JP3243167B2 - Synchronizer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a synchronizing apparatus for a digital radio communication apparatus, and more particularly, to independently correlating signals received from a plurality of antennas to estimate the effect of fading and to evaluate the effect of fading. The present invention relates to a synchronizer that performs synchronization pull-in by using a received signal from an antenna having a smaller number.

[0002]

2. Description of the Related Art When performing wireless communication, it is necessary to synchronize between a transmitter and a receiver. Therefore, a known pattern is inserted into the transmission sequence, a correlation is obtained on the receiving side, and synchronization is obtained by determining a time having a high correlation as a known pattern reception time.

FIG. 3 is a block diagram showing the configuration of a conventional synchronizer, and its operation will be described with reference to the frame formats shown in FIGS. In the frame format of FIG. 2, symbols for acquiring synchronization are arranged at the center, but may be at the beginning or end.

In FIG. 3, the synchronizer comprises a fading estimator 301, a correlator A 302, a correlator B 304 and a synchronization determination circuit 306.

FIG. 5 is a block diagram showing a detailed configuration of the fading estimator 301.

In FIG. 5, the fading estimator includes a memory E501, a correlator E502, a correlator F503, a memory F504, and a complex calculator 505.

The fading estimation constructed as described above
The operation of the device will be described. The memory E of FIG.
And the memory F have a synchronization word of the desired wave and the interference wave, respectively.
(Here, M symbols), sw1₁, Sw1_Two,
…, Sw1_M, Sw2₁, Sw2 _Two , ..., sw2_MIs saved
Is done. sw1_x, Sw2_xAre the x symbol
A set of in-phase and quadrature components of the synchronization word of the desired wave and interference wave
Here, it is expressed as a complex number.

FIG. 7 shows a detailed configuration of the correlator E shown in FIG. In FIG. 5, a correlator E includes a shift register 701.
, A complex multiplier 702, and an adder 704.

The correlator E in FIG. 5 has a shift register in which the quadrature component and the in-phase component of the A / D-converted received wave are stored for a synchronization word length. At time T, the shift register stores N pieces of received data from time T−N + 1 to T, r
_{T-N + 1} , r _{T-N + 2} ,..., R _T are stored. r _T is a set of an in-phase component and a quadrature component of the received signal at time T, and is represented here as a complex number. The correlator E of FIG. 5 outputs a correlation value rs1 between the synchronization word of the desired wave (the contents of the memory E of FIG. 5) and the received wave. The complex multiplier 702 and the adder 704 in FIG. 7 respectively perform multiplication and addition based on the following arithmetic expressions.

[Formula 1]

X bar represents a complex conjugate of X, and | X |
Represents the size of rs1 indicates how similar the waveform of the synchronization word of the desired wave of M symbols is to the waveform of the received signal. The more similar the waveforms are, the closer to 1 becomes, and it becomes 1 when they completely match. Conversely, if the waveforms are not similar, the closer they are, the closer to zero. By performing the correlation with the received waveform, if the time has a high correlation value, it can be determined that the synchronization word has been received.

The detailed configuration of the correlator F in FIG. 5 is the same as that of the correlator E, and is as shown in FIG. The correlator F in FIG. 5 has a shift register in which the quadrature component and the in-phase component of the A / D-converted received wave are stored for a synchronization word length. N received data in the shift register from the time T-N + 1 to T at time _{T, r T-N + 1} , r T-N + 2, ..., r T is stored. r _T is a set of an in-phase component and a quadrature component of the received signal at time T, and is represented here as a complex number.
The correlator F of FIG. 5 outputs a correlation value rs2 between the synchronization word of the interference wave (the contents of the memory F of FIG. 5) and the received wave.

[Formula 2]

The complex calculator 505 shown in FIG.
From the outputs rs1 and rs2 of the correlator F, the fading of the desired wave and the fading of the interference wave, X and Y, which are obtained as follows, are output.

[Equation 3]

FIG. 8 shows the configuration of the correlator A in the synchronizer shown in FIG. 8, a correlator A includes a shift register 801, a complex multiplier 802, a memory A803, and a memory B8.
04, an adder 805, and a complex multiplier 806.

.., Sw1 ₂ ,..., Sw1 _M , sw2 ₁ , sw1 ₁ , sw1 ₂ ,...
sw2 ₂ ,..., sw2 _M are stored. sw1 _x , sw2 _x
Are the set of the in-phase component and the quadrature component of the synchronization word of the desired wave of the x-th symbol and the set of the in-phase component and the quadrature component of the synchronization word of the interference wave, respectively, and are expressed here as complex numbers. Correlator A in the synchronizer shown in FIG. 3 has a shift register in which the quadrature component and the in-phase component of the A / D-converted received wave are stored for a synchronization word length. At time T, the shift register stores N pieces of received data from time T−N + 1 to T, r
_{T-N + 1} , r _{T-N + 2} ,..., R _T are stored. r _T is a set of an in-phase component and a quadrature component of the received signal at time T, and is represented here as a complex number. The correlator A in the synchronizer shown in FIG. 3 is a synchronization word for the desired wave (contents of the memory B in FIG. 8)
And a correlation value s1 obtained by removing the estimated interference wave from the received wave. Specifically, based on each value of the shift register, the fading of the interference wave × the synchronization word of the interference wave (FIG. 8)
The contents of the memory A of the desired wave are subtracted, and the result obtained by dividing by the fading term of the desired wave is correlated with the synchronization word of the desired wave.

(Equation 4)

X bar represents the complex conjugate of X, and | X |
Represents the size of s1 indicates how similar the waveform of the synchronization word of the desired signal for M symbols is to the waveform of the received signal. The more similar the waveforms are, the closer to 1 the value becomes, and the value becomes 1 when they completely match. Conversely, if the waveforms are not similar, the closer they are, the closer to zero. By performing the correlation with the received waveform, if the time has a high correlation value, it can be determined that the synchronization word has been received.

FIG. 9 shows the configuration of the correlator B in the synchronizer shown in FIG. In FIG. 9, a correlator B includes a shift register 901, a complex multiplier 902, a memory A903, and a memory B9.
04, an adder 905, and a complex multiplier 906.

The memory B and the memory A in FIG. 9 have the same configuration as the memory B and the memory A in FIG. 8, but the memory B and the memory A in FIG. Will be saved. The correlator B in the synchronizer of FIG. 3 has a shift register in which the quadrature component and the in-phase component of the A / D-converted received wave are stored for a synchronization word length.
At time T, the shift register stores N pieces of received data from time T−N + 1 to T, r _{T−N + 1} , r _{T−N + 2} ,.
_T is saved. r _T is a set of an in-phase component and a quadrature component of the received signal at time T, and is represented here as a complex number. The correlator B in the synchronizer shown in FIG. 3 outputs a synchronization word (contents of the memory B in FIG. 9) of the interference wave and a correlation value s2 obtained by removing the desired wave estimated from the received wave.
Specifically, the fading of the desired wave × the synchronizing word of the desired wave from the values of the shift register (contents of the memory A in FIG. 9)
Then, the value obtained by dividing by the fading term of the interference wave is correlated with the synchronization word of the interference wave.

(Equation 5)

The synchronization determination circuit 306 in the synchronization device shown in FIG.
Then, based on the inputs from the correlators A and B, it is determined whether or not it is the synchronization word reception time. For example, a time when a high correlation value is quickly obtained from both the correlator A and the correlator B is determined as the synchronization word reception time.

FIG. 6 shows the configuration of the synchronization determination circuit 306 in the synchronizer of FIG. 6 includes an OR circuit 601, an address counter 602, a latch circuit 603,
And a comparator 604.

The outputs of the correlator A and the correlator B are given as inputs 1 and 2 to the input of the OR circuit 601 respectively. The latch circuit 603 stores the value of the address counter 602 when the output of the OR circuit 601 becomes 1 for the first time. The address counter 602 changes at each sampling clock timing and is reset at a predetermined cycle. The comparator 604 has an address counter 602 indicating the current time.
Is compared with the output stored in the latch circuit 603, and 1 is output if they match, and 0 is output if they do not match.

[0021]

In the case of the conventional configuration as described above, there is a problem that the influence of fading is large and the synchronization pull-in time characteristic deteriorates when the input level is low.

[0022]

In order to solve the above-mentioned problem, the present invention provides a plurality of antennas (two in the embodiment).
Are prepared, independently perform correlation processing on received signals obtained from a plurality of antennas, independently estimate a desired wave and an interference wave for the received signals obtained from a plurality of antennas, and by an influence of fading, Select the one that does not have lower power. This makes it possible to perform synchronization pull-in accurately and at high speed.

[0023]

FIG. 1 is a functional block diagram showing an embodiment of a synchronizer according to the present invention. In FIG. 1, a synchronizer includes a correlator A101, a correlator B103, and an antenna A10.
5, a fading estimator A106, a comparator A107, a correlator C108, a correlator D110, and a fading estimator B11.
2, the antenna B113, the comparator B114, and the synchronization determination circuit 1
It is composed of 15 and.

The fading estimator A shown in FIG. 1 is similar to the conventional fading estimator shown in FIG. 5 in that the fading of the desired wave and the fading of the interference wave estimated from the received signal from the antenna A, X, Outputs Y.

(Equation 6)

Here, rsa1 and rsa2 are respectively
The correlation value between the synchronization word of the desired wave and the signal received from the antenna A and the correlation value between the synchronization word of the interference wave and the signal received from the antenna A are expressed by the following equations.

[Formula 7]

(Equation 8)

In the above formulas 6, 7 and 8, sw1 ₁ , sw1 ₂ ,..., Sw1 _M , sw2 ₁ , sw2
₂ ,..., Sw2 _M are a synchronization word of a desired wave and a synchronization word of an interference wave (here, M symbols). s
w1 _x and sw2 _x are a set of the in-phase component and the quadrature component of the synchronization word of the desired wave of the x symbol and a set of the in-phase component and the quadrature component of the synchronization word of the interference wave, respectively, and are expressed here as complex numbers. ra _T is a set of the in-phase component and the quadrature component of the signal received from the antenna A at the time T, and is represented here as a complex number. X bar represents the complex conjugate of X, and | X | represents the magnitude of X.

The correlator A in FIG. 1 has a shift register in which the quadrature component and the in-phase component of the A / D-converted received wave from the antenna A are stored by the synchronization word length. This shift register can be shared with the correlator B of FIG.
The received data from the N antennas A from time T−N + 1 to T, ra _{T−N + 1} , ra _{T−N + 2} ,
…, Ra _T is stored. The correlator A shown in FIG. 1 outputs a synchronization word sa1 (contents of the memory A) of the desired wave and a correlation value sa1 obtained by removing the estimated interference wave from the wave received from the antenna A. Specifically, the fading term of the interference wave × the synchronizing word of the interfering wave is subtracted from each value of the shift register, and the result is divided by the fading term of the desired wave, and the synchronization word of the desired wave is correlated.

(Equation 9)

Sa1 represents how similar the waveform of the synchronization word of the desired wave of M symbols is to the waveform of the signal received from the antenna A. The more similar the waveform is, the closer to 1 the waveform becomes, the more completely the waveform becomes. It becomes 1 when they match. Conversely, if the waveforms are not similar, the closer they are, the closer to zero. By performing the correlation with the received waveform, if the time has a high correlation value, it can be determined that the synchronization word has been received.

The correlator B in FIG. 1 has a shift register for storing the quadrature component and the in-phase component of the A / D-converted received wave from the antenna A by the synchronization word length. This shift register can be shared with the correlator A in FIG. At time T, the shift register stores time T−N + 1 to T
Received data from N antennas A up to r
a _{T-N + 1} , ra _{T-N + 2} ,..., ra _T are stored. r
a _T is a set of the in-phase component and the quadrature component of the signal received from the antenna A at the time T, and is represented here as a complex number.
The correlator B shown in FIG. 1 outputs a correlation value sa2 obtained by removing a desired word estimated from a received word from the antenna A and a synchronization word of the interference wave (contents of the memory B). Specifically, fading of a desired wave from each value of the shift register
The synchronization word of the interference wave is obtained by subtracting the synchronization word of the desired wave and dividing by the fading term of the interference wave.

[Formula 10]

The fading estimator B of FIG. 1 is similar to the conventional fading estimator shown in FIG. 5 in that the fading of the desired wave and the fading of the interference wave estimated from the signal received from the antenna B, W, Output Z.

[Equation 11]

Here, rsb1 and rsb2 are respectively
The correlation value between the synchronization word of the desired wave and the signal received from the antenna B and the correlation value between the synchronization word of the interference wave and the signal received from the antenna B are expressed by the following equations.

(Equation 12)

(Equation 13)

In the above formulas 11, 12 and 13, sw1 ₁ , sw1 ₂ ,..., Sw1 _M , sw2 ₁ , s
w2 _2, ..., sw2 _M is (a M symbol in this case) in which the respective desired wave synchronization word and the interference wave of the synchronization word. sw1 _x and sw2 _x are a set of the in-phase component and the quadrature component of the synchronization word of the desired wave of the x symbol and a set of the in-phase component and the quadrature component of the synchronization word of the interference wave, respectively, and are expressed here as complex numbers. rb _T is a set of the in-phase component and the quadrature component of the signal received from the antenna B at the time T, and is represented here as a complex number. X bar represents the complex conjugate of X, and | X | represents the magnitude of X.

The correlator C shown in FIG. 1 has a shift register for storing the quadrature component and the in-phase component of the A / D converted reception wave from the antenna B by the synchronization word length. This shift register can be shared with the correlator D of FIG. At time T, the shift register stores time T−N + 1 to T
RB _{T-N + 1} , RB _{T-N + 2} ,.
rb _T is preserved. rb _T is a set of the in-phase component and the quadrature component of the signal received from the antenna B at the time T, and is represented here as a complex number. The correlator C shown in FIG. 1 has a correlation value sb obtained by removing the interference wave estimated from the synchronization word of the desired wave (contents of the memory C) and the reception wave from the antenna B.
Outputs 1. Specifically, the fading term of the interference wave × the synchronizing word of the interfering wave is subtracted from each value of the shift register, and the result is divided by the fading term of the desired wave, and the synchronization word of the desired wave is correlated.

Equation 14

X bar represents a complex conjugate of X, and | X |
Represents the size of sb1 indicates how similar the waveform of the synchronization word of the desired wave of M symbols and the waveform of the signal received from the antenna B are. Becomes 1. Conversely, if the waveforms are not similar, the closer they are, the closer to zero. By the process of correlating with the received waveform, if the correlation value is high,
It can be determined that the synchronization word has been received.

The correlator D of FIG. 1 has a shift register for storing the quadrature component and the in-phase component of the A / D-converted received wave from the antenna B by the synchronization word length. This shift register can be shared with the correlator C of FIG.
At time T, the received data from the N antennas B from time T−N + 1 to T are stored in the shift register, rb
_{T-N + 1, rb T} -N + 2, ..., rb T is stored. rb _T
Is a set of the in-phase component and the quadrature component of the signal received from the antenna B at the time T, and is represented here as a complex number. FIG.
In the correlator D, the synchronization word of the interference wave (contents of the memory D)
And a correlation value sb2 of the signal obtained by removing the desired wave estimated from the received wave. Specifically, the fading of the desired wave × the synchronization word of the desired wave is subtracted from each value of the shift register, and the result is divided by the synchronization word of the interference wave, and the synchronization word of the interference wave is correlated.

(Equation 15)

FIG. 10 shows the configuration of the comparator A in the synchronization device shown in FIG. In FIG. 10, the comparator A includes a switch A1001 and a switch B1002.

The effect of fading X, W on switch A
Is entered. The switch A compares X and W with the complex number 1 + j0, and outputs 1 if X is closer and 0 if X is farther.

When the output of switch A is 1 (when X is closer to 1 + j0), switch B outputs the input from correlator A in FIG. Otherwise, output the input from correlator C. Specifically, the in-phase component of the fading effect X is Xi, the quadrature component Xq, and the fading effect W is
Is Wi and the quadrature component Wq is (Xi−
1) Compare ² + Xq ² with (Wi-1) ² + Wq ² and calculate (X
If i-1) ² + Xq ² is small, the input from correlator A in FIG. 1 is output; otherwise, the input from correlator C is output.

FIG. 11 shows the configuration of the comparator B in the synchronizer shown in FIG. In FIG. 11, the comparator B includes a switch C1003 and a switch D1004.

The effects of fading Y and Z are applied to the switch C.
Is entered. The switch C compares Y and Z with the complex number 1 + j0, and outputs 1 if Y is closer and 0 if far.

When the output of switch C is 1 (when Y is closer to 1 + j0), switch D outputs the input from correlator B in FIG. Otherwise, output the input from correlator D. Specifically, when the in-phase component of the fading effect Y is Yi, the quadrature component is Yq, the in-phase component of the fading effect Z is Zi, and the quadrature component is Zq, (Y
i-1) ² + Yq ² and (Zi-1) ² + Zq ² ,
If (Yi-1) ² + Yq ² is small, the input from correlator B in FIG. 1 is output, otherwise, the input from correlator D is output.

As described above, the synchronizer of the present invention uses the comparators A and B so that the antenna input which is less affected by fading can be selected separately for the desired wave and the interference wave. Thus, synchronization can be accurately and quickly performed.

The configuration of the synchronization determination circuit 115 in FIG. 1 conforms to the conventional configuration shown in FIG. That is, the output of the correlator A, the correlator C, the correlator B, or the correlator D output from either the comparator A or the comparator B is determined as the synchronization word reception time.

[0044]

As is apparent from the embodiments described above, the synchronizer of the present invention has a plurality of antennas, and independently receives a desired signal and an interference wave with respect to received signals obtained from the plurality of antennas. Is estimated, and the power that is not affected by fading and whose power is not reduced is selected, thereby enabling accurate and high-speed synchronization pull-in.
In other words, instead of simple combining diversity or switching diversity, spatial diversity that is selected using the fading estimation result is applied, so that accuracy and synchronization pull-in time characteristics can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram of a synchronization device according to the present invention;

FIG. 2 shows a frame format of a transmission signal used in the present invention;

FIG. 3 is a block diagram of a conventional synchronous device;

FIG. 4 is an output waveform of a correlator having a conventional configuration used in the present invention;

FIG. 5 is a block diagram of a conventional fading estimator used in the present invention;

FIG. 6 is a block diagram of a conventional synchronization determination circuit used in the present invention;

FIG. 7 is a block diagram of a correlator used in the fading estimator of FIG. 5;

FIG. 8 is a block diagram of the correlator used in FIG. 3 and the first and second correlators of the present invention;

FIG. 9 is a block diagram of a correlator used in the third and fourth correlators of the present invention;

FIG. 10 is a block diagram of a first comparator used in the synchronization device of the present invention;

FIG. 11 is a block diagram of a second comparator used in the synchronizer of the present invention.

[Explanation of symbols]

 101, 302 correlator A 103, 304 correlator B 105 fading estimator A 106 antenna A 107 comparator A 108 correlator C 110 correlator D 112 fading estimator B 113 antenna B 114 comparator B 115, 306 synchronization determination circuit 301 Fading estimator 501 Memory E 502 Correlator E 503 Correlator F 504 Memory F 505 Complex calculator 601 Logical OR circuit 602 Address counter 603 Latch circuit 604 Comparator 701,801,901 Shift register 702,802,806,902, 906 Complex multipliers 704, 805, 905 Adders 803, 903 Memory A 804, 904 Memory B 1001 Switch A 1002 Switch B 1003 Switch C 1004 Switch D

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-8-172423 (JP, A) JP-A-9-55727 (JP, A) JP-A-9-200281 (JP, A) JP-A-5-200281 75507 (JP, A) JP-A-8-46532 (JP, A) JP-A-56-8931 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H04L 7/08 H04B 1 / 10 H04B 7/08

Claims (1)

(57) [Claims] 1. A synchronizing apparatus for inserting a known pattern into a transmission sequence, correlating at a receiving side, and determining a time having a high correlation as a known pattern reception time to perform synchronization pull-in. Estimation in the vicinity of the synchronization word from the reception signal of one antenna using the synchronization word of the desired wave and the synchronization word of the interference wave
A first fading estimator that outputs the fading of the desired wave and the interference wave, a first correlator that calculates a correlation value between a received wave from the first antenna and a synchronization word of the desired wave, A second correlator for calculating a correlation value between the received wave from the antenna and the synchronization word of the interference wave, and a synchronization word near the synchronization word using the synchronization word of the desired wave and the synchronization word of the interference wave from the reception signal of the second antenna. Estimated at
A second fading estimator that outputs the fading of the desired wave and the interference wave, a third correlator that calculates a correlation value between a received wave from the second antenna and a synchronization word of the desired wave, A fourth correlator for calculating a correlation value between a received wave from the antenna and a synchronization word of the interference wave; an output of the first and third correlators; a first fading estimator and a second fading estimator; Discriminating and selecting the first comparator and the output of the second and fourth correlators based on the output of the fading estimator, and discriminating the output of the first fading estimator and the output of the second fading estimator A synchronization device comprising: a second comparator for selecting the output of the first comparator; and a synchronization determination circuit for performing synchronization pull-in from an output of the first comparator and an output of the second comparator.