CN112511471B - Channel estimation method, apparatus, device and medium based on space-frequency block code - Google Patents

Abstract

The invention discloses a channel estimation method based on a space-frequency block code, comprising: determining an initial channel estimation value by using received signals and transmitted signals of two adjacent subcarriers; determining a target by using the received signals and transmitted signals of each group of subcarriers Symbol timing offset; use the target symbol timing offset to perform phase correction on the initial channel estimate to obtain the final target channel estimate. It can be seen that when this scheme performs channel estimation based on the space-frequency block code, it is necessary to calculate the target symbol timing offset, and use the target symbol timing offset to perform phase correction on the initial channel estimation value. In this way, symbol timing caused by symbol timing can be avoided. The problem of decoding failure caused by deviation ensures the reliability of decoding; the invention also discloses a channel estimation device, equipment and medium based on space-frequency block code, which can also achieve the above technical effects.

Description

Channel estimation method, apparatus, device and medium based on space-frequency block code

technical field

The present invention relates to the technical field of mobile communication systems, and more particularly, to a method, apparatus, device and medium for channel estimation based on space-frequency block codes.

Background technique

MIMO (multiple-input multiple-output, multiple-input multiple-output)-OFDM (orthogonal frequency division multiplexing, orthogonal frequency division multiplexing technology) system is to simultaneously arrange multiple The multiple-input multiple-output system MIMO composed of antennas combines the characteristics of high diversity gain, large system capacity of MIMO system, resistance to frequency selective fading and high spectrum utilization of OFDM system. Driven by the requirements, it is receiving more and more attention.

In MIMO technology, from the perspective of improving spatial diversity, space-time block coding (STBC) is the most widely studied due to its orthogonality design, which only requires linear complexity for maximum likelihood decoding. . Combining space-time block coding with OFDM, a space-frequency block coding (SFBC) is formed. At this time, the requirements of the space-time block code for the channel time domain characteristics also turn into the requirements for the channel frequency domain characteristics. For example, the corresponding space-frequency code of the Alamouti space-time code requires that the frequency domain channel where the same code block is located is slowly changing.

Referring to Fig. 1, it is a schematic diagram of the SFBC-based MIMO-OFDM classic system framework in the existing solution. It can be seen from Fig. 1 that Fig. 1 shows the process of receiving and sending data in the MIMO-OFDM system, including: the information bits at the transmitting end are passed through complex numbers The information symbols are obtained by constellation modulation, encoded by SFBC, and then split and modulated by OFDM, and then sent to each transmitting antenna. The receiving end first performs OFDM demodulation on the signals received by each antenna, and then uses the demodulated frequency domain data for channel estimation, and sends the obtained frequency domain channel information together with the frequency domain received data to the SFBC decoder. Decoding is performed, and information bits are obtained after demodulation and recovery. Both time-frequency synchronization and channel estimation are key technologies in OFDM systems. Note that the OFDM system (especially the CP (cyclic-prefix, cyclic prefix)-OFDM) has a relatively low accuracy for symbol timing synchronization due to the guard interval function played by the CP. In principle, the error of symbol timing synchronization only needs to be less than 1/2 of the CP length. At this time, the influence of symbol timing can be eliminated by rational use of the CP guard interval.

However, if the Alamouti space-time code scheme is combined with the OFDM system to form a MIMO-OFDM system, the timing deviation introduced by the symbol timing will cause an additional linear phase shift to the frequency-domain equivalent channel of the received data, so that the Alamouti code will The requirement for slow channel variation in the same coding block cannot be met, which leads to decoding failure.

Therefore, how to avoid the decoding failure caused by the timing deviation introduced by the symbol timing is a problem to be solved by those skilled in the art.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a channel estimation method, apparatus, device and medium based on space-frequency block code, so as to avoid decoding failure caused by timing deviation introduced by symbol timing.

In order to achieve the above objects, the present invention provides a channel estimation method based on space-frequency block codes, including:

Determine the initial channel estimation value by using the received signal and the transmitted signal of two adjacent subcarriers;

The target symbol timing offset is determined by the received signal and the transmitted signal of each group of subcarriers; wherein, each group of subcarriers includes four adjacent subcarriers; the adjacent four subcarriers include the adjacent two subcarriers. subcarriers;

Phase correction is performed on the initial channel estimation value using the target symbol timing offset to obtain a final target channel estimation value.

Wherein, determining the initial channel estimation value by using the received signals and the transmitted signals of two adjacent subcarriers includes:

Determine each group of subcarriers, and each group of subcarriers includes a first subcarrier, a second subcarrier, a third subcarrier, and a fourth subcarrier whose subcarrier sequence numbers are sequentially increased;

Taking the first subcarrier and the second subcarrier in each group of subcarriers as two adjacent subcarriers;

According to the received signals obtained by the first receive antenna and the second receive antenna on the first subcarrier and the second subcarrier, and the first transmit antenna and the second transmit antenna transmit on the first subcarrier and the second subcarrier , determine the first channel estimation function;

An initial channel estimation value is determined according to the first channel estimation function.

Wherein, the initial channel estimation value includes:

a first initial channel estimate between the first transmit antenna and the first receive antenna, a second initial channel estimate between the second transmit antenna and the first receive antenna, the first transmit antenna and a third initial channel estimation value between the second receiving antenna and the second receiving antenna, and a fourth initial channel estimation value between the second transmitting antenna and the second receiving antenna.

Wherein, determining the timing deviation of the target symbol through the received signal and the transmitted signal of each group of subcarriers includes:

According to the received signals obtained by the first receive antenna and the second receive antenna on the third subcarrier and the fourth subcarrier, and the first transmit antenna and the second transmit antenna transmit on the third subcarrier and the fourth subcarrier , determine the second channel estimation function;

calculating, according to the first channel estimation function and the second channel estimation function of each group of subcarriers, an initial symbol timing offset corresponding to each group of subcarriers;

The target symbol timing offset is determined by using the initial symbol timing offset corresponding to each group of subcarriers.

The determining the symbol timing deviation using the initial symbol timing deviation corresponding to each group of subcarriers includes: calculating an average value of the initial symbol timing deviations of each group of subcarriers, and using the average value as the target symbol timing deviation .

Wherein, performing phase correction on the initial channel estimation value by using the target symbol timing offset to obtain a final target channel estimation value, including:

及估计值确定规则，对初始信道估计值进行相位校正，得到最终的目标信道估计值；Use the target symbol timing offset

and the estimation value determination rule, perform phase correction on the initial channel estimation value, and obtain the final target channel estimation value;

Wherein, the estimated value determination rule is:

为所述第一发送天线与所述第一接收天线间的第一目标信道估计值，

为所述第二发送天线与所述第一接收天线间的第二目标信道估计值，e为自然常数，N为子载波的总数，k为子载波的序号，

为所述第一发送天线与所述第一接收天线间的第一初始信道估计值，

为所述第二发送天线与所述第一接收天线间的第二初始信道估计值，

为所述第一发送天线与所述第二接收天线间的第三目标信道估计值，

为所述第二发送天线与所述第二接收天线间的第一目标信道估计值，

为所述第一发送天线与所述第二接收天线间的第三初始信道估计值，

为所述第二发送天线与所述第二接收天线间的第四初始信道估计值。in,

is the estimated value of the first target channel between the first transmit antenna and the first receive antenna,

is the estimated value of the second target channel between the second transmitting antenna and the first receiving antenna, e is a natural constant, N is the total number of subcarriers, k is the sequence number of the subcarriers,

is the first initial channel estimation value between the first transmit antenna and the first receive antenna,

is the second initial channel estimation value between the second transmit antenna and the first receive antenna,

is the estimated value of the third target channel between the first transmit antenna and the second receive antenna,

is the estimated value of the first target channel between the second transmit antenna and the second receive antenna,

is the third initial channel estimation value between the first transmit antenna and the second receive antenna,

is the fourth initial channel estimation value between the second transmit antenna and the second receive antenna.

In order to achieve the above objects, the present invention further provides a channel estimation device based on space-frequency block codes, comprising:

a first estimation value determination module, configured to determine an initial channel estimation value by using the received signals and the transmitted signals of two adjacent subcarriers;

A symbol timing offset determination module, used for determining the target symbol timing offset through the received signal and the transmitted signal of each group of subcarriers; wherein, each group of subcarriers includes four adjacent subcarriers; the adjacent four subcarriers including the two adjacent subcarriers;

A second estimation value determination module, configured to perform phase correction on the initial channel estimation value by using the target symbol timing offset to obtain a final target channel estimation value.

Wherein, the first estimated value determination module includes:

a first determining unit, configured to determine each group of subcarriers, where each group of subcarriers includes a first subcarrier, a second subcarrier, a third subcarrier, and a fourth subcarrier whose subcarrier sequence numbers are sequentially increased;

an adjacent subcarrier determination unit, configured to use the first subcarrier and the second subcarrier in each group of subcarriers as two adjacent subcarriers;

a second determining unit, configured to obtain received signals on the first sub-carrier and the second sub-carrier according to the first receiving antenna and the second receiving antenna, and the first transmitting antenna and the second transmitting antenna on the first sub-carrier the transmission signal sent by the carrier and the second sub-carrier to determine the first channel estimation function;

A third determining unit, configured to determine an initial channel estimation value according to the first channel estimation function.

To achieve the above object, the present invention further provides an electronic device, comprising:

memory for storing computer programs;

The processor is configured to implement the steps of the above-mentioned method for channel estimation based on space-frequency block codes when executing the computer program.

In order to achieve the above object, the present invention further provides a computer-readable storage medium on which a computer program is stored, and when the computer program is executed by the processor, the above-mentioned channel estimation based on the space-frequency block code is realized. steps of the method.

It can be seen from the above solutions that a method for channel estimation based on space-frequency block codes provided by an embodiment of the present invention includes: determining an initial channel estimation value by using received signals and transmitted signals of two adjacent subcarriers; The received signal and the transmitted signal determine the target symbol timing offset; wherein, each group of subcarriers includes four adjacent subcarriers; the adjacent four subcarriers include the adjacent two subcarriers; using the The target symbol timing offset performs phase correction on the initial channel estimation value to obtain the final target channel estimation value.

It can be seen that when this scheme performs channel estimation based on the space-frequency block code, it is necessary to calculate the target symbol timing offset, and use the target symbol timing offset to perform phase correction on the initial channel estimation value. In this way, symbol timing caused by symbol timing can be avoided. The problem of decoding failure caused by deviation ensures the reliability of decoding; the invention also discloses a channel estimation device, equipment and medium based on space-frequency block code, which can also achieve the above technical effects.

Description of drawings

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the following briefly introduces the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained according to these drawings without creative efforts.

FIG. 1 is a schematic diagram of a classic system framework of SFBC-based MIMO-OFDM in the existing solution;

2 is a schematic flowchart of a method for channel estimation based on a space-frequency block code disclosed in an embodiment of the present invention;

3a is a schematic diagram of a channel estimation value when STO is 0 disclosed in an embodiment of the present invention;

3b is a schematic diagram of another channel estimation value when STO is 0 disclosed in an embodiment of the present invention;

3c is a schematic diagram of another channel estimation value when STO is 0 disclosed in an embodiment of the present invention;

3d is a schematic diagram of another channel estimation value when STO is 0 disclosed in an embodiment of the present invention;

4a is a schematic diagram of a channel estimation value when STO is 32 disclosed in an embodiment of the present invention;

FIG. 4b is a schematic diagram of another channel estimation value when STO is 32 disclosed in an embodiment of the present invention;

4c is a schematic diagram of another channel estimation value when the STO is 32 disclosed in an embodiment of the present invention;

FIG. 4d is a schematic diagram of another channel estimation value when the STO is 32 disclosed in the embodiment of the present invention;

FIG. 5a is a schematic diagram of a signal estimation value when STO is 0 disclosed in an embodiment of the present invention;

FIG. 5b is a schematic diagram of a signal estimation value when STO is 32 disclosed in an embodiment of the present invention;

6a is a schematic diagram of a channel estimation value after STO compensation disclosed in an embodiment of the present invention;

6b is a schematic diagram of another channel estimation value after STO compensation disclosed in an embodiment of the present invention;

6c is a schematic diagram of another channel estimation value after STO compensation disclosed in an embodiment of the present invention;

FIG. 6d is a schematic diagram of another channel estimation value after STO compensation disclosed in an embodiment of the present invention;

FIG. 7 is a block diagram for realizing channel estimation based on phase correction disclosed in an embodiment of the present invention;

8 is a schematic structural diagram of a channel estimation apparatus based on a space-frequency block code disclosed in an embodiment of the present invention;

FIG. 9 is a schematic structural diagram of an electronic device disclosed in an embodiment of the present invention.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

The embodiments of the present invention disclose a channel estimation method, device, device and medium based on space-frequency block codes, so as to avoid decoding failure caused by timing deviation introduced by symbol timing.

Referring to FIG. 2, a schematic flowchart of a method for channel estimation based on a space-frequency block code provided by an embodiment of the present invention includes:

S101. Determine an initial channel estimation value by using the received signal and the transmitted signal of two adjacent subcarriers;

Wherein, in this scheme, the process of determining the initial channel estimation value using the received signals and the transmitted signals of two adjacent subcarriers specifically includes:

Determine each group of subcarriers, wherein each group of subcarriers includes a first subcarrier, a second subcarrier, a third subcarrier, and a fourth subcarrier whose subcarrier sequence numbers increase in sequence; The subcarrier and the second subcarrier are regarded as two adjacent subcarriers; according to the received signals obtained by the first receiving antenna and the second receiving antenna in the first subcarrier and the second subcarrier, and the first transmitting antenna and the second receiving For the transmit signals sent by the two transmit antennas on the first subcarrier and the second subcarrier, a first channel estimation function is determined; and an initial channel estimation value is determined according to the first channel estimation function.

It should be noted that when performing channel estimation in this solution, all sub-carriers need to be grouped first. For example, if the total number of sub-carriers is 64, and the number of sub-carriers in each group is set to 4, then the 64 sub-carriers can be divided into groups. The carrier is divided into 16 groups of sub-carriers. In this scheme, the 4 sub-carriers are named according to the sub-carrier serial number of each group of sub-carriers, that is, each group of sub-carriers includes: the first sub-carrier, the second sub-carrier, The third subcarrier and the fourth subcarrier. Moreover, when the initial channel estimation value is determined in this solution, the initial channel estimation value is specifically determined by two adjacent subcarriers, the first subcarrier and the second subcarrier.

Specifically, for the convenience of analysis, in this embodiment, single-input single-output (SISO) OFDM is used as an example for description. Assuming that the symbol time offset (STO) is d, the received signal The frequency domain expression of is:

（1）

(1)

为第

个子载波上的接收信号，

表示第

个子载波处信道频域响应，

为第

个子载波上的发送信号，

表示子载波数目。in,

for the first

received signals on subcarriers,

means the first

The channel frequency domain response at subcarriers,

for the first

The transmitted signal on subcarriers,

Indicates the number of subcarriers.

和

；发射天线2在这两个频点上依次承载信息符号

和

。On this basis, consider the case of using SFBC in a 2×2 MIMO-OFDM system. The Alamouti space-time code is applied to the frequency domain to obtain the SFBC coding scheme. The same SFBC coding block will occupy two adjacent frequency points in the frequency domain OFDM symbol block of two transmitting antennas, and transmitting antenna 1 will carry information symbols on these two frequency points in turn.

and

; The transmitting antenna 2 carries information symbols on these two frequency points in turn

and

.

The system frequency domain model of receiving antenna 1 is represented by equation (2):

（2）

(2)

表示接收天线1在第1个子载波上接收到的分组中的第一个信号，

则表示接收天线1在第2个子载波上接收到的分组中的第二个信号。

为发射天线1在第一时刻发送的第一个信号，

为发射天线2在第一时刻发送的第一个信号，

为发射天线1在第二时刻发送的第二个信号，

为发射天线2在第二时刻发送的第二个信号，

为第1个子载波中发射天线1与接收天线1之间的初始信道估计值，

为第1个子载波中发射天线2与接收天线1之间的初始信道估计值，

为第2个子载波中发射天线1与接收天线1之间的初始信道估计值，

为第2个子载波中发射天线2与接收天线1之间的初始信道估计值。

为接收天线1在第一个子载波中接收数据的噪声，

为接收天线1在第二个子载波中接收数据的噪声。in,

represents the first signal in the packet received by receive antenna 1 on the 1st subcarrier,

Then it represents the second signal in the packet received by receiving antenna 1 on the second subcarrier.

is the first signal sent by transmitting antenna 1 at the first moment,

is the first signal sent by the transmitting antenna 2 at the first moment,

is the second signal sent by transmit antenna 1 at the second moment,

is the second signal sent by the transmitting antenna 2 at the second moment,

is the initial channel estimate between transmit antenna 1 and receive antenna 1 in the first subcarrier,

is the initial channel estimate between transmit antenna 2 and receive antenna 1 in the first subcarrier,

is the initial channel estimate between transmit antenna 1 and receive antenna 1 in the second subcarrier,

is the initial channel estimation value between transmit antenna 2 and receive antenna 1 in the second subcarrier.

is the noise of the data received in the first subcarrier for receive antenna 1,

The noise of the received data in the second subcarrier for receive antenna 1.

Correspondingly, the system frequency domain model of the receiving antenna 2 is represented by (3):

（3）

(3)

表示接收天线2在第1个子载波上接收到的分组中的第一个信号，

表示接收天线2在第2个子载波上接收到的分组中的第二个信号。

为接收天线2在第一个子载波中接收数据的噪声，

为接收天线1在第二个子载波中接收数据的噪声。in,

represents the first signal in the packet received by receiving antenna 2 on the first subcarrier,

Represents the second signal in the packet received by receive antenna 2 on the 2nd subcarrier.

is the noise of the data received in the first subcarrier for receive antenna 2,

The noise of the received data in the second subcarrier for receive antenna 1.

In this embodiment, it is assumed that the channel frequency domain responses of two adjacent subcarriers are equal (approximately equal), then formula (2) can be transformed into formula (4), and formula (3) can be transformed into formula (5):

（4）

(4)

（5）

(5)

According to the above formula (4) and formula (5), the initial channel estimation value can be determined as:

（6）

(6)

（7）

(7)

、

、

、

，其中，

为第一发送天线与第一接收天线间的第一初始信道估计值，

为第二发送天线与第一接收天线间的第二初始信道估计值，

为第一发送天线与第二接收天线间的第三初始信道估计值，

为第二发送天线与第二接收天线间的第四初始信道估计值。The initial channel estimation value can be determined by formula (6) and formula (7)

,

,

,

,in,

is the first initial channel estimation value between the first transmitting antenna and the first receiving antenna,

is the second initial channel estimation value between the second transmitting antenna and the first receiving antenna,

is the third initial channel estimation value between the first transmit antenna and the second receive antenna,

is the fourth initial channel estimation value between the second transmit antenna and the second receive antenna.

、

、

、

中具有定时偏差所带来的影响，因此，不能利用这上述公式（6）和公式（7）实现对信道的估计，STO会造成信道估计的不确定性。参见图3a、图3b、图3c、图3d和图4a、图4b、图4c、图4d，为本发明实施例公开的STO对MIMO-OFDM系统中采用SFBC时信道估计的影响示意图，其中，图3a、图3b、图3c、图3d，为本发明实施例公开的符号定时偏差为0时的不同信道估计值示意图，图4a、图4b、图4c、图4d，为本发明实施例公开的符号定时偏差为32时的不同信道估计值示意图，相对应地，STO对信道估计的影响会反映到后续SFBC分集，利用式（6）和（7）获得的信道估计值，SFBC分集处理采用LS估计可以得到信号估计值为：Due to the above

,

,

,

Therefore, the above formula (6) and formula (7) cannot be used to realize the estimation of the channel, and STO will cause the uncertainty of the channel estimation. 3a, 3b, 3c, 3d, and 4a, 4b, 4c, and 4d, it is a schematic diagram of the influence of STO on channel estimation in a MIMO-OFDM system when SFBC is adopted according to an embodiment of the present invention, wherein, 3a, 3b, 3c, and 3d are schematic diagrams of different channel estimation values when the symbol timing offset is 0 disclosed in the embodiment of the present invention, and FIGS. 4a, 4b, 4c, and 4d are disclosed in the embodiment of the present invention Schematic diagram of different channel estimation values when the symbol timing deviation of the LS estimation can get the estimated signal value as:

（8）

(8)

Referring to Fig. 5a and Fig. 5b, the influence of the STO disclosed in this embodiment on the estimated value of the signal obtained by adopting SFBC diversity reception in the MIMO-OFDM system, wherein Fig. 5a is the estimated value of the 2×2 MIMO signal when the symbol timing offset is 0 , Figure 5b shows the estimated value of the 2×2 MIMO signal when the symbol timing offset is 32; it can be seen that the symbol timing offset will affect the channel estimated value and the signal estimated value. Therefore, in this scheme, when the MIMO-OFDM system adopts the space frequency During coding, it is necessary to overcome the influence of the symbol timing deviation and realize the accurate estimation of the channel, so as to realize the correct diversity reception of the final signal.

S102. Determine the target symbol timing offset according to the received signal and the transmitted signal of each group of subcarriers; wherein, each group of subcarriers includes four adjacent subcarriers; the adjacent four subcarriers include the adjacent four subcarriers. the two subcarriers;

Wherein, the process of determining the timing deviation of the target symbol by the received signal and the transmitted signal of each group of subcarriers in this scheme specifically includes: according to the first receiving antenna and the second receiving antenna obtained on the third subcarrier and the fourth subcarrier The received signal, and the transmit signal sent by the first transmit antenna and the second transmit antenna on the third subcarrier and the fourth subcarrier, determine a second channel estimation function; according to the first channel estimation function of each group of subcarriers and the second channel estimation function, calculating the initial symbol timing offset corresponding to each group of subcarriers; and determining the target symbol timing offset by using the initial symbol timing offset corresponding to each group of subcarriers.

In this embodiment, in order to overcome the influence of the symbol timing deviation on the channel estimation value, it is reasonable to assume that the channel frequency domain responses of the adjacent four subcarriers are equal (approximately equal), and can be determined by the above formula (4) and formula (5) The first channel estimation function for calculating the channel estimation function corresponding to the first subcarrier and the second subcarrier, this time, the second channel estimation function for calculating the channel estimation function corresponding to the third subcarrier and the fourth subcarrier is determined as: :

（9）

(9)

（10）

(10)

表示接收天线1在第3个子载波上接收到的分组中的第三个信号，

则表示接收天线1在第4个子载波上接收到的分组中的第四个信号，

为发射天线1在第三时刻发送的第三个信号，

为发射天线2在第三时刻发送的第三个信号，

为发射天线1在第四时刻发送的第四个信号，

为发射天线2在第四时刻发送的第四个信号，

为接收天线1在第三个子载波中接收数据的噪声，

为接收天线1在第四个子载波中接收数据的噪声。

为接收天线2在第三个子载波中接收数据的噪声，

为接收天线2在第四个子载波中接收数据的噪声。in,

represents the third signal in the packet received by receive antenna 1 on the third subcarrier,

Then it represents the fourth signal in the packet received by receiving antenna 1 on the fourth subcarrier,

is the third signal sent by transmitting antenna 1 at the third moment,

is the third signal sent by transmit antenna 2 at the third moment,

is the fourth signal sent by transmitting antenna 1 at the fourth moment,

is the fourth signal sent by the transmitting antenna 2 at the fourth moment,

is the noise of the data received in the third subcarrier for receive antenna 1,

The noise of the received data in the fourth subcarrier for receive antenna 1.

is the noise of the data received in the third subcarrier for receive antenna 2,

The noise of the received data in the fourth sub-carrier for receive antenna 2.

In this embodiment, for the convenience of analysis, the influence of noise is ignored. Using the properties of the diagonal matrix, formula (4) in the first channel estimation function and formula (9) in the second channel estimation function can be further processed to obtain formula (11) and formula (12):

（11）

(11)

（12）

(12)

表示共轭转置。将式（11）和式（12）进行共轭点乘，利用相邻四个子载波的信道频域响应相等（近似相等）的假设，可以得到公式（13）：in,

represents the conjugate transpose. Conjugate point multiplication of equations (11) and (12), and use the assumption that the channel frequency domain responses of the adjacent four subcarriers are equal (approximately equal), equation (13) can be obtained:

(13)

(13)

The initial symbol timing offset corresponding to this group of subcarriers can be calculated by formula (13). Similarly, formula (4) and formula (10) can be obtained by formula (14) through the above process:

(14)

(14)

，从而提高STO的估计精度。Another initial symbol timing offset corresponding to this group of subcarriers can be calculated by formula (14). After obtaining the initial symbol timing offset corresponding to each group of subcarriers in the above method, the initial symbol timing offset of each group of subcarriers can be calculated. the average value of the final target symbol timing offset

, thereby improving the estimation accuracy of STO.

S103. Perform phase correction on the initial channel estimation value by using the target symbol timing offset to obtain a final target channel estimation value.

Wherein, this scheme uses the target symbol timing offset to perform phase correction on the initial channel estimation value to obtain the final target channel estimation value, including:

及估计值确定规则，对初始信道估计值进行相位校正，得到最终的目标信道估计值；该估计值确定规则为：Use target symbol timing offset

and the estimation value determination rule, perform phase correction on the initial channel estimation value to obtain the final target channel estimation value; the estimation value determination rule is:

为所述第一发送天线与所述第一接收天线间的第一目标信道估计值，为所述第二发送天线与所述第一接收天线间的第二目标信道估计值，e为自然常数，N为子载波的总数，k为子载波的序号，

为所述第一发送天线与所述第一接收天线间的第一初始信道估计值，

为所述第二发送天线与所述第一接收天线间的第二初始信道估计值，

为所述第一发送天线与所述第二接收天线间的第三目标信道估计值，

为所述第二发送天线与所述第二接收天线间的第一目标信道估计值，

为所述第一发送天线与所述第二接收天线间的第三初始信道估计值，

为所述第二发送天线与所述第二接收天线间的第四初始信道估计值。in,

is the estimated value of the first target channel between the first transmitting antenna and the first receiving antenna, is the estimated value of the second target channel between the second transmitting antenna and the first receiving antenna, and e is a natural constant , N is the total number of subcarriers, k is the sequence number of the subcarriers,

is the first initial channel estimation value between the first transmit antenna and the first receive antenna,

is the second initial channel estimation value between the second transmit antenna and the first receive antenna,

is the estimated value of the third target channel between the first transmit antenna and the second receive antenna,

is the estimated value of the first target channel between the second transmit antenna and the second receive antenna,

is the third initial channel estimation value between the first transmit antenna and the second receive antenna,

is the fourth initial channel estimation value between the second transmit antenna and the second receive antenna.

It should be noted that, in this embodiment, if formula (4) is extended to the general case:

（15）

(15)

Combined with formula (15), the accurate target channel estimation value can be obtained as:

（16）

(16)

（17）

(17)

6a, 6b, 6c, and 6d, the effects of channel estimation under the condition of using SFBC in the MIMO-OFDM system after compensating STO disclosed in this embodiment, wherein, FIG. 6a, FIG. 6b, FIG. 6c and FIG. 6d, respectively represent schematic diagrams of different channel estimation values when the symbol timing deviation is 32. It can be seen that accurate channel estimation values can be completely obtained through phase correction.

、

、

、

，在此基础上，结合式（13）和式（14）在频域实现STO的精确估计，最后，利用式（16）和式（17）实现相位校正，得到最终的目标信道估计值

、

、

、

。From the above, it can be seen that this scheme proposes a channel estimation method with "phase correction" suitable for MIMO-OFDM under the condition of SFBC. This method performs "phase correction" on the frequency domain channel response data at the receiving end, so that The corrected equivalent frequency domain channel meets the requirements of the Alamouti scheme again, so as to ensure the reliability of decoding. Referring to FIG. 7 , which is a block diagram of the implementation of channel estimation based on phase correction disclosed in this embodiment. In this solution, the frequency domain data received based on two antennas is the received signal, and the pilot data is the transmitted signal. The transmission information and the above formulas (6) and (7) realize channel estimation, and obtain the initial channel estimation value:

,

,

,

, on this basis, combine Equation (13) and Equation (14) to achieve accurate estimation of STO in the frequency domain, and finally, use Equation (16) and Equation (17) to achieve phase correction to obtain the final target channel estimation value

,

,

,

.

The channel estimation apparatus, equipment, and medium provided by the embodiments of the present invention are described below. The channel estimation apparatus described below and the channel estimation apparatus, equipment, and medium described above may refer to each other.

Referring to FIG. 8, a schematic structural diagram of a channel estimation apparatus based on space-frequency block codes provided by an embodiment of the present invention includes:

a first estimation value determination module 100, configured to determine an initial channel estimation value by using received signals and transmitted signals of two adjacent subcarriers;

A symbol timing offset determination module 200, configured to determine a target symbol timing offset through the received signal and the transmitted signal of each group of subcarriers; wherein, each group of subcarriers includes four adjacent subcarriers; the four adjacent subcarriers The carrier includes the two adjacent subcarriers;

The second estimation value determination module 300 is configured to perform phase correction on the initial channel estimation value by using the target symbol timing offset to obtain a final target channel estimation value.

Wherein, the first estimated value determination module includes:

a first determining unit, configured to determine each group of subcarriers, where each group of subcarriers includes a first subcarrier, a second subcarrier, a third subcarrier, and a fourth subcarrier whose subcarrier sequence numbers are sequentially increased;

an adjacent subcarrier determination unit, configured to use the first subcarrier and the second subcarrier in each group of subcarriers as two adjacent subcarriers;

a second determining unit, configured to obtain received signals on the first sub-carrier and the second sub-carrier according to the first receiving antenna and the second receiving antenna, and the first transmitting antenna and the second transmitting antenna on the first sub-carrier the transmission signal sent by the carrier and the second sub-carrier to determine the first channel estimation function;

A third determining unit, configured to determine an initial channel estimation value according to the first channel estimation function.

Wherein, the initial channel estimation value includes:

a first initial channel estimate between the first transmit antenna and the first receive antenna, a second initial channel estimate between the second transmit antenna and the first receive antenna, the first transmit antenna and a third initial channel estimation value between the second receiving antenna and the second receiving antenna, and a fourth initial channel estimation value between the second transmitting antenna and the second receiving antenna.

Wherein, the symbol timing deviation determination module includes:

a fourth determination unit, configured to obtain received signals from the third subcarrier and the fourth subcarrier according to the first receiving antenna and the second receiving antenna, and the first transmitting antenna and the second transmitting antenna on the third subcarrier the transmission signal sent by the carrier and the fourth sub-carrier to determine the second channel estimation function;

a calculation unit, configured to calculate the initial symbol timing offset corresponding to each group of subcarriers according to the first channel estimation function and the second channel estimation function of each group of subcarriers;

A fifth determining unit, configured to determine the target symbol timing offset by using the initial symbol timing offset corresponding to each group of subcarriers.

The fifth determining unit is specifically configured to: calculate the average value of the initial symbol timing deviation of each group of subcarriers, and use the average value as the target symbol timing deviation.

及估计值确定规则，对初始信道估计值进行相位校正，得到最终的目标信道估计值；其中，所述估计值确定规则为：Wherein, the second estimated value determination module is specifically configured to: utilize the target symbol timing offset

and the estimation value determination rule, phase correction is performed on the initial channel estimation value to obtain the final target channel estimation value; wherein, the estimation value determination rule is:

为所述第一发送天线与所述第一接收天线间的第一目标信道估计值，

为所述第二发送天线与所述第一接收天线间的第二目标信道估计值，e为自然常数，N为子载波的总数，k为子载波的序号，

为所述第一发送天线与所述第一接收天线间的第一初始信道估计值，

为所述第二发送天线与所述第一接收天线间的第二初始信道估计值，

为所述第一发送天线与所述第二接收天线间的第三目标信道估计值，

为所述第二发送天线与所述第二接收天线间的第一目标信道估计值，

为所述第一发送天线与所述第二接收天线间的第三初始信道估计值，

为所述第二发送天线与所述第二接收天线间的第四初始信道估计值。in,

is the estimated value of the first target channel between the first transmit antenna and the first receive antenna,

is the estimated value of the second target channel between the second transmitting antenna and the first receiving antenna, e is a natural constant, N is the total number of subcarriers, k is the sequence number of the subcarriers,

is the first initial channel estimation value between the first transmit antenna and the first receive antenna,

is the second initial channel estimation value between the second transmit antenna and the first receive antenna,

is the estimated value of the third target channel between the first transmit antenna and the second receive antenna,

is the estimated value of the first target channel between the second transmit antenna and the second receive antenna,

is the third initial channel estimation value between the first transmit antenna and the second receive antenna,

is the fourth initial channel estimation value between the second transmit antenna and the second receive antenna.

Referring to FIG. 9 , an embodiment of the present invention further discloses a schematic structural diagram of an electronic device, including:

memory 11 for storing computer programs;

The processor 12 is configured to implement the steps of the space-frequency block code-based channel estimation method described in any of the above method embodiments when executing the computer program.

In this embodiment, the device may be a PC (Personal Computer, personal computer), or may be a terminal device such as a smart phone, a tablet computer, a palmtop computer, and a portable computer.

The device may include a memory 11 , a processor 12 and a bus 13 .

The memory 11 includes at least one type of readable storage medium, including flash memory, hard disk, multimedia card, card-type memory (eg, SD or DX memory, etc.), magnetic memory, magnetic disk, optical disk, and the like. The memory 11 may in some embodiments be an internal storage unit of the device, such as a hard disk of the device. The memory 11 may also be an external storage device of the device in other embodiments, such as a plug-in hard disk, a smart memory card (SmartMedia Card, SMC), a Secure Digital (SD) card, a flash memory card ( Flash Card), etc. Further, the memory 11 may also include both an internal storage unit of the device and an external storage device. The memory 11 can not only be used to store application software installed in the device and various types of data, such as program codes for executing the channel estimation method, etc., but also can be used to temporarily store data that has been output or will be output.

In some embodiments, the processor 12 may be a central processing unit (Central Processing Unit, CPU), controller, microcontroller, microprocessor or other data processing chip for executing program codes or processing stored in the memory 11 Data, such as program code to perform channel estimation methods, etc.

The bus 13 may be a peripheral component interconnect (PCI for short) bus or an extended industry standard architecture (Extended industry standard architecture, EISA for short) bus or the like. The bus can be divided into address bus, data bus, control bus and so on. For ease of presentation, only one thick line is used in FIG. 9, but it does not mean that there is only one bus or one type of bus.

Further, the device may also include a network interface 14, and the network interface 14 may optionally include a wired interface and/or a wireless interface (such as a WI-FI interface, a Bluetooth interface, etc.), which is usually used between the device and other electronic devices Establish a communication connection.

Optionally, the device may further include a user interface 15, the user interface 15 may include a display (Display), an input unit such as a keyboard (Keyboard), and the optional user interface 15 may also include a standard wired interface and a wireless interface. Optionally, in some embodiments, the display may be an LED display, a liquid crystal display, a touch-sensitive liquid crystal display, an OLED (Organic Light-Emitting Diode, organic light-emitting diode) touch device, and the like. Among them, the display may also be appropriately referred to as a display screen or a display unit, for displaying information processed in the device and for displaying a visual user interface.

FIG. 9 only shows the device with the components 11-15. Those skilled in the art can understand that the structure shown in FIG. Either some components are combined, or different component arrangements.

Embodiments of the present invention further disclose a computer-readable storage medium, where a computer program is stored on the computer-readable storage medium, and when the computer program is executed by a processor, the space-frequency-based grouping described in any of the foregoing method embodiments is implemented The steps of the channel estimation method of the code.

Wherein, the storage medium may 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 various storage media that can store program codes medium.

The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments, and the same and similar parts between the various embodiments can be referred to each other.

The above description of the disclosed embodiments enables any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (5)

1. A channel estimation method based on space-frequency block code is characterized by comprising the following steps:

determining an initial channel estimation value by using receiving signals and transmitting signals of two adjacent subcarriers;

determining a target symbol timing deviation through the receiving signals and the sending signals of each group of subcarriers; wherein each group of subcarriers comprises four adjacent subcarriers; the four adjacent subcarriers comprise the two adjacent subcarriers;

carrying out phase correction on the initial channel estimation value by using the target symbol timing deviation to obtain a final target channel estimation value;

wherein, the determining the initial channel estimation value by using the received signals and the transmitted signals of two adjacent subcarriers comprises:

determining each group of subcarriers, wherein each group of subcarriers comprises a first subcarrier, a second subcarrier, a third subcarrier and a fourth subcarrier, the serial numbers of the subcarriers of which are sequentially increased;

taking a first subcarrier and a second subcarrier in each group of subcarriers as two adjacent subcarriers;

determining a first channel estimation function according to receiving signals acquired by a first receiving antenna and a second receiving antenna on a first subcarrier and a second subcarrier and sending signals sent by a first sending antenna and a second sending antenna on the first subcarrier and the second subcarrier;

determining an initial channel estimation value according to the first channel estimation function;

wherein, the determining the target symbol timing offset through the received signal and the transmitted signal of each group of subcarriers includes:

determining a second channel estimation function according to the received signals acquired by the first receiving antenna and the second receiving antenna on the third subcarrier and the fourth subcarrier and the sending signals sent by the first transmitting antenna and the second transmitting antenna on the third subcarrier and the fourth subcarrier;

calculating initial symbol timing deviation corresponding to each group of subcarriers according to the first channel estimation function and the second channel estimation function of each group of subcarriers;

calculating the average value of the initial symbol timing deviation of each group of subcarriers, and taking the average value as the target symbol timing deviation;

wherein, the phase correcting the initial channel estimation value by using the target symbol timing deviation to obtain a final target channel estimation value includes:

using the target symbol timing offset

An estimated value determining rule, which is used for carrying out phase correction on the initial channel estimated value to obtain a final target channel estimated value;

wherein the evaluation value determination rule is:

wherein H₁₁Is a first target channel estimate, H, between the first transmit antenna and the first receive antenna₂₁E is a natural constant, N is the total number of subcarriers, k is the serial number of the subcarriers,

for a first initial channel estimate between the first transmit antenna and the first receive antenna,

is a second initial channel estimate, H, between the second transmit antenna and the first receive antenna₁₂Is a third target channel estimate, H, between the first transmit antenna and the second receive antenna₂₂For a first target channel estimate between the second transmit antenna and the second receive antenna,

for a third initial channel estimate between the first transmit antenna and the second receive antenna,

is a fourth initial channel estimate between the second transmit antenna and the second receive antenna.

2. The channel estimation method of claim 1, wherein the initial channel estimation value comprises:

a first initial channel estimation value between the first transmitting antenna and the first receiving antenna, a second initial channel estimation value between the second transmitting antenna and the first receiving antenna, a third initial channel estimation value between the first transmitting antenna and the second receiving antenna, and a fourth initial channel estimation value between the second transmitting antenna and the second receiving antenna.

3. A channel estimation device based on space-frequency block codes, comprising:

a first estimated value determining module, configured to determine an initial channel estimated value by using received signals and transmitted signals of two adjacent subcarriers;

a symbol timing deviation determining module, configured to determine a target symbol timing deviation according to the received signal and the transmitted signal of each group of subcarriers; wherein each group of subcarriers comprises four adjacent subcarriers; the four adjacent subcarriers comprise the two adjacent subcarriers;

a second estimated value determining module, configured to perform phase correction on the initial channel estimated value by using the target symbol timing offset to obtain a final target channel estimated value;

wherein the first estimated value determining module comprises:

the device comprises a first determining unit, a second determining unit and a third determining unit, wherein the first determining unit is used for determining each group of subcarriers, and each group of subcarriers comprises a first subcarrier, a second subcarrier, a third subcarrier and a fourth subcarrier, the serial numbers of the subcarriers of which are sequentially increased;

an adjacent subcarrier determining unit, configured to use a first subcarrier and a second subcarrier in each group of subcarriers as two adjacent subcarriers;

a second determining unit, configured to determine a first channel estimation function according to received signals obtained by the first receiving antenna and the second receiving antenna at the first subcarrier and the second subcarrier and transmission signals sent by the first transmitting antenna and the second transmitting antenna at the first subcarrier and the second subcarrier;

a third determining unit, configured to determine an initial channel estimation value according to the first channel estimation function;

wherein the symbol timing offset determination module comprises:

a fourth determining unit, configured to determine a second channel estimation function according to received signals obtained by the first receiving antenna and the second receiving antenna at the third subcarrier and the fourth subcarrier and transmission signals sent by the first transmitting antenna and the second transmitting antenna at the third subcarrier and the fourth subcarrier;

a calculating unit, configured to calculate an initial symbol timing offset corresponding to each group of subcarriers according to the first channel estimation function and the second channel estimation function of each group of subcarriers;

a fifth determining unit, configured to calculate an average value of the initial symbol timing deviations of each group of subcarriers, and use the average value as the target symbol timing deviation;

wherein the second estimated value determining module is specifically configured to: using the target symbol timing offset

An estimated value determining rule, which is used for carrying out phase correction on the initial channel estimated value to obtain a final target channel estimated value; wherein the evaluation value determination rule is:

wherein H₁₁Is a first target channel estimate, H, between the first transmit antenna and the first receive antenna₂₁E is a natural constant, N is the total number of subcarriers, k is the serial number of the subcarriers,

for a first initial channel estimate between the first transmit antenna and the first receive antenna,

is a second initial channel estimate, H, between the second transmit antenna and the first receive antenna₁₂Is a third target channel estimate, H, between the first transmit antenna and the second receive antenna₂₂For a first target channel estimate between the second transmit antenna and the second receive antenna,

for a third initial channel estimate between the first transmit antenna and the second receive antenna,

is a fourth initial channel estimate between the second transmit antenna and the second receive antenna.

4. An electronic device, comprising:

a memory for storing a computer program;

a processor for implementing the steps of the space frequency block code based channel estimation method according to claim 1 or 2 when executing said computer program.

5. A computer-readable storage medium, characterized in that the computer-readable storage medium has stored thereon a computer program which, when being executed by a processor, carries out the steps of the space frequency block code based channel estimation method according to claim 1 or 2.

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