CN102447504A - Method and device for eliminating intercoupling effect at transmitter side - Google Patents

Abstract

The invention provides a method and device for eliminating an intercoupling effect at a transmitter side, which solves the problem that the system capacity is lowered arising from the intercoupling among antenna units in the prior art. A transmitter acquires a coupling matrix at the transmitter side, carries out pretreatment on a signal to be transmitted according to the coupling matrix so as to generate a decoupled signal, and then, transmits the decoupled signal to a receiver. When the transmitter also carries out a decoupling operation on an original training sequence like that on the signal to be transmitted, improvement is not needed to carry out at a receiver side; and when the transmitter transmits the original training sequence which is not decoupled, the receiver further needs to carry out backward processing of a decoupling operation on the received signal so as to reconstruct the original signal. With the adoption of the technical scheme provided by the invention, the system capacity can be increased.

Description

Method and device for eliminating mutual coupling effect at transmitter end

Technical Field

The present invention relates to a mimo wireless communication system, and more particularly, to a method and apparatus for eliminating mutual coupling effect at a transmitter.

Background

It is known that in a multiple-Input multiple-Output (Multi-Output) system, theoretically increasing the number of antennas can improve the performance of the system. However, in practical applications, the size of the antenna array is limited by space. For a fixed size antenna array, increasing the number of antennas will decrease the distance between the antenna elements. When the antenna elements are arranged very close together, the performance of the system will be greatly reduced if the mutual coupling effect between the antenna elements is not considered in advance in the system design.

The mutual coupling between the antenna elements means the interaction between the antenna elements. No solution is proposed in the prior art to eliminate the mutual coupling effect in MIMO systems.

Disclosure of Invention

In order to solve the problem that mutual coupling between antenna units in the prior art causes system capacity reduction, the invention provides a method and a device for eliminating mutual coupling effect at a transmitter end, wherein the transmitter acquires a coupling matrix at the transmitter end; preprocessing a signal to be transmitted according to the coupling matrix to generate a signal subjected to decoupling processing; the decoupled signal is then sent to a receiver. When the transmitter also performs the same decoupling operation as the signal to be transmitted on the original training sequence, the receiver does not need to perform improvement, and when the transmitter transmits the original training sequence without the coupling processing, the receiver further needs to perform the inverse processing of the decoupling operation on the received signal to recover the original signal. By adopting the technical scheme of the invention, the system capacity can be improved.

According to a first aspect of the present invention, there is provided a method for decoupling a signal to be transmitted in a transmitter of a mimo wireless communication network, the method comprising: A. acquiring a coupling matrix at a transmitter end; B. preprocessing the signal to be transmitted according to the coupling matrix to generate a signal subjected to decoupling processing; and C, sending the signal subjected to decoupling processing to a receiver.

According to a second aspect of the present invention, there is provided a method for performing decoupling inverse processing on a received signal in a receiver of a multiple-input multiple-output wireless communication network, the method comprising: a. acquiring relevant information of a coupling matrix at a transmitter end, and acquiring the coupling matrix according to the relevant information; b. acquiring a training sequence which is not subjected to coupling processing in the past from the transmitter end, and acquiring a receiving signal from the transmitter; c. estimating an equivalent channel according to the received training sequence which is not subjected to coupling processing from the transmitter end and a pre-known original training sequence, and estimating a signal which is sent by the transmitter and is subjected to decoupling processing according to the equivalent channel and the received signal; and d, carrying out decoupling inverse operation on the estimated signals subjected to decoupling processing according to the coupling matrix so as to recover the original signals to be transmitted.

According to a third aspect of the present invention, there is provided a first apparatus for decoupling a signal to be transmitted in a transmitter of a mimo wireless communication network, the apparatus comprising: a first obtaining device, configured to obtain a coupling matrix at a transmitter end; decoupling means for preprocessing the signal to be transmitted according to the coupling matrix to generate a decoupled signal; and a transmitting device for transmitting the signal subjected to decoupling processing to a receiver.

According to a fourth aspect of the present invention, there is provided a second apparatus for performing decoupling inverse processing on a received signal in a receiver of a multiple-input multiple-output wireless communication network, the second apparatus comprising: a second obtaining device, configured to obtain relevant information of a coupling matrix at a transmitter end, and obtain the coupling matrix according to the relevant information; the acquiring device is further configured to acquire a training sequence from the transmitter without being subjected to the past coupling processing, and acquire a received signal from the transmitter; estimating means, configured to estimate an equivalent channel according to the received training sequence from the transmitter without being subjected to the past coupling processing and a pre-known original training sequence, and estimate a decoupled signal sent by the transmitter according to the equivalent channel and the received signal; and a recovery device, configured to perform a decoupling inverse operation on the estimated signal subjected to decoupling processing according to the coupling matrix, so as to recover an original signal to be sent.

The scheme of the invention brings obvious advantages to the compactly arranged multi-antenna array of the MIMO system, eliminates the mutual coupling effect at the receiver end in practical application and obviously improves the system capacity.

Drawings

Other features, objects and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments thereof, which proceeds with reference to the accompanying drawings.

Fig. 1 shows a circuit network representation of an antenna array according to a specific embodiment of the present invention;

FIG. 2A illustrates a system method flow diagram in accordance with a specific embodiment of the present invention;

FIG. 2B illustrates a system method flow diagram in accordance with a specific embodiment of the present invention;

FIG. 3 shows a block diagram of an apparatus according to a specific embodiment of the present invention;

fig. 4 shows a relationship between the number of antennas and the system capacity when the channel state information is unknown at the transmitting end according to an embodiment of the present invention;

fig. 5 shows a relationship between the number of antennas and system capacity when channel state information is known at a transmitting end according to an embodiment of the present invention.

Wherein the same or similar reference numerals indicate the same or similar step features or means/modules.

Detailed Description

And (3) system model:

the system model that considers the mutual coupling effect of the transmitter and the mutual coupling effect of the receiver can be expressed as: (1)

y＝C_rHC_tx+z(1)

where x is the transmitted signal vector, C_rIs a coupling matrix at the receiver end, C_tIs the coupling matrix at the transmitter end, H is the spatial channel matrix, and z is the additive noise vector.

The antenna array at the transmitter end can be represented as a circuit network as shown in fig. 1.

From Kirchhoff's Voltage Law (KVL), it can be derived that:

$C_t=Z_L^t{(Z^t+Z_L^t)}^{-1}---\left(2\right)$

wherein, C_tA coupling matrix at the transmitter end is represented,

representing a diagonal matrix formed by equivalent load impedances of the transmitting antennas, Z^tAn impedance matrix of the transmitting antennas is represented, in which diagonal elements are inherent impedances of the respective transmitting antennas, and non-diagonal elements are mutual impedances between the transmitting antennas.

Systematic method flow

Fig. 2A and 2B each show a system method flow diagram in accordance with a specific embodiment of the present invention. Note that, in fig. 2A and 2B, steps S20-S22 are identical. Therefore, we first describe the steps S20-S22 in detail. In fig. 2A and 2B we show a transmitter 1 and a receiver 2, with the transmitter and receiver in the base station and the receiver and transmitter in the mobile station, so that the transmitter 1 can be located in the base station and the receiver 2 in the mobile station; or the transmitter 1 is located in the mobile station and the receiver 2 is located in the base station. In the following embodiments, the transmitter 1 and the receiver 2 performing transceiving operation in pairs are taken as an example for explanation, and the receiver 2 and the transmitter are not limited to being located in a specific device.

First, in step S20, the transmitter 1 acquires a coupling matrix at the transmitter 1 side.

Specifically, in one embodiment, in step S200 (not shown in the figure), the transmitter 1 side measures the inherent impedance of each transmitting antenna of the transmitter 1 side, the mutual impedance between each transmitting antenna, and the equivalent load impedance of each transmitting antenna.

Then, in step S201 (not shown in the figure), the transmitter 1 calculates a coupling matrix at the transmitter 1 end using the measured intrinsic impedance, mutual impedance and equivalent load impedance.

In the prior art, according to v ═ Z^ti, where v is the terminal voltage vector, i is the terminal current vector, Z^tRepresenting the transmission impedance matrix, deducing the coupling matrix at the 1 end of the transmitter to be represented as:

C_t＝Z^t(Z^t+Z_s)^-1

however, the above formula is erroneous in the derivation process because of Z ═ v according to the formula^ti, it will conclude that there is no fault with the termination voltage, i.e. v 0, when the circuit is open, i.e. i 0. In practice, according to kirchhoff's voltage law, when the circuit is open, the terminal voltage should be equal to the power supply, i.e., v ═ v_s. Thus, C_t＝Z^t(Z^t+Z_s)^-1Is erroneous.

In a preferred embodiment, therefore, the coupling matrix at the transmitter 1 is further modified, i.e. according to Kirchhoff's Voltage Law (KVL),

it can be derived that:

$C_t=Z_L^t{(Z^t+Z_L^t)}^{-1}---\left(3\right)$

wherein C is_tA coupling matrix at the transmitter 1 side is shown,representing a diagonal matrix formed by equivalent load impedances of the transmit antennas of the transmitter 1, Z^tAn impedance matrix of the transmitting antennas of the transmitter 1 is shown, whose diagonal elements are the inherent impedances of the respective transmitting antennas of the transmitter 1 and whose off-diagonal elements are the mutual impedances between the transmitting antennas.

Therefore, the transmitter 1 calculates the coupling matrix of the transmitter 1 according to the calculation formula of the corrected coupling matrix.

In another embodiment, if the antenna configuration at the transmitter 1 end is fixed, that is, the coupling matrix is fixed for the transmitter 1, the coupling matrix may also be provided to the transmitter 1 as a system parameter, so that the transmitter 1 does not need to calculate the coupling matrix according to each impedance, but directly obtains the coupling matrix according to the system configuration parameter.

Then, in step S21, the transmitter 1 pre-processes the signal to be transmitted according to the coupling matrix acquired in step S20 to generate a signal subjected to decoupling processing.

Specifically, the transmitter 1 utilizes the obtained coupling matrix C at the transmitter 1 end_tIs pre-multiplied by the signal vector to be transmitted

So as to obtain the signal x subjected to decoupling processing, $x=C_t^{-1}\tilde{x}.$

it is understood that y is C according to the above formula (1)_rHC_tx + z, after the signal to be transmitted is decoupled, the signal actually transmitted in the channel already offsets the influence of coupling between the transmitting antennas, thereby improving the system capacity.

Then, in step S22, the transmitter 1 transmits the signal subjected to the decoupling processing to the receiver 2.

Also included after step S20 is that transmitter 1 transmits a training sequence to receiver 2. The transmitter 1 can send the decoupled training sequence to the receiver 2, or send the training sequence without being coupled to the receiver 2, which will be described in detail below.

The first situation is as follows: hereinafter, with reference to fig. 2A, a case where the transmitter 1 does not perform the decoupling process on the original training sequence will be described.

For example, in step S23, the transmitter 1 does not perform decoupling processing on the original channel training sequence, and directly transmits the channel training sequence without being subjected to the decoupling processing to the receiver 2.

In addition, in the case that the original training sequence is not decoupled by the transmitter 1, in order to enable the receiver 2 to correctly acquire the signal that the transmitter 1 needs to transmit, in step S24, the system or the transmitter 1 needs to provide the receiver 2 with the information related to the coupling matrix, so that the receiver 2 acquires the information related to the coupling matrix from the transmitter 1 or the system.

Then, in step S25, the receiver 2 acquires the correlation information of the coupling matrix at the transmitter 1, and acquires the coupling matrix according to the correlation information.

Specifically, the receiver 2 can acquire the coupling matrix at the transmitter 1 end in any of the following ways.

The first method is as follows: for example, when the antenna configuration of the transmitter 1 end is fixed, that is, the transmitter 1 end has only one antenna configuration mode, and the antenna array does not perform antenna configuration adaptively according to different situations, the coupling matrix of the transmitter 1 may be stored in the system as configured network parameters, and then the receiver 2 acquires the coupling matrix of the transmitter 1 end according to the system configuration;

the second method comprises the following steps: when the transmitter 1 has multiple antenna configurations and the transmitter 1 can know in advance for each antenna configuration, the transmitter 1 can perform sorting and indexing on the coupling matrices corresponding to the antenna configurations, and the transmitter 1 can provide the list of the antenna coupling matrices to the receiver 2 before sending data, that is, when the transmitter 1 provides the serial number of the coupling matrix corresponding to the adopted antenna configuration as the related information of the coupling matrix to the receiver 2, the receiver 2 can obtain the corresponding coupling matrix according to the index serial number information.

The third method comprises the following steps: in addition, when the configuration of the transmitting antenna of the transmitter 1 is dynamic and the transmitter 1 cannot know all the antenna configurations of the transmitter 1 in advance, the transmitter 1 may also provide the inherent impedance, the mutual impedance and the load impedance of the transmitting antenna array obtained in real time to the receiver 2, and the receiver 2 may use the formula according to the inherent impedance, the mutual impedance and the load impedanceA coupling matrix is calculated.

The method is as follows: alternatively, when the transmitter 1 directly transmits the coupling matrix to the receiver 2, the receiver 2 may directly acquire the coupling matrix from the transmitter 1.

For the mode three receiver 2 providing the transmitter 1 with the respective impedance information, the overhead is less than for the mode four receiver 2 providing the transmitter 1 with the parameters of the coupling matrix.

Of course, those skilled in the art will understand that the above-mentioned implementations are not limited to the scenarios listed in this way, for example, for the way three, it may be applied to the case that the transmitter 1 has multiple antenna configurations and the transmitter 1 has all possible antenna configurations.

Of course, if the transmitter 1 may send different types of coupling matrix related information to the receiver 2, for example, the coupling matrix itself, the index of the coupling matrix, or the inherent impedance of each antenna in the antenna array represented by the coupling matrix, the mutual impedance between the antennas, and the load impedance of the antennas, the transmitter 1 further needs to send signaling to the receiver 2 to inform the receiver 2 of what type of coupling matrix related information is to be sent, so as to facilitate the receiver 2 to perform correct reception.

Then, in step S26, the receiver 2 acquires the training sequence from the transmitter 1 without the past coupling processing, and acquires the received signal y from the transmitter 1.

Then, in step S27, the receiver 2 estimates an equivalent channel, which can be represented as HC, from the training sequence received from the transmitter 1 without the past coupling process and the pre-known original training sequence_t. Then, the receiver 2 estimates a transmission signal based on the equivalent channel and the reception signal y. Receiver 2 based on equivalent channel HC_tAnd the estimated value of the received signal y is the decoupled signal x sent by the transmitter 1, which is denoted as

Then, in step S28, the receiver 2 further performs decoupling processing on the estimated signal subjected to decoupling processing based on the coupling matrix obtained in step S25

Performing decoupling inverse operation to recover the original signal to be transmittedThat is to say that the first and second electrodes,

the recovered data is then used by the receiver 2

Subsequent conventional processing and data detection is performed.

Case two: decoupling training sequence

Hereinafter, referring to fig. 2B, case two will be described in detail. Note that steps S20-S22 are identical to case one, and therefore, are not described herein.

In step S23', the transmitter 1 also performs decoupling processing on the original training sequence according to the coupling matrix obtained in step S20, that is, the transmitter 1 pre-multiplies the training sequence by the inverse matrix of the coupling matrix, thereby obtaining a decoupled training sequence. Then, the transmitter 1 transmits the decoupled training sequence to the receiver 2.

The above-described decoupling process is completely transparent to the receiver 2 and the receiver 2 does not need to know additional information but only needs to perform the signal processing in a conventional manner. That is, in step S24', the receiver 2 receives the decoupled training sequence and the received decoupled signal.

Then, atIn step S25', the receiver 2 estimates an equivalent channel according to the received decoupled training sequence and a pre-known original channel training sequence, where the estimated equivalent channel is H, and then estimates an original signal to be transmitted according to the estimated equivalent channel and the received decoupled signal

The receiver 2 uses the estimated signal to be transmitted

I.e. subsequent conventional data detection and the like can be performed.

While the embodiments of the present invention have been described in detail above from the perspective of a system method flow, the present invention will be further described below from the perspective of a block diagram of an apparatus.

Fig. 3 shows a block diagram of an apparatus according to a specific embodiment of the present invention. The first device 10 is located in the transmitter 1 and the second device 20 is located in the receiver 2. The first means 10 comprise first acquiring means 100, decoupling means 101, sending means 102. Therein, in one embodiment, the first acquiring apparatus 100 further comprises a measuring apparatus 1000 and a calculating apparatus 1001. The second means 20 comprise second acquiring means 200, estimating means 201 and restoring means 202.

First, the first acquiring apparatus 100 acquires a coupling matrix at the transmitter. In a preferred embodiment, the first obtaining apparatus 100 further includes a measuring apparatus 1000 and a calculating apparatus 1001, the measuring apparatus 1000 is configured to measure an inherent impedance of each transmitting antenna at the transmitter end, a mutual impedance between each transmitting antenna, and an equivalent load impedance of each transmitting antenna.

Then, the calculation means 1001 calculates a coupling matrix at the transmitter end using the measured intrinsic impedance, mutual impedance, and equivalent load impedance. Specifically, the calculation means 1001 calculates according to the formula

Calculating a transmitter-end coupling matrix, wherein C_tA coupling matrix at the transmitter end is represented,

representing a diagonal matrix formed by equivalent load impedances of the transmitting antennas, Z^tAn impedance matrix of the transmitting antennas is represented, in which diagonal elements are inherent impedances of the respective transmitting antennas, and non-diagonal elements are mutual impedances between the transmitting antennas.

Then, the decoupling device 101 performs preprocessing on the signal to be transmitted according to the coupling matrix to generate a signal subjected to decoupling processing.

Specifically, the inverse matrix obtaining device in the decoupling device 101 first obtains the inverse matrix of the coupling matrix; the signal to be transmitted is then pre-processed using the inverse of the coupling matrix to generate a decoupled signal.

Then, the transmitting apparatus 102 transmits the decoupled signal to the receiver.

The transmitting device 102 is further configured to transmit a channel training sequence.

In one embodiment, the sending apparatus 102 performs a decoupling process on the original channel training sequence according to the coupling matrix; and then the decoupled channel training sequence is sent to a receiver.

In another embodiment, the transmitting device 102 directly transmits the original channel training sequence without the past coupling process to the receiver.

Therefore, in order for the receiver to be able to correctly recover the data signal, the transmitter also needs to provide the receiver with information about the coupling matrix. The relevant information of the coupling matrix comprises the coupling matrix itself, the serial number of the coupling matrix or the inherent impedance, the mutual impedance and the load impedance of the antenna at the transmitter end.

Therefore, the second acquiring means 200 in the receiver acquires the relevant information of the coupling matrix at the transmitter end, and acquires the coupling matrix according to the relevant information.

The second obtaining means may obtain the coupling matrix in any one of the following manners:

-obtaining a coupling matrix at the transmitter end according to the system configuration;

-receiving a coupling matrix from a transmitter;

-when the relevant information comprises a sequence number of the coupling matrix, obtaining the coupling matrix at the transmitter end according to the obtained sequence number;

-when the relevant information comprises the intrinsic impedance, the mutual impedance and the load impedance of the transmit antenna array, calculating a coupling matrix from the intrinsic impedance, the mutual impedance and the load impedance.

Then, the second acquiring means 200 is further configured to acquire the training sequence without the past coupling processing from the transmitter end, and acquire the received signal from the transmitter;

then, the estimation device 201 estimates an equivalent channel according to the received training sequence from the transmitter without the past coupling processing and the pre-known original training sequence, and estimates a decoupled signal sent by the transmitter according to the equivalent channel and the received signal.

Then, the recovery device 202 performs a decoupling inverse operation on the estimated signal subjected to decoupling processing according to the coupling matrix to recover the original signal to be transmitted.

In another embodiment, if the channel training sequence transmitted by the transmitting device 102 is decoupled, the receiver does not need to make any modification at this time, and the receiver can recover the required signal vector after performing conventional channel estimation and the like.

Simulation result

In order to study the mutual coupling effect at the transmitter end, we take a multiple-Input Single-Output (MISO) system as an example below, and it is understood by those skilled in the art that the present invention is not only applicable to a MISO system, but also applicable to a MIMO system, and the simulated MISO system has M transmit antennas and 1 receive antenna, so that the channel model represented by formula (1) can be simplified to formula (3) below:

y＝hC_tx+z (3)

where z is additive gaussian noise, obeying a complex normal distribution, z ∈ CN (0, 1), the mean of z is 0, the variance is 1, h can be expressed as:

<math> <mrow> <mi>h</mi> <mo>=</mo> <msub> <mi>h</mi> <mi>w</mi> </msub> <msup> <mrow> <mo>(</mo> <msubsup> <mi>&Psi;</mi> <mi>t</mi> <mrow> <mn>1</mn> <mo>/</mo> <mn>2</mn> </mrow> </msubsup> <mo>)</mo> </mrow> <mi>H</mi> </msup> </mrow> </math>

wherein h is_wThe elements of (1) are independent and identically distributed complex symmetrical Gaussian random variables, and obey normal distribution CN (0, 1), psi_tRepresenting a transmission spatial correlation matrix

Based on the 'single-ring' principle proposed by Jakes, and using the spatial correlation model given in formula (1), Ψ_tEach element in (a) may be represented as:

Ψ_t，ij＝J₀(2πd_ij/λ)，i，j＝1，2，...，M，

wherein, λ represents the wavelength of the light,J₀(. 0) is a Bessel function of order 0, which is the distance between the ith and jth transmit antennas.

The antenna array at the transmitter end is assumed to consist of identical dipole antennas of 0.5 λ length and 0.025 λ radius, side by side in a straight line. The antenna impedance is the same, i.e.:

$Z_{11}^t=Z_{22}^t=...=Z_{\mathrm{MM}}^t.$

in the following, we use

Representing the antenna impedance. Transmission impedance matrix Z^tThe inherent impedance of the antenna and the mutual impedance between the antennas in (1) are calculated according to the formula given below:

v_0，j＝v_s，j，j＝1，2，...，M

to reduce power loss, the load impedance is chosen to be the complex conjugate of the antenna's intrinsic impedance, i.e., $Z_L={Z_{\mathrm{nn}}^t}^{*}.$

suppose that the power radiated into space is limited to P_tAnd therefore, the first and second electrodes are,

||C_tx||²≤P_t。

here, the limiting condition is a radiation power limiting condition rather than a power amplification output power limiting condition, because the power amplification output power limiting condition does not take into account interference and electromagnetic radiation, and the radiation power limiting takes into account interference and electromagnetic radiation, and therefore, the use of the radiation power limiting as the limiting condition of the system is more appropriate than the use of the power amplifier output power limiting condition.

By adopting the mutual coupling elimination scheme provided by the invention, at the transmitter end, the inverse matrix of the coupling matrix at the transmitter end and the signal vector to be transmittedMultiplication:

$x=C_t^{-1}\tilde{x}$

wherein, <math> <mrow> <msup> <mrow> <mo>|</mo> <mo>|</mo> <mover> <mi>x</mi> <mo>~</mo> </mover> <mo>|</mo> <mo>|</mo> </mrow> <mn>2</mn> </msup> <mo>&le;</mo> <msub> <mi>P</mi> <mi>t</mi> </msub> <mo>.</mo> </mrow> </math>

the method proposed by the invention for case a: the Transmitter 1 knows the Channel State Information (Channel State Information) at the Transmitter, i.e. has CSIT; and case B: the transmitter 1 side has unknown channel state information, i.e. MIMO system without CSIT is applicable. Below, we will give simulation results for the two scenarios described above:

case a: MIMO system without CSIT

By adopting the mutual coupling elimination processing, when the transmitter end does not know CSI, the signal vector to be transmitted

It is assumed that:

$E\left(\tilde{x}{\tilde{x}}^H\right)=\frac{P_t}{M}I.$

the system capacity is:

$C_{\mathrm{MCC},\mathrm{NCSIT}}={\log }_2(1+\frac{P_t}{M}{\left|\right|h\left|\right|}^2).$

if the MIMO system adjusts its power amplifier output power according to the radiated power limit, but does not consider the mutual coupling effect,

$E\left\{{\mathrm{xx}}^H\right\}=\frac{P_t}{\mathrm{tr}\left(C_t{C}_t^H\right)}I.$

thus, the channel capacity of the system is:

$C_{\mathrm{NMCC},\mathrm{NCSIT}}={\log }_2(1+\frac{P_t}{\mathrm{tr}\left(C_t{C}_t^H\right)}{\left|\right|{\mathrm{hC}}_t\left|\right|}^2).$

let C_{f，MCC，NCSIT}，C_{L，MCC，NCSIT}And C_{L，NMCC，NCSIT}Transmit antenna array with sparse arrangement when CSI is unknown at the transmitter end, respectivelyColumns and systems employing mutual coupling effect cancellation, transmit antenna arrays having fixed lengths and systems employing mutual coupling effect cancellation, and transmit antenna arrays having fixed lengths and systems not employing mutual coupling effect cancellation. Wherein f in the first subscript of the symbol represents far spaced, sparsely arranged, L in the first subscript represents a fixed Length (fix Length), that is, the total Length of the antenna array in line is fixed, and when the number of elements in the antenna array is increased, the spacing between adjacent antenna elements is reduced. The MCC in the second subscript indicates a mutual coupling cancellation indicating a scheme in which mutual coupling cancellation is used, and the NMCC in the second subscript indicates a non-mutual coupling cancellation indicating a scheme in which mutual coupling cancellation is not used. The third subscript NCSIT represents the unknown CSI of the transmitter 1.

Fig. 4 shows the effect of using mutual coupling cancellation operation on using a compact antenna array for a MIMO system when the channel state information is unknown at the transmitter 1, where e (c) represents the expected value of the channel capacity. As can be seen from fig. 4, when the mutual coupling effect is not considered, increasing the number of transmitting antennas after a critical value brings about a serious system performance degradation; and after applying the process of mutual coupling cancellation proposed by the present invention, the system performance C_{L，MCC，NCSIT}Very close to the upper limit C_{f，MCC，NCSIT}The upper limit C_{f，MCC，NCSIT}A sparse antenna array arrangement without length limitation corresponding to the transmitter 1 side. At C_{L，MCC，NCSIT}And C_{f，MCC，NCSIT}The slight gap between them is due to the channel capacity loss caused by channel correlation.

Case B: the MIMO system has a CSIT

When the transmitter 1 end knows the CSI, the mutual coupling elimination processing is adopted, and the signal vector to be transmittedComprises the following steps:

$\tilde{x}=\frac{\sqrt{P_t}{h}^H}{\left|\right|h\left|\right|}\widetilde{\stackrel{~}{x}}$

wherein,

is a transmission signal to be precoded, and

thus, the system capacity is:

C_MCC，CSIT＝log₂(1+P_t||h||²).

if the MIMO system will hC_tAs equivalent channel, and adjusting its power amplifier output power according to the radiation power limitation, then

$x=\frac{\sqrt{P_t}{C}_t^H{h}^H}{\left|\right|h{C}_t{C}_t^H\left|\right|}\widetilde{\stackrel{~}{x}}.$

Thus, the capacity of the system is:

$C_{\mathrm{NMCC},\mathrm{CSIT}}={\log }_2(1+P_t\frac{{\left|h{C}_t{C}_t^H{h}^H\right|}^2}{{\left|\right|{\mathrm{hC}}_t{C}_t^H\left|\right|}^2}).$

let C_{f，MCC，CSIT}，C_{L，MCC，CSIT}And C_{L，NMCC，CSIT}Respectively, a system with sparsely arranged transmit antenna arrays and employing mutual coupling effect cancellation, when CSI is known at the transmitter 1, a method and a system for implementing the sameFixed length transmit antenna arrays and systems employing mutual coupling effect cancellation, and systems having fixed length transmit antenna arrays and not employing mutual coupling effect cancellation. Wherein, f in the first subscript of the symbol represents far spaced, sparsely arranged, L in the first subscript represents a fixed length, that is, the total length of the antenna array in line is fixed, and when the number of the elements in the antenna array is increased, the distance between the adjacent antenna elements is reduced. The MCC in the second subscript indicates a mutual coupling cancellation indicating a scheme in which mutual coupling cancellation is used, and the NMCC in the second subscript indicates a non-mutual coupling cancellation indicating a scheme in which mutual coupling cancellation is not used. The third subscript CSIT indicates the known CSI at the transmitter 1.

Fig. 5 shows a MIMO system with a compact transmit antenna array employing a process of canceling mutual coupling effects when CSIT is known. Where e (c) represents the expected value of the channel capacity. If the mutual coupling effect is not considered, the system performance cannot be obviously improved by increasing the number of transmitting antennas after a critical value; and after the processing of eliminating the mutual coupling effect proposed by the invention is adopted, the system performance C_{L，MCC，CSIT}Very close to the upper limit C_{f，MCC，CSIT}The upper limit C_{f，MCC，CSIT}The upper system capacity value C corresponds to a sparse antenna array arrangement at the transmitter end without length limitation_{f，MCC，CSIT}Which increases significantly as the number of transmit antennas increases. At C_{L，MCC，NCSIT}And C_{f，MCC，NCSIT}The slight gap between them is due to the channel capacity loss caused by channel correlation.

While embodiments of the present invention have been described above, the present invention is not limited to a particular system, device, and protocol, and various modifications and changes may be made by those skilled in the art within the scope of the appended claims.

Other variations to the disclosed embodiments can be understood and effected by those skilled in the art from a study of the specification, the disclosure, the drawings, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the word "a" or "an" does not exclude a plurality. In practical applications of the invention, one element may perform the functions of several technical features recited in the claims. Any reference signs in the claims shall not be construed as limiting the scope.

Claims (15)

1. A method in a transmitter of a multiple-input multiple-output wireless communication network for decoupling processing of a signal to be transmitted, the method comprising:

A. acquiring a coupling matrix at a transmitter end;

B. preprocessing the signal to be transmitted according to the coupling matrix to generate a signal subjected to decoupling processing; and

C. and sending the signal subjected to decoupling processing to a receiver.

2. The method of claim 1, wherein step a further comprises:

A1. measuring the inherent impedance of each transmitting antenna at the transmitter end, the mutual impedance among the transmitting antennas and the equivalent load impedance of each transmitting antenna;

A2. calculating a coupling matrix at the transmitter end using the measured intrinsic impedance, the mutual impedance, and the equivalent load impedance.

3. The method of claim 2, wherein said step a2 further comprises, according to a formula

Calculating said transmitter-side coupling matrix, wherein C_tA coupling matrix representing the ends of said transmitter,

representing a diagonal matrix formed by said equivalent load impedances of said transmitting antennas, Z^tAn impedance matrix representing the transmitting antennas, diagonal elements of which are the inherent impedances of the respective transmitting antennas, and off-diagonal elements of which are the mutual impedances between the transmitting antennas.

4. The method of any one of claims 1 to 3, wherein step B further comprises:

B1. acquiring an inverse matrix of the coupling matrix; and

B2. and preprocessing the signal to be transmitted by utilizing an inverse matrix of the coupling matrix to generate the decoupled signal.

5. The method of any of claims 1-4, wherein step A is further followed by:

-decoupling the original channel training sequence according to the coupling matrix;

-transmitting the decoupled channel training sequence to the receiver.

6. The method of any of claims 1-4, wherein step A is further followed by:

-sending the original channel training sequence to the receiver without decoupling.

7. The method of any one of claims 1-6, further comprising after step A:

-providing information about the coupling matrix to the receiver.

8. The method of claim 7, wherein the information about the coupling matrix comprises the coupling matrix, a sequence number of the coupling matrix, or an intrinsic impedance, a mutual impedance, and a load impedance of a transmitter-side antenna.

9. A method for decoupled inverse processing of a received signal in a receiver of a multiple-input multiple-output wireless communication network, the method comprising:

a. acquiring relevant information of a coupling matrix at a transmitter end, and acquiring the coupling matrix according to the relevant information;

b. acquiring a training sequence which is not subjected to coupling processing in the past from the transmitter end, and acquiring a receiving signal from the transmitter;

c. estimating an equivalent channel according to the received training sequence which is not subjected to coupling processing from the transmitter end and a pre-known original training sequence, and estimating a signal which is sent by the transmitter and is subjected to decoupling processing according to the equivalent channel and the received signal; and

d. and performing decoupling inverse operation on the estimated signals subjected to decoupling processing according to the coupling matrix so as to recover the original signals to be transmitted.

10. The method of claim 9, wherein the step a comprises any one of:

-obtaining a coupling matrix at the transmitter end according to a system configuration;

-receiving a coupling matrix from the transmitter;

-when the relevant information comprises a sequence number of the coupling matrix, acquiring the coupling matrix at the transmitter according to the acquired sequence number;

-calculating the coupling matrix from the intrinsic impedance, the transimpedance and the load impedance when the correlation information comprises the intrinsic impedance, the transimpedance and the load impedance of the transmit antenna array.

11. A first apparatus for decoupling a signal to be transmitted in a transmitter of a multiple-input multiple-output wireless communication network, the apparatus comprising:

a first obtaining device, configured to obtain a coupling matrix at a transmitter end;

decoupling means for preprocessing the signal to be transmitted according to the coupling matrix to generate a decoupled signal; and

and the sending device is used for sending the signal subjected to decoupling processing to a receiver.

12. The first apparatus of claim 11, wherein the first obtaining means further comprises:

the measuring device is used for measuring the inherent impedance of each transmitting antenna at the transmitter end, the mutual impedance among the transmitting antennas and the equivalent load impedance of each transmitting antenna;

and the calculating device is used for calculating a coupling matrix at the transmitter end by using the measured inherent impedance, the measured mutual impedance and the measured equivalent load impedance.

13. The first apparatus of claim 12, wherein the computing apparatus is further configured to, according to a formula

Calculating said transmitter-side coupling matrix, wherein C_tA coupling matrix representing the ends of said transmitter,

representing a diagonal matrix formed by said equivalent load impedances of said transmitting antennas, Z^tAn impedance matrix representing the transmitting antennas, diagonal elements of which are the inherent impedances of the respective transmitting antennas, and off-diagonal elements of which are the mutual impedances between the transmitting antennas.

14. The first device of any of claims 11 to 13, wherein the decoupling device further comprises:

an inverse matrix obtaining device for obtaining an inverse matrix of the coupling matrix; and

the decoupling device is further configured to pre-process the signal to be transmitted by using an inverse matrix of the coupling matrix to generate the decoupled signal.

15. A second apparatus for decoupling inverse processing of a received signal in a receiver of a multiple-input multiple-output wireless communication network, the second apparatus comprising:

a second obtaining device, configured to obtain relevant information of a coupling matrix at a transmitter end, and obtain the coupling matrix according to the relevant information;

the acquiring device is further configured to acquire a training sequence from the transmitter without being subjected to the past coupling processing, and acquire a received signal from the transmitter;

estimating means, configured to estimate an equivalent channel according to the received training sequence from the transmitter without being subjected to the past coupling processing and a pre-known original training sequence, and estimate a decoupled signal sent by the transmitter according to the equivalent channel and the received signal; and

and the recovery device is used for carrying out decoupling inverse operation on the estimated signals subjected to decoupling processing according to the coupling matrix so as to recover the original signals to be sent.

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