CN105933262A - CFO (Carrier Frequency Offset) method based on double training sequences - Google Patents

CFO (Carrier Frequency Offset) method based on double training sequences Download PDF

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CN105933262A
CN105933262A CN201610349050.XA CN201610349050A CN105933262A CN 105933262 A CN105933262 A CN 105933262A CN 201610349050 A CN201610349050 A CN 201610349050A CN 105933262 A CN105933262 A CN 105933262A
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cfo
training sequences
steps
double training
double
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CN105933262B (en
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肖清华
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Huaxin Consulting Co Ltd
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Huaxin Consulting Co Ltd
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes
    • H04L27/2601—Multicarrier modulation systems
    • H04L27/2647—Arrangements specific to the receiver only
    • H04L27/2655—Synchronisation arrangements
    • H04L27/2657—Carrier synchronisation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes
    • H04L27/2601—Multicarrier modulation systems
    • H04L27/2647—Arrangements specific to the receiver only
    • H04L27/2655—Synchronisation arrangements
    • H04L27/2689—Link with other circuits, i.e. special connections between synchronisation arrangements and other circuits for achieving synchronisation
    • H04L27/2695—Link with other circuits, i.e. special connections between synchronisation arrangements and other circuits for achieving synchronisation with channel estimation, e.g. determination of delay spread, derivative or peak tracking

Abstract

The invention discloses a CFO (Carrier Frequency Offset) method based on double training sequences. The method comprises the steps of establishing a transceiving model, adding the double training sequences, synthesizing received signals, capturing an offset factor, estimating a CFO and the like; two different training sequences are added to initial signals, and different received signals are synthesized, so that the influence of noise on frequency offset estimation is completely counteracted. The method has the characteristics of simplifying the calculation quantity, having high capture precision, reducing frequency offset, weakening synchronous errors, reducing the bit error rate of a system and improving customer perception.

Description

CFO methods of estimation based on double training sequences
Technical field
The CFO (Carrier Frequency Offset, carrier frequency offset) that the present invention relates to a kind of LTE system estimates Method, especially relates to a kind of CFO method of estimation based on double training sequences.
Background technology
LTE is the communication system that 3GPP is the most developing, and LTE is by taking OFDM (Orthogonal Frequency Division Multiplexing, OFDM) multichannel mode, each subcarrier is overlapped, greatly Width promote system spectrum efficiency, be very suitable for being wirelessly transferred of high data rate, this be also LTE compare 2/3G technology can One of reason that cell throughout is greatly improved.
Problematically, competence exertion performance when OFDM needs each subcarrier to keep its orthogonality, the quickest to synchronous error Sense, and present in the multidiameter fading channel of practical radio communication environment ISI (Intern Symbol Interference, symbol Between disturb) carrier frequency offset CFO and symbol time offset STO (Symbol Timing Offset) can be caused, cause error code Rate improves, LTE system hydraulic performance decline.
It addition, the tiny frequency deviation existed between transmitter carrier frequency and receiver local oscillator, and due to The Doppler frequency shift that the receiving-transmitting sides relative motion of communication produces also results in the generation of CFO.
Summary of the invention
The goal of the invention of the present invention is to overcome under in LTE network of the prior art, CFO deviation causes OFDM performance The deficiency of fall, it is provided that a kind of CFO methods of estimation based on double training sequences.
To achieve these goals, the present invention is by the following technical solutions:
A kind of CFO method of estimation based on double training sequences, comprises the steps:
(1-1) transmitting-receiving model is set up；
(1-2) double training sequence is added；
(1-3) signal syntheses is received；
(1-4) capture deflection factor；
(1-5) estimation CFO.
The present invention includes setting up transmitting-receiving model, adds double training sequence, receives signal syntheses, captures deflection factor, estimation The steps such as CFO；Add two kinds of different training sequences to initial signal, different reception signals is synthesized, and then completely Offset the impact that frequency deviation is estimated by noise.Compare tradition simpler based on data-aided algorithm for estimating, can solve again blind simultaneously The problem of algorithm for estimating acquisition accuracy difference.
The present invention utilizes double training sequence can offset the impact that frequency deviation is estimated by noise, the most in a multi-path environment can Preferably reduce frequency departure, give full play to the orthogonal performance of each subcarrier of LTE, weaken synchronous error, reduce error rate of system, Promote client perception.
As preferably, described step (1-1) comprises the steps:
The transmitting signal setting transmitting-receiving model is a length of N, N=N of y (n), x (n) as x (n), reception signalg 2, y (n) =x (n) * δ (ε)+w (n), wherein, δ (ε) is signal deflection factor, and ε is CFO to be evaluated, and w (n) is interchannel noise, NgFor often Number, n=O ..., N-1；
As preferably, described step (1-2) comprises the steps:
In transmitting-receiving model, add two kinds of different training sequences u (n) and v (n), respectively obtain z1(n)=u (n) * δ (ε) + w (n) and z2(n)=v (n) * δ (ε)+w (n).
As preferably, described step (1-3) comprises the steps:
(4-1) formula Z (n)=Z is utilized1(n)-Z2N () calculates Z (n), utilize formula T (n)=u (n)-v (n) to calculate T (n)；
(4-2) formula Z is utilizedcN ()=inv (T (n)) * Z (n) calculates composite signal ZcN (), wherein inv () represents square The inversion operation of battle array.
As preferably, described step (1-4) comprises the steps:
To composite signal ZcN in (), all elements is sued for peace, obtain deflection factor
As preferably, step (1-5) comprises the steps:
(6-1) formula R is utilizedε=δ (ε)/N calculates deflection factor Rε；
(6-2) formula is utilizedCalculating ε, wherein, Re () represents the real part seeking imaginary number Function, j represents imaginary unit.
Therefore, there is advantages that
The CFO methods of estimation based on double training sequences of the present invention, utilize different training sequences, the docking collection of letters number to carry out Synthesis, thus the interference of interchannel noise is completely eliminated, and draw the frequency deflection launching and receiving signal.
, there is not the requirement of complexity to training sequence in the CFO evaluation methods based on double training sequences of the present invention, thus Simplified operation amount as much as possible can be carried out by means of the special sequence such as unitary matrice or diagonal matrix；
Decrease frequency departure, given full play to the orthogonal performance of each subcarrier of LTE, weakened synchronous error, reduce Error rate of system, improves client perception.
Accompanying drawing explanation
Fig. 1 is a kind of flow chart of the present invention；
Fig. 2 is to estimate comparison diagram without a kind of CFO frequency deviation during interchannel noise；
A kind of CFO frequency deviation when Fig. 3 is to have interchannel noise estimates comparison diagram.
Detailed description of the invention
The present invention will be further described with detailed description of the invention below in conjunction with the accompanying drawings.
Embodiment as shown in Figure 1 is a kind of based on double training sequence CFO methods of estimation, including setting up transmitting-receiving model, adds Add double training sequence, receive signal syntheses, capture the steps such as deflection factor, estimation CFO.
Step 1: set up transmitting-receiving model；
The transmitting signal setting transmitting-receiving model is a length of N, N=N of y (n), x (n) as x (n), reception signalg 2, y (n) =x (n) * δ (ε)+w (n), wherein, δ (ε) is signal deflection factor, and ε is CFO to be evaluated, and w (n) is interchannel noise, NgFor often Number, n=O ..., N-1；
Step 2: add double training sequence；
In transmitting-receiving model, add two kinds of different training sequences u (n) and v (n), respectively obtain z1(n)=u (n) * δ (ε) + w (n) and z2(n)=v (n) * δ (ε)+w (n)；
Step 3: receive signal syntheses
Step 3-1: utilize formula Z (n)=Z1(n)-Z2N () calculates Z (n), utilize formula T (n)=u (n)-v (n) to calculate T (n)；
Step 3-2: utilize formula ZcN ()=inv (T (n)) * Z (n) calculates composite signal ZcN (), wherein inv () represents The inversion operation of matrix；
Step 4: capture deflection factor；
To composite signal ZcN in (), all elements is sued for peace, obtain deflection factor
Step 5: estimation CFO；
Step 5-1: utilize formula Rε=δ (ε)/N calculates deflection factor Rε；
Step 5-2: utilize formulaCalculating ε, wherein, Re () represents the reality seeking imaginary number Portion's function, j represents imaginary unit.
Below with N=4, NgAs a example by=2 being specifically described the present invention, representative basis data are as shown in table 1:
Table 1
Sequence number Project Data
1 Signal to noise ratio (SNR) 20
2 Noise signal AWGN
Step 1: set up transmitting-receiving model；
Additive white Gaussian noise is utilized to generate channel noise signals
W (n)=awgn (rand (2,2)+i*rand (2,2), SNR)=[8.0993,3.7845；2.7965,1.8394],
Gained transmitting-receiving model is y (n)=x (n) * δ (ε)+w (n)；
Step 2: add double training sequence；
The double training sequence of stochastic generation
U (n)=rand (2,2)=[0.8329,0.5252；0.9399,0.9216] and
V (n)=rand (2,2)=[0.0623,0.5987；0.3040,0.1252].
Respectively obtain
z1(n)=[94574+0.0022i, 5.1425+0.0137i；4.6579+0.0039i, 3.7007+
0.0197i]) and
z2(n)=[8.7602+0.0025i, 4.44540.0081i；3.2256+0.0005i, 2.2685+
0.0042i]；
Step 3: receive signal syntheses
Step 3-1: calculate
Z (n)=Z1(n)-Z2(n)=[0.6971-0.0003i, 0.6971+0.0056i；1.4323+
0.0034i, 1.4322+0.0155i],
And T (n)=u (n)-v (n)=[0.7706 ,-0.0735；0.6359,0.7964]；
Step 3-2: calculate composite signal
Zc(n)=inv (T (n)) * Z (n)=[1.0000+0.0000i, 1.0000+0.0085i；1.0000+
0.0042i, 0.9999+0.0127i]；
Step 4: capture deflection factor；
To composite signal ZcN in (), all elements is sued for peace, obtain deflection factor
Step 5: estimation CFO；
Step 5-1: calculate
Step 5-2: calculate
By the present invention and tradition method of estimation based on CP, based on leading Moose method of estimation and based on pilot tone The method that Classen estimates just without being contrasted under interchannel noise and two kinds of scenes of noise jamming, sees shown in Fig. 2, Fig. 3.
As in figure 2 it is shown, be can be seen that by comparing result, TTSE method, under identical signal to noise ratio snr premise, possesses less Least mean-square error MSE.For comparing other method, TTSE is more insensitive to noise.
As it is shown on figure 3, on the premise of there is interchannel noise, TTSE possesses better performance.
Should be understood that the present embodiment is merely to illustrate the present invention rather than limits the scope of the present invention.In addition, it is to be understood that After having read the content that the present invention lectures, the present invention can be made various changes or modifications by those skilled in the art, these etc. Valency form falls within the application appended claims limited range equally.

Claims (6)

1. CFO methods of estimation based on double training sequences, is characterized in that, comprise the steps:
(1-1) transmitting-receiving model is set up；
(1-2) double training sequence is added；
(1-3) signal syntheses is received；
(1-4) capture deflection factor；
(1-5) estimation CFO.
CFO method of estimation based on double training sequences the most according to claim 1, is characterized in that, described step (1-1) is wrapped Include following steps:
The transmitting signal setting transmitting-receiving model is a length of N, N=N of y (n), x (n) as x (n), reception signalg 2, y (n)=x N () * δ (ε)+w (n), wherein, δ (ε) is signal deflection factor, and ε is CFO to be evaluated, and w (n) is interchannel noise, NgFor constant, N=0 ..., N-1.
CFO method of estimation based on double training sequences the most according to claim 1, is characterized in that, described step (1-2) is wrapped Include following steps:
In transmitting-receiving model, add two kinds of different training sequences u (n) and v (n), respectively obtain z1(n)=u (n) * δ (ε)+w (n) And z2(n)=v (n) * δ (ε)+w (n).
CFO method of estimation based on double training sequences the most according to claim 1, is characterized in that, described step (1-3) is wrapped Include following steps:
(4-1) formula Z (n)=Z is utilized1(n)-Z2N () calculates Z (n), utilize formula T (n)=u (n)-v (n) to calculate T (n)；
(4-2) formula Z is utilizedcN ()=inv (T (n)) * Z (n) calculates composite signal Zc(n), wherein inv () representing matrix Inversion operation.
CFO method of estimation based on double training sequences the most according to claim 1, is characterized in that, described step (1-4) is wrapped Include following steps:
To composite signal ZcN in (), all elements is sued for peace, obtain deflection factor
6. according to the CFO methods of estimation based on double training sequences described in claim 1 or 2 or 3 or 4 or 5, it is characterized in that, step Suddenly (1-5) comprises the steps:
(6-1) formula R is utilizedε=δ (ε)/N calculates deflection factor Rε；
(6-2) formula is utilizedCalculating ε, wherein, Re () represents the real part functions seeking imaginary number, J represents imaginary unit.
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CN114584438A (en) * 2022-01-05 2022-06-03 华信咨询设计研究院有限公司 5G CFO estimation method based on reference carrier frequency offset
CN114584447A (en) * 2022-01-12 2022-06-03 华信咨询设计研究院有限公司 5G CFO estimation method based on offset noise

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Cited By (4)

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Publication number Priority date Publication date Assignee Title
CN114584438A (en) * 2022-01-05 2022-06-03 华信咨询设计研究院有限公司 5G CFO estimation method based on reference carrier frequency offset
CN114584438B (en) * 2022-01-05 2023-08-15 华信咨询设计研究院有限公司 5G CFO estimation method based on reference carrier frequency offset
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