CN102130880A - Method and system for correcting frequency offset estimation in OFDM system - Google Patents

Abstract

The invention discloses a method for correcting frequency offset estimation in an orthogonal frequency division multiplexing access (OFDMA) system. The method comprises the following steps of: estimating channel estimation values of two time slots according to a reference signal which is generated at a transmitting end and a reference signal which is generated at a receiving end, and obtaining an initial frequency offset estimated value according to the channel estimation values of the two time slots; and correcting the channel estimation values of the two time slots to obtain a frequency offset estimation corrected value according to an interference matrix between sub-carriers in the process of correcting the initial frequency offset estimated value. The invention also discloses a system for correcting frequency offset estimation in the OFDMA system. An initial frequency offset estimated value correction unit in the system is used for correcting the channel estimation values of the two time slots to obtain the frequency offset estimation corrected value according to the interference matrix between sub-carriers in the process of correcting the initial frequency offset estimated value. The method and the system improve the frequency offset estimation accuracy.

Description

Bearing calibration and system that a kind of OFDMA system frequency deviation is estimated

Technical field

The present invention relates to the frequency offset correction technology, relate in particular to a kind of OFDM and insert bearing calibration and the system that (OFDMA, Orthogonal Frequency Division Multiple Access) system frequency deviation is estimated.

Background technology

In the OFDMA system, owing to there is the influence of the Doppler frequency shift in crystal oscillator deviation and space, can produce the frequency shift (FS) of subcarrier, therefore need carry out frequency offset estimating with reference signal at receiving terminal, yet prior art only is inaccurate according to the frequency deviation estimating method that reference signal is carried out, because frequency offset estimating could be proofreaied and correct the influence that brings to channel estimating owing to frequency deviation effectively accurately, therefore, it is very necessary improving accuracy of frequency offset estimation.

Summary of the invention

In view of this, main purpose of the present invention is to provide a kind of bearing calibration and system of OFDMA system frequency deviation estimation, can estimate the frequency offset estimating value under the various channel circumstances exactly, thereby improve accuracy of frequency offset estimation.

For achieving the above object, technical scheme of the present invention is achieved in that

The bearing calibration that a kind of OFDMA system frequency deviation is estimated, this method comprises:

OFDM inserts the reference signal of (OFDMA) system transmitting terminal generation and carries out orthogonal frequency (OFDM) demodulation through behind the channel at receiving terminal, and receiving terminal extracts the reference signal that is received;

The reference signal that reference signal that produces according to transmitting terminal and receiving terminal are received estimates the channel estimation value of two time slots, obtains the initial frequency deviation estimated value according to the channel estimation value of described two time slots;

The initial frequency deviation estimated value is carried out timing, is according to interference matrix between subcarrier the channel estimation value of described two time slots to be proofreaied and correct the back to obtain the frequency offset estimating corrected value.

Wherein, obtaining the initial frequency deviation estimated value according to the channel estimation value of described two time slots specifically comprises: the channel estimation value according to two time slots obtains phase difference, calculates the initial frequency deviation estimated value according to described phasometer.

Wherein, describedly according to interference matrix between subcarrier the channel estimation value of described two time slots is proofreaied and correct the back and obtain the frequency offset estimating corrected value and specifically comprise: to initial frequency deviation estimated value timing, calculate interference matrix between subcarrier, obtain the channel estimation value of two new time slots according to the reference signal that interference matrix and described receiving terminal received between described subcarrier, channel estimation value according to two new time slots obtains phase difference, calculates the frequency offset estimating corrected value according to described phasometer.

Wherein, interference matrix is specially A (γ) between described subcarrier, and the computing formula that is adopted is:

$A\left(\mathrm{\γ}\right)=\left(\begin{array}{cccccccccccc}{w}_0& w_1& w_2& w_3& 0& 0& 0& 0& 0& 0& 0& 0\\ w_{-1}& w_0& w_1& w_2& w_3& 0& 0& 0& 0& 0& 0& 0\\ w_{-2}& w_{-1}& w_0& w_1& w_2& w_3& 0& 0& 0& 0& 0& 0\\ w_{-3}& w_{-2}& w_{-1}& w_0& w_1& w_2& w_3& 0& 0& 0& 0& 0\\ 0& w_{-3}& w_{-2}& w_{-1}& w_0& w_1& w_2& w_3& 0& 0& 0& 0\\ 0& 0& w_{-3}& w_{-2}& w_{-1}& w_0& w_1& w_2& w_3& 0& 0& 0\\ 0& 0& 0& w_{-3}& w_{-2}& w_{-1}& w_0& w_1& w_2& w_3& 0& 0\\ 0& 0& 0& 0& w_{-3}& w_{-2}& w_{-1}& w_0& w_1& w_2& w_3& 0\\ 0& 0& 0& 0& 0& w_{-3}& w_{-2}& w_{-1}& w_0& w_1& w_2& w_3\\ 0& 0& 0& 0& 0& 0& w_{-3}& w_{-2}& w_{-1}& w_0& w_1& w_2\\ 0& 0& 0& 0& 0& 0& 0& w_{-3}& w_{-2}& w_{-1}& w_0& w_1\\ 0& 0& 0& 0& 0& 0& 0& 0& w_{-3}& w_{-2}& w_{-1}& w_0\end{array}\right);$

Wherein, when the number of current subcarrier is k, w _-3Be the interference coefficient of the subcarrier of k-3, w _-2Be the interference coefficient of the subcarrier of k-2, w _-1Be the interference coefficient of the subcarrier of k-1, w ₀Be the interference coefficient of current subcarrier, w ₁Be the interference coefficient of the subcarrier of k+1, w ₂Be the interference coefficient of the subcarrier of k+2, w ₃Be the interference coefficient of the subcarrier of k+3, γ is a frequency offseting value.

Wherein, described w _-3, described w _-2, described w _-1, described w ₀, described w ₁, described w ₂With described w ₃The computing formula of Cai Yonging is specially respectively:

w _-3＝exp(-jπ*(-3)/N)/(N*sin(π*(-3+γ)/N))*β；

w _-2＝exp(-jπ*(-2)/N)/(N*sin(π*(-2+γ)/N))*β；

w _-1＝exp(-jπ*(-1)/N)/(N*sin(π*(-1+γ)/N))*β；

w ₀＝exp(-jπ*(0)/N)/(N*sin(π*(0+γ)/N))*β；

w ₁＝exp(-jπ*(1)/N)/(N*sin(π*(1+γ)/N))*β；

w ₂＝exp(-jπ*(2)/N)/(N*sin(π*(2+γ)/N))*β；

w ₃＝exp(-jπ*(3)/N)/(N*sin(π*(3+γ)/N))*β；

Wherein,

γ=-freq_offset/ Δ f; Described β is the coefficient of frequency shift (FS); Described freq_offset/ Δ f is the initial frequency deviation estimated value, and Δ f is the frequency interval between subcarrier; The sampling number that described N determines for the OFDMA system bandwidth, above-mentioned j is an imaginary unit, j ²=-1.

The corrective system that a kind of OFDMA system frequency deviation is estimated, this system comprises: demodulation and initial frequency deviation estimation unit, initial frequency deviation are estimated correcting unit; Wherein,

Described demodulation and initial frequency deviation estimation unit, the reference signal that is used for the transmitting terminal generation of OFDMA system is carried out the OFDM demodulation through behind the channel at receiving terminal, and receiving terminal extracts the reference signal that is received; The reference signal that reference signal that produces according to transmitting terminal and receiving terminal are received estimates the channel estimation value of two time slots, obtains the initial frequency deviation estimated value according to the channel estimation value of described two time slots;

Described initial frequency deviation is estimated correcting unit, is used for the initial frequency deviation estimated value is carried out timing, is according to interference matrix between subcarrier the channel estimation value of described two time slots to be proofreaied and correct the back to obtain the frequency offset estimating corrected value.

Wherein, described demodulation and initial frequency deviation estimation unit are further used for calculating under the initial frequency deviation estimated value situation, obtain phase difference according to the channel estimation value of two time slots, calculate the initial frequency deviation estimated value according to described phasometer.

Wherein, described initial frequency deviation is estimated correcting unit, being further used for according to interference matrix between subcarrier the channel estimation value of described two time slots being proofreaied and correct the back obtains under the frequency offset estimating corrected value situation, to initial frequency deviation estimated value timing, calculate interference matrix between subcarrier, obtain the channel estimation value of two new time slots according to the reference signal that interference matrix and described receiving terminal received between described subcarrier, channel estimation value according to two new time slots obtains phase difference, calculates the frequency offset estimating corrected value according to described phasometer.

Wherein, described initial frequency deviation is estimated correcting unit, is further used for calculating when interference matrix is specially A (γ) between subcarrier, and the computing formula that is adopted is:

$A\left(\mathrm{\γ}\right)=\left(\begin{array}{cccccccccccc}{w}_0& w_1& w_2& w_3& 0& 0& 0& 0& 0& 0& 0& 0\\ w_{-1}& w_0& w_1& w_2& w_3& 0& 0& 0& 0& 0& 0& 0\\ w_{-2}& w_{-1}& w_0& w_1& w_2& w_3& 0& 0& 0& 0& 0& 0\\ w_{-3}& w_{-2}& w_{-1}& w_0& w_1& w_2& w_3& 0& 0& 0& 0& 0\\ 0& w_{-3}& w_{-2}& w_{-1}& w_0& w_1& w_2& w_3& 0& 0& 0& 0\\ 0& 0& w_{-3}& w_{-2}& w_{-1}& w_0& w_1& w_2& w_3& 0& 0& 0\\ 0& 0& 0& w_{-3}& w_{-2}& w_{-1}& w_0& w_1& w_2& w_3& 0& 0\\ 0& 0& 0& 0& w_{-3}& w_{-2}& w_{-1}& w_0& w_1& w_2& w_3& 0\\ 0& 0& 0& 0& 0& w_{-3}& w_{-2}& w_{-1}& w_0& w_1& w_2& w_3\\ 0& 0& 0& 0& 0& 0& w_{-3}& w_{-2}& w_{-1}& w_0& w_1& w_2\\ 0& 0& 0& 0& 0& 0& 0& w_{-3}& w_{-2}& w_{-1}& w_0& w_1\\ 0& 0& 0& 0& 0& 0& 0& 0& w_{-3}& w_{-2}& w_{-1}& w_0\end{array}\right);$

Wherein, when the number of current subcarrier is k, w _-3Be the interference coefficient of the subcarrier of k-3, w _-2Be the interference coefficient of the subcarrier of k-2, w _-1Be the interference coefficient of the subcarrier of k-1, w ₀Be the interference coefficient of current subcarrier, w ₁Be the interference coefficient of the subcarrier of k+1, w ₂Be the interference coefficient of the subcarrier of k+2, w ₃Be the interference coefficient of the subcarrier of k+3, γ is a frequency offseting value.

Wherein, described initial frequency deviation is estimated correcting unit, is further used for calculating described w _-3, described w _-2, described w _-1, described w ₀, described w ₁, described w ₂With described w ₃The time, the computing formula of Cai Yonging is specially respectively:

w _-3＝exp(-jπ*(-3)/N)/(N*sin(π*(-3+γ)/N))*β；

w _-2＝exp(-jπ*(-2)/N)/(N*sin(π*(-2+γ)/N))*β；

w _-1＝exp(-jπ*(-1)/N)/(N*sin(π*(-1+γ)/N))*β；

w ₀＝exp(-jπ*(0)/N)/(N*sin(π*(0+γ)/N))*β；

w ₁＝exp(-jπ*(1)/N)/(N*sin(π*(1+γ)/N))*β；

w ₂＝exp(-jπ*(2)/N)/(N*sin(π*(2+γ)/N))*β；

w ₃＝exp(-jπ*(3)/N)/(N*sin(π*(3+γ)/N))*β；

Wherein,

γ=-freq_offset/ Δ f; Described β is the coefficient of frequency shift (FS); Described freq_offset/ Δ f is the initial frequency deviation estimated value, and Δ f is the frequency interval between subcarrier; The sampling number that described N determines for the OFDMA system bandwidth, above-mentioned j is an imaginary unit, j ²=-1.

The reference signal that OFDMA of the present invention system transmitting terminal produces is carried out orthogonal frequency (OFDM) demodulation through behind the channel at receiving terminal, and receiving terminal extracts the reference signal that is received; The reference signal that reference signal that produces according to transmitting terminal and receiving terminal are received estimates the channel estimation value of two time slots, obtains the initial frequency deviation estimated value according to the channel estimation value of described two time slots; The initial frequency deviation estimated value is carried out timing, is according to interference matrix between subcarrier the channel estimation value of described two time slots to be proofreaied and correct the back to obtain the frequency offset estimating corrected value.

Adopt the present invention, by introducing interference matrix between subcarrier, and according to interference matrix between subcarrier the channel estimation value of described two time slots is proofreaied and correct the back and obtain the frequency offset estimating corrected value, can estimate the frequency offset estimating value under the various channel circumstances exactly, thereby improve accuracy of frequency offset estimation.

Description of drawings

Fig. 1 carries out the realization flow schematic diagram of frequency offset correction for the embodiment of the invention.

Embodiment

Basic thought of the present invention is: by introducing interference matrix between subcarrier, and according to interference matrix between subcarrier the channel estimation value of described two time slots is proofreaied and correct the back and obtain the frequency offset estimating corrected value, can estimate the frequency offset estimating value under the various channel circumstances exactly, thereby improve accuracy of frequency offset estimation.

Be described in further detail below in conjunction with the enforcement of accompanying drawing technical scheme.

The bearing calibration that a kind of OFDMA system frequency deviation is estimated, this method mainly comprises following content:

The reference signal that OFDMA system transmitting terminal produces is carried out the OFDM demodulation through behind the channel at receiving terminal, and receiving terminal extracts the reference signal that is received; The reference signal that reference signal that produces according to transmitting terminal and receiving terminal are received estimates the channel estimation value of two time slots, obtains the initial frequency deviation estimated value according to the channel estimation value of described two time slots; The initial frequency deviation estimated value is carried out timing, is according to interference matrix between subcarrier the channel estimation value of described two time slots to be proofreaied and correct the back to obtain the frequency offset estimating corrected value.The frequency offset estimating corrected value of this frequency offset estimating corrected value for finally obtaining after the initial frequency deviation estimated value is proofreaied and correct.

Further, the reference signal that described reference signal that produces according to transmitting terminal and receiving terminal are received estimates the channel estimation value of two time slots, obtains the initial frequency deviation estimated value according to the channel estimation value of described two time slots and specifically comprises:

The reference signal reference that a1, OFDMA system transmitting terminal produce is through extracting reference signal receive_reference after receiving terminal carries out the OFDM demodulation behind the channel.Wherein, at reference, actual is to have sent 2 reference signals a subframe, that is to say that the value of reference has 2; At receive_reference, be actually a subframe and received 2 reference signals, that is to say that the value of receive_reference has 2, distinguish mutually with the value of reference.In addition, the signal of receiving terminal this locality also comprises the local reference signal identical with the value of reference, that is to say, this local reference signal also is 2, and identical with the value of reference.

A2, choose an adequate resources piece (RB), adopt the channel estimation methods of prior OFDM system,, estimate the channel estimation value of two time slots, be respectively h and h ' according to receive_reference and reference.Wherein, at the computational methods of h and h ', if the value of 2 reference is respectively A1, A2; Make the value of 2 receive_reference be respectively B1, B2; Make the receiving terminal local reference signal identical with the value of reference, the value of 2 local reference signals is respectively C1=A1, C2=A2; H=B1-C1 then; H '=B2-C2.

A3, obtain the phase difference θ between h and the h ', and by Obtain corresponding initial frequency deviation estimated value freq_offset.

Further, describedly according to interference matrix between subcarrier the channel estimation value of described two time slots is proofreaied and correct the back and obtain the frequency offset estimating corrected value and specifically comprise;

B1, obtain new h and h ' respectively with A (γ) * receive_reference, wherein A (γ) is an interference matrix between subcarrier, γ=-freq_offset/ Δ f, γ is a frequency offseting value, Δ f is the frequency interval between subcarrier, and wherein the computational process of A (γ) is as follows:

$\mathrm{\β}=\sin (\mathrm{\π}*\mathrm{\γ})*\exp (\mathrm{j\π}*\mathrm{\γ}*\left(\frac{N-1}{N}\right));$

w _-3＝exp(-jπ*(-3)/N)/(N*sin(π*(-3+γ)/N))*β；

w _-2＝exp(-jπ*(-2)/N)/(N*sin(π*(-2+γ)/N))*β；

w _-1＝exp(-jπ*(-1)/N)/(N*sin(π*(-1+γ)/N))*β；

w ₀＝exp(-jπ*(0)/N)/(N*sin(π*(0+γ)/N))*β；

w ₁＝exp(-jπ*(1)/N)/(N*sin(π*(1+γ)/N))*β；

w ₂＝exp(-jπ*(2)/N)/(N*sin(π*(2+γ)/N))*β；

w ₃＝exp(-jπ*(3)/N)/(N*sin(π*(3+γ)/N))*β；

$A\left(\mathrm{\γ}\right)=\left(\begin{array}{cccccccccccc}{w}_0& w_1& w_2& w_3& 0& 0& 0& 0& 0& 0& 0& 0\\ w_{-1}& w_0& w_1& w_2& w_3& 0& 0& 0& 0& 0& 0& 0\\ w_{-2}& w_{-1}& w_0& w_1& w_2& w_3& 0& 0& 0& 0& 0& 0\\ w_{-3}& w_{-2}& w_{-1}& w_0& w_1& w_2& w_3& 0& 0& 0& 0& 0\\ 0& w_{-3}& w_{-2}& w_{-1}& w_0& w_1& w_2& w_3& 0& 0& 0& 0\\ 0& 0& w_{-3}& w_{-2}& w_{-1}& w_0& w_1& w_2& w_3& 0& 0& 0\\ 0& 0& 0& w_{-3}& w_{-2}& w_{-1}& w_0& w_1& w_2& w_3& 0& 0\\ 0& 0& 0& 0& w_{-3}& w_{-2}& w_{-1}& w_0& w_1& w_2& w_3& 0\\ 0& 0& 0& 0& 0& w_{-3}& w_{-2}& w_{-1}& w_0& w_1& w_2& w_3\\ 0& 0& 0& 0& 0& 0& w_{-3}& w_{-2}& w_{-1}& w_0& w_1& w_2\\ 0& 0& 0& 0& 0& 0& 0& w_{-3}& w_{-2}& w_{-1}& w_0& w_1\\ 0& 0& 0& 0& 0& 0& 0& 0& w_{-3}& w_{-2}& w_{-1}& w_0\end{array}\right);$

Wherein, N is the sampling number that the OFDMA system bandwidth is determined, β is a coefficient of frequency shift (FS), supposes that current subcarrier is k, w _-3Be the interference coefficient of the subcarrier of k-3, w _-2Be the interference coefficient of the subcarrier of k-2, w _-1Be the interference coefficient of the subcarrier of k-1, w ₀Be the interference coefficient of current subcarrier, w ₁Be the interference coefficient of the subcarrier of k+1, w ₂Be the interference coefficient of the subcarrier of k+2, w ₃It is the interference coefficient of the subcarrier of k+3.Currently get 12 subcarrier and form an A (γ), can obtain the interference matrix A (γ) of 12 subcarriers.

B2, with among the above-mentioned b1 of the present invention, be different from prior art by introducing A (γ), and the new h and the h ' that calculate according to A (γ) * receive_reference, the above-mentioned a2 of repeated using, a3 calculate the formula of h and h ', finally obtain new freq_offset (the frequency offset estimating corrected value that new freq_offset finally obtains after being the initial frequency deviation estimated value being proofreaied and correct).

Here it is to be noted: prove that through emulation this repetitive process is through after once, initial frequency deviation estimated value freq_offset is more near the actual frequency deviations value, and this repetitive process 1 time and effect repeatedly are very approaching, so the present invention adopts once and repeats, and at last through the above-mentioned new freq_offset that once repeats to obtain as final frequency offset estimating value.

Below to the present invention's elaboration of giving an example.

Embodiment: the frequency offset estimating with the LTE up-line system is an example.

In the present embodiment, a subframe has two time slots, and 12 subcarriers are arranged on the RB, and subcarrier spacing is Δ f=15000Hz, and fixedly frequency deviation is set to 800Hz.If it is 20MHz that the system bandwidth of current employing is set, corresponding sampling points is counted N=2048, adopts Cyclic Prefix in the normal ofdm system (normalCP).The reference signal that transmitting terminal generates condition according to the rules is mapped in the resource grid, and generation single-carrier frequency division multiple access (SC-FDMA) symbol is launched.Through behind the channel, receiving terminal receives the data of eating dishes without rice or wine, and extracts transmitting terminal through the reference signal behind the channel, and carries out following frequency offset estimating in view of the above, and carries out frequency offset estimating by the A (γ) that the present invention introduces and proofread and correct.

Wherein, present embodiment carries out the frequency offset estimating correcting process, as shown in Figure 1, may further comprise the steps:

Step 101, the reference signal receive_reference and the local reference signal reference that obtain according to reception carry out least square (LS, Least Square) channel estimating, select a RB, obtain the channel estimation value h and the h ' of last two time slots of this RB.

Step 102, calculate the phase difference of h and h ', and calculate the initial frequency deviation estimated value by phase difference θ

Here owing to be normal CP, therefore, a subframe has 14 symbols, and it is 1ms that the position of two reference symbols is respectively 3 and 10, one subframe durations, so the time interval between two reference signals

The initial frequency deviation estimated value freq_offset that calculates thus is 773Hz.

The frequency offseting value γ that step 103, basis obtain calculates interference matrix A (γ) between the subcarrier on the current RB.Because most inter-carrier interference (ICI) is that influence is bigger between adjacent nearest several subcarriers, thus current get near the subcarrier about each 3 subcarrier calculate their influences.This moment N=2048.

$\mathrm{\β}=\sin (\mathrm{\π}*0.02)*\exp (\mathrm{j\π}*0.02*\left(\frac{2048-1}{2048}\right));$

w _-3＝exp(-jπ*(-3)/2048)/(2048*sin(π*(-3+0.02)/2048))*β；

w _-2＝exp(-jπ*(-2)/2048)/(2048*sin(π*(-2+0.02)/2048))*β；

w _-1＝exp(-jπ*(-1)/2048)/(2048*sin(π*(-1+0.02)/2048))*β；

w ₀＝exp(-jπ*(0)/2048)/(2048*sin(π*(0+0.02)/2048))*β；

w ₁＝exp(-jπ*(1)/2048)/(2048*sin(π*(1+0.02)/2048))*β；

w ₂＝exp(-jπ*(2)/2048)/(2048*sin(π*(2+0.02)/2048))*β；

w ₃＝exp(-jπ*(3)/2048)/(2048*sin(π*(3+0.02)/2048))*β；

$A=\left(\begin{array}{cccccccccccc}{w}_0& w_1& w_2& w_3& 0& 0& 0& 0& 0& 0& 0& 0\\ w_{-1}& w_0& w_1& w_2& w_3& 0& 0& 0& 0& 0& 0& 0\\ w_{-2}& w_{-1}& w_0& w_1& w_2& w_3& 0& 0& 0& 0& 0& 0\\ w_{-3}& w_{-2}& w_{-1}& w_0& w_1& w_2& w_3& 0& 0& 0& 0& 0\\ 0& w_{-3}& w_{-2}& w_{-1}& w_0& w_1& w_2& w_3& 0& 0& 0& 0\\ 0& 0& w_{-3}& w_{-2}& w_{-1}& w_0& w_1& w_2& w_3& 0& 0& 0\\ 0& 0& 0& w_{-3}& w_{-2}& w_{-1}& w_0& w_1& w_2& w_3& 0& 0\\ 0& 0& 0& 0& w_{-3}& w_{-2}& w_{-1}& w_0& w_1& w_2& w_3& 0\\ 0& 0& 0& 0& 0& w_{-3}& w_{-2}& w_{-1}& w_0& w_1& w_2& w_3\\ 0& 0& 0& 0& 0& 0& w_{-3}& w_{-2}& w_{-1}& w_0& w_1& w_2\\ 0& 0& 0& 0& 0& 0& 0& w_{-3}& w_{-2}& w_{-1}& w_0& w_1\\ 0& 0& 0& 0& 0& 0& 0& 0& w_{-3}& w_{-2}& w_{-1}& w_0\end{array}\right);$

Step 104, initial frequency deviation estimated value freq_offset is carried out timing, earlier obtain new h and h ' respectively with A (γ) * receive_reference, wherein A (γ) is an interference matrix between subcarrier, γ=-freq_offset/ Δ f, γ is a frequency offseting value, and Δ f is the frequency interval between subcarrier; The new h and the h ' that will obtain again, repeated execution of steps 102, step 103 are to obtain new freq_offset, and this moment, freq_offset was 795Hz, and the frequency offset estimating corrected value that finally obtains after promptly the initial frequency deviation estimated value being proofreaied and correct is 795Hz.

The corrective system that a kind of OFDMA system frequency deviation is estimated, this system comprises: demodulation and initial frequency deviation estimation unit, initial frequency deviation are estimated correcting unit.Wherein, demodulation and initial frequency deviation estimation unit are used for the reference signal of OFDMA system transmitting terminal generation and carry out the OFDM demodulation through behind the channel at receiving terminal, and receiving terminal extracts the reference signal that is received; The reference signal that reference signal that produces according to transmitting terminal and receiving terminal are received estimates the channel estimation value of two time slots, obtains the initial frequency deviation estimated value according to the channel estimation value of described two time slots.Initial frequency deviation estimates that correcting unit is used for the initial frequency deviation estimated value is carried out timing, is according to interference matrix between subcarrier the channel estimation value of described two time slots to be proofreaied and correct the back to obtain the frequency offset estimating corrected value.

Here, demodulation and initial frequency deviation estimation unit are further used for calculating under the initial frequency deviation estimated value situation, obtain phase difference according to the channel estimation value of two time slots, calculate the initial frequency deviation estimated value according to described phasometer.

Here, initial frequency deviation estimates that correcting unit is further used for according to interference matrix between subcarrier the channel estimation value of described two time slots being proofreaied and correct the back and obtains under the frequency offset estimating corrected value situation, to initial frequency deviation estimated value timing, calculate interference matrix between subcarrier, obtain the channel estimation value of two new time slots according to the reference signal that interference matrix and described receiving terminal received between described subcarrier, channel estimation value according to two new time slots obtains phase difference, calculates the frequency offset estimating corrected value according to described phasometer.

Here, initial frequency deviation estimates that correcting unit is further used for calculating when interference matrix is specially A (γ) between subcarrier, and the computing formula that is adopted is:

$A\left(\mathrm{\γ}\right)=\left(\begin{array}{cccccccccccc}{w}_0& w_1& w_2& w_3& 0& 0& 0& 0& 0& 0& 0& 0\\ w_{-1}& w_0& w_1& w_2& w_3& 0& 0& 0& 0& 0& 0& 0\\ w_{-2}& w_{-1}& w_0& w_1& w_2& w_3& 0& 0& 0& 0& 0& 0\\ w_{-3}& w_{-2}& w_{-1}& w_0& w_1& w_2& w_3& 0& 0& 0& 0& 0\\ 0& w_{-3}& w_{-2}& w_{-1}& w_0& w_1& w_2& w_3& 0& 0& 0& 0\\ 0& 0& w_{-3}& w_{-2}& w_{-1}& w_0& w_1& w_2& w_3& 0& 0& 0\\ 0& 0& 0& w_{-3}& w_{-2}& w_{-1}& w_0& w_1& w_2& w_3& 0& 0\\ 0& 0& 0& 0& w_{-3}& w_{-2}& w_{-1}& w_0& w_1& w_2& w_3& 0\\ 0& 0& 0& 0& 0& w_{-3}& w_{-2}& w_{-1}& w_0& w_1& w_2& w_3\\ 0& 0& 0& 0& 0& 0& w_{-3}& w_{-2}& w_{-1}& w_0& w_1& w_2\\ 0& 0& 0& 0& 0& 0& 0& w_{-3}& w_{-2}& w_{-1}& w_0& w_1\\ 0& 0& 0& 0& 0& 0& 0& 0& w_{-3}& w_{-2}& w_{-1}& w_0\end{array}\right);$

Wherein, when the number of current subcarrier is k, w _-3Be the interference coefficient of the subcarrier of k-3, w _-2Be the interference coefficient of the subcarrier of k-2, w _-1Be the interference coefficient of the subcarrier of k-1, w ₀Be the interference coefficient of current subcarrier, w ₁Be the interference coefficient of the subcarrier of k+1, w ₂Be the interference coefficient of the subcarrier of k+2, w ₃Be the interference coefficient of the subcarrier of k+3, γ is a frequency offseting value.

Here, initial frequency deviation estimates that correcting unit is further used for calculating described w _-3, described w _-2, described w _-1, described w ₀, described w ₁, described w ₂With described w ₃The time, the computing formula of Cai Yonging is specially respectively:

w _-3＝exp(-jπ*(-3)/N)/(N*sin(π*(-3+γ)/N))*β；

w _-2＝exp(-jπ*(-2)/N)/(N*sin(π*(-2+γ)/N))*β；

w _-1＝exp(-jπ*(-1)/N)/(N*sin(π*(-1+γ)/N))*β；

w ₀＝exp(-jπ*(0)/N)/(N*sin(π*(0+γ)/N))*β；

w ₁＝exp(-jπ*(1)/N)/(N*sin(π*(1+γ)/N))*β；

w ₂＝exp(-jπ*(2)/N)/(N*sin(π*(2+γ)/N))*β；

w ₃＝exp(-jπ*(3)/N)/(N*sin(π*(3+γ)/N))*β；

Wherein, γ=-freq_offset/ Δ f; Described β is the coefficient of frequency shift (FS); Described freq_offset/ Δ f is the initial frequency deviation estimated value, and Δ f is the frequency interval between subcarrier; The sampling number that described N determines for the OFDMA system bandwidth.

The above is preferred embodiment of the present invention only, is not to be used to limit protection scope of the present invention.

Claims (10)

1. bearing calibration that the OFDMA system frequency deviation is estimated is characterized in that this method comprises:

OFDM inserts the reference signal of (OFDMA) system transmitting terminal generation and carries out orthogonal frequency (OFDM) demodulation through behind the channel at receiving terminal, and receiving terminal extracts the reference signal that is received;

The reference signal that reference signal that produces according to transmitting terminal and receiving terminal are received estimates the channel estimation value of two time slots, obtains the initial frequency deviation estimated value according to the channel estimation value of described two time slots;

The initial frequency deviation estimated value is carried out timing, is according to interference matrix between subcarrier the channel estimation value of described two time slots to be proofreaied and correct the back to obtain the frequency offset estimating corrected value.

2. method according to claim 1, it is characterized in that, obtaining the initial frequency deviation estimated value according to the channel estimation value of described two time slots specifically comprises: the channel estimation value according to two time slots obtains phase difference, calculates the initial frequency deviation estimated value according to described phasometer.

3. method according to claim 1, it is characterized in that, describedly according to interference matrix between subcarrier the channel estimation value of described two time slots is proofreaied and correct the back and obtain the frequency offset estimating corrected value and specifically comprise: to initial frequency deviation estimated value timing, calculate interference matrix between subcarrier, obtain the channel estimation value of two new time slots according to the reference signal that interference matrix and described receiving terminal received between described subcarrier, channel estimation value according to two new time slots obtains phase difference, calculates the frequency offset estimating corrected value according to described phasometer.

4. according to claim 2 or 3 described methods, it is characterized in that interference matrix is specially A (γ) between described subcarrier, the computing formula that is adopted is:

$A\left(\mathrm{\γ}\right)=\left(\begin{array}{cccccccccccc}{w}_0& w_1& w_2& w_3& 0& 0& 0& 0& 0& 0& 0& 0\\ w_{-1}& w_0& w_1& w_2& w_3& 0& 0& 0& 0& 0& 0& 0\\ w_{-2}& w_{-1}& w_0& w_1& w_2& w_3& 0& 0& 0& 0& 0& 0\\ w_{-3}& w_{-2}& w_{-1}& w_0& w_1& w_2& w_3& 0& 0& 0& 0& 0\\ 0& w_{-3}& w_{-2}& w_{-1}& w_0& w_1& w_2& w_3& 0& 0& 0& 0\\ 0& 0& w_{-3}& w_{-2}& w_{-1}& w_0& w_1& w_2& w_3& 0& 0& 0\\ 0& 0& 0& w_{-3}& w_{-2}& w_{-1}& w_0& w_1& w_2& w_3& 0& 0\\ 0& 0& 0& 0& w_{-3}& w_{-2}& w_{-1}& w_0& w_1& w_2& w_3& 0\\ 0& 0& 0& 0& 0& w_{-3}& w_{-2}& w_{-1}& w_0& w_1& w_2& w_3\\ 0& 0& 0& 0& 0& 0& w_{-3}& w_{-2}& w_{-1}& w_0& w_1& w_2\\ 0& 0& 0& 0& 0& 0& 0& w_{-3}& w_{-2}& w_{-1}& w_0& w_1\\ 0& 0& 0& 0& 0& 0& 0& 0& w_{-3}& w_{-2}& w_{-1}& w_0\end{array}\right);$

Wherein, when the number of current subcarrier is k, w _-3Be the interference coefficient of the subcarrier of k-3, w _-2Be the interference coefficient of the subcarrier of k-2, w _-1Be the interference coefficient of the subcarrier of k-1, w ₀Be the interference coefficient of current subcarrier, w ₁Be the interference coefficient of the subcarrier of k+1, w ₂Be the interference coefficient of the subcarrier of k+2, w ₃Be the interference coefficient of the subcarrier of k+3, γ is a frequency offseting value.

5. method according to claim 4 is characterized in that, described w _-3, described w _-2, described w _-1, described w ₀, described w ₁, described w ₂With described w ₃The computing formula of Cai Yonging is specially respectively:

w _-3＝exp(-jπ*(-3)/N)/(N*sin(π*(-3+γ)/N))*β；

w _-2＝exp(-jπ*(-2)/N)/(N*sin(π*(-2+γ)/N))*β；

w _-1＝exp(-jπ*(-1)/N)/(N*sin(π*(-1+γ)/N))*β；

w ₀＝exp(-jπ*(0)/N)/(N*sin(π*(0+γ)/N))*β；

w ₁＝exp(-jπ*(1)/N)/(N*sin(π*(1+γ)/N))*β；

w ₂＝exp(-jπ*(2)/N)/(N*sin(π*(2+γ)/N))*β；

w ₃＝exp(-jπ*(3)/N)/(N*sin(π*(3+γ)/N))*β；

Wherein,

γ=-freq_offset/ Δ f; Described β is the coefficient of frequency shift (FS); Described freq_offset/ Δ f is the initial frequency deviation estimated value, and Δ f is the frequency interval between subcarrier; The sampling number that described N determines for the OFDMA system bandwidth, above-mentioned j is an imaginary unit, j ²=-1.

6. the corrective system that the OFDMA system frequency deviation is estimated is characterized in that this system comprises: demodulation and initial frequency deviation estimation unit, initial frequency deviation estimation correcting unit; Wherein,

Described demodulation and initial frequency deviation estimation unit, the reference signal that is used for the transmitting terminal generation of OFDMA system is carried out the OFDM demodulation through behind the channel at receiving terminal, and receiving terminal extracts the reference signal that is received; The reference signal that reference signal that produces according to transmitting terminal and receiving terminal are received estimates the channel estimation value of two time slots, obtains the initial frequency deviation estimated value according to the channel estimation value of described two time slots;

Described initial frequency deviation is estimated correcting unit, is used for the initial frequency deviation estimated value is carried out timing, is according to interference matrix between subcarrier the channel estimation value of described two time slots to be proofreaied and correct the back to obtain the frequency offset estimating corrected value.

7. system according to claim 6, it is characterized in that described demodulation and initial frequency deviation estimation unit are further used for calculating under the initial frequency deviation estimated value situation, channel estimation value according to two time slots obtains phase difference, calculates the initial frequency deviation estimated value according to described phasometer.

8. system according to claim 6, it is characterized in that, described initial frequency deviation is estimated correcting unit, being further used for according to interference matrix between subcarrier the channel estimation value of described two time slots being proofreaied and correct the back obtains under the frequency offset estimating corrected value situation, to initial frequency deviation estimated value timing, calculate interference matrix between subcarrier, obtain the channel estimation value of two new time slots according to the reference signal that interference matrix and described receiving terminal received between described subcarrier, channel estimation value according to two new time slots obtains phase difference, calculates the frequency offset estimating corrected value according to described phasometer.

9. according to claim 7 or 8 described systems, it is characterized in that described initial frequency deviation is estimated correcting unit, is further used for calculating when interference matrix is specially A (γ) between subcarrier, the computing formula that is adopted is:

$A\left(\mathrm{\γ}\right)=\left(\begin{array}{cccccccccccc}{w}_0& w_1& w_2& w_3& 0& 0& 0& 0& 0& 0& 0& 0\\ w_{-1}& w_0& w_1& w_2& w_3& 0& 0& 0& 0& 0& 0& 0\\ w_{-2}& w_{-1}& w_0& w_1& w_2& w_3& 0& 0& 0& 0& 0& 0\\ w_{-3}& w_{-2}& w_{-1}& w_0& w_1& w_2& w_3& 0& 0& 0& 0& 0\\ 0& w_{-3}& w_{-2}& w_{-1}& w_0& w_1& w_2& w_3& 0& 0& 0& 0\\ 0& 0& w_{-3}& w_{-2}& w_{-1}& w_0& w_1& w_2& w_3& 0& 0& 0\\ 0& 0& 0& w_{-3}& w_{-2}& w_{-1}& w_0& w_1& w_2& w_3& 0& 0\\ 0& 0& 0& 0& w_{-3}& w_{-2}& w_{-1}& w_0& w_1& w_2& w_3& 0\\ 0& 0& 0& 0& 0& w_{-3}& w_{-2}& w_{-1}& w_0& w_1& w_2& w_3\\ 0& 0& 0& 0& 0& 0& w_{-3}& w_{-2}& w_{-1}& w_0& w_1& w_2\\ 0& 0& 0& 0& 0& 0& 0& w_{-3}& w_{-2}& w_{-1}& w_0& w_1\\ 0& 0& 0& 0& 0& 0& 0& 0& w_{-3}& w_{-2}& w_{-1}& w_0\end{array}\right);$

Wherein, when the number of current subcarrier is k, w _-3Be the interference coefficient of the subcarrier of k-3, w _-2Be the interference coefficient of the subcarrier of k-2, w _-1Be the interference coefficient of the subcarrier of k-1, w ₀Be the interference coefficient of current subcarrier, w ₁Be the interference coefficient of the subcarrier of k+1, w ₂Be the interference coefficient of the subcarrier of k+2, w ₃Be the interference coefficient of the subcarrier of k+3, γ is a frequency offseting value.

10. system according to claim 9 is characterized in that, described initial frequency deviation is estimated correcting unit, is further used for calculating described w _-3, described w _-2, described w _-1, described w ₀, described w ₁, described w ₂With described w ₃The time, the computing formula of Cai Yonging is specially respectively:

w _-3＝exp(-jπ*(-3)/N)/(N*sin(π*(-3+γ)/N))*β；

w _-2＝exp(-jπ*(-2)/N)/(N*sin(π*(-2+γ)/N))*β；

w _-1＝exp(-jπ*(-1)/N)/(N*sin(π*(-1+γ)/N))*β；

w ₀＝exp(-jπ*(0)/N)/(N*sin(π*(0+γ)/N))*β；

w ₁＝exp(-jπ*(1)/N)/(N*sin(π*(1+γ)/N))*β；

w ₂＝exp(-jπ*(2)/N)/(N*sin(π*(2+γ)/N))*β；

w ₃＝exp(-jπ*(3)/N)/(N*sin(π*(3+γ)/N))*β；

Wherein,

γ=-freq_offset/ Δ f; Described β is the coefficient of frequency shift (FS); Described freq_offset/ Δ f is the initial frequency deviation estimated value, and Δ f is the frequency interval between subcarrier; The sampling number that described N determines for the OFDMA system bandwidth, above-mentioned j is an imaginary unit, j ²=-1.

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