CN105981344B

CN105981344B - A kind of pilot sending method, channel estimation methods and device

Info

Publication number: CN105981344B
Application number: CN201480075375.2A
Authority: CN
Inventors: 张佳胤; 徐正勳; 李奇真
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2014-04-18
Filing date: 2014-04-18
Publication date: 2019-10-25
Anticipated expiration: 2034-04-18
Also published as: CN105981344A; WO2015158003A1

Abstract

The present invention provides a kind of pilot sending method, channel estimation methods and devices, it is related to wireless communication technology field, it is able to solve the lower problem of throughput comprising following steps: frequency pilot sign matrix (S101) is generated according to the number for the empty time stream for sending signal；It is obtained according to the channel width for sending signal and sends the corresponding pilot frequency sequence (S102) of signal；Pilot matrix (S103) is generated according to frequency pilot sign matrix and pilot frequency sequence；Determine pilot tone insertion position (S104) of each group frequency pilot sign in corresponding empty time stream in orthogonal frequency division multiplexing (OFDM) symbol；Each group frequency pilot sign is inserted into the pilot tone insertion position in each corresponding empty time stream respectively, each empty time stream (S105) after obtaining pilot tone insertion；Each empty time stream after insertion pilot tone is sent to receiving end (S106)；Pilot reception value is extracted in receiving end pilot tone insertion position according to the pre-stored data from the empty time stream received, carries out channel estimation according to pilot frequency sequence and pilot reception value.The present invention is sent for pilot tone and channel estimation.

Description

Pilot frequency sending method, channel estimation method and device

Technical Field

The present invention relates to the field of wireless communication technologies, and in particular, to a pilot frequency transmission method, a channel estimation method, and a channel estimation device.

Background

A WLAN (Wireless Local Area Network) uses a MIMO (Multi-input Multi-output) technology to transmit data, and a receiving end needs to perform channel estimation through pilot frequency when receiving a data stream sent by a sending end.

In order to enable a receiving end to effectively perform channel estimation in a high doppler Frequency shift environment, the existing WLAN standard protocol adopts a space-time design scheme for pilot frequencies, i.e., the original number of pilot frequencies is kept unchanged, no additional overhead is added, only the Frequency domain position of the pilot Frequency is changed, and a certain number of OFDM (Orthogonal Frequency Division Multiplexing) symbol periods are usedEach subcarrier location within a cell is assigned a pilot. The transmitting end disperses the pilot frequency in the data frame, and then the receiving end extracts the dispersed pilot frequency to carry out channel estimation. When space-time flow number (N) is adopted_STS) Space Time block code of 2 (Space Time block code: STBC), each pilot position contains two symbols, and to avoid excessive pilot symbol overhead, frequency domain interpolation is used to insert pilots (even subcarriers or odd subcarriers) at only half of the subcarrier positions.

The existing WLAN standard protocol can only support two space-time streams at most, and more space-time stream conditions are not considered, so that the throughput rate of a channel is low.

Disclosure of Invention

The invention provides a pilot frequency sending method, a channel estimation method and a channel estimation device, which can solve the problem of low throughput rate.

In order to achieve the purpose, the invention adopts the following technical scheme:

in a first aspect, an apparatus for pilot transmission is provided, the apparatus comprising:

the symbol matrix generating unit is used for generating a pilot frequency symbol matrix according to the number of the space-time streams of the transmitted signals, wherein the pilot frequency symbol matrix is a row orthogonal matrix;

a pilot sequence acquiring unit, configured to acquire a pilot sequence corresponding to the transmission signal according to a channel bandwidth of the transmission signal;

a pilot matrix generating unit, configured to generate a pilot matrix according to the pilot symbol matrix and the pilot sequence, where each row of the pilot matrix is a group of pilot symbols;

an insertion position obtaining unit, configured to determine a pilot insertion position of each group of pilot symbols in an orthogonal frequency division multiplexing OFDM symbol on a corresponding space-time stream;

the inserting operation unit is used for respectively inserting each group of pilot symbols into the pilot inserting positions on each corresponding space-time stream to obtain each space-time stream after the pilot is inserted;

and the sending unit is used for sending each space-time stream after the pilot frequency is inserted to a receiving end.

With reference to the first aspect, in a first possible implementation manner, the pilot sequence acquiring unit is specifically configured to:

selecting a corresponding pilot frequency sequence mapping algorithm according to the channel bandwidth;

and acquiring the pilot sequence corresponding to the sending signal by using the determined pilot sequence mapping algorithm.

With reference to the first possible implementation manner of the first aspect, in a second possible implementation manner, the selecting, by the pilot sequence acquiring unit, a corresponding pilot sequence mapping algorithm according to the channel bandwidth includes:

if the channel bandwidth is 20MHz, determining a first pilot sequence mapping formula as the pilot sequence mapping algorithm, where the first pilot sequence mapping formula includes:

or, if the channel bandwidth is 40MHz, determining a second pilot sequence mapping formula as the pilot sequence mapping algorithm, where the second pilot sequence mapping formula includes:

or, if the channel bandwidth is 80MHz, determining a third pilot sequence mapping formula as the pilot sequence mapping algorithm, where the third pilot sequence mapping formula includes:

or, if the channel bandwidth is 160MHz continuously, determining a fourth pilot sequence mapping formula as the pilot sequence mapping algorithm, where the fourth pilot sequence mapping formula includes:

where N denotes the nth OFDM symbol, k denotes the kth subcarrier, psi denotes the value of an element in the pilot sequence, N_STSRepresenting the number of said space-time streams.

With reference to the first aspect, in a third possible implementation manner, the pilot matrix generating unit is specifically configured to:

and forming the pilot matrix according to the pilot symbol matrix and the pilot sequence, wherein the element of the ith row and the jth column of the pilot matrix is the value obtained by multiplying the element of the ith row and the jth column of the pilot symbol matrix by the element in the pilot sequence.

With reference to the first aspect, in a fourth possible implementation manner, the insertion position obtaining unit is specifically configured to:

continuously setting insertion positions with the number equal to the column number of the pilot matrix from a preset subcarrier of a preset OFDM symbol, and then continuously setting the insertion positions with the number equal to the column number of the pilot matrix on the OFDM symbol with the time domain interval of the preset subcarrier of the preset OFDM symbol and the subcarrier with the frequency domain interval of the preset carrier interval;

and repeating the operations of moving and setting the insertion position until at least one pilot frequency appears on each subcarrier in a preset pilot frequency period, and acquiring and recording the pilot frequency insertion position of each group of pilot frequency symbols in the OFDM symbols on the corresponding space-time stream.

In a second aspect, an apparatus for channel estimation is provided, the apparatus comprising:

a receiving unit, configured to receive each space-time stream, and obtain a channel bandwidth and the number of space-time streams;

a symbol matrix construction unit, configured to generate a pilot symbol matrix according to the number of the space-time streams, where the pilot symbol matrix is a row orthogonal matrix;

a pilot sequence constructing unit, configured to obtain a corresponding pilot sequence according to the channel bandwidth;

an extracting unit, configured to extract a pilot receiving value from a corresponding OFDM symbol of each space-time stream according to a pilot insertion position, where the pilot insertion position is pre-stored;

and a channel estimation unit, configured to perform channel estimation on the transmission signal according to the pilot reception value, the pilot sequence, and the pilot symbol matrix.

With reference to the second aspect, in a first possible implementation manner, the pilot sequence constructing unit is specifically configured to:

and acquiring the corresponding pilot frequency sequence by utilizing the determined pilot frequency sequence mapping algorithm.

With reference to the first possible implementation manner of the second aspect, in a second possible implementation manner, the selecting, by the pilot sequence constructing unit, a corresponding pilot sequence mapping algorithm according to the channel bandwidth includes:

With reference to the second aspect, in a third possible implementation manner, the channel estimation unit is specifically configured to:

and taking the pilot frequency receiving value, the pilot frequency sequence and the pilot frequency symbol matrix as input values of a channel estimation algorithm, and obtaining an estimated value of channel response by utilizing the channel estimation algorithm.

With reference to the third possible implementation manner of the second aspect, in a fourth possible implementation manner, the channel estimation algorithm includes:

wherein,represents the estimated value of the channel response, Y represents the pilot reception value, x represents the pilot sequence, and P represents the pilot symbol matrix.

In a third aspect, a pilot transmitting method is provided, where the method includes:

generating a pilot frequency symbol matrix according to the number of space-time streams of a transmitted signal, wherein the pilot frequency symbol matrix is a row orthogonal matrix;

acquiring a pilot frequency sequence corresponding to the sending signal according to the channel bandwidth of the sending signal;

generating a pilot frequency matrix according to the pilot frequency symbol matrix and the pilot frequency sequence, wherein each row of the pilot frequency matrix is a group of pilot frequency symbols;

determining the pilot frequency inserting position of each group of the pilot frequency symbols in the orthogonal frequency division multiplexing OFDM symbols on the corresponding space-time stream;

inserting each group of pilot symbols into the pilot insertion positions on each corresponding space-time stream respectively to obtain each space-time stream with the pilot inserted;

and transmitting each space-time stream after pilot frequency insertion to a receiving end.

With reference to the third aspect, in a first possible implementation manner, the obtaining a pilot sequence corresponding to the transmission signal according to the channel bandwidth of the transmission signal includes:

With reference to the first possible implementation manner of the third aspect, in a second possible implementation manner, the selecting, according to the channel bandwidth, a corresponding pilot sequence mapping algorithm includes:

With reference to the third aspect, in a third possible implementation manner, the generating a pilot matrix according to the pilot symbol matrix and the pilot sequence includes:

With reference to the third aspect, in a fourth possible implementation manner, the determining positions of pilot insertion in each group of the pilot symbols in an orthogonal frequency division multiplexing OFDM symbol on a corresponding space-time stream includes:

In a fourth aspect, a channel estimation method is provided, the method comprising:

receiving each space-time stream, and acquiring the channel bandwidth and the number of the space-time streams;

generating a pilot frequency symbol matrix according to the number of the space-time streams, wherein the pilot frequency symbol matrix is a row orthogonal matrix;

acquiring a corresponding pilot frequency sequence according to the channel bandwidth;

extracting a pilot frequency receiving value from the corresponding OFDM symbol of each space-time stream according to a pilot frequency inserting position, wherein the pilot frequency inserting position is pre-stored;

and performing channel estimation on the sending signal according to the pilot frequency receiving value, the pilot frequency sequence and the pilot frequency symbol matrix.

With reference to the fourth aspect, in a first possible implementation manner, the acquiring a corresponding pilot sequence according to the channel bandwidth includes:

With reference to the first possible implementation manner of the fourth aspect, in a second possible implementation manner, the selecting, according to the channel bandwidth, a corresponding pilot sequence mapping algorithm includes:

With reference to the fourth aspect, in a third possible implementation manner, the performing channel estimation on the transmission signal according to the pilot reception value, the pilot sequence, and the pilot symbol matrix includes:

With reference to the third possible implementation manner of the fourth aspect, in a fourth possible implementation manner, the channel estimation algorithm includes:

In a fifth aspect, a pilot transmitting apparatus is provided, and the pilot transmitting apparatus includes: a bus, and a processor, a memory, a transmitter, and an interface connected to the bus, wherein the interface is for communicating with an external device; the memory to store instructions, the processor to execute the instructions to:

and transmitting each space-time stream after the pilot frequency is inserted to a receiving end through the transmitter.

With reference to the fifth aspect, in a first possible implementation manner, the processor executes the instructions to specifically:

With reference to the first possible implementation manner of the fifth aspect, in a second possible implementation manner, the executing, by the processor, the instruction to select a corresponding pilot sequence mapping algorithm according to the channel bandwidth includes:

With reference to the fifth aspect, in a third possible implementation manner, the processor executes the instructions to specifically:

With reference to the fifth aspect, in a fourth possible implementation manner, the processor executes the instructions to specifically:

In a sixth aspect, there is provided a channel estimation apparatus, comprising: a bus, and a processor, a memory, a receiver, and an interface connected to the bus, wherein the interface is for communicating with an external device; the memory to store instructions, the processor to execute the instructions to:

receiving each space-time stream through the receiver, and acquiring the channel bandwidth and the number of the space-time streams;

With reference to the sixth aspect, in a first possible implementation manner, the processor executes the instructions to specifically:

With reference to the first possible implementation manner of the sixth aspect, in a second possible implementation manner, the executing, by the processor, the instruction to select a corresponding pilot sequence mapping algorithm according to the channel bandwidth includes:

With reference to the sixth aspect, in a third possible implementation manner, the processor executes the instructions to specifically:

With reference to the third possible implementation manner of the sixth aspect, in a fourth possible implementation manner, the channel estimation algorithm includes:

The invention provides a pilot frequency sending method, a channel estimation method and a device, which realize the support of using more space-time streams by adjusting the insertion position of a pilot frequency in an Orthogonal Frequency Division Multiplexing (OFDM) symbol on the space-time streams; compared with the prior art, the pilot frequency sending method provided by the invention considers the condition of multiple space-time streams, so that the sent signal has higher throughput rate.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

Fig. 1 is a schematic structural diagram of a pilot sending apparatus according to an embodiment of the present invention;

fig. 2 is a schematic diagram of a structure of a transmission signal according to an embodiment of the present invention;

fig. 3 is a schematic structural diagram of a channel estimation apparatus according to an embodiment of the present invention;

fig. 4 is a flowchart illustrating a pilot sending method according to an embodiment of the present invention;

fig. 5 is a schematic diagram illustrating an effect of determining a pilot insertion position according to an embodiment of the present invention;

FIG. 6 shows a pilot matrix Q₄Respectively inserted into the insertion positions of four space-time streamsA schematic diagram;

fig. 7 is a flowchart illustrating a channel estimation method according to an embodiment of the present invention;

fig. 8 is a schematic structural diagram of a pilot sending apparatus according to an embodiment of the present invention;

fig. 9 is a schematic structural diagram of a channel estimation device according to an embodiment of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

An embodiment of the present invention provides a pilot sending apparatus 800, as shown in fig. 1, the pilot sending apparatus 800 includes:

a symbol matrix generation unit 801, a pilot sequence acquisition unit 802, a pilot matrix generation unit 803, an insertion position acquisition unit 804, an insertion operation unit 805, and a transmission unit 806.

Note that the dotted lines indicate that the units may or may not have a direct connection relationship, for example, the pilot matrix generation unit 803 may or may not notify the insertion position acquisition unit 804 after acquiring the pilot matrix.

Specifically, the symbol matrix generating unit 801 is configured to generate a pilot symbol matrix according to the number of space-time streams of the transmission signal.

Wherein, the pilot frequency symbol matrix is a row orthogonal matrix; the transmission signal is a Data field included in a PPDU (PLCP Protocol Data Unit) of a WLAN (Wireless Local Area Network).

Exemplarily, the WLAN employs a spatial multiplexing technique, where spatial multiplexing refers to independently transmitting data streams composed of different signals in parallel through multiple antennas in a wireless channel. Wherein, each data stream composed of the signals transmitted in parallel is called space-time stream.

In a high mobility environment, the existing WLAN standard protocol can only support 2 space-time streams employing space-time block code (STBC) at most, and the situation of more space-time streams employing beamforming is not considered, so that throughput is limited. In addition, the existing WLAN standard protocol adopts a frequency domain interpolation method when transmitting two space-time streams, and the frequency domain interpolation method is applicable when the subcarrier spacing is small, but not applicable when the subcarrier spacing is large.

In the embodiment of the present invention, the number of the space-time streams for transmitting signals is not limited, and may be equal to 2 or greater than 2.

Determining the number of pilot frequencies of time domain expansion according to the number of the space-time streams of the sending signal, wherein the number of the pilot frequencies of the time domain expansion can be equal to the number of the space-time streams; generating a pilot symbol matrix, namely generating a row orthogonal matrix (pairwise orthogonal between rows of the matrix) with the row number equal to the number of space-time streams and the column number equal to the number of pilot frequency of time domain expansion; for example: if the number of space-time streams is 4 and the number of pilots for time domain spreading is also 4, the generated pilot symbol matrix may be:

in particular, if the number of space-time streams is 1, the symbol matrix degenerates to 1.

It should be noted that the number of the time domain expanded pilot frequency may also be larger than the number of the space-time stream, a row orthogonal matrix whose row number and column number are both equal to the number of the time domain expanded pilot frequency may be generated first, and a sub-matrix whose column number is equal to the number of the time domain expanded pilot frequency and row number is equal to the number of the space-time stream in the matrix is extracted as a symbol matrix; for example: if the number of the space-time streams is 3, the number of the pilot frequency of the time domain extension may be 4, and the symbol matrix may adopt P₄The first 3 rows of.

Specifically, the pilot sequence acquiring unit 802 is configured to acquire a pilot sequence corresponding to a transmission signal according to a channel bandwidth of the transmission signal;

illustratively, there is a one-to-one correspondence between the pilot sequences and the channel bandwidths of the transmission signals, so that the pilot sequences corresponding to the transmission signals can be obtained through the channel bandwidths of the transmission signals.

The corresponding pilot sequence is obtained according to the channel bandwidth, a corresponding pilot sequence mapping algorithm may be selected according to the channel bandwidth, and the pilot sequence corresponding to the transmission signal is obtained by using the determined pilot sequence mapping algorithm.

Wherein, the channel bandwidth of the transmitted signal currently comprises 20MHz, 40MHz, 80MHz, 160 MHz; and as the WLAN standard protocol improves, the transmission signal may have other channel bandwidths, which is not limited herein.

The selecting a corresponding pilot sequence mapping algorithm according to the channel bandwidth may include:

if the channel bandwidth is 20MHz, determining a first pilot sequence mapping formula as a pilot sequence mapping algorithm, where the first pilot sequence mapping formula includes:

or, if the channel bandwidth is 40MHz, determining a second pilot sequence mapping formula as a pilot sequence mapping algorithm, where the second pilot sequence mapping formula includes:

or, if the channel bandwidth is 80MHz, determining a third pilot sequence mapping formula as a pilot sequence mapping algorithm, where the third pilot sequence mapping formula includes:

or, if the channel bandwidth is 160MHz continuously, determining a fourth pilot sequence mapping formula as a pilot sequence mapping algorithm, where the fourth pilot sequence mapping formula includes:

where N denotes the nth OFDM symbol, k denotes the kth subcarrier, psi denotes the value of an element in the pilot sequence, N_STSRepresenting the number of space-time streams.

It should be noted that the above listed pilot sequence mapping formula is only exemplary, but not limited thereto, and the present invention may also obtain the corresponding pilot sequence through other algorithms, which is not limited herein.

Specifically, the pilot matrix generating unit 803 is configured to generate a pilot matrix according to the pilot symbol matrix and the pilot sequence.

Wherein each row of the pilot matrix is a group of pilot symbols; the number of rows and columns of the pilot matrix is respectively the same as the number of rows and columns of the pilot symbol matrix, i.e., the number of rows of the pilot matrix is equal to the number of space-time streams, and the number of columns is equal to the number of time-domain spread pilots.

Illustratively, each row of the pilot matrix is formed by multiplying a non-0 element of the first pilot sequence by each row of the pilot symbol matrix. Because the number of rows of the pilot matrix is equal to the number of space-time streams, each space-time stream can independently use a group of pilot symbols; and because each group of pilot symbols are orthogonal, the receiving end can distinguish and identify different space-time streams through the received different pilot symbols.

An insertion position obtaining unit 804, configured to determine pilot insertion positions of each group of pilot symbols in an orthogonal frequency division multiplexing OFDM symbol on a corresponding space-time stream;

fig. 2 is a schematic diagram of a structure of a transmission signal. As shown in fig. 2, an OFDM (Orthogonal Frequency Division Multiplexing) symbol refers to a radio transmission resource composed of all available subcarriers in a transmission signal for a certain duration. The symbol duration and the subcarrier spacing are in inverse relationship.

As shown in fig. 2, each pilot frequency is distributed on each subcarrier of each OFDM symbol of the transmission signal, and the pilot frequency distribution may be uniform distribution or non-uniform distribution; taking the first pilot as an example, the subcarrier carrying the first pilot in the OFDM symbol is the insertion position of the first pilot in the OFDM symbol.

For example, determining the positions of the pilot insertion in the OFDM symbol on the corresponding space-time stream for each group of pilot symbols may be performed by: continuously setting insertion positions with the number equal to the column number of a pilot matrix from a preset subcarrier of a preset OFDM symbol, and then continuously setting the insertion positions with the number equal to the column number of the pilot matrix on the OFDM symbol with the column number of the pilot matrix in the time domain interval of the preset subcarrier of the preset OFDM symbol and the subcarrier with the column number of the pilot matrix in the frequency domain interval of the preset carrier interval;

and repeating the operations of moving and setting the insertion positions until at least one pilot frequency appears on each subcarrier in a preset pilot frequency period, and acquiring and recording the pilot frequency insertion positions of each group of pilot frequency symbols in the OFDM symbols on the corresponding space-time stream.

The preset OFDM symbol and the preset subcarrier may be initial insertion positions set by default in the system, such as a first subcarrier of a first OFDM symbol in a preset pilot period; the preset pilot frequency period can be a time frequency block pilot frequency period; the preset carrier interval can be a fixed interval value (i.e. pilot frequency distribution is uniform) or a variable interval value (pilot frequency distribution is non-uniform) set by default of the system, the specific selection is determined according to the position of the subcarrier in the space-time stream, and the use requirement can be met as long as the pilot frequency appears on each subcarrier at least once in the preset pilot frequency period; and the above settings are exemplary only, including but not limited to.

It should be noted that, the pilot insertion position may be recorded and stored after the pilot insertion position, so that the receiving end obtains the pilot insertion position, and extracts the pilot inserted in the subcarrier corresponding to the OFDM symbol from the received space-time stream.

Specifically, the inserting operation unit 805 is configured to insert each group of pilot symbols into a pilot inserting position on each corresponding space-time stream, so as to obtain each space-time stream into which a pilot is inserted;

specifically, the sending unit 806 is configured to send each space-time stream with the pilot inserted therein to the receiving end.

Illustratively, after receiving each space-time stream, the receiving end extracts a pilot receiving value from a pilot insertion position corresponding to the space-time stream, and then performs channel estimation on the transmission signal in combination with other necessary parameters acquired by itself.

The embodiment of the invention provides a pilot frequency sending device, which obtains a pilot frequency symbol matrix and a pilot frequency sequence corresponding to a sent signal according to the number of space-time streams of the sent signal and a channel bandwidth, then obtains the pilot frequency matrix according to the pilot frequency symbol matrix and the pilot frequency sequence, inserts each group of pilot frequency symbols into corresponding pilot frequency insertion positions in each space-time stream of the sent signal after determining the pilot frequency insertion positions of each group of pilot frequency symbols in the pilot frequency matrix in Orthogonal Frequency Division Multiplexing (OFDM) symbols of the sent signal, and finally sends each space-time stream after inserting the pilot frequency to a receiving end. The number of the space-time streams for transmitting the signal is not limited, that is, the number of the space-time streams may be equal to or greater than 2, so that the pilot frequency transmission method provided by the embodiment of the present invention has a higher throughput rate compared to the prior art in which multiple space-time streams are considered.

An embodiment of the present invention provides a channel estimation apparatus 900, as shown in fig. 3, the channel estimation apparatus 900 includes:

receiving section 901, symbol matrix constructing section 902, pilot sequence constructing section 903, extracting section 904, and channel estimating section 905.

Specifically, the receiving unit 901 is configured to receive each space-time stream, and obtain a channel bandwidth and the number of space-time streams.

Receiving each space-time stream, which may be each space-time stream sent by a pilot frequency sending device; the number of the acquired channel bandwidth and the number of the space-time streams may be the number of the channel bandwidth and the space-time streams acquired from the pilot transmitting apparatus, or the number of the channel bandwidth and the number of the space-time streams agreed with the pilot transmitting apparatus acquired from the storage of the channel estimating apparatus 900.

Specifically, the symbol matrix constructing unit 902 is configured to generate a pilot symbol matrix according to the number of space-time streams.

Wherein, the pilot symbol matrix is a row orthogonal matrix.

Exemplarily, the number of the pilot frequency of the time domain extension is determined according to the number of the space-time stream, and the number of the pilot frequency of the time domain extension may be equal to the number of the space-time stream; generating a pilot symbol matrix, namely generating a row orthogonal matrix (pairwise orthogonal between rows of the matrix) with the row number equal to the number of space-time streams and the column number equal to the number of pilot frequency of time domain expansion; for example: if the number of space-time streams is 4 and the number of pilots for time domain spreading is also 4, the generated pilot symbol matrix may be:

in particular, if the number of space-time streams is 1, the symbol matrix degenerates to 1. If the number of the pilot frequency of the time domain expansion can be larger than that of the space-time stream, a row orthogonal matrix with the row number and the column number equal to that of the pilot frequency of the time domain expansion can be generated first, and a sub-matrix with the column number equal to that of the pilot frequency of the time domain expansion and the row number equal to that of the space-time stream in the matrix is extracted as a symbol matrix; for example: if the number of the space-time streams is 3, the number of the pilot frequency of the time domain extension may be 4, and the symbol matrix may adopt P₄The first 3 rows of.

It should be noted that the strategy adopted by the symbol matrix constructing unit 902 to generate the symbol matrix needs to ensure that the symbol matrix is completely consistent with the pilot sending apparatus, that is, the symbol matrix acquired by the symbol matrix constructing unit 902 is ensured to be completely consistent with the symbol matrix acquired by the pilot sending apparatus.

Optionally, in order to ensure that the symbol matrix acquired by the symbol matrix constructing unit 902 is completely consistent with the symbol matrix acquired by the pilot sending apparatus, the symbol matrix constructing unit 902 may also directly acquire the symbol matrix generated and sent by the pilot sending apparatus; and the specific manner of obtaining the symbol matrix is not limited herein.

Specifically, the pilot sequence constructing unit 903 is configured to obtain a corresponding pilot sequence according to a channel bandwidth.

For example, the corresponding pilot sequence is obtained according to the channel bandwidth, a corresponding pilot sequence mapping algorithm may be selected according to the channel bandwidth, and the pilot sequence corresponding to the transmission signal is obtained by using the determined pilot sequence mapping algorithm.

Wherein, the channel bandwidth currently comprises 20MHz, 40MHz, 80MHz and 160 MHz; and with the improvement of the WLAN standard protocol, there may be other channel bandwidths as well, which is not limited herein.

It should be noted that the above listed pilot sequence mapping formula is only exemplary, but not limited thereto, and the present invention may also obtain the corresponding pilot sequence through other algorithms, which is not limited herein. And the strategy adopted by the pilot sequence constructing unit 903 to acquire the pilot sequence needs to ensure that the pilot sequence is completely consistent with the pilot sending device, that is, the pilot sequence acquired by the pilot sequence constructing unit 903 is ensured to be completely consistent with the pilot sequence acquired by the pilot sending device.

Optionally, in order to ensure that the pilot sequence acquired by the pilot sequence constructing unit 903 is completely consistent with the pilot sequence acquired by the transmitting end, the pilot sequence constructing unit 903 may also directly acquire the generated and transmitted pilot sequence; and the specific way of acquiring the pilot sequence is not limited herein.

Specifically, the extracting unit 904 is configured to extract a pilot receiving value from a corresponding OFDM symbol of each space-time stream according to the pilot inserting position.

Wherein, the pilot insertion position is pre-stored, and according to the pilot insertion position, the extraction unit 904 may determine the pilot insertion position in the corresponding OFDM symbol of each space-time stream, further extract the pilot, and obtain a pilot received value;

specifically, the channel estimation unit 905 is configured to perform channel estimation on the transmission signal according to the pilot receiving value, the pilot sequence, and the pilot symbol matrix.

Illustratively, the channel estimation unit 905 obtains an estimated value of a channel response by using a channel estimation algorithm using the pilot reception value, the pilot sequence, and the pilot symbol matrix as input values of the channel estimation algorithm.

The channel estimation algorithm comprises the following steps:

wherein,denotes an estimated value of a channel response, Y denotes a pilot reception value, x denotes a pilot sequence, and P denotes a pilot symbol matrix.

Take 2 space-time streams as an example, in the Nth_rOn a single subcarrier on each receiving antenna, the frequency domain expression of the received signal is as follows:

Y＝HPx+W；

wherein, for the receiving antenna i at t_jA value received at a time;let it be assumed here that₁And t₂The channel characteristics at time H are unchanged; x is a pilot frequency; p is a pilot symbol matrix (two-dimensional orthogonal matrix); w is a two-dimensional noise matrix.

Through LS (Least squares) channel estimation, the channel estimation value can be expressed as follows:

estimated toA store is made for demodulating the data using coherent detection. When the next pilot frequency period comes, it willAnd updating the estimated new value, thereby achieving the aim of channel tracking.

The embodiment of the invention provides a channel estimation device, which extracts a pilot frequency receiving value from a space-time stream according to a pilot frequency inserting position stored in advance after the space-time stream is received, and carries out channel estimation according to the pilot frequency receiving value, an obtained pilot frequency sequence and a pilot frequency symbol matrix. Because there is no limit on the number of the space-time streams for transmitting signals, that is, the number of the space-time streams may be equal to or greater than 2, the pilot frequency transmission method provided by the embodiment of the present invention has a higher throughput rate compared to the prior art in which multiple space-time streams are considered.

An embodiment of the present invention provides a pilot sending method, as shown in fig. 4, the method includes the following specific steps:

s101, a pilot frequency symbol matrix is generated according to the number of the space-time streams of the transmitted signals.

Wherein, the pilot frequency symbol matrix is a row orthogonal matrix; the sending signal refers to a data field contained in a PPDU of the WLAN; in the embodiment of the present invention, the number of the space-time streams for transmitting signals is not limited, and may be equal to 2 or greater than 2.

Exemplarily, the number of pilot frequencies of the time domain extension is determined according to the number of space-time streams of the transmission signal, and the number of pilot frequencies of the time domain extension may be equal to the number of space-time streams; generating a pilot symbol matrix, namely generating a row orthogonal matrix (pairwise orthogonal between rows of the matrix) with the row number equal to the number of space-time streams and the column number equal to the number of pilot frequency of time domain expansion; for example: if the number of space-time streams is 4 and the number of pilots for time domain spreading is also 4, the generated pilot symbol matrix may be:

And S102, acquiring a pilot frequency sequence corresponding to the transmission signal according to the channel bandwidth of the transmission signal.

wherein,meaning that if the channel bandwidth of the transmitted signal is 20MHz, the pilot sequence is located only on-21, -7, and 21 subcarriers.

wherein,meaning that if the channel bandwidth of the transmitted signal is 40MHz, the pilot sequence is located only on-53, -25, -11, 25 and 53 subcarriers.

wherein,indicating that if the channel bandwidth of the transmitted signal is 80MHz, the pilot sequence is located only on-103, -75, -39, -11, 39, 75, and 103 subcarriers.

wherein,it means that if the channel bandwidth of the transmission signal is 160MHz, the pilot sequence is located only on the-231, -203, -167, -139, -117, -89, -53, -25, 39, 53, 89, 117, 139, 167, 203, and 231 subcarriers.

And for the discontinuous 160MHz transmission bandwidth, the pilot frequency sequence mapping algorithm of each 80MHz bandwidth is formula (3).

In particular, in equations (1), (2), (3) and (4), N denotes the nth OFDM symbol, k denotes the kth subcarrier, ψ denotes the value of an element in a pilot sequence, N_STSRepresents the number of space-time streams, floor (x) represents the largest integer no greater than x.

And the values of psi are shown in table 1:

TABLE 1

Bandwidth of	ψ₀	ψ₁	ψ₂	ψ₃	ψ₄	ψ₅	ψ₆	ψ₇
									20MHz	1	1	1	-1
40MHz	1	1	1	-1	-1	1
									80/160MHz	1	1	1	-1	-1	1	1	1

For the above-mentioned transmission signals with 20MHZ, 40MHZ, 80MHZ and 160MHZ bandwidths, the signal of the iTx transmission chain can be expressed as:

wherein,indicating the number of data sub-carriers, N_STS，totalRepresents the total number of space-time streams,representing the time-domain windowing function, N_SRIndicating the sequence number, N, of the highest data subcarrier in a segment_userIndicating the number of users who use the time-frequency users at the same time,a spatial mapping matrix is represented on the sub-carrier k,the definitions of (A) and (B) are shown in formulas (1) to (4).

p_nIs performed in a string with a basic sequence of 127 elementsThe sequence generated by cyclic shift, the base sequence can be represented as follows:

P_0..126v＝{1，1，1，1，-1，-1，-1，1，-1，-1，-1，-1，1，1，-1，1，-1，-1，1，1，-1，1，1，-1，1，1，1，1，1，1，-1，1，1，1，-1，1，1，-1，-1，1，1，1，-1，1，-1，-1，-1，1，-1，1，-1，-1，1，-1，-1，1，1，1，1，1，-1，-1，1，1，-1，-1，1，-1，1，-1，1，1，-1，-1，-1，1，1，-1，-1，-1，-1，1，-1，-1，，-1，1，1，1，1，-1，1，-1，1，-1，1，-1，-1，-1，-1，-1，1，-1，1，1，-1，1，-1，1，1，1，-1，-1，1，-1，-1，-1，1，1，1，-1，-1，-1，-1，-1，-1，-1}；

γ_k，BWis a parameter that controls the subcarrier rotation and is related to the signal bandwidth.

And the modulation constellation of the user u transmitted on the subcarrier k, the nth OFDM symbol and the mth space-time stream in the data domain is represented.

P_VHTLTFRepresenting a pilot symbol matrix, Δ_FIndicating the sub-carrier spacing, T, of an OFDM symbol_SYMDenotes the duration, T, of an OFDM symbol_GI，DataIndicating the duration of the guard interval, T, in an OFDM symbol_CS，VHTWhich represents the cyclic shift for each space-time stream.

For a specific explanation of the parameters in equation (5) reference may be made to the document "IEEEP802.11ac^TM-2013”。

And S103, generating a pilot matrix according to the pilot symbol matrix and the pilot sequence.

Illustratively, the element in the ith row and the jth column of the pilot matrix is a value obtained by multiplying the element in the ith row and the jth column of the pilot symbol matrix by the pilot sequence element.

Specifically, let the element of the pilot sequence of the transmission signal beThe number of space-time streams for transmitting signals is 4, and the pilot symbol matrix is:

the pilot matrix may be:

it should be noted that, since the number of rows of the pilot matrix is equal to the number of space-time streams, each space-time stream can use a group of pilot symbols independently; because each group of pilot symbols are orthogonal, the receiving end can distinguish and identify different space-time streams through the received different pilot symbols; the receiving end may be a channel estimation device.

S104, determining the pilot insertion positions of each group of pilot symbols in the orthogonal frequency division multiplexing OFDM symbols on the corresponding space-time stream.

Specifically, determining the pilot insertion position of each group of pilot symbols in the OFDM symbols on the corresponding space-time stream may be performed by: continuously setting insertion positions with the number equal to the column number of a pilot matrix from a preset subcarrier of a preset OFDM symbol, and then continuously setting the insertion positions with the number equal to the column number of the pilot matrix on the OFDM symbol with the column number of the pilot matrix in the time domain interval of the preset subcarrier of the preset OFDM symbol and the subcarrier with the column number of the pilot matrix in the frequency domain interval of the preset carrier interval;

Taking the number of the space-time streams as 4 as an example, as shown in fig. 5, the left diagram is an effect schematic diagram of the pilot insertion position in the original state, and is continuously set on a certain subcarrier; the right diagram is a schematic diagram showing the effect of the pilot insertion positions after being re-moved and arranged, and the pilot insertion positions are distributed on a plurality of subcarriers, and each group is continuously provided with 4 positions.

And S105, inserting each group of pilot symbols into the pilot insertion positions on each corresponding space-time stream respectively to obtain each space-time stream after the pilot is inserted.

Exemplarily, taking the number of space-time streams as 4 as an example, fig. 6 shows a pilot matrix Q₄I.e. each group of pilot symbols is inserted into the insertion positions of four space-time streams.

Particularly, when the number of pilot symbols corresponding to the number of null streams cannot be divided by the number of OFDM symbols in the data field of a PPDU, the number of positions of a group of insertion positions in the null streams is inevitably less than the number of pilot symbols of the pilot group, and in this case, the corresponding number of pilot symbols in a row of the pilot matrix may be selected to be inserted into the insertion positions.

And S106, transmitting each space-time stream after pilot frequency insertion to a receiving end.

After receiving each space-time stream, the receiving end extracts a pilot frequency receiving value from a pilot frequency inserting position corresponding to the space-time stream, and then performs channel estimation on a sending signal by combining other necessary parameters acquired by the receiving end.

The existing WLAN standard protocol adopts a frequency domain interpolation method when a pilot sequence is inserted into a space-time stream, but the frequency domain interpolation method cannot be applied to the situation that the subcarrier interval is large. The method adopted by the embodiment of the invention abandons a frequency domain interpolation method, and generates a pilot frequency matrix by acquiring a pilot frequency symbol matrix and a pilot frequency sequence instead, and inserts the pilot frequency into the space-time stream according to the pilot frequency matrix so that a receiving end can distinguish the space-time stream when receiving; therefore, compared with the prior art, the pilot frequency sending method provided by the embodiment of the invention does not increase extra pilot frequency overhead, is not limited by the channel subcarrier interval, and has wider application range.

An embodiment of the present invention provides a channel estimation method, as shown in fig. 7, the method includes the following specific steps:

s201, receiving each space-time stream, and acquiring a channel bandwidth and the number of the space-time streams.

Receiving each space-time stream, which may be each space-time stream sent by a receiving sending end; the number of the acquired channel bandwidth and the number of the acquired space-time streams can be the number of the acquired channel bandwidth and the acquired space-time streams from the transmitting end, or the number of the acquired channel bandwidth and the acquired space-time streams which are agreed with the transmitting end from a local storage; the transmitting end may be a pilot transmitting apparatus.

And S202, generating a pilot symbol matrix according to the number of the space-time streams.

Wherein, the pilot symbol matrix is a row orthogonal matrix.

It should be noted that the strategy adopted for generating the symbol matrix needs to ensure that the symbol matrix is completely consistent with the transmitting end, that is, the obtained symbol matrix is ensured to be completely consistent with the symbol matrix obtained by the transmitting end.

Optionally, in order to ensure that the obtained symbol matrix is completely consistent with the symbol matrix obtained by the sending end, the symbol matrix generated and sent by the sending end may also be directly obtained; and the specific manner of obtaining the symbol matrix is not limited herein.

S203, acquiring a corresponding pilot frequency sequence according to the channel bandwidth.

It should be noted that the above listed pilot sequence mapping formula is only exemplary, but not limited thereto, and the present invention may also obtain the corresponding pilot sequence through other algorithms, which is not limited herein. And the strategy adopted for acquiring the pilot sequence needs to ensure the complete consistency with the transmitting end, namely the acquired pilot sequence is ensured to be completely consistent with the pilot sequence acquired by the transmitting end.

Optionally, in order to ensure that the obtained pilot sequence is completely consistent with the pilot sequence obtained by the sending end, the pilot sequence generated and sent by the sending end may also be directly obtained; and the specific way of acquiring the pilot sequence is not limited herein.

And S204, extracting a pilot frequency receiving value from the corresponding OFDM symbol of each space-time stream according to the pilot frequency inserting position.

The pilot insertion positions are pre-stored, and according to the pilot insertion positions, the insertion positions of the pilots can be determined in the corresponding OFDM symbols of each space-time stream, and the pilots are further extracted to obtain pilot receiving values.

And S205, performing channel estimation on the transmission signal according to the pilot frequency receiving value, the pilot frequency sequence and the pilot frequency symbol matrix.

The channel estimation algorithm comprises the following steps:

Y＝HPx+W；

wherein, for the receiving antenna i at t_jA value received at a time;let it be assumed here that₁And t₂No change in channel characteristics at time H(ii) a x is a pilot frequency; p is a pilot symbol matrix (two-dimensional orthogonal matrix); w is a two-dimensional noise matrix.

The embodiment of the invention provides a channel estimation method, which comprises the steps of extracting a pilot frequency receiving value from a space-time stream according to a pilot frequency inserting position stored in advance after the space-time stream is received, and carrying out channel estimation according to the pilot frequency receiving value, an obtained pilot frequency sequence and a pilot frequency symbol matrix. Because there is no limit on the number of the space-time streams for transmitting signals, that is, the number of the space-time streams may be equal to or greater than 2, the pilot frequency transmission method provided by the embodiment of the present invention has a higher throughput rate compared to the prior art in which multiple space-time streams are considered.

An embodiment of the present invention further provides a pilot transmitting apparatus 1000, as shown in fig. 8, where the pilot transmitting apparatus 1000 includes:

a bus 1001, and a processor 1002, a memory 1003, a transmitter 1004, and an interface 1005 connected to the bus 1001, wherein the interface 1005 is used for communication with an external device;

the memory 1003 is configured to store instructions that when executed by the processor 1002 are configured to generate a pilot symbol matrix based on a number of space-time streams of a transmitted signal.

Wherein, the pilot symbol matrix is a row orthogonal matrix.

The processor 1002 executes the instructions to obtain a pilot sequence corresponding to the transmission signal according to the channel bandwidth of the transmission signal.

The processor 1002 executes the instructions to generate a pilot matrix based on the pilot symbol matrix and the pilot sequence.

Wherein each row of the pilot matrix is a set of pilot symbols.

The processor 1002 executes the instructions to determine pilot insertion positions of each set of pilot symbols in an orthogonal frequency division multiplexing, OFDM, symbol on a corresponding space-time stream.

The processor 1002 executes the instructions to further insert each group of pilot symbols into a pilot insertion position on each corresponding space-time stream, so as to obtain each space-time stream after pilot insertion.

The processor 1002 executes the instructions to transmit each space-time stream with the pilot inserted thereto to a receiving end via a transmitter 1004.

In this embodiment of the present invention, optionally, the processor 1002 executing the instructions may specifically be configured to:

and acquiring a pilot sequence corresponding to the transmission signal by using the determined pilot sequence mapping algorithm.

In this embodiment of the present invention, optionally, the executing of the instructions by the processor 1002 to select a corresponding pilot sequence mapping algorithm according to the channel bandwidth includes:

and forming a pilot matrix according to the pilot symbol matrix and the pilot sequence, wherein the element of the ith row and the jth column of the pilot matrix is the value of the element of the ith row and the jth column of the pilot symbol matrix multiplied by the element in the pilot sequence.

continuously setting insertion positions with the number equal to the column number of a pilot matrix from a preset subcarrier of a preset OFDM symbol, and then continuously setting the insertion positions with the number equal to the column number of the pilot matrix on the OFDM symbol with the column number of the pilot matrix in the time domain interval of the preset subcarrier of the preset OFDM symbol and the subcarrier with the column number of the pilot matrix in the frequency domain interval of the preset carrier interval;

An embodiment of the present invention further provides a channel estimation apparatus 1100, as shown in fig. 9, where the channel estimation apparatus 1100 includes:

a bus 1101, and a processor 1102, a memory 1103, a receiver 1104 and an interface 1105 connected to the bus, wherein the interface 1105 is used for communication with external devices;

the memory 1103 is configured to store instructions, and the processor 1102 executes the instructions to receive each space-time stream through the receiver 1104 and obtain a channel bandwidth and a number of space-time streams;

the processor 1102 executes the instructions to generate a pilot symbol matrix based on the number of space-time streams.

Wherein, the pilot symbol matrix is a row orthogonal matrix.

The processor 1102 executes the instructions to obtain a corresponding pilot sequence according to a channel bandwidth.

The processor 1102 executes the instructions to extract pilot received values from corresponding OFDM symbols of each space-time stream according to pilot insertion positions, which are pre-stored.

The processor 1102 executes the instructions to perform channel estimation for the transmitted signal based on the pilot received values, the pilot sequence, and the pilot symbol matrix.

In this embodiment of the present invention, optionally, the processor 1102 executing the instructions may specifically be configured to:

and acquiring a corresponding pilot sequence by utilizing the determined pilot sequence mapping algorithm.

In this embodiment of the present invention, optionally, the processor 1102 executing the instructions to select a corresponding pilot sequence mapping algorithm according to the channel bandwidth includes:

The channel estimation algorithm comprises the following steps:

It can be seen that, according to the pilot sending method, the channel estimation method and the channel estimation device provided in the embodiments of the present invention, a pilot frequency symbol matrix is generated by a sending end according to the number of the space-time streams of the sending signal, then a pilot frequency sequence corresponding to the sending signal is obtained according to the channel bandwidth of the sending signal, then obtaining a pilot matrix according to the pilot symbol matrix and the pilot sequence, determining the insertion position of each group of pilot symbols in the pilot matrix in the orthogonal frequency division multiplexing OFDM symbols on the corresponding space-time streams, respectively inserting each group of pilot symbols into the pilot insertion positions on the corresponding space-time streams to obtain each space-time stream after the pilot is inserted, finally sending each space-time stream after the pilot is inserted to a receiving end, after the receiving end receives the space-time stream, and extracting a pilot frequency receiving value from the space-time stream according to a pre-stored inserting position, and performing channel estimation according to the pilot frequency sequence and the pilot frequency receiving value. Compared with the prior art that the frequency domain interpolation algorithm is used for only supporting 2 space-time streams, the method and the device provided by the embodiment of the invention overcome the defect that the frequency domain interpolation cannot be adopted for a larger subcarrier interval, have no limitation on the number of the space-time streams, namely the number of the used space-time streams can be equal to 2 or larger than 2, are suitable for outdoor high-Doppler frequency shift scenes, and can not increase extra pilot frequency overhead.

In the several embodiments provided in the present application, it should be understood that the disclosed system, apparatus and method may be implemented in other manners. For example, the above-described apparatus embodiments are merely illustrative, and for example, the division of the units is only one logical division, and other divisions may be realized in practice, for example, a plurality of units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may be in an electrical, mechanical or other form.

In addition, functional units in the embodiments of the present invention may be integrated into one processing unit, or each unit may be physically included alone, or two or more units may be integrated into one unit. The integrated unit can be realized in a form of hardware, or in a form of hardware plus a software functional unit.

The integrated unit implemented in the form of a software functional unit may be stored in a computer readable storage medium. The software functional unit is stored in a storage medium and includes several instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute some steps of the methods according to the embodiments of the present invention. And the aforementioned storage medium includes: various media capable of storing program codes, such as a usb disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk, or an optical disk.

The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention, and all the changes or substitutions should be covered within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the appended claims.

Claims

1. A pilot transmitting apparatus applied in an outdoor high-mobility environment using spatial multiplexing, the apparatus comprising:

2. The pilot transmitting apparatus of claim 1, wherein the pilot sequence acquiring unit is specifically configured to:

3. The pilot transmitting apparatus of claim 2, wherein the pilot sequence acquiring unit selects the corresponding pilot sequence mapping algorithm according to the channel bandwidth comprises:

where n denotes an nth OFDM symbol, k denotes a kth subcarrier, ψ denotes a value of an element in the pilot sequence, and NSTS denotes the number of the space-time streams.

4. The pilot transmitting apparatus of claim 1, wherein the pilot matrix generating unit is specifically configured to:

5. The pilot transmitting apparatus of claim 1, wherein the insertion location obtaining unit is specifically configured to:

6. A channel estimation apparatus applied in an outdoor high-mobility environment using spatial multiplexing, the apparatus comprising:

and the channel estimation unit is used for carrying out channel estimation on the transmitted signal according to the pilot frequency receiving value, the pilot frequency sequence and the pilot frequency symbol matrix.

7. The channel estimation apparatus according to claim 6, wherein the pilot sequence construction unit is specifically configured to:

8. The channel estimation device of claim 7, wherein the pilot sequence construction unit selects a corresponding pilot sequence mapping algorithm according to the channel bandwidth, comprising:

9. The channel estimation device according to claim 6, wherein the channel estimation unit is specifically configured to:

10. The channel estimation device according to claim 9, wherein the channel estimation algorithm comprises:

11. A pilot frequency sending method is applied to an outdoor high-mobility environment adopting a spatial multiplexing technology, and is characterized by comprising the following steps:

12. The method of claim 11, wherein the obtaining the pilot sequence corresponding to the transmission signal according to the channel bandwidth of the transmission signal comprises:

13. The method of claim 12, wherein selecting the corresponding pilot sequence mapping algorithm according to the channel bandwidth comprises:

14. The method of claim 11, wherein the generating a pilot matrix from the pilot symbol matrix and the pilot sequence comprises:

15. The method of claim 11, wherein the determining positions of pilot insertion in each set of the pilot symbols in an Orthogonal Frequency Division Multiplexing (OFDM) symbol on a corresponding space-time stream comprises:

continuously setting insertion positions with the number equal to the column number of the pilot matrix from a preset subcarrier of a preset OFDM symbol, and then moving to the OFDM symbol with the number equal to the column number of the pilot matrix of the space-time stream at the time interval of the preset subcarrier of the preset OFDM symbol and continuously setting the insertion positions with the number equal to the column number of the pilot matrix on the subcarrier of the preset carrier interval at the frequency interval;

16. A channel estimation method is applied to an outdoor high-mobility environment adopting a spatial multiplexing technology, and is characterized by comprising the following steps:

and performing channel estimation on a sending signal according to the pilot frequency receiving value, the pilot frequency sequence and the pilot frequency symbol matrix.

17. The method of claim 16, wherein the obtaining the corresponding pilot sequence according to the channel bandwidth comprises:

18. The method of claim 17, wherein selecting the corresponding pilot sequence mapping algorithm according to the channel bandwidth comprises:

19. The method of claim 16, wherein the channel estimating the transmitted signal according to the pilot received value, the pilot sequence, and the pilot symbol matrix comprises:

20. The method of claim 19, wherein the channel estimation algorithm comprises:

21. A pilot transmitting apparatus applied in an outdoor high-mobility environment using spatial multiplexing, the pilot transmitting apparatus comprising: a bus, and a processor, a memory, a transmitter, and an interface connected to the bus, wherein the interface is for communicating with an external device; the memory to store instructions, the processor to execute the instructions to:

22. The pilot transmitting apparatus of claim 21, wherein the processor executes the instructions to:

23. The pilot transmitting apparatus of claim 22, wherein the processor executing the instructions to select a corresponding pilot sequence mapping algorithm according to the channel bandwidth comprises:

24. The pilot transmitting apparatus of claim 21, wherein the processor executes the instructions to:

25. The pilot transmitting apparatus of claim 21, wherein the processor executes the instructions to:

26. A channel estimation device applied in an outdoor high-mobility environment using spatial multiplexing, the channel estimation device comprising: a bus, and a processor, a memory, a receiver, and an interface connected to the bus, wherein the interface is for communicating with an external device; the memory to store instructions, the processor to execute the instructions to:

27. The channel estimation device of claim 26, wherein the processor executes the instructions to:

28. The channel estimation device of claim 27, wherein the processor executing the instructions to select a corresponding pilot sequence mapping algorithm according to the channel bandwidth comprises:

29. The channel estimation device of claim 26, wherein the processor executes the instructions to:

30. The channel estimation device according to claim 29, wherein the channel estimation algorithm comprises:

wherein,an estimated value representing the channel response, Y represents the pilot reception value, x represents the pilot sequence, and P represents the pilot symbol momentAnd (5) arraying.