CN107078824B

CN107078824B - Method, transmitter and receiver for transmitting channel estimation reference information and channel estimation

Info

Publication number: CN107078824B
Application number: CN201480083288.1A
Authority: CN
Inventors: 刘晟
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2014-12-26
Filing date: 2014-12-26
Publication date: 2020-03-20
Anticipated expiration: 2034-12-26
Also published as: WO2016101271A1; CN107078824A

Abstract

The embodiment of the invention provides a method for sending channel estimation reference information, which comprises the following steps of aiming at N continuous sub-informationCarrier wave

Loading a reference signal X (4m +2) corresponding to the subcarrier on the subcarrier 4m +2, loading zeros on other subcarriers, wherein N is a multiple of 8,

performing frequency-to-time domain conversion on the N consecutive subcarriers to obtain a conversion result { x (N) }, wherein,

generating a guard interval GI according to { -x (n) }; channel estimation reference information { GI, x (n) } is transmitted. The embodiment of the invention also provides a channel estimation method, a transmitter and a receiver. According to the technical solution provided by the embodiment of the present invention, for N consecutive subcarriers, channel estimation can be performed on each subcarrier that can be used for wireless transmission according to the reference signal carried on subcarrier 4m + 2.

Description

Method, transmitter and receiver for transmitting channel estimation reference information and channel estimation

Technical Field

The present invention relates to channel estimation technology, and more particularly, to a method, a transmitter, and a receiver for transmitting channel estimation reference information and channel estimation.

Background

Related technical standards of a Wireless Local Area Network (WLAN) based on an Orthogonal Frequency Division Multiplexing (OFDM) technology in the prior art are composed of versions of 802.11a, 802.11n, 802.11ac, and the like, which are evolved gradually, wherein 802.11n and 802.11ac already support Single User Multiple Input and Multiple Output (SU-MIMO) and downlink multi User Multiple Input and Multiple Output (MU-MIMO). The IEEE 802.11 standards organization has initiated standardization work for a new generation WLAN standard 802.11ax called High Efficiency wireless local area network (HEW), where uplink MU-MIMO is a key technology of 802.11 ax.

As of today, 802.11ax does not have a suitable channel estimation scheme.

Disclosure of Invention

In view of the above, it is actually necessary to provide a method for sending channel estimation reference information to provide a suitable channel estimation scheme for the latest WLAN technical standard.

Meanwhile, a channel estimation method is provided to provide a suitable channel estimation scheme for the latest WLAN technical standard.

Meanwhile, a transmitter is provided to provide a suitable channel estimation scheme for the latest WLAN technology standard.

Meanwhile, a receiver is provided to provide a suitable channel estimation scheme for the latest WLAN technical standard.

In accordance with an aspect of the embodiments of the present invention, there is provided a method for transmitting channel estimation reference information, including:

for N consecutive sub-carriers

performing frequency-time domain conversion on the N consecutive subcarriers to obtain a conversion result { x (N) }, wherein,

generating a guard interval GI according to { -x (n) };

channel estimation reference information { GI, x (n) } is transmitted.

In accordance with another aspect of the present invention, there is provided a channel estimation method, including:

receiving channel estimation reference information { GI ', x' (N) }, wherein the channel estimation reference information { GI ', x' (N) } is used for N continuous subcarriers

Channel estimation is carried out, N is a multiple of 8,

generating { x '(n), -x' (n), x '(n), -x' (n) } from { GI ', x' (n) };

performing time-frequency domain conversion on { X ' (n), -X ' (n), X ' (n), -X ' (n) } to obtain a reference signal X ' (4m +2) carried on the subcarrier 4m +2, wherein the reference signal X ' (4m +2) is obtained by filtering the reference signal X ' (n), and the reference signal X ' (n) is obtained by filtering the reference signal X ' (4m +2) carried on the subcarrier 4m

Channel estimation is performed on the N consecutive subcarriers in accordance with a reference signal X' (4m +2) carried on the subcarrier 4m + 2.

In accordance with still another aspect of the present invention, there is provided a transmitter including:

a processor to:

for N consecutive sub-carriers

generating a guard interval GI according to { -x (n) };

a transmitting unit, configured to send channel estimation reference information { GI, x (n) }.

In accordance with yet another aspect of the present invention, there is provided a receiver comprising:

a receiving unit, configured to receive channel estimation reference information { GI ', x' (N) }, where the channel estimation reference information { GI ', x' (N) } is used for N consecutive subcarriers

Channel estimation is carried out, N is a multiple of 8,

a processor to:

generating { x '(n), -x' (n), x '(n), -x' (n) } from { GI ', x' (n) };

According to the technical scheme provided by the embodiment of the invention, for N continuous subcarriers, channel estimation can be carried out on each subcarrier which can be used for carrying out wireless transmission according to the reference signal carried on the subcarrier 4m +2, so that a proper channel estimation scheme can be provided for the latest WLAN technical standard.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments of the present invention will be briefly described below, and it is obvious that the drawings described below are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

FIG. 1 is a diagram illustrating an exemplary WLAN deployment scenario system to which embodiments of the present invention may be applied;

FIG. 2 is a diagram of the distribution of sub-carriers occupied by HE-LTF in the 802.11ax standard in question;

fig. 3 is a distribution diagram of sub-carriers occupied by HE-LTF according to an embodiment of the present invention;

FIG. 4 is a schematic diagram of signals transmitted via two paths;

fig. 5 is an exemplary flowchart of a method of transmitting channel estimation reference information according to an embodiment of the present invention;

FIG. 6 is an exemplary flow chart of a channel estimation method according to an embodiment of the invention;

fig. 7 is a diagram illustrating a hardware configuration of a transmitter according to an embodiment of the present invention;

fig. 8 is a diagram illustrating a hardware structure of a receiver according to an embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, embodiments of the present invention are described in further detail below with reference to the accompanying drawings. In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the invention. It is to be understood that the embodiments described below are only some of the embodiments of the present invention, and not all of them. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

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

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

The embodiment of the invention can be applied to a wireless local area network, and the wireless local area network can be a Basic Service Set (BSS for short) containing access points. It should be understood that under the infrastructure of the WiFi system, multiple basic service sets may be included in the network, and each basic service set may include an AP and multiple STAs associated with the AP. The embodiments of the present invention are merely exemplified by stations, and the present invention is not limited thereto.

Fig. 1 is a schematic diagram of a typical WLAN deployment scenario system to which an embodiment of the present invention may be applied. Fig. 1 includes two sites: station 102 and station 104, and station 102 and station 104. In this system, a station 102 may transmit a data packet to a station 104, and similarly, a station 104 may also transmit a data packet to a station 102, where the station may be the STA or the AP, and the number of the stations may be one or more.

In the WLAN system, in order for a receiver to demodulate a signal from a transmitter, a channel estimation operation is first performed to estimate channel parameters of a channel between the transmitter and the receiver. To this end, the transmitter carries a reference signal in a Preamble (Preamble) directed to the receiver, which is known to both the transmitter and the receiver. Then, the receiver performs a channel estimation operation based on the received reference signal transmitted through the channel from the transmitter and a reference signal known by the receiver itself, that is, channel parameters of the channel between the transmitter and the receiver can be estimated. In 802.11ax, the reference signal is transmitted through a High Efficiency Long Training Field (HE-LTF) in the preamble.

The length of the OFDM symbol used by the existing WLAN systems based on the 802.11a, 802.11n and 802.11ac standards is 3.2us, and a Guard Interval (GI) with a length of 0.8us, that is, a Cyclic Prefix (CP), needs to be added before each OFDM symbol. Thus, in the 802.11a, 802.11n and 802.11ac standards, a complete symbol period is 4us in length. For convenience of description, the OFDM symbols adopted by the 802.11a, 802.11n, and 802.11ac standards will be simply referred to as unit length OFDM symbols hereinafter.

In order to reduce the overhead of GI, one OFDM symbol is defined to include 4 unit length OFDM symbols in the 802.11ax standard. Thus, the length of the OFDM symbol defined by the 802.11ax standard is 12.8us (3.2 × 4us), and after adding the CP with the length of 0.8us, one complete symbol period in the 802.11ax standard is 13.6 us. For convenience of description, the OFDM symbol adopted by the 802.11ax standard is hereinafter referred to simply as a 4 × length OFDM symbol.

Taking the 20MHz bandwidth as an example, when a 4-length OFDM symbol is used, the number of Fast Fourier Transform (FFT) points is 256, which corresponds to 256 subcarriers in the frequency domain of the 4-length OFDM symbol, i.e., subcarriers-128, -127,. 126, 127. Of the 256 subcarriers, subcarriers-1, 0, 1 are not used for wireless transmission, because these 3 subcarriers are susceptible to dc offset of the transmitting/receiving system. Meanwhile, the leftmost 6 subcarriers in the frequency spectrum, namely subcarriers-128, -127., -123, and the rightmost 5 subcarriers in the frequency spectrum, namely subcarriers 123, 124.,. 127, are called guard subcarriers and are not used for wireless transmission, so as to reduce the out-of-band leakage of the transmitted signal and avoid generating interference on adjacent channels. As such, among the 256 subcarriers, the subcarriers that can be used for wireless transmission are subcarriers-122, -121., -2, and subcarriers 2, 3.,. 122.

Fig. 2 is a distribution diagram of sub-carriers occupied by HE-LTF in the 802.11ax standard in question. As shown in FIG. 2, in generating the HE-LTF, the reference signals are carried on subcarriers + -4, + -8, + -12,. + -. 120 and the signals carried on the remaining subcarriers are zero in 256 subcarriers (i.e., subcarriers-128 to 127). In this way, the HE-LTF can be generated by performing an inverse fast fourier transform on the 256 subcarriers and adding a cyclic prefix. In performing channel estimation, the receiver may perform channel estimation by channel interpolation on other subcarriers available for wireless transmission based on reference signals carried on subcarriers ± 4, ± 8, ± 12., ± 120.

However, it is understood that, according to the HE-LTF transmission scheme described above, among the subcarriers that can be used to transmit signals, there are still few subcarriers that cannot be channel-estimated by channel interpolation. Specifically, according to the HE-LTF transmission scheme described above, among the subcarriers carrying reference signals, the subcarriers closest to the edge of the spectrum are the subcarriers ± 120, and therefore the subcarriers ± 122, ± 121 cannot refer to the reference signals carried on the subcarriers ± 120 for channel estimation through channel interpolation. Similarly, among the subcarriers carrying the reference signals, the subcarrier closest to the center of the spectrum is the subcarrier ± 4, so that the subcarriers ± 2 and ± 3 cannot refer to the reference signal carried on the subcarrier ± 4 for channel estimation through channel interpolation.

Fig. 3 is a distribution diagram of sub-carriers occupied by HE-LTF according to an embodiment of the present invention. As shown in fig. 3, in generating the HE-LTF, reference signals are carried on subcarriers ± 2, ± 6, ± 10,. and ± 122 in 256 subcarriers-128, -127,. 126, 127, with the signals carried on the remaining subcarriers being zero. In this way, the subcarriers that do not carry the reference signal among the subcarriers that can be used for wireless transmission can refer to the reference signal carried in the subcarriers that carry the reference signal, and perform channel estimation by channel interpolation. It is understood that the above scheme for allocating the subcarriers carrying the reference signals is not limited to the scenario in which the number of subcarriers is 256. In fact, the subcarriers carrying the reference signals can be allocated according to the above scheme as long as the number of subcarriers is a multiple of 8.

As described in the background of the invention, the subcarriers that are not available for wireless transmission include 3 subcarriers in the middle of the spectrum and guard subcarriers, and the guard subcarriers include 6 leftmost subcarriers in the spectrum and 5 rightmost subcarriers in the spectrum. Thus, for N consecutive subcarriers

The subcarriers that are not available for wireless transmission include subcarriers-1, 0, 1 (3 subcarriers in the middle of the spectrum), subcarriers

(leftmost 6 subcarriers in the spectrum) and subcarriers

(the rightmost 5 subcarriers in the spectrum). In this way, the subcarriers available for wireless transmission are subcarriers

And sub-carrier

When allocating reference signal-bearing subcarriers, the allocated reference signal-bearing subcarriers should also be selected from the subcarriers available for wireless transmission described above.

To sum up, according to the technical solution provided by the embodiment of the present invention, for N consecutive subcarriers

Loading a reference signal corresponding to the subcarrier on the subcarrier 4m +2, loading zeros on other subcarriers, wherein N is a multiple of 8,

referring to the distribution diagram shown in FIG. 3, in generating the HE-LTF, for the above-mentioned N consecutive subcarriers

The reference signal will be carried on subcarrier 4m +2 among the subcarriers available for wireless transmission, while the signals carried on the other subcarriers are zero. If x (k) represents the signal carried on the subcarrier, when k is 4m +2, x (k) is the reference signal carried on the subcarrier 4m + 2; when k ≠ 4m +2, X (k) is zero. As such, performing the inverse fourier transform on the N subcarriers will result in the following:

from the above formula, it can be seen that:

in other words, the result of the inverse Fourier transform can be expressed as { x (n), -x (n) }, where

Thus, if the transmitter wants to send { x (n), -x (n) }, then only { x (n) } needs to be sent. In this case, the receiver may be responsive to the received signal { x' (n) } (where

) Generating { x '(n), -x' (n), x '(n), -x' (n) }. The effect of the above method of transmitting only { x (n) } is obvious, and the scenario with bandwidth of 20MHz and number of subcarriers of 256 is taken as an example, { x (n), (n) } x (n)) The length of x (n), -x (n) } is 12.gus, while the length of { x (n) } (where 0. ltoreq. n.ltoreq.63) is only 3.2 us.

It should be noted that in the specific application, the actually sent information should also include a guard interval GI, if the transmitter wants to send { x (n) } (where

) The actual transmitted information will be { GI, x (n) }. Those skilled in the art will understand that GI is a cyclic prefix CP of { x (n), -x (n) }, and the cyclic prefix CP is a copy of the end of { x (n), -x (n) }, that is, a copy of the end of { -x (n) }. As such, the GI may be generated based on { -x (n) }.

Those skilled in the art should understand that the role of { GI, x (n) } is to assist the receiver in channel estimation, and thus, the { GI, x (n) } is channel estimation reference information. Compared with the mode of using { GI, x (n), -x (n), -x (n) } as the channel estimation reference information, the channel estimation reference information has significantly reduced overhead.

In practical applications, the above method for reducing the overhead of the channel estimation reference information is also applicable in a multipath scenario, and is described below with reference to fig. 4.

Fig. 4 is a schematic diagram of signals transmitted through two paths. Under the influence of multipath effects, a signal transmitted by a transmitter will reach a receiver through multiple paths, and in this case, the signal received by the receiver is a superimposed signal formed by superimposing signals transmitted through the multiple paths. In the scenario shown in fig. 4, there are two paths, the signal S (t) arriving at the receiver via the first path is { GI, S, -S }, and the signal S (t- τ) arriving at the receiver via the second path is delayed by a time period τ from S (t). After performing the operation of removing the guard interval GI, the superimposed signal at the receiver can be represented as { S ', -S ', -S ' }. It will be appreciated that the superimposed signal { S ', -S', S ', -S' } may be generated by the receiver from { S '}, and { S' } may be obtained by the receiver from the signal { GI, S } and its delayed signal after a delay of duration τ. In other words, if the signal to be transmitted is { GI, S, -S, S, -S }, then the transmitter need only transmit { GI, S }.

In conjunction with the above scheme for allocating subcarriers carrying reference signals and the above method for reducing overhead of reference information for channel estimation, an embodiment of the present invention provides a scheme for performing channel estimation, which is described in detail with reference to fig. 5 and 6.

Fig. 5 is an exemplary flowchart of a method 500 for transmitting channel estimation reference information according to an embodiment of the present invention.

Step 502, for N consecutive subcarriers

for example, N may be 256 at a bandwidth of 20 MHz.

Step 504, performing frequency-time domain conversion on the N consecutive subcarriers to obtain a conversion result { x (N) }, wherein,

it will be appreciated that one example of a frequency-to-time domain transform is the inverse fourier transform. In a specific implementation, inverse fast fourier transform is often used for frequency-to-time domain conversion.

Step 506, generating a guard interval GI according to { -x (n) };

step 508, sending the channel estimation reference information { GI, x (n) }.

According to the technical solution provided by the embodiment of the present invention, for N consecutive subcarriers, channel estimation can be performed on each subcarrier that can be used for wireless transmission according to the reference signal carried on subcarrier 4m + 2.

In addition, by sending { GI, x (n) } instead of { GI, x (n), -x (n) } as the channel estimation reference information, the overhead is greatly reduced.

Fig. 6 is an exemplary flow chart of a channel estimation method 600 according to an embodiment of the invention.

Step 602, receiving channel estimation reference information { GI ', x' (N) }, wherein the channel estimation reference information { GI ', x' (N) } is used for N consecutive subcarriers

Channel estimation is carried out, N is a multiple of 8,

for example, N may be 256 at a bandwidth of 20 MHz.

More specifically, the channel estimation reference information { GI ', x' (N) } is used to perform channel estimation on a subcarrier, which is available for wireless transmission, among N consecutive subcarriers.

Step 604, generating { x '(n), -x' (n), x '(n), -x' (n) } from { GI ', x' (n) };

specifically, firstly, removing GI 'in { GI', x '(n) }, so as to obtain { x' (n) }; then { x ' (n), -x ' (n), x ' (n), -x ' (n) } is generated according to { x ' (n) }.

Step 606, performing time-frequency domain conversion on { X '(n), -X' (n), X '(n), -X' (n) }, to obtain a reference signal X '(4 m +2) carried on subcarrier 4m +2, wherein the reference signal X' (4m +2) is obtained

It will be appreciated that one example of a time-to-frequency domain transform is the fourier transform. In particular implementations, a fast fourier transform is often used for time-to-frequency domain conversion.

In step 608, channel estimation is performed on the N consecutive subcarriers according to the reference signal X' (4m +2) carried on the subcarrier 4m + 2.

In a specific implementation procedure, step 608 specifically performs channel estimation on a subcarrier that can be used for wireless transmission in the N consecutive subcarriers according to a reference signal X' (4m +2) carried on subcarrier 4m + 2.

In a specific implementation process, for subcarriers other than subcarrier 4m +2 in subcarriers available for wireless transmission, channel interpolation may be used for estimation.

In particular, the method 500 shown in fig. 5 and the method 600 shown in fig. 6 may also be embodied as corresponding software products. At this time, each step may be implemented by a virtual module (e.g., a process or a function, etc.).

Accordingly, embodiments of the present invention further provide a transmitter corresponding to the method 500 for sending channel estimation reference information illustrated in fig. 5, and a receiver corresponding to the channel estimation method 600 illustrated in fig. 6, which are described in detail below with reference to fig. 7 and 8.

Fig. 7 is a diagram illustrating a hardware structure of a transmitter 700 according to an embodiment of the invention. As shown in fig. 7, the transmitter 700 includes a processor 702 and a transmitting unit 704.

The processor 702 is configured to perform steps 502-506 of the method 500.

The sending unit 704 is configured to perform step 508 in the method 500.

The details of the steps performed by the processor 702 and the sending unit 704 may refer to the method 500.

Fig. 8 is a diagram illustrating a hardware structure of a receiver 800 according to an embodiment of the present invention. As shown in fig. 8, receiver 800 comprises a receiving unit 802 and a processor 804.

The receiving unit 802 is configured to perform step 602 in the method 600.

The processor 804 is configured to perform steps 604-608 of the method 600.

The details of the steps performed by the receiving unit 802 and the processor 804 may be found in the method 600.

In addition, the embodiment of the present invention also provides a transceiver, which includes the transmitter 600 shown in fig. 7 and the receiver 800 shown in fig. 8.

In a specific implementation process, the processor 702 and the sending unit 704 in fig. 7, and the receiving unit 802 and the processor 804 in fig. 8 may also be implemented in a hardware + firmware manner. In other words, all of the units may be implemented by hardware, or all of the units may be implemented by hardware plus firmware, or some of the units may be implemented by hardware plus firmware, and other units may be implemented by hardware.

It is to be understood that the embodiments described herein may be implemented in hardware, software, firmware, middleware, microcode, or any combination thereof. For a hardware implementation, the Processing units may be implemented within one or more ASICs (Application specific integrated Circuits), DSPs (Digital Signal Processing), DSPDs (Digital Signal Processing devices), PLDs (Programmable Logic devices), FPGAs (Field Programmable Gate arrays), processors, controllers, microcontrollers, microprocessors, chips, and other electronic units or combinations thereof for performing the functions described herein.

When the embodiments are implemented in software, firmware, middleware or microcode, program code or code segments, they may be stored in a machine-readable medium, such as a storage component. A code segment may represent a procedure, a function, a subprogram, a program, a routine, a subroutine, a module, a software package, a class, or any combination of instructions, data structures, or program statements. A code segment may be incorporated into another code segment or a hardware circuit by passing and/or receiving information, data, arguments, parameters, or memory contents. Information, arguments, parameters, data, etc. may be passed, forwarded, or transmitted using any suitable means including memory sharing, message passing, token passing, network transmission, etc.

For a software implementation, the techniques described herein may be implemented with modules (e.g., procedures, functions, and so on) that perform the functions described herein. The software codes may be stored in a memory and executed by a processor. The memory unit may be implemented within the processor or external to the processor, in which case it can be communicatively coupled to the processor via various means as is known in the art.

What has been described above includes examples of one or more embodiments. It is, of course, not possible to describe every conceivable combination of components or methodologies for purposes of describing the aforementioned embodiments, but one of ordinary skill in the art may recognize that many further combinations and permutations of various embodiments are possible. Accordingly, the embodiments described in this application are intended to embrace all such alterations, modifications and variations that fall within the spirit and scope of the appended claims. Furthermore, to the extent that the term "includes" is used in either the detailed description or the claims, such term is intended to be inclusive in a manner similar to the term "comprising" as "comprising" is interpreted when employed as a transitional word in a claim.

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

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

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

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

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

The functions, if implemented in the form of software functional units and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present invention may be embodied in the form of a software product, which is stored in a storage medium and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the method according to the embodiments of the present invention. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and other various media capable of storing program codes.

In summary, the above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for transmitting channel estimation reference information, comprising:

for N consecutive sub-carriers

generating a guard interval GI according to { -x (n) };

channel estimation reference information { GI, x (n) } is transmitted.

2. The method of claim 1, wherein N is 256 at 20 MHz.

3. The method of claim 1 or 2, wherein the frequency-time domain conversion is an inverse fast fourier transform.

4. A method of channel estimation, comprising:

Channel estimation is carried out, N is a multiple of 8,

generating { x '(n), -x' (n), x '(n), -x' (n) } from { GI ', x' (n) };

for { x ' (n), -x ' (n), x ' ((n))n), -X '(n) } performs a time-frequency domain conversion to obtain a reference signal X' (4m +2) carried on a subcarrier 4m +2, wherein

Channel estimation is performed on the N consecutive subcarriers by means of channel interpolation according to the reference signal X' (4m +2) carried on subcarrier 4m + 2.

5. The method of claim 4, wherein N is 256 at 20MHz bandwidth.

6. The method of claim 4 or 5, wherein the time-frequency domain is converted to a fast Fourier transform.

7. A transmitter, comprising:

a processor to:

for N consecutive sub-carriers

generating a guard interval GI according to { -x (n) };

8. The transmitter of claim 7, wherein N is 256 at a bandwidth of 20 MHz.

9. A receiver, comprising:

Channel estimation is carried out, N is a multiple of 8,

a processor to:

generating { x '(n), -x' (n), x '(n), -x' (n) } from { GI ', x' (n) };

10. The receiver of claim 9, wherein N is 256 at a bandwidth of 20 MHz.

11. A storage medium storing a computer software product comprising instructions for causing a computer device to perform the method of any one of claims 1 to 3.

12. A storage medium storing a computer software product comprising instructions for causing a computer device to perform the method of any one of claims 4 to 6.