WO2012155463A1

WO2012155463A1 - A system synchronization method and device

Info

Publication number: WO2012155463A1
Application number: PCT/CN2011/081757
Authority: WO
Inventors: 李静
Original assignee: 中兴通讯股份有限公司
Priority date: 2011-05-17
Filing date: 2011-11-03
Publication date: 2012-11-22
Also published as: CN102790737B; CN102790737A

Abstract

The present invention relates to a synchronization method for an Orthogonal Frequency Division Multiplexing (OFDM) system, which comprises: finding the position corresponding to a time offset through the peak value searching of a pilot channel response; obtaining the frequency offset estimation value according to the phase difference between the time offset and a pilot signal; and performing synchronization for the OFDM system according to the time offset and the frequency offset estimation value. The present invention also provides a synchronization device. Application of the present invention solves the problem in the prior art that the computation of the time offset and frequency offset estimation value has a large amount of calculation and is inaccurate.

Description

一种***的同步方法及装置技术领域 System synchronization method and device

本发明涉及通信领域，特别地涉及一种 OFDM ( Orthogonal Frequency Division Multiplex , 正交频分复用） *** MIMO ( Multiple-Input Multiple-Output, 多输入多输出）时的同步方法及装置。背景技术 The present invention relates to the field of communications, and in particular, to a method and apparatus for synchronizing MIMO (Multiple Input Multiple-Output) (MIMO) in an OFDM (Orthogonal Frequency Division Multiplex) system. Background technique

OFDM ***作为三代以后的移动通信***，因其具有高效的频谱利用率和良好的抗多径能力而倍受瞩目，已经被广泛的应用在 WLAN ( Wireless Local Area Networks, 无线局域网 )、 DAB ( Digital Audio Broadcasting, 数字音频广播）、 DVB ( Digital Video Broadcasting , 数字视频广播）等。 IEEE802.16工作组在其制定的空中接口标准中就采用了 OFDM技术作为它的传输技术。 As a mobile communication system after three generations, OFDM system has attracted attention because of its high efficiency spectrum utilization and good anti-multipath capability. It has been widely used in WLAN (Wireless Local Area Networks), DAB (Digital). Audio Broadcasting, Digital Audio Broadcasting, DVB (Digital Video Broadcasting), etc. The IEEE 802.16 working group adopted OFDM technology as its transmission technology in its air interface standard.

MIMO技术是无线移动通信领域智能天线技术的重大突破，它利用空间中增加的传输信道，在发送端和接收端采用多天线同时发送信号，由于各发射天线同时发送的信号占用同一个频带，所以无需增加带宽，就能够成倍提高***容量和频谱利用率。 OFDM与 MIMO结合的***具有很高的传输速率，同时通过分集达到很强的可靠性。 MIMO technology is a major breakthrough in the smart antenna technology in the field of wireless mobile communications. It uses the increased transmission channel in space, and uses multiple antennas to transmit signals simultaneously at the transmitting end and the receiving end. Since the signals transmitted by the transmitting antennas simultaneously occupy the same frequency band, By increasing bandwidth, you can double your system capacity and spectrum utilization. Systems combining OFDM and MIMO have high transmission rates while achieving high reliability through diversity.

同步技术是实现 OFDM***的关键技术，包括时偏估计和频偏估计，通过时偏估计和频偏估计得出的时偏和频偏是反映***性能的重要参数。对于无线移动通信***来说，无线信号存在时变性，在传输过程中会出现无线信号的频率偏移，如多普勒频移，或者由于发射机与接收机载波频率之间存在的频率偏差，都会使得 OFDM***子载波之间的正交性遭到破坏，从而导致子信道间干扰，信号产生畸变，严重影响***性能。因此，同步包括时间同步、频率同步是***性能的重要保障。 Synchronization technology is the key technology to realize OFDM system, including time-offset estimation and frequency offset estimation. Time-shift and frequency offset obtained by time-offset estimation and frequency-offset estimation are important parameters reflecting system performance. For wireless mobile communication systems, the wireless signal is time-varying, and the frequency offset of the wireless signal occurs during transmission, such as Doppler shift, or due to the frequency deviation between the transmitter and receiver carrier frequencies. The orthogonality between subcarriers in the OFDM system is destroyed, resulting in interference between subchannels, and the signal is distorted, which seriously affects system performance. Therefore, synchronization Including time synchronization and frequency synchronization are important guarantees for system performance.

OFDM***采用 MIMO技术时，时频偏估计方法为导频共轭相乘估计 l =——Y arg(Y_kY*_+l) When OFDM system adopts MIMO technology, the time-frequency offset estimation method is pilot conjugate multiplication estimation l =——Y arg(Y _k Y* _+l )

时偏频偏，具体为：使用公式 ^{1π Μ} ^ 计算时偏，其中， 1表示时偏， N是 FFT点数， M是导频间隔， 1是子载波， k和 k+1为子载波的索引。 Time offset, specifically: Calculate the time offset using the formula ^{1π Μ} ^, where 1 is the time offset, N is the FFT point, M is the pilot interval, 1 is the subcarrier, and k and k+1 are the subcarrier indices. .

但是，由于 OFDM***采用 MIMO技术时，分给每个用户的导频非常少，而导频共轭相乘需要对所有的数据进行 IFFT (逆向快速傅里叶变换），这就导致该方法的运算量很大、浪费资源；另外，导频共轭相乘计算时偏频偏的方法中，使用了导频近似等效的方法进行的时偏估计，认为空载波上的值和导频载波上的一样，如此，就会使计算频偏时的原始数据不够准确，再利用这种等效数据进行时偏和频偏估计，就会使时偏和频偏估计值不够准确。 However, since OFDM systems use MIMO technology, there are very few pilots allocated to each user, and pilot conjugate multiplication requires IFFT (inverse fast Fourier transform) on all data, which leads to the method. The computational complexity is large and wastes resources; in addition, in the method of pilot bias conjugate multiplication calculation, the time-bias deviation method is used, and the pilot bias equivalent method is used to estimate the time offset, and the value on the null carrier and the pilot carrier are considered. The same as above, this will make the original data when calculating the frequency offset not accurate enough, and then use this equivalent data to perform time-bias and frequency-offset estimation, which will make the time-offset and frequency-offset estimation values inaccurate.

可见，目前已有的 OFDM*** MIMO时的同步方法中的时偏和频偏估计值，计算时运算量大、且不够准确。发明内容 It can be seen that the time offset and the frequency offset estimation value in the synchronization method of the existing OFDM system in OFDM system are large in calculation and not accurate enough. Summary of the invention

本发明解决的技术问题是提供了一种 OFDM*** MIMO时的同步方法及装置，以解决现有技术时偏和频偏估计值计算时运算量大、且不准确的问题。 The technical problem to be solved by the present invention is to provide a synchronization method and apparatus for MIMO in OFDM systems, which solves the problem of large computational complexity and inaccuracy in the calculation of time offset and frequency offset estimation values in the prior art.

为解决上述问题，本发明提供了一种 OFDM***的同步方法，该方法包括： To solve the above problems, the present invention provides a synchronization method for an OFDM system, the method comprising:

通过对导频信道响应的峰值搜索找到时偏对应的位置； Finding the position corresponding to the time offset by the peak search of the pilot channel response;

根据时偏和导频符号之间的相位差得出频偏估计值； Deriving a frequency offset estimation value according to a phase difference between the time offset and the pilot symbol;

根据时偏和频偏估计值进行正交频分复用 OFDM***的同步。 The synchronization of the OFDM system is performed according to the time offset and the frequency offset estimation value.

上述的方法，其中，所述通过对导频信道响应的峰值搜索找到时偏对应的位置，为：对导频序列进行 IFFT转换后得到导频信道响应的峰值位置。上述的方法，其中，所述对导频序列进行 IFFT转换后得到导频信道响应的峰值位置，为：对导频序列进行 IFFT转换后得到导频信道响应的峰值位置。 The above method, wherein the finding a time offset by searching for a peak of a pilot channel response The position should be: the peak position of the pilot channel response obtained after IFFT conversion of the pilot sequence. In the above method, the peak position of the pilot channel response is obtained by performing IFFT conversion on the pilot sequence, and the peak position of the pilot channel response is obtained after performing IFFT conversion on the pilot sequence.

上述的方法，其中，所述对导频序列进行 IFFT转换后得到导频信道响应的峰值位置，包括：对导频序列 P进行 IFFT得到第 n时刻的导频为

In the above method, the peak position of the pilot channel response obtained by performing IFFT conversion on the pilot sequence includes: performing IFFT on the pilot sequence P to obtain the pilot at the nth time is

其中， j为傅里叶变化表达式里定义的虚部符号， N表示 FFT点数， m 为导频 pilot索引，导频序列的集合记为 #Pilot, 为输入的符号序列； Where j is the imaginary part symbol defined in the Fourier transform expression, N is the FFT point number, m is the pilot pilot index, and the set of pilot sequences is denoted as #Pilot, which is the input symbol sequence;

Δ,.为时延，不大于 N_g , i为累加的索引， N_g是循环前缀时间与有用符号时间的比率； Δ,. is the delay, not greater than N _g , i is the accumulated index, and N _g is the ratio of the cyclic prefix time to the useful symbol time;

当" 且 =max(<¾)时，

/^取最大值，即为导频信道响应的峰值位置。 When "and =max(<3⁄4),

/^ takes the maximum value, which is the peak position of the pilot channel response.

上述的方法，其中，所述得出频偏估计值，包括：先获得导频载波上的频域接收数据，然后利用频域接收数据计算得出频偏估计值。 The above method, wherein the obtaining the frequency offset estimation value comprises: first obtaining frequency domain receiving data on the pilot carrier, and then calculating the frequency offset estimation value by using the frequency domain receiving data.

上述的方法，其中，所述获得导频载波上的频域接收数据，为：：第 0个符号第 m个载波上的频域接收数据 The above method, wherein the obtaining frequency domain receiving data on the pilot carrier is:: frequency domain receiving data on the mth carrier of the 0th symbol

「- k(£T + i-m)) "- k(£T + i-m))

第 0个符号第 + 3个载波上的频域接收数据 cx_V(-j2^(m + 3)/N)∑d_i0 -∑cx_V( ]2π^^{£Τ +} ~^m))

Frequency domain received data cx _{V on the} +3th carrier of the 0th symbol (-j2^(m + 3)/N)∑d _i0 -∑cx _V ( ]2π^ ^{£Τ +} ~ ^m) )

i=0 k=0 V N ) i=0 k=0 V N )

P₂ : 第个符号第 w个载波上的频域接收数据

P ₂ : frequency domain receive data on the wth carrier of the first symbol

P₃ : 第 g个符号第 m + 3个载波上的频域接收数据、^ ^ f ^ k(_£T + i-m) exp(-j2^(m + 3)/ N) ' exp(7'2^—— )^ d_iq '∑ exp jln P ₃ : frequency domain receive data on the mth 3th carrier of the gth symbol , ^ ^ f ^ k( _£ T + im) exp(-j2^(m + 3)/ N) 'exp(7'2^—— )^ d _iq '∑ exp jln

上述的方法，其中，所述得出频偏估计值，为：使用公式 ——或 The above method, wherein the obtained frequency offset estimation value is: using a formula - or

2Τ 2Τ

— Θ + 31 — Θ + 31

ε = ^——计算得到频偏估计值； ε = ^——calculate the frequency offset estimate;

2Τ 其中， £是频偏， N是 Fi 的点数， T = T_b+T_g , T_b =N , T_g =-N, 7；表 2Τ where £ is the frequency offset, N is the number of points of Fi, T = T _b + T _g , T _b = N , T _g =-N, 7;

8 示有用符号时间， r_g表示保护间隔或循环前缀时间，为采样点， /是时偏， Θ为 arg (尸 ₂ * )或为 arg (尸 ₃ *尸 ₀*)。本发明还提供了一种同步装置，包括， 8 indicates the useful symbol time, r _g indicates the guard interval or cyclic prefix time, is the sampling point, / is the time offset, Θ is arg (corpse ₂ * ) or arg (corpse ₃ * corpse ₀ *). The invention also provides a synchronization device, including

峰值搜索模块，用于通过对导频信道响应的峰值搜索找到时偏对应的位置； a peak search module, configured to find a position corresponding to a time offset by a peak search of a pilot channel response;

频偏估计模块，用于根据时偏和导频符号之间的相位差得出频偏估计值； a frequency offset estimation module, configured to obtain a frequency offset estimation value according to a phase difference between the time offset and the pilot symbol;

同步模块，用于根据时偏和频偏估计值进行正交频分复用 OFDM*** 的同步。 a synchronization module, configured to perform orthogonal frequency division multiplexing (OFDM) synchronization based on time offset and frequency offset estimation.

上述的同步装置，其中，所述频偏估计模块，用于先获得导频载波上的频域接收数据，然后利用频域接收数据计算得出频偏估计值。 In the above synchronization device, the frequency offset estimation module is configured to first obtain frequency domain received data on a pilot carrier, and then calculate a frequency offset estimation value by using frequency domain received data.

上述的同步装置，其中，所述峰值搜索模块，具体用于利用以下公式计算频域接收数据： In the above synchronization device, the peak search module is specifically configured to calculate frequency domain receiving data by using the following formula:

：第 0个符号第 m个载波上的频域接收数据

: Frequency domain receive data on the mth carrier of the 0th symbol

：第 0个符号第 m + 3个载波上的频域接收数据

Ρ₂ : 第个符号第 w个载波上的频域接收数据

: Frequency domain receive data on the mth 3th carrier of the 0th symbol

Ρ ₂ : Frequency domain receive data on the wth carrier of the first symbol

P₃ : 第 g个符号第 m + 3个载波上的频域接收数据。P ₃ : Frequency domain reception data on the mth 3th carrier of the gth symbol.

上述的同步装置，其中，所述频偏估计模块，具体用于利用公式 The synchronization device described above, wherein the frequency offset estimation module is specifically configured to use a formula

N N N N

β 3/ ø I 3/ β 3/ ø I 3/

ε = ¹⁷¹ 或 f = ^——计算得到频偏估计值； ε = ¹⁷¹ or f = ^ - calculate the frequency offset estimate;

2Τ 2Τ 其中， £是频偏估计值， N是 Fi 的点数， T = T_b + T_g , T_b = N , T_g = -N , 2Τ 2Τ where £ is the frequency offset estimate, N is the number of points of Fi, T = T _b + T _g , T _b = N , T _g = -N ,

8 8

7；表示有用符号时间， 7；表示保护间隔或循环前缀时间， /是时偏， Θ arg( ₂ * )或为 arg( ₃ *尸₀*)。采用本发明的技术方案，具有高性能和低复杂度的优点，易于实现，其优点主要表现在：（1 ) 复杂度低，因为已有技术中的峰值搜索需要对所有的数据载波做 IFFT, 本发明的峰值搜索仅需找到导频对应的位置，在导频对应的位置对导频载波进行 IFFT, 由于对于 MIMO来说，导频载波已经很少了，是非 MIMO时的一半，所以能够降低峰值搜索计算的复杂度；（2 ) 通过时偏定位后确定频偏，频偏的定位是利用非 MIMO时导频符号之间相位差的关系推导出来的，复杂度低并且准确，这种方法在实际***中非常易于实现。附图说明 7; indicates useful symbol time, 7; indicates guard interval or cyclic prefix time, / is time offset, Θ arg( ₂ * ) or arg( ₃ * corpse ₀ *). The technical solution of the invention has the advantages of high performance and low complexity, and is easy to implement, and the advantages thereof are mainly as follows: (1) The complexity is low, because the peak search in the prior art needs to perform IFFT on all data carriers. The peak search of the present invention only needs to find the position corresponding to the pilot, and performs IFFT on the pilot carrier at the position corresponding to the pilot. Since the pilot carrier is rarely used for MIMO, it is half of the non-MIMO, so it can be reduced. The complexity of the peak search calculation; (2) the frequency offset is determined by the time-biased positioning, and the frequency offset is derived by using the relationship of the phase difference between the pilot symbols in the non-MIMO, and the complexity is low and accurate. Very easy to implement in real systems. DRAWINGS

此处所说明的附图用来提供对本发明的进一步理解，构成本发明的一部分，本发明的示意性实施例及其说明用于解释本发明，并不构成对本发明的不当限定。在附图中： The drawings are intended to provide a further understanding of the invention, and are intended to be a part of the invention. In the drawing:

图 1是本发明实施例流程图；图 2是 MIMO子载波的 Patten A基本结构图； Figure 1 is a flow chart of an embodiment of the present invention; 2 is a Ptten A basic structure diagram of a MIMO subcarrier;

图 3是 MIMO子载波的 Patten B基本结构图。具体实施方式 Figure 3 is a diagram showing the basic structure of Patten B of a MIMO subcarrier. detailed description

为了使本发明所要解决的技术问题、技术方案及有益效果更加清楚、明白，以下结合附图和实施例，对本发明进行进一步详细说明。应当理解，此处所描述的具体实施例仅仅用以解释本发明，并不用于限定本发明。 The present invention will be further described in detail below with reference to the accompanying drawings and embodiments in order to make the present invention. It is understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

如图 1所示，是本发明实施例流程图，提供了一种 OFDM*** MIMO 时的同步方法，包括： As shown in FIG. 1 , it is a flowchart of an embodiment of the present invention, which provides a synchronization method for MIMO in an OFDM system, including:

步驟 S101 : 对导频信号进行峰值搜索，找到时偏对应的位置；本步驟具体为：先计算出导频信号的低通等效信号；再利用导频信号的低通等效信号，计算得出导频子载波序列；最后利用导频子载波序列计算时偏。 Step S101: Perform a peak search on the pilot signal to find a position corresponding to the time offset; the specific step is: first calculating a low-pass equivalent signal of the pilot signal; and then using the low-pass equivalent signal of the pilot signal, calculating The pilot subcarrier sequence is output; finally, the pilot subcarrier sequence is used to calculate the time offset.

这里，所述低通等效信号，可以通过下述公式计算： S(t) = 1/ N∑ , exv[2nkAf(t― N_gT_s 0≤t≤T_b + T_g 其中，表示低通等效信号， ^表示有用符号时间， ^表示保护间隔或循环前缀时间； N表示 FFT (快速傅里叶变换）点数，；^是发射的信号， Δ/是子载波间隔， 7；是持续的符号时间， N_gA循环前缀时间与有用符号时间的比率， k为采样点， j为傅里叶变化表达式里定义的虚部符号， t为起始时间；根据 OFDM***定义的 Δ/与 7；成反比的关系，低通等效信号可以写为： S{t、 = N^X _k \2 {t _ N _gT _s、 j I NT _s 0≤t≤T_b + T_g ；所述，利用导频信号的低通等效信号，计算得出导频子载波序列，包括：对导频信号的低通等效信号进行抽样，再增加噪音和干扰信号，最终得到导频子载波序列；其中，所述对低通等效信号进行抽样，可以在时刻 t_n =N_gT_s +nT_s(n = 0,l,2...N-l)^ S (t)进行抽样计算，具体为： Here, the low-pass equivalent signal can be calculated by the following formula: S(t) = 1/ N∑ , exv[2nkAf(t- N _g T _s 0≤t≤T _b + T _g where, indicating low Pass the equivalent signal, ^ denotes the useful symbol time, ^ denotes the guard interval or cyclic prefix time; N denotes the FFT (Fast Fourier Transform) point number, ;^ is the transmitted signal, Δ/ is the subcarrier spacing, 7; is continuous Symbol time, N _g A ratio of cyclic prefix time to useful symbol time, k is the sampling point, j is the imaginary part symbol defined in the Fourier variation expression, t is the starting time; Δ/ according to the OFDM system definition In inverse relationship with 7;, the low-pass equivalent signal can be written as: S{t, = N^X _k \2 {t _ N _g T _s , j I NT _s 0 ≤ t ≤ T _b + T _g ; The pilot subcarrier sequence is calculated by using the low pass equivalent signal of the pilot signal, including: sampling the low pass equivalent signal of the pilot signal, adding noise and interference signals, and finally obtaining the pilot Carrier sequence Wherein, the sampling of the low-pass equivalent signal may be performed at a time t _n =N _g T _s +nT _s (n = 0, l, 2...Nl)^ S (t), specifically :

R_n = exp [2^'kn/N]；R _n = exp [2^'kn/N];

所述增加噪声和干扰信号，最终得到导频子载波序列，具体可以通过 - +- 八 Adding noise and interference signals, and finally obtaining a pilot subcarrier sequence, specifically by - + - eight

下迷公

； Under the public

;

k [θ ······ #Pilot 其中， Y_k = C, exp [- + Z_k= X_kH_k +Z_k , 表示导频子

k [θ ······ #Pilot where Y _k = C, exp [- + Z _k = X _k H _k +Z _k , indicating the pilot

载波序列， H是信道沖击响应的低通的 FFT, 表示第 k个子载波上的信道响应，是噪声和干扰；所述利用导频子载波序列计算时偏，可以为：通过对进行 IFFT得到， p_n =1/ a_t ex [2^- j (n- Δ_;. ) / N] , 其中, 当" =Δ且 ₌max( j时, ex [2^ 'm(n-A_i )/N]=1 , /?„取最大值, 即导频时域信道响应的峰值位置即为时偏。 The carrier sequence, H is a low-pass FFT of the channel impulse response, indicating the channel response on the kth subcarrier, which is noise and interference; and the calculation of the pilot subcarrier sequence using the time offset may be: by performing IFFT on the pair , p _n =1/ a _t ex [2^- j (n- Δ _; . ) / N] , where, when " = Δ and ₌ max ( j , ex [2^ 'm(nA _i )/N ]=1 , /? „ take the maximum value, that is, the peak position of the pilot time domain channel response is the time offset.

步驟 S102: 根据时偏和导频符号之间的相位差得出频偏估计值。 Step S102: The frequency offset estimation value is obtained according to the phase difference between the time offset and the pilot symbol.

本步驟具体为：先获得导频载波上的频域接收数据，然后利用频域接收数据计算出频偏估计值； The step is specifically: first obtaining frequency domain receiving data on the pilot carrier, and then calculating the frequency offset estimation value by using the frequency domain receiving data;

这里，所述先获得导频载波上的频域接收数据，可以为：当 MIMO的子载波为图 2所示的 Patten A时，图中包括空载波、导频载波和数据载波三种，斜阴影圆圈表示导频载波，横阴影圆圈表示空载波，其余空白圆圈表示数字载波，其中两个导频载波分别为，或者可以为：当 MIMO的子载波为图 3所示的 Patten B时，图中包括空载波、导频载波和数据载波三种，斜阴影圆圈表示导频载波，横阴影圆圈表示空载波，其余空白圆圈表示数字载波，其中两个导频载波，分别为 ^Ρ。，其中，。为第 0个符号第 w个载波上的频域接收数据，可以使用下述公式表示：

Here, the obtaining the frequency domain receiving data on the pilot carrier may be: when the MIMO subcarrier is the Patten A shown in FIG. 2, the figure includes three types: a null carrier, a pilot carrier, and a data carrier. The shaded circle represents the pilot carrier, the horizontal shaded circle represents the empty carrier, and the remaining blank circles represent the digital carrier, where the two pilot carriers are respectively, or may be: When the MIMO subcarrier is the Patten B shown in FIG. 3, the figure It includes three types: null carrier, pilot carrier and data carrier. The oblique hatched circle indicates the pilot carrier, the horizontal hatched circle indicates the null carrier, and the remaining blank circles indicate the digital carrier, and the two pilot carriers are respectively ^Ρ . , among them, . The data received in the frequency domain on the wth carrier of the 0th symbol can be expressed by the following formula:

为第 0个符号第 + 3个载波上的频域接收数据，可以使用下述公式表示： ex_V(-j2^(m + 3)/N)∑ d_i0 ·∑ exp /1π ~ - ~~ 为第个符号第 w个载波上的频域接收数据，可以使用下述公式表示：

The data received in the frequency domain on the +3th carrier of the 0th symbol can be expressed by the following formula: ex _V (-j2^(m + 3)/N)∑ d _i0 ·∑ exp /1π ~ - ~~ The data is received in the frequency domain on the wth carrier of the first symbol, which can be expressed by the following formula:

为第 g个符号第 + 3个载波上的频域接收数据，可以使用下述公式表示： exp(-j2^(m + 3)/N) - exp(72^r— -) , d_iq ·∑exp ]1π ~ -—— - ； The data received in the frequency domain on the +3th carrier of the gth symbol can be expressed by the following formula: exp(-j2^(m + 3)/N) - exp(72^r− -) , d _iq · ∑exp ]1π ~ -—— - ;

N i=o k=o V N / N i=o k=o V N /

所述利用导频子载波与时偏计算出频偏估计值，包括：当 MIMO格式为图 2中的 Patten A时，根据下述公式计算： £ = ^ ；当 MIMO格式 The calculating the frequency offset estimation value by using the pilot subcarrier and the time offset includes: when the MIMO format is Patten A in FIG. 2, calculated according to the following formula: £ = ^ ; when MIMO format

2T 2T

^Ν- θ + 31 ^Ν - θ + 31

的图 3中的 Patten B时，根据下述公式计算： ε = ^ In Patten B in Figure 3, it is calculated according to the following formula: ε = ^

2Τ 其中， 6>为 argCP₃ N是 Fi 的点数， T = T_b + T_g , T_b = N , T_g = -N , 2Τ where 6> is argCP ₃ N is the number of points of Fi, T = T _b + T _g , T _b = N , T _g = -N ,

8 为采样点， /是时偏， £是频偏。 8 is the sampling point, / is the time offset, and £ is the frequency offset.

这样，通过以上的两个步驟就可以得到 MIMO用户的时偏和频偏估计值。 In this way, the time offset and frequency offset estimates of the MIMO user can be obtained through the above two steps.

步驟 S103: 根据时偏和频偏估计值进行 OFDM***的同步。 Step S103: Perform synchronization of the OFDM system according to the time offset and the frequency offset estimation value.

本发明还提供一种同步装置实施例，具体包括，峰值搜索模块，用于通过对导频信道响应的峰值搜索找到时偏对应的位置； The present invention also provides an embodiment of a synchronization device, specifically including a peak search module, configured to find a position corresponding to a time offset by a peak search of a pilot channel response;

同步模块，用于根据时偏和频偏估计值进行 OFDM***的同步。 A synchronization module is configured to perform synchronization of the OFDM system according to the time offset and the frequency offset estimation value.

所述峰值搜索模块，具体用于对导频序列进行 IFFT转换，计算得到导频信道响应的峰值位置； The peak search module is specifically configured to perform IFFT conversion on the pilot sequence, and calculate a peak position of the pilot channel response;

其中，所述导频信道响应的峰值位置，可以利用以下公式进行计算： The peak position of the pilot channel response can be calculated by using the following formula:

= 11 ^ a_f exp[2^r j (n - Δ. ) / TV] 其中，为载波位置为 k的导频序列， k为采样点， j为傅里叶变化表达式里定义的虚部符号， N表示 FFT点数， m为导频 pilot索引，导频序列的集合记为 #Pilot, 为输入的符号序列； = 11 ^ a _f exp[2^rj (n - Δ. ) / TV] where is the pilot sequence with carrier position k, k is the sampling point, j is the imaginary part symbol defined in the Fourier variation expression , N represents the number of FFT points, m is the pilot pilot index, and the set of pilot sequences is denoted as #Pilot, which is the input symbol sequence;

当" 且" ^ max^ )时， _exp[2/T_ m(" - AJ/N] _{= 1} , _{p ( n )}取最大值，即导频信道响应的峰值位置；其中，为时延，不大于 ^，为累加的索引， ^ 是循环前缀时间与有用符号时间的比率。 When "and" ^ max^ ), _ex p[2/T_ m(" - AJ/N] _{= 1} , _{p ( n )} takes the maximum value, that is, the peak position of the pilot channel response; where, is the delay, Not greater than ^, the cumulative index, ^ is the ratio of the cyclic prefix time to the useful symbol time.

所述频偏估计模块，用于先获得导频载波上的频域接收数据，然后利用频域接收数据计算得出频偏估计值。 The frequency offset estimation module is configured to first obtain frequency domain receiving data on a pilot carrier, and then use the frequency domain receiving data to calculate a frequency offset estimation value.

所述频偏估计模块，具体用于当 MIMO的子载波为图 2所示的 Patten A 时，分别计算两个导频载波，当 MIMO的子载波为图 3所示的 Patten B 其中， P₀ = ρ(-]2π /Ν)∑ d_i0 ·∑ exp { ]2π ^^{£Τ +} ~^m)) P, = ex_V(-j2^(m + 3)/N)∑ d_i0 ·∑ exp /1π ~ - ~~The frequency offset estimation module is specifically configured to calculate two pilot carriers when the MIMO subcarrier is the Patten A shown in FIG. 2, and when the MIMO subcarrier is the Patten B shown in FIG. Where P ₀ = ρ(-]2π /Ν)∑ d _i0 ·∑ exp { ]2π ^ ^{£Τ +} ~ ^m) ) P, = ex _V (-j2^(m + 3)/N)∑ d _i0 ·∑ exp /1π ~ - ~~

=0 k=0 V N /

=0 k=0 VN /

P₃ = exp(-72^r/(m + 3)/N) · exp02^r— -)∑ d_iq ·∑ exp jln^ ~ - ~~ '-P ₃ = exp(-72^r/(m + 3)/N) · exp02^r— -)∑ d _iq ·∑ exp jln^ ~ - ~~ '-

N i= k= V J 所述频偏估计模块，具体用于导频载波计算出频偏估计值； N i= k= V J The frequency offset estimation module is specifically configured to calculate a frequency offset estimation value for the pilot carrier;

其中，所述计算出频偏估计值，包括：当 MIMO格式为图 2中的 Patten The calculating the frequency offset estimation value includes: when the MIMO format is Patten in FIG. 2

3/ 3/

A时，根据下述公式计算： ε =^ ；当 ΜΙΜΟ格式的图 3中的 Patten B When A is calculated according to the following formula: ε =^ ; Patten B in Figure 3 of the ΜΙΜΟ format

2T 2T

— Θ+31 — Θ+31

时，根据下述公式计算： ε = When calculated according to the following formula: ε =

上述说明示出并描述了本发明的一个优选实施例，但如前所述，应当理解本发明并非局限于本文所披露的形式，不应看作是对其他实施例的排除，而可用于各种其他组合、修改和环境，并能够在本文所述发明构想范围内，通过上述教导或相关领域的技术或知识进行改动。而本领域人员所进行的改动和变化不脱离本发明的精神和范围，则都应在本发明所附权利要求的保护范围内。 The above description shows and describes a preferred embodiment of the present invention, but as described above, it should be understood that the present invention is not limited to the forms disclosed herein, and should not be construed as Other combinations, modifications, and environments are possible and can be modified by the teachings or related art or knowledge within the scope of the inventive concept described herein. All changes and modifications made by those skilled in the art are intended to be within the scope of the appended claims.

Claims

权利要求书 Claim

1、一种正交频分复用 OFDM***的同步方法，其特征在于，该方法包括： A method for synchronizing orthogonal frequency division multiplexing OFDM systems, characterized in that the method comprises:

2、根据权利要求 1所述的方法，其特征在于，所述通过对导频信道响应的峰值搜索找到时偏对应的位置，为：对导频序列进行逆向快速傅里叶变换 IFFT转换后得到导频信道响应的峰值位置。 The method according to claim 1, wherein the peak search corresponding to the pilot channel response finds a position corresponding to the time offset, which is: performing inverse fast Fourier transform IFFT conversion on the pilot sequence The peak position of the pilot channel response.

3、根据权利要求 2所述的方法，其特征在于，所述对导频序列进行 IFFT 转换后得到导频信道响应的峰值位置，包括： The method according to claim 2, wherein the IFFT conversion of the pilot sequence results in a peak position of the pilot channel response, including:

对导频序列 P 进行 IFFT ，得到第 n 时刻的导频

Performing an IFFT on the pilot sequence P to obtain the pilot at the nth moment

其中， j为傅里叶变化表达式里定义的虚部符号， N表示 FFT点数， m为导频 pilot索引，导频序列的集合记为 #Pilot，为输入的符号序列； Where j is the imaginary part symbol defined in the Fourier variation expression, N is the FFT point number, m is the pilot pilot index, and the set of pilot sequences is denoted as #Pilot, which is the input symbol sequence;

Δ,.为时延，不大于 N_g， i为累加的索引， N_g是循环前缀时间与有用符号时间的比率； Δ,. is the delay, not greater than N _g , i is the accumulated index, and N _g is the ratio of the cyclic prefix time to the useful symbol time;

当 Μ = Δ,且 , ^ max ^, )时， exp[2^ y'm ( « - Δ_; ) /Ν] = 1 , /?„取最大值作为导频信道响应的峰值位置。 When Μ = Δ, and ^ max ^, ), exp[2^ y'm ( « - Δ _; ) /Ν] = 1 , /? „ takes the maximum value as the peak position of the pilot channel response.

4、根据权利要求 1所述的方法，其特征在于，所述得出频偏估计值，包括： The method according to claim 1, wherein the obtaining the frequency offset estimation value comprises:

先获得导频载波上的频域接收数据，然后利用频域接收数据计算得出频偏估计值。 First, the frequency domain receiving data on the pilot carrier is obtained, and then the frequency domain estimation data is used to calculate the frequency offset estimation value.

5、根据权利要求 4所述的方法，其特征在于，所述获得导频载波上的频域接收数据，为： 5. The method according to claim 4, wherein the obtaining on the pilot carrier The frequency domain receives data as:

P_Q：第 0个符号第 m个载波上的频域接收数据 P _Q : frequency domain receive data on the mth carrier of the 0th symbol

k(£T + i-m) k(£T + i-m)

N )

P_x：第 0个符号第 + 3个载波上的频域接收数据

P _x : frequency domain receive data on the +3th carrier of the 0th symbol

P₂：第个符号第 w个载波上的频域接收数据 P ₂ : frequency domain receive data on the wth carrier of the first symbol

, f . k(£T + i-m) , f . k(£T + i-m)

d_iq ' exp ]2πd _iq ' exp ]2π

k=。、 N J

k=. , NJ

P₃: 第 g个符号第 + 3个载波上的频域接收数据 exp(-j2^-/(m + 3)/N) ' exp(j2^— -)∑ d_iq ' exp )2π^ ~ - ~~ ^L 。 P ₃ : frequency domain reception data on the +3th carrier of the gth symbol exp(-j2^-/(m + 3)/N) ' exp(j2^− -)∑ d _iq ' exp )2π^ ~ - ~~ ^L .

N _!=0 k=0 、 N J N _!=0 k=0 , NJ

6、根据权利要求 1或 4所述的方法，其特征在于，所述得出频偏估计值，为：使用 ——或£=^——计算得到频偏估计值； The method according to claim 1 or 4, wherein the obtaining the frequency offset estimation value is: calculating the frequency offset estimation value by using - or £=^;

2Τ 2Τ 其中， £是频偏估计值， Ν是 FFT的点数, T = T_b+T_g , T_b =N , T_g =-N, 2Τ 2Τ where £ is the frequency offset estimate, Ν is the number of points in the FFT, T = T _b + T _g , T _b = N , T _g = -N,

8 8

7；表示有用符号时间， 7；表示保护间隔或循环前缀时间， /是时偏， 0为 arg( ₂ * )或为 argCP₃ * ）。 7; indicates useful symbol time, 7; indicates guard interval or cyclic prefix time, / is time offset, 0 is arg( ₂ * ) or argCP ₃ * ).

7、一种同步装置，其特征在于，包括， 7. A synchronization device, characterized in that

8、根据权利要求 7所述的同步装置，其特征在于，所述峰值搜索模块，用于获得导频信道响应的峰值位置为对导频序列进行 IFFT后得到导频信道响应的峰值位置，所述导频信道响应的峰值位置为： 8. The synchronization device according to claim 7, wherein: The peak search module is configured to obtain a peak position of the pilot channel response, where the peak position of the pilot channel response is obtained after the IFFT is performed on the pilot sequence, where the peak position of the pilot channel response is:

对导频序列 P 进行 IFFT，得到第 n 时刻的导频 Pn Performing an IFFT on the pilot sequence P to obtain the pilot Pn at the nth moment

N-1 N-1

⁼1/^∑ ∑ ^ai xp[2^- jm(n- Δ. ) / Λ^] ⁼ 1/^∑ ∑ ^a i xp[2^- jm(n- Δ. ) / Λ^]

i=0 me#Pilot i=0 me#Pilot

其中， j为傅里叶变化表达式里定义的虚部符号， N表示 FFT点数， m 为导频 pilot索引，导频序列的集合记为 #Pilot， A为输入的符号序列； Where j is the imaginary part symbol defined in the Fourier transform expression, N is the FFT point number, m is the pilot pilot index, and the set of pilot sequences is denoted as #Pilot, where A is the input symbol sequence;

当 Μ = Δ,且 , ₌max( !.)时， exp[2r m("_A,)/N]=l， p (n)取最大值，即导频信道响应的峰值位置； When Μ = Δ, and, ₌ max( !.), exp[2r m("_A,)/N]=l, p (n) takes the maximum value, that is, the peak position of the pilot channel response;

Δ,.为时延，不大于 N_g， i 为累加的索引， N_g是循环前缀时间与有用符号时间的比率。 Δ,. is the delay, not greater than N _g , i is the accumulated index, and N _g is the ratio of the cyclic prefix time to the useful symbol time.

9、根据权利要求 8所述的同步装置，其特征在于， 9. The synchronization device according to claim 8, wherein:

10、根据权利要求 9所述的同步装置，其特征在于， 10. The synchronization device according to claim 9, wherein:

所述频偏估计模块，具体用于利用以下公式计算频域接收数据： The frequency offset estimation module is specifically configured to calculate frequency domain receiving data by using the following formula:

P_Q：第 0个符号第 m个载波上的频域接收数据

P _Q : frequency domain receive data on the mth carrier of the 0th symbol

Ρ, 第 0个符号第 + 3个载波上的频域接收数据 exp(-j2^-/(m + 3)/N)∑ d_i0 -∑ exp )2π^ ~ - ~~ ^L Ρ, the frequency domain receiving data on the +3th carrier of the 0th symbol exp(-j2^-/(m + 3)/N)∑ d _i0 -∑ exp )2π^ ~ - ~~ ^L

i=o i=o V N J i=o i=o V N J

P₂ 第个符号第 w个载波上的频域接收数据

Frequency domain receiving data on the wth carrier of P ₂ first symbol

P₃ 第 g个符号第 + 3个载波上的频域接收数据

Frequency domain received data on P ₃ + g-th symbol of the carriers 3

11、根据权利要求 10所述的同步装置，其特征在于，所述频偏估计模块，具体用于利用 ——或£=^——计算得到 The synchronization device according to claim 10, wherein the frequency offset estimation module is specifically configured to calculate by using - or £=^

2Τ 2Τ 2Τ 2Τ

频偏估计值； Frequency offset estimate;

其中， £是频偏估计值， Ν是 FFT的点数, T = T_b+T_g , T_b=N , T_g =-N, Where £ is the frequency offset estimate, Ν is the number of points in the FFT, T = T _b + T _g , T _b = N , T _g = -N,

8 8