CN107547119B - Transmission mode self-adaption method and device based on correlation between channels - Google Patents

Abstract

The embodiment of the invention provides a transmission mode self-adaption method and a device based on correlation between channels, wherein the method comprises the following steps: performing channel estimation on a current frame of a receiving end to obtain a channel matrix; performing singular value decomposition on the channel matrix to obtain a diagonal matrix, wherein diagonal elements in the diagonal matrix are singular values of the channel matrix; calculating the ratio of the maximum singular value to the minimum singular value in all the singular values, and taking the ratio as the condition number of the current frame; judging whether the condition number is larger than a preset condition number threshold value or not to obtain a judgment result, determining the channel type of the current frame corresponding to the judgment result, and determining the transmission mode of the current frame according to the channel type, wherein the channel type comprises a line-of-sight (LOS) channel or a non-NLOS channel. By applying the embodiment of the invention, the throughput performance of the link can be improved.

Description

A method and device for adaptive transmission mode based on inter-channel correlation

technical field

The present invention relates to the field of communication technologies, and in particular, to a method and device for adaptive transmission mode based on inter-channel correlation.

Background technique

In the indoor broadband mobile communication system, the communication link between the base station and the mobile station is accomplished through the alternation between LOS (Line of Sight, line of sight) and NLOS (Non Line of Sight, non-line of sight). It means that in wireless communication, the transmitting and receiving antennas must be able to see directly at two points, and there is no obstruction in the middle. NLOS means that in wireless communication, the line of sight of two points that need to be communicated is blocked and cannot see each other. In order to meet the increasing demand for high-speed data transmission, the data transmission of the LOS communication link and the NLOS communication link can be realized by configuring multiple antennas between the base station and the mobile station, thus forming a MIMO (Multiple Input Multiple Output, Multiple-input multiple-output) systems, where spatial diversity and spatial multiplexing are the main techniques used in MIMO systems.

In the existing transmission mode based on inter-channel correlation, the transmission mode of spatial multiplexing is adopted for both the LOS communication link and the NLOS communication link between the base station and the mobile station. Specifically, first use multiple antennas at the receiving end and the transmitting end, so that multiple antennas can generate multipath components in the process of spatial propagation, and then make full use of the multipath components in the spatial propagation, and use the multipath components in the same frequency band The resulting multiple data channels (MIMO sub-channels) transmit the signal so that the channel capacity increases linearly with the number of antennas. This channel capacity increase does not need to occupy additional bandwidth, nor does it need to consume additional transmit power, so it is a very effective means to increase channel and system capacity.

However, for indoor scenarios, especially when small base stations are sparsely distributed, the communication link between the base station and the mobile station will face more frequent alternations between LOS and NLOS. For link NLOS, spatial multiplexing is used. can bring higher throughput performance, but for LOS whose link quality is better than NLOS, using the transmission mode of spatial multiplexing will lead to a decrease in the throughput performance of the link.

SUMMARY OF THE INVENTION

The purpose of the embodiments of the present invention is to provide a transmission mode adaptation method and device based on inter-channel correlation, so as to improve the throughput performance of the link. The specific technical solutions are as follows:

The embodiment of the present invention discloses a transmission mode adaptation method based on inter-channel correlation, the method includes:

Perform channel estimation on the current frame of the receiver to obtain a channel matrix;

Perform singular value decomposition on the channel matrix to obtain a diagonal matrix, and the diagonal elements in the diagonal matrix are the singular values of the channel matrix;

Calculate the ratio of the largest singular value and the smallest singular value among all singular values, and use the ratio as the condition number of the current frame, and the condition number represents the magnitude of the correlation between the channels;

Judging whether the condition number is greater than a preset condition number threshold, obtaining a judgment result, determining the channel type of the current frame corresponding to the judgment result, and determining the transmission mode of the current frame according to the channel type, Wherein, the channel type includes a line-of-sight LOS channel or a non-line-of-sight NLOS channel.

Optionally, performing singular value decomposition on the channel matrix to obtain a diagonal matrix, where the diagonal elements in the diagonal matrix represent singular values of the channel matrix, including:

According to the formula

Perform singular value decomposition on the channel matrix to obtain a diagonal matrix, where m×m, m×n, and n×n respectively represent the rank of the matrix, m represents the number of antennas at the transmitting end, n represents the number of antennas at the receiving end, and H represents the number of antennas at the receiving end. For the channel matrix, U represents a left unitary _matrix , U1, . . . , _Um , . , _S1 , . , . . . , V _n×n are the elements of the left unitary matrix, respectively.

Optionally, judging whether the condition number is greater than a preset condition number threshold, obtaining a judgment result, determining the channel type of the current frame corresponding to the judgment result, and determining the channel type according to the channel type. The transmission mode of the current frame, including:

Judging whether the condition number is greater than a preset condition number threshold, and obtaining a judgment result;

If the judgment result is that the condition number is greater than the preset condition number threshold value, determine that the channel type of the current frame corresponding to the judgment result is the LOS channel, and use the LOS channel for the LOS channel. The transmission mode of space diversity;

If the judgment result is that the condition number is less than or equal to the preset condition number threshold, determine that the channel type of the current frame corresponding to the judgment result is the NLOS channel, and determine the NLOS channel. The channel adopts the transmission mode of spatial multiplexing.

Optionally, after determining the channel type of the current frame corresponding to the judgment result, and determining the transmission mode of the current frame according to the channel type, the method further includes:

The transmission mode of the current frame is taken as a transmission mode corresponding to a frame in a preset period adjacent to the current frame.

An embodiment of the present invention discloses a transmission mode adaptation device based on inter-channel correlation, the device comprising:

an estimation module, which is used to perform channel estimation on the current frame of the receiving end to obtain a channel matrix;

a decomposition module, configured to perform singular value decomposition on the channel matrix to obtain a diagonal matrix, where the diagonal elements in the diagonal matrix are singular values of the channel matrix;

a calculation module, configured to calculate the ratio of the largest singular value to the smallest singular value among all singular values, and use the ratio as the condition number of the current frame, and the condition number represents the size of the correlation between the channels;

A judgment module, configured to judge whether the condition number is greater than a preset condition number threshold, obtain a judgment result, determine the channel type of the current frame corresponding to the judgment result, and determine the current frame according to the channel type The transmission mode of the frame, wherein the channel type includes a line-of-sight LOS channel or a non-line-of-sight NLOS channel.

Optionally, the decomposition module is specifically used for:

According to the formula

Perform singular value decomposition on the channel matrix to obtain a diagonal matrix, where m×m, m×n, and n×n respectively represent the rank of the matrix, m represents the number of antennas at the transmitting end, n represents the number of antennas at the receiving end, and H represents the number of antennas at the receiving end. For the channel matrix, U represents a left unitary _matrix , U1, . . . , _Um , . , _S1 , . , . . . , V _n×n are the elements of the left unitary matrix, respectively.

The judging module includes:

a judging submodule for judging whether the condition number is greater than a preset condition number threshold, and obtaining a judgment result;

A first determination submodule, configured to determine that the channel type of the current frame corresponding to the judgment result is the LOS channel if the judgment result is that the condition number is greater than the preset condition number threshold , and adopt the transmission mode of space diversity to the LOS channel;

A second determination submodule, configured to determine that the channel type of the current frame corresponding to the determination result is the channel type if the condition number is less than or equal to the preset condition number threshold as the determination result NLOS channel, and a spatial multiplexing transmission mode is adopted for the NLOS channel.

The device also includes:

A determining module, configured to use the transmission mode of the current frame as the transmission mode corresponding to the frame in a preset period adjacent to the current frame.

The embodiment of the present invention also discloses an electronic device, comprising a processor, a communication interface, a memory and a communication bus, wherein the processor, the communication interface and the memory communicate with each other through the communication bus;

the memory for storing computer programs;

The processor is configured to implement the steps of the above-mentioned method for adapting a transmission mode based on inter-channel correlation when executing the program stored in the memory.

In yet another aspect of the implementation of the present invention, a computer-readable storage medium is also disclosed, wherein instructions are stored in the computer-readable storage medium, and when the computer-readable storage medium is run on a computer, the computer is made to execute any one of the above-mentioned one A transmission mode adaptation method based on inter-channel correlation.

A method and device for adaptive transmission mode based on inter-channel correlation provided by the embodiments of the present invention, firstly perform channel estimation on the current frame of the receiving end to obtain a channel matrix; then perform singular value decomposition on the channel matrix to obtain a diagonal matrix; Then calculate the ratio of the largest singular value and the smallest singular value among all singular values, and use the ratio as the condition number of the current frame; finally judge whether the condition number is greater than the preset condition number threshold, obtain the judgment result, and determine the current corresponding to the judgment result. The channel type of the frame, and the transmission mode of the current frame is determined according to the channel type. In this way, the condition number is used as the correlation index between the channels. By judging the size of the condition number of the current frame and the preset condition number threshold, and according to the judgment result, it is determined whether the current frame is the LOS channel type or the NLOS channel type, and finally according to the The channel type determines the transmission mode of the current frame. In this way, different transmission modes are used for different channel types, so that both the LOS channel type and the NLOS channel type can adopt the transmission mode that improves the throughput performance of the link, thereby greatly improving the throughput performance of the link. Of course, it is not necessary for any product or method to implement the present invention to simultaneously achieve all of the advantages described above.

Description of drawings

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the following briefly introduces the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained according to these drawings without creative efforts.

FIG. 1 is a schematic flowchart of a method for adapting a transmission mode based on inter-channel correlation according to an embodiment of the present invention;

2 is a topology diagram of an inter-channel static scene provided by an embodiment of the present invention;

3 is a topology diagram of an inter-channel dynamic scenario provided by an embodiment of the present invention;

4 is a cumulative distribution diagram of line-of-sight and non-line-of-sight channel condition numbers provided by an embodiment of the present invention;

FIG. 5 is another schematic flowchart of a transmission mode adaptation method based on inter-channel correlation provided by an embodiment of the present invention;

6 is a simulation result diagram of a transmission mode based on inter-channel correlation provided by an embodiment of the present invention;

FIG. 7 is a schematic structural diagram of a transmission mode adaptation apparatus based on inter-channel correlation according to an embodiment of the present invention;

FIG. 8 is a schematic structural diagram of an electronic device according to an embodiment of the present invention.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

In recent years, the focus of indoor broadband mobile communication systems is to improve the transmission rate and capacity in hotspot and indoor coverage scenarios. Compared with other scenarios, indoor scenarios have larger bandwidth and lower mobile station moving speeds, so indoor broadband mobile communication It has better indoor channel environment and higher peak throughput, which greatly improves its transmission rate. However, for indoor scenarios, especially when small base stations are sparsely distributed, the communication link between the base station and the mobile station will face more frequent alternations between LOS and NLOS, which is required in indoor scenarios compared to outdoor macro base station scenarios. new topics to consider. Based on this, the present invention provides a transmission mode adaptation method based on inter-channel correlation, and the specific process is as follows:

Referring to FIG. 1, FIG. 1 is a schematic flowchart of a transmission mode adaptation method based on inter-channel correlation provided by an embodiment of the present invention, including the following steps:

S101: Perform channel estimation on the current frame of the receiving end to obtain a channel matrix.

Specifically, because the wireless channel has great randomness, the amplitude, phase and frequency of the received signal are distorted, which brings great challenges to the design of the receiver. Meanwhile, in the wireless communication system, diversity, channel equalization, best matching receiver design, maximum likelihood detection, coherent demodulation and adaptive link technology all need the support of good channel estimation. Therefore, the channel estimator is a very important part of the receiver, and channel estimation has also become a very important subject in the field of wireless communication.

For each frame in the link, the receiver can obtain the channel matrix through channel estimation. Channel estimation is the process of estimating the model parameters of an assumed channel model from the received data. If the channel is linear, then channel estimation is the estimation of the system impulse response. It should be emphasized that channel estimation is a mathematical representation of the effect of the channel on the input signal, and a "good" channel estimation is an estimation algorithm that minimizes some estimation error. Commonly used channel estimation criteria in wireless communication include Minimum Mean Square Error (MMSE) and Maximum Likelihood (ML).

S102. Perform singular value decomposition on the channel matrix to obtain a diagonal matrix, where the diagonal elements in the diagonal matrix are singular values of the channel matrix.

Specifically, since the concept of the condition number comes from the singular value (SDV) decomposition of the channel, when the condition number is used as the index of the channel state information, the channel matrix needs to be decomposed into singular value first. By performing singular value decomposition on the channel matrix, a left unitary matrix, a diagonal matrix and a right unitary matrix are obtained, wherein the elements on the diagonal in the diagonal matrix are the singular values of the channel matrix.

S103: Calculate the ratio of the largest singular value to the smallest singular value among all singular values, and use the ratio as a condition number of the current frame, where the condition number represents the magnitude of the correlation between channels.

Specifically, according to the formula

Calculate the ratio of the largest singular value and the smallest singular value among all singular values, and use the ratio as the condition number (CN, ConditionNumber) of the current frame. Since in the diagonal matrix, the size of the singular value measures the "health status" of the "degree of freedom" supported by the channel. The closer the value is to 0, the closer the degree of freedom is to the edge of "degeneration". For example, in the case of two singular values in the "optimal channel", the two singular values are the same size, which means that the channel supports both degrees of freedom well without any difference, which is an ideal situation; and This is different when there are two singular values in the "random channel", one with a larger value and one with a smaller value. In other words, this channel is more than enough to support 1 degree of freedom, if you want to support 2, the effect is not so good. Therefore, the condition number is a very valuable parameter. The condition number is defined as the result of the ratio of the largest singular value to the smallest singular value in the "diagonal matrix S". The transmission conditions of the channels (degrees of freedom) are very average; the larger the ratio, the greater the difference and unbalanced transmission conditions of each sub-channel. Here, the condition number represents the magnitude of the correlation between the channels, that is, the magnitude of the degrees of freedom of each parallel sub-channel between the channels.

S104, determine whether the condition number is greater than a preset condition number threshold, obtain a determination result, determine the channel type of the current frame corresponding to the determination result, and determine the transmission of the current frame according to the channel type mode, wherein the channel type includes a line-of-sight LOS channel or a non-line-of-sight NLOS channel.

Determine the judgment threshold T of strong and weak channel correlation, and use this threshold to determine the best transmission mode of the current link. In the specific operation, singular value decomposition should be performed on the channel matrices of LOS and NLOS in the actual indoor system, the condition number should be calculated, and the received signal close to the middle of all received signals should be selected according to the distribution of received signals in the indoor scene to the base station. distance as a judgment value. Here, the preset condition number threshold value may be set according to the actual situation. For example, for the topology diagram of the inter-channel static scene in FIG. 2 , T=15 may be selected as the determination threshold. When the condition number threshold (denoted as CNT) is determined, compare the condition number of the current frame (denoted as CN) and CNT. When CN is greater than CNT, it indicates that the channel has strong correlation, and it can be judged as the LOS channel environment, that is, the current The frame should adopt the transmission mode of spatial diversity. On the contrary, it shows that the correlation of the channel is weak, and it can be judged as the NLOS channel environment, that is, the current frame should adopt the transmission mode of spatial multiplexing. Such an adaptive result can deal with the problem of poor throughput performance caused by switching between LOS and NLOS environments in mobile scenarios.

It can be seen that, the method for adaptive transmission mode based on inter-channel correlation provided by the embodiment of the present invention first performs channel estimation on the current frame of the receiving end to obtain a channel matrix; then performs singular value decomposition on the channel matrix to obtain a diagonal matrix; then calculate the ratio of the largest singular value and the smallest singular value among all singular values, and use the ratio as the condition number of the current frame; finally judge whether the condition number is greater than the preset condition number threshold value, and obtain the judgment result, which corresponds to the judgment result. The channel type of the current frame, and the transmission mode of the current frame is determined according to the channel type. In this way, the condition number is used as the correlation index between the channels. By judging the size of the condition number of the current frame and the preset condition number threshold, and according to the judgment result, it is determined whether the current frame is the LOS channel type or the NLOS channel type, and finally according to the The channel type determines the transmission mode of the current frame. In this way, different transmission modes are used for different channel types, so that both the LOS channel type and the NLOS channel type can adopt the transmission mode that improves the throughput performance of the link, thereby greatly improving the throughput performance of the link.

In the previous research on transmission mode adaptation, a common transmission mode adaptation method is based on channel quality, but for LOS with link quality better than NLOS, due to the strong correlation between antennas, It is not suitable for the transmission mode using TM3 spatial multiplexing. Therefore, for indoor scenarios where LOS and NLOS frequently alternate, the transmission mode adaptation process should be designed in combination with specific channel characteristics. The indoor scene based on provided by the present invention is introduced through FIG. 2 and FIG. 3 .

FIG. 2 is a topology diagram of an inter-channel static scene according to an embodiment of the present invention. The topology of the static scene shown in Figure 2 is that there are 6 independent rooms on each side of the hall, and the area of each room is 6m×6m. There are two large rooms in the center of the hall, occupying a proportion of 8m x 8m. The thickness of the line in the figure represents the thickness of the wall, the thick line represents the thicker wall, and the thin line represents the thinner wall. The base station is deployed in the center of the hall for signal transmission (Tx), and three are located in the test point in the figure. Representing the static detection point UE, the UE is the receiver (Rx), and the straight-line distance from Tx is 3m, respectively. 15m, 24m. Obviously, the propagation mode of the signal between Tx and Rx at a distance of 3m is LOS, and the test point at Rx is called "good point", and the propagation mode of 15m and 24m is NLOS, and the thickness of the penetrated wall is different, respectively. Call the test points at Rx "middle point" and "handicap".

FIG. 3 is a topology diagram of a dynamic scene between channels provided by an embodiment of the present invention. In the topology diagram of the dynamic scene shown in FIG. 3, there are also 6 independent rooms on both sides of the hall, and the area of each room is 6 m ×6m. There are two large rooms in the center of the hall, occupying a proportion of 8m x 8m. The thickness of the line in the figure represents the thickness of the wall, the thick line represents the thicker wall, and the thin line represents the thinner wall. In Fig. 2, · at A, B, C, D, E, F, G, H, I indicates the detection point in the path, between A, B, C, D, E, F, G, H, I The straight line represents the movement path, and the user's movement route is X->A->B->C->D->E->D->C->B->F->G->H->I. The movement path from X to A is used to complete the initialization and testing of the channel environment, and will not be included in the performance simulation. It can be observed in the figure that A->B->C and C->B->F are LOS transmissions, D->E->D and G->H->I are NLOS transmissions (penetrating a block of thin wall and two thin walls). C->D, D->C and F->G are LOS to NLOS transition states. In addition, it should be noted that the speed of the UE (static detection point) is 3km/h, and the total length of the route is 32m, so the total duration of the route is 38.4s.

From the topology diagrams of static and dynamic scenarios between channels provided in Figures 2 and 3, it can be seen that LOS and NLOS frequently alternate in indoor scenarios. Therefore, it is necessary to adapt the transmission mode in combination with specific channel characteristics.

In the embodiment of the present invention, using the channel singular value to describe the channel correlation characteristic is based on the relationship between the MIMO channel capacity and the channel singular value. Here, the relationship between the channel capacity and the channel singular value can be expressed by the formula:

表示信道矩阵的奇异值，i表示第i个信道，i为大于零的自然数。这里，公式中的信道估计就是从接收数据中将假定的某个信道模型的模型参数估计出来的过程。在本发明中，先通过对接收端的当前帧进行信道估计，可以确定信道矩阵；然后通过信道矩阵进行奇异值分解，从而得到信道奇异值；最后，通过信道奇异值来描述信道相关特性，根据信道的相关特性，为信道选择相适应的传输模式，使得信道间传输模式自适应，从而也提高了链路的吞吐性能。to represent, where H represents the channel matrix, C represents the channel capacity, B represents the channel bandwidth, N represents the total number of channels, ρ represents the average power of the signal,

Represents the singular value of the channel matrix, i represents the ith channel, and i is a natural number greater than zero. Here, the channel estimation in the formula is the process of estimating the model parameters of a certain channel model assumed from the received data. In the present invention, the channel matrix can be determined by first performing channel estimation on the current frame of the receiving end; then the singular value decomposition is performed on the channel matrix to obtain the channel singular value; finally, the channel correlation characteristics are described by the channel singular value, and according to the channel The relevant characteristics of the channel, select the appropriate transmission mode for the channel, so that the transmission mode between the channels is adaptive, thereby also improving the throughput performance of the link.

In the embodiment of the present invention, singular value decomposition is performed on the channel matrix to obtain a diagonal matrix, which may be specifically:

According to the formula

Perform singular value decomposition on the channel matrix to obtain a diagonal matrix, where m×m, m×n, and n×n respectively represent the rank of the matrix, m represents the number of antennas at the transmitting end, n represents the number of antennas at the receiving end, and H represents the number of antennas at the receiving end. For the channel matrix, U represents a left unitary _matrix , U1, . . . , _Um , . , _S1 , . , . . . , V _n×n are the elements of the left unitary matrix, respectively.

Here, the unitary matrix can be simplified by multiplying it with its own conjugate transpose. Using the right unitary matrix, the transmitted signal can be preprocessed, and the transmission process can be transformed into a diagonal with parallel subchannels. array form. Here, by performing singular value decomposition on the channel matrix, the condition number is calculated according to the ratio of singular values, so that the transmission conditions of each parallel sub-channel in the channel can be judged more accurately.

Here, the number of singular values is the rank of the channel matrix, and the number of singular values directly reflects the number of degrees of freedom supported by the channel. For example, when the rank of the channel matrix is 2, through the formula:

Perform singular value decomposition on the channel matrix to obtain a diagonal matrix, where H represents the channel matrix, U represents the left unitary matrix, U1, U2, U3, and U4 are the elements of the left unitary matrix, S represents the diagonal matrix, S1, S2 are the elements of the diagonal matrix, respectively, representing the singular value of the channel matrix, V represents the right unitary matrix, and V1, V2, V3, and V4 are the elements of the left unitary matrix, respectively. Here, when the rank of the channel matrix is 2, by performing singular value decomposition on the channel matrix, the condition number is calculated according to the ratio of the singular values, so that the transmission conditions of each parallel subchannel in the channel can be judged more accurately.

For another example, when the rank of the channel matrix is 3, through the formula:

Perform singular value decomposition on the channel matrix to obtain a diagonal matrix, where H represents the channel matrix, U represents the left unitary matrix, and U1, U2, U3, U4, U5, U6, U7, U8, and U9 are the elements of the left unitary matrix, respectively. , S represents the diagonal matrix, S1, S2, S3 are the elements of the diagonal matrix, respectively, representing the singular value of the channel matrix, V represents the right unitary matrix, V1, V2, V3, V4, V5, V6, V7, V8, V9 are the elements of the left unitary matrix, respectively. Here, when the rank of the channel matrix is 3, by performing singular value decomposition on the channel matrix, the condition number CN is calculated according to the ratio of the singular values, so that the transmission conditions of each parallel subchannel in the channel can be more accurately judged.

In addition, it should be noted that when the rank of the channel matrix is n, the singular value decomposition of the channel matrix can be performed by using the above formula for performing singular value decomposition on the channel matrix.

In the embodiment of the present invention, it is judged whether the condition number is greater than the preset condition number threshold, the judgment result is obtained, the channel type of the current frame corresponding to the judgment result is determined, and the transmission mode of the current frame is determined according to the channel type, which may be specifically: :

The first step is to judge whether the condition number is greater than the preset condition number threshold, and obtain the judgment result.

Specifically, the determination threshold value T of strong and weak channel correlation, that is, the preset condition number threshold value, is first determined, and then the optimal transmission mode of the current link is determined by using the threshold value. In the specific operation, singular value decomposition should be performed on the channel matrix of LOS and NLOS in the actual indoor system, the condition number should be calculated according to the largest singular value and the smallest singular value in the decomposed singular values, and the preset condition number should be selected according to the distribution. Threshold value. For example, for the distribution diagram of FIG. 2, T=15 may be selected as the decision threshold.

In the second step, if the judgment result is that the condition number is greater than the preset condition number threshold, determine that the channel type of the current frame corresponding to the judgment result is the LOS channel, and use the space diversity transmission mode for the LOS channel.

After the condition number threshold (CNT) is determined, compare the condition number (denoted as CN) and CNT of the current frame. When CN is greater than CNT, it means that the channel has strong correlation and can be judged as the LOS channel environment, then the current frame should be The transmission method of space diversity is adopted. Among them, the spatial diversity is realized by using multiple receiving antennas. One pair of antennas is used to transmit at the transmitting end, and multiple pairs of antennas are used to receive at the receiving end. The distance between the receiving antennas is dλ/2 (λ is the working wavelength) to ensure that the fading characteristics of the output signals of the receiving antennas are independent of each other, that is, when the output signal of one receiving antenna is very low, other receiving antennas The output of the antenna does not necessarily have a low amplitude at the same time. The corresponding merging circuit selects the channel with the larger signal amplitude and the best signal-to-noise ratio to obtain a total receiving antenna output signal. In this way, the influence of channel fading is reduced, and the reliability of transmission is improved. This technology has applications in analog frequency division mobile communication system (FDMA), digital time division system (TDMA) and code division system (CDMA). Here, spatial diversity is adopted for the LOS channel environment, which improves the quality of the transmitted signal.

In the third step, if the judgment result is that the condition number is less than or equal to the preset condition number threshold, determine that the channel type of the current frame corresponding to the judgment result is the NLOS channel, and use the spatial multiplexing transmission mode for the NLOS channel.

Specifically, when CN is less than or equal to CNT, it indicates that the correlation of the channel is weak, and it can be judged that it is an NLOS channel environment, and the current frame should adopt the transmission mode of spatial multiplexing. Such an adaptive result can deal with the problem of poor throughput performance caused by switching between LOS and NLOS environments in mobile scenarios. Among them, spatial multiplexing is to use multiple antennas at the transmitter and receiver at the same time, which can double the transmission rate of the system.

In general, spatial diversity (TM2) and spatial multiplexing (TM3) technologies are the main technologies used by microcells in indoor scenarios. For indoor broadband mobile communication systems, experiments show that using TM3 under LOS will lead to low link throughput performance, while using TM3 under NLOS will bring higher throughput performance gains than using TM2. Combined with the characteristics of precoding matrices of different transmission modes, the poor effect of spatial multiplexing in LOS is caused by the strong correlation of LOS channels. When the correlation index between channels is selected as the decision of which transmission mode to use under LOS and NLOS. When determining the factor, the best throughput performance of the link can be obtained.

In order to verify the rationality of selecting the condition number as the indicator of the correlation between LOS and NLOS channels and to formulate the judgment threshold of the correlation strength, the CDF (the cumulative distribution of the condition number) of LOS and NLOS was calculated under the channel simulation of 1000 frames. function) distribution, as shown in Figure 4.

In Figure 4, the abscissa represents the condition number, and the ordinate represents the cumulative distribution function CDF of the condition number. In Figure 4, three channels are shown, namely the non-line-of-sight channel (LET-Hi NLOS) and the line-of-sight channel (LET-Hi NLOS). LOS), ideal dual-antenna transceiver transmission mode (Ideal 2 × 2 MIMN channel), among which, LET-Hi is a technology that uses linear energy transfer small base stations to meet the needs of hot spots and indoor coverage. It can be seen from Figure 4 that in the ideal case, the cumulative distribution function distribution of the condition number is very stable, but in practice, the larger the condition number, the more suitable the channel type is LOS, and the smaller the condition number, the more suitable the channel type is NLOS. Channel. Since TM3 uses the irrelevance between antennas to obtain gain, it is not suitable for LOS channel environment, especially under dynamic channel conditions, LOS and NLOS are constantly switching, so it is necessary to carry out transmission mode adaptation.

In an optional embodiment of the present invention, the channel type of the current frame corresponding to the judgment result is determined, and after the transmission mode of the current frame is determined according to the channel type, the transmission mode of the current frame can also be used as the adjacent frame after the current frame. The transmission mode corresponding to the frame within the preset period of .

Specifically, if the corresponding transmission mode is determined for each frame, and then the corresponding transmission mode is respectively used for the channel environment corresponding to each frame, the throughput performance of the link can be greatly improved. However, in practice, if there are many adjacent frames with different transmission modes, it is necessary to continuously adjust the transmission mode, which will cause additional bandwidth loss to the system. In order to reduce the additional bandwidth loss caused by continuous adjustment to the system, an appropriate adjustment period is often selected to perform adaptive adjustment. For the adaptive method described in the present invention, CQI (Channel Quality Indicator, channel quality indicator) can be used. The same period is reported, and a period value that is more in line with actual needs can also be determined through experiments. For example, a period of twenty frames can be used. The transmission mode of the frame is also spatial multiplexing. Here, taking the transmission mode of the current frame as the transmission mode corresponding to the frame in the preset period adjacent to the current frame can reduce additional bandwidth loss caused by the system, wherein the preset period is set according to actual needs.

Another schematic flowchart of a method for adapting a transmission mode based on inter-channel correlation provided by an embodiment of the present invention is as shown in FIG. 5 , and the specific process is as follows:

Step 501, the receiving process of the Nth frame receiving end.

Here, since the corresponding transmission mode needs to be determined for the Nth frame, the signal of the Nth frame needs to be received at the receiving end, and the Nth frame may be any frame in the entire channel.

Step 502, a matrix H is obtained by channel estimation, and the matrix H is decomposed by SVD.

Here, because the present invention judges the channel type of the Nth frame by the condition number, and the condition number is obtained by singular value decomposition. Therefore, it is necessary to perform channel estimation on the Nth frame to obtain the matrix H, which is the channel matrix, and perform singular value (SDV) decomposition on the channel matrix to obtain a diagonal matrix. The elements in the diagonal matrix are the singular values of the channel matrix. .

Step 503: Calculate the current condition number (CN) according to the singular value.

By performing singular value (SDV) decomposition on the channel matrix, the obtained diagonal matrix includes multiple singular values, and the ratio of the largest singular value and the smallest singular value among these singular values is taken as the condition number (CN) of the current frame.

Step 504, it is judged that CN>CNT.

Here, CNT is a preset condition number threshold value, and the judgment result is obtained by judging whether the condition number CN of the current frame is greater than the preset condition number threshold value CNT.

Step 505, select a space diversity transmission mode.

Specifically, when the condition number is greater than the preset condition number threshold, it is determined that the channel type of the current frame corresponding to the judgment result is the LOS channel, and the space diversity transmission mode is adopted for the LOS channel.

Step 506, select a spatial multiplexing transmission mode.

Specifically, when the condition number is less than or equal to the preset condition number threshold, it is determined that the channel type of the current frame corresponding to the judgment result is the NLOS channel, and the spatial multiplexing transmission mode is adopted for the NLOS channel.

Step 507: Determine the transmission mode of the next frame.

After the transmission mode of the Nth frame is determined, the transmission mode is adopted for the Nth frame, and the transmission mode of the N+1th frame is continued to be determined, and the determination method is the same as the above steps for determining the Nth frame.

It can be seen that a method for adaptive transmission mode based on inter-channel correlation provided by the embodiment of the present invention first performs channel estimation on the Nth frame of the receiving end to obtain a channel matrix; and performs singular value decomposition on the channel matrix to obtain a diagonal matrix ; Calculate the ratio of the largest singular value and the smallest singular value among all singular values, and use the ratio as the condition number of the Nth frame; determine whether the condition number is greater than the preset condition number threshold, obtain the judgment result, and determine the corresponding judgment result. The channel type of the Nth frame, and the transmission mode of the current frame is determined according to the channel type, thereby greatly improving the throughput performance of the link.

A transmission mode adaptation method based on inter-channel correlation provided by the embodiment of the present invention is adopted, and simulation is carried out, the resource size is 2PRBs, and high-order 256QAM is adopted. The relevant parameters are shown in Table 1.

Table 1

Among them, RB stands for Antenna Bearer, HARQ stands for Hybrid Automatic Repeat Request, QPSK stands for Quadrature Phase Shift Keying Signal, AMC stands for Adaptive Modulation and Coding, and MMSE stands for Parallel Minimum Mean Square Error Algorithm.

The simulation results are shown in Figure 6. The simulation results given in Figure 6 show that the abscissa represents the signal-to-noise ratio (SNR), in decibels (dB), and the ordinate represents the throughput of the link (Throughput), in megabytes Bits per second (Mbps). The figure shows the simulation results of spatial diversity under line-of-sight, the simulation results of spatial multiplexing under line-of-sight, the simulation results of spatial diversity under non-line-of-sight, the simulation results of spatial multiplexing under non-line-of-sight, and the transmission mode automatic of line-of-sight. Simulation results of adaptive and non-line-of-sight transmission mode adaptation. As can be seen from Figure 6, when the transmission mode adaptation is performed, compared with no adaptation, the most suitable transmission is selected in TM2 (spatial diversity) and TM3 (spatial multiplexing) under line-of-sight and non-line-of-sight. mode to maximize the throughput performance of the link.

Referring to FIG. 7, FIG. 7 is a schematic structural diagram of a transmission mode adaptation device based on inter-channel correlation provided by an embodiment of the present invention, including the following modules:

an estimation module 701, configured to perform channel estimation on the current frame of the receiving end to obtain a channel matrix;

The decomposition module 702 is used to perform singular value decomposition on the channel matrix to obtain a diagonal matrix, and the diagonal elements in the diagonal matrix are the singular values of the channel matrix;

The calculation module 703 is used to calculate the ratio of the largest singular value and the smallest singular value among all the singular values, and the ratio is used as the condition number of the current frame, and the condition number represents the size of the correlation between the channels;

The judgment module 704 is used to judge whether the condition number is greater than the preset condition number threshold, obtain the judgment result, determine the channel type of the current frame corresponding to the judgment result, and determine the transmission mode of the current frame according to the channel type, wherein the channel type Including line-of-sight LOS channels or non-line-of-sight NLOS channels.

It can be seen from this that, in the transmission mode adaptation device based on inter-channel correlation provided by the embodiment of the present invention, the estimation module first performs channel estimation on the current frame of the receiving end to obtain the channel matrix; then the channel matrix is singularized by the decomposition module. value decomposition to obtain a diagonal matrix; then calculate the ratio of the largest singular value and the smallest singular value among all singular values through the calculation module, and use the ratio as the condition number of the current frame; finally, the judgment module is used to judge whether the condition number is greater than the preset condition number gate The limit value is obtained, the judgment result is obtained, the channel type of the current frame corresponding to the judgment result is determined, and the transmission mode of the current frame is determined according to the channel type. In this way, the condition number is used as the correlation index between the channels. By judging the size of the condition number of the current frame and the preset condition number threshold, and according to the judgment result, it is determined whether the current frame is the LOS channel type or the NLOS channel type, and finally according to the The channel type determines the transmission mode of the current frame, which greatly improves the throughput performance of the link.

Further, the decomposition module 702 is specifically used for:

According to the formula

Perform singular value decomposition on the channel matrix to obtain a diagonal matrix, where m×m, m×n, and n×n respectively represent the rank of the matrix, m represents the number of antennas at the transmitting end, n represents the number of antennas at the receiving end, and H represents the number of antennas at the receiving end. For the channel matrix, U represents a left unitary _matrix , U1, . . . , _Um , . , _S1 , . , . . . , V _n×n are the elements of the left unitary matrix, respectively.

Further, the judgment module 704 includes:

a judgment sub-module, used for judging whether the condition number is greater than the preset condition number threshold, and obtaining the judgment result;

The first determination submodule is used for determining that the channel type of the current frame corresponding to the judgment result is the LOS channel if the judgment result is that the condition number is greater than the preset condition number threshold value, and adopts the transmission mode of space diversity for the LOS channel;

The second determination sub-module is configured to determine that the channel type of the current frame corresponding to the judgment result is an NLOS channel if the condition number is less than or equal to the preset condition number threshold as a result of the judgment, and use spatial multiplexing for the NLOS channel. transfer mode.

Further, the device also includes:

The determining module is configured to use the transmission mode of the current frame as the transmission mode corresponding to the frame in the preset period adjacent to the current frame.

An embodiment of the present invention further provides an electronic device, as shown in FIG. 8 , including a processor 801 , a communication interface 802 , a memory 803 and a communication bus 804 , wherein the processor 801 , the communication interface 802 , and the memory 803 pass through the communication bus 804 complete communication with each other,

a memory 803 for storing computer programs;

When the processor 801 is used to execute the program stored in the memory 803, the following steps are implemented:

Perform channel estimation on the current frame of the receiver to obtain a channel matrix;

Perform singular value decomposition on the channel matrix to obtain a diagonal matrix, and the diagonal elements in the diagonal matrix are the singular values of the channel matrix;

Calculate the ratio of the largest singular value and the smallest singular value among all singular values, and use the ratio as the condition number of the current frame, and the condition number represents the magnitude of the correlation between channels;

Judging whether the condition number is greater than the preset condition number threshold, obtaining the judgment result, determining the channel type of the current frame corresponding to the judgment result, and determining the transmission mode of the current frame according to the channel type, wherein the channel type includes line-of-sight LOS channel or Non-line-of-sight NLOS channel.

The communication bus mentioned in the above electronic device may be a peripheral component interconnect standard (Peripheral Component Interconnect, PCI) bus or an Extended Industry Standard Architecture (Extended Industry Standard Architecture, EISA) bus or the like. The communication bus can be divided into an address bus, a data bus, a control bus, and the like. For ease of presentation, only one thick line is used in the figure, but it does not mean that there is only one bus or one type of bus.

The communication interface is used for communication between the above electronic device and other devices.

The memory may include random access memory (Random Access Memory, RAM), and may also include non-volatile memory (Non-Volatile Memory, NVM), such as at least one disk memory. Optionally, the memory may also be at least one storage device located away from the aforementioned processor.

The above-mentioned processor may be a general-purpose processor, including a central processing unit (Central Processing Unit, CPU), a network processor (Network Processor, NP), etc.; may also be a digital signal processor (Digital Signal Processing, DSP), an application-specific integrated circuit (Application Specific Integrated Circuit, ASIC), Field-Programmable Gate Array (Field-Programmable Gate Array, FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components.

It can be seen that, through the electronic device provided by the embodiment of the present invention, the current frame of the receiving end is firstly channel estimated to obtain a channel matrix; then singular value decomposition is performed on the channel matrix to obtain a diagonal matrix; and then all singular values are calculated. The ratio of the largest singular value and the smallest singular value is used as the condition number of the current frame; finally, it is judged whether the condition number is greater than the preset condition number threshold value, the judgment result is obtained, and the channel type of the current frame corresponding to the judgment result is determined, and Determine the transmission mode of the current frame according to the channel type. In this way, the condition number is used as the correlation index between channels. By judging the size of the condition number of the current frame and the preset condition number threshold, and according to the judgment result, it is determined whether the current frame is the LOS channel type or the NLOS channel type, and finally according to the The channel type determines the transmission mode of the current frame, which greatly improves the throughput performance of the link.

In yet another embodiment provided by the present invention, a computer-readable storage medium is also provided, where instructions are stored in the computer-readable storage medium, when the computer-readable storage medium is run on a computer, the computer is made to execute any one of the above-mentioned embodiments. The described method of transmission mode adaptation based on inter-channel correlation. Wherein, the method for adaptive transmission mode based on inter-channel correlation includes:

Perform channel estimation on the current frame of the receiver to obtain a channel matrix;

Perform singular value decomposition on the channel matrix to obtain a diagonal matrix, and the diagonal elements in the diagonal matrix are the singular values of the channel matrix;

Calculate the ratio of the largest singular value and the smallest singular value among all singular values, and use the ratio as the condition number of the current frame, and the condition number represents the magnitude of the correlation between channels;

Judging whether the condition number is greater than the preset condition number threshold, obtaining the judgment result, determining the channel type of the current frame corresponding to the judgment result, and determining the transmission mode of the current frame according to the channel type, wherein the channel type includes line-of-sight LOS channel or Non-line-of-sight NLOS channel.

It can be seen that, through the computer-readable storage medium provided by the embodiment of the present invention, first perform channel estimation on the current frame of the receiving end to obtain a channel matrix; then perform singular value decomposition on the channel matrix to obtain a diagonal matrix; and then calculate all The ratio of the largest singular value to the smallest singular value in the singular value, and the ratio is used as the condition number of the current frame; finally, it is judged whether the condition number is greater than the preset condition number threshold, the judgment result is obtained, and the channel of the current frame corresponding to the judgment result is determined. type, and determine the transmission mode of the current frame according to the channel type. In this way, the condition number is used as the correlation index between the channels. By judging the size of the condition number of the current frame and the preset condition number threshold, and according to the judgment result, it is determined whether the current frame is the LOS channel type or the NLOS channel type, and finally according to the The channel type determines the transmission mode of the current frame, which greatly improves the throughput performance of the link.

It should be noted that, in this document, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any relationship between these entities or operations. any such actual relationship or sequence exists. Moreover, the terms "comprising", "comprising" or any other variation thereof are intended to encompass a non-exclusive inclusion such that a process, method, article or device that includes a list of elements includes not only those elements, but also includes not explicitly listed or other elements inherent to such a process, method, article or apparatus. Without further limitation, an element qualified by the phrase "comprising a..." does not preclude the presence of additional identical elements in a process, method, article or apparatus that includes the element.

Each embodiment in this specification is described in a related manner, and the same and similar parts between the various embodiments may be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the embodiments of the apparatus, electronic equipment, and computer-readable storage medium, since they are basically similar to the method embodiments, the description is relatively simple.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention are included in the protection scope of the present invention.

Claims (8)

1. A transmission mode adaptation method based on inter-channel correlation, characterized in that the method comprises: Perform channel estimation on the current frame of the receiver to obtain a channel matrix; Perform singular value decomposition on the channel matrix to obtain a diagonal matrix, and the diagonal elements in the diagonal matrix are the singular values of the channel matrix; Calculate the ratio of the largest singular value and the smallest singular value among all singular values, and use the ratio as the condition number of the current frame, and the condition number represents the magnitude of the correlation between the channels; Judging whether the condition number is greater than a preset condition number threshold, obtaining a judgment result, determining the channel type of the current frame corresponding to the judgment result, and determining the transmission mode of the current frame according to the channel type, Wherein, the channel type includes a line-of-sight LOS channel or a non-line-of-sight NLOS channel; judging whether the condition number is greater than a preset condition number threshold, obtaining a judgment result, determining the channel type of the current frame corresponding to the judgment result, and determining the transmission of the current frame according to the channel type mode, including: Judging whether the condition number is greater than a preset condition number threshold, and obtaining a judgment result; If the judgment result is that the condition number is greater than the preset condition number threshold value, determine that the channel type of the current frame corresponding to the judgment result is the LOS channel, and use the LOS channel for the LOS channel. The transmission mode of space diversity; If the judgment result is that the condition number is less than or equal to the preset condition number threshold, determine that the channel type of the current frame corresponding to the judgment result is the NLOS channel, and determine the NLOS channel. The channel adopts the transmission mode of spatial multiplexing. 2 . The method according to claim 1 , wherein the channel matrix is subjected to singular value decomposition to obtain a diagonal matrix, and the diagonal elements in the diagonal matrix represent singular values of the channel matrix. 3 . ,include: According to the formula

Perform singular value decomposition on the channel matrix to obtain a diagonal matrix, where m×m, m×n, and n×n respectively represent the rank of the matrix, m represents the number of antennas at the transmitting end, n represents the number of antennas at the receiving end, and H represents the number of antennas at the receiving end. For the channel matrix, U represents a left unitary _matrix , U1, . . . , _Um , . , _S1 , . , . . . , V _n×n are the elements of the left unitary matrix, respectively. 3. The method according to claim 1, wherein after the determining the channel type of the current frame corresponding to the judgment result, and determining the transmission mode of the current frame according to the channel type, the The method also includes: The transmission mode of the current frame is taken as a transmission mode corresponding to a frame in a preset period adjacent to the current frame. 4. A transmission mode adaptation device based on inter-channel correlation, characterized in that the device comprises: an estimation module, which is used to perform channel estimation on the current frame of the receiving end to obtain a channel matrix; a decomposition module, configured to perform singular value decomposition on the channel matrix to obtain a diagonal matrix, where the diagonal elements in the diagonal matrix are singular values of the channel matrix; a calculation module, configured to calculate the ratio of the largest singular value to the smallest singular value among all singular values, and use the ratio as the condition number of the current frame, and the condition number represents the size of the correlation between the channels; A judgment module, configured to judge whether the condition number is greater than a preset condition number threshold, obtain a judgment result, determine the channel type of the current frame corresponding to the judgment result, and determine the current frame according to the channel type the transmission mode of the frame, wherein the channel type includes a line-of-sight LOS channel or a non-line-of-sight NLOS channel; The judging module includes: a judging submodule for judging whether the condition number is greater than a preset condition number threshold, and obtaining a judgment result; A first determination submodule, configured to determine that the channel type of the current frame corresponding to the judgment result is the LOS channel if the judgment result is that the condition number is greater than the preset condition number threshold , and adopt the transmission mode of space diversity to the LOS channel; A second determination submodule, configured to determine that the channel type of the current frame corresponding to the determination result is the channel type if the condition number is less than or equal to the preset condition number threshold as the determination result NLOS channel, and a spatial multiplexing transmission mode is adopted for the NLOS channel. 5. The device according to claim 4, wherein the decomposition module is specifically used for: According to the formula

Perform singular value decomposition on the channel matrix to obtain a diagonal matrix, where m×m, m×n, and n×n respectively represent the rank of the matrix, m represents the number of antennas at the transmitting end, n represents the number of antennas at the receiving end, and H represents the number of antennas at the receiving end. For the channel matrix, U represents a left unitary _matrix , U1, . . . , _Um , . , _S1 , . , . . . , V _n×n are the elements of the left unitary matrix, respectively. 6. The apparatus of claim 4, wherein the apparatus further comprises: A determining module, configured to use the transmission mode of the current frame as the transmission mode corresponding to the frame in a preset period adjacent to the current frame. 7. An electronic device, comprising a processor, a communication interface, a memory, and a communication bus, wherein the processor, the communication interface, and the memory communicate with each other through the communication bus; the memory for storing computer programs; The processor is configured to implement the method steps of any one of claims 1-3 when executing the program stored in the memory. 8. A computer-readable storage medium, wherein a computer program is stored in the computer-readable storage medium, and when the computer program is executed by a processor, the method steps of any one of claims 1-3 are implemented .

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