WO2021190527A1

WO2021190527A1 - Frequency offset estimation method, station, and access point

Info

Publication number: WO2021190527A1
Application number: PCT/CN2021/082558
Authority: WO
Inventors: 陈正; 袁方超; 陈鹏
Original assignee: 华为技术有限公司
Priority date: 2020-03-27
Filing date: 2021-03-24
Publication date: 2021-09-30
Also published as: CN113452635B; CN113452635A

Abstract

The present application provides a frequency offset estimation method, a station (STA), and an access point (AP). The frequency offset estimation method can be applied to an uplink multi-STA multiple-input and multiple-output scenario, and comprises: an AP instructs an STA by means of first information how to generate and report frequency offset estimation training sequences; and determine a frequency offset between the AP and the STA on the basis of at least two received frequency offset estimation training sequences. The technical solution provided in the present application can improve the accuracy for the AP to obtain a frequency offset value between each of multiple STAs and the AP. The present application can be applied to 802.11ax, 802.11be, and a future wireless local area network wireless fidelity (WiFi) system.

Description

Method, site and access point for frequency offset estimation

This application claims the priority of a Chinese patent application filed with the Chinese Patent Office on March 27, 2020, the application number is 202010228622.5, and the application name is "Methods, Sites, and Access Points for Frequency Offset Estimation", all of which are approved The reference is incorporated in this application.

Technical field

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

Background technique

With the development of wireless local area network technology, the uplink multiple-user multiple input multiple output (UL MU-MIMO) technology is introduced, and multiple uplink stations (stations, STAs) are connected to the access point (access point, AP) sends data at the same time. Through spatial multiplexing technology and orthogonal equalization on the AP side, interference between various sites is eliminated, and the utilization of uplink spectrum resources is effectively increased.

However, there are different types of sites, and the radio links of the sites are different, so the carrier frequency used by the sites when sending data is difficult to be consistent, that is, multiple sites cannot achieve frequency synchronization when sending data to the AP. As a result, when the AP side performs channel estimation, it is difficult for the channels of multiple stations to be orthogonal and crosstalk with each other, which greatly reduces the accuracy of channel estimation. Therefore, how to improve the uplink multi-site channel multi-input multi-output scenario where the AP estimates the frequency offset values of multiple sites relative to the AP has become a problem to be solved urgently.

Summary of the invention

This application provides a method, station, and access point for frequency offset estimation, in order to improve the accuracy of the frequency offset estimation determined by the access point.

In the first aspect, a method for frequency offset estimation is provided. The method for frequency offset estimation may be executed by an access point AP, or may also be executed by a chip or circuit set in the AP. This is not limited.

The method used for frequency offset estimation includes:

The AP sends first information to the STA. The first information is used to indicate the number of spatial streams M corresponding to the STA that needs to report the first training sequence and the second training sequence, and the STA reports that the first training sequence or the second training sequence occupies The first subcarrier subset of the M And S are positive integers, used to determine the first training sequence or the second training sequence; the AP receives the physical layer protocol data unit PPDU from the STA on the first subcarrier subset, and the PPDU includes the first A training sequence and a second training sequence, where the first training sequence and the second training sequence are used to determine the frequency offset value between the STA and the AP.

In the method for frequency offset estimation provided by the embodiment of this application, the AP instructs the STA how to generate and report the frequency offset estimation training sequence through the first information, and determines the relationship between the AP and the STA based on the received at least two frequency offset estimation training sequences. The frequency offset value can improve the accuracy of AP's determination of frequency offset estimation.

With reference to the first aspect, in some implementations of the first aspect, the first information includes: first indication information and second indication information, the first indication information is used for indicating the M, and the second indication information is used for Determine the first subset of subcarriers.

The above-mentioned indication information indicating the number M of STAs and the indication information indicating the first subcarrier subset may be two different indication information, providing different indication information transmission modes, thereby improving the flexibility of the solution.

With reference to the first aspect, in some implementations of the first aspect, the AP sending the first information to the STA includes: the AP sends a trigger frame to the STA, and 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.

In the method for frequency offset estimation provided by the embodiment of the application, the first information sent by the AP to instruct the STA to generate and report the frequency offset estimation training sequence can reuse the trigger frame sent by the existing AP to the STA, thereby saving Signaling overhead, and can be compatible with existing processes to improve solution compatibility.

With reference to the first aspect, in some implementations of the first aspect, 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 for including the above-mentioned first indication information in the trigger frame is to carry the first indication information in the general information field in the trigger frame, and multiplex the existing fields in the trigger frame to carry the first indication. Information, can save signaling overhead.

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

The above-mentioned first training sequence or second training sequence can be determined based on the element corresponding to the STA in the preset P matrix, and a method for determining the first training sequence or the second training sequence based on the known P matrix is provided, without introducing new The matrix can increase compatibility with existing solutions.

With reference to the first aspect, in some implementations of the first aspect, the method further includes: the AP receives a first information matrix on the first subset of subcarriers, the first information matrix consisting of the first training sequence and The channel information and the frequency offset value between the STA and the AP are determined; the AP receives a second information matrix on the first subcarrier subset, and the second information matrix is composed of the second training sequence and channel information and the STA The frequency offset value between the STA and the AP is determined; 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 by the embodiment of the present application, the AP may determine the frequency offset value between the STA and the AP based on the information matrix received by itself on the first subcarrier subset. Since the two information matrices received by the AP on the first subcarrier subset are different due to the frequency offset between the STA and the AP, the frequency between the STA and the AP can be accurately determined based on the two received information matrices. Offset value to improve the accuracy of AP's determination of frequency offset estimation.

With reference to the first aspect, in some 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 arranged at intervals.

In the method for frequency offset estimation provided by the embodiment of the application, when the PPDU sent by the STA to the AP, and the PPDU includes the first training sequence, the second training sequence and the channel estimation training sequence, the first training sequence, the second training sequence There are many ways to arrange the training sequence and the channel estimation training sequence in the PPDU, which can improve the flexibility of the PPDU structure.

With reference to the first aspect, in some implementations of the first aspect, the first training sequence, the second training sequence, and the channel estimation training sequence are alternately arranged in the PPDU including: the first training sequence is located after the preamble sequence and is located in the channel Before the estimated training sequence, the second training sequence is located after the channel estimation training sequence and before the data symbols; 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 in the first After the channel estimation training sequence and before the second channel estimation training sequence, the first channel estimation training sequence and the second channel estimation training sequence form the channel estimation training sequence.

With reference to the first aspect, in some implementations of the first aspect, the first training sequence, the second training sequence, and the channel estimation training sequence are sequentially arranged in the PPDU including: the first training sequence is located after the preamble sequence and is located in the first Before the second training sequence, the second training sequence is located before the channel estimation training sequence; or, the first training sequence is located after the channel estimation training sequence, and is located before the second training sequence, and the second training sequence is located before the data symbols.

The method for frequency offset estimation provided in the embodiment of the present application provides a variety of different PPDU frame format structures, thereby improving the flexibility of the solution.

With reference to the first aspect, in some implementations of the first aspect, the PPDU further includes an automatic gain control training sequence, and the automatic gain control training sequence is used by the AP to adjust to receive the first subcarrier subset on the first subcarrier subset. The received power of the training sequence and/or the second training sequence.

In the method for frequency offset estimation provided by the embodiment of the application, the PPDU sent by the STA to the AP, and the automatic gain control training sequence is added to the PPDU, and the AP can adjust the first subcarrier subset based on the automatic gain control training sequence. The received power of the first training sequence and/or the second training sequence is received upward, so that the receiving power of the AP receiving the first training sequence and/or the second training sequence is adjustable.

In the second aspect, a method for frequency offset estimation is provided. The method for frequency offset estimation can be executed by the STA, or can also be executed by a chip or circuit set in the STA, which is not limited in this application. .

The method used for frequency offset estimation includes:

The STA receives the first information from the AP, the first information is used to indicate the number of spatial streams M corresponding to the STA that needs to report the first training sequence and the second training sequence, and the STA reports the first training sequence or the second training sequence Occupied first subcarrier subset; wherein, the first subcarrier subset is the subcarrier subset corresponding to the STA in the S preset subcarrier subsets, and the M and S are positive integers and are used to determine the first subcarrier subset. A training sequence or a second training sequence;

The STA sends a physical layer protocol data unit PPDU to the AP on the first subcarrier subset. 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 The frequency offset value between the STA and the AP.

In 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 AP based on the received at least two frequency offset estimation training sequences The frequency offset value between the AP and the STA can improve the accuracy of the AP's determination of the frequency offset estimation.

With reference to the second aspect, in some implementations of the second aspect, the first information includes: first indication information and second indication information, the first indication information is used for indicating the M, and the second indication information is used for Determine the first subset of subcarriers.

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

In the method for frequency offset estimation provided by the embodiments of this application, the first information sent by the AP to instruct the STA on how to generate and report the frequency offset estimation training sequence can reuse the existing trigger frame sent by the AP to the STA, thereby saving Signaling overhead, and can be compatible with existing processes to improve solution compatibility.

With reference to the second aspect, in some implementation manners 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 the mapping relationship between the STA and P matrix elements.

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 arranged at intervals.

With reference to the second aspect, in some implementations of the second aspect, the first training sequence, the second training sequence, and the channel estimation training sequence are alternately arranged in the PPDU including: the first training sequence is located after the preamble sequence and is located in the channel Before the estimated training sequence, the second training sequence is located after the channel estimation training sequence and before the data symbols; 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 in the first After the channel estimation training sequence and before the second channel estimation training sequence, the first channel estimation training sequence and the second channel estimation training sequence form the channel estimation training sequence.

With reference to the second aspect, in some implementations of the second aspect, the first training sequence, the second training sequence, and the channel estimation training sequence are sequentially arranged in the PPDU including: the first training sequence is located after the preamble sequence and is located in the first training sequence. Before the second training sequence, the second training sequence is located before the channel estimation training sequence; or, the first training sequence is located after the channel estimation training sequence, and is located 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, and the automatic gain control training sequence is used by the AP to adjust to receive the first subcarrier subset on the first subcarrier subset. The received power of the training sequence and/or the second training sequence.

In a third aspect, an apparatus for frequency offset estimation is provided, and the apparatus is used to execute the method provided in the above-mentioned first aspect. Specifically, the device may include a module for executing the first aspect and any possible implementation manner of the first aspect.

In a fourth aspect, a device for frequency offset estimation is provided, and the device is configured to execute the method provided in the second aspect. Specifically, the device may include a module for executing the second aspect and any possible implementation manner of the second aspect.

In a fifth aspect, an apparatus for frequency offset estimation is provided, including a processor. The processor is coupled to the memory and can be used to execute instructions in the memory to implement the foregoing first aspect and the method in any one of the possible implementation manners of the first aspect. Optionally, the device further includes a memory. Optionally, the device further includes a communication interface, and the processor is coupled with the communication interface.

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

In another implementation, the device is a chip or a chip system.

Optionally, the transceiver may be a transceiver circuit. Optionally, the input/output interface may be an input/output circuit.

In a sixth aspect, an apparatus for frequency offset estimation is provided, including a processor. The processor is coupled with the memory and can be used to execute instructions in the memory to implement the foregoing second aspect and the method in any one of the possible implementation manners of the second aspect. Optionally, the device further includes a memory. Optionally, the device further includes a communication interface, and the processor is coupled with the communication interface.

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

In another implementation, the device is a chip or a chip system.

In a seventh aspect, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by an apparatus, the apparatus enables the apparatus to implement the first aspect and the method in any one of the possible implementation manners of the first aspect .

In an eighth aspect, a computer-readable storage medium is provided with a computer program stored thereon, which when executed by an apparatus, causes the apparatus to implement the second aspect and the method in any one of the possible implementation manners of the second aspect .

In a ninth aspect, a computer program product containing instructions is provided, when the instructions are executed by a computer, the device implements the first aspect and the method provided in any one of the possible implementation manners of the first aspect.

In a tenth aspect, a computer program product containing instructions is provided, which when executed by a computer, causes an apparatus to implement the second aspect and the method provided in any one of the possible implementation manners of the second aspect.

In an eleventh aspect, a communication system is provided, including the aforementioned access point and station.

Description of the drawings

Figure 1 is a system schematic diagram of a typical WLAN deployment scenario.

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

FIG. 3 is a schematic diagram of two STAs sending data to an AP according to an embodiment of the present application.

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

FIG. 5 is a schematic diagram of orthogonal sequences corresponding to multiple STAs provided in an embodiment of the present application.

FIG. 6 is a schematic flowchart of a method for frequency offset estimation provided by an embodiment of the present application.

(A) and (b) in FIG. 7 are schematic diagrams of dividing a subset of subcarriers according to an embodiment of the present application.

FIG. 8 is a schematic diagram of a general information field of a trigger frame provided by an embodiment of the present application.

(A) and (b) in FIG. 9 are schematic diagrams of indirectly indicating a subset of subcarriers according to an embodiment of the present application.

FIG. 10 is a schematic diagram of determining related information of a frequency offset estimation training sequence provided by an embodiment of the present application.

FIG. 11 is a schematic diagram of a frequency offset estimation training sequence provided by an embodiment of the present application.

(A)-(e) in FIG. 12 are schematic diagrams of the frame format of the physical frame provided in the embodiment of the present application.

FIG. 13 is a scenario to which the method for frequency offset estimation provided by an embodiment of the present application is applicable.

FIG. 14 is a schematic diagram of a physical frame sent by multiple STAs received by an AP.

FIG. 15 is a schematic diagram of an apparatus 1500 for frequency offset estimation proposed in this application.

FIG. 16 is a schematic structural diagram of a STA 1600 applicable to an embodiment of the present application.

FIG. 17 is a schematic diagram of an apparatus 1700 for frequency offset estimation proposed in this application.

FIG. 18 is a schematic structural diagram of an AP 1800 applicable to an embodiment of the present application.

Detailed ways

The technical solution in this application will be described below in conjunction with 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 AP and STA. Each BSS may contain one AP and multiple STAs associated with the AP.

The above-mentioned AP is called an access point, and can also be called a wireless access point or hotspot. APs are the access points for user terminals to enter the wired network and are mainly deployed in homes, buildings, and campuses. A typical AP coverage radius is tens of meters to hundreds of meters. It should be understood that the AP can also be deployed outdoors. AP is equivalent to a bridge connecting wired network and wireless network, and its main function is to connect the clients of each wireless network together, and then connect the wireless network to the Ethernet. At present, the main standards 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 that supports the WLAN standard. For example, the AP may be a terminal device or a network device with a wireless fidelity (wireless fidelity, WiFi) chip.

The STA is called a station. In this application, the STA represents a user terminal, so it may be directly called a user terminal or a user in the following. STA can be equipped with wireless communication chip, wireless sensor or wireless communication terminal. STA can be a device that supports WLAN standard. For example, STA can be a mobile phone that supports WiFi communication function, a tablet computer that supports WiFi communication function, a set-top box that supports WiFi communication function, a smart TV that supports WiFi communication function, and WiFi communication function is supported. Smart wearable devices and computers supporting WiFi communication functions.

Figure 1 is a system schematic diagram of a typical WLAN deployment scenario, including one AP and 4 STAs. The AP can communicate with STA#1, STA#2, STA#3, and STA#4, respectively. The uplink transmission mode between AP and STA includes but not limited to orthogonal frequency-division multiple access (OFDMA) mode, multi-site channel multiple input multiple output (MU-MIMO) ) Mode or a hybrid transmission mode of OFDMA and MU-MIMO.

In this application, the uplink transmission mode between the AP and multiple STAs is an MU-MIMO mode as an example, and the number of AP antennas N is greater than or equal to the sum M of the antennas of all STAs associated with it. It should be understood that any STA can include multiple antennas. When a certain STA has two antennas, the STA can be equivalent to two identical single-antenna STAs, but the channels from 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 a STA in an MU-MIMO manner according to an embodiment of the present application. The AP in FIG. 2 includes N antennas (antenna #1 to antenna #N as shown in FIG. 2), and the total number of antennas of all STAs is M. In Fig. 2 h _NM represents the channel between the antenna M on the STA side and the antenna N on the AP side.

In this application, the number of spatial streams M refers to the total number of antenna elements M of the STA, and the number of spatial streams corresponding to the STA M can be understood as the total number of antenna elements M of at least one STA;

The embodiments of this application are applicable to systems of 2 spatial streams (spatial stream, ss), and are also applicable to systems of 4, 8, and 16 ss. With the development of technology, the technical solutions provided in the embodiments of this application can also be applied to more The system of spatial flow numbers.

Figure 2(a) shows that one STA may include multiple antennas. If there is a frequency difference between the STA and the AP, the signals sent by the multiple antennas included in the STA and the AP have the same frequency difference. Figure 2(b) is an equivalent transformation of Figure 2(a), that is, an STA including multiple antennas can be equivalent to multiple identical single-antenna STAs. It should be understood that this equivalent transformation is only for easier understanding of this application The technical solution provided does not constitute any limit to the protection scope of this application. In the case that a STA including multiple antennas is equivalent to multiple identical single-antenna STAs, the total number of antennas M of the above-mentioned STAs can be understood as the number of STAs M, that is, the multi-antenna STA is equivalent to a single antenna. In the case of an antenna STA, the number M of spatial streams corresponding to the STAs involved in the embodiment of the present application may also be referred to as the number M of STAs.

In order to facilitate the understanding of the embodiments of the present application, the following descriptions are made.

First, in this application, "used to indicate" can include both used for direct indication and used for indirect indication. When describing a certain indication information for indicating A, the indication information may directly indicate A or indirectly indicate A, but it does not mean that A must be carried in the indication information.

The information indicated by the instruction information is called the information to be indicated. In the specific implementation process, there are many ways to indicate the information to be indicated. For example but not limited to, the information to be indicated can be directly indicated, such as the information to be indicated or the information to be indicated. Indicates the index of the information, etc. The information to be indicated can also be indicated indirectly by indicating other information, where there is an association relationship 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 other parts of the information to be indicated are known or agreed in advance. For example, it is also possible to realize the indication of specific information by means of a pre-arranged order (for example, stipulated in an agreement) of various information, so as to reduce the indication overhead to a certain extent. At the same time, it can also identify the common parts of each information and give unified instructions, so as to reduce the instruction overhead caused by separately indicating the same information.

Second, the first, second, and various digital numbers (for example, "#1", "#2", etc.) shown in this application are only for convenience of description, and are used for distinguishing objects, and are not used to limit the text. Apply for the scope of the embodiment. For example, distinguish different sequences, or distinguish different STAs, etc. It is not used to describe a specific order or sequence. It should be understood that the objects described in this way can be interchanged under appropriate circumstances, so as to be able to describe solutions other than the embodiments of the present application.

Third, in this application, "pre-defined" may include pre-defined, for example, protocol definition. Among them, "pre-defined" can be implemented by pre-saving corresponding codes, tables, or other methods that can be used to indicate related information in the device (for example, including STA and AP), and this application does not limit the specific implementation manner.

Fourth, the "saving" referred to in the embodiments of the present application may refer to storing in one or more memories. The one or more memories may be provided separately, or integrated in an encoder or decoder, a processor, or a communication device. The one or more memories may also be partly provided separately, and partly integrated in a decoder, a processor, or a communication device. The type of the memory can be any form of storage medium, which is not limited in this application.

Fifth, the “protocols” involved in the embodiments of this application may refer to standard protocols in the communication field, such as WiFi protocol, new radio (NR) protocol, and related protocols applied to future communication systems. The application is not limited.

Sixth, in order to facilitate understanding, the following briefly describes the main parameters involved in this application:

h _ij : the channel between the antenna of STA#j and the AP-side antenna #i, i and j are positive integers. (This application uses a single-antenna STA as an example for description. The case where the STA includes multiple antennas can be equivalent to a single-line STA as shown in FIG. 2).

AP-side antenna #k receives the information size on the l-th symbol, and k and l are positive integers.

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

The training sequence sent on the Wth symbol in the first training sequence corresponding to STA#q rotates in phase relative to the training sequence sent on the first symbol.

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

Specifically, the uplink multi-site MIMO mainly relies on the multi-antenna orthogonal equalization on the AP side, that is, the AP side uses the training sequence to obtain the link information (for example, channel state information (CSI)) of the air interface, and then equalizes the multi-site The effective load of multiple sites splits the superimposed information of multiple sites, so that each site is orthogonal to each other and does not affect each other. Therefore, whether the wireless channel state information can be accurately obtained, on the one hand, will directly affect the orthogonality of the uplink multi-site, or it is the key to the accuracy of each site to obtain their respective streams; on the other hand, it may also affect the access point during the downlink data transmission. Precoding accuracy. This process of obtaining wireless channel state information may also be referred to as channel estimation.

However, there are different types of user terminals, and the radio frequency links of different user terminals may be different. Therefore, it is difficult for the carrier frequency used by the user terminals to transmit signals to be consistent, that is, it is difficult for different user terminals to achieve frequency synchronization.

First, with reference to Fig. 3, a brief description of the impact of signal frequency unsynchronization sent by multiple user terminals on the estimated channel on the AP side will be explained. FIG. 3 is a schematic diagram of two STAs sending data to an AP according to an embodiment of the present application. Fig. 3 includes two STAs (STA#1 and STA#2 as shown in Fig. 3) and an AP. Among them, STA#1 and STA#2 can access the network through the AP. For example, STA#1 and STA#2 can be two mobile phones that support WiFi communication, the AP can be a router with a WiFi chip, and the AP has two antennas (antenna #1 and antenna #2 shown in Figure 3). ).

As a possible implementation, there is no frequency difference between STA#1 and STA#2 and AP, that is, there is no carrier frequency offset (CFO), then the two positive signals sent by STA#1 and STA#2 There will be no phase rotation for the intersecting symbol, and the CFO is referred to as the frequency offset value in the following.

For example, the data sent by STA#1 is

Then through the spatial channels h ₁₁ and h ₂₁ , they reach antenna #1 and antenna #2 on the AP side respectively; the data sent by STA#2 is

Then, through the spatial channels h ₁₂ and h ₂₂ , they reach antenna #1 and antenna #2 on the AP side, respectively. The information received by antenna #1 and antenna #2 on the AP side is the superimposed signal of the two STAs after passing through the air interface channel. Specifically, the information received by antenna #1 includes

with

in,

The information received by antenna #2 includes

with

in,

Specifically, the data sent by the STA involved in the embodiments of this application can be understood as a training sequence corresponding to a long training field (LTF) sent by the STA on a certain subcarrier. The data can be understood as a signal or information, and the LTF includes In the PPDU sent by the STA to the AP, taking 802.11ax as an example, the LTF may be HE-LTF, and the specific frame format of the PPDU containing the HE-LTF may be as follows:

Among them, L-STF means non-High throughput short training field, L-LTF means non-High throughput long training field, L-SIG means non-High throughput signal Field (non-High throughput signal field), RL-SIG means repetition non-High throughput signal field (repetition non-High throughput signal field), HE-SIG-A means high efficiency signal field A (High efficiency signal field A), HE- SIG-B means High efficiency signal field B, HE-STF means High efficiency short training field (HE-STF), HE-LTF means High efficiency long training field (high-efficiency long) Training field (HE-STF), Data represents a data field, and PE represents a package extension field (package extension field).

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

Among them, L-STF stands for non-high-throughput short training field, L-LTF stands for non-high-throughput long training field, L-SIG stands for non-high-throughput signal field, RL-SIG stands for repeated non-high-throughput signal field, general signaling field ( The universal signal field (U-SIG) and the extremely High throughput signal field (EHT-SIG) are used to carry the signaling used to demodulate subsequent data, and the extremely high throughput short training sequence (extremely High Throughput short training field, EHT-STF) is used for automatic gain control of subsequent fields, eExtremely High throughput long training field (EHT-LTF) is used for channel estimation, Data represents data field, PE represents Packet extension field.

The AP side only needs to _{solve for the received information h 11} , h ₂₁ , h ₁₂ and h _{22 to} obtain the CSI. The above process can be expressed in a matrix way, which is more conducive to understanding. The information matrix received at the AP is expressed as the following formula:

The AP side knows that the training sequences sent by STA#1 and STA#2 are X ₁ =[1 -1] and X ₂ =[1 1], respectively. Based on the training sequence, the AP can learn the matrix in the above formula

This matrix is called the P matrix in the current agreement. Therefore, the AP side only needs to perform the following operations on the received information matrix to obtain the channel matrix:

As another possible implementation manner, STA#1 and STA#2 have their respective frequency offsets with the AP. For example, the frequency offset of STA#1 relative to the AP is Δf ₁ , and the frequency offset of STA#2 relative to the AP is Δf ₂ . When STA1 and STA2 send data on two consecutive orthogonal symbols, the data will rotate in phase. Assuming that the period of each symbol is T, that is, the data sent by STA#1 on the second symbol is relative to that of STA#1. The phase of the data sent on the first symbol is rotated

In the same way, the data sent by STA#2 on the second symbol is rotated relative to the data sent by STA#2 on the first symbol.

Then the data sent by STA#1 is

The data sent by STA#2 is

The information matrix received at the AP is expressed as the following formula:

For the AP side, the default P matrix corresponding to the data sent by the two STAs is

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

It can be found that the channel matrix determined by the AP is that the channel of one of the two STAs is doped with the channel of the other STA, and crosstalk has occurred. From the above calculation process, it can be seen that this is due to the presence of frequency offset. In this case, the corresponding P _fix matrix is non-orthogonal, that is to say, if the AP side can learn the frequency offset information of the STA, the known P matrix on the AP side can be compensated or corrected so that the P matrix is not the above

But consider the P _fix matrix after frequency offset information

Then the AP performs inversion based on the matrix P _fix to obtain the channel information, and the AP can obtain accurate channel information.

As explained in detail above in conjunction with Figure 3, when there is a frequency offset between the STA and the AP, the AP cannot accurately obtain the channel information between the STA and the AP based on the original P matrix. In order to obtain accurate channel information, the P must first be obtained. _fix matrix, and _{the key to obtaining the P fix} matrix is to know the frequency offset value between the STA and the AP, and the P _fix matrix can be obtained by correcting or compensating the P matrix based on the frequency offset value.

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

Optionally, let the same STA send two identical data on two symbols, so that when the AP side receives the information corresponding to the two data, it only needs to compare the information corresponding to the two data in the two symbols. The frequency offset value between STA and AP can be obtained by changing.

For example, as shown in FIG. 4, FIG. 4 is a schematic diagram of a single-antenna STA transmitting data according to an embodiment of the present application. The data sent by STA#1 on the two symbols should be X ₁ =[1 1]. Since the frequency offset value between STA and AP is Δf ₁ , it is equivalent to the data sent by STA#1 on the two symbols. for

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

AP divides the received information matrix to find the angle, or conjugate to find the angle, then the relative rotation angle 2πΔf ₁ T of the two data can be obtained, and then the frequency offset value Δf _{1 of} STA#1 and AP can be calculated.

However, because the information matrix received by the AP side is the superposition of data sent by multiple STAs when sending data from multiple STAs in the uplink, the information cannot be distinguished, even if each STA sends repeated data on two symbols, because the AP side The information on the two received symbols is the superposition of multiple STA data, so the frequency offset value between each STA relative to the AP cannot be accurately estimated by the above-mentioned point division method.

Optionally, it can be considered that within the measured WiFi bandwidth, the channels in consecutive orthogonal blocks of sub-carriers are almost equal, that is, the channels are relatively flat channels. Different orthogonal sequences are assigned to the subcarriers sent by each STA, so that the AP side can unpack the channel information of each STA, and then obtain the phase rotation angle between symbols.

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

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

Because the subcarriers sent by each STA are allocated orthogonal sequences, so:

Taking antenna #1 as an example on the AP side, the information received by each subcarrier of the first symbol can be expressed as:

Since the premise is that the channels in consecutive orthogonal blocks of sub-carriers are almost equal, so

By analogy with each orthogonal block, there are 234 effective sub-carriers in 802.11ax, and it is necessary to ensure that the continuous sub-carriers are flat. Under the above prerequisites, orthogonalize the received signals. Taking the signal of orthogonal STA#2 as an example, orthogonalize the signals received by AP side antenna #1 on each subcarrier of the first symbol Sum

due to

so

The signal of STA#2 can be eliminated, leaving only the information of STA#1, namely:

In the same way, for the second symbol, the AP side can perform the same processing as described above to obtain:

joint

with

_{2πΔf 1} T can be calculated.

However, the above-mentioned prerequisites that the channels in consecutive orthogonal sub-carrier blocks are almost equal are relatively harsh conditions, which are difficult to meet in reality, which results in the difficulty of guaranteeing the accuracy of channel estimation by the AP.

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

It should be understood that the method provided in the embodiment of the present application can be applied to a WLAN communication system, for example, the communication system 100 shown in FIG. 1. The communication system may include at least one AP and multiple STAs. The frequency offsets between the multiple STAs and the AP are inconsistent.

In the embodiments of the present application, a single-antenna STA is taken as an example for description, that is, an AP is associated with multiple single-antenna STAs. When a certain STA includes multiple antennas, the frequency offset between each antenna of the STA and the antenna of the AP is the same, so the calculation method of the channel information between the other antennas of the STA and the antenna of the AP can be referred to The calculation method of the channel information between a certain antenna in the STA and the antenna of the AP involved in the embodiment of the present application is not repeated in this application for the case where a certain STA includes multiple antennas.

It should also be understood that the method for frequency offset estimation provided by the embodiments of the present application can also be applied in a scenario of multiple APs. For example, the system of the WLAN deployment scenario shown in FIG. 1 also includes another AP. The communication between the AP and the STA is the same as the communication between the AP and the STA shown in FIG. It is estimated that this application will not go into details.

In addition, the data transmission between the STA and the AP can occur over the full bandwidth (for example, a 20M bandwidth, including 256 subcarriers). In the embodiment of the present application, the frequency offset estimation between the STA and the AP on one subcarrier is taken as an example To illustrate, the frequency offset estimation method between the STA and the AP on the other subcarriers is the same, which will not be repeated in this application.

The embodiments shown below do not specifically limit the specific structure of the execution body of the method provided in the embodiments of the application, as long as the program can be run and recorded with the code of the method provided in the embodiments of the application to provide the method according to the embodiments of the application. For example, the execution subject of the method provided in the embodiment of the present application may be an AP or STA, or a functional module in the AP or STA that can call and execute the program.

In the following, without loss of generality, the interaction between the AP and the STA is taken as an example to describe in detail the method for frequency offset estimation provided in the embodiment of the present application.

FIG. 6 is a schematic flowchart of a method for frequency offset estimation provided by an embodiment of the present application. The executive body includes AP and STA.

For ease of understanding, only one STA is shown in FIG. 6. Actually, there are multiple STAs associated with the AP shown in FIG. 6 in the embodiment of this application. Not all STAs are shown in FIG. 6 because multiple APs are associated The steps performed by the STAs are the same. For the specific steps performed by other STAs not shown, reference may be made to the STA shown in FIG. 6, which will not be described 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 of spatial streams M corresponding to the STA that needs to report the first training sequence and the second training sequence, and the first subcarrier occupied by the STA receiving the first information to report the first training sequence or the second training sequence Subset. Wherein, the first training sequence and the second training sequence are used to estimate the frequency offset value between the AP and the STA, and the first sub-carrier subset is the sub-carrier sub-carriers corresponding to the STA in the S preset sub-carrier subsets set.

The number M of spatial streams corresponding to the aforementioned STA refers to the sum of the number of antennas M 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 based on a single antenna. STA is explained as an example (as shown in Figure 2(b), a multi-antenna STA can be equivalent to a single-antenna STA). In this case, the number of spatial streams M corresponding to the STA can also be referred to as the number of STAs M, that is, the number of STAs. The number of streams is equal to the number of STAs that need to report the first training sequence and the second training sequence, and the number of STAs can be replaced with the number of spatial streams in the following.

It should be understood that the first training sequence and the second training sequence involved in the embodiments of this application are the same training sequence, but they occupy different positions in the physical protocol date unit (PPDU) sent by the STA to the AP. , The information included in the first training sequence and the second training sequence is the same, so how the STA generates the first training sequence can be explained from the perspective of the first training sequence below. The foregoing M and S are positive integers, and M and S are used to determine the first training sequence. How to determine the first training sequence based on M and S will be described below, which is not described here.

The above-mentioned first training sequence may also be called frequency offset estimation training sequence, long training field (long training field, LTF), extremely high throughput-LTF (extremely high throughput LTF, EHT-LTF), or frequency offset training sequence, etc. In the embodiment of the present application, the name of the training sequence used to estimate the frequency offset value is not limited.

It should be noted that, in order to facilitate the description of the method for frequency offset estimation provided by the embodiment of this application from the perspective of one STA in the embodiment shown in FIG. 6, the above-mentioned STA is any of the multiple STAs associated with the AP. one.

Exemplarily, the first information may be used to indicate that multiple STAs associated with the AP report the subset of subcarriers occupied by the first training sequence or the second training sequence; or,

Exemplarily, the AP may send multiple pieces of information to multiple STAs associated with the AP, and the multiple pieces of information respectively indicate the number of STAs that need to report the first training sequence and the second training sequence, and the STA receiving the information reports the first training. The subset of subcarriers occupied by the sequence or the second training sequence.

In another implementation manner, the above-mentioned first information may indicate the number of symbols required by the STA to report the first training sequence, and the number of symbols may be used to determine the dimension of the P matrix, and the P matrix is used to determine the first training sequence. .

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

It should be noted that the number of symbols J, the total number of subcarrier subsets S, and the total number M of STAs that need to report the frequency offset estimation training sequence in the embodiment of this application can be derived from each other, that is to say, J, S, and M are three. Knowing two of the parameters from the parameters can determine the other parameter. The specific determination process can be table lookup or calculation, which is not limited in this application.

That is to say, when the protocol is predefined or the AP instructs the STA to report the number of symbols required for the first training sequence, the number S of the aforementioned subcarrier subsets may not be predefined by the protocol. In the embodiment of this application, the number S of subcarrier subsets is known as an example. When the number of symbols J required to report the first training sequence is known, it is similar to the number S of subcarrier subsets, the difference is that One is to derive J from S, and the other is to directly indicate that J can be obtained without deriving J, which will not be repeated in this application.

In the embodiments of this application, the division of sub-carrier subsets can be pre-defined by the protocol, or negotiated between the STA and the AP, or notified to each STA through signaling after the AP determines it, or it can also be one of the STAs. After inter-negotiation is determined and the result is reported to the AP through signaling, it should be understood that the manner in which all subcarriers are divided to obtain at least one subcarrier subset is not limited in the embodiment of the present application.

For example, the protocol predefines that all sub-carriers (K) are divided into S sub-carrier subsets. There is no intersection between the S sub-carrier subsets. The sub-carriers occupied by each sub-carrier subset can be continuous or Is non-continuous, where K is a positive integer and S is a positive integer.

Exemplarily, if the subcarriers in the subcarrier subset are continuous, the subcarriers included in the above S subcarrier subsets may be:

Sub-carrier subset #1 includes sub-carriers {1,2,3,..., K/S}, and sub-carrier subset #2 includes sub-carriers {K/S+1, K/S+2, K/S+3 ,..., 2K/S},..., subcarrier subset #S includes subcarriers {KK/S+1,KK/S+2,KK/S+3,...,K}. As shown in FIG. 7(a), FIG. 7 is a schematic diagram of dividing a subset of subcarriers according to an embodiment of the present application.

Exemplarily, if the subcarriers in the subcarrier subset are non-contiguous, the subcarriers included in the above S subcarrier subsets may be:

Sub-carrier subset #1 includes sub-carrier {1,K/

S+

1,2K/S+1,...,KK/S+1}, and sub-carrier subset #2 includes sub-carrier {2,K/

S+

2 ,2K/S+2,...,KK/S+2},..., sub-carrier subset #S includes sub-carrier {K/S, 2K/S, 2K/S+3,..., K}. As shown in Figure 7(b).

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

For example, all subcarriers scheduled currently include K subcarriers, and all subcarriers scheduled next time are 2K subcarriers. The embodiment of this application mainly estimates the frequency offset value between the STA and the AP in a certain scheduling process. For other scheduling processes that need to estimate the frequency offset value, you can refer to the solution for estimating the frequency offset value provided in the embodiment of this application. In the embodiments of the present application, the frequency offset estimation schemes in different scheduling procedures will not be described in detail.

As a possible implementation, the foregoing first information includes first indication information and second indication information, where the first indication information is used to indicate the number of STAs that need to report the first training sequence and the second training sequence. M, 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 successively. In the embodiment of this application, the first indication information The sequence of sending the second instruction information to the STA is not limited.

As a possible implementation manner, the above-mentioned first information is a trigger frame (TF) specified in the existing protocol or the next-generation standard protocol, and the trigger frame is used to trigger the STA to report the PPDU. In the embodiment of the present application, the frame format of the trigger frame specified in the 802.11ax protocol is taken as an example for description. Q bits can be added to the common information field of the trigger frame. 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, where Q is 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 a general information field of a trigger frame provided in an embodiment of the present application.

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

Trigger type (trigger type), uplink length (uplink length, UL length), more trigger frames (more trigger frame, more TF), carrier sense required (CS required), uplink bandwidth (uplink bandwidth, UL BW), guard interval and long training field type (guard interval and long training field type, GI and LTF type), MU-MIMO long training field type (MU-MIMO LTF mode), efficient long training field symbol number and intermediate training sequence Number of cycles (number of HE-LTF symbols and mid-amble periodicity), uplink space time block code (UL STBC), low density parity check code extra symbol segment ), access point transmit power (AP TX power), uplink packet extension (UL packet extension), uplink spatial division multiplexing (UL spatial reues), Doppler (Doppler), uplink high-efficiency model field A2 part reserved field ( UL HE-SIG-A2reserved), reserved fields (reserved), trigger dependent common information (trigger dependent common information).

The specific meaning of each field of the trigger frame involved in the embodiments of the present application can refer to the provisions in the existing protocol and the next-generation standard protocol, for example, the provisions in the 802.11ax or 802.11be standards, which will not be repeated in this application. The general information field in the trigger frame involved in the embodiment of this application is different from the general information field of the trigger frame specified in the existing protocol and the next-generation standard protocol in that the reserved bit field of the general information field and the general information related to the trigger type The first indication information is added between the fields, and the first indication information may occupy at least one bit.

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

As another possible implementation manner, the above-mentioned first information is a trigger frame specified in the existing protocol or the next-generation standard protocol, and the first indication information may be a newly added field in the trigger frame, rather than being limited to a trigger frame. For the newly added fields in the general information field in the example of the application, there is no limitation on where the first indication information is located in the trigger frame. It is only necessary to carry the first indication information in the trigger frame and send it to the AP. The associated STA is sufficient.

As yet another possible implementation manner, the above-mentioned first information is a trigger frame specified in the existing protocol or the next-generation standard protocol, and the first indication information can be multiplexed with fields reserved in the trigger frame (for example, as shown in FIG. 8 reserved field), in this implementation mode, signaling overhead can be saved.

As yet another possible implementation manner, the above-mentioned first information is a trigger frame specified in the existing protocol or the next-generation standard protocol. The first indication information may partially reuse the reserved fields in the trigger frame, and the other part may be used as the trigger frame in the trigger frame. Newly added fields (for example, when the reserved fields are not enough).

It should be understood that the foregoing first indication information carried in the trigger frame is only an example, and does not constitute any limitation to the protection scope of the present application. For example, the above-mentioned first indication information may be carried in newly-added signaling between AP and STA and sent to STA; or, the above-mentioned first indication information may be carried in other existing signaling between AP and STA. , Sent to STA.

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

Further, when the first information is a trigger frame specified in the existing protocol or the next-generation standard protocol, the scheduling information field included in the trigger frame may be used to indicate the first sub-carrier subset, that is, the second sub-carrier subset mentioned above. The indication information can multiplex the scheduling information field in the trigger frame to realize the function of indicating the first subcarrier subset. The following describes in detail how to multiplex the scheduling information field to indicate the first subcarrier subset with reference to FIG. 9.

FIG. 9 is a schematic diagram of indirectly indicating a subset of subcarriers according to an embodiment of the present application. From Figure 9 (a) includes:

Media access control header (MAC header) information, STA scheduling information sorting, padding, and frame check sequence (FCS). Among them, MAC header information includes frame control (frame control), duration (duration), receiver address (reserve address, RA), transmitter address (transmit address, TA), common information (common information); STA scheduling information order Including the scheduling information of at least one user (user information). The scheduling information of the at least one user is arranged in a certain order in the STA scheduling information field. Therefore, the scheduling information of each STA can be sequentially arranged in the order of the scheduling information corresponding to multiple STAs in the trigger frame. Each STA corresponds to each sub-carrier subset. When all the sub-carrier subsets are filled, the remaining STAs are re-arranged from the first sub-carrier subset. The final emission effect is shown in Figure 9 (b). The arrangement process can be expressed as:

Assuming that there are a total of M STAs (STA#1～STA#M shown in Figure 9(b)) need to send frequency offset estimation training sequences to the AP, and all the subcarriers scheduled this time are divided into S subcarrier subsets. . Then the i-th STA needs to send a frequency offset estimation training sequence on the mod(i-1, S)+1th subcarrier subset, where mod represents a modulo operation. It can be seen from Figure 9(b) that the first mod(i-1, S)+1 sub-carrier subsets all carry

STA, in order to be able to

STAs are distinguished from each other, and the STA needs to multiply by

Dimensional P matrix, corresponding to a frequency offset estimation training sequence needs

Symbols, and the remaining sub-carrier subsets carry

STA, in order to be able to

STAs are distinguished from each other, and the STA needs to multiply by

Symbols.

It should be noted that the multiplexing scheduling information field shown in FIG. 9 indicating the first subcarrier subset is only an example, and does not constitute any limitation to the protection scope of the present application.

As a possible implementation, the above-mentioned second indication information is a newly added field in the trigger frame to indicate the first sub-carrier subset, or the above-mentioned second indication information multiplexes the reserved field in the trigger frame to indicate the first sub-carrier subset. A subset of subcarriers.

It should be understood that the foregoing second indication information carried in the trigger frame is only an example, and does not constitute any limitation to the protection scope of the present application. For example, the above-mentioned second indication information may be carried in newly-added signaling between AP and STA and sent to STA; or, the above-mentioned second indication information may be carried in other existing signaling between AP and STA. , Sent to STA.

Further, after receiving the above-mentioned first information, the STA may generate a first training sequence based on the first information. That is, the method flow shown in FIG. 6 further includes S620, where the STA generates a first training sequence.

First, the STA determines that there are M STAs under the current schedule that need to send the first training sequence and the second training sequence to the AP based on the first indication information (for example, a newly added field in the general information field of the trigger frame).

Secondly, the STA determines the first subcarrier subset (e.g., subcarrier subset#j) corresponding to the STA based on the second indication information (e.g., the position of the STA in the scheduling information field is STA#i), Furthermore, the number of symbols required to transmit the first training sequence and the number of STAs (M _j ) carried on the first subcarrier subset can be determined, and the number of STAs carried on the first subcarrier subset can be determined. STA(R _i ).

_{Wherein, the number M j} of STAs carried on the first subcarrier subset is used to determine the dimension of the P matrix. The P matrix is an M _j -dimensional square matrix. The ordering determines the number of rows of the STA multiplied by the P matrix to generate the first training sequence.

Taking the first information as the trigger frame, and the second indication information multiplexing the scheduling information in the trigger frame as an example, the process of the STA generating the first training sequence is illustrated:

step one:

The STA determines to generate the first training 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 its own rank i in the scheduling information field in the trigger frame. The related information required by the sequence is shown in FIG. 10. FIG. 10 is a schematic diagram of determining related information for the first training sequence provided by an embodiment of the present application. It can be seen from FIG. 10 that the related information includes the following information:

1. The number of symbols required to send the first training sequence

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

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

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

It should be noted that FIG. 10 takes the first indication information indicating the number M of STAs as an example to illustrate the case where the STA generates the first training sequence, and the first indication information indicates the number J of symbols required by the STA to report the first training sequence. Next, the STA can determine the relevant information required to generate the first training sequence based on the number of symbols J and its own ranking i in the scheduling information field in the trigger frame:

1. The number of symbols required to send the first training sequence

Among them, M can be determined by J and S;

Step two:

Based on the relevant information obtained in step 1, the STA generates the first training sequence that needs to be sent to the AP. The first training sequence sent by the STA on the subcarrier subset #j is shown in FIG. 11, which is a schematic diagram of a first training sequence provided by an embodiment of the present application. It can be seen from Figure 11 that the preset data is multiplied by _{the R i} _{row of the M j} -dimensional P matrix. In particular, when

When, 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, a possible implementation is that the preamble sequence, the channel estimation training sequence, and the data symbol portion can be generated in accordance with the provisions of the existing protocol or the next-generation standard protocol. In this application, how to The generation of the preamble sequence, the channel estimation training sequence, and the part of the data symbol are not limited. The generation can be completed according to the generation method in the existing protocol or the next-generation standard protocol, or it can also be completed based on the generation method specified in the future agreement.

After the frequency offset estimation training sequence, the preamble sequence, the channel estimation training sequence, and the data symbol portion are generated, the STA can obtain the PPDU that needs to be sent to the AP. That is, the method flow shown in FIG. 6 also includes S630, where the STA sends a PPDU to the AP.

In the embodiment of the application, the PPDU needs to include at least two training sequences (e.g., the first training sequence and the second training sequence), and may also include more than two training sequences (e.g., in addition to the above-mentioned first training sequence and the first training sequence). In addition to the second training sequence, it also includes a third training sequence, a fourth training sequence, etc., where the first training sequence, the second training sequence, the third training sequence, and the fourth training sequence are the same training sequence). Two training sequences are included in the PPDU as an example. When the PPDU includes more than two training sequences, it is similar to the case where the PPDU includes two training sequences, which will not be repeated in this application.

It should be noted that the above-mentioned physical protocol data unit (physical protocol date unit, PPDU) can be understood as the uplink transmission PPDU (uplink transport block PPDU, UL TB PPDU) that is reported to the AP by the STA specified in the protocol, which can also be referred to as Physical frame, the name of the frame carrying the first training sequence and the second training sequence reported by the STA to the AP in the embodiment of the present application is not limited.

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

A possible implementation manner, the first training sequence, the second training sequence, and the channel estimation training sequence are arranged alternately in the PPDU:

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 symbols.

Exemplarily, as can be seen from (a) in FIG. 12, the above-mentioned frequency offset estimation training sequence includes two (for example, the first training sequence and the second training sequence shown in (a) in FIG. 12), And the two frequency offset estimation training sequences can be respectively placed before and after the channel estimation training sequence;

For another 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, where the first channel The estimated training sequence and the second channel estimation training sequence constitute a channel estimation training sequence.

Exemplarily, as can be seen from (b) in FIG. 12, the above-mentioned frequency offset estimation training sequence includes two (for example, the first training sequence and the second training sequence shown in (a) in FIG. 12), And the two frequency offset estimation training sequences can be respectively placed before and after the partial channel estimation training sequences.

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.

Exemplarily, as can be seen from (c) in FIG. 12, the above-mentioned frequency offset estimation training sequence includes two (for example, the first training sequence and the second training sequence shown in (a) in FIG. 12), And the two frequency offset estimation training sequences can be placed in front of the channel estimation training sequence;

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

Exemplarily, as can be seen from (d) in FIG. 12, the above-mentioned frequency offset estimation training sequence includes two (for example, the first training sequence and the second training sequence shown in (a) in FIG. 12), And the two frequency offset estimation training sequences can be respectively placed behind the channel estimation training sequence.

It should be understood that the format of the PPDU shown in (a)-(d) in Figure 12 is just an example and does not constitute any limitation to the protection scope of this application. The arrangement of the first training sequence and the second training sequence in the PPDU is also It can be in other forms, and the PPDU can also include more than two frequency offset estimation training sequences, which will not be repeated here. When the PPDU format is shown in Figure 12(a), the transmission interference is minimal.

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

Further, after the AP receives the PPDU, it can implement frequency offset estimation based on the two frequency offset estimation training sequences in the PPDU, that is, the method process shown in FIG. 6 also includes S640, where the AP performs frequency offset estimation.

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

Further, consider the frequency offset value between the STA and the AP. Assume that the frequency offset values between _{M j STAs and AP are respectively}

The frequency offset estimation training sequence sent by each STA in M _j STAs will be due to the frequency offset. The frequency offset estimation training sequence sent on each symbol after the first symbol is relative to the frequency offset estimation sent on the first symbol The training sequence will generate phase rotation accumulation, so the frequency offset estimation training sequence sent on a certain symbol Q has a phase rotation angle of j2πΔf(Q-1)T relative to the frequency offset estimation training sequence sent on the first symbol. In the presence of frequency offset, the first information matrix corresponding to the first frequency offset estimation training sequence received by each antenna of the AP can be expressed as:

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

Among them, D is the number of symbols in the channel estimation training sequence. The first information matrix corresponding to the first frequency offset estimation training sequence received (i.e. formula (1-2)) is left multiplied by the second information matrix corresponding to the second frequency offset estimation training sequence (i.e. formula (1-2)) (1-3) on), you can get:

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 second information matrix corresponding to the second frequency offset estimation training sequence has standard characteristics Value decomposition properties, using eigenvalue decomposition to solve the eigenvalues:

Based on the above eigenvalues, the frequency offset values between the _{M j STAs and the AP are calculated}

The solution process in the case of the PPDU format shown in FIG. 12(b)-FIG. 12(d) is similar to the solution process of the frequency offset value in the case of the PPDU format shown in FIG. 12(a), and will not be repeated here.

It should be noted that in the embodiments of the application, the content corresponding to the frequency offset estimation training sequence received by the AP is referred to as an information matrix, which is just an example, and does not constitute any limitation to the protection scope of the application. For example, it can also be referred to as a signal matrix. , Frequency offset estimation training sequence information, etc.

Further, the PPDU in the embodiment of the present application may also include an automatic gain control training sequence. This automatic gain control training sequence can generally be called a short training field (STF). For example, in the 802.11ax protocol, in addition to the L-STF and HE-STF specified in the current protocol, it also adds a similar HE- STF field, this newly added field can be called automatic gain control training sequence; for example, in 802.11be protocol or future WiFi protocol, in addition to the extremely high throughput (STF) specified in the current protocol, In addition to EHT-STF), a field similar to EHT-STF is also added, and this newly added field can be called an automatic gain control training sequence. In the embodiment of the present application, the automatic gain control training sequence is used to control the receiver amplifier gear control when the AP receives the frequency offset estimation training sequence (for example, when the AP receives the first training sequence and/or the second training sequence), As shown in Figure 12(e).

It should be noted that the reason for joining the automatic gain control training sequence is that the subcarriers occupied by the STA when sending the frequency offset estimation training sequence and other parts (such as the preamble sequence, the channel estimation training sequence and the data symbols) are different. Due to the frequency selectivity of the channel, the total received signal strength of the AP may change relative to other parts. In order to enhance the receiving performance, it is necessary to adjust the receiver amplifier gear.

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

In order to facilitate the understanding of the method for frequency offset estimation provided by the embodiment of the present application, a specific example is used for description below.

It is assumed that the method for frequency offset estimation provided by the embodiment of this application is applied to the scenario shown in FIG. 13, and an AP is associated with 3 STAs (STA#1, STA#2, and STA#3 as shown in FIG. 13) , Each STA is a single-antenna STA.

The frequency offsets of the three STAs relative to the AP are Δf ₁ , Δf ₂ , and Δf _{3 respectively} . The entire frequency band scheduled this time is divided into 2 sub-carrier 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:

step one:

The AP sends a trigger frame to notify all STAs that they are ready to send PPDUs. The trigger frame includes first indication information and scheduling information. The first indication information indicates that there are 3 STAs in the scenario shown in Figure 13 to send frequency offset estimation training sequences, The order of the scheduling information field of the STA in the trigger frame is STA#1, STA#2, and STA#3.

Step two:

After receiving the trigger frame, STA#1 constructs a frequency offset estimation training sequence. STA#1 learned that one of the two frequency offset estimation training sequences contains

Symbols; and learned 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 subcarrier subset# The first STA on 1. Therefore, the first frequency offset estimation training sequence sent by STA#1 on the two symbols is the preset data multiplied by the two-dimensional P matrix.

Multiply the two values in the first row in [1,-1]. That is to say, the first symbol in the first frequency offset estimation training sequence is the preset data multiplied by 1, and the second symbol is the preset data multiplied by -1. Figure 14 shows the first line of physical frames sent by STA#1. Figure 14 is a schematic diagram of PPDUs sent by multiple STAs received by an AP.

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

Multiply the two values in the second row of [1,1] by [1,1]. That is to say, the first symbol in the first frequency offset estimation training sequence is the preset data multiplied by 1, and the second symbol is the preset data multiplied by 1. As shown in Figure 14, the second line is the PPDU sent by STA#3;

After receiving the trigger frame, STA#2 constructs a frequency offset estimation training sequence. STA#2 learns that one of the two frequency offset estimation training sequences contains 2 symbols; and learns that STA#2 needs to occupy subcarrier subset #2, and that there is one on this subcarrier subset #2 STA (STA#2), STA#2 is the first STA on the subcarrier subset #2. Therefore, the first frequency offset estimation training sequence sent by STA#2 on two symbols is the preset data multiplied by the value of the first row in the one-dimensional P matrix [1], that is, multiplied by [1,1]. That is to say, the first symbol in the first frequency offset estimation training sequence is the preset data multiplied by 1, and the second symbol is the preset data multiplied by 1. As shown in FIG. 14, the third line is the PPDU sent by STA#3.

Step three:

STA#1, STA#2, and STA#3 respectively send two repetitive frequency offset estimation training sequences that they have formed to the AP.

Step 4:

On subcarrier subset #1, the information matrix received by AP’s antenna #1 is the sum of STA#1’s data experience channel h ₁₁ and STA#3’s data experience channel h _13. AP’s antenna #2 received information is the STA # data subjected to channel h data subjected to channel 1 ₂₁ and the STA # 3 h of information ₂₃ two partial data and, AP antenna # 3 is received is the STA # data subjected to channel h 1 to ₃₁ and The data of STA#3 undergoes the sum of two parts of data of _{channel h 33.}

For the frequency offset estimation training sequence sent on each symbol, because each STA has a different frequency offset relative to the AP, the second symbol of STA#1 should be -1 sent on the second symbol, but due to the phase rotation, it becomes

The following symbols can be deduced by analogy. Similarly, the second symbol sent on STA#3 should be 1, but due to phase rotation, it becomes

The following symbols can be deduced by analogy.

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

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

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

Using the eigenvalue decomposition theorem, the eigenvalue can be obtained

Find the angle of its characteristic value and divide by the corresponding coefficient to get Δf ₁ and Δf ₃ .

On subcarrier subset #2, the information received by AP antenna #1 is that the data of STA#2 has experienced the data of channel h ₁₂ , and the information received by AP antenna #2 is that the data of STA #2 has experienced the data of channel h ₂₂ . data. 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:

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

available

Take the complex angle and divide by the corresponding coefficient to get Δf ₂ .

In addition, the first information matrix corresponding to the first frequency offset estimation training sequence can also be obtained by pseudo-inverse multiplication by the second information matrix corresponding to the second frequency offset estimation training sequence to obtain Δf ₂ , the calculation method is as follows:

The calculation needs to ignore the second column of the first information matrix corresponding to the first frequency offset estimation training sequence, and the second column of the second information matrix corresponding to the second frequency offset estimation training sequence; that is, use the first The first column of the first information matrix corresponding to the frequency offset estimation training sequence is left-multiplied by the pseudo-inverse of the first column of the second information matrix corresponding to the second frequency offset estimation training sequence to obtain:

available

It should be understood that the AP and/or STA in the foregoing 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 should also be understood that, in the various embodiments of the present application, if there is no special description and logical conflicts, the terms and/or descriptions between different embodiments can be consistent and can be mutually cited. The technologies in different embodiments Features can be combined to form new embodiments according to their inherent logical relationships.

It should also be understood that, in the foregoing method embodiments, the size of the sequence numbers of the foregoing processes does not mean the order of execution, and the execution order of the processes should be determined by their functions and internal logic, and should not correspond to the implementation process of the embodiments of this application. Constitute any limitation.

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 device for frequency offset estimation provided by the embodiment of the present application is described in detail below with reference to FIG. 15-18.

Refer to FIG. 15, which is a schematic diagram of the apparatus 150 for frequency offset estimation proposed in the present application. As shown in FIG. 15, the apparatus 1500 includes a receiving unit 1510 and a sending unit 1520.

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

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

The sending unit 1520 is 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 the second training sequence, and the first training The sequence and the second training sequence are used to determine the frequency offset value between the station and the AP.

The device 1500 completely corresponds to the STA in the method embodiment, and the device 1500 may be the STA in the method embodiment, or a chip or functional module inside the STA in the method embodiment. The corresponding unit of the device 1500 is used to perform the corresponding steps performed by the STA in the method embodiment shown in FIG. 6.

Wherein, the receiving unit 1510 in the device 1500 executes the steps of the STA receiving in the method embodiment. For example, step S610 of receiving the first information in FIG. 6 is performed.

The sending unit 1520 executes the steps sent by the STA in the method embodiment. For example, perform step S630 of sending a PPDU to the AP in FIG. 6;

The device 150 may further include a processing unit, which executes the steps implemented or processed internally by the STA in the method embodiment. For example, step S620 of generating the first training sequence in FIG. 6 is performed.

The sending unit 1520 and the receiving unit 1510 may constitute a transceiver unit, and have the functions of receiving and sending at the same time. Among them, the processing unit may be a processor. The sending unit 1520 may be a transmitter, and the receiving unit 1510 may be a receiver. The receiver and transmitter can be integrated to form a transceiver.

Refer to FIG. 16, which is a schematic structural diagram of an STA 1600 applicable to an embodiment of the present application. This STA 1600 can be applied to the system shown in Figure 1. For ease of description, FIG. 16 only shows the 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 and output device (corresponding to the sending unit 1520 and the receiving unit 1530 shown in FIG. 15). The processor is used to control the antenna and the input and output device to send and receive signals, the memory is used to store a computer program, and the processor is used to call and run the computer program from the memory to execute the method for frequency offset estimation proposed by this application by the STA. Corresponding process and/or operation. I won't repeat them here.

Those skilled in the art can understand that, for ease of description, FIG. 16 only shows a memory and a processor. 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, etc., which is not limited in the embodiment of the present application.

Referring to FIG. 17, FIG. 17 is a schematic diagram of the 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 sending unit 1720.

The sending unit 1720 is configured to send first information to the station STA, where the first information is used to indicate the number of spatial streams M corresponding to the STA that needs to report the first training sequence and the second training sequence, and the STA reports the first training sequence. The first subcarrier subset occupied by the training sequence or the second training sequence,

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

The number M of spatial streams corresponding to the above STA refers to the sum of the number of antennas M included in at least one STA that needs to report the first training sequence and the second training sequence, and in the embodiment of the present application, a single-antenna STA is taken as an example To illustrate (as shown in Figure 2(b), a multi-antenna STA can be equivalent to a single-antenna STA). In this case, the number of spatial streams M corresponding to the STA can also be referred to as the number of STAs M, that is, the number of spatial streams and The number of STAs that need to report the first training sequence and the second training sequence is equal.

In addition, when the embodiment of this application is also applied to uplink transmission, the above-mentioned first information may be the PPDU sent by the STA to the AP. The first indication information of the number of spatial streams M and the second indication information used to instruct the STA to report the first subcarrier subset occupied by the first training sequence or the second training sequence may be carried in the STA sent to the AP In the signaling field of the PPDU, for example, it is carried in the HE-SIG or EHT-SIG field in the PPDU.

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

The device 1700 completely corresponds to the AP in the method embodiment, and the device 1700 may be the AP in the method embodiment, or a chip or functional module inside the AP in the method embodiment. The corresponding unit of the device 1700 is used to execute the corresponding steps executed by the AP in the method embodiment shown in FIG. 6.

Wherein, the receiving unit 1710 in the device 1700 executes the steps of AP receiving in the method embodiment. For example, step S620 of receiving the PDU sent by the STA in FIG. 6 is performed.

The receiving unit 1720 in the device 1700 executes the steps sent by the AP in the method embodiment. For example, step S610 of sending the first information to the STA in FIG. 6 is performed.

The device 1700 may further include a processing unit that executes steps implemented or processed inside the AP in the method embodiment. For example, step S640 of performing frequency offset estimation in FIG. 6 is performed.

The receiving unit 1710 and the sending unit 1720 may constitute a transceiver unit, and have the functions of receiving and sending at the same time. Among them, the processing unit may be a processor. The sending unit 1720 may be a transmitter. The receiving unit 1710 may be a receiver. The receiver and transmitter can be integrated to form a transceiver.

Referring to FIG. 18, FIG. 18 is a schematic structural diagram of an AP 1800 applicable to an embodiment of the present application, which can be used to implement the function of the AP in the above-mentioned method for frequency offset estimation. It can be a schematic diagram of the AP structure.

AP includes 1810 part and 1820 part. The 1810 part is mainly used for receiving and sending radio frequency signals and the conversion between radio frequency signals and baseband signals; the 1820 part is mainly used for baseband processing and controlling positioning management components. The 1810 part can generally be called a transceiver unit, transceiver, transceiver circuit, or transceiver. The 1820 part is usually the control center of the positioning management component, and may generally be referred to as a processing unit, which is used to control the positioning management component to perform processing operations on the AP side in the foregoing method embodiment.

The transceiver unit of part 1810 may also be called a transceiver or a transceiver, etc., which includes an antenna and a radio frequency unit, and the radio frequency unit is mainly used for radio frequency processing. Optionally, the device used for implementing the receiving function in part 1810 can be regarded as the receiving unit, and the device used for implementing the sending function as the sending unit, that is, the part 1810 includes the receiving unit and the sending unit. The receiving unit may also be called a receiver, a receiver, or a receiving circuit, and the sending unit may be called a transmitter, a transmitter, or a transmitting circuit, etc.

The 1820 part may include one or more single boards, and each single board may include one or more processors and one or more memories. The processor is used to read and execute the program in the memory to realize the baseband processing function and control the positioning management component. If there are multiple boards, each board can be interconnected to enhance processing capabilities. As an optional implementation, multiple single boards may share one or more processors, or multiple single boards may share one or more memories, or multiple single boards may share one or more processing at the same time. Device.

It should be understood that FIG. 18 is only an example and not a limitation, and the above-mentioned AP including the transceiver unit and the processing unit may not depend on the structure shown in FIG. 18.

It should also be understood that the AP 1800 shown in FIG. 18 can implement the AP function involved in the method embodiment of FIG. 6. The operations and/or functions of each unit in the AP1800 are respectively for implementing the corresponding processes executed by the AP in the method embodiment of the present application. In order to avoid repetition, detailed descriptions are appropriately omitted here. The structure of the AP illustrated in FIG. 18 is only a possible form, and should not constitute any limitation in the embodiment of the present application. This application does not exclude the possibility of other AP structures that may appear in the future.

The embodiment of the present application also provides a communication system, which includes the aforementioned STA and AP.

This application also provides a computer-readable storage medium that stores instructions in the computer-readable storage medium. When the instructions run on a computer, the computer executes the steps performed by the STA in the method shown in FIG. 6 .

The present application also provides a computer-readable storage medium that stores instructions in the computer-readable storage medium. When the instructions run on a computer, the computer executes the steps performed by the AP in the method shown in FIG. 6 .

This application also provides a computer program product containing instructions. When the computer program product runs on a computer, the computer executes the steps performed by the STA in the method shown in FIG. 6.

This application also provides a computer program product containing instructions. When the computer program product runs on a computer, the computer executes the steps executed by the AP in the method shown in FIG. 6.

The application also provides a chip including a processor. The processor is used to read and run a computer program stored in the memory to execute the corresponding operation and/or process performed by the STA in the method for frequency offset estimation provided in the present application. Optionally, the chip further includes a memory, the memory and the processor are connected to the memory through a circuit or a wire, and the processor is used to read and execute the computer program in the memory. Further optionally, the chip further includes a communication interface, and the processor is connected to the communication interface. The communication interface is used to receive data and/or information that needs to be processed, and the processor obtains 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. The processor may also be embodied as a processing circuit or a logic circuit.

The application also provides a chip including a processor. The processor is used to read and run the computer program stored in the memory to execute the corresponding operation and/or process executed by the AP in the method for frequency offset estimation provided in the present application. Optionally, the chip further includes a memory, the memory and the processor are connected to the memory through a circuit or a wire, and the processor is used to read and execute the computer program in the memory. Further optionally, the chip further includes a communication interface, and the processor is connected to the communication interface. The communication interface is used to receive data and/or information that needs to be processed, and the processor obtains 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. The processor may also be embodied as a processing circuit or a logic circuit. It should be understood that the aforementioned chip can also be replaced with a chip system, which will not be repeated here. The terms "including" and "having" and any variations of them in this application are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or device that includes a series of steps or units is not necessarily limited to clearly listed Instead, those steps or units listed may include other steps or units that are not clearly listed or are inherent to these processes, methods, products, or equipment.

A person of ordinary skill in the art may realize that the units and algorithm steps of the examples described in combination with the embodiments disclosed herein can be implemented by electronic hardware or a combination of computer software and electronic hardware. Whether these functions are executed by hardware or software depends on the specific application and design constraint conditions of the technical solution. Professionals and technicians can use different methods for each specific application to implement the described functions, but such implementation should not be considered beyond the scope of this application.

Those skilled in the art can clearly understand that, for the convenience and conciseness of description, the specific working process of the system, device and unit described above can refer to the corresponding process in the foregoing method embodiment, which will not be repeated here.

In the several embodiments provided in this application, it should be understood that the disclosed system, device, and method can be implemented in other ways. For example, the device embodiments described above are merely illustrative, for example, the division of the units is only a logical function division, and there may be other divisions in actual implementation, for example, multiple units or components may be combined or It can be integrated into another system, or some features can be ignored or not implemented. In addition, the displayed or discussed mutual coupling or direct coupling or communication connection may be indirect coupling or communication connection through some interfaces, devices or units, and may be in electrical, mechanical or other forms.

The units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the objectives of the solutions of the embodiments.

In addition, the functional units in the various embodiments of the present application may be integrated into one processing unit, or each unit may exist alone physically, or two or more units may be integrated into one unit.

If the function is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer readable storage medium. Based on this understanding, the technical solution of the present application essentially or the part that contributes to the existing technology or the part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including Several instructions are used to make a computer device (which may be a personal computer, a server, or a network device, etc.) execute all or part of the steps of the methods described in the various embodiments of the present application. The aforementioned storage media include: U disk, mobile hard disk, read-only memory (read-only memory, ROM), random access memory (random access memory, RAM), magnetic disk or optical disk and other media that can store program code .

In addition, the term "and/or" in this application is only an association relationship that describes associated objects, which means that there can be three types of relationships, for example, A and/or B, which can mean that A alone exists, and both A and B exist. , There are three cases of B alone. In addition, the character "/" in this document generally means that the associated objects before and after are in an "or" relationship; the term "at least one" in this application can mean "one" and "two or more", for example, A At least one of, B and C can mean: A alone exists, B alone exists, C alone exists, A and B exist alone, A and C exist at the same time, C and B exist at the same time, A and B and C exist at the same time, this Seven situations. In addition, the term "multiply left/multiply right" in this application describes the calculation method between matrices. For example, matrix A is multiplied by matrix B to the left to obtain matrix BA, and matrix A is multiplied by matrix B to the right to obtain matrix AB; in this application, the term "multiplying left by/multiplying right by" describes the calculation method between matrices. For example, matrix A is multiplied by matrix B on the left to obtain matrix AB, and matrix A is multiplied by matrix B on the right to obtain matrix BA.

The above are only specific implementations of this application, but the protection scope of this application is not limited to this. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed in this application. Should be covered within the scope of protection of this application. Therefore, the protection scope of this application should be subject to the protection scope of the claims.

Claims

A method for frequency offset estimation, which is applied to an access point AP communicating with multiple STAs, and is characterized in that it includes:

The AP sends first information to the STA, where the first information is used to indicate the number of spatial streams M corresponding to the STA that needs to report the first training sequence and the second training sequence, and the number of spatial streams M that the STA reports the first training sequence or the first training sequence. The first sub-carrier subset occupied by the second training sequence,

Wherein, the STA is any one of the multiple STAs, the first subcarrier subset is a subcarrier subset corresponding to the STA in S preset subcarrier subsets, and the M and S are A positive integer, used to determine 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, the PPDU includes the first training sequence and the second training sequence, the first training sequence and The second training sequence is used to determine the frequency offset value between the STA and the AP.
The method according to claim 1, wherein the first information comprises:

First indication information and second indication information, where the first indication information is used to indicate the M, and the second indication information is used to determine the first subcarrier subset.
The method according to claim 2, wherein the AP sending the first information to the STA comprises:

The AP sends a trigger frame to the STA, the trigger frame is used to trigger the STA to report the PPDU, wherein the trigger frame carries the first indication information and the second indication information, and the first The indication information is the scheduling information field.
The method according to claim 3, wherein the carrying of the first indication information in the trigger frame comprises:

The trigger frame includes a general information field, and the general information field includes the first indication information.
The method according to any one of claims 1 to 4, wherein the first training sequence or the second training sequence is determined by a mapping relationship between the STA and P matrix elements.
The method according to any one of claims 1-5, wherein the method further comprises:

The AP receives 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 AP ；

The AP receives a second information matrix on the first subset of subcarriers, the second information matrix being determined by the second training sequence and channel information, and the 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.
The method according to any one of claims 1-6, 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 in The PPDUs are arranged one after another in sequence, or alternately arranged at intervals.
The method according to any one of claims 1-7, wherein the PPDU further comprises an automatic gain control training sequence, and the automatic gain control training sequence is used by the AP to adjust the first subcarrier. The received power of the first training sequence and/or the second training sequence is received on a subset.
A method for frequency offset estimation, which is applied to any one STA among multiple station STAs communicating with an access point AP, and is characterized in that it includes:

The STA receives first information from the AP, and the first information is used to indicate the number of spatial streams M corresponding to the STA that needs to report the first training sequence and the second training sequence, and the STA reports the first training Sequence or the first sub-carrier subset occupied by the second training sequence;

Wherein, the first subcarrier subset is the subcarrier subset corresponding to the STA in the S preset subcarrier subset, and the M and S are positive integers, and are used to determine the first training sequence or the The second training sequence;

The STA sends a physical layer protocol data unit PPDU to the AP on the first subcarrier subset, and the PPDU includes the first training sequence and the second training sequence, and the first training sequence and the second training sequence are included in the PPDU. The second training sequence is used to determine the frequency offset value between the STA and the AP.
The method according to claim 9, wherein the first information comprises:

First indication information and second indication information, where the first indication information is used to indicate the M, and the second indication information is used to determine the first subcarrier subset.
The method according to claim 10, wherein the STA receiving the first information from the AP comprises:

The STA receives a trigger frame from the AP, the trigger frame is used to trigger the STA to report the PPDU, wherein the trigger frame carries the first indication information and the second indication information, and the first One indication information is the scheduling information field.
The method according to claim 11, wherein the carrying of the first indication information in the trigger frame comprises:

The trigger frame includes a general information field, and the general information field includes the first indication information.
The method according to any one of claims 9-12, wherein the first training sequence or the second training sequence is determined by a mapping relationship between the STA and P matrix elements.
The method according to any one of claims 9-13, 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 in The PPDUs are arranged one after another in sequence, or alternately arranged at intervals.
The method according to any one of claims 9-14, wherein the PPDU further comprises an automatic gain control training sequence, and the automatic gain control training sequence is used for the AP to adjust the first subcarrier. The received power of the first training sequence and/or the second training sequence is received on a subset.
An access point, characterized in that it comprises:

The sending unit is used to send first information to the station STA, where the first information is used to indicate the number of spatial streams M corresponding to the STA that needs to report the first training sequence and the second training sequence, and the STA reports the first training Sequence or the first sub-carrier subset occupied by the second training sequence,

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

The receiving unit is 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 the second training sequence, and the first training The sequence and the second training sequence are used to determine the frequency offset value between the STA and the access point.
The access point according to claim 16, wherein the first information comprises:

First indication information and second indication information, where the first indication information is used to indicate the M, and the second indication information is used to determine the first subcarrier subset.
The access point according to claim 17, wherein the sending unit sending the first information to the STA comprises:

The sending unit sends a trigger frame to the STA, the trigger frame is used to trigger the STA to report the PPDU, wherein the trigger frame carries the first indication information and the second indication information, and the first indication information and the second indication information are carried in the trigger frame. One indication information is the scheduling information field.
The access point according to claim 18, wherein the first indication information carried in the trigger frame comprises:

The trigger frame includes a general information field, and the general information field includes the first indication information.
The access point according to any one of claims 16-19, wherein the first training sequence or the second training sequence is determined by a mapping relationship between the STA and P matrix elements.
The access point according to any one of claims 16-20, wherein the receiving unit is further configured to receive a first information matrix on the first subcarrier subset, and the first information The matrix is determined by the first training sequence and channel information, and the 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 composed of the second training sequence and channel information, and the STA and the access point The frequency offset value between is determined;

Wherein, the frequency offset value between the STA and the access point is determined according to the first information matrix and the second information matrix.
The access point according to any one of claims 16-21, wherein the PPDU further comprises a channel estimation training sequence, the first training sequence, the second training sequence, and the channel estimation training The sequence is arranged one after another in the PPDU, or alternately arranged at intervals.
The access point according to any one of claims 16-22, wherein the PPDU further comprises an automatic gain control training sequence, and the automatic gain control training sequence is used for the access point to adjust in the The received power of the first training sequence and/or the second training sequence is received on the first subcarrier subset.
A site, characterized in that it includes:

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

Wherein, the station is any one of multiple stations communicating with the access point, and the first subcarrier subset is a subcarrier subset corresponding to the station in the S preset subcarrier subsets, so The M and S are positive integers and are used to determine 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, the PPDU includes the first training sequence and the second training sequence, the first training sequence And the second training sequence is used to determine the frequency offset value between the station and the AP.
The site according to claim 24, wherein the first information comprises:

First indication information and second indication information, the first indication information is used to indicate the M, and the second indication information is used to determine the first subcarrier subset.
The station according to claim 25, wherein the receiving unit receiving the first information from the AP comprises:

The receiving unit receives a trigger frame from the AP, the trigger frame is used to trigger the station to report the PPDU, wherein the trigger frame carries the first indication information and the second indication information, and the The first indication information is the scheduling information field.
The station according to claim 26, wherein the first indication information carried in the trigger frame comprises:

The trigger frame includes a general information field, and the general information field includes the first indication information.
The station according to any one of claims 24-27, wherein the first training sequence or the second training sequence is determined by a mapping relationship between the station and P matrix elements.
The station according to any one of claims 24-28, 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 in The PPDUs are arranged one after another in sequence, or alternately arranged at intervals.
The station according to any one of claims 24-29, wherein the PPDU further comprises an automatic gain control training sequence, and the automatic gain control training sequence is used by the AP to adjust the first subcarrier. The received power of the first training sequence and/or the second training sequence is received on a subset.
A communication device, characterized in that it comprises:

Memory, used to store computer programs;

A processor, configured to execute a computer program stored in the memory, so that the communication device executes the method according to any one of claims 1-8 or causes the communication device to execute any one of claims 9-15 The method described in one item.
A computer-readable storage medium, wherein the computer-readable storage medium is used to store a computer program, and the computer program includes instructions for implementing the method according to any one of claims 1-8, Or include instructions for implementing the method according to any one of claims 9-15.
A computer program product, characterized by comprising computer program code, when the computer program code runs on a computer, causes the computer to implement the method according to any one of claims 1-8 or causes the computer to implement The method of any one of claims 9-15.
A chip comprising one or more processing circuits, wherein the one or more processing circuits are used to implement the method according to any one of claims 1-8 or implement any one of claims 9-15 The method described in the item.
A device characterized by being used to implement the method according to any one of claims 1-8 or to implement the method according to any one of claims 9-15.
A communication system, characterized by comprising the access point according to any one of claims 16-23 and the station according to any one of claims 24-30.