CN101588223A - Method, device and system for acquiring multiple-input multiple-output channel information - Google Patents

Abstract

The invention provides a method, device and system for acquiring MIMO channel information. The method mainly includes: receiving a detection sounding signal sent by a terminal, wherein the sounding signal includes correlation information of a downlink MIMO channel of the terminal; detecting the sounding signal, and acquiring correlation information of a downlink MIMO channel of the terminal contained therein information. Utilizing the present invention, the base station can obtain the overall correlation situation of the downlink MIMO channel of the user terminal by detecting the sounding signal sent by the user terminal, so that the base station can obtain relatively comprehensive MIMO channel information. Therefore, the base station can adaptively select a suitable MIMO technology for transmission in a timely manner according to the channel characteristics of the downlink MIMO channel.

Description

Method, device and system for acquiring multi-input and multi-output channel information

technical field

The present invention relates to the technical field of wireless communication, in particular to a method and device for acquiring MIMO (Multi-input Multi-output) channel information based on sounding (detection) signals.

Background technique

With the development of wireless communication, high-speed and high-quality communication has become the development trend of the current wireless communication system. Since the conventional single-antenna transceiver communication system can no longer meet the high-capacity and high-reliability requirements of the next-generation wireless communication system, the use of multi-antenna technology can double the communication system without increasing spectrum resources and transmission power. Capacity and reliability, so the MIMO communication system has attracted widespread attention in the industry.

OFDM (Orthogonal Frequency Division Multiplexing) technology has been widely used in wireless communication systems due to its effective anti-fading characteristics and high spectral efficiency. When OFDM technology and MIMO technology are combined, the two technologies complement each other and complement each other's advantages. It has been recognized by the industry as the key technology of the next generation B3G/4G wireless communication.

The MIMO communication system uses multiple antennas at both the transmitting and receiving ends, and the working modes of the MIMO communication system can be divided into two types: an open-loop mode and a closed-loop mode. The so-called open-loop mode means that the MIMO transmitter can adopt MIMO technology without knowing the MIMO channel information, while the closed-loop mode means that the MIMO transmitter needs to adaptively adjust the MIMO transmission signal according to the MIMO channel information. Since closed-loop MIMO can make full use of MIMO channel information, it can maximize the use of air space resources of MIMO systems and obtain better performance than open-loop methods.

Since the closed-loop method needs to know the user's downlink MIMO channel information in advance when transmitting, it is generally necessary for the receiving end to feed back the user's downlink MIMO channel information to the transmitting end, and feeding back MIMO channel information requires a large overhead of the system. In practical applications In , often only part of the MIMO channel information is fed back, and the part of the MIMO channel information mainly includes:

1) CQI (Channel Quality Indicator, channel quality indicator) value on the transmission subband;

2) RI (Rank Indication, rank information) of the MIMO channel;

3) MIMO precoding codebook index information;

4) MIMO antenna selection, etc.

In the TDD (Time Division Duplexing, Time Division Duplexing) system using MIMO technology, considering the reciprocity between the transmitting and receiving channels, the transmitter of the base station can estimate the user's uplink MIMO channel by detecting the sounding signal transmitted by the user, and according to The estimated result of the uplink MIMO channel is used to replace the estimated result of the user's downlink MIMO channel. Therefore, the user can realize the feedback of the downlink MIMO channel information by transmitting the sounding signal.

A feedback scheme of MIMO channel information based on the sounding signal in the prior art is:

In the frame structure of the Wimax (Worldwide Interoperability for Microwave Access, global interoperability technology based on microwave access) TDD system, several sounding signals are reserved in the uplink subframe for users to transmit sounding signals, and the number of sounding signals reserved Up to 8. Before the user transmits the sounding signal, he needs to obtain the sounding scheduling information of the base station for the user in advance. The sounding scheduling information mainly consists of the time domain position information of the sounding signal, the frequency domain position information or the shift information of the sounding sequence, and the sounding signal. transmit power, etc. At the base station, by detecting the sounding signal transmitted by the user, the uplink MIMO channel information of the user can be estimated, and the downlink MIMO channel information of the user can be obtained further.

In the process of realizing the present invention, the inventors have found that at least the following problems exist in the above-mentioned prior art:

In the above-mentioned Wimax TDD system, as shown in Figure 1, the closed-loop MIMO technology with 4 antennas is used on the base station side, and only one fixed antenna (antenna 1) is used on the terminal side to transmit sounding signals. By estimating the sounding signal transmitted by the terminal, the base station can obtain the MIMO channel information of the terminal's antenna 1, but the MIMO channel information of the terminal's antenna 2 is unknown, so it can only use the MIMO channel information of the antenna 1 for closed loop MIMO. Since the MIMO channel information obtained by the base station is incomplete, there is a great risk when the closed-loop MIMO is adopted on the base station side.

Contents of the invention

Embodiments of the present invention provide a method, device and system for acquiring MIMO channel information, so as to solve the problem in the prior art that the downlink MIMO channel information acquired by the base station is not comprehensive.

A method for acquiring MIMO channel information comprising:

receiving a sounding signal sent by the terminal, where the sounding signal includes correlation information of the downlink MIMO channel of the terminal;

The sounding signal is detected to obtain the correlation information of the downlink MIMO channel of the terminal contained therein.

A device for acquiring MIMO channel information, comprising:

The signal receiving module is configured to receive a detection sounding signal sent by the terminal, and the sounding signal includes correlation information of the downlink MIMO channel of the terminal;

The signal detection module is configured to detect the sounding signal received by the signal receiving module, and acquire the correlation information of the downlink MIMO channel of the terminal contained therein.

A terminal comprising:

The codebook acquisition module is configured to query the mapping relationship between the pre-configured rank information and the codebook of the sounding signal according to the rank information of the downlink MIMO channel to obtain the codebook of the sounding signal, the rank information representing the downlink MIMO channel of the terminal related information;

The sounding signal sending module is used to use the codebook of the sounding signal as a vector to obtain a sounding signal group obtained by multiplying the sounding signal to be fed back, and send the sounding signal group through a single antenna.

A multiple-input multiple-output MIMO channel information acquisition system, comprising:

The device for obtaining MIMO channel information and the terminal, the terminal sends to the device for obtaining MIMO channel information a sounding signal that includes the correlation information of the downlink MIMO channel of the terminal, and the MIMO channel information The obtaining means detects the sounding signal, and obtains the correlation information of the downlink MIMO channel of the terminal contained therein.

It can be seen from the above-mentioned technical solutions provided by the embodiments of the present invention that the implementation of the present invention can enable the base station to obtain the overall correlation of the downlink MIMO channels of the user terminal by detecting the sounding signal sent by the user terminal, so that the base station can obtain a more comprehensive MIMO channel information.

Description of drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the accompanying drawings that need to be used in the description of the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For Those of ordinary skill in the art can also obtain other drawings based on these drawings without any creative effort.

1 is a schematic diagram of a closed-loop MIMO network in the prior art in which a base station uses 4 antennas to receive sounding signals and a terminal uses 1 antenna to send sounding signals;

FIG. 2 is a processing flowchart of a method for MIMO feedback based on sounding provided in Embodiment 1 of the present invention;

FIG. 3 is a processing flowchart of a method for MIMO feedback based on sounding provided in Embodiment 2 of the present invention;

FIG. 4 is a schematic diagram of the SNR gain comparison between the newly constructed sounding signal group and the existing sounding signal in channel estimation provided by Embodiment 2 of the present invention;

FIG. 5 is a processing flowchart of a method for MIMO feedback based on sounding provided by Embodiment 3 of the present invention;

FIG. 6 is a specific implementation structural diagram of a device for acquiring MIMO channel information provided by an embodiment of the present invention;

FIG. 7 is a specific implementation structural diagram of a terminal provided by an embodiment of the present invention.

Detailed ways

In the embodiment of the present invention, the terminal sends a sounding signal including the correlation information of the downlink MIMO channel of the terminal to the base station, and the base station detects the sounding signal to obtain the correlation information of the downlink MIMO channel of the terminal contained therein.

In order to facilitate the understanding of the embodiments of the present invention, several specific embodiments will be taken as examples for further explanation below in conjunction with the accompanying drawings, and each embodiment does not constitute a limitation to the embodiments of the present invention.

Embodiment one

The processing flow of the method for MIMO feedback based on sounding provided in this embodiment is shown in FIG. 2 , including the following processing steps:

Step 21, the base station receives the detection sounding signal sent by the terminal, and the sounding signal includes the correlation information of the downlink MIMO channel of the terminal.

According to the rank information of the downlink MIMO channel, the terminal queries the mapping relationship between the pre-configured rank information and the codebook of the sounding signal to obtain the codebook of the sounding signal, and the rank information represents the correlation information of the downlink MIMO channel of the terminal.

The terminal uses the codebook of the sounding signal as a vector to obtain a sounding signal group obtained by multiplying the sounding signal to be fed back, and the terminal adds a cyclic prefix to the multiple sounding signals in the sounding signal group, and passes A single antenna transmits separately.

The base station respectively receives the multiple sounding signals included in the sounding signal group sent by the terminal through the multiple antennas.

Step 22, the base station detects the sounding signal, and obtains the correlation information of the downlink MIMO channel of the terminal contained therein.

The base station detects each sounding signal received by each antenna, and obtains a channel estimation value corresponding to each sounding signal;

Correlating and superimposing the channel estimation values corresponding to each sounding signal received by all antennas to obtain a superposition value, and obtaining a codebook of the corresponding sounding signal according to the superposition value;

Querying the mapping relationship between the pre-configured rank information and the codebook of the sounding signal according to the codebook of the sounding signal, and acquiring the rank information of the downlink MIMO channel of the terminal.

The rank information of the downlink MIMO channel of the above-mentioned terminal reflects the overall correlation of the downlink MIMO channel of the terminal, so that the base station side can obtain relatively comprehensive MIMO channel information, so that the base station can adaptively implement Select a suitable MIMO transmission technology in a closed-loop mode.

Embodiment two

The processing flow of the method for MIMO feedback based on sounding provided in this embodiment is shown in FIG. 3 , including the following processing steps:

Step 31: Use the rank information of the MIMO channel to represent the correlation information of the downlink MIMO channel of the terminal, and construct a mapping relationship between the rank information of the MIMO channel and the codebook of the sounding signal.

In this embodiment, the rank information of the MIMO channel is used to quantify and represent the correlation information of the downlink MIMO channel of the terminal. Exemplarily, taking the terminal using 4 receiving antennas as an example for illustration, the rank of the downlink MIMO channel of the terminal is at most 4, wherein a rank of 1 means that all 4 receiving antennas are correlated with each other; a rank of 2 means that only 2 The root receiving antennas are not correlated with each other; a rank of 3 means that only 3 receiving antennas are not correlated with each other; a rank of 4 means that 4 receiving antennas are not correlated with each other.

Exemplarily, the above-mentioned rank information 1, 2, 3, and 4 are quantized into 2-bit symbols: 00, 01, 10, and 11, and correspond to the codebooks of the sounding signal: (1, 1), (1, -1 ), (1, j) and (1, -j). The mapping relationship between the above-mentioned rank information of the MIMO channel and the codebook is shown in Table 1 below.

Table 1:

Rank of MIMO channel Rank quantization bits of MIMO channel Codebook C of the sounding signal 1 00 (1,1) 2 01 (1, -1) 3 10 (1,j) 4 11 (1,-j)

In practical applications, the correspondence between codebooks and ranks in Table 1 does not need to be strictly bound.

When the number of receiving antennas of the terminal is less than 4, the codebook of the sounding signal shown in Table 1 above is also used to represent the correlation information of the downlink MIMO channel of the terminal. When the number of receiving antennas of the terminal is greater than 4, 4 of them are selected, and the codebook of the sounding signal shown in Table 1 above is used to represent the correlation information of the downlink MIMO channels of the selected 4 antennas.

Step 32, the terminal adds the codebook of the sounding signal corresponding to the rank information of the downlink MIMO channel as a precoding codebook to the original sounding signal, obtains a newly constructed sounding signal group, and sends it to the base station.

The terminal can use the existing estimation method to obtain the rank information of the downlink MIMO channel, query the mapping table shown in the above Table 1 according to the rank information, and obtain the codebook of the corresponding sounding signal.

Assuming that the users in the Wimax TDD system share the sounding channel through frequency division multiplexing, the subcarrier groups B ₁ , B ₂ ... B _U used by each user are orthogonal to each other. Assuming that user u occupies subcarrier family B _u , and the sounding pilot used is P(k), k∈Bu _, then the original sounding signal of user u based on OFDM modulation is: s(n), n=0, 1, 2.....N-1, n is the total length of the sounding signal. in, $\mathrm{the\; s}\left(\mathrm{no}\right)=\frac{1}{f}\underset{k=0}{\overset{f-1}{\mathrm{\&Sigma;}}}P\left(k\right)\&Center\; Dot;{\mathrm{<figure-callout\; id="2"\; label="e\; j"\; filenames="A2009100874220033H1.png"\; state="\{\{state\}\}">e</figure-callout>}}^j,$ F is the number of points of IFFT (Inverse Fast Fourier Transform) during OFDM modulation, and n is the time-domain sampling point of the sounding signal. $j=\sqrt{-1}.$

Taking the codebook of the above-mentioned sounding signal as a precoding codebook in the form of a two-dimensional vector and multiplying it with the above-mentioned original sounding signal s(n), the newly constructed sounding signal group is obtained as follows: $\left[\begin{array}{c}{\mathrm{the\; <figure-callout\; id="1"\; label="s"\; filenames="A2009100874220033H1.png"\; state="\{\{state\}\}">s</figure-callout>}}_1^{\&prime;}\left(\mathrm{no}\right)\\ {\mathrm{the\; <figure-callout\; id="2"\; label="s"\; filenames="A2009100874220033H1.png"\; state="\{\{state\}\}">s</figure-callout>}}_2^{\&prime;}\left(\mathrm{no}\right)\end{array}\right]=C^T\&Center\; Dot;\mathrm{the\; s}\left(\mathrm{no}\right),$ n=0, 1, 2...N-1, where C ^T is the transpose of the codebook vector of the above-mentioned sounding signal.

The above-mentioned newly constructed sounding signal group includes two sounding signals, corresponding to one character in the codebook of the above-mentioned sounding signal, respectively. For example, they respectively correspond to 1 and -1 in the codebook (1, -1).

In addition, in order to overcome the inter-symbol interference caused by multipath fading, the general sounding signal needs to add a cyclic prefix before transmission, and the length of the cyclic prefix should be greater than the maximum channel multipath delay L.

In this embodiment, the terminal only uses a fixed single antenna to transmit the sounding signal (that is, does not use the antenna polling method to transmit the sounding signal). The terminal adds a cyclic prefix to the two sounding signals in the newly constructed sounding signal group, respectively, and sends them to the base station through a single antenna.

Step 33, each receiving antenna of the base station detects each received sounding signal, obtains the estimated information of the downlink channel of each sounding signal of each antenna, and synthesizes the information of the downlink channel of the sounding signal of each antenna to obtain the precoding of the terminal Codebook information and integrated downlink channel estimation information on each antenna.

At the base station, multiple antennas are used to receive the sounding signal sent by the terminal. Each receiving antenna of the base station needs to detect each sounding signal received. At the same time, the uplink channel information of each sounding signal of each antenna is obtained by estimating each sounding signal. Then, through the reciprocity between the uplink and downlink channels in the TDD system, the downlink channel information of the terminal is obtained.

The specific detection process of the information of the uplink channel of each sounding signal of the above antenna is as follows:

Assuming that the receiving antenna at the base station is identified as i, i=0, 1, .. N _r -1, where N _r is the total number of receiving antennas at the base station, the two sounding signals received by antenna i are:

${\mathrm{<span\; class="notranslate">\; the\; <figure-callout\; id="1"\; label="y"\; filenames="A2009100874220033H1.png"\; state="\{\{state\}\}">y</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}}{\overset{\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="1"\; label="h"\; filenames="A2009100874220033H1.png"\; state="\{\{state\}\}">h</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; the\; <figure-callout\; id="1"\; label="s"\; filenames="A2009100874220033H1.png"\; state="\{\{state\}\}">s</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span>$ ${\mathrm{<span\; class="notranslate">\; the\; <figure-callout\; id="2"\; label="y"\; filenames="A2009100874220033H1.png"\; state="\{\{state\}\}">y</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}}{\overset{\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="h"\; filenames="A2009100874220033H1.png"\; state="\{\{state\}\}">h</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; the\; <figure-callout\; id="2"\; label="s"\; filenames="A2009100874220033H1.png"\; state="\{\{state\}\}">s</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0,1,2</span>}<span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span>\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; .</span>$

Wherein h _{1, i} (p), h _{2, i} (p), p=0, 1, 2...L-1 is the time-domain impulse response of antenna i receiving the channel on 2 sounding signals.

Assuming that two sounding signals are adjacent, the channel responses in the adjacent sounding signals can be approximately equal, so h _{1, i} (p)≈h _{2, i} (p)=h _i (p). Assume that the cyclic prefix length of the sounding signal is greater than the maximum channel multipath delay L, so after removing the cyclic prefix from the above sounding signal y _{1, i} , y _{2, i} , perform FFT (Fast Fourier Transform) transformation get:

${\mathrm{<span\; class="notranslate">\; <figure-callout\; id="1"\; label="Y"\; filenames="A2009100874220033H1.png"\; state="\{\{state\}\}">Y</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}}{\overset{\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; e</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="j"\; filenames="A2009100874220033H1.png"\; state="\{\{state\}\}">j</figure-callout></span>}\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;kn</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>\underset{\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}}{\overset{\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="1"\; label="h"\; filenames="A2009100874220033H1.png"\; state="\{\{state\}\}">h</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; the\; <figure-callout\; id="1"\; label="s"\; filenames="A2009100874220033H1.png"\; state="\{\{state\}\}">s</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; CP</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span>$

${\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="Y"\; filenames="A2009100874220033H1.png"\; state="\{\{state\}\}">Y</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}}{\overset{\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; e</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="j"\; filenames="A2009100874220033H1.png"\; state="\{\{state\}\}">j</figure-callout></span>}\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;kn</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>\underset{\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}}{\overset{\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="h"\; filenames="A2009100874220033H1.png"\; state="\{\{state\}\}">h</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; the\; <figure-callout\; id="2"\; label="s"\; filenames="A2009100874220033H1.png"\; state="\{\{state\}\}">s</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; CP</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0,1,2</span>}<span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}$

Then, according to the above Y _{1, i} (k), Y _{2, i} (k), the estimated information of the uplink channel corresponding to the two sounding signals received by antenna i is calculated as:

H′ _{1, i} (k)=Y _{1, i} (k)/P(k), H′ _{2, i} (k)=Y _{2, i} (k)/P(k), _k∈Bu

Since the sounding signal received by the receiving antenna i has undergone the above multiplication operation with the precoding codebook, the above H' _{1, i} (k), H' _{2, i} (k) have the following relationship:

$\left[\begin{array}{c}{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="1"\; label="h"\; filenames="A2009100874220033H1.png"\; state="\{\{state\}\}">h</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span>\\ {\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="h"\; filenames="A2009100874220033H1.png"\; state="\{\{state\}\}">h</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span>\end{array}\right]<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; C</span>}}^{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; \&Element;</span>{\mathrm{<span\; class="notranslate">\; B</span>}}_{\mathrm{<span\; class="notranslate">\; u</span>}}$

in $h_i\left(k\right)=\underset{p=0}{\overset{L-1}{\mathrm{\&Sigma;}}}{h}_i\left(p\right)\&CenterDot;e^{-\mathrm{<figure-callout\; id="2"\; label="j"\; filenames="A2009100874220033H1.png"\; state="\{\{state\}\}">j</figure-callout>}2\mathrm{\&pi;kp}/f},k\&Element;B_u$ is the frequency domain response of the uplink channel on antenna i. Since the uplink and downlink channels in the TDD system are reciprocal, the estimation of the frequency domain response H _i (k) can obtain the downlink channel information between the base station antenna i and the fixed transmitting single antenna of the terminal.

To accurately estimate the above-mentioned frequency domain response H _i (k), it is also necessary to detect the above-mentioned precoding codebook according to the above-mentioned Y _1,i (k), Y _2,i (k), and then obtain Rank information of the downlink MIMO channel of the terminal. The process of jointly detecting the above precoding codebook information by each antenna is as follows:

The above-mentioned H′ _{1, i} (k), H′ _{2, i} (k), i=0, 1, 2...N _r -1 values of each antenna are conjugated and multiplied and then superimposed to obtain: $W=\frac{1}{N_r}\underset{i=0}{\overset{N_r-1}{\mathrm{\&Sigma;}}}\&Center\; Dot;\underset{k\&Element;{\mathrm{<figure-callout\; id="1"\; label="B\; u\; h"\; filenames="A2009100874220033H1.png"\; state="\{\{state\}\}">B</figure-callout>}}_u}{\mathrm{\&Sigma;}}{h}_{}^{}{}_{1,i}^{\&prime;}\left(k\right)\&Center\; Dot;\mathrm{conj}\left({\mathrm{<figure-callout\; id="2"\; label="h"\; filenames="A2009100874220033H1.png"\; state="\{\{state\}\}">h</figure-callout>}}_{2,i}^{\&prime;}\left(k\right)\right),$ Wherein, conj(H′ _{2, i} (k)) is H′ _{2, the conjugation of relevant elements of i} (k),

Compare the size of the real part Re(W) and the imaginary part Im(W) of the above-mentioned W, if Re(W)>Im(W), and Re(W)>0, then the above-mentioned precoding codebook is C=(1 , 1), the rank information of the downlink MIMO channel of the corresponding terminal is 1;

If Re(W)>Im(W), and Re(W)≤0, then the above precoding codebook is C=(1,-1), and the rank information of the downlink MIMO channel of the corresponding terminal is 2;

If Re(W)≤Im(W), and Im(W)>0, then the above precoding codebook is C=(1, j), and the rank information of the downlink MIMO channel of the corresponding terminal is 3;

If Re(W)≤Im(W) and Im(W)≤0, then the above precoding codebook is C=(1,-j), and the rank information of the downlink MIMO channel of the corresponding terminal is 4.

Finally, the above frequency domain response H _i (k) is calculated by detecting the above precoding codebook C obtained:

${\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; conj</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; C</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&Center\; Dot;</span>\left[\begin{array}{c}{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="1"\; label="h"\; filenames="A2009100874220033H1.png"\; state="\{\{state\}\}">h</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span>\\ {\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="h"\; filenames="A2009100874220033H1.png"\; state="\{\{state\}\}">h</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span>\end{array}\right]<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; conj</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; C</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; C</span>}}^{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; \&Element;</span>{\mathrm{<span\; class="notranslate">\; B</span>}}_{\mathrm{<span\; class="notranslate">\; u</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0,1,2</span>}<span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span>{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}$

where conj(C) is the conjugate of the relevant elements of precoding C, and C ^T is the transposition of the precoding codebook vector. Since the uplink and downlink channels in the TDD system are reciprocal, the downlink channel information between the base station antenna i and the fixed transmitting single antenna of the terminal can be obtained according to the above frequency domain response H _i (k).

In this embodiment, since the newly constructed sounding signal includes two sounding signals, the redundancy of the sounding signals can improve the channel estimation performance of the base station's sounding. For example, take the system simulation parameter table shown in Table 2 below as an example:

Table 2: System Simulation Parameter Table

system bandwidth 10M FFT points 1024 cyclic prefix 128 User multiplexing method Frequency extraction (frequency division multiplexing) frequency interval 8 channel type Multipath slow fading Number of base station antennas 2

A schematic diagram of the SNR gain comparison between the newly constructed sounding signal group and the existing sounding signal in channel estimation is shown in FIG. Compared with the sounding signal, it can bring about 3dB SNR gain.

In the prior art, a multi-antenna technology is adopted on the base station side, and multiple antennas can be used to transmit and receive signals at the same time, but only one fixed antenna is used to transmit sounding signals on the terminal side.

In addition, in many current wireless communication systems (such as LTE (Long Term Evolution) TDD systems), the number of receiving antennas of a terminal is often less than the number of transmitting antennas. Therefore, if the base station only relies on the transmitting antenna of the terminal, it is difficult to estimate the channel information of the receiving antenna of the terminal.

Therefore, in the prior art, the base station can only obtain the MIMO channel information of the antenna that transmits the sounding signal of the terminal, but is unaware of the MIMO channel information of other antennas of the terminal. Since the MIMO channel information obtained by the base station is incomplete, there is a great risk when the closed-loop MIMO is adopted on the base station side. Because for the MIMO system, when the spatial multiplexing technology is adopted, the channels affect each other rather than being independent of each other. Therefore, without knowing the correlation of all MIMO channels, blindly optimizing the receiving performance of some MIMO channels is often ineffective, and sometimes even counterproductive.

In this embodiment, the correlation information of the downlink MIMO channel of the terminal is included in the sounding signal sent by the terminal, and the base station detects the sounding signal to obtain the correlation information of the downlink MIMO channel of the terminal contained therein. Therefore, even if the terminal uses one fixed antenna to transmit sounding, the base station can know the overall correlation of the downlink MIMO channel. In this way, the channel correlation information can be used as a reference index for the MIMO of the base station, which facilitates switching between various MIMO transmission schemes of the base station.

On the other hand, when the base station estimates the sounding signal, the detection performance of the sounding signal is also crucial. For users at the edge of the cell, since users cannot transmit using multi-antenna technology, it is necessary to increase the sounding transmission power to improve the detection performance of the base station for the sounding signal, which also increases the power consumption of the terminal equipment. In this embodiment, by including multiple sounding signals in the constructed sounding signal group, the redundancy of the sounding signals is increased, thereby improving the sounding channel estimation performance of the base station.

Embodiment Three

In this embodiment, the sounding channel is shared among users through code division multiplexing. The processing flow of the method for MIMO feedback based on sounding provided in this embodiment is shown in FIG. 5 , including the following processing steps:

Step 51: Use the rank information of the MIMO channel to represent the correlation information of the downlink MIMO channel of the terminal, and construct a mapping relationship between the rank information of the MIMO channel and the codebook of the sounding signal.

In this embodiment, the rank information of the MIMO channel is used to quantify and represent the correlation information of the downlink MIMO channel of the terminal. Exemplarily, taking the terminal using 4 receiving antennas as an example for illustration, the rank of the downlink MIMO channel of the terminal is at most 4, wherein a rank of 1 means that all 4 receiving antennas are correlated with each other; a rank of 2 means that only 2 The root receiving antennas are not correlated with each other; a rank of 3 means that only 3 receiving antennas are not correlated with each other; a rank of 4 means that 4 receiving antennas are not correlated with each other.

Exemplarily, the above-mentioned rank information 1, 2, 3, and 4 are quantized into 2-bit symbols: 00, 01, 10, and 11, and correspond to the codebooks of the sounding signal: (1, 1), (1, -1 ), (1, j) and (1, -j). The mapping relationship between the above-mentioned rank information of the MIMO channel and the codebook is shown in Table 3 below.

table 3:

I. Rank of MIMO channel I. Rank quantization bits of MIMO channel Codebook C of I.sounding signal 1 II.00 II.(1,1) 2 III.01 III.(1,-1) 3 IV.10 IV.(1,j) 4 V.11 V.(1,-j)

In practical applications, the correspondence between codebooks and ranks in Table 1 does not need to be strictly bound.

When the number of receiving antennas of the terminal is less than 4, the codebook of the sounding signal shown in Table 1 above is also used to represent the correlation information of the downlink MIMO channel of the terminal. When the number of receiving antennas of the terminal is greater than 4, 4 of them are selected, and the codebook of the sounding signal shown in Table 1 above is used to represent the correlation information of the downlink MIMO channels of the selected 4 antennas.

Step 52: The code division multiplexing terminal adds the codebook of the sounding signal corresponding to the rank information of the downlink MIMO channel as a precoding codebook to the original sounding signal, obtains a newly constructed sounding signal group, and sends it to the base station.

The terminal can use the existing estimation method to obtain the rank information of the downlink MIMO channel, query the mapping table shown in the above Table 1 according to the rank information, and obtain the codebook of the corresponding sounding signal.

Assuming that the users in the Wimax TDD system share the sounding channel through frequency division multiplexing, the subcarrier families B ₁ , B ₂ . . . _BU used by each user are orthogonal to each other. Assuming that user u occupies subcarrier family B _u , and the sounding pilot used is P(k), k∈Bu _, then the original sounding signal of user u based on OFDM modulation is: s(n), n=0, 1, 2.....N-1, n is the total length of the sounding signal. in, $\mathrm{the\; s}\left(\mathrm{no}\right)=\frac{1}{f}\underset{k=0}{\overset{f-1}{\mathrm{\&Sigma;}}}P\left(k\right)\&Center\; Dot;{\mathrm{<figure-callout\; id="2"\; label="e\; j"\; filenames="A2009100874220033H1.png"\; state="\{\{state\}\}">e</figure-callout>}}^j,$ F is the number of points of IFFT (Inverse Fast Fourier Transform) during OFDM modulation, and n is the time-domain sampling point of the sounding signal. $j=\sqrt{-1}.$

Taking the codebook of the above-mentioned sounding signal as a precoding codebook in the form of a two-dimensional vector and multiplying it with the above-mentioned original sounding signal s(n), the newly constructed sounding signal group is obtained as follows:

$\left[\begin{array}{c}{\mathrm{the\; <figure-callout\; id="1"\; label="s"\; filenames="A2009100874220033H1.png"\; state="\{\{state\}\}">s</figure-callout>}}_1^{\&prime;}\left(\mathrm{no}\right)\\ {\mathrm{the\; <figure-callout\; id="2"\; label="s"\; filenames="A2009100874220033H1.png"\; state="\{\{state\}\}">s</figure-callout>}}_2^{\&prime;}\left(\mathrm{no}\right)\end{array}\right]=C^T\&Center\; Dot;\mathrm{the\; s}\left(\mathrm{no}\right),\mathrm{no}=\mathrm{0,1,2}...N-1,$ Where C ^T is the transpose of the codebook vector of the above sounding signal.

The above-mentioned newly constructed sounding signal group includes two sounding signals, corresponding to one character in the codebook of the above-mentioned sounding signal, respectively. For example, they respectively correspond to 1 and -1 in the codebook (1, -1).

In addition, in order to overcome the inter-symbol interference caused by multipath fading, the general sounding signal needs to add a cyclic prefix before transmission, and the length of the cyclic prefix should be greater than the maximum channel multipath delay L.

In this embodiment, the terminal only uses a fixed single antenna to transmit the sounding signal (that is, does not use the antenna polling method to transmit the sounding signal). The terminal adds a cyclic prefix to the two sounding signals in the newly constructed sounding signal group, respectively, and sends them to the base station through a single antenna.

Step 53, each receiving antenna of the base station detects each received sounding signal using the traditional time-domain channel estimation method, obtains the estimated information of the downlink channel of each sounding signal of each antenna, and synthesizes the downlink channel of the sounding signal of each antenna The channel information acquires the precoding codebook information of the terminal and the integrated downlink channel estimation information on each antenna.

After the antenna i at the base station receives the sounding signal group sent by the above code division multiplexed terminal, it uses the traditional time-domain channel estimation method to detect the sounding signal group, and the time-domain channel estimation of antenna i is obtained as: h _{1, i} (n), h _{2, i} (n), n=0, 1, ... F-1, i = 0, 1, 2 ... N _r -1, where F is the number of system FFT transformation points, N _r is the total number of receiving antennas of the base station. Then, according to the cyclic shift u of the user codeword, the downlink channel information corresponding to the two sounding signals received by the antenna i is extracted in the time domain: h _{1, i} (n), h _{2, i} (n ),, n∈A _u , where A _u is the channel extraction position corresponding to the cyclic shift u.

Since the sounding signal received by each receiving antenna of the base station has been multiplied by the precoding codebook above, to accurately estimate the frequency domain response h _i (n) of the uplink channel on each receiving antenna, it must also be based on the above Y _1,i (k) and Y _2,i (k) detect the above-mentioned precoding codebook. The process of jointly detecting the above precoding codebook by each antenna is as follows:

When the time-domain detection method is used, the frequency-domain responses of the uplink channels of each antenna h _{1, i} (n), h _{2, i} (n), n∈A _u , i=0, 1, 2.... N _r -1 values are conjugated and multiplied and then superimposed to obtain: $W^{\&prime;}=\frac{1}{N_r}\underset{i=0}{\overset{N_r-1}{\mathrm{\&Sigma;}}}\&CenterDot;\underset{\mathrm{no}\&Element;A_{\mathrm{<figure-callout\; id="1"\; label="u\; h"\; filenames="A2009100874220033H1.png"\; state="\{\{state\}\}">u</figure-callout>}}}{\mathrm{\&Sigma;}}{h}_{}{}_{1,i}\left(\mathrm{no}\right)\&CenterDot;\mathrm{conj}\left({\mathrm{<figure-callout\; id="2"\; label="h"\; filenames="A2009100874220033H1.png"\; state="\{\{state\}\}">h</figure-callout>}}_{2,i}\left(\mathrm{no}\right)\right),$ Wherein, conj(h _{2, i} (n)) is the conjugate of the relevant element of h _{2, i} (n).

When the frequency domain detection method is used, the frequency domain responses of the uplink channels of each antenna h _{1, i} (n), h _{2, i} (n), , n∈A _u , i=0, 1, 2... N _r -1 is first filled with zeros in the time domain, and transformed to the frequency domain by the FFT transformation of point F: ${\mathrm{<figure-callout\; id="1"\; label="h"\; filenames="A2009100874220033H1.png"\; state="\{\{state\}\}">h</figure-callout>}}_{1,i}\left(k\right)=\underset{\mathrm{no}=0}{\overset{f-1}{\mathrm{\&Sigma;}}}{\mathrm{<figure-callout\; id="1"\; label="h"\; filenames="A2009100874220033H1.png"\; state="\{\{state\}\}">h</figure-callout>}}_{1,i}\left(\mathrm{no}\right)\&CenterDot;{\mathrm{<figure-callout\; id="2"\; label="e\; j"\; filenames="A2009100874220033H1.png"\; state="\{\{state\}\}">e</figure-callout>}}^j,$ ${\mathrm{<figure-callout\; id="1"\; label="h"\; filenames="A2009100874220033H1.png"\; state="\{\{state\}\}">h</figure-callout>}}_{1,i}\left(k\right)=\underset{\mathrm{no}=0}{\overset{f-1}{\mathrm{\&Sigma;}}}{\mathrm{<figure-callout\; id="1"\; label="h"\; filenames="A2009100874220033H1.png"\; state="\{\{state\}\}">h</figure-callout>}}_{1,i}\left(\mathrm{no}\right)\&CenterDot;{\mathrm{<figure-callout\; id="2"\; label="e\; j"\; filenames="A2009100874220033H1.png"\; state="\{\{state\}\}">e</figure-callout>}}^j,$ , k=0, 1, 2...F-1, i=0, 1, 2... _Nr -1. Superimpose the above H _{1, i} (k), H _{2, i} (k) of each antenna to get: $W=\frac{1}{N_r}\underset{i=0}{\overset{N_r-1}{\mathrm{\&Sigma;}}}\&Center\; Dot;\underset{k=\mathrm{0,1,2}..f-1_{\mathrm{<figure-callout\; id="1"\; label="u\; h"\; filenames="A2009100874220033H1.png"\; state="\{\{state\}\}">u</figure-callout>}}}{\mathrm{\&Sigma;}}{h}_{}{}_{1,i}\left(k\right)\&Center\; Dot;\mathrm{conj}\left({\mathrm{<figure-callout\; id="2"\; label="h"\; filenames="A2009100874220033H1.png"\; state="\{\{state\}\}">h</figure-callout>}}_{2,i}\left(k\right)\right).$

Compare the size of the real part Re(W) and the imaginary part Im(W) of W obtained by the above-mentioned time domain detection method or frequency domain detection method, if Re(W)>Im(W), and Re(W)>0, Then the above precoding codebook is C=(1,1), and the rank information of the downlink MIMO channel of the corresponding terminal is 1;

If Re(W)>Im(W), and Re(W)≤0, then the above precoding codebook is C=(1,-1), and the rank information of the downlink MIMO channel of the corresponding terminal is 2;

If Re(W)≤Im(W), and Im(W)>0, then the above precoding codebook is C=(1, j), and the rank information of the downlink MIMO channel of the corresponding terminal is 3;

If Re(W)≤Im(W) and Im(W)≤0, then the above precoding codebook is C=(1,-j), and the rank information of the downlink MIMO channel of the corresponding terminal is 4.

When the time-domain detection method is used, the time-domain impulse response h _i (n) of the downlink channel estimated by the sounding signal on the receiving antenna i is calculated by detecting the above-mentioned precoding codebook C:

${\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; conj</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; C</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&CenterDot;</span>\left[\begin{array}{c}{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="1"\; label="h"\; filenames="A2009100874220033H1.png"\; state="\{\{state\}\}">h</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span>\\ {\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="h"\; filenames="A2009100874220033H1.png"\; state="\{\{state\}\}">h</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span>\end{array}\right]<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; \&CenterDot;</span>\mathrm{<span\; class="notranslate">\; conj</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; C</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; C</span>}}^{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; \&Element;</span>{\mathrm{<span\; class="notranslate">\; A</span>}}_{\mathrm{<span\; class="notranslate">\; u</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0,1,2</span>}<span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span>{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}$

Where conj(C) is the conjugation of relevant elements of the precodebook C, and C ^T is the transpose of the precodebook vector.

When the frequency domain detection method is used, the frequency domain response H _i (k) of the uplink channel estimated by the sounding signal on the receiving antenna i is calculated by detecting the above-mentioned precoding codebook C:

${\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; \&CenterDot;</span>\mathrm{<span\; class="notranslate">\; conj</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; C</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&CenterDot;</span>\left[\begin{array}{c}{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="1"\; label="h"\; filenames="A2009100874220033H1.png"\; state="\{\{state\}\}">h</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span>\\ {\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="h"\; filenames="A2009100874220033H1.png"\; state="\{\{state\}\}">h</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span>\end{array}\right]<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; conj</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; C</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; C</span>}}^{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0,1,2</span>}<span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0,1,2</span>}<span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span>{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}$

Where conj(C) is the conjugation of relevant elements of the precodebook C, and C ^T is the transpose of the precodebook vector. Since the uplink and downlink channels in the TDD system are reciprocal, according to the time domain impulse response h _i (n) and the frequency domain response H _i (k), the downlink channel between the base station antenna i and the fixed transmitting single antenna of the terminal can be obtained information.

In the prior art, a multi-antenna technology is adopted on the base station side, and multiple antennas can be used to transmit and receive signals at the same time, but only one fixed antenna is used to transmit sounding signals on the terminal side. The base station can only obtain the MIMO channel information of the antenna that transmits the sounding signal of the terminal, but is unaware of the MIMO channel information of other antennas of the terminal. Since the MIMO channel information obtained by the base station is incomplete, there is a great risk when the closed-loop MIMO is adopted on the base station side.

In this embodiment, the correlation information of the downlink MIMO channel of the terminal is included in the sounding signal sent by the terminal, and the base station detects the sounding signal to obtain the correlation information of the downlink MIMO channel of the terminal contained therein. Therefore, even if the terminal uses one fixed antenna to transmit sounding, the base station can know the overall correlation of the downlink MIMO channel. The detection of the sounding signal group sent by the code division multiplexed terminal is realized, and the overall correlation of the downlink MIMO channel of the terminal and the estimated uplink channel information on each receiving antenna are obtained. The base station can adaptively select a suitable MIMO transmission technology in a closed-loop mode according to the channel characteristics of the downlink MIMO channel in time.

Embodiment four

The sounding-based MIMO feedback method described in the above embodiments can be used in combination with the existing terminal MIMO feedback scheme.

The base station can simultaneously schedule some users in the sounding area of the same frame to use the sounding-based MIMO feedback method proposed by the embodiment of the present invention, while scheduling other users to still use the existing MIMO feedback scheme. The sounding scheduling information of the base station to the terminal is indicated through the UL_sounding_Command_IE message. In this embodiment, the above-mentioned sounding scheduling information is used to instruct the terminal to send the sounding signal containing the correlation information of the downlink MIMO channel of the terminal. For example, UL_sounding_Command_IE can be used The reserved field in the message is used to distinguish which MIMO feedback scheme the terminal needs to adopt.

In the above UL_sounding_Command_IE message, the description of the Include additional feedback field is shown in Table 3 below:

Table 3: Additional Feedback Field Descriptions

Include additional feedback describe 0b00   No additional feedback 0b01 Channel coefficient feedback 0b10 Pilot coefficient feedback 0b11 News Feedback

When the Include additional feedback field is set to 0b01, it indicates that the terminal is allowed to use additional feedback, for example, additional feedback of downlink channel coefficients or downlink reception pilots. When Includeadditional feedback=0b01, the description of the additional feedback using channel coefficients is shown in Table 4 below:

Table 4: Description of additional feedback using channel coefficients

Exemplarily, this embodiment uses the 2-bit reserved field in the above Table 4 to indicate whether to use the sounding-based MIMO feedback method proposed by the embodiment of the present invention. When the base station needs to instruct the terminal to adopt the sounding-based MIMO feedback method proposed by the embodiment of the present invention, when the base station sets the UL_sounding_Command_IE message, in addition to setting the basic configuration parameters of sounding transmission like the existing MIMO feedback scheme, it also needs to set the The include additional feedback field is set to 0b01, indicating that the user needs to adopt an additional feedback method, but when describing the includeadditional feedback field in detail, set the 1-bit reserved field to 1, indicating that the base station scheduling is proposed by the embodiment of the present invention For the sounding-based MIMO feedback method, if the original MIMO feedback scheme is still used, the reserved bit is set to 0.

This embodiment implements the mixed use of the sounding-based MIMO feedback method described in the above embodiments and the existing terminal MIMO feedback solution.

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

Embodiment Four

The embodiment of the present invention also provides a device for acquiring MIMO channel information, and its specific implementation structure is shown in Figure 6, specifically including:

The signal receiving module 61 is configured to receive a detection sounding signal sent by the terminal, where the sounding signal includes correlation information of the downlink MIMO channel of the terminal;

The signal detection module 62 is configured to detect the sounding signal received by the signal receiving module 41, and obtain the correlation information of the downlink MIMO channel of the terminal contained therein.

The device may also include:

The mapping relationship module 63 is configured to configure the mapping relationship between the rank information of the downlink MIMO channel of the terminal and the codebook of the sounding signal, the rank information represents the correlation information of the downlink MIMO channel of the terminal, and the code of the sounding signal This is used as a vector to multiply the sounding signal including rank information that needs to be fed back by the terminal to obtain the sounding signal group;

Exemplarily, taking the terminal using 4 receiving antennas as an example for illustration, the rank of the downlink MIMO channel of the terminal is at most 4, wherein a rank of 1 means that all 4 receiving antennas are correlated with each other; a rank of 2 means that only 2 The root receiving antennas are not correlated with each other; a rank of 3 means that only 3 receiving antennas are not correlated with each other; a rank of 4 means that 4 receiving antennas are not correlated with each other.

Exemplarily, the above-mentioned rank information 1, 2, 3, and 4 are quantized into 2-bit symbols: 00, 01, 10, and 11, and correspond to the codebooks of the sounding signal: (1, 1), (1, -1 ), (1, j) and (1, -j). The mapping relationship between the above-mentioned rank information of the MIMO channel and the codebook is shown in Table 4 below.

Table 4:

I. Rank of MIMO channel I. Rank quantization bits of MIMO channel Codebook C of I.sounding signal 1 II.00 II.(1,1) 2 III.01 III.(1,-1) 3 IV.10 IV.(1,j) 4 V.11 V.(1,-j)

In practical applications, the correspondence between codebooks and ranks in Table 4 does not need to be strictly bound.

When the number of receiving antennas of the terminal is less than 4, the codebook of the sounding signal shown in Table 1 above is also used to represent the correlation information of the downlink MIMO channel of the terminal. When the number of receiving antennas of the terminal is greater than 4, 4 of them are selected, and the codebook of the sounding signal shown in Table 1 above is used to represent the correlation information of the downlink MIMO channels of the selected 4 antennas.

The signal receiving module 61 receives the sounding signal group sent by the terminal. The generation process of the sounding signal group is as follows: the rank information of the MIMO channel is used to represent the correlation information of the downlink MIMO channel of the terminal, and the mapping relationship between the rank information of the MIMO channel and the codebook of the sounding signal is constructed. The terminal uses the codebook of the sounding signal corresponding to the rank information of the downlink MIMO channel as a precoding codebook, and adds it to the original sounding signal to obtain a newly constructed sounding signal group and send it to the base station.

The device may also include:

The indication information sending module 64 is configured to send sounding scheduling information including indication information to the terminal, where the indication information is used to instruct the terminal to send a sounding signal including correlation information of downlink MIMO channels of the terminal. The base station can simultaneously schedule some users to use the sounding-based MIMO feedback method proposed by the embodiment of the present invention in the sounding area of the same frame, while scheduling other users to still use the existing MIMO feedback scheme. The sounding scheduling information of the base station to the terminal can be indicated through the UL_sounding_Command_IE message, and the above-mentioned sounding scheduling information instructs the terminal to send the sounding signal containing the correlation information of the downlink MIMO channel of the terminal. For example, the reserved field in the UL_sounding_Command_IE message can be used to Distinguish which MIMO feedback scheme the terminal needs to adopt.

The signal detection module 62 specifically includes:

The codebook acquisition module 622 is configured to detect each sounding signal received by each antenna, and obtain a channel estimate corresponding to each sounding signal; perform correlation superposition on the channel estimate corresponding to each sounding signal received by all antennas The superposition value is obtained, and the codebook of the corresponding sounding signal is obtained according to the superposition value.

At the base station, multiple antennas are used to receive the sounding signal sent by the terminal. Each receiving antenna of the base station needs to detect each sounding signal received. At the same time, the uplink channel information of each sounding signal of each antenna is obtained by estimating each sounding signal. Then, through the reciprocity between the uplink and downlink channels in the TDD system, the downlink channel information of the terminal is obtained.

The specific detection process of the information of the uplink channel of each sounding signal of the above antenna is as follows:

Assuming that the receiving antenna at the base station is identified as i, i=0, 1, .. N _r -1, where N _r is the total number of receiving antennas at the base station, the two sounding signals received by antenna i are:

${\mathrm{<span\; class="notranslate">\; the\; <figure-callout\; id="1"\; label="y"\; filenames="A2009100874220033H1.png"\; state="\{\{state\}\}">y</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}}{\overset{\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="1"\; label="h"\; filenames="A2009100874220033H1.png"\; state="\{\{state\}\}">h</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; the\; <figure-callout\; id="1"\; label="s"\; filenames="A2009100874220033H1.png"\; state="\{\{state\}\}">s</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; the\; <figure-callout\; id="2"\; label="y"\; filenames="A2009100874220033H1.png"\; state="\{\{state\}\}">y</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}}{\overset{\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="h"\; filenames="A2009100874220033H1.png"\; state="\{\{state\}\}">h</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; the\; <figure-callout\; id="2"\; label="s"\; filenames="A2009100874220033H1.png"\; state="\{\{state\}\}">s</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0,1,2</span>}<span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span>\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; .</span>$

Wherein h _{1, i} (p), h _{2, i} (p), p=0, 1, 2...L-1 is the time-domain impulse response of antenna i receiving the channel on 2 sounding signals.

Assuming that two sounding signals are adjacent, the channel responses in the adjacent sounding signals can be approximately equal, so h _{1, i} (p)≈h _{2, i} (p)=h _i (p). Assume that the cyclic prefix length of the sounding signal is greater than the maximum channel multipath delay L, so after removing the cyclic prefix from the above sounding signal y _{1, i} , y _{2, i} , perform FFT (Fast Fourier Transform) transformation get:

${\mathrm{<span\; class="notranslate">\; <figure-callout\; id="1"\; label="Y"\; filenames="A2009100874220033H1.png"\; state="\{\{state\}\}">Y</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}}{\overset{\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; e</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="j"\; filenames="A2009100874220033H1.png"\; state="\{\{state\}\}">j</figure-callout></span>}\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;kn</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>\underset{\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}}{\overset{\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="1"\; label="h"\; filenames="A2009100874220033H1.png"\; state="\{\{state\}\}">h</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; the\; <figure-callout\; id="1"\; label="s"\; filenames="A2009100874220033H1.png"\; state="\{\{state\}\}">s</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; CP</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span>$

${\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="Y"\; filenames="A2009100874220033H1.png"\; state="\{\{state\}\}">Y</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}}{\overset{\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; e</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="j"\; filenames="A2009100874220033H1.png"\; state="\{\{state\}\}">j</figure-callout></span>}\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;kn</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>\underset{\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}}{\overset{\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="h"\; filenames="A2009100874220033H1.png"\; state="\{\{state\}\}">h</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; the\; <figure-callout\; id="2"\; label="s"\; filenames="A2009100874220033H1.png"\; state="\{\{state\}\}">s</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; CP</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0,1,2</span>}<span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}$

Then, according to the above Y _{1, i} (k), Y _{2, i} (k), the estimated information of the uplink channel corresponding to the two sounding signals received by antenna i is calculated as:

H′ _{1, i} (k)=Y _{1, i} (k)/P(k), H′ _{2, i} (k)=Y _{2, i} (k)/P(k), _k∈Bu

Since the sounding signal received by the receiving antenna i has undergone the above multiplication operation with the precoding codebook, the above H' _{1, i} (k), H' _{2, i} (k) have the following relationship:

$\left[\begin{array}{c}{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="1"\; label="h"\; filenames="A2009100874220033H1.png"\; state="\{\{state\}\}">h</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span>\\ {\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="h"\; filenames="A2009100874220033H1.png"\; state="\{\{state\}\}">h</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span>\end{array}\right]<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; C</span>}}^{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; \&Element;</span>{\mathrm{<span\; class="notranslate">\; B</span>}}_{\mathrm{<span\; class="notranslate">\; u</span>}}$

in $h_i\left(k\right)=\underset{p=0}{\overset{L-1}{\mathrm{\&Sigma;}}}{h}_i\left(p\right)\&CenterDot;e^{-\mathrm{<figure-callout\; id="2"\; label="j"\; filenames="A2009100874220033H1.png"\; state="\{\{state\}\}">j</figure-callout>}2\mathrm{\&pi;kp}/f},k\&Element;B_u$ is the frequency domain response of the uplink channel on antenna i. Since the uplink and downlink channels in the TDD system are reciprocal, the estimation of the frequency domain response H _i (k) can obtain the downlink channel information between the base station antenna i and the fixed transmitting single antenna of the terminal.

To accurately estimate the above-mentioned frequency domain response H _i (k), it is also necessary to detect the above-mentioned precoding codebook according to the above-mentioned Y _1,i (k), Y _2,i (k), and then obtain Rank information of the downlink MIMO channel of the terminal. The process of jointly detecting the above precoding codebook information by each antenna is as follows:

The above-mentioned H′ _{1, i} (k), H′ _{2, i} (k), i=0, 1, 2...N _r -1 values of each antenna are conjugated and multiplied and then superimposed to obtain: $W=\frac{1}{N_r}\underset{i=0}{\overset{N_r-1}{\mathrm{\&Sigma;}}}\&Center\; Dot;\underset{k\&Element;{\mathrm{<figure-callout\; id="1"\; label="B\; u\; h"\; filenames="A2009100874220033H1.png"\; state="\{\{state\}\}">B</figure-callout>}}_u}{\mathrm{\&Sigma;}}{h}_{}^{}{}_{1,i}^{\&prime;}\left(k\right)\&Center\; Dot;\mathrm{conj}\left({\mathrm{<figure-callout\; id="2"\; label="h"\; filenames="A2009100874220033H1.png"\; state="\{\{state\}\}">h</figure-callout>}}_{2,i}^{\&prime;}\left(k\right)\right),$ Wherein, conj(H′ _{2, i} (k)) is H′ _{2, the conjugation of relevant elements of i} (k),

Compare the size of the real part Re(W) and the imaginary part Im(W) of the above-mentioned W, if Re(W)>Im(W), and Re(W)>0, then the above-mentioned precoding codebook is C=(1 ,1);

If Re(W)>Im(W), and Re(W)≤0, then the above precoding codebook is C=(1,-1);

If Re(W)≤Im(W), and Im(W)>0, then the above precoding codebook is C=(1, j);

If Re(W)≤Im(W) and Im(W)≤0, then the above precoding codebook is C=(1, -j).

The rank information acquisition module 621 is configured to, according to the codebook of the sounding signal acquired by the codebook acquisition module, query the mapping relationship between the rank information configured in the mapping relationship module and the codebook of the sounding signal, and acquire the Rank information of the downlink MIMO channel.

For example, when the above precoding codebook is C=(1, -1), the rank information of the downlink MIMO channel of the corresponding terminal is 2; when the above precoding codebook is C=(1, -1), the corresponding terminal The rank information of the downlink MIMO channel is 2; when the above-mentioned precoding codebook is C=(1, j), the rank information of the downlink MIMO channel of the corresponding terminal is 3; when the above-mentioned precoding codebook is C=(1, -j), the rank information of the downlink MIMO channel of the corresponding terminal is 4.

The channel estimation information acquisition module 623 is configured to acquire the final channel estimation information on each antenna according to the codebook of the sounding signal acquired by the codebook acquisition module 422 of the sounding signal and the channel estimation information corresponding to each sounding signal received by each antenna. channel estimation information.

For example, by detecting the above precoding codebook C obtained above, the above frequency domain response H _i (k) is calculated:

${\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; \&CenterDot;</span>\mathrm{<span\; class="notranslate">\; conj</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; C</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&Center\; Dot;</span>\left[\begin{array}{c}{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="1"\; label="h"\; filenames="A2009100874220033H1.png"\; state="\{\{state\}\}">h</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span>\\ {\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="h"\; filenames="A2009100874220033H1.png"\; state="\{\{state\}\}">h</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span>\end{array}\right]<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; conj</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; C</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; C</span>}}^{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; \&Element;</span>{\mathrm{<span\; class="notranslate">\; B</span>}}_{\mathrm{<span\; class="notranslate">\; u</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0,1,2</span>}<span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span>{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}$

where conj(C) is the conjugate of the relevant elements of precoding C, and C ^T is the transposition of the precoding codebook vector. Since the uplink and downlink channels in the TDD system are reciprocal, the downlink channel information between the base station antenna i and the fixed transmitting single antenna of the terminal can be obtained according to the above frequency domain response H _i (k).

The above-mentioned means for acquiring MIMO channel information may be a base station.

The embodiment of the present invention also provides a terminal, the specific implementation structure of which is shown in Figure 7, specifically including:

The codebook acquisition module 71 is configured to query the mapping relationship between the pre-configured rank information and the codebook of the sounding signal according to the rank information of the downlink MIMO channel to obtain the codebook of the sounding signal, the rank information representing the downlink MIMO of the terminal Correlation information for the channel.

The sounding signal sending module 72 is configured to use the codebook of the sounding signal as a vector to obtain a sounding signal group obtained by multiplying the sounding signal to be fed back, and send the sounding signal group through a single antenna.

The embodiment of the present invention also provides a MIMO channel information acquisition system, which specifically includes the MIMO channel information acquisition device shown in FIG. 6 and the terminal shown in FIG. 7 . The terminal sends a detection sounding signal including the correlation information of the downlink MIMO channel of the terminal to the MIMO channel information obtaining device, and the MIMO channel information obtaining device detects the sounding signal, and obtains the terminal contained therein The correlation information of the downlink MIMO channel.

In summary, the implementation of the present invention enables the base station to obtain the overall correlation of downlink MIMO channels of the user terminal by detecting the sounding signal sent by the user terminal, so that the base station can obtain relatively comprehensive MIMO channel information. Therefore, the base station can adaptively select the appropriate MIMO technology for transmission according to the channel characteristics of the downlink MIMO channel in a timely manner, and truly and effectively improve the receiving performance of users at the edge of the cell (where the channel environment is complex and changeable).

The embodiment of the present invention also improves the channel estimation performance of the sounding signal at the base station through the redundancy of the sounding signal, which can improve the estimation performance by 3dB at most, and can significantly improve the closed-loop MIMO feedback performance of the Wimax TDD system.

The embodiments of the present invention can be applied to user terminals located at the cell edge, and can effectively improve the detection performance of the base station for the sounding signal of the cell edge user without increasing the sounding transmission power of the cell edge user.

The embodiment of the present invention is fully compatible with the existing Wimax standard protocol, and is an enhanced technology based on the existing Wimax standard protocol, so it can be mixed and used together with the existing terminal MIMO feedback scheme. It can be realized as long as it depends on the scheduling of the base station side, and does not need to make any modification to the existing Wimax standard protocol, which has strong realizability and low technical complexity.

The above is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed in the present invention can easily think of changes or Replacement should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be determined by the protection scope of the claims.

Claims (13)

1, a kind of acquisition methods of multiple-input and multiple-output mimo channel information is characterized in that, comprising:

The detection sounding signal that receiving terminal sends comprises the correlation information of the descending mimo channel of described terminal in the described sounding signal;

Described sounding signal is detected, obtain the correlation information of the descending mimo channel of the described terminal that described sounding signal comprises.

2, method according to claim 1 is characterized in that, before the detection sounding signal that described receiving terminal sends, also comprises:

Described terminal is according to the order information of descending mimo channel, and the mapping relations between the code book of inquiry order information and sounding signal are obtained the code book of described sounding signal, the correlation information of the descending mimo channel of the described terminal of described order information representation;

The sounding sets of signals that obtains behind the sounding signal multiplication of code book as vector and needs feedback of described terminal with described sounding signal is by the described souding sets of signals of the antenna transmission of described terminal.

3, method according to claim 2 is characterized in that, described described sounding signal is detected, and obtains the correlation information of the descending mimo channel of the described terminal that described sounding signal comprises, and specifically comprises:

Receive the sounding signal that comprises in the described sounding sets of signals respectively by a plurality of antennas, each sounding signal that each antenna is received detects, and obtains each sounding signal corresponding channel estimation value;

Each sounding signal corresponding channel estimation value that all antennas are received stack of being correlated with obtains superposition value, obtains the code book of corresponding sounding signal according to described superposition value;

According to the mapping relations between the code book of pre-configured order information of the code book of described sounding signal inquiry and sounding signal, obtain the order information of the descending mimo channel of described terminal.

4, method according to claim 3 is characterized in that, described method also comprises:

The channel estimating information of each the sounding signal correspondence that receives according to the code book of described sounding signal and each antenna is obtained the comprehensive channel estimating information on each antenna of base station.

5, method according to claim 3 is characterized in that, described each sounding signal that each antenna is received detects, and obtains each sounding signal corresponding channel estimation value, comprising:

After each sounding signal that each antenna is received removes Cyclic Prefix, carry out fast fourier transform again;

If described terminal adopts the mode of frequency division multiplexing to send described souding sets of signals, the subcarrier family shared according to described terminal extracts each sounding signal corresponding channel estimation value that each antenna receives the sounding signal after described fast fourier transform;

Perhaps, if described terminal adopts the mode of code division multiplexing to send described souding sets of signals, cyclic shift amount according to the code word of described terminal extracts each sounding signal corresponding channel estimation value that each antenna receives the sounding signal after described fast fourier transform.

6, method according to claim 1 and 2 is characterized in that, described method also comprises:

Send the sounding schedule information that comprises indication information to described terminal, described indication information is used for the sounding signal that indicating terminal sends the correlation information of the descending mimo channel that comprises terminal.

7, a kind of deriving means of multiple-input and multiple-output mimo channel information is characterized in that, comprising:

Signal receiving module is used for the detection sounding signal that receiving terminal sends, and has comprised the correlation information of the descending mimo channel of terminal in the described sounding signal;

Signal detection module is used for the received described sounding signal of described signal receiving module is detected, and obtains the correlation information of the descending mimo channel of the terminal that wherein comprises.

8, the deriving means of multiple-input and multiple-output mimo channel information according to claim 7 is characterized in that, described device also comprises:

The indication information sending module is used for sending the sounding schedule information that comprises indication information to terminal, and described indication information is used for the sounding signal that indicating terminal sends the correlation information of the descending mimo channel that comprises terminal.

9, according to the deriving means of claim 7 or 8 described multiple-input and multiple-output mimo channel information, it is characterized in that described device also comprises:

The mapping relations module, be used for the mapping relations between the code book of the order information of descending mimo channel of configurating terminal and sounding signal, described order information representation the correlation information of descending mimo channel of terminal, behind the sounding signal multiplication that comprises order information that the code book of described sounding signal is used for need feeding back as vector and terminal, obtain the sounding sets of signals;

Described signal receiving module, the described sounding sets of signals that receiving terminal sends.

10, the deriving means of multiple-input and multiple-output mimo channel information according to claim 9 is characterized in that, described signal detection module specifically comprises:

The code book acquisition module, each the sounding signal that is used for each antenna is received detects, and obtains each sounding signal corresponding channel estimation value; Each sounding signal corresponding channel estimation value that all antennas are received stack of being correlated with obtains superposition value, obtains the code book of corresponding sounding signal according to described superposition value;

Order information acquisition module, the code book that is used for the sounding signal that obtained according to described code book acquisition module, mapping relations between the order information that disposes in the query mappings relationship module and the code book of sounding signal are obtained the order information of the descending mimo channel of described terminal.

11, the deriving means of multiple-input and multiple-output mimo channel information according to claim 10 is characterized in that, described signal detection module also comprises:

Channel estimating information acquisition module, be used for the code book of the sounding signal that obtained according to described code book acquisition module and the channel estimating information of each sounding signal correspondence that each antenna receives, obtain the comprehensive channel estimating information on each antenna of base station.

12, a kind of terminal is characterized in that, comprising:

The code book acquisition module, be used for order information according to descending mimo channel, inquire about the code book that mapping relations between the code book of pre-configured order information and sounding signal are obtained the sounding signal, described order information representation the correlation information of descending mimo channel of terminal;

The sounding signal transmitting module, the sounding sets of signals that obtains behind the sounding signal multiplication that is used for the code book of described sounding signal is fed back as vector and needs sends described sounding sets of signals by single antenna.

13, a kind of system that obtains of multiple-input and multiple-output mimo channel information is characterized in that, comprising:

Deriving means and terminal as claimed in claim 12 as each described mimo channel information of claim 7 to 11, described terminal sends the detection sounding signal of the correlation information of the descending mimo channel that has comprised terminal to the deriving means of described mimo channel information, the deriving means of described mimo channel information detects described sounding signal, obtains the correlation information of the descending mimo channel of the terminal that wherein comprises.

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