CN1314289C - Time solt synchronous detection and channel estimation in mobile communication receiver - Google Patents

Abstract

The present invention relates to the time slot synchronous detection and channel estimation in a mobile communication device-a receiver. In the time slot synchronous detection method used in the mobile communication receiver of the present invention, for a sampling level, a minimum mean square error algorithm is utilized to calculate an RCF (impulse response), and then, a maximum point is detected in the calculated RCF (impulse response) so as to carry out synchronous detection. The method of the present invention is capable of detecting relatively accurate synchronous information and simply obtaining a channel estimation value. The algorithms can be used for designing relevant receivers and can be used on a mobile terminal or a mobile communication device base station.

Description

Slot synchronization in the mobile communication receiver detects and channel estimating

Technical field

The present invention relates to mobile communication, the slot synchronization that is specifically related in mobile communication equipment (mobile phone and the base station) receiver detects and channel estimating.

Background technology

Mobile communcations system (such as GSM, CDMA IS95, WCDMA, TD-SCDMA, CDMA2000) in the physical layer, transmitter adds some bits in each time slot of each send channel, i.e. training sequence, and receiver detects these training sequences and carries out catching of synchronizing information and channel estimating.Catch and the most frequently used method of channel estimating of synchronizing information are to use correlator (correlator).In cdma system, base station transceiver (BTS) is being given each mobile phone sending signal by the method for code division multiple access (CDMA) at the same time with on the same frequency, simultaneously each mobile phone also sends signal to BTS simultaneously, has certain interference so issue between each user's the signal.The training sequence that is transmitted needs certain autocorrelation performance and their cross correlation, but because the cross correlation of training sequence and autocorrelation are not complete perfect conditions, promptly not all to be 0 in all places, so can cause certain interference, particularly under the situation that each user's signal power has a long way to go.

Because LS (Least-squares) algorithm can reduce these interference, adopts the LS algorithm to carry out synchronous detecting and channel estimating usually.

Fig. 1 has described the Mathematical Modeling of training sequence through channel.

Common LS algorithm is all handled at chip-level.Generate a matrix with training sequence, and describe this Mathematical Modeling with a mathematical formulae:

y＝ M* h+n

In above formula, y is the signal that receiver receives, and h is the impulse response (impulse response) of channel, and M is a training sequence.If number of users is 2 in model, h is: $\stackrel{\‾}{h}=\left[\begin{array}{c}{h}_{L,1}\\ h_{L,2}\end{array}\right],...,{\stackrel{\‾}{h}}_{L,n}=\begin{array}{}\end{array}\left[\begin{array}{c}{h}_{0,n}\\ h_{1,n}\\ .\\ .\\ .\\ h_{L,n}\end{array}\right],n=\mathrm{1,2}$

Wherein, L is a channel length, and M is the expression matrix of training sequence: M=[M ₁M ₂].

$M_n=\left[\begin{array}{cccc}{m}_{L,n}& ...& m_{1,n}& m_{0,n}\\ m_{L-1,n}& ...& m_{2,n}& m_{1,n}\\ .& & .& .\\ .& & .& .\\ .& & .& .\\ m_{L+P-1,n}& ...& m_{P,n}& m_{P-1n}\end{array}\right].n=1.2.$

Can obtain then: y=M* h+n

Can be by minimizing (y-M* h) ²Obtain following result:

$\hat{h}={\arg }_h\min {\left|\right|y-\stackrel{\‾}{\mathrm{Mh}}\left|\right|}^2={\left({\stackrel{\‾}{M}}^H\stackrel{\‾}{M}\right)}^{-1}{\stackrel{\‾}{M}}^{H}y.$

In formula, (M ^HM) ^-1Be a constant, in order to reduce the cross correlation of training sequence, if y=M* is h+n, h=(M so ^HM) ^-1M ^H(M* h+n), results estimated will be h=h+ (M ^HM) ^-1M ^H* n is so the interference that is caused by their cross correlation in the training sequence or autocorrelation performance has been balanced out.

But in the slot synchronization detection method of prior art, the error of calculation of other LS algorithm of chip-level is bigger.Fig. 3 has shown the example of the raised cosine filter (RCF (impulse response)) of the method calculating of adopting prior art, and visible error is bigger, carries out synchronous detecting if therefrom find out maximum, then makes mistakes easily.

Therefore, need improve existing synchronization detecting method.

Summary of the invention

Purpose of the present invention promptly is to solve the bigger problem of error in the slot synchronization detection method of prior art.

According to an aspect of the present invention, provide the slot synchronization detection method of using in a kind of mobile communication receiver, may further comprise the steps: on the sampling rank, utilized lms algorithm to calculate raised cosine filter; In the raised cosine filter that calculates, detect maximum point, thereby carry out synchronous detecting.

In the method for the invention, utilizing lms algorithm to calculate in the process of raised cosine filter, the training sequence matrix conversion of chip-level is become the training sequence matrix of sample stage.

Preferably, become in the process of training sequence matrix of sample stage, each element of chip-level training sequence matrix is changed into 8 * 8 diagonal angle submatrix in training sequence matrix conversion with chip-level.

In the method according to the invention, further on the basis of detected synchronizing information, the raised cosine filter that calculates is carried out down-sampling, obtain impulse response, to carry out channel estimating.

According to a further aspect in the invention, provide the receiver in a kind of mobile communcations system, it has: on the sampling rank, utilize lms algorithm to calculate the device of raised cosine filter; And in the raised cosine filter that calculates, detect maximum point, thereby carry out the device of synchronous detecting.

Receiver according to the present invention can further include based on detected synchronizing information, and the raised cosine filter that calculates is carried out down-sampling, thereby obtains the device of impulse response.

According to a further aspect in the invention, also provide a kind of mobile communication base station and terminal, it is characterized in that receiver of the present invention.

Description of drawings

Accompanying drawing helps to understand better the present invention, and in this part in conjunction with formation the application.

In the accompanying drawing:

Fig. 1 has described the Mathematical Modeling of training sequence through channel;

Fig. 2 has shown an example of raised cosine filter being carried out down-sampling;

Fig. 3 has shown the example of the raised cosine filter of the method calculating of adopting prior art;

Fig. 4 has shown the example of the raised cosine filter that adopts method calculating of the present invention;

Fig. 5 has shown the flow chart of method of the calculating raised cosine filter of prior art;

Fig. 6 has shown the flow chart of method of the calculating raised cosine filter of prior art;

Fig. 7 has shown the schematic diagram that comprises receiver of the present invention.

Embodiment

Below the present invention will be described in detail.

In slot synchronization detection method of the present invention, the LS algorithm carries out on sampling rank (samplelevel), and obtains raised cosine filter RCF (Impulse Response), carries out the synchronous detecting of time slot thus.

Here, RCF is the convolution of two RRCF, and RRCF is a root raised cosine filter, that is:

RCF(X)＝RRCF(RRCF(X))

The time domain specification of RRCF commonly used is in mobile communication:

${\mathrm{RC}}_0\left(t\right)\frac{\sin \left(\mathrm{\π}\frac{t}{T_C}(1-\mathrm{\α})\right)+4\mathrm{\α}\frac{t}{T_C}\cos \left(\mathrm{\π}\frac{t}{T_C}(1+\mathrm{\α})\right)}{\mathrm{\π}\frac{t}{T_C}(1-{\left(4\mathrm{\α}\frac{t}{T_C}\right)}^2)}$

If the Metzler matrix on the chip rank is

Then on sample stage, each element will generate 8 * 8 elements, and promptly an element will generate a submatrix, and the value of supposing this element is x (x can be imaginary number), and this submatrix is so:

x，0，0，0，0，0，0，0

0，x，0，0，0，0，0，0

0，0，x，0，0，0，0，0

0，0，0，x，0，0，0，0

0，0，0，0，x，0，0，0

0，0，0，0，0，x，0，0

0，0，0，0，0，0，x，0

0，0，0，0，0，0，0，x

Become a big Metzler matrix in that these submatrixs are merged then, then the Metzler matrix on the sampling rank is:

$M=\left(\begin{array}{c}\mathrm{1,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0}\\ \mathrm{0,1,0,0,0,0,0,0,0,1,0,0,0,0},\mathrm{0,0}\\ \mathrm{0,0,1,0,0,0,0,0,0,0,1,0,0,0,0},0\\ \mathrm{0,0,0,1,0,0,0,0,0,0,0,1,0,0,0,0}\\ \mathrm{0,0,0,01,0,0,0,0,0,0,0,1,0,0,0}\\ \mathrm{0,0,0,0,0,1,0,0,0,0,0,0,0,1,0,0}\\ \mathrm{0,0,0,0,0,0,1,0,0,0,0,0,0,0,1,0}\\ \mathrm{0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,1}\\ \mathrm{0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0}\\ \mathrm{0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0}\\ \mathrm{0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0}\\ \mathrm{0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0}\\ \mathrm{0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0}\\ \mathrm{0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0}\\ \mathrm{0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0}\\ \mathrm{0,0,0,0,0,0,0,0,0,0,0,0,0,0,0},1\end{array}\right)$

Can use this Metzler matrix to calculate, by formula h=(M ^HM) ^-1M ^HY obtains raised cosine filter RCF (Impulse response), and therefrom detects maximum and obtain synchronizing information.

Down-sampling RCF (Impulse response) obtains other impulse response of chip-level (Impulse Response) then, the method of down-sampling is: obtain synchronizing information by detecting maximum, adopt one (by the relation decision of spreading rate and sampling rate) forward or backward every four values or eight values then, obtain channel estimation results.

Fig. 2 has shown an example of RCF (impulse response) being carried out down-sampling.The point of arrow indication is the point of down-sampling among the figure, and the result is resulting channel impulse response.Fine rule among the figure is represented the real part that is worth, and thick line is represented imaginary part.The filter here is 8 samplings for each chip, so per 8 are adopted one.The length of channel impulse response vector is by various parameter decisions in the system.

Fig. 3 and Fig. 4 are respectively RCF (Impulse Response) result who uses traditional synchronization detecting method and synchronization detecting method of the present invention to obtain, send signal wherein for 8 users, the characteristic of channel of giving each user is according to standard: 3GPP TR125.945 case 1,4 users' signal has the gain (detecting first user's signal) of 0db, other 4 users' signal has the gain of 4db, adds the noise of 5db.From Fig. 3 as seen, use the error of traditional resulting raised cosine filter of synchronization detecting method bigger, carry out synchronous detecting, then be easy to generate big error if therefrom detect maximum.

As seen from Figure 4, the raised cosine filter RCF (ImpulseResponse) that uses method of the present invention to obtain has very little error, therefrom detects maximum and carries out synchronous detecting, then is not easy very much to make mistakes.

Fig. 6 has shown the schematic construction of the receiver of having implemented synchronization detecting method of the present invention.As shown in Figure 6, receiver comprises amplifier 10, one-level frequency converter 20, coherent demodulator 30, A/D converter 40, and digital baseband part 50.Carrying out slot synchronization in digital baseband part 50 detects and channel estimating.As mentioned above, in the digital baseband part according to receiver of the present invention, carry out the LS algorithm on the sampling rank, thereby obtain the very little raised cosine filter of error, can carrying out accurately on this basis, slot synchronization detects and channel estimating.

According to another aspect of the present invention, also provide a kind of mobile communication base station and terminal, wherein comprised according to receiver of the present invention.Like this, can eliminate the interference that cross correlation between the training sequence and autocorrelation cause effectively according to mobile communication base station of the present invention and terminal.

More than the present invention is described in detail, but those skilled in the art will appreciate that under the situation that does not break away from essence of the present invention, can carry out various suitable modifications.

Claims (9)

1. the slot synchronization detection method of using in the mobile communication receiver may further comprise the steps:

On the sampling rank, utilize lms algorithm to calculate raised cosine filter;

In the raised cosine filter that calculates, detect maximum point, thereby carry out synchronous detecting,

Wherein, utilizing lms algorithm to calculate in the process of raised cosine filter, the training sequence matrix conversion of chip-level is become the training sequence matrix of sample stage.

2. method according to claim 1, wherein each element with chip-level training sequence matrix changes into 8 * 8 diagonal angle submatrix.

3. according to any one described method among the claim 1-2, further comprise:

On the basis of detected synchronizing information, the raised cosine filter that calculates is carried out down-sampling, thereby obtain impulse response.

4. the receiver in the mobile communcations system, it has:

On the sampling rank, utilize lms algorithm to calculate the device of raised cosine filter;

Based on detected synchronizing information, in the raised cosine filter that calculates, detect maximum point, thereby carry out the device of synchronous detecting,

Wherein, the device that utilizes lms algorithm to calculate raised cosine filter becomes the training sequence matrix conversion of chip-level in the training sequence matrix of sample stage.

5. receiver according to claim 4 further comprises:

Based on detected synchronizing information, the raised cosine filter that calculates is carried out down-sampling, thereby obtain the device of impulse response.

6. a communication terminal is characterized in that having receiver, and this receiver has:

On the sampling rank, utilize lms algorithm to calculate the device of raised cosine filter;

Based on detected synchronizing information, in the raised cosine filter that calculates, detect maximum point, thereby carry out the device of synchronous detecting,

Wherein, the device that utilizes lms algorithm to calculate raised cosine filter becomes the training sequence matrix conversion of chip-level in the training sequence matrix of sample stage.

7. communication terminal according to claim 6, wherein said receiver further comprises:

Based on detected synchronizing information, the raised cosine filter that calculates is carried out down-sampling, thereby obtain the device of impulse response.

8. a mobile communication base station is characterized in that having receiver, and this receiver has:

On the sampling rank, utilize lms algorithm to calculate the device of raised cosine filter;

Based on detected synchronizing information, in the raised cosine filter that calculates, detect maximum point, thereby carry out the device of synchronous detecting,

Wherein, the device that utilizes lms algorithm to calculate raised cosine filter becomes the training sequence matrix conversion of chip-level in the training sequence matrix of sample stage.

9. communication terminal according to claim 8, wherein said receiver further comprises:

Based on detected synchronizing information, the raised cosine filter that calculates is carried out down-sampling, thereby obtain the device of impulse response.

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