Patent Publication Number: US-2023155616-A1

Title: Downlink transmitting system and switching method

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of International Application No. PCT/CN2021/104770, filed on Jul. 6, 2021, which claims priority to Chinese Patent Application No. 202010716226.7, filed on Jul. 23, 2020. The disclosures of the aforementioned applications are herein incorporated by reference in their entireties. 
    
    
     TECHNICAL FIELD 
     This application relates to the communication field, and more specifically, to a downlink transmitting system and a switching method. 
     BACKGROUND 
     A massive multiple-input multiple-output (Massive MIMO) technology is a key technology of a current 5th generation (5G) mobile communication system. In this technology, a large-scale antenna array is deployed on a network device to improve a system throughput. However, because a massive MIMO device uses a large quantity of transceiver units (TRxs) (for example, 32 TRxs or 64 TRxs are used), energy consumption of the network device increases sharply. Particularly, when load of the network device is low, enabling of a large quantity of transmit (Tx) channels makes an energy efficiency ratio of the network device significantly lower than an energy efficiency ratio of the network device with medium and high load. 
     Currently, in an architecture of a downlink transmitting system using digital beamforming (DBF), when the load of the network device is low, a part of Tx channels are disabled to save energy. However, in this manner, in a process of disabling the part of Tx channels, the Tx channels are also disconnected from a part of the antenna array. In this case, a scale of the antenna array is reduced. Furthermore, reduction in the scale of the antenna array causes damage to an aperture of the antenna array and reduction in an effective isotropic radiated power (EIRP) of the network device. Consequently, performance and coverage of the network device are reduced to different extent. 
     In an architecture of a downlink transmitting system using hybrid beamforming (HBF), a quantity of Tx channels is reduced to save energy. However, when the load of the network device is high or a vertical distribution spacing between users relative to a ground is large, performance of the architecture of the downlink transmitting system using HBF is significantly poorer than performance of the architecture of the downlink transmitting system using DBF. 
     SUMMARY 
     This application provides a downlink transmitting system, which can support switching between different connection states, so as to adapt to different application scenarios. 
     According to a first aspect, a downlink transmitting system is provided and includes at least one digital intermediate frequency module group, at least one Tx port group, a plurality of power amplifiers (PAs), at least one switching switch, and an antenna array. The plurality of PAs are connected to the antenna array. The plurality of PAs are connected to all Tx ports included in the downlink transmitting system in a one-to-one correspondence. The at least one digital intermediate frequency module group is in a one-to-one correspondence with the at least one Tx port group. Each Tx port group is connected to each digital intermediate frequency module in a corresponding digital intermediate frequency module group through one switching switch. Each Tx port group includes a plurality of Tx ports. A quantity of digital intermediate frequency modules included in each digital intermediate frequency module group is equal to a quantity of Tx ports included in a corresponding Tx port group. Each switching switch includes at least two connection states. Quantities of enabled digital intermediate frequency modules in a digital intermediate frequency module group connected to the switching switch in different connection states are different. All Tx ports in a Tx port group connected to the switching switch in the different connection states are in an enabled state. 
     Based on the foregoing downlink transmitting system, each switching switch includes the at least two connection states, and the quantities of enabled digital intermediate frequency modules in the digital intermediate frequency module group connected to the switching switch in the different connection states are different. Therefore, when a quantity of enabled digital intermediate frequency modules is small, the foregoing transmitting system can achieve an effect of energy saving, and is applicable to a scenario in which network load is low. When all digital intermediate frequency modules are enabled or the quantity of enabled digital intermediate frequency modules is large, the foregoing transmitting system is applicable to a scenario in which the network load is high. In addition, regardless of the quantity of enabled digital intermediate frequency modules in the downlink transmitting system, all the Tx ports in the downlink transmitting system are in an enabled state. Therefore, PAs connected to all the Tx ports are also in an enabled state. In this way, a scale of the antenna array connected to all PAs is not reduced, and performance of the downlink transmitting system is not affected. 
     With reference to the first aspect, in some implementations of the first aspect, the at least two connection states include a first connection state and a second connection state, and a quantity of enabled digital intermediate frequency modules in the first connection state is greater than a quantity of enabled digital intermediate frequency modules in the second connection state. When a connection state of a first switching switch is the first connection state, a plurality of Tx ports in a first Tx port group are connected to a plurality of digital intermediate frequency modules in a first digital intermediate frequency module group in a one-to-one correspondence, the first Tx port group and the first digital intermediate frequency module group are connected through the first switching switch, and the first switching switch is any one of the at least one switching switch. When the connection state of the first switching switch is the second connection state, at least one first digital intermediate frequency module port in the first digital intermediate frequency module group is connected to at least two Tx ports in the first Tx port group, and at least one second digital intermediate frequency module in the first digital intermediate frequency module group is not connected to all Tx ports in the first Tx port group. 
     With reference to the first aspect, in some implementations of the first aspect, a connection state of at least one of the at least one switching switch is the first connection state when a first condition is met, and the first condition includes at least one of the following conditions: A quantity of users served by the downlink transmitting system is greater than or equal to a first threshold; and a vertical spacing between at least two of the users relative to a ground is greater than or equal to a second threshold. 
     With reference to the first aspect, in some implementations of the first aspect, a connection state of at least one of the at least one switching switch is the second connection state when a second condition is met, and the second condition is as follows: A quantity of users served by the downlink transmitting system is less than a first threshold, and a vertical spacing between any two of the users relative to a ground is less than a second threshold. 
     With reference to the first aspect, in some implementations of the first aspect, the downlink transmitting system further includes a baseband processor, and the baseband processor is configured to control a connection state of each of the at least one switching switch. 
     With reference to the first aspect, in some implementations of the first aspect, the switching switch is a bridge. 
     With reference to the first aspect, in some implementations of the first aspect, the downlink transmitting system further includes a plurality of phase shifters, and the plurality of phase shifters are connected to all the Tx ports included in the downlink transmitting system in a one-to-one correspondence. 
     Based on the foregoing downlink transmitting system, the phase shifter may perform analog weighting between different antenna bays included in the antenna array. Therefore, coverage of a vertical beam of the downlink transmitting system can be expanded. 
     According to a second aspect, a downlink transmitting system is provided and includes: at least one Tx channel group, at least one PA group, at least one switching switch, and an antenna array. The at least one PA group is connected to the antenna array. The at least one Tx channel group is in a one-to-one correspondence with the at least one PA group. Each Tx channel group is connected to each PA in a corresponding PA group through one switching switch. Each Tx channel group includes a plurality of Tx channels. Each Tx channel includes a Tx port and a digital intermediate frequency module. A quantity of PAs included in each PA group is equal to a quantity of Tx channels included in a corresponding Tx channel group. Each switching switch includes at least two connection states. Quantities of enabled Tx channels in a Tx channel group connected to the switching switch in different connection states are different. All PAs in a PA group connected to the switching switch in the different connection states are in an enabled state. 
     Based on the foregoing downlink transmitting system, each switching switch includes the at least two connection states, and the quantities of enabled Tx channels in the Tx channel group connected to the switching switch in the different connection states are different. Therefore, when a quantity of enabled Tx channels is small, the foregoing transmitting system can achieve an effect of energy saving, and is applicable to a scenario in which network load is low. When all Tx channels are enabled or the quantity of enabled Tx channels is large, the foregoing transmitting system is applicable to a scenario in which the network load is high. In addition, regardless of the quantity of enabled Tx channels in the downlink transmitting system, all PAs in the downlink transmitting system are in an enabled state. Therefore, a scale of the antenna array connected to all the PAs is not reduced, and performance of the downlink transmitting system is not affected. 
     With reference to the second aspect, in some implementations of the second aspect, the at least two connection states include a first connection state and a second connection state, and a quantity of enabled Tx channels in the first connection state is greater than a quantity of enabled Tx channels in the second connection state. When a connection state of a first switching switch is the first connection state, a plurality of Tx channels in a first Tx channel group are connected to a plurality of PAs in a first PA group in a one-to-one correspondence, the first Tx channel group and the first PA group are connected through the first switching switch, and the first switching switch is any one of the at least one switching switch. When the connection state of the first switching switch is the second connection state, at least one first Tx channel in the first Tx channel group is connected to at least two PAs in the first PA group, and at least one second Tx channel in the first Tx channel group is not connected to all PAs in the first PA group. 
     With reference to the second aspect, in some implementations of the second aspect, a connection state of at least one of the at least one switching switch is the first connection state when a first condition is met, and the first condition includes at least one of the following conditions: A quantity of users served by the downlink transmitting system is greater than or equal to a first threshold; and a vertical spacing between at least two of the users relative to a ground is greater than or equal to a second threshold. 
     With reference to the second aspect, in some implementations of the second aspect, a connection state of at least one of the at least one switching switch is the second connection state when a second condition is met, and the second condition is as follows: A quantity of users served by the downlink transmitting system is less than a first threshold, and a vertical spacing between any two of the users relative to a ground is less than a second threshold. 
     With reference to the second aspect, in some implementations of the second aspect, the downlink transmitting system further includes a baseband processor, and the baseband processor is configured to control a connection state of each of the at least one switching switch. 
     With reference to the second aspect, in some implementations of the second aspect, the switching switch is a bridge. 
     With reference to the second aspect, in some implementations of the second aspect, the downlink transmitting system further includes a plurality of phase shifters, and the plurality of phase shifters are connected to all the PAs included in the downlink transmitting system in a one-to-one correspondence. 
     Based on the foregoing downlink transmitting system, the phase shifter may perform analog weighting between different antenna bays included in the antenna array. Therefore, coverage of a vertical beam of the downlink transmitting system can be expanded. 
     According to a third aspect, a downlink transmitting system is provided and includes: a plurality of Tx channels, at least one PA group, at least one switching switch, and an antenna array. The plurality of Tx channels are connected to all PAs included in the downlink transmitting system in a one-to-one correspondence. The antenna array includes at least one antenna bay group. The at least one PA group is in a one-to-one correspondence with the at least one antenna bay group. Each PA group is connected to each antenna bay in a corresponding antenna bay group through one switching switch. Each PA group includes a plurality of PAs. A quantity of PAs included in each PA group is equal to a quantity of antenna bays included in a corresponding antenna bay group. Each switching switch includes at least two connection states. Quantities of enabled PAs in a PA group connected to the switching switch in different connection states are different. All antenna bays in an antenna bay group connected to the switching switch in the different connection states are in an enabled state. 
     Based on the foregoing downlink transmitting system, each switching switch includes the at least two connection states, and the quantities of enabled PAs in the PA group connected to the switching switch in the different connection states are different. In other words, quantities of enabled Tx channels connected to the PAs in a one-to-one correspondence are different. Therefore, when a quantity of enabled PAs is small, in other words, when a quantity of enabled Tx channels is small, the foregoing transmitting system can achieve an effect of energy saving, and is applicable to a scenario in which network load is low. When all PAs are enabled or the quantity of enabled PAs is large, in other words, when all Tx channels are enabled or the quantity of enabled Tx channels is large, the foregoing transmitting system is applicable to a scenario in which the network load is high. In addition, regardless of the quantity of enabled PAs in the downlink transmitting system, all antenna bays in the downlink transmitting system are in an enabled state. Therefore, a scale of the antenna array is not reduced, and performance of the downlink transmitting system is not affected. 
     With reference to the third aspect, in some implementations of the third aspect, the at least two connection states include a first connection state and a second connection state, and a quantity of enabled PAs in the first connection state is greater than a quantity of enabled PAs in the second connection state. When a connection state of a first switching switch is the first connection state, a plurality of PAs in a first PA group are connected to a plurality of antenna bays in a first antenna bay group in a one-to-one correspondence, the first PA group and the first antenna bay group are connected through the first switching switch, and the first switching switch is any one of the at least one switching switch. When the connection state of the first switching switch is the second connection state, at least one first PA in the first PA group is connected to at least two antenna bays in the first antenna bay group, and at least one second PA in the first PA group is not connected to all antenna bays in the first antenna bay group. 
     With reference to the third aspect, in some implementations of the third aspect, a connection state of at least one of the at least one switching switch is the first connection state when a first condition is met, and the first condition includes at least one of the following conditions: A quantity of users served by the downlink transmitting system is greater than or equal to a first threshold; and a vertical spacing between at least two of the users relative to a ground is greater than or equal to a second threshold. 
     With reference to the third aspect, in some implementations of the third aspect, a connection state of at least one of the at least one switching switch is the second connection state when a second condition is met, and the second condition is as follows: A quantity of users served by the downlink transmitting system is less than a first threshold, and a vertical spacing between any two of the users relative to a ground is less than a second threshold. 
     With reference to the third aspect, in some implementations of the third aspect, the downlink transmitting system further includes a baseband processor, and the baseband processor is configured to control a connection state of each of the at least one switching switch. 
     With reference to the third aspect, in some implementations of the third aspect, the switching switch is a bridge. 
     With reference to the third aspect, in some implementations of the third aspect, the downlink transmitting system further includes a plurality of phase shifters, and the plurality of phase shifters are connected to a plurality of antenna bays included in the downlink transmitting system in a one-to-one correspondence. 
     Based on the foregoing downlink transmitting system, the phase shifter may perform analog weighting between different antenna bays included in the antenna array. Therefore, coverage of a vertical beam of the downlink transmitting system can be expanded. 
     According to a fourth aspect, a switching method is provided and applied to a downlink transmitting system. The downlink transmitting system includes: at least one digital intermediate frequency module group, at least one Tx port group, a plurality of PAs, at least one switching switch, and an antenna array. The plurality of PAs are connected to the antenna array. The plurality of PAs are connected to all Tx ports included in the at least one Tx port group in a one-to-one correspondence. The at least one digital intermediate frequency module group is in a one-to-one correspondence with the at least one Tx port group. Each Tx port group is connected to each digital intermediate frequency module in a corresponding digital intermediate frequency module group through one switching switch. Each Tx port group includes a plurality of Tx ports. A quantity of digital intermediate frequency modules included in each digital intermediate frequency module group is equal to a quantity of Tx ports included in a corresponding Tx port group. Each switching switch includes at least two connection states. Quantities of enabled digital intermediate frequency modules in a digital intermediate frequency module group connected to the switching switch in different connection states are different. All Tx ports in a Tx port group connected to the switching switch in the different connection states are in an enabled state. 
     The method includes: controlling a connection state of the at least one switching switch based on a quantity of served users and a vertical spacing between different users relative to a ground. 
     With reference to the fourth aspect, in some implementations of the fourth aspect, the at least two connection states include a first connection state and a second connection state, and a quantity of enabled digital intermediate frequency modules in the first connection state is greater than a quantity of enabled digital intermediate frequency modules in the second connection state. When a connection state of a first switching switch is the first connection state, a plurality of Tx ports in a first Tx port group are connected to a plurality of digital intermediate frequency modules in a first digital intermediate frequency module group in a one-to-one correspondence, the first Tx port group and the first digital intermediate frequency module group are connected through the first switching switch, and the first switching switch is any one of the at least one switching switch. When the connection state of the first switching switch is the second connection state, at least one first digital intermediate frequency module in the first digital intermediate frequency module group is connected to at least two Tx ports in the first Tx port group, and at least one second digital intermediate frequency module in the first digital intermediate frequency module group is not connected to all Tx ports in the first Tx port group. 
     With reference to the fourth aspect, in some implementations of the fourth aspect, the controlling a connection state of the at least one switching switch based on a quantity of served users and a vertical spacing between different users relative to a ground includes: when a first condition is met, controlling a connection state of at least one of the at least one switching switch to be the first connection state. The first condition includes at least one of the following conditions: The quantity of users served by the downlink transmitting system is greater than or equal to a first threshold; and a vertical spacing between at least two of the users relative to the ground is greater than or equal to a second threshold. 
     With reference to the fourth aspect, in some implementations of the fourth aspect, the controlling a connection state of the at least one switching switch based on a quantity of served users and a spacing between different users includes: when a second condition is met, controlling a connection state of at least one of the at least one switching switch to be the second connection state. The second condition is as follows: The quantity of users served by the downlink transmitting system is less than a first threshold, and a vertical spacing between any two of the users relative to the ground is less than a second threshold. 
     With reference to the fourth aspect, in some implementations of the fourth aspect, the method further includes: determining the quantity of users and the vertical spacing between the different users relative to the ground based on a received channel state information beam identifier. 
     According to a fifth aspect, a switching method is provided and applied to a downlink transmitting system. The downlink transmitting system includes: at least one Tx channel group, at least one PA group, at least one switching switch, and an antenna array. The at least one PA group is connected to the antenna array. The at least one Tx channel group is in a one-to-one correspondence with the at least one PA group. Each Tx channel is connected to each PA in a corresponding PA group through one switching switch. Each Tx channel group includes a plurality of Tx channels. Each Tx channel includes a Tx port and a digital intermediate frequency module. A quantity of PAs included in each PA group is equal to a quantity of Tx channels included in a corresponding Tx channel group. Each switching switch includes at least two connection states. Quantities of enabled Tx channels in a Tx channel group connected to the switching switch in different connection states are different. All PAs in a PA group connected to the switching switch in the different connection states are in an enabled state. 
     The method includes: controlling a connection state of the at least one switching switch based on a quantity of served users and a vertical spacing between different users relative to a ground. 
     With reference to the fifth aspect, in some implementations of the fifth aspect, the at least two connection states include a first connection state and a second connection state, and a quantity of enabled Tx channels in the first connection state is greater than a quantity of enabled Tx channels in the second connection state. When a connection state of a first switching switch is the first connection state, a plurality of Tx channels in a first Tx channel group are connected to a plurality of PAs in a first PA group in a one-to-one correspondence, the first Tx channel group and the first PA group are connected through the first switching switch, and the first switching switch is any one of the at least one switching switch. When the connection state of the first switching switch is the second connection state, at least one first Tx channel in the first Tx channel group is connected to at least two PAs in the first PA group, and at least one second Tx channel in the first Tx channel group is not connected to all PAs in the first PA group. 
     With reference to the fifth aspect, in some implementations of the fifth aspect, the controlling a connection state of the at least one switching switch based on a quantity of served users and a vertical spacing between different users relative to a ground includes: when a first condition is met, controlling a connection state of at least one of the at least one switching switch to be the first connection state. The first condition includes at least one of the following conditions: The quantity of users served by the downlink transmitting system is greater than or equal to a first threshold; and a vertical spacing between at least two of the users relative to the ground is greater than or equal to a second threshold. 
     With reference to the fifth aspect, in some implementations of the fifth aspect, the controlling a connection state of the at least one switching switch based on a quantity of served users and a spacing between different users includes: when a second condition is met, controlling a connection state of at least one of the at least one switching switch to be the second connection state. The second condition is as follows: The quantity of users served by the downlink transmitting system is less than a first threshold, and a vertical spacing between any two of the users relative to the ground is less than a second threshold. 
     With reference to the fifth aspect, in some implementations of the fifth aspect, the method further includes: determining the quantity of users and the vertical spacing between the different users relative to the ground based on a received channel state information beam identifier. 
     According to a sixth aspect, a switching method is provided and applied to a downlink transmitting system. The downlink transmitting system includes: a plurality of Tx channels, at least one PA group, at least one switching switch, and an antenna array. The antenna array includes at least one antenna bay group. The at least one PA group is in a one-to-one correspondence with the at least one antenna bay group. Each PA group is connected to each antenna bay in a corresponding antenna bay group through one switching switch. Each PA group includes a plurality of PAs. A quantity of PAs included in each PA group is equal to a quantity of antenna bays included in a corresponding antenna bay group. Each switching switch includes at least two connection states. Quantities of enabled PAs in a PA group connected to the switching switch in different connection states are different. All antenna bays in an antenna bay group connected to the switching switch in the different connection states are in an enabled state. 
     The method includes: controlling a connection state of the at least one switching switch based on a quantity of served users and a vertical spacing between different users relative to a ground. 
     With reference to the sixth aspect, in some implementations of the sixth aspect, the at least two connection states include a first connection state and a second connection state, and a quantity of enabled PAs in the first connection state is greater than a quantity of enabled PAs in the second connection state. When a connection state of a first switching switch is the first connection state, a plurality of PAs in a first PA group are connected to a plurality of antenna bays in a first antenna bay group in a one-to-one correspondence, the first PA group and the first antenna bay group are connected through the first switching switch, and the first switching switch is any one of the at least one switching switch. When the connection state of the first switching switch is the second connection state, at least one first PA in the first PA group is connected to at least two antenna bays in the first antenna bay group, and at least one second PA in the first PA group is not connected to all antenna bays in the first antenna bay group. 
     With reference to the sixth aspect, in some implementations of the sixth aspect, the controlling a connection state of the at least one switching switch based on a quantity of served users and a vertical spacing between different users relative to a ground includes: when a first condition is met, controlling a connection state of at least one of the at least one switching switch to be the first connection state. The first condition includes at least one of the following conditions: The quantity of users served by the downlink transmitting system is greater than or equal to a first threshold; and a vertical spacing between at least two of the users relative to the ground is greater than or equal to a second threshold. 
     With reference to the sixth aspect, in some implementations of the sixth aspect, the controlling a connection state of the at least one switching switch based on a quantity of served users and a spacing between different users includes: when a second condition is met, controlling a connection state of at least one of the at least one switching switch to be the second connection state. The second condition is as follows: The quantity of users served by the downlink transmitting system is less than a first threshold, and a vertical spacing between any two of the users relative to the ground is less than a second threshold. 
     With reference to the sixth aspect, in some implementations of the sixth aspect, the method further includes: determining the quantity of users and the vertical spacing between the different users relative to the ground based on a received channel state information beam identifier. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    is a schematic diagram of a structure of a downlink transmitting system using DBF; 
         FIG.  2    is a schematic diagram of a structure of a downlink transmitting system using HBF; and 
         FIG.  3    to  FIG.  28    are schematic diagrams of structures of downlink transmitting systems according to embodiments of this application. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     The following describes technical solutions of this application with reference to accompanying drawings. 
     A massive multiple-input multiple-output (Massive MIMO) technology is a key technology of a current 5th generation (5G) mobile communication system. In this technology, a large-scale antenna array is deployed on a network device to improve a system throughput. However, because a massive MIMO device uses a large quantity of transceiver units (TRxs) (for example, 32 TRxs or 64 TRxs are used), energy consumption of the network device increases sharply. Particularly, when load of the network device is low, enabling of a large quantity of transmit (Tx) channels makes an energy efficiency ratio of the network device significantly lower than an energy efficiency ratio of the network device with medium and high load. 
       FIG.  1    shows an architecture of a downlink transmitting system using digital beamforming (DBF). As shown in  FIG.  1   , when load of a network device is low, a part of Tx channels may be disabled to save energy. For example, in  FIG.  1   , a Tx channel may be disabled by disconnecting a Tx  3  from an intermediate frequency (namely, a digital intermediate frequency module, which is denoted as an intermediate frequency below)  3  and a power amplifier (PA)  3 , and another Tx channel may be disabled by disconnecting a Tx  4  from an intermediate frequency  4  and a PA  4 . 
     As shown in  FIG.  1   , in a process of disabling the part of Tx channels, the Tx channels are also disconnected from a part of an antenna array. In this case, a scale of the antenna array is reduced. Furthermore, reduction in the scale of the antenna array causes damage to an aperture of the antenna array and reduction in an effective isotropic radiated power (EIRP) of the network device. Consequently, performance and coverage of the network device are reduced to different extent. 
       FIG.  2    shows an architecture of a downlink transmitting system using hybrid beamforming (HBF). Compared with the architecture of the downlink transmitting system using DBF shown in  FIG.  1   , for the architecture of the downlink transmitting system using HBF shown in  FIG.  2   , a quantity of Tx channels and a quantity of PAs are reduced by half. Correspondingly, for a vertical array driven by one Tx channel and one PA, that 1 channel drives 3 antenna elements is changed to that 1 channel drives 6 antenna elements. To be specific, as shown in FIG. 2, a quantity of rows of an antenna array connected to one Tx channel and one PA is increased from 3 to 6. 
     In the architecture of the downlink transmitting system using HBF shown in  FIG.  2   , because the quantity of Tx channels is reduced, an effect of energy saving is achieved to some extent when load of a network device is low, and a loss of performance is small. However, when the load of the network device is high or a vertical distribution spacing between users relative to a ground is large, the performance of the architecture of the downlink transmitting system using HBF is significantly poorer than performance of the architecture of the downlink transmitting system using DBF. 
     In view of this, an embodiment of this application provides a downlink transmitting system. The downlink transmitting system can adjust a quantity of Tx channels based on an application scenario, without causing damage to an aperture of an antenna array. 
     The following describes the technical solutions of this application with reference to the accompanying drawings. 
     In embodiments shown below, “first”, “second”, “third” and various numbers are merely used for distinguishing for ease of description, and are not used to limit the scope of embodiments of this application. For example, the numbers are used to distinguish between different PAs, different phase shifters, and the like. In addition, “including” and “having” and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units further includes another inherent step or unit. 
     The technical solutions in embodiments of this application may be applied to various communication systems, such as a long term evolution (LTE) system, an LTE frequency division duplex (FDD) system, an LTE time division duplex (TDD) system, a universal mobile telecommunication system (UMTS), a worldwide interoperability for microwave access (WiMAX) communication system, a 5th generation (5G) mobile communication system or a new radio access technology (NR) system, a 6th generation (6G) mobile communication system, or a future evolved communication system. The 5G mobile communication system may include a non-standalone (NSA) communication system and/or a standalone (SA) communication system. 
       FIG.  3    is a schematic diagram of a structure of a downlink transmitting system  300  according to an embodiment of this application. The downlink transmitting system  300  may include: at least one Tx channel group (for example, a Tx channel group  361  and a Tx channel group  362  in  FIG.  3   ), at least one PA group (for example, a PA group  331  and a PA group  332  in  FIG.  3   ), at least one switching switch (for example, a switching switch  321  and a switching switch  322  in  FIG.  3   ), and an antenna array  350 . 
     The antenna array  350  may include a plurality of antenna bays (for example, an antenna bay  351  to an antenna bay  354  in  FIG.  3   ). A quantity of rows of antenna elements included in each antenna bay is not limited in this embodiment of this application. For example, the antenna bay  351  includes three rows of antenna elements, and an antenna bay  352  includes two rows of antenna elements. 
     The at least one PA group is connected to the antenna array  350 , and each PA in all PAs included in the at least one PA group is connected to one antenna bay in the antenna array  350 . For example, in  FIG.  3   , a PA  3311  is connected to the antenna bay  351 , and a PA  3312  is connected to the antenna bay  352 . A PA  3321  is connected to an antenna bay  353 , and a PA  3322  is connected to the antenna bay  354 . 
     Each Tx channel may include an intermediate frequency and a Tx port. For example, in  FIG.  3   , a 1 st  Tx channel may include an intermediate frequency  1  and a Tx port  1 , a 2 nd  Tx channel may include an intermediate frequency  2  and a Tx port  2 , a 3 rd  Tx channel may include an intermediate frequency  3  and a Tx port  3 , and a 4 th  Tx channel may include an intermediate frequency  4  and a Tx port  4 . 
     The at least one Tx channel group is in a one-to-one correspondence with the at least one PA group, and each Tx channel group is connected to each PA in a corresponding PA group through one switching switch. For example, in  FIG.  3   , the Tx channel group  361  corresponds to the PA group  331 , and the Tx channel group  361  is connected to each PA in the PA group  331  through the switching switch  321 . The Tx channel group  362  corresponds to the PA group  332 , and the Tx channel group  362  is connected to each PA in the PA group  332  through the switching switch  322 . 
     Each of the at least one Tx channel group includes a plurality of Tx channels, and a quantity of Tx channels included in each Tx channel group is equal to a quantity of PAs included in a corresponding PA group. 
     For example, in  FIG.  3   , the Tx channel group  361  and the Tx channel group  362  each include 2 Tx channels, a quantity of Tx channels included in the Tx channel group  361  and a quantity of PAs included in the PA group  331  are both 2, and a quantity of Tx channels included in the Tx channel group  362  and a quantity of PAs included in the PA group  332  are both 2. 
     For another example, in  FIG.  4   , a quantity of Tx channels included in a Tx channel group  363  is 4, and the quantity of Tx channels included in the Tx channel group  363  and a quantity of PAs included in a PA group  333  are both 4. 
     Optionally, each of the at least one Tx channel group may include a same quantity of Tx channels. For example, in  FIG.  3   , the quantity of Tx channels included in the Tx channel group  361  and the quantity of Tx channels included in the Tx channel group  362  are both 2. 
     Optionally, each of the at least one Tx channel group may include a different quantity of Tx channels. For example, in  FIG.  5   , a quantity of Tx channels included in a Tx channel group  361  is 2, but a quantity of Tx channels included in a Tx channel group  363  is 4. 
     Each of the at least one switching switch includes at least two connection states, and quantities of enabled Tx channels in a Tx channel group connected to the switching switch in different connection states are different. In other words, the downlink transmitting system  300  includes the at least two connection states. 
     The at least two connection states may include a first connection state and a second connection state, and a quantity of enabled Tx channels in the first connection state is greater than a quantity of enabled Tx channels in the second connection state. 
     When a connection state of a first switching switch is the first connection state, a plurality of Tx channels in a first Tx channel group are connected to a plurality of PAs in a first PA group in a one-to-one correspondence, the first Tx channel group and the first PA group are connected through the first switching switch, and the first switching switch is any one of the at least one switching switch. 
     For example, in  FIG.  3   , the first switching switch may be the switching switch  321 , the first Tx channel group is the Tx channel group  361 , and the first PA group is the PA group  331 . When a connection state of the switching switch  321  is the first connection state, two Tx channels in the Tx channel group  361  are connected to two PAs in the PA group  331  in a one-to-one correspondence. To be specific, the 1 st  Tx channel is correspondingly connected to the PA  3311 , and the 2 nd  Tx channel is correspondingly connected to the PA  3312 . Alternatively, the first switching switch may be the switching switch  322 , the first Tx channel group is the Tx channel group  362 , and the first PA group is the PA group  332 . When a connection state of the switching switch  322  is the first connection state, two Tx channels in the Tx channel group  362  are connected to two PAs in the PA group  332  in a one-to-one correspondence. To be specific, the 3 rd  Tx channel is correspondingly connected to the PA  3321 , and the 4 th  Tx channel is correspondingly connected to the PA  3322 . 
     For example, in  FIG.  4   , the first switching switch may be a switching switch  323 , the first Tx channel group is the Tx channel group  363 , and the first PA group is the PA group  333 . When a connection state of the switching switch  323  is the first connection state, four Tx channels in the Tx channel group  363  are connected to four PAs in the PA group  333  in a one-to-one correspondence. To be specific, a 1 st  Tx channel is correspondingly connected to a PA  3331 , a 2 nd  Tx channel is correspondingly connected to a PA  3332 , a 3 rd  Tx channel is correspondingly connected to a PA  3333 , and a 4 th  Tx channel is correspondingly connected to a PA  3334 . 
     If connection states of all switching switches in the at least one switching switch are the first connection state, it may be considered that the downlink transmitting system  300  is in the first connection state. It can be learned that downlink transmitting systems  300  shown in  FIG.  3    to  FIG.  5    are in the first connection state. 
     When the connection state of the first switching switch is the second connection state, at least one first Tx channel in the first Tx channel group is connected to at least two PAs in the first PA group, and at least one second Tx channel in the first Tx channel group is not connected to all PAs in the first PA group. It may be understood that, when the second Tx channel is not connected to all the PAs in the first PA group, the second Tx channel is in a disabled state. 
     For example, in  FIG.  6   , the first switching switch may be a switching switch  321 , the first Tx channel group is a Tx channel group  361 , the first PA group is a PA group  331 , the first Tx channel is a 1 st  Tx channel, and the second Tx channel is a 2 nd  Tx channel. When a connection state of the switching switch  321  is the second connection state, the 1 st  Tx channel is connected to two PAs (namely, a PA  3311  and a PA  3312 ) in the PA group  331 , and the 2 nd  Tx channel is in a disabled state. Alternatively, the first switching switch may be a switching switch  322 , the first Tx channel group is a Tx channel group  362 , the first PA group is a PA group  332 , the first Tx channel is a 3 rd  Tx channel, and the second Tx channel is a 4 th  Tx channel. When a connection state of the switching switch  322  is the second connection state, the 3 rd  Tx channel is connected to two PAs (namely, a PA  3321  and a PA  3322 ) in the PA group  332 , and the 4 th  Tx channel is in a disabled state. 
     For example, in  FIG.  7   , the first switching switch may be a switching switch  323 , the first Tx channel group is a Tx channel group  363 , the first PA group is a PA group  333 , the first Tx channel is a 1 st  Tx channel, and the second Tx channel is a 2 nd  Tx channel to a 4 th  Tx channel. When a connection state of the switching switch  323  is the second connection state, the 1 st  Tx channel is connected to four PAs (namely, a PA  3331  to a PA  3334 ) in the PA group  333 , and the 2 nd  Tx channel to the 4 th  Tx channel are in a disabled state. 
     For example, in  FIG.  8   , the first switching switch may be a switching switch  323 , the first Tx channel group is a Tx channel group  363 , the first PA group is a PA group  333 , the first Tx channel is a 1 st  Tx channel, and the second Tx channel is a 2 nd  Tx channel and a 3 rd  Tx channel. When a connection state of the switching switch  323  is the second connection state, the 1 st  Tx channel is connected to three PAs (namely, a PA  3331  to a PA  3333 ) in the PA group  333 , the 2 nd  Tx channel and the 3 rd  Tx channel are in a disabled state, and a 4 th  Tx channel may still be connected to a PA  3334 . 
     If a connection state of at least one of the at least one switching switch is the second connection state, it may be considered that the downlink transmitting system  300  is in the second connection state. It can be learned that downlink transmitting systems  300  shown in  FIG.  6    to  FIG.  8    are in the second connection state. 
     As shown in  FIG.  3    to  FIG.  8   , the downlink transmitting system  300  may further include a baseband processor  310  (for example, may be a baseband lower (BBL)), and a connection state of each of the at least one switching switch may be controlled by the baseband processor. For example, the baseband processor may control the connection state of the switching switch based on a quantity of users served by the downlink transmitting system  300  and a vertical spacing between different users relative to a ground. 
     For example, when a first condition is met, the baseband processor controls the connection state of the at least one of the at least one switching switch to be the first connection state, where the first condition includes at least one of the following conditions: 
     The quantity of users served by the downlink transmitting system  300  is greater than or equal to a first threshold; and 
     a vertical spacing between at least two of the users served by the downlink transmitting system  300  relative to the ground is greater than or equal to a second threshold. 
     For another example, when a second condition is met, the baseband processor controls the connection state of the at least one of the at least one switching switch to be the second connection state, where the second condition is as follows: 
     The quantity of users served by the downlink transmitting system  300  is less than a first threshold, and a vertical spacing between any two of the users served by the downlink transmitting system  300  relative to the ground is less than a second threshold. 
     Optionally, when the second condition is met, the baseband processor is further configured to determine whether the users are distributed within coverage of the downlink transmitting system in the second connection state. If the users are distributed within the coverage of the downlink transmitting system in the second connection state, the baseband processor controls the connection state of the at least one of the at least one switching switch to be the second connection state. Alternatively, if the users are distributed outside the coverage of the downlink transmitting system in the second connection state, the baseband processor controls the connection state of the at least one of the at least one switching switch to be the first connection state. 
     For example, with reference to the downlink transmitting systems  300  shown in  FIG.  3    and  FIG.  6    (where a quantity of Tx channels included in each Tx channel group and a quantity of PAs included in each PA group are both 2), if the downlink transmitting system  300  includes 64 Tx channels, the downlink transmitting system  300  in the first connection state may be referred to as 64 DBF. If a connection state of each switching switch in the downlink transmitting system  300  is the second connection state, a quantity of enabled Tx channels is 32, and the downlink transmitting system  300  in the second connection state may be referred to as 32 DBF. Therefore, when the second condition is met, the baseband processor is further configured to determine whether the users are distributed within coverage of the 32 DBF. If the users (for example, 3 rd  and 4 th  users counted from top to bottom in  FIG.  6   ) are distributed within the coverage of the 32 DBF, the baseband processor controls the switching switch to enable the downlink transmitting system  300  to be in the second connection state. If the users (for example, 1 st  and 2 nd  users counted from top to bottom in  FIG.  6   ) are not distributed within the coverage of the 32 DBF, the baseband processor controls the switching switch to enable the downlink transmitting system  300  to be in the first connection state. 
     A method for determining, by the baseband processor, the quantity of users served by the downlink transmitting system  300  and the spacing between the different users is not limited in this embodiment of this application. For example, the baseband processor may determine the quantity of users and the spacing between the different users based on a received channel state information (CSI) beam identifier (ID). 
     It should be understood that  FIG.  3    to  FIG.  8    are merely examples, and show four or six Tx channels, four or six PAs, and one or two switching switches. Optionally, the downlink transmitting system  300  may include K Tx channels, K PAs, and L switching switches, where K is an integer greater than 1, and L is a positive integer. 
     Optionally, as shown in  FIG.  9    and  FIG.  10   , the downlink transmitting system  300  may further include a plurality of phase shifters (a phase shifter  341  to a phase shifter  344  in  FIG.  9    and  FIG.  10   ). The plurality of phase shifters are connected to all PAs included in the at least one PA group in a one-to-one correspondence. For example, in  FIG.  9    and  FIG.  10   , a PA  3311  is correspondingly connected to the phase shifter  341 , a PA  3312  is correspondingly connected to a phase shifter  342 , a PA  3321  is correspondingly connected to a phase shifter  343 , and a PA  3322  is correspondingly connected to the phase shifter  344 . The phase shifter may be located between the PA and the switching switch (as shown in  FIG.  9   ), or may be located between the PA and the antenna array (as shown in  FIG.  10   ). This is not limited in this embodiment of this application. 
     It should be understood that, when the downlink transmitting system  300  includes the phase shifters, because the phase shifters may adjust a phase of a beam, that is, may adjust a direction of the beam, even if the downlink transmitting system  300  is in the second connection state, the downlink transmitting system  300  may adjust coverage by using the phase shifters. Therefore, when the downlink transmitting system  300  includes the phase shifters, the baseband processor does not need to determine whether the users are distributed within the coverage of the downlink transmitting system in the second connection state. In other words, when determining that the second condition is met, the baseband processor may control the switching switch to enable the downlink transmitting system  300  to be in the second connection state. 
       FIG.  11    is a schematic diagram of a structure of another downlink transmitting system  400  according to an embodiment of this application. The downlink transmitting system  400  may include: at least one Tx port group (for example, a Tx port group  441  and a Tx port group  442  in  FIG.  11   ), at least one digital intermediate frequency module group (where a digital intermediate frequency module is denoted as an intermediate frequency below) (for example, an intermediate frequency group  421  and an intermediate frequency group  422  in  FIG.  11   ), at least one switching switch (for example, a switching switch  431  and a switching switch  432  in  FIG.  11   ), a plurality of PAs (for example, a PA  451  to a PA  454  in  FIG.  11   ), and an antenna array  460 . 
     The antenna array  460  may include a plurality of antenna bays (for example, an antenna bay  461  to an antenna bay  464  in  FIG.  11   ). A quantity of rows of antenna elements included in each antenna bay is not limited in this embodiment of this application. For example, the antenna bay  461  includes three rows of antenna elements, and an antenna bay  462  includes two rows of antenna elements. 
     The plurality of PAs are connected to the antenna array  460 , and each PA in the plurality of PAs is connected to one antenna bay in the antenna array  460 . For example, in  FIG.  11   , the PA  451  is connected to the antenna bay  461 , and a PA  452  is connected to the antenna bay  462 . A PA  453  is connected to an antenna bay  463 , and the PA  454  is connected to the antenna bay  464 . 
     The plurality of PAs are connected to all Tx ports included in the at least one Tx port group in a one-to-one correspondence. For example, in  FIG.  11   , the PA  451  is connected to a Tx port  1 , the PA  452  is connected to a Tx port  2 , the PA  453  is connected to a Tx port  3 , and the PA  454  is connected to a Tx port  4 . 
     The at least one Tx port group is in a one-to-one correspondence with the at least one intermediate frequency group, and each Tx port group is connected to each intermediate frequency in a corresponding intermediate frequency group through one switching switch. For example, in  FIG.  11   , the Tx port group  441  corresponds to the intermediate frequency group  421 , and the Tx port group  441  is connected to each intermediate frequency in the intermediate frequency group  421  through the switching switch  431 . The Tx port group  442  corresponds to the intermediate frequency group  422 , and the Tx port group  442  is connected to each intermediate frequency in the intermediate frequency group  422  through the switching switch  432 . 
     Each of the at least one Tx port group includes a plurality of Tx ports, and a quantity of Tx ports included in each Tx port group is equal to a quantity of intermediate frequencies included in a corresponding intermediate frequency group. 
     For example, in  FIG.  11   , the Tx port group  441  and the Tx port group  442  each include 2 Tx ports, a quantity of Tx ports included in the Tx port group  441  and a quantity of intermediate frequencies included in the intermediate frequency group  421  are both 2, and a quantity of Tx ports included in the Tx port group  442  and a quantity of intermediate frequencies included in the intermediate frequency group  422  are both 2. 
     For another example, in  FIG.  12   , a quantity of Tx ports included in a Tx port group  443  is 4, and the quantity of Tx ports included in the Tx port group  443  and a quantity of intermediate frequencies included in an intermediate frequency group  423  are both 4. 
     Optionally, each of the at least one Tx port group may include a same quantity of Tx ports. For example, in  FIG.  11   , the quantity of Tx ports included in the Tx port group  441  and the quantity of Tx ports included in the Tx port group  442  are both 2. 
     Optionally, each of the at least one Tx port group may include a different quantity of Tx ports. For example, in  FIG.  13   , a quantity of Tx ports included in a Tx port group  441  is 2, but a quantity of Tx ports included in a Tx port group  443  is 4. 
     Each of the at least one switching switch includes at least two connection states, and quantities of enabled intermediate frequencies in an intermediate frequency group connected to the switching switch in different connection states are different. In other words, the downlink transmitting system  400  includes the at least two connection states. 
     The at least two connection states may include a first connection state and a second connection state, and a quantity of enabled intermediate frequencies in the first connection state is greater than a quantity of enabled intermediate frequencies in the second connection state. 
     When a connection state of a first switching switch is the first connection state, a plurality of Tx ports in a first Tx port group are connected to a plurality of intermediate frequencies in a first intermediate frequency group in a one-to-one correspondence, the first Tx port group and the first intermediate frequency group are connected through the first switching switch, and the first switching switch is any one of the at least one switching switch. 
     For example, in  FIG.  11   , the first switching switch may be the switching switch  431 , the first Tx port group is the Tx port group  441 , and the first intermediate frequency group is the intermediate frequency group  421 . When a connection state of the switching switch  431  is the first connection state, two Tx ports in the Tx port group  441  are connected to two intermediate frequencies in the intermediate frequency group  421  in a one-to-one correspondence. To be specific, the Tx port  1  is correspondingly connected to an intermediate frequency  1 , and the Tx port  2  is correspondingly connected to an intermediate frequency  2 . Alternatively, the first switching switch may be the switching switch  432 , the first Tx port group is the Tx port group  442 , and the first intermediate frequency group is the intermediate frequency group  422 . When a connection state of the switching switch  432  is the first connection state, two Tx ports in the Tx port group  442  are connected to two intermediate frequencies in the intermediate frequency group  422  in a one-to-one correspondence. To be specific, the Tx port  3  is correspondingly connected to an intermediate frequency  3 , and the Tx port  4  is correspondingly connected to an intermediate frequency  4 . 
     For example, in  FIG.  12   , the first switching switch may be a switching switch  433 , the first Tx port group is the Tx port group  443 , and the first intermediate frequency group is the intermediate frequency group  423 . When a connection state of the switching switch  433  is the first connection state, four Tx ports in the Tx port group  443  are connected to four intermediate frequencies in the intermediate frequency group  423  in a one-to-one correspondence. To be specific, a Tx port  1  is correspondingly connected to an intermediate frequency  1 , a Tx port  2  is correspondingly connected to an intermediate frequency  2 , a Tx port  3  is correspondingly connected to an intermediate frequency  3 , and a Tx port  4  is correspondingly connected to an intermediate frequency  4 . 
     If connection states of all switching switches in the at least one switching switch are the first connection state, it may be considered that the downlink transmitting system  400  is in the first connection state. It can be learned that downlink transmitting systems  400  shown in  FIG.  11    to  FIG.  13    are in the first connection state. 
     When the connection state of the first switching switch is the second connection state, at least one first intermediate frequency in the first intermediate frequency group is connected to at least two Tx ports in the first Tx port group, and at least one second intermediate frequency in the first intermediate frequency group is not connected to all Tx ports in the first Tx port group. It may be understood that, when the second intermediate frequency is not connected to all the Tx ports in the first Tx port group, the second intermediate frequency is in a disabled state. 
     For example, in  FIG.  14   , the first switching switch may be a switching switch  431 , the first Tx port group is a Tx port group  441 , the first intermediate frequency group is an intermediate frequency group  421 , the first intermediate frequency is an intermediate frequency  1 , and the second intermediate frequency is an intermediate frequency  2 . When a connection state of the switching switch  431  is the second connection state, the intermediate frequency  1  is connected to two Tx ports (namely, a Tx port  1  and a Tx port  2 ) in the Tx port group  441 , and the intermediate frequency  2  is in a disabled state. Alternatively, the first switching switch may be a switching switch  432 , the first Tx port group is a Tx port group  442 , the first intermediate frequency group is an intermediate frequency group  422 , the first intermediate frequency is an intermediate frequency  3 , and the second intermediate frequency is an intermediate frequency  4 . When a connection state of the switching switch  432  is the second connection state, the intermediate frequency  3  is connected to two Tx ports (namely, a Tx port  3  and a Tx port  4 ) in the Tx port group  442 , and the intermediate frequency  4  is in a disabled state. 
     For example, in  FIG.  15   , the first switching switch may be a switching switch  433 , the first Tx port group is a Tx port group  443 , the first intermediate frequency group is an intermediate frequency group  423 , the first intermediate frequency is an intermediate frequency  1 , and the second intermediate frequency is an intermediate frequency  2  to an intermediate frequency  4 . When a connection state of the switching switch  433  is the second connection state, the intermediate frequency  1  is connected to four Tx ports (namely, a Tx port  1  to a Tx port  4 ) in the Tx port group  443 , and the intermediate frequency  2  to the intermediate frequency  4  are in a disabled state. 
     For example, in  FIG.  16   , the first switching switch may be a switching switch  433 , the first Tx port group is a Tx port group  443 , the first intermediate frequency group is an intermediate frequency group  423 , the first intermediate frequency is an intermediate frequency  1 , and the second intermediate frequency is an intermediate frequency  2  and an intermediate frequency  3 . When a connection state of the switching switch  433  is the second connection state, the intermediate frequency  1  is connected to three Tx ports (namely, a Tx port  1  to a Tx port  3 ) in the Tx port group  443 , the intermediate frequency  2  and the intermediate frequency  3  are in a disabled state, and a Tx port  4  may still be connected to an intermediate frequency  4 . 
     If a connection state of at least one of the at least one switching switch is the second connection state, it may be considered that the downlink transmitting system  400  is in the second connection state. It can be learned that downlink transmitting systems  400  shown in  FIG.  14    to  FIG.  16    are in the second connection state. 
     As shown in  FIG.  11    to  FIG.  16   , the downlink transmitting system  400  may further include a baseband processor  410  (for example, may be a BBL), and a connection state of each of the at least one switching switch may be controlled by the baseband processor. For example, the baseband processor may control the connection state of the switching switch based on a quantity of users served by the downlink transmitting system  400  and a vertical spacing between different users relative to a ground. 
     For example, when a first condition is met, the baseband processor controls the connection state of the at least one of the at least one switching switch to be the first connection state, where the first condition includes at least one of the following conditions: 
     The quantity of users served by the downlink transmitting system  400  is greater than or equal to a first threshold; and 
     a vertical spacing between at least two of the users served by the downlink transmitting system  400  relative to the ground is greater than or equal to a second threshold. 
     For another example, when a second condition is met, the baseband processor controls the connection state of the at least one of the at least one switching switch to be the second connection state, where the second condition is as follows: 
     The quantity of users served by the downlink transmitting system  400  is less than a first threshold, and a vertical spacing between any two of the users served by the downlink transmitting system  400  relative to the ground is less than a second threshold. 
     Optionally, when the second condition is met, the baseband processor is further configured to determine whether the users are distributed within coverage of the downlink transmitting system in the second connection state. If the users are distributed within the coverage of the downlink transmitting system in the second connection state, the baseband processor controls the connection state of the at least one of the at least one switching switch to be the second connection state. Alternatively, if the users are distributed outside the coverage of the downlink transmitting system in the second connection state, the baseband processor controls the connection state of the at least one of the at least one switching switch to be the first connection state. 
     For example, with reference to the downlink transmitting systems  400  shown in  FIG.  11    and  FIG.  14    (where a quantity of Tx ports included in each Tx port group and a quantity of intermediate frequencies included in each intermediate frequency group are both 2), if the downlink transmitting system  400  includes 64 Tx ports, the downlink transmitting system  400  in the first connection state may be referred to as 64 DBF. If a connection state of each switching switch in the downlink transmitting system  400  is the second connection state, a quantity of enabled intermediate frequencies is 32, and the downlink transmitting system  400  in the second connection state may be referred to as 32 DBF. Therefore, when the second condition is met, the baseband processor is further configured to determine whether the users are distributed within coverage of the 32 DBF. If the users (for example, 3 rd  and 4 th  users counted from top to bottom in  FIG.  14   ) are distributed within the coverage of the 32 DBF, the baseband processor controls the switching switch to enable the downlink transmitting system  400  to be in the second connection state. If the users (for example, 1 st  and 2 nd  users counted from top to bottom in  FIG.  14   ) are not distributed within the coverage of the 32 DBF, the baseband processor controls the switching switch to enable the downlink transmitting system  400  to be in the first connection state. 
     A method for determining, by the baseband processor, the quantity of users served by the downlink transmitting system  400  and the vertical spacing between the different users relative to the ground is not limited in this embodiment of this application. For example, the baseband processor may determine the quantity of users and the vertical spacing between the different users relative to the ground based on a received CSI beam ID. 
     It should be understood that  FIG.  11    to  FIG.  16    are merely examples, and show four or six Tx ports, four or six intermediate frequencies, four or six PAs, and one or two switching switches. Optionally, the downlink transmitting system  400  may include K Tx ports, K intermediate frequencies, K PAs, and L switching switches, where K is an integer greater than 1, and L is a positive integer. 
     Optionally, as shown in  FIG.  17   , the downlink transmitting system  400  may further include a plurality of phase shifters (for example, a phase shifter  471  to a phase shifter  474  in  FIG.  17   ). The plurality of phase shifters are connected to a plurality of Tx ports in a one-to-one correspondence. For example, in  FIG.  17   , a Tx port  1  is correspondingly connected to the phase shifter  471 , a Tx port  2  is correspondingly connected to a phase shifter  472 , a Tx port  3  is correspondingly connected to a phase shifter  473 , and a Tx port  4  is correspondingly connected to the phase shifter  474 . 
     It should be understood that, when the downlink transmitting system  400  includes the phase shifters, because the phase shifters may adjust a phase of a beam, that is, may adjust a direction of the beam, even if the downlink transmitting system  400  is in the second connection state, the downlink transmitting system  400  may adjust coverage by using the phase shifters. Therefore, when the downlink transmitting system  400  includes the phase shifters, the baseband processor does not need to determine whether the users are distributed within the coverage of the downlink transmitting system in the second connection state. In other words, when determining that the second condition is met, the baseband processor may control the switching switch to enable the downlink transmitting system  400  to be in the second connection state. 
       FIG.  18    is a schematic diagram of a structure of another downlink transmitting system  500  according to an embodiment of this application. The downlink transmitting system  500  may include: a plurality of Tx channels, at least one PA group (for example, a PA group  521  and a PA group  522  in  FIG.  18   ), at least one antenna bay group (for example, an antenna bay group  541  and an antenna bay group  542  in  FIG.  18   ), and at least one switching switch (for example, a switching switch  531  and a switching switch  532  in  FIG.  18   ). 
     Each Tx channel may include an intermediate frequency and a Tx port. For example, in  FIG.  18   , a 1 st  Tx channel may include an intermediate frequency  1  and a Tx port  1 , a 2 nd  Tx channel may include an intermediate frequency  2  and a Tx port  2 , a 3 rd  Tx channel may include an intermediate frequency  3  and a Tx port  3 , and a 4 th  Tx channel may include an intermediate frequency  4  and a Tx port  4 . 
     The at least one PA group is in a one-to-one correspondence with the at least one antenna bay group, and each PA group is connected to each antenna bay in a corresponding antenna bay group through one switching switch. For example, in  FIG.  18   , the PA group  521  corresponds to the antenna bay group  541 , and the PA group  521  is connected to each antenna bay in the antenna bay group  541  through the switching switch  531 . The PA group  522  corresponds to the antenna bay group  542 , and the PA group  522  is connected to each antenna bay in the antenna bay group  542  through the switching switch  532 . 
     Each of the at least one PA group includes a plurality of PAs, and a quantity of PAs included in each PA group is equal to a quantity of antenna bays included in a corresponding antenna bay group. 
     For example, in  FIG.  18   , the PA group  521  and the PA group  522  each include two PAs, a quantity of PAs included in the PA group  521  and a quantity of antenna bays included in the antenna bay group  541  are both 2, and a quantity of PAs included in the PA group  522  and a quantity of antenna bays included in the antenna bay group  542  are both 2. 
     For another example, in  FIG.  19   , a quantity of PAs included in a PA group  523  is 4, and the quantity of PAs included in the PA group  523  and a quantity of antenna bays included in an antenna bay group  543  are both 4. 
     Optionally, each of the at least one PA group may include a same quantity of PAs. For example, in  FIG.  18   , the quantity of PAs included in the PA group  521  and the quantity of PAs included in the PA group  522  are both 2. 
     Optionally, each of the at least one PA group may include a different quantity of PAs. For example, in  FIG.  20   , a quantity of PAs included in a PA group  521  is 2, but a quantity of PAs included in a PA group  523  is 4. 
     A quantity of rows of antenna elements included in each antenna bay is not limited in this embodiment of this application. For example, in  FIG.  18   , an antenna bay  5411  includes three rows of antenna elements, and an antenna bay  5412  includes two rows of antenna elements. 
     Each of the at least one switching switch includes at least two connection states, and quantities of enabled PAs in a PA group connected to the switching switch in different connection states are different. In other words, the downlink transmitting system  500  includes the at least two connection states. It may be understood that, in the downlink transmitting system  500 , a plurality of Tx channels are connected to a plurality of PAs in a one-to-one correspondence. Therefore, in the different connection states, quantities of enabled Tx channels in the downlink transmitting system  500  are different. 
     The at least two connection states may include a first connection state and a second connection state, and a quantity of enabled PAs in the first connection state is greater than a quantity of enabled PAs in the second connection state. In other words, a quantity of enabled Tx channels in the first connection state is greater than a quantity of enabled Tx channels in the second connection state. 
     When a connection state of a first switching switch is the first connection state, a plurality of PAs in a first PA group are connected to a plurality of antenna bays in a first antenna bay group in a one-to-one correspondence, the first PA group and the first antenna bay group are connected through the first switching switch, and the first switching switch is any one of the at least one switching switch. 
     For example, in  FIG.  18   , the first switching switch may be the switching switch  531 , the first PA group is the PA group  521 , and the first antenna bay group is the antenna bay group  541 . When a connection state of the switching switch  531  is the first connection state, two PAs in the PA group  521  are connected to two antenna bays in the antenna bay group  541  in a one-to-one correspondence. To be specific, a PA  5211  is correspondingly connected to the antenna bay  5411 , and a PA  5212  is correspondingly connected to the antenna bay  5412 . Alternatively, the first switching switch may be the switching switch  532 , the first PA group is the PA group  522 , and the first antenna bay group is the antenna bay group  542 . When a connection state of the switching switch  532  is the first connection state, two PAs in the PA group  522  are connected to two antenna bays in the antenna bay group  542  in a one-to-one correspondence. To be specific, a PA  5221  is correspondingly connected to an antenna bay  5421 , and a PA  5222  is correspondingly connected to an antenna bay  5422 . 
     For example, in  FIG.  19   , the first switching switch may be a switching switch  533 , the first PA group is the PA group  523 , and the first antenna bay group is the antenna bay group  543 . When a connection state of the switching switch  533  is the first connection state, four PAs in the PA group  523  are connected to four antenna bays in the antenna bay group  543  in a one-to-one correspondence. To be specific, a PA  5231  is correspondingly connected to an antenna bay  5431 , a PA  5232  is correspondingly connected to an antenna bay  5432 , a PA  5233  is correspondingly connected to an antenna bay  5433 , and a PA  5234  is correspondingly connected to an antenna bay  5434 . 
     If connection states of all switching switches in the at least one switching switch are the first connection state, it may be considered that the downlink transmitting system  500  is in the first connection state. It can be learned that downlink transmitting systems  500  shown in  FIG.  18    to  FIG.  20    are in the first connection state. 
     When the connection state of the first switching switch is the second connection state, at least one first PA in the first PA group is connected to at least two antenna bays in the first antenna bay group, and at least one second PA in the first PA group is not connected to all antenna bays in the first antenna bay group. It may be understood that, when the second PA is not connected to all the antenna bays in the first antenna bay group, the second PA is in a disabled state. It may be understood that, when the second PA is in the disabled state, a Tx channel connected to the second PA is also in a disabled state. 
     For example, in  FIG.  21   , the first switching switch may be a switching switch  531 , the first PA group is a PA group  521 , the first antenna bay group is an antenna bay group  541 , the first PA is a PA  5211 , and the second PA is a PA  5212 . When a connection state of the switching switch  531  is the second connection state, the PA  5211  is connected to two antenna bays (namely, an antenna bay  5411  and an antenna bay  5422 ) in the antenna bay group  541 , the PA  5212  is in a disabled state, and correspondingly, a second Tx channel connected to the PA  5212  is also in a disabled state. Alternatively, the first switching switch may be a switching switch  532 , the first PA group is a PA group  522 , the first antenna bay group is an antenna bay group  542 , the first PA is a PA  5221 , and the second PA is a PA  5222 . When a connection state of the switching switch  532  is the second connection state, the PA  5221  is connected to two antenna bays (namely, an antenna bay  5421  and an antenna bay  5422 ) in the antenna bay group  542 , the PA  5222  is in a disabled state, and a fourth Tx channel connected to the PA  5222  is also in a disabled state correspondingly. 
     For example, in  FIG.  22   , the first switching switch may be a switching switch  533 , the first antenna bay group is an antenna bay group  543 , the first PA group is a PA group  523 , the first PA is a PA  5231 , and the second PA is a PA  5232  to a PA  5234 . When a connection state of the switching switch  533  is the second connection state, the PA  5231  is connected to four antenna bays (namely, an antenna bay  5431  to an antenna bay  5434 ) in the antenna bay group  543 , the PA  5232  to the PA  5234  are in a disabled state, and, a second Tx channel to a fourth Tx channel that are respectively connected to the PA  5232  to the PA  5234  are also in a disabled state correspondingly. 
     For example, in  FIG.  23   , the first switching switch may be a switching switch  533 , the first antenna bay group is an antenna bay group  543 , the first PA group is a PA group  523 , the first PA is a PA  5231 , and the second PA is a PA  5232  and a PA  5233 . When a connection state of the switching switch  533  is the second connection state, the PA  5231  is connected to three antenna bays (namely, an antenna bay  5431  to an antenna bay  5433 ) in the antenna bay group  543 , the PA  5232  and the PA  5233  are in a disabled state, a second Tx channel and a third Tx channel that are respectively connected to the PA  5232  and the PA  5233  are also in a disabled state correspondingly, and a PA  5234  may still be connected to an antenna bay  5434 . 
     If a connection state of at least one of the at least one switching switch is the second connection state, it may be considered that the downlink transmitting system  500  is in the second connection state. It can be learned that downlink transmitting systems  500  shown in  FIG.  21    to  FIG.  23    are in the second connection state. 
     As shown in  FIG.  18    to  FIG.  23   , the downlink transmitting system  500  may further include a baseband processor  510  (for example, may be a BBL), and a connection state of each of the at least one switching switch may be controlled by the baseband processor. For example, the baseband processor may control the connection state of the switching switch based on a quantity of users served by the downlink transmitting system  500  and a vertical spacing between different users relative to a ground. 
     For example, when a first condition is met, the baseband processor controls the connection state of the at least one of the at least one switching switch to be the first connection state, where the first condition includes at least one of the following conditions: 
     The quantity of users served by the downlink transmitting system  500  is greater than or equal to a first threshold; and 
     a vertical spacing between at least two of the users served by the downlink transmitting system  500  relative to the ground is greater than or equal to a second threshold. 
     For another example, when a second condition is met, the baseband processor controls the connection state of the at least one of the at least one switching switch to be the second connection state, where the second condition is as follows: 
     The quantity of users served by the downlink transmitting system  500  is less than a first threshold, and a vertical spacing between any two of the users served by the downlink transmitting system  500  relative to the ground is less than a second threshold. 
     Optionally, when the second condition is met, the baseband processor is further configured to determine whether the users are distributed within coverage of the downlink transmitting system in the second connection state. If the users are distributed within the coverage of the downlink transmitting system in the second connection state, the baseband processor controls the connection state of the at least one of the at least one switching switch to be the second connection state. Alternatively, if the users are distributed outside the coverage of the downlink transmitting system in the second connection state, the baseband processor controls the connection state of the at least one of the at least one switching switch to be the first connection state. 
     For example, with reference to the downlink transmitting system  500  shown in  FIG.  18    and  FIG.  21    (where a quantity of PAs included in each PA group and a quantity of antenna bays included in each antenna bay group are both 2), if the downlink transmitting system  500  includes 64 PAs (in other words, includes 64 Tx channels), the downlink transmitting system  500  in the first connection state may be referred to as 64 DBF. If a connection state of each switching switch in the downlink transmitting system  500  is the second connection state, a quantity of enabled PAs is 32 (in other words, a quantity of enabled Tx channels is 32), and the downlink transmitting system  500  in the second connection state may be referred to as 32 DBF. Therefore, when the second condition is met, the baseband processor is further configured to determine whether the users are distributed within coverage of the 32 DBF. If the users (for example, 3 rd  and 4 th  users counted from top to bottom in  FIG.  21   ) are distributed within the coverage of the 32 DBF, the baseband processor controls the switching switch to enable the downlink transmitting system  500  to be in the second connection state. If the users (for example, 1 st  and 2 nd  users counted from top to bottom in  FIG.  21   ) are not distributed within the coverage of the 32 DBF, the baseband processor controls the switching switch to enable the downlink transmitting system  500  to be in the first connection state. 
     A method for determining, by the baseband processor, the quantity of users served by the downlink transmitting system  500  and the vertical spacing between the different users relative to the ground is not limited in this embodiment of this application. For example, the baseband processor may determine the quantity of users and the vertical spacing between the different users relative to the ground based on a received CSI beam ID. 
     It should be understood that  FIG.  18    to  FIG.  23    are merely examples, and show four or six antenna bays, four or six PAs, and one or two switching switches. Optionally, the downlink transmitting system  500  may include K antenna bays, K PAs, and L switching switches, where K is an integer greater than 1, and L is a positive integer. 
     Optionally, as shown in  FIG.  24   , the downlink transmitting system  500  may further include a plurality of phase shifters (for example, a phase shifter  551  to a phase shifter  554  in  FIG.  24   ). The plurality of phase shifters are connected to a plurality of antenna bays in a one-to-one correspondence. For example, in  FIG.  24   , an antenna bay  5411  is correspondingly connected to the phase shifter  551 , an antenna bay  5412  is correspondingly connected to a phase shifter  552 , an antenna bay  5421  is correspondingly connected to a phase shifter  553 , and an antenna bay  5422  is correspondingly connected to the phase shifter  554 . 
     It should be understood that, when the downlink transmitting system  500  includes the phase shifters, because the phase shifters may adjust a phase of a beam, that is, may adjust a direction of the beam, even if the downlink transmitting system  500  is in the second connection state, the downlink transmitting system  500  may adjust coverage by using the phase shifters. Therefore, when the downlink transmitting system  500  includes the phase shifters, the baseband processor does not need to determine whether the users are distributed within the coverage of the downlink transmitting system in the second connection state. In other words, when determining that the second condition is met, the baseband processor may control the switching switch to enable the downlink transmitting system  500  to be in the second connection state. 
     A structure and a type of a switching switch are not limited in embodiments of this application. In the following embodiment, a downlink transmitting system  300  is used as an example to describe the structure and the type of the switching switch provided in embodiments of this application. In the following embodiments, an example in which each Tx channel group includes two Tx channels and each PA group includes two PAs is used for description. 
     In an implementation, the switching switch may be a bridge. 
     For example, in a downlink transmitting system  300  shown in  FIG.  25    and  FIG.  26   , a Tx channel group  361  and a PA group  331  are connected through a bridge  321 , and a Tx channel group  362  and a PA group  332  are connected through a bridge  322 . The downlink transmitting system  300  shown in  FIG.  11    and  FIG.  12    further includes a phase shifter, and the phase shifter is located between a bridge and a PA. In this case, the Tx channel group  361  is connected to a phase shifter  341  and a phase shifter  342   21  through the bridge  321 , and the Tx channel group  362  is connected to a phase shifter  343  and a phase shifter  344  through the bridge  322 . 
     The downlink transmitting system  300  shown in  FIG.  25    is in a first connection state. When determining that a first condition is met, a baseband processor may control the bridges to enable connection states of the bridge  321  and the bridge  322  to be the first connection state. 
     For example, in  FIG.  25   , the baseband processor controls the bridge  321 , to enable a port A and a port C of the bridge  321  to be in a connected state, and enable a port B and a port D of the bridge  321  to be in a connected state, so as to enable two Tx channels in the Tx channel group  361  to be connected to two PAs in the PA group  331  in a one-to-one correspondence. To be specific, a 1 st  Tx channel is connected to a PA  3311 , and a 2 nd  Tx channel is connected to a PA  3312 . The baseband processor controls the bridge  322 , to enable a port A and a port C of the bridge  322  to be in a connected state, and enable a port B and a port D of the bridge  322  to be in a connected state, so as to enable two Tx channels in the Tx channel group  362  to be connected to two PAs in the PA group  332  in a one-to-one correspondence. To be specific, a 3 rd  Tx channel is connected to a PA  3321 , and a 4 th  Tx channel is connected to a PA  3322 . 
     The downlink transmitting system  300  shown in  FIG.  26    is in a second connection state. When determining that a second condition is met, the baseband processor may control the bridges to enable the connection states of the bridge  321  and the bridge  322  to be the second connection state. 
     For example, in  FIG.  26   , the baseband processor controls the bridge  321 , to enable the port A, the port C, and the port D of the bridge  321  to be in a connected state, and enable the port B and the port D of the bridge  321  to be in a disconnected state, so as to enable the 1 st  Tx channel to be connected to the PA  3311  and the PA  3312 , and the 2 nd  Tx channel to be in a disabled state. The baseband processor controls the bridge  322 , to enable the port A and the port C of the bridge  322  to be in a disconnected state, and enable the port B, the port C, and the port D of the bridge  322  to be in a connected state, so as to enable the 4 th  Tx channel to be connected to the PA  3321  and the PA  3322 , and the 3 rd  Tx channel to be in a disabled state. 
     In another implementation, the switching switch may include a single-pole double-throw switch, or include a single-pole double-throw switch and a single-pole single-throw switch. 
     For example, in a downlink transmitting system  300  shown in  FIG.  27    and  FIG.  28   , a Tx channel group  361  and a PA group  331  are connected through a switching switch  321 , and the switching switch  321  may include a switch  3211  and a switch  3212 . The switch  3211  and the switch  3212  may be single-pole double-throw switches. Alternatively, the switch  3211  is a single-pole single-throw switch, and the switch  3212  is a single-pole double-throw switch. Alternatively, the switch  3211  is a single-pole double-throw switch, and the switch  3212  is a single-pole single-throw switch. A Tx channel group  362  and a PA group  332  are connected through a switching switch  322 , and the switching switch  322  may include a switch  3221  and a switch  3222 . The switch  3221  and the switch  3222  may be single-pole double-throw switches. Alternatively, the switch  3221  is a single-pole single-throw switch, and the switch  3222  is a single-pole double-throw switch. Alternatively, the switch  3221  is a single-pole double-throw switch, and the switch  3222  is a single-pole single-throw switch. 
     The downlink transmitting system  300  shown in  FIG.  27    is in a first connection state. When determining that a first condition is met, a baseband processor may control the switching switch to enable connection states of the switching switch  321  and the switching switch  322  to be the first connection state. 
     For example, in  FIG.  27   , the baseband processor controls the switching switch  321 , to enable a port C of the switch  3211  to be connected to a port A of the switch  3211 , and enable a port D of the switch  3212  to be connected to a port B of the switch  3212 , so as to enable two Tx channels in the Tx channel group  361  to be connected to two PAs in the PA group  331  in a one-to-one correspondence. To be specific, a 1 st  Tx channel is connected to a PA  331 , and a 2 nd  Tx channel is connected to a PA  332 . The baseband processor controls the switching switch  322 , to enable a port C of the switch  3221  to be connected to a port A of the switch  3221 , and enable a port D of the switch  3221  to be connected to a port B of the switch  3222 , so as to enable two Tx channels in the Tx channel group  362  to be connected to two PAs in the PA group  332  in a one-to-one correspondence. In other words, a 3 rd  Tx channel is connected to a PA  333 , and a 4 th  Tx channel is connected to a PA  334 . 
     The downlink transmitting system  300  shown in  FIG.  28    is in a second connection state. When determining that a second condition is met, the baseband processor may control the switching switch to enable the connection states of the switching switch  321  and the switching switch  322  to be the second connection state. 
     For example, in  FIG.  28   , the baseband processor controls the switching switch  321 , to enable the port C of the switch  3211  to be connected to the port A of the switch  3211 , and enable the port D of the switch  3212  to be connected to the port A, so as to enable the 1 st  Tx channel to be connected to the PA  3311  and the PA  3312 , and the 2 nd  Tx channel to be in a disabled state. The baseband processor controls the switching switch  322 , to enable the port C of the switch  3221  to be connected to the port A of the switch  3221 , and enable the port D of the switch  3222  to be connected to the port A, so as to enable the 3 rd  Tx channel to be connected to the PA  3321  and the PA  3322 , and the 4 th  Tx channel to be in a disabled state. 
     It should be understood that the switches  3212  and  3222  in  FIG.  28    are both single-pole double-throw switches, and the switch  3211  and the switch  3221  may be single-pole double-throw switches or may be single-pole single-throw switches. 
     It should be further understood that the single-pole single-throw switch mentioned in this embodiment of this application is a switch having a single-pole single-throw function, and the single-pole double-throw switch mentioned in this embodiment of this application is a switch having a single-pole double-throw function. 
     For structures and types of the switching switches in the downlink transmitting system  400  and the downlink transmitting system  500  provided in embodiments of this application, refer to descriptions in  FIG.  25    to  FIG.  28   . For brevity, details are not described in this embodiment of this application. 
     The foregoing descriptions are merely specific implementations of this application, but are not intended to limit the protection scope of this application. Any variation or replacement readily figured out by a person skilled in the art within the technical scope disclosed in this application shall fall within the protection scope of this application. Therefore, the protection scope of this application shall be subject to the protection scope of the claims.