WO2008122229A1

WO2008122229A1 - Method, communication device for obtaining channel information

Info

Publication number: WO2008122229A1
Application number: PCT/CN2008/070583
Authority: WO
Inventors: Yuanjie Li; Yi Wang
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2007-04-10
Filing date: 2008-03-25
Publication date: 2008-10-16
Also published as: CN101286754A; CN101286754B

Abstract

A method and communication device for obtaining channel information. The method includes: the second communication device receives mixed pilot frequency transmitted from the first communication device and generated by superimposing the down-link pilot frequency and the up-link pilot frequency; estimating the up-link channel and obtaining the up-link channel parameter based on the received mixed pilot frequency and the known up-link pilot frequency (504); estimating the closed loop channel and obtaining the closed loop channel parameter based on the known down-link pilot frequency and the received mixed pilot frequency, and obtaining the down-link channel parameter based on the closed loop channel parameter and the up-link channel parameter; or resuming the obtain of the mixed pilot frequency transmitted from the first communication device based on the up-link channel parameter (505), and obtaining the down-link channel parameter based on the resuming obtained mixed pilot frequency transmitted from the first communication device, the known up-link pilot frequency, and the down down-link pilot frequency (506).

Description

Method for acquiring channel information, communication device

The present application claims priority to Chinese Patent Application No. 200710095851.9, entitled "Method of Obtaining Channel Information, Communication Device", filed on April 10, 2007, the entire contents of which is incorporated herein by reference. in.

Technical field

The present invention relates to the field of communications, and in particular, to a method and a communication device for acquiring channel information.

Background technique

In a wireless communication system, a signal is fading or distorted by a transmission channel during transmission. To recover a signal of a transmission source, the receiving end usually needs to estimate a transmission physical channel, and eliminate the channel pair by an equalization method. The effect of the transmitted signal. 1 is a schematic diagram of a typical wireless communication structure. As shown, the transmission source 101 encodes a signal using an encoder 102, the modulator 103 modulates the encoded signal, and transmits the modulated signal to the channel 104. In the transmission process of the channel 104, the signal is added to the noise by the interference of the noise source 105, and the signal reaches the receiving end through the channel, and the receiving end uses the channel estimation pre-equalization 106 to estimate the equalization of the channel 104, and restores the transmitting end. The transmitted signal; then, the recovered signal is demodulated via the demodulator 107, and the demodulated signal is decoded by the decoder 108 to read the signal.

However, due to additive noise at the receiving end, the effect of equalization is often affected by additive noise. For example: Zero Forcing (ZF) equalizer can cause noise amplification at lower signal-to-noise ratios; Although the Minimum Mean Square Error (MMSE) equalizer can effectively suppress the influence of noise, it needs to perform complex variance estimation on the noise at the receiving end. Other algorithms, such as: Maximum Likelihood Detection Algorithms, etc., also because the amount of calculation is too large, it is not suitable for actual system use.

To this end, the prior art proposes an effective solution: pre-processing the signal at the transmitting end, such as pre-equalization processing in a Single-Input Single-Output (SISO) system, and multiple transmissions. Multiple Input Multiple Output (MIMO) system Precoding processing is required.

The technical solution for pre-processing the signal according to the characteristics of the transmission channel at the transmitting end is a closed-loop precoding technology in the MIMO system, and the application of the technology can improve the performance of the system.

However, one of the main technical requirements for implementing pre-equalization on the downlink in the SISO system, or implementing pre-coding and other pre-processing in the MIMO system is: The transmitter needs a known downlink channel.

In order to enable the transmitting end to know the parameters of the downlink channel, a technical solution is provided in the current 802.20 standard, in particular, the terminal estimates the forward link according to the forward common pilot, and calculates the optimal for the terminal. The precoding matrix, and then the index number of the precoding matrix, the rank of the channel, and the channel quality indicator (CQI) of the downlink are fed back to the base station in the form of signaling, and the base station can according to the feedback information. The transmitted data is precoded.

The inventors of the present invention found that the solution provided by the prior art has at least the following drawbacks in carrying out the process of the present invention:

1. The processing load of the terminal is increased: the terminal needs to make a judgment based on the estimated downlink channel to determine the codebook to be used, and the calculation amount is large.

2. The correctness of the downlink information parameters fed back from the terminal to the transmitting end cannot be guaranteed in the transmission process to the transmitting end: Due to the influence of channel fading, the parameter may be distorted during the channel transmission, and the transmitting end cannot obtain the correct downlink. Link parameters.

In addition, in order to be able to learn the parameters of the downlink channel, the pre-equalization or pre-coding processing is performed by using the downlink channel history, and another widely used technical solution exists in the prior art: The channel feedback strategy is specifically:

After receiving the downlink pilot signal, the terminal estimates the downlink channel, acquires parameters of the downlink channel, and then encodes the estimated parameters of the downlink channel, and then forms an orthogonal frequency division multiplexing together with the uplink pilot (Orthogonal The frequency division multiplexing (OFDM) symbol is sent to the base station, where the encoded downlink channel information occupies the odd subcarrier of the OFDM symbol, and the uplink pilot occupies the even subcarrier of the OFDM symbol, and after receiving the signal, the base station first Uplink of even subcarriers The uplink channel estimation is performed frequently, and the downlink channel history transmitted by the terminal is recovered by using the estimation result of the uplink channel.

In the process of the present invention, the inventor of the present invention finds that the technical solution of the direct channel feedback strategy still has at least the following defects: After the downlink channel information is encoded, the odd subcarriers are used to feed back to the base station, occupying certain channel resources; At the same time, the downlink channel history may still be distorted during the channel transmission process, so that the transmitting end cannot obtain the parameters of the correct downlink channel.

Summary of the invention

The embodiment of the invention provides a method for acquiring channel information, which is used to estimate the parameters of the downlink channel and reduce the feedback overhead while estimating the uplink channel.

The embodiment of the invention further provides a communication device, which reduces feedback overhead, so that the communication device of the opposite end acquires the history of the downlink channel while estimating the uplink channel.

The embodiment of the invention further provides a communication device, which acquires parameters of the downlink channel while estimating the uplink channel.

A method for acquiring channel information provided by an embodiment of the present invention includes:

The second communications device receives the mixed pilot that is generated by the first communications device and is generated by the uplink pilot and the uplink pilot superposition;

Estimating the uplink channel according to the received mixed pilot and the known uplink pilot, acquiring an uplink channel

And obtaining downlink channel parameters according to the mixed pilot and the uplink channel parameters.

A communication device provided by an embodiment of the present invention includes:

a receiving unit, configured to receive a downlink pilot that is sent by the second communications device;

a pilot coding unit, configured to superimpose the received downlink pilot and the uplink pilot to form a mixed pilot, and a sending unit, configured to send the mixed pilot to the second communications device.

a receiving unit, configured to receive a mixed pilot sent by the first communications device, where the mixed pilot is: And a superposition of the uplink pilot and the uplink pilot that are sent by the first communications device, and an uplink channel estimating unit, configured to: according to the mixed pilot, and the known uplink pilot, to the uplink channel Estimate to obtain an upstream channel history;

And a downlink channel estimation unit, configured to acquire a downlink channel history according to the mixed pilot and the uplink channel parameter.

In the technical solution of the embodiment of the present invention, the second communications device receives, by the first communications device, the hybrid pilot generated by the uplink pilot and the uplink pilot, according to the mixed pilot, and the known uplink pilot. The downlink pilot estimates acquire the parameters of the uplink channel and the downlink channel, so that the uplink channel is estimated while the history of the downlink channel is acquired.

In the technical solution of the embodiment of the present invention, the first communications device, by transmitting the hybrid pilot to the second communications device, enables the second communications device to obtain the downlink channel parameter while estimating the acquired uplink channel parameter, instead of After receiving the downlink pilot, the second communication device performs corresponding estimation on the downlink pilot and corresponding precoding, and returns the result of the estimation process to the second communication device, so that the second communication device obtains. The parameters of the downlink channel. It can be seen that the technical solution of the embodiment of the present invention reduces signaling overhead and saves transmission resources compared with the prior art; and compared with the prior art, since the downlink channel parameters are not directly transmitted, the parameter is effectively avoided due to the fading of the transmission channel. The resulting distortion causes the second communication device to fail to get the correct downlink channel history.

The technical solution of the embodiment of the present invention is also advantageous for placing relatively complex downlink channel estimation, precoding, and the like on the second communication device side, and the effect is better when the processing capability of the first communication device is relatively weak. .

DRAWINGS

The drawings described herein are provided to provide a further understanding of the invention, and are not a limitation of the invention. In the drawing:

1 is a schematic diagram of typical wireless communication transmission and reception in the prior art;

2 is a schematic diagram of an application for acquiring channel information in a SISO system according to Embodiment 1 of the present invention; Schematic diagram of the process;

3 is a schematic flowchart of a method for acquiring channel information in a MIMO system according to Embodiment 2 of the present invention;

4 is a schematic flowchart of another method for acquiring channel information in a SISO system according to Embodiment 3 of the present invention;

FIG. 5 is a schematic flowchart of another method for acquiring channel information in a MIMO system according to Embodiment 4 of the present invention;

6 is a schematic structural diagram of a communication device according to Embodiment 5 of the present invention;

FIG. 7 is a schematic structural diagram of another communication device according to Embodiment 5 of the present invention;

8 is a schematic structural diagram of a communication device provided in Embodiment 6 of the present invention;

9 is a schematic structural diagram of a communication device provided in Embodiment 7 of the present invention;

FIG. 10 is a schematic structural diagram of a communication device according to Embodiment 8 of the present invention.

detailed description

The invention will be described in detail below with reference to the drawings in conjunction with the embodiments. The illustrative embodiments of the invention and the description thereof are intended to be illustrative of the invention, and are not intended to limit the invention.

Embodiment 1 : This embodiment takes a method for acquiring channel information provided by an embodiment of the present invention in an SISO system as an example, and the method is specifically described. FIG. 2 is a schematic flowchart of the method according to the embodiment, as shown in FIG. 2 . As shown, the method mainly includes:

Step 201: The second communications device sends a downlink pilot to the first communications device.

The second communication device performs OFDM modulation on the downlink pilot and the downlink data, and adds a cyclic prefix (CP) to transmit from the transmitting antenna to the downlink channel. Specifically, after the transmission data is coded and modulated, the downlink pilot is inserted into the equally spaced subcarriers in the frequency domain, and after being modulated by OFDM, the CP is transmitted from the transmitting antenna.

In order to prevent the downlink pilot in the hybrid pilot in this embodiment from affecting the estimation of the uplink channel and the closed loop channel by the second communication device, the first communication device and the second communication device may be preset. The uplink pilot and the downlink pilot respectively make the uplink pilot and the downlink pilot meet the following conditions:

(1) For the downlink pilot, the convolution result of the downlink pilot in the time domain can be an impulse function in the range of the delay spread length of the uplink channel _3⁄4// the delay spread length of the downlink channel/^ That is, the autocorrelation function of the downlink pilot in the time domain can be expressed as a form shown in the functional formula (1), so that the first communication device directly receives the received downlink pilot after receiving the downlink pilot. The uplink pilots are superimposed.

Where w denotes the conjugate of the uplink pilot ^θ; denotes the delay spread length of the downlink channel; 3⁄4 _/ denotes the delay spread length of the uplink channel; /^ +/ ^ denotes the delay spread length of the closed loop channel; a is greater than A real number of zero, without loss of generality, can be equal to 1.

(2) For the uplink pilot, its convolution result in the time domain is an impulse function in the delay spread length _μ/ range of the uplink channel, that is, the autocorrelation function of the uplink pilot in the time domain can be expressed as:

( ²⁾ , where , ;^) denotes the conjugate of the uplink pilot ^0); "is a real number greater than zero, without loss of generality, can be made equal to 1.

(3) For the uplink pilot and downlink pilot, both of which result of the convolution of the length of the delay spread in the length of delay spread _{¾ /} downlink channels and uplink channel / ^ and within the range of zero. which is:

The second communication device sends the downlink pilot that meets the limits of the functional formulas (1) and (3) to the first communications device, so that the second communications device directly receives the received downlink pilot after receiving the downlink pilot. Superimposed with the uplink pilot.

Step 202: The first communications device receives the downlink pilot, and receives the received downlink pilot and uplink pilot. The superimposed generation of the mixed pilot transmits the superimposed mixed pilot to the second communication device.

After receiving the signal sent by the second communication device, the first communication device extracts the signal on the corresponding pilot channel after demodulating the received signal through the de-CP and OFDM, and extracts the extracted downlink pilot and the signal. The uplink pilot transmitted to the second communication device is superimposed on the frequency domain to generate a mixed pilot. The hybrid pilot is: a superposition of a downlink pilot transmitted by the second communication device to the first communication device and an uplink pilot transmitted by the first communication device to the second communication device. That is, in the OFDM system, the hybrid pilot is represented by: including, in one subcarrier of one OFDM symbol, a downlink pilot that is sent by the second communications device to the first communications device via its downlink channel, and the first communications device The uplink pilot to be sent to the second communication device.

The uplink pilot transmitted by the first communication device to the second communication device satisfies the restriction condition indicated by the pre-set function formulas (2) and (3) in step 201.

After the first communication device generates the hybrid pilot, when the uplink data is sent to the second communication device, the superimposed mixed pilot is OFDM-modulated together with the uplink data, and after the CP is added, the uplink transmission is performed, and the uplink transmission is performed. Two communication devices.

The first communications device, when transmitting the hybrid pilot to the second communications device, can simply equalize the power allocated to the uplink pilot and the downlink pilot in the hybrid pilot.

However, in an actual system, if the downlink pilot is directly superimposed with the uplink pilot in the case where the transmission power of the first communication device is limited, the transmission power of the first communication device needs to be greatly improved, even It may be larger than the upper limit of the transmission power of the first communication device, which is disadvantageous for implementation. In addition, the downlink pilot will bring convolution noise in the process of returning to the second communication device, and since the noise also passes through the uplink channel, it is difficult to be eliminated in the channel estimation process. Therefore, in the embodiment of the present invention, most of the power can be allocated to the uplink pilot, and a small portion of the power is allocated to the downlink pilot, which can not only ensure the pilot (mixed pilot) transmission of the first communication device. The power does not exceed the predetermined upper emission limit, and the convolution noise can be suppressed to a large extent, thereby improving the accuracy of the uplink communication channel estimation by the second communication device at the opposite end.

In this embodiment, when the first communication device transmits the mixed pilot, the downlink pilot and the uplink pilot transmit power are The allocation provides two alternative technical solutions:

Option 1: Total power constant scheme

In the present scheme, the total transmit power of the pilot subcarrier of the first communication device (the sum of the uplink pilot transmit power allocated to the subcarrier and the transmit power of the downlink pilot) is fixed, and may be The total transmit power constant value informs the second communication device.

Then, the power allocation factor is defined, where the power allocation factor is assumed to be: the ratio of the power allocated to the downlink pilot to the total power of the hybrid pilot, and the mixed pilot signal transmitted on the uplink pilot channel is:

Wherein ^/ represents the downlink pilot received by the first communication device, indicating the uplink pilot transmitted by the first communication device.

In this solution, the first communication device may dynamically calculate the power allocation factor according to an actual situation, and transmit the power allocation factor to the second communication device when transmitting the mixed pilot, so that the second communication is performed. The device is informed of the power allocation of the received mixed pilot.

It should be noted that, in this solution, the transmission power allocation factor occupies very little overhead, for example, it is required to specify that the downlink pilots occupy 0.1 or 0.25 of the total power, and only one bit of information transmission is required.

Option 2: Uplink pilot power constant scheme

In this solution, for the power allocated to the uplink pilot, the power allocated to the uplink pilot may be negotiated to be constant, and the constant value of the uplink pilot power is notified to the second communication device; for the power allocated to the uplink pilot, Flexible allocation can be made according to actual channel conditions (such as CQI) under the premise that the total transmit power does not exceed the predetermined total transmit power limit.

In this solution, for the downlink channel, since the power of the uplink pilot is known to be constant, the second communication device can be informed of the actual uplink pilot condition, which provides a primary premise for ensuring the correctness of the uplink channel. For the downlink channel, since the downlink pilot is power-adjusted at the first communication device, the estimated downlink channel and the real channel may differ by a factor; however, since the second communication device acquires the downlink channel parameter, the purpose is to Transmitting the signal for pre-processing to make some useful corrections to the channel, Since the signal remains unchanged before and after passing through the pre-processing module, the second communication device does not actually need to know the scale factor of the difference between the estimated downlink channel and the actual downlink channel, but only needs to normalize the estimation result. It can be used to design pre-processing modules and perform pre-equalization or pre-coding pre-processing.

It can be seen that, if the power allocation scheme described in the second scheme is used, the first communication device does not need to feed back any power allocation information. Therefore, scheme 2 can further save feedback overhead relative to scheme 1.

Step 203: The second communications device receives the mixed pilot transmitted by the first communications device.

After receiving the signal, the second communication device extracts the mixed pilot therein. It is assumed that the signal sent by the first communication device reaches the second communication device through the uplink channel with the delay extension length, and the mixed pilot signal received by the second communication device can be expressed as:

_{y Bp ( ") = diag {} Y up {n) + P {n)) F up H u i + w βρ (η) (4), wherein the second communication device indicates the mixing guide the received frequency;

The sum of the downlink pilot received by the communication device and the additive noise passing through the uplink channel; P _ul (n) represents the sum of the uplink pilot transmitted by the first communication device and the additive noise passing through the uplink channel in the frequency domain; Diag(Y _up (n + P _ul (n shows the diagonal matrix formed by the sum of Y _up (n and ^O), ρ represents the discrete Fourier transform (DFT) matrix for the uplink channel and the pilot A matrix of corresponding parts; represents a convolution matrix for the upstream channel; w _Bp (n) represents additive noise superimposed at the receiving end when the mixed pilot arrives at the second communication device.

The function formula (4) can also be written as a convolutional form of the time domain signal as shown in functional formula (5):

Wherein ^ represents the time domain form of the downlink channel; 3⁄4 _/ represents the time domain form of the uplink channel; ρ τ ή represents the time domain form of the uplink pilot in the mixed pilot received by the second communication device; represents the second communication device receiving a time domain version of the uplink pilot in the mixed pilot; w _{T r} 0) indicating that the hybrid pilot is passing a time domain form of additive noise superimposed in an uplink channel; a time domain form indicating additive noise of the pilot signal superimposed at a receiving end of the second communication device; indicating a total equivalent noise term;

Step 204: The second communications device estimates the uplink channel according to the received mixed pilot and the known uplink pilot to obtain an uplink channel device.

After receiving the hybrid pilot sent by the first communications device, the second communications device estimates the uplink channel, and specifically, the uplink pilot that is known by the second communications device is used. The uplink communications are used by the second communications device and the first communications device. The pre-negotiated determination determines the point multiplication by the received mixed pilot. That is equivalent to convolution with the received mixed pilot signal ^^( ) in the time domain using the conjugate of the time domain form _3⁄4 ( ) of the known uplink pilot: ρ (η), with:

(6),

⁼ ΐ/(")* /* /* (") ⁺ ΐ/(")3⁄4/*3⁄4/(")+4/(") (")

Without loss of generality, let the function (2) equal 1 and the functional formulas (2) and (3) into the function (6) respectively, and the function (7) can be obtained: / / ⁽ 3⁄4 " ^{) =} ( ⁷ ),

The estimated value of the acquired uplink channel parameter can be calculated according to the function formula (7). It should be noted that, if the first communication device transmits the hybrid pilot, the power allocation according to the allocation scheme of the transmit power in step 202 is used, and accordingly, after the second communication device receives the mixed pilot, According to the received power allocation factor", use

Substituting /(«) in function formulas (6), (7), the corresponding uplink channel estimation can be performed according to the replaced functional formula; if the first communication device is transmitting the hybrid pilot, step 202 is used. In the power allocation described in the second embodiment of the transmission power distribution, the functions (6) and (7) may be directly applied for calculation.

Step 205: The second communications device estimates the closed-loop channel according to the known downlink pilot and the received mixed pilot, and acquires a closed-loop channel parameter. Since the downlink pilot is transmitted from the second communication device to the first communication device via the downlink channel, and then returned by the first communication device to the second communication device via the uplink channel, the closed-loop channel formed by the uplink channel and the downlink channel passes.

Therefore, similar to the estimation of the uplink channel, the second communication device can use the known downlink pilot (ie, the downlink pilot that is sent by the second communication device to the first communication device) to multiply the received mixture in the frequency domain. Pilot, performing closed loop channel estimation. That is equivalent to the time domain, a time domain representation of a known downlink pilot conjugated p _dl (n) convoluted with the mixing received pilot signal y _Bp {ri), are:

₍₈₎ ,

3⁄4/(") ⁺ /(") 3⁄4(")+3⁄4(")* ^w (")

Substituting the functional formula (1) into the functional formula (8), we can get the functional formula (9):

Hall = hdl * hul = p _dl (n) * (w) = hdl * l + p _dl {n) * w(n) ( 9 ), according to the function formula (9), the estimated value of the closed-loop channel parameter can be calculated^ _{/D It} should be noted that if the first communication device transmits the hybrid pilot, the power allocation of the allocation scheme of the downlink pilot and the uplink pilot between the uplink pilots in step 202 is used, and the corresponding After the second communication device receives the mixed pilot, according to the received power allocation factor,

Function (8), ^^O) in (9), the closed-loop channel can be estimated according to the replaced functional formula; if the first communication device transmits the mixed pilot, the one used in step 202 is used. The power allocation described in the second embodiment of the allocation of the transmission power between the downlink pilot and the uplink pilot is directly applied to the calculation of the closed-loop channel by using the functional equations (8) and (9).

Step 206: The second communications device acquires a downlink channel history according to the closed loop channel parameter and the uplink channel parameter.

The estimated value of the uplink channel can be calculated according to the function formula (7), and the function formula (9) is calculated. The estimated value of the obtained closed-loop channel is obtained by deconvolution, and the estimated value of the downlink channel is obtained to obtain the downlink channel ^:^.

In addition, the downlink channel parameters can also be obtained from the frequency domain. Suppose that a downlink pilot is located at the m^i channel H _m on the downlink channel, and after being superimposed with the uplink pilot at the device of the Kth, the second communication device is returned from the nth subframe of the uplink, then the function The frequency domain expressions of equations (7) and (9) are:

Hm = HnmlHn ( 10 ),

Where H is the frequency domain representation of the downlink channel parameters; Hnm is the frequency domain representation of the closed-loop channel parameters; H« is the frequency domain representation of the upstream channel parameters.

It should be noted that the second communication device in this embodiment may be, but is not limited to, a base station, and the first communication device may be, but is not limited to, a terminal.

It can be seen that the first communication device applying the technical solution of the embodiment sends the downlink pilot delivered by the first communication device received by the second communication device to the second communication device, and needs to send the downlink pilot to the second communication device. And the second communication device can estimate the uplink channel according to the mixed pilot and the predicted uplink pilot; and can estimate according to the mixed pilot and the known downlink pilot The closed loop channel is then combined with the estimated upstream channel and closed loop channel to estimate the downlink channel. It is possible to acquire the parameters of the downlink channel while performing uplink channel estimation. Compared with the prior art, the technical solution of this embodiment greatly reduces the signaling overhead for the second communication device to acquire downlink channel parameters. For example, if the power allocation scheme 1 in step 202 is used, the method for applying the embodiment of the present invention requires only a small signaling transmission power allocation factor, and if the power allocation scheme 2 in step 202 is used, the implementation of the present invention is applied. The signaling overhead required for the example method is zero.

Embodiment 2: This embodiment takes a method for acquiring channel information provided by an embodiment of the present invention in a MIMO system as an example, and the method is specifically described. The basic process of the method is shown in FIG. , the method mainly includes:

Step 301: The second communications device sends a downlink pilot to the first communications device. This step is the same as step 201 in Embodiment 1, but since the multi-antenna transmission and reception techniques are used in the MIMO system, the present embodiment is different from Embodiment 1 in that: each antenna of the second communication device Downlink pilots are respectively sent to the first communications device.

In order to prevent the downlink pilots in the hybrid pilot in the technical solution of the embodiment from affecting the estimation of the uplink channel and the closed loop channel by the second communication device, the first communication device and the second communication device may be preset. For each uplink pilot and downlink pilot, each uplink pilot and downlink pilot respectively satisfy the following conditions:

(1) For the downlink pilots sent by the antennas of the second communication device to the first communication device, the convolution result of each downlink pilot in the time domain may be extended in the delay of the uplink channel/^ and the downlink channel The range of the delay spread length / ^ is the impulse function, that is, the autocorrelation function of each downlink pilot in the time domain can be expressed as: 1 ^{1 )} , the downlink pilot transmitted by the communication device

The downlink pilot delivered by the first communication device; is a real number greater than zero, and may be equal to 1 without loss of generality.

(2) For each uplink of the antenna pair, the convolution result in the time domain is an impulse function in the delay spread length _μ/ range of the uplink channel, that is, the self-time of each uplink pilot in the time domain. The correlation function can be expressed as:

,· * "α η = 0 (

= _{0 < n ≤ Lul} ^{( 16 )} , where i is the identity of the antenna of the first communication device; j is the identity of the antenna of the first communication device;

Equal to 1.

(3) Convolution result of any uplink pilot and any downlink pilot for each uplink pilot and downlink pilot In the range of the delay spread length _m of the uplink channel and the delay spread length / ^ of the downlink channel, that is: ∑ / *( /(" - 0 =. Q < n _≤ L _{ul +} L _dl (17),

n where 4 W represents the conjugate of the uplink pilot (t) sent by the first communication device antenna i to the second communication device; ^^- t) indicates that the second communication device antenna j is delivered to the first communication device Downlink pilot; i, j are antenna identifiers respectively, i can be equal to j; a is a real number greater than zero, and can be equal to 1 without loss of generality.

The second communication device sends the downlink pilot that satisfies the constraint condition represented by the functional formulas (11), (17) to the first communication device, so that the second communication device directly receives the downlink pilot after receiving the downlink pilot. The downlink pilot is superimposed with the uplink pilot without additional processing of the received downlink pilot.

Step 302: The first communications device receives the downlink pilot, and superimposes the received downlink pilot with the uplink pilot to generate a mixed pilot, and sends the superposed mixed pilot to the second communications device.

It is assumed that in the ΜΙΜΟ system of the embodiment, the second communication device and the first communication device both transmit and receive with two antennas, and the second communication device sends downlink pilots to the first communication device through the antennas 1, 2 respectively, at the first At the communication device, the pilot signal γ ¹ (η) received by the antenna 1 of the first communication device is:

+ w _U ^l _p (n) ( 12 ), wherein the downlink pilot transmitted by the antenna 1 of the second communication device received by the antenna 1 of the first communication device is received; a downlink pilot that is sent by the second communication device antenna 2; a downlink channel of the antenna 1 of the second communication device to the antenna 1 of the first communication device;

dl an antenna ² antenna of the second communication device to the first communication apparatus 1 of the downlink ^channel; Ρ Φ denotes a matrix portion corresponding to the DFT matrix for the downlink channel with the pilot configuration.

The pilot signal _p received by the antenna 2 of the first communication device (n is:

= (PJ / + dg P _dp h + w _U ^l _p (n) ( 13 ), where ^ W represents the downlink pilot transmitted by the antenna 2 of the first communication device received by the antenna 1 of the second communication device; a downlink pilot transmitted by the antenna 2 of the first communication device and transmitted by the antenna 2 of the second communication device; a downlink signal indicating the downlink of the antenna 1 of the second communication device to the antenna 2 of the first communication device

The channel represents the downlink channel of the antenna 2 of the second communication device to the antenna 2 of the first communication device; F _dp represents a matrix formed by the portion corresponding to the pilot in the DFT matrix of the downlink channel.

After the first communication device demodulates the received signal by de-CP and OFDM, the downlink pilot signal on the corresponding pilot channel on each receiving antenna is extracted, and the uplink pilot to be sent to the antenna is used. Corresponding superposition is performed to generate a mixed pilot to be transmitted by each antenna on the first communication device. For example: The mixed pilot on antenna 1 of the first communication device is:

Xi(n) = y _u ^l _p (n) + P _u ^l _l (n) (14),

Wherein, the uplink pilot transmitted by the antenna 1 of the first communication device to the second communication device is indicated. The mixed pilot on antenna 2 of the first communication device is:

X2{n) = y _up (n) + P _ul (n) (15), where the uplink pilot transmitted by the antenna 2 of the first communication device to the second communication device is indicated. The uplink pilot transmitted by the first communication device to the second communication device satisfies the restriction condition represented by the functional formulas (16) and (17) in the above step 301.

The first communication device performs OFDM modulation on the mixed pilot and uplink data of each antenna, adds the CP, and transmits the signal to the second communication device through the uplink channel.

The first communication device may transmit the hybrid pilot. Referring to the power allocation schemes 1 and 2 in Embodiment 1, the following power allocation scheme is used:

Option 3: Total power constant scheme The same as the first solution of step 202 in Embodiment 1 is: arranging that the total transmit power of the pilot subcarrier of the first communication device (including the power of transmitting the uplink pilot and the downlink pilot in the subcarrier) is constant, The constant value may be notified to the second communication device after the appointment.

Different from the first solution in the embodiment: since the current system is a MIMO system, it is possible that the downlink pilots received by the antennas of the first communication device are respectively from different antennas of the second communication device, and thus the first communication device The hybrid pilot transmitted by each antenna includes a plurality of uplink pilots, and the hybrid pilots are: a superposition of a plurality of downlink pilots and an uplink pilot that is required to be sent by the antenna to the second communication device. Therefore, the ratio of this rate.

Scheme 4: Uplink pilot power constant scheme

The solution is different from the first solution in the step 202 of the first embodiment. The first communication device uses multiple antennas to transmit, and each antenna sends its own uplink pilot. Therefore, for the first communication device, the total The uplink pilots that are sent may be more than one. Therefore, for the power of the uplink pilot allocated to each antenna pair, the transmit power of the uplink pilot of the antenna of the first communication device may be negotiated to be a constant value, and each uplink is agreed upon. The constant value of the pilot power informs the second communication device.

The power of the uplink pilot of each antenna is similar to the scheme 2 in Embodiment 1, and can be flexibly allocated according to channel conditions (such as CQI) under the premise that the total transmit power does not exceed the predetermined total transmit power limit. .

It can be seen that if the power scheme described in Embodiment 4 is used, the first communication device does not need to feed back any power allocation information, which can further save feedback overhead with respect to scheme 3.

Step 303: The second communications device receives the mixed pilot transmitted by the first communications device.

After the hybrid pilot transmitted by the first communication device passes through the uplink channel, it reaches the second communication device. Assuming that the second communication device uses two antennas to transmit and receive, at the second communication device, the mixed pilot received by the antenna 1 of the second communication device is a superposition of the mixed pilots transmitted by the second communication terminal antenna 1 and the antenna 2, The mixed pilot received by the antenna 1 of the second communication device can be expressed as: 1 1 1 11 2 2 12 1

yBP (") = ^dia S( ^Y up (") + ^p ul ("))3⁄4A/ + ^dia S( ^Y up (") + ^p ul ("))3⁄4 / + ^w Bp ( ⁿ ) ( ^{1 8} ) Wherein / ^ UI represents the uplink channel of the antenna 1 of the first communication device to the antenna 1 of the second communication device; represents the uplink channel of the antenna 2 of the first communication device to the antenna 1 of the second communication device;

The additive noise superimposed at the antenna 1 of the second communication device; ρ represents a matrix of portions corresponding to the pilots in the DFT matrix of the upstream channel.

Similarly, the mixed pilot received by the antenna 2 of the second communication device can be expressed as:

2 1 1 21 2 2 22 2

BP (") = ^dia S( ^Y up (") + ^p ul ("))3⁄4Λ/ + ^dia S( ^Y up (") + ^p ul ("))3⁄4A/ + ^w Bp ( ⁿ ) ( ¹⁹ )° Wherein / ¹ represents the uplink channel of the antenna 1 of the first communication device to the antenna 2 of the second communication device;

Representing an uplink channel of the antenna 2 of the first communication device to the antenna 2 of the second communication device;

The additive noise superimposed at the antenna 2 of the second communication device.

It should be noted that, in this embodiment, both the first communication device and the second communication device use two antennas to transmit and receive. However, the embodiment is not limited thereto, and the number of transmitting and receiving antennas of the first communication device and the second communication device is also Can be different.

Step 304: The second communications device estimates each uplink channel according to the received mixed pilot and the known uplink pilots, and acquires each uplink channel device.

For each uplink channel estimate, the second communications device uses the known uplink pilots to multiply the mixed pilots received by the antennas in the frequency domain. That is equivalent to the time domain form of the uplink pilot of the antenna i of the first communication device known by the second communication device in the time domain, and the antenna of the second communication device

The mixed pilot signal received by j is convoluted, and the uplink channel from antenna i to antenna j is estimated, ρ^{η) and _yB J _p (n, convolution can be expressed as:

= Pui^ * * i) * di^ + ^h * ^h ) * di^ + ^h2 * ^h i * di^ ( ²⁰ ).

Substituting the functional formulas (16), (17) into the functional formula (20), the uplink channel of the antenna i of the first communication device to the antenna j of the second communication device can be estimated:

") = + p * (") ( ²¹ ).

For example: for the estimation of the uplink channel of the antenna 1 of the first communication device to the antenna 1 of the second communication device, the second communication device uses the uplink pilot of the antenna 1 of the known first communication device (pre-agreed know) j The conjugation of (n) is convoluted with the signal _D (n) received by the antenna 1 of the second communication device, and can be estimated

( ²² ),

Similarly, the second communication device convolves with the signal received by the antenna 1 of the second communication device by using the conjugate of the uplink pilot (pre-defined) of the antenna 2 of the known first communication device, which can be estimated. Upstream channel; ^:

Ul

*V") = ^h J ^l + , * ") ( ²³ ),

Similarly, the second communication device uses the conjugate of the uplink pilot (pre-defined) («) of the antenna 1 of the known first communication device and the signal received by the antenna 2 of the second communication device (n).

Convolution, you can estimate the upstream channel / ^1:

UI 2 ⁼ (") * = ^h ul + * ^W B _P ^ ( ²⁴ ).

Similarly, the second communication device convolves with the signal received by the antenna 2 of the second communication device by using the conjugate of the uplink pilot (pre-approved) of the antenna 2 of the known first communication device. Estimate the upstream channel / ^ ² :

Ul

2 ⁼ (") * = ^k u + O * ^W ") ( ²⁵ ).

It should be noted that, if the first communication device transmits the hybrid pilot, the power allocation described in the third step of step 301 is used, and accordingly, after the second communication device receives the mixed pilot, according to the known The ratio of the uplink pilot power to the total power: the allocation factor", using the corresponding replacement function

( 21 ), the uplink channel can be estimated according to the replaced functional formula;

When transmitting the hybrid pilot, the communication device uses the power allocation described in the fourth embodiment of the downlink pilot in step 301 and the transmission power between the uplink pilots, and directly applies the function formula (21) for calculation. It is sufficient to estimate each uplink channel.

Step 305: The second communications device estimates each closed-loop channel according to the known downlink pilots and the received mixed pilots, and acquires each closed-loop channel parameter.

Since each downlink pilot passes from the second communication device to the first communication device via the downlink channel, and then the first communication device returns to the second communication device via the uplink channel, the closed channel formed by the uplink channel and the downlink channel passes.

Therefore, in the same manner as the uplink channel estimation in step 302, the second communication device may perform time domain on the downlink pilots sent by the antennas of the known communication device and the hybrid pilots received by the second communication device, respectively. Convolution or point multiplication on the frequency domain. E.g:

In the time domain, the conjugate of the time domain form 0) of the downlink pilot transmitted to the first communication device by the antenna i of the second communication device known by the second communication device is respectively received by the second communication device The mixed pilot signal ₇ ^) is subjected to a convolution operation, and the equations are solved for each convolutional expression, and each closed-loop channel can be estimated to obtain each closed-loop channel parameter.

For example, the case where the second communication device transmits and receives the two antennas is taken as an example. For the mixed pilot received by the antenna 1 of the second communication device, the downlink pilot of the antenna 1 and the downlink pilot of the antenna 2 can be used for the hybrid respectively. The pilot performs convolution in the time domain or point multiplication in the frequency domain; for the mixed pilot received by the second communication device antenna 2, the downlink pilot of the antenna 1 and the downlink pilot of the antenna 2 can be used respectively. The mixed pilot performs convolution in the time domain or point multiplication in the frequency domain. Combined with each arithmetic function formula, the estimation result of the closed-loop channel can be obtained.

Step 306: The second communications device acquires each downlink channel device according to each closed loop channel parameter and each uplink channel parameter.

In the same manner as step 206 in the first embodiment, the downlink channel parameters of the antenna pair are obtained according to the closed loop channel parameters and the uplink channel parameters. E.g:

The downlink channel is a 2x2 matrix / 3⁄4>, and the upstream channel is a 2x2 matrix.

' That is:

It can be seen from the function formula (28) that each downlink channel, h, h _d ³ , h _d ⁴ can be obtained according to the estimated closed-loop channel 11, each uplink channel, and . It should be noted that the second communication device in this embodiment may be, but is not limited to, a base station, and the first communication device may be, but is not limited to, a terminal.

A person skilled in the art can understand that all or part of the steps of implementing the above embodiments can be completed by hardware related to program instructions, and the program can be stored in a computer readable storage medium, when executed, The method may include the following steps: the second communication device receives the first communication device Generating a downlink pilot, and superimposing the received downlink pilot with the uplink pilot to generate a mixed pilot, and transmitting the mixed pilot to the first communications device; the first communications device receives the mixed pilot, and according to The received hybrid pilot and the known uplink pilot are used to estimate an uplink channel to obtain an uplink channel parameter; the first communications device performs a closed loop channel according to the known downlink pilot and the received mixed pilot. Estimating, acquiring a closed loop channel parameter; the first communications device acquiring the downlink channel parameter according to the closed loop channel parameter and the uplink channel parameter. The storage medium may be: a ROM/RAM, a magnetic disk, an optical disk, or the like.

It can be seen that, after receiving the downlink pilots sent by the antennas of the second communication device, and receiving the uplink pilots by the antennas, the antennas of the first communication device of the first embodiment of the present embodiment are used. And transmitting, by the second communication device, the hybrid pilot formed by the uplink pilots to be sent and the uplink pilots to be sent are sent to the second communications device, and the second communications device can estimate according to the mixed pilots and the known uplink pilots. The second communication device may further estimate each closed-loop channel according to the mixed pilot and the known downlink pilots, and then combine the estimated uplink channels and the closed-loop channel to estimate each downlink. channel. The technical solution of the embodiment can obtain the parameters of each downlink channel while estimating the uplink channels, and greatly reduce the signaling overhead for acquiring the parameters of the downlink channel. For example, if the power allocation scheme 3 in step 302 is utilized, only a small signaling overhead for transmitting the power allocation factor is needed, and if the power allocation scheme 4 in step 302 is referenced, the required signaling overhead is zero.

Embodiment 3: This embodiment takes another method for obtaining channel information provided by an embodiment of the present invention in the SISO system as an example, and the method is specifically described. FIG. 4 is a schematic flowchart of the method of the embodiment. As shown in FIG. 4, the method mainly includes:

Step 401: The second communications device sends a downlink pilot to the first communications device.

This step is basically the same as step 201 in Embodiment 1, except that:

In order to prevent the downlink pilot in the hybrid pilot in the technical solution of the present invention from affecting the estimation of the uplink channel by the first communications device, the uplink pilot and the downlink pilot between the first communications device and the second communications device may be preset. , the uplink pilot and the downlink pilot respectively satisfy the following conditions:

(1) The downlink pilot that is sent by the second communications device to the first communications device can be sent down. The convolution result of the pilot in the time domain is an impulse function in the range of the delay spread length of the uplink channel _3⁄4/ , that is, the autocorrelation function of the downlink pilot in the time domain can be expressed as:

. ⁽²⁹⁾ , where z^/W represents the conjugate of the downlink pilot P _dl ; represents the delay spread length of the downlink channel; is a real number greater than zero, and may be equal to 1 without loss of generality.

(2) for the uplink pilot transmitted by the first communication device to the second communication device, the convolution result in the time domain is an impulse function in the delay extension length _3⁄4/ range of the uplink channel, that is, the uplink pilot The autocorrelation function on the time domain can be expressed as shown in function (2) in step 201 of the embodiment 1.

(3) For the uplink pilot and the downlink pilot, the convolution result of the two is zero in the range of the delay spread length of the uplink channel, that is:

Vul ^(t)P dl ⁿ - ^{t) =} ° ° ^≤n≤L ul ( ^{30 )} ,

It should be noted that if the downlink pilot satisfies the condition represented by the functional formula (3) in Embodiment 1, it necessarily satisfies the condition represented by the functional formula (30) in this embodiment, that is, it can be understood as: (30) The condition of the restriction is a subset of the conditions restricted by functional formula (3).

The second communication device sends the downlink pilot that meets the limits of the functions (29) and (30) to the first communication device, so that the first communication device directly receives the received downlink pilot after receiving the downlink pilot. Superimposed with the uplink pilot without additional processing of the received downlink pilot.

Step 402: The first communications device receives the downlink pilot, and superimposes the received downlink pilot with the uplink pilot to generate a mixed pilot, and sends the superposed mixed pilot to the second communications device.

This step is basically the same as the step 202 in the first embodiment: after receiving the downlink pilot, the first communication device superimposes the received downlink pilot with the uplink pilot to be transmitted to generate a mixed pilot, and the mixed pilot Send to the second communication device. This step is different from step 202 in that the uplink pilot transmitted by the first communication device to the second communication device satisfies the restriction condition represented by the functional formulas (2) and (30) in step 401. After the first communication device generates the hybrid pilot, when the uplink data is sent to the second communication device, the superimposed mixed pilot is OFDM-modulated together with the uplink data, and the CP is added for uplink transmission and sent to the second. communication device.

The first communication device may use the pilot power allocation scheme in the first embodiment or the second embodiment in the case of transmitting the hybrid pilot. For details, refer to the related description in Embodiment 1, and no further details are provided herein.

Step 403: The second communications device receives the mixed pilot sent by the first communications device.

This step is the same as step 203 in the first embodiment. It is assumed that the hybrid pilot transmitted by the first communication device reaches the second communication device after the uplink channel with the delay extension length of Lui, and the mixed pilot received at the second communication device can be represented as a function in step 201 of Embodiment 1. The form shown by the formula (2).

Step 404: The second communications device estimates the uplink channel according to the received mixed pilot and the known uplink pilot to obtain an uplink channel device.

In the same manner as step 204 in the first embodiment, the second communication device convolves in the time domain using the conjugate ( _η ) of the known uplink pilot in the time domain form and the received mixed pilot signal yn). Function (6), estimating the uplink pilot according to function (6):

( ₆₎ ,

You can make the function formula (2) equal to 1, and the function formulas (2) and (30) into the function formula (6), and you can get the function formula (7):

K (")* ") = (7 ),

The estimated value of the acquired uplink channel parameter can be calculated according to the function formula (7). It should be noted that, if the first communication device uses the power allocation scheme described in the first step of step 202 when transmitting the hybrid pilot, the second communication device receives the mixed pilot, according to the received Power allocation factor", use (1 - ") / (") to replace ^ ^ («) in function (6), (7), The estimated value of the uplink channel can be obtained according to the replaced functional formula; if the first communication device uses the power allocation described in the second step of step 202 when transmitting the mixed pilot, the function formula (6) is directly applied. (7) Calculate to obtain an estimate of the uplink channel.

Step 405: The second communications device resumes acquiring the mixed pilot transmitted by the first communications device according to the uplink channel parameter.

According to the estimation result of the uplink channel, the hybrid pilot received by the second communication device may be equalized to recover the signal of the hybrid pilot at the transmitting end (the first communication device). Among them, the methods of equalization recovery are: ZF equalization, MMSE equalization, and the like. For example, using ZF equalization can be obtained: y _U ei ⁿ ) = { ^dia S{H _u i))~ ^l y _Bp (n) ( 31 ) where represents the mixed pilot transmitted by the first communication device to be recovered; Denoting a parameter of the estimated uplink channel; diag{H _ul ) indicating a diagonal matrix formed by the estimated uplink channel parameters;

The (diag(H _u i )) matrix takes the inverse matrix.

The signal obtained by the hybrid pilot at the transmitting end (the first communication device), that is, the mixed pilot transmitted by the first communication device, can be calculated according to the functional formula (31).

Step 406: The second communications device estimates, according to the recovered hybrid pilot, the known uplink pilot and the downlink pilot, the downlink channel parameter.

Functional formula (31)

Pue («) = ( iag(H _ul y _βρ (n)

= diag(P _dl (n))F _dp h _dl + w _up (n) + P _ul (n) + (diag(H _ul ))~ ^l w _Bp (n) ( 32 ), =diag(P _d i (n)) F _dp h _d i + _3⁄4/ (n) + w(n) where corpse ί / (" ) represents the frequency domain form of the downlink pilot; diag (P _dl (")) represents the frequency of the downlink area a diagonal matrix formed by the upper pilot; an IFFT matrix indicating the uplink pilot; a downlink time domain channel vector; an additive noise indicating the hybrid pilot superimposed on the uplink channel; a frequency domain form indicating the uplink pilot; The diagonal matrix formed by the downlink pilots; w^pO?) represents the superimposed noise on the mixed pilot received by the second communication device; represents the total equivalent noise term.

Function by the formula (32) can be seen, by subtracting the second communication device known in the uplink pilot ^ _¾ ( «) from the formula (a first communication device and the second communication device previously agreed), i.e., the estimated value can be obtained: Diag{Pdl {n))F _dp h _d i + w(n).

After the estimated value is obtained: the downlink pilot transmitted by the known second communication device to the first communication device and the known 7^ can be used to estimate the history of acquiring the downlink channel.

It can be seen that, after receiving the downlink pilot sent by the second communications device, the first communications device that is used in the technical solution of the embodiment sends the uplink pilot to the second communications device, and then receives the downlink downlink. The frequency is superimposed with the uplink pilot to be transmitted, a hybrid pilot is generated, and the mixed pilot is transmitted to the second communication device. After receiving the hybrid pilot, the second communications device can estimate the uplink channel history according to the mixed pilot and the known uplink pilot; and according to the estimated uplink channel history, the hybrid sent by the first communications device can be recovered. a pilot, an uplink pilot sent by the first communications device to the second communications device according to the hybrid pilot transmitted by the restored first communications device, and the downlink pilot that is sent by the second communications device to the first communications device. The frequency is estimated to obtain the parameters of the downlink channel, so that the uplink channel parameters can be obtained while the parameters of the downlink channel are obtained, and the signaling overhead required for acquiring the downlink channel parameters is greatly reduced.

In addition, since the downlink channel parameters are not required to be obtained by calculating the closed-loop channel parameters in this embodiment, the convolution result between the uplink pilot and the downlink pilot is the delay spread length of the uplink channel. ^ is zero (satisfying the function (30)), and it is not required to be zero in the range of the delay spread length _3⁄4/ + of the closed-loop channel as required in the embodiment 1 (means that the function (3) is satisfied) . The number of available pilot sequences due to the conditions restricted by functional formula (3) is: where Ν is the OFDM symbol

The length, and the number of available pilot sequences resulting from the constraints of function (30) is: NIL _ul . It can be seen that the technical solution of the present embodiment can greatly increase the number of available pilots in the OFDM symbol with respect to the technical solution of the first embodiment, so that the pilot overhead is further reduced.

Embodiment 4: This embodiment takes another method for acquiring channel information provided by an embodiment of the present invention in a MIMO system as an example, and the method is specifically described. The basic process of the method is shown in Figure 5, the port diagram, the method may include:

Step 501: The second communications device sends a downlink pilot to the first communications device.

This step is the same as the step 301 in the second embodiment. The difference is: in order to prevent the downlink pilots in the mixed pilot from affecting the estimation of the uplink channel and the closed loop channel by the second communication device in the technical solution of the present invention. The uplink pilot and the downlink pilot between the first communication device and the second communication device may be preset, so that each uplink pilot and downlink pilot meet the following conditions:

(1) The downlink pilot transmitted by the antennas of the second communication device to the first communication device may be such that the convolution result of each downlink pilot in the time domain is within a delay extension length of the uplink channel of _3⁄4/ The impulse function, that is, the autocorrelation function of each downlink pilot in the time domain can be expressed as:

The conjugate of the downlink pilot ^) sent by the antenna of the first communication device to the second communication device; ^(« _ t) indicates the downlink guide sent by the antenna j of the first communication device to the second communication device Frequency; 7^ / is the delay spread length of the downlink channel; i, j are antenna identifiers, i can be equal to j; is a real number greater than zero, without loss of generality, can be equal to 1. (2) for the downlink pilots sent by the antennas of the second communication device to the first communication device, the convolution result of each downlink pilot in the time domain is impulse within the delay spread length _m/ range of the uplink channel. The function, that is, the autocorrelation function of each uplink pilot in the time domain can be expressed as:

"an = 0 _ri χ

= _{0 < n ≤ Lul} ( ³⁹ ), wherein the conjugate of the uplink pilot transmitted by the antenna i of the first communication device to the second communication device, ^ ^ is the antenna j of the first communication device to the second communication device The transmitted uplink pilot, L _u i is the delay spread length of the uplink channel, which is a real number greater than zero, and i and j are antenna identifiers of the second communication device, and i may be equal to “.

(2) For each uplink pilot and downlink pilot, the convolution result of any uplink pilot and any downlink pilot is zero in the range of the delay spread length _3⁄4/ of the uplink channel, that is:

The second communication device sends the downlink pilot that satisfies the restriction condition represented by the functional formulas (33), (34) to the first communication device, so that the second communication device directly receives the downlink pilot after receiving the downlink pilot. The downlink pilot is superimposed with the uplink pilot without additional processing of the received downlink pilot.

Step 502: The first communications device receives the downlink pilot, and superimposes the received downlink pilot with the uplink pilot to generate a mixed pilot, and sends the superposed mixed pilot to the second communications device.

This step is basically the same as step 302 in Embodiment 2, except that: the uplink pilot transmitted by the first communications device to the second communications device satisfies the functions represented by the functional formulas (39) and (34) in step 501. limitation factor.

In the method of this embodiment, the first communication device may use the third solution or the fourth solution in the second embodiment. The pilot power allocation scheme allocates the mixed pilots of the antennas. For details, refer to the related description in Embodiment 2. I will not repeat them here.

Step 503: The second communications device receives the mixed pilot transmitted by the first communications device.

This step is basically the same as step 303 in Embodiment 2. In the MIMO system of the present embodiment, the second communication device and the first communication device both transmit and receive using two antennas, similar to step 303 in Embodiment 2, and the hybrid guide received by the antenna 1 of the second communication device The frequency can be expressed as a form shown by the functional formula (18). The mixed pilot received by the antenna 2 of the second communication device can be expressed in the form shown by the functional formula (19).

It should be noted that, in the present invention, the second communication device and the first communication device both transmit and receive by using two antennas. However, the present invention is not limited thereto, and the number of the transmitting and receiving antennas of the second communication device and the first communication device may be different.

Step 504: The second communications device estimates each uplink channel according to the received mixed pilot and each known uplink pilot, and acquires each uplink channel history.

The specific implementation of this step is the same as the specific implementation of step 304 in Embodiment 2, and details are not described herein. Step 505: The second communications device resumes acquiring the mixed pilots transmitted by the antennas of the first communications device according to the estimated uplink channel parameters.

The second communication device performs equalization recovery on the mixed pilots received by the antennas of the base station according to the estimated uplink channels, and acquires signals at the transmitting end of the second communication device. Taking the second communication device and the first communication device both using two antennas for transmission and reception as an example: the mixed pilot received by the antenna 1 of the second communication device may be expressed in the form shown by the functional formula (18), and the second communication device The mixed pilot received by the antenna 2 can be expressed in the form shown by the functional formula (19). The equalization recovery of (), ; ^) respectively acquires the mixed pilot j («) transmitted by the antenna 1 of the first communication device, and the mixed pilot x ₂ (n) transmitted by the antenna 2 of the first communication device. The equalization method can use ZF equalization, or MMSE equalization.

In order to facilitate the equilibrium recovery process, the functional formulas (18) and (19) are respectively expressed in the following forms:

^ ^η )=0 )0 ) ^{( 35 )} ,

Vi _n (n) = (η) + h ² x (η) (36). It can be obtained by functional formulas (35) and (36).

(37),

According to the function formula (37), there are: y _B ^l _P (n)

H ( 38 )

y _B p( ⁿ )

The hybrid pilots transmitted by the first communication device antenna 1 and the antenna 2 are estimated according to the function formula (38): x\(n), X2(n). Step 506: The second communications device estimates, according to the recovered mixed pilot, the known uplink pilot and the downlink pilot, the downlink channel history.

Obtaining ^ (ή) and ₂ (after subtracting the uplink pilots 3⁄4(«), Ρ^{η) superimposed by the known first communication device, respectively, can obtain the estimated value of the downlink pilot after passing the downlink channel. y^pin), and then using the known downlink pilot (the second communication device antenna 1 and the downlink pilot transmitted by the antenna 2 to the first communication device), the downlink channel can be recovered.

It should be noted that the second communication device in this embodiment may be, but is not limited to, a base station, and the first communication device may be, but not limited to, a terminal.

It will be understood by those skilled in the art that all or part of the steps of the foregoing embodiments may be implemented by a program to instruct related hardware, and the program may be stored in a computer readable storage medium, and the program is executed. The method may include the following steps: the second communications device receives the downlink pilot that is sent by the first communications device, and superimposes the received downlink pilot with the uplink pilot to generate a mixed pilot, and sends the mixed pilot to the first a communication device; the first communication device receives the hybrid pilot, and estimates an uplink channel according to the received mixed pilot and the known uplink pilot to obtain an uplink channel parameter; Uplink channel parameters, recovering the acquired hybrid pilot transmitted by the second communications device; the first communications device according to the hybrid pilot transmitted by the second communications device, known uplink pilot, known Downlink pilot, obtaining downlink channel parameters. The storage medium referred to herein is, for example, a ROM/RAM, a magnetic disk, an optical disk, or the like.

It can be seen that, after receiving the downlink pilots sent by the antennas of the second communication device, the antennas of the first communication device of the technical solution of the present embodiment receive all the downlink pilots and the antennas to be received by the antennas. The uplink pilots sent by the second communications device are superimposed to generate a hybrid pilot, and the hybrid pilot is sent to the second communications device. After receiving the hybrid pilot, the second communications device can estimate the uplink channel according to the mixed pilot and the predicted uplink pilot; and recover the mixed pilot sent by the first communications device according to the estimated uplink channel history. The downlink channel can be estimated according to the hybrid pilot transmitted by the first communication device that is recovered, and the downlink pilot that is sent by the second communications device and the uplink pilot that is sent by the known first communications device. history. The technical solution of the embodiment can obtain the parameters of the downlink channel while performing the uplink channel estimation, and greatly reduce the signaling overhead for obtaining the parameters of the downlink channel.

In addition, since it is not necessary to obtain each downlink channel parameter by calculating each closed-loop channel parameter in this embodiment, the convolution result between the uplink pilot and each downlink pilot is delayed length of the uplink channel. _3⁄4/ zero is sufficient (function (34) is satisfied), and it is not required to be zero in the range of the delay spread length of the closed-loop channel as required in Embodiment 3 (means function (17) is satisfied). The number of available pilot sequences due to the conditions restricted by functional formula (17) is:

The length of the OFDM symbol, and the number of available pilot sequences obtained by the condition of the function (34) is: NIL _ul . It can be seen that the technical solution of the embodiment can be used to greatly increase the number of available pilots in the OFDM symbol and further reduce the pilot overhead.

Embodiment 5: FIG. 6 is a schematic structural diagram of a communication device according to the embodiment. As shown in the figure, the communication device may include:

The receiving unit 601 is configured to receive a downlink pilot that is sent by the second communications device, where the received downlink pilot can meet the constraint condition represented by the function formula (11) in the embodiment in the time domain.

The pilot coding unit 602 is configured to superimpose the received downlink pilot and the uplink pilot to form a hybrid guide. Frequency.

The pilot coding unit 602 can include:

The uplink pilot coding unit 6021 is configured to encode the uplink pilot transmitted to the second communication device, so that each uplink pilot satisfies the restriction condition represented by the functional formulas (16) and (17) in the second embodiment.

The hybrid pilot coding unit 6022 is configured to perform superposition coding on the uplink pilot acquired by the uplink pilot coding unit 6021 and the downlink pilot received by the receiving unit 601.

The pilot coding unit 602 can ensure that the generated hybrid pilot satisfies the constraint conditions represented by the functional formulas (16) and (17) at the same time, and can ensure that the second communication device receives the hybrid pilot after the uplink channel and the closed loop channel. The estimate is not affected by the superimposed downlink pilots.

The coding superposition here is to superimpose the uplink pilot and the downlink pilot in subcarriers of one OFDM symbol. In the OFDM system, the superimposed hybrid pilots are represented as: a downlink pilot of a downlink channel between the second communication device and the second communication device, and a corresponding uplink channel in one subcarrier of one OFDM symbol Uplink pilot.

The sending unit 603 is configured to send the mixed pilot to the second communications device, which is generally a transmitting antenna. It should be noted that, if the communication device supports the MIMO technology, the mixed pilot transmitted by each antenna is the pilot pilot unit 602 is a mixed pilot that needs to be sent through the antenna, that is, the hybrid pilot is: the antenna The superposition of the received downlink pilots sent by the antennas of the second communication device and the uplink pilots that the antenna needs to send to the second communication device.

The communication device can generate the pilot pilot by the pilot coding unit 602 and transmit it to the second communication device via the transmitting unit 603.

However, in general, in combination with the processing in the prior art, as shown in FIG. 7, after the pilot coding unit 602 generates the hybrid pilot, the modulation unit 604 may be used to perform OFDM modulation on the generated mixed pilot together with the uplink data, and then, The CP encoding unit 605 is used to add the modulated OFDM signal to the CP, and then transmit the uplink transmission through the transmitting unit 603 to the second communication device.

The communication device of this embodiment may be, but is not limited to, a terminal. It can be seen that the communication device provided by the embodiment of the present invention passes the downlink pilot that is sent by the second coding device received by the communication device by the pilot coding unit 602, and the communication device is to be sent to the second communication device. The uplink pilot is mixed and superimposed, and the received downlink pilot is returned to the second communication device while the uplink pilot is transmitted, so that the second communication device can be based on the received mixed pilot, and Knowing the uplink pilot, estimating the uplink channel, and estimating the downlink channel according to the estimated uplink channel and the known downlink pilot, and acquiring the parameters of the downlink channel. For details, refer to the specific processing procedure of the second communication device in Embodiments 3 and 4. Related descriptions are not described herein. In this way, the second communication device can perform corresponding pre-processing (pre-coding, or pre-equalization) according to the downlink channel parameters.

At the same time, the second communication device acquires the history of the downlink channel by transmitting the mixed pilot superposed by the downlink pilot and the uplink pilot, instead of performing corresponding on the communication device as described in the prior art. The downlink channel is estimated, and the estimated downlink channel parameter is transmitted with the uplink pilot, and a certain subcarrier in the transmitted signal is occupied, and transmitted to the second communication device, so that the second communication device acquires the parameter of the downlink channel. It can be seen that the communication device to which the present invention is applied can avoid the complex processing of the downlink channel estimation, precoding, and the like, and can avoid the distortion generated during the parameter transmission of the downlink channel. Moreover, since the pilot coding unit 602 uplinks The superposition of pilot and uplink pilots, the communication device to which the present invention is applied greatly reduces the pilot overhead used, and saves transmission resources.

Embodiment 6: FIG. 8 is a schematic structural diagram of another communication device according to the embodiment. As shown in the figure, the communication device of this embodiment is different from the communication device shown in FIG. 7 in Embodiment 5 in that:

First, the receiving unit 801 in this embodiment replaces the receiving unit 601 in the embodiment 5, and the receiving unit 801 is configured to receive the downlink pilot that is sent by the second communications device, where the received downlink pilot can be in the time domain. The form satisfies the constraints expressed by the functional formula (33) in the embodiment.

The second hybrid pilot coding unit 8022 and the uplink pilot coding unit 8021 in the pilot coding unit 802 in this embodiment replace the hybrid pilot coding unit 6022 in the pilot coding unit 602 in the embodiment 5, respectively. The uplink pilot coding unit 6021.

The uplink pilot coding unit 8021 in this embodiment is used for uplinking to the second communication device. The frequency is encoded such that each of the uplink pilots satisfies the restriction conditions expressed by the functional formulas (39) and (34) in the fourth embodiment. The pilot is superimposed and encoded with the downlink pilot received by the receiving unit 801.

The uplink pilot generated by the uplink pilot coding unit 8021 satisfies the constraint conditions represented by the functional formulas (39) and (34), and can ensure that the estimation of the uplink channel is not affected by the second communication device after receiving the hybrid pilot. The effect of the downlink pilots being superimposed.

As can be seen from the above, the communication device provided by the embodiment of the present invention, through the pilot coding unit 802, the downlink pilot that is sent by the second communication device to the communication device, and the communication device to be sent to the second communication device The uplink pilot performs mixing and superimposition, and returns the received downlink pilot to the second communication device while transmitting the uplink pilot, so that the second communication device can be based on the received mixed pilot, and known The uplink pilot estimates the uplink channel, and according to the estimated uplink channel, the received mixed pilot channel at the pilot transmitting end can be recovered, thereby being able to recover according to the recovered mixed pilot and the known downlink pilot and uplink. Pilot, obtain the parameters of the downlink channel. The specific processing procedure of the second communication device is described in detail in the embodiments 3 and 4, and details are not described herein.

Similarly, in Embodiment 5, the communication device to which the present invention is applied can avoid the complicated processing of the downlink channel estimation, precoding, and the like, and can avoid the distortion generated during the parameter transmission of the downlink channel. In addition, due to the pilot The coding unit 802 superimposes the uplink pilot and the uplink pilot, and the communication device applying the present invention greatly reduces the pilot overhead used compared with the prior art, thereby saving the transmission resource cost.

The embodiment of the invention further provides a communication device, comprising: a receiving unit, an uplink channel estimating unit and a downlink channel estimating unit. The receiving unit is configured to receive the hybrid pilot that is sent by the first communications device, where the hybrid pilot is: the downlink pilot that is sent by the first communications device and is sent by the communications device, and the uplink pilot. The uplink channel estimation unit is configured to: estimate, according to the hybrid pilot, and the known uplink pilot, an uplink channel to obtain an uplink channel parameter; and the downlink channel estimation unit, configured to perform, according to the hybrid The pilot and the uplink channel parameters acquire downlink channel parameters. The downlink channel estimation unit may also have different implementation manners according to different constraint conditions that the downlink pilots that are sent by the first communication device and that are sent by the communication device meet different constraints.

For example, the downlink channel estimation unit may include: a closed loop channel estimation unit and a first downlink channel parameter acquisition unit. The closed-loop channel estimation unit is configured to estimate a closed-loop channel according to the received mixed pilot and the known downlink pilot, to obtain a closed-loop channel parameter, where the first downlink channel parameter acquiring unit is configured to The closed loop channel parameter and the uplink channel parameter acquire downlink channel parameters.

The downlink channel estimation unit may further include: a hybrid pilot recovery unit and a second downlink channel parameter acquisition unit. The hybrid pilot recovery unit is configured to resume acquiring the hybrid pilot sent by the first communications device according to the uplink channel parameter and the received mixed pilot; the second downlink channel parameter acquiring unit is used by And obtaining downlink channel parameters according to the hybrid pilot, the known downlink pilot, and the known uplink pilot sent by the first communications device.

The following is an example of j3⁄4.

Embodiment 7 FIG. 9 is a schematic structural diagram of a communication device according to the embodiment. As shown in the figure, the communication device may include:

The downlink pilot coding unit 901 is configured to encode the downlink pilot that is sent to the first communication device, so that the downlink pilot satisfies the restriction condition represented by the functional formulas (11) and (17) in the second embodiment. The form of the uplink pilot in the functional formulas (11) and (17) in the time domain satisfies the restriction condition represented by the functional formula (16). The foregoing restriction condition can be: after receiving the downlink pilot, the first communication device superimposes the downlink pilot and the uplink pilot to generate a mixed pilot, and sends the mixed pilot to the communication device in this embodiment, and the implementation is performed. The communication device of the example is not affected by the superimposed downlink pilots based on the hybrid pilot's estimation of the uplink channel or the closed loop channel.

The transmitting unit 902 is configured to send the downlink pilot generated by the downlink pilot coding unit 901 to the first communication device.

The receiving unit 903 is configured to receive the mixed pilot sent by the first communications device, where the hybrid pilot is: The downlink pilot transmitted by the first communication device and the uplink pilot are superimposed. Generally, the sending unit 902 and the receiving unit 903 can be antennas of the communications device.

The uplink channel estimation unit 904 is configured to estimate an uplink channel according to the mixed pilot received by the receiving unit 903 and the known uplink pilot, to obtain an uplink channel parameter. The specific estimation process is detailed in the corresponding description in Embodiments 1 and 2.

The closed-loop channel estimation unit 905 is configured to estimate a closed-loop channel according to the mixed pilot received by the receiving unit 903 and the known downlink pilot, to obtain a closed-loop channel parameter. The specific estimation process is detailed in the corresponding description in Embodiments 1 and 2.

The downlink channel estimation unit 906 is configured to obtain the downlink channel parameter according to the closed loop channel parameter estimated by the closed loop channel estimation unit 905 and the uplink channel parameter estimated by the uplink channel estimation unit 904.

It should be noted that the communication device in this embodiment may be, but is not limited to, a base station, and the first communication device may be, but is not limited to, a terminal.

It can be seen that the communication device provided by the embodiment of the present invention can estimate the uplink channel and the closed-loop channel according to the received mixed pilot, thereby estimating the downlink channel according to the estimated uplink channel and the closed-loop channel, and acquiring the downlink channel parameter. Thereby, corresponding pre-processing (pre-coding, or pre-equalization) can be performed according to the downlink channel parameters.

Embodiment 8: FIG. 10 is a schematic structural diagram of a communication device according to the embodiment. As shown in the figure, the communication device may include:

The downlink pilot coding unit 1001 is configured to encode the downlink pilot that is sent to the first communication device, so that the downlink pilot satisfies the restriction condition represented by the functional formulas (33) and (34) in the fourth embodiment. The uplink pilot in the functional formulas (33) and (34) satisfies the constraint condition expressed by the functional formula (39).

The foregoing restriction condition can be: after receiving the downlink pilot, the first communication device superimposes the downlink pilot and the uplink pilot to generate a mixed pilot, and sends the mixed pilot to the communication device in this embodiment, The communication device of the embodiment estimates the uplink channel according to the mixed pilot, and is not subject to being superimposed The influence of the line pilot, and the signal of the hybrid pilot at the first communication device can be recovered according to the downlink pilot, thereby estimating the parameter for acquiring the uplink channel.

The transmitting unit 1002, the receiving unit 1003, and the uplink channel estimating unit 1004 are the same as the transmitting unit 1002, the receiving unit 1003, and the uplink channel estimating unit 904 in the seventh embodiment, respectively.

The hybrid pilot recovery unit 1005 is configured to resume acquiring the mixed pilot transmitted by the first communications device according to the uplink channel parameter estimated by the uplink channel estimating unit 904, and the received mixed pilot, that is, recovering and acquiring the received hybrid guide. The signal at the transmitting end (first communication device) of the mixed pilot. For details on how it works, see the related description in Examples 3 and 4.

The downlink channel estimation unit 1006 is configured to estimate, according to the hybrid pilot information that the obtained first communication device sends, the downlink pilot, and the uplink pilot, which are known by the communication device, to estimate the downlink channel, and obtain the downlink. Channel parameters. The specific working principle is detailed in the related descriptions in Embodiments 3 and 4.

It can be seen that the communication device provided by the embodiment of the present invention is capable of estimating an uplink channel according to the received mixed pilot, and recovering the received mixed pilot at the pilot transmitting end according to the estimated downlink channel (first communication) The signal of the device, according to the recovered mixed pilot, combines the known downlink pilot and the uplink pilot, and obtains downlink channel parameters, so that corresponding preprocessing (precoding, or pre-equalization) can be performed according to the downlink channel parameter. ).

It should be noted that the communication device of this embodiment may be implemented in the form of hardware or in the form of a software function module. The device of this embodiment can be sold or used as a stand-alone product or in a computer readable storage medium.

The foregoing method and communication device for obtaining channel information provided by the embodiments of the present invention are described in detail in the foregoing embodiments, which are only used to help understand the method and the principle of the embodiments of the present invention. Meanwhile, for those skilled in the art. The usual variations and substitutions made within the scope of the present invention should be included in the scope of the present invention.

Claims

Rights request

A method for obtaining channel information, comprising:

2. The method for acquiring channel information according to claim 1, wherein:

The downlink pilot includes: a downlink pilot that is sent by the at least one antenna of the second communications device to the first communications device;

The uplink pilot includes: an uplink pilot that is sent by the at least one antenna of the first communications device to the second communications device.

The method for acquiring channel information according to claim 1 or 2, wherein the downlink pilot transmitted by the at least one antenna of the second communication device to the first communication device is in the time domain. Satisfy:

* , · n = 0

∑P _dJ {t)pJ {n - t) = ,

Wherein, W is a conjugate of the downlink pilot /^(t) sent by the antenna i of the second communication device to the first communication device, where ^^-t) is the antenna j of the second communication device The downlink pilot that is sent to the first communications device, 7^ / is the delay spread length of the downlink channel, and L _ul is the delay spread length of the uplink channel, which is a real number greater than zero, and i and j are second Antenna identification of the communication device;

The form of the uplink pilot sent by the at least one antenna of the first communications device to the second communications device in the time domain satisfies:

, Wherein, is the conjugate of the uplink pilot/ _W transmitted by the antenna i of the first communication device to the second communication device, („^ is the uplink sent by the antenna j of the first communication device to the second communication device Pilot, which is the delay extension length of the uplink channel, "is a real number greater than zero, i, j are the antenna identifiers of the first communication device;

Each of the uplink pilots and the downlink pilots satisfy:

∑ P _u ^l i (t)p _d ^J _l (n - t) = 0 0 < n ≤ L _u i + L _d wherein the uplink pilot transmitted by the antenna i of the first communication device to the second communication device

/ _W conjugate, /^O-t) is the downlink pilot that is sent to the first communication device by the antenna j of the second communication device, 7^ / is the delay extension length of the downlink channel, is the uplink The delay spread length of the channel, a is a real number greater than zero, and i and j are antenna identifiers of the first communication device and the second communication device, respectively.

The method for obtaining channel information according to claim 3, wherein the step of acquiring downlink channel parameters according to the uplink channel parameter comprises:

Obtaining a closed loop channel according to a known downlink pilot and the received mixed pilot, and acquiring a closed loop channel parameter;

And obtaining downlink channel parameters according to the closed loop channel parameter and the uplink channel parameter.

Wherein, W is a downlink pilot sent by the antenna i of the second communication device to the first communication device; a conjugate of w, /^(«) is the antenna j of the second communication device Under the first communication device The downlink pilot that is sent is the delay extension length of the downlink channel, which is a real number greater than zero, and i and j are antenna identifiers of the second communication device;

Wherein, *) is the uplink pilot transmitted by the antenna i of the first communication device to the second communication device

The conjugate of 4/«, /^ («-^ is the antenna of the first communication device) transmits the uplink pilot to the second communication device, which is the delay spread length of the uplink channel, which is a real number greater than zero, i And j are antenna identifiers of the first communication device;

Each of the uplink pilots and the downlink pilots satisfy:

Wherein, a total of uplink pilots sent by the antenna i of the first communication device to the second communication device

The downlink pilot that is sent to the first communication device by the antenna j of the second communication device is a delay extension length of the uplink channel, which is a real number greater than zero, where i and j are respectively the first communication device, The antenna identification of the second communication device.

The method for obtaining channel information according to claim 5, wherein the step of acquiring downlink channel parameters according to the uplink channel parameter comprises:

Acquiring and acquiring the hybrid pilot transmitted by the first communications device according to the uplink channel parameter; acquiring, according to the recovered hybrid pilot, the known uplink pilot, and the known downlink pilot, which are obtained by the recovered Downstream channel history.

The method for acquiring channel information according to claim 1, wherein the method further comprises: the first communication device allocating a constant transmit power to the mixed pilot, and determining to allocate to each of the uplinks The ratio of the transmit power of the line pilot to the constant transmit power of the mixed pilot;

Transmitting, by the first communications device, the hybrid pilot to the second communications device according to the constant transmit power of the hybrid pilot, and the ratios, and transmitting the ratios to the second communications The device: the step of estimating an uplink channel according to the received mixed pilot and the known uplink pilot includes:

Determining, by the second communications device, the actual uplink pilot according to the ratios and the known uplink pilots;

The second communications device estimates each uplink channel according to the actual uplink pilot and the received mixed pilot.

The method for acquiring channel information according to claim 1, wherein the method further comprises: the first communication device separately assigning a constant transmission power to each uplink pilot, and causing the constant transmissions to be performed. The power is less than an upper limit of the transmit power of the predetermined mixed pilot;

Determining a transmit power of the hybrid pilot to be transmitted;

And transmitting, according to the transmit power of each uplink pilot, the transmit power of the hybrid pilot, to the second communication device;

The estimating the uplink channel according to the received mixed pilot and the known uplink pilot includes:

Determining, by the second communications device, an actual uplink pilot according to the known transmit power of each uplink pilot;

The second communication device estimates each uplink channel according to the actual uplink pilot and the received mixed pilot, respectively.

9. A communication device, characterized in that it comprises:

The communication device according to claim 9, wherein the pilot coding unit comprises: an uplink pilot coding unit, configured to encode uplink pilots sent to the second communication device, so that each The form of the uplink pilot in the time domain satisfies:

The conjugate of the uplink pilot transmitted by the second communications device, ^ («- is the uplink pilot transmitted by the antenna j of the communication device to the second communications device, which is the delay spread length of the uplink channel, which is greater than The real number of zero, i, j are the antenna identifiers of the communication device, and

∑ P _u ^l i (t)p _d ^J _l (nt) = 0 0<n≤L _u i +L _d

n

Wherein, the uplink pilot transmitted by the antenna i of the communication device to the second communication device

The conjugate of the _W / the conjugate of the _W , the downlink pilot transmitted by the antenna j of the second communication device to the communication device, 7^/ is the delay extension length of the downlink channel The delay spread length of the uplink channel is a real number greater than zero, and i and j are respectively antenna identifiers of the communication device and the second communication device; and the downlink pilots received by the receiving unit are superimposed and encoded.

The communication device according to claim 9, wherein the pilot coding unit comprises: an uplink pilot coding unit, configured to encode an uplink pilot transmitted to the second communication device, so that each uplink is uplinked The form of the pilot in the time domain satisfies:

Where * _{w is} the uplink pilot transmitted by the antenna i of the communication device to the second communication device _w Conjugation, ^(«^ is the uplink pilot transmitted by the antenna j of the communication device to the second communication device, and L _u i is the delay spread length of the uplink channel, which is a real number greater than zero, and

An uplink pilot transmitted by the antenna i of the communication device to the second communication device

a conjugate, 4) a downlink pilot that is received by the receiving unit and sent by the antenna j of the second communication device to the communication device, which is a delay extension length of the uplink channel, which is a real number greater than zero; The downlink pilot received by the receiving unit is superimposed and encoded.

12. A communication device, comprising:

a receiving unit, configured to receive a hybrid pilot sent by the first communications device, where the hybrid pilot is: a downlink pilot transmitted by the first communications device and a superposition of uplink pilots; a channel estimation unit, configured to estimate an uplink channel according to the mixed pilot and the known uplink pilot, to obtain an uplink channel history;

13. The communication device of claim 12, further comprising:

a downlink pilot coding unit, configured to encode a downlink pilot that is sent to the first communications device; a signaling device.

The communication device according to claim 12, wherein when the downlink pilot coding unit encodes the downlink pilot, the form of the downlink pilot in the time domain is satisfied:

i Wherein /^*(t) is a conjugate of the downlink pilot transmitted by the antenna i of the communication device to the first communication device,

The downlink pilot that is sent to the first communications device by the antenna j of the communication device, 7^/ is the delay spread length of the downlink channel, and is the delay spread length of the uplink channel, which is a real number greater than zero, and

∑ P _u ^l i (t)p _d ^J _l (nt) = 0 0<n≤L _u i+L _d

n

Wherein, W) is a common til y yoke of the uplink pilot transmitted by the first communication device antenna i to the communication device, ^ («-0 is the downlink guide issued by the antenna j of the communication device to the first communication device The frequency, L _dl is the delay spread length of the downlink channel, and is the delay spread length of the uplink channel, which is a real number greater than zero; the downlink channel estimation unit includes:

a closed loop channel estimation unit, configured to estimate a closed loop channel according to the received mixed pilot and the known downlink pilot, to obtain a closed loop channel parameter;

And a first downlink channel parameter obtaining unit, configured to acquire a downlink channel device according to the closed loop channel parameter and the uplink channel device.

The communication device according to claim 13, wherein when the downlink pilot coding unit encodes the downlink pilot, the form of the downlink pilot in the time domain is satisfied:

Wherein, (the conjugate of the downlink pilot sent by the antenna i of the first communication device to the communication device,

a downlink pilot that is sent to the communication device by the antenna j of the first communication device, and 7^/ is a delay extension length of the downlink channel, which is a real number greater than zero, and

Wherein the first communications device frequency antenna i ^ _W common to the uplink pilot transmitted from the communication apparatus of the present The yoke, ^ (« _-0 is the downlink pilot transmitted by the antenna j of the communication device to the first communication device, and L _dl is the delay extension length of the downlink channel, which is the delay extension length of the uplink channel, which is greater than a real number of zero; the downlink channel estimation unit includes:

a hybrid pilot recovery unit, configured to resume acquiring the mixed pilot transmitted by the first communications device according to the uplink channel parameter and the received mixed pilot;

And a second downlink channel parameter acquiring unit, configured to acquire a downlink channel parameter according to the mixed pilot, the known downlink pilot, and the known uplink pilot sent by the first communications device.