CN107113266B

CN107113266B - Channel estimation method and device of wireless local area network

Info

Publication number: CN107113266B
Application number: CN201480084356.6A
Authority: CN
Inventors: 卢伟山; 林梅露; 刘乐
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2014-12-31
Filing date: 2014-12-31
Publication date: 2019-12-24
Anticipated expiration: 2034-12-31
Also published as: CN107113266A; WO2016106753A1

Abstract

The embodiment of the invention provides a channel estimation method of a wireless local area network, which comprises the steps of generating a preset number of long training field LTF symbols; generating a reference pilot frequency symbol carried on an empty subcarrier, wherein the empty subcarrier corresponds to a preset resource block, and the precoding mode of the reference pilot frequency symbol is the same as that of the preset resource block; and sending the LTF symbol and the reference pilot frequency symbol to a station, wherein the LTF symbol and the reference pilot frequency symbol are used for the station to perform channel estimation on the subcarriers occupied by the preset resource block. The invention can greatly improve the accuracy of channel estimation and improve the system performance by using the channel estimation method of the spare subcarrier auxiliary interpolation.

Description

Channel estimation method and device of wireless local area network

Technical Field

The present invention relates to the field of communications technologies, and in particular, to a channel estimation method and apparatus for a wireless local area network.

Background

Orthogonal Frequency Division Multiplexing (OFDM) is a multi-carrier modulation technique, and is widely applied to fourth-generation cellular communication systems, such as Long-term evolution (LTE) and Worldwide Interoperability for microwave access (WiMAX) systems. The existing Wireless Local Access Network (WLAN) standard based on the OFDM technology is composed of versions of 802.11a, 802.11n, 802.11ac, and the like, which are evolved gradually. The IEEE802.11 standards organization has initiated standardization work for a new generation WLAN standard 802.11ax called HEW (High Efficiency wireless local area network), in which OFDMA (Orthogonal frequency division Multiple Access) is a key technology of 802.11 ax.

In a downlink OFDMA system, different resource blocks are allocated to different users, so an AP may use different precodes to communicate with different users on different resource blocks, at this time, a user cannot interpolate a full band to obtain channel information, and the user needs to extrapolate to estimate edge subcarrier channel information of a resource block.

Disclosure of Invention

The embodiment of the invention provides a channel estimation method and a channel estimation device of a wireless local area network, which are used for accurately estimating a channel.

In a first aspect, the present invention provides a channel estimation method for a wireless local area network, including:

generating a preset number of LTF symbols of the long training field;

generating a reference pilot frequency symbol carried on an empty subcarrier, wherein the empty subcarrier corresponds to a preset resource block, and the precoding mode of the reference pilot frequency symbol is the same as that of the preset resource block;

and sending the LTF symbol and the reference pilot frequency symbol to a station, wherein the LTF symbol and the reference pilot frequency symbol are used for the station to perform channel estimation on the subcarriers occupied by the preset resource block.

In a first possible implementation manner of the first aspect, the LTF symbol is specifically a compressed LTF symbol, and generating the compressed LTF symbol is specifically:

the number of the LTF symbols is +/-N_gN sub-carriers with pilot symbols added, N_gIs a positive integer, n is a subcarrier number;

performing Inverse Discrete Fourier Transform (IDFT) on the LTF symbol to obtain N_gA periodic time domain signal;

intercepting the N_gObtaining the compressed LTF symbol for one period of the periodic time domain signal.

In the first aspect or the first possible implementation manner of the first aspect, a second possible implementation manner of the first aspect is further provided, and the preset number of LTF symbols is specifically greater than or equal to the number of data streams.

In the first aspect or the first or second possible implementation manner of the first aspect, a third possible implementation manner of the first aspect is further provided, and includes:

and sending vacant sub-carrier mapping information to the STA, wherein the vacant sub-carrier mapping information represents the corresponding relation between the vacant sub-carriers and the preset resource blocks.

In a second aspect, the present invention provides a channel estimation method for a wireless local area network, including:

receiving a long training field LTF symbol and a reference pilot frequency symbol sent by an Access Point (AP);

determining first channel information of a preset resource block corresponding to a subcarrier carrying the LTF symbol according to the received LTF symbol;

determining second channel information of vacant sub-carriers bearing the reference pilot symbols corresponding to the preset resource block according to the received reference pilot symbols;

and determining third channel information of all subcarriers of the preset resource block according to the first channel information and the second channel information.

In a first possible implementation manner of the second aspect, the method includes:

and receiving vacant subcarrier mapping information sent by an access point AP, wherein the vacant subcarrier mapping information represents the corresponding relation between vacant subcarriers and preset resource blocks.

In a third aspect, the present invention provides a channel estimation method for a wireless local area network, including:

generating a preset number of LTF symbols of the long training field;

generating a phase tracking pilot frequency symbol, wherein the phase tracking pilot frequency symbol is borne on at least one most marginal subcarrier of a preset resource block, and the precoding mode of the phase tracking pilot frequency symbol is the same as that of the preset resource block;

and sending the LTF symbol and the phase tracking pilot frequency symbol to a station, wherein the LTF symbol and the phase tracking pilot frequency symbol are used for the station to carry out channel estimation on the subcarriers occupied by the preset resource block.

In a first possible implementation manner of the third aspect, the LTF symbol is specifically a compressed LTF symbol, and generating the compressed LTF symbol is specifically:

In the third aspect or the first possible implementation manner of the third aspect, a second possible implementation manner of the third aspect is further provided, and the preset number of LTF symbols is greater than or equal to the number of data streams.

In the third aspect or the first or second possible implementation manner of the third aspect, a third possible implementation manner of the third aspect is further provided, and includes:

and sending phase tracking pilot frequency symbol mapping information to the STA, wherein the phase tracking pilot frequency symbol mapping information represents the corresponding relation between the phase tracking pilot frequency symbols and the preset resource blocks.

In a fourth aspect, the present invention provides a channel estimation method for a wireless local area network, including:

receiving a long training field LTF symbol and a phase tracking pilot frequency symbol sent by an Access Point (AP);

determining second channel information of the most marginal sub-carrier carrying the phase tracking pilot frequency symbol in the preset resource block according to the received phase tracking pilot frequency symbol;

In a first possible implementation manner of the fourth aspect, the method includes:

and receiving phase tracking pilot frequency symbol mapping information sent by the AP, wherein the phase tracking pilot frequency symbol mapping information represents the corresponding relation between the phase tracking pilot frequency symbol and a preset resource block.

In a fifth aspect, the present invention provides a channel estimation method for a wireless local area network, including:

sending a long training field LTF symbol to a station;

and sending length information and user auxiliary information of the LTF symbols to the station, wherein the length information represents the compression multiple of the LTF symbols, and the user auxiliary information is used for indicating whether the station can use subcarriers of adjacent resource blocks for channel estimation in an auxiliary manner.

In a first possible implementation manner of the fifth aspect, the LTF symbol has a compression multiple of 1, 2, or 4.

In a sixth aspect, the present invention provides a channel estimation method for a wireless local area network, including:

receiving a Long Training Field (LTF) symbol, length information of the LTF symbol and user auxiliary information sent by an access point, wherein the length information represents a compression multiple of the LTF symbol, and the user auxiliary information is used for indicating whether a station can use a subcarrier of an adjacent resource block for channel estimation in an auxiliary manner;

and determining channel information of all subcarriers in the resource block according to the long training field LTF symbol, the length information and the user auxiliary information.

In a seventh aspect, the present invention provides a wireless local area network device, including:

a processor for generating a preset number of long training field LTF symbols;

and the transmitter is used for sending the LTF symbol and the reference pilot frequency symbol to a station, wherein the LTF symbol and the reference pilot frequency symbol are used for the station to perform channel estimation on the subcarriers occupied by the preset resource block.

In a first possible implementation manner of the seventh aspect, the processor is further configured to:

In the seventh aspect or the first possible implementation manner of the seventh aspect, a second possible implementation manner of the seventh aspect is further provided, where the preset number of LTF symbols is greater than or equal to the number of data streams.

In the seventh aspect or the first or second possible implementation manner of the seventh aspect, a third possible implementation manner of the seventh aspect is further provided, and the transmitter is further configured to:

In an eighth aspect, the present invention provides a wireless local area network device, including:

the receiver is used for receiving the long training field LTF symbol and the reference pilot frequency symbol sent by the access point AP;

the processor is used for determining first channel information of a preset resource block corresponding to a subcarrier carrying the LTF symbol according to the received LTF symbol;

In a first possible implementation manner of the eighth aspect, the receiver is further configured to:

In a ninth aspect, the present invention provides a wireless local area network device, including:

a processor for generating a preset number of long training field LTF symbols;

and the transmitter is used for sending the LTF symbol and the phase tracking pilot frequency symbol to a station, wherein the LTF symbol and the phase tracking pilot frequency symbol are used for the station to perform channel estimation on the subcarriers occupied by the preset resource block.

In a first possible implementation manner of the ninth aspect, the processor is further configured to:

In the ninth aspect or the first possible implementation manner of the ninth aspect, a second possible implementation manner of the ninth aspect is further provided, and the preset number of LTF symbols is specifically greater than or equal to the number of data streams.

In the ninth aspect or the first or second possible implementation manner of the ninth aspect, a third possible implementation manner of the ninth aspect is further provided, and the transmitter is further configured to:

In a tenth aspect, the present invention provides a wireless local area network device, including:

the receiver is used for receiving the LTF symbol and the phase tracking pilot frequency symbol of the long training field sent by the AP;

In a first possible implementation manner of the tenth aspect, the receiver is further configured to:

In an eleventh aspect, the present invention provides a wireless local area network apparatus, including:

a transmitter for transmitting long training field LTF symbols to a station;

In a first possible implementation manner of the eleventh aspect, the LTF symbol has a compression multiple of 1, 2, or 4.

In a twelfth aspect, the present invention provides a wireless local area network device, including:

the receiver is used for receiving a Long Training Field (LTF) symbol sent by an access point, length information of the LTF symbol and user auxiliary information, wherein the length information represents a compression multiple of the LTF symbol, and the user auxiliary information is used for indicating whether a station can use a subcarrier of an adjacent resource block for channel estimation in an auxiliary manner;

and the processor is used for determining the channel information of all subcarriers in the resource block according to the long training field LTF symbol, the length information and the user auxiliary information.

According to the technical scheme disclosed by the embodiment, the channel estimation method using the spare subcarrier auxiliary interpolation can greatly improve the accuracy of channel estimation and improve the system performance.

Drawings

FIG. 1 is a schematic diagram of the frame structure of 802.11a, 802.11n, 802.11 ac;

FIG. 2 is a schematic diagram of a frame structure of 802.11 ax;

fig. 3 is a schematic view of a WLAN deployment scenario;

fig. 4 is a schematic diagram of subcarriers according to embodiment 1 of the present invention;

FIG. 5 is a flowchart of a method of example 1 of the present invention;

fig. 6 is a schematic diagram of subcarrier indexes of LTF symbols in embodiment 1 of the present invention;

fig. 7 is a schematic diagram of spare subcarrier indexes according to embodiment 1 of the present invention;

FIG. 8 is a flowchart of a method in accordance with embodiment 2 of the present invention;

FIG. 9 is a flowchart of a method of embodiment 3 of the present invention;

fig. 10 is a schematic diagram of phase tracking pilot index according to embodiment 3 of the present invention;

FIG. 11 is a flowchart of a method according to embodiment 4 of the present invention;

FIG. 12 is a flowchart of a method in accordance with embodiment 5 of the present invention;

fig. 13 is a schematic diagram of subcarriers used for carrying channel estimation pilots in an LTF symbol according to embodiment 5 of the present invention;

fig. 14 is a schematic diagram of subcarriers used for carrying channel estimation pilots in another LTF symbol according to embodiment 5 of the present invention;

FIG. 15 is a flowchart of a method in accordance with embodiment 6 of the present invention;

FIG. 16 is a schematic view of an apparatus according to example 7 of the present invention;

FIG. 17 is a schematic view of an apparatus in accordance with example 8 of the present invention;

FIG. 18 is a schematic view of an apparatus in accordance with example 9 of the present invention;

FIG. 19 is a schematic view of an apparatus according to example 10 of the present invention;

FIG. 20 is a schematic view of an apparatus in accordance with example 11 of the present invention;

FIG. 21 is a schematic view of an apparatus according to embodiment 12 of the present invention.

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

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, 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 some, but not all, embodiments of the present invention. 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.

In the existing WLAN systems, there are great differences between frame structures of the respective systems, where the frame structures of 802.11a, 802.11n, and 802.11ac are shown in fig. 1, and fig. 1 is only used for explaining an exemplary frame structure, and does not represent actual field lengths and the like. The frame structures of the 3 systems all have the same Legacy prefix field (Legacy Preamble), and specifically include a Legacy Short Training field (L-STF), a Legacy Long Training field (L-LTF), and a Legacy signaling field (L-SIG). After the Legacy Preamble field, 802.11a includes a Data field (Data), and 802.11n includes a High Throughput signaling field (HT-SIG), a High Throughput Short Training field (HT-Short Training field, HT-STF), a High Throughput Long Training field (HT-LTF), and a Data field (Data), respectively, and 802.11ac includes a Very High Throughput signaling a field (Very High Throughput signaling-a field, VHT-SIG-a), a Very High Throughput Short Training field (Very High Throughput Short Training field, VHT-STF), a Very High Throughput Long Training field (Very High Throughput signaling-B), and a Very High Throughput signaling a field (Very High Throughput signaling-a field, VHT-SIG-a), a Very High Throughput Short Training field (VHT-LTF), a Very High Throughput Long Training field (VHT-ltb), and a Very High Throughput signaling field (VHT-SIG-B).

In the subsequent evolution process of the WLAN, optionally, a future possible WLAN standard, such as 802.11ax or other possible WLAN standards, is provided. Further optionally, taking 802.11ax as an example, a possible frame structure is shown in fig. 2, in order to be backward compatible with a WLAN device adopting an existing system, a beginning portion of a frame of 802.11ax is also a Legacy Preamble field, that is, the frame includes L-STF, L-LTF and L-SIG fields. The L-SIG field is followed by a High Efficiency wireless local area network signaling field 1(High Efficiency Signal-1 field, HE-SIG-1) and a High Efficiency wireless local area network signaling field 2(High Efficiency Signal-1 field, HE-SIG-2), followed by a High Efficiency wireless local area network Short Training field (HE-STF), a High Efficiency wireless local area network Long Training field (HE-LTF), a High Efficiency wireless local area network signaling B field (High Efficiency Signal-A field, HE-SIG-B), and followed by a Data field (Data).

It should be noted that, in the future possible WLAN standards, the names of the standards or the names of the fields, etc. may be replaced by any other names, and should not be considered as limiting the scope of the present invention.

A typical WLAN deployment scenario is shown in fig. 3, and includes an Access Point (AP) and at least one Station (STA). Illustratively, in the scenario illustrated in fig. 3, the AP communicates with STA1 and STA2, respectively.

The Station (STA) may be a wireless communication chip, a wireless sensor or a wireless communication terminal. For example: the mobile phone supporting the Wireless Fidelity (WiFi) communication function, the tablet computer supporting the WiFi communication function, the set top box supporting the WiFi communication function, the smart television supporting the WiFi communication function, the smart wearable device supporting the WiFi communication function, and the computer supporting the WiFi communication function. Optionally, a station may only support the 802.11ax system, and further optionally, the station may also support multiple WLAN systems such as 802.11ac, 802.11n, 802.11g, 802.11b, and 802.11 a.

An Access Point (AP) is also called as a wireless Access Point or a hotspot. The AP is a special station, can provide access service for the station, can be an access point for a mobile user to enter a wired network, and is mainly deployed in a home, a building and a garden, and typically has a coverage radius of several tens of meters to hundreds of meters, and certainly, can also be deployed outdoors. The AP acts as a bridge connecting the network and the wireless network, and mainly functions to connect the wireless network clients together and then to access the wireless network to the ethernet. The standard mainly used by APs at present is the Institute of Electrical and Electronics Engineers (IEEE) 802.11 series. Specifically, the AP may be a terminal device or a network device with a WiFi chip. Optionally, the AP may be a device supporting 802.11ax standard, and further optionally, the AP may be a device supporting multiple wireless local area network standards such as 802.11ac, 802.11n, 802.11g, 802.11b, and 802.11 a.

In one embodiment, the subcarriers of the DATA field are allocated to a plurality of resource blocks, so that different resource blocks are flexibly allocated to different stations, and the resource blocks are used for carrying uplink and downlink DATA of the corresponding stations; wherein, at least two continuous resource blocks have subcarriers which are not used for carrying data. Such subcarriers between two consecutive resource blocks that do not carry data are referred to as free subcarriers.

As shown in fig. 4, for an implementation of WLAN conforming to 802.11ax, the number of Discrete Fourier Transform (DFT)/Inverse Discrete Fourier Transform (Inverse DFT, IDFT) points in the DATA field is 256, that is, there are 256 subcarriers, where subcarriers-1, 0, 1 are Direct Current (DC), and subcarriers-122 to-2 and subcarriers 2 to 122 are used for carrying DATA information, that is, there are 242 subcarriers for carrying DATA information. Sub-carrier-128 to sub-carrier-123 and sub-carrier 123 to sub-carrier 128 are guard bands. The 242 subcarriers for carrying data information are divided into 9 resource blocks, each resource block is 26 subcarriers, and the remaining 8 unused subcarriers. These 9 resource blocks occupy subcarrier-122 to subcarrier-97 (resource block 1), subcarrier-95 to subcarrier-70 (resource block 2), subcarrier-68 to subcarrier-43 (resource block 3), subcarrier-41 to subcarrier-16 (resource block 4), subcarrier-14 to subcarrier 14 (resource block 5), subcarrier 16 to subcarrier 41 (resource block 6), subcarrier 43 to subcarrier 68 (resource block 7), subcarrier 70 to subcarrier 95 (resource block 8), subcarrier 97 to subcarrier 122 (resource block 9), respectively, the remaining 8 unused subcarriers are subcarriers-96, -69, -42, -15, 42, 69, 96, which are referred to herein as spare subcarriers.

Fig. 4 is merely an example, and the allocation of the subcarriers and resource blocks of the DATA field may be in other forms.

Embodiment 1 of the present invention provides a method for sending channel estimation information of a wireless local area network, which is used for channel estimation in a WLAN system. The method flow of this embodiment is shown in fig. 5, and the specific steps are as follows:

s101, generating a preset number of long training field LTF symbols;

s102, generating a reference pilot frequency symbol borne on an empty subcarrier, wherein the empty subcarrier corresponds to a preset resource block, and the precoding mode of the reference pilot frequency symbol is the same as that of the preset resource block;

s103, sending the LTF symbol and the reference pilot frequency symbol to a station, wherein the LTF symbol and the reference pilot frequency symbol are used for the station to perform channel estimation on the subcarriers occupied by the preset resource block.

In 802.11ax, Data uses 4 times the DFT points of the Legacy Preamble field, called 4x length symbols, for which HE-LTF needs to provide 4x channel estimation, i.e. HE-LTF also needs to use 4x length symbols.

The bandwidth supported by the AP can be divided into S resource blocks, the index of each resource block is S, the AP schedules K users for downlink transmission, and the AP allocates S to each user_kResource blocks, without loss of generality, it is assumed here that each resource block can only be allocated to one user, i.e. there isAnd the AP performs M with each user_kAnd transmitting the data stream.

In S101, the AP generates a preset number of LTF symbols, where the preset number may be determined according to system parameters, but is not limited to be determined according to the system parameters, and when there are multiple data streams to be transmitted, multiple HE-LTFs are required to implement channel estimation. Further optionally, the preset number is greater than or equal to

Optionally, the AP generates a preset number of compressed LTF symbols, and for any compressed LTF symbol, the generation method is specifically as follows:

s1011 numbered as +/-N in LTF symbol_gN sub-carriers with pilot symbols added, N_gIs a positive integer, optionally, N_g＝4，n＝1，2，3...；

S1012, precoding each pilot frequency symbol, wherein the adopted precoding mode is the same as the precoding mode used by the resource block bearing the pilot frequency symbol;

s1013, IDFT conversion is carried out on the LTF symbol to obtain N_gA time domain signal waveform of a cycle;

s1014, intercepting N_gOne period of the time domain signal waveform forms a compressed LTF symbol.

Since the compressed LTF sequence is used, for example, the compression multiple is 4, the AP/STA can estimate channel information of the subcarrier index as shown in fig. 6 by using the compressed LTF sequence, and the AP/STA can interpolate the channel information of the subcarrier index by using an interpolation operation, and by using the channel information, the AP/STA can equalize and decode data carried by each subcarrier.

In S102, the AP generates a plurality of data symbols, and in each data symbol, allocates a free subcarrier to a preset resource block, where the preset resource block is a resource block allocated to a specific STA, and the preset resource block may be, but is not limited to, determined according to a system resource allocation manner, a user resource scheduling manner, and the like. Illustratively, as shown in fig. 7, in a system with a 20M bandwidth, the whole bandwidth is divided into 9 resource blocks, the number of vacant subcarriers in a data symbol is 8, a subcarrier-96 is allocated to a resource block 1, a subcarrier-69 is allocated to a resource block 2, a subcarrier-42 is allocated to a resource block 3, a subcarrier-15 and a subcarrier-15 are allocated to a resource block 5, a subcarrier 42 is allocated to a resource block 7, a subcarrier 69 is allocated to a resource block 8, and a subcarrier 96 is allocated to a resource block 9.

Optionally, this embodiment may further include:

s1020, sending vacant sub-carrier mapping information to the STA, wherein the vacant sub-carrier mapping information represents the corresponding relation between the vacant sub-carriers and the preset resource blocks.

Specifically, the relationship between the vacant subcarrier and the preset resource block may be that the vacant subcarrier corresponds to one or more adjacent preset resource blocks, the vacant subcarrier corresponds to one or more preset resource blocks specified in advance, or other mapping manners known to those skilled in the art, which is not limited in this embodiment.

And the AP carries out precoding on each reference pilot frequency symbol carried by the empty and spare sub-carriers, wherein the adopted precoding mode is the same as the precoding mode used by the preset resource block. For example, for a resource block s, which is allocated to a user k, and a vacant subcarrier n 'is allocated to the resource block s for assisting the user k in channel estimation on an edge subcarrier of the resource block s, a signal after precoding preprocessing of a channel estimation reference pilot symbol filled by the vacant subcarrier n' can be represented as:

y_n′＝W_k，n′x_n′

wherein, W_k，n′M x M of free sub-carrier n' for user k_kA precoding matrix, x_n′M in vacant sub-carrier n' for user k_kX 1 channel estimation reference pilot symbols.

As will be appreciated by those skilled in the art, the above methods include:

s101a, generating a preset number of LTF symbols of the long training fields, wherein the preset number is larger than or equal to the number of data streams;

s102a, generating a reference pilot symbol, where the reference pilot symbol is carried on vacant sub-carriers, each vacant sub-carrier unit (which may be 1 or more vacant sub-carriers according to the situation of continuous spatial sub-carriers) corresponds to a preset one or more resource blocks, and the precoding mode of the reference pilot symbol is the same as that of the corresponding preset resource block; wherein the free subcarriers are subcarriers between two consecutive resource blocks;

s103, generating data symbols, wherein the data symbols aiming at different target stations are borne in different preset or allocated resource blocks;

the above generation process does not limit the execution order, and the order depends on the data structure in the new WLAN system (e.g. 802.11 ax).

And S104, sending the LTF symbol, the reference pilot symbol and a data symbol, wherein the LTF symbol and the reference pilot symbol are used for the target station to perform channel estimation on the resource block of the target station so as to analyze the corresponding data symbol.

In the downlink OFDMA system, different resource blocks are allocated to different users, so the AP may use different precodes to communicate with different users on different resource blocks, at this time, the users cannot interpolate the full band to obtain the channel information of subcarriers-122 to subcarrier-2 and subcarriers 2 to subcarrier 122, and if the compressed LTF is used for channel estimation, the users need to extrapolate to estimate the edge subcarrier channel information of the resource block, but the channel information is inaccurate, and the performance loss is severe in the case of a high MCS. According to the technical scheme disclosed by the embodiment, the channel estimation method using the spare subcarrier auxiliary interpolation can greatly improve the accuracy of channel estimation and improve the system performance.

Embodiment 2 of the present invention provides a channel estimation method for a wireless local area network, which is used for channel estimation in a WLAN system. The method flow of this embodiment is shown in fig. 8, and the specific steps are as follows:

s201, receiving a long training field LTF symbol and a reference pilot frequency symbol sent by an access point AP;

s202, according to the received LTF symbol, determining first channel information of a preset resource block corresponding to a subcarrier carrying the LTF symbol;

s203, determining second channel information of the vacant sub-carriers bearing the reference pilot symbols corresponding to the preset resource block according to the received reference pilot symbols;

s204, determining third channel information of all subcarriers of the preset resource block according to the first channel information and the second channel information.

Optionally, before S201, this embodiment may further include:

s200, receiving vacant subcarrier mapping information sent by an access point AP, wherein the vacant subcarrier mapping information represents the corresponding relation between vacant subcarriers and preset resource blocks. For example, in fig. 7, it is assumed that user 1 allocates resource block 2, that is, resource block 2 is a preset resource block of user 1, and user 1 receives multiple LTF symbols and estimates channel information of subcarriers carrying channel estimation pilot symbols in resource block 2, that is, channel information of subcarrier-96, subcarrier-92, subcarrier-88,.. sub-carrier-76, and subcarrier-72. User 1 receives the reference pilot symbols and estimates the channel information for sub-carrier-69. Finally, the user 1 obtains the channel information of the subcarriers-95 to-72, i.e. each subcarrier of the resource block 2, according to the channel information of the subcarriers-96, the subcarriers-92, the subcarriers-88, the.

In this embodiment, the first channel information refers to channel information of subcarriers carrying LTF symbols in a preset resource block, the second channel information refers to channel information of spare subcarriers carrying reference pilot symbols in the preset resource block, and the third channel information refers to channel information of all subcarriers of the preset resource block.

The specific method for determining the first channel information according to the LTF symbols in S202 and the second channel information according to the reference pilot symbols in S203 is not limited in this patent application, and those skilled in the art may implement the method by using any one or a combination of multiple prior art, and will not be described herein again.

According to the first channel information determined in S202 and the second channel information determined in S203, in S204, the channel information of each subcarrier in the preset resource block may be determined, but is not limited to, by using an interpolation algorithm or the like.

Embodiment 3 of the present invention provides a channel estimation method for a wireless local area network, which is used for channel estimation in a WLAN system. The method flow of this embodiment is shown in fig. 9, and the specific steps are as follows:

s301, generating a preset number of LTF symbols of the long training field;

s302, generating a phase tracking pilot frequency symbol, wherein the phase tracking pilot frequency symbol is borne on at least one most marginal subcarrier of a preset resource block, and the precoding mode of the phase tracking pilot frequency symbol is the same as that of the preset resource block;

and S303, sending the LTF symbol and the phase tracking pilot frequency symbol to a station, wherein the LTF symbol and the phase tracking pilot frequency symbol are used for the station to perform channel estimation on the subcarriers occupied by the preset resource block.

Wherein the content of the first and second substances,in S101, the AP generates a preset number of LTF symbols, where the preset number may be determined, but is not limited to be determined according to system parameters, and when there are multiple data streams to be transmitted, multiple HE-LTFs are required to implement channel estimation. Further optionally, the preset number is greater than or equal to

The AP generates a compressed LTF symbol, and a specific embodiment thereof may refer to S101, which is not described herein again.

In S302, the phase tracking pilot symbols are used to assist the user in tracking the phase rotation of each OFDM symbol. Since there is a residual frequency offset between the transmitting end and the receiving end, the receiving end may experience a phase rotation when receiving the OFDM symbol. For example, considering the p-th OFDM symbol, the received signals at n subcarriers after being affected by phase rotation are:

wherein the equivalent channel estimation of the receiving end is h_p，nw_p，n，x_p，nIs a phase tracking pilot symbol that is,is phase rotation of the p-th OFDM symbol, so that the receiving end can estimateNamely, it is

Therefore, in order for the receiving end to track the phase rotation of each OFDM symbol on the resource block of the OFDM symbol, at least one edge-most subcarrier may be used for carrying the phase tracking pilot symbol in the resource block, and in particular, the subcarrier a and the subcarrier B are edge-most subcarriers assuming that the resource block occupies subcarriers a to B.

Optionally, as shown in fig. 10, under a bandwidth of 20M, the system can divide 9 resource blocks, where the last edge subcarrier-97 of the resource block 1, the last edge subcarrier-70 of the resource block 2, the last edge subcarrier-43 of the resource block 3, the last edge subcarrier-41 of the resource block 4, the last edge subcarriers-14 and 14 of the resource block 5, the last edge subcarrier 41 of the resource block 6, the last edge subcarrier 43 of the resource block 7, the last edge subcarrier 70 of the resource block 8, and the last edge subcarrier 97 of the resource block 9 are used to carry phase tracking pilot symbols of the corresponding resource block.

Optionally, this embodiment may further include:

s3020, sending phase tracking pilot symbol mapping information to the STA, wherein the phase tracking pilot symbol mapping information represents a corresponding relation between a phase tracking pilot symbol and a preset resource block.

And the AP carries out precoding on the phase tracking pilot frequency symbol carried on the most marginal subcarrier, and the adopted precoding mode is the same as the precoding mode used by the preset resource block. For a specific implementation of precoding, reference may be made to S102, which is not described herein again.

As will be appreciated by those skilled in the art, the above methods include:

s301a, generating a preset number of LTF symbols of the long training field;

s302a, generating a phase tracking pilot symbol, wherein the phase tracking pilot symbol is carried on at least one most marginal subcarrier of a preset resource block, and the precoding mode of the phase tracking pilot symbol is the same as that of the corresponding preset resource block;

s303a, generating data symbols, where the data symbols for different target stations are carried in different preset or allocated resource blocks;

S304, the LTF symbol, the phase tracking pilot symbol and the data symbol are sent, and the LTF symbol and the reference pilot symbol are used for the target station to perform channel estimation on the resource block of the target station so as to analyze the corresponding data symbol.

In the technical scheme disclosed in this embodiment, the method for performing channel estimation by using phase tracking pilot symbol assisted interpolation can greatly improve the accuracy of channel estimation and improve the system performance.

It should be noted that the solutions disclosed in embodiment 1 and embodiment 3 of the present invention are not completely contradictory, and in some scenarios, a person skilled in the art may easily think that the solutions disclosed in the two embodiments are simultaneously adopted and combined to further improve the accuracy of channel estimation, and the solution combined by the two embodiments is also within the protection scope of the present invention.

Embodiment 4 of the present invention provides a channel estimation method for a wireless local area network, which is used for channel estimation in a WLAN system. The method flow of this embodiment is shown in fig. 11, and the specific steps are as follows:

s401, receiving a long training field LTF symbol and a phase tracking pilot symbol sent by an access point AP;

s402, according to the received LTF symbol, determining first channel information of a preset resource block corresponding to a subcarrier carrying the LTF symbol;

s403, according to the received phase tracking pilot symbol, determining second channel information of the most marginal sub-carrier carrying the phase tracking pilot symbol in the preset resource block;

s404, determining third channel information of all subcarriers of the preset resource block according to the first channel information and the second channel information.

Optionally, before S401, this embodiment may further include:

s400, receiving phase tracking pilot symbol mapping information sent by the AP, wherein the phase tracking pilot symbol mapping information represents the corresponding relation between a phase tracking pilot symbol and a preset resource block. For example, as shown in fig. 10, user 1 is assigned resource block 2, that is, resource block 2 is a preset resource block of user 1, and user 1 receives multiple LTF symbols and estimates channel information of subcarriers used for carrying channel estimation pilot symbols in resource block 2, that is, channel information of subcarrier-96, subcarrier-92, subcarrier-88,.. subcarrier-76, and subcarrier-72. User 1 receives the phase tracking pilot symbol and estimates the channel information of the edge-most sub-carrier-70 according to the edge-most sub-carrier-70 carrying the phase tracking pilot. Finally, the user 1 obtains the channel information of the subcarriers-95 to-72, i.e. each subcarrier of the resource block 2, according to the channel information of the subcarriers-96, the subcarriers-92, the subcarriers-88, the subcarriers-76, the subcarriers-72 and the subcarriers-70.

In this embodiment, the first channel information refers to channel information of a subcarrier carrying an LTF symbol in a preset resource block, the second channel information refers to channel information of a most marginal subcarrier carrying a phase tracking pilot symbol in the preset resource block, and the third channel information refers to channel information of all subcarriers of the preset resource block.

The specific method for determining the first channel information according to the LTF symbols in S402 and the second channel information according to the reference pilot symbols in S403 is not limited in this patent application, and those skilled in the art may implement the method by using any one or a combination of multiple prior art, and will not be described herein again.

Based on the first channel information determined in S402 and the second channel information determined in S403, in S404, the channel information of each subcarrier in the preset resource block may be determined, but is not limited to, by using an interpolation algorithm or the like.

It should be noted that the solutions disclosed in embodiment 2 and embodiment 4 of the present invention are not completely contradictory, and in some scenarios, a person skilled in the art may easily think that the solutions disclosed in the two embodiments are simultaneously adopted and combined to further improve the accuracy of channel estimation, and the solution combined by the two embodiments is also within the protection scope of the present invention.

Embodiment 5 of the present invention provides a channel estimation method for a wireless local area network, which is used for channel estimation in a WLAN system. The method flow of this embodiment is shown in fig. 12, and the specific steps are as follows:

s501, sending a long training field LTF symbol to a site;

s502, sending length information of the LTF symbols and user auxiliary information to the station, wherein the length information represents compression multiples of the LTF symbols, and the user auxiliary information is used for indicating whether the station can use subcarriers of adjacent resource blocks for channel estimation in an auxiliary mode.

In S501, the AP generates an LTF symbol, and the specific implementation thereof may refer to S101, which is not described herein again.

In S502, the length information of the LTF symbol, i.e., the compression factor of the LTF symbol is N_g，N_gRefer to the definition in S1011. It should be noted that in 802.11ax, the LTF symbols have a one-to-one correspondence with length, illustratively, the length is 3.2us when the compression factor is 4 and 12.8us when the LTF is not compressed. Therefore, in S502, the length information of the LTF symbol can be characterized as a compression multiple or a length, and other equivalent representation methods are within the scope of the present invention.

Optionally, if the LTF symbol may be compressed by 4 times, compressed by 2 times, or uncompressed, the length information of the LTF symbol has three possible values, and two bits are required for indication, further optionally, 00 may be used to indicate that the LTF is compressed by 4 times, 01 indicates that the LTF is compressed by 2 times, and 11 indicates that the LTF symbol is not compressed. The present application does not limit the number of bits of the length information, and those skilled in the art may set the length information according to system parameters, system design requirements, and the like.

Alternatively, the user assistance information may be indicated by 1 bit, where bit 0 indicates that the station uses subcarrier-assisted channel estimation of adjacent resource blocks, and bit 1 indicates that the station does not use subcarrier-assisted channel estimation of adjacent resource blocks. For example, when all resource blocks are not pre-processed with pre-coding, the bit may be set to 0 to indicate that the station uses subcarrier-assisted channel estimation of adjacent resource blocks. When the resource block is pre-processed with different pre-coding, this bit may be set to 1 to indicate that the station does not use subcarrier-assisted channel estimation of adjacent resource blocks.

Exemplary, N_gLTF symbol of 4, user 1 assignsWith resource block 2, then user 1 knows that resource block 2 has subcarrier indices of-96, -92, -88, -84, -80, 76, -72 in the LTF symbol for carrying the channel estimation pilot. With the user assistance information, user 1 may determine whether channel estimation for the edge subcarriers of resource block 2 can be performed with subcarrier-68 assistance for resource block 3.

Further optionally, when the LTF symbol is compressed by 4 times, the subcarriers of each resource block in the LTF symbol for carrying the channel estimation pilot are as shown in fig. 13, and when the LTF symbol is compressed by 2 times, the subcarriers of each resource block in the LTF symbol for carrying the channel estimation pilot are as shown in fig. 14.

In the technical scheme disclosed in this embodiment, the method for channel estimation by user-assisted interpolation can greatly improve the accuracy of channel estimation and improve the system performance.

It should be noted that, in some scenarios, the technical solution disclosed in embodiment 5 of the present invention may be used in combination with the solutions disclosed in embodiment 1 and embodiment 3 of the present invention to further improve the accuracy of channel estimation, and the solutions used in combination of these two embodiments are also within the scope of the present invention.

For example, in S502, when the user assistance information indicates that the station cannot perform channel estimation using subcarrier assistance of adjacent resource blocks, the channel estimation may be performed by separately combining the technical solutions disclosed in embodiment 1 or embodiment 3, or may be performed by simultaneously combining the technical solutions disclosed in embodiment 1 and embodiment 3. It is easy to think that even when the user assistance information indicates that the station can use the subcarrier assistance of the adjacent resource block for channel estimation, the new technical solution generated by the combination of the above embodiments is within the protection scope of the present invention.

Embodiment 6 of the present invention provides a channel estimation method for a wireless local area network, which is used for channel estimation in a WLAN system. The method flow of this embodiment is shown in fig. 15, and the specific steps are as follows:

s601, receiving a Long Training Field (LTF) symbol sent by an access point, length information of the LTF symbol and user auxiliary information, wherein the length information represents a compression multiple of the LTF symbol, and the user auxiliary information is used for indicating whether a station can use a subcarrier of an adjacent resource block for channel estimation in an auxiliary manner;

s602, determining channel information of all subcarriers in a resource block according to the long training field LTF symbol, the length information and the user auxiliary information.

Exemplary, N_gWhen the number is 4, user 1 is assigned resource block 2, and according to the length information of the received LTF symbol, user 1 determines that the subcarrier index of resource block 2 in the LTF symbol for carrying the channel estimation pilot is-96, -92, -88, -84, -80, 76, and-72, and further determines whether the channel estimation of the edge subcarrier of resource block 2 can be improved by using subcarrier-68 of resource block 3 in an auxiliary manner according to the received user auxiliary information.

Embodiment 7 of the present invention provides a wireless local area network apparatus 70, configured to perform channel estimation in a WLAN system, as shown in fig. 16, including:

a processor 701, configured to generate a preset number of long training field LTF symbols, and generate a reference pilot symbol carried on an empty subcarrier, where the empty subcarrier corresponds to a preset resource block, and a precoding manner of the reference pilot symbol is the same as a precoding manner of the preset resource block;

a transmitter 702, configured to send the LTF symbol and the reference pilot symbol to a terminal, where the LTF symbol and the reference pilot symbol are used for the terminal to perform channel estimation on subcarriers occupied by the preset resource block.

Optionally, the processor 701 is further configured to:

Further optionally, the preset number of LTF symbols is greater than or equal to the number of data streams.

Optionally, the transmitter 702 is further configured to:

The apparatus 70 disclosed in this embodiment can be used to execute the method disclosed in embodiment 1 of the present invention, and is not described herein again.

An embodiment 8 of the present invention provides a wireless local area network apparatus 80, configured to perform channel estimation in a WLAN system, as shown in fig. 17, including:

a receiver 801, configured to receive a long training field LTF symbol and a reference pilot symbol sent by an access point AP;

a processor 802, configured to determine, according to the received LTF symbol, first channel information of a preset resource block corresponding to a subcarrier carrying the LTF symbol;

Optionally, the receiver 801 is further configured to:

The apparatus 80 disclosed in this embodiment can be used to perform the method disclosed in embodiment 2 of the present invention, and is not described herein again.

Embodiment 9 of the present invention provides a wireless local area network apparatus 90, configured to perform channel estimation in a WLAN system, as shown in fig. 18, including:

a processor 901, configured to generate a preset number of long training field LTF symbols;

a transmitter 902, configured to send the LTF symbol and the phase tracking pilot symbol to a station, where the LTF symbol and the phase tracking pilot symbol are used for the station to perform channel estimation on subcarriers occupied by the preset resource block.

Optionally, the processor 901 is further configured to:

Optionally, the transmitter 902 is further configured to:

The apparatus 90 disclosed in this embodiment can be used to execute the method disclosed in embodiment 3 of the present invention, and is not described herein again.

It should be noted that the solutions disclosed in embodiment 7 and embodiment 9 of the present invention are not completely contradictory, and in some scenarios, a person skilled in the art may easily think that the solutions disclosed in the two embodiments are simultaneously adopted and combined to further improve the accuracy of channel estimation, and the solution combined by the two embodiments is also within the protection scope of the present invention.

An embodiment 10 of the present invention provides a wireless local area network apparatus 100, configured to perform channel estimation in a WLAN system, as shown in fig. 19, including:

a receiver 1001, configured to receive a long training field LTF symbol and a phase tracking pilot symbol sent by an access point AP;

a processor 1002, configured to determine, according to the received LTF symbol, first channel information of a preset resource block corresponding to a subcarrier carrying the LTF symbol;

Optionally, the receiver 1001 is further configured to:

The apparatus 100 disclosed in this embodiment can be used to execute the method disclosed in embodiment 4 of the present invention, and is not described herein again.

It should be noted that the solutions disclosed in the embodiment 80 and the embodiment 100 are not completely contradictory, and in some scenarios, a person skilled in the art may easily think that the solutions disclosed in the two embodiments are adopted simultaneously and combined to further improve the accuracy of channel estimation, and the solution combined by the two embodiments is also within the protection scope of the present invention.

An embodiment 11 of the present invention provides a wireless local area network apparatus 110, configured to perform channel estimation in a WLAN system, as shown in fig. 20, including:

a transmitter 1101 for transmitting long training field LTF symbols to a station;

Optionally, wherein the LTF symbol has a compression multiple of 1, 2, or 4.

The apparatus 110 disclosed in this embodiment can be used to execute the method disclosed in embodiment 5 of the present invention, and is not described herein again.

It should be noted that, in some scenarios, the technical solution disclosed in embodiment 11 of the present invention may be used in combination with the solutions disclosed in embodiment 7 and embodiment 9 of the present invention to further improve the accuracy of channel estimation, and the solutions used in combination of these two embodiments are also within the scope of the present invention.

An embodiment 12 of the present invention provides a wireless local area network device 120, configured to perform channel estimation in a WLAN system, as shown in fig. 21, where the device includes:

a receiver 1201, configured to receive a long training field LTF symbol sent by an access point, length information of the LTF symbol, and user assistance information, where the length information represents a compression multiple of the LTF symbol, and the user assistance information is used to indicate whether a station can use a subcarrier of an adjacent resource block for channel estimation;

a processor 1202, configured to determine channel information of all subcarriers in a resource block according to the long training field LTF symbol, the length information, and the user assistance information.

The apparatus 120 disclosed in this embodiment can be used to execute the method disclosed in embodiment 6 of the present invention, and is not described herein again.

The apparatus provided in the embodiment of the present invention may be applied to an AP or an STA, and may specifically include a fixed station such as a WLAN router, a WLAN switch, a computer, a server, and the like, and may also include a mobile station such as a mobile phone, a tablet computer, a wearable device, a notebook computer, and the like. Further, the receiver or the transmitter may be a dedicated receiving device or a dedicated transmitting device, or may be a transceiver device integrating receiving and transmitting functions. The processor may be an Integrated Circuit (IC), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA), or the like, and may also be Integrated in a baseband processor or a general-purpose processor.

Through the above description of the embodiments, those skilled in the art will clearly understand that the present invention can be implemented by software plus necessary general hardware. Based on such understanding, all or part of the steps in the technical solution of the present invention may be implemented by instructing the relevant hardware through a program, where the program may be stored in a computer-readable storage medium, and when the program is executed, the program includes the steps of the above method embodiments, and the storage medium, such as: ROM/RAM, magnetic disk, optical disk, etc.

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 claims.

Claims

1. A method for channel estimation in a wireless local area network, the method comprising:

generating a preset number of LTF symbols of the long training field;

2. The method according to claim 1, wherein the LTF symbol is in particular a compressed LTF symbol, and wherein generating the compressed LTF symbol is in particular:

performing inverse discrete Fourier transform (IDF) on the LTF symbolT, obtaining N_gA periodic time domain signal;

3. The method according to claim 1 or 2, wherein the preset number of LTF symbols is in particular greater than or equal to the number of data streams.

4. The method according to claim 1 or 2, characterized in that the method further comprises:

5. A method for channel estimation in a wireless local area network, the method comprising:

6. The method of claim 5, further comprising:

7. A method for channel estimation in a wireless local area network, the method comprising:

generating a preset number of LTF symbols of the long training field;

8. The method according to claim 7, wherein the LTF symbol is a compressed LTF symbol, and wherein generating the compressed LTF symbol is specifically:

9. The method according to claim 7 or 8, wherein the preset number of LTF symbols is greater than or equal to the number of data streams.

10. The method according to claim 7 or 8, characterized in that the method further comprises:

11. A method for channel estimation in a wireless local area network, the method comprising:

12. The method of claim 11, further comprising:

13. A method for channel estimation in a wireless local area network, the method comprising:

sending a long training field LTF symbol to a station;

sending length information and user auxiliary information of the LTF symbols to the station, wherein the length information represents compression multiples of the LTF symbols, and the user auxiliary information is used for indicating whether the station can use subcarriers of adjacent resource blocks for channel estimation in an auxiliary mode;

the long training field LTF symbol, the length information, and the user assistance information are used by the station to determine channel information for all subcarriers in a resource block.

14. The method of claim 13, wherein the LTF symbols are compressed by a factor of 1, 2, or 4.

15. A method for channel estimation in a wireless local area network, the method comprising:

16. An apparatus of a wireless local area network, the apparatus comprising:

a processor for generating a preset number of long training field LTF symbols;

17. The apparatus of claim 16, wherein the processor is further configured to:

intercepting the N_gOne period of the periodic time domain signal, a compressed LTF symbol is obtained.

18. The apparatus according to claim 16 or 17, wherein the preset number of LTF symbols is greater than or equal to the number of data streams.

19. The apparatus of claim 16 or 17, wherein the transmitter is further configured to:

20. An apparatus of a wireless local area network, the apparatus comprising:

21. The apparatus of claim 20, wherein the receiver is further configured to:

22. An apparatus of a wireless local area network, the apparatus comprising:

a processor for generating a preset number of long training field LTF symbols;

23. The apparatus of claim 22, wherein the processor is further configured to:

24. The apparatus according to claim 22 or 23, wherein the preset number of LTF symbols is greater than or equal to the number of data streams.

25. The apparatus of claim 22 or 23, wherein the transmitter is further configured to:

26. An apparatus of a wireless local area network, the apparatus comprising:

27. The apparatus of claim 26, wherein the receiver is further configured to:

28. An apparatus of a wireless local area network, the apparatus comprising:

a transmitter for transmitting long training field LTF symbols to a station;

29. The apparatus of claim 28, wherein the LTF symbols are compressed by a factor of 1, 2, or 4.

30. An apparatus of a wireless local area network, the apparatus comprising: