CN107800467A - beam selection method and device - Google Patents

Abstract

The present application provides a beam selection method. The method includes: a. Pre-configuring beams of the first to Kth grades and the corresponding relationship between the beams of each grade; b. Sending each beam of the first grade to the user terminal UE; c. Receiving the beam index fed back by the UE; d 1. Determine the beam corresponding to the received beam index, if the determined beam is not the K-th beam, send each beam in the next-level beam corresponding to the determined beam to the UE, and then return c; if the determined beam is the K-th beam For K-level beams, the determined beams are used as candidate beams selected by the UE. Through the present application, the overhead of beam selection can be reduced, and the accuracy of beam selection can be improved at the same time.

Description

Beam selection method and device

technical field

The present application relates to mobile communication technology, in particular to a beam selection method and device.

Background technique

At present, the fourth generation mobile communication technology (4G) has begun to be widely deployed all over the world, and the fifth generation mobile communication technology (5G) has become an emerging research field. The application of massive multiple-input multiple-output (MIMO, Multiple-Input Multiple-Output) has become a hot field of 5G technology. Compared with traditional MIMO technology, massive MIMO can use more antennas in the base station (eNB) in order to provide greater throughput. At the same time, the further application of beamforming technology under the massive MIMO technology can achieve more accurate directional services, so that more communication links can be provided in the same space. Serving capacity.

Contents of the invention

The example of this application provides a beam selection method. The method includes:

a. Pre-configure the first to Kth beams and the corresponding relationship between the beams at each level; where K is a natural number;

b. Send each beam of the first level to the user terminal UE;

c. Receive the beam index fed back by the UE;

d. Determine the beam corresponding to the received beam index,

If the determined beam is not the K-th level beam, send each beam in the next-level beam corresponding to the determined beam to the UE, and then return c;

If the determined beam is the Kth level beam, the determined beam is used as a candidate beam selected by the UE.

The example of the present application also provides a basic method for realizing the above-mentioned beam selection method, including:

The configuration module is used to perform beam selection configuration, and determine the beams of each level from the first level to the Kth level and the corresponding relationship between the beams of each level; wherein, K is a natural number;

A beam reference signal sending module, configured to send a beam reference signal to a user terminal UE;

A feedback receiving module, configured to receive a beam index fed back by the UE;

The control module is used to control the beam reference signal sending module to send the beam reference signal of the first beam configured by the configuration module to the UE; after the feedback receiving module receives the beam index fed back by the UE, determine the beam corresponding to the beam index fed back by the UE , and judge whether the beam is the beam of the Kth level, if yes, the beam is the beam selected by the UE; if not, the control beam reference signal sending module sends the beam reference signal of the next-level beam corresponding to the beam to the UE .

The beam selection scheme described in this application does not need to send candidate beams to the UE one by one for measurement, so that the overhead of the beam selection process can be greatly reduced in the case of a large number of candidate beams. In addition, in the beam selection scheme described in this application, the width of the upper-level beam is required to be greater than the width of the lower-level beam. Therefore, the UE first selects from the beam with a wider width, and then selects from a beam with a narrower width. It can better resist the influence of phase noise on the accuracy of beam selection, improve the accuracy of beam selection, and then ensure the quality of communication.

Description of drawings

In order to more clearly illustrate the technical solutions in this application, the accompanying drawings that need to be used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some examples of the application. Ordinary technicians can also obtain other drawings based on these drawings on the premise of not paying creative work. in,

Figure 1 shows an example of beams at various levels described in an example of the present application;

Fig. 2 shows the flowchart of the beam selection method described in an example of the present application;

Figure 3 shows the beam selection process between the base station and a single UE;

Figure 4 shows the process of beam selection between the base station and multiple UEs;

Fig. 5 shows the flowchart of the beam selection method described in another example of the present application;

FIG. 6 shows an example of fine phase adjustment of selected beams described in an example of the present application;

FIG. 7 shows a flowchart of a method for finely adjusting the phase of a selected beam described in an example of the present application;

Figures 8a and 8b show an example of fine phase adjustment of selected beams as described in another example of the present application; and

Fig. 9 shows a schematic diagram of the internal structure of a base station described in an example of the present application.

Detailed ways

The technical solutions in this application will be clearly and completely described below in conjunction with the accompanying drawings. Apparently, the described examples are part of the examples in this application, not all of them. Based on the examples in this application, all other examples obtained by persons of ordinary skill in the art without making creative efforts belong to the scope of protection of this application.

As mentioned above, more antennas and more beams can be obtained by combining massive MIMO technology with beamforming technology. For example, the number of beams that can be used in a 5G system can reach 512 or even more. With the increase of antenna number, beam number and precision, the capacity of the system can be greatly improved. Moreover, as the number of beams increases, the width of each beam becomes narrower, so that more precise directional services can be realized. In this case, how the mobile terminal (UE) selects the beam has become one of the urgent problems to be solved in the 5G communication system.

As mentioned above, when massive MIMO technology is applied, the number of beams that can be generated and the accuracy will be greatly increased. If all the beams are sent to the UE one by one in an exhaustive way, the UE will measure and select from them one by one. A very large signaling overhead will be generated. For this reason, an example of the present application provides a beam selection method, and beam selection is performed by selecting beams hierarchically, thereby avoiding excessive signaling overhead during the beam selection process.

In the example of the present invention, before performing beam selection, the basic configuration of beam selection needs to be performed first. These configurations mainly include the following aspects:

First, the number N of candidate beams to be selected is determined. In the examples of the present invention, the beams generated by the base station that can be selected by the UE are referred to as candidate beams. The above number of candidate beams may be related to the number of transmitting antennas of the base station. After the configuration of the base station is completed, generally the number N of beams that the base station can generate can be determined. Certainly, the above number of candidate beams may also be determined by system configuration.

Second, determine the order K of the hierarchical beam selection method. The level K of the above-mentioned hierarchical beam selection may be a fixed empirical value. For example, considering the complexity of the hierarchical beam selection method, the level K of beam selection is directly set to 3 during system configuration. The above-mentioned number of beam selection stages K can also be determined according to specific application scenarios and requirements. For example, for a system with relatively high latency requirements, the number of beam selection stages K can be reduced to reduce latency.

Thirdly, according to the N candidate beams and the number K of beam selection levels, determine the beams included in each level from the first level to the Kth level of beams. In the example of this application, the beams from the 1st to the Kth class need to meet the following requirements:

1) Each beam of the i-th level corresponds to two or more beams of the i+1-th level respectively, where i=[1, K-1].

2) The i+1-th level beams correspond to one i-th level beam.

3) Each beam of level i can correspond to two or more beams of level i+1 respectively, and the width of beam of level i will be greater than the width of beam of level i+1.

4) The Kth level beam is the above N candidate beams.

5) The direction of each beam of the i-th level is related to the direction of the corresponding two or more i+1-th level beams. Specifically, it may be shown that the correlation coefficient between the coefficient of a certain i-th beam and the coefficients of two or more i+1-th beams corresponding to it is greater than a preset threshold. That is, if the correlation coefficient of the two beam coefficients is greater than a preset threshold, the two beams are considered to be correlated; otherwise, the two beams are considered to be uncorrelated. The above-mentioned coefficient of the beam may specifically be an array factor (Array Factor) of the beam.

The beams of the first level to the Kth level can also meet the following requirement: the width of the i-th level beam will be greater than the width of the i+1-th level beam.

Figure 1 shows an example of the determined beam levels. In this example, there are 8 candidate beams, and the number of beam selection levels is 3. As shown in Figure 1, in this example, there are 2 first-level beams (Level 1), beams B ₁ and B ₂ , and each beam corresponds to 2 of the 4 beams in the second-level beam (Level 2). beams. For example, beam B ₁ corresponds to beams B ₁₁ and B ₁₂ , and beam B ₂ corresponds to beams B ₂₁ and B ₂₂ . Each of the 4 beams of the second level corresponds to 2 beams of the 8 beams of the third level beam (Level 3). For example, beam B ₁₁ corresponds to beams B ₁₁₁ and B ₁₁₂ , beam B ₁₂ corresponds to beams B ₁₂₁ and B ₁₂₂ , beam B ₂₁ corresponds to beams B ₂₁₁ and B ₂₁₂ , and beam B ₂₂ corresponds to beams B ₂₂₁ and B ₂₂₂ . The third level is eight candidate beams B ₁₁₁ , B ₁₁₂ , B ₁₂₁ , B ₁₂₂ , B ₂₁₁ , B ₂₁₂ , B ₂₂₁ and B ₂₂₂ . It can be seen from Figure 1 that the widths of the 2 beams of the first level are respectively greater than the widths of the 4 beams of the second level; and the widths of the 4 beams of the second level are respectively greater than the widths of the 8 beams of the third level. and beam B ₁ is related to the direction of beams B ₁₁ and B ₁₂ , beam B ₂ is related to the direction of beams B ₂₁ and B ₂₂ , beam B ₁₁ is related to the direction of beams B ₁₁₁ and B ₁₁₂ , and beam B ₁₂ is related to the direction of beam B ₁₂₁ Associated with the direction of B ₁₂₂ , beam B ₂₁ is associated with the direction of beams B ₂₁₁ and B ₂₁₂ , and beam B ₂₂ is associated with the direction of beams B ₂₂₁ and B ₂₂₂ .

After completing the above settings, the beam selection can be started. Figure 2 shows the beam selection method described in the examples of this application. As shown in Figure 2, the method includes the following steps:

Step 201: the base station sends each beam of the first level to the UE.

In the example of this application, in the beam selection process, what the base station sends to the UE is the reference signal of each beam. It is referred to here simply as a Beam Reference Signal (BRS).

In order to send the BRS to the UE, the base station needs to perform relevant resource configuration in advance, that is, inform the UE which subframe (subframe) or time instance (time instance) it will occupy and which time-frequency resources in the time instance will be occupied to send the BRS. In this example, the above configuration may be referred to as BRS resource configuration. Usually, the base station can configure BRS resources through RRC control signaling or dynamic control signaling; it can also be triggered through dynamic signaling after RRC pre-defined BRS resources; it can also be pre-configured in each subframe or time instance. Contains BRS.

Usually, the base station needs to indicate to the UE in which subframe or time instance the base station will perform BRS transmission. For example, a BRS indicator bit BRS_ENABLE can be added to the downlink control information (DCI) related to downlink transmission transmitted on the downlink control channel, where BRS_ENABLE=1 indicates that the base station will start to send BRS. When the UE detects that the BRS indication bit BRS_ENABLE is 1, it will perform beam detection.

Step 202: UE performs beam detection, finds the beam with the best reception performance as the selected beam, and feeds back the beam index (BI) of the selected beam to the base station.

In order for the UE to feed back the beam index of the selected beam to the base station, the base station also needs to pre-define the feedback mode of the UE and perform related configuration, that is, inform the UE which feedback mode to use for feedback. In this example, the above feedback modes may include: 1) no feedback is required; 2) only the beam index of the selected beam is fed back; and 3) besides the beam index of the selected beam is fed back, a channel quality indicator (CQI, Channel Quality Indicator), rank indication (RI, RankIndication), precoding matrix indication (PMI, Precoding Matrix Indicator) and so on.

Usually, it is also necessary to add an additional feedback mode indication bit to indicate which feedback mode the UE adopts for feedback. For example, the feedback mode indication bit FEEDBACK_MODE is added to the downlink transmission-related DCI transmitted on the downlink control channel, where FEEDBACK_MODE=0 indicates that no feedback is required; FEEDBACK_MODE=1 indicates that the UE only needs to feed back the beam index of the selected beam; FEEDBACK_MODE =2 indicates that the UE not only needs to feed back the beam index of the selected beam but also needs to feed back parameters such as the current CQI, RI, and PMI. In this case, the UE will perform corresponding feedback according to the indication of the feedback mode indication bit. For example, when the UE detects FEEDBACK_MODE=1, it will only feed back the beam index of the selected beam; when the UE detects FEEDBACK_MODE=2, it will feed back the beam index, CQI, RI and PMI of the selected beam.

Regarding the timing of the UE's feedback, the Long Term Evolution (LTE) defines the minimum interval between Reference Signal (RS) transmission and Channel State Indication (CSI) feedback. Therefore, in the example of the present invention, the UE can determine the timing of feedback in the following two ways:

(1) The timing of the feedback is determined by the transmission time of the reference signal. If the reference signal is received at time X, the UE will feed back at time X+N.

(2) The feedback time is determined by the CSI feedback trigger (Trigger), for example, the UE will feedback after receiving the CSI feedback trigger signal.

Step 203: the base station receives the beam index fed back by the UE, and determines the beam corresponding to the received beam index.

In this step, the base station may directly determine the beam selected by the UE according to the received beam index.

Step 204: The base station judges whether the determined beam is the K-th class beam, and if the determined beam is not the K-th class beam, execute step 205; if the determined beam is the K-th class beam, execute step 206.

Step 205: the base station sends each beam in the next-level beam corresponding to the determined beam to the UE, and then returns to step 202.

In this step, the method for the base station to send each beam in the next-level beam corresponding to the determined beam to the UE may refer to the above-mentioned step 201, which will not be repeated here.

Step 206: the base station takes the determined beam as the beam finally selected by the UE.

Through the above hierarchical beam selection method, there is no need to send the candidate beams to the UE one by one for measurement, so that the overhead of the beam selection process can be greatly reduced in the case of a large number of candidate beams.

Fig. 3 shows the beam selection process between the base station and a single UE in the case of only one UE. As shown in FIG. 3 , the base station first transmits the reference signals of the two first-level beams B ₁ and B ₂ shown in FIG. 1 at the resource position indicated by the shaded part in the downlink subframe #0. After detecting the two beams, the UE selects the beam B ₂ with better performance through measurement, and feeds back the beam index of the selected beam in the uplink subframe #5, that is, BI=2. Next, the base station transmits reference signals of two beams B ₂₁ and B ₂₂ in the second-level beam corresponding to the beam B ₂ shown in FIG. 1 at the resource position indicated by the shaded part in the downlink subframe #6. After detecting the two beams, the UE selects the beam B ₂₂ with better performance through measurement, and feeds back the beam index of the selected beam in the uplink subframe #10, that is, BI=22. Finally, the base station transmits reference signals of two beams B ₂₂₁ and B ₂₂₂ in the third-level beam corresponding to beam B ₂₂ shown in FIG. 1 at the resource position indicated by the shaded part in the downlink subframe #11. After detecting the two beams, the UE selects the beam B ₂₂₂ with better performance through measurement, and feeds back the beam index of the selected beam in the uplink subframe #15, that is, BI=223. At the same time, according to the feedback mode indication The bit indication also feeds back information such as the current CQI, RI, and PMI. So far, the beam selection process is completed. It can be seen that through the three selection processes, the base station sends a total of 6 beams, and the UE can accurately select the most suitable beam from the 8 candidate beams.

Fig. 4 shows the process of beam selection between the base station and multiple UEs in the case of multiple UEs. In this example, first assume that the number of candidate beams is 512; the number of beam selection levels is 3, that is, each level has 8 beams, and the beams of each level correspond to the 8 beams of the next level. The number of UEs covered by the base station is 10, including UE1, UE2, . . . , UE10. In this case, as shown in FIG. 4 , the base station first transmits the reference signals of the 8 beams B ₁ to B ₈ of the first stage. After detecting these 8 beams, each UE selects the beam with better performance through measurement. UE1 and UE2 select beam B ₁ and feed back the corresponding BI; UE3 selects beam B ₂ and feeds back the corresponding BI. UE4 and UE5 selected beam B ₃ and fed back the corresponding BI; UE6, UE7 and UE8 selected beam B ₅ and fed back the corresponding BI; UE9 selected beam B ₆ and fed back the corresponding BI ; and the UE 10 selects the beam B ₇ and feeds back the corresponding BI. Next, the base station sends reference beams B ₁₁ -B ₁₈ , B ₂₁ -B ₂₈ , B ₃₁ -B ₃₈ , B ₅₁ -B ₅₈ , B ₆₁ -B ₆₈ and B ₇₁ -B ₇₈ as shown in Figure 4 respectively. Signal. After detecting these beams, each UE selects a beam with better performance through measurement. UE1 selects beam B ₁₁ and feeds back the corresponding BI; UE2 selects beam B ₁₅ and feeds back the corresponding BI; UE3 Selected beam B ₂₅ and fed back the corresponding BI; UE4 selected beam B ₃₂ and fed back the corresponding BI; UE5 selected beam B ₃₆ and fed back the corresponding BI; UE6, UE7 and UE8 selected beam B ₅₄ , and fed back the corresponding BI; UE9 selected beam B ₆₇ , and fed back the corresponding BI; and UE10 selected beam B ₇₂ , and fed back the corresponding BI. Then, the base station sends the reference signals of the third-level beams corresponding to the beams selected by the UE. Finally, each UE selects the beam with the best performance according to the detection results of each beam, and feeds back information such as the beam index, CQI, RI, and PMI of the selected beam to the base station. As shown in Figure 4, in this example, the number of beams sent by the base station to the UE is 8+6х8+8х8=120 during the three beam transmission processes from the first stage to the third stage, but there are 512 beam candidates. indivual. Therefore, the number of beams to be transmitted by the base station can be greatly reduced through this hierarchical beam selection method, thereby greatly reducing the overhead of the beam selection process.

In addition, as mentioned earlier, in the 5G era, more antennas and more beams can be obtained by combining massive MIMO technology and beamforming technology, and the width of the beam is getting narrower, so as to achieve more accurate directional service. However, as the beam width becomes narrower, the beam will be more affected by phase noise, thus affecting the accuracy of beam selection and the quality of communication. For this reason, in the multi-level beams of the method described in this application, it is required that the upper-level beams can cover the corresponding lower-level beams, that is, the width of the upper-level beams is greater than the width of the lower-level beams. Therefore, the UE starts with the wider beam. Select from among the narrower beams, which can better resist the influence of phase noise on the accuracy of beam selection, improve the accuracy of beam selection, and thus ensure the quality of communication.

Further, in order to further counteract the influence of phase noise on beam selection accuracy, the present application also proposes a beam selection method. In this method, after the candidate beam finally selected by the UE is determined, phase adjustment is further performed on the candidate beam finally selected by the UE, and the adjusted beam is sent to the UE. After performing beam detection on the phase-adjusted beam, the UE feeds back the beam index of the selected beam to the base station. At this time, the base station can determine the phase-adjusted candidate beam selected by the UE. In this method, by adjusting the phase of the candidate beam selected by the UE, the beam can be precisely aligned with the UE, thereby avoiding the influence of phase noise on the accuracy of beam selection and communication quality.

Fig. 5 shows the beam selection method described in the example of this application. As shown in Figure 5, the method includes the following steps:

Step 501: the base station sends each beam of the first level to the UE.

Step 502: UE performs beam detection, finds the beam with the best reception performance as the selected beam, and feeds back the beam index (BI) of the selected beam to the base station.

Step 503: the base station receives the beam index fed back by the UE, and determines the beam corresponding to the received beam index.

Step 504: The base station judges whether the determined beam is the K-th class beam, and if the determined beam is not the K-th class beam, execute step 505; if the determined beam is the K-th class beam, execute step 506.

Step 505: the base station sends each beam in the next-level beam corresponding to the determined beam to the UE, and then returns to step 502.

The implementation method of the above-mentioned steps 501-505 may be the same as the implementation method of the above-mentioned steps 201-205, and will not be repeated here.

Step 506: The base station takes the beam selected by the UE as the center, and rotates the beam selected by the UE clockwise and counterclockwise with a preset rotation accuracy s times to obtain a total of 2s beams, wherein every two adjacent beams The angle between the beams differs by one rotation precision. Among them, s is a natural number.

In this example, the above-mentioned rotation accuracy and the setting of the number of rotations s can be determined according to the width of the candidate beam and the angle between adjacent candidate beams, so as to ensure that each adjacent beam in the 2s+1 beams only shifts by one Small angles, and no closer to other candidate beams after offsetting.

Step 507: the base station sends the obtained 2s beams together with the beam selected by the UE to the UE.

In this step, the base station will send a total of 2s+1 beams of BRS to the UE.

Step 508: UE performs beam detection, finds the beam with the best reception performance as the selected beam, and feeds back the beam index (BI) of the selected beam to the base station.

Step 509: the base station receives the beam index fed back by the UE, and determines the beam corresponding to the received beam index.

Step 510: the base station takes the determined beam as the beam finally selected by the UE.

The above steps 506-510 realize the fine adjustment of the phase of the selected beam, so that the selected beam can be aligned with the UE more precisely, and effectively avoid the influence of phase noise on the accuracy of beam selection and communication quality.

Figure 6 shows an example of the phase fine-tuning of the selected beams described above. In the example shown in FIG. 6 , it is assumed that s=2. In this example, the base station firstly rotates the candidate beam B ₂₁₂ selected by the UE counterclockwise and clockwise by one rotation precision twice to obtain four beams B _212-2 , B _212-1 and B ₂₁₂₊₁ , B _{212 +2} . In this case, the base station will transmit BRSs of the following five beams B _212-2 , B _212-1 , B ₂₁₂ , B ₂₁₂₊₁ and B ₂₁₂₊₂ to the UE. After performing beam detection, the UE selects and feeds back B ₂₁₂₊₁ . In this case, the base station can determine that beam B ₂₁₂₊₁ can be more accurately aimed at the UE.

As an alternative to the above step 510, after step 509 is performed, the base station may further perform the following process as shown in FIG. 7:

Step 510A, determine whether the beam determined this time is the most edge beam obtained by rotation, if yes, execute step 510B; if not, execute step 510C.

Step 510B: the base station takes the determined beam as the beam finally selected by the UE.

Step 510C: The base station continues to center on the beam selected by the UE, and continues to rotate the beam clockwise and counterclockwise with a preset rotation accuracy s times, and obtains 2s beams in total, wherein every two adjacent beams The angle between them differs by one rotational precision. Among them, s is a natural number.

Step 510D: the base station sends the obtained 2s beams and the beam selected by the UE to the UE, and then returns to step 508 .

The above steps 506-509, 510A-510D realize the fine adjustment of the phase of the selected beam, so that the selected beam can be more accurately aligned with the UE, effectively avoiding the impact of phase noise on the accuracy of beam selection and communication quality.

Figures 8a and 8b show examples of the phase fine-tuning of the selected beams described above. In the example shown in Figures 8a and 8b it is assumed that s=1. In this example, the base station firstly rotates the candidate beam B ₁₂₁ selected by the UE counterclockwise and clockwise by one rotation accuracy respectively to obtain two beams B _121-1 and B ₁₂₁₊₁ . In this case, as shown in Figure 8a, the base station will transmit the following 3 beams B _121-1 , B ₁₂₁ and B ₁₂₁₊₁ to the UE. After performing beam detection, the UE selects and feeds back B ₁₂₁₊₁ . In this case, the base station will continue to rotate one rotation precision counterclockwise and clockwise around the beam B ₁₂₁₊₁ to obtain two beams B ₁₂₁ and B ₁₂₁₊₂ . In this case, as shown in Fig. 8b, the base station will transmit the following 3 beams B ₁₂₁ , B ₁₂₁₊₁ and B ₁₂₁₊₂ to the UE. At this time, after the beam detection, if the UE selects the beam B ₁₂₁₊₁ , the beam B ₁₂₁₊₁ is the beam finally selected by the UE. If the UE selects the beam B ₁₂₁₊₂ , the base station will continue to rotate counterclockwise and clockwise around the beam B ₁₂₁₊₂ to obtain a new beam, and continue to send it to the UE for selection until the UE finds the final beam.

Corresponding to the above beam selection method, the example of the present application also provides a base station for implementing the above beam selection method. Fig. 9 shows the internal structure of the base station described in the example of this application. As shown in Figure 9, the base station includes:

The configuration module 901 is used to perform beam selection configuration, and determine the beams of each level from the 1st to the Kth level and the corresponding relationship between the beams of each level; wherein, the beams of the 1st to the Kth level configured by the configuration module 901 To meet the requirements stated above;

A beam reference signal sending module 902, configured to send a beam reference signal to the UE;

A feedback receiving module 903, configured to receive a beam index fed back by the UE;

The control module 904 is used to control the beam reference signal sending module 902 to send the beam reference signal of the first-level beam configured by the configuration module 901 to the UE; after the feedback receiving module 903 receives the beam index fed back by the UE, determine the beam fed back by the UE index the corresponding beam, and judge whether the beam is the beam of the Kth level, if yes, the beam is the beam finally selected by the UE; if not, the control beam reference signal sending module 902 sends the next beam corresponding to the beam to the UE The beam reference signal of the level beam.

The above-mentioned base station may further include: a phase adjustment module 905, configured to perform phase adjustment on the beam selected by the UE, and control the beam reference signal of the beam after the phase adjustment by the beam reference signal sending module 902; and the feedback receiving module 903 receives the UE After the beam index is fed back, the beam corresponding to the beam index fed back by the UE is determined as the beam finally selected by the UE.

The above-mentioned phase adjustment module 905 may use the above-mentioned method of steps 506-510 or the methods of steps 506-509, 510A-510D to perform phase adjustment.

As mentioned above, the above-mentioned base station that implements beam selection can greatly reduce the signaling overhead of the beam selection process through the hierarchical beam selection method, and because the width of the configured upper-level beam is larger than the width of the lower-level beam, this solution can also be effective. To combat the influence of phase noise on beam selection accuracy and communication quality, that is, to improve the accuracy of beam selection, thereby improving the communication quality of the system.

The above is only an example of the application, and is not intended to limit the application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the application shall be included in the scope of protection of the application within.

Claims (16)

1. A beam selection method, characterized in that, comprising: a. Pre-configure the first to Kth beams and the corresponding relationship between the beams at each level; where K is a natural number; b. Send each beam of the first level to the user terminal UE; c. Receive the beam index fed back by the UE; d. Determine the beam corresponding to the received beam index, If the determined beam is not the K-th level beam, send each beam in the next-level beam corresponding to the determined beam to the UE, and then return c; If the determined beam is the Kth level beam, the determined beam is used as a candidate beam selected by the UE. 2. The method according to claim 1, wherein the first to Kth beams meet the following conditions: Each beam of level i corresponds to two or more beams of level i+1 respectively; The beams of the i+1th level correspond to one beam of the ith level; Each beam of level i can correspond to two or more beams of level i+1 respectively; The K-th beam is N candidate beams, where N is a natural number; and The direction of each beam of the i-th level is related to the directions of two or more i+1-th level beams corresponding to it; wherein, i=[1, K-1]. 3. The method according to claim 1 or 2, wherein the width of the i-th beam is greater than the width of the i+1th beam, where i=[1, K-1]. 4. The method according to claim 2, wherein the direction of each beam of the i-th level is related to the directions of two or more i+1-th level beams corresponding to it respectively, comprising: A correlation coefficient between the coefficient of the i-th beam and the coefficient of the i+1-th beam corresponding to it is greater than a preset threshold. 5. The method according to claim 4, wherein the coefficient of the beam comprises an array factor of the beam. 6. The method according to claim 1, wherein the sending each beam of the first level to the user terminal UE comprises: performing beam reference signal BRS resource configuration through radio resource control RRC signaling or dynamic control signaling; and The BRS of each beam of the first level is sent on the configured BRS resources. 7. The method according to claim 1, wherein the sending each beam of the first level to the user terminal UE comprises: Pre-configuring beam reference signal BRS resources in radio resource control RRC signaling; Informing the UE to prepare to receive the BRS through dynamic signaling when preparing to send the BRS; and The BRS of each beam of the first level is sent on the configured BRS resource. 8. The method according to claim 1, wherein the sending each beam in the next-level beam corresponding to the determined beam to the UE comprises: performing beam reference signal BRS resource configuration through radio resource control RRC signaling or dynamic control signaling; and The BRS of each beam of the next level is sent on the configured BRS resources. 9. The method according to claim 1, wherein the sending each beam in the next-level beam corresponding to the determined beam to the UE comprises: Pre-configuring beam reference signal BRS resources in radio resource control RRC signaling; Informing the UE to prepare to receive the BRS through dynamic signaling when preparing to send the BRS; and The BRS of each beam of the next level is sent on the configured BRS resources. 10. The method according to claim 7 or 9, wherein the notifying the UE of preparing to receive the BRS through dynamic signaling comprises: Adding a BRS indication bit on the downlink control information DCI related to downlink transmission transmitted on the downlink control channel; wherein, when the BRS indication bit is 1, it indicates that the base station will start sending BRS; When preparing to send a BRS, set the BRS indication bit to 1. 11. The method according to claim 1, further comprising: notifying the UE of the mode of feeding back the beam index; wherein, the mode of feeding back the beam index includes: no feedback is required; only the beam index of the selected beam is fed back; and In addition to feeding back the beam index of the selected beam, it is also necessary to feed back the channel quality indicator CQI, the rank indicator RI and the precoding matrix indicator PMI. 12. The method according to claim 11, wherein the mode of notifying the UE of the feedback beam index comprises: A feedback mode indication bit is added to the DCI related to downlink transmission transmitted on the downlink control channel, wherein the feedback mode indication bit is 0, indicating that no feedback is required; the feedback mode indication bit is 1, indicating that only feedback is required. The beam index of the beam; the feedback mode indication bit being 2 indicates that not only the beam index of the selected beam but also the current CQI, RI and PMI need to be fed back. 13. The method according to claim 1, wherein said using the determined beam as a candidate beam selected by the UE comprises: Perform phase adjustment on the determined beam, and send the beam reference signal of the phase-adjusted beam to the UE; receiving the beam index fed back by the UE; The beam corresponding to the beam index fed back by the UE is determined as the beam selected by the UE. 14. The method according to claim 13, wherein the phase adjustment of the determined beam comprises: Taking the determined beam as the center, rotate the determined beam clockwise and counterclockwise with the preset rotation accuracy s times respectively, and obtain 2s beams in total, wherein the angle difference between every two adjacent beams is one Rotation accuracy; where, s is a natural number. 15. A base station, characterized in that it comprises: The configuration module is used to perform beam selection configuration, and determine the beams of each level from the first level to the Kth level and the corresponding relationship between the beams of each level; wherein, K is a natural number; A beam reference signal sending module, configured to send a beam reference signal to a user terminal UE; A feedback receiving module, configured to receive a beam index fed back by the UE; The control module is used to control the beam reference signal sending module to send the beam reference signal of the first beam configured by the configuration module to the UE; after the feedback receiving module receives the beam index fed back by the UE, determine the beam corresponding to the beam index fed back by the UE , and judge whether the beam is the beam of the Kth level, if yes, the beam is the beam selected by the UE; if not, the control beam reference signal sending module sends the beam reference signal of the next-level beam corresponding to the beam to the UE . 16. The base warfare according to claim 15, further comprising: The phase adjustment module is configured to adjust the phase of the beam selected by the UE, and control the beam reference signal sending module to send the beam reference signal of the beam after the phase adjustment; and after the feedback receiving module 903 receives the beam index fed back by the UE, determine the The beam corresponding to the beam index is fed back as the beam selected by the UE.