WO2010078685A1

WO2010078685A1 - A feedback method for the index of multiple levels codebook in a closed loop mimo system and a device thereof

Info

Publication number: WO2010078685A1
Application number: PCT/CN2009/000010
Authority: WO
Inventors: 宋扬; 蔡立羽; 朱孝龙
Original assignee: 上海贝尔股份有限公司; 阿尔卡特朗讯
Priority date: 2009-01-06
Filing date: 2009-01-06
Publication date: 2010-07-15
Also published as: CN102246426A; CN102246426B

Abstract

A feedback method for the channel information based on a multiple levels codebook in the network device of a multiple input/multiple output system and a device thereof, and a data transmission method based on a multiple levels codebook in the network device of a multiple input/multiple output system and a device thereof are provided in the present invention. The multiple levels codebook adopted in the present invention has the following characteristics: the codebook comprises multiple codeword levels, each codeword level comprises multiple codewords, one codeword not at the lowest level has one associated sub-group which is combined by some codewords being one level lower than itself, one codeword not at the highest level has one and only one associated codeword which is one level higher than itself. By using the feedback method for the channel information based on a multiple levels codebook in the network device of a multiple input/multiple output system and a device thereof, and the data transmission method based on a multiple levels codebook in the network device of a multiple input/multiple output system and a device thereof provided in the present invention, the following income can be obtained: the feedback overhead is reduced, the changing rate of the different channel characteristic is adapted, thereby the channel change is better followed.

Description

Closed loop MIMO system

Multi-level codebook index feedback method and device thereof

The present invention relates to multiple input multiple output (MIMO) technology, and more particularly to a method and apparatus for using a codebook index to feed back channel information in a closed loop multiple input multiple output antenna system. Background technique

In a closed loop multiple input multiple output system, during communication, the receiver needs to feed back channel information to the transmitter for transmission of the data signal.

Considering a MIMO system with Nt transmit antennas and Nr receive antennas, let Mt denote the number of spatial multiplexed data streams to be transmitted, and the vector X of Mt xl denotes the signals carried by these data streams, and the precoding matrix W is A matrix of Nt x Mt dimensions that transforms the X vector into a zt vector of Nt x 1 dimension:

z = Wx

The z vector is the actual signal transmitted at the transmitting antenna. The signal received at the receiving antenna is indicated as:

r = HWx + n

Where H represents the channel matrix and n represents the Gaussian white noise vector.

If the feedback overhead is not considered, the optimal choice of W is the right singular vector of the H matrix. However, the cost of feeding back these singular vectors is very large. Therefore, a limited feedback closed-loop MIMO precoding scheme has been proposed. For each transmit antenna scale, a set of precoding matrices or vectors is constructed, and this set of matrices or vectors (hereinafter referred to as matrices) is called a "codebook", and both the base station and the mobile station know this code. Here, the codebook is represented as P = {Pi , ..., P _L }, and each of the matrices is referred to as a "codeword". If = 2' indicates the size of the codebook, then q is the number of bits required to index the codebook. Taking a 4 x 2 MIMO system as an example, a codebook of size L = 64 only needs to feed back 6 bits of information for the transmitter to select the precoding matrix. When the codebook of a MIMO system is determined, the receiver detects the channel and selects the optimal codeword (precoding matrix) for the current time,

1

Confirmation The index of the codeword is then fed back to the transmitter. Through this limited codebook index feedback, the MIMO system can save a lot of feedback overhead. Figure 1 shows a system block diagram of a MIMO system with finite precoding codebook index feedback as described above. In some prior art standards, such as IEEE 802.16e, the finite precoding matrix codebook index feedback scheme has been widely adopted.

The MIMO system may also adopt a limited feedback scheme of feedback quantization channel matrix codebook index, that is, pre-construction of the quantized channel matrix codebook and stored in the transmitter and the receiver; the receiver detects the channel and selects the current from the quantized channel matrix codebook. The optimal codeword of the moment, and feeding back the index of the codeword; the transmitter determines the current channel transmission matrix according to the codeword corresponding to the index, and then calculates an optimal precoding matrix for data transmission according to the current channel transmission matrix. .

A proposed precoding matrix codebook differential feedback scheme adopts the following method: periodically (every few frames) feed back a complete precoding matrix codeword index (6 bits), in two adjacent complete codewords Shorter (less than 6 bits, for example 3 bits) differential information is fed back between the index feedbacks, the difference information being used to indicate between the new codeword and the codeword indicated by the previous codeword or the previous complete codeword index. The index number is poor, and the transmitter determines the precoding matrix codeword to be used according to the codeword indicated by the previous codeword or the last complete codeword index used and the received difference information. In the case of slow channel change, because the channel has strong correlation in time, less differential information can better track the channel changes of two adjacent frames, and compared to one complete feedback each time. The codebook index, the precoding matrix codebook differential feedback scheme can further reduce the total feedback overhead.

However, the prior art still has some drawbacks. For example, the feedback overhead of the finite precoding codebook index feedback scheme still needs to be further reduced, and the precoding matrix codebook differential feedback scheme cannot adapt well to the channel changing speed. Summary of the invention

In order to overcome the above-mentioned deficiencies in the prior art, the present invention provides a channel information feedback method and apparatus based on a multi-level codebook in a network device of a multiple input multiple output system, and a network device based on a multiple input multiple output system Level codebook data transmission method And its equipment.

According to a first aspect of the present invention, a method for feeding back channel information in a network device of a multiple input multiple output system is proposed, wherein the network device includes a predetermined codebook, the codebook including a plurality of codewords Level, each codeword level includes multiple codewords for data transmission by the peer device, and any non-lowest level codeword has a number of lower-level codewords composed of a subgroup associated with it, any non-highest level The codeword has one and only one higher level codeword associated therewith, the method comprising the steps of: a. receiving a first signal from the peer device; b. receiving, according to the received first signal, Determining a current codeword level in the predetermined codebook, and determining a first codeword from the codewords of the current codeword level; c. receiving the first codeword and/or the receiving according to the first codeword a first signal determining a feedback message to be transmitted; d. transmitting a feedback of the desired transmission determined in step c - in accordance with a second aspect of the invention, a network in a multiple input multiple output system is proposed A method for transmitting data in a device, wherein the network device includes a predetermined codebook, the codebook includes a plurality of codeword levels, and each codeword level includes a plurality of codewords for data transmission by the network device Any non-lowest level codeword having a plurality of lower level codeword components associated with a subset thereof, any non-highest level codeword having one and only one higher level codeword associated therewith, the method comprising The following steps: A. transmitting a first signal; B. receiving a feedback message from the peer device; C. determining a current codeword level according to the received feedback message and/or the last used codeword, and at the current Determining a second codeword in a codeword level codeword; D. transmitting data according to the second codeword.

According to a third aspect of the present invention, a feedback apparatus for feeding back channel information in a network device of a multiple input multiple output system is proposed, wherein the network device includes a predetermined codebook, the codebook including a plurality of codes Word level, each codeword level includes multiple codewords for data transmission by the peer device, and any non-lowest level codeword has a number of lower-level codewords composed of a subgroup associated with it, any non-highest level The codeword has one and only one high-level codeword associated therewith, and the feedback device includes: a first receiving device, configured to receive a first signal from the peer device; and a first codeword determining device, Determining a current codeword level from the predetermined codebook according to the received first signal, Determining a first codeword from the codewords of the current codeword level; the feedback message determining means, for determining the feedback to be sent according to the first codeword and/or the received first signal a feedback message sending device, configured to send a feedback message determined by the device to determine a desired feedback message.

According to a fourth aspect of the present invention, a data transmission apparatus for transmitting data in a network device of a multiple input multiple output system is proposed, wherein the network device includes a predetermined codebook, and the codebook includes a plurality of codes a word level, each codeword level includes a plurality of codewords for data transmission by the network device, and any non-lowest level codeword has a plurality of lower-level codewords composed of a subgroup associated with it, any non-highest The level codeword has one and only one higher level codeword associated therewith, and the data transmission apparatus includes: a first transmitting device, configured to send the first signal; and a second receiving device, configured to receive from the peer end a feedback message of the device; the second codeword determining means, configured to determine a current codeword level according to the received feedback message and/or the last used codeword, and determine a second in the codeword of the current codeword level And a second sending device, configured to perform data transmission according to the second codeword.

According to a fifth aspect of the invention, there is provided a network device in a multiple input multiple output system comprising the feedback device of the third aspect of the invention and/or the data transmission device of the fourth aspect of the invention.

The codebook in the present invention may be a precoding matrix codebook or a quantized channel matrix codebook. A codebook-based channel information feedback method and apparatus thereof, and a codebook-based data transmission method and apparatus thereof in a network device of a multiple input multiple output system by using a multiple input multiple output system proposed by the present invention, at least Get the following benefits:

1. The index feedback scheme based on multi-level codebook can further reduce the feedback overhead compared to the differential feedback scheme;

2. The selection of different levels of codewords can adaptively match the speed of the channel change, so that the channel can be better tracked. DRAWINGS

A detailed description of a non-limiting embodiment, with reference to the accompanying drawings, Other features, objectives and advantages of Ming will become more apparent.

Figure 1 shows a finite precoding matrix codebook index feedback in the prior art.

System of MIMO system ^ I diagram;

2 is a tree structure diagram of a multi-level codebook in an embodiment of the present invention; FIG. 3 is a flowchart showing channel information feedback in a MIMO system according to an embodiment of the present invention;

4 is a structural block diagram of a feedback device for feeding back channel information in a network device of a multiple input multiple output system according to an embodiment of the present invention;

5 is a block diagram showing the structure of a data transmission apparatus for transmitting data in a network device of a multiple input multiple output system according to an embodiment of the present invention;

6 is a schematic diagram showing a correspondence relationship between feedback information and codeword changes in a period of time according to an embodiment of the present invention;

7 is a schematic diagram showing a correspondence relationship between feedback information and codeword changes in a period of time according to an embodiment of the present invention;

Wherein, the same or similar reference numerals denote the same or similar step features or devices (modules). detailed description

The channel information feedback scheme of the MIMO system in the present invention is based on a multi-level codebook, where the codebook may be a set of precoding matrices or a set of quantized channel matrices, and each matrix in the codebook is called a codeword. .

2 shows a tree structure diagram of a multi-level codebook in one embodiment of the present invention. As shown in FIG. 2, the multi-level codebook in this embodiment is divided into three levels. The first level has a total of 4 code words, denoted as N. , N ₂ , N ₃ . The second level has a total of 16 code words, of which Ν ₀ , ₀ , Ν _0; ι , Ν ₀ , ₂ , Ν. , 3 composition and Ν. An associated second level codeword subgroup, N _u , N _{1 ;3} , is associated with a second level codeword subgroup, N ₂ ,. , N _2>1 , N ₂ , ₂ , N ₂ , ₃ constitute a second-level codeword subgroup associated with N ₂ , N ₃ ,. , N ₃ , i , N ₃ , ₂ , N ₃ , ₃ constitute a second-level codeword subgroup associated with N ₃ . The third level has a total of 64 code words, and the four groups are divided into 16 third level code word subgroups, each third level code word subgroup and a second level. Codewords are associated, for example, N. . , Q, Νοο, ι ^ Noo, 2 Now constitutes a third-level codeword subgroup associated with Νο, ο, N. _3,. , No3, l NQ ₃ , ₂ , NQ ₃ , ₃ composition and N. , a third-level codeword subgroup associated with ₃ , Ν ₃₃ , (), Ν _33>1 , N ₃₃ , ₂ , N ₃₃ , ₃ constitute a third-level codeword associated with N ₃ , ₃ Group, and so on. The association relationship between the code words in the three-level codebook in this embodiment forms a tree structure similar to the three-level quadtree. In this embodiment, the association relationship between the code words of each level may be established according to the following principles: a higher level of correlation between the code words in the same level constitutes a subgroup, and a higher level codeword associated with the subgroup It is also the one of all higher level codewords that has a higher or even higher correlation with the codewords in that subset. For example, N. Is the first level code word with NQ,. , ΝΟ, Ι, N. , 2, NQ, ₃ , the second-level codeword subgroup has the highest correlation, and 相关ο, ο, Νο, ι, No, ₂ , No, ₃ have a correlation coefficient higher than each other. The correlation coefficient between the codeword and other second-level codewords. Wherein, a non-lowest level codeword may be different from a codeword in a lower one level codeword subgroup associated therewith, for example, NQ is different from N. , _G , N ₀ , i N _Q , ₂ , N _G , ₃ . Alternatively, a non-lowest level a codeword may be taken from one level to its codeword subset associated codeword in ,, e.g., N ₀ and Νο, ο, Νο, ι, Ν. , ₂ , Ν. , _{3 of} which are the same.

In another embodiment of the invention, a two level codebook is employed. The first level has a total of 8 code words. The second level has a total of 64 code words, and the eight groups are divided into eight second level code word subgroups, and each second level code word subgroup is associated with a first level code word. In this embodiment, the association relationship between the code words of each level may be established according to the following principles: a higher level of correlation between the code words in the same level constitutes a subgroup, and a higher level codeword associated with the subgroup It is also the one of all higher level codewords that has a higher or even higher correlation with the codewords in that subset.

In summary, the multi-level codebook used in the present invention has the following features: The codebook includes a plurality of codeword levels, each codeword level includes a plurality of codewords, and a non-lowest level codeword has a plurality of lower-level codewords. A subgroup associated with it, a non-highest level codeword has one and only one higher level codeword associated with it. Those skilled in the art will appreciate that the number of codewords in a subset of codewords of a certain level is not particularly limited. In order to facilitate the unifying of the number of bits of the feedback information and the format of the feedback information, preferably, the number of codewords in each subset of codewords is the same, and more preferably, the number of codewords in the subset of codewords is an integer of two. Power. FIG. 3 is a flow chart showing channel information feedback based on a multi-level codebook in a MIMO system according to an embodiment of the present invention. The invention will now be described from a system perspective with reference to Figures 3 and 2. Although the following embodiments describe a multi-level codebook feedback scheme in the MIMO system of the present invention based on a precoding matrix codebook, those skilled in the art should be able to apply the multilevel codebook feedback scheme to a quantization channel based matrix very easily. Codebook in MIMO systems.

In accordance with an embodiment of the present invention, a multi-level precoding matrix codebook is employed in a MIMO system for data transmission, and a predetermined multi-level precoding matrix codebook is employed having a codebook structure as shown in FIG. The feedback scheme based on the multi-level precoding matrix codebook in the present invention can be used for both the uplink and the downlink. As shown in FIG. 3, the MIMO system of this embodiment includes a network device 1 and a network device 2. On the downlink, the network device 1 corresponds to the terminal device, and the network device 2 corresponds to the base station device; on the uplink, the network device 1 corresponds to the base station device, and the network device 2 corresponds to the terminal device. Both the network device 1 and the network device 2 are aware of the predetermined multi-level precoding matrix codebook.

First, in step S21, the network device 2 transmits the first signal. Typically, the first signal includes a pilot signal for channel estimation.

In step S11, the network device 1 receives the first signal from the peer device, i.e. from the network device 2.

In step S12, the network device 1 determines a current codeword level from the predetermined codebook based on the received first signal, and determines a first codeword from the codewords of the current codeword level. Typically, this first codeword is the precoding matrix that network device 2 needs to use for data transmission at a specified time thereafter.

In step S13, the network device 1 determines the feedback message that needs to be transmitted based on the first codeword and/or the received first signal. Typically, the feedback message here is used to instruct the network device 2 to use the first codeword for data transmission.

In step S14, the network device 1 transmits the feedback message that needs to be transmitted determined in step S13.

In step S22, the network device 2 receives a feedback message from the peer device, that is, from the network device 1. In step S23, the network device 2 determines the current codeword level based on the received feedback message and/or the last used codeword, and determines a second codeword in the codeword of the current codeword level. In the case where there is no error in data reception, the second codeword determined by the network device 2 should be identical to the first codeword determined by the network device 1.

In step S24, the network device 2 performs data transmission using the second codeword. According to an embodiment of the present invention, specifically, in step S12, the following two sub-steps are further included. In a first sub-step, the network device 1 determines the first channel characteristic based on the received first signal. In a second sub-step, the network device 1 determines the current codeword level from a predetermined codebook according to the first channel characteristic, and determines the first codeword from codewords of the current codeword level. . For example, when the first signal sent by the network device 2 includes a pilot signal for channel estimation, the network device 1 can determine the current channel transmission matrix H, that is, the first channel characteristic, according to the received pilot signal; Then, the network device 1 determines an optimal precoding matrix and a current codeword level according to the current channel transmission matrix H, and determines a first codeword from the codewords of the current codeword level according to the optimal precoding matrix. Typically, the first codeword is the one of all codewords at the current codeword level that best matches the optimal precoding matrix. Preferably, the network device 1 can determine which level of codeword to use based on how fast the channel characteristics change. For example, in this embodiment, there are 64 third-level codewords, and 6 bits are required to feed back a complete third-level codeword index; there are 4 first-level codewords, and a complete first-level codeword index is fed back. Only 2 bits are needed; therefore, when the feedback message is less than 6 bits and the channel characteristics change rapidly, the higher level codeword can be used to better track the change of channel characteristics. Specifically, the network device 1 can determine the speed of the channel characteristic change according to the correlation coefficient between the current channel transmission matrix H and the channel transmission matrix of the previous frame determined according to the received first frame of the previous frame. For example, you can set a high limit and a low limit. If the correlation coefficient of the channel transmission matrix of two adjacent frames is greater than the high limit, the channel change is considered to be slow, and the network device 1 determines the current codeword level as the third level; if the correlation coefficient is less than the low limit, the channel is considered The change is faster, the network device 1 determines the current codeword level as the first level; if the correlation coefficient is between the high limit value and the low limit value, the channel change speed is considered to be medium, and the network device 1 determines the current codeword level. For the second level. After determining the current codeword level, network device 1 A codeword that best matches the optimal precoding matrix can be selected from the class of codewords and determined as the first codeword.

According to some embodiments of the present invention, in order to better cooperate with the use of the multi-level codeword, two types of feedback messages are set: a first feedback message and a second feedback message, where the first feedback message is mainly used to control the codeword. The change of the level, the second feedback message is mainly used to indicate index addressing in a certain codeword subgroup, and the processing priority of the first feedback message is higher than the second feedback message. The codebook structure shown in FIG. 2 includes three levels of codewords in the codebook, and each codeword subgroup includes four codewords. Therefore, the first feedback message and the second feedback message only need to carry 2 bits. information. Those skilled in the art should understand that if other codebook structures are used, the number of information bits that each of the first feedback message and the second feedback message need to carry will also change accordingly. The MIMO system needs to set different bearer resources for the first feedback message and the second feedback message respectively. For example, different time slots/frequency in the same signal frame respectively carry the first feedback message and the second feedback message, or The same time slot/frequency in different signal frames respectively carries the first feedback message and the second feedback message. Preferably, if the frame structure specified by the IEEE 802.16 protocol family is adopted in the MIMO system, the first feedback message may be carried in the MAC PDU.

According to an embodiment of the present invention, when the network device 2 starts data communication with the network device 1, the first signal transmitted by the network device 2 will carry corresponding information indicating that it will perform the first data transmission.

In step S12, the network device 1 determines, according to the received first signal, that the network device 2 will perform the first data transmission, and the network device 1 determines a first codeword as the code used by the network device 2 for the first data transmission. Word, according to different settings, the first codeword can be any level of codeword, preferably, the first codeword can be selected from the lowest level of codewords.

In step S13, the network device 1 determines, according to the received first signal, that the network device 2 is to perform the first data transmission, the network device 1 determines to send an initial feedback message, where the initial feedback message includes the first codeword. Complete index information. In step S14, the network device 1 transmits the initial feedback message.

In step S23, the network device 2 determines that the received feedback message is initial feedback. The message, the network device 2 selects a codeword from the predetermined codebook according to the received initial feedback message to determine it as the second codeword.

In step S24, the network device 2 uses the second codeword for transmitting data. According to another embodiment of the present invention, the network device 1 determines whether to transmit the first feedback message based on the ordinal number of the signal frame.

In step S12, the network device 1 determines the first codeword.

In step S13, the network device 1 judges whether or not the frame number of the received first signal satisfies a predetermined condition. If the frame number satisfies the predetermined condition, the network device 1 determines that a first feedback message needs to be transmitted, the first feedback message including control information indicating a change in the codeword level used by the network device 2. If the frame number does not satisfy the predetermined condition, the network device 1 determines that a second feedback message needs to be transmitted, the second feedback message including index offset information. According to different settings, the index offset information may be used to indicate a relationship between the first codeword and a codeword used for data transmission of a previous frame, or to indicate the first codeword and the first one. The relationship between the code words indicated by the feedback message.

In step S14, the network device 1 transmits the feedback message that needs to be sent. Preferably, the network device 1 periodically sends a first feedback message, that is, a first feedback message is sent every certain number of frames, and those frames between two adjacent frames that send the first feedback message are sent. Second feedback message.

According to another embodiment of the invention, the first feedback message can be used to indicate that the network device 2 maintains the codeword level used.

In step S12, the network device 1 determines the first codeword.

In step S13, when the network device 1 determines that the current codeword level of the first codeword is the same as the first predetermined number of recently used codewords, it is determined that a first feedback message needs to be sent, the first feedback. The message includes control information for instructing the network device 2 to keep the codeword level used unchanged. For example, the first predetermined number may be taken as 1. If the current first codeword is a second-level codeword, and the codeword used for data transmission of the previous frame is also the second-level codeword, the network device 1 determines that it needs to send one. The first feedback message is used to indicate that the network device 2 keeps the used codeword level unchanged. Of course, the first predetermined number It can also be taken as a natural number other than 1. When the network device 1 determines that the last first feedback message includes control information for indicating that the network device 2 keeps the used codeword level unchanged, and the current codeword level of the first codeword is indicated by the previous first feedback message. The codeword level is the same, and the network device 1 determines that a second feedback message needs to be sent, and the second feedback message includes index offset information. According to different settings, the index offset information may be used to indicate a relationship between the first codeword and a codeword used for data transmission of a previous frame, or to indicate the first codeword and the first one. The relationship between the code words indicated by the feedback message. For example, the last first feedback message indicates that the network device 2 keeps the used codeword level unchanged, and the codewords used for data transmission of the current first codeword and the last few frames are both second-level codewords, and the network device 1 determines A second feedback message including index offset information needs to be sent. When the network device 1 determines that the last first feedback message includes control information for indicating that the network device 2 keeps the used codeword level unchanged, and the current codeword level of the first codeword is different from the level of the previous used codeword, The network device 1 then determines that a first feedback message needs to be sent, the first feedback message including control information for instructing the network device 2 to change the level of the codeword used. For example, the last first feedback message indicates that the network device 2 keeps the used codeword level unchanged, and the codeword used in the previous frame data transmission is the second-level codeword, and the current first codeword is the third level. The codeword, the network device 1 determines that a first feedback message needs to be sent, the first feedback message including control information for instructing the network device 2 to change the level of the codeword used.

In step S14, the network device 1 transmits the feedback message that needs to be sent. In step S22, the network device 2 receives a feedback message from the network device 1. In step S23, when the network device 2 determines that the received feedback message includes a first feedback message, the first feedback message includes control information for indicating a change in the codeword level used by the network device 2 or is used to indicate the network device. 2 Holding the control information of the used codeword level unchanged, the network device 2 determines the current codeword level according to the level of the first feedback message and the last used codeword. When the network device 2 determines that the received feedback message includes a second feedback message, where the second feedback message includes index offset information, the network device 2 determines the second according to the second feedback message and the determined current codeword level. Codeword.

In step S24, the network device 2 performs data transmission using the second codeword. According to another embodiment of the present invention, the first feedback message may be used to indicate that the network device 2 keeps the codeword used unchanged.

In step S12, the network device 1 determines the first codeword.

In step S13, when the network device 1 determines that the correlation coefficient between the first codeword and the second predetermined number of recently used codewords is greater than a first threshold, the network device 1 determines to send a first feedback message, The first feedback message includes control information for instructing the network device 2 to keep the codewords used unchanged. When the network device 1 determines that the last first feedback message includes control information for indicating that the network device 2 keeps the used codeword unchanged, and the correlation coefficient between the first codeword and the last used codeword is greater than the first threshold, Then the network device 1 determines not to send a feedback message. When the network device 1 determines that the previous first feedback message includes control information for indicating that the peer device keeps the used codeword unchanged, and the correlation coefficient between the first codeword and the last used codeword is less than The first threshold, the network device 1 determines to send a first feedback message, the first feedback message includes control information for instructing the network device 2 to change the used codeword. For example, the second predetermined number can be taken as 1. The codeword used by the network device 2 for data transmission in the nth frame is Νοο, ο, and the correlation coefficient between the first codeword of the n+1th frame determined by the network device 1 and No _Q , o is greater than the first threshold, then the network The device 1 determines that a first feedback message needs to be sent, and the first feedback message is used to indicate that the network device 2 keeps the used codeword unchanged, that is, the network device 2 will still use N in the n+1th frame data transmission. . ,. This code word. From the n+2th frame until the n+mth frame (m > 2), the first codeword determined by the network device 1 and N. . If the correlation coefficient between _Q and _Q is greater than the first threshold, the network device 1 determines that no feedback message is sent from the n+2th frame to the n+th frame, that is, the network device 2 is in the n+2th frame to the nth. This codeword will still be used in the +m frame data transfer. In the n+m+1 frame, the correlation coefficient between the first codeword and the Νοο, ο determined by the network device 1 is less than the first threshold, and the network device 1 determines to send a first feedback message for indicating the network device 2 Change the codeword used. Of course, the second predetermined number can also be taken as other natural numbers than one.

In step S14, the network device 1 transmits the feedback message that needs to be sent. In step S22, the network device 2 receives a feedback message from the network device 1. In step S23, when the network device 2 determines that the network device 1 is not received. The feedback message, and the previous feedback message includes a first feedback message for indicating that the network device 2 keeps the used codeword unchanged, and the network device 2 determines the last used codeword as the second codeword. For example, the codeword used by the network device 2 for data transmission in the nth frame is N. . ,. . The feedback message for the n+1 frame received by the network device 2 includes a first feedback message, which is used to indicate that the network device 2 keeps the codeword used, and the network device 2 will be N. _q , Q is determined as the second codeword, that is, the network device 2 will still use the codeword Νοο, ο in the n+1th frame data transmission. Next, the network device 2 does not receive the feedback message for the n+2th frame until the n+mth frame (m > 2), and the network device 2 still determines Νοο, ο as the second codeword, that is, the network. Device 2 will still use the codeword Νοο,ο in the n+2th frame until the n+mth frame data transmission.

In step S24, the network device 2 performs data transmission using the second codeword.

According to another embodiment of the present invention, the first signal sent by the network device 2 further includes an indication message for specifying a codeword level, and then in step S12, the network device 1 will be according to the received first signal. The indication message determines a current codeword level from the predetermined codebook, and selects one of the codewords of the current codeword level to be determined as the first codeword. For example, the first signal transmitted by the network device 2 in a certain frame includes both a pilot signal for channel estimation and an indication message for indicating that the next codeword uses a second level codeword. Then, after receiving the first signal, in step S12, the network device 1 estimates the channel transmission matrix 根据 according to the received pilot signal, and determines that the current codeword level is the second level according to the received indication message, and then A codeword that best matches the channel transmission matrix Η is selected from the second level codewords and determined as the first codeword.

4 is a block diagram showing the structure of a feedback device for feeding back channel information in a network device of a multiple input multiple output system according to an embodiment of the present invention. As shown in FIG. 4, the feedback device 10 includes a first feedback device 101, a first codeword determining device 102, a feedback message determining device 103, and a feedback message transmitting device 104. Fig. 5 is a block diagram showing the structure of a data transmission apparatus for transmitting data in a network device of a multiple input multiple output system according to an embodiment of the present invention. As shown in FIG. 5, the data transmission device 20 includes a first transmitting device 201, a second receiving device 202, a second codeword determining device 203, and a second transmitting device 204. The invention will now be described from a device perspective with reference to Figures 2 to 5 . In an embodiment of the present invention, a multi-level precoding matrix codebook is used in the MIMO system for data transmission, and the predetermined multi-level precoding matrix codebook used has a codebook structure as shown in FIG. 2. The feedback scheme based on the multi-level precoding matrix codebook in the present invention can be used for both the uplink and the downlink. As shown in FIG. 3, the MIMO system of this embodiment includes a network device 1 and a network device 2. On the downlink, the network device 1 corresponds to the terminal device, the network device 2 corresponds to the base station device; on the uplink, the network device 1 corresponds to the base station device, and the network device 2 corresponds to the terminal device. Typically, the feedback device 10 is configured in the network device 1 and the data transmission device 20 is configured in the network device 2. Both the feedback device 10 and the data transmission device 20 are aware of the predetermined multi-level precoding matrix codebook.

On the network device 2 side, the first signal is first transmitted by the first transmitting device 201. Typically, the first signal comprises a pilot signal for channel estimation.

On the side of the network device 1, the first signal from the peer device, i.e. from the network device 2, is first received by the first receiving device 101.

Next, the first codeword determining means 102 determines a current codeword level from the predetermined codebook based on the received first signal, and determines a first codeword from the codewords of the current codeword level. Typically, this first codeword is the precoding matrix that network device 2 needs to use for data transmission at a specified time later.

Next, the feedback message determining means 103 determines the feedback message to be transmitted based on the first codeword and/or the received first signal. Typically, the feedback message here is used to instruct the network device 2 to use the first codeword for data transmission.

Then, the feedback message transmitting device 104 transmits the feedback message that needs to be sent. Returning to the network device 2 - side, the second receiving device 202 is configured to receive a feedback message from the peer device, that is, from the network device 1.

Then, the second codeword determining means 203 in the network device 2 determines the current codeword level according to the received feedback message and/or the last used codeword, and determines a second in the codeword of the current codeword level. Codeword. In the case where there is no error in data reception, the second codeword determined by the network device 2 should be identical to the first codeword determined by the network device 1.

Then, the second transmitting device 204 performs data transmission using the second codeword. According to an embodiment of the present invention, in particular, a channel characteristic determining device (not shown) is further included in the first codeword determining device 102, and the channel characteristic determining device is configured to use the received first signal. Determine the first channel characteristics. The first codeword determining means 102 determines the current codeword level from the predetermined codebook based on the first channel characteristic determined by the channel characteristic determining means, and determines the first codeword from the codeword of the current codeword level. For example, when the first signal transmitted by the first transmitting device 201 in the network device 2 includes a pilot signal for channel estimation, the channel characteristic determining device in the network device 1 can determine the current according to the received pilot signal. The channel transmission matrix H, that is, the first channel characteristic. Then, the first codeword determining means in the network device 1 determines the optimal precoding matrix and the current codeword level according to the current channel transmission matrix H, and determines one from the codewords of the current codeword level according to the optimal precoding matrix. The first code word. Typically, the first codeword is the one of all codewords at the current codeword level that best matches the optimal precoding matrix. Preferably, the first codeword determining means 102 can determine which level of codeword to use based on how fast the channel characteristics change. For example, in this embodiment, there are 64 third-level codewords, and 6 bits are required to feed back a complete third-level codeword index; there are 4 first-level codewords, and a complete first-level codeword index is fed back. Only 2 bits are needed; therefore, when the feedback message is less than 6 bits and the channel characteristics change rapidly, the higher level codeword can be used to better track the change of channel characteristics. Specifically, the first codeword determining apparatus 102 may determine the channel characteristic change according to a correlation coefficient between the current channel transmission matrix H and a channel transmission matrix of a previous frame determined according to the received first frame of the previous frame. speed. For example, you can set a high limit and a low limit. If the correlation coefficient of the channel transmission matrix of two adjacent frames is greater than the high limit value, the channel change is considered to be slow, and the first codeword determining apparatus 102 determines the current codeword level as the third level; if the correlation coefficient is less than the low limit value If the channel change is faster, the first codeword determining device 102 determines the current codeword level as the first level; if the correlation coefficient is between the high limit value and the low limit value, the channel change speed is considered to be medium, A codeword determining means 102 determines the current codeword level as the second level. After determining the current codeword level, the first codeword determining means 102 can select a codeword that best matches the optimal precoding matrix from the class of codewords and determine it as the first codeword.

According to some embodiments of the present invention, in order to better match the use of multi-level codewords, There are two types of feedback messages: a first feedback message and a second feedback message, where the first feedback message is mainly used to control the change of the codeword level, and the second feedback message is mainly used to indicate the sub-group of a certain codeword. The index, the processing priority of the first feedback message is higher than the second feedback message. The codebook structure shown in FIG. 2 includes three levels of codewords in the codebook, and each codeword subgroup includes four codewords. Therefore, the first feedback message and the second feedback message only need to carry 2 bits. information. It should be understood by those skilled in the art that if other codebook structures are used, the number of information bits that each of the first feedback message and the second feedback message need to carry will also change accordingly. The MIMO system needs to set different bearer resources for the first feedback message and the second feedback message respectively. For example, different time slots/frequency in the same signal frame respectively carry the first feedback message and the second feedback message, or The same time slot/frequency in different signal frames respectively carries the first feedback message and the second feedback message. Preferably, if the frame structure specified by the IEEE 802.16 protocol family is adopted in the MIMO system, the first feedback message may be carried in the MAC PDU.

According to an embodiment of the present invention, when the network device 2 starts data communication with the network device 1, the first signal transmitted by the network device 2 will also carry corresponding information indicating that it will perform the first data transmission.

On the network device 1 side, the first codeword determining device 102 determines, according to the received first signal, that the network device 2 will perform the first data transmission, and determines a first codeword as the network according to the received first signal. The codeword used by device 2 for the first data transmission. Depending on the settings, the first codeword can be any level of codeword. Preferably, the first codeword can be selected from the lowest level of codewords.

The feedback message determining means 103 then determines to transmit an initial feedback message comprising the complete index information of the first codeword.

Next, the feedback message transmitting means 104 transmits the initial feedback message.

On the network device 2 side, the second receiving device 202 receives the feedback message from the network device 1. When the second codeword determining means 203 determines that the received feedback message is an initial feedback message, it selects a codeword from the predetermined codebook to determine the second codeword based on the received initial feedback message.

Then, the second transmitting device 204 performs data transmission using the second codeword. According to another embodiment of the present invention, in the network device 1, it is determined whether to transmit the first feedback message according to the ordinal number of the signal frame.

On the side of the network device 1, the first codeword determining means 102 will determine the first codeword. The feedback message determining means 103 judges whether or not the frame number of the received first signal satisfies a predetermined condition. If the frame number of the frame satisfies the predetermined condition, the feedback message determining means 103 determines that a first feedback message needs to be transmitted, the first feedback message including control information for indicating a change in the codeword level used by the network device 2. If the frame number does not satisfy the predetermined condition, the feedback message determining means 103 determines that a second feedback message needs to be transmitted, the second feedback message including index offset information. According to different settings, the index offset information may be used to indicate a relationship between the first codeword and a codeword used for data transmission of a previous frame, or to indicate the first codeword and the first one. The relationship between the code words indicated by the feedback message.

The feedback message transmitting means 104 then transmits the feedback message that needs to be sent. Preferably, the network device 1 periodically sends a first feedback message, that is, a first feedback message is sent every certain number of frames, and those frames between two adjacent frames that send the first feedback message are sent. Second feedback message.

On the side of the network device 1, the first codeword determining means 102 will determine the first codeword. When the feedback message determining means 103 determines that the current codeword level of the first codeword is the same as the level of the first predetermined number of recently used codewords, it determines that a first feedback message needs to be sent, the first feedback message includes The control information indicating that the network device 2 keeps the level of the code used is unchanged. For example, the first predetermined number may be taken as 1. If the current first codeword is a second-level codeword, and the codeword used for the previous frame data transmission is also the second-level codeword, the feedback message determining means 103 determines that it is needed. A first feedback message is sent, the first feedback message is used to indicate that the network device 2 keeps the used codeword level unchanged. Of course, the first predetermined number S can also be taken as other natural numbers than one. When the feedback message determining means 103 determines that the last first feedback message includes control information for instructing the network device 2 to keep the used codeword level unchanged, and the current codeword level of the first codeword and the previous first feedback If the codeword level indicated by the message is the same, it determines that a second feedback message needs to be sent, and the second feedback message includes index offset information. According to different settings, the index offset information may be used to indicate a relationship between the first codeword and a codeword used for data transmission of a previous frame, or to indicate the first codeword and the first one. The relationship between the code words indicated by the feedback message. For example, if the last first feedback message indicates that the network device 2 keeps the used codeword level unchanged, and the codewords used for data transmission of the current first codeword and the last few frames are both second-level codewords, the feedback message is determined. Apparatus 103 determines that a second feedback message including index offset information needs to be transmitted. When the feedback message determining means 103 determines that the last first feedback message includes control information for indicating that the network device 2 keeps the used codeword level unchanged, and the current codeword level of the first codeword is the same as the level of the last used codeword. Differently, it is determined that a first feedback message needs to be sent, the first feedback message including control information for instructing the network device 2 to change the level of the codeword used. For example, if the last first feedback message indicates that the network device 2 keeps the used codeword level unchanged, and the codeword used in the previous frame data transmission is the second level codeword, and the current first codeword is the third level. The codeword, the feedback message determining means 103 determines that a first feedback message needs to be transmitted, the first feedback message including control information for instructing the network device 2 to change the level of the codeword used.

The feedback message transmitting means 104 then transmits the feedback message that needs to be sent. On the network device 2 side, the second receiving device 202 receives the feedback message from the network device 1.

When the second codeword determining means 203 determines that the received feedback message includes a first feedback message, the first feedback message includes control information for indicating a change of the codeword level used by the network device 2 or for indicating the network device 2 The second codeword determining means 203 determines the current codeword level based on the level of the first feedback message and the last used codeword, while maintaining the control information of the used codeword level unchanged. When the second codeword determining means 203 determines that the received feedback message includes a second feedback message, the second feedback message includes index offset information, the second codeword determining means 203 is determined according to the second feedback message and the determined The current codeword level determines the second codeword.

Then, the second transmitting device 204 performs data transmission using the second code word.

According to another embodiment of the present invention, the first feedback message may be used to indicate a network setting Standby 2 keeps the codeword used unchanged.

On the side of the network device 1, the first codeword determining means 102 will determine the first codeword. When the feedback message determining means 103 determines that the correlation coefficient between the first codeword and the second predetermined number of recently used codewords is greater than a first threshold, it determines to send a first feedback message, the first feedback message including Control information for instructing the network device 2 to keep the codewords used unchanged. When the feedback message determining means 103 determines that the last first feedback message includes control information for indicating that the network device 2 keeps the used codeword unchanged, and the correlation coefficient between the first codeword and the last used codeword is greater than the first The threshold, then it is determined not to send a feedback message. When the feedback message determining means 103 determines that the last first feedback message includes control information for indicating that the peer device keeps the used codeword unchanged, and the correlation between the first codeword and the last used codeword The coefficient is less than the first threshold, and it is determined to send a first feedback message, the first feedback message including control information for instructing the network device 2 to change the used codeword. For example, the second predetermined number can be taken as 1. The codeword used by the network device 2 in the nth frame data transmission is Noo, and the first codeword of the n+1th frame determined by the first codeword determining means 102 in the network device 1 is N. Q,. If the correlation coefficient is greater than the first threshold, the feedback message determining means 103 determines that a first feedback message needs to be sent, the first feedback message is used to indicate that the network device 2 keeps the used codeword unchanged, that is, the network device 2 is The n+1 frame data transmission will still use the codeword Νοο,ο. From the n+2th frame until the n+mth frame (m > 2), the first codeword in the network device 1 determines the first codeword and N determined by the device 102. . If the correlation coefficient between _Q and _Q is greater than the first threshold, the feedback message determining means 103 determines that no feedback message is sent from the n+2th frame until the n+th frame, that is, the network device 2 is in the n+2th frame. The codeword Νοο,ο will still be used in the n+m frame data transmission. In the n+m+1 frame, the correlation coefficient between the first codeword determined by the first codeword determining means 102 in the network device 1 and Νοο, ο is less than the first threshold, and the feedback message determining means 103 determines to transmit A first feedback message is used to instruct the network device 2 to change the codeword used. Of course, the second predetermined number can also be taken as other natural numbers than one.

The feedback message transmitting means 104 then transmits the feedback message that needs to be sent. On the network device 2 side, the second receiving device 202 receives a feedback message from the network device 1. When the second codeword determining means 203 determines that the feedback message from the network device 1 is not received, and the previous feedback message includes a first feedback message for indicating that the network device 2 keeps the used codeword unchanged, the second The code word determining means 203 determines the last used code word as the second code word.

For example, the codeword used by the network device 2 for data transmission in the nth frame is N. D,. . If the feedback message for the n+1 frame received by the second receiving device 202 includes a first feedback message, where the first feedback message is used to indicate that the network device 2 keeps the codeword used, the second codeword The determining means 203 will be N. . _{Q is} determined to be the second codeword, that is, the network device 2 will still use N _QQ in the n+1th frame data transmission. This code word. Next, the second receiving device 202 does not receive the feedback message for the n+2th frame up to the n+mth frame (m > 2), and the second codeword determining means 203 still determines Νοο, ο as the second The codeword, that is, the network device 2 will still use N in the n+2th frame until the n+mth frame data transmission. . ,. This code word. The second transmitting means 204 uses the codeword N in the n+2th frame up to the n+mth frame. . , o for data transmission.

According to another embodiment of the present invention, the first signal transmitted by the network device 2 further includes an indication message for specifying a codeword level. Then, on the network device 1 side, the first codeword determining means 102 determines the current codeword level from the predetermined codebook according to the indication message in the received first signal, and selects from the codewords of the current codeword level. One is determined to be the first codeword. For example, the first signal transmitted by the network device 2 in a certain frame includes both a pilot signal for channel estimation and an indication message for indicating that the next codeword uses a second level codeword. Then, in the network device 1, after the first receiving device 101 receives the first signal, the first codeword determining device 102 estimates the channel transmission matrix H according to the received pilot signal, and according to the received indication message. Determining that the current codeword level is the second level, and then selecting a codeword that best matches the channel transmission matrix H from the second level codeword and determining it as the first codeword.

In still another embodiment of the present invention, a codebook employed in a MIMO system has a codebook structure as shown in FIG. The complete index of the third-level codeword has the following correspondence: The codeword N _xy , the complete index of _z is abcdef, where ab, cd, ef are two-digit binary numbers corresponding to x, y, z, respectively, for example, codewords Noo, _{3 has} a full index of 000011, codeword N ₃₃ , ₀ T/CN2009/000010 The full index is 111100, and so on. The higher the level having a shorter codeword complete index, the corresponding relationship between the correspondence relationship similar to, e.g., the complete index for codeword No 00, complete codeword index N ₃ is 11, the code word N _2, The complete index of ₃ is 1011, the complete index of codeword N _{1; 3} is 0111, and so on. In this embodiment, the feedback message sent by the network device 1 in a certain frame is used to indicate the codeword used by the network device 2 in the next frame.

In this embodiment, the second feedback message contains two bits of information for addressing in a subset of codewords. If the codeword of the current frame is not the lowest level codeword, then a current second feedback message is used to indicate that the codeword of the next frame will be addressed in the subset of codewords associated with the current codeword. If the codeword of the current frame is the lowest level codeword, then a current second feedback message is used to indicate that the codeword of the next frame will be addressed in the subset of codewords to which the current codeword belongs. For example, if the current frame of the codeword is N _{l 5 and the} current second feedback message is 10, the codeword of the next frame should be Ni, ₂ ; if the codeword of the current frame is N ₁₂ , ₃ , the current The second feedback message is 10, and the codeword of the next frame should be N ₁₂ , ₂ .

In this embodiment, the first feedback message includes two bits of information, and the content of the control instruction corresponding to each first feedback message is as follows:

00, returning to the initial state, the first feedback message indicating that the next second feedback message is used for addressing in the first level codeword;

01. Upscaling a level. If the codeword of the current frame is an i-th codeword, the first feedback message indicates that the next second feedback message is used for addressing in the i-th level codeword;

10, moving to the low level activation/invalidation, the first feedback message indicating whether the lower level movement is allowed;

1 1 , keep the current codeword active/invalid, if the current first feedback message is active to keep the current codeword, the codeword used by the current frame will be used from the next frame until the next first feedback message is received. .

According to an implementation manner of the embodiment, the first feedback message and the second feedback message are respectively carried in the same time slot/frequency in different frames, and the feedback message sent by the network device 1 in a certain frame is used to indicate that the network device 2 is under For the codeword used in one frame, the network device 1 feeds back the complete index of a third level codeword for the first frame data transmission of the network device 2, and then sends a first feedback message every 4 frames. If the first feedback signal is 00, the next frame will be fed back 9 000010 The full index of a third-level codeword. Figure 6 shows the correspondence between feedback messages and codeword changes over a period of time in this implementation. As shown in FIG. 6, a sequence labeled as III acts as a sequence number of each frame; a message labeled I acts as a feedback message sent by the network device 1 in each frame, wherein the tag 1 is a first feedback message; A codeword index used by the network device 2 in each frame.

According to another implementation of this embodiment, the first feedback message and the second feedback message may be carried in different time slots/frequencies in the same frame, respectively. Preferably, the first feedback message may be carried on the MAC PDU, and the second feedback message is carried on the control channel of the PHY. In this way, the transmission of the feedback message and the selection of the codeword are more flexible, so that the channel change can be better tracked. The feedback message sent by the network device 1 in a certain frame is used to indicate the codeword used by the network device 2 in the next frame, and the network device 1 feeds back an index of the first level codeword for the first frame data transmission of the network device 2, and the A feedback message can be sent at any time as needed. Figure 7 shows the correspondence between feedback messages and codeword changes over a period of time in this implementation. As shown in FIG. 7, the sequence labeled as ΠΙ is the sequence number of each frame; the two messages marked as I are sent by the network device 1 in each frame, wherein the line marked with 1 is the first feedback message, with the mark 2 Each row is a second feedback message; a code labeled Π acts as a codeword used by the network device 2 in each frame.

The non-limiting embodiments of the present invention have been described above, but the present invention is not limited to a specific system, device, or specific protocol, and various modifications and changes can be made by those skilled in the art within the scope of the appended claims. .

Claims

Claim

A method for feeding back channel information in a network device of a multiple input multiple output system, wherein the network device comprises a predetermined codebook, the codebook comprising a plurality of codeword levels, each codeword level comprising Multiple codewords are used for data transmission by the peer device, and any non-lowest level codeword has a plurality of lower level codewords composed of a subgroup associated with it, and any non-highest level codeword has one and only one Associated high-level codewords, the method includes the following steps:

Receiving a first signal from the peer device;

b. determining, according to the received first signal, a current codeword level from the predetermined codebook, and determining a first codeword from the codewords of the current codeword level; Determining a feedback message to be sent by a codeword and/or the received first signal;

d. Send the feedback message you want to send in step c.

2. The method according to claim 1, wherein the step c further comprises:

― If the peer device is to perform the first data transmission, it is determined that an initial codeword feedback message is sent, where the initial feedback message includes index information of the first codeword, and is used to indicate that the peer device uses Decoding the first codeword for data transmission;

The step d further includes:

- Send the initial codeword feedback message.

The method according to claim 1, wherein the step c further comprises:

- if the frame number of the received first signal satisfies a predetermined condition, determining to send a first feedback message, the first feedback message including control for indicating a change in a codeword level used by the peer device Information

The step d further includes:

- transmitting the first feedback message.

4. The method according to claim 3, wherein the step c is further included - if the frame number of the received first signal does not satisfy the predetermined condition, it is determined to send a second feedback message, the second feedback message includes index offset information, and the index offset information is used to indicate Determining a relationship between the first codeword and the last used codeword or the codeword indicated by the previous first feedback message;

The step d further includes:

- transmitting the second feedback message.

The method according to claim 1, wherein the step c further comprises:

Determining to send a first feedback message if the current codeword level of the first codeword is the same as the first predetermined number of recently used codewords, the first feedback message comprising means for indicating the peer The device maintains control information with the same codeword level used;

The step d further includes:

- transmitting the first feedback message.

The method according to claim 5, wherein the step c further comprises:

- if the last first feedback message includes control information indicating that the peer device keeps the used codeword level unchanged, and the current codeword level of the first codeword is indicated by the previous first feedback message If the codewords are of the same level, it is determined that a second feedback message is sent, where the second feedback message includes index offset information, where the index offset information is used to indicate the first codeword and the last used codeword or the first one. The relationship between the code words indicated by the feedback message;

The step d further includes:

- transmitting the second feedback message.

The method according to claim 5 or 6, wherein the step c further comprises:

- if the last first feedback message includes control information indicating that the peer device keeps the used codeword level unchanged, and the current codeword level of the first codeword is different from the level of the last used codeword, And determining to send a first feedback message, where the first feedback message includes control information for indicating that the peer device changes the used codeword level; The step d further includes:

- transmitting the first feedback message.

8. The method according to claim 1, wherein the step c further comprises:

- if the correlation coefficient between the first codeword and the second predetermined number of recently used codewords is greater than a first threshold, determining to send a first feedback message, the first feedback message including The control device that keeps the codeword used by the peer device is unchanged; the step d further includes:

- transmitting the first feedback message.

9. The method according to claim 8, wherein the step c further comprises:

- if the last first feedback message includes control information indicating that the peer device keeps the used codeword unchanged, and the correlation coefficient between the first codeword and the last used codeword is greater than the first The threshold determines that no feedback message is sent.

10. The method according to claim 8, wherein the step c further comprises:

- if the last first feedback message includes control information indicating that the peer device keeps the used codeword unchanged, and the correlation coefficient between the first codeword and the last used codeword is less than the first The threshold is determined to send a first feedback message, where the first feedback message includes control information for instructing the peer device to change the used codeword;

The step d further includes:

- transmitting the first feedback message including control information for instructing the peer device to change the codeword used.

1 1. The method according to any one of claims 1 to 10, wherein the step b comprises:

b. determining, according to the received first signal, a first channel characteristic;

B2. determining, according to the first channel characteristic, the current codeword level from the predetermined codebook, and determining the first codeword from codewords of the current codeword level.

12. The method according to claim 1, wherein the step B2 also includes:

Determining the current codeword level from the predetermined codebook based on the first channel characteristic and a correlation coefficient between channel characteristics determined by the last received first signal, and from the current code The first codeword is determined in a word-level codeword.

13. The method according to claim 1, wherein the received first signal comprises an indication message for specifying a codeword level;

The step b further includes:

Determining, according to the indication message, the current codeword level from the predetermined codebook, and determining the first codeword from a codeword of the current codeword level.

14. A method for transmitting data in a network device of a multiple input multiple output system, wherein the network device comprises a predetermined codebook, the codebook comprising a plurality of codeword levels, each codeword level comprising The codewords are used by the network device for data transmission, and any non-lowest level codeword has a plurality of lower level codewords composed of a subgroup associated with it, and any non-highest level codeword has one and only one Associated high-level codewords, the method includes the following steps:

A. sending the first signal;

B. receiving a feedback message from the peer device;

C. determining a current codeword level according to the received feedback message and/or the last used codeword, and determining a second codeword in the codeword of the current codeword level;

D. Data transmission is performed according to the second codeword.

The method according to claim 14, wherein the step C further comprises:

- if the feedback message is an initial feedback message, determining the second codeword from the codebook based on the initial feedback message.

The method according to claim 14, wherein the step C further comprises:

- if the feedback message comprises a first feedback message, the first feedback message comprising control information indicating a change in a codeword level used by the network device or for indicating that the network device keeps the used codeword level unchanged Control information, according to the first feedback The level of the message and the last used codeword determines the current codeword level.

The method according to claim 14 or 16, wherein the step C further comprises:

- if the feedback message comprises a second feedback message comprising index offset information, the second codeword is determined based on the second feedback message, the current codeword level.

The method according to claim 14, wherein the step C further comprises:

- if the feedback message from the peer device is not received in step B, and the previous feedback message includes a first feedback message indicating that the network device keeps the codeword used unchanged, then the last used code The word is determined to be the second codeword.

19. A feedback device for feeding back channel information in a network device of a multiple input multiple output system, wherein the network device comprises a predetermined codebook comprising a plurality of codeword levels, each codeword level Include a plurality of codewords for data transmission by the peer device, any non-lowest level codeword having a plurality of lower level codewords forming a subgroup associated therewith, and any one of the non-highest level codewords has one and only one The higher-level codeword associated with it, the feedback device includes:

a first receiving device, configured to receive a first signal from the peer device; a first codeword determining device, configured to determine a current code from the predetermined codebook according to the received first signal a word level, and determining a first codeword from the codeword of the current codeword level;

a feedback message determining means, configured to determine, according to the first codeword and/or the received first signal, a feedback message to be sent;

And a feedback message sending device, configured to send a feedback message determined by the feedback message determining device to be sent.

The feedback device according to claim 19, wherein the feedback message determining device is further configured to:

- if the peer device is to perform the first data transmission, determining to send an initial codeword feedback message, the initial feedback message including index information of the first codeword, Instructing the peer device to use the first codeword to perform data transmission; the feedback message sending apparatus is further configured to:

- Send the initial codeword feedback message.

And if the frame number of the received first signal satisfies a predetermined condition, determining to send a first feedback message, the first feedback message including control information indicating a change in a codeword level used by the peer device ;

The feedback message sending device is further configured to:

- transmitting the first feedback message.

The feedback device according to claim 21, wherein the feedback message determining device is further configured to:

And if it is determined that the frame number of the received first signal does not satisfy the predetermined condition, determining to send a second feedback message, where the second feedback message includes index offset information, where the index offset information is used to indicate the a relationship between the first codeword and the last used codeword or the codeword indicated by the previous first feedback message;

The feedback message sending device is further configured to:

- transmitting the second feedback message.

Determining to send a first feedback message if the current codeword level of the first codeword is the same as the first predetermined number of recently used codewords, the first feedback message comprising means for indicating the peer The device maintains control information with the same codeword level used; the feedback message sending device is further configured to:

- transmitting the first feedback message.

The feedback device according to claim 23, wherein the feedback message determining device is further configured to:

- if the last first feedback message includes control information for indicating that the peer device keeps the used codeword level unchanged, and the current codeword level of the first codeword is the same as the previous one And determining, by the first feedback message, that the codewords are of the same level, determining to send a second feedback message, where the second feedback message includes index offset information, where the index offset information is used to indicate the first codeword and the previous one. The relationship between the codeword used or the codeword indicated by the previous first feedback message;

The feedback message sending device is further configured to:

- transmitting the second feedback message.

The feedback device according to claim 23 or 24, wherein the feedback message determining device is further configured to:

- if the last first feedback message includes control information indicating that the peer device keeps the used codeword level unchanged, and the current codeword level of the first codeword is different from the level of the last used codeword, And determining to send a first feedback message, where the first feedback message includes control information for indicating that the peer device changes the used codeword level;

The feedback message sending device is further configured to:

- transmitting the first feedback message.

Determining to send a first feedback message if the correlation coefficient between the first codeword and the second predetermined number of recently used codewords is greater than a first threshold, the first feedback message comprising The peer device maintains control information that the codeword used is unchanged; the feedback message sending device is further configured to:

- transmitting the first feedback message.

The feedback device according to claim 26, wherein the feedback message determining device is further configured to:

- if the last first feedback message includes means for indicating that the peer device remains used The control information of the codeword is unchanged, and the correlation coefficient between the first codeword and the last used codeword is less than the first threshold, and then determining to send a first feedback message, where the first feedback message is used for Instructing the peer device to change control information of the used codeword;

The feedback message sending device is further configured to:

The feedback device according to any one of claims 19 to 28, wherein the first codeword determining device further comprises:

Channel characteristic determining means, configured to determine a first channel characteristic according to the received first signal;

The first codeword determining apparatus is further configured to determine the current codeword level from the predetermined codebook according to the first channel characteristic, and determine the first from a codeword of the current codeword level One code word.

The feedback device according to claim 29, wherein the first codeword determining device is further configured to:

The feedback device according to claim 19, wherein the received first signal comprises an indication message for specifying a codeword level;

The first codeword determining device is further configured to:

32. A data transmission apparatus for transmitting data in a network device of a multiple input multiple output system, wherein the network device includes a predetermined codebook including a plurality of inputs, any non-lowest level codewords Having a plurality of lower level codeword components associated with a subset, any non-highest level codeword having one and only one higher level codeword associated therewith, the data transmission device comprising: a first sending device, configured to send the first signal;

a second receiving device, configured to receive a feedback message from the peer device; a second codeword determining device, configured to determine a current codeword level according to the received feedback message and/or a used codeword, and Determining a second codeword in the codeword of the current codeword level;

And a second sending device, configured to perform data transmission according to the second codeword.

The data transmission device according to claim 32, wherein the second codeword determining device is further configured to:

- if the feedback message comprises a first feedback message, the first feedback message comprising control information indicating a change in a codeword level used by the network device or for indicating that the network device keeps the used codeword level unchanged Control information, then determining the current codeword level based on the level of the first feedback message and the last used codeword.

The data transmission device according to claim 32 or 34, wherein the second codeword determining device is further configured to:

- if the feedback message includes a second feedback message, the second feedback message includes index offset information, the second codeword is determined according to the second feedback message, the current codeword.

- if the second receiving device does not receive a feedback message from the peer device, and the previous feedback message includes a first feedback message indicating that the network device keeps the used codeword unchanged, then A used codeword is determined to be the second codeword.

A network device in a multiple input multiple output system, comprising the feedback device according to any one of claims 17 to 28 and/or the data transmission device according to any one of claims 29 to 32.