CN102271031B

CN102271031B - A kind of method and system of feedback of channel information

Info

Publication number: CN102271031B
Application number: CN201110226934.3A
Authority: CN
Inventors: 陈艺戬; 杨勋; 李儒岳; 戴博
Original assignee: ZTE Corp
Current assignee: ZTE Corp
Priority date: 2011-08-09
Filing date: 2011-08-09
Publication date: 2018-02-06
Anticipated expiration: 2031-08-09
Also published as: CN102271031A

Abstract

The invention discloses a kind of method and system of feedback of channel information, and the transfer resource available position of control signaling can be obtained by UE, CSI is calculated according to the transfer resource available position of acquisition and feeds back；Wherein, CSI represents the one or more in rank indication information, pre-coding matrix instruction information, channel quality indication (CQI) information.Furthermore it is also possible to for terminal to the channel of same base station, UE calculates the CSI of at least two same types, and feeds back to base station.The inventive method and system can improve feedback accuracy, and reduce expense.

Description

Method and system for feeding back channel information

Technical Field

The present invention relates to the field of communications, and in particular, to a method and a system for channel information feedback.

Background

Currently, in order to increase the capacity of a multiple-input multiple-output (MIMO) system, a common method is to use a precoding technique. Closed-loop precoding is a precoding technique with the best performance, but a base station needs to acquire Channel State Information (CSI) of a downlink channel to determine a modulation mode, a code rate, a rank and precoding used when data is sent to a terminal, so as to ensure that the terminal obtains the most accurate Information amount in unit time. In a Frequency Division Duplex (FDD) system, an uplink channel and a downlink channel have no reciprocity, and therefore, a terminal needs to measure the downlink channel to obtain channel state information and feed the channel state information back to a base station. The CSI fed back by the terminal includes CQI (Channel Quality Indicator), RI (Rank Indicator), PMI (Precoding Matrix Indicator) suitable for a current Channel. The CQI indicates a modulation scheme and a code rate of a channel.

In the Long Term Evolution (LTE) plan, there are two main downlink channels: a Physical Downlink Control Channel (PDCCH) and a Physical Downlink Shared Channel (PDSCH). And the base station sends control signaling information to the terminal through the PDCCH. The base station transmits data information to the terminal through the PDSCH. In LTE, because the PDCCH uses a diversity technique, the PDCCH does not need to perform precoding according to CSI information, and the CSI obtained by the base station is mainly used for PDSCH, so both the feedback content and the feedback mode of the CSI are for adapting to the requirements of PDSCH.

In release (R)11 of 3GPP LTE (Long Term Evolution-Advanced), due to the requirement of PDCCH capacity expansion, some resource locations may be opened up in the original PDSCH region as transmission resources of PDCCH, and a closed-loop precoding technique is used, as shown in fig. 1. Thus, the terminal is required to feed back CSI for PDCCH. However, the current feedback method has the following problems:

the current CSI feedback content and feedback method are designed for PDSCH, and although the CSI feedback content and feedback method are also used for describing and feeding back channel information, the PDCCH has a much higher requirement for robustness than PDSCH, and the system has a relatively strict requirement for error rate of control signaling data transmitted through PDCCH. Moreover, the PDCCH is generally transmitted without using many layers, so the accuracy of the existing CSI cannot meet the requirements of the PDCCH. In addition, if the feedback accuracy is improved, a large amount of feedback overhead is usually brought.

Disclosure of Invention

In view of the above, the present invention provides a method and a system for feeding back channel information to improve the feedback accuracy and reduce the overhead.

In order to achieve the purpose, the technical scheme of the invention is realized as follows:

a method of channel information feedback, the method comprising:

a user terminal UE obtains a transmission resource available position of a control signaling, and calculates and feeds back channel state information CSI according to the obtained transmission resource available position;

wherein, the CSI represents one or more of rank indication information RI, precoding matrix indication information PMI and channel quality indication information CQI.

The manner of obtaining the available location of the control signaling transmission resource by the UE comprises at least one of the following:

the base station configures the available position of transmission resources for the UE through signaling, wherein the available position comprises one or more RBs;

or, calculating the available position of the control signaling transmission resource according to the radio network temporary identifier RNTI.

And when the CSI refers to the RI, the value of the RI is limited within the range of {1,2 }.

When the CSI refers to PMI or CQI, the PMI or CQI is calculated according to the RI fixed as 1 or 2.

And when the CSI refers to PMI or CQI, calculating the PMI or CQI according to the calculated RI value.

The process of calculating the CSI includes:

aiming at a channel from a terminal to the same base station, the UE calculates at least two pieces of CSI with the same type and feeds back the CSI to the base station;

the CSI comprises at least one first CSI and at least one second CSI which is the same as the first CSI in type; the first CSI characterizes channel information of one or more subbands; the second CSI characterizes channel information of RBs contained in the one or more subbands;

the base station also calculates a third CSI according to the first CSI and the second CSI through a function relation F; the third CSI characterizes channel information of RBs included in the one or more subbands.

And when the CSI is fed back, the first CSI and the second CSI are simultaneously subjected to aperiodic feedback through a Physical Uplink Shared Channel (PUSCH) or periodic feedback through a Physical Uplink Control Channel (PUCCH).

A method for feeding back channel information comprises that UE calculates at least two pieces of CSI of the same type aiming at channels from a terminal to the same base station and feeds back the CSI to the base station;

A system for feeding back channel information comprises a transmission resource available position acquisition unit and a CSI feedback unit; wherein,

the transmission resource available position obtaining unit is used for obtaining the transmission resource available position of the control signaling;

the CSI feedback unit is used for calculating CSI according to the obtained available position of the transmission resource and feeding back the CSI;

wherein, the CSI represents one or more of RI, PMI and CQI.

The transmission resource available position obtaining unit, when obtaining the control signaling transmission resource available position, is configured to:

configuring the available position of transmission resources for the UE through a signaling sent by a base station, wherein the available position comprises RBs; or,

and calculating the available position of the control signaling transmission resource according to the RNTI.

When the CSI refers to PMI or CQI, the CSI feedback unit is configured to, when calculating the PMI or CQI: calculated as RI fixed as 1 or 2.

When the CSI refers to PMI or CQI, the CSI feedback unit is configured to, when calculating the PMI or CQI: and calculating PMI or CQI according to the calculated RI value.

When the CSI feedback unit calculates the CSI, it is configured to:

aiming at a channel from a terminal to the same base station, calculating at least two pieces of CSI with the same type, and feeding back the CSI to the base station;

obtaining a third CSI according to the first CSI and the second CSI through a function relation F; the third CSI characterizes channel information of RBs included in the one or more subbands.

The CSI feedback unit, when feeding back CSI, is configured to: and performing aperiodic feedback on the first CSI and the second CSI through a PUSCH or periodic feedback through a PUCCH at the same time.

The available transmission resource position acquisition unit and the CSI feedback unit are arranged in the UE.

A system for feeding back channel information comprises a UE and a base station; wherein,

aiming at a channel from a terminal to the same base station, the UE is used for calculating at least two pieces of CSI of the same type and feeding back the CSI to the base station;

the base station is used for calculating according to the first CSI and the second CSI through a function relation F to obtain a third CSI; the third CSI characterizes channel information of RBs included in the one or more subbands.

The method and the system can improve the feedback precision and reduce the expenditure.

Drawings

Fig. 1 is a schematic diagram of PDCCH expansion;

FIG. 2 is a schematic diagram of RB locations allocated for physical layer control signaling of a user;

fig. 3 is a simplified channel information feedback process according to an embodiment of the present invention;

fig. 4 is a system diagram of channel information feedback according to an embodiment of the present invention.

Detailed Description

In practical applications, the available location of the control signaling transmission resource may be obtained by a User Equipment (UE), such as a terminal. The UE calculates CSI according to the obtained available position of the transmission resource; the CSI may refer to one or more of RI, PMI, CQI. And the UE feeds the CSI back to the base station.

Further, there are various ways for the UE to obtain the available location of the control signaling transmission resource, such as: obtaining the signaling configuration sent by a base station; or, the base station configures RBs needing blind detection for the UE through high-level RRC signaling; or the UE calculates the available position of the control signaling transmission resource according to a Radio Network Temporary Identifier (RNTI).

Further, when the CSI refers to RI, the value of RI is limited to {1,2 }; when the CSI refers to PMI or CQI, the PMI or CQI is calculated according to the RI fixed as 1 or 2. The RI is specifically fixed to 1 or 2 and is indicated by the base station in a manner of transmitting higher layer signaling.

It should be noted that, for the same base station channel, the UE may calculate at least two CSIs and feed back the CSI to the base station, where the CSI may indicate one or more of RI, PMI, and CQI. One CSI is taken as a first CSI and represents channel information of one or more sub-bands in at least two CSIs fed back by the UE; and the other CSI is used as second CSI and is used for representing the channel information of the RB contained in one or more sub-bands.

When feeding back CSI, the UE feeds back at least two CSI to the base station, where the first CSI and the second CSI may perform periodic feedback through a Physical Uplink Control Channel (PUCCH) at the same time, or both the first CSI and the second CSI may perform aperiodic feedback through a Physical Uplink Shared Channel (PUSCH).

When the CSI refers to PMI, the second PMI characterizes PMI information of RBs contained in one or more sub-bands; when the CSI refers to CQI, the second CQI characterizes CQI information of RBs included in one or more subbands. When the CSI refers to RI, the RI value is limited in a {1,2} range; when the second CSI refers to PMI or CQI, the PMI or CQI is calculated according to RI fixed as 1 or 2 when being calculated. The RI is specifically fixed to 1 or 2 and is indicated by the base station in a manner of transmitting higher layer signaling.

The base station obtains a third CSI according to the first CSI and the second CSI through a function relation F; the third CSI characterizes channel information of RBs included in the one or more subbands.

The invention is described below with reference to the drawings and examples.

Example 1;

step 101:

the base station configures the available positions of the control signaling transmission resources for the UE, and as shown in fig. 2, the physical layer control signaling of user 1 is allocated in some or all of RB (0), RB (5), RB (9), and RB (14). Here, RB (i) represents all 14 rectangle positions on the i +1 th row from top to bottom in fig. 2, and the time-frequency resource position where the 14 rectangles are located represents 1 RB. Each rectangle represents the length of 1 OFDM symbol in the time domain and the length of 12 subcarriers in the frequency domain. At this time, the base station does not notify the UE of specific location information, but the UE accurately knows the location information through blind detection. Therefore, RB (0), RB (5), RB (9), RB (14) are all possible transport locations for physical layer control signaling for UE 1.

Or, the UE calculates possible transmission resources of the physical layer control signaling through the RNTI. The available position of the UE may also be RB (0), RB (5), RB (9), RB (14), or another RB obtained by this method.

Step 102:

the UE calculates CSI according to the available position of the transmission resource configured by the base station; the CSI may indicate one or more of RI, PMI, CQI.

For RB (0), RB (5), RB (9), and RB (14), the UE calculates an RI in a unified manner, where the RI may be a value selected from a set of value ranges that is most suitable for the current channel condition, and the RI is actually information of the best number of layers that the UE recommends to the base station for PDCCH downlink transmission. Such as: the UE selects an RI for the RBs in common, for example, RI ═ 1.

The UE may select an RI for each of the RBs, for example, RI x1 for RB (0), RI x2 for RB (5), RI x3 for RB (9), and RI x4 for RB (14); wherein, x1, x2, x3 and x4 are the same or different values and all belong to the value range set of RI. Such as: x1 ═ 1, x2 ═ 2, x3 ═ 1, and x4 ═ 2; for another example: x 1-3, x 2-2, x 3-1, x 4-2, etc.

The PMI represents the index of a certain code word in the codebook, and the code word can well quantize the characteristic vector information of the corresponding resource and can perform more accurate precoding after being recommended to the base station. Such as: for RB (0), the UE finds the most suitable code word from the codebook corresponding to RI according to RI information. Taking a 4-antenna codebook as an example, the codebook table is shown in table 1.

TABLE 1

Wherein,i is a unit array, and I is a unit array,a representation matrix W_kThe (j) th column of vectors,a representation matrix W_kJ (d) of₁,j₂,...,j_nA matrix of code words formed of the columns,represents u_nThe conjugate transpose matrix of (a); wherein n represents a serial number and takes a value of 0 to 15.

Such as: RI of RB (0) is 1, and the selected PMI is calculated as 12, thereby representing a codeword matrixFor another example: RI of RB (9) is 3, and the selected PMI is 6, which indicates the codeword matrix

The CQI indicates a modulation scheme, a coding rate, and an efficiency that are used for a codeword stream that is not layered before precoding on the premise that a certain error rate is satisfied. Table 2 shows a CQI table with an overhead of 4 bits. When RI is 1, the number of codeword streams is 1. When RI is 2, the number of codeword streams is 2. Such as: if RI employed is 1, RB (14) employs 1 codeword stream whose CQI is 8. For another example: RB (5), if the RI employed is 2, 2 codeword streams are employed, CQI of the 1 st codeword stream is 2, and CQI of the 2 nd codeword stream is 3.

TABLE 2

Step 103:

and the UE feeds the CSI back to the base station.

When the UE feeds back the CSI, the CSI may be fed back periodically or aperiodically. When the UE feeds back the CSI periodically, the UE loads the CSI on an uplink channel PUCCH; when the UE feeds back the CSI aperiodically, the UE loads the CSI on an uplink channel PUSCH.

Example 2;

in step 102 of embodiment 1, the value range of RI is {1,2 }.

Defining the value range of RI as {1,2}, there may be the following advantages:

1) the low rank can better keep the robustness of PDCCH transmission;

2) the wrong selection probability of the RI can be reduced, and the performance loss caused by the rollback condition of the RI can be avoided;

3) the feedback overhead of the terminal is reduced to 1 bit.

For example, if the value range of RI is defined as {1,2,3,4,5,6,7,8} in 8 antennas, the feedback overhead of each RI needs 3 bits at this time; if the value range of RI is limited to {1,2}, the feedback overhead of each RI only needs 1 bit.

In addition, if the value range of RI is defined as {1,2,3,4,5,6,7,8}, according to the existing RI calculation method, it may often happen that RI is greater than 2 in the uncorrelated channels, for example, RI is 3. In this way, after the base station receives RI 3 recommended by the UE, RI 2 may be set again to ensure the robustness of PDCCH transmission, and at this time, the PMI and CQI corresponding to the RI need to be recalculated, thereby causing a certain performance loss.

As described above, in step 102 of embodiment 1, the value range of RI can be limited to {1,2 }.

Example 3;

in step 102 of embodiment 1, the base station defines, through higher layer signaling, that the value of RI is 1 or 2. The UE does not need to calculate RI, and directly calculates PMI and CQI under RI sent by the base station.

Thus, the UE does not need to feed back the RI, and the feedback overhead of the RI can be reduced to 0.

If the base station informs the UE that the RI is 1, the UE sets the searched codebook to be a codebook with the rank of 1, and sets the number of the code word streams to be 1. According to such setting, the UE calculates PMI and CQI from the downlink channel.

If the base station informs the UE that the RI is 2, the UE sets the searched codebook to be a codebook with the rank of 2, and sets the number of the code word streams to be 2. According to such setting, the UE calculates the PMI, the CQI of the 1 st codeword stream, and the CQI of the 2 nd codeword stream from the downlink channel.

Example 4;

step 401:

the base station configures the available positions of control signaling transmission resources RB (i1), RB (i2), … and RB (im) for the UE.

Step 402:

the UE measures the CSI used for data transmission and feeds back the CSI on the PUSCH by adopting a 1-2 mode, wherein the 1-2 mode refers to a feedback mode of the UE on the PUSCH in the LTE standard. In the 1-2 mode, if RI is 1, the CSI includes: PMI of each sub-band SB (1), SB (2), …, SB (n) and CQI of the 1 st codeword stream of the full-width band over the entire bandwidth.

Step 403:

the UE obtains the sub-bands SB (j1), SB (j2), … and SB (jm) corresponding to RB (i1), RB (i2), … and RB (im).

Step 404:

PMIs of RB (i1), RB (i2), … and RB (im) are respectively calculated by taking PMIs of sub-bands SB (j1), SB (j2), … and SB (jm) as first PMIs. The PMI of RB (i1), RB (i2), …, RB (im) obtained here is the second PMI fed back.

Example 5;

taking RI 1 as an example, in step 404 in embodiment 4, the PMI is calculated by:

step 501:

table 3 shows a two-level codebook having rank RI of 1, L1 denotes a one-level codebook, and L2 denotes a two-level codebook. The L1 codebook is a 4-antenna codebook of rank 1 in table 1. Obviously, the PMI overhead for identifying one codeword in L1 is 4 bits. The PMI overhead of one codeword in identity L2 is 6 bits. The codebooks used for the subbands SB (j1), SB (j2), … and SB (jm) are L1. The codebooks used for RB (i1), RB (i2), … and RB (im) are L2. In order to reduce the feedback overhead of RB (i1), RB (i2), …, RB (im), the characteristic that the chord distances of the codewords of RB (i1), RB (i2), …, RB (im) and the corresponding codewords of SB (j1), SB (j2), …, SB (jm) are close can be fully utilized, and the 4-to-1 relationship is established between the codewords in L2 according to the near-far relationship of the codewords and the codewords in L1. Thus, each codeword in the L1 codebook corresponds to a small codebook of 4 codewords. The small codebook is a subset of the two-level codebook L2. RB (i1), RB (i2), … and RB (im) can determine a subset of L2 according to PMI of SB (j1), SB (j2), … and SB (jm), and thenThe codewords are obtained in this subset, so that the overhead can be effectively reduced while maintaining performance. Thus, the codewords in L2 obtained from RB (i1), RB (i2), … and RB (im) are identified as PMIs_SB×4+PMI_RB. The PMI_SB、PMI_RBAnd 4-bit and 2-bit PMIs respectively representing subband and corresponding RB feedback. If the PMI of SB (j1) corresponding to RB (i1) is 6, then from the two-level codebook table shown in table 3, the codebook C (6) used by RB (i1) has 4 codewords:

1)[0.5；-0.4410-0.2357i；0.2778+0.4157i；-0.0490-0.4976i]；

2)[0.5；-0.3865-0.3172i；0.0975+0.4904i；0.2357-0.4410i]；

3)[0.5；-0.3172-0.3865i；-0.0975+0.4904i；0.4410-0.2357i]；

4)[0.5；-0.2357-0.4410i；-0.2778+0.4157i；0.4976+0.0490i]；

step 502:

and the UE calculates and selects proper code words from 4 code words in the codebook C (6) according to the downlink channel information of the RB (i1), and feeds back the corresponding PMI. The range of values of PMI is {1,2,3,4 }. The PMI feedback overhead of SB (j1) is 4 bits. The PMI feedback overhead of RB (i1) is 2 bits. By using the secondary structure, the channel information feedback overhead of the control signaling resource can be effectively reduced.

Similarly, the PMI of RB (i2), …, RB (im) can be calculated according to the above steps.

TABLE 3

Example 6;

step 601:

Step 602:

the UE measures CSI used for data transmission and feeds back the CSI on a PUSCH by adopting a 3-1 mode, wherein the 3-1 mode refers to a feedback mode of the UE on the PUSCH in the LTE standard. In 3-1 mode, if RI is 1, CSI includes: CQI of the 1 st codeword stream of the full bandwidth, PMI of the full bandwidth, and the difference between CQI of each subband SB (1), SB (2), …, SB (n) and CQI of the full bandwidth over the entire bandwidth.

Step 603:

the UE obtains sub-bands SB (j1), SB (j2), … and SB (jm) corresponding to RB (i1), RB (i2), … and RB (im);

step 604:

the CQIs of RBs (i1), RB (i2), …, and RB (im) are calculated, respectively, using the CQIs of subbands SB (j1), SB (j2), …, and SB (jm) as the first CQI. The CQI of the RB (i1), RB (i2), …, RB (im) is the second CQI fed back.

Example 7;

taking RI 1 as an example, in step 604 of embodiment 6, the method for calculating CQI is as follows:

step 701:

the CQI for each sub-band SB (j1), SB (j2), …, SB (jm) is calculated from the differential quantization table shown in table 4 as the difference between the CQI for each sub-band SB (j1), SB (j2), …, SB (jm) and the full-bandwidth CQI over the entire bandwidth.

Differential representation of subband CQI	Offset of
		0	0
1	1
		2	≥2
3	≤-1

TABLE 4

Step 702:

the UE calculates CQI for RB (i1), RB (i2), …, RB (im) from CQI and channels of RB (i1), RB (i2), …, RB (im) shown in Table 2.

Step 703:

differences between the CQI of RB (i1), RB (i2), …, RB (im) and the corresponding CQI of SB (j1), SB (j2), …, SB (jm) are calculated, respectively. From the difference quantization table shown in table 4, difference representations of the CQIs of RB (i1), RB (i2), …, and RB (im) are obtained.

As can be seen from the above steps, if there is no differential representation of the CQIs of RB (i1), RB (i2), …, RB (im), the feedback overhead of each CQI needs 4 bits. After the differential representation, the CQIs of RB (i1), RB (i2), …, and RB (im) each require a feedback overhead of 2 bits.

With reference to the above embodiments, the operation idea of the present invention for performing channel information feedback can be represented as a flow shown in fig. 3, where the flow includes the following steps:

step 310: the UE obtains the available location of the transmission resource for the control signaling.

Step 320: and the UE calculates the CSI according to the obtained available position of the transmission resource and feeds back the CSI.

In addition, the UE can also calculate at least two pieces of CSI of the same type aiming at the channel from the terminal to the same base station and feed back the CSI to the base station; the CSI comprises at least one first CSI and at least one second CSI which is the same as the first CSI in type; the first CSI characterizes channel information of one or more subbands; the second CSI characterizes channel information of RBs contained in the one or more subbands; the base station also calculates a third CSI according to the first CSI and the second CSI through a function relation F; the third CSI characterizes channel information of RBs included in the one or more subbands.

In order to ensure the smooth implementation of the above embodiments and operation idea, the arrangement shown in fig. 4 can be performed. Referring to fig. 4, fig. 4 is a diagram of a channel information feedback system according to an embodiment of the present invention, where the system includes a transmission resource available position acquisition unit and a CSI feedback unit connected to each other. These two units may be provided in the UE.

In practical application, the transmission resource available position obtaining unit can obtain the transmission resource available position of the control signaling. And the CSI feedback unit can calculate CSI according to the obtained available position of the transmission resource and feed back the CSI.

In addition, for the channel from the terminal to the same base station, the UE may also be configured to calculate at least two pieces of CSI of the same type and feed back the CSI to the base station; the CSI comprises at least one first CSI and at least one second CSI which is the same as the first CSI in type; the first CSI characterizes channel information of one or more subbands; the second CSI characterizes channel information of RBs contained in the one or more subbands; the base station may be configured to obtain a third CSI by calculating according to the first CSI and the second CSI through a functional relationship F; the third CSI characterizes channel information of RBs included in the one or more subbands.

In summary, the channel information feedback technology of the present invention can improve the feedback accuracy and reduce the overhead regardless of the method or the system.

The above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention.

Claims

1. A method for channel information feedback, the method comprising:

a user terminal UE obtains a transmission resource available position of a control signaling, and calculates and feeds back channel state information CSI according to the obtained transmission resource available position; the method for the UE to obtain the available position of the control signaling transmission resource comprises at least one of the following steps: the method comprises the steps that the information is obtained through signaling configuration issued by a base station, or the base station configures RBs needing blind detection for UE through high-level RRC signaling, or the UE calculates according to a Radio Network Temporary Identifier (RNTI) to obtain the available position of the control signaling transmission resource;

2. The method of claim 1, wherein when the CSI refers to RI, RI value is limited to {1,2 }.

3. The method of claim 1, wherein the CSI refers to PMI or CQI, and wherein the PMI or CQI is calculated according to RI fixed as 1 or 2.

4. The method of claim 1, wherein when the CSI refers to PMI or CQI, PMI or CQI calculation is performed according to the calculated RI value.

5. The method according to any of claims 1 to 4, wherein the process of calculating the CSI comprises:

6. The method of claim 5,

7. A system for feeding back channel information is characterized in that the system comprises a transmission resource available position acquisition unit and a CSI feedback unit; wherein,

the transmission resource available position obtaining unit is used for obtaining the transmission resource available position of the control signaling; wherein, the manner of obtaining the available position of the transmission resource of the control signaling comprises at least one of: the method comprises the steps that the information is obtained through signaling configuration issued by a base station, or the base station configures RBs needing blind detection for UE through high-level RRC signaling, or the UE calculates according to a Radio Network Temporary Identifier (RNTI) to obtain the available position of the control signaling transmission resource;

wherein, the CSI represents one or more of RI, PMI and CQI.

8. The system of claim 7, wherein when the CSI refers to RI, the RI is limited to {1,2 }.

9. The system of claim 7, wherein when the CSI refers to PMI or CQI, the CSI feedback unit, when calculating the PMI or CQI, is configured to: calculated as RI fixed as 1 or 2.

10. The system of claim 7, wherein when the CSI refers to PMI or CQI, the CSI feedback unit, when calculating the PMI or CQI, is configured to: and calculating PMI or CQI according to the calculated RI value.

11. The system according to any of claims 7 to 10, wherein the CSI feedback unit, when calculating the CSI, is configured to:

12. The system of claim 11,

13. The system according to any of claims 7 to 10, wherein said transmission resource available location acquisition unit, CSI feedback unit, are located in the UE.