CN102014094A - Intelligent calibration method of antenna transmitting channel and antenna receiving channel and relevant device - Google Patents

Abstract

The invention discloses an intelligent calibration method of an antenna transmitting channel and an antenna receiving channel and a relevant device, which is used for solving the problem that signals transmitted in an LTE (Long Term Evolution) system can not be calibrated accurately by the traditional antenna calibration technology. The method comprises the following steps of: determining frequency domain calibration factors corresponding to subcarriers loading signals to be sent, exchanging the time domain estimation value of each transmitting channel, which is isolated from the time domain signal received by the calibration channel, to obtain the frequency domain estimation value of each subcarrier of each transmitting channel by the frequency domain calibration factors, and determining the frequency domain calibration factors corresponding to the subcarriers according to the frequency domain estimation value of each subcarrier; and when sending signals, calibrating the signals to be sent according to the determined frequency domain calibration factors corresponding to the subcarriers.

Description

The calibration steps of smart antenna transmission channel and receive path and relevant apparatus

Technical field

The present invention relates to the mobile communication technology field, relate in particular to the calibration steps of a kind of method of definite smart antenna transmission channel frequency domain calibration factor, a kind of smart antenna transmission channel, a kind of method of definite smart antenna receive path frequency domain calibration factor, a kind of calibration steps of smart antenna receive path, a kind of calibrating installation of smart antenna transmission channel and a kind of calibrating installation of smart antenna receive path.

Background technology

Accompanying drawing 1 comprises baseband signal processing unit, at least one antenna, at least one radio-frequency (RF) transceiver, at least one coupler, closes road splitter and calibrating signal processing unit for the structural representation of intelligent antenna array system in the existing TD-SCDMA network in this system.Usually in the time of will transmitting, the path that is formed by connecting by coupler, radio frequency sender, baseband signal processing unit is called transmission channel; During with received signal, the path that is formed by connecting by coupler, radio frequency receiver, baseband signal processing unit is called receive path; Be called calibrated channel with closing the path that the road splitter is formed by connecting.

The process that the signal of transmission channel transmission is calibrated is as follows:

(1) baseband signal processing unit sends calibrating sequence at the protection time slot of TD-SCDMA radio frames, and calibrating sequence is generated by the code word cyclic shift at time domain orthogonal;

(2) calibrating signal enters calibrated channel through radio frequency sender, multi-channel rf passage, coupler, mixer;

(3) the calibrating signal processing unit receives the calibrating signal that multichannel is superimposed by receiver;

(4) the calibrating signal processing unit utilizes the time domain orthogonal of calibrating signal, calculates amplitude and phase place that radio-frequency channel, every road sends signal;

(5) the calibrating signal processing unit calculates calibration factor, and sends baseband signal processing unit to;

(6) baseband signal processing unit compensates radio-frequency channel, every road transmission signal times with calibration factor.

Above-mentioned steps (1) to step (5) normally utilizes the protection interval (GP, Guard Period) between sending signal by smart antenna time slot and the received signal time slot to finish.

The process that the signal of receive path reception is calibrated is as follows:

(1) the calibrating signal processing unit sends calibrating sequence at the protection time slot of TD-SCDMA radio frames, and calibrating sequence is generated by the code word cyclic shift at time domain orthogonal;

(2) calibrating signal enters each radio-frequency channel, road of aerial array through radio frequency sender, calibrated channel, splitter, coupler;

(3) baseband signal processing unit receives each road calibrating signal respectively by the receiver of multi-channel rf passage, and each road calibrating signal is transmitted to the calibrating signal processing unit;

(4) the calibrating signal processing unit calculates amplitude and the phase place that radio-frequency channel, every road receives calibrating signal;

(5) the calibrating signal processing unit calculates calibration factor, and sends baseband signal processing unit to;

(6) baseband signal processing unit multiply by calibration factor with radio-frequency channel, every road received signal and compensates.

Above-mentioned steps (1) to step (5) normally utilizes the protection interval (GP, Guard Period) between sending signal by smart antenna time slot and the received signal time slot to finish.

In the TD-SCDMA network, frequency bandwidth (1.6MHz) shared during transmission signals is narrower, thereby can think between the signal that each transmission channel sends or signal that each receive path receives between frequency domain characteristic do not have significant difference, thereby for all transmission channels, only need compensate on amplitude and phase place the signal that each transmission channel sends with one group of time domain calibration factor; Equally, for all receive paths, only need compensate on amplitude and phase place the signal that each receive path receives, can obtain good signal calibration effect with one group of time domain calibration factor.

Yet, for Long Term Evolution (LTE, Long Term Evolution) network, because shared frequency bandwidth broad during transmission signals, be generally 10MHz～20MHz, the bandwidth that takies than TD-SCDMA Network Transmission signal many, therefore the difference of frequency domain characteristic can cause very important influence to signal between the signal that sends of each transmission channel or between the signal that receives of each receive path, if still adopt the antenna calibration method in the above-mentioned TD-SCDMA network, can not obtain good calibration effect.

Summary of the invention

The embodiment of the invention provides a kind of calibration steps of smart antenna transmission channel and a kind of calibration steps of smart antenna receive path, can't be to transmitting and problem that received signal is accurately calibrated in the LTE system in order to solve in the existing collimation technique.

Accordingly, the embodiment of the invention also provides a kind of method of definite smart antenna transmission channel frequency domain calibration factor, a kind of method of definite smart antenna receive path frequency domain calibration factor, a kind of calibrating installation of smart antenna transmission channel and a kind of calibrating installation of smart antenna receive path.

The technical scheme that the embodiment of the invention provides is as follows:

A kind of method of definite smart antenna transmission channel frequency domain calibration factor comprises:

Isolate the time domain estimated value of every road transmission channel from the time-domain signal that calibrated channel receives, described time-domain signal is to be generated by the subcarrier time-domain signal coupling that carries calibrating sequence that each road transmission channel sends, and

Time domain estimated value to every road transmission channel is carried out conversion, obtains the frequency domain estimated value of every road each subcarrier of transmission channel; And

According to the frequency domain estimated value of each subcarrier that obtains, determine the frequency domain calibration factor of each subcarrier correspondence.

A kind of calibration steps of smart antenna transmission channel comprises:

Determine the frequency domain calibration factor of the subcarrier correspondence of carrying signal to be sent, the frequency domain calibration factor of described subcarrier is for to carry out conversion to the time domain estimated value of isolated every road transmission channel the time-domain signal that receives from calibrated channel, to obtain the frequency domain estimated value of every road each subcarrier of transmission channel, according to the frequency domain estimated value of each subcarrier that obtains, determine again;

When sending signal,, signal to be sent is calibrated according to the frequency domain calibration factor of the subcarrier correspondence of determining.

A kind of calibrating installation of smart antenna transmission channel comprises:

Separative element is used for isolating from the time-domain signal that calibrated channel receives the time domain estimated value of every road transmission channel, and described time-domain signal is to be generated by the subcarrier time-domain signal coupling that carries calibrating sequence that each road transmission channel sends;

Determining unit is used at every road transmission channel, and carry out: the time domain estimated value to this transmission channel is carried out conversion, obtains the frequency domain estimated value of this each subcarrier of transmission channel; And, determine the frequency domain calibration factor of each subcarrier correspondence according to the frequency domain estimated value that obtains;

Alignment unit is used for when sending signal, and the frequency domain calibration factor of the subcarrier correspondence of the carrying signal of determining according to determining unit to be sent is calibrated signal to be sent.

A kind of method of definite smart antenna receive path frequency domain calibration factor comprises:

Obtain the subcarrier time-domain signal that carries calibrating sequence that calibrated channel that each receive path receives respectively sends;

The subcarrier time-domain signal that every road receive path is received carries out conversion, obtains the frequency domain estimated value of the subcarrier time-domain signal that every road receive path receives; And

The corresponding relation of the subcarrier of symbol in the frequency domain estimated value of the subcarrier time-domain signal that receives according to the every road receive path that obtains, the symbol in the calibrating sequence and the carrying calibrating sequence is determined the frequency domain estimated value of each subcarrier in the receive path of every road;

According to the frequency domain estimated value of each subcarrier that obtains, determine the frequency domain calibration factor of each subcarrier correspondence.

A kind of calibration steps of smart antenna receive path comprises:

Determine the frequency domain calibration factor of the subcarrier correspondence of carrying signal, the frequency domain estimated value of the subcarrier time-domain signal that described frequency domain calibration factor receives for the every road receive path that carries out conversion according to the subcarrier time-domain signal that every road receive path is received and obtain is determined;

During received signal, according to determine the frequency domain calibration factor of subcarrier correspondence, calibrate to the received signal.

A kind of calibrating installation of smart antenna receive path comprises:

Acquiring unit is used to obtain the subcarrier time-domain signal that carries calibrating sequence that calibrated channel that each receive path receives respectively sends;

Determining unit is used for the subcarrier time-domain signal that every road receive path receives is carried out conversion, obtains the frequency domain estimated value of the subcarrier time-domain signal that every road receive path receives; And the corresponding relation of the subcarrier of symbol in the frequency domain estimated value of the subcarrier time-domain signal that receives according to the every road receive path that obtains, the symbol in the calibrating sequence and the carrying calibrating sequence, determine the frequency domain estimated value of each subcarrier in the receive path of every road; According to the frequency domain estimated value of each subcarrier that obtains, determine the frequency domain calibration factor of each subcarrier correspondence;

Alignment unit, when being used for received signal, the frequency domain calibration factor of the subcarrier correspondence of the carrying signal of determining according to determining unit is calibrated to the received signal.

The embodiment of the invention will send to calibrated channel for the symbols carry in the corresponding calibrating sequence of each road transmission channel appointment on each subcarrier of transmission channel for transmission channel; From the time-domain signal that calibrated channel obtains, isolate the time domain estimated value of every road transmission channel, time domain estimated value to every road transmission channel correspondence is carried out the frequency domain estimated value that FFT obtains each subcarrier correspondence in this transmission channel, thereby determine the frequency domain calibration factor of each subcarrier according to the frequency domain estimated value of each subcarrier, when sending signal, according to the time domain estimated value and the frequency domain calibration factor of the send channel correspondence that obtains, signal to be sent is calibrated;

For receive path, obtain the time-domain signal that carries calibrating sequence that each receive path receives respectively; The time-domain signal that every road receive path is received carries out FFT respectively, obtains the frequency domain estimated value of each subcarrier correspondence in this transmission channel, thereby determines the frequency domain calibration factor of each subcarrier and the time domain estimated value of this receive path correspondence; When received signal, time domain estimated value and frequency domain calibration factor according to the receive channel correspondence of determining, calibrate to the received signal, by the frequency domain calibration factor of introducing in the such scheme, the radio-frequency channel calibration program that the embodiment of the invention proposes can be calibrated the frequency characteristic difference between each radio-frequency channel, thereby can accurately calibrate the signal that intelligent antenna array transmitted in the LTE network.

Description of drawings

Fig. 1 is the structural representation of intelligent antenna array system in the existing TD-SCDMA network;

Fig. 2 carries out the flow chart of calibration process for what the embodiment of the invention proposed to transmission channel;

Fig. 3 carries out the flow chart of calibration process for what the embodiment of the invention proposed to receive path;

Fig. 4 carries the schematic diagram of the shared channel time slot of the time-domain signal of calibrating sequence for emission in the embodiment of the invention;

Fig. 5 is when carrying out transmission channel calibration and receive path calibration in the embodiment of the invention, and transmission carries the schematic diagram of the shared channel time slot of the time-domain signal of calibrating sequence;

Fig. 6 a carries out transmission channel when calibration in the embodiment of the invention, send the schematic diagram of the shared channel time slot of the time-domain signal that carries calibrating sequence;

Fig. 6 b carries out receive path when calibration in the embodiment of the invention, send the schematic diagram of the shared channel time slot of the time-domain signal that carries calibrating sequence;

The structural representation of the calibrating installation of the smart antenna transmission channel that Fig. 7 provides for the embodiment of the invention;

The structural representation of the calibrating installation of the smart antenna receive path that Fig. 8 provides for the embodiment of the invention.

Embodiment

The LTE system is a wide-band communication system, adopts the OFDM transmission means, and system is a plurality of subcarriers with the frequency band division of using at first, data to be transmitted is mapped on a plurality of subcarriers simultaneously transmits, with increase system opposing multipath interference capability.

Yet existing intelligent antenna calibration technology but can't effectively be calibrated the difference of the frequency response between each radio-frequency channel of different frequency in the LTE network.

The intelligent antenna calibration method that the embodiment of the invention proposes is when calibrating transmission channel, the calibrating signal processing unit is after the time domain estimated value that obtains each transmission channel, time domain estimated value to each transmission channel is carried out fast Fourier transform (FFT, Fast Fourier Transform), determine the frequency domain calibration factor of transmission channel correspondence in view of the above, baseband signal processing unit is calibrated subcarrier according to the time domain estimated value and the frequency domain calibration factor of the transmission channel correspondence of determining when sending signal; Similarly, when receive channel is calibrated, the calibrating sequence that the calibrating signal processing unit receives each receive path (being the time domain estimated value) carries out FFT, determine the frequency domain calibration factor of receive path correspondence in view of the above, when baseband signal processing unit receives signal, according to the use estimated value and the frequency domain calibration factor of receive path correspondence, calibrate to the received signal.

To introduce two embodiment in detail and come the main realization principle of the inventive method is explained in detail and illustrates according to inventive principle of the present invention below.

Embodiment one

Please refer to accompanying drawing 2, in the present embodiment transmission channel being carried out the flow chart of calibration process, smart antenna has k transmission channel in the present embodiment.

Step 201, baseband signal processing unit is determined the calibrating sequence that every road transmission channel is corresponding respectively, the calibrating sequence of each transmission channel correspondence should have frequency domain autocorrelation and time domain autocorrelation preferably, is quadrature between the calibrating sequence of each transmission channel correspondence.For example select for use the ZC sequence as calibration root sequence, when determining the calibrating sequence of k road transmission channel difference correspondence,,, obtain the calibrating sequence of other k-1 road transmission channel correspondences by the cyclic shift method with the calibrating sequence of ZC sequence as the 1 road transmission channel correspondence;

Step 202, at each transmission channel, baseband signal processing unit is with each subcarrier to this transmission channel of the sign map in the calibrating sequence of this transmission channel correspondence;

Suppose that the LTE network bandwidth is D MHz, comprises M _ScIndividual subcarrier, for the transmission channel of k road, the n (0≤n＜M in this transmission channel _Sc) content of individual sub-carriers carry is r _k(n) (r _k(n) can be the symbol in the calibrating sequence of this transmission channel correspondence, also can be sky, be to determine by the corresponding relation of symbol in the calibrating signal and subcarrier, provided the symbol in 3 kinds of calibrating sequences and the corresponding relation of subcarrier in the present embodiment), the time-domain signal that baseband signal processing unit sends to k road transmission channel can be expressed as:

$x_k\left(m\right)=\frac{1}{M_{\mathrm{SC}}}\underset{n=0}{\overset{M_{\mathrm{BC}}-1}{\mathrm{\Σ}}}{r}_k\left(n\right)\exp \left(j2\mathrm{\π}\frac{\mathrm{nm}}{M_{\mathrm{sc}}}\right),m=0\mathrm{LL}{M}_{\mathrm{sc}}-1---(1-1)$

Step 203 comprises that the transmission channel of radio-frequency (RF) transceiver, coupler will send to calibrated channel with the time-domain signal that the mode in the step 202 is being carried calibrating sequence;

K road transmission channel is sending time-domain signal x _k(m) before, should be at x _k(m) add 144 Cyclic Prefix (CP, Circulation Prefix) in and obtain x _k' (m), with x _k' (m) send to calibration channel.

Step 204, calibrating signal processing unit are obtained time-domain signal y ' that the time-domain signal that is sent by each road transmission channel that calibrated channel receives is superimposed (m),

$y^{\′}\left(m\right)=\underset{k=1}{\overset{K}{\mathrm{\Σ}}}{x}_k^{\′}\left(m\right)*h_k\left(m\right)+w\left(m\right)---(1-2)$

Wherein, h _k(m) channel fading of expression radio-frequency channel k, w (m) represents the Gaussian noise summation of all transmission channels, * represents convolution.

Step 205, calibrating signal processing unit according to the time-domain signal y ' that gets access in the step 204 (m) are determined the frequency domain estimated value of the transmission channel that is superimposed

Y ' (m) is removed 144 CP obtains y (m), y (m) is carried out FFT obtain Y (n),

$Y\left(n\right)=\underset{k=1}{\overset{K}{\mathrm{\Σ}}}{r}_k\left(n\right)H_k\left(n\right)+w\left(n\right),n=0,...M_{\mathrm{SC}}-1---(1-3)$

Wherein, H _k(n) be corresponding frequency domain channel decline to obtaining behind radio-frequency channel, k road time domain channel decline the carrying out FFT,

From Y (n), obtain the overall frequency domain estimated value of send channel

Concrete grammar is as follows:

According to the corresponding relation of symbol in the calibrating signal and subcarrier, determine to carry the frequency domain estimated value Y (n of the subcarrier of the symbol in the calibrating sequence _i), n wherein _iIt is the subcarrier sign that carries symbol i;

Wherein c (i) is an i symbol in the calibrating sequence root sequence;

Be the overall corresponding frequency domain estimated value of the subcarrier that carries all transmission channels of i symbol in the calibrating sequence;

Step 206, the signal frequency-domain estimated value that the calibrating signal processing unit sends the transmission channel that is superimposed

Carry out inverse FFT (IFFT, Inverse Fast Fourier Transform), determine corresponding time domain estimated value

$h^{\%}\left(m\right)=\frac{1}{M_{\mathrm{sc}}^{\mathrm{AC}}}\underset{i=0}{\overset{M_{\mathrm{sc}}^{\mathrm{AC}}-1}{\mathrm{\Σ}}}{H}^{\%}\left(i\right)\exp \left(j2\mathrm{\π}\frac{\mathrm{im}}{M_{\mathrm{sc}}^{\mathrm{AC}}}\right),m=0\mathrm{LL}{M}_{\mathrm{sc}}^{\mathrm{AC}}-1---(1-4)$

Step 207, calibrating signal processing unit are utilized the cyclic shift characteristic of calibrating sequence, the time domain estimated value of the signal that sends from the send channel that is superimposed

In isolate the time domain estimated value of the signal that each road transmission channel sends

${\tilde{h}}_k=[\tilde{h}((k-1)\·W+1),\tilde{h}((k-1)\·W+2),....,\tilde{h}(k\·W)],k=1,\mathrm{LL},K---(1-5)$

Wherein, W is for estimating length of window, and K is an antenna amount, W=calibrating sequence length / antenna amount K.

Step 208, calibrating signal processing unit basis is determined

Judge that time-domain signal peak value that each road transmission channel sends and time delay are whether in preset range, if enter step 209; Otherwise, think corresponding transmission channel fault, calibrating signal processing unit record dependent failure, and notice baseband signal processing unit do not carry out subsequent treatment and handle resource to save;

Judge that the time-domain signal peak value of transmission channel transmission and the detailed process whether time delay meets the demands are:

At first definite

The size of peak value and the character position when peak value occurring, peak information CIR _{K, i}Represent that k transmission channel peak value occurs on i symbol in calibrating sequence,

${\mathrm{CIR}}_{k,i}=f_{\max }\left(h_k^{\%}\right),k=1,\mathrm{LL},K$

CIR _{K, i}Be plural number, comprised amplitude and phase information when peak value appears in k road transmission channel.

Secondly, determine the peak information of every road transmission channel

K=1, whether L L, K in the predetermined threshold scope of peak amplitude, promptly judge CIR _{K, i}∈ [C _Low, C _High] whether set up;

Then, when the peak amplitude of k road transmission channel is in the predetermined threshold scope, judge whether the character position that occurs peak value in the radio-frequency channel, every road is identical, promptly judge for different k values, CIR _{K, i}, k=1, L L, whether the i value among the K is identical.

For example, be 40 characters in calibrating sequence length, the quantity of transmission channel is 8 o'clock, the estimation length of window is W=5, knows that according to (1-5) peak information of each transmission channel is as follows:

${\mathrm{CIR}}_{\mathrm{1,1}}=f_{\max }(\tilde{h}\left(1\right),\tilde{h}\left(2\right),...,\tilde{h}\left(5\right)),$

${\mathrm{CIR}}_{\mathrm{2,1}}=f_{\max }(\tilde{h}\left(6\right),\tilde{h}\left(7\right),...,\tilde{h}\left(10\right)),$

${\mathrm{CIR}}_{\mathrm{3,1}}=f_{\max }(\tilde{h}\left(11\right),\tilde{h}\left(12\right),...,\tilde{h}\left(15\right)),$

${\mathrm{CIR}}_{\mathrm{4,1}}=f_{\max }(\tilde{h}\left(16\right),\tilde{h}\left(17\right),...,\tilde{h}\left(20\right)),$

${\mathrm{CIR}}_{\mathrm{5,1}}=f_{\max }(\tilde{h}\left(21\right),\tilde{h}\left(22\right),...,\tilde{h}\left(25\right)),$

${\mathrm{CIR}}_{\mathrm{6,1}}=f_{\max }(\tilde{h}\left(26\right),\tilde{h}\left(27\right),...,\tilde{h}\left(30\right)),$

${\mathrm{CIR}}_{\mathrm{7,1}}=f_{\max }(\tilde{h}\left(31\right),\tilde{h}\left(32\right),...,\tilde{h}\left(35\right)),$

${\mathrm{CIR}}_{\mathrm{8,1}}=f_{\max }(\tilde{h}\left(36\right),\tilde{h}\left(37\right),...,\tilde{h}\left(40\right)).$

If above-mentioned CIR _1,1To CIR _8,1All in the predetermined peak amplitude threshold range, i.e. CIR _{K, 1}∈ [C _Low, C _High], k=1 ..., 8, and all in calibrating sequence the position of the 1st symbol peak value appears, illustrate that the amplitude of 8 transmission channels and time delay are all normal; Otherwise, if CIR _1,1To CIR _8,1In arbitrary CIR _{K, i}, k=1 ..., 8 in the predetermined peak amplitude threshold range, illustrates that corresponding k road transmission channel peak amplitude is undesired, and transmitting power is crossed conference and is caused peak amplitude to surpass predetermined threshold, in order to protect hardware device, at this moment should suitably reduce transmitting power; If it is inconsistent the character position of peak value to occur, for example CIR _2,2The time delay that the 2 road transmission channel is described is undesired, thinks that the 2 road transmission channel breaks down.

Step 209, calibrating signal processing unit send the time domain estimated value of signal to every road transmission channel

Carry out FFT, obtain corresponding frequency domain estimated value

And with basis

The frequency domain calibration factor of each road transmission channel correspondence of determining sends to baseband signal processing unit;

The detailed process of determining the frequency domain calibration factor is as follows:

For the symbol in the 1st kind, the 2nd kind, the 3rd kind calibrating sequence and the corresponding relation of subcarrier, at first obtain the same average transmit power of subcarrier frequently in each transmission channel, be about to the 1st subcarrier in the transmitting power, the 2 road transmission channel of the 1st subcarrier in the 1 road transmission channel transmitting power ..., the transmitting power of the 1st subcarrier adds and averages in the 8 road transmission channel, obtains the average transmit power of the 1st subcarrier

K=1 wherein ..., K represents the transmission channel sign, n represents the subcarrier sign,

Determine the frequency domain calibration factor calib_factor of each subcarrier in the transmission channel of k road according to the average transmit power of above-mentioned each subcarrier of determining _k(n), calib_factor _k(n) be plural number

K=1 wherein ..., K.

For the subcarrier that does not carry the symbol in the calibrating sequence, owing to do not obtain the frequency domain channel estimated result, can't calculate calibration factor, the calibration factor that can adopt the immediate subcarrier of frequency is as this subcarrier calibration factor.

Preferably, in order to reduce calibration factor storage capability in the baseband signal processor, can the shared same frequency domain calibration factor of a plurality of subcarriers, in this case, determine that the process of the frequency domain calibration factor that a plurality of subcarriers are shared is as follows:

Predetermined N _cThe shared same frequency domain calibration factor of individual subcarrier is at first determined N _cThe mean value of individual sub-carrier frequency domain estimated value;

N wherein _i∈ [1, N _Sc],

And then calculate the average transmit power of each subcarrier;

K=1 wherein ..., K is the transmission channel sign,

Sign for subcarrier mean value;

Determine the frequency domain calibration factor calib_factor of each subcarrier in the transmission channel of k road according to the average transmit power of above-mentioned each subcarrier of determining _k(n), calib_factor _k(n) be plural number

K=1 wherein ..., K.

In the actual alignment process, in a calibration cycle, repeatedly determine the frequency domain calibration factor usually, the mean value of asking for the frequency domain calibration factor of repeatedly determining is as the frequency domain calibration factor that is used for carrying out transmitting the frequency domain adjustment;

Step 210, the frequency domain calibration factor that baseband signal processing unit is determined according to step 209 is calibrated the signal to be sent that is carried on the subcarrier.The frequency-region signal frequency domain calibration factor corresponding with k road transmission channel for example that k road transmission channel is to be sent multiplies each other, and compensates with amplitude and phase place to signal to be sent.

In step 202, the symbol in the calibrating sequence and the corresponding relation of subcarrier can have following 3 kinds:

1, one-to-one relationship

The symbol quantity that comprises at calibrating sequence

With the number of subcarriers M in the transmission channel used band _ScIdentical, promptly

The time, give a unique subcarrier with each symbol in the calibrating sequence is corresponding, promptly each subcarrier is all carrying in the calibrating sequence and the unique corresponding symbol of this subcarrier;

2, corresponding relation uniformly-spaced

Usually can select to comprise the less calibrating sequence of symbol quantity the symbol quantity that comprises at calibrating sequence for use for the complexity that reduces calibration calculations Less than the number of subcarriers M in the transmission channel used band _ScThe time, give equally distributed parton carrier wave in the transmission channel used band with each allocation of symbols in the calibrating sequence one by one, for example in calibrating sequence, comprise 3 symbols, and when 9 subcarriers are arranged, give the 3rd subcarrier with the 1st allocation of symbols in the calibrating sequence, give the 6th subcarrier with the 2nd allocation of symbols, give the 9th subcarrier the 3rd allocation of symbols;

3, sub-band corresponding relation

Similar with the 2nd kind of corresponding relation, this corresponding relation can use and comprise the less calibrating sequence of symbol a large amount of subcarriers are calibrated.The transmission channel used band is divided into the B sub-frequency bands, in each sub-band M is arranged _Sc/ B subcarrier; One by one with corresponding unique subcarrier in each sub-band or the subcarrier that is spacedly distributed given of each symbol in the calibrating sequence.For example calibrating sequence comprises 3 symbols, 30 subcarriers are arranged in the transmission channel used band, if be divided into 10 sub-frequency bands, have under the situation of 3 subcarriers in each sub-band, the 1st allocation of symbols in the calibrating sequence can be given the 1st subcarrier in each sub-band, give the 2nd subcarrier in each sub-band with the 2nd allocation of symbols, give the 3rd subcarrier in each subcarrier the 3rd allocation of symbols; Be divided into 3 sub-frequency bands, have under the situation of 10 subcarriers in each sub-band, give the 3rd subcarrier in each sub-band with the 1st allocation of symbols in the calibrating sequence, give the 6th subcarrier in each sub-band with the 2nd allocation of symbols, give the 9th subcarrier in each sub-band the 3rd allocation of symbols.

Embodiment two

Please refer to accompanying drawing 3, in the present embodiment receive path being carried out the flow chart of calibration process, smart antenna has k road transmission channel in the present embodiment.

Step 301, the calibrating signal processing unit is determined the calibrating sequence of calibrated channel correspondence;

Step 302, the calibrating signal processing unit is given the allocation of symbols in the calibrating sequence of calibrated channel correspondence each subcarrier of calibrated channel, symbol in the concrete branch timing calibrating sequence and the corresponding relation between each subcarrier please refer to the description among the embodiment one, here repeat no more;

Step 303, calibrated channel is by closing the time-domain signal x that the road splitter will carry calibrating sequence _k(m) send to k road receive path, wherein

$x_k\left(m\right)=\frac{1}{M_{\mathrm{sc}}}\underset{n=0}{\overset{M_{\mathrm{sc}}}{\mathrm{\Σ}}}r\left(n\right)\exp \left(j2\mathrm{\π}\frac{\mathrm{nm}}{M_{\mathrm{sc}}}\right),m=0\mathrm{LL}{M}_{\mathrm{sc}}-1---(2-1)$

R in (2-1) (n) is the content of n sub-carriers carry, and according to the corresponding relation of symbol in the calibrating sequence in the step 301 and subcarrier, r (n) may be the symbol in the calibrating sequence, also may be sky.

Calibrated channel is sending x _k(m) before, also should be at x _k(m) add 144 cyclic prefix CP in, will add the x of Cyclic Prefix _k' (m) send to receive path.

Step 304, the time-domain signal y ' that is carrying calibrating sequence that k road receive path will receive respectively _k(m) send to baseband signal processing unit, wherein,

y′ _k(m)＝x′(m)*h _k(m)+w _k(m) (2-2)

H in (2-2) _k(m) be the decline of receive path k, w _k(m) be Gaussian noise in the receive path of k road.

Step 305, the time-domain signal that baseband signal processing unit receives each receive path is transmitted to the calibrating signal processing unit;

Step 306, calibrating signal processing unit are removed the time-domain signal y ' that calibrating sequence is being carried on the k road respectively _k(m) 144 CP in obtain y _k(m), to y _k(m) carry out FFT, obtain corresponding frequency domain estimated value Y _k(n), wherein

Y _k(n)＝r _k(n)H _k(n)+w _k(n)，n＝0，...，M _sc-1 (2-3)

Step 307, calibrating signal processing unit carry the frequency domain estimated value Y of the signal correspondence of calibrating sequence according to the k road of determining in the step 306 _k(n), determine the frequency domain calibration factor calib_factor of each road receive path correspondence _k(n);

H in (2-3) _k(n) be the channel frequency domain estimated value of receive path k.

According to the corresponding relation of symbol in the calibrating sequence in the step 302 and subcarrier, determine to be carried on the calibrating sequence Y on the subcarrier _{K, c}(n _i), n wherein _iFor carrying the subcarrier sign of the symbol in the calibrating sequence

$H_k^{\%}\left(i\right)=Y_{k,c}\left(n_i\right)/c\left(i\right),k=1,\mathrm{LL},K---(2-4)$

Because

Be to determine according to the time-domain signal that each receive path receives respectively, so basis

Can determine the frequency domain calibration factor of each road receive path correspondence, the method for specifically determining please refer to the description in embodiment one step 209.

Step 308, the calibrating signal processing unit is to determining in the step 307

Carry out IFFT, obtain the time domain estimated value of each receive path correspondence

$h_k^{\%}\left(m\right)=\frac{1}{M_{\mathrm{sc}}^{\mathrm{AC}}}\underset{i=0}{\overset{M_{\mathrm{sc}}^{\mathrm{AC}}-1}{\mathrm{\Σ}}}{H}_k^{\%}\left(i\right)\exp \left(j2\mathrm{\π}\frac{\mathrm{im}}{M_{\mathrm{sc}}^{\mathrm{AC}}}\right),m=0\mathrm{LL}{M}_{\mathrm{sc}}^{\mathrm{AC}}-1$

Also can represent with following formula

${\tilde{h}}_k=[{\tilde{h}}_k\left(0\right),...,{\tilde{h}}_k(M_{\mathrm{sc}}^{\mathrm{AC}}-1)].$

Step 309, the calibrating signal processing unit is according to determining in the step 308

Whether peak amplitude and the time delay of judging each road receive path satisfy pre-provisioning request, if meet the demands, then enter step 310, otherwise think corresponding receive path fault, calibrating signal processing unit record dependent failure, and the notice baseband signal processing unit, do not carry out subsequent treatment and handle resource to save;

Judge that wherein the peak amplitude of receive path and the detailed process whether time delay meets the demands please refer to the description in the step 208 among the embodiment one, repeat no more here.

Step 310, the calibrating signal processing unit is with the frequency domain calibration factor calib_factor of each road receive path correspondence of determining in the step 307 _kSend to baseband signal processing unit;

Step 311, baseband signal processing unit is according to the frequency domain calibration factor, the signal that receive path is received carries out amplitude and phase error compensation, for example the signal transformation that k road receive path is received is multiplied each other to frequency domain and the frequency domain calibration factor corresponding with k road receive path, with this signal that receive path receives is carried out amplitude and phase error compensation.

Please refer to accompanying drawing 4; similar to the collimation technique of existing TD-SCDMA network; transmission channel carries among the time-domain signal of calibrating sequence and the embodiment two calibration channel in transmission and sends when carrying the time-domain signal of calibrating sequence to receive path in embodiment one; all be to utilize the protection interval (GP, guard Period) between uplink pilot time slot UpPTS and the descending pilot frequency time slot DwPTS to finish.Different with the TD-SCDMA network is, can come the different GP length of flexible configuration with the length of descending pilot frequency time slot DwPTS according to uplink pilot time slot UpPTS in the LTE network, be short UpPTS and the long GP of DwPTS distribution, be long UpPTS and the short GP of DwPTS distribution, for example, please refer to table 1, for the longest DwPTS:26336 Ts distributes the shortest GP:2192 Ts, for the shortest DwPTS:6592TS distributes the longest GP:21936 Ts.

Table 1GP allocation list (referring to TS36.211 table 4.2-1)

In real system, when the calibrating sequence of selecting for use self need take 2048 Ts, add the CP of 144Ts during transmission after, need to take 2192Ts altogether, if that as seen adopt during cell configuration is the shortest 2192Ts, calibrating sequence takies whole GP with needs so.For fear of in calibration process, calibrating signal is interfered, and needs the sufficiently long GP of configuration.The GP that specifically selects for use need determine according to the number of timeslots that cell coverage area and calibrating sequence take.Under normal CP condition, dispose under 4, No. 8 special subframes and the expansion CP condition, when disposing 3, No. 6 special subframes, the GP between UpPTS and DwPTS is too short, is easy to be interfered in calibration process, so does not advise selecting for use above allocation plan.

Calibrate when calibrating with two pairs of receive paths of embodiment at a pair of transmission channel of embodiment, can the identical time in GP send calibrating sequence, please refer to accompanying drawing 5, GP length is L _GTs, the time that calibrating sequence need take is L _CTs, then be Δ L=(L the remaining time except that sending calibrating sequence among the GP _G-L _C) T _S, the time that sends calibrating sequence should be selected in the position of GP middle part and close UpPTS, when receive path is calibrated, can reduce the interference that is subjected to neighbor cell DwPTS so as far as possible.For example can select to begin to send calibrating sequence from GP original position 2/3 Δ L.

In that being calibrated, transmission channel also can select for use when receive path is calibrated the time different among the GP to send calibrating sequence.For example, please refer to accompanying drawing 6a, when transmission channel is calibrated, can be in the GP original position, promptly, owing to remaining GP part among the GP behind the transmission calibrating sequence is also longer, can avoid calibrating signal that follow-up upward signal is caused interference like this immediately following behind DwPTS, sending calibrating sequence.Please refer to accompanying drawing 6b, when receive path is calibrated, can in GP, send calibrating sequence in the position near UpPTS, because the GP part before the transmission calibrating sequence is longer, can avoid the downstream signal of other sub-districts that calibrating signal is caused interference like this.

In the LTE network, usually time domain is required relatively stricter, require time delay error between each radio-frequency channel (comprising transmission channel and receive path) less than 65ns, at this moment suggestion uses FFT or IFFT to carry out the time-domain and frequency-domain conversion at 2048 in embodiment one, embodiment two.

The embodiment of the invention is to be that example is introduced and determined the frequency domain calibration factor with calibrating signal processing unit and baseband signal processing unit, and the process of transmission channel and receive path being calibrated according to the frequency domain calibration factor of determining.The function of calibrating signal processing unit or baseband signal processing unit also can be realized by other unit of intelligent antenna array system in the LTE network in the foregoing description.

Accordingly, the embodiment of the invention also provides a kind of calibrating installation of smart antenna transmission channel, and as shown in Figure 7, this device comprises separative element 701, determining unit 702 and alignment unit 703, wherein,

Separative element 701 is used for isolating from the time-domain signal that calibrated channel receives the time domain estimated value of every road transmission channel, and described time-domain signal is to be generated by the subcarrier time-domain signal coupling that carries calibrating sequence that each road transmission channel sends;

Determining unit 702 is used at every road transmission channel, and carry out: the time domain estimated value to this transmission channel is carried out conversion, obtains the frequency domain estimated value of this each subcarrier of transmission channel; And, determine the frequency domain calibration factor of each subcarrier correspondence according to the frequency domain estimated value that obtains;

Alignment unit 703 is used for when sending signal, and the frequency domain calibration factor of the subcarrier correspondence of the carrying signal of determining according to determining unit 702 to be sent is calibrated signal to be sent.

The function of above-mentioned separative element 701, determining unit 702 can be realized by the calibrating signal processing unit in the accompanying drawing 1, the function of alignment unit 703 can be realized by baseband signal processing unit, also can be realized by other component units of intelligent antenna array system.

The embodiment of the invention also provides a kind of calibrating installation of smart antenna receive path, and as shown in Figure 8, this device comprises acquiring unit 801, determining unit 802 and alignment unit 803, wherein,

Acquiring unit 801 is used to obtain the subcarrier time-domain signal that carries calibrating sequence that calibrated channel that each receive path receives respectively sends;

Determining unit 802 is used for the subcarrier time-domain signal that every road receive path receives is carried out conversion, obtains the frequency domain estimated value of the subcarrier time-domain signal that every road receive path receives; And the corresponding relation of the subcarrier of symbol in the frequency domain estimated value of the subcarrier time-domain signal that receives according to the every road receive path that obtains, the symbol in the calibrating sequence and the carrying calibrating sequence, determine the frequency domain estimated value of each subcarrier in the receive path of every road; According to the frequency domain estimated value of each subcarrier that obtains, determine the frequency domain calibration factor of each subcarrier correspondence;

Alignment unit 803, when being used for received signal, the frequency domain calibration factor of the subcarrier correspondence of the carrying signal of determining according to determining unit 802 is calibrated to the received signal.

The function of above-mentioned acquiring unit 801, determining unit 802 can be realized by the calibrating signal processing unit in the accompanying drawing 1, the function of alignment unit 803 can be realized by baseband signal processing unit, also can be realized by other component units of intelligent antenna array system.

Obviously, those skilled in the art can carry out various changes and modification to the present invention and not break away from the spirit and scope of the present invention.Like this, if of the present invention these are revised and modification belongs within the scope of claim of the present invention and equivalent technologies thereof, then the present invention also is intended to comprise these changes and modification interior.

Claims (16)

1. the method for a definite smart antenna transmission channel frequency domain calibration factor is characterized in that, comprising:

Isolate the time domain estimated value of every road transmission channel from the time-domain signal that calibrated channel receives, described time-domain signal is to be generated by the subcarrier time-domain signal coupling that carries calibrating sequence that each road transmission channel sends, and

Time domain estimated value to every road transmission channel is carried out conversion, obtains the frequency domain estimated value of every road each subcarrier of transmission channel; And

According to the frequency domain estimated value of each subcarrier that obtains, determine the frequency domain calibration factor of each subcarrier correspondence.

2. the calibration steps of a smart antenna transmission channel is characterized in that, comprising:

Determine the frequency domain calibration factor of the subcarrier correspondence of carrying signal to be sent, the frequency domain calibration factor of described subcarrier is for to carry out conversion to the time domain estimated value of isolated every road transmission channel the time-domain signal that receives from calibrated channel, to obtain the frequency domain estimated value of every road each subcarrier of transmission channel, determine according to the frequency domain estimated value of each subcarrier that obtains again;

When sending signal,, signal to be sent is calibrated according to the frequency domain calibration factor of the subcarrier correspondence of determining.

3. the method for claim 1 is characterized in that, carries calibrating sequence on the subcarrier time-domain signal that transmission channel sends, and specifically comprises:

Specify corresponding calibrating sequence for every road transmission channel, the calibrating sequence that wherein every road calibrating sequence is corresponding with other transmission channels is a quadrature;

With the symbols carry in the calibrating sequence on the subcarrier time-domain signal of corresponding transmission channel.

4. method as claimed in claim 3 is characterized in that, when the symbol quantity that comprises in calibrating sequence is identical with the number of subcarriers of corresponding transmission channel, with each symbols carry in the calibrating sequence on the subcarrier of unique correspondence.

5. method as claimed in claim 3, it is characterized in that, the symbol quantity that comprises in calibrating sequence is during less than the number of subcarriers of corresponding transmission channel, with the symbols carry in the calibrating sequence on the parton carrier wave, described parton carrier wave is evenly distributed on the total bandwidth of transmission channel, and each symbol in the calibrating sequence is unique corresponding with each subcarrier in the described parton carrier wave; Or

Ratio according to the symbol quantity that comprises in the number of subcarriers of transmission channel and the corresponding calibrating sequence, determine the number of subcarriers of prosign in the carrying calibrating sequence, and the symbol quantity that the calibrating sequence of being separated by between the subcarrier of carrying prosign comprises subtracts 1 subcarrier.

6. as claim 4 or 5 described methods, it is characterized in that, from the time-domain signal that calibrated channel receives, isolate the time domain estimated value of every road transmission channel, specifically comprise:

The time-domain signal that calibrated channel is received carries out conversion, obtains the signal frequency-domain estimated value that calibrated channel receives; And

The corresponding relation of the subcarrier of symbol in the signal frequency-domain estimated value that receives according to calibrated channel, the symbol in the calibrating sequence and the carrying calibrating sequence is determined the frequency domain estimated value of each transmission channel of being superimposed; And

Frequency domain estimated value to each transmission channel of being superimposed is carried out inverse transformation, obtains the time domain estimated value of each transmission channel of being superimposed;

According to the quadrature characteristics between the calibrating sequence of each passage correspondence, from the time domain estimated value of each transmission channel of being superimposed, isolate the time domain estimated value of every road transmission channel by cyclic shift.

7. the method for claim 1 is characterized in that, the time domain estimated value of transmission channel is carried out conversion before, also comprise:

When the performance parameter of determining this transmission channel according to the time domain estimated value of this transmission channel meets pre-provisioning request, carry out described conversion to determine the frequency domain calibration factor of transmission channel; Otherwise, abandon this conversion.

8. the method for claim 1 is characterized in that, according to the frequency domain estimated value of each subcarrier, determines the frequency domain calibration factor of each subcarrier correspondence, is specially:

At each subcarrier, with all transmission channels and this carrier wave with the ratio of the average transmit power of subcarrier frequently and this sub-carrier frequency domain estimated value as the corresponding frequency domain calibration factor of this subcarrier.

9. the method for claim 1 is characterized in that, according to the frequency domain estimated value of each subcarrier, determines the frequency domain calibration factor of each subcarrier correspondence, specifically comprises:

Number of subcarriers N according to predetermined shared same frequency domain calibration factor _c, determine N _cThe mean value of individual sub-carrier frequency domain estimated value; And

Determine the average transmit power of all subcarriers;

Average transmit power and described N with all subcarriers of determining _cThe ratio of the mean value of individual sub-carrier frequency domain estimated value is as described N _cThe frequency domain calibration factor that individual subcarrier is shared.

10. the method for claim 1 is characterized in that, sends the time-domain signal that carries calibrating sequence to calibrated channel with approaching time period of descending pilot frequency time slot in the protection time slot.

11. the calibrating installation of a smart antenna transmission channel is characterized in that, comprising:

Separative element is used for isolating from the time-domain signal that calibrated channel receives the time domain estimated value of every road transmission channel, and described time-domain signal is to be generated by the subcarrier time-domain signal coupling that carries calibrating sequence that each road transmission channel sends;

Determining unit is used at every road transmission channel, and carry out: the time domain estimated value to this transmission channel is carried out conversion, obtains the frequency domain estimated value of this each subcarrier of transmission channel; And, determine the frequency domain calibration factor of each subcarrier correspondence according to the frequency domain estimated value that obtains;

Alignment unit is used for when sending signal, and the frequency domain calibration factor of the subcarrier correspondence of the carrying signal of determining according to determining unit to be sent is calibrated signal to be sent.

12. the method for a definite smart antenna receive path frequency domain calibration factor is characterized in that, comprising:

Obtain the subcarrier time-domain signal that carries calibrating sequence that calibrated channel that each receive path receives respectively sends;

The subcarrier time-domain signal that every road receive path is received carries out conversion, obtains the frequency domain estimated value of the subcarrier time-domain signal that every road receive path receives; And

The corresponding relation of the subcarrier of symbol in the frequency domain estimated value of the subcarrier time-domain signal that receives according to the every road receive path that obtains, the symbol in the calibrating sequence and the carrying calibrating sequence is determined the frequency domain estimated value of each subcarrier in the receive path of every road;

According to the frequency domain estimated value of each subcarrier that obtains, determine the frequency domain calibration factor of each subcarrier correspondence.

13. the calibration steps of a smart antenna receive path is characterized in that, comprising:

Determine the frequency domain calibration factor of the subcarrier correspondence of carrying signal, the frequency domain estimated value of the subcarrier time-domain signal that described frequency domain calibration factor receives for the every road receive path that carries out conversion according to the subcarrier time-domain signal that every road receive path is received and obtain is determined;

During received signal, according to determine the frequency domain calibration factor of subcarrier correspondence, calibrate to the received signal.

14. method as claimed in claim 12 is characterized in that, the frequency domain calibration factor according to the subcarrier correspondence of carrying signal before calibrating to the received signal, also comprises:

Frequency domain estimated value to each subcarrier of receive path of obtaining is carried out conversion, obtains the time domain estimated value of receive path, and

When the performance parameter of determining this receive path according to the time domain estimated value of receive path meets pre-provisioning request, calibrate to the received signal according to the frequency domain calibration factor of subcarrier correspondence; Otherwise, abandon calibration.

15. method as claimed in claim 12 is characterized in that, sends the time-domain signal that carries calibrating sequence to receive path with approaching time period of uplink pilot time slot in the protection time slot.

16. the calibrating installation of a smart antenna receive path is characterized in that, comprising:

Acquiring unit is used to obtain the subcarrier time-domain signal that carries calibrating sequence that calibrated channel that each receive path receives respectively sends;

Determining unit is used for the subcarrier time-domain signal that every road receive path receives is carried out conversion, obtains the frequency domain estimated value of the subcarrier time-domain signal that every road receive path receives; And the corresponding relation of the subcarrier of symbol in the frequency domain estimated value of the subcarrier time-domain signal that receives according to the every road receive path that obtains, the symbol in the calibrating sequence and the carrying calibrating sequence, determine the frequency domain estimated value of each subcarrier in the receive path of every road; According to the frequency domain estimated value of each subcarrier that obtains, determine the frequency domain calibration factor of each subcarrier correspondence;

Alignment unit, when being used for received signal, the frequency domain calibration factor of the subcarrier correspondence of the carrying signal of determining according to determining unit is calibrated to the received signal.

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