CN107547119A - A kind of transmission mode adaptive approach and device based on inter-channel correlation - Google Patents

Abstract

The embodiments of the invention provide a kind of transmission mode adaptive approach based on inter-channel correlation and device, methods described to include：Channel estimation is carried out to the present frame of receiving terminal, obtains channel matrix；Singular value decomposition is carried out to channel matrix, obtains diagonal matrix, diagonal element is the singular value of channel matrix in diagonal matrix；Calculate maximum singular value and the ratio of minimum singular value in all singular values, the conditional number using ratio as present frame；Whether Rule of judgment number is more than preparatory condition number threshold value, judged result is obtained, it is determined that the channel type of present frame corresponding with judged result, and determines according to channel type the transmission mode of present frame, wherein, channel type includes sighting distance LOS channels or non line of sight NLOS channels.Using the embodiment of the present invention, it is possible to increase the throughput performance of link.

Description

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

technical field

The present invention relates to the field of communication technology, in particular to a transmission mode adaptive method and device 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 completed by alternating between LOS (Line of Sight, line of sight) and NLOS (Non Line of Sight, non-line-of-sight), where LOS It means that in wireless communication, the transmitting and receiving antennas must be able to look directly at two points without any obstruction in the middle. NLOS means that in wireless communication, the two points of sight that need to communicate are blocked and cannot see each other. In order to meet the growing demand for high-speed data transmission, multiple antennas can be configured between the base station and the mobile station to realize the data transmission of the LOS communication link and the NLOS communication link, thus forming a MIMO (Multiple Input Multiple Output, Multiple-input multiple-output) systems, in which space diversity and space multiplexing are the main technologies used in MIMO systems.

The existing transmission mode based on inter-channel correlation adopts the transmission mode of spatial multiplexing for both the LOS communication link and the NLOS communication link between the base station and the mobile station. Specifically, multiple antennas are used at the receiving end and the transmitting end first, so that multiple antennas can generate multipath components during space propagation, and then make full use of the multipath components in space propagation to use multipath components on the same frequency band Multiple data channels (MIMO sub-channels) are generated to transmit signals, so that the channel capacity increases linearly with the number of antennas. This increase in channel capacity does not need to occupy additional bandwidth or consume additional transmit power, so it is a very effective means to increase channel and system capacity.

However, for indoor scenarios, especially in the case of sparse distribution of small base stations, the communication link between the base station and the mobile station will face more frequent alternation between LOS and NLOS. For the link NLOS, the use of spatial multiplexing can bring higher throughput performance, but for LOS whose link quality is better than NLOS, adopting the transmission mode of spatial multiplexing will cause the throughput performance of the link to decrease.

Contents of the invention

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

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

Perform channel estimation on the current frame at the receiving end to obtain a channel matrix;

performing 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;

Calculating the ratio of the largest singular value to the smallest singular value among all singular values, using the ratio as the condition number of the current frame, the condition number representing the magnitude of the correlation between channels;

judging whether the condition number is greater than a preset condition number threshold, obtaining a judgment result, determining a channel type of the current frame corresponding to the judgment result, and determining a 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, wherein diagonal elements in the diagonal matrix represent singular values of the channel matrix, including:

According to the formula

Singular value decomposition is performed on the channel matrix to obtain a diagonal matrix, wherein 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 In the channel matrix, U represents a left unitary matrix, U1, ..., Um, ..., U _m(m-1)+1 , ..., U _m×m are elements of the left unitary matrix, and S represents a diagonal matrix , S1,..., Sm×n are the elements of the diagonal matrix respectively, representing the singular value of the channel matrix, H represents the right unitary matrix, V1,..., Vn,..., V _n(n-1)+1 , ..., V _n×n are the elements of the left unitary matrix respectively.

Optionally, the judging whether the condition number is greater than a preset condition number threshold, obtaining a judging result, determining the channel type of the current frame corresponding to the judging 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, it is determined that the channel type of the current frame corresponding to the judgment result is the LOS channel, and the LOS channel is used Transmission mode with space diversity;

If the judgment result is that the condition number is less than or equal to the preset condition number threshold value, then determine that the channel type of the current frame corresponding to the judgment result is the NLOS channel, and perform the NLOS 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 used as a transmission mode corresponding to frames within a preset period adjacent to the current frame.

The embodiment of the present invention discloses a transmission mode adaptive device based on inter-channel correlation, and the device includes:

An estimation module, configured to perform channel estimation on the current frame at 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 the 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 a condition number of the current frame, and the condition number represents the magnitude of the correlation between channels;

A judging 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 A frame transmission mode, 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

Singular value decomposition is performed on the channel matrix to obtain a diagonal matrix, wherein 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 In the channel matrix, U represents a left unitary matrix, U1, ..., Um, ..., U _m(m-1)+1 , ..., U _m×m are elements of the left unitary matrix, and S represents a diagonal matrix , S1,..., Sm×n are the elements of the diagonal matrix respectively, representing the singular value of the channel matrix, H represents the right unitary matrix, V1,..., Vn,..., V _n(n-1)+1 , ..., V _n×n are the elements of the left unitary matrix respectively.

The judgment module includes:

A judging submodule, used to judge whether the condition number is greater than a preset condition number threshold, and obtain a judgment result;

A first determining 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 adopting a space diversity transmission mode for the LOS channel;

The second determining submodule is configured to determine that the channel type of the current frame corresponding to the judgment result is the An NLOS channel, and adopts a spatial multiplexing transmission mode 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 frames within a preset period adjacent to the current frame.

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

The memory is used to store computer programs;

The processor is configured to, when executing the program stored in the memory, realize the steps of the above-mentioned transmission mode adaptive method based on inter-channel correlation.

In yet another aspect of the implementation of the present invention, a computer-readable storage medium is also disclosed. The computer-readable storage medium stores instructions, and when it is run on a computer, it causes the computer to perform any one of the above-mentioned ones. A transmission mode adaptation method based on inter-channel correlation.

The embodiment of the present invention provides a transmission mode adaptive method and device based on inter-channel correlation. First, channel estimation is performed on the current frame at the receiving end to obtain a channel matrix; then, a singular value decomposition is performed on the channel matrix to obtain a diagonal matrix; Then 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; finally judge whether the condition number is greater than the preset condition number threshold, obtain the judgment result, and determine the current frame corresponding to the judgment result The channel type of the frame, and determine the transmission mode of the current frame according to the channel type. This kind of condition number is used as the correlation index between channels, by judging the size of the condition number of the current frame and the threshold value of the preset condition number, and determining whether the current frame is an LOS channel type or an NLOS channel type according to the judgment result, and finally according to 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, implementing any product or method of the present invention does not necessarily need to achieve all the above-mentioned advantages at the same time.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the 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. Those skilled in the art can also obtain other drawings based on these drawings without creative work.

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;

FIG. 2 is a topology diagram of a static scene between channels provided by an embodiment of the present invention;

FIG. 3 is a topology diagram of a dynamic scene between channels provided by an embodiment of the present invention;

FIG. 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;

FIG. 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 device based on inter-channel correlation provided by an embodiment of the present invention;

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

detailed description

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

In recent years, the indoor broadband mobile communication system focuses on improving the transmission rate and capacity in hot spots and indoor coverage scenarios. Compared with other scenarios, indoor scenarios have larger bandwidth and lower mobile station movement speed, so indoor broadband mobile communication It has a better indoor channel environment and higher peak throughput, thus greatly improving its transmission rate. However, for indoor scenarios, especially in the case of sparse distribution of small base stations, the communication link between the base station and the mobile station will face more frequent alternation between LOS and NLOS, which is the need for indoor scenarios compared to outdoor macro base station scenarios. new topics to consider. Based on this, the present invention provides a transmission mode adaptive 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 at the receiving end to obtain a channel matrix.

Specifically, due to the great randomness of the wireless channel, the amplitude, phase, and frequency of the received signal are distorted, which brings great challenges to the design of the receiver. At the same time, in wireless communication systems, diversity, channel equalization, optimal 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 component in 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 model parameters of an assumed channel model from received data. If the channel is linear, then channel estimation is to estimate the system impulse response. It should be emphasized that channel estimation is a mathematical representation of the influence of the channel on the input signal, and a "good" channel estimation is an estimation algorithm that minimizes certain estimation errors. The channel estimation criteria commonly used in wireless communication are minimum mean square error criterion (MMSE) and maximum likelihood criterion (ML).

S102. Perform singular value decomposition on the channel matrix to obtain a diagonal matrix, where 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 an indicator of the channel state information, it is necessary to perform the Singular Value Decomposition on the channel matrix 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 the 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 to 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" 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 of the same size, which means that the channel supports both degrees of freedom well without any difference, which is an ideal situation; while It is different in the case of two singular values in the "random channel", one with a large value and one with a small value. In other words, this channel is more than enough to support 1 degree of freedom, but 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 closer this ratio (condition number) is to 1, it means that each parallel element in the channel The transmission conditions of the channel (degrees of freedom) are very average; the larger the ratio, the larger the difference and unbalanced transmission conditions of each sub-channel. Here, the condition number represents the size of the correlation between channels, that is, the size of the degrees of freedom of each parallel sub-channel between channels.

S104, judging whether the condition number is greater than a preset condition number threshold, obtaining a judging result, determining the channel type of the current frame corresponding to the judging result, and determining 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 threshold T for judging whether the channel correlation is strong or weak, and use this threshold to determine the best transmission mode for the current link. In the specific operation, the singular value decomposition of the channel matrix of LOS and NLOS in the actual indoor system should be performed, the condition number should be calculated, and the distribution of the received signal in the indoor scene should be used to select the received signal near the middle of all received signals to the base station. distance as a judgment value. Here, the threshold value of the preset condition number can be set according to the actual situation. For example, for the topology diagram of the inter-channel static scene in FIG. 2 , T=15 can be selected as the decision threshold. After the condition number threshold (denoted as CNT) is determined, compare the condition number of the current frame (denoted as CN) with CNT. When CN is greater than CNT, it indicates that the correlation of the channel is strong, and it can be judged as the LOS channel environment, that is, the current The frame should adopt the transmission mode of space diversity, otherwise, it means 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 space multiplexing. Such an adaptive result can cope with the problem of poor throughput performance caused by switching between LOS and NLOS environments in mobile scenarios.

It can be seen that, in the transmission mode adaptive method based on inter-channel correlation provided by the embodiment of the present invention, the channel estimation is first performed on the current frame at the receiving end to obtain the channel matrix; then the singular value decomposition is performed on the channel matrix to obtain the diagonal Matrix; then 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; finally judge whether the condition number is greater than the preset condition number threshold value, obtain the judgment result, and determine whether it corresponds to the judgment result The channel type of the current frame, and determine the transmission mode of the current frame according to the channel type. This kind of condition number is used as the correlation index between channels, by judging the size of the condition number of the current frame and the threshold value of the preset condition number, and determining whether the current frame is an LOS channel type or an NLOS channel type according to the judgment result, and finally according to 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 previous studies on transmission mode adaptation, a common transmission mode adaptation method is based on channel quality, but for LOS whose link quality is 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 the present invention is introduced through FIG. 2 and FIG. 3 .

FIG. 2 is a topology diagram of a static scene between channels provided by an embodiment of the present invention. The topological diagram of the static scene shown in Figure 2 is that there are 6 independent rooms on both sides of the hall, and the area of each room is 6m×6m. In the center of the hall there are two large rooms with a proportion of 8m×8m. The thickness of the lines in the figure represents the thickness of the wall, thick lines represent thicker walls, and thin lines represent thinner walls. The base station is deployed in the center of the hall for signal transmission (Tx), and the three test points in the figure represent the static detection point UE, UE is the receiver (Rx), and the straight-line distance from Tx is 3m, 15m, 24m. Obviously, the propagation mode of the signal between Tx and Rx with a distance of 3m is LOS, and the test point at Rx is called "good point", the propagation mode of 15m and 24m is NLOS, and the thickness of the wall penetrated is different, respectively The test points at Rx are called "middle point" and "near point".

Fig. 3 is a topological diagram of a dynamic scene between channels provided by an embodiment of the present invention. In the topological diagram of a 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 6m ×6m. In the center of the hall there are two large rooms with a proportion of 8m×8m. The thickness of the lines in the figure represents the thickness of the wall, thick lines represent thicker walls, and thin lines represent thinner walls. In Figure 2, · at A, B, C, D, E, F, G, H, and I indicates the detection point in the path, between A, B, C, D, E, F, G, H, and I The straight line of represents the moving path, and the user's moving route is X->A->B->C->D->E->D->C->B->F->G->H->I. The moving 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 (respectively through a wall Thin Wall and Two Thin Walls). C->D, D->C and F->G are the transition states from LOS to NLOS. 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.

Through the topology diagrams of static and dynamic scenarios between channels provided in Figure 2 and Figure 3, it can be seen that LOS and NLOS frequently alternate in indoor scenarios. Therefore, it is very 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 channel capacity and channel singular value can be expressed by the formula:

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 i-th 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 an assumed channel model 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 performing singular value decomposition through the channel matrix to obtain the channel singular value; finally, describing the channel correlation characteristics through the channel singular value, 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 self-adaptive, thereby improving the throughput performance of the link.

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

According to the formula

Singular value decomposition is performed on the channel matrix to obtain a diagonal matrix, wherein 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 In the channel matrix, U represents a left unitary matrix, U1, ..., Um, ..., U _m(m-1)+1 , ..., U _m×m are elements of the left unitary matrix, and S represents a diagonal matrix , S1,..., Sm×n are the elements of the diagonal matrix respectively, representing the singular value of the channel matrix, H represents the right unitary matrix, V1,..., Vn,..., V _n(n-1)+1 , ..., V _n×n are the elements of the left unitary matrix respectively.

Here, the unitary matrix can simplify itself by multiplying it with its conjugate transpose. Using the right unitary matrix, the transmitted signal can be preprocessed, and the transmission process can be transformed into a diagonal channel with parallel sub-channels. array form. Here, 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 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, the formula:

Singular value decomposition is performed 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, and S1 and S2 are the elements of the diagonal matrix and represent the singular values 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 sub-channel in the channel can be judged more accurately.

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

Singular value decomposition is performed 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. Here, when the rank of the channel matrix is 3, the channel matrix is subjected to singular value decomposition to calculate the condition number CN according to the ratio of the singular values, so that the transmission conditions of each parallel sub-channel in the channel can be judged more accurately.

In addition, it should be noted that when the rank of the channel matrix is n, the channel matrix can be subjected to singular value decomposition through 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 value, 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 specifically be :

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

Specifically, first determine the threshold value T for judging whether the channel correlation is strong or weak, that is, the preset condition number threshold value, and then use the threshold value to determine the best transmission mode for the current link. In the specific operation, the singular value decomposition of the channel matrix of LOS and NLOS in the practical indoor system should be performed, and the condition number should be calculated according to the largest singular value and the smallest singular value in the decomposed singular value, and the preset condition number should be selected according to the distribution threshold. For example, for the distribution diagram in 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 value, then it is determined that the channel type of the current frame corresponding to the judgment result is a LOS channel, and a space diversity transmission mode is adopted 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 indicates that the correlation of the channel is strong, and it can be judged as an LOS channel environment, and the current frame should be The transmission mode adopts space diversity. Among them, space diversity is realized by using multiple receiving antennas. One antenna is used for transmission at the sending end, and multiple antennas are used for receiving 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 a certain receiving antenna is very low, other receiving antennas The output of the antenna does not necessarily have a low amplitude phenomenon at the same time, and the path with the larger signal amplitude and the best signal-to-noise ratio is selected from the corresponding combining circuit to obtain a total receiving antenna output signal. This reduces the influence of channel fading and improves the reliability of transmission. This technology is used in analog frequency division mobile communication system (FDMA), digital time division system (TDMA) and code division system (CDMA). Here, space 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 value, then determine that the channel type of the current frame corresponding to the judgment result is an NLOS channel, and adopt a 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 as an NLOS channel environment, and the current frame should adopt the transmission mode of spatial multiplexing. Such an adaptive result can cope 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 transmitting end and receiving end 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 for micro cells 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 TM2. Combined with the characteristics of precoding matrices in different transmission modes, the poor effect of using spatial multiplexing under LOS is caused by the strong correlation of LOS channels. When determining the factor, the best throughput performance of the link can be obtained.

In order to verify the rationality of choosing the condition number as the correlation indicator between LOS and NLOS channels and to draw up the threshold value for judging the strength of the correlation, the CDF (cumulative distribution of the condition number of the LOS and NLOS function) distribution, as shown in Figure 4.

In Fig. 4, the abscissa represents the condition number, and the ordinate represents the cumulative distribution function CDF of the condition number. In Fig. 4, three channels are shown, namely the non-line-of-sight channel (LET-Hi NLOS), the line-of-sight channel (LET-Hi LOS), ideal dual-antenna transceiver transmission mode (Ideal 2×2MIMN channel), among which, LET-Hi is a technology that uses linear energy transfer small base stations to meet hotspot and indoor coverage requirements. It can be seen from Figure 4 that under ideal conditions, the cumulative distribution function distribution of the condition number is very stable, but in reality, 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. Because TM3 uses the uncorrelation between antennas to obtain gain, it is not suitable for the channel environment of LOS, 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, after 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, the transmission mode of the current frame can also be regarded as the next adjacent to the current frame. The transmission mode corresponding to the frames within the preset period.

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

The embodiment of the present invention also provides another schematic flowchart of a transmission mode adaptive method based on inter-channel correlation, as shown in FIG. 5 , and the specific process is as follows:

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

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 can be any frame in the entire channel.

Step 502, channel estimation obtains a matrix H, and performs SVD decomposition on the matrix H.

Here, because the present invention judges the channel type of the Nth frame through the condition number, and the condition number is obtained through singular value decomposition. Therefore, it is necessary to perform channel estimation on the Nth frame first 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, and 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.

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

Step 504, judge CN>CNT.

Here, CNT is the 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 a LOS channel, and a space diversity transmission mode is adopted for the LOS channel.

Step 506, selecting a spatial multiplexing transmission mode.

Specifically, when 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 an NLOS channel, and adopt a spatial multiplexing transmission mode 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 determined continuously, and the determination method is the same as the above-mentioned steps of determining the Nth frame.

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

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

Table 1

Among them, RB means antenna bearer, HARQ means hybrid automatic repeat request, QPSK means quadrature phase shift keying signal, AMC means adaptive modulation and coding, and MMSE means 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), and the unit is decibel (dB), and the ordinate represents the throughput of the link (Throughput), and the unit is M Bits per second (Mbps). The figure shows the simulation results of space diversity under line-of-sight, the simulation results of space multiplexing under line-of-sight, the simulation results of space diversity under non-line-of-sight, the simulation results of space multiplexing under non-line-of-sight, the transmission mode of line-of-sight Simulation results of adaptation and simulation results of non-line-of-sight transmission mode adaptation. It can be seen from Figure 6 that when the transmission mode is adaptive, 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 at 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 in 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 channels;

Judging module 704, used to judge whether the condition number is greater than the preset condition number threshold value, 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 that, in the transmission mode adaptive device based on inter-channel correlation provided by the embodiment of the present invention, the channel estimation module is used to estimate the current frame of the receiving end to obtain the channel matrix; and 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 to the smallest singular value in all singular values through the calculation module, 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 gate through the judgment module Limit value, 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. This kind of condition number is used as the correlation index between channels, by judging the size of the condition number of the current frame and the threshold value of the preset condition number, and determining whether the current frame is an LOS channel type or an NLOS channel type according to the judgment result, and finally according to 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

Singular value decomposition is performed on the channel matrix to obtain a diagonal matrix, wherein 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 In the channel matrix, U represents a left unitary matrix, U1, ..., Um, ..., U _m(m-1)+1 , ..., U _m×m are elements of the left unitary matrix, and S represents a diagonal matrix , S1,..., Sm×n are the elements of the diagonal matrix respectively, representing the singular value of the channel matrix, H represents the right unitary matrix, V1,..., Vn,..., V _n(n-1)+1 , ..., V _n×n are the elements of the left unitary matrix respectively.

Further, the judging module 704 includes:

A judging sub-module is used to judge whether the condition number is greater than the preset condition number threshold value, and obtain the judgment result;

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

The second determination submodule is used to determine that the channel type of the current frame corresponding to the judgment result is an NLOS channel if the judgment result is that the condition number is less than or equal to the preset condition number threshold value, and the NLOS channel adopts the method of spatial multiplexing transfer mode.

Further, 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 within the preset period adjacent to the current frame.

The embodiment of the present invention also provides an electronic device, as shown in FIG. complete the mutual communication,

memory 803, for storing computer programs;

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

Perform channel estimation on the current frame at the receiving end to obtain a channel matrix;

Singular value decomposition is performed 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 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 magnitude of the correlation between channels;

Judging whether the condition number is greater than the preset condition number threshold value, 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 a 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 (PCI) bus or an 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 representation, 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 electronic device and other devices.

The memory may include a random access memory (Random Access Memory, RAM), and may also include a 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 far away from the aforementioned processor.

Above-mentioned processor can be general-purpose processor, comprises central processing unit (Central Processing Unit, CPU), network processor (Network Processor, NP) etc.; Can also be Digital Signal Processor (Digital Signal Processing, DSP), ASIC (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 an electronic device provided by an embodiment of the present invention, the channel estimation is first performed on the current frame of the receiving end to obtain the channel matrix; then the channel matrix is subjected to singular value decomposition to obtain a diagonal matrix; and then all singular values are calculated. The ratio of the maximum singular value to the minimum singular value, using 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, 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. This kind of condition number is used as the correlation index between channels, by judging the size of the condition number of the current frame and the threshold value of the preset condition number, and determining whether the current frame is an LOS channel type or an NLOS channel type according to the judgment result, and finally according to 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. Instructions are stored in the computer-readable storage medium. When the computer-readable storage medium is run on a computer, it causes the computer to execute any one of the above-mentioned embodiments. The described transmission mode adaptive method based on inter-channel correlation. Wherein, the described transmission mode adaptive method based on inter-channel correlation includes:

Perform channel estimation on the current frame at the receiving end to obtain a channel matrix;

Singular value decomposition is performed 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 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 magnitude of the correlation between channels;

Judging whether the condition number is greater than the preset condition number threshold value, 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 a line-of-sight LOS channel or Non-line-of-sight NLOS channel.

It can be seen that, through a computer-readable storage medium provided by an embodiment of the present invention, the channel estimation is first performed on the current frame at the receiving end to obtain a channel matrix; then the channel matrix is subjected to singular value decomposition to obtain a diagonal matrix; and then all The ratio of the largest singular value to the smallest singular value in the 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 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. This kind of condition number is used as the correlation index between channels, by judging the size of the condition number of the current frame and the threshold value of the preset condition number, and determining whether the current frame is an LOS channel type or an NLOS channel type according to the judgment result, and finally according to 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 article, 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 that there is a relationship between these entities or operations. any such actual relationship or order exists between them. Furthermore, the term "comprises", "comprises" or any other variation thereof is intended to cover a non-exclusive inclusion such that a process, method, article, or apparatus comprising a set of elements includes not only those elements, but also includes elements not expressly listed. other elements of or also include elements inherent in such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the process, method, article or apparatus comprising said element.

Each embodiment in this specification is described in a related manner, the same and similar parts of each embodiment can 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, and for relevant parts, please refer to part of the description of the method embodiments.

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 principles of the present invention are included in the protection scope of the present invention.

Claims (10)

1. a kind of transmission mode adaptive approach based on inter-channel correlation, it is characterised in that methods described includes：

Channel estimation is carried out to the present frame of receiving terminal, obtains channel matrix；

Singular value decomposition is carried out to the channel matrix, obtains diagonal matrix, diagonal element is described in the diagonal matrix The singular value of channel matrix；

Calculate maximum singular value and the ratio of minimum singular value in all singular values, the bar using the ratio as the present frame Number of packages, the conditional number characterize the size of the correlation of interchannel；

Judge whether the conditional number is more than preparatory condition number threshold value, obtain judged result, it is determined that with the judged result pair The channel type for the present frame answered, and the transmission mode of the present frame is determined according to the channel type, wherein, it is described Channel type includes sighting distance LOS channels or non line of sight NLOS channels.

2. according to the method for claim 1, it is characterised in that it is described that singular value decomposition is carried out to the channel matrix, obtain To diagonal matrix, the singular value of channel matrix described in diagonal element representation in the diagonal matrix, including：

According to formula

Singular value decomposition is carried out to the channel matrix, obtains diagonal matrix, wherein, m × m, m × n, n × n difference representing matrixs Order, m represents transmitting terminal antenna number, and n represents receiving terminal antenna number, and H represents the channel matrix, and U represents left unitary matrix, U1 ..., Um ..., U_m(m-1)+1..., U_m×mThe element of respectively described left unitary matrix, S represent diagonal matrix, and S1 ..., Sm × n are respectively institute The element of diagonal matrix is stated, represents the singular value of the channel matrix, H represents right unitary matrix, V1 ..., Vn ..., V_n(n-1)+1..., V_n×nThe element of respectively described left unitary matrix.

3. according to the method for claim 1, it is characterised in that described to judge whether the conditional number is more than preparatory condition number Threshold value, judged result is obtained, it is determined that the channel type of the present frame corresponding with the judged result, and according to the letter Road type determines the transmission mode of the present frame, including：

Judge whether the conditional number is more than preparatory condition number threshold value, obtain judged result；

If the judged result, which is the conditional number, is more than the preparatory condition number threshold value, it is determined that with the judged result The channel type of the corresponding present frame is the LOS channels, and the transmission mould of space diversity is used to the LOS channels Formula；

If the judged result be the conditional number be less than or equal to the preparatory condition number threshold value, it is determined that with it is described The channel type of the present frame corresponding to judged result is the NLOS channels, and uses spatial reuse to the NLOS channels Transmission mode.

4. according to the method for claim 1, it is characterised in that the determination is corresponding with the judged result described current The channel type of frame, and after determining according to the channel type transmission mode of the present frame, methods described also includes：

Using the transmission mode of the present frame as the frame in the predetermined period adjacent with after the present frame corresponding to biography Defeated pattern.

5. a kind of transmission mode self-reacting device based on inter-channel correlation, it is characterised in that described device includes：

Estimation module, for carrying out channel estimation to the present frame of receiving terminal, obtain channel matrix；

Decomposing module, for carrying out singular value decomposition to the channel matrix, obtain diagonal matrix, it is diagonal in the diagonal matrix Element be the channel matrix singular value；

Computing module, for calculating maximum singular value and the ratio of minimum singular value in all singular values, using the ratio as The conditional number of the present frame, the conditional number characterize the size of the correlation of interchannel；

Judge module, for judging whether the conditional number is more than preparatory condition number threshold value, judged result is obtained, it is determined that and institute The channel type of the present frame corresponding to judged result is stated, and the transmission mould of the present frame is determined according to the channel type Formula, wherein, the channel type includes sighting distance LOS channels or non line of sight NLOS channels.

6. device according to claim 5, it is characterised in that the decomposing module, be specifically used for：

According to formula

Singular value decomposition is carried out to the channel matrix, obtains diagonal matrix, wherein, m × m, m × n, n × n difference representing matrixs Order, m represents transmitting terminal antenna number, and n represents receiving terminal antenna number, and H represents the channel matrix, and U represents left unitary matrix, U1 ..., Um ..., U_m(m-1)+1..., U_m×mThe element of respectively described left unitary matrix, S represent diagonal matrix, and S1 ..., Sm × n are respectively institute The element of diagonal matrix is stated, represents the singular value of the channel matrix, H represents right unitary matrix, V1 ..., Vn ..., V_n(n-1)+1..., V_n×nThe element of respectively described left unitary matrix.

7. device according to claim 5, it is characterised in that the judge module, including：

Judging submodule, for judging whether the conditional number is more than preparatory condition number threshold value, obtain judged result；

First determination sub-module, if being that the conditional number is more than the preparatory condition number threshold value for the judged result, The channel type for then determining the present frame corresponding with the judged result is the LOS channels, and the LOS channels are adopted With the transmission mode of space diversity；

Second determination sub-module, if being that the conditional number is less than or equal to the preparatory condition number for the judged result Threshold value, it is determined that the channel type of the present frame corresponding with the judged result is the NLOS channels, and to described NLOS channels use the transmission mode of spatial reuse.

8. device according to claim 5, it is characterised in that described device also includes：

Determining module, for using the transmission mode of the present frame as in the predetermined period adjacent with after the present frame Transmission mode corresponding to frame.

9. a kind of electronic equipment, it is characterised in that including processor, communication interface, memory and communication bus, wherein, it is described Processor, the communication interface, the memory complete mutual communication by the communication bus；

The memory, for depositing computer program；

The processor, during for performing the program deposited on the memory, realize any described sides of claim 1-5 Method step.

10. a kind of computer-readable recording medium, it is characterised in that the computer-readable recording medium internal memory contains computer Program, when the computer program is executed by processor, realize any described method and steps of claim 1-5.