WO2016011633A1 - Frequency deviation residual error estimation method, apparatus and system - Google Patents

Abstract

Disclosed are a frequency deviation residual error estimation method, apparatus and system, which belong to the field of wireless communications. The apparatus comprises: a first generation unit for generating a data portion according to a short training field (STF), wherein the data portion includes M orthogonal frequency division multiplexing (OFDM) symbols; pilot frequency subcarriers are arranged in N OFDM symbols; a position, in a frequency domain, of the pilot frequency subcarrier of each OFDM symbol of the N OFDM symbols and a position, in the frequency domain, of a subcarrier used in the STF are the same; and 1≤N<M; a second generation unit for generating a radio frame, wherein the radio frame includes the STF and the data portion; and a sending unit for sending the radio frame to a receiving apparatus such that the receiving apparatus estimates a frequency deviation residual error of the data portion. The frequency deviation residual error estimation method, apparatus and system can solve the problem that each OFDM symbol of the data portion has a pilot frequency overhead, and realize the effect that at least one OFDM symbol does not have the pilot frequency overhead. The present invention is used for wireless communications.

Description

 TECHNICAL FIELD The present invention relates to the field of wireless communications, and in particular, to a frequency offset residual estimation method, apparatus, and system. Background Art In a wireless communication system, data is transmitted through a radio frame, and there is a frequency offset between a carrier frequency of a radio frame transmitted by a transmitting device and a carrier frequency of a radio frame received by a receiving device. In order to ensure the reliable transmission of data, it is necessary to accurately estimate the frequency offset and compensate the frequency offset residual. In the wireless communication standard, the WiFi (Wireless Fidelity) system uses OFDM (Orthogonal Frequency Division Multiplexing) technology for communication. In the communication process, frequency offset and frequency offset residual estimation are needed. And compensation.

 In the prior art, the radio frame includes a preamble and a data part, where the preamble includes an STF (Short Training Field), and the data part includes an OFDM symbol, and each of the OFDM symbols is set with a preset number. The pilot subcarrier, STF is used for frequency offset estimation, and the pilot subcarriers in the OFDM symbol of the data portion are used for frequency offset residual estimation. For example, in the IEEE 802.11ac standard, in the case where the channel bandwidth is 20 MHz (megahertz), 4 pilot subcarriers are set in each OFDM symbol of the data portion.

When the pilot overhead in an OFDM symbol is high, the number of data subcarriers in the OFDM symbol is small, and the data carrying capability is low. For example, in the IEEE802.11ac standard, when the channel bandwidth is 20 MHz, the number of valid subcarriers in the OFDM symbol of the data part is 56, and the number of effective subcarriers in which the pilot subcarriers are set is four. The pilot overhead for each OFDM symbol of the data portion is 4/56. The pilot subcarriers are disposed in each OFDM symbol of the data portion in the prior art, and thus there is a problem of pilot overhead for each OFDM symbol of the data portion. SUMMARY OF THE INVENTION In order to solve the problem that there is a pilot overhead in each OFDM symbol of a data part, an embodiment of the present invention provides a residual estimation method, apparatus, and system. The technical solution is as follows: In a first aspect, an embodiment of the present invention provides a frequency offset residual estimation apparatus, where the frequency offset residual estimation apparatus includes:

 a first generating unit, configured to generate a data part according to the STF, where the data part includes M orthogonal frequency division multiplexing OFDM symbols, where a pilot subcarrier is disposed in the N OFDM symbols, where the N OFDM symbols are The position of the pilot subcarrier of each OFDM symbol in the frequency domain is the same as the position of the subcarrier used in the STF in the frequency domain, and the N is an integer greater than or equal to 1 and less than the integer of M;

 a second generating unit, configured to generate a radio frame, where the STF and the data part are included in the radio frame;

 And a sending unit, configured to send the radio frame to the receiving apparatus, so that the receiving apparatus estimates a frequency offset residual of the data part according to pilot subcarriers in the N OFDM symbols.

 With reference to the first aspect, in a first implementation manner, the first generating unit includes: a setting module, configured to set a pilot in any one or two OFDM symbols in the data part according to the STF Subcarrier.

 With reference to the first aspect, in a second implementation manner, the setting module includes: a setting submodule, configured to set a pilot subcarrier in a first OFDM symbol in the data part according to the STF.

 In a second aspect, an embodiment of the present invention provides a frequency offset residual estimation apparatus, where the frequency offset residual estimation apparatus includes:

 a receiving unit, configured to receive a radio frame sent by the transmitting device, where the radio frame includes an STF and a data part, where the data part is generated according to the STF, where the data part includes M OFDM symbols, where N a pilot subcarrier is disposed in the OFDM symbol, and a position of the pilot subcarrier of each of the N OFDM symbols in the frequency domain is the same as a position of the subcarrier used in the STF in the frequency domain, The N is an integer greater than or equal to 1 and less than the M;

 And an estimating unit, configured to estimate a frequency offset residual of the data portion according to pilot subcarriers in the N OFDM symbols.

 With reference to the second aspect, in a first implementation manner, a pilot subcarrier is disposed in any one or two OFDM symbols in the data portion.

 With reference to the second aspect, in a second implementation manner, a pilot subcarrier is disposed in a first OFDM symbol in the data portion.

In a third aspect, an embodiment of the present invention provides a frequency offset residual estimation method, where the frequency offset residual estimation Methods include:

 Generating a data portion according to the STF, where the data portion includes M OFDM symbols, where a pilot subcarrier is disposed in the N OFDM symbols, and a pilot subcarrier of each of the N OFDM symbols is in a frequency domain The position is the same as the position of the subcarrier used in the STF in the frequency domain, and the N is an integer greater than or equal to 1 and smaller than the M;

 Generating a radio frame, where the STF and the data portion are included in the radio frame;

 Transmitting the radio frame to a receiving device, so that the receiving device estimates a frequency offset residual of the data portion based on pilot subcarriers in the N OFDM symbols.

 In combination with the third aspect, in the first implementable manner, the data part is generated according to the STF, and includes:

 The pilot subcarriers are set in any one or two of the OFDM symbols in the data portion according to the STF.

 With reference to the third aspect, in a second implementation manner, the setting, by the STF, the pilot subcarriers in any one or two OFDM symbols in the data part, including:

 The pilot subcarrier is set in the first OFDM symbol in the data portion according to the STF. In a fourth aspect, an embodiment of the present invention provides a frequency offset residual estimation method, where the frequency offset residual estimation method includes:

 And receiving, by the transmitting device, a radio frame, where the radio frame includes an STF and a data part, where the data part is generated according to the STF, where the data part includes M OFDM symbols, where N OFDM symbols are set a pilot subcarrier, wherein a position of a pilot subcarrier of each OFDM symbol in the frequency domain is the same as a position of a subcarrier used in the STF in a frequency domain, and the N is greater than Or an integer equal to 1 and less than the M;

 The frequency offset residual of the data portion is estimated based on the pilot subcarriers in the N OFDM symbols. With reference to the fourth aspect, in a first implementation manner, a pilot subcarrier is disposed in any one or two OFDM symbols in the data portion.

 In conjunction with the fourth aspect, in a second implementation manner, a pilot subcarrier is disposed in a first OFDM symbol in the data portion.

 In a fifth aspect, an embodiment of the present invention provides a frequency offset residual estimation apparatus, where the frequency offset residual estimation apparatus includes:

a processor, configured to generate a data part according to the STF, where the data part includes M OFDM symbols, where a pilot subcarrier is disposed in the N OFDM symbols, where the N OFDM symbols are The position of the pilot subcarrier of each OFDM symbol in the frequency domain is the same as the position of the subcarrier used in the STF in the frequency domain, and the N is an integer greater than or equal to 1 and smaller than the integer of M;

 The processor is further configured to generate a radio frame, where the radio frame includes the STF and the data portion;

 And a transmitter, configured to send the radio frame to a receiving device, so that the receiving device estimates a frequency offset residual of the data portion according to pilot subcarriers in the N OFDM symbols.

 With reference to the fifth aspect, in a first implementation manner, the processor is configured to set a pilot subcarrier in any one or two OFDM symbols in the data part according to the STF.

 With reference to the fifth aspect, in a second implementation manner, the processor is configured to set a pilot subcarrier in a first 0 FDM symbol in the data part according to the STF.

 In a sixth aspect, an embodiment of the present invention provides a frequency offset residual estimation apparatus, where the frequency offset residual estimation apparatus includes:

 a receiver, configured to receive a radio frame sent by the transmitting device, where the radio frame includes an STF and a data part, where the data part is generated according to the STF, where the data part includes M OFDM symbols, where N a pilot subcarrier is disposed in the OFDM symbol, and a position of the pilot subcarrier of each of the N OFDM symbols in the frequency domain is the same as a position of the subcarrier used in the STF in the frequency domain, The N is an integer greater than or equal to 1 and less than the M;

 And a processor, configured to estimate a frequency offset residual of the data portion according to pilot subcarriers in the N OFDM symbols.

 In conjunction with the sixth aspect, in a first implementation manner, a pilot subcarrier is disposed in any one or two OFDM symbols in the data portion.

 In conjunction with the sixth aspect, in a second implementation manner, a pilot subcarrier is disposed in a first OFDM symbol in the data portion.

 In a seventh aspect, the present invention provides a frequency offset residual estimation system, including:

 Any of the frequency offset residual estimating devices of the first aspect;

 And any of the frequency offset residual estimation devices of the second aspect.

 In an eighth aspect, the present invention provides a frequency offset residual estimation system, including:

 A frequency offset residual estimation device according to the fifth aspect;

 And any of the frequency offset residual estimation devices described in the sixth aspect.

Embodiments of the present invention provide a frequency offset residual estimation method, apparatus, and system, where a transmitting device generates a data portion according to an STF, where the data portion includes M OFDM symbols, where, N OFDM symbols The pilot subcarrier is set in the number, and the pilot subcarrier is not set in the MN OFDM symbols of the data part, so at least one OFDM symbol in the data part has no pilot overhead. BRIEF DESCRIPTION OF THE DRAWINGS In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly described below. It is obvious that the drawings in the following description are only the present invention. For some embodiments, other drawings may be obtained from those skilled in the art without any inventive effort.

 1 is a schematic structural diagram of a radio frame according to an embodiment of the present invention;

 2 is a schematic structural diagram of a frequency offset residual estimation apparatus according to an embodiment of the present invention; FIG. 3 is a schematic structural diagram of a first generation unit of a frequency offset residual estimation apparatus according to an embodiment of the present invention;

 4 is a schematic structural diagram of a setting module of a first generating unit of a frequency offset residual estimating apparatus according to an embodiment of the present invention;

 FIG. 5 is a schematic structural diagram of another frequency offset residual estimation apparatus according to an embodiment of the present invention; FIG. 6 is a flowchart of a frequency offset residual estimation method according to an embodiment of the present invention;

 FIG. 7 is a flowchart of another method for estimating a frequency offset residual according to an embodiment of the present invention;

 FIG. 8 is a flowchart of still another frequency offset residual estimation method according to an embodiment of the present invention; FIG.

 FIG. 9 is a schematic structural diagram of an STF according to an embodiment of the present invention; FIG.

 FIG. 10 is a schematic structural diagram of a data part according to an embodiment of the present invention;

 FIG. 11 is a flowchart of frequency offset estimation according to an embodiment of the present invention;

 12 is a schematic diagram of throughput performance of a wireless communication system according to an embodiment of the present invention; FIG. 13 is a schematic structural diagram of still another frequency offset residual estimation apparatus according to an embodiment of the present invention; FIG. 14 is an implementation of the present invention. Another schematic diagram of the structure of the frequency offset residual estimation device provided by the example. DETAILED DESCRIPTION OF THE EMBODIMENTS In order to make the objects, technical solutions, and advantages of the present invention more comprehensible, the embodiments of the present invention will be further described in detail below.

The wireless communication system includes a transmitting device and a receiving device. The transmitting device and the receiving device communicate with each other through a wireless frame. Referring to FIG. 1, a wireless frame according to an embodiment of the present invention is shown. Schematic. The radio frame includes: a traditional preamble, a control field, a downlink subframe, and an uplink subframe. The structure of the conventional preamble is the same as that of the prior art. The embodiment of the present invention does not further describe the present invention. The downlink subframe and the uplink subframe include a preamble 01 and a data portion 02, where the preamble 01 includes an STF, an LTF. (Long Training Field, Long Training Field) and SIG (Signaling, Signaling Field), the data portion 02 may include downlink multi-user data, downlink single-user data, uplink multi-user data, and uplink single-user data, which need to be described above. The data portion 02 is composed of OFDM symbols.

 The embodiment of the present invention provides a frequency offset residual estimation apparatus 20. As shown in FIG. 2, the frequency offset residual estimation apparatus 20 includes: a first generation unit 201, a second generation unit 202, and a transmission unit 203.

 a first generating unit 201, configured to generate a data part according to the STF, where the data part includes M OFDM symbols, where a pilot subcarrier is set in the N OFDM symbols, and a pilot subcarrier of each OFDM symbol in the N OFDM symbols The position in the frequency domain is the same as the position of the subcarrier used in the STF in the frequency domain, and N is an integer greater than or equal to 1 and less than M.

 The second generating unit 202 is configured to generate a radio frame, where the STF and the data part are included in the radio frame. The sending unit 203 is configured to send the radio frame to the receiving device, so that the receiving device estimates the frequency offset residual of the data portion according to the pilot subcarrier in the N OFDM symbols.

 In summary, the first generating unit generates a data part according to the STF, where the data part includes M OFDM symbols, where the pilot subcarriers are set in the N OFDM symbols, and the MN OFDM symbols in the data part are not set. Frequency subcarriers, so at least one OFDM symbol in the data portion has no pilot overhead.

 Specifically, as shown in FIG. 3, the first generating unit 201 may include: a setting module 2011. The setting module 2011 is configured to set a pilot subcarrier in any one or two OFDM symbols in the data part according to the STF.

 As shown in FIG. 4, the setting module 2011 may further include: setting a sub-module 20111.

 The setting sub-module 20111 is configured to set a pilot sub-carrier in the first OFDM symbol in the data part according to the STF.

In summary, the first generating unit generates a data part according to the STF, where the data part includes M OFDM symbols, where the pilot subcarriers are set in the N OFDM symbols, and the MN OFDM symbols in the data part are not set. Frequency subcarriers, so at least one OFDM symbol in the data portion has no pilot overhead. The embodiment of the present invention provides a frequency offset residual estimation apparatus 30. As shown in FIG. 5, the frequency offset residual estimation is performed. The metering device 30 includes: a receiving unit 301 and an estimating unit 302.

 The receiving unit 301 is configured to receive a radio frame sent by the transmitting device, where the radio frame includes an STF and a data part, where the data part is generated according to the STF, and the data part includes M OFDM symbols, where the pilot is set in the N OFDM symbols Subcarrier, the position of the pilot subcarrier of each OFDM symbol in the N OFDM symbols in the frequency domain is the same as the position of the subcarrier used in the STF in the frequency domain, and N is an integer greater than or equal to 1 and less than M .

 The estimating unit 302 is configured to estimate a frequency offset residual of the data portion according to the pilot subcarriers in the N OFDM symbols.

 It should be noted that a pilot subcarrier is disposed in any one or two OFDM symbols in the data part. In an actual application, a pilot subcarrier is disposed in the first OFDM symbol in the data part.

 In summary, the receiving unit receives the radio frame sent by the transmitting device, where the radio frame includes an STF and a data part, where the data part includes M OFDM symbols, where the pilot subcarriers are set in the N OFDM symbols, and the data is The pilot subcarriers are not set in some MN OFDM symbols, so at least one OFDM symbol in the data portion has no pilot overhead.

 The frequency offset residual estimation apparatus provided by the embodiment of the present invention can be applied to the frequency offset residual estimation method described below. The working flow and working principle of each unit in the embodiment of the present invention can be referred to the description in the following embodiments. An embodiment of the present invention provides a frequency offset residual estimation method. As shown in FIG. 6, the method includes: Step 401: Generate a data part according to an STF, where the data part includes M OFDM symbols, where N OFDM symbols are set Pilot subcarrier, the position of the pilot subcarrier of each OFDM symbol in the N OFDM symbols in the frequency domain is the same as the position of the subcarrier used in the STF in the frequency domain, and N is greater than or equal to 1 and less than M The integer.

 Step 402: Generate a radio frame, where the STF and the data part are included in the radio frame.

 Step 403: Send the radio frame to the receiving device, so that the receiving device estimates the frequency offset residual of the data portion according to the pilot subcarriers in the N OFDM symbols.

 It should be noted that generating the data part according to the STF may include: setting a pilot subcarrier in any one or two OFDM symbols in the data part according to the STF, in actual application, according to the first OFDM symbol in the data part of the STF The pilot subcarrier is set.

In summary, the transmitting device generates a data portion according to the STF, and the data portion includes M OFDM portions. The symbol, in which the pilot subcarriers are disposed in the N OFDM symbols, the pilot subcarriers are not set in the MN OFDM symbols of the data portion, and therefore, at least one OFDM symbol in the data portion has no pilot overhead. The embodiment of the present invention provides a frequency offset residual estimation method. As shown in FIG. 7, the method includes: Step 501: Receive a radio frame sent by a transmitting device, where the radio frame includes an STF and a data part, and the data part is generated according to the STF. The data portion includes M OFDM symbols, where the pilot subcarriers are disposed in the N OFDM symbols, and the positions of the pilot subcarriers of each of the N OFDM symbols in the frequency domain are used in the STF. The subcarriers have the same position in the frequency domain, and N is an integer greater than or equal to 1 and less than M.

 It should be noted that pilot subcarriers are disposed in any one or two OFDM symbols in the data portion. In practical applications, pilot subcarriers are disposed in the first OFDM symbol in the data portion.

 Step 502: Estimate the frequency offset residual of the data portion according to the pilot subcarriers in the N OFDM symbols.

 In summary, the receiving device receives a radio frame sent by the transmitting device, where the radio frame includes an STF and a data portion, where the data portion includes M OFDM symbols, where the pilot subcarriers are set in the N OFDM symbols, and the data is The pilot subcarriers are not set in some MN OFDM symbols, so at least one OFDM symbol in the data portion has no pilot overhead. An embodiment of the present invention provides a frequency offset residual estimation method. As shown in FIG. 8, the method includes: Step 601: A transmitting device generates an STF.

 The process of generating the STF by the transmitting device can refer to the prior art, which is not described in the embodiment of the present invention.

 For example, FIG. 9 shows a schematic structural diagram of an STF generated by a transmitting device, which is generated according to the IEEE802.11ac standard, and includes: a null subcarrier 701, a blank subcarrier 702, and a used subcarrier 703. The used subcarrier 703 may be a pilot subcarrier, that is, a subcarrier into which a pilot is inserted, where the null subcarrier 701 is located in a frequency domain of the STF 70 as shown by a diamond-shaped square in FIG. On both sides, the blank subcarrier 702 is as shown by the blank square in FIG. 9, and the used subcarrier 703 is shown in the truncated square in FIG. 9, and the blank subcarrier 702 and the used subcarrier 703 are fixed. The intervals are arranged in the frequency domain.

Step 602: The transmitting device generates a data portion according to the STF. For example, the transmitting device may generate the data portion according to the position of the used subcarrier in the frequency domain in the STF, so that the generated data portion includes M OFDM symbols, where the pilot subcarriers are set in the N OFDM symbols. The position of the pilot subcarrier of each OFDM symbol in the N OFDM symbol is the same as the position of the subcarrier used in the STF in the frequency domain, and N is an integer greater than or equal to 1 and less than M, that is, 1 ≤ N < M.

 As shown in FIG. 10, it provides a schematic structural diagram of a data portion of a radio frame. The data portion 80 is generated according to the STF 70 in FIG. 9 in the case where the channel bandwidth is 20 MHz, and the data portion 80 includes The invalid subcarrier 801, the data subcarrier 802, and the pilot subcarrier 803, the null subcarrier 801 is shown by a diamond-shaped square in FIG. 10, and the data subcarrier 802 is shown by a dotted square in FIG. The frequency subcarrier 803 is shown as a trellis square in FIG. 10, and the data portion 80 includes M OFDM symbols, wherein a pilot subcarrier 803 is disposed in the N OFDM symbols, and the pilot subcarrier 803 is in the frequency domain. The upper position corresponds to the position of the subcarrier 703 in the STF 70 in the frequency domain.

 It should be noted that, in the embodiment of the present invention, the pilot subcarriers may be set in the multiple OFDM symbols of the data part, and the OFDM symbols of the pilot subcarriers may or may not be adjacent to each other. This is not limited.

 In particular, in order to reduce the pilot overhead of the entire data frame, pilot subcarriers may be set in a small number of OFDM symbols, for example, pilot subcarriers are set in any one or two OFDM symbols in the data portion. In practical applications, A pilot subcarrier may be set in the first OFDM symbol in the data portion. For example, as shown in Table 1, Table 1 describes the pilot overhead of the data part corresponding to different channel bandwidths in the prior art. Taking IEEE802.11ac as an example, it is assumed that the OFDM symbol of the data part is 20, When the channel bandwidth is 20 MHz, the number of valid subcarriers in each OFDM symbol of the data part is 56, and 4 pilot subcarriers are set in each OFDM symbol of the data part, and the pilot overhead of the data part is 4/56. =7.14%; Similarly, in the case of a channel bandwidth of 40 MHz, 6 pilot subcarriers are set in each OFDM symbol of the data part, and the pilot overhead of the data part is 5.17%; in the case of a channel bandwidth of 80 MHz, There are 8 pilot subcarriers in each OFDM symbol in the data part, and the pilot overhead of the data part is 3.28%. In the case of a channel bandwidth of 160 MHz, 16 pilots are set in each OFDM symbol of the data part. Carrier, the pilot portion of the data portion is 3.2%.

 Table 1

The pilot overhead of the pilot data portion in each OFDM symbol of the channel band 笕 data portion Number of subcarriers

 20MHz 4 7.14%

 40MHz 6 5.17%

 80MHz 8 3.28%

 160MHz 16 3.2%

 Table 2 shows the pilot overhead of the data portion corresponding to the frequency offset residual estimation method provided by the embodiment of the present invention under different channel bandwidths. For example, assuming that the data portion includes 20 OFDM symbols, in the case of a channel bandwidth of 20 MHz, the number of effective subcarriers in each OFDM symbol of the data portion is 56, and 12 of the first OFDM symbols in the data portion are set. Pilot subcarrier, the pilot overhead of the data part is 12/(56*20)=1.07%. Similarly, in the case of a channel bandwidth of 40 MHz, 24 pilots are set in the first OFDM symbol of the data part. The pilot overhead of the data part is 1.03%. In the case of the channel bandwidth of 80 MHz, 48 pilot subcarriers are set in the first OFDM symbol of the data part, and the pilot overhead of the data part is 0.984%; In the case of a channel bandwidth of 160 MHz, 56 pilot subcarriers are set in the first OFDM symbol of the data portion, and the pilot overhead of the data portion is 0.96%. As can be seen from comparison with Table 1, the implementation of the present invention is implemented. The frequency offset residual estimation method provided by the example can effectively reduce the pilot overhead of the data part.

 Table 2

 Step 603: The transmitting device generates a radio frame according to the STF and the data part.

The transmitting device combines the STF and the data portion to generate a radio frame. For example, the transmitting device may combine the STF 70 in FIG. 9 and the data portion 80 in FIG. 10 to generate a radio frame, and the data portion of the radio frame includes M OFDMs. a symbol, where 12 pilot subcarriers are disposed in N OFDM symbols, and a position of a pilot subcarrier of each OFDM symbol in the frequency domain is in frequency with a subcarrier used in the STF The positions on the fields are the same, and N is an integer greater than or equal to 1 and less than M. Step 604: The transmitting device sends a radio frame to the receiving device.

 Step 605: The receiving device performs frequency offset estimation on the radio frame.

 For example, as shown in FIG. 11, the receiving apparatus may perform frequency offset estimation on the radio frame by using a differential phase estimation method, and the specific process includes:

 Step 6051: The receiving device performs initial frequency offset estimation on the radio frame.

In the wireless communication system provided by the embodiment of the present invention, the transmitting device includes multiple transmitting antennas, the receiving device includes multiple receiving antennas, and a multipath time varying channel exists between the tth transmitting antenna and the rth receiving antenna, During the transmission of the nth OFDM symbol, the channel is unchanged, and the calculation formula (1) of the received signal ^W in the time domain of the first receiving antenna of the receiving device at the ith sampling moment of the "first OFDM symbol" is:

y ^{ (ί) = _e ^„ _g

其中， =卜^， "'N-ij, j=[ X..,N_g -l] ^ N为 _0FDM中子载波的个数， N_g 为 OFDM的 CP (Cyclic Prefix,循环前缀） 长度， s为归一化频偏值， 为 发设装置的第 ^个发射天线到第 个接收天线在第"个 OFDM 符号对应多径时 变信道的第 ¹径的信道响应， ^τ 为第 t个发射天线到第 r个接收天线的第 Z径时 延， ^ ((n -l)(N + N_g) + i- )为第 t个发射天线的第"个 _0FDM符号经过发射 天线 t和接收天线 之间第 Z径信道时延后的第 个采样点的值， ^z^ ^W为第 个接 收天线在第"个 OFDM符号的第 ^ζ'个采样时刻对应的加性高斯白噪声。

Where Bu = ^, "'N-ij, j = [X .., N g -l] ^ N _0FDM is the number of subcarriers, N _g of an OFDM CP (Cyclic Prefix, Cyclic Prefix) length, s is the normalized frequency offset value of ^ transmit antennas hair set apparatus to the second receiving antenna multipath time-varying ^first diameter of the channel response of the channel at the "OFDM symbol corresponding to, ^[tau] is the t th transmitter The Zth path delay from the antenna to the rth receiving antenna, ^((n -l)(N + N _g ) + i- ) is the "the _{0th DM} symbol of the tth transmitting antenna passes through the transmitting antenna t and the receiving antenna value of the sampling points of the first delayed-path channel between Z, ^z ^ ^W for the first receive antenna at the first sampling time ^ζ 'of "OFDM symbol corresponding to additive white gaussian noise.

其中， ' = L_ "^_ij ， 为接收天线的个数， 为 OFDM符号的个数， 为公式 （1) 中计算得到的 )^W， s为归一化频偏值。 The receiving device may determine the initial normalized carrier frequency offset estimation by using a CP-based frequency offset estimation method according to the relationship between the CP portion and the OFDM symbol in the OFDM symbol received by the receiving device, and determine the initial formula (2):

Wherein, '= L_ "^ _ij, is the number of receiving antennas, is the number of OFDM symbols for the equation calculated) ^W (1), s is the normalized frequency offset value.

In formula (2), the range of frequency offset needs to be guaranteed to be _0· ⁵ ≤ ≤0· ⁵ , and the corresponding phase range is: ('· + N) ≤ ;

才艮据归一化频偏和初始频率偏差之间的关系 = ^Δ / ， 可得初始频率偏差 S的范围为：

According to the relationship between the normalized frequency offset and the initial frequency deviation = ^Δ / , the range of the initial frequency deviation S is:

 _ 1 / 2 X / Hz ≤ Δ / ≤ 1 / 2 X / Hz.

 Step 6052: The receiving device performs pilot data buffering.

The OFDM signal of the current time domain received by all receiving antennas of the MIMO (Multi-input Multi-output)-OFDM system of the ^Ν τ root transmitting antenna and the ^NR root receiving antenna is removed by CP, and then subjected to DFT (Discrete) The Fourier Transform (Discrete Fourier Transform) module converts the frequency domain pilot subcarrier y, and finally updates the received pilot data buffer using the following formula (3):

j ， 表示 根发射天线、 根接收天线的 γ^ = γ γ° = γ (3) where y =

j , indicating the root transmit antenna and the root receive antenna

In a MIMO-OFDM system, all receiving antennas receive a removal of the CP after passing through the DFT module.

■ τ τ τ ' T

The pre-frequency domain OFDM symbol block, ^ [Pi ], ^{y W} [P ₂ ], , y ^W PN^l is the frequency domain received signal vector on the rth receive antenna, ^Α ^{= 1} '···'^ ^{_ Λ} ^ ¹ are a number of pilot subcarriers, wherein, ^(·) Γ denotes transpose demand variables in parentheses. Step 6053: The receiving device performs data preprocessing and phase calculation.

 After the data is preprocessed by the adjacent two pilot subcarriers stored in the pilot data buffer, the following phase values are calculated by combining the adjacent pilot subcarriers transmitted by the transmitting device:

Angle = arg{Y ⁽ ' ^l Y ⁽⁰ )

 Where, represents the phase value, (to take the phase of the variable in parentheses.

 Step 6054: The receiving device performs frequency offset residual estimation on the radio frame.

 Αττεά /

Based on the frequency offset estimation ^ε , the initial phase difference ^/4 can be obtained. The initial phase difference can be calculated according to the following formula (4):

 Times = round Α

其中， times 表示相位折叠数， ^^ W为四舍五入运算， 为时域上相邻 的设置有导频子载波的 OFDM符号之间间隔的 OFDM符号个数。

Where Times represents the number of phase folds, and ^^ W is a rounding operation, which is the number of OFDM symbols spaced between OFDM symbols with pilot subcarriers adjacent in the time domain.

Calculate three sets of phase candidate correction values of the phase value. If the frequency offset estimation s is a positive value, the candidate correction value ^Ω "^ ⁶ '· is selected to be added, that is, Angle ^ = angle + times x 2π;

Angle ₂ - angle + (times + \) 2π;

Angle ₃ - angle + (times - Ϊ) χ 2π;

If the frequency offset estimate s is negative, then the candidate correction value ^{ω Ζ£)} '· is selected to be subtracted, ie

 Angle = angle times x 2π

Angle ₂ - angle (times + \) 2π;

Angle ₃ - angle (times - Ϊ) χ 2π;

在三个绝对差值中获取最小的绝对差值， 将该最小的绝对差值所对应的修 订相位值^ g^.作为最终修订的相位值用于后续计算， 该相位值即为频偏残差， 即令 angle =

, angle₂ , angle₃ }， min{ · }表示取括号内数值的最小值， 贝 angle即为频偏残差。 Calculate three absolute values based on the three sets of candidate phase values (5):

Obtaining the smallest absolute difference among the three absolute differences, and using the revised phase value corresponding to the minimum absolute difference ^ g^. as the final revised phase value for subsequent calculation, the phase value is the frequency offset Poor, that is, let angle =

, angle ₂ , angle ₃ }, min{ · } means taking the minimum value of the value in the parentheses, and the Bay angle is the frequency offset residual.

 The residual estimation method provided by the embodiment of the present invention can effectively improve the data throughput rate of the wireless communication system. For example, when the IEEE802.11ac standard is adopted and the channel bandwidth is 20 MHz, in the prior art, the data portion in the wireless frame is assumed. In the M OFDM symbol, the pilot subcarrier is set, and the OFDM symbol has a pilot overhead. In the embodiment of the present invention, the data part includes M OFDM symbols, where the pilot is set in the N OFDM symbols. Subcarriers, there are no pilot subcarriers set in the ij MN OFDM symbols, so at least one OFDM symbol in the data portion has no pilot overhead, which improves the data carrying capability of the OFDM symbol, assuming the first part of the data portion. The pilot subcarrier is set in the OFDM symbol, and the overall pilot overhead of the data portion is almost negligible with respect to the entire data portion. Therefore, the frequency offset residual estimation method provided by the embodiment of the present invention is applied to the wireless communication system. In the system, the loss of throughput performance of the system is also relatively small.

Table 3 is a simulation parameter table of throughput performance, in which IFFT (Inverse Fast Fourier Transform) represents fast 4 humiliation inverse transform, MCS (Modulation and Coding Scheme) modulation And coding strategy, Tx (Transmit, Transmit) represents the transmit antenna in the wireless communication system, Rx (Receive) represents the receive antenna in the wireless communication system, ppm (Parts Per Million, per million units) is the frequency offset residual The unit of value, CHD NLOS (Channel D Non Line Of Sight, channel model name) is the channel model used for the simulation, and ms (Millisecond, milliseconds) is the time unit. table 3

 As shown in Table 3, it is assumed that the number of receiving antennas of the transmitting antenna and the receiving device of the transmitting device is one; the number of IFFT transform points is 64; the length of the CP of the radio frame is 16; the residual value of the frequency offset is lOppm; The method adopted by the algorithm is differential phase method or ideal frequency offset estimation method; the channel type of wireless communication is CHD NLOS; the modulation mode of wireless frame is set to 8; the length of wireless frame is 5.464 ms, and the data part of the radio frame includes 1361 OFDM symbols, the number of effective subcarriers per OFDM symbol is 56, and the frequency offset residual estimation method provided by the embodiment of the present invention is used, and 12 pilot subcarriers are set in the first OFDM symbol of the data part. The number of data subcarriers of the OFDM symbol is 44. In the prior art, the number of data subcarriers per OFDM symbol of the data part is 52. According to the frequency offset residual estimation method provided by the embodiment of the present invention, the pilot OFDM symbol is set in the first OFDM symbol of the data part, and the data part is in the 1360 OFDM symbols except the first OFDM symbol. The number of valid data subcarriers per OFDM symbol is 56, and the data carrying capacity of the 1360 OFDM symbols is improved compared to the prior art.

FIG. 12 is a schematic diagram showing the throughput performance results of the broadband WiFi corresponding to Table 3. Wherein, the solid lines A0, A1, A2, A3, A4, A5, A6, and A7 indicate that the MCS is MCS0, MCS1, MCS2, MCS3, MCS4, MCS5, MCS6, and MCS7, respectively, and are set in the OFDM symbol of the data part. For the case of continuous pilot subcarriers, the throughput performance of the corresponding wireless communication system when using the ideal frequency offset estimation method; the dotted lines B0, Bl, B2, B3, B4, B5, B6 and B7 respectively indicate that the MCS is MCS0, MCS1, MCS2, MCS3, MCS4, MCS5, MCS6, and MCS7, when the pilot subcarrier is set in the first OFDM symbol of the data part, the throughput performance of the corresponding wireless communication system is determined by the differential phase estimation method. schematic diagram. As can be seen from Figure 12:

 When the MCS is any one of the MCS 0, the MCS 1 and the MCS2, the throughput performance of the wireless communication system corresponding to the pilot subcarrier is set in the first OFDM symbol of the data part, which is superior to the data part in the prior art. The throughput performance of the wireless communication system corresponding to the continuous pilot subcarrier is set in the OFDM symbol.

 When the MCS is any one of the MCS 4, the MCS5, the MCS6, and the MCS7, the throughput of the wireless communication system corresponding to the pilot subcarrier is set in the first OFDM symbol of the data part under the condition of medium and low SNR. The performance is basically the same as the throughput performance of the wireless communication system corresponding to the prior art; when the signal-to-noise ratio is sufficiently high, the throughput of the wireless communication system corresponding to the pilot subcarrier is set in the first OFDM symbol of the data portion. Performance is better than the throughput performance of the system corresponding to the prior art.

 In summary, the data portion is generated according to the STF, and the data portion includes M OFDM symbols, where the pilot subcarriers are disposed in the N OFDM symbols, and the pilot subcarriers are not set in the MN OFDM symbols in the data portion. Therefore, at least one OFDM symbol in the data portion has no pilot overhead. Further, in the data part, there is no pilot overhead in at least one OFDM symbol, which improves the capability of the OFDM symbol to carry data, thereby improving the data throughput of the wireless communication system. The embodiment of the present invention provides a frequency offset residual estimation apparatus 90. As shown in FIG. 13, the frequency offset residual estimation apparatus 90 includes: a processor 901 and a transmitter 902.

 The processor 901 is configured to generate a data part according to the STF, where the data part includes M OFDM symbols, where the pilot subcarriers are set in the N OFDM symbols, and the pilot subcarriers of each OFDM symbol in the N OFDM symbols are in the frequency The position on the domain is the same as the position of the subcarrier used in the STF in the frequency domain, and N is an integer greater than or equal to 1 and less than M.

The processor 901 is further configured to generate a radio frame, where the radio frame includes an STF and a data part. The transmitter 902 is configured to send the radio frame to the receiving device, so that the receiving device estimates the frequency offset residual of the data portion according to the pilot subcarrier in the N OFDM symbols. In summary, the processor generates a data part according to the STF, where the data part includes M OFDM symbols, where pilot subcarriers are set in the N OFDM symbols, and no pilots are set in the MN OFDM symbols of the data part. Carrier, therefore, at least 1 OFDM symbol in the data portion has no pilot overhead.

 The processor 901 is further configured to: set the pilot subcarrier in any one or two OFDM symbols in the data part according to the STF, in actual application, according to the STTF in the first OFDM symbol in the data part. Set the pilot subcarriers.

 In summary, the processor generates a data part according to the STF, where the data part includes M OFDM symbols, where pilot subcarriers are set in the N OFDM symbols, and no pilots are set in the MN OFDM symbols of the data part. Carrier, so there is no pilot overhead in at least 1 OFDM symbol in the data portion. The embodiment of the present invention provides a frequency offset residual estimation apparatus 100. As shown in FIG. 14, the frequency offset residual estimation apparatus 100 includes: a receiver 1001 and a processor 1002.

 The receiver 1001 is configured to receive a radio frame sent by the transmitting device, where the radio frame includes an STF and a data part, where the data part is generated according to the STF, and the data part includes M OFDM symbols, where the pilot is set in the N OFDM symbols Subcarrier, the position of the pilot subcarrier of each OFDM symbol in the N OFDM symbols in the frequency domain is the same as the position of the subcarrier used in the STF in the frequency domain, and N is an integer greater than or equal to 1 and less than M .

 The processor 1002 is configured to estimate a frequency offset residual of the data portion of the pilot subcarrier in the N OFDM symbols.

 It should be noted that pilot subcarriers are disposed in any one or two OFDM symbols in the data portion. In practical applications, pilot subcarriers are disposed in the first OFDM symbol in the data portion.

 In summary, the receiver receives a radio frame transmitted by the transmitting device, where the radio frame includes a data portion, and the data portion includes M OFDM symbols, where the pilot subcarriers are set in the N OFDM symbols, and the MN of the data portion The pilot subcarriers are not set in the OFDM symbols, so at least one OFDM symbol in the data portion has no pilot overhead.

An embodiment of the present invention provides a frequency offset residual estimation system, including: a transmitting apparatus and a receiving apparatus, where the transmitting apparatus includes the frequency offset residual estimating apparatus 20 shown in FIG. 2, and the receiving apparatus includes the frequency offset residual shown in FIG. Estimation device 30. An embodiment of the present invention provides a frequency offset residual estimation system, including: a transmitting apparatus and a receiving apparatus, where the transmitting apparatus includes a frequency offset residual estimating apparatus 90 as shown in FIG. 13, and the receiving apparatus includes the frequency offset residual shown in FIG. Difference estimation device 100.

 A person skilled in the art may understand that all or part of the steps of implementing the above embodiments may be completed by hardware, or may be instructed by a program to execute related hardware, and the program may be stored in a computer readable storage medium. The storage medium mentioned may be a read only memory, a magnetic disk or an optical disk or the like.

 The above is only the preferred embodiment of the present invention, and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., which are within the spirit and scope of the present invention, should be included in the protection of the present invention. Within the scope.

Claims

Claim A frequency offset residual estimation apparatus, wherein the frequency offset residual estimation apparatus includes: a first generation unit, configured to generate a data part according to a short training field STF, where the data part includes M orthogonalities a frequency division multiplexed OFDM symbol, where pilot subcarriers are disposed in N OFDM symbols, and a position of a pilot subcarrier of each OFDM symbol in the frequency domain is used in the STF The subcarriers have the same position in the frequency domain, and the N is an integer greater than or equal to 1 and smaller than the M;  a second generating unit, configured to generate a radio frame, where the STF and the data part are included in the radio frame;  And a sending unit, configured to send the radio frame to the receiving apparatus, so that the receiving apparatus estimates a frequency offset residual of the data part according to pilot subcarriers in the N OFDM symbols. 2. The frequency offset residual estimating apparatus according to claim 1, wherein:  The first generating unit includes:  And a setting module, configured to set a pilot subcarrier in any one or two OFDM symbols in the data part according to the STF. 3. The frequency offset residual estimating apparatus according to claim 2, wherein:  The setting module includes:  And a setting submodule, configured to set a pilot subcarrier in the first OFDM symbol in the data part according to the STF. 4. A frequency offset residual estimation apparatus, comprising:  a receiving unit, configured to receive a radio frame sent by the transmitting device, where the radio frame includes an STF and a data part, where the data part is generated according to the STF, where the data part includes M OFDM symbols, where N a pilot subcarrier is disposed in the OFDM symbol, where a position of a pilot subcarrier of each 0 FD M symbol in the frequency domain is in a frequency domain and a subcarrier used in the S TF is in a frequency domain The position is the same, and the N is an integer greater than or equal to 1 and less than the M; An estimating unit, configured to estimate the data part according to pilot subcarriers in the N OFDM symbols Frequency offset residual 5. The frequency offset residual estimating apparatus according to claim 4, wherein:  A pilot subcarrier is disposed in any one or two of the OFDM symbols in the data portion. 6. The frequency offset residual estimating apparatus according to claim 5, wherein:  A pilot subcarrier is disposed in the first OFDM symbol in the data portion. 7. A frequency offset residual estimation method, comprising:  Generating a data portion according to the STF, where the data portion includes M OFDM symbols, where a pilot subcarrier is disposed in the N OFDM symbols, and a pilot subcarrier of each of the N OFDM symbols is in a frequency domain The position is the same as the position of the subcarrier used in the STF in the frequency domain, and the N is an integer greater than or equal to 1 and smaller than the M;  Generating a radio frame, where the STF and the data portion are included in the radio frame;  Transmitting the radio frame to a receiving device, so that the receiving device estimates a frequency offset residual of the data portion based on pilot subcarriers in the N OFDM symbols. The method according to claim 7, wherein the generating the data portion according to the STF comprises:  The pilot subcarriers are set in any one or two of the OFDM symbols in the data portion according to the STF. The method according to claim 8, wherein the setting a pilot subcarrier in any one or two OFDM symbols in the data part according to the STF includes:  A pilot subcarrier is set in a first OFDM symbol in the data portion according to the STF. 10. A frequency offset residual estimation method, comprising: Receiving, by the transmitting device, a radio frame, where the radio frame includes an STF and a data part, where the data part is generated according to the STF, and the data part includes M OFDM symbols, where N OFDM symbols are set a pilot subcarrier, a position of a pilot subcarrier of each of the N OFDM symbols in a frequency domain and a position of a subcarrier used in the STF in a frequency domain Similarly, the N is an integer greater than or equal to 1 and less than the M;  Estimating a frequency offset residual of the data portion based on pilot subcarriers in the N OFDM symbols. 11. The method of claim 10, wherein  A pilot subcarrier is disposed in any one or two of the OFDM symbols in the data portion. 12. The method of claim 11 wherein:  A pilot subcarrier is disposed in the first OFDM symbol in the data portion. A frequency offset residual estimation apparatus, wherein the frequency offset residual estimation apparatus includes: a processor, configured to generate a data part according to an STF, where the data part includes M OFDM symbols, where, a pilot subcarrier is disposed in the OFDM symbol, and a position of the pilot subcarrier of each of the N OFDM symbols in the frequency domain is the same as a position of the subcarrier used in the STF in the frequency domain, The N is an integer greater than or equal to 1 and less than the M;  The processor is further configured to generate a radio frame, where the radio frame includes the STF and the data portion;  And a transmitter, configured to send the radio frame to the receiving device, so that the receiving device estimates a frequency offset residual of the data portion according to the pilot subcarrier in the N 0 FD M symbols. 14. The frequency offset residual estimating apparatus according to claim 13, wherein:  The processor is configured to set a pilot subcarrier in any one or two OFDM symbols in the data part according to the STF. 15. The frequency offset residual estimating apparatus according to claim 14, wherein:  The processor is configured to set a pilot subcarrier in a first OFDM symbol in the data part according to the STF. A frequency offset residual estimation apparatus, wherein the frequency offset residual estimation apparatus comprises: a receiver, configured to receive a radio frame transmitted by a transmitting apparatus, where the radio frame includes an STF and a data part, where The data portion is generated according to the STF, where the data portion includes M OFDM symbols, where a pilot subcarrier is disposed in the N OFDM symbols, where the N OFDM symbols are The position of the pilot subcarrier of each OFDM symbol in the frequency domain is the same as the position of the subcarrier used in the STF in the frequency domain, and the N is an integer greater than or equal to 1 and smaller than the integer of M;  And a processor, configured to estimate a frequency offset residual of the data portion according to the pilot subcarriers in the N 0 FD M symbols. 17. The frequency offset residual estimating apparatus according to claim 16, wherein:  A pilot subcarrier is disposed in any one or two of the OFDM symbols in the data portion. 18. The frequency offset residual estimating apparatus according to claim 17, wherein:  A pilot subcarrier is disposed in the first OFDM symbol in the data portion. 19. A frequency offset residual estimation system, comprising:  The frequency offset residual estimating apparatus according to any one of claims 1 to 3;  And a frequency offset residual estimating apparatus according to any one of claims 4 to 6. 20. A frequency offset residual estimation system, comprising:  A frequency offset residual estimating apparatus according to any one of claims 13 to 15;  And a frequency offset residual estimating apparatus according to any one of claims 16 to 18.