JP6812055B2 - How to feed back channel quality, user equipment, and base stations - Google Patents

Description

The present application relates to mobile communication technology, and more particularly to methods for feeding back channel quality, user equipment, and base stations.

In wireless communication systems, base stations typically need to feed back channel quality from user equipment (UEs) in order to schedule users, and then each user's channel quality is based on the channel quality fed back from each UE. The modulation coding method (MCS), time frequency resource, etc. used for downlink transmission are determined.

The embodiments of the present application have been made in view of the above, provide a method of adjusting the channel quality, and aim to improve the accuracy of downlink scheduling. Accordingly, system throughput and user throughput can also be improved to some extent.

In the embodiments of the present application, a method of feeding back the channel quality is provided. This method is used in a first user device (UE) to receive a first downlink signal transmitted at a first time and to obtain a first channel quality value based on the first downlink signal. A second when the base station performs multi-user transmission based on the second downlink signal estimated and transmitted at the second time after the first time and based on the second downlink signal. The channel quality value is estimated, the channel quality adjusting factor is calculated based on the first channel quality value and the second channel quality value, and the channel quality adjusting factor is fed back to the base station to provide the base station. Adjusts the channel quality of the first UE at the time of multi-user transmission estimated by the base station based on the channel quality adjusting factor, and performs multi-user transmission using the adjusted channel quality. Here, the multi-user transmission is a downlink transmission from a base station to a plurality of UEs including the first UE, using the same time frequency resource.

In the embodiments of the present application, a user device (UE) is provided. The UE includes a receiving module that receives a first downlink signal transmitted at the first time and a second downlink signal transmitted at a second time after the first time, and the first downlink signal. An estimation module that estimates the first channel quality value based on the downlink signal of the above, and estimates the second channel quality value when the base station performs multi-user transmission based on the second downlink signal. A calculation module that calculates a channel quality adjusting factor based on the first channel quality value and the second channel quality value, and feeding back the channel quality adjusting factor to a base station, the base station uses the channel. Feedback for adjusting the channel quality of the first UE during multi-user transmission estimated by the base station based on the quality adjusting factor and performing multi-user transmission using the adjusted channel quality. A module is provided, wherein the multi-user transmission is a downlink transmission from a base station to a plurality of UEs including the first UE, using the same time frequency resource.

In the embodiments of the present application, a base station is provided. The base station transmits the first downlink signal at the first time, so that the first user equipment (UE) estimates the first channel quality value based on the first downlink signal. By transmitting the second downlink signal at the second time after the first time, the first UE transmits the second downlink signal, and the base station transmits the multi-user based on the second downlink signal. The transmission module that estimates the second channel quality value at the time of performing the above and calculates the channel quality adjusting factor based on the first channel quality value and the second channel quality value, and the first channel quality value. A modulation coding method (MCS) used for the downlink signal of the first UE when performing multi-user transmission based on the receiving module that receives the channel quality adjusting factor fed back from the UE and the channel quality adjusting factor. ) Is provided, wherein the multi-user transmission is downlink transmission from the base station to a plurality of UEs including the first UE using the same time frequency resource.

As can be seen from the above solutions, according to the method of feeding back the channel quality in the mobile communication system, the user equipment, and the base station provided in the embodiment of the present application, the UE itself calculates the channel quality adjusting factor. By feeding back this channel quality adjusting factor to the base station, the base station can know the channel quality deviation estimated by the UE. In addition, this allows the base station to determine the MCS used to transmit the downlink signal of the UE when actually performing multi-user transmission, effectively improving the accuracy of the MCS in subsequent transmissions. However, system throughput and user throughput can be improved.

It is a schematic diagram of the flow of the method of feeding back the channel quality in the Example of this application. It is a schematic diagram of the flow of the method of feeding back the channel quality in the Example of this application. It is a schematic diagram of the multi-user transmission in the Example of this application. It is a schematic diagram of the flow of the method of adjusting CQI in the Example of this application. It is a schematic diagram of the probability distribution of the interference power adjustment value in the Example of this application. It is a schematic diagram of the probability distribution of the interference power adjustment value in the Example of this application. It is a signaling exchange diagram of the method of adjusting CQI in the Example of this application. It is a schematic diagram of the flow of the method of adjusting CQI in the Example of this application. It is a schematic diagram of the configuration of the user equipment in the Example of this application. It is a schematic diagram of the structure of the base station in the Example of this application.

In order to further clarify the object, the solution, and the merit of the present invention, the present application will be described in more detail with reference to the drawings below with reference to examples.

FIG. 1a is a schematic diagram of a flow of a method of feeding back channel quality in the embodiment of the present application. This method is used for the first UE and includes the following steps:

In step 11, the first downlink signal transmitted at the first time is received, and the first channel quality value is estimated based on the first downlink signal.

The first downlink signal (sometimes referred to as the first downlink data) refers to a downlink signal for channel estimation transmitted from the base station to the first UE, such as a pilot signal. The pilot signal may be, for example, a downlink reference signal (RS) such as a cell reference signal (CRS) or a UE-specific reference signal (UE-specific RS).

The channel quality value is a numerical value for expressing the channel quality. The channel quality values are, for example, signal-to-noise ratio (SINR), signal-to-noise ratio (SNR), signal-to-noise ratio (SIR), carrier-to-interference ratio (CIR), reference signal reception quality (RSRQ), and the like. You may.

In step 12, the second downlink signal transmitted at the second time after the first time is received, and the base station performs multi-user transmission based on the second downlink signal. Estimate the channel quality value of.

Multi-user transmission refers to downlink transmission from a base station to a plurality of UEs including the first UE using the same time frequency resource.

The second downlink signal (sometimes referred to as the second downlink data) is a downlink signal for multi-user transmission transmitted from the base station to the first UE, for example, a control signal for multi-user transmission. Point to. The first UE may acquire the parameters of the multi-user transmission from the second downlink signal and use the parameters of the multi-user transmission to estimate the second channel quality value. The parameters of the multi-user transmission may include the power and precoding matrix allocated to the first UE during multi-user transmission, and the power allocated to at least one second UE among the plurality of UEs. Good.

In step 13, a channel quality adjusting factor is calculated based on the first channel quality value and the second channel quality value, and the channel quality adjusting factor is fed back to the base station.

The base station adjusts the channel quality of the first UE at the time of multi-user transmission estimated by the base station based on the channel quality adjusting factor, and uses the adjusted channel quality for multi-user transmission. May be done.

In the embodiment of the present application, the UE estimates the channel quality at the time of multi-user transmission for the case of multi-user transmission, calculates the channel quality adjusting factor based on this channel quality, and bases the channel quality adjusting factor. Give feedback to the station. In this way, the base station can adjust the estimated value of the channel quality of the UE at the time of multi-user transmission by using the channel quality adjusting factor, and perform multi-user transmission based on the adjusted estimated value. Therefore, the accuracy of MCS in the subsequent transmission can be effectively improved, and the system throughput and the user throughput can be improved.

FIG. 1b is a schematic diagram of the flow of the method of feeding back the channel quality in the embodiment of the present application. This method is used for the first UE. In this embodiment, the case where SINR is used as the channel quality value will be described as an example. This method involves the following steps:

In step 101, the first downlink data transmitted at the first time is received, and the first SINR is estimated based on the first downlink data.

As used herein, downlink data may refer to user data, pilot data, or control signaling data.

In a specific realization, SINR is the ratio of the strength of the received useful signal to the strength of the received interference signal and noise. The first downlink data may be, for example, a downlink reference signal (RS) such as a cell reference signal (CRS). The first UE may estimate the first SINR based on the received RS. This is expressed as Equation 1.

In step 102, the second SINR is estimated based on the received second downlink data.

Here, the second downlink data is transmitted at the second time after the first time. The second downlink data includes data transmitted to the first UE. In this way, the first UE estimates the second SINR based on the received data signal. This is expressed as Equation 2.

In step 103, the CQI regulator (that is, the channel quality regulator) is calculated based on the first SINR and the second SINR, and the CQI regulator is fed back to the base station.

In one embodiment, the calculation of the CQI regulator γ may be expressed as Equation 3.

In a typical scenario of multi-user transmission, as shown in FIG. 2, the base station simultaneously serves a plurality of users UE1, UE2, UE3, and UE4. Depending on whether the resources assigned to the user are orthogonal, the base station either employs orthogonal multi-user multi-antenna (MU-MIMO) transmission or non-orthogonal multiple access (NOMA) transmission. Can be determined.

Specifically, MU-MIMO transmission belongs to the orthogonal access method, and a plurality of users are assigned orthogonal resources. For example, different spatial resources are used to simultaneously transmit signals to UE1 and UE3 of FIG. In NOMA transmission, the same resource can be assigned to multiple users. For example, in FIG. 2, since the difference in channel quality between UE1 and UE2 is large, the base station allocates non-orthogonal resources to UE1 and UE2 during downlink scheduling, for example, causing them to use the same time frequency resource block. But allocates different power. In this way, differences in channel quality of a plurality of users can be converted into multiplexing gain. On the UE side, demultiplexing may be performed using a series interference elimination technique. Similarly, UE3 and UE4 may also adopt the NOMA transmission method.

Regarding MU-MIMO transmission, when UE1 and UE3 are taken as an example, the first UE among them may be UE1. When the UE 1 feeds back the CQI, it receives interference from the UE 3 when actually transmitting downlink data (that is, performing multi-user transmission) at the second time, and interference by another UE in an adjacent cell. I can't know. Here, since UE1 and UE3 use orthogonal resources, the above interference is mainly from other UEs in adjacent cells.

When UE1 and UE2 are taken as an example for NOMA transmission with non-orthogonal resources, the first UE among them may be UE1. Since both are non-orthogonal in the power dimension, UE1 cannot know the interference by UE2 paired with its own station during multi-user transmission and the interference by other UEs in the adjacent cell when feeding back CQI. .. Here, since the transmission is non-orthogonal, the above-mentioned interference is mainly from the UE 2 paired with the own station in the same cell.

As can be seen from this, in the case of orthogonal MU-MIMO or non-orthogonal NOMA transmission, the CQI fed back from the UE 1 to the base station is significantly different from the actual CQI at the time of actual downlink data transmission. As a result, the accuracy of the MCS determined during scheduling by the base station is reduced, so it is necessary to adjust the CQI referenced during scheduling.

According to the method provided in the above embodiment, the first UE itself estimates the CQI regulator based on the SINR of the two times before and after, and further feeds back to the base station, so that the base station Based on this CQI regulator, it is possible to determine the MCS to use for subsequent multi-user transmissions, effectively improving the accuracy of MCSs in multi-user transmissions, and improving system throughput and user throughput. be able to.

FIG. 3 is a schematic diagram of a flow of a method of adjusting CQI in another embodiment of the present application. This method is used for the first UE and includes the following steps:

In step 301, a plurality of candidate adjustment values are preset.
Here, the numerical value of the candidate adjustment value (also referred to as the candidate CQI adjustment value) may be preset to a fixed value by the first UE, or the first UE is quantized based on the interference power adjustment value λ. May be obtained. Here, a specific method based on the interference power adjustment value λ is shown in step 304. The first UE stores the interference power adjustment value λ calculated each time, and obtains L candidate CQI adjustment values α1, ..., αL by the following procedure.

In step 3011, the probability distribution of the interference power adjustment value calculated before the second time is statistic.
In step 3012, the probability value p corresponding to each interference power adjustment value is determined based on the probability distribution.

In step 3013, the probability values are grouped.
The probability threshold value pth is set in advance, all the probability values p1, ..., PM larger than this probability threshold value are taken out, and then the probability values having similar numerical values are grouped. The number of probability values in each group may be the same or different.

In step 3014, the interference power adjustment values λ corresponding to the probability values in each group are averaged, and the obtained average values are determined as L candidate CQI adjustment values.

Here, the total number L of the candidate CQI adjustment values may be preset by the first UE. The value of L affects the accuracy of the fed-back CQI regulator. For example, when L = 4, α1 = −0.1, α2 = 0.1, α3 = 0.23, α4 = 0.56. Further, for example, in the case of L = 8, α1 = −0.3, α2 = −0.15, α3 = 0, α4 = 0.1, α5 = 0.2, α6 = 0.3, α7 = 0. 5, α8 = 0.7. The value of L also affects the transmission resource used for feedback of the CQI adjustment value.

FIG. 4a is a schematic diagram of the probability distribution of the interference power adjustment value in one embodiment of the present invention, and corresponds to the case of L = 4. As shown in FIG. 4a, the horizontal axis is the interference power adjustment value, and the vertical axis is the probability value. Each interference power adjustment value corresponds to one probability value and is represented by a straight line marked with a circle. A probability value having a probability threshold value of 2% and a probability value higher than the probability threshold value of thth includes a total of 10 numerical values, that is, M = 10. These 10 probability values are divided into a total of 4 groups according to the principle of numerical proximity, as shown by the markers "Group 1" to "Group 4" in FIG. 4a. Here, "group 1" contains four probability values, "group 2" contains one probability value, "group 3" contains two probability values, and "group 4" contains three probability values. .. The interference power adjustment values corresponding to the probability values for each group are averaged to obtain α1 to α4.

FIG. 4b is a schematic diagram of the probability distribution of the interference power adjustment value in one embodiment of the present invention, and corresponds to the case of L = 8. The probability distribution in FIG. 4b is similar to that in FIG. 4a. Ten probability values higher than the probability threshold pth are divided into eight groups as shown by the markers "Group 1" to "Group 8" in FIG. 4b. Here, "group 2" and "group 7" each include two probability values, and the other groups each include one probability value. The interference power adjustment values corresponding to the probability values for each group are averaged to obtain α1 to α8.

In step 302, the first downlink data transmitted at the first time is received, and the first SINR is estimated based on the first downlink data.

In step 303, the second SINR is estimated based on the received second downlink data, and the first power allocated to the first UE at the time of transmitting the second downlink data by the base station and the first power. Acquires the second power allocated to the two UEs.

When transmitting downlink data to a plurality of UEs, the base station informs each UE of the power allocated to each of all the paired UEs via downlink control signaling. For example, it is the second UE that is paired with the first UE. The base station informs the first UE of the first power β ₁ assigned to the first UE and the second power β ₂ assigned to the second UE.

In step 304, the CQI regulator is calculated based on the first SINR and the second SINR.

The interference power adjustment value λ is calculated based on the first SINR (SINR ₁ ), the second SINR (SINR ₂ ), the first power β ₁ , and the second power β ₂ , and the interference power adjustment value λ is calculated. And each candidate CQI adjustment value α1, ..., αL is determined, and the candidate CQI adjustment value corresponding to the smallest difference among the determined differences is used as the CQI adjustment factor.

In one embodiment, the first UE is paired with the second UE, and the first UE is the spatial resource allocated to the first UE by the base station from the downlink control signaling and the first UE. Determine if the spatial resources allocated to the 2 UEs are the same. Depending on whether the spatial resources are the same, it can be determined whether the first UE and the second UE perform orthogonal MU-MIMO transmission or non-orthogonal NOMA transmission.

Specifically, the first UE uses resources in which the spatial resources allocated to the first UE by the base station and the spatial resources allocated to the second UE are not the same, for example, orthogonal resources. When it is determined that MU-MIMO transmission is to be realized, the interference power adjustment value λ is estimated by an equation such as the following equation 4.

In the first UE, the spatial resource allocated to the first UE by the base station and the spatial resource allocated to the second UE are the same, and for example, NOMA transmission is realized by using non-orthogonal resources. Then, when the first power β ₁ is the second power β ₂ or more, that is, the first UE is a longer-distance user than the second UE, the following equation 5 is used. The interference power adjustment value λ is estimated by the equation.

In the case of NOMA transmission, when the first power β ₁ is smaller than the second power β ₂ , that is, the first UE is a closer user than the second UE, there is no need to feed back the CQI regulator. .. At this time, Null may be set in the information field for feeding back the interference power adjustment value λ in the uplink resource.

It should be pointed out that the second UE may include at least one UE that is paired with the first UE and uses orthogonal resources (eg, different spatial resources). As shown in FIG. 2, when the first UE is UE1, the second UE may be UE3, or the second UE includes UE3 and UE4. When the second UE includes a plurality of UEs paired with the first UE, the second power β ₂ is the sum of the powers allocated to each of all the UEs paired with the first UE. ..

In another embodiment, the second UE includes a third UE and a fourth UE, and the second power is a third power β ₃ assigned to the third UE and a fourth UE. Includes a _fourth power β ₄ assigned to. The first UE, the third UE, and the fourth UE simultaneously realize orthogonal MU-MIMO transmission and non-orthogonal NOMA transmission. In this case, in the first UE, the spatial resource allocated to the first UE by the base station and the spatial resource allocated to the third UE from the downlink control signaling are not the same, that is, the first UE. It realizes MU-MIMO transmission between the UE and the third UE, and the spatial resource allocated to the first UE by the base station and the spatial resource allocated to the fourth UE are the same, that is, , Determines to implement NOMA transmission between the first UE and the fourth UE.

As shown in FIG. 2, when the first UE is UE1, the third UE may be UE3, or the third UE includes UE3 and UE4, and the fourth UE is It may be UE2. When the third UE includes a plurality of UEs, the third power β ₃ is the sum of the powers allocated to each of all UEs paired with the first UE, which use different spatial resources. For example, it is the sum of the electric powers allocated to the UE 3 and the UE 4. When the fourth UE includes a plurality of UEs, the fourth power β ₄ is the sum of the powers allocated to each of all the UEs paired with the first UE that use the same spatial resources.

When the first power β ₁ is larger than the fourth power β ₄ , that is, it is expressed that the first UE is a long-distance user than the fourth UE, an equation such as the following equation 6 is used. The interference power adjustment value λ is estimated by.

When the first power β ₁ is less than or equal to the fourth power β _4, that is, it is represented that the first UE is a closer user than the fourth UE, for example, in FIG. 2, the UE 1 is If the user is a shorter distance user than the UE 2, the interference power adjustment value λ is estimated by an equation such as the following equation 7.

In step 305, the CQI regulator is fed back to the base station.
In this step, whether or not the UE feeds back the CQI regulator to the base station is set semi-statically by upper layer signaling (eg, radio resource control (RRC) signaling) or at the base station by downlink control signaling. It may be set dynamically.

Knowing that feedback is needed from the received signaling, the first UE may feed back the CQI regulator to the base station on the physical uplink control channel (PUCCH) or physical uplink shared channel (PUSCH). Good.

FIG. 5 is a signaling diagram of a method of adjusting CQI in one embodiment of the present invention. As shown in FIG. 5, this method includes the following steps.

In step 501, the base station transmits a downlink reference signal to the first UE at the first time.
In step 502, the first UE estimates the first SINR and the first CQI based on the received downlink reference signal.

In step 503, the first UE feeds back the first CQI to the base station.
In step 504, if the base station decides to schedule the user based on the received first CQI and schedule the first UE, the base station will use it for the first UE based on the first CQI. Determine the MCS of 1.

In step 505, the base station reschedules the first UE, transmits the second downlink data to the first UE at the second time according to the first MCS, and via downlink control signaling. Notify the first UE to feed back the CQI regulator.

For example, the base station sets an instruction bit in the physical downlink control channel (PDCCH). Upon receiving this instruction bit, the UE knows whether or not it is necessary to feed back the CQI adjuster from this instruction bit. This setting may be a dynamic setting, and the UE calculates the CQI adjusting factor only after receiving this instruction bit. For example, the base station statistics the block error rate (BLER) based on the result of the downlink hybrid automatic repeat request (HARQ), and if the BLER is larger than a predetermined threshold, sets an instruction bit in the PDCCH. May be good.

In step 506, the first UE estimates the second SINR and the second CQI based on the received second downlink data, and adjusts the CQI based on the first SINR and the second SINR. Calculate the factors.

In step 507, the first UE feeds back the second CQI and the CQI regulator to the base station.

In step 508, the base station determines a second MCS to use for subsequent transmission of downlink data from the first UE, based on the received second CQI and CQI regulator.

In step 509, the base station reschedules the first UE, encodes and adjusts the data of the first UE according to the second MCS, and goes to the first UE at the third time. The third downlink data is transmitted.

Here, the method of determining the MCS based on SINR or CQI may refer to the algorithm in the LTE / LTE-A protocol, and the description thereof is omitted here.

FIG. 6 is a schematic diagram of a flow of a method for adjusting CQI in another embodiment of the present invention. This method is used for base stations and includes the following steps, as shown in FIG.

In step 601 the first UE estimates the first SINR based on the first downlink data by transmitting the first downlink data to the first UE at the first time. ..

In this step, the first UE may simultaneously estimate the first CQI based on the first downlink data. Thereby, the first CQI is fed back to the base station and used in step 602 to determine the first MCS to be used for transmitting the second downlink data.

By transmitting the second downlink data to the first UE at the second time in step 602, the first UE estimates the second SINR based on the second downlink data, and the first The channel quality indicator (CQI) regulator is calculated based on the SINR of the above and the second SINR.

In this step, the first UE may simultaneously estimate the second CQI based on the second downlink data. Thereby, the second CQI is fed back to the base station and used to determine the second MCS used for transmitting the third downlink data in step 604.

In step 603, the CQI regulator fed back from the first UE is received.
In step 604, the second MCS to be used for transmitting the third downlink data to the first UE is determined based on the CQI regulator.

In this step, the base station has a first power β ₁ assigned to the first UE, a second power β ₂ assigned to the second UE, and a CQI regulator when transmitting the second downlink data. A third SINR (represented as SINR ₃ ) is calculated based on γ, and then a second MCS to be used for the third downlink data is determined based on the third SINR. Here, the third downlink data is transmitted at the third time after the second time.

In one embodiment, the base station allocates spatial resources to the first and second UEs when rescheduling the first UE and the second UE to be paired users. When the spatial resource allocated to the first UE and the spatial resource allocated to the second UE are not the same, for example, when MU-MIMO transmission is realized using orthogonal resources, the following equation 8 is used. , Calculate the third SINR.

The spatial resource allocated to the first UE and the spatial resource allocated to the second UE are the same, for example, NOMA transmission is realized by using non-orthogonal resources, and the first power β _{When 1} is the second power β ₂ or more, that is, the first UE is a distant user than the second UE, the third SINR is calculated by the following formula 9.

It should be pointed out that for NOMA transmission, if the first power β ₁ is less than the second power β ₂ , i.e. the first UE is a closer user than the second UE, then the base station is the user. The third SINR may be determined based on the second CQI fed back from (as described in step 602).

In another embodiment, the base station reschedules the first UE, the third UE, and the fourth UE to be paired users, the first UE, the third UE, and Spatial resources are allocated to the fourth UE to simultaneously realize orthogonal MU-MIMO transmission and non-orthogonal NOMA transmission. The spatial resources allocated to the first UE by the base station and the spatial resources allocated to the third UE are not the same, that is, MU-MIMO transmission between the first UE and the third UE. The spatial resource allocated to the first UE by the base station and the spatial resource allocated to the fourth UE are the same, that is, between the first UE and the fourth UE. Achieve NOMA transmission. When the first power is larger than the fourth power, that is, it is expressed that the first UE is a long-distance user than the fourth UE, the third SINR is calculated by the following formula 10. ..

When the first power is less than or equal to the fourth power, that is, it is represented that the first UE is a closer user than the fourth UE (eg, in FIG. 2, UE 1 is closer than UE 2). The third SINR is calculated by the following formula 11 (which is a distance user).

As described in step 602, when the first UE feeds back the second CQI (represented as CQI ₂ ) to the base station, in the above equations 8 to 11, the noise power N = 1 / CQI ₂ is there.

FIG. 7 is a schematic diagram of the configuration of the user device 700 according to the embodiment of the present application. The user device 700 receives the reception module 710 that receives the first downlink signal transmitted at the first time and the second downlink signal transmitted at the second time after the first time. The first channel quality value (for example, SINR) is estimated based on the first downlink data received by the module 710, and the base station performs multi-user transmission based on the second downlink data. An estimation module 720 that estimates the channel quality value of 2, a calculation module 730 that calculates a channel quality adjustment factor based on the first channel quality value and the second channel quality value obtained by the estimation module 720, and a channel. It includes a feedback module 740 that feeds back quality adjustment factors to the base station.

In one embodiment, the user device 700 further includes a setting module 750 that presets a plurality of candidate adjustment values.

Correspondingly, the receiving module 710 further receives the downlink control signaling to provide the first power allocated to the UE for multi-user transmission by the base station when transmitting the second downlink signal, and a first power. Acquires the second power allocated to the two UEs.

In one embodiment, the calculation module 730 calculates the interference power adjustment value based on the first channel quality value, the second channel quality value, the first power acquired by the receiving module 710, and the second power. Then, the difference between the interference power adjustment value and each candidate adjustment value set in the setting module 750 is determined, and the candidate adjustment value corresponding to the smallest difference among the determined differences is set as the channel quality adjustment factor. ..

In one embodiment, the setting module 750 statistics the probability distribution of the interference power adjustment values calculated before the second time, and determines the probability value corresponding to each interference power adjustment value based on the probability distribution. The probability values are divided into groups, the interference power adjustment values corresponding to the probability values in each group are averaged, and the obtained average value is determined as a candidate adjustment value.

In one embodiment, the estimation module 720 acquires the multi-user transmission parameters from the second downlink signal, estimates the second channel quality value using the multi-user transmission parameters, and estimates the multi-user transmission. User transmission parameters include the power and precoding matrix allocated to the first UE and the power allocated to at least one second UE of the plurality of UEs.

In one embodiment, the receiving module 710 further receives radio resource control (RRC) signaling, and the feedback module 740 further base stations the channel quality regulator in response to the RRC signaling received by the receiving module 710. Give feedback to.

In one embodiment, the feedback module 740 feeds back the channel quality regulator to the base station on the physical uplink control channel (PUCCH) or physical uplink shared channel (PUSCH).

FIG. 8 is a schematic diagram of the configuration of the base station 800 according to the embodiment of the present invention. The base station 800 transmits the first downlink signal at the first time, so that the first user equipment (UE) estimates the first channel quality value based on the first downlink signal. By transmitting the second downlink signal at the second time in this way, the quality of the second channel when the first UE performs multi-user transmission by the base station based on the second downlink signal. The transmission module 810 that estimates the values and calculates the channel quality adjustment factor based on the first channel quality value and the second channel quality value, and the channel quality adjustment factor fed back from the first UE. A receiving module 820 for receiving and a scheduling module 830 for determining a modulation coding method (MCS) to be used for the downlink signal of the first UE based on the channel quality adjusting factor received by the receiving module 820 are provided.

In one embodiment, the second downlink signal is sent to the power and precoding matrix for multi-user transmission assigned to the first UE, and to at least one second UE among the plurality of UEs. It may include the allocated power for multi-user transmission.

In one embodiment, the scheduling module 830 is assigned to the first power assigned to the first UE, the second power assigned to the second UE, and the channel quality regulator when transmitting the second downlink signal. Based on, a third channel quality value (eg, SINR) is calculated and used for the third downlink signal transmitted at the third time after the second time based on the third channel quality value. Determine the MCS.

によって、第３のチャネル品質値を算出し、第１のＵＥに割り当てられた空間リソースと、第２のＵＥに割り当てられた空間リソースとが同じであり、かつ、第１の電力が第２の電力以上である場合、

によって、第３のチャネル品質値を算出し、ここで、γはチャネル品質調整因子であり、β_１は第１の電力であり、β_２は第２の電力であり、Ｎは雑音電力である。 In one embodiment, the scheduling module 830 allocates spatial resources to the first and second UEs, and the spatial resources allocated to the first UE and the spatial resources allocated to the second UE are the same. If not,

Calculates the third channel quality value, the spatial resource allocated to the first UE and the spatial resource allocated to the second UE are the same, and the first power is the second. If it is more than power

Therefore, the third channel quality value is calculated, where γ is the channel quality adjusting factor, β ₁ is the first power, β ₂ is the second power, and N is the noise power. ..

In one embodiment, the second UE includes a third UE and a fourth UE, and the second power is allocated to the third UE and the third UE allocated to the third UE. Also includes a fourth power source.

によって、第３のチャネル品質値を算出し、第１の電力が第４の電力以下である場合、

によって、第３のチャネル品質値を算出し、ここで、γはチャネル品質調整因子であり、β_１は第１の電力であり、β_３は第３の電力であり、β_４は第４の電力であり、Ｎは雑音電力である。 In the scheduling module 830, the spatial resource allocated to the first UE and the spatial resource allocated to the third UE are not the same, and the spatial resource allocated to the first UE by the base station and the fourth UE. When spatial resources are allocated to the first UE, the third UE, and the fourth UE so that the spatial resources allocated to the UEs are the same, and the first power is greater than the fourth power.

When the third channel quality value is calculated by, and the first power is less than or equal to the fourth power,

Therefore, the third channel quality value is calculated, where γ is the channel quality regulator, β ₁ is the first power, β ₃ is the third power, and β ₄ is the fourth power. It is electric power, and N is noise electric power.

In one embodiment, the base station 800 statistics the block error rate based on the result of the downlink hybrid automatic repeat request, and if the block error rate is greater than a predetermined threshold, the control module transmits a control command to the transmission module 810. 840 is further provided.

In response to this, the transmission module 810 further transmits downlink control signaling according to the control command to notify the UE to feed back the channel quality regulator.

According to the method of feeding back the channel quality provided in the embodiment of the present invention, the UE calculates the channel quality adjusting factor, and the channel quality adjusting factor is fed back to the base station, so that the base station becomes the UE. It is possible to know the estimated channel quality deviation during multi-user transmission. In addition, the base station can determine the MCS to use for the actual downlink signal transmission based on this channel quality regulator, effectively improving the accuracy of the MCS in subsequent transmissions and downlink scheduling. Can improve the accuracy of.

As a matter of explanation, not all steps and modules are required in each flow and each block diagram described above, and some steps or modules may be ignored as needed in practice. The execution order of each step is not constant and may be adjusted as necessary. The division of each module is merely a functional division for convenience of explanation, and when it is actually realized, one module may be realized by a plurality of separated modules, or the functions of the plurality of modules may be realized. It may be realized by the same module. These modules may be located in the same device or in different devices. Further, the "first" and "second" used in the above explanation are merely for conveniently distinguishing two objects having the same meaning, and indicate that there is a substantial difference. Not.

The modules in each example may be implemented in a hardware manner or in a hardware platform software manner.

The hardware may be implemented by dedicated hardware or hardware that executes machine-readable directives. For example, the hardware may be a specially configured permanent circuit or logic device (eg, a dedicated processor such as an FPGA or ASIC) to perform a particular operation. The hardware may include programmable logic devices or circuits (eg, including general purpose processors and other programmable processors) that are temporarily configured by the software to perform certain operations.

The software contains machine-readable directives and is stored in a non-volatile storage medium. For this reason, each example may be referred to as a software product. The machine-readable directive allows an operating system running on a computer or the like to perform some or all of the processing described here. The non-volatile computer-readable storage medium may be plugged into memory provided on an expansion board within the computer or written to memory provided on an expansion unit connected to the computer. The CPU mounted on the expansion board or the expansion unit can execute some or all of the actual processing according to the command.

Non-volatile computer readable storage media include floppy disks, hard disks, optical magnetic disks, optical disks (for example, CD-ROM, CD-R, CD-RW, DVD-ROM, DVD-RAM, DVD-RW, DVD + RW), magnetic tapes. , Non-volatile memory card, and ROM. Alternatively, the program code may be downloaded from the server computer via a communication network.

To summarize the above, the scope of claims is not limited to the embodiments in the examples described above and should be most broadly interpreted with reference to the specification as a whole.

700 User equipment 710 Receive module 720 Estimate module 730 Calculation module 740 Feedback module 750 Setting module 800 Base station 810 Transmit module 820 Receive module 830 Scheduling module 840 Control module

Claims (20)

A method of feeding back channel quality, used in the first user equipment (UE).
The first downlink signal transmitted at the first time is received, and the first channel quality value is estimated based on the first downlink signal.
A second channel quality value when the base station performs multi-user transmission based on the second downlink signal transmitted at the second time after the first time and based on the second downlink signal. Estimate and
A channel quality adjusting factor is calculated based on the first channel quality value and the second channel quality value.
The channel quality adjusting factor is fed back to the base station, and the base station adjusts the channel quality of the first UE at the time of multi-user transmission estimated by the base station based on the channel quality adjusting factor. Including providing for multi-user transmission using the tuned channel quality.
The method characterized in that the multi-user transmission is a downlink transmission from a base station to a plurality of UEs including the first UE using the same time frequency resource. Set multiple candidate adjustment values in advance
Further including acquiring the first power allocated to the first UE and the second power allocated to the second UE when the second downlink signal is transmitted by the base station.
To calculate the channel quality adjusting factor based on the first channel quality value and the second channel quality value
The interference power adjustment value is calculated based on the first channel quality value, the second channel quality value, the first power, and the second power.
The feature is that the difference between the interference power adjustment value and each candidate adjustment value is determined, and the candidate adjustment value corresponding to the smallest difference among the determined differences is used as the channel quality adjustment factor. The method according to claim 1. Setting the plurality of candidate adjustment values in advance
The probability distribution of the interference power adjustment value calculated before the second time is statistic, and the probability value corresponding to each interference power adjustment value is determined based on the probability distribution.
A claim comprising grouping the probability values, averaging the interference power adjustment values corresponding to the probability values in each group, and determining the obtained average value as the candidate adjustment value. Item 2. The method according to item 2. To calculate the interference power adjustment value based on the first channel quality value, the second channel quality value, the first power, and the second power
From the downlink control signaling, it is determined whether or not the spatial resource allocated to the first UE by the base station and the spatial resource allocated to the second UE are the same.
When it is determined by the base station that the spatial resource allocated to the first UE and the spatial resource allocated to the second UE are not the same.

The interference power adjustment value λ is calculated by
It is determined that the spatial resource allocated to the first UE by the base station and the spatial resource allocated to the second UE are the same, and the first power is the second power. If so,

Including calculating the interference power adjustment value λ by
Here, SINR ₁ is the first channel quality value, SINR ₂ is the second channel quality value, β ₁ is the first power, and β ₁ is the second power. The method according to claim 2, wherein the method is characterized by the above. The second UE includes a third UE and a fourth UE, and the second power is allocated to the third power allocated to the third UE and to the fourth UE. Including the fourth power
To calculate the interference power adjustment value based on the first channel quality value, the second channel quality value, the first power, and the second power
From the downlink control signaling, the spatial resource allocated to the first UE by the base station and the spatial resource allocated to the third UE are not the same and are allocated to the first UE by the base station. Determined that the allocated spatial resource and the spatial resource allocated to the fourth UE are the same,
When the first power is larger than the fourth power,

The interference power adjustment value λ is calculated by
When the first power is less than or equal to the fourth power

Including calculating the interference power adjustment value λ by
Here, SINR ₁ is the first channel quality value, SINR ₂ is the second channel quality value, β ₁ is the first power, and β ₃ is the third power. The method according to claim 2, wherein β ₄ is the fourth electric power. Estimating the second channel quality value when the base station performs multi-user transmission based on the second downlink signal is
1. The first aspect of the present invention includes obtaining a parameter of multi-user transmission from the second downlink signal and estimating the quality value of the second channel using the parameter of the multi-user transmission. The method described in. The multi-user transmission parameter is characterized by including the power and precoding matrix allocated to the first UE and the power allocated to at least one second UE of the plurality of UEs. The method according to claim 6. Claims 1 to 7, further comprising notifying the first UE to feed back the channel quality regulator to the base station via radio resource control (RRC) signaling. The method according to any one item. It is a user device (UE)
A receiving module that receives the first downlink signal transmitted at the first time and the second downlink signal transmitted at the second time after the first time.
Estimate the first channel quality value based on the first downlink signal, and estimate the second channel quality value when the base station performs multi-user transmission based on the second downlink signal. Module and
A calculation module that calculates channel quality adjustment factors based on the first channel quality value and the second channel quality value, and
The channel quality adjusting factor is fed back to the base station, and the base station adjusts the channel quality of the first UE at the time of multi-user transmission estimated by the base station based on the channel quality adjusting factor. A feedback module for performing multi-user transmission using the tuned channel quality.
Here, the multi-user transmission is a downlink transmission from a base station to a plurality of UEs including the first UE, using the same time frequency resource. It also has a setting module that presets multiple candidate adjustment values.
By receiving the downlink control signaling, the receiving module further receives the first power allocated to the UE at the time of transmitting the second downlink signal by the base station and the second power allocated to the second UE. Get 2 power and
The calculation module calculates an interference power adjustment value based on the first channel quality value, the second channel quality value, the first power, and the second power, and calculates the interference power adjustment value. The UE according to claim 9, wherein the difference between the and each candidate adjustment value is determined, and the candidate adjustment value corresponding to the smallest difference among the determined differences is used as the channel quality adjustment factor. .. The setting module statistics the probability distribution of the interference power adjustment value calculated before the second time, determines the probability value corresponding to each interference power adjustment value based on the probability distribution, and determines the probability value corresponding to each interference power adjustment value. 10. The UE according to claim 10, wherein the UE is divided into groups, the interference power adjustment values corresponding to the probability values in each group are averaged, and the obtained average value is determined as the candidate adjustment value. The estimation module acquires multi-user transmission parameters from the second downlink signal, estimates the second channel quality value using the multi-user transmission parameters, and sets the multi-user transmission parameters. 10. The tenth aspect of claim 10, wherein the power and precoding matrix allocated to the first UE and the power allocated to at least one second UE among the plurality of UEs are included. UE. The receiving module further receives radio resource control (RRC) signaling and
The feedback module further relates to any one of claims 9 to 12, further comprising feeding back the channel quality regulator to the base station in response to the RRC signaling received by the receiving module. The described UE. The feedback module is any one of claims 9 to 12, wherein the feedback module feeds back the channel quality adjusting factor to the base station through a physical uplink control channel (PUCCH) or a physical uplink shared channel (PUSCH). UE described in. It ’s a base station,
By transmitting the first downlink signal at the first time, the first user equipment (UE) is made to estimate the first channel quality value based on the first downlink signal, and the first By transmitting the second downlink signal at the second time after the first time, the first UE causes the base station to perform multi-user transmission based on the second downlink signal. A transmission module that estimates the channel quality value of 2 and calculates a channel quality adjusting factor based on the first channel quality value and the second channel quality value.
A receiving module that receives the channel quality adjusting factor fed back from the first UE, and
A scheduling module that determines the modulation coding method (MCS) used for the downlink signal of the first UE when performing multi-user transmission based on the channel quality adjusting factor is provided.
The base station is characterized in that the multi-user transmission is downlink transmission from the base station to a plurality of UEs including the first UE using the same time frequency resource. The scheduling module is based on the first power allocated to the first UE, the second power allocated to the second UE, and the channel quality regulator when transmitting the second downlink signal. , A third channel quality value is calculated, and based on the third channel quality value, the MCS to be used for the third downlink signal transmitted at the third time after the second time is determined. The base station according to claim 15, characterized in that. The scheduling module allocates spatial resources to the first UE and the second UE, and the spatial resources allocated to the first UE and the spatial resources allocated to the second UE are not the same. If not,

Calculates the third channel quality value, the spatial resource allocated to the first UE and the spatial resource allocated to the second UE are the same, and the first power Is greater than or equal to the second power

Therefore, the third channel quality value is calculated, where γ is the channel quality adjusting factor, β ₁ is the first power, β ₂ is the second power, and N is the second power. The base station according to claim 16, wherein the base station is noise power. The second UE includes a third UE and a fourth UE, and the second power is allocated to the third power allocated to the third UE and to the fourth UE. Including the fourth power
In the scheduling module, the spatial resource allocated to the first UE and the spatial resource allocated to the third UE are not the same, and the spatial resource allocated to the first UE by the base station. , The spatial resource is allocated to the first UE, the third UE, and the fourth UE so that the spatial resource allocated to the fourth UE is the same, and the first power is generated. If it is larger than the fourth power,

When the third channel quality value is calculated and the first power is equal to or less than the fourth power,

Therefore, the third channel quality value is calculated, where γ is the channel quality adjusting factor, β ₁ is the first power, β ₃ is the third power, and β ₄ The base station according to claim 16, wherein is the fourth electric power and N is the noise electric power. The second downlink signal includes the power and precoding matrix allocated to the first UE, and the power allocated to at least one second UE among the plurality of UEs. The base station according to claim 15. A control module that statistics the block error rate based on the result of the downlink hybrid automatic repeat request and transmits a control command to the transmission module when the block error rate is larger than a predetermined threshold value is further provided.
Any of claims 15 to 19, wherein the transmission module further transmits downlink control signaling in accordance with the control command to notify the UE to feed back the channel quality regulator. The base station described in item 1.

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