages are divided into the N3 broadcast message groups, resources are wasted. Compared with a case in which the to-be-processed broadcast messages are divided into the N3 broadcast message groups, after the to-be-processed broadcast messages are divided into the N4 broadcast message groups, each broadcast message group includes fewer broadcast messages, that is, fewer broadcast beams need to be transmitted in each time window, and more broadcast beams can be shut down, thereby reducing a waste of resources and further reducing energy consumption. Therefore, a method for flexibly adjusting a quantity of broadcast message groups based on the quantity of access users is provided, to meet a differentiated requirement for a communication resource and better reduce energy consumption. 
     The foregoing describes a case in which the quantity of access users falls within the two user quantity ranges. It may be understood that the network device may alternatively set three or more user quantity ranges, and then may determine, based on a correspondence between a user quantity range and a quantity of broadcast message groups, a quantity of broadcast message groups corresponding to the quantity of access users. 
     In another optional embodiment, the cell information includes the downlink resource utilization and the quantity of access users. 
     When the downlink resource utilization falls within a first downlink resource utilization range and the quantity of access users falls within a first user quantity range, all broadcast message groups to be sent in one time window are divided into a fifth quantity of broadcast message groups based on the downlink resource utilization and the quantity of access users; and when the downlink resource utilization falls within a second downlink resource utilization range and the quantity of access users falls within a second user quantity range, all broadcast message groups to be sent in one time window are divided into a sixth quantity of broadcast message groups. Both the fifth quantity and the sixth quantity are positive integers greater than 1, the fifth quantity is less than the sixth quantity, and the sixth quantity is less than or equal to a total quantity of broadcast beams configured for the cell. 
     In this embodiment, when the downlink resource utilization is less than the first preset threshold and the quantity of access users is less than the first preset user quantity, it is determined that the cell information meets the preset low-load condition. When the downlink resource utilization is greater than or equal to the first preset threshold or the quantity of access users is greater than or equal to the first preset user quantity, it is determined that the cell information does not meet the preset low-load condition. 
     The network device presets two downlink resource utilization ranges and two user quantity ranges. The first downlink resource utilization range is [a second preset threshold, the first preset threshold), and the second downlink resource utilization range is [0, the second preset threshold). The first user quantity range is [a second preset user quantity, the first preset user quantity), and the second user quantity range is [0, the second preset user quantity). 
     When the downlink resource utilization falls within the first downlink resource utilization range and the quantity of access users falls within the first user quantity range, the to-be-processed broadcast messages are divided into N5 broadcast message groups. When the obtained downlink resource utilization falls within the second downlink resource utilization range and the quantity of access users falls within the second user quantity range, the to-be-processed broadcast messages may be divided into N6 broadcast message groups. N5 is the fifth quantity, N6 is the sixth quantity, and N6 is greater than N5. Therefore, a method for flexibly adjusting a quantity of broadcast message groups based on the downlink resource utilization and the quantity of access users is provided, to meet a differentiated requirement for a communication resource and better reduce energy consumption. 
     It may be understood that the network device may alternatively set three or more downlink resource utilization ranges and user quantity ranges, and then may determine, based on a correspondence among a downlink resource utilization range, a user quantity range, and a quantity of broadcast message groups, a quantity of broadcast message groups corresponding to the downlink resource utilization and the quantity of access users. 
     For ease of understanding, the following describes the beamforming-based communication method by using a specific example. 
     For all broadcast messages to be sent in one time window, each broadcast message occupies one slot. For example, the slots occupied by all the broadcast messages may be shown in Table 1. 
     
       
         
           
               
               
               
               
               
             
               
                 TABLE 1 
               
               
                   
               
               
                   
                 SSB 
                 SIB1 
                 OSI 
                 Paging 
               
               
                   
               
             
            
               
                 Slot numbers of all 
                 0, 1, 2, 3 
                 10, 11, 12, 13, 
                 1, 2 
                 10, 11, 12, 13, 
               
               
                 broadcast messages 
                   
                 15, 16, 17 
                   
                 15, 16,17 
               
               
                   
               
            
           
         
       
     
     For example, a time window is 20 ms. The time window includes a first frame and a second frame that are adjacent to each other, and the first frame is before the second frame. 
     As shown in  FIG. 4A , the broadcast messages shown in Table 1 include an SSB, a SIB1, OSI, and Paging. Slots occupied by the SSB include a slot  0 , a slot  1 , a slot  2 , and a slot  3  in the first frame. Slots occupied by the SIB1 include a slot  10 , a slot  11 , a slot  12 , a slot  13 , a slot  15 , a slot  16 , and a slot  17  in the first frame. Slots occupied by the OSI include a slot  1  and a slot  2  in the second frame. Slots occupied by the Paging include a slot  10 , a slot  11 , a slot  12 , a slot  13 , a slot  15 , a slot  16 , and a slot  17  in the second frame. 
     The to-be-processed broadcast messages may be divided into the plurality of broadcast message groups in a plurality of manners. The following provides an example for description. 
     In an example, when the downlink resource utilization falls within the first downlink resource utilization range, all the broadcast messages are divided into two broadcast message groups, and slots occupied by each broadcast message group are shown in Table 2. 
     
       
         
           
               
               
               
               
               
             
               
                 TABLE 2 
               
               
                   
               
               
                   
                 SSB 
                 SIB1 
                 OSI 
                 Paging 
               
               
                   
               
             
            
               
                 Slot number of a first 
                 0, 1 
                 10, 11, 12, 13 
                 1 
                 10, 11, 12, 13 
               
               
                 broadcast message group 
                   
                   
                   
                   
               
               
                 Slot number of a second 
                 2, 3 
                 15, 16, 17 
                 2 
                 15, 16, 17 
               
               
                 broadcast message group 
               
               
                   
               
            
           
         
       
     
     A broadcast beam (that is, a first broadcast beam group) corresponding to the first broadcast message group, and a broadcast beam (that is, a second broadcast beam group) corresponding to the second broadcast message group are determined 
       FIG. 4B  is a schematic diagram of slots occupied by the first broadcast message group shown in Table 2, and  FIG. 4C  is a schematic diagram of slots occupied by the second broadcast message group shown in Table 2. The following describes the first broadcast beam group and the second broadcast beam group based on  FIG. 4B  and  FIG. 4C . 
     As shown in  FIG. 4B , in a first time window, the first broadcast beam group includes broadcast beams transmitted in the slot  0  and the slot  1  of the first frame, broadcast beams transmitted in the slot  10 , the slot  11 , the slot  12 , and the slot  13  of the first frame, a broadcast beam transmitted in the slot  1  of the second frame, and broadcast beams transmitted in the slot  10 , the slot  11 , the slot  12 , and the slot  13  of the second frame. Broadcast beams for sending no broadcast message include broadcast beams in the slot  2  and the slot  3  of the first frame, broadcast beams in the slot  15 , the slot  16 , and the slot  17  of the first frame, a broadcast beam in the slot  2  of the second frame, and broadcast beams in the slot  15 , the slot  16 , and the slot  17  of the second frame. 
     As shown in  FIG. 4C , in a second time window, the second broadcast beam group includes broadcast beams in the slot  2  and the slot  3  of the first frame, broadcast beams in the slot  15 , the slot  16 , and the slot  17  of the first frame, a broadcast beam in the slot  2  of the second frame, and broadcast beams in the slot  15 , the slot  16 , and the slot  17  of the second frame. Broadcast beams for sending no broadcast message include broadcast beams in the slot  0  and the slot  1  of the first frame, broadcast beams in the slot  10 , the slot  11 , the slot  12 , and the slot  13  of the first frame, a broadcast beam in the slot  1  of the second frame, and broadcast beams in the slot  10 , the slot  11 , the slot  12 , and the slot  13  of the second frame. 
     It can be understood that when the first broadcast beam group is transmitted in the first time window, the second broadcast beam group is shut down. When the second broadcast beam group is transmitted in the second time window, the first broadcast beam group is shut down. In this way, some broadcast beams may be shut down in each time window, and a power amplifier corresponding to the broadcast beam that is shut down stops working, thereby reducing energy consumption of the power amplifier. 
     When the downlink resource utilization falls within the second downlink resource utilization range, all the broadcast messages are divided into four broadcast message groups, and a slot occupied by each broadcast message group is shown in Table 3. 
     
       
         
           
               
               
               
               
               
               
             
               
                   
                 TABLE 3 
               
               
                   
                   
               
               
                   
                   
                 SSB 
                 SIB1 
                 OSI 
                 Paging 
               
               
                   
                   
               
             
            
               
                   
                 Slot number of a first 
                 0 
                 10, 11 
                 1 
                 10, 11 
               
               
                   
                 broadcast message group 
                   
                   
                   
                   
               
               
                   
                 Slot number of a second 
                 1 
                 12, 13 
                 2 
                 12, 13 
               
               
                   
                 broadcast message group 
                   
                   
                   
                   
               
               
                   
                 Slot number of a third 
                 2 
                 15, 16 
                   
                 15, 16 
               
               
                   
                 broadcast message group 
                   
                   
                   
                   
               
               
                   
                 Slot number of a fourth 
                 3 
                 17 
                   
                 17 
               
               
                   
                 broadcast message group 
               
               
                   
                   
               
            
           
         
       
     
     A broadcast beam (that is, a first broadcast beam group) corresponding to the first broadcast message group, a broadcast beam (that is, a second broadcast beam group) corresponding to the second broadcast message group, a broadcast beam (that is, a third broadcast beam group) corresponding to the third broadcast message group, and a broadcast beam (that is, a fourth broadcast beam group) corresponding to the fourth broadcast message group are determined. 
       FIG. 4D ,  FIG. 4E ,  FIG. 4F , and  FIG. 4G  are schematic diagrams of a slot occupied by the first broadcast message group, a slot occupied by the second broadcast message group, a slot occupied by the third broadcast message group, and a slot occupied by the fourth broadcast message group shown in Table 3, respectively. The following separately describes the broadcast beam groups based on  FIG. 4D ,  FIG. 4E ,  FIG. 4F , and  FIG. 4G . 
     As shown in  FIG. 4D , in a first time window, the first broadcast beam group includes a broadcast beam transmitted in the slot  0  of the first frame, broadcast beams transmitted in the slot  10  and the slot  11  of the first frame, a broadcast beam transmitted in the slot  1  of the second frame, and broadcast beams transmitted in the slot  10  and the slot  11  of the second frame. 
     As shown in  FIG. 4E , in a second time window, the second broadcast beam group includes a broadcast beam in the slot  1  of the first frame, broadcast beams in the slot  12  and the slot  13  of the first frame, a broadcast beam in the slot  2  of the second frame, and broadcast beams in the slot  12  and the slot  13  of the second frame. 
     As shown in  FIG. 4F , in a third time window, the third broadcast beam group includes a broadcast beam transmitted in the slot  2  of the first frame, broadcast beams transmitted in the slot  15  and the slot  16  of the first frame, and broadcast beams transmitted in the slot  15  and the slot  16  of the second frame. 
     As shown in  FIG. 4G , in a fourth time window, the fourth broadcast beam group includes a broadcast beam in the slot  3  of the first frame, a broadcast beam in the slot  17  of the first frame, and a broadcast beam in the slot  17  of the second frame. 
     When the first broadcast beam group is transmitted in the first time window, at least one of the second broadcast beam group, the third broadcast beam group, and the fourth broadcast beam group may be shut down. By analogy, when one broadcast beam group is transmitted in each time window, at least one of other broadcast beam groups may be shut down. In this way, some beams may be shut down in each time window, thereby reducing energy consumption of a power amplifier corresponding to the beam that is shut down. 
     In another example, when the quantity of access users falls within the first user quantity range, all the broadcast messages are divided into two broadcast message groups, and slots occupied by each broadcast message group are shown in Table 2. 
     When the quantity of access users falls within the second user quantity range, all the broadcast messages are divided into three broadcast message groups, and a slot occupied by each broadcast message group is shown in Table 4. 
     
       
         
           
               
               
               
               
               
             
               
                 TABLE 4 
               
               
                   
               
               
                   
                 SSB 
                 SIB1 
                 OSI 
                 Paging 
               
               
                   
               
             
            
               
                 Slot number of a first 
                 0, 1 
                 10, 11,  
                 1 
                 10, 11,  
               
               
                 broadcast message group 
                   
                 12, 13 
                   
                 12, 13 
               
               
                 Slot number of a second 
                 2 
                 15, 16 
                 2 
                 15, 16 
               
               
                 broadcast message group 
                   
                   
                   
                   
               
               
                 Slot number of a third 
                 3 
                 17 
                   
                 17 
               
               
                 broadcast message group 
               
               
                   
               
            
           
         
       
     
     Table 4 shows a case in which the slots are occupied by the three broadcast message groups. 
     A broadcast beam (that is, a first broadcast beam group) corresponding to the first broadcast message group, a broadcast beam (that is, a second broadcast beam group) corresponding to the second broadcast message group, and a broadcast beam (that is, a third broadcast beam group) corresponding to the third broadcast message group are determined. 
     When the first broadcast beam group is transmitted in a first time window, the second broadcast beam group and/or the third broadcast beam group may be shut down. By analogy, when one broadcast beam group is transmitted in each time window, at least one of other broadcast beam groups may be shut down. In this way, some broadcast beams may be shut down in each time window, and a power amplifier corresponding to the broadcast beam that is shut down stops working, thereby reducing energy consumption. 
     It should be noted that a broadcast message type and a quantity of broadcast messages included in the broadcast message group are not limited to the foregoing examples. This is not limited. In a process of obtaining through division the broadcast message groups, each broadcast message group may include more types of broadcast messages or fewer types of broadcast messages. For example, each broadcast message group may not include a paging message. Alternatively, each broadcast message group may include more or fewer broadcast messages. 
     In a scenario with a small quantity of users, because a network device continuously sends broadcast messages, a waste of network resources is caused, and a problem of a waste of energy consumption of the device exists. Another method for reducing the waste of network resources and reducing broadcast energy consumption of the network device appears in  FIG. 5 . This embodiment of a beamforming-based communication method includes the following steps. 
     Step  501 . Obtain cell information. 
     In this embodiment, the cell information includes downlink resource utilization and/or a quantity of access users. 
     Step  502 . When the cell information meets a preset low-load condition, prolong, based on the cell information, a sending periodicity of a broadcast message. 
     When the downlink resource utilization is less than a first preset threshold, the quantity of access users is less than a first preset user quantity, or both the foregoing conditions are met, it may be determined that the cell information meets the preset low-load condition. If the cell information meets the preset low-load condition, it indicates that a cell network is in a low-load state or a no-load state; and if the cell information does not meet the preset low-load condition, it indicates that the cell network is in a high-load state or a normal-load state. 
     The first preset threshold may be a ratio of a total quantity of slots occupied by a broadcast message in a time window to a total quantity of downlink slots, or a value that is set based on actual application. The value is not limited. A specific value of the first preset user quantity may be set based on actual experience, and this is not limited. 
     The broadcast message includes at least one of a synchronization signal block, a SIB1 message, OSI, or a paging message. 
     Step  503 . Send the broadcast message based on the prolonged sending periodicity. 
     A sending periodicity that is not prolonged is preset duration, and the prolonged sending periodicity is greater than the preset duration. Compared with sending the broadcast message based on the preset duration, sending the broadcast message based on the prolonged sending periodicity only requires a smaller quantity of sending times of the broadcast message. In this way, fewer broadcast beams need to be used, thereby reducing energy consumption of a network device. 
     Prolonging the sending periodicity of the broadcast message may be prolonging a sending periodicity or sending periodicities of one or more broadcast messages. The following provides detailed descriptions. 
     In an optional embodiment, the cell information is the downlink resource utilization, and the broadcast message is the synchronization signal block. 
     The prolonging, based on the cell information, a sending periodicity of a broadcast message includes: when the downlink resource utilization is less than the first preset threshold and the downlink resource utilization is greater than or equal to a second preset threshold, adjusting a sending periodicity of the synchronization signal block from the preset duration to first duration; and when the downlink resource utilization is less than the second preset threshold, adjusting the sending periodicity of the synchronization signal block from the preset duration to second duration. 
     In this embodiment, the network device presets two downlink resource utilization ranges. A first downlink resource utilization range is [the second preset threshold, the first preset threshold), and a second downlink resource utilization range is [0, the second preset threshold). The first duration is greater than the preset duration, and the second duration is greater than the first duration. 
     The network device determines, based on a preset correspondence between a downlink resource utilization range and a sending periodicity, a sending periodicity corresponding to the downlink resource utilization. 
     For example, in the preset correspondence between a downlink resource utilization range and a sending periodicity, the preset duration is 20 ms, a sending periodicity corresponding to the first downlink resource utilization range is 40 ms, and a sending periodicity corresponding to the second downlink resource utilization range is 80 ms. 
     In another example, the preset duration is 20 ms, a sending periodicity corresponding to the first downlink resource utilization range is 80 ms, and a sending periodicity corresponding to the second downlink resource utilization range is 160 ms. The preset duration may be but is not limited to 20 ms, 40 ms, 80 ms, or 160 ms. Values of the preset duration, the first duration, and the second duration are not limited to the foregoing examples. 
     For another type of broadcast message, for example, the SIB1 message, the OSI, or the paging message, a manner of prolonging, based on the cell information, a sending periodicity of the SIB1 message, a sending periodicity of the OSI, or a sending periodicity of the paging message is similar to a manner of prolonging, based on the cell information, the synchronization signal block. 
     The foregoing example shows only two downlink resource utilization ranges. Alternatively, the network device may configure more than three ranges, and then determine, based on the preset correspondence between a downlink resource utilization range and a sending periodicity, the sending periodicity corresponding to the downlink resource utilization. 
     It can be understood that there is a negative correlation between the downlink resource utilization and the sending periodicity of the broadcast message. Lower downlink resource utilization indicates a longer sending periodicity of the broadcast message and fewer broadcast beams for sending the broadcast message in each periodicity. In this way, working power amplifiers can be reduced, to reduce more energy consumption. Therefore, a method for flexibly adjusting the sending periodicity of the broadcast message based on the downlink resource utilization is provided, to meet a differentiated requirement for a communication resource and better reduce energy consumption. 
     For ease of understanding, the following describes a correspondence between a downlink resource utilization range and a sending periodicity of a SIB1 message by using an example. The network device presets two downlink resource utilization ranges. A first downlink resource utilization range is [the second preset threshold, the first preset threshold), and a second downlink resource utilization range is [0, the second preset threshold). A periodicity corresponding to the first downlink resource utilization range is 80 ms, and a periodicity corresponding to the second downlink resource utilization range is 160 ms. 
       FIG. 6A ,  FIG. 6B , and  FIG. 6C  are schematic diagrams of sending SIB1s in different sending periodicities. As shown in  FIG. 6A , when the downlink resource utilization is greater than the first preset threshold, a periodicity for sending the SIB1 by the network device is 20 ms. As shown in  FIG. 6B , when the downlink resource utilization is less than the first preset threshold and the downlink resource utilization is greater than or equal to the second preset threshold, a periodicity for sending the SIB1 by the network device is 80 ms. As shown in  FIG. 6C , when the downlink resource utilization is less than the second preset threshold, a periodicity for sending the SIB1 by the network device is 160 ms. 
     In another optional embodiment, the cell information is the quantity of access users, and the broadcast message is the synchronization signal block. 
     The prolonging, based on the cell information, a sending periodicity of a broadcast message includes: when the quantity of access users is less than the first preset user quantity and the quantity of access users is greater than or equal to a second preset user quantity, adjusting the sending periodicity of the broadcast message from preset duration to third duration, where the third duration is greater than the preset duration; and when the quantity of access users is less than the second preset user quantity, adjusting the sending periodicity of the broadcast message from the preset duration to fourth duration. The fourth duration is greater than the third duration. 
     In this embodiment, the network device presets two user quantity ranges. A first user quantity range is [the second preset threshold, the first preset threshold), and a second user quantity range is [0, the second preset threshold). 
     The network device determines, based on a preset correspondence between a user quantity range and a sending periodicity, a sending periodicity corresponding to the quantity of access users. For example, in the preset correspondence between a user quantity range and a sending periodicity, the preset duration is 20 ms, a sending periodicity corresponding to the first user quantity range is 40 ms, and a sending periodicity corresponding to the second user quantity range is 80 ms. In another example, the preset duration is 20 ms, a sending periodicity corresponding to the first user quantity range is 80 ms, and a sending periodicity corresponding to the second user quantity range is 160 ms. 
     For another type of broadcast message, for example, the SIB1 message, the OSI, or the paging message, a manner of prolonging, based on the cell information, a sending periodicity of the SIB1 message, a sending periodicity of the OSI, or a sending periodicity of the paging message is similar to a manner of prolonging, based on the cell information, the synchronization signal block. Details are not described herein again. In the foregoing example, the preset duration is 20 ms, the third duration is 40 ms or 80 ms, and the fourth duration is 80 ms or 160 ms. It may be understood that values of the preset duration, the third duration, and the fourth duration are not limited to the foregoing examples. The preset duration may be but is not limited to 20 ms, 40 ms, 80 ms, or 160 ms. 
     The foregoing example shows only two user quantity ranges. Alternatively, the network device may configure more than three user quantity ranges, and then determine, based on the preset correspondence between a user quantity range and a sending periodicity, the sending periodicity corresponding to the quantity of access users. 
     It can be understood that there is a negative correlation between the quantity of access users and the sending periodicity of the broadcast message. A smaller quantity of access users indicates a longer sending periodicity of the broadcast message and fewer broadcast beams for sending the broadcast message in each periodicity. In this way, working power amplifiers can be reduced, to reduce more energy consumption. Therefore, a method for flexibly adjusting the sending periodicity of the broadcast message based on the quantity of access users is provided, to meet a differentiated requirement for a communication resource and better reduce energy consumption. 
     In another optional embodiment, the cell information includes the downlink resource utilization and the quantity of access users, and the broadcast message is the synchronization signal block. 
     The prolonging, based on the cell information, a sending periodicity of a broadcast message includes: when the downlink resource utilization falls within a first downlink resource utilization range and the quantity of access users falls within a first user quantity range, adjusting the sending periodicity of the broadcast message from preset duration to fifth duration; and when the downlink resource utilization falls within a second downlink resource utilization range and the quantity of access users falls within a second user quantity range, adjusting the sending periodicity of the broadcast message from the preset duration to sixth duration. 
     In this embodiment, the fifth duration is greater than the preset duration, the first downlink resource utilization range is a range that is less than the first preset threshold and not less than a second preset threshold, and the first user quantity range is a range that is less than the first preset user quantity and not less than a second preset user quantity. The sixth duration is greater than the fifth duration, the second downlink resource utilization range is a range that is less than the second preset threshold, and the second user quantity range is a range that is less than the second preset user quantity. 
     A correspondence among a downlink resource utilization range, an access user quantity range, and a sending periodicity of the synchronization signal block may be shown in Table 5. 
     
       
         
           
               
               
               
             
               
                 TABLE 5 
               
               
                   
               
               
                   
                   
                 Sending periodicity 
               
               
                 Downlink resource 
                 Access user 
                 of a synchronization 
               
               
                 utilization range 
                 quantity range 
                 signal block 
               
               
                   
               
             
            
               
                 Greater than or equal 
                 Greater than or equal 
                 20 ms 
               
               
                 to a first 
                 to a first preset 
                   
               
               
                 preset threshold 
                 user quantity 
                   
               
               
                 First downlink resource 
                 First user 
                 40 ms 
               
               
                 utilization range 
                 quantity range 
                   
               
               
                 Second downlink  
                 Second user 
                 80 ms 
               
               
                 resource 
                 quantity range 
                   
               
               
                 utilization range 
               
               
                   
               
            
           
         
       
     
     In Table 5, the preset duration is 20 ms, the fifth duration is 40 ms, and the sixth duration is 80 ms. It may be understood that values of the preset duration, the fifth duration, and the sixth duration are not limited to the foregoing examples. 
     The foregoing example shows only two downlink resource utilization ranges and two user quantity ranges. Alternatively, the network device may configure more than three downlink resource utilization ranges and user quantity ranges, and then determine a corresponding sending periodicity based on a preset correspondence among a downlink resource utilization range, a user quantity range, and a sending periodicity. 
     Therefore, a method for flexibly adjusting the sending periodicity of the broadcast message based on the downlink resource utilization and the quantity of access users is provided, to meet a differentiated requirement for a communication resource and better reduce energy consumption. 
     The foregoing describes a process of periodically sending the broadcast message (for example, the OSI). However, during actual application, the network device usually sends the OSI in an on-demand sending mode. The on-demand sending mode means that after a terminal sends an OSI request, the network device broadcasts the OSI based on the OSI request. 
     As shown in  FIG. 7 , another embodiment of a beamforming-based communication method includes the following steps. 
     Step  701 . Receive, in an on-demand broadcast mode, a broadcast OSI request initiated by a terminal, and send OSI to the terminal based on the broadcast OSI request. 
     Step  702 . When a quantity of periodicities during which broadcast OSI requests sent by the terminal are continuously received in a monitoring window is greater than or equal to a first preset periodicity quantity, adjust a mode for broadcasting the OSI from the on-demand broadcast mode to a periodic broadcast mode. 
     When the quantity of periodicities during which the broadcast OSI requests sent by the terminal are continuously received in the monitoring window is greater than the first preset periodicity quantity, it indicates that a large quantity of users initiates requests in a cell. Because traffic of the cell is heavy, a network device adjusts the mode for broadcasting the OSI from the on-demand broadcast mode to the periodic broadcast mode. 
     Step  703 . Periodically broadcast the OSI in the periodic broadcast mode. 
     In this embodiment, in a heavy traffic scenario, UE does not need to send an OSI request to the network device and can directly obtain OSI by periodically monitoring the OSI. Therefore, the network device does not need to receive and process OSI requests of a large quantity of UEs, thereby reducing energy consumption of the network device. 
     In an optional embodiment, the method further includes: when a quantity of periodicities for broadcasting the OSI is greater than or equal to a second preset periodicity quantity, adjusting the mode for broadcasting the OSI from the periodic broadcast mode to the on-demand broadcast mode. Values of the first preset periodicity quantity and the second preset periodicity quantity may be set based on actual application, and this is not limited herein. 
       FIG. 8  is a schematic diagram of broadcasting OSI. In an on-demand broadcast mode, when broadcast OSI requests sent by a terminal are received in a monitoring window in n consecutive periodicities, and n is greater than a first preset periodicity quantity, a network device periodically broadcasts the OSI. After broadcasting the OSI in m consecutive periodicities, the network device may switch from a periodic broadcast mode to the on-demand broadcast mode, and the process is cyclically performed in the foregoing manner. n and m are integers greater than 1, and specific values may be set based on an actual situation. 
     A network device can implement the beamforming-based communication method in the embodiment shown in  FIG. 3  or the optional embodiment shown in  FIG. 9 . This embodiment of a network device includes: 
     a processing module  901 , configured to obtain cell information, where 
     the processing module  901  is further configured to: when the cell information meets a preset low-load condition, divide, based on the cell information, to-be-processed broadcast messages into a plurality of broadcast message groups, where each broadcast message group corresponds to one time window, and a length of each time window is equal to a synchronization signal sending periodicity; and 
     the processing module  901  is further configured to determine, based on a preset correspondence between a broadcast message and a broadcast beam, a broadcast beam group corresponding to each broadcast message group and a broadcast beam for sending no broadcast message in each time window; and 
     a sending module  902 , configured to send a broadcast message group in each time window by using the broadcast beam group, where 
     the processing module  901  is further configured to shut down, in each time window, the broadcast beam for sending no broadcast message. 
     In an optional embodiment, the cell information is downlink resource utilization; and 
     the processing module  901  is further configured to: when the downlink resource utilization is less than a first preset threshold, determine that the cell information meets the preset low-load condition. 
     Optionally, the processing module  901  is configured to: when the downlink resource utilization is less than the first preset threshold and the downlink resource utilization is greater than or equal to a second preset threshold, divide the to-be-processed broadcast messages into a first quantity of broadcast message groups; and 
     when the downlink resource utilization is less than the second preset threshold, divide the to-be-processed broadcast messages into a second quantity of broadcast message groups, where both the first quantity and the second quantity are positive integers greater than 1, the first quantity is less than the second quantity, and the second quantity is less than or equal to a total quantity of broadcast beams configured for a cell. 
     In another optional embodiment, the cell information is a quantity of access users; and 
     the processing module  901  is further configured to: when the quantity of access users is less than a first preset user quantity, determine that the cell information meets the preset low-load condition. 
     Optionally, the processing module  901  is further configured to: when the quantity of access users is less than the first preset user quantity and the quantity of access users is greater than or equal to a second preset user quantity, divide the to-be-processed broadcast messages into a third quantity of broadcast message groups; and 
     when the quantity of access users is less than the second preset user quantity, divide the to-be-processed broadcast messages into a fourth quantity of broadcast message groups, where both the third quantity and the fourth quantity are positive integers greater than 1, the third quantity is less than the fourth quantity, and the fourth quantity is less than or equal to a total quantity of broadcast beams configured for a cell. 
     In another optional embodiment, 
     the cell information includes downlink resource utilization and a quantity of access users; and 
     the processing module  901  is further configured to: when the downlink resource utilization is less than a first preset threshold and the quantity of access users is less than a first preset user quantity, determine that the cell information meets the preset low-load condition. 
     Optionally, the processing module  901  is further configured to: when the downlink resource utilization falls within a first downlink resource utilization range and the quantity of access users falls within a first user quantity range, divide the to-be-processed broadcast messages into a fifth quantity of broadcast message groups, where the first downlink resource utilization range is a range that is less than the first preset threshold and not less than a second preset threshold, and the first user quantity range is a range that is less than the first preset user quantity and not less than a second preset user quantity; and 
     when the downlink resource utilization falls within a second downlink resource utilization range and the quantity of access users falls within a second user quantity range, divide the to-be-processed broadcast messages into a sixth quantity of broadcast message groups, where both the fifth quantity and the sixth quantity are positive integers greater than 1, the fifth quantity is less than the sixth quantity, and the sixth quantity is less than or equal to a total quantity of broadcast beams configured for a cell. The second downlink resource utilization range is a range that is less than the second preset threshold, and the second user quantity range is a range that is less than the second preset user quantity. 
     In the embodiment shown in  FIG. 9  or the optional embodiment, the broadcast message includes at least one of a synchronization signal block, a SIB1 message, OSI, or a paging message. 
     A network device can implement the beamforming-based communication method in the embodiment shown in  FIG. 5  or the optional embodiment shown in  FIG. 10 . This embodiment of a network device includes: 
     a processing module  1001 , configured to obtain cell information, where 
     the processing module  1001  is further configured to: when the cell information meets a preset low-load condition, prolong, based on the cell information, a sending periodicity of a broadcast message; and 
     a sending module  1002 , configured to send the broadcast message based on the prolonged sending periodicity. 
     In an optional embodiment, the cell information is downlink resource utilization; and 
     the processing module  1001  is further configured to: when the downlink resource utilization is less than a first preset threshold, determine that the cell information meets the preset low-load condition. 
     Optionally, the processing module  1001  is configured to: when the downlink resource utilization is less than the first preset threshold and the downlink resource utilization is greater than or equal to a second preset threshold, adjust the sending periodicity of the broadcast message from preset duration to first duration, where the first duration is greater than the preset duration; and 
     when the downlink resource utilization is less than the second preset threshold, adjust the sending periodicity of the broadcast message from the preset duration to second duration, where the second duration is greater than the first duration. 
     In another optional embodiment, the cell information is a quantity of access users; and 
     the processing module  1001  is further configured to: when the quantity of access users is less than a first preset user quantity, determine that the cell information meets the preset low-load condition. 
     Optionally, the processing module  1001  is configured to: when the quantity of access users is less than the first preset user quantity and the quantity of access users is greater than or equal to a second preset user quantity, adjust the sending periodicity of the broadcast message from preset duration to third duration, where the third duration is greater than the preset duration; and 
     when the quantity of access users is less than the second preset user quantity, adjust the sending periodicity of the broadcast message from the preset duration to fourth duration, where the fourth duration is greater than the third duration. 
     In another optional embodiment, 
     the cell information includes downlink resource utilization and a quantity of access users; and 
     the processing module  1001  is further configured to: when the downlink resource utilization is less than a first preset threshold and the quantity of access users is less than a first preset user quantity, determine that the cell information meets the preset low-load condition. 
     Optionally, the processing module  1001  is configured to: when the downlink resource utilization falls within a first downlink resource utilization range and the quantity of access users falls within a first user quantity range, adjust the sending periodicity of the broadcast message from preset duration to fifth duration, where the fifth duration is greater than the preset duration, the first downlink resource utilization range is a range that is less than the first preset threshold and not less than a second preset threshold, and the first user quantity range is a range that is less than the first preset user quantity and not less than a second preset user quantity; and 
     when the downlink resource utilization falls within a second downlink resource utilization range and the quantity of access users falls within a second user quantity range, adjust the sending periodicity of the broadcast message from the preset duration to sixth duration, where the sixth duration is greater than the fifth duration, the second downlink resource utilization range is a range that is less than the second preset threshold, and the second user quantity range is a range that is less than the second preset user quantity. 
     In the embodiment shown in  FIG. 10  or the optional embodiment, the broadcast message includes at least one of a synchronization signal block, a SIB1 message, OSI, or a paging message. 
     A network device can implement the beamforming-based communication method in the embodiment shown in  FIG. 7  or the optional embodiment shown in  FIG. 11 . This embodiment of a network device includes a receiving module  1101 , a processing module  1102 , and a sending module  1103 . 
     The receiving module  1101  is configured to receive, in an on-demand broadcast mode, a broadcast other system information OSI request initiated by a terminal. 
     The sending module  1103  is configured to send OSI to the terminal based on the broadcast OSI request. 
     The processing module  1102  is configured to: when a quantity of periodicities during which broadcast OSI requests sent by the terminal are continuously received in a monitoring window is greater than a first preset periodicity quantity, adjust a mode for broadcasting the OSI from the on-demand broadcast mode to a periodic broadcast mode. 
     The sending module  1103  is further configured to periodically broadcast the OSI in the periodic broadcast mode. 
     In an optional embodiment, 
     the processing module  1102  is further configured to: when a quantity of periodicities for broadcasting the OSI is greater than or equal to a second preset periodicity quantity, adjust the mode for broadcasting the OSI from the periodic broadcast mode to the on-demand broadcast mode. 
     A computer storage medium stores instructions. When the instructions are run on a computer, the computer is enabled to perform the beamforming-based communication method in the foregoing embodiment. 
     All or some of the foregoing embodiments may be implemented by using software, hardware, firmware, or any combination thereof. When the software is used to implement the embodiments, all or some of the embodiments may be implemented in a form of a computer program product. 
     The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the procedures or the functions according to the embodiments are all or partially generated. The computer may be a general-purpose computer, a dedicated computer, a computer network, or another programmable apparatus. The computer instructions may be stored in a computer-readable storage medium or may be transmitted from a computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions may be transmitted from a website, a computer, a server, or a data center to another website, computer, server, or data center in a wired (for example, a coaxial cable, an optical fiber, or a digital subscriber line (DSL)) or wireless (for example, infrared, radio, and microwave) manner. The computer-readable storage medium may be any usable medium accessible by a computer, or a data storage device, for example, a server or a data center, integrating one or more usable media. The usable medium may be a magnetic medium (for example, a floppy disk, a hard disk, or a magnetic tape), an optical medium (for example, a DVD), a semiconductor medium (for example, a solid state drive (SSD)), or the like. 
     The foregoing embodiments are merely intended for describing the solutions of the embodiments, and should not be considered as limiting. Although the embodiments are described in detail, a person of ordinary skill may still make modifications to the solutions described in the foregoing embodiments or make equivalent replacements to some features thereof, without departing from the scope of the embodiments.