Patent Publication Number: US-2019190670-A1

Title: Signal transmission method and apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of International Application No. PCT/CN2017/098612, filed on Aug. 23, 2017, which claims priority to Chinese Patent Application No. 201610726705.0, filed on Aug. 25, 2016. The disclosures of the aforementioned applications are hereby incorporated by reference in their entireties. 
    
    
     TECHNICAL FIELD 
     Embodiments of this application relate to communications technologies, and in particular, to a signal transmission method and apparatus. 
     BACKGROUND 
     As users have increasingly high requirements on communication, coordinated multipoint transmission/reception (CoMP for short) is introduced in a Long Term Evolution Advanced (LTE-Advanced for short) system. The CoMP means that a plurality of transmission points in different geographical locations participate in data transmission of one user equipment through coordination or jointly receive data sent by one user equipment. The participating in data transmission of one user equipment through coordination includes a plurality of scenarios, for example: simultaneously transmitting data for one user equipment by a plurality of transmission points; or dynamic point selection, that is, a plurality of transmission points perform coordinated scheduling, and finally one of the plurality of transmission points is selected to transmit data for the user equipment; or coordinated scheduling or coordinated beamforming, that is, a plurality of transmission points reduce interference between the transmission points through coordinated scheduling or coordinated beamforming. This improves overall system performance. The joint reception means that a plurality of transmission points simultaneously receive uplink data of the user equipment, and then the uplink data received by the transmission points are combined, to improve performance of uplink data transmission. 
     To perform selective frequency scheduling on a link, CoMP user equipment needs to separately send a sounding reference signal (SRS for short) to the plurality of transmission points, to detect channel quality. In this case, a base station to which the plurality of transmission points belong needs to separately perform SRS resource configuration for the CoMP user equipment. Consequently, resource waste is caused. In addition, because the CoMP user equipment separately sends an SRS to the plurality of transmission points, a delay in obtaining channel quality is caused. 
     SUMMARY 
     Embodiments of this application provide a signal transmission method and apparatus, so as to save resources during selective frequency scheduling and reduce a delay in obtaining channel quality. 
     According to a first aspect, an embodiment of this application provides a signal transmission method, including: receiving, by a first device, reference signal configuration information sent by a second device, where the reference signal configuration information includes reference signal resource location information and/or a reference signal sequence parameter, the reference signal resource location information is used to indicate a time domain resource and/or a frequency domain resource for transmitting a reference signal, the reference signal sequence parameter includes all or some parameters required for generating a reference signal sequence, and the reference signal is used to detect channel quality; and receiving, by the first device, a reference signal sent by first user equipment corresponding to the reference signal configuration information. 
     In this embodiment of this application, the first device exchanges the reference signal configuration information with the second device, where the reference signal configuration information includes the resource location information and/or the reference signal sequence parameter, the reference signal resource location information is used to indicate the time domain resource and/or the frequency domain resource for transmitting a reference signal, the reference signal sequence parameter includes all or some parameters required for generating the reference signal sequence, and the reference signal is used to detect channel quality. The first device receives, based on the reference signal configuration information, the reference signal that is corresponding to the reference signal configuration information and that is sent by the first user equipment, so as to prevent the first device and the second device from separately configuring the reference signal configuration information for coordinated multipoint transmission user equipment. This saves resources. In addition, reference signals received by the first device and the second device are sent by the coordinated multipoint transmission user equipment at a same moment. This reduces delays in obtaining channel quality by different devices, and improves performance of coordinated transmission. 
     In one embodiment, after the receiving, by a first device, reference signal configuration information sent by a second device, the method further includes: sending, by the first device, first control information to second user equipment for which a physical uplink shared channel (PUSCH) is configured on the reference signal resource location information, where the first control information includes first indication information, and the first indication information is used to indicate the reference signal resource location information in the reference signal configuration information, or the first indication information is used to indicate that the reference signal resource location information is not used to transmit the PUSCH of the second user equipment. 
     In this embodiment of this application, a reference signal of the second user equipment is not configured for the first device on the reference signal resource location information, but the PUSCH of the second user equipment is configured for the first device on the reference signal resource location information. Therefore, the first device needs to instruct the second user equipment, for which the PUSCH is configured on the reference signal resource location information, not to transmit the PUSCH on the reference signal resource location information. In this way, a conflict with transmission of the reference signal corresponding to the reference signal configuration information can be avoided. 
     In one embodiment, when the reference signal resource location information is not used to transmit the PUSCH of the second user equipment, the method further includes: puncturing the PUSCH of the second user equipment at a resource location indicated by the reference signal resource location information, or performing rate matching on the PUSCH of the second user equipment on a resource other than a resource location indicated by the reference signal resource location information. 
     In one embodiment, after the receiving, by a first device, reference signal configuration information sent by a second device, the method further includes: sending, by the first device, second control information to fifth user equipment for which a reference signal is configured on the reference signal resource location information, where the second control information is used to indicate that the fifth user equipment for which the reference signal is configured on the reference signal resource location information sends a first reference signal, and the first reference signal is orthogonal to the reference signal corresponding to the reference signal configuration information. 
     In this embodiment of this application, the first device configures the reference signal for the fifth user equipment on the reference signal resource location information. Therefore, the first device needs to instruct the fifth user equipment, for which the reference signal is configured on the reference signal resource location information, to transmit, on the reference signal resource location information, a first reference signal orthogonal to the reference signal sequence indicated by the reference signal sequence parameter, to avoid interference to transmission of the reference signal corresponding to the reference signal configuration information. 
     In one embodiment, after the receiving, by a first device, reference signal configuration information sent by a second device, the method further includes: sending, by the first device, third control information to third user equipment for which a reference signal is configured on the resource location information in the reference signal configuration information, where the third control information is used to indicate that the third user equipment for which the reference signal is configured on the reference signal resource location information does not send the reference signal. 
     In this embodiment of this application, the first device configures the reference signal for the third user equipment on the reference signal resource location information. Therefore, the first device needs to instruct the third user equipment, for which the reference signal is configured on the reference signal resource location information, not to send the reference signal on the reference signal resource location information, to avoid interference to transmission of the reference signal corresponding to the reference signal configuration information. 
     In one embodiment, after the receiving, by a first device, reference signal configuration information sent by a second device, the method further includes: sending, by the first device, fourth control information to fourth user equipment for which a PDSCH is configured on the reference signal resource location information, where the fourth control information includes second indication information, and the second indication information is used to indicate that the reference signal resource location information is not used to receive the PDSCH of the fourth user equipment. 
     In this embodiment of this application, the first device does not configure a reference signal for the fourth user equipment on the reference signal resource location information, but the first device configures the PDSCH for the fourth user equipment on the reference signal resource location information. Therefore, the first device needs to notify the fourth user equipment for which the PDSCH is configured on the reference signal resource location information that the reference signal resource location information is not used to receive the PDSCH of the fourth user equipment, so that on one hand, a conflict with transmission of the reference signal corresponding to the reference signal configuration information is avoided, and on the other hand, accuracy of receiving the PDSCH of the fourth user equipment is ensured. 
     In one embodiment, after the sending, by the first device, fourth control information to fourth user equipment for which a PDSCH is configured on the reference signal resource location information, the method further includes: mapping, by the first device, the PDSCH to a configured resource corresponding to the PDSCH; performing, by the first device, puncturing at a resource location at which the configured resource corresponding to the PDSCH overlaps a resource location indicated by the reference signal resource location information; and sending, by the first device, a PDSCH on which puncturing processing has been performed. 
     In one embodiment, after the sending, by the first device, fourth control information to fourth user equipment for which a PDSCH is configured on the reference signal resource location information, the method further includes: removing, by the first device from a configured resource corresponding to the PDSCH, a resource overlapping a resource location indicated by the reference signal resource location information, to obtain a first target resource corresponding to the PDSCH; mapping, by the first device, the PDSCH to the first target resource; and sending, by the first device, the PDSCH. 
     According to a second aspect, an embodiment of this application provides a signal transmission method, including: sending, by a second device, reference signal configuration information to a first device, where the reference signal configuration information includes reference signal resource location information and/or a reference signal sequence parameter, the reference signal resource location information is used to indicate a time domain resource and/or a frequency domain resource for transmitting a reference signal, the reference signal sequence parameter includes all or some parameters required for generating a reference signal sequence, the reference signal configuration information is used to indicate that the first device receives a reference signal sent by user equipment corresponding to the reference signal configuration information, and the reference signal is used to detect channel quality; and receiving, by the second device based on the reference signal configuration information, a reference signal sent by first user equipment corresponding to the reference signal configuration information. 
     In this embodiment of this application, the first device exchanges the reference signal configuration information with the second device, where the reference signal configuration information includes the resource location information and/or the reference signal sequence parameter, the reference signal resource location information is used to indicate the time domain resource and/or the frequency domain resource for transmitting a reference signal, the reference signal sequence parameter includes all or some parameters required for generating the reference signal sequence, and the reference signal is used to detect channel quality. The first device receives, based on the reference signal configuration information, the reference signal that is corresponding to the reference signal configuration information and that is sent by the first user equipment, so as to prevent the first device and the second device from separately configuring the reference signal configuration information for coordinated multipoint transmission user equipment (namely, the first user equipment). This saves resources. In addition, reference signals received by the first device and the second device are sent by the coordinated multipoint transmission user equipment at a same moment. This reduces delays in obtaining channel quality by different devices, and improves performance of coordinated transmission. 
     In any one of the foregoing implementations, in one embodiment, the reference signal configuration information includes the reference signal configuration information of the coordinated multipoint transmission user equipment, and that the first device receives a reference signal sent by first user equipment corresponding to the reference signal configuration information includes: receiving, by the first device based on the reference signal configuration information, the reference signal sent by the coordinated multipoint transmission user equipment. 
     In one embodiment, the reference signal resource location information includes pattern information of the reference signal on the time domain resource or the frequency domain resource. 
     In one embodiment, the reference signal resource location information includes time domain resource information, frequency domain resource information, and/or the like. The time domain resource information includes at least subframe location information and/or symbol location information. 
     In one embodiment, the reference signal configuration information further includes power information, the power information is used to indicate a preset power value or power calculation information, the preset power value is a preset power value of the reference signal, and the power calculation information is preset calculation information used to determine power of the reference signal. 
     According to a third aspect, an embodiment of this application provides a signal transmission method, including: receiving, by user equipment, first control information sent by a first device, where a reference signal is not configured for the user equipment on reference signal resource location information in reference signal configuration information received by the first device, but a to-be-transmitted physical uplink shared channel (PUSCH) is configured, the first control information includes first indication information, the first indication information is used to indicate the reference signal resource location information in the reference signal configuration information, or the first indication information is used to indicate that the reference signal resource location information is not used to transmit the PUSCH of the user equipment, and the reference signal is used to detect channel quality; and sending, by the user equipment, the PUSCH based on the first control information, to avoid a conflict with transmission of the reference signal corresponding to the reference signal configuration information. 
     In one embodiment, the sending, by the user equipment, the PUSCH based on the first control information includes: mapping, by the user equipment, the PUSCH to a configured resource corresponding to the PUSCH; performing, by the user equipment, puncturing at a resource location at which the configured resource corresponding to the PUSCH overlaps a resource location indicated by the reference signal resource location information; and sending, by the user equipment, a PUSCH on which puncturing processing has been performed. 
     In one embodiment, the sending, by the user equipment, the PUSCH based on the first control information includes: removing, by the user equipment from a configured resource corresponding to the PUSCH, a resource overlapping a resource location indicated by the reference signal resource location information, to obtain a second target resource corresponding to the PUSCH; mapping, by the user equipment, the PUSCH to the second target resource; and sending, by the user equipment, the PUSCH. 
     According to a fourth aspect, an embodiment of this application provides a signal transmission method, including: receiving, by user equipment, second control information sent by a first device, where a reference signal is configured for the user equipment on reference signal resource location information in reference signal configuration information received by the first device, the second control information is used to indicate that the user equipment sends a first reference signal, and the first reference signal is orthogonal to the reference signal corresponding to the reference signal configuration information; and sending, by the user equipment, the first reference signal based on the second control information, to avoid interference to transmission of the reference signal corresponding to the reference signal configuration information. 
     In one embodiment, the sending, by the user equipment, the first reference signal based on the second control information includes: sending, by the user equipment, the first reference signal on a resource indicated by the reference signal resource location information that is in the reference signal configuration information and that is included in the second control information. 
     According to a fifth aspect, an embodiment of this application provides a signal transmission method, including: receiving, by user equipment, third control information sent by a first device, where a reference signal is configured for the user equipment on resource location information in reference signal configuration information received by the first device, the third control information is used to indicate that the user equipment does not send the reference signal on the reference signal resource location information, and the reference signal is used to detect channel quality; and determining, by the user equipment, that the reference signal is not sent on the reference signal resource location information, to avoid interference to transmission of the reference signal corresponding to the reference signal configuration information. 
     According to a sixth aspect, an embodiment of this application provides a signal transmission method, including: receiving, by user equipment, fourth control information sent by a first device, where a reference signal is not configured for the user equipment on resource location information in reference signal configuration information received by the first device, but a to-be-transmitted physical downlink shared channel (PDSCH) is configured, the fourth control information includes second indication information, the second indication information is used to indicate that the first device punctures the PDSCH of the user equipment at a resource location indicated by reference signal resource location information, or the second indication information is used to indicate that the first device performs rate matching on the PDSCH of the user equipment on a resource other than a resource location indicated by reference signal resource location information, and the reference signal is used to detect channel quality; and receiving, by the user equipment, the PDSCH based on the fourth control information. In this way, on one hand, a conflict with transmission of the reference signal corresponding to the reference signal configuration information can be avoided, and on the other hand, accuracy of receiving the PDSCH by the user equipment can be ensured. 
     In one embodiment, the receiving, by the user equipment, the PDSCH based on the fourth control information includes: receiving, by the user equipment, the PDSCH on the resource other than the resource location indicated by the reference signal resource location information that is in the reference signal configuration information and that is indicated by the second indication information. 
     According to a seventh aspect, an embodiment of this application provides a signal transmission apparatus. The signal transmission apparatus includes: a receiving module, configured to: receive reference signal configuration information sent by another device, where the reference signal configuration information includes reference signal resource location information and/or a reference signal sequence parameter, the reference signal resource location information is used to indicate a time domain resource and/or a frequency domain resource for transmitting a reference signal, the reference signal sequence parameter includes all or some parameters required for generating a reference signal sequence, and the reference signal is used to detect channel quality; and receive a reference signal sent by user equipment corresponding to the reference signal configuration information. 
     Based on a similar conception, a principle of resolving a problem by the apparatus corresponds to the solution in the method design in the first aspect. Therefore, for implementation of the apparatus, reference may be made to the implementation of the method, and repeated content is not described again. 
     According to an eighth aspect, an embodiment of this application provides a signal transmission apparatus. The signal transmission apparatus includes: a sending module, configured to send reference signal configuration information to another device, where the reference signal configuration information includes reference signal resource location information and/or a reference signal sequence parameter, the reference signal resource location information is used to indicate a time domain resource and/or a frequency domain resource for transmitting a reference signal, the reference signal sequence parameter includes all or some parameters required for generating a reference signal sequence, and the reference signal configuration information is used to indicate that the another device receives a reference signal sent by user equipment corresponding to the reference signal configuration information; and a receiving module, configured to receive, based on the reference signal configuration information, the reference signal sent by the user equipment corresponding to the reference signal configuration information, where the reference signal is used to detect channel quality. 
     Based on a similar conception, a principle of resolving a problem by the apparatus corresponds to the solution in the method design in the second aspect. Therefore, for implementation of the apparatus, reference may be made to the implementation of the method, and repeated content is not described again. 
     According to a ninth aspect, an embodiment of this application provides a signal transmission apparatus. The signal transmission apparatus includes: a receiving module, configured to receive first control information sent by a first device, where a reference signal is not configured for the signal transmission apparatus on resource location information in reference signal configuration information received by the first device, but a to-be-transmitted physical uplink shared channel (PUSCH) is configured, the first control information includes first indication information, the first indication information is used to indicate the resource location information in the reference signal configuration information, or the first indication information is used to indicate that the reference signal resource location information is not used to transmit the PUSCH of the signal transmission apparatus, and the reference signal is used to detect channel quality; a sending module, configured to send the PUSCH based on the first control information. 
     Based on a similar conception, a principle of resolving a problem by the apparatus corresponds to the solution in the method design in the third aspect. Therefore, for implementation of the apparatus, reference may be made to the implementation of the method, and repeated content is not described again. 
     According to a tenth aspect, an embodiment of this application provides a signal transmission apparatus. The signal transmission apparatus includes: a receiving module, configured to receive second control information sent by a first device, where a reference signal is configured for the signal transmission apparatus on reference signal resource location information in reference signal configuration information received by the first device, the second control information is used to indicate that the signal transmission apparatus sends a first reference signal, and the first reference signal is orthogonal to the reference signal corresponding to the reference signal configuration information; and a sending module, configured to send the first reference signal based on the second control information. 
     Based on a similar conception, a principle of resolving a problem by the apparatus corresponds to the solution in the method design in the fourth aspect. Therefore, for implementation of the apparatus, reference may be made to the implementation of the method, and repeated content is not described again. 
     According to an eleventh aspect, an embodiment of this application provides a signal transmission apparatus. The signal transmission apparatus includes: a receiving module, configured to receive third control information sent by a first device, where a reference signal is configured for the signal transmission apparatus on reference signal resource location information in reference signal configuration information received by the first device, and the third control information is used to indicate that the signal transmission apparatus does not send the reference signal on the reference signal resource location information; and a sending module, configured to determine that the reference signal is not sent on the reference signal resource location information. 
     Based on a similar conception, a principle of resolving a problem by the apparatus corresponds to the solution in the method design in the fifth aspect. Therefore, for implementation of the apparatus, reference may be made to the implementation of the method, and repeated content is not described again. 
     According to a twelfth aspect, an embodiment of this application provides a signal transmission apparatus. The signal transmission apparatus includes: a receiving module, configured to receive fourth control information sent by a first device, where a reference signal is not configured for the signal transmission apparatus on reference signal resource location information in reference signal configuration information received by the first device, but a to-be-transmitted PDSCH is configured, the fourth control information includes second indication information, the second indication information is used to indicate that the first device punctures the PDSCH at a resource location indicated by the reference signal resource location information, or the second indication information is used to indicate that the first device performs rate matching on the PDSCH on a resource other than a resource location indicated by the reference signal resource location information, and the reference signal is used to detect channel quality. The receiving module is further configured to receive the PDSCH based on the fourth control information. 
     Based on a similar conception, a principle of resolving a problem by the apparatus corresponds to the solution in the method design in the sixth aspect. Therefore, for implementation of the apparatus, reference may be made to the implementation of the method, and repeated content is not described again. 
     According to a thirteenth aspect, an embodiment of this application provides a signal transmission apparatus. The signal transmission apparatus may be a first device. The signal transmission apparatus includes: a transmitter, a receiver, and a processor. Further, the signal transmission apparatus may include a memory configured to store an executable instruction. The processor is configured to execute the executable instruction, to perform the method according to any one of the first aspect. 
     According to a fourteenth aspect, an embodiment of this application provides a signal transmission apparatus. The signal transmission apparatus may be a second device. The signal transmission apparatus includes: a transmitter, a receiver, and a processor. Further, the signal transmission apparatus may include a memory configured to store an executable instruction. The processor is configured to execute the executable instruction, to perform the method according to any one of the second aspect. 
     According to a fifteenth aspect, an embodiment of this application provides a signal transmission apparatus. The signal transmission apparatus may be user equipment. The signal transmission apparatus includes: a transmitter, a receiver, and a processor. Further, the signal transmission apparatus may include a memory configured to store an executable instruction. The processor is configured to execute the executable instruction, to perform the method according to any one of the third aspect, the fourth aspect, the fifth aspect, or the sixth aspect. 
     According to a sixteenth aspect, an embodiment of this application provides a non-volatile computer readable storage medium that stores one or more programs. The one or more programs include an instruction. When the instruction is executed by user equipment, a first device, or a second device, the user equipment or the device performs the solution in the corresponding method design. Repeated content is not described again. 
     According to a seventeenth aspect, an embodiment of this application provides a signal transmission apparatus. The signal transmission apparatus may be configured to perform the method according to any one of the first aspect, the second aspect, the third aspect, the fourth aspect, the fifth aspect, or the sixth aspect. The apparatus has a function of implementing behavior of user equipment, a first device, or a second device in the method aspects, and includes a means (means) corresponding to a step or a function described in the method aspects. The step or the function may be implemented by software, by hardware, or by a combination of hardware and software. 
     In one embodiment, a function of a processing module in this embodiment of this application may be specifically implemented by a processor in corresponding user equipment, a corresponding first device, or a corresponding second device; a function of a sending module may be specifically implemented by a transmitter in the corresponding user equipment, the corresponding first device, or the corresponding second device; and a function of a receiving module may be specifically implemented by a receiver in the corresponding user equipment, the corresponding first device, or the corresponding second device. The transmitter and the receiver may be separately disposed, or may be integrated into a transceiver. This is not limited in this embodiment of this application. 
     In one embodiment, the signal transmission apparatus includes one or more processors and a communications unit. The one or more processors are configured to support the signal transmission apparatus in executing a corresponding function in the foregoing method. The communications unit is configured to support the signal transmission apparatus in communicating with another device, to implement a reception and/or sending function. 
     In one embodiment, the signal transmission apparatus may further include one or more memories. The memory is coupled to the processor, and the memory stores a necessary program instruction and necessary data of the signal transmission apparatus. The one or more memories may be integrated with the processor, or may be separated from the processor. This is not limited in this application. 
     The signal transmission apparatus may be a base station, a TRP, or the like, and the communications unit may be a transceiver or a transceiver circuit. 
     Alternatively, the signal transmission apparatus may be a communications chip, and may be disposed in a base station or a TRP. The communications unit may be an input/output circuit or an input/output interface of the communications chip. 
     Alternatively, the signal transmission apparatus may be an intelligent terminal, a wearable device, or the like, and the communications unit may be a transceiver or a transceiver circuit. 
     Furthermore, the signal transmission apparatus may be a communications chip, and may be disposed in user equipment. The communications unit may be an input/output circuit or an input/output interface of the communications chip. 
     These aspects and another aspect of this application will be clearer and easier to understand based on descriptions of the following (a plurality of) embodiments. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       To describe technical solutions in embodiments of this application or the prior art more clearly, the following briefly describes the accompanying drawings required for describing the embodiments. 
         FIG. 1  is a signaling interaction diagram of a signal transmission method according to one embodiment of this application; 
         FIG. 2  is a schematic diagram when reference signal resource location information is pattern information according to an embodiment of this application; 
         FIG. 3  is a schematic diagram of mapping a symbol of an SRS; 
         FIG. 4  is a schematic structural diagram of a signal transmission apparatus according to one embodiment of this application; 
         FIG. 5  is a schematic structural diagram of a signal transmission apparatus according to one embodiment of this application; 
         FIG. 6  is a schematic structural diagram of a signal transmission apparatus according to one embodiment of this application; 
         FIG. 7  is a schematic structural diagram of a signal transmission apparatus according to one embodiment of this application; 
         FIG. 8  is a schematic structural diagram of a signal transmission apparatus according to one embodiment of this application; and 
         FIG. 9  is a schematic structural diagram of a signal transmission apparatus according to one embodiment of this application. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     In the specification and claims of the embodiments of this application, the terms “first”, “second”, and the like are intended to distinguish between similar objects, but are unnecessarily intended to describe a particular order or sequence. It should be understood that the data termed in such a way is interchangeable in proper circumstances so that the embodiments of this application described herein can be, for example, implemented in other orders than the order illustrated or described herein. In addition, the terms “include”, “contain”, and any other variants mean to cover the non-exclusive inclusion, for example, a process, method, system, product, or device that includes a list of operations or units is not necessarily limited to those expressly listed operations or units, but may include other operations or units not expressly listed or inherent to such a process, method, system, product, or device. 
     A next-generation mobile communications system requires large-capacity and high-quality data transmission. A multiple input multiple output (MIMO for short) technology is considered as one of key technologies that can implement future high-speed data transmission. A plurality of transmit antennas of a conventional centralized MIMO system are all centered at a base station (BS for short) end. Different from the centralized MIMO system, a plurality of transmit antennas of a distributed MIMO system are distributed at different geographical locations, and each pair of transmit and receive links of the distributed MIMO system are more independent of each other. Therefore, the distributed MIMO system has advantages such as a large capacity, low power consumption, better coverage, and low electromagnetic damage to a human body, and is considered as one of candidate solutions of a future wireless communications system. 
     In a distributed MIMO system, to improve signal reliability of edge user equipment and a throughput of an edge cell, use of a transmission method with a plurality of transmission points and a plurality of data streams may be considered. Specifically, a base station may obtain channel quality of each transmission point in a manner of receiving an SRS sent by user equipment. However, for a plurality of transmission points, the user equipment needs to repeatedly send the SRS. Consequently, resource waste and a delay in obtaining channel quality are caused. 
     For the foregoing problem, the embodiments of this application provide a signal transmission method and apparatus, to implement coordinated transmission of a reference signal, for example, an SRS, by exchanging reference signal configuration information between devices, for example, base stations, so that a delay in obtaining channel quality is reduced while resources are reduced. 
     For an application scenario, the embodiments of this application may be applied to a time division duplex (TDD for short) system and a frequency division duplex (FDD for short) system. The embodiments of this application may be applied to a single-carrier system and a multicarrier system. The embodiments of this application may be applied to a high-frequency (higher than a frequency band of 6 GHz) communications system and a low-frequency (e.g., lower than a frequency band of 6 GHz) communications system. 
       FIG. 1  is a signaling interaction diagram of Embodiment 1 of a signal transmission method according to this application. As shown in  FIG. 1 , the signal transmission method includes the following operations. 
     Operation S 101 : A first device receives reference signal configuration information sent by a second device. 
     Correspondingly, the second device sends the reference signal configuration information to the first device. 
     To enable the first device and the second device to simultaneously receive a reference signal subsequently sent by coordinated transmission user equipment, the second device needs to notify reference signal configuration information of the coordinated transmission user equipment to the first device. 
     The first device and the second device may be specifically a first base station and a second base station, respectively. However, this embodiment of this application is not limited thereto. 
     The reference signal configuration information includes reference signal resource location information and/or a reference signal sequence parameter, the reference signal resource location information is used to indicate a time domain resource and/or a frequency domain resource for transmitting a reference signal, and the reference signal sequence parameter includes all or some parameters required for generating a reference signal sequence. For details, refer to descriptions about the reference signal sequence in the prior art. Details are not described herein again. The reference signal is used to detect channel quality. In other words, the reference signal configuration information may include the reference signal resource location information; or the reference signal configuration information may include the reference signal sequence parameter; or the reference signal configuration information may include the reference signal resource location information and the reference signal sequence parameter. 
     Content included in the reference signal configuration information may be set according to an actual requirement. When the reference signal configuration information includes only the reference signal resource location information, a person skilled in the art may understand that the first device and the second device have negotiated a reference signal sequence parameter corresponding to the reference signal resource location information included in the reference signal configuration information. Likewise, when the reference signal configuration information includes only the reference signal sequence parameter, a person skilled in the art may understand that the first device and the second device have negotiated reference signal resource location information corresponding to the reference signal sequence parameter included in the reference signal configuration information. Alternatively, a correspondence between the reference signal sequence parameter and the reference signal resource location information has been configured for the first device. 
     In one embodiment, the reference signal resource location information may be specifically pattern information of the reference signal on the time domain resource or the frequency domain resource. For example, as shown in  FIG. 2 , a pattern  1 , a pattern  2 , and a pattern  3  are three possible SRS resource location distributions. In this case, a specific subframe location of the reference signal resource location information may be defined by a protocol, or may be user-defined. This is not limited in this embodiment of this application. In addition, alternatively, the reference signal resource location information may be specifically time domain resource information and/or frequency domain resource information, and the time domain resource information includes at least subframe location information and/or symbol location information. If the reference signal subsequently sent by the coordinated transmission user equipment occupies a full-bandwidth frequency domain resource, the reference signal resource location information may include only the time domain resource information, such as the subframe location information, the symbol location information, or the subframe location information and the symbol location information. If the reference signal subsequently sent by the coordinated transmission user equipment is sent only on a fixed preset quantity of symbol locations, the reference signal resource location information may include only the frequency domain resource information. For example, in an existing LTE system, an SRS is transmitted only on one or more last symbols of an uplink subframe or a special subframe, shown in  FIG. 3 . The special subframe is a subframe used for uplink-downlink transition in a TDD system, and the special subframe includes three parts: a downlink part (DwPTS for short), a guard period (GP for short), and an uplink part (the uplink part of the special subframe, UpPTS for short). 
     In one embodiment, the reference signal configuration information may further include power information, and the power information is used to indicate a preset power value or power calculation information. The preset power value is a preset power value of the reference signal. The power calculation information is preset calculation information used to determine power of the reference signal. 
     For example, for a serving cell C, a transmit power P SRS  at which user equipment sends an SRS in a subframe i is defined as follows: 
         P   SRS,c ( i )=min{ P   CMAX,c ( i ), P   SRS   _   OFFSET,c ( m )+10 log 10 ( M   SRS,c )+ P   O   _   POSCH,c ( j )+α c ( j )· PL   c   +f   c ( i )},
 
     where a unit of P SRS,c  (i) is dBm; 
     P CMAX,c (z) is a configured transmit power of the user equipment in the subframe i of the serving cell C; 
     for P SRS   _   OFFSET,c  (m), values of m=0 and m=1 for the serving cell C are semi-statically configured by using higher layer signaling; for SRS transmission (e.g., periodic SRS transmission) with a trigger type 0, m=0; and for SRS transmission (e.g., aperiodic SRS transmission) with a trigger type 1, m=1; 
     M SRS,c  is a bandwidth for SRS transmission performed in the subframe i of the serving cell c, and denotes a quantity of resource blocks; 
     f c (i) is a power control and modulation status of a current PUSCH of the serving cell c; and 
     values of P O   _   PUSCH,c  (j) and π c  (j) are as follows when j=1: 
     P O   _   PUSCH,c  (1) P O   _   UE   _   PUSCH,c,2  (1)+P O   _   NOMINAL   _   PUSCH,c,2  (1), where P O   _   UE   _   PUSCH,c,2  (1) and P O   _   NOMINAL   _   PUSCH,c,2 (1) are provided by using higher layer parameters p0-UE-PUSCH-SubframeSet2-r12 and p0-NominalPUSCH-SubframeSet2-r12; and 
       α c ( j )=α c,2 ∈{0,0.4,0.5,0.6,0.7,0.8,0.9,1},
 
     where α c,2  is provided by using a higher layer parameter alpha-SubframeSet2-r12. 
     When the first device and the second device coordinate to participate in data transmission of first user equipment, that is, the first user equipment is in CoMP, the first user equipment generates and sends, based on the reference signal configuration information, the reference signal corresponding to the reference signal configuration information. For example, the first user equipment determines, based on the power information included in the reference signal configuration information, power of the reference signal corresponding to the reference signal configuration information. After learning the power information included in the reference signal configuration information, the first device may better measure a channel status based on the SRS. 
     Operation S 102 : The first device receives the reference signal that is corresponding to the reference signal configuration information and that is sent by the first user equipment. 
     Operation S 103 : The second device receives, based on the reference signal configuration information, the reference signal that is corresponding to the reference signal configuration information and that is sent by the first user equipment. 
     In one embodiment, the first device configures or schedules transmission of the reference signal of the user equipment based on the reference signal configuration information received by the first device, and receives the reference signal sent by the CoMP user equipment (namely, the first user equipment). The second device configures the reference signal configuration information for the CoMP user equipment, and receives, based on the reference signal configuration information, the reference signal sent by the CoMP user equipment. 
     After the first user equipment corresponding to the reference signal configuration information sends the reference signal, the first device and the second device receive the reference signal. The first device and the second device may obtain, by receiving the reference signal, a channel feature of the first user equipment that sends the reference signal, so as to determine whether to perform data transmission with the first user equipment or determine a specific scheduling policy for performing data transmission with the first user equipment. The scheduling policy includes joint transmission, dynamic point selection transmission, transport layer quantity selection, precoding selection, modulation and coding selection, time/frequency resource location selection, or the like. 
     In the signal transmission method in this embodiment of this application, the first device exchanges the reference signal configuration information with the second device, to implement coordinated transmission of the reference signal (for example, the SRS) sent by the CoMP user equipment, so that the first device and the second device do not need to separately configure, for the CoMP user equipment, a resource used to transmit the reference signal. This saves resources. In addition, the CoMP user equipment sends a same reference signal to a plurality of devices (including the first device and the second device), so as to reduce delays in obtaining channel quality by different devices, and improve performance of coordinated transmission. 
     Based on the foregoing embodiment, in an implementation, the reference signal configuration information may be the reference signal configuration information of the CoMP user equipment. In this case, that the first device receives the reference signal that is corresponding to the reference signal configuration information and that is sent by the first user equipment may include: receiving, by the first device based on the reference signal configuration information, the reference signal sent by the CoMP user equipment. 
     In another implementation, the reference signal configuration information may be reference signal configuration information of any user equipment served by the second device. In this case, after the first device receives the reference signal configuration information sent by the second device, the first device needs to determine whether the first user equipment corresponding to the reference signal configuration information is the CoMP user equipment. If it is determined that the first user equipment corresponding to the reference signal configuration information is the CoMP user equipment, the first device receives the reference signal that is corresponding to the reference signal configuration information and that is sent by the first user equipment; or if it is determined that the first user equipment corresponding to the reference signal configuration information is not the CoMP user equipment, the first device ignores the reference signal configuration information, and does not perform any subsequent processing. 
     That the first device configures or schedules transmission of the reference signal of the user equipment based on the reference signal configuration information is described below in detail by using several specific embodiments. 
     In one embodiment, after the first device receives the reference signal configuration information sent by the second device, the signal transmission method may further include: sending, by the first device, first control information to second user equipment for which a physical uplink shared channel (PUSCH for short) is configured on the reference signal resource location information. 
     A reference signal of the second user equipment is not configured on the reference signal resource location information, and the PUSCH of the second user equipment is configured on the reference signal resource location information. The first control information may include first indication information, and the first indication information is used to indicate the resource location information in the reference signal configuration information, or the first indication information is used to indicate that the reference signal resource location information is not used to transmit the PUSCH of the second user equipment. 
     When the first indication information is used to indicate the resource location information in the reference signal configuration information, the second user equipment may indirectly determine, based on a presetting (for example, stipulation in a protocol), that a resource location indicated by the first indication information is not used to transmit the PUSCH of the second user equipment; or when the first indication information is used to indicate that the reference signal resource location information is not used to transmit the PUSCH of the second user equipment, the second user equipment may determine, in a direct form, that the resource location indicated by the first indication information is not used to transmit the PUSCH of the second user equipment. The direct form such as a specific indication or a dedicated indication is used, so that the second user equipment determines that the resource location indicated by the first indication information is not used to transmit the PUSCH of the second user equipment. 
     In this embodiment, the first device does not configure the reference signal for the second user equipment on the reference signal resource location information, but the first device configures the PUSCH for the second user equipment on the reference signal resource location information. Therefore, the first device needs to instruct the second user equipment, for which the PUSCH is configured on the reference signal resource location information, not to transmit the PUSCH on the reference signal resource location information. In this way, a conflict with transmission of the reference signal corresponding to the reference signal configuration information can be avoided. 
     Correspondingly, the second user equipment receives the first control information sent by the first device, and sends the PUSCH based on the first control information. The second user equipment may send the PUSCH based on the first control information in the following two specific implementations: 
     In one embodiment, the PUSCH of the second user equipment is punctured at a resource location indicated by the reference signal resource location information. Specifically, the second user equipment maps the PUSCH to a configured resource corresponding to the PUSCH. The second user equipment punctures the PUSCH of the second user equipment at a resource location at which the configured resource corresponding to the PUSCH overlaps the resource location indicated by the reference signal resource location information. The second user equipment sends a PUSCH on which puncturing processing has been performed. 
     In another embodiment, rate matching is performed on the PUSCH of the second user equipment on a resource other than a resource location indicated by the reference signal resource location information. Specifically, the second user equipment removes, from a configured resource corresponding to the PUSCH, a resource overlapping the resource location indicated by the reference signal resource location information, to obtain a second target resource corresponding to the PUSCH; the second user equipment maps the PUSCH to the second target resource; and the user equipment sends the PUSCH. 
     Selection of the foregoing two implementations may be predefined by a protocol, or may be indicated by the first control information, or may be indicated by other information. This is not limited in this embodiment of this application. 
     In one embodiment, after the first device receives the reference signal configuration information sent by the second device, the signal transmission method may further include: sending, by the first device, second control information to fifth user equipment for which a reference signal is configured on the reference signal resource location information. 
     The second control information is used to indicate that the fifth user equipment for which the reference signal is configured on the reference signal resource location information sends a first reference signal, and the first reference signal is orthogonal to the reference signal corresponding to the reference signal resource location information. 
     In this embodiment, the first device configures the reference signal for the fifth user equipment on the reference signal resource location information. Therefore, the first device needs to instruct the fifth user equipment, for which the reference signal is configured on the reference signal resource location information, to transmit, on the reference signal resource location information, the first reference signal orthogonal to the reference signal sequence indicated by the reference signal sequence parameter, to avoid interference to transmission of the reference signal corresponding to the reference signal resource location information. 
     Correspondingly, the fifth user equipment receives the second control information sent by the first device, and sends the first reference signal based on the second control information. That the fifth user equipment sends the first reference signal based on the second control information may include: sending, by the fifth user equipment, the first reference signal on a resource indicated by the reference signal resource location information in the reference signal configuration information. 
     In one embodiment, after the first device receives the reference signal configuration information sent by the second device, the signal transmission method may further include: sending, by the first device, third control information to third user equipment for which a reference signal is configured on the resource location information in the reference signal configuration information. 
     The third control information is used to indicate that the third user equipment for which the reference signal is configured on the reference signal resource location information does not send the reference signal. 
     As understood by a person skilled in the art, the fact that the third user equipment does not send the reference signal only represents that a resource location indicated by the reference signal resource location information is not used to send the reference signal at a moment, but the resource location indicated by the reference signal resource location information is still used to send the reference signal as usual at another moment. This does not interfere with communication of the third user equipment. In addition, if the third user equipment does not send the reference signal at the current resource location indicated by the reference signal resource location information, after the third user equipment sends, at a next moment, the reference signal corresponding to the reference signal configuration information, a base station may then schedule the third user equipment to send the reference signal. 
     In this embodiment, the first device configures the reference signal for the third user equipment on the reference signal resource location information. Therefore, the first device needs to instruct the third user equipment, for which the reference signal is configured on the reference signal resource location information, not to send the reference signal on the reference signal resource location information, to avoid interference to transmission of the reference signal corresponding to the reference signal resource location information. 
     Correspondingly, the third user equipment receives the third control information sent by the first device, and determines that the reference signal is not sent on the reference signal resource location information. 
     In one embodiment, after the first device receives the reference signal configuration information sent by the second device, the signal transmission method may further include: sending, by the first device, fourth control information to fourth user equipment for which a physical downlink shared channel (PDSCH for short) is configured on the reference signal resource location information. 
     A reference signal of the fourth user equipment is not configured on the reference signal resource location information, and the PDSCH of the fourth user equipment is configured on the reference signal resource location information. The fourth control information includes second indication information, and the second indication information is used to indicate that the reference signal resource location information is not used to receive the PDSCH of the fourth user equipment. 
     In this embodiment, the first device does not configure the reference signal for the fourth user equipment on the reference signal resource location information, but the first device configures the PDSCH for the fourth user equipment on the reference signal resource location information. Therefore, the first device needs to notify the fourth user equipment for which the PDSCH is configured on the reference signal resource location information that the reference signal resource location information is not used to receive the PDSCH of the user equipment, so that on one hand, a conflict with transmission of the reference signal corresponding to the reference signal configuration information is avoided, and on the other hand, accuracy of receiving the PDSCH of the fourth user equipment is ensured. 
     In one embodiment, after the sending, by the first device, fourth control information to fourth user equipment for which a PDSCH is configured on the reference signal resource location information, the signal transmission method may further include: mapping, by the first device, the PDSCH to a configured resource corresponding to the PDSCH; puncturing, by the first device, the PDSCH at a resource location at which the configured resource corresponding to the PDSCH overlaps a resource location indicated by the reference signal resource location information; and sending, by the first device, a PDSCH on which puncturing processing has been performed. In other words, the first device performs puncturing at the resource location indicated by the reference signal resource location information, to send the PDSCH. 
     Alternatively, after the sending, by the first device, fourth control information to fourth user equipment for which a PDSCH is configured on the reference signal resource location information, the signal transmission method may further include: removing, by the first device from a configured resource corresponding to the PDSCH, a resource overlapping a resource location indicated by the reference signal resource location information, to obtain a first target resource corresponding to the PDSCH; mapping, by the first device, the PDSCH to the first target resource; and sending, by the first device, the PDSCH. In other words, the first device performs rate matching on the PDSCH on a resource other than the resource location indicated by the reference signal resource location information, to send the PDSCH. 
     Selection of the foregoing two implementations in which the first device sends the PDSCH may be predefined by a protocol, or may be indicated by the first control information. This is not limited in this embodiment of this application. 
     Correspondingly, the fourth user equipment receives the fourth control information sent by the first device, and receives the PDSCH based on the fourth control information. That the fourth user equipment receives the PDSCH based on the fourth control information may include: receiving, by the fourth user equipment, the PDSCH on the resource other than the resource location indicated by the reference signal resource location information in the reference signal configuration information. 
     This embodiment is mainly for the TDD system, especially for a full-duplex device, for example, a full-duplex base station. 
     It should be noted that in any one of the foregoing embodiments, control information (including the first control information, the second control information, the third control information, and the fourth control information) may be carried in higher layer signaling or physical layer signaling for transmission. The higher layer signaling may include radio resource control (Radio Resource Control, RRC for short) signaling and the like. Further, both the higher layer signaling and the physical layer signaling include common signaling and dedicated signaling. Therefore, the control information may be carried in the common signaling for transmission, or may be carried in the dedicated signaling for transmission. 
     When the control information is carried in the common signaling, only some user equipments in a current cell may receive the dedicated signaling. In this case, after receiving the common signaling, user equipments having a resource conflict perform subsequent processing based on the control information carried in the common signaling. The subsequent processing includes receiving the PDSCH, sending the PUSCH, sending the first reference signal, or the like. For details, refer to the descriptions in the foregoing embodiments. However, user equipments having no resource conflict may not perform any operation. 
     When the control information is carried in the dedicated signaling, all user equipments in a current cell may receive the common signaling. In this case, after receiving the dedicated signaling, user equipments having a resource conflict perform subsequent processing based on the control information carried in the dedicated signaling. The subsequent processing includes receiving the PDSCH, sending the PUSCH, sending the first reference signal, or the like. For details, refer to the descriptions in the foregoing embodiments. However, user equipments having no resource conflict may not perform any operation. 
     The following describes apparatus embodiments of this application, which may be used to perform the method embodiments of this application. For details that are not disclosed in the apparatus embodiments of this application, refer to the method embodiments of this application. 
       FIG. 4  is a schematic structural diagram of a signal transmission apparatus according to one embodiment of this application. This embodiment of this application provides a signal transmission apparatus. The signal transmission apparatus may be a first device. Referring to  FIG. 4 , the signal transmission apparatus  40  includes a receiving module  41 . 
     The receiving module  41  is configured to: receive reference signal configuration information sent by another device (for example, a second device), where the reference signal configuration information includes reference signal resource location information and/or a reference signal sequence parameter, the reference signal resource location information is used to indicate a time domain resource and/or a frequency domain resource for transmitting a reference signal, the reference signal sequence parameter includes all or some parameters required for generating a reference signal sequence, and the reference signal is used to detect channel quality; and receive a reference signal sent by first user equipment corresponding to the reference signal configuration information. 
     The signal transmission apparatus in this embodiment of this application exchanges the reference signal configuration information with the another device, to implement coordinated transmission of a reference signal (for example, an SRS) sent by CoMP user equipment, so that the signal transmission apparatus and the another device do not need to separately configure, for the CoMP user equipment, a resource used to transmit the reference signal. In addition, the CoMP user equipment sends a same reference signal to a plurality of devices (including the signal transmission apparatus and another device), so as to reduce delays in obtaining channel quality by different devices, and improve performance of coordinated transmission. 
     In the foregoing embodiment, the reference signal configuration information may be reference signal configuration information of coordinated multipoint transmission user equipment. For example, when being configured to receive the reference signal that is corresponding to the reference signal configuration information and that is sent by the first user equipment, the receiving module  41  is specifically configured to receive, based on the reference signal configuration information, a reference signal sent by the coordinated multipoint transmission user equipment. 
     In one embodiment, the reference signal resource location information may include pattern information of the reference signal on the time domain resource or the frequency domain resource. 
     Further, the reference signal resource location information may include time domain resource information and/or frequency domain resource information. The time domain resource information may include at least subframe location information, symbol location information, and/or the like. 
     Still further, the reference signal configuration information may include power information, and the power information is used to indicate a preset power value or power calculation information. The preset power value is a preset power value of the reference signal. The power calculation information is preset calculation information used to determine power of the reference signal. 
     Based on the foregoing embodiment, the signal transmission apparatus  40  may further include a first sending module  42 . The first sending module  42  may be configured to: after the receiving module  41  receives the reference signal configuration information sent by the another device, send first control information to second user equipment for which a PUSCH is configured on the reference signal resource location information. The first control information may include first indication information, and the first indication information is used to indicate the resource location information in the reference signal configuration information, or the first indication information is used to indicate that the reference signal resource location information is not used to transmit the PUSCH of the second user equipment. 
     It should be noted that, that the reference signal resource location information is not used to transmit the PUSCH of the second user equipment may include: puncturing the PUSCH of the second user equipment at a resource location indicated by the reference signal resource location information, or performing, by the user equipment, rate matching on the PUSCH of the second user equipment on a resource other than a resource location indicated by the reference signal resource location information. 
     In this embodiment, the signal transmission apparatus does not configure the reference signal for the second user equipment on the reference signal resource location information, but the signal transmission apparatus configures the PUSCH for the second user equipment on the reference signal resource location information. Therefore, the signal transmission apparatus needs to instruct the second user equipment, for which the PUSCH is configured on the reference signal resource location information, not to transmit the PUSCH on the reference signal resource location information. In this way, on one hand, a conflict with transmission of the reference signal corresponding to the reference signal configuration information can be avoided, and on the other hand, accuracy of receiving the PDSCH by the second user equipment can be ensured. 
     In one embodiment, the signal transmission apparatus  40  may further include a second sending module  43 . 
     The second sending module  43  is configured to: after the receiving module  41  receives the reference signal configuration information sent by the second device, send second control information to fifth user equipment for which a reference signal is configured on the reference signal resource location information. The second control information is used to indicate that the fifth user equipment for which the reference signal is configured on the reference signal resource location information sends a first reference signal, and the first reference signal is orthogonal to the reference signal sequence indicated by the SRS sequence parameter. 
     In this embodiment, the signal transmission apparatus configures the reference signal for the fifth user equipment on the reference signal resource location information. Therefore, the signal transmission apparatus needs to instruct the fifth user equipment, for which the reference signal is configured on the reference signal resource location information, to transmit, on the reference signal resource location information, the first reference signal orthogonal to the reference signal sequence indicated by the SRS sequence parameter, to avoid interference to transmission of the reference signal corresponding to the reference signal configuration information. 
     For example, the signal transmission apparatus  40  may further include a third sending module  44 . 
     The third sending module  44  is configured to: after the receiving module  41  receives the reference signal configuration information sent by the another device, send third control information to third user equipment for which a reference signal is configured on the resource location information in the reference signal configuration information. The third control information is used to indicate that the third user equipment for which the reference signal is configured on the reference signal resource location information does not send the reference signal. 
     In this embodiment, the signal transmission apparatus configures the reference signal for the third user equipment on the reference signal resource location information. Therefore, the signal transmission apparatus needs to instruct the third user equipment, for which the reference signal is configured on the reference signal resource location information, not to send the reference signal on the reference signal resource location information, to avoid interference to transmission of the reference signal corresponding to the reference signal configuration information. 
     Further, the signal transmission apparatus  40  may further include a fourth sending module  45 . 
     The fourth sending module  45  is configured to: after the receiving module  41  receives the reference signal configuration information sent by another device, send fourth control information to fourth user equipment for which a PDSCH is configured on the reference signal resource location information. A reference signal of the fourth user equipment is not configured on the reference signal resource location information, and the PDSCH of the fourth user equipment is configured on the reference signal resource location information. The fourth control information may include second indication information, and the second indication information is used to indicate that the reference signal resource location information is not used to receive the PDSCH of the fourth user equipment. 
     In this embodiment, the signal transmission apparatus does not configure the reference signal for the fourth user equipment on the reference signal resource location information, but the signal transmission apparatus configures the PDSCH for the fourth user equipment on the reference signal resource location information. Therefore, the signal transmission apparatus needs to instruct the fourth user equipment, for which the PDSCH is configured on the reference signal resource location information, not to receive the PDSCH on the reference signal resource location information, to avoid occurrence of a conflict with transmission of the reference signal corresponding to the reference signal configuration information. 
     Based on the foregoing embodiment, in an implementation, the signal transmission apparatus  40  may further include a first processing module (not shown). The first processing module may be configured to: after the fourth processing module  45  sends the fourth control information to the fourth user equipment for which the PDSCH is configured on the reference signal resource location information, map the PDSCH to a configured resource corresponding to the PDSCH; and puncture at a resource location at which the configured resource corresponding to the PDSCH overlaps a resource location indicated by the reference signal resource location information. In this case, the fourth sending module  45  may be further configured to send a PDSCH on which puncturing processing has been performed. 
     In another implementation, the signal transmission apparatus  40  may further include a second processing module (not shown). The second processing module may be configured to: after the fourth processing module  45  sends the fourth control information to the fourth user equipment for which the PDSCH is configured on the reference signal resource location information, remove, from a configured resource corresponding to the PDSCH, a resource overlapping a resource location indicated by the reference signal resource location information, to obtain a first target resource corresponding to the PDSCH; and map the PDSCH to the first target resource. In the implementation, the fourth sending module  45  may be further configured to send the PDSCH. 
       FIG. 5  is a schematic structural diagram of a signal transmission apparatus according to one embodiment of this application. This embodiment of this application provides a signal transmission apparatus. The signal transmission apparatus may be a second device. Referring to  FIG. 5 , the signal transmission apparatus  50  includes a sending module  51  and a receiving module  52 . 
     The sending module  51  is configured to send reference signal configuration information to another device, where the reference signal configuration information includes reference signal resource location information and/or a reference signal sequence parameter, the reference signal resource location information is used to indicate a time domain resource and/or a frequency domain resource for transmitting a reference signal, the reference signal sequence parameter includes all or some parameters required for generating a reference signal sequence, the reference signal configuration information is used to indicate that the another device receives a reference signal sent by user equipment corresponding to the reference signal configuration information, and the reference signal is used to detect channel quality. The receiving module  52  is configured to receive, based on the reference signal configuration information, the reference signal sent by the user equipment corresponding to the reference signal configuration information. 
     For the signal transmission apparatus in this embodiment of this application, the another device exchanges the reference signal configuration information with the signal transmission apparatus, to implement coordinated transmission of a reference signal (for example, an SRS) sent by CoMP user equipment, so that the another device and the signal transmission apparatus do not need to separately configure, for the CoMP user equipment, a resource used to transmit the reference signal. In addition, the CoMP user equipment sends a same reference signal to a plurality of devices (including another device and the signal transmission apparatus), so as to reduce delays in obtaining channel quality by different devices, and improve performance of coordinated transmission. 
     In one embodiment, the reference signal configuration information is reference signal configuration information of a coordinated multipoint transmission user equipment, and the reference signal configuration information is used to indicate that the another device receives, based on the reference signal configuration information, a reference signal sent by the coordinated multipoint transmission user equipment. 
     In one embodiment, the reference signal resource location information may be specifically pattern information of the reference signal on the time domain resource or the frequency domain resource. 
     In one embodiment, the reference signal resource location information may include time domain resource information, frequency domain resource information, and/or the like. The time domain resource information may include at least subframe location information or symbol location information. 
     In one embodiment, the reference signal configuration information may further include power information, the power information is used to indicate a preset power value or power calculation information, the preset power value is a preset power value of the reference signal, and the power calculation information is preset calculation information used to determine power of the reference signal. 
       FIG. 6  is a schematic structural diagram of a signal transmission apparatus according to one embodiment of this application. This embodiment of this application provides a signal transmission apparatus. The signal transmission apparatus may be user equipment. Referring to  FIG. 6 , the signal transmission apparatus  60  includes a receiving module  61  and a sending module  62 . 
     The receiving module  61  is configured to receive first control information sent by a first device, where a reference signal is not configured for the signal transmission apparatus on reference signal resource location information in reference signal configuration information received by the first device, but a to-be-transmitted PUSCH is configured, the first control information includes first indication information, the first indication information is used to indicate the resource location information in the reference signal configuration information, or the first indication information is used to indicate that the reference signal resource location information is not used to transmit the PUSCH of the signal transmission apparatus  60 , and the reference signal is used to detect channel quality. The sending module  62  is configured to send the PUSCH based on the first control information. 
     For the signal transmission apparatus in this embodiment of this application, the signal transmission apparatus receives the first control information sent by the first device, to implement coordinated transmission of a reference signal sent by the signal transmission apparatus, so that the first device and a second device do not need to separately configure, for the signal transmission apparatus, a resource used to transmit the reference signal. In addition, the signal transmission apparatus sends a same reference signal to a plurality of devices (including the first device and the second device), so as to reduce delays in obtaining channel quality by different devices, and improve performance of coordinated transmission. 
     In an embodiment, the sending module  62  may be specifically configured to: map the PUSCH to a configured resource corresponding to the PUSCH; puncture at a resource location at which the configured resource corresponding to the PUSCH overlaps a resource location indicated by the reference signal resource location information; and send a PUSCH on which puncturing processing has been performed. 
     In another embodiment, the sending module  62  may be specifically configured to: remove, from a configured resource corresponding to the PUSCH, a resource overlapping a resource location indicated by the reference signal resource location information, to obtain a second target resource corresponding to the PUSCH; map the PUSCH to the second target resource; and send the PUSCH. 
     Alternatively, the receiving module  61  is configured to receive second control information sent by the first device, where a reference signal is not configured for the signal transmission apparatus on the reference signal resource location information  60  in the reference signal configuration information received by the first device, the second control information is used to indicate that the signal transmission apparatus  60  sends a first reference signal, and the first reference signal is orthogonal to a reference signal indicated by an SRS sequence parameter in the SRS configuration information. The sending module  62  is configured to send the first reference signal based on the second control information. 
     For the signal transmission apparatus in this embodiment of this application, the signal transmission apparatus receives the second control information sent by the first device, to implement coordinated transmission of the reference signal (for example, an SRS) sent by the signal transmission apparatus, so that the first device and the second device do not need to separately configure, for the signal transmission apparatus, a resource used to transmit the reference signal. In addition, the signal transmission apparatus sends a same reference signal to a plurality of devices (including the first device and the second device), so as to reduce delays in obtaining channel quality by different devices, and improve performance of coordinated transmission. 
     Further, the sending module  62  may be specifically configured to send the first reference signal on a resource indicated by the reference signal resource location information that is in the reference signal configuration information and that is included in the second control information. 
       FIG. 7  is a schematic structural diagram of Embodiment 4 of a signal transmission apparatus according to this application. This embodiment of this application provides a signal transmission apparatus. The signal transmission apparatus may be user equipment. Referring to  FIG. 7 , the signal transmission apparatus  70  includes a receiving module  71  and a processing module  72 . 
     The receiving module  71  is configured to receive third control information sent by the first device, where a reference signal is configured for the signal transmission apparatus  70  on resource location information in reference signal configuration information received by the first device, and the third control information is used to indicate that the signal transmission apparatus  70  does not send a reference signal on the reference signal resource location information. The processing module  72  is configured to determine that the reference signal is not sent on the reference signal resource location information. 
     For the signal transmission apparatus in this embodiment of this application, the signal transmission apparatus receives the third control information sent by the first device, to implement coordinated transmission of the reference signal (for example, an SRS) sent by the signal transmission apparatus, so that the first device and a second device do not need to separately configure, for the signal transmission apparatus, a resource used to transmit the reference signal. In addition, the signal transmission apparatus sends a same reference signal to a plurality of devices (including the first device and the second device), so as to reduce delays in obtaining channel quality by different devices, and improve performance of coordinated transmission. 
     The structure shown in  FIG. 7  is still used as an example. Alternatively, the receiving module  71  is configured to: receive fourth control information sent by the first device, where a reference signal is not configured for the signal transmission apparatus  70  on the resource location information in the reference signal configuration information received by the first device, but a to-be-transmitted PDSCH is configured, the fourth control information includes second indication information, and the second indication information is used to indicate that the first device punctures the PDSCH at a resource location indicated by the reference signal resource location information, or the second indication information is used to indicate that the first device performs rate matching on the PDSCH a resource other than a resource location indicated by the reference signal resource location information; and receive the PDSCH based on the fourth control information. In this embodiment, the signal transmission apparatus  70  may not include the processing module  72 . 
     In one embodiment, when being configured to receive the PDSCH based on the fourth control information, the receiving module  71  is specifically configured to receive the PDSCH on the resource other than the resource location indicated by the reference signal resource location information in the reference signal configuration information. 
     For the signal transmission apparatus in this embodiment of this application, the signal transmission apparatus receives the fourth control information sent by the first device, to implement coordinated transmission of a reference signal sent by the signal transmission apparatus, so that the first device and the second device do not need to separately configure, for the signal transmission apparatus, a resource used to transmit the reference signal. In addition, the signal transmission apparatus sends a same reference signal to a plurality of devices (including the first device and the second device), so as to reduce delays in obtaining channel quality by different devices, and improve performance of coordinated transmission. 
       FIG. 8  is a schematic structural diagram of Embodiment 5 of a signal transmission apparatus according to this application. This embodiment of this application provides a signal transmission apparatus. The signal transmission apparatus may be a first device or a second device. Referring to  FIG. 8 , the signal transmission apparatus  80  includes a processing component  810 , and the processing component  810  further includes one or more processors and a transceiver  830 . The transceiver  830  further includes a receiver and/or a transmitter, and is configured to perform transmission over an air interface. The receiver and the transmitter may be disposed through integration, or may be disposed separately. Further, the signal transmission apparatus  80  may include a memory resource represented by a memory  820 , and the memory resource is used to store an instruction, for example, an application program, that can be executed by the processing component  810 . The application program stored in the memory  820  may include one or more modules that each correspond to a set of instructions. In addition, the processing component  810  is configured to execute the instructions, to perform the foregoing corresponding signal transmission method. The memory  820  may be integrated into the processing component  810 , or may be separated from the processing component  810 . This is not limited herein. 
     The signal transmission apparatus  80  may further include a wired or wireless network interface  840 . The network interface  840  is configured to connect the signal transmission apparatus  80  to another network device, for example, a core network element. 
       FIG. 9  is a schematic structural diagram of a signal transmission apparatus according to one embodiment of this application. This embodiment of this application provides a signal transmission apparatus. The signal transmission apparatus may be user equipment. Referring to  FIG. 9 , the signal transmission apparatus  90  may include a processing component  902  and a communications component  916 . The processing component  902  is configured to perform the foregoing corresponding signal transmission method, and the communications component  916  is configured to perform transmission over an air interface. 
     Further, the signal transmission apparatus  90  may include a memory  904 . The memory  904  may be integrated into the processing component  902 , or may be separated from the processing component  902 . 
     The memory  904  is configured to store an instruction, for example, an application program, that can be executed by the processing component  902 . 
     For example, the signal transmission apparatus  90  may further include one or more of the following components: a power supply component  906 , a multimedia component  908 , an audio component  910 , an input/output (input/output, I/O for short) interface  912 , and a sensor component  914 . 
     In an example, the processing component  902  usually controls an overall operation of the signal transmission apparatus  90 , for example, an operation related to display, data communication, a camera operation, and a recording operation. The processing component  902  may include one or more processors  920  to execute an instruction, to complete all of or some of the operations of the foregoing method. In addition, the processing component  902  may include one or more modules, so that the processing component  902  interacts with another component. For example, the processing component  902  may include a multimedia module, so that the multimedia component  908  interacts with the processing component  902 . 
     The memory  904  is configured to store various types of data to support the operation of the signal transmission apparatus  90 . An example of the data includes an instruction, contact data, address book data, a message, an image, a video, and the like of any application program or method that are used to perform an operation on the signal transmission apparatus  90 . The memory  904  may be implemented by any type of volatile storage device, any type of volatile non-volatile storage device, or a combination thereof, such as a static random access memory (SRAM for short), an electrically erasable programmable read-only memory (EEPROM for short), an erasable programmable read-only memory (EPROM for short), a programmable read-only memory (PROM for short), a read-only memory (ROM for short), a magnetic memory, a flash memory, a magnetic disk, or an optical disc. 
     The power supply component  906  supplies power to various components of the signal transmission apparatus  90 . The power supply component  906  may include a power management system, one or more power supplies, and another component related to generation, management, and distribution of power for the signal transmission apparatus  90 . 
     The multimedia component  908  includes a screen providing an output interface between the signal transmission apparatus  90  and a user. In some embodiments, the screen may include a liquid crystal display (LCD for short) and a touch panel (TP for short). If the screen includes the touch panel, the screen may be implemented as a touchscreen, to receive an input signal from the user. The touch panel includes one or more touch sensors to sense a touch, sliding, and a gesture that is on the touch panel. The touch sensor not only may sense a boundary of a touch action or a sliding action, but also detects duration and pressure that are related to the touch operation or the sliding operation. In some embodiments, the multimedia component  908  includes a front-facing camera and/or a rear-facing camera. When the signal transmission apparatus  90  is in an operation mode, for example, in a shooting mode or in a video mode, the front-facing camera and/or the rear-facing camera may receive external multimedia data. Each front-facing camera and each rear-facing camera may be a fixed optical lens system or may have a focal length and an optical zoom capability. 
     The audio component  910  is configured to output and/or input an audio signal. For example, the audio component  910  includes a microphone (MIC for short). When the signal transmission apparatus  90  is in an operation mode, for example, in a call mode, a recording mode, or a voice recognition mode, the microphone is configured to receive an external audio signal. The received audio signal may be further stored in the memory  904  or sent by using the communications component  916 . In some embodiments, the audio component  910  further includes a speaker, configured to output an audio signal. 
     The I/O interface  912  provides an interface between the processing component  902  and a peripheral interface module, and the peripheral interface module may be a keyboard, a click wheel, buttons, or the like. These buttons may include, but are not limited to, a home button, a volume button, a startup button, and a lock button. 
     The sensor component  914  includes one or more sensors, configured to provide status estimation in various aspects for the signal transmission apparatus  90 . For example, the sensor component  914  may detect an on/off state of the signal transmission apparatus  90  and relative positioning of the component. For example, the component is a display or a small keyboard of the signal transmission apparatus  90 . The sensor component  914  may further detect a location change of the signal transmission apparatus  90  or a component of the signal transmission apparatus  90 , existence or nonexistence of contact between the user and the signal transmission apparatus  90 , an orientation or acceleration/deceleration of the signal transmission apparatus  90 , and a temperature change of the signal transmission apparatus  90 . The sensor component  914  may include a proximity sensor, configured to detect existence of a nearby object when there is no physical contact. The sensor component  914  may further include an optical sensor, such as a complementary metal-oxide-semiconductor (CMOS for short), a charge-coupled device (CCD for short), or a photosensitive imaging element, and is configured in an imaging application. In some embodiments, the sensor component  914  may further include an acceleration sensor, a gyro sensor, a magnetic sensor, a pressure sensor, or a temperature sensor. 
     The communications component  916  is configured to enable the signal transmission apparatus  90  to communicate with another device in a wired manner or wirelessly. The signal transmission apparatus  90  may access a wireless network according to a communication standard, such as Wireless Fidelity (Wi-Fi for short), 2G, 3G, or a combination thereof. In an example of an embodiment, the communications component  916  receives a broadcast signal or broadcast-related information from an external broadcast management system by using a broadcast channel. In an example of an embodiment, the communications component  916  further includes a near field communication (NFC for short) module, to facilitate short-range communication. For example, the NFC module may be implemented based on a radio frequency identification (RFID for short) technology, an infrared data association (IrDA for short) technology, an ultra-wideband (UWB for short) technology, a Bluetooth (BT for short) technology, and another technology. 
     In an example of an embodiment, the signal transmission apparatus  90  may be implemented by one or more application-specific integrated circuits (ASIC for short), a digital signal processor (DSP for short), a digital signal processing device (DSPD for short), a programmable logic device (PLD for short), a field programmable gate array (FPGA for short), a controller, a microcontroller, a microprocessor, or another electronic element, and is configured to perform the foregoing signal transmission method. 
     A non-transitory computer readable storage medium is provided. When an instruction in the storage medium is executed by a processor in a first device, a second device, or user equipment, the first device, the second device, or the user equipment can perform the foregoing corresponding signal transmission method. 
     An embodiment of this application further provides a communications system. The communications system includes the first device and/or the second device described in the foregoing embodiments. 
     Further, the communications system may include the user equipment described in the foregoing embodiments. For specific descriptions, refer to the foregoing embodiments. Details are not described herein. 
     According to another embodiment, a signal transmission method includes sending reference signal configuration information to a first device, wherein the reference signal configuration information comprises at least one of reference signal resource location information or a reference signal sequence parameter, wherein the reference signal resource location information is used to indicate at least one of a time domain resource or a frequency domain resource for transmitting a reference signal, the reference signal sequence parameter comprises at least some parameters required for generating a reference signal sequence, the reference signal configuration information is used to indicate that the first device receives a reference signal from user equipment corresponding to the reference signal configuration information, and the reference signal is used to detect channel quality; and receiving, based on the reference signal configuration information, a reference signal from first user equipment corresponding to the reference signal configuration information. 
     The reference signal resource location information comprises at least one of time domain resource information or frequency domain resource information, wherein the time domain resource information comprises at least one of subframe location information or symbol location information; or the reference signal resource location information comprises pattern information of the reference signal on the time domain resource or the frequency domain resource. 
     According to another embodiment, a signal transmission method includes receiving first control information from a first device, wherein a reference signal is not configured on reference signal resource location information in reference signal configuration information received by the first device, but a physical uplink shared channel (PUSCH) to be transmitted is configured, the first control information comprises first indication information, and the first indication information is used to indicate the reference signal resource location information in the reference signal configuration information, or the first indication information is used to indicate that the reference signal resource location information is not used to transmit the PUSCH, and the reference signal is used to detect channel quality; and sending the PUSCH based on the first control information. 
     The sending the PUSCH based on the first control information includes mapping the PUSCH to a configured resource corresponding to the PUSCH; performing puncturing at a resource location at which the configured resource corresponding to the PUSCH overlaps a resource location indicated by the reference signal resource location information; and sending a PUSCH on which puncturing processing has been performed; or removing, from a configured resource corresponding to the PUSCH, a resource overlapping a resource location indicated by the reference signal resource location information, to obtain a second target resource corresponding to the PUSCH; mapping the PUSCH to the second target resource; and sending the PUSCH. 
     According to another embodiment, a signal transmission method includes receiving third control information from a first device, wherein a reference signal is configured on resource location information in reference signal configuration information received by the first device, the third control information is used to indicate that the reference signal is not sent on the reference signal resource location information, and the reference signal is used to detect channel quality; and determining that the reference signal is not sent on the reference signal resource location information. 
     According to another embodiment, a signal transmission method includes receiving fourth control information from a first device, wherein a reference signal is not configured on resource location information in reference signal configuration information received by the first device, but a physical downlink shared channel (PDSCH) to be transmitted is configured, the fourth control information comprises second indication information, the second indication information is used to indicate that the first device punctures the PDSCH of user equipment at a resource location indicated by the reference signal resource location information, or the second indication information is used to indicate that the first device performs rate matching on the PDSCH of user equipment on a resource other than a resource location indicated by the reference signal resource location information, and the reference signal is used to detect channel quality; and receiving the PDSCH based on the fourth control information. 
     In the several embodiments provided in this application, it should be understood that the disclosed device and method may be implemented in another manner. For example, the described device embodiment is merely an example. For example, the unit or unit division is merely logical function division and may be other division during actual implementation. For example, a plurality of units or modules may be combined or integrated into another system, or some features may be ignored or not performed. In addition, the displayed or discussed mutual couplings, direct couplings, or communication connections may be implemented by using some interfaces. The indirect couplings or communication connections between the devices or modules may be implemented in electrical, mechanical, or other forms. 
     The modules described as separate parts may or may not be physically separate, and parts displayed as modules may or may not be physical modules, may be located in one position, or may be distributed on a plurality of network units. Some or all of the modules may be selected according to actual needs to achieve the objectives of the solutions of the embodiments. 
     A person of ordinary skill in the art may understand that all or some of the operations of the method embodiments may be implemented by a program instructing relevant hardware. The program may be stored in a computer-readable storage medium. When the program runs, the operations of the method embodiments are performed. The foregoing storage medium includes any medium that can store program code, such as a ROM, a RAM, a magnetic disk, or an optical disc. 
     Finally, it should be noted that the foregoing embodiments are merely intended for describing the technical solutions of this application other than limiting this application. Although this application is described in detail with reference to the foregoing embodiments, a person of ordinary skill in the art should understand that they may still make modifications to the technical solutions described in the foregoing embodiments or make equivalent replacements to some or all technical features thereof, without departing from the scope of the technical solutions of the embodiments of this application.