JP2001044904A - Frame synchronizing device and method for establishing frame synchronization - Google Patents

Abstract

PROBLEM TO BE SOLVED: To apply a device and method under a propagation situation in which the same channel interference in digital radio communication cannot be ignored. SOLUTION: This device consists of a receiving means 30 which receives a receiving wave including a frame synchronizing signal with a plurality of antennas 111 to 11k down converts the receiving wave and outputs the receiving wave as a received baseband signal, a synthesizing means 50 which estimathes an arrival direction of an incoming wave from the received baseband signal, weights and synthesuzes the received baseband signal so as to separate and extract only the signal in the direction of each arrival angle estimate and outputs a synthetic signal in each arrival angle estimate, and a correlation detecting means 51 which calculates correlation between the synthetic signal of each arrival angle estimate and the frame synchronizing signal and extracts frame timing on the basis of these correlation signals.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a frame synchronization apparatus and a frame synchronization establishment method, and more particularly, to a frame synchronization apparatus and a frame synchronization establishment method applicable in a propagation condition where co-channel interference in digital radio communication cannot be ignored. It is about.

[0002]

2. Description of the Related Art In demodulation operation in digital mobile communication, it is important to establish frame synchronization first, and in particular, it is essential in burst transmission such as TDMA (Time Division Multiple Access). FIG. 1 shows a configuration of a conventional frame synchronization device. As shown in FIG. 2, the transmission signal is transmitted in a frame configuration in which a frame synchronization signal 31 having a time width T _FS is followed by a data signal 32 having a time width T _D. First, the antenna 11
Are amplified by the low-noise amplifier 12 and then branched by the hybrid 13.

[0003] One of the signals branched by the hybrid 13, after being multiplied by the carrier signal when the carrier signal generator 18 outputs a multiplier 14 _1, the low-pass filter 15
Entered into ₁ . Then, the signal is sampled by the A / D converter 16 ₁ every sampling period T _S and converted into a digital signal. The other signal branched by the hybrid 13 is multiplied by a multiplier 14 ₂ by a carrier signal whose phase is rotated by 90 degrees by a phase shifter 17, and the low-pass filter 15
After being input to the _2, it is sampled by the A / D converter 16 ₂ and converted into a digital signal.

[0004] This operation is down-converted from the RF frequency band of the received signal to baseband, the output of the A / D converter 16 ₁ and the A / D converter 16 ₂ in-phase component of the quasi-synchronized detection signal And a quadrature component, and the two are combined to form a received baseband signal. Hereinafter, all baseband signals will be represented by complex numbers with the in-phase component as the real part and the quadrature component as the imaginary part.

Here, the low noise amplifier 12, the hybrid 13, the multiplier 14 ₁ , the multiplier 14 ₂ , and the phase shifter 1
7, low-pass filter 15 ₁ , low-pass filter 1
5 _2, A / D converter 16 _1, A / D converter 16 ₂ constitutes a baseband receive signal generator 10. Correlator 19
Represents the received baseband signal and the frame signal memory 20
Is obtained and output.
This correlation value is a complex number, and the absolute value square operation circuit 21
Calculates the absolute value square of this correlation value and calculates the maximum value detector 22
Output to The maximum value detector 22 obtains the timing at which the absolute value square of the correlation value becomes maximum in the frame signal section T _F (= T _FS + T _D ), and outputs this to the output terminal as the frame timing. The reason why the timing at which the absolute value square of the correlation value becomes the maximum is set as the frame timing will be described later.

FIG. 3 shows a configuration example of the correlator 19 shown in FIG.
This configuration is equivalent to a transversal filter. Each of the complex multipliers 42 _{1 to} 42 _{N ′} includes a reception baseband signal input from an input terminal CI and delay elements 43 ₁ to 43 _{N ′ of a} delay time T _S. A received baseband signal delayed by _-1 is set and multiplied by the complex conjugate of the frame synchronization signal input from input terminal FI.

Here, N ′ is an integer. When the code length of the frame synchronization signal is N and the symbol period of the modulation is T,
N ′ = N (T / T _S ). The complex adder 41 adds the multiplication results of the complex multipliers 42 _{1 to} 42 _{N ′} and outputs the result to the output terminal CO as a correlation value. As the above-mentioned frame synchronization signal, a code sequence having a sharp autocorrelation, that is, a code sequence having a sharp peak when the correlation with itself has a time difference of zero is used.
There is a PN sequence as such a code sequence, and its autocorrelation is shown in FIG. In this figure, T _S = T.

Therefore, if a code having sharp autocorrelation is used as the frame synchronization signal, the correlation peaks when the timings on the transmitting side and the receiving side match. When _two direct waves and _two delayed waves with delay times τ ₁ and τ ₂ arrive on the multipath channel, an example of the square of the absolute value of the correlation value is shown in FIG. In FIG. 5, at time t ₁ , the frame synchronization signal of the direct wave matches the timing on the receiving side, and at this time, the absolute value square of the correlation value reaches a peak. This value is proportional to the power of the direct wave. The same applies to times t ₂ = t ₁ + τ ₁ and t ₃ = t ₂ + τ _{2. At} these times, the frame synchronization signal of the delay wave of delay time τ ₁ and τ ₂ matches the timing of the receiving side, and the correlation value The absolute value squared becomes the peak. These values are also proportional to the power of each delayed wave. Therefore, if the timing at which the absolute value square of the correlation value becomes the maximum is found, the frame timing corresponding to the path having the maximum power among the multipaths can be extracted.

Next, FIG. 6 shows a configuration in which the frame synchronizer of FIG. 1 is extended to diversity reception. First, the received signal from each antenna 11 ₁ to 11 _K, the baseband signal generator 10 ₁ to 10 _K respectively, converts the received signal of the RF frequency band to baseband, the received baseband signal Generate. Here, antennas 11 _{1 to} 11
_K , the baseband signal generators 10 ₁ to 10 _K , and the carrier signal generator 18 correspond to the receiving unit 30. Next, the received baseband signals from the antennas 11 _{1 to} 11 _K are input to the correlators 19 _{1 to} 19 _K , and the correlation with the frame synchronization signal is output. Then, the absolute value square calculators 21 _{1 to} 21 _K calculate and output the absolute value square of the correlation. These values are added by the adder 23 and input to the maximum value detector 22.

The maximum value detector 22 determines a timing at which the sum of the absolute values of the correlation values becomes maximum in the frame signal section, and outputs this as a frame timing. With this configuration, the peak value of the square of the absolute value of the correlation value can be amplified by the diversity, and the accuracy of frame synchronization can be improved. However, in the conventional frame synchronizer shown in FIGS. 1 and 6, when co-channel interference cannot be ignored, the interference wave power can be reduced to 1 / N by the interference suppression by the correlation operation. When the power becomes about N times the power of the desired wave, there is a disadvantage that the characteristics are significantly deteriorated.

[0011]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a frame synchronization apparatus and a frame synchronization establishment method which can be applied under the propagation conditions where co-channel interference in digital wireless communication cannot be ignored.

[0012]

According to a first aspect of the present invention, in a frame synchronization apparatus, a reception wave including a frame synchronization signal is received by a plurality of antennas, down-converted, and output as a reception baseband signal. Receiving means for estimating the direction of arrival of an incoming wave from the received baseband signal, and weighting and combining the received baseband signal so as to separate and extract only the signal in the direction of each angle of arrival estimation; A synthesizing unit that outputs a synthesized signal for each value, and a correlation detecting unit that obtains a correlation between the synthesized signal and the frame synchronization signal for each of the arrival angle estimation values, and extracts a frame timing based on these correlation signals. It is characterized by having.

According to the first aspect of the present invention, receiving means for receiving a received wave including a frame synchronization signal by a plurality of antennas, down-converting the down-converted signal and outputting it as a received baseband signal, and arriving from the received baseband signal Estimating the direction of arrival of, and weighting and combining the received baseband signals so as to separate and extract only the signal in the direction of each angle of arrival estimation,
A synthesizing unit that outputs a synthesized signal for each arrival angle estimation value, and a correlation detection unit that obtains a correlation between the synthesized signal for each arrival angle estimation value and the frame synchronization signal, and extracts a frame timing based on these correlation signals. With this arrangement, the direction of arrival of an incoming wave is estimated from a received baseband signal including a frame synchronization signal received by a plurality of antennas, and the received baseband signal is separated and extracted only in the direction of each direction of arrival angle estimation value. A frame synchronizing apparatus, which extracts a frame timing based on a correlation between the synthesized signal and the frame synchronizing signal, and provides a frame synchronizing apparatus which can be applied under a propagation condition where co-channel interference in digital wireless communication cannot be ignored. it can.

According to a second aspect of the present invention, in the frame synchronizer according to the first aspect, the weighting coefficient of the weighted combining in the combining means is based on a direction-constrained output minimizing method, and It is characterized by obtaining from. According to the second aspect of the present invention, the desired wave signal component in which the interference wave is suppressed is obtained from the synthesized signal by obtaining the weighting coefficient of the weighted synthesis from the received baseband signal based on the direction-constrained output minimization method. Obtainable.

Further, since frame synchronization is performed based on the combined signal in which interference is suppressed, it is possible to provide frame synchronization that operates well even in a propagation situation where co-channel interference cannot be ignored. The invention described in claim 3 is the first invention.
In the frame synchronization apparatus described above, a signal obtained by normalizing the power of the correlation signal for each of the angle-of-arrival estimation values with the power of the composite signal is applied to the correlation detection unit, and the correlation detection unit performs the normalization. The timing at which the signal obtained is maximized is set as the frame timing.

According to the third aspect of the present invention, the correlation detecting means extracts the frame timing based on the standardized synthesized signal, so that the interference wave signal component is relatively large. Even when the correlation signal power corresponding to the signal component becomes large, accurate frame timing can be extracted. According to a fourth aspect of the present invention, there is provided a frame synchronizing device comprising the synthesizing means according to the second aspect and the correlation detecting means according to the third aspect.

According to a fourth aspect of the present invention, the frame synchronizer is provided with the synthesizing means according to the second aspect and the correlation detecting means according to the third aspect. According to a fifth aspect of the present invention, in the method for establishing frame synchronization in digital mobile communication, a direction of arrival of an incoming wave is estimated from a received baseband signal including a frame synchronization signal received by a plurality of antennas, and each arrival angle estimation value is obtained. And weighting and synthesizing the received baseband signal so as to separate and extract only the signal in the direction of (i), and extracting the frame timing based on the correlation between the synthesized signal and the frame synchronization signal.

According to the fifth aspect of the present invention, the direction of arrival of an incoming wave is estimated from a received baseband signal including a frame synchronization signal received by a plurality of antennas, and only the signal in the direction of each estimated angle of arrival is separated. By extracting and synthesizing the weight of the received baseband signal and extracting the frame timing based on the correlation between the synthesized signal and the frame synchronization signal, it can be applied under the propagation conditions where co-channel interference in digital wireless communication cannot be ignored. A method for establishing frame synchronization can be provided.

[0019]

Next, an embodiment of the present invention will be described.
This will be described with reference to the drawings. FIG. 7 shows the configuration of the embodiment of the present invention.
Show. First, K (K is an integer of 2 or more) antennas 1
1₁~ 11_KFrom the baseband signal generation
Vessel 10₁-10 _KDown-convert to baseband
And output as a received baseband signal. This base
Sband signal generator 10₁-10_KIs shown in FIG.
The antenna 11₁~ 11
_K, Baseband signal generator 10 ₁-10_K, And
The rear signal generator 18 corresponds to the receiving means 30.

The combining means 50 outputs from the receiving means 30
Receive baseband signal to terminal CI₁~ CI_KInput from
And the direction of arrival of the arriving wave from the received baseband signal
presume. Separate and extract only signals in the direction of each angle of arrival estimation
Weighting and combining the received baseband signals so that
A composite signal for each arrival angle estimation value is output. Here,
Since the number of angle-of-arrival estimation values is 3, three synthesized signals are
A₁~ A _ThreeOutput to The correlation detecting means 51
Calculates the correlation with the frame sync signal
To extract frame timing based on this correlation signal.
Output to the input terminal.

FIG. 8 shows the structure of the synthesizing means 50 described above.
First, from the terminal CI ₁ ~CI _K, the received base band signal of each antenna is input. The angle-of-arrival estimation / weighting coefficient control circuit 55 estimates the angle of arrival of the arriving wave based on these received baseband signals. As this estimation algorithm, (i) MUSIC (Multiple Signal Classifica
Option) Subspace-Based method such as algorithm or (ii)
Beamforming methods such as direction-constrained output minimization methods are known, but the Subspace-Based method involves eigenexpansion of matrices, so the amount of calculation becomes enormous, and the beamforming method that requires a relatively small amount of calculation is used. Is desirable. In the following, a description will be given of the DOA estimation using the direction-constrained output minimization method.

First, variables are defined as preparation. Here, i is an integer indicating time iT, and the received baseband signals input from terminals CI _{1 to} CI _K are x ₁ (i) to x _K (i). Received baseband signals _{x 1 (i) ~x K (} i) was subjected to weighted synthesized weighting coefficients w ^* ₁ ~w ^* _K, to generate a composite signal y (i). When this synthesized signal y (i) is represented using a K-dimensional reception baseband signal vector X (i) and a K-dimensional weighting coefficient vector W defined by the following equation, y (i) = W ^H X (i) (1) W ^H = [w ^* ₁ w ^* ₂ ... w ^* _K ] (2) ^XH (i) = [x ^* ₁ (i) x ^* ₂ (i) ... x ^* _K (i)] (3) ). Where ^* is the complex conjugate and ^H is the complex conjugate transpose.

The direction-constrained output minimization method operates such that, assuming that the arrival angle of a desired wave is φ, only the arrival wave coming from φ is extracted. More specifically, the weighting coefficient is estimated so as to minimize the average power of the combined signal while keeping the average power of the incoming wave at the arrival angle φ constant. When the weighting coefficient is estimated in this manner, the arriving waves at other angles of arrival are suppressed,
In a situation where the noise signal power can be ignored, the average power of the combined signal is proportional to the average power of the arriving wave at the angle of arrival φ.

Next, a constraint condition for keeping the average power of the arriving wave at the arrival angle φ constant will be described with reference to FIG. In this drawing, it is assumed that the shape of the antenna is a linear array in which the antennas are arranged on a line at an interval d, and a plane wave having an arrival angle φ is arriving. Here, the interval d needs to be λ / 2 (λ: wavelength of radio wave) or less in order to appropriately control the directivity of the array antenna. The arriving wave of the antenna 2 has a φ path difference of dcos with respect to the arriving wave of the antenna 1, and has a phase delay of 2πcosφ / λ with respect to the arriving wave of the antenna 2. Similarly, the arriving wave of the k-th (1 ≦ k ≦ K) antenna is 2π (k−
1) There is a phase delay of dcos φ / λ. Considering this phase delay and equation (1), the constraint condition for keeping the average power of the arriving wave at the angle of arrival φ constant is: W ^H A (φ) = 1 (const) (4) A ^H (φ) = [a _{^{* 1 (φ) a * 2}} (φ) ··· a * K (φ)] (5) a K (φ) = exp [-j2π (k-1) dcos φ / λ], 1 ≦ k ≦ K (6) Here, A (φ) is a vector called a steering vector, and j is an imaginary unit.

From the equation (1), the average power P (W) of the composite signal y (i) is given by P (W) = W ^H RW (7) Here, R is an autocorrelation matrix of the K-dimensional received baseband signal vector X (i), and R = <X (i) X ^H (i)> (8) Note that <> represents an ensemble average. W that minimizes equation (7) under the constraint condition of equation (4) is expressed as W
When _OPT, W _OPT is ^{_{W OPT = [A H (φ}} ) R -1 A (φ)] -1 R -1 A (φ) (9) and is known to become (RTJr.Compton Author " Adap
tive antennas "Chapter 6, Prentice Hall Publishing, 19
1988).

By substituting equation (9) into equation (7), P _m (φ) = P (W _OPT ) = [A ^H (φ) R ⁻¹ A (φ)] ⁻¹ (10) Since P _m (φ) = P (W _OPT ) is proportional to the average power of the arriving wave at the angle of arrival φ in a situation where the noise signal power can be ignored, P _m (φ) with respect to the angle of arrival φ is plotted. By finding the peak, the angle of arrival of the actual arriving wave can be estimated, and the peak value is substantially proportional to the average power of the arriving wave.

In order to actually obtain R, the ensemble average in equation (8) may be replaced with a time average. FIG.
The angle-of-arrival estimation / weighting coefficient control circuit 55 calculates the angle-of-arrival estimation value based on the direction-constrained output minimization method as described above, and separates and extracts only the signal in the direction of each angle-of-arrival estimation value, In (9), the weighting coefficient is obtained by substituting the arrival angle estimation value for φ and output.

It is also possible to apply the Subspace-Based method such as the MUSIC algorithm to the angle of arrival estimation.
Also in this case, the weighting coefficient may be obtained by substituting the arrival angle estimation value into φ in Expression (9). In addition, when the correlated arriving waves arrive at different angles of arrival, it is not possible to accurately estimate the angle of arrival as it is, so that the moving average (TJShan, M. Wax, and
T.Kailath, “On Spatial Smoothing for Direction-o
f-Arrival Estimation of Coherent Signals ”, IE
EE.Trans.Acoustics, Speech, and Signal Processing,
Vol. ASSP-33, No4, pp.805-811, August 1985)
It is necessary to apply the technique.

In FIG. 8, the number of arrival angle estimation values is 3, and 3
One weighting coefficient vector is obtained. First angle of arrival
For the estimate, the first element of the weighting coefficient vector
Complex conjugate w^* ₁₁Is a complex multiplier 52₁₁To the k-th element in order
Complex conjugate w^* _K1Is a complex multiplier 52_K1Is set to Duplicate
Prime multiplier 52₁₁~ Complex multiplier 52_K1Of the output of
Calculator 53₁, The complex adder 53₁Output
The signal is a synthesized signal corresponding to the first arrival angle estimation value.
Terminal A₁Output to Similarly, the second angle of arrival estimation
For the value, the complex of the first element of the weighting coefficient vector
Conjugate w^* ₁₂Is a complex multiplier 52₁₂To the k-th element
Element conjugate w^* _K2Is a complex multiplier 52_K2Is set to
The first element of the weighting coefficient vector
Complex conjugate w^* ₁₃Is a complex multiplier 52₁₃Then, in order, the K-th point
Prime complex conjugate w^* _K3Is a complex multiplier 52_K3Is set to
Therefore, the complex adder 53_TwoAnd complex adder 53_ThreeOutput
A combined signal whose signals correspond to the second and third angle of arrival estimates;
Terminal A_TwoAnd terminal A_ThreeOutput to Moving path
Then, in many cases, the arrival angles of the desired wave and the interference wave are different
Then, at least one of the above synthesized signals has an interference wave
It becomes the suppressed desired signal component.

Next, FIG. 10 shows the configuration of the correlation detecting means 51 of FIG. Combined signal for each arrival angle estimated value from the terminal A ₁ to A ₃ is input, the correlation between the frame synchronizing signal is obtained at each correlator 19 ₁ to 19 _3. The absolute value square calculators 21 _{1 to} 21 ₃ calculate and output the absolute value square of the correlation signal, that is, the power. Here, the correlators 19 _{1 to} 19 ₃ and the absolute value square calculators 21 _{1 to} 21 ₃ are the same as those in FIG.

There are two types of synthesized signals: a desired signal component and an interference signal component. When the interference signal power is relatively large, the correlation signal power corresponding to the interference signal component is larger. Sometimes. Therefore, the power of the composite signal is obtained from each composite signal by the root mean square calculators 63 _{1 to} 63 ₃ , and the correlation signal power is normalized, that is, division is performed. The maximum value detector receives the standardized correlation signal power as input, and outputs the maximum value timing to the output terminal as frame timing. What can take the maximum value corresponds to the desired wave signal component among the three normalized correlation signal powers, and the timing at which the time series becomes maximum in the frame signal section _TF is the frame timing.

As described above, since signals can be separated and extracted for each direction of arrival of an incoming wave, when the arrival angles of the desired wave and the interference wave are different, a composite signal in which the interference wave is suppressed can be obtained. Since the frame timing is extracted based on the correlation between the synthesized signal and the frame synchronization signal, the apparatus operates well even in a propagation situation where co-channel interference cannot be ignored. FIG.
FIG. 1 shows the frame synchronization accuracy of the present invention and the prior art by computer simulation.

The horizontal axis represents the average E _b / N _o , the vertical axis represents the average value of the extracted frame timings, and the true frame timing is 0. The modulation method was QPSK, the frame synchronization signal was 31 symbols, and the subsequent data signal was 256 symbols. There is one interfering station, and the propagation path is 2-path Rayleigh fading with a delay time difference of 1T. The number of antennas K is 6
The desired station and the interfering station were asynchronous. From the figure, the average E _b / N _o is 25dB or more, precisely frame synchronization is found to be performed in propagation conditions where co-channel interference can not be ignored.

Although the present invention relates to frame synchronization, if a synthesized signal from which frame timing is extracted is input to a detector such as an equalizer, it can be easily extended to a signal decision unit. it can. Since the present invention is configured as described above, the prior art differs from the prior art in that weighting and combining are performed so that a received baseband signal is separated for each direction of arrival of an incoming wave, and a correlation between the combined signal and a frame synchronization signal is obtained. The difference is that the timing is extracted.

Next, a flow of a method for establishing frame synchronization in digital mobile communication according to the present invention will be described with reference to FIGS. First, the synthesizing unit 50 estimates the direction of arrival of an incoming wave from a received baseband signal including a frame synchronization signal received by a plurality of antennas by the receiving unit 30 (S10), and extracts only the signal in the direction of each estimated angle of arrival. The received baseband signals are weighted and combined so as to be separated and extracted (S11), and then the correlation detecting means 51 extracts a frame timing based on the correlation between the combined signal and the frame synchronization signal (S12).

As described above, according to the present invention, a signal is separated and extracted for each angle of arrival of an incoming wave. Therefore, when the arrival angle of a desired wave and an interference wave are different, a combined signal in which the interference wave is suppressed is obtained. be able to. Further, since the frame timing is extracted based on the correlation between the synthesized signal and the frame synchronization signal, the frame synchronization can be accurately performed even in a propagation situation where co-channel interference cannot be ignored.

In the above embodiment, the frame synchronizer has been described in terms of a circuit, but the same function as that of the circuit can be handled by software. Therefore,
Performing a part or all of the configuration described in the embodiment by software is also included in the technical contents of the present invention. Further, the present invention is effective when used in a wireless system that performs high-speed transmission because co-channel interference cannot be ignored.

[0038]

According to the present invention as described above, the following various effects can be obtained. According to the first aspect of the present invention, receiving means for receiving a received wave including a frame synchronization signal with a plurality of antennas, down-converting the converted signal and outputting the converted signal as a received baseband signal, and an arrival direction of the incoming wave from the received baseband signal Combining means for weighting and combining the received baseband signals so as to separate and extract only the signal in the direction of each angle of arrival estimation, and outputting a synthesized signal for each angle of arrival estimation; And a correlation detection means for extracting a frame timing based on these correlation signals, so that a reception baseband signal including a frame synchronization signal received by a plurality of antennas is obtained. The direction of arrival of the arriving wave is estimated from the received signal, and the received baseband signal is weighted and synthesized so as to separate and extract only the signal in the direction of each angle of arrival estimation. Extracts frame timing based on the correlation between the composite signal and the frame synchronizing signal, it is possible to provide the applicable frame synchronizer under propagation conditions co-channel interference can not be ignored like in digital wireless communications.

According to the second aspect of the present invention, the desired wave in which the interference wave is suppressed from the synthesized signal is obtained by determining the weighting coefficient of the weighted synthesis from the received baseband signal based on the direction-constrained output minimization method. A signal component can be obtained. Also, since frame synchronization is performed based on the combined signal in which interference has been suppressed, it is possible to provide frame synchronization that operates well even in a propagation situation where co-channel interference cannot be ignored.

According to the third aspect of the present invention, the correlation detecting means extracts the frame timing based on the standardized synthesized signal, so that the interference wave signal component is relatively large. Even when the correlation signal power corresponding to the signal component becomes large, accurate frame timing can be extracted. According to the invention described in claim 5, the direction of arrival of an incoming wave is estimated from a received baseband signal including a frame synchronization signal received by a plurality of antennas,
By weighting and combining the received baseband signals so as to separate and extract only the signal in the direction of each angle of arrival estimation, and extracting the frame timing based on the correlation between the synthesized signal and the frame synchronization signal, the same channel in digital wireless communication It is possible to provide a method of establishing frame synchronization that can be applied under a propagation condition where interference cannot be ignored.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining a configuration example of a conventional frame device.

FIG. 2 is a diagram for explaining a frame configuration example of a transmission signal.

FIG. 3 is a diagram illustrating a configuration example of a correlator.

FIG. 4 is a diagram for explaining autocorrelation of a PN sequence.

FIG. 5 is a diagram for explaining the absolute value square of the correlator output in the multipath propagation path.

FIG. 6 is a diagram illustrating a configuration example of conventional frame synchronization extended to diversity reception.

FIG. 7 is a diagram illustrating an example.

FIG. 8 is a diagram for describing a configuration example of a synthesizing unit.

FIG. 9 is a diagram for explaining a relationship between a linear ray and a plane wave.

FIG. 10 is a diagram for describing a configuration example of a correlation detection unit.

FIG. 11 is a diagram for explaining frame synchronization characteristics according to the present invention and the prior art.

FIG. 12 is a flowchart of a frame synchronization establishing method.

[Explanation of symbols]

 Reference Signs List 10 baseband signal generator 11 antenna 12 low noise amplifier 13 hybrid 14 multiplier 15 low pass filter 16 A / D converter 17 phase shifter 18 carrier signal generator 19 correlator 20 frame signal memory 21 absolute value square calculator 22 Maximum value detector 23 Adder 41, 53 Complex adder 42, 52 Complex multiplier 43 Delay element 50 Synthesizing means 51 Correlation detecting means 55 Arrival angle estimation / weighting coefficient control circuit 63 Root mean square calculator 64 Division circuit 65 Maximum Value detector

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04L 7/08 H04B 7/26 DF term (Reference) 5J021 AA05 AA06 DB01 FA00 FA05 FA09 FA13 FA14 FA16 FA18 FA20 FA23 FA24 FA26 FA30 FA32 FA34 HA05 HA06 5K028 AA04 BB04 CC02 HH03 MM17 NN01 NN08 5K047 AA13 BB01 CC06 GG34 HH01 HH15 HH43 5K059 CC03 CC04 DD35 EE02 5K067 AA03 AA26 BB02 CC04 CC24 DD47 EE02

Claims (5)

[Claims] A receiving unit that receives a reception wave including a frame synchronization signal with a plurality of antennas, down-converts the reception wave, and outputs the down-converted signal as a reception baseband signal, and estimates an arrival direction of the arrival wave from the reception baseband signal; Combining means for weighting and combining the received baseband signals so as to separate and extract only signals in the direction of each angle of arrival estimation, and outputting a combined signal for each of the angle of arrival estimations; A frame synchronization apparatus comprising: a correlation detection unit that obtains a correlation between the synthesized signal and the frame synchronization signal and extracts a frame timing based on the correlation signal. 2. A frame synchronization apparatus according to claim 1, wherein a weighting coefficient of said weighting synthesis in said synthesis means is obtained from said received baseband signal based on a direction-constrained output minimization method. 3. A signal obtained by normalizing the power of the correlation signal for each of the estimated angle of arrival values with the power of the composite signal is applied to the correlation detection means. 2. The frame synchronizer according to claim 1, wherein the timing at which the signal becomes maximum is the frame timing. 4. A frame synchronizing device comprising the synthesizing means according to claim 2 and the correlation detecting means according to claim 3. 5. A method for establishing frame synchronization in digital mobile communication, comprising: estimating a direction of arrival of an incoming wave from a received baseband signal including a frame synchronization signal received by a plurality of antennas; A method for establishing frame synchronization, comprising: weighting and combining the received baseband signal so as to separate and extract the frame timing; and extracting a frame timing based on a correlation between the combined signal and the frame synchronization signal.