CN113452635B

CN113452635B - Method, station and access point for frequency offset estimation

Info

Publication number: CN113452635B
Application number: CN202010228622.5A
Authority: CN
Inventors: 陈正; 袁方超; 陈鹏
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2020-03-27
Filing date: 2020-03-27
Publication date: 2022-12-27
Anticipated expiration: 2040-03-27
Also published as: WO2021190527A1; CN113452635A

Abstract

The application provides a method for frequency offset estimation, a station STA and an access point AP. The method for estimating the frequency offset can be applied to an uplink multi-site multi-input multi-output scene, and comprises the following steps: the AP instructs how to generate and report a frequency offset estimation training sequence by the STA through the first information, and determines the frequency offset between the AP and the STA based on the received at least two frequency offset estimation training sequences. The technical scheme provided by the application can improve the accuracy of the AP for acquiring the frequency offset values between the plurality of STAs and the AP respectively. The application can be applied to 802.11ax,802.11be and a future wireless local area network (WiFi) system.

Description

Method, station and access point for frequency offset estimation

Technical Field

The present application relates to the field of communications, and more particularly, to a method, station and access point for frequency offset estimation.

Background

With the development of wireless local area network technology, an uplink multi-site multi-input multi-output (UL MU-MIMO) technology is introduced, multiple uplink Sites (STAs) send data to an Access Point (AP) at the same time, and through a spatial multiplexing technology and orthogonal equalization at the AP side, interference between sites is eliminated, and the utilization rate of uplink spectrum resources is effectively increased.

However, the stations are various in types, and radio frequency links of the stations are different from one another, so that carrier frequencies used by the stations when transmitting data are difficult to be consistent, that is, frequency synchronization cannot be achieved when a plurality of stations transmit data to the AP. When channel estimation is performed on the AP side, it is difficult for channels of multiple stations to be orthogonal and crosstalk with each other, and channel estimation accuracy is greatly reduced. Therefore, how to improve the frequency offset value of multiple stations relative to the AP in the uplink multi-station channel mimo scenario becomes a problem to be solved urgently.

Disclosure of Invention

The application provides a method, a station and an access point for frequency offset estimation, so as to improve the accuracy of determining the frequency offset estimation by the access point.

In a first aspect, a method for frequency offset estimation is provided, where the method for frequency offset estimation may be performed by an access point AP, or may also be performed by a chip or a circuit disposed in the AP, which is not limited in this application.

The method for frequency offset estimation comprises the following steps:

the AP sends first information to an STA, wherein the first information is used for indicating the number M of spatial streams corresponding to the STA needing to report a first training sequence and a second training sequence and a first subcarrier subset occupied by the first training sequence or the second training sequence reported by the STA, the STA is any one of the STAs, the first subcarrier subset is a subcarrier subset corresponding to the STA in S preset subcarrier subsets, and M and S are positive integers and are used for determining the first training sequence or the second training sequence; the AP receives a physical layer protocol data unit, PPDU, from the STA on the first subset of subcarriers, where the PPDU includes the first and second training sequences for determining a frequency offset value between the STA and the AP.

According to the method for frequency offset estimation provided by the embodiment of the application, the AP indicates how the STA generates and reports the frequency offset estimation training sequence through the first information, and determines the frequency offset value between the AP and the STA based on the received at least two frequency offset estimation training sequences, so that the accuracy of determining the frequency offset estimation by the AP can be improved.

With reference to the first aspect, in certain implementations of the first aspect, the first information includes: first indication information and second indication information, the first indication information being used for indicating the M, the second indication information being used for determining the first subset of subcarriers.

The indication information indicating the number M of STAs and the indication information indicating the first subcarrier subset may be two different indication information, and provide different indication information sending modes, thereby improving the flexibility of the scheme.

With reference to the first aspect, in some implementations of the first aspect, the sending, by the AP, the first information to the STA includes: the AP sends a trigger frame to the STA, where the trigger frame is used to trigger the STA to report the PPDU, where the trigger frame carries the first indication information and the second indication information, and the first indication information is a scheduling information field.

According to the method for frequency offset estimation provided by the embodiment of the application, the first information which is sent by the AP and used for indicating how the STA generates and reports the frequency offset estimation training sequence can be used for multiplexing the trigger frame which is sent to the STA by the existing AP, so that the signaling overhead is saved, and the method can be compatible with the existing process and can improve the scheme compatibility.

With reference to the first aspect, in some implementations of the first aspect, the carrying the first indication information in the trigger frame includes: the trigger frame includes a general information field, and the general information field includes the first indication information.

Further, a possible implementation manner that the trigger frame includes the first indication information is that the general information field in the trigger frame carries the first indication information, and an existing field in the multiplexing trigger frame carries the first indication information, which can save signaling overhead.

With reference to the first aspect, in certain implementations of the first aspect, the first training sequence or the second training sequence is determined by a mapping relationship between the STA and elements of a P matrix.

The first training sequence or the second training sequence can be determined based on the elements corresponding to the STA in the preset P matrix, and a manner of determining the first training sequence or the second training sequence based on the known P matrix is provided, so that the compatibility with the existing scheme can be increased without introducing a new matrix.

With reference to the first aspect, in certain implementations of the first aspect, the method further includes: the AP receiving a first information matrix on the first subset of subcarriers, the first information matrix determined by the first training sequence and channel information and a frequency offset value between the STA and the AP; the AP receiving a second information matrix on the first subset of subcarriers, the second information matrix determined by the second training sequence and channel information and a frequency offset value between the STA and the AP; wherein the frequency offset value between the STA and the AP is determined according to the first information matrix and the second information matrix.

In the method for frequency offset estimation provided in the embodiment of the present application, the AP may determine a frequency offset value between the STA and the AP based on an information matrix received on the first subcarrier subset by the AP itself. Because the two information matrixes received by the AP on the first subcarrier subset are different due to the frequency offset value between the STA and the AP, the frequency offset value between the STA and the AP can be accurately determined based on the two received information matrixes, and the accuracy of determining the frequency offset estimation by the AP is improved.

With reference to the first aspect, in certain implementations of the first aspect, the PPDU further includes a channel estimation training sequence, and the first training sequence, the second training sequence, and the channel estimation training sequence are sequentially arranged in the PPDU, or alternately and crossly arranged.

In the method for frequency offset estimation provided by the embodiment of the present application, when a PPDU sent by an STA to an AP includes a first training sequence, a second training sequence, and a channel estimation training sequence, the first training sequence, the second training sequence, and the channel estimation training sequence are arranged in multiple ways in the PPDU, so that the flexibility of a PPDU structure can be improved.

With reference to the first aspect, in some implementations of the first aspect, the alternately cross-arranging the first training sequence, the second training sequence, and the channel estimation training sequence in the PPDU includes: the first training sequence is positioned behind the leader sequence and before the channel estimation training sequence, and the second training sequence is positioned behind the channel estimation training sequence and before the data symbol; or, the first training sequence is located after the preamble sequence and before the first channel estimation training sequence, and the second training sequence is located after the first channel estimation training sequence and before the second channel estimation training sequence, where the first channel estimation training sequence and the second channel estimation training sequence constitute a channel estimation training sequence.

With reference to the first aspect, in some implementations of the first aspect, the arranging the first training sequence, the second training sequence, and the channel estimation training sequence in the PPDU includes: the first training sequence is positioned behind the leader sequence and before the second training sequence, and the second training sequence is positioned before the channel estimation training sequence; or, the first training sequence is located after the channel estimation training sequence and before the second training sequence, and the second training sequence is located before the data symbols.

The method for frequency offset estimation provided by the embodiment of the application provides structures of various different PPDU frame formats, thereby improving the flexibility of the scheme.

With reference to the first aspect, in certain implementations of the first aspect, the PPDU further includes an automatic gain control training sequence for the AP to adjust a reception power at which the first and/or second training sequences are received on the first subset of subcarriers.

In the method for frequency offset estimation provided in the embodiment of the present application, a PPDU is sent by an STA to an AP, and an agc training sequence is newly added to the PPDU, and the AP may adjust, based on the agc training sequence, a reception power for receiving the first training sequence and/or the second training sequence on the first subcarrier subset, so that the reception power for receiving the first training sequence and/or the second training sequence by the AP is adjustable.

In a second aspect, a method for frequency offset estimation is provided, where the method for frequency offset estimation may be performed by an STA, or may be performed by a chip or a circuit disposed in the STA, and this is not limited in this application.

The method for frequency offset estimation comprises the following steps:

the STA receives first information from the AP, wherein the first information is used for indicating the number M of spatial streams corresponding to the STA needing to report a first training sequence and a second training sequence and a first subcarrier subset occupied by the STA reporting the first training sequence or the second training sequence; the first subcarrier subset is a subcarrier subset corresponding to the STA in S preset subcarrier subsets, and M and S are positive integers used for determining the first training sequence or the second training sequence;

the STA sends a physical layer protocol data unit (PPDU) to the AP on the first subset of subcarriers, where the PPDU includes the first training sequence and a second training sequence, and the first training sequence and the second training sequence are used to determine a frequency offset value between the STA and the AP.

According to the method for frequency offset estimation provided by the embodiment of the application, the STA determines how to generate and report the frequency offset estimation training sequence based on the received first information, so that the AP can determine the frequency offset value between the AP and the STA based on the received at least two frequency offset estimation training sequences, and the accuracy of determining the frequency offset estimation by the AP can be improved.

With reference to the second aspect, in certain implementations of the second aspect, the first information includes: first indication information for indicating the M and second indication information for determining the first subset of subcarriers.

The indication information indicating the number M of STAs and the indication information indicating the first subcarrier subset may be two different indication information, and different indication information sending modes are provided, thereby improving the flexibility of the scheme.

With reference to the second aspect, in some implementations of the second aspect, the receiving, by the STA, the first information from the AP includes: the STA receives a trigger frame from the AP, where the trigger frame is used to trigger the STA to report the PPDU, where the trigger frame carries the first indication information and the second indication information, and the first indication information is a scheduling information field.

With reference to the second aspect, in some implementations of the second aspect, the carrying of the first indication information in the trigger frame includes: the trigger frame includes a general information field, and the general information field includes the first indication information.

With reference to the second aspect, in some implementations of the second aspect, the first training sequence or the second training sequence is determined by a mapping relationship between the STA and a P matrix element.

With reference to the second aspect, in some implementations of the second aspect, the PPDU further includes a channel estimation training sequence, and the first training sequence, the second training sequence, and the channel estimation training sequence are sequentially arranged in the PPDU, or alternately and crossly arranged.

With reference to the second aspect, in some implementations of the second aspect, the alternately interleaving, in the PPDU, the first training sequence, the second training sequence and the channel estimation training sequence includes: the first training sequence is positioned behind the leader sequence and before the channel estimation training sequence, and the second training sequence is positioned behind the channel estimation training sequence and before the data symbol; or, the first training sequence is located after the preamble sequence and before the first channel estimation training sequence, and the second training sequence is located after the first channel estimation training sequence and before the second channel estimation training sequence, wherein the first channel estimation training sequence and the second channel estimation training sequence constitute the channel estimation training sequence.

With reference to the second aspect, in some implementations of the second aspect, the sequentially arranging the first training sequence, the second training sequence, and the channel estimation training sequence in the PPDU includes: the first training sequence is positioned behind the leader sequence and before the second training sequence, and the second training sequence is positioned before the channel estimation training sequence; or, the first training sequence is located after the channel estimation training sequence and before the second training sequence, and the second training sequence is located before the data symbols.

With reference to the second aspect, in some implementations of the second aspect, the PPDU further includes an automatic gain control training sequence for the AP to adjust a reception power at which the first and/or second training sequences are received on the first subset of subcarriers.

In the method for frequency offset estimation provided in the embodiment of the present application, a PPDU sent by an STA to an AP and an agc training sequence is added to the PPDU, and the AP may adjust the receiving power for receiving the first training sequence and/or the second training sequence on the first subcarrier subset based on the agc training sequence, so that the receiving power for receiving the first training sequence and/or the second training sequence by the AP is adjustable.

In a third aspect, an apparatus for frequency offset estimation is provided, where the apparatus is configured to perform the method provided in the first aspect. In particular, the apparatus may comprise means for performing the first aspect and any one of the possible implementations of the first aspect.

In a fourth aspect, an apparatus for frequency offset estimation is provided, the apparatus being configured to perform the method provided in the second aspect. In particular, the apparatus may comprise means for performing the second aspect and any possible implementation of the second aspect.

In a fifth aspect, an apparatus for frequency offset estimation is provided and includes a processor. The processor is coupled to the memory and is operable to execute instructions in the memory to implement the method of the first aspect as well as any one of the possible implementations of the first aspect. Optionally, the apparatus further comprises a memory. Optionally, the apparatus further comprises a communication interface, the processor being coupled to the communication interface.

In one implementation, the apparatus is an access point. When the device is an access point, the communication interface may be a transceiver, or an input/output interface.

In another implementation, the apparatus is a chip configured in an access point. When the apparatus is a chip configured in an access point, the communication interface may be an input/output interface.

In another implementation, the apparatus is a chip or a system of chips.

Alternatively, the transceiver may be a transmit-receive circuit. Alternatively, the input/output interface may be an input/output circuit.

In a sixth aspect, an apparatus for frequency offset estimation is provided that includes a processor. The processor is coupled to the memory and is operable to execute the instructions in the memory to implement the method of the second aspect and any possible implementation of the second aspect. Optionally, the apparatus further comprises a memory. Optionally, the apparatus further comprises a communication interface, the processor being coupled to the communication interface.

In one implementation, the apparatus is a station. When the device is a station, the communication interface may be a transceiver, or an input/output interface.

In another implementation, the apparatus is a chip configured in a site. When the apparatus is a chip configured in a station, the communication interface may be an input/output interface.

In another implementation, the apparatus is a chip or a system of chips.

In a seventh aspect, a computer-readable storage medium is provided, on which a computer program is stored, which, when executed by an apparatus, causes the apparatus to carry out the method of the first aspect and any one of the possible implementations of the first aspect.

In an eighth aspect, there is provided a computer readable storage medium having stored thereon a computer program which, when executed by an apparatus, causes the apparatus to carry out the method of the second aspect as well as any one of the possible implementations of the second aspect.

In a ninth aspect, there is provided a computer program product comprising instructions which, when executed by a computer, cause an apparatus to carry out the method of the first aspect as well as any one of the possible implementations of the first aspect.

A tenth aspect provides a computer program product comprising instructions which, when executed by a computer, cause an apparatus to carry out the method provided in the second aspect as well as any one of the possible implementations of the second aspect.

In an eleventh aspect, there is provided a communication system comprising an access point and a station as described above.

Drawings

Fig. 1 is a system diagram of a typical WLAN deployment scenario.

Fig. 2 (a) and (b) are schematic diagrams of uplink transmission between an AP and an STA in an MU-MIMO manner according to an embodiment of the present application.

Fig. 3 is a schematic diagram illustrating two STAs transmitting data to an AP according to an embodiment of the present application.

Fig. 4 is a schematic diagram of a single-antenna STA transmitting data according to an embodiment of the present application.

Fig. 5 is a schematic diagram of orthogonal sequences respectively corresponding to multiple STAs according to an embodiment of the present disclosure.

Fig. 6 is a schematic flow chart of a method for frequency offset estimation according to an embodiment of the present application.

Fig. 7 (a) and (b) are schematic diagrams illustrating a division of subcarrier subsets according to an embodiment of the present application.

Fig. 8 is a schematic diagram of a general information field of a trigger frame according to an embodiment of the present application.

Fig. 9 (a) and (b) are schematic diagrams of indirectly indicating a subcarrier subset according to an embodiment of the present application.

Fig. 10 is a diagram illustrating information related to determining a training sequence for frequency offset estimation according to an embodiment of the present application.

Fig. 11 is a schematic diagram of a frequency offset estimation training sequence according to an embodiment of the present application.

Fig. 12 (a) - (e) are schematic diagrams of frame formats of physical frames provided in the embodiment of the present application.

Fig. 13 is a scenario in which the method for frequency offset estimation provided in the embodiment of the present application is applied.

Fig. 14 is a diagram illustrating a physical frame transmitted by a plurality of STAs received by an AP.

Fig. 15 is a diagram of an apparatus 1500 for frequency offset estimation as proposed in the present application.

Fig. 16 is a schematic structural diagram of an STA 1600 suitable for use in embodiments of the present application.

Fig. 17 is a diagram of an apparatus 1700 for frequency offset estimation proposed by the present application.

Fig. 18 is a schematic structural diagram of an AP1800 suitable for the embodiment of the present application.

Detailed Description

The technical solution in the present application will be described below with reference to the accompanying drawings.

The embodiments of the present application may be applied to a Wireless Local Area Network (WLAN), and the WLAN may include one or more Basic Service Sets (BSS). The network nodes of the BSS include an AP and STAs. Each BSS may contain an AP and a plurality of STAs associated with the AP.

The AP is referred to as an access point, and may also be referred to as a wireless access point or a hotspot. The AP is an access point for a user terminal to enter a wired network, and is mainly deployed in a home, a building, and a campus. Typical AP coverage radii are tens to hundreds of meters. It should be understood that the AP may also be deployed outdoors. The AP acts as a bridge connecting the network and the wireless network, and mainly functions to connect clients of the respective wireless networks together and then to access the wireless networks to the ethernet. Currently, the standards mainly adopted by APs are the Institute of Electrical and Electronics Engineers (IEEE) 802.11 series, such as the 802.11ax or 802.11be standards. The AP may be a device supporting a WLAN system, for example, the AP may be a terminal device or a network device with a wireless fidelity (WiFi) chip.

The STA is referred to as a station, and in this application, the STA means a user terminal, so that it may be directly referred to as a user terminal or a user hereinafter. The STA may be a wireless communication terminal with a wireless communication chip, a wireless sensor, or a wireless communication. The STA may be a device supporting a WLAN system, for example, the STA may be a mobile phone supporting a WiFi communication function, a tablet computer supporting a WiFi communication function, a set-top box supporting a WiFi communication function, an intelligent television supporting a WiFi communication function, an intelligent wearable device supporting a WiFi communication function, and a computer supporting a WiFi communication function.

Fig. 1 is a system diagram of a typical WLAN deployment scenario, which includes an AP and 4 STAs, where the AP can communicate with STA #1, STA #2, STA #3, and STA #4, respectively. The uplink transmission mode between the AP and the STA includes, but is not limited to, an Orthogonal Frequency Division Multiple Access (OFDMA) mode, a multi-site channel multiple input multiple output (MU-MIMO) mode, or a hybrid transmission mode of OFDMA and MU-MIMO.

In the present application, the uplink transmission method between the AP and the STAs is taken as MU-MIMO, and the number N of AP antennas is greater than or equal to the sum M of the antennas of all STAs associated therewith. It should be understood that any STA may include multiple antennas, and when a STA has two antennas, the STA may be equivalent to two identical single-antenna STAs, except that the channels of the two equivalent STAs to the AP are different. As shown in fig. 2, fig. 2 is a schematic diagram of uplink transmission between an AP and an STA in an MU-MIMO manner according to an embodiment of the present application. In fig. 2, the AP includes N antennas (antenna #1 to antenna # N shown in fig. 2), and the total number of antennas of all STAs is M. H in FIG. 2 _NM Denotes a channel between an antenna M on the STA side and an antenna N on the AP side.

In this application, the spatial stream number M refers to a sum M of antenna numbers of the STAs, and the spatial stream number M corresponding to the STA may be understood as the sum M of the antenna numbers of at least one STA;

the embodiment of the application is suitable for a system of 2 spatial streams (ss) and a system of 4,8, 16ss, and along with the development of the technology, the technical scheme provided by the embodiment of the application can also be suitable for a system with more spatial streams.

Fig. 2 (a) shows that a STA may include multiple antennas, and if there is a frequency difference between the STA and the AP, the STA includes multiple antennas that transmit signals with the same frequency difference as that between the AP. Fig. 2 (b) is an equivalent transformation of fig. 2 (a), that is, an STA including multiple antennas may be equivalent to multiple identical single-antenna STAs, and it should be understood that this equivalent transformation is only for easier understanding of the technical solutions provided in the present application, and does not set any limit to the scope of the present application. In a case where an STA including multiple antennas is equivalent to multiple identical single-antenna STAs, the sum M of the number of antennas of the STA may be understood as the number M of STAs, that is, the number M of spatial streams corresponding to the STA in the embodiment of the present application may also be referred to as the number M of STAs in a case where a multi-antenna STA is equivalent to a single-antenna STA.

To facilitate understanding of the embodiments of the present application, the following description is made.

First, in the present application, "for indicating" may include for direct indication and for indirect indication. When a certain indication information is described for indicating a, the indication information may be included to directly indicate a or indirectly indicate a, and does not mean that a is necessarily carried in the indication information.

If the information indicated by the indication information is referred to as information to be indicated, in a specific implementation process, there are many ways of indicating the information to be indicated, for example, but not limited to, directly indicating the information to be indicated, such as the information to be indicated itself or an index of the information to be indicated. The information to be indicated can also be indirectly indicated by indicating other information, wherein an association relationship exists between the other information and the information to be indicated. It is also possible to indicate only a part of the information to be indicated, while the other part of the information to be indicated is known or predetermined. For example, the indication of the specific information may be implemented by means of a predetermined arrangement order of the respective information (e.g., protocol specification), thereby reducing the indication overhead to some extent. Meanwhile, the universal parts of all information can be identified and indicated in a unified mode, so that the indication overhead caused by independently indicating the same information is reduced.

Second, first, second, and various numerical numbers (e.g., "#1", "#2", etc.) shown in the present application are merely for convenience of description, and are not intended to limit the scope of the embodiments of the present application. E.g., to distinguish between different sequences, or to distinguish between different STAs, etc. Rather than to describe a particular order or sequence. It should be understood that the objects so described are interchangeable under appropriate circumstances so as to enable description of aspects other than those of the embodiments of the application.

Third, in the present application, "preset" may include a predefined definition, for example, a protocol definition. The "predefined" may be implemented by saving a corresponding code, table, or other means that can be used to indicate the relevant information in advance in the device (e.g., including the STA and the AP), and the present application is not limited to a specific implementation manner thereof.

Fourth, the term "store" referred to in the embodiments of the present application may refer to a store in one or more memories. The one or more memories may be provided separately or integrated in the encoder or decoder, the processor, or the communication device. The one or more memories may also be provided separately, with a portion of the one or more memories being integrated into the decoder, the processor, or the communication device. The type of memory may be any form of storage medium and is not intended to be limiting of the present application.

Fifth, the "protocol" in this embodiment may refer to a standard protocol in the communication field, and may include, for example, a WiFi protocol, a New Radio (NR) protocol, and a related protocol applied in a future communication system, which is not limited in this application.

Sixth, for ease of understanding, the following is a brief description of the main parameters involved in the present application:

h _ij : the channel between the antenna of STA # j and the AP-side antenna # i, j being a positive integer. (the present application takes a single-antenna STA as an example for explanation, and the case where the STA includes multiple antennas may be as shown in fig. 2STA acting as a single line).

The AP side antenna # k receives the information size on the ith symbol, where k and l are positive integers.

Δf _q : frequency offset between STA # q and AP.

: the training sequence transmitted on the W-th symbol in the first training sequence corresponding to STA # q is rotated in phase with respect to the training sequence transmitted on the first symbol.

P _fix : and P matrix corrected based on frequency offset values between the STA and the AP.

Specifically, uplink multi-site MIMO mainly depends on multi-antenna orthogonal balancing at the AP side, that is, the AP side obtains link information (e.g., channel State Information (CSI)) of an air interface by using a training sequence, and further balances effective loads of multiple sites, and splits superimposed information of multiple sites, so that the sites are orthogonal to each other and do not affect each other. Therefore, whether the wireless channel state information can be accurately obtained or not can directly influence the uplink multi-site orthogonality on one hand, or influence the key of each site for obtaining the accuracy of each stream on the other hand; on the other hand, the accuracy of precoding performed by the access point during downlink data transmission may also be affected. This process of obtaining wireless channel state information may also be referred to as channel estimation.

However, the types of the user terminals are various, and the radio frequency links of different user terminals may be different, so that carrier frequencies used by the user terminals when transmitting signals are difficult to be consistent, that is, it is difficult for different user terminals to perform frequency synchronization.

First, the influence of the asynchronism of the frequencies of signals transmitted by a plurality of user terminals on the estimation of the channel on the AP side will be briefly described with reference to fig. 3. Fig. 3 is a schematic diagram illustrating two STAs transmitting data to an AP according to an embodiment of the present application. Fig. 3 includes two STAs (STA #1 and STA #2 shown in fig. 3) and an AP, where STA #1 and STA #2 can access the network through the AP. For example, STA #1 and STA #2 may be two handsets supporting WiFi communication functions, the AP may be a router with a WiFi chip, and the AP is configured with two antennas (such as antenna #1 and antenna #2 shown in fig. 3).

As a possible implementation, there is no frequency difference between STA #1 and STA #2 and the AP, i.e. there is no Carrier Frequency Offset (CFO), and the two orthogonal symbols transmitted by STA #1 and STA #2 do not have phase rotation, and the CFO is simply referred to as frequency offset value hereinafter.

For example, STA #1 transmits data of

Then through a spatial channel h ₁₁ 、h ₂₁ Antenna #1 and antenna #2 on the AP side, respectively; STA #2 transmits data of

Then through a spatial channel h ₁₂ 、h ₂₂ And reaches the antenna #1 and the antenna #2 on the AP side, respectively. The information received by the AP side antenna #1 and the AP side antenna #2 is a superimposed signal of the two STAs after passing through an air interface channel, and specifically, the information received by the antenna #1 includes information including

And

wherein the content of the first and second substances,

the information received by antenna #2 includes

And

wherein the content of the first and second substances,

specifically, the STA sending data in the embodiment of the present application may be understood as a training sequence corresponding to a Long Training Field (LTF) sent by the STA on a certain subcarrier, and the data may be understood as a signal or information, where the LTF is included in a PPDU sent by the STA to an AP, taking 802.11ax as an example, the LTF may be a HE-LTF, and a specific frame format of the PPDU including the HE-LTF may be as follows:

ext> whereinext>,ext> Lext> -ext> STFext> representsext> nonext> -ext> Highext> throughputext> shortext> trainingext> fieldext> (ext> nonext> -ext> Highext> throughputext> shortext> trainingext> fieldext>)ext>,ext> Lext> -ext> LTFext> representsext> nonext> -ext> Highext> throughputext> longext> trainingext> fieldext> (ext> nonext> -ext> Highext> throughputext> longext> trainingext> fieldext>)ext>,ext> Lext> -ext> SIGext> representsext> nonext> -ext> Highext> throughputext> signalext> fieldext> (ext> nonext> -ext> Highext> throughputext> signalext> fieldext>)ext>,ext> RLext> -ext> SIGext> representsext> repetitionext> nonext> -ext> Highext> throughputext> signalext> fieldext> (ext> repetitionext> nonext> -ext> Highext> throughputext> signalext> fieldext>)ext>,ext> HEext> -ext> SIGext> -ext> Aext> representsext> Highext> efficiencyext> signalext> fieldext> Aext>,ext> HEext> -ext> SIGext> -ext> Bext> representsext> Highext> efficiencyext> signalext> fieldext> Bext>,ext> HEext> -ext> Fext> representsext> Highext> efficiencyext> shortext> trainingext> fieldext> (ext> Highext> -ext> efficiencyext> shortext> trainingext> fieldext>,ext> HEext> -ext> STFext>)ext>,ext> HEext> -ext> LTFext> representsext> Highext> efficiencyext> trainingext> fieldext> (ext> Highext> efficiencyext> shortext> trainingext> fieldext>,ext> HEext> -ext> STFext>)ext>,ext> andext> HEext> -ext> LTFext> representsext> Highext> efficiencyext> longext> trainingext> fieldext> (ext> Highext> efficiencyext> shortext> trainingext> fieldext>,ext> HEext> -ext> fieldext>)ext>,ext> andext> HEext> -ext> dataext> packetext> fieldext> (ext> PEext>)ext>.ext>

As another example, taking 802.11be as an example, the LTF may be an EHT-LTF, and one possible format of a PPDU frame containing the EHT-LTF may be as follows:

wherein L-STF denotes a non-High throughput short training field, L-LTF denotes a non-High throughput long training field, L-SIG denotes a non-High throughput signal field, RL-SIG denotes a repeated non-High throughput signal field, a universal signaling field (U-SIG) and an extreme High throughput signaling field (EHT-SIG) for carrying signaling for demodulating subsequent Data, an extreme High throughput short training sequence (EHT-STF) for automatic gain control of subsequent fields, an extreme High throughput long training sequence (EHT-LTF) for channel estimation, data field, PE denotes a packet extension field.

The AP side only needs to receive the information h ₁₁ 、h ₂₁ 、h ₁₂ And h ₂₂ And solving to obtain the CSI. The above process can be expressed in a matrix manner to be more easily understood, and the information matrix received at the AP is expressed as the following formula:

the training sequences transmitted by STA #1 and STA #2 are known to be X respectively at AP side ₁ ＝[1 -1]And X ₂ ＝[1 1]Based on the training sequence AP, the matrix in the above formula can be obtained

This matrix is referred to as the P matrix in the current protocol. Therefore, the AP side can obtain the channel matrix only by performing the following operations on the received information matrix:

as another possible implementation, STA #1 and STA #2 have respective frequency offsets with the AP, for example, the frequency offset of STA #1 relative to the AP is Δ f ₁ Frequency offset of STA #2 relative to AP is Deltaf ₂ . When STA1 and STA2 transmit data on two consecutive orthogonal symbols, the data will be phase-rotated, assuming that the period of each symbol is T, i.e. the data transmitted by STA #1 on the second symbol is phase-rotated with respect to the data transmitted by STA #1 on the first symbol

Similarly, data transmitted by STA #2 on the second symbol is transmitted on the first symbol with respect to STA #2The data transmitted on one symbol is phase-rotated

The data transmitted by STA #1 is

STA #2 transmits data of

The information matrix received at the AP is represented by the following equation:

for the AP side, the P matrix corresponding to the data sent by the two default STAs is also defined as

Because the AP side does not know that the STA has a frequency offset with respect to the AP, the AP obtains a channel matrix according to the original operation:

it can be found that the channel matrix determined by the AP has a channel of one STA doped with a channel of the other STA, and mutual crosstalk occurs, as can be seen from the above calculation process, because in the presence of frequency offset, the corresponding P is _fix The matrix is caused by non-orthogonality, that is, if the AP side can know the frequency offset information of the STA, the P matrix known by the AP side is compensated or corrected, so that the P matrix is not the above-mentioned P matrix

But instead takes into account P after the frequency offset information _fix Matrix array

The AP is then based on the matrix P _fix And the AP can obtain accurate channel information by inverting to obtain the channel information.

As described in detail above with reference to fig. 3, when there is a frequency offset between the STA and the AP, the AP cannot accurately obtain channel information between the STA and the AP based on the original P matrix, and to obtain accurate channel information, it is first necessary to obtain P _fix Matrix to obtain P _fix The key point of the matrix is to obtain the frequency offset value between the STA and the AP, and the P matrix can be obtained by correcting or compensating the P matrix based on the frequency offset value _fix And (4) a matrix.

Therefore, the embodiments of the present application mainly relate to how to know the frequency offset value between the STA and the AP.

Optionally, the same STA sends two same data on two symbols, so that when the AP side receives information corresponding to the two data, only the changes of the information corresponding to the two data in the two symbols need to be compared to obtain the frequency offset value of the STA and the AP.

For example, as shown in fig. 4, fig. 4 is a schematic diagram of a single-antenna STA according to an embodiment of the present application to transmit data. The data respectively sent by STA #1 on two symbols should be X ₁ ＝[1 1]Since the frequency offset between STA and AP is Δ f ₁ Data corresponding to STA #1 transmitted on two symbols respectively is

The information matrix corresponding to the data in two consecutive symbols received by AP antenna #1 is

The AP carries out point division on the received information matrix to solve the angle or conjugate to solve the angle, and then the angle 2 pi delta f of relative rotation of the two data can be obtained ₁ T, and further calculating to obtain a frequency deviation value delta f of the STA #1 and the AP ₁ 。

However, when multiple uplink STAs transmit data, the information matrix received by the AP is a superposition of data transmitted by multiple STAs, and therefore, even if each STA transmits duplicate data on two symbols, the information matrix received by the AP is a superposition of data of multiple STAs, so that the frequency offset value between each STA and the AP cannot be accurately estimated by the above-mentioned point division angle calculation method.

Alternatively, it can be considered that within the measured WiFi bandwidth, the channels within consecutive orthogonal blocks of subcarriers are nearly equal, i.e., the channels are relatively flat channels. Different orthogonal sequences are distributed to subcarriers sent by all STAs, so that the AP side can solve channel information of all the STAs, and further phase rotation angles among symbols are obtained.

For example, as shown in fig. 5, fig. 5 is a schematic diagram of orthogonal sequences respectively corresponding to multiple STAs according to an embodiment of the present application. For STA #1, the data transmitted by each subcarrier of the first symbol is

For STA #2, the data transmitted by each subcarrier of the first symbol is

Since the subcarriers transmitted by each STA are allocated with orthogonal sequences, the following:

taking antenna #1 as an example, the AP side may respectively represent the information received by each subcarrier of the first symbol as:

since the premise is that the channels within the contiguous orthogonal blocks of subcarriers are nearly equal, the channel estimation is based on the fact that the channels within the contiguous orthogonal blocks of subcarriers are nearly equal

By analogy with each orthogonal block, there are 234 effective subcarriers in 802.11ax to ensure that the consecutive subcarriers are flat. The received signals are orthogonalized under the premise that the above-mentioned precondition is satisfied, and taking the signal of the orthogonal STA #2 as an example, the signals received by the AP side antenna #1 at each subcarrier of the first symbol are orthogonally summed

Due to the fact that

Therefore, it is not only easy to use

The signal of STA #2 may be canceled out, leaving only the information of STA #1, namely:

similarly, for the second symbol, the AP side may perform the same processing as described above to obtain:

association

And

can calculate to obtain 2 pi delta f ₁ T。

However, it is a relatively harsh condition that the channels in the subcarrier orthogonal blocks whose preconditions are continuous are almost equal, which is difficult to satisfy in reality, and thus the accuracy of channel estimation performed by the AP is difficult to ensure.

In order to solve the above-mentioned drawbacks of channel estimation, the present application provides a method for frequency offset estimation. The accuracy of frequency offset estimation is improved by sending two repeated frequency offset estimation training sequences to the AP.

It should be understood that the methods provided by the embodiments of the present application may be applied to a WLAN communication system, such as the communication system 100 shown in fig. 1. The communication system may include at least one AP and a plurality of STAs. Frequency offset between the plurality of STAs and the AP is inconsistent.

In the embodiment of the present application, a single-antenna STA is taken as an example for description, that is, one AP associates with multiple single-antenna STAs. When a certain STA includes multiple antennas, frequency offset between each antenna in the STA and an antenna of the AP is the same, so the calculation method of channel information between other antennas on the STA and the antennas of the AP may refer to the calculation method of channel information between the certain antenna in the STA and the antennas of the AP in the embodiment of the present application, and details of this application are not repeated for the case where the certain STA includes multiple antennas.

It should also be understood that the method for frequency offset estimation provided in the embodiment of the present application may also be applied in a scenario with multiple APs, for example, the system in the WLAN deployment scenario shown in fig. 1 further includes another AP, the communication between the another AP and the STA is the same as the communication between the AP and the STA shown in fig. 1, and the frequency offset estimation between the another AP and the STA may refer to the frequency offset estimation between the AP and the STA shown in fig. 1, which is not described again in this application.

In addition, data transmission between the STA and the AP may occur over a full bandwidth (for example, 20 megabases, including 256 subcarriers), in this embodiment, frequency offset estimation between the STA and the AP on one subcarrier is taken as an example for description, and frequency offset estimation between the STA and the AP on other subcarriers is the same, which is not described herein again.

The embodiments shown below do not particularly limit the specific structure of the execution subject of the method provided by the embodiments of the present application, as long as the communication can be performed according to the method provided by the embodiments of the present application by running the program recorded with the code of the method provided by the embodiments of the present application, for example, the execution subject of the method provided by the embodiments of the present application may be an AP or an STA, or a functional module capable of calling a program and executing the program in the AP or the STA.

Hereinafter, the method for frequency offset estimation provided by the embodiments of the present application is described in detail by taking the interaction between the AP and the STA as an example without loss of generality.

Fig. 6 is a schematic flow chart of a method for frequency offset estimation according to an embodiment of the present application. The execution body includes an AP and an STA.

For convenience of understanding, only one STA is shown in fig. 6, in an embodiment of the present application, there are multiple STAs associated with the AP shown in fig. 6, and all STAs are not shown in fig. 6, because steps executed by the multiple STAs associated with the AP are the same, and steps executed by other STAs not shown may refer to the STAs shown in fig. 6, which is not described again in detail below.

The method for frequency offset estimation includes some or all of the following steps.

S610, the AP sends the first information to the STA.

The first information is used to indicate the number M of spatial streams corresponding to the STA that needs to report the first training sequence and the second training sequence, and the first subcarrier subset occupied by the first training sequence or the second training sequence reported by the STA that receives the first information. The first training sequence and the second training sequence are used for estimating a frequency offset value between the AP and the STA, and the first subcarrier subset is a subcarrier subset corresponding to the STA in S preset subcarrier subsets.

The above spatial stream number M corresponding to the STA refers to a sum M of the number of antennas included in at least one STA that needs to report the first training sequence and the second training sequence, and the embodiment shown in fig. 6 is described by taking a single-antenna STA as an example (as shown in fig. 2 (b), a multi-antenna STA may be equivalent to a single-antenna STA).

It should be understood that the first training sequence and the second training sequence referred to in this embodiment are identical training sequences, except that positions occupied in a physical layer protocol data unit (PPDU) transmitted by the STA to the AP are different, and information included in the first training sequence and the second training sequence is the same, so how the STA generates the first training sequence may be described below from the perspective of the first training sequence. M and S are positive integers, and M and S are used to determine the first training sequence, and how to determine the first training sequence based on M and S will be described below, and will not be described here.

The first training sequence may also be referred to as a frequency offset estimation training sequence, a Long Training Field (LTF), an extra high throughput LTF (EHT-LTF), a frequency offset training sequence, or the like.

It should be noted that, for convenience of describing the method for frequency offset estimation provided by the embodiment of the present application from the perspective of one STA in the embodiment shown in fig. 6, the STA is any one of multiple STAs associated with an AP.

Exemplarily, the first information may be used to instruct a plurality of STAs associated with the AP to report a subcarrier subset occupied by the first training sequence or the second training sequence; alternatively, the first and second electrodes may be,

for example, the AP may send a plurality of information to a plurality of STAs associated with the AP, where the plurality of information respectively indicates the number of STAs that need to report the first training sequence and the second training sequence and a subcarrier subset occupied by the first training sequence or the second training sequence reported by the STA that receives the information.

In another implementation, the first information may indicate the number of symbols required for the STA to report the first training sequence, where the number of symbols may be used to determine a dimension of a P matrix, and the P matrix is used to determine the first training sequence.

As another possible implementation manner, the number of symbols required for the STA to report the first training sequence may also be determined in a protocol predefined manner.

It should be noted that, in the embodiment of the present application, the number J of symbols, the total number S of subcarrier subsets, and the total number M of STAs that need to report a frequency offset estimation training sequence may be obtained by mutual derivation, that is, two of the J, S and the M parameters are known to determine another parameter. The specific determination process may be table lookup or calculation, and the application is not limited.

That is, when the protocol is predefined or the AP indicates the number of symbols required by the STA to report the first training sequence, the number S of subcarrier subsets may not be predefined by the protocol. In the embodiment of the present application, the number S of subcarrier subsets is obtained as an example, and when the number J of symbols required for reporting the first training sequence is obtained, the number is similar to the number S of subcarrier subsets, except that J is derived from S, and J can be obtained without deriving J by directly indicating J, which is not described in detail herein.

In this embodiment of the present application, the dividing manner of the subcarrier subsets may be predefined by a protocol, may also be negotiated between an STA and an AP, may also be notified to each STA by a signaling after the AP determines, or may also be reported to the AP by a signaling after the STA negotiates and determines, and it should be understood that in this embodiment of the present application, there is no limitation on how to divide all subcarriers to obtain at least one subcarrier subset.

For example, the protocol predefines that all subcarriers (K) are divided into S subcarrier subsets, there is no intersection between the S subcarrier subsets, and subcarriers occupied by each subcarrier subset may be consecutive or non-consecutive, where K is a positive integer and S is a positive integer.

For example, if the subcarriers in the subcarrier subsets are consecutive, the subcarriers included in the above S subcarrier subsets may be:

subcarrier subset #1 includes

subcarriers

1,2,3, …, K/S, subcarrier subset #2 includes subcarriers { K/S +1,K/S +2,K/S +3, …,2K/S }, …, subcarrier subset # S includes subcarriers { K-K/S +1,K-K/S +2,K-K/S +3, …, K }. As shown in fig. 7 (a), fig. 7 is a schematic diagram of dividing a subcarrier subset according to an embodiment of the present disclosure.

For example, if the subcarriers in the subcarrier subsets are non-consecutive, the subcarriers included in the above S subcarrier subsets may be:

subcarrier subset #1 includes subcarriers 1,K/S +1,2K/S +1, …, K-K/S +1, subcarrier subset #2 includes subcarriers 2,K/S +2,2K/S +2, …, K-K/S +2}, …, subcarrier subset # S includes subcarriers { K/S,2K/S +3, …, K }. As shown in fig. 7 (b).

It should be noted that all the subcarriers referred to in this application refer to all the subcarriers currently scheduled, and the number of the subcarriers scheduled at each time may be different.

For example, all subcarriers currently scheduled include K subcarriers, and all subcarriers next scheduled are 2K subcarriers. In the embodiment of the present application, the frequency offset value between the STA and the AP in a certain scheduling procedure is mainly estimated, and for the case that the frequency offset value needs to be estimated in other scheduling procedures, reference may be made to the scheme for estimating the frequency offset value provided in the embodiment of the present application, and details of the frequency offset estimation scheme in different scheduling procedures are not repeated in the embodiment of the present application.

As a possible implementation manner, the first information includes first indication information and second indication information, where the first indication information is used to indicate the number M of STAs needing to report the first training sequence and the second training sequence, and the second indication information is used to indicate the first subcarrier subset.

Optionally, the first indication information and the second indication information may be sent to the STA at the same time, or the first indication information and the second indication information may be sent to the STA sequentially.

As a possible implementation manner, the first information is a Trigger Frame (TF) specified in an existing protocol or a next generation standard protocol, and the trigger frame is used for triggering the STA to report the PPDU. In the embodiment of the present application, a frame format of a trigger frame defined in a protocol 802.11ax is described as an example. Q bits may be added to a common information field (common information field) of the trigger frame, where the Q bits are used to indicate the number M of STAs that need to report the first training sequence and the second training sequence, and Q is a positive integer. In this example, the format of the general information field in the trigger frame is shown in fig. 8, and fig. 8 is a schematic diagram of the general information field of the trigger frame provided in the embodiment of the present application.

As can be seen from fig. 8, the fields included in the trigger frame are:

trigger type (trigger type), uplink length (UL length), more trigger frames (more TF), carrier sense required (CS required), uplink bandwidth (UL BW), guard interval and long training field type (GI and LTF type), MU-MIMO long training field type (MU-MIMO LTF mode), number of high efficiency long training symbols and number of middle training sequence cycles (number of HE-LTF symbols and mid-amplitude), uplink space-time block code (uplink space block code, UL STBC), low density parity check code extra symbol segment (low density parity check code extra symbol segment), access point transmit power (AP TX power), uplink packet extension (UL packet extension), uplink spatial multiplexing (UL spatial streams), doppler (Doppler), uplink high-efficiency model field A2 partial reserved field (UL HE-SIG-A2 reserved), reserved field (reserved), trigger type dependent common information (trigger dependent common information).

The specific meaning of each field of the trigger frame related in the embodiment of the present application may refer to the specification in the existing protocol and the next-generation standard protocol, for example, the specification in the 802.11ax or 802.11be standard, and is not described in detail in the present application. The difference between the general information field in the trigger frame related to the embodiment of the present application and the general information field of the trigger frame specified in the existing protocol and the next generation standard protocol is that first indication information is added between the reserved bit field of the general information field and the general information field related to the trigger type, and the first indication information may occupy at least one bit.

For example, if the number of STAs which need to report the first training sequence and the second training sequence is 10, the first indication information occupies 4 bits.

As another possible implementation manner, the first information is a trigger frame specified in an existing protocol or a next generation standard protocol, and the first indication information may be a field newly added in the trigger frame, instead of being limited to a field newly added in a general information field in the trigger frame.

As another possible implementation manner, the first information is a trigger frame specified in an existing protocol or a next-generation standard protocol, and the first indication information may multiplex a reserved field (e.g., a reserved field shown in fig. 8) in the trigger frame, so that in this implementation manner, signaling overhead may be saved.

As another possible implementation manner, the first information is a trigger frame specified in an existing protocol or a next-generation standard protocol, and the first indication information may partially multiplex a reserved field in the trigger frame, and partially serve as a newly added field in the trigger frame (for example, in a case that the reserved field is not sufficient).

It should be understood that the above-mentioned first indication information is carried in the trigger frame by way of example only, and does not limit the scope of the present application in any way. For example, the first indication information may be carried in a newly added signaling between the AP and the STA, and sent to the STA; alternatively, the first indication information may be carried in other existing signaling between the AP and the STA, and sent to the STA.

The embodiment of the present application may also be applied to uplink transmission, that is, the first information may be a PPDU sent by the STA to the AP, and the first indication information and the second indication information may be carried in a signaling (Signal) field of the PPDU sent by the STA to the AP, for example, carried in an HE-SIG field or an EHT-SIG field in the PPDU.

Further, in the case that the first information is a trigger frame specified in an existing protocol or a next generation standard protocol, the scheduling information field included in the trigger frame may be used to indicate the first subset of subcarriers, that is, the second indication information mentioned above may multiplex the scheduling information field in the trigger frame to implement the function of indicating the first subset of subcarriers, and how to multiplex the scheduling information field to indicate the first subset of subcarriers is described in detail below with reference to fig. 9.

Fig. 9 is a schematic diagram of indirectly indicating a subcarrier subset according to an embodiment of the present application. Fig. 9 (a) includes:

medium access control header (MAC header) information, STA scheduling information ordering, padding (padding), and Frame Check Sequence (FCS). The MAC header information includes frame control (frame control), duration (duration), receiver Address (RA), transmitter Address (TA), and common information (common information); the STA scheduling information sequence includes scheduling information (user information) of at least one user, the scheduling information of the at least one user is arranged in a certain sequence in the STA scheduling information field, so that each STA can be sequentially corresponding to each subcarrier subset according to the sequence of the scheduling information corresponding to the multiple STAs in the trigger frame, after all subcarrier subsets are arranged completely, the remaining STAs are arranged from the first subcarrier subset again, and the final emission effect is as shown in fig. 9 (b), and the arrangement process may be represented as:

assuming that M STAs (STA #1 to STA # M shown in fig. 9 (b)) need to transmit a frequency offset estimation training sequence to the AP, all subcarriers in this scheduling are divided into S subcarrier subsets. The ith STA needs to send the frequency offset estimation training sequence on mod (i-1,S) +1 subcarrier subset, where mod represents the modulo operation. As can be seen from FIG. 9 (b), the first mod (i-1,S) +1 subcarrier subsets all carry

An STA, in order to be able to

The STA is distinguished, and the frequency offset estimation training sequence is transmitted by the STA and needs to be multiplied

The P matrix of dimension, corresponding to a frequency offset estimation training sequence requirement

One symbol, with the remaining sub-carrier subsets carrying

An STA, in order to be able to

The STA is distinguished from other STAs, and the STA needs to multiply when sending the frequency offset estimation training sequence

A symbol.

It should be noted that the multiplexing scheduling information field shown in fig. 9 indicates the first subcarrier subset by way of example only, and the scope of the present application is not limited in any way.

As a possible implementation manner, the second indication information is a newly added field in the trigger frame, and is used to indicate the first subcarrier subset, or the second indication information multiplexes the remaining field in the trigger frame and indicates the first subcarrier subset.

It should be understood that the second indication information is carried in the trigger frame by way of example only, and does not limit the scope of the present application in any way. For example, the second indication information may be carried in a newly added signaling between the AP and the STA, and sent to the STA; alternatively, the second indication information may be carried in other existing signaling between the AP and the STA, and sent to the STA.

Further, after the STA receives the first information, a first training sequence may be generated based on the first information. That is, the method flow shown in fig. 6 further includes S620, where the STA generates the first training sequence.

First, the STA determines that M STAs currently scheduled need to send a first training sequence and a second training sequence to the AP based on first indication information (e.g., a newly added field in a trigger frame general information field).

Then, the STA determines a first subcarrier subset (e.g., subcarrier subset # j) corresponding to the STA based on the second indication information (e.g., the STA is located at the STA # i in the scheduling information field), and may further determine the number of symbols required for transmitting the first training sequence and the number of STAs (M) carried on the first subcarrier subset _j ) And determining that the STA is the second STA (R) carried on the first subset of subcarriers _i )。

Wherein the number M of STAs carried on the first subcarrier subset _j For determining the dimension of a P matrix of M _j The first training sequence may be generated by multiplying the STA by the P-th row of the matrix, which is determined by the order of the STA among all STAs carried by the first subset of subcarriers.

Taking the first information as a trigger frame and the scheduling information in the second indication information multiplexing trigger frame as an example to explain the process of generating the first training sequence by the STA:

the method comprises the following steps:

the STA determines relevant information required for generating the first training sequence based on the predefined number S of subcarrier subsets, the number M of STAs indicated by the first indication information carried in the trigger frame, and the rank i of the STA in the scheduling information field of the trigger frame, as shown in fig. 10, fig. 10 is a schematic diagram of determining relevant information of the first training sequence provided in the embodiment of the present application, and as can be seen from fig. 10, the relevant information includes the following information:

1. send the firstNumber of symbols required for training sequence

2. The sequence number j = mod (i-1,S) +1 of the first subcarrier subset occupied by the STA;

3. the number of all STAs borne by the first subcarrier subset occupied by the STA

4. The serial number of the STA in all STAs carried by the occupied first subcarrier subset

It should be noted that, in fig. 10, the number M of the STAs indicated by the first indication information is taken as an example to illustrate that the STA generates the first training sequence, and when the first indication information indicates that the STA reports the number J of symbols required by the first training sequence, the STA may determine, based on the number J of symbols and the sequence i in the scheduling information field of the STA in the trigger frame, the relevant information required for generating the first training sequence:

1. number of symbols required for transmitting the first training sequence

2. The sequence number j = mod (i-1,S) +1 of the first subset of subcarriers occupied by the STA;

Wherein M can be determined by J and S;

Step two:

based on the related information obtained in the step one, the STA generates a first training sequence to be sent to the AP. Fig. 11 shows a first training sequence transmitted by an STA on subcarrier subset # j, where fig. 11 is a schematic diagram of the first training sequence provided in this embodiment of the present application. As can be seen from FIG. 11, multiplying M by the preset data _j Rth of dimension P matrix _i In particular, when

Then, the last symbol of the first training sequence is a copy of the first symbol of the first training sequence or the last symbol of the first training sequence is a copy of other symbols of the first training sequence.

Further, after the STA generates the first training sequence, in a possible implementation manner, the preamble sequence, the channel estimation training sequence, and the data symbol portion may be generated according to the specification in the existing protocol or the next generation standard protocol, and how to generate the preamble sequence, the channel estimation training sequence, and the data symbol portion is not limited in the application. The generation may be done in accordance with generation methods in existing protocols or next generation standard protocols, or may also be done based on generation methods specified in future protocols.

After the frequency offset estimation training sequence, the preamble sequence, the channel estimation training sequence, and the data symbol part are generated, the STA may obtain the PPDU to be sent to the AP. That is, the method flow shown in fig. 6 further includes S630, where the STA transmits a PPDU to the AP.

In this embodiment of the present application, the PPDU needs to include at least two training sequences (e.g., a first training sequence and a second training sequence), or may include more than two training sequences (e.g., in addition to the first training sequence and the second training sequence, a third training sequence, a fourth training sequence, and the like, where the first training sequence, the second training sequence, the third training sequence, and the fourth training sequence are the same training sequence), which is described below by taking two training sequences included in the PPDU as an example, and when the PPDU includes more than two training sequences, the PPDU is similar to the PPDU including two training sequences, which is not described in this application again.

It should be noted that, the physical layer protocol data unit (PPDU) may be understood as an uplink transport block PPDU (UL TB PPDU) reported by an STA to an AP and defined in a protocol, and may also be referred to as a physical frame for short.

As shown in fig. 12, fig. 12 is a schematic diagram of a format of a PPDU provided in the embodiment of the present application.

In one possible implementation, the first training sequence, the second training sequence, and the channel estimation training sequence are alternately arranged in a PPDU in a cross:

for example, the first training sequence is located after the preamble sequence and before the channel estimation training sequence, and the second training sequence is located after the channel estimation training sequence and before the data symbol.

Illustratively, as can be seen from (a) in fig. 12, the frequency offset estimation training sequence described above includes two (e.g., the first training sequence and the second training sequence shown in (a) in fig. 12), and the two frequency offset estimation training sequences may be respectively placed before and after the channel estimation training sequence;

for example, the first training sequence is located after the preamble sequence and before the first channel estimation training sequence, and the second training sequence is located after the first channel estimation training sequence and before the second channel estimation training sequence, wherein the first channel estimation training sequence and the second channel estimation training sequence constitute the channel estimation training sequence.

Illustratively, as can be seen from (b) in fig. 12, the frequency offset estimation training sequence described above includes two (e.g., the first training sequence and the second training sequence shown in (a) in fig. 12), and the two frequency offset estimation training sequences may be respectively placed before and after the partial channel estimation training sequence.

In another possible implementation manner, the first training sequence, the second training sequence, and the channel estimation training sequence are sequentially arranged in the PPDU:

for example, the first training sequence is located after the preamble sequence and before the second training sequence, and the second training sequence is located before the channel estimation training sequence.

Illustratively, as can be seen from (c) in fig. 12, the frequency offset estimation training sequence described above includes two (e.g., the first training sequence and the second training sequence shown in (a) in fig. 12), and the two frequency offset estimation training sequences may be placed in front of the channel estimation training sequence;

also for example, the first training sequence is located after the channel estimation training sequence and before the second training sequence, and the second training sequence is located before the data symbols.

Illustratively, as can be seen from (d) in fig. 12, the frequency offset estimation training sequences described above include two (e.g., the first training sequence and the second training sequence shown in (a) in fig. 12), and the two frequency offset estimation training sequences may be respectively placed after the channel estimation training sequence.

It should be understood that the formats of the PPDUs shown in (a) - (d) in fig. 12 are only examples and do not limit the scope of the present application at all, the arrangement manner of the first training sequence and the second training sequence in the PPDU may also be other forms, and the PPDU may further include more than two frequency offset estimation training sequences, which is not described herein again. In the case where the format of the PPDU is as shown in fig. 12 (a), interference of transmission is minimized.

In addition, the preamble sequence in the PPDU may further include third indication information, where the third indication information is used to indicate a total number M of STAs carried on the frequency offset estimation training sequence _j 。

Further, after receiving the PPDU, the AP may implement frequency offset estimation based on two frequency offset estimation training sequences in the PPDU, that is, the method flow shown in fig. 6 further includes S640, and the AP performs frequency offset estimation.

Taking a certain subcarrier in the subcarrier subset j as an example, if the frequency offset value between the STA and the AP is not considered, the information matrix corresponding to the first or second frequency offset estimation training sequence received by each antenna of the AP may be represented as:

further, the frequency offset value between the STA and the AP is considered. Suppose, M _j The frequency offset values between the STA and the AP are respectively delta f ₁ 、Δf ₂ 、…、Δf _Mj ，M _j Due to frequency offset, a frequency offset estimation training sequence sent by each STA in the STAs accumulates phase rotation relative to a frequency offset estimation training sequence sent on a first symbol due to frequency offset, so that a phase rotation angle of the frequency offset estimation training sequence sent on a certain symbol Q relative to the frequency offset estimation training sequence sent on the first symbol is j2 pi Δ f (Q-1) T, and a first information matrix corresponding to the first frequency offset estimation training sequence received by each antenna of the AP in the presence of frequency offset may be represented as:

the second information matrix corresponding to the second frequency offset estimation training sequence received by the AP in PPDU format shown in fig. 12 (a) can be expressed as:

wherein, D is the symbol number of the channel estimation training sequence. Pseudo-inverse left-multiplying a first information matrix (i.e., equation (1-2)) corresponding to the received first frequency offset estimation training sequence by a second information matrix (i.e., equation (1-3)) corresponding to the second frequency offset estimation training sequence to obtain:

it can be seen from equations 1-4 that after the first information matrix corresponding to the first frequency offset estimation training sequence is inverted, the result obtained by left-multiplying the first information matrix corresponding to the second frequency offset estimation training sequence has standard eigenvalue decomposition properties, and the eigenvalue is obtained by using eigenvalue decomposition solution:

calculating M based on the characteristic value _j Frequency deviation value delta f between each STA and AP ₁ 、Δf ₂ 、…、

The solution procedure in the case of the PPDU format shown in fig. 12 (b) -12 (d) is similar to the solution procedure of the frequency offset value in the case of the PPDU format shown in fig. 12 (a), and is not described again here.

It should be noted that, in this embodiment, a content corresponding to the frequency offset estimation training sequence received by the AP is referred to as an information matrix only by way of example, and the scope of protection of this application is not limited at all, and for example, the content may also be referred to as a signal matrix, frequency offset estimation training sequence information, and the like.

Further, in the embodiment of the present application, the PPDU may further include an automatic gain control training sequence. The agc midamble may be generally referred to as a Short Training Field (STF), for example, in the 802.11ax protocol, a field similar to HE-STF is added in addition to the L-STF and HE-STF specified in the current protocol, and the added field may be referred to as an agc midamble; also for example, in the 802.11be protocol or the WiFi protocol in the future, in addition to the extra high throughput-STF (EHT-STF) specified in the current protocol, a field similar to the EHT-STF is added, and the added field may be referred to as an automatic gain control training sequence. In the embodiment of the present application, the agc midamble is used to control the receiver amplifier stage control of the AP when receiving the frequency offset estimation midamble (e.g., controlling the AP to receive the first midamble and/or the second midamble), as shown in fig. 12 (e).

It should be noted that the reason for adding the agc midamble is that the subcarriers occupied by the STA in transmitting the frequency offset estimation midamble are different from those occupied by other parts (e.g., preamble sequence, channel estimation midamble, and data symbols), and due to the frequency selectivity of the channel, the total received signal strength of the AP may change relative to other parts.

For example, the target signal strength of the uplink message after being amplified and adjusted by the AP is X. For other parts except the frequency offset estimation training sequence, the AP estimates that the signal intensity is Y based on the existing automatic gain control training sequence, and the amplifier gear of the AP needs to be adjusted to X/Y when receiving the part; and for the frequency offset estimation training sequence, the AP estimates that the signal intensity of the part is Z based on the newly added automatic gain control training sequence, and the amplifier gear of the AP needs to be adjusted to X/Z when receiving the frequency offset estimation training sequence part.

In order to facilitate understanding of the method for frequency offset estimation provided in the embodiments of the present application, a specific example is described below.

It is assumed that the method for frequency offset estimation provided in the embodiment of the present application is applied to the scenario shown in fig. 13, one AP associates 3 STAs (STA #1, STA #2, and STA #3 shown in fig. 13), and each STA is an STA with a single antenna.

The frequency offsets of the 3 STAs relative to the AP are respectively delta f ₁ 、Δf ₂ 、Δf ₃ . The whole frequency band of the scheduling is divided into 2 subcarrier subsets. In the scenario shown in fig. 13, the method for frequency offset estimation provided by the embodiment of the present application includes the following steps:

the method comprises the following steps:

the AP sends a trigger frame to notify all STAs to prepare to send a PPDU, where the trigger frame includes first indication information and scheduling information, and the first indication information indicates that 3 STAs in the scene shown in fig. 13 send frequency offset estimation training sequences, and the sequence of the scheduling information fields of the STAs in the trigger frame is STA #1, STA #2, and STA #3.

Step two:

and after the STA #1 receives the trigger frame, establishing a frequency offset estimation training sequence. STA #1 knows that one of the two frequency offset estimation training sequences contains

A symbol; and knows that STA #1 needs to occupy subcarrier subset #1, and there are 2 STAs (STA #1 and STA # 3) on this subcarrier subset #1, and STA #1 is the first STA on this subcarrier subset # 1. Therefore, the first frequency offset estimation training sequences transmitted by STA #1 on two symbols are the preset data multiplied by the two-dimensional P matrix

Two values of the first row in, i.e. multiplication by [1, -1]. That is, the first symbol in the first frequency offset estimation training sequence is transmitted as the default data multiplied by 1, and the second symbol is transmitted as the default data multiplied by-1. Fig. 14 shows a physical frame transmitted by the first STA #1, and fig. 14 is a diagram of a PPDU transmitted by a plurality of STAs received by an AP.

And after receiving the trigger frame, the STA #3 constructs a frequency offset estimation training sequence. The STA #3 acquires that one of the two frequency offset estimation training sequences contains 2 symbols; and knows that STA #3 needs to occupy subcarrier subset #1, and there are 2 STAs (STA #1 and STA # 3) on this subcarrier subset #1, and STA #3 is the second STA on this subcarrier subset # 1. Therefore, the first frequency offset estimation training sequences transmitted by STA #3 on two symbols are the preset data multiplied by the two-dimensional P matrix

Two values in the second row, i.e., multiply by [1,1]. That is, the first symbol in the first frequency offset estimation training sequence is transmitted with the preset data multiplied by 1, and the second symbol is transmitted with the preset data multiplied by 1. PPDU transmitted by the second behavior STA #3 as shown in fig. 14;

and after the STA #2 receives the trigger frame, establishing a frequency offset estimation training sequence. The STA #2 learns that one of the two frequency offset estimation training sequences contains 2 symbols; and knows that STA #2 needs to occupy subcarrier subset #2, and there are 1 STA (STA # 2) on this subcarrier subset #2, STA #2 is the first STA on this subcarrier subset #2. Therefore, the first frequency offset estimation training sequences transmitted by STA #2 on two symbols are the preset data multiplied by the value of the first row in the one-dimensional P matrix [1], i.e., multiplied by [1,1]. That is, the first symbol in the first frequency offset estimation training sequence is sent with the preset data multiplied by 1, and the second symbol is sent with the preset data multiplied by 1. The third action is a PPDU transmitted by STA #3 as shown in fig. 14.

Step three:

STA #1, STA #2, and STA #3 transmit two repeated frequency offset estimation training sequences, which are respectively constructed, to the AP.

Step four:

on the sub-carrier subset #1, the information matrix received by the antenna #1 of the AP is the data experience channel h of the STA #1 ₁₁ Data with STA #3 experiences channel h ₁₃ The sum of the two data portions and the information received by the antenna #2 of the AP is that the data of the STA #1 goes through the channel h ₂₁ Data with STA #3 experiences channel h ₂₃ The sum of the two data portions and the information received by the antenna #3 of the AP is that the data of the STA #1 goes through the channel h ₃₁ Data with STA #3 experiences channel h ₃₃ The sum of the two portions of data.

For the training sequence of frequency offset estimation transmitted on each symbol, the transmission itself on the second symbol of STA #1 should be-1 due to different frequency offsets of STAs relative to AP, but becomes phase-rotated

The following symbols are analogized in turn. Similarly, the transmission on the second symbol of STA #3 should be 1, but due to the phase rotation, it becomes a change

The following symbols are analogized in turn.

Then the first information matrix corresponding to the first frequency offset estimation training sequence received by the AP on subcarrier subset 1 is:

a second information matrix corresponding to a second frequency offset estimation training sequence received by the AP on the subcarrier subset 1 is:

the AP uses the received first information matrix corresponding to the first frequency offset estimation training sequence to perform pseudo-inverse left multiplication on the second information matrix corresponding to the second frequency offset estimation training sequence, and then the corresponding characteristic value standard form can be obtained:

the eigenvalue is obtained by using the eigenvalue decomposition theorem

By finding the angle of its characteristic value and then dividing by the corresponding coefficient, Δ f can be obtained ₁ And Δ f ₃ 。

On the subcarrier subset #2, the AP antenna #1 receives information that the data of STA #2 experiences channel h ₁₂ Data of (2), information received by the antenna #2 of the AP is that the data of the STA #2 goes through the channel h ₂₂ The data of (1). Considering the frequency offset between STA #2 and AP, the first information matrix corresponding to the first frequency offset estimation training sequence received by AP on subcarrier subset #2 is:

the second information matrix corresponding to the second frequency offset estimation training sequence received by the AP on subcarrier subset 2 is:

and the AP uses the coefficient quotient of the same position in the second information matrix corresponding to the received second frequency offset estimation training sequence and the first information matrix corresponding to the first frequency offset estimation training sequence to obtain:

can obtain

By taking the complex angle and dividing by the corresponding coefficient, Δ f can be obtained ₂ 。

In addition, Δ f can also be obtained by solving in a manner that a first information matrix corresponding to a first frequency offset estimation training sequence is subjected to pseudo-inverse pre-multiplication on a second information matrix corresponding to a second frequency offset estimation training sequence ₂ The calculation method is as follows:

during calculation, a second column of a first information matrix corresponding to the received first frequency offset estimation training sequence and a second column of a second information matrix corresponding to the second frequency offset estimation training sequence need to be ignored; namely, the first column of the first information matrix corresponding to the first frequency offset estimation training sequence is used for performing pseudo-inverse left multiplication on the first column of the second information matrix corresponding to the second frequency offset estimation training sequence, so as to obtain:

can obtain

It should be understood that the AP and/or the STA in the above method embodiments may perform some or all of the steps in the embodiments, and these steps or operations are only examples, and the embodiments of the present application may also include performing other operations or variations of various operations.

It is also to be understood that the terminology and/or the description of different embodiments may be in the nature of words and/or phrases and may be referred to one another or any other embodiment herein without specifically indicating or implying any logical conflict between such embodiments, wherein technical features of different embodiments may be combined to form new embodiments based on their inherent logical relationships.

It should also be understood that, in the foregoing method embodiment, the sequence numbers of the foregoing processes do not imply an order of execution, and the order of execution of the processes should be determined by their functions and inherent logic, and should not limit the implementation process of the embodiment of the present application.

The method for frequency offset estimation provided by the embodiment of the present application is described in detail above with reference to fig. 6, and the apparatus for frequency offset estimation provided by the embodiment of the present application is described in detail below with reference to fig. 15 to 18.

Referring to fig. 15, fig. 15 is a schematic diagram of an apparatus 150 for frequency offset estimation according to the present application. As shown in fig. 15, the apparatus 1500 includes a receiving unit 1510 and a transmitting unit 1520.

A receiving unit 1510, configured to receive first information from an access point AP, where the first information is used to indicate a number M of spatial streams corresponding to STAs that need to report a first training sequence and a second training sequence, and a first subcarrier subset occupied by the first training sequence or the second training sequence reported by the station;

the station is any one of multiple stations communicating with the access point, the first subcarrier subset is a subcarrier subset corresponding to the station in S preset subcarrier subsets, and M and S are positive integers and used for determining the first training sequence or the second training sequence.

A sending unit 1520, configured to send a physical layer protocol data unit PPDU to the AP on the first subcarrier subset, where the PPDU includes the first training sequence and a second training sequence, and the first training sequence and the second training sequence are used to determine a frequency offset value between the station and the AP.

The apparatus 1500 completely corresponds to the STA in the method embodiment, and the apparatus 1500 may be the STA in the method embodiment, or a chip or a functional module inside the STA in the method embodiment. The corresponding elements of apparatus 1500 are for performing the corresponding steps performed by the STA in the method embodiment shown in fig. 6.

The receiving unit 1510 in the apparatus 1500 performs the steps of STA receiving in the method embodiment. For example, step S610 of receiving the first information in fig. 6 is performed.

The transmitting unit 1520 performs the steps of the STA transmission in the method embodiment. For example, step S630 of transmitting a PPDU to the AP in fig. 6 is performed;

the apparatus 150 may also include a processing unit that performs the steps of the STA internal implementation or processing in the method embodiments. For example, step S620 of generating the first training sequence in fig. 6 is performed.

The transmitting unit 1520 and the receiving unit 1510 may constitute a transceiving unit, and have both functions of receiving and transmitting. Wherein the processing unit may be a processor. The transmitting unit 1520 may be a transmitter and the receiving unit 1510 may be a receiver. The receiver and transmitter may be integrated together to form a transceiver.

Referring to fig. 16, fig. 16 is a schematic structural diagram of an STA 1600 suitable for use in an embodiment of the present application. The STA 1600 may be used in the system shown in fig. 1. For convenience of explanation, fig. 16 shows only main components of the STA. As shown in fig. 16, the STA 1600 includes a processor, a memory, a control circuit, an antenna, and an input-output device (corresponding to the transmitting unit 1520 and the receiving unit 1530 shown in fig. 15). The processor is used for controlling the antenna and the input and output device to send and receive signals, the memory is used for storing a computer program, and the processor is used for calling and running the computer program from the memory to execute corresponding procedures and/or operations executed by the STA in the method for frequency offset estimation provided by the application. And will not be described in detail herein.

Those skilled in the art will appreciate that fig. 16 shows only one memory and processor for ease of illustration. In an actual STA, there may be multiple processors and memories. The memory may also be referred to as a storage medium or a storage device, and the like, which is not limited in this application.

Referring to fig. 17, fig. 17 is a schematic diagram of an apparatus 1700 for frequency offset estimation proposed in the present application. As shown in fig. 17, the apparatus 1700 includes a receiving unit 1710 and a transmitting unit 1720.

A sending unit 1720, configured to send first information to a station STA, where the first information is used to indicate a number M of spatial streams corresponding to STAs that need to report a first training sequence and a second training sequence and a first subcarrier subset occupied by the first training sequence or the second training sequence reported by the STA,

the STA is any one of a plurality of STAs communicating with the access point, the first subcarrier subset is a subcarrier subset corresponding to the STA in S preset subcarrier subsets, and M and S are positive integers and are used for determining the first training sequence or the second training sequence.

The number M of spatial streams corresponding to the STA refers to a sum M of the number of antennas included in at least one STA that needs to report the first training sequence and the second training sequence, and in this embodiment of the present application, a single-antenna STA is taken as an example for description (as shown in fig. 2 (b), a multi-antenna STA may be equivalent to a single-antenna STA).

In addition, when the embodiment of the present application is also applied to uplink transmission, the first information may be PPDU sent by an STA to an AP, where first indication information included in the first information is used to indicate a number M of spatial streams corresponding to the STA that needs to report a first training sequence and a second training sequence, and second indication information used to indicate the STA to report a first subcarrier subset occupied by the first training sequence or the second training sequence, and the first indication information may be carried in a signaling field of the PPDU sent by the STA to the AP, for example, in a HE-SIG field or an EHT-SIG field in the PPDU.

A receiving unit 1710, configured to receive, on the first subcarrier subset, a physical layer protocol data unit PPDU from the STA, where the PPDU includes the first training sequence and the second training sequence, and the first training sequence and the second training sequence are used to determine a frequency offset value between the STA and the access point.

The apparatus 1700 completely corresponds to the AP in the method embodiment, and the apparatus 1700 may be the AP in the method embodiment or a chip or a functional module inside the AP in the method embodiment. Corresponding elements of the apparatus 1700 are adapted to perform corresponding steps performed by the AP in the method embodiment shown in fig. 6.

Receiving unit 1710 in apparatus 1700 performs the steps of AP receiving in the method embodiment. For example, step S620 in fig. 6 is performed in which the receiving STA transmits the PDU.

A receiving unit 1720 in the apparatus 1700 performs the steps of the AP transmission in the method embodiment. For example, step S610 of transmitting the first information to the STA in fig. 6 is performed.

The apparatus 1700 may further comprise a processing unit to perform the steps of the AP internal implementation or processing in the method embodiments. For example, step S640 of fig. 6 for frequency offset estimation is performed.

The receiving unit 1710 and the transmitting unit 1720 may constitute a transmitting and receiving unit, and have both a receiving function and a transmitting function. Wherein the processing unit may be a processor. The transmitting unit 1720 may be a transmitter. The receiving unit 1710 may be a receiver. The receiver and transmitter may be integrated together to form a transceiver.

Referring to fig. 18, fig. 18 is a schematic structural diagram of an AP1800 applicable to the embodiment of the present application, which may be used to implement the functions of the AP in the foregoing method for frequency offset estimation. The structure of the AP can be schematically illustrated.

The AP includes 1810 portions and 1820 portions. 1810 part is mainly used for receiving and transmitting radio frequency signals and converting the radio frequency signals and baseband signals; section 1820 is primarily used for baseband processing, control of location management components, and the like. Portion 1810 may be referred to generally as a transceiver unit, transceiver, transceiving circuitry, transceiver, or the like. Section 1820 is generally a control center of the location management component, and may be generally referred to as a processing unit, for controlling the location management component to perform the processing operations on the AP side in the above-described method embodiments.

1810 transceiver unit, which may also be referred to as transceiver or transceiver, includes an antenna and a radio frequency unit, wherein the radio frequency unit is mainly used for radio frequency processing. Alternatively, a device used for implementing a receiving function in part 1810 may be regarded as a receiving unit, and a device used for implementing a sending function may be regarded as a sending unit, that is, part 1810 includes a receiving unit and a sending unit. The receiving unit may also be referred to as a receiver, a receiving circuit, or the like, and the sending unit may be referred to as a transmitter, a transmitting circuit, or the like.

Section 1820 may include one or more boards, each of which may include one or more processors and one or more memories. The processor is used to read and execute programs in the memory to implement baseband processing functions and control of the positioning management components. If a plurality of single boards exist, the single boards can be interconnected to enhance the processing capacity. As an alternative implementation, multiple boards may share one or more processors, multiple boards may share one or more memories, or multiple boards may share one or more processors at the same time.

It should be understood that fig. 18 is merely an example and not a limitation, and the AP including the transceiving unit and the processing unit may not depend on the structure shown in fig. 18.

It should also be understood that the AP1800 shown in fig. 18 is capable of implementing the AP functionality involved in the method embodiment of fig. 6. The operations and/or functions of the respective units in the AP1800 are respectively for implementing the corresponding procedures executed by the AP in the method embodiment of the present application. To avoid repetition, detailed description is appropriately omitted herein. The structure of the AP illustrated in fig. 18 is only one possible form, and should not be construed as limiting the embodiments of the present application in any way. This application does not exclude the possibility of other forms of AP structures that may appear in the future.

An embodiment of the present application further provides a communication system, which includes the STA and the AP.

The present application also provides a computer-readable storage medium having stored therein instructions, which when executed on a computer, cause the computer to perform the steps performed by the STA in the method as shown in fig. 6.

The present application also provides a computer-readable storage medium, which stores instructions that, when executed on a computer, cause the computer to perform the steps performed by the AP in the method shown in fig. 6.

The present application also provides a computer program product containing instructions which, when run on a computer, cause the computer to perform the steps performed by the STA in the method as shown in fig. 6.

The present application also provides a computer program product containing instructions which, when run on a computer, cause the computer to perform the steps performed by the AP in the method as shown in fig. 6.

The application also provides a chip comprising a processor. The processor is configured to read and execute a computer program stored in the memory to perform corresponding operations and/or procedures performed by the STA in the method for frequency offset estimation provided by the present application. Optionally, the chip further comprises a memory, the memory is connected with the processor through a circuit or a wire, and the processor is used for reading and executing the computer program in the memory. Further optionally, the chip further comprises a communication interface, and the processor is connected to the communication interface. The communication interface is used for receiving data and/or information needing to be processed, and the processor acquires the data and/or information from the communication interface and processes the data and/or information. The communication interface may be an input/output interface, interface circuit, output circuit, input circuit, pin or related circuit on the chip, etc. The processor may also be embodied as a processing circuit or a logic circuit.

The application also provides a chip comprising a processor. The processor is configured to read and execute the computer program stored in the memory to perform corresponding operations and/or procedures performed by the AP in the method for frequency offset estimation provided by the present application. Optionally, the chip further comprises a memory, the memory is connected with the processor through a circuit or a wire, and the processor is used for reading and executing the computer program in the memory. Further optionally, the chip further comprises a communication interface, and the processor is connected to the communication interface. The communication interface is used for receiving data and/or information needing to be processed, and the processor acquires the data and/or information from the communication interface and processes the data and/or information. The communication interface may be an input/output interface, interface circuit, output circuit, input circuit, pin or related circuit on the chip, etc. The processor may also be embodied as a processing circuit or a logic circuit. It should be understood that the above chip may be replaced by a chip system, which is not described herein. The terms "comprises," "comprising," and "having," and any variations thereof, in this application are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.

Those of ordinary skill in the art will appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware or combinations of computer software and electronic hardware. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present application.

It is clear to those skilled in the art that, for convenience and brevity of description, the specific working processes of the above-described systems, apparatuses and units may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again.

In the several embodiments provided in the present application, it should be understood that the disclosed system, apparatus and method may be implemented in other 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 application 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 functions, if implemented in the form of software functional units and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solutions of the present application or portions thereof that substantially contribute to the prior art may be embodied in the form of a software product, which is stored in a storage medium and includes several instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the methods described in the embodiments of the present application. And the aforementioned storage medium includes: a U-disk, a portable hard disk, a read-only memory (ROM), a Random Access Memory (RAM), a magnetic disk, an optical disk, or other various media capable of storing program codes.

In addition, the term "and/or" in the present application is only one kind of association relationship describing the associated object, and means that three kinds of relationships may exist, for example, a and/or B may mean: a exists alone, A and B exist simultaneously, and B exists alone. In addition, the character "/" herein generally indicates that the former and latter related objects are in an "or" relationship; the term "at least one" in this application may mean "one" and "two or more", e.g., at least one of A, B and C may mean: a alone, B alone, C alone, A and B together, A and C together, C and B together, and A and B together and C and B together, seven cases exist. In addition, the term "left-multiplying/right-multiplying" in this application describes the way of computation between matrices. For example, the matrix A is multiplied by the matrix B to obtain a matrix BA, and the matrix A is multiplied by the matrix B to obtain a matrix AB; the term "left-times/right-times" in this application describes the way in which the calculations between the matrices are made. For example, matrix A is multiplied left by matrix B to yield matrix AB, and matrix A is multiplied right by matrix B to yield matrix BA.

The above description is only for the specific embodiments of the present application, but the scope of the present application 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 application, and shall be covered by the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. A method for frequency offset estimation, applied to an Access Point (AP) communicating with a plurality of Stations (STA), comprises:

the AP sends first information to an STA, wherein the first information is used for indicating the number M of spatial streams corresponding to the STA which needs to report a first training sequence and a second training sequence and a first subcarrier subset occupied by the first training sequence or the second training sequence reported by the STA,

the STA is any one of the STAs, the first subcarrier subset is a subcarrier subset corresponding to the STA in S preset subcarrier subsets, and M and S are positive integers and used for determining the first training sequence or the second training sequence;

the AP receives a physical layer protocol data unit (PPDU) from the STA on the first subcarrier subset, wherein the PPDU comprises the first training sequence and a second training sequence, and the first training sequence and the second training sequence are used for determining a frequency offset value between the STA and the AP.

2. The method of claim 1, wherein the first information comprises:

first indication information and second indication information, the first indication information being used for indicating the M, the second indication information being used for determining the first subcarrier subset.

3. The method of claim 2, wherein the AP sending the first information to the STA comprises:

and the AP sends a trigger frame to the STA, wherein the trigger frame is used for triggering the STA to report the PPDU, the trigger frame carries the first indication information and the second indication information, and the first indication information is a scheduling information field.

4. The method of claim 3, wherein the carrying of the first indication information in the trigger frame comprises:

the trigger frame comprises a general information field, and the general information field comprises the first indication information.

5. The method of any of claims 1-4, wherein the first training sequence or the second training sequence is determined by a mapping relationship between the STA and a P matrix element.

6. The method according to any one of claims 1-4, further comprising:

the AP receives a first information matrix on the first subcarrier subset, wherein the first information matrix is determined by the first training sequence and channel information and a frequency offset value between the STA and the AP;

the AP receiving a second information matrix on the first subcarrier subset, the second information matrix being determined by the second training sequence and channel information and a frequency offset value between the STA and the AP;

and determining a frequency offset value between the STA and the AP according to the first information matrix and the second information matrix.

7. The method according to any one of claims 1-4, wherein the PPDU further comprises a channel estimation training sequence, and the first training sequence, the second training sequence and the channel estimation training sequence are arranged in sequence in the PPDU, or alternatively, are arranged alternately and crossly.

8. The method of any of claims 1-4, wherein the PPDU further comprises an automatic gain control training sequence, the automatic gain control training sequence being used by the AP to adjust the received power at which the first and/or second training sequences are received on the first subset of subcarriers.

9. A method for frequency offset estimation, applied to any STA of a plurality of stations STA communicating with an access point AP, comprising:

the STA receives first information from the AP, wherein the first information is used for indicating the number M of spatial streams corresponding to the STA which needs to report a first training sequence and a second training sequence and a first subcarrier subset occupied by the STA reporting the first training sequence or the second training sequence;

the first subcarrier subset is a subcarrier subset corresponding to the STA in S preset subcarrier subsets, and M and S are positive integers used for determining the first training sequence or the second training sequence;

and the STA sends a physical layer protocol data unit (PPDU) to the AP on the first subcarrier subset, wherein the PPDU comprises the first training sequence and a second training sequence, and the first training sequence and the second training sequence are used for determining a frequency offset value between the STA and the AP.

10. The method of claim 9, wherein the first information comprises:

11. The method of claim 10, wherein the STA receiving the first information from the AP comprises:

the STA receives a trigger frame from the AP, wherein the trigger frame is used for triggering the STA to report the PPDU, the trigger frame carries the first indication information and the second indication information, and the first indication information is a scheduling information field.

12. The method of claim 11, wherein the carrying of the first indication information in the trigger frame comprises:

13. The method of any of claims 9-12, wherein the first training sequence or the second training sequence is determined by a mapping relationship between the STA and a P matrix element.

14. The method according to any of claims 9-12, wherein the PPDU further comprises a channel estimation training sequence, and wherein the first training sequence, the second training sequence and the channel estimation training sequence are arranged in sequence in the PPDU or alternately and crossly arranged.

15. The method of any of claims 9-12, wherein the PPDU further comprises an automatic gain control training sequence for the AP to adjust a receive power at which the first and/or second training sequences are received on the first subset of subcarriers.

16. An access point, comprising:

a sending unit, configured to send first information to a station STA, where the first information is used to indicate a number M of spatial streams corresponding to STAs that need to report a first training sequence and a second training sequence and a first subcarrier subset occupied by the first training sequence or the second training sequence reported by the STA,

the STA is any one of a plurality of STAs communicating with the access point, the first subcarrier subset is a subcarrier subset corresponding to the STA in S preset subcarrier subsets, and M and S are positive integers and used for determining the first training sequence or the second training sequence;

a receiving unit, configured to receive a physical layer protocol data unit PPDU from the STA on the first subcarrier subset, where the PPDU includes the first training sequence and a second training sequence, and the first training sequence and the second training sequence are used to determine a frequency offset value between the STA and the access point.

17. The access point of claim 16, wherein the first information comprises:

18. The access point of claim 17, wherein the transmitting unit transmits the first information to the STA comprises:

the sending unit sends a trigger frame to the STA, where the trigger frame is used to trigger the STA to report the PPDU, and the trigger frame carries the first indication information and the second indication information, and the first indication information is a scheduling information field.

19. The access point of claim 18, wherein the carrying of the first indication information in the trigger frame comprises:

20. The access point of any of claims 16-19, wherein the first training sequence or the second training sequence is determined by a mapping relationship between the STA and a P matrix element.

21. The access point of any of claims 16-19, wherein the receiving unit is further configured to receive a first information matrix on the first subset of subcarriers, the first information matrix being determined by the first training sequence and channel information and a frequency offset value between the STA and the access point;

the receiving unit is further configured to receive a second information matrix on the first subcarrier subset, where the second information matrix is determined by the second training sequence and channel information and a frequency offset value between the STA and the access point;

wherein a frequency offset value between the STA and the access point is determined according to the first information matrix and the second information matrix.

22. The access point of any of claims 16-19, wherein the PPDU further comprises a channel estimation training sequence, and wherein the first training sequence, the second training sequence and the channel estimation training sequence are arranged in sequence in the PPDU or are arranged to be interleaved at intervals.

23. The access point of any of claims 16-19, wherein the PPDU further comprises an automatic gain control training sequence for the access point to adjust a receive power at which the first and/or second training sequences are received on the first subset of subcarriers.

24. A station, comprising:

a receiving unit, configured to receive first information from an access point AP, where the first information is used to indicate a number M of spatial streams corresponding to a station that needs to report a first training sequence and a second training sequence, and a first subcarrier subset occupied by the station reporting the first training sequence or the second training sequence;

the station is any one of multiple stations communicating with the access point, the first subcarrier subset is a subcarrier subset corresponding to the station in S preset subcarrier subsets, and M and S are positive integers and used for determining the first training sequence or the second training sequence;

a sending unit, configured to send a physical layer protocol data unit PPDU to the AP on the first subcarrier subset, where the PPDU includes the first training sequence and a second training sequence, and the first training sequence and the second training sequence are used to determine a frequency offset value between the station and the AP.

25. The station of claim 24, wherein the first information comprises:

26. The station of claim 25, wherein the receiving unit receives the first information from the AP comprises:

the receiving unit receives a trigger frame from the AP, where the trigger frame is used to trigger the station to report the PPDU, where the trigger frame carries the first indication information and the second indication information, and the first indication information is a scheduling information field.

27. The station of claim 26, wherein the trigger frame carrying the first indication information comprises:

28. The station according to any of claims 24-27, characterized in that the first training sequence or the second training sequence is determined by a mapping between the station and a P matrix element.

29. The station of any one of claims 24-27, wherein the PPDU further comprises a channel estimation training sequence, and wherein the first training sequence, the second training sequence and the channel estimation training sequence are arranged in sequence in the PPDU or alternately and crossly arranged.

30. The station of any one of claims 24-27, wherein the PPDU further comprises an automatic gain control training sequence for the AP to adjust a receive power at which the first and/or second training sequences are received on the first subset of subcarriers.

31. A communications apparatus, comprising:

a memory for storing a computer program;

a processor for executing a computer program stored in the memory, to cause the communication apparatus to perform the method of any one of claims 1-8 or to cause the communication apparatus to perform the method of any one of claims 9-15.

32. A computer-readable storage medium, characterized in that the computer-readable storage medium is for storing a computer program comprising instructions for implementing the method according to any one of claims 1-8, or comprising instructions for implementing the method according to any one of claims 9-15.