CN106879076B - Data transmission method and device - Google Patents

Abstract

The present application discloses a method and a device for data transmission, which relate to the field of communication technologies and can solve the problem of low efficiency in transmitting service data by a base station using an unlicensed frequency band. The data transmission method of the present application includes: when a base station needs to send data to a destination terminal, the base station acquires the user group identifier of the destination terminal, and the base station locally acquires a valid CSI measurement result corresponding to the user group identifier of the destination terminal; The CSI measurement result sends data to the destination terminal. This application applies to the process of transferring data.

Description

A method and device for data transmission

technical field

The present application relates to the field of communication technologies, and in particular, to a method and apparatus for data transmission.

Background technique

In the Long Term Evolution (LTE) frequency division duplex (Frequency Division Dual, FDD) system, when the base station sends data to the user equipment, it needs to first request the user equipment to perform Channel State Information (Channel State Information, CSI) measurement and Feedback the CSI measurement results. The base station learns the current downlink channel conditions from the feedback CSI measurement results, and selects a corresponding transmission scheme to achieve high-speed transmission of downlink data. Since the LTE system works in the licensed frequency band, the base station has the absolute right to use the licensed frequency band. Therefore, the base station can always receive the CSI measurement result fed back by the terminal and send data to the terminal.

In order to meet the ever-increasing demand for data services, communication operators also begin to use resource-rich unlicensed frequency bands to transmit data, for example: Licensed Assisted Access (LAA) system of LTE. In the unlicensed frequency band, in order to avoid interference between different systems, the LAA system needs to monitor the channel before transmitting data, and perform Clear Channel Assessment (CCA), and then use the unlicensed frequency band to ensure that the channel is idle. data transmission. In addition, in order to ensure that the opportunities for different systems to use the unlicensed frequency band are relatively fair, and to avoid the system that first occupies the unlicensed frequency band from occupying the unlicensed frequency band, it is generally required that the continuous data transmission time of the system using the unlicensed frequency band cannot exceed the maximum transmission time. Therefore, the data transmission of the LAA system on the unlicensed frequency band is also discontinuous and limited by the maximum transmission time.

If the LAA system adopts the existing CSI feedback mechanism, the process from the base station sending the reference signal to the terminal until the base station receiving the CSI measurement result fed back by the terminal has taken up most of the continuous transmission time, so that the base station actually uses Because there is not much time to transmit service data, and the amount of service data to be transmitted is also limited, the efficiency of the LAA system to transmit service data using unlicensed frequency bands is reduced.

SUMMARY OF THE INVENTION

The present application provides a method and device for data transmission, which can solve the problem of low efficiency in transmitting service data by a base station using an unlicensed frequency band.

To achieve the above object, the application adopts the following technical solutions:

In a first aspect, the present application provides a method for data transmission, the method comprising:

When the base station needs to send data to the destination terminal, the base station obtains the user group identifier of the destination terminal, wherein the terminals in the same group can share a user group identifier, and the terminals with the same user group identifier can share the channel state information CSI measurement result;

obtaining, by the base station locally, a valid CSI measurement result corresponding to the user group identifier of the destination terminal;

The base station sends data to the destination terminal according to the effective CSI measurement result.

In a second aspect, the present application provides an apparatus for data transmission, the apparatus comprising:

a processing unit, configured to acquire the user group identifier of the destination terminal, wherein the terminals in the same group can share a user group identifier, and the terminals with the same user group identifier can share the channel state information CSI measurement result;

Obtain a valid CSI measurement result corresponding to the user group identifier of the destination terminal locally;

A sending unit, configured to send data to the destination terminal according to the effective CSI measurement result obtained by the processing unit.

In a method and device for data transmission provided by the present application, when a base station needs to send data to a destination terminal, it directly invokes the effective CSI measurement result in the packet according to the user group identifier, and sends downlink data to the destination terminal. Compared with the prior art, the base station requires the terminal to perform CSI measurement and feed back the CSI measurement result before sending downlink data each time. However, in the unlicensed frequency band, the process of CSI measurement and feedback takes a long time, resulting in low efficiency for the base station to transmit service data using the unlicensed frequency band. In this application, the base station directly calls the valid CSI measurement results in the same group, which saves the time for the terminal to perform CSI measurement and feedback. Therefore, more service data can be transmitted within the transmittable time, which improves the utilization of unauthorized CSI by the base station. The efficiency of transmitting service data in the frequency band.

Description of drawings

In order to illustrate the technical solutions in the embodiments of the present application more clearly, the following briefly introduces the drawings required in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can also be obtained from these drawings without any creative effort.

FIG. 1 is a schematic structural diagram of a communication system according to an embodiment of the present application;

2 is a flowchart of a method for data transmission provided by an embodiment of the present application;

3 is a flowchart of another method for data transmission provided by an embodiment of the present application;

4 is a flowchart of another method for data transmission provided by an embodiment of the present application;

FIG. 5 is a flowchart of still another data transmission method provided by an embodiment of the present application;

6 is a schematic structural diagram of a data transmission apparatus according to an embodiment of the present application;

FIG. 7 is a schematic structural diagram of another data transmission apparatus provided by an embodiment of the present application;

FIG. 8 is a schematic structural diagram of a data transmission system according to an embodiment of the present application.

Detailed ways

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, but not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

A data transmission method provided by an embodiment of the present application can be applied to the communication system shown in FIG. 1 , where the communication system includes a base station and at least one terminal, as shown in FIG. 2 , and the method flow of the present application is shown in FIG. 2 , Specifically include:

101. When the base station needs to send data to a destination terminal, the base station acquires the user group identifier of the destination terminal.

Specifically, before the base station obtains the user group identifier of the destination terminal, the base station needs to group the terminals in the service area in advance, and set a user group identifier for each group, and the user group identifier is unique at least within the base station , which is used to distinguish other user groups in the base station, and terminals in the same group share a user group identifier.

The base station may divide the served terminals into at least two groups according to the geographic locations of the served terminals. The base station may also divide the served terminal into at least two groups according to the path loss between itself and the served terminal. Among them, the way to obtain the location can be obtained by using the Global Positioning System (Global Positioning System, GPS), or can be obtained by using the Observed Time Difference of Arrival (OTDOA) method, or the uplink time difference of arrival ( Uplink Time Difference of arrival, U-TDOA) method. The present application does not limit the implementation manner of grouping.

Specifically, after the base station groups the terminals in the service area, the terminals in each group have the same characteristics, such as the same location or the same path loss. In a low mobility scenario, the spatial characteristics and channel quality are relatively static. In this case, these same characteristics indicate that the channel conditions between the base station and these terminals are similar, and the same CSI measurement results can be shared within a certain period of time. For example, it is assumed that there are three terminals in a group in the service area of the base station, namely terminal A, terminal B and terminal C, and the channel conditions of these three terminals are similar. If terminal A feeds back the CSI measurement result, when the base station needs to send downlink data to terminal B or C, it can directly use the CSI measurement result to learn the channel conditions, and select an appropriate transmission scheme to send downlink data to terminal B or terminal C. Therefore, when the base station needs to send data to the target terminal, the CSI measurement results in the same group can be shared, and the user group identifier of the target terminal needs to be obtained first.

102. The base station obtains a valid CSI measurement result corresponding to the user group identifier of the destination terminal locally.

Wherein, the base station locally pre-stores the CSI measurement result corresponding to the user group identifier, and the CSI measurement result is time-sensitive, that is, valid within a preset time, and invalid beyond the preset time. It should be noted that each time the base station sends downlink data to the terminal in the same group, it will first call the effective CSI measurement result in the group. When there is no valid CSI measurement result in the packet, the base station will send a reference signal to the terminal, requesting the terminal to perform CSI measurement, and then receive a new valid CSI measurement result. Therefore, in each group, the base station locally stores at most one valid CSI measurement result.

103. The base station sends data to the destination terminal according to the effective CSI measurement result.

Specifically, the base station selects an appropriate modulation, demodulation and coding mode, resource allocation type and specific transmission scheme according to the acquired valid CSI measurement results and the receiving capability of the destination terminal, and sends data to the destination terminal.

In a data transmission method provided by the present application, when a base station needs to send data to a destination terminal, it directly invokes the effective CSI measurement result in the packet according to the user group identifier, and sends downlink data to the destination terminal. Compared with the prior art, the base station requires the terminal to perform CSI measurement and feed back the CSI measurement result before sending downlink data each time. However, in the unlicensed frequency band, the process of CSI measurement and feedback takes a long time, resulting in low efficiency for the base station to transmit service data using the unlicensed frequency band. In this application, the base station directly calls the valid CSI measurement results in the same group, which saves the time for the terminal to perform CSI measurement and feedback. Therefore, more service data can be transmitted within the transmittable time, which improves the utilization of unauthorized CSI by the base station. The efficiency of transmitting service data in the frequency band.

Further, on the basis of FIG. 2 , considering that a data transmission method provided by this embodiment of the present application needs to pre-store CSI measurement results for each group after grouping, as shown in FIG. 3 , before step 102, the Methods also include:

201. The base station sends a first reference signal to a specified number of terminals in each group respectively.

Wherein, the first reference signal is used to instruct a specified number of terminals in each group to perform CSI measurement.

Specifically, after grouping, the base station selects a specified number of terminals from each group, and sends a reference signal to each selected terminal, requiring these terminals to perform CSI measurement and feed back the CSI measurement results. The setting of the specified number may be determined according to the geographical location of the terminal, or the path loss from the base station to the terminal.

Exemplarily, it is assumed that the base station divides the terminals in the service area into 3 groups, which are named as the first group, the second group and the third group respectively. The first group includes terminal A and terminal B, the second group includes terminal C, and the third group includes terminal D and terminal E. Taking the specified number of 1 as an example, the base station selects one terminal from the first group, the second group, and the third group, respectively terminal A, terminal C, and terminal E, and sends reference signals to these three terminals, requesting The three terminals perform CSI measurements.

202. The base station respectively receives the CSI measurement results fed back by the terminals in each group.

Exemplarily, with reference to the example of step 201, the base station receives three CSI measurement results fed back by terminal A, terminal C, and terminal E, respectively.

203. The base station stores each received CSI measurement result in correspondence with the user group identifier of the terminal that sends each CSI measurement result.

Specifically, when receiving the CSI measurement result fed back by the selected terminal, the base station acquires the user group identifier of the terminal, establishes a corresponding relationship between the user group identifier and the CSI measurement result, and stores it locally. In this way, the base station prestores a CSI measurement result for each group.

Exemplarily, in combination with the examples of steps 201 and 202, the base station stores the CSI measurement result fed back by terminal A corresponding to the user group identifier of the first group, and stores the CSI measurement result fed back by terminal C corresponding to the user group identifier of the second group. , and store the CSI measurement result fed back by the terminal E corresponding to the user group identifier of the third group.

204. When the existence duration of the CSI measurement result exceeds the valid survival time limit, the base station sets the CSI measurement result to be invalid.

Specifically, since channel conditions are time-varying, the base station needs to set an effective lifetime for the stored CSI measurement results according to system characteristics and channel changes.

While storing the CSI measurement result, the base station sets the CSI measurement result to be valid, starts the counter, and sets the initial value of the counter to zero. Every time a transmission time interval (Transmission Time Interval, TTI) passes, the value of the counter is automatically incremented by 1, and when the value of the counter exceeds the preset value, the CSI measurement result is set as invalid. Among them, the preset value is the number of transmission time intervals included in the effective survival time limit. Therefore, when the value of the counter exceeds the preset value, the existence time of the CSI measurement result also exceeds the effective survival time limit. The measurement result is set to invalid.

On the basis of FIG. 2 , there may be a situation where the base station does not obtain valid CSI measurement results. In this case, the base station needs to obtain the CSI measurement results in other ways. Therefore, in another possible implementation provided by the embodiment of the present application, As shown in FIG. 4, before step 103, steps 301 to 302 can also be performed:

301. When the base station does not obtain a valid CSI measurement result, the base station sends a second reference signal to the target terminal by using an unlicensed frequency band.

Wherein, the second reference signal is used to instruct the target terminal to perform CSI measurement.

Specifically, when the base station does not obtain valid CSI measurement results, it includes the fact that the valid CSI measurement results are invalid, or the destination terminal does not belong to any existing group, etc. At this time, the base station needs to send a second reference signal to the destination terminal, requesting The destination terminal performs CSI measurement.

302. The base station receives the CSI measurement result fed back by the target terminal from the licensed frequency band.

Specifically, after the destination terminal receives the second reference signal sent by the base station, the destination terminal performs CSI measurement, and sends the CSI measurement result to the base station, where the CSI measurement result may carry the unlicensed frequency band used by the second reference signal Information. After receiving the CSI measurement result sent by the target terminal, the base station can obtain the reference information corresponding to the CSI measurement result according to the information of the unlicensed frequency band carried in the CSI measurement result, and further obtain the reference information according to the second reference signal and the CSI measurement result. Under the current channel conditions of the downlink, select a corresponding transmission scheme to send downlink data to the destination terminal.

Compared with the data transmission method provided by the embodiments of the present application, the base station receives the CSI measurement result through the unlicensed frequency band. Since a continuous data transmission in the unlicensed frequency band is limited by the maximum transmission time, it is difficult to guarantee The base station can receive the CSI measurement result fed back by the terminal, which may waste the opportunity of CSI measurement performed by the local destination terminal and feedback of the CSI measurement result, resulting in a waste of network resources. In the present application, since the CSI measurement result is received through the licensed frequency band, and since the base station has the absolute right to use the licensed frequency band, the base station can guarantee to receive the CSI measurement result, which improves the efficiency of data transmission.

In an application scenario of the embodiment of the present application, when the data transmission method provided by the embodiment of the present application is applied to the LAA system, as shown in FIG. 5 , the method specifically includes:

401. The base station groups the terminals in the service area, and sets a user group identifier for each group.

For the specific implementation of this step, reference may be made to step 101 .

402. The base station performs CCA.

Specifically, since the LAA system works in an unlicensed frequency band, in order to avoid interference between different systems, the LAA system needs to monitor the channel before transmitting data, and perform CCA. CCA detects the signal energy and compares it with the threshold, and judges according to the comparison result. The busy and idle state of the channel, and data transmission is performed when the channel is guaranteed to be idle. The specific implementation of the CCA refers to the prior art, and details are not repeated here.

403. After detecting that the channel is idle, the base station sends a reference signal to the first terminal.

Wherein, the first terminal is any terminal operating in the service area of the base station.

Specifically, if the base station detects that the channel is idle, it occupies channel resources. After occupying the channel resource, the reference signal is sent to the first terminal by using the unlicensed frequency band.

404. The first terminal performs CSI measurement according to the received reference signal.

405. The first terminal sends the CSI measurement result to the base station.

Specifically, since the process from the base station sending the reference signal to the first terminal completing the CSI measurement takes a long time, in order to ensure that the CSI measurement result sent by the first terminal can be successfully received by the base station, the first terminal can use the licensed frequency band to send the CSI measurement result.

406. After receiving the CSI measurement result, the base station stores the CSI measurement result and the user group identifier of the first terminal correspondingly locally, and starts a counter.

For the specific implementation of this step, reference may be made to steps 201-203.

407. The base station sends downlink data to the first terminal according to the received CSI measurement result.

408. When the base station needs to send downlink data to the second terminal, the base station determines whether the user group identifier of the second terminal is the same as the user group identifier of the first terminal.

Wherein, the second terminal is another terminal other than the first terminal operating in the service area of the base station.

Specifically, when the user group identifier of the second terminal is different from the user group identifier of the first terminal, the base station sends reference information to the second terminal, requesting the second terminal to perform CSI measurement and feed back the CSI measurement result.

409. When the user group identifier of the second terminal is the same as the user group identifier of the first terminal, the base station determines whether the CSI measurement result of the first terminal is valid.

Specifically, the base station judges whether the value of the counter exceeds the valid lifetime set for the CSI measurement result of the first terminal, if not, the CSI measurement result is valid; otherwise, the CSI measurement result is invalid.

Wherein, when the CSI measurement result of the first terminal is invalid, the base station sends a reference signal to the second terminal, requesting the second terminal to perform CSI measurement and feed back the CSI measurement result, and the base station then sends data to the second terminal according to the received CSI measurement result .

410. When the CSI measurement result of the first terminal is valid, the base station invokes the CSI measurement result of the first terminal to send downlink data to the second terminal.

An embodiment of the present invention further provides an apparatus 60 for data transmission, as shown in FIG. 6 , the apparatus includes:

The processing unit 61 is used to obtain the user group identification of the destination terminal, wherein the terminals in the same group can share the same channel state information CSI measurement result; obtain the effective CSI measurement result corresponding to the user group identification of the destination terminal from the local.

The sending unit 62 is configured to send data to the destination terminal according to the effective CSI measurement result obtained by the processing unit 61 .

In a data transmission device provided by the present application, when a base station needs to send data to a destination terminal, it directly invokes the effective CSI measurement result in the packet according to the user group identifier, and sends downlink data to the destination terminal. Compared with the prior art, the base station requires the terminal to perform CSI measurement and feed back the CSI measurement result before sending downlink data each time. However, in the unlicensed frequency band, the process of CSI measurement and feedback takes a long time, resulting in low efficiency for the base station to transmit service data using the unlicensed frequency band. In this application, the base station directly calls the valid CSI measurement results in the same group, which saves the time for the terminal to perform CSI measurement and feedback. Therefore, more service data can be transmitted within the transmittable time, which improves the utilization of unauthorized CSI by the base station. The efficiency of transmitting service data in the frequency band.

Further, the processing unit 61 is further configured to divide the served terminal into at least two groups according to the geographic location of the terminal served by the base station; or, according to the path loss between the base station and the served terminal, divide the served terminal into at least two groups. The served terminals are divided into at least two groups.

Further, an embodiment of the present application further provides a data transmission device 70 , as shown in FIG. 7 , the device 70 further includes a receiving unit 71 and a storage unit 72 .

The sending unit 62 is further configured to send a first reference signal to a specified number of terminals in each group respectively, where the first reference signal is used to instruct the specified number of terminals in each group to perform CSI measurement.

The receiving unit 71 is configured to respectively receive the CSI measurement results fed back by the terminal in each group.

The storage unit 72 is configured to store each CSI measurement result received by the receiving unit 71 in correspondence with the user group identifier of the terminal sending each CSI measurement result.

The processing unit 61 is further configured to, by the base station, set the CSI measurement result to be invalid when the existence duration of the CSI measurement result exceeds the valid survival time limit.

Further, the sending unit 62 is further configured to use an unlicensed frequency band to send a second reference signal to the target terminal, where the second reference signal is used to instruct the target terminal to perform CSI measurement.

The receiving unit 71 is further configured to receive the CSI measurement result fed back by the destination terminal from the licensed frequency band.

Further, the processing unit 61 is further configured to start a counter when the storage unit 72 stores the CSI measurement result; every time a transmission time interval TTI passes, the value of the counter is automatically incremented by 1; When the value of the counter exceeds the preset value, the CSI measurement result is set to be invalid.

As shown in FIG. 8, an embodiment of the present invention provides a terminal for data transmission, including: a processor 801, a memory 802, a transceiver 803, and a bus 804, and the processor 801, the memory 802, and the transceiver 803 pass through the bus 804 communicate with each other. Wherein, the memory 802 is used to store multiple instructions to realize the data transmission provided by the present invention, and the processor 801 executes the multiple instructions to realize that when the base station needs to send data to the destination terminal, the base station obtains the The user group identifier of the destination terminal, the base station obtains the valid CSI measurement result corresponding to the user group identifier of the destination terminal locally; the base station sends data to the destination terminal according to the valid CSI measurement result. The terminals in the same group may share the same channel state information CSI measurement result.

Further, the processor 801 is further configured for the base station to divide the served terminal into at least two groups according to the geographic location of the served terminal; Path loss, dividing the served terminal into at least two packets.

Further, the processor 801 is further configured for the base station to send a first reference signal to a specified number of terminals in each group respectively, where the first reference signal is used to instruct the specified number of terminals in each group to CSI measurement; the base station respectively receives the CSI measurement results fed back by the terminals in each group; when the base station stores each received CSI measurement result corresponding to the user group identifier of the terminal sending each CSI measurement result; When the existence duration of the CSI measurement result exceeds the valid lifetime, the base station sets the CSI measurement result to be invalid.

Further, the processor 801 is further configured to send a second reference signal to the destination terminal by using the unlicensed frequency band when the base station does not obtain a valid CSI measurement result, and the second reference signal is used for Instruct the target terminal to perform CSI measurement; the base station receives the CSI measurement result fed back by the target terminal from the licensed frequency band.

Further, the processor 801 is also used for the base station to start a counter while storing the CSI measurement result; every time a transmission time interval TTI passes, the value of the counter is automatically incremented by 1; when the value of the counter is When the preset value is exceeded, the base station sets the CSI measurement result to be invalid.

The processor 801 in this embodiment of the present invention may be a processor, or may be a general term for multiple processing elements. For example, the processor 801 may be a central processing unit (Central Processing Unit, CPU for short), a specific integrated circuit (Application Specific Integrated Circuit, ASIC for short), or is configured to implement one or more embodiments of the present invention An integrated circuit, for example: one or more microprocessors (digital signal processor, DSP for short), or one or more Field Programmable Gate Array (Field Programmable Gate Array, FPGA for short).

The memory 802 may be a storage device or a general term for a plurality of storage elements, and is used to store executable program codes and the like. And the memory 802 may include random access memory (RAM), and may also include non-volatile memory (non-volatile memory), such as disk memory, flash memory (Flash), and the like.

The bus 804 may be an Industry Standard Architecture (ISA) bus, a Peripheral Component (PCI) bus, an Extended Industry Standard Architecture (EISA) bus, or the like. The bus 804 can be divided into an address bus, a data bus, a control bus, and the like. For ease of presentation, only one thick line is used in FIG. 8, but it does not mean that there is only one bus or one type of bus.

The various embodiments in this specification are described in a progressive manner, and the same and similar parts between the various embodiments may be referred to each other, and each embodiment focuses on the differences from other embodiments.

place. In particular, for the apparatus embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and reference may be made to the partial description of the method embodiment for related parts.

Those of ordinary skill in the art can understand that all or part of the processes in the methods of the above embodiments can be implemented by instructing the relevant hardware through a computer program, and the program can be stored in a computer-readable storage medium, and the program is During execution, it may include the processes of the embodiments of the above-mentioned methods. The storage medium may be a magnetic disk, an optical disk, a read-only memory (Read-Only Memory, ROM), or a random access memory (Random Access Memory, RAM) or the like.

The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art who is familiar with the technical scope disclosed by the present invention can easily think of changes or substitutions. All should be included within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims (8)

1. A method of data transmission, comprising:

a base station respectively sends first reference signals to a specified number of terminals in each group, and the first reference signals are used for indicating the specified number of terminals in each group to carry out CSI measurement; determining the specified quantity according to the geographic position of the terminal or the path loss from the base station to the terminal;

the base station receives CSI measurement results fed back by the terminals in each group respectively;

the base station respectively stores each received CSI measurement result and the user group identification of the terminal which sends each CSI measurement result correspondingly;

when the existence duration of the CSI measurement result exceeds the effective survival time limit, the base station sets the CSI measurement result to be invalid;

when a base station needs to send data to a target terminal, the base station acquires a user group identifier of the target terminal, wherein terminals in the same group can share one user group identifier, and terminals with the same user group identifier can share a Channel State Information (CSI) measurement result;

the base station locally acquires an effective CSI measurement result corresponding to the user group identification of the target terminal;

and the base station sends data to the target terminal according to the effective CSI measurement result.

2. The method of claim 1, wherein before the base station acquires the user group identity of the destination terminal, the method further comprises:

the base station divides the served terminals into at least two groups according to the geographical positions of the served terminals; or,

the base station divides the served terminals into at least two groups according to the path loss between the base station and the served terminals.

3. The method according to claim 1, wherein the setting, by the base station, the CSI measurement result to invalid when the existence duration of the CSI measurement result exceeds the valid survival duration specifically includes:

the base station starts a counter while storing the CSI measurement result;

the numerical value of the counter is automatically increased by 1 every time a transmission time interval TTI passes;

and when the value of the counter exceeds a preset value, the base station sets the CSI measurement result to be invalid.

4. The method according to any of claims 1-3, wherein before the base station sends data to the destination terminal according to the valid CSI measurement result, the method further comprises:

when the base station does not obtain a valid CSI measurement result, the base station sends a second reference signal to the target terminal by using an unauthorized frequency band, wherein the second reference signal is used for indicating the target terminal to carry out CSI measurement;

and the base station receives the CSI measurement result fed back by the target terminal from the authorized frequency band.

5. An apparatus for data transmission, comprising:

the processing unit is used for acquiring a user group identifier of a target terminal, wherein the terminals in the same group can share one user group identifier, the terminals with the same user group identifier can share a Channel State Information (CSI) measurement result, and the processing unit is also used for setting the CSI measurement result to be invalid by the base station when the existence duration of the CSI measurement result exceeds the effective survival time limit;

obtaining an effective CSI measurement result corresponding to the user group identification of the target terminal from the local;

a sending unit, configured to send data to the destination terminal according to the valid CSI measurement result obtained by the processing unit, and further configured to send first reference signals to a specified number of terminals in each group, where the first reference signals are used to indicate the specified number of terminals in each group to perform CSI measurement; determining the specified quantity according to the geographic position of the terminal or the path loss from the base station to the terminal;

a receiving unit, configured to receive CSI measurement results fed back by terminals in each group respectively;

and the storage unit is used for correspondingly storing each CSI measurement result received by the receiving unit and the user group identification of the terminal sending each CSI measurement result.

6. The apparatus of claim 5, wherein the processing unit is further configured to divide the served terminals into at least two groups according to the geographic locations of the served terminals of the base station; or,

the served terminals are divided into at least two groups according to the path loss between the base station and the served terminals.

7. The apparatus of claim 5, wherein the processing unit is further configured to start a counter while the storage unit stores the CSI measurement result;

the numerical value of the counter is automatically increased by 1 every time a transmission time interval TTI passes;

and when the value of the counter exceeds a preset value, setting the CSI measurement result to be invalid.

8. The apparatus according to any of claims 5-7, wherein the transmitting unit is further configured to transmit a second reference signal to the destination terminal using an unlicensed frequency band, where the second reference signal is used to instruct the destination terminal to perform CSI measurement;

the receiving unit is further configured to receive a CSI measurement result fed back by the destination terminal from an authorized frequency band.

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