CN107005515B

CN107005515B - Information sending and receiving method, device and system in wireless local area network

Info

Publication number: CN107005515B
Application number: CN201480083920.2A
Authority: CN
Inventors: 朱俊; 张佳胤
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2014-12-15
Filing date: 2014-12-15
Publication date: 2020-02-14
Anticipated expiration: 2034-12-15
Also published as: CN107005515A; WO2016095092A1

Abstract

The embodiment of the invention provides a method, a device and a system for sending and receiving information in a wireless local area network. The method comprises the following steps: a transmitting end generates information for channel estimation, wherein the information for channel estimation comprises N1 × OFDM symbols, and the N1 × OFDM symbols comprise 1 × OFDM symbols of frequency offset; the transmitting end transmits the information for channel estimation. According to the embodiment of the invention, the first sequence and the second sequence of the channel estimation with frequency offset are merged into the third sequence through the receiving end, and the preset estimation value is inserted between the adjacent channel estimation values of the third sequence, so that the interval of frequency domain interpolation is reduced by half, and the accuracy of the channel estimation is improved.

Description

Information sending and receiving method, device and system in wireless local area network

Technical Field

The embodiment of the invention relates to the technical field of communication, in particular to a method, a device and a system for sending and receiving information in a wireless local area network.

Background

A Wireless Local Area Network (WLAN) is a data transmission system, which uses a Radio Frequency (RF) technology to transmit information and is developed along with the wide application of intelligent terminals. The IEEE802.11 family of standards is the primary standard for WLANs, including 802.11, 802.11b/g/a, 802.11n, and 802.11 ac. The 802.11n and 802.11ac adopt an Orthogonal Frequency Division Multiplexing (OFDM) technology as a core technology of a physical layer. Since the performance of the wireless communication system is greatly affected by the wireless channel, such as shadow fading and frequency selective fading, the channel parameters of the wireless channel need to be estimated by channel estimation. Fig. 1 shows a format of a High Throughput (HT) Physical layer Protocol Data Unit (PPDU) specified by the 802.11n standard, where the PPDU includes a High Throughput Long Training field 10 for channel estimation, the High Throughput Long Training field 10 includes one or more High Throughput-Long Training Sequence (HT-LTF) symbols 11, and one HT-LTF symbol is an OFDM symbol.

In the prior art, OFDM symbols are mainly divided into 1 × OFDM symbols and 4 × OFDM symbols, and the subcarrier intervals corresponding to the 1 × OFDM symbols

Its Fourier transform period

Subcarrier spacing for 4 x OFDM symbol

Its Fourier transform period

As shown in fig. 2, 22 represents a1 × OFDM symbol of a frequency domain, and a solid line part represents a subcarrier corresponding to the 1 × OFDM symbol; 21 denotes a 4 × OFDM symbol in the frequency domain, and a solid portion thereof denotes a subcarrier corresponding to the 4 × OFDM symbol; the subcarrier interval of the 1 × OFDM symbol is 4 times the subcarrier interval of the 4 × OFDM symbol, and since the data portion of the physical layer needs to be transmitted using the 4 × OFDM symbol, it is necessary to estimate channel parameters of a radio channel when transmitting the 4 × OFDM symbol, and since the time taken for a transmitting end to transmit one 4 × OFDM symbol is longer than the time taken to transmit one 1 × OFDM symbol, if the channel estimation is performed by transmitting the 4 × OFDM symbol between the transmitting end and the receiving end, the system overhead is large. In order to obtain channel estimation values of all subcarrier positions corresponding to 4 × OFDM symbols on the premise of reducing system overhead, in the prior art, a transmitting end transmits a1 × OFDM symbol, and after a receiving end receives the 1 × OFDM symbol, as shown in fig. 2, three subcarriers (dotted lines) are inserted at equal intervals between adjacent subcarriers (solid lines) in a subcarrier 22 corresponding to the 1 × OFDM symbol, and the channel estimation values at the inserted three subcarriers (dotted lines) are determined according to the channel estimation values at the adjacent subcarriers (solid lines) of the 1 × OFDM symbol.

Under outdoor scene, because multipath fading is strong, correlation between adjacent subcarriers of 1 × OFDM symbol is poor, under this condition, three subcarriers (dotted lines) are inserted between adjacent subcarriers of 1 × OFDM symbol (solid lines) at equal intervals, which will result in low accuracy of channel estimation, thereby affecting system performance.

Disclosure of Invention

The embodiment of the invention provides a method, a device and a system for transmitting and receiving information in a wireless local area network, which are used for improving the accuracy of channel estimation.

One aspect of the embodiments of the present invention is to provide an information sending method in a wireless local area network, including:

a transmitting end generates information for channel estimation, wherein the information for channel estimation comprises N1 × OFDM symbols, and the N1 × OFDM symbols comprise 1 × OFDM symbols of frequency offset;

the transmitting end transmits the information for channel estimation.

Another aspect of the embodiments of the present invention is to provide an information receiving method in a wireless local area network, including:

a receiving end receives information for channel estimation, wherein the information for channel estimation comprises N1 × OFDM symbols, and the N1 × OFDM symbols comprise 1 × OFDM symbols of frequency offset;

and the receiving end carries out channel estimation according to the N1 multiplied OFDM symbols.

Another aspect of the embodiments of the present invention is to provide a transmitting end, including:

an information generating module for generating information for channel estimation, the information for channel estimation including N1 × OFDM symbols including 1 × OFDM symbols of a frequency offset;

a sending module, configured to send the information for channel estimation.

Another aspect of the embodiments of the present invention is to provide a receiving end, including:

a receiving module, configured to receive information for channel estimation, where the information for channel estimation includes N1 × OFDM symbols, and the N1 × OFDM symbols include 1 × OFDM symbols of a frequency offset;

and the channel estimation module is used for carrying out channel estimation according to the N1 multiplied OFDM symbols.

Another aspect of the embodiments of the present invention is to provide an information sending and receiving system in a wireless local area network, including the sending end and the receiving end.

In the information sending and receiving method, device, and system in the wireless local area network provided in the embodiments of the present invention, a sending end sends a first 1 × OFDM symbol and a second 1 × OFDM symbol having a preset frequency difference, a receiving end obtains a first channel estimation sequence and a second channel estimation sequence according to the first 1 × OFDM symbol and the second 1 × OFDM symbol, the first channel estimation sequence and the second channel estimation sequence are combined into a third channel estimation sequence, and a preset estimation value is inserted between adjacent channel estimation values of the third channel estimation sequence to obtain a channel estimation sequence at a subcarrier position corresponding to a 4 × OFDM symbol.

Drawings

FIG. 1 is a diagram of a high throughput physical layer protocol data unit format in the prior art;

FIG. 2 is a frequency domain sequence diagram of a1 × OFDM symbol and a 4 × OFDM symbol of the prior art;

fig. 3 is a flowchart of an information sending method in a wireless local area network according to an embodiment of the present invention;

fig. 4 is a schematic diagram of frequency offset of 1 × OFDM symbol according to an embodiment of the present invention;

FIG. 5 is a schematic diagram of a frequency offset of 1 × OFDM symbol according to another embodiment of the present invention;

FIG. 6 is a schematic diagram of a frequency offset of 1 × OFDM symbol according to another embodiment of the present invention;

fig. 7 is a diagram illustrating a relationship between a number of space-time streams and a cyclic shift delay time according to another embodiment of the present invention;

fig. 8 is a flowchart of an information receiving method in a wireless local area network according to another embodiment of the present invention;

fig. 9 is a sequence diagram of channel estimation provided by another embodiment of the present invention;

fig. 10 is a sequence diagram of a channel estimation after superposition according to another embodiment of the present invention;

fig. 11 is a sequence diagram of interpolated channel estimation according to another embodiment of the present invention;

fig. 12 is a flowchart illustrating a process of a sending end according to another embodiment of the present invention;

fig. 13 is a flowchart illustrating a process of a sending end according to another embodiment of the present invention;

fig. 14 is a structural diagram of a transmitting end according to an embodiment of the present invention;

fig. 15 is a structural diagram of a transmitting end according to another embodiment of the present invention;

fig. 16 is a block diagram of a transmitting end according to another embodiment of the present invention;

fig. 17 is a structural diagram of a receiving end according to an embodiment of the present invention;

fig. 18 is a structural diagram of a receiving end according to another embodiment of the present invention;

fig. 19 is a block diagram of an information transmission and reception system in a wireless lan according to an embodiment of the present invention;

fig. 20 is a block diagram of a transmitting end according to another embodiment of the present invention;

fig. 21 is a structural diagram of a receiving end according to another embodiment of the present invention.

Detailed Description

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

The terminology used in the embodiments of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used in the examples of the present invention and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It should also be understood that the term "and/or" as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items. It will be further understood that the terms "comprises" and/or "comprising," when used herein, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

It should be understood that although the terms first, second, etc. may be used in describing various positioning devices in embodiments of the present invention, these positioning devices should not be limited by these terms. These terms are only used to distinguish pointing devices from one another. For example, a first positioning device may also be referred to as a second positioning device, and similarly, a second positioning device may also be referred to as a first positioning device, without departing from the scope of embodiments of the present invention.

In the 802.11ax standard in the process of preparation at present, in order to improve the system throughput rate in the system intensive scene, the OFDMA technology is introduced, and the subcarrier interval of the corresponding physical layer data part is determined by the existing subcarrier interval

Is reduced to

kHz, the Fourier transform period of the OFDM symbol of the data part of the physical layer is also determined by

Become into

The embodiment of the invention is applicable to the scenes of an indoor channel and an outdoor channel, and the transmission bandwidth BW of the channel is 20 MHz. Number of space-time streams N in embodiments of the present invention_STSThe number of the PPDU messages sent by the sending end is the same, and the number N of 1 × OFDM symbols in one PPDU can be specifically determined by table 1:

TABLE 1

N_STS	N
		1	2
2	4
		3	8
4	8
		5	12
6	12
		7	16
8	16

Since the sub-carrier spacing of the 1 x OFDM symbol is

When the transmission bandwidth is BW-20 MHz, the total number of sub-carriers is

Carried by these sub-carriersThe HE-LTF frequency domain sequence carried is described as follows.

HELTF_-32,31＝{0,0,0,0,1,1,1,1,-1,-1,1,1,-1,1,-1,1,1,1,1,1,1,-1,1,1,-1,1,-1,1,1,1,1,0,1,-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,-1,0,0,0}。

Fig. 3 is a flowchart of an information sending method in a wireless local area network according to an embodiment of the present invention. The information sending method in the wireless local area network provided by the embodiment of the invention is that a sending end sends N1 × OFDM symbols to a receiving end, wherein the N1 × OFDM symbols comprise frequency offset 1 × OFDM symbols, so that the receiving end carries out channel estimation according to the N1 × OFDM symbols, and the information sending method specifically comprises the following steps:

step S101, a transmitting end generates information for channel estimation, wherein the information for channel estimation comprises N1 × OFDM symbols, and the N1 × OFDM symbols comprise frequency offset 1 × OFDM symbols; the generating, by the transmitting end, information for channel estimation includes:

the sending end divides the N1 × OFDM symbols into a first 1 × OFDM symbol and a second 1 × OFDM symbol, and performs frequency offset on the first 1 × OFDM symbol or the second 1 × OFDM symbol so that the frequency of the first 1 × OFDM symbol and the frequency of the second 1 × OFDM symbol are different by a preset value;

the preset value is half of the interval of the sub-carriers corresponding to the 1 × OFDM symbol.

A PPDU message sent by a sending end includes N1 × OFDM symbols, and the N1 × OFDM symbols are divided into two types, one type is denoted as a first 1 × OFDM symbol, and the other type is denoted as a second 1 × OFDM symbol, that is, the first 1 × OFDM symbol is not only one symbol, but also the second 1 × OFDM symbol is not only one symbol. And performing frequency offset on the first 1 × OFDM symbol relative to the second 1 × OFDM symbol in a frequency domain, or performing frequency offset on the second 1 × OFDM symbol relative to the first 1 × OFDM symbol, so that a difference between frequencies of the first 1 × OFDM symbol and the second 1 × OFDM symbol in the frequency domain is a preset value, where the preset value is preferably half of a subcarrier interval corresponding to the 1 × OFDM symbol in the embodiment of the present invention.

Step S102, the sending end sends the information for channel estimation.

The transmitting, by the transmitting end, the information for channel estimation includes: the transmitting end transmits the first 1 × OFDM symbol and the second 1 × OFDM symbol.

The sending end sends the first 1 × OFDM symbol and the second 1 × OFDM symbol with the frequency difference of a preset value to a receiving end, and the receiving end receives the first 1 × OFDM symbol and the HELTF_-32,31Obtaining a first sequence of channel estimation by a channel estimation algorithm, and similarly, obtaining a second sequence of channel estimation according to the received second 1 × OFDM symbol and HELTF_-32,31And obtaining a channel estimation second sequence through a channel estimation algorithm, combining the channel estimation first sequence and the channel estimation second sequence into a channel estimation third sequence, wherein the same frequency point only corresponds to the first 1 × OFDM symbol or the second 1 × OFDM symbol due to the fact that the frequency difference between the first 1 × OFDM symbol and the second 1 × OFDM symbol is a preset value, and the interval between adjacent channel estimation values in the combined channel estimation third sequence is smaller than the interval of subcarriers corresponding to the 1 × OFDM symbol. And inserting a preset estimated value between every two adjacent channel estimated values to obtain a channel estimated sequence at the subcarrier position corresponding to the 4 multiplied OFDM symbol.

The method comprises the steps that a sending end sends a first 1 multiplied OFDM symbol and a second 1 multiplied OFDM symbol with preset frequency difference, a receiving end obtains a first channel estimation sequence and a second channel estimation sequence according to the first 1 multiplied OFDM symbol and the second 1 multiplied OFDM symbol, the first channel estimation sequence and the second channel estimation sequence are combined into a third channel estimation sequence, preset estimation values are inserted between adjacent channel estimation values of the third channel estimation sequence to obtain a channel estimation sequence at a subcarrier position corresponding to a 4 multiplied OFDM symbol, compared with the prior art, the interval of frequency domain interpolation is reduced by half, and the accuracy of channel estimation and the system performance are improved.

Fig. 4 is a schematic diagram of frequency offset of 1 × OFDM symbol according to an embodiment of the present invention; FIG. 5 is a schematic diagram of a frequency offset of 1 × OFDM symbol according to another embodiment of the present invention; fig. 6 is a schematic diagram of a frequency offset of 1 × OFDM symbol according to another embodiment of the present invention. On the basis of the foregoing embodiment, before performing the frequency offset on the first 1 × OFDM symbol or the second 1 × OFDM symbol, the method further includes:

multiplying a frequency domain sequence carried by a subcarrier corresponding to each 1 × OFDM symbol by an orthogonal mapping matrix A, the frequency domain sequence being a sequence corresponding to the 1 × OFDM symbol in a frequency domain,

wherein, K_PilotFor the set of pilot sub-carriers,

w＝exp(-j2π/6)，

[R]_m,n＝[P]_1,n，k∈[-32,...,31]，N_STSrepresenting the number of space-time streams.

The embodiment of the present invention provides a parity division method for N1 × OFDM symbols, where the dividing, by the transmitting end, the N1 × OFDM symbols into a first 1 × OFDM symbol and a second 1 × OFDM symbol includes: the transmitting end numbers the N1 × OFDM symbols in sequence, where N is 0,1, … N-1, the 1 × OFDM symbol with N as an even number is used as the first 1 × OFDM symbol, the 1 × OFDM symbol with N as an odd number is used as the second 1 × OFDM symbol, N is greater than or equal to 2, and N is an even number.

E.g. number of space-time streams N_STSWhen the number of the symbols is 1, one PPDU message sent by the sending end includes 2 × OFDM symbols, where a 0 th 1 × OFDM symbol may be used as the first 1 × OFDM symbol, and a1 st 1 × OFDM symbol may be used as the second 1 × OFDM symbol; the 0 th 1 × OFDM symbol may be the second 1 × OFDM symbol, and the 1 st 1 × OFDM symbol may be the first 1 × OFDM symbol.

E.g., number of space-time streams N_STSWhen 2, one PPDU message sent by the sending end includes 41 × OFDM symbols, and for the 41 × OFDsThe M symbols are numbered, where n is 0,1,2,3, and 0, 2 th 1 × OFDM symbol may be the first 1 × OFDM symbol, and 1, 3 th 1 × OFDM symbol may be the second 1 × OFDM symbol; the 0 th and 2 nd 1 × OFDM symbols may be the second 1 × OFDM symbol, and the 1 st and 3 rd 1 × OFDM symbols may be the first 1 × OFDM symbol.

Before the frequency offset is performed on the first 1 × OFDM symbol or the second 1 × OFDM symbol, the step of multiplying the frequency domain sequence carried by the subcarrier corresponding to each 1 × OFDM symbol by an orthogonal mapping matrix a includes: if the N1 × OFDM symbols and the ith symbol_STSCorresponding to each space-time stream, i is more than or equal to 1_STS≤N_STSThen, the frequency-domain value carried by the kth sub-carrier corresponding to the nth 1 × OFDM symbol is multiplied by

Wherein N is_STSRepresents the number of space-time currents, k ∈ [ -32.,. 31]，

I-th representing an orthogonal mapping matrix A_STSColumn col of row.

E.g. number of space-time streams N_STSWhen 1, one PPDU message sent by the sending end includes 2 × OFDM symbols, and in this case, i is_STS＝1，n＝0,1，col＝1，Represents the 1 st row and 1 st column of the orthogonal mapping matrix A due to N _STS1, so

To represent

1, namely 1, at this time, the frequency domain sequence L _ k carried by the kth subcarrier corresponding to the 0 th 1 × OFDM symbol is multiplied by the orthogonal mapping matrix a to become 1 × L _ k, and the 1 st 1 is a function ofAnd multiplying the frequency domain sequence L _ k carried by the kth subcarrier corresponding to the OFDM symbol by the orthogonal mapping matrix A to obtain 1 × L _ k.

If the 0 th 1 × OFDM symbol is the first 1 × OFDM symbol, the 1 st 1 × OFDM symbol is the second 1 × OFDM symbol, and the frequency offset of the second 1 × OFDM symbol is half of the subcarrier interval corresponding to the 1 × OFDM symbol, as shown in fig. 4, the center frequency of the k-th subcarrier 1 × L _ k 42 corresponding to the 1 st 1 × OFDM symbol is shifted from the center frequency of the k-th subcarrier 1 × L _ k 41 corresponding to the 0 th 1 × OFDM symbol

E.g., number of space-time streams N_STSWhen the number of the symbols n is 0,1,2, and 3, the transmitting end respectively transmits one PPDU message by using two transmitting antennas, assuming that a transmitting antenna a transmits a PPDU message 1 corresponding to the 1 st space-time stream and a transmitting antenna b transmits a PPDU message 2 corresponding to the 2 nd space-time stream, where the PPDU message 1 and the PPDU message 2 respectively include 41 × OFDM symbols with the numbers n being 0,1,2, and 3;

when i is_STSWhen n is 0,1, col is 1, [ a ═ b]_1,11, that is, the frequency domain sequence L _ k carried by the kth subcarrier corresponding to the 0 th 1 × OFDM symbol in the PPDU message 1 is multiplied by the orthogonal mapping matrix a to become 1 × L _ k, and the frequency domain sequence L _ k carried by the kth subcarrier corresponding to the 1 st 1 × OFDM symbol is multiplied by the orthogonal mapping matrix a to become 1 × L _ k;

when i is_STSWhen n is 2,3, col is 2, [ a ═ b]_1,2The frequency domain sequence L _ k carried by the kth subcarrier corresponding to the 2 nd 1 × OFDM symbol in the PPDU message 1 is multiplied by the orthogonal mapping matrix a to become-1 × L _ k, and the frequency domain sequence L _ k carried by the kth subcarrier corresponding to the 3 rd 1 × OFDM symbol is multiplied by the orthogonal mapping matrix a to become-1 × L _ k;

when i is_STSWhen n is 0,1, col is 1, [ a ═ 2]_2,1That is, the frequency domain sequence L _ k carried by the kth subcarrier corresponding to the 0 th 1 × OFDM symbol in the PPDU message 2 is multiplied by the orthogonal mapping matrix a to become 1 × L _ k, and the frequency domain sequence L _ k carried by the kth subcarrier corresponding to the 1 st 1 × OFDM symbol is multiplied by the orthogonal mapping matrix aThen becomes 1 × L _ k;

when i is_STSWhen n is 2,3, col is 2, [ a ═ b]_2,2That is, the frequency domain sequence L _ k carried by the kth subcarrier corresponding to the 2 nd 1 × OFDM symbol in the PPDU message 2 is multiplied by the orthogonal mapping matrix a to become 1 × L _ k, and the frequency domain sequence L _ k carried by the kth subcarrier corresponding to the 3 rd 1 × OFDM symbol is multiplied by the orthogonal mapping matrix a to become 1 × L _ k.

Using the 0 th and 2 nd 1 × OFDM symbols in PPDU message 1 and PPDU message 2 as the first 1 × OFDM symbols, using the 1 st and 3 th 1 × OFDM symbols as the second 1 × OFDM symbols, and performing frequency offset on the second 1 × OFDM symbols, where the frequency offset is half of the subcarrier interval corresponding to the 1 × OFDM symbols, as shown in fig. 5, 50 denotes a guard interval, and the center frequency of the kth subcarrier 1 × L _ k 52 corresponding to the 1 st 1 × OFDM symbol in PPDU message 1 is shifted by the center frequency of the kth subcarrier 1 × L _ k 51 corresponding to the 0 th 1 × OFDM symbol

The center frequency of the kth subcarrier-1 × L _ k 54 corresponding to the 3 rd 1 × OFDM symbol is shifted from the center frequency of the kth subcarrier-1 × L _ k 53 corresponding to the 2 nd 1 × OFDM symbol

The center frequency of the kth subcarrier 1 × L _ k 62 corresponding to the 1 st 1 × OFDM symbol in the PPDU message 2 is shifted from the center frequency of the kth subcarrier 1 × L _ k 61 corresponding to the 0 th 1 × OFDM symbolThe center frequency of the kth subcarrier 1 × L _ k 64 corresponding to the 3 rd 1 × OFDM symbol is shifted from the center frequency of the kth subcarrier 1 × L _ k 63 corresponding to the 2 nd 1 × OFDM symbol

The 0 th, 1 st, 2 nd and 3 rd 1 × OFDM symbols in the PPDU message 1 are respectively transmitted at the same time as the 0 th, 1 st, 2 nd and 3 rd 1 × OFDM symbols in the PPDU message 2.

In an embodiment of the present invention, another method for dividing N1 × OFDM symbols into a first 1 × OFDM symbol and a second 1 × OFDM symbol includes: the sending end carries out the first-order transmission in the N1 multiplied OFDM symbols

A1 × OFDM symbol as the first 1 × OFDM symbol, and

and taking the 1 × OFDM symbols as the second 1 × OFDM symbols, wherein N is more than or equal to 4, and N is an even number.

E.g. number of space-time streams N_STSWhen the number n is 0,1,2,3, the 0 th and 1 st 1 × OFDM symbols may be used as the first 1 × OFDM symbols, and the 2 nd and 3 rd 1 × OFDM symbols may be used as the second 1 × OFDM symbols; the 0 th and 1 st 1 × OFDM symbols may be the second 1 × OFDM symbol, and the 2 nd and 3 rd 1 × OFDM symbols may be the first 1 × OFDM symbol.

I-th representing an orthogonal mapping matrix A_STSColumn col of row.

Analyzing the number of space-time streams N according to the above embodiment_STSThe method of 2 may obtain the result shown in fig. 6, where 50 denotes a guard interval, where 71 denotes the kth subcarrier 1 × L _ k corresponding to the 0 th 1 × OFDM symbol in the

PPDU message

1, 72 denotes the kth subcarrier-1 × L _ k corresponding to the 1 st 1 × OFDM symbol in the

PPDU message

1, 73 denotes the kth subcarrier 1 × L _ k corresponding to the 2 nd 1 × OFDM symbol in the

PPDU message

1, and 74 denotes the kth subcarrier-1 × L _ k corresponding to the 3 rd 1 × OFDM symbol in the PPDU message 1;

81 represents the kth subcarrier 1 × L _ k corresponding to the 0 th 1 × OFDM symbol in the PPDU message 2, 82 represents the kth subcarrier 1 × L _ k corresponding to the 1 st 1 × OFDM symbol in the PPDU message 2, 83 represents the kth subcarrier 1 × L _ k corresponding to the 2 nd 1 × OFDM symbol in the PPDU message 2, and 84 represents the kth subcarrier 1 × L _ k corresponding to the 3 rd 1 × OFDM symbol in the PPDU message 2; the specific analysis process is the same as the above embodiment, and is not described herein again.

In addition, the embodiment of the present invention does not limit the classification method for the N1 × OFDM symbols, and the N1 × OFDM symbols are divided into two types to facilitate frequency offset of one type of 1 × OFDM symbol with respect to another type of 1 × OFDM symbol.

The embodiment of the invention provides two classification methods for N1 multiplied OFDM symbols and a specific implementation process of multiplying a frequency domain sequence carried by a subcarrier corresponding to each 1 multiplied OFDM symbol by an orthogonal mapping matrix A in different classification methods, wherein the orthogonal mapping matrix can realize the expansion of multi-space streams.

Fig. 7 is a diagram illustrating a relationship between the number of space-time streams and the cyclic shift delay time according to another embodiment of the present invention. On the basis of the foregoing embodiment, after multiplying the frequency domain sequence carried by the subcarrier corresponding to each 1 × OFDM symbol by the orthogonal mapping matrix a, the method further includes: number of said space-time streams N_STSAnd when the number of the symbols is more than or equal to 2, performing internal cyclic shift on each 1 × OFDM symbol corresponding to each space-time stream according to the cyclic shift delay time corresponding to each space-time stream.

Space-time stream number N in the embodiment of the invention_STSThe correspondence of the cyclic shift delay times for each space-time stream is shown in fig. 7, for example, the number N of space-time streams_STSWhen 1, the cyclic shift delay time corresponding to the 1 st space-time stream is 0, and the number of space-time streams is N_STSWhen the 1 st space-time stream corresponds to the PPDU message 1, the cyclic shift delay time corresponding to the 2 nd space-time stream is 0, and the cyclic shift delay time corresponding to the 2 nd space-time stream is 400ns, if the 1 st space-time stream corresponds to the PPDU message 1, and the 2 nd space-time stream corresponds to the PPDU message 2, the 1 × OFDM symbols in the PPDU message 2 are subjected to internal cyclic shift, that is, a frequency domain sequence corresponding to one 1 × OFDM symbol is subjected to internal cyclic shift, and a frequency domain sequence corresponding to each 1 × OFDM symbol in the PPDU message 1 is not changed.

The frequency shifting the first 1 × OFDM symbol or the second 1 × OFDM symbol comprises: shifting the frequency domain sequence of the first 1 × OFDM symbol or the second 1 × OFDM symbol, and performing inverse discrete fourier transform on the shifted frequency domain sequence to obtain a first 1 × OFDM symbol of a time domain or a second 1 × OFDM symbol of the time domain; or performing inverse discrete fourier transform on the first 1 × OFDM symbol or the second 1 × OFDM symbol to obtain a first 1 × OFDM symbol of a time domain or a second 1 × OFDM symbol of the time domain, and performing angle offset on the first 1 × OFDM symbol of the time domain or the second 1 × OFDM symbol of the time domain.

In the embodiment of the present invention, frequency offset is performed only on the first 1 × OFDM symbol or the second 1 × OFDM symbol after classification, and two ways of implementing frequency offset are provided by taking the second 1 × OFDM symbol as an example: one way is to directly shift the second 1 × OFDM symbol in the frequency domain, and the offset is half of the subcarrier interval corresponding to the 1 × OFDM symbol, that is, the offset isBecause the HT-LTF symbol in the PPDU message is a time domain signal, the inverse discrete fourier transform needs to be performed on the frequency domain sequence after frequency shift in the frequency domain to obtain a time domain sequence. Another method is to perform inverse discrete fourier transform on the second 1 × OFDM symbol in the frequency domain to obtain a time domain sequence in a complex form, and perform angle offset on the time domain sequence in the complex form, which is equivalent to performing frequency offset in the frequency domain.

In any of the above manners, the expression of the HE-LTF field time domain signal finally sent by the sending end is shown in the following formula (1):

wherein, if the parity division method is applied to N1 × OFDM symbols,

n_FSnmod 2; if the forward-backward division is applied to N1 × OFDM symbols,

α, a normalization parameter, which is determined by the total number of space-time streams, the number of available subcarriers, etc.;indicating a loop delay value; t is_GIRepresents a guard interval value;

is a time domain window function, here N_HELTFThe meaning of N is the same as that in the above embodiment.

Fig. 8 is a flowchart of an information receiving method in a wireless local area network according to another embodiment of the present invention; fig. 9 is a sequence diagram of channel estimation provided by another embodiment of the present invention; fig. 10 is a sequence diagram of a channel estimation after superposition according to another embodiment of the present invention; fig. 11 is a sequence diagram of interpolated channel estimation according to another embodiment of the present invention. The information receiving method in the wireless local area network provided by the embodiment of the invention specifically comprises the following steps:

step S701, a receiving end receives information for channel estimation, where the information for channel estimation includes N1 × OFDM symbols, and the N1 × OFDM symbols include 1 × OFDM symbols of frequency offset;

the N1 × OFDM symbols include a first 1 × OFDM symbol and a second 1 × OFDM symbol, and a frequency of the first 1 × OFDM symbol and a frequency of the second 1 × OFDM symbol differ by a preset value.

The process of dividing, by the transmitting end, a plurality of 1 × OFDM symbols in the PPDU message into a first 1 × OFDM symbol and a second 1 × OFDM symbol, and performing frequency offset on the first 1 × OFDM symbol or the second 1 × OFDM symbol is consistent with the above embodiment, and details are not described here again.

Step S702, the receiving end performs channel estimation according to the N1 × OFDM symbols.

The specific steps of the receiving end for performing channel estimation according to the N1 × OFDM symbols are as follows:

step S801, the receiving end obtains a first channel estimation sequence and a second channel estimation sequence according to the first 1 × OFDM symbol and the second 1 × OFDM symbol;

the transmitting end comprises N_TXMore than or equal to 1 transmitting antenna, the receiving end comprises N_RXThe receiving end obtains a first sequence of channel estimation and a second sequence of channel estimation according to the first 1 × OFDM symbol and the second 1 × OFDM symbol, wherein the receiving end includes: the receiving end obtains a channel estimation value according to the first 1 × OFDM symbol and the second 1 × OFDM symbol

Denotes the ith_RXA receiving antenna and the ith_TXI is more than or equal to 1 of channel estimation value of k subcarrier position between transmitting antennas_RX≤N_RX，1≤i_TX≤N_TX，k∈[-32,...,31]Where l ═ 0 indicates that the subcarrier position has not been frequency shifted, and l ═ 1 indicates that the subcarrier position has been frequency shifted; the channel estimates a first sequence as

The second sequence of the channel estimation is

Number of space-time streams N_STSWhen 1 hour, the transmitting end transmits the number of antennas N_TXReceiving end receiving antenna number N as 1_RX1, the receiving end receives a first 1 × OFDM symbol (without offset) and a second 1 × OFDM symbol (with offset) as shown in fig. 4, and the first 1 × OFDM symbol corresponds to 64 subcarriers 1 × L _ k without frequency offset, k ∈ 32]The second 1 × OFDM symbol corresponds to 64 frequency-shifted subcarriers 1 × L _ k, k ∈ [ -32., 31 []；

And the receiving end receives the first 1 × OFDM symbol and the second 1 × OFDM symbol, and the receiving end performs channel estimation algorithm and known HE-LTF frequency domain sequence:

HELTF_-32,31the channel estimation value corresponding to the subcarrier position between the receiving antenna and the transmitting antenna is obtained by comparing {0,0,0,0,1,1,1,1, 1, -1, -1,1, -1,1,1,1,1,1, 0,1, -1, -1,1,1, -1, -1, -1,1, -1,1,1, -1, -1,1,1,1, -1, -1,0, 0} to obtain the channel estimation value corresponding to the subcarrier position between the receiving antenna and the transmitting antennaBy

Forming a first sequence of channel estimatesByForming a second sequence of channel estimates

Indicating that the subcarrier position is not frequency shifted, and l-1 indicating that the subcarrier position is frequency shifted.

As shown in fig. 9, the solid line portion of the first 1 × OFDM symbol frequency domain sequence 91 represents the subcarriers corresponding to the first 1 × OFDM symbol, the subcarrier spacing

Solid line partial table of the second 1 × OFDM symbol frequency domain sequence 92Showing the sub-carriers, sub-carrier spacing, corresponding to the second 1 x OFDM symbolThe second 1 x OFDM symbol frequency domain sequence 92 is frequency shifted relative to the first 1 x OFDM symbol frequency domain sequence 91

Step S802, the receiving end combines the first channel estimation sequence and the second channel estimation sequence into a third channel estimation sequence, where the third channel estimation sequence includes a plurality of channel estimation values.

The third sequence of the channel estimation is

Number of space-time streams N_STSWhen being equal to 1, will

And

the following sequences were obtained by pooling:

as shown in fig. 10, the subcarrier spacing represented by the solid line portion of the combined sequence 100 is 2 times the subcarrier spacing of the 4 × OFDM symbol.

Step S803, the receiving end inserts a preset estimation value between each adjacent channel estimation value to obtain a channel estimation sequence at a subcarrier position corresponding to a 4 × OFDM symbol.

The method specifically comprises the following steps: the receiving end estimates the channel of each adjacent channel

Insert preset estimate between

Obtaining channel estimation sequence at subcarrier position corresponding to 4 x OFDM symbol

On the basis of fig. 10, the adjacent channel estimation value s_i,s_i+1A preset estimated value r is inserted between_iThe channel estimation sequence { s) at the position of the subcarrier corresponding to the 4 × OFDM symbol can be obtained₁,r₁,s₂,r₂,…s₁₂₈,r₁₂₈}, specific interpolated value r_iAccording to s_i,s_i+1The value of (d) is determined, as shown in fig. 11, the subcarrier spacing represented by the solid line portion of the sequence 110 is the same as the 4 × OFDM symbol subcarrier spacing.

The 802.11n and 802.11ac standards also use a Multiple-Input Multiple-Output (MIMO) system, which includes Multiple transmitting ends and Multiple receiving ends, where the transmitting signals respectively transmitted by the Multiple transmitting ends almost synchronously reach the same receiving end, that is, the receiving signal of the same receiving end is a superimposed signal of Multiple transmitting signals, so that to correctly identify Multiple transmitting signals from one superimposed signal, the channel characteristics of Multiple parallel channels between each transmitting end and the same receiving end need to be estimated through channel estimation.

By the number of space-time streams N_STSFor example 2, the number of transmitting antennas N at the transmitting end_TXReceiving end receiving antenna number N2_RX＝2，1≤i_RX≤2，1≤i_TX2, assuming that a transmitting antenna A and a transmitting antenna B, a receiving antenna 1 and a receiving antenna 2 correspondingly form 4 channels: a1, A2, B1 and B2. Specifically, taking a transmitting antenna a, a transmitting antenna B, and a receiving antenna 1 as an example, as shown in fig. 5, the transmitting antenna a sends out 41 × OFDM symbols: 1 × HTLTF (without offset), 1 × HTLTF (with offset), -1 × HTLTF (without offset), -1 × HTLTF (with offset); transmit antenna B sends out 41 × OFDM symbols: 1 × HTLTF (without offset), 1 × HTLTF (with offset), 1 × HTLTF (without offset), 1 × HTLTF (with offset); each HTLTF represents one 1 × OFDM symbol and corresponds to 64 subcarriers 1 × L _ k, k ∈ [ -32.,. 31]. Due to the transmitting antenna A transmittingThe 4 output 1 × OFDM symbols and 41 × OFDM symbols transmitted by the transmitting antenna B are mixed together in a channel for simultaneous transmission, and there are 4 cases that the receiving antenna 1 receives the kth sub-carrier from the transmitting antenna a and the transmitting antenna B:

1 × L _ K × a1 (without frequency offset) +1 × L _ K × B1 (without frequency offset)

1 x L _ K x a1 (with frequency offset) +1 x L _ K x B1 (with frequency offset)

-1 × L _ K _ a1 (without frequency offset) +1 × L _ K _ B1 (without frequency offset)

-1 x L _ K x a1 (with frequency offset) +1 x L K x B1 (with frequency offset)

From the above 4 cases, a1 and B1 without frequency offset and a1 and B1 with frequency offset can be obtained, and then the complete channel estimation sequences of a1 and B1 can be obtained. Similarly, the complete channel estimation sequences of a2 and B2 can be obtained. Specifically, the (i) th_RX,i_TX) The pair of sequences can be represented as

And

will be (i) th_RX,i_TX) Combining the sequences to obtain a combined sequence:

the ith channel estimation value can be obtained by interpolating every two adjacent channel estimation values of the combined sequence_RXA receiving antenna to the ith_TXChannel estimation sequence at 4 x OFDM symbol subcarrier position between transmitting antennas

Fig. 12 is a flowchart illustrating a process of a sending end according to another embodiment of the present invention. The embodiment of the invention provides a space-time stream number N_STSWhen the channel estimation method is 1, the transmitting end and the receiving end perform processing procedures to implement the channel estimation method.

The processing procedure of the sending end is as follows:

step S121, counting the number N of the space-time streams_STSDetermining 1 × OFDM symbol number N ═ 2, N included in HE-LTF field_STSThe correspondence relationship with N is shown in table 1 above.

Step S122, determining a frequency domain sequence corresponding to the 1 multiplied OFDM symbol;

since the sub-carrier spacing of the 1 x OFDM symbol isWhen the transmission bandwidth is BW ═ 20MHz, the total number of subcarriers is

The HE-LTF frequency domain sequences carried by these subcarriers are described as follows.

HELTF_-32,31＝{0,0,0,0,1,1,1,1,-1,-1,1,1,-1,1,-1,1,1,1,1,1,1,-1,1,1,-1,1,-1,1,1,1,1,0,1,-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,-1,0,0,0}

Step S123, multiplying the frequency domain sequence carried by the subcarrier of each 1 multiplied OFDM symbol by an orthogonal mapping matrix A;

the definition of the orthogonal mapping matrix a and the specific multiplication process are the same as those in the above embodiments, and are not described herein again. In FIG. 12

Representing the multiplication of the frequency-domain value carried by the k-th subcarrierThe orthogonal mapping matrix a.

Step S124, different cyclic shift delays are applied to each space-time stream of the HE-LTF field;

number of space-time streams N_STSThe correspondence relationship between the cyclic shift delay times corresponding to the respective space-time streams is shown in fig. 7, and the specific cyclic shift delay processing is the same as that in the above-described embodiment.

Step S125, mapping the space-time stream to a transmitting antenna;

one empty time flow corresponds to one PPDU message, if the total transmission chain number is N_TXThe total number of the space-time streams is N_STSThen the antenna mapping matrix Q for the k-th sub-carrier_kIs N_TXLine N_STSColumn, here the number of space-time streams is N _STS1, the number of transmission links is N_TXWhen 1, i.e. single spatial stream, single transmit antenna, Q may be taken_k＝1。

Step S126, obtaining a time domain sequence through inverse discrete Fourier transform;

ith_TXThe expression of HE-LTF field time domain signal transmitted by each transmission link is as follows (2)

α represents normalization parameter, which is determined by total space-time flow number, available subcarrier number, etc.;

indicating a loop delay value; t is_GIRepresents a guard interval value;

is a time domain window function.

Step S127, frequency offset;

if the frequency offset is carried out on the even numbered 1 × OFDM symbols of the HE-LTF field, the ith symbol is finally obtained_TXThe expression of the HE-LTF field time domain signal transmitted by each transmission link is as follows (3):

wherein n is_FS＝n mod 2。

The processing procedure of the receiving end is as follows:

step S131, obtaining transmission bandwidth BW and total space-time flow number N according to information carried by signaling field in PPDU message lead code_STS；

Step S132, counting the number N of the space-time streams_STSDetermining the number N of 1 × OFDM symbols contained in the HE-LTF field_HELTF；

Here, the number of space-time streams is N _STS1, i.e., single spatial stream, the HE-LTF field contains 1 × OFDM symbol number N_HELTF＝2。

And step S133, determining the HE-LTF frequency domain sequence according to the transmission bandwidth.

Since the sub-carrier spacing of the 1 x OFDM symbol is

When the transmission bandwidth is BW being 20MHz, the total number of subcarriers is

Step S134, the received HE-LTF field and the known frequency domain sequence HELTF_-32,31Obtaining a channel estimation value corresponding to the position of a subcarrier;

the obtained channel estimation sequence 1 and sequence 2 are respectively

And

step S135, combining the obtained channel estimation sequence 1 and sequence 2 into a sequence shown below;

the combined subcarrier spacing is 2 times the 4 x OFDM symbol subcarrier spacing.

Step S136, interpolating every two adjacent channel estimation values of the merged sequence;

r_mis s is_mAnd s_m+1Interpolation, the channel estimation sequence { s) at the position of 4 × OFDM symbol subcarrier obtained after interpolation₁,r₁,s₂,r₂,…s₁₂₈,r₁₂₈}。

The specific processing procedures of steps S134-S136 are consistent with the above-described embodiment.

Fig. 13 is a flowchart illustrating a process of a sending end according to another embodiment of the present invention. The embodiment of the invention provides a space-time stream number N_STSWhen 2, in order to implement the above channel estimation method, the transmitting end and the receiving end perform processing procedures.

The processing procedure of the sending end is as follows:

step S141, counting the number of the space-time streams N_STS2, determining the number of 1 × OFDM symbols contained in the HE-LTF field, N4, N_STSThe correspondence relationship with N is shown in table 1 above.

Step S142, determining a frequency domain sequence corresponding to the 1 multiplied OFDM symbol;

since the sub-1 × OFDM symbolThe carrier spacing is

When the transmission bandwidth is BW ═ 20MHz, the total number of subcarriers isThe HE-LTF frequency domain sequences carried by these subcarriers are described as follows.

Step S143, multiplying the frequency domain sequence carried by the subcarrier of each 1 × OFDM symbol by an orthogonal mapping matrix A;

the definition of the orthogonal mapping matrix a and the specific multiplication process are the same as those in the above embodiments, and are not described herein again. The input sequence in fig. 13 includes the frequency domain sequence of the two space-time streams, the frequency domain sequence of the first space-time stream and the matrix

Multiplication, frequency domain sequence and matrix of the second space-time stream

The multiplication is carried out in such a way that,

specifically, the orthogonal mapping matrix a multiplied by the frequency-domain value carried by the kth subcarrier is represented.

Step S144, different cyclic shift delays are applied to each space-time stream of the HE-LTF field;

number of space-time streams N_STSFig. 7 shows a cyclic shift delay time correspondence relationship corresponding to each space-time stream, where the number of space-time streams is N_STSWhen 2, the cyclic shift delay of the first space-time stream is

The cyclic shift delay of the second space-time stream is

The specific cyclic shift delay process is consistent with the above embodiments.

Step S145, mapping the space-time stream to a transmitting antenna;

one space-time stream corresponds to one PPDU message, and the space-time stream is mapped to the matrix Q through an antenna_kIf the total number of the transmitting links is N_TXThe total number of the space-time streams is N_STSThen the antenna mapping matrix Q for the k-th sub-carrier_kIs N_TXLine N_STSColumn, here the number of space-time streams is N_STS2, the number of transmitting links is N_TXWhen it is 2, it is advisable

Step S146, obtaining a time domain sequence by inverse discrete Fourier transform;

ith_TXThe expression of HE-LTF field time domain signal transmitted by each transmission link is as follows (4)

indicating a loop delay value; t is_GIRepresents a guard interval value;

is a time domain window function.

Step S147, frequency offset;

if the frequency offset is carried out on the even numbered 1 × OFDM symbols of the HE-LTF field, the ith symbol is finally obtained_TXThe expression of the HE-LTF field time domain signal transmitted by each transmission link is as follows (5):

wherein n is_FS＝n mod 2。

If it is preceded by HE-LTF field

Frequency shifting every 1 × OFDM symbol, then the ith symbol is finally obtained_TXThe HE-LTF field time domain signal expression sent by the transmission links is as follows (6):

wherein the content of the first and second substances,

the processing procedure of the receiving end is as follows:

step S151, obtaining transmission bandwidth BW and total space-time flow number N according to information carried by signaling field in PPDU message lead code_STS；

Step S152, counting the number N of the space-time streams_STSDetermining the number N of 1 × OFDM symbols contained in the HE-LTF field_HELTF；

Here, the number of space-time streams is N_STS2, i.e., single spatial stream, the HE-LTF field contains 1 × OFDM symbol number N_HELTF＝4。

And step S153, determining the HE-LTF frequency domain sequence according to the transmission bandwidth.

Since the sub-carrier spacing of the 1 x OFDM symbol is

Step S154, the received HE-LTF field and the known frequency domain sequence HELTF_-32,31Obtaining a channel estimation value corresponding to the position of a subcarrier;

here, the number of space-time streams is N_STS2, the number of transmitting links is N_TXIf the number of receiving antennas is N2_RXWhen 2, then N is obtained_TX·N_RXAnd estimating a sequence pair for the channel. Wherein the (i) th_RX,i_TX) The pair of sequences can be represented as

Step S155 is to add the (i) th_RX,i_TX) Merging the sequences into the sequences shown below;

Step S156, interpolating every two adjacent channel estimation values of the merged sequence;

obtaining the ith_RXA receiving antenna to the ith_TXChannel estimation sequence at 4 x OFDM symbol subcarrier position between transmitting antennas

The specific processing procedures of steps S154-S156 are consistent with the above-described embodiment.

Fig. 14 is a structural diagram of a transmitting end according to an embodiment of the present invention. As shown in fig. 14, the transmitting end 160 includes an information generating module 161 and a transmitting module 162, where the information generating module 161 is configured to generate information for channel estimation, the information for channel estimation includes N1 × OFDM symbols, and the N1 × OFDM symbols include a frequency offset 1 × OFDM symbol; the sending module 162 is configured to send the information for channel estimation.

The information generating module 161 comprises a classifying module 1611 and a frequency offset module 1612, wherein the classifying module 1611 is configured to divide the N1 × OFDM symbols into a first 1 × OFDM symbol and a second 1 × OFDM symbol; the frequency offset module 1612 is configured to frequency offset the first 1 × OFDM symbol or the second 1 × OFDM symbol, so that a frequency of the first 1 × OFDM symbol and a frequency of the second 1 × OFDM symbol are different by a preset value.

The transmitting module 162 is specifically configured to transmit the first 1 × OFDM symbol and the second 1 × OFDM symbol.

Fig. 15 is a structural diagram of a transmitting end according to another embodiment of the present invention; fig. 16 is a block diagram of a transmitting end according to another embodiment of the present invention. In addition to fig. 14, as shown in fig. 15, the classifying module 161 is specifically configured to number the N1 × OFDM symbols in sequence, where the number N is 0,1, … N-1, the 1 × OFDM symbol with the even number N is used as the first 1 × OFDM symbol, the 1 × OFDM symbol with the odd number N is used as the second 1 × OFDM symbol, N ≧ 2, and N is an even number.

The information generating module 161 further comprises a first calculating module 1613, wherein the first calculating module 1613 is configured to calculate the number of the N1 × OFDM symbols and the ith symbol_STSCorresponding to each space-time stream, i is more than or equal to 1_STS≤N_STSThen, the frequency-domain value carried by the kth sub-carrier corresponding to the nth 1 × OFDM symbol is multiplied by

I-th representing an orthogonal mapping matrix A_STSColumn col of row.

As shown in fig. 16, the classifying module 161 is specifically configured to classify the N1 × OFDM symbols into the first symbol and the second symbol

A1 × OFDM symbol as the first 1 × OFDM symbol, and

The information generating module 161 further comprises a second calculating module 1614, wherein the second calculating module 1614 is configured to calculate the number of the N1 × OFDM symbols and the ith symbol_STSCorresponding to each space-time stream, i is more than or equal to 1_STS≤N_STSThen, the frequency-domain value carried by the kth sub-carrier corresponding to the nth 1 × OFDM symbol is usedMultiplication by

Wherein N is_STSRepresents the number of space-time currents, k ∈ [ -32.,. 31]， I-th representing an orthogonal mapping matrix A_STSColumn col of row.

The frequency offset module 1612 is specifically configured to shift the frequency domain sequence of the first 1 × OFDM symbol or the second 1 × OFDM symbol, and perform inverse discrete fourier transform on the shifted frequency domain sequence to obtain the first 1 × OFDM symbol of the time domain or the second 1 × OFDM symbol of the time domain; or performing inverse discrete fourier transform on the first 1 × OFDM symbol or the second 1 × OFDM symbol to obtain a first 1 × OFDM symbol of a time domain or a second 1 × OFDM symbol of the time domain, and performing angle offset on the first 1 × OFDM symbol of the time domain or the second 1 × OFDM symbol of the time domain.

The sending end provided in the embodiment of the present invention may be specifically configured to execute the method embodiment provided in fig. 3, and specific functions are not described herein again.

Fig. 17 is a structural diagram of a receiving end according to an embodiment of the present invention. As shown in fig. 17, a receiving end 170 includes a receiving module 171 and a channel estimation module 172, where the receiving module 171 is configured to receive information for channel estimation, the information for channel estimation includes N1 × OFDM symbols, and the N1 × OFDM symbols include 1 × OFDM symbols with frequency offset; the channel estimation module 172 is configured to perform channel estimation according to the N1 × OFDM symbols.

Fig. 18 is a structural diagram of a receiving end according to another embodiment of the present invention. On the basis of fig. 17, the channel estimation module 172 includes a channel estimation sequence obtaining unit 1721, a combining unit 1722 and an interpolating unit 1723, wherein the channel estimation sequence obtaining unit 1721 is configured to obtain a first channel estimation sequence and a second channel estimation sequence according to the first 1 × OFDM symbol and the second 1 × OFDM symbol; a merging unit 1722 is configured to merge the first channel estimation sequence and the second channel estimation sequence into a third channel estimation sequence, where the third channel estimation sequence includes multiple channel estimation values; the interpolation unit 1723 is configured to obtain a channel estimation sequence at a subcarrier position corresponding to 4 × OFDM symbol after inserting a preset estimation value between each adjacent channel estimation value.

The transmitting end comprises N_TXMore than or equal to 1 transmitting antenna, the receiving end comprises N_RXMore than or equal to 1 receiving antenna; the channel estimation sequence obtaining unit 1721 is specifically configured to obtain a channel estimation value according to the first 1 × OFDM symbol and the second 1 × OFDM symbol

Denotes the ith_RXA receiving antenna and the ith_TXI is more than or equal to 1 of channel estimation value of k subcarrier position between transmitting antennas_RX≤N_RX，1≤i_TX≤N_TX，k∈[-32,...,31]Where l ═ 0 indicates that the subcarrier position has not been frequency shifted, and l ═ 1 indicates that the subcarrier position has been frequency shifted;

the channel estimates a first sequence as

The second sequence of the channel estimation is

The channel estimation third sequence

The interpolation unit 1723 is specifically configured to interpolate channel estimation values at each neighbor

Insert preset estimate between

The receiving end provided in the embodiment of the present invention may be specifically configured to execute the method embodiment provided in fig. 3, and specific functions are not described herein again.

Fig. 19 is a block diagram of an information transmitting and receiving system in a wireless lan according to an embodiment of the present invention. The information sending and receiving system in the wireless local area network according to the embodiment of the present invention may execute the processing procedure provided in the embodiment of the information sending and receiving method in the wireless local area network, as shown in fig. 19, the information sending and receiving system 190 in the wireless local area network includes the sending end 160 and the receiving end 170 described in the above embodiments.

The information sending and receiving system in the wireless local area network provided by the embodiment of the invention can execute the processing flow provided by the information sending and receiving method in the wireless local area network.

Fig. 20 is a block diagram of a transmitting end according to another embodiment of the present invention. As shown in fig. 20, a transmitting end 160 includes a bus 202, and an interface 201, a processor 203, and a memory 204 connected to the bus 202, where the memory 204 is configured to store an instruction, and the processor 203 is configured to execute the instruction stored in the memory 204 to generate information for channel estimation, where the information for channel estimation includes N1 × OFDM symbols, and the N1 × OFDM symbols include a1 × OFDM symbol of a frequency offset; the interface 201 is used to transmit the information for channel estimation.

In this embodiment of the present invention, optionally, the processor 203 is further configured to perform the following steps, dividing the N1 × OFDM symbols into a first 1 × OFDM symbol and a second 1 × OFDM symbol; performing frequency offset on the first 1 × OFDM symbol or the second 1 × OFDM symbol, so that a frequency of the first 1 × OFDM symbol and a frequency of the second 1 × OFDM symbol are different by a preset value. The interface 201 is further configured to transmit the first 1 × OFDM symbol and the second 1 × OFDM symbol.

In this embodiment of the present invention, optionally, the processor 203 is further configured to number the N1 × OFDM symbols in sequence, where the number N is 0,1, … N-1, use the 1 × OFDM symbol with the even number N as the first 1 × OFDM symbol, use the 1 × OFDM symbol with the odd number N as the second 1 × OFDM symbol, where N ≧ 2, and N is an even number. If the N1 × OFDM symbols and the ith symbol_STSCorresponding to each space-time stream, i is more than or equal to 1_STS≤N_STSThen, the frequency-domain value carried by the kth sub-carrier corresponding to the nth 1 × OFDM symbol is multiplied by

I-th representing an orthogonal mapping matrix A_STSColumn col of row.

In this embodiment of the present invention, optionally, the processor 203 is further configured to perform the following step of preceding the N1 × OFDM symbols

A1 × OFDM symbol as the first 1 × OFDM symbol, and

and taking the 1 × OFDM symbols as the second 1 × OFDM symbols, wherein N is more than or equal to 4, and N is an even number. If the N1 × OFDM symbols and the ith symbol_STSCorresponding to each space-time stream, i is more than or equal to 1_STS≤N_STSThen, the frequency-domain value carried by the kth sub-carrier corresponding to the nth 1 × OFDM symbol is multiplied by

I-th representing an orthogonal mapping matrix A_STSColumn col of row.

In this embodiment of the present invention, optionally, the processor 203 is further configured to shift a frequency domain sequence of the first 1 × OFDM symbol or the second 1 × OFDM symbol, and perform an inverse discrete fourier transform on the shifted frequency domain sequence to obtain a first 1 × OFDM symbol in a time domain or a second 1 × OFDM symbol in the time domain; or performing inverse discrete fourier transform on the first 1 × OFDM symbol or the second 1 × OFDM symbol to obtain a first 1 × OFDM symbol of a time domain or a second 1 × OFDM symbol of the time domain, and performing angle offset on the first 1 × OFDM symbol of the time domain or the second 1 × OFDM symbol of the time domain.

In this embodiment of the present invention, optionally, the preset value is half of a subcarrier interval corresponding to the 1 × OFDM symbol.

The method comprises the steps that a sending end sends a first 1 multiplied OFDM symbol and a second 1 multiplied OFDM symbol with preset frequency difference, a receiving end obtains a first channel estimation sequence and a second channel estimation sequence according to the first 1 multiplied OFDM symbol and the second 1 multiplied OFDM symbol, the first channel estimation sequence and the second channel estimation sequence are combined into a third channel estimation sequence, preset estimation values are inserted between adjacent channel estimation values of the third channel estimation sequence to obtain a channel estimation sequence at a subcarrier position corresponding to a 4 multiplied OFDM symbol, compared with the prior art, the interval of frequency domain interpolation is reduced by half, and the accuracy of channel estimation and the system performance are improved; two classification methods for N1 × OFDM symbols are provided, and a specific implementation process of multiplying a frequency domain sequence carried by a subcarrier corresponding to each 1 × OFDM symbol by an orthogonal mapping matrix A in different classification methods is provided, and the orthogonal mapping matrix can realize the expansion of multiple spatial streams.

Fig. 21 is a structural diagram of a receiving end according to another embodiment of the present invention. As shown in fig. 21, a receiving end 170 includes a bus 212, and an interface 211, a processor 213, and a memory 214 connected to the bus 212, where the interface 211 is configured to receive information for channel estimation, where the information for channel estimation includes N1 × OFDM symbols, and the N1 × OFDM symbols include 1 × OFDM symbols of frequency offset; the memory 214 is configured to store instructions and the processor 213 is configured to execute the instructions stored in the memory 214 for channel estimation based on the N1 × OFDM symbols.

In this embodiment of the present invention, optionally, the N1 × OFDM symbols include a first 1 × OFDM symbol and a second 1 × OFDM symbol, and a frequency of the first 1 × OFDM symbol and a frequency of the second 1 × OFDM symbol differ by a preset value.

In this embodiment of the present invention, optionally, the processor 213 is further configured to perform the following steps, obtaining a first sequence of channel estimates and a second sequence of channel estimates according to the first 1 × OFDM symbol and the second 1 × OFDM symbol; combining the first and second channel estimation sequences into a third channel estimation sequence, the third channel estimation sequence comprising a plurality of channel estimation values; and inserting a preset estimated value between every two adjacent channel estimated values to obtain a channel estimated sequence at the subcarrier position corresponding to the 4 multiplied OFDM symbol.

In this embodiment of the present invention, optionally, the sending end includes N_TXMore than or equal to 1 transmitting antenna, the receiving end comprises N_RXMore than or equal to 1 receiving antenna; the processor 213 is further configured to perform the step of obtaining a channel estimation value from the first 1 × OFDM symbol and the second 1 × OFDM symbol

The second sequence of the channel estimation is

In this embodiment of the present invention, optionally, the channel estimation third sequence

In the embodiment of the present invention, optionally, the processor 213 is further configured to perform the following steps, at each adjacent channel estimation valueInsert preset estimate between

The information sending and receiving system in the wireless local area network according to the embodiment of the present invention may be implemented by replacing the sending end 160 in fig. 20 with the sending end 160 in fig. 19, and replacing the receiving end 170 in fig. 21 with the receiving end 170 in fig. 19, so as to obtain the information sending and receiving system in the wireless local area network according to the embodiment of the present invention.

In summary, in the embodiment of the present invention, the sending end sends the first 1 × OFDM symbol and the second 1 × OFDM symbol with a preset frequency difference, the receiving end obtains the first channel estimation sequence and the second channel estimation sequence according to the first 1 × OFDM symbol and the second 1 × OFDM symbol, merges the first channel estimation sequence and the second channel estimation sequence into the third channel estimation sequence, and inserts the preset estimation value between each adjacent channel estimation value of the third channel estimation sequence to obtain the channel estimation sequence at the subcarrier position corresponding to the 4 × OFDM symbol, which reduces the interval of frequency domain interpolation by half compared with the prior art, and improves the accuracy of channel estimation and the system performance; two classification methods for N1 × OFDM symbols are provided, and a specific implementation process of multiplying a frequency domain sequence carried by a subcarrier corresponding to each 1 × OFDM symbol by an orthogonal mapping matrix A in different classification methods is provided, and the orthogonal mapping matrix can realize the expansion of multiple spatial streams.

In the embodiments provided in the present invention, it should be understood that the disclosed apparatus and method may be implemented in other ways. 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.

The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.

In addition, functional units in the embodiments of the present invention may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are 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 to enable a computer device (which may be a personal computer, a server, or a network device) or a processor (processor) 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.

It is obvious to those skilled in the art that, for convenience and simplicity of description, the foregoing division of the functional modules is merely used as an example, and in practical applications, the above function distribution may be performed by different functional modules according to needs, that is, the internal structure of the device is divided into different functional modules to perform all or part of the above described functions. For the specific working process of the device described above, reference may be made to the corresponding process in the foregoing method embodiment, which is not described herein again.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An information sending method in a wireless local area network, comprising:

the sending end sends the information for channel estimation;

wherein the generating, by the transmitting end, information for channel estimation includes:

the transmitting, by the transmitting end, the information for channel estimation includes:

the transmitting end transmits the first 1 × OFDM symbol and the second 1 × OFDM symbol.

2. The method of claim 1, wherein the transmitting end dividing the N1 × OFDM symbols into a first 1 × OFDM symbol and a second 1 × OFDM symbol comprises:

the transmitting end numbers the N1 × OFDM symbols in sequence, where N is 0,1, … N-1, the 1 × OFDM symbol with N as an even number is used as the first 1 × OFDM symbol, the 1 × OFDM symbol with N as an odd number is used as the second 1 × OFDM symbol, N is greater than or equal to 2, and N is an even number.

3. The method of claim 2, wherein before frequency shifting the first 1 x OFDM symbol or the second 1 x OFDM symbol, further comprising:

if the N1 × OFDM symbols and the ith symbol_STSCorresponding to each space-time stream, i is more than or equal to 1_STS≤N_STSThen, the frequency-domain value carried by the kth sub-carrier corresponding to the nth 1 × OFDM symbol is multiplied by

4. The method of claim 1, wherein the transmitting end dividing the N1 × OFDM symbols into a first 1 × OFDM symbol and a second 1 × OFDM symbol comprises:

the transmitting end carries out the front-end treatment on the N1 multiplied OFDM symbols

A1 × OFDM symbol as the first 1 × OFDM symbol, andand taking the 1 × OFDM symbols as the second 1 × OFDM symbols, wherein N is more than or equal to 4, and N is an even number.

5. The method of claim 4, wherein before frequency shifting the first 1 x OFDM symbol or the second 1 x OFDM symbol, further comprising:

I-th representing an orthogonal mapping matrix A_STSColumn col of row.

6. The method of any of claims 1-5, wherein frequency shifting the first 1 x OFDM symbol or the second 1 x OFDM symbol comprises:

shifting the frequency domain sequence of the first 1 × OFDM symbol or the second 1 × OFDM symbol, and performing inverse discrete fourier transform on the shifted frequency domain sequence to obtain a first 1 × OFDM symbol of a time domain or a second 1 × OFDM symbol of the time domain; or

Performing inverse discrete fourier transform on the first 1 × OFDM symbol or the second 1 × OFDM symbol to obtain a first 1 × OFDM symbol of a time domain or a second 1 × OFDM symbol of the time domain, and performing angle offset on the first 1 × OFDM symbol of the time domain or the second 1 × OFDM symbol of the time domain.

7. The method of claim 6, wherein the predetermined value is half of the subcarrier spacing corresponding to the 1 x OFDM symbol.

8. An information receiving method in a wireless local area network, comprising:

the receiving end carries out channel estimation according to the N1 multiplied OFDM symbols;

the N1 × OFDM symbols comprise a first 1 × OFDM symbol and a second 1 × OFDM symbol, and the frequency of the first 1 × OFDM symbol and the frequency of the second 1 × OFDM symbol are different by a preset value.

9. The method of claim 8, wherein the receiving end performs channel estimation according to the N1 × OFDM symbols comprises:

the receiving end obtains a first channel estimation sequence and a second channel estimation sequence according to the first 1 × OFDM symbol and the second 1 × OFDM symbol;

the receiving end combines the first channel estimation sequence and the second channel estimation sequence into a third channel estimation sequence, wherein the third channel estimation sequence comprises a plurality of channel estimation values;

and the receiving end inserts a preset estimated value between every two adjacent channel estimated values to obtain a channel estimated sequence at the subcarrier position corresponding to the 4 multiplied OFDM symbol.

10. The method of claim 9, wherein a transmitting end comprises N_TXMore than or equal to 1 transmitting antenna, the receiving end comprises N_RXMore than or equal to 1 receiving antenna;

the receiving end obtaining a first sequence of channel estimation and a second sequence of channel estimation according to the first 1 × OFDM symbol and the second 1 × OFDM symbol includes:

the receiving end obtains a channel estimation value according to the first 1 × OFDM symbol and the second 1 × OFDM symbol

the channel estimates a first sequence as

The second sequence of the channel estimation is

11. The method of claim 10, wherein the channel estimation third sequence

12. The method according to any one of claims 8-11, wherein the obtaining, by the receiving end, the channel estimation sequence at the subcarrier position corresponding to the 4 × OFDM symbol after inserting the preset estimation value between each adjacent channel estimation values comprises:

the receiving end estimates the channel of each adjacent channel

Insert preset estimate between

13. A transmitting end, comprising:

a sending module, configured to send the information for channel estimation;

wherein the information generation module comprises:

a classification module for dividing the N1 × OFDM symbols into a first 1 × OFDM symbol and a second 1 × OFDM symbol;

a frequency offset module, configured to perform frequency offset on the first 1 × OFDM symbol or the second 1 × OFDM symbol, so that a frequency of the first 1 × OFDM symbol and a frequency of the second 1 × OFDM symbol differ by a preset value;

the transmitting module is specifically configured to transmit the first 1 × OFDM symbol and the second 1 × OFDM symbol.

14. The transmitting end according to claim 13, wherein the classifying module is specifically configured to number the N1 × OFDM symbols in sequence, where N is 0,1, … N-1, the 1 × OFDM symbol with N being an even number is used as the first 1 × OFDM symbol, the 1 × OFDM symbol with N being an odd number is used as the second 1 × OFDM symbol, N is greater than or equal to 2, and N is an even number.

15. The transmitting end according to claim 14, wherein the information generating module further comprises:

a first calculating module for calculating the number of the N1 × OFDM symbols and the ith symbol_STSCorresponding to each space-time stream, i is more than or equal to 1_STS≤N_STSThen, the frequency-domain value carried by the kth sub-carrier corresponding to the nth 1 × OFDM symbol is multiplied by

Wherein N is_STSRepresenting space-time streamsNumber, k ∈ [ -32.,. 31]，

I-th representing an orthogonal mapping matrix A_STSColumn col of row.

16. The transmitting end according to claim 13, wherein the classifying module is specifically configured to forward the N1 × OFDM symbols

A1 × OFDM symbol as the first 1 × OFDM symbol, and

17. The transmitting end according to claim 16, wherein the information generating module further comprises:

a second calculation module for calculating the number of the N1 × OFDM symbols and the ith symbol_STSCorresponding to each space-time stream, i is more than or equal to 1_STS≤N_STSThen, the frequency-domain value carried by the kth sub-carrier corresponding to the nth 1 × OFDM symbol is multiplied by

I-th representing an orthogonal mapping matrix A_STSColumn col of row.

18. The transmitting end according to any one of claims 13 to 17, wherein the frequency offset module is specifically configured to shift a frequency domain sequence of the first 1 × OFDM symbol or the second 1 × OFDM symbol, and perform an inverse discrete fourier transform on the shifted frequency domain sequence to obtain a first 1 × OFDM symbol in a time domain or a second 1 × OFDM symbol in the time domain; or performing inverse discrete fourier transform on the first 1 × OFDM symbol or the second 1 × OFDM symbol to obtain a first 1 × OFDM symbol of a time domain or a second 1 × OFDM symbol of the time domain, and performing angle offset on the first 1 × OFDM symbol of the time domain or the second 1 × OFDM symbol of the time domain.

19. The transmitting end of claim 18, wherein the preset value is half of a subcarrier spacing corresponding to the 1 x OFDM symbol.

20. A receiving end, comprising:

a channel estimation module, configured to perform channel estimation according to the N1 × OFDM symbols;

21. The receiving end of claim 20, wherein the channel estimation module comprises:

a channel estimation sequence obtaining unit, configured to obtain a first channel estimation sequence and a second channel estimation sequence according to the first 1 × OFDM symbol and the second 1 × OFDM symbol;

a merging unit, configured to merge the first channel estimation sequence and the second channel estimation sequence into a third channel estimation sequence, where the third channel estimation sequence includes a plurality of channel estimation values;

and the interpolation unit is used for obtaining a channel estimation sequence at the position of the subcarrier corresponding to the 4 multiplied OFDM symbol after inserting a preset estimation value between every two adjacent channel estimation values.

22. The receiving end of claim 21, wherein the transmitting end comprises N_TXMore than or equal to 1 transmitting antenna, the receiving end comprises N_RXMore than or equal to 1 receiving antenna;

the channel estimation sequence obtaining unit is specifically configured to obtain a channel estimation value according to the first 1 × OFDM symbol and the second 1 × OFDM symbol

the channel estimates a first sequence as

The second sequence of the channel estimation is

23. The receiving end of claim 22, wherein the third sequence of channel estimates

24. Root of herbaceous plantReceiving end according to any of claims 21 to 23, characterized in that the interpolation unit is specifically adapted to interpolate channel estimates per neighbour

Insert preset estimate between

25. An information transmission and reception system in a wireless local area network, comprising a transmission end according to any one of claims 13 to 19 and a reception end according to any one of claims 20 to 24.