JP3462435B2 - Oscillator control circuit and oscillator control method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oscillator control circuit and an oscillator control method for performing automatic frequency control of a temperature-compensated oscillator mounted in a communication terminal device in a wireless communication system.

[0002]

2. Description of the Related Art In recent years, wireless communication systems such as mobile phones and car phones have rapidly become widespread. In a communication terminal device of this wireless communication system, a temperature-compensated oscillator (Temperature Controlled Cryst) is used as an oscillator that generates reference timings for various processes such as synchronization establishment and transmission / reception switching.
al Oscillator; hereinafter referred to as "TCXO") is often used. Then, in the communication terminal device, in order to compensate the transmission timing of the TCXO, the automatic frequency control (Auto
matic Frequency Control; hereinafter referred to as "AFC")
It is carried out.

A conventional oscillator control circuit for performing AFC on TCXO will be described below with reference to FIG. FIG. 7 is a block diagram showing the internal configuration of a conventional oscillator control circuit.

In FIG. 7, the correction signal generating section 1 has a TC
A correction signal for correcting the timing of the TCXO is generated based on the information on the phase difference between the timing signal output from the XO and the detected reception signal.

The loopback coefficient generator 2 generates a preset loopback coefficient. The multiplier 3 multiplies the correction signal output from the correction signal generation unit 1 by the loopback coefficient output from the loopback coefficient generation unit 2.

The adder 4 subtracts the output signal of the multiplier 3 from the output signal of the latch 5 and outputs a TCXO control signal. The latch 5 temporarily stores the TCXO control signal output from the adder 4, and outputs the stored previous control signal to the adder 4 at the control timing of the next TCXO.

As described above, the conventional oscillator control circuit has T
By generating a correction signal based on the phase difference between the timing signal output from the CXO and the detected reception signal, and correcting the previous control signal with the correction signal, the TCXO
AFC is being conducted.

[0008]

However, since the conventional oscillator control circuit continues to control the TCXO even when the decoding result of the received signal is incorrect, it is necessary to perform highly reliable automatic frequency control. There is a problem that you can not.

The present invention has been made in view of the above points, and an object thereof is to provide an oscillator control circuit and an oscillator control method capable of performing highly reliable automatic frequency control.

[0010]

Oscillator control circuit of the present invention According to an aspect of the correction signal generating means for generating a correction signal based on the phase difference between the output signal of the reception signal and the oscillator, the correction signal generator
Coefficient multiplication for multiplying the correction signal output from the means by a coefficient
Means and the coefficient multiplying means based on the input information.
A coefficient control means for Gosuru, the the control signal of the previous oscillator
Control signal generating means for adding a correction signal multiplied by a coefficient to generate a control signal for an oscillator, and initialization means for initializing the control signal based on the input information and for setting the correction signal to 0 Take.

With this configuration, the control of the oscillator can be restarted from the beginning when the input data is inappropriate, so that the oscillator control can be prevented from being performed based on the incorrect data, and the reliability of the AFC can be improved. Can be improved and AFC converges according to the reliability of the input data.
The speed can be adaptively controlled.

In the oscillator control circuit of the present invention, when the initialization means inputs a signal indicating a synchronization error, the control signal is initialized and the correction signal is set to 0.

With this configuration, the control of the oscillator can be restarted from the beginning when there is a synchronization error, so that the oscillator control can be prevented from being performed based on erroneous data and the reliability of the AFC can be improved. Can be increased.

In the oscillator control circuit of the present invention, when the initialization means inputs a signal indicating a synchronization error and the correlation power between the spreading code estimated in the initial synchronization processing and the received signal is smaller than the threshold value, the control is performed. The signal is initialized and the correction signal is set to 0.

With this configuration, in the case of a synchronization error, it is possible to determine whether or not to restart the oscillator control from the beginning by referring to the correlation power in the initial synchronization processing, so that the reliability of the AFC is further improved. Can be increased.

In the oscillator control circuit of the present invention, the initialization means inputs the signal indicating the synchronization error, and initializes the control signal when the correlation power between the spread code of the communication channel and the received signal is smaller than the threshold value. And the correction signal is set to 0.

With this configuration, in the case of a synchronization error, it is possible to determine whether or not to restart the oscillator control by referring to the correlation power after detection, so that the reliability of the AFC is further enhanced. be able to.

[0018]

[0019]

In the oscillator control circuit of the present invention, the coefficient control means controls the coefficient multiplication means such that the coefficient increases as the correlation power between the spread code estimated in the initial synchronization processing and the received signal increases. take.

With this configuration, the loopback coefficient can be controlled based on the correlation power in the initial synchronization processing, so that the AFC convergence speed can be controlled according to the reliability.

In the oscillator control circuit of the present invention, the coefficient controlling means controls the coefficient multiplying means so that the coefficient increases as the correlation power between the spread code of the communication channel and the received signal increases.

With this configuration, the loopback coefficient can be controlled based on the correlation power after detection.
The convergence speed of FC can be controlled according to reliability.

The communication terminal device of the present invention has a configuration in which the oscillator is controlled by any of the oscillator control circuits described above.

With this configuration, since AFC with high reliability can be performed, radio communication with good reception quality can be performed.

In the oscillator control method of the present invention, the correction signal generated based on the phase difference between the received signal and the output signal of the oscillator is multiplied by the coefficient, and the correction signal multiplied by the coefficient is used as the control signal of the previous oscillator. When the control signal of the oscillator is added and the signal indicating the synchronization error is input, the control signal is initialized and the correction signal is set to 0.

With this method, the control of the oscillator can be restarted from the beginning in the case of a synchronization error, so that the oscillator control can be prevented from being performed based on erroneous data and the reliability of the AFC can be improved. Can be increased.

In the oscillator control method of the present invention, the correction signal generated based on the phase difference between the received signal and the output signal of the oscillator is multiplied by the coefficient, and the correction signal multiplied by the coefficient is used as the control signal of the previous oscillator. Generate a control signal for the oscillator by adding it, input a signal indicating a synchronization error, and initialize the control signal if the correlation power between the spreading code and the received signal estimated in the initial synchronization processing is smaller than a threshold value. The method of setting the correction signal to 0 is adopted.

According to this method, in the case of a synchronization error, it is possible to determine whether or not to restart the control of the oscillator from the beginning by referring to the correlation power in the initial synchronization processing, so that the reliability of the AFC can be further improved. Can be increased.

In the oscillator control method of the present invention, the correction signal generated based on the phase difference between the received signal and the output signal of the oscillator is multiplied by the coefficient, and the correction signal multiplied by the coefficient is used as the control signal of the previous oscillator. When the control signal of the oscillator is added and the signal indicating the synchronization error is input, and the correlation power between the spread code of the communication channel and the received signal is smaller than the threshold value, the control signal is initialized and the correction is performed. The method of setting the signal to 0 is adopted.

According to this method, in the case of synchronization error, it is possible to determine whether or not to restart the oscillator control from the beginning by referring to the correlation power after detection, so that the reliability of AFC is further enhanced. be able to.

The oscillator control method of the present invention employs a method in which the larger the correlation power between the spread code estimated in the initial synchronization process and the received signal, the larger the coefficient by which the correction signal is multiplied.

With this method, the loopback coefficient can be controlled based on the correlation power in the initial synchronization processing, so that the AFC convergence speed can be controlled according to the reliability.

The oscillator control method of the present invention employs a method in which the larger the correlation power between the spread code of the communication channel and the received signal, the larger the coefficient by which the correction signal is multiplied.

With this method, the loopback coefficient can be controlled on the basis of the correlation power after detection.
The convergence speed of FC can be controlled according to reliability.

[0036]

BEST MODE FOR CARRYING OUT THE INVENTION The essence of the present invention is to return the TCXO control signal to the initial value, set the correction signal to 0, and restart the control of the TCXO from the beginning when the decoding result of the received signal is incorrect. .

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In the following description, the case of being installed in a communication terminal device for performing CDMA (code division multiple access) wireless communication will be described as an example. In the CDMA system, a wideband signal secondarily modulated by a spreading code is wirelessly transmitted on the transmitting side, and a narrowband signal is obtained on the receiving side by multiplying the received signal by the same spreading code as on the transmitting side. is there.

(First Embodiment) The first embodiment is a CRC.
(Cyclic Redundancy Check) Based on the results, TCX
This is a form of deciding whether to continue control over O or start over.

FIG. 1 is a block diagram showing the configuration of the main part of a communication terminal device equipped with an oscillator control circuit according to this embodiment.

In FIG. 1, the code detector 101 detects a long code by which the received signal is multiplied. The synchronization unit 102 creates a delay profile and instructs the code generation unit 103 on the timing of generating the spreading code. The code generation unit 103 generates the spread code detected by the code detection unit 101 at the timing instructed by the synchronization unit 102.

Despreading sections 104 and 105 multiply the spread received signal by the spreading code output from code generating section 103. The detection units 106 and 107 are the despreading unit 1
Detection processing is performed from the output signals of 04 and 105. Synthesis part 1
08 combines the output signals of the detection units 106 and 107 at the same timing.

Decoding section 109 decodes the output signal of combining section 108 and outputs reception channel decoded data.
In addition, the decoding unit 109 performs CRC after decoding to obtain C
The RC result is output to the oscillator control circuit 111.

The phase difference detector 110 detects the phase difference between the received signal and the timing signal output from the TCXO 112, based on the output signal of the despreader 104.

The oscillator control circuit 111 includes the phase difference detector 1
A to the TCXO 112 based on the output signal of 10
Perform FC. Further, if the CRC result of the decoding unit 109 is erroneous (NG), the oscillator control circuit 111 outputs T
The control signal output to the CXO 112 is returned to the initial value.

The TCXO 112 is an oscillator control circuit 111.
A timing signal is output to each unit such as the phase difference detection unit 110 based on the control signal output from the.

Next, the configuration of the oscillator control circuit 111 according to the present embodiment will be described. FIG. 2 is a block diagram showing the internal configuration of the oscillator control circuit 111 according to the present embodiment.

In FIG. 2, the correction signal generator 201 is
A correction signal for correcting the timing of the TCXO 112 is generated based on the phase difference information output from the phase difference detection unit 110. The loopback coefficient generator 202 generates a preset loopback coefficient.

The multiplier 203 adds the correction signal output from the correction signal generation unit 201 to the loopback coefficient generation unit 202.
Multiply the loopback coefficient output from.

The reset control unit 204 includes a decoding unit 10
When a signal indicating that the CRC result is incorrect is input from 9, the moving contact of the switch 206 is connected to the multiplier 20.
3 to the zero data generation unit 205, switch 20
The moving contact 9 is switched from the adder 207 to the initial value generation unit 208.

The zero data generator 205 outputs "0" data as a correction signal. The switch 206 outputs either the correction signal output from the multiplier 203 or the zero data generation unit 205 under the control of the reset control unit 204.

The adder 207 subtracts the output signal of the switch 206 from the output signal of the latch 210 and outputs the TCXO control signal.

The initial value generation unit 208 uses a preset TC
Generate an initial value for the XO control signal. The switch 209 is
Under the control of the reset controller 204, either the TCXO control signal output from the adder 207 or the initial value generator 208 is output.

The latch 210 temporarily stores the TCXO control signal output from the switch 209, and the next TCXO control signal is stored.
The stored previous control signal is output to the adder 207 at the control timing of O112.

Next, the signal processing of the oscillator control circuit 111 according to this embodiment will be described. In the following description, L is an update cycle and j is a natural number.

The correction signal D (jL) generated by the correction signal generation unit 201 based on the phase difference information is multiplied by the loopback coefficient k in the multiplier 203.

Normally, the switch 206 is connected to the multiplier 203, and the switch 209 is connected to the adder 207. Therefore, the correction signal kD (j
L) passes through the switch 206, is input to the adder 207, and is added to the previous TCXO control signal C ((j-1) L) stored in the latch 210 to update the updated T.
The CXO control signal C (jL) is generated. The generated TCX
The O control signal C (jL) passes through the switch 209 and TC
It is output to the XO 112.

That is, the TCXO control signal C (jL) output from the oscillator control circuit 111 according to this embodiment is
It is represented by the following formula (1).

C (jL) = C ((j-1) L) -kD (jL) (1) Here, the CRC result in the decoding unit 109 is erroneous, and the signal indicating the information is that the reset control unit 204
Output to the switch 206, the switch 206 is connected to the zero data generation unit 205 and the switch 209 is connected to the initial value generation unit 208 under the control of the reset control unit 204.

In this case, the preset initial value is TC
The XO control signal C (jL) passes through the switch 209 and is output to the TCXO 112. That is, the control value is initialized and the control of the TCXO 112 is restarted from the beginning.

As described above, when the CRC result is erroneous, the TCXO control is restarted from the beginning, whereby it is possible to prevent the TCXO from being controlled based on erroneous data, and the reliability of the AFC is improved. Can be increased.

In the present embodiment, CDMA is used as the multiple access method, but the present invention is not limited to this, and similar effects can be obtained by using other multiple access methods such as TDMA. Obtainable.

(Second Embodiment) Asynchronous CDM between base stations
In the wireless communication system A, it is necessary for the communication terminal device to identify the long code of the base station that is a communication partner and establish synchronization with the base station when the power is turned on. Usually, a long code mask method is adopted in which a long code is multiplied by a short code, a part of the long code is masked, and a long code group identification short code is multiplexed on this part.
In this case, the communication terminal device identifies the long code of the base station in three stages as the initial synchronization process.

The second embodiment is a mode in which it is determined whether to control the TCXO continuously or to start over from the beginning, based on the CRC result and the correlation power in the initial synchronization processing.

The signal processing in the code detection unit of the communication terminal device equipped with the oscillator control circuit according to this embodiment will be described below.

FIG. 3 is a block diagram showing the internal structure of the code detection unit 301 of the communication terminal device equipped with the oscillator control circuit according to the present embodiment.

First, as a first step, a correlator 302 such as a matched filter correlates the received signal with the short code output from the SC generator 303. Then, the power converter 304 converts the correlation output into electric power,
The maximum value detection unit 305 detects the maximum value of the correlation power,
The SC timing generator 306 detects the mask symbol timing, which is the timing at which the maximum value of the correlation power is detected.

Next, as a second step, first, at the mask symbol timing detected in the first step, the long code group identification short code is sequentially output from the LGC generator, and the received signal is received by the correlator 308. Is correlated with. Then, the power conversion unit 309 converts the correlation output into power, the maximum value detection unit 310 detects the maximum value of the correlation power, and the LC timing generation unit 311 detects the maximum value of the correlation power. From this, a long code group including the long code of the base station is detected.

Next, in the third step, first, at the mask symbol timing detected in the first step, the replica code generator 312 outputs the long codes included in the long code group detected in the first step. Are sequentially output, and the correlator 313 correlates with the received signal.
Then, the power conversion unit 314 converts the correlation output into power, and the threshold determination unit 315 identifies a code whose correlation power exceeds a preset threshold value as a long code of the base station.

Then, the code data indicating the identified long code is output to the code generator 103, and the phase data indicating the frame timing is output to the synchronizing section 102.

Here, in this embodiment, the correlation power is A
As a parameter showing the reliability of FC, Fig. 4
As shown in, the threshold value determination unit 315 outputs the correlation power value to the reset control unit 402 and the loopback control unit 403 of the oscillator control unit 401.

FIG. 4 is a block diagram showing the internal structure of the oscillator control circuit 401 according to the present embodiment. In the oscillator control circuit 401 shown in FIG. 4, the same components as those of the oscillator control circuit 111 shown in FIG. 2 are designated by the same reference numerals and the description thereof will be omitted. Further, the configuration other than the code detection unit and the oscillator control circuit of the communication terminal device equipped with the oscillator control circuit according to the present embodiment is the same as that of the communication terminal device shown in FIG. Omit it.

In FIG. 4, the reset control unit 402 is
The CRC result is input from the decoding unit 109, and the correlation power is input from the threshold value determination unit 315. Then, even when the reset control unit 402 inputs a signal indicating that the CRC result is erroneous, if the correlation power is sufficiently large, the reliability of AFC is high, and therefore the switch 206 and the switch 209 have the same reliability. On the other hand, switching control is not performed.

Since the loopback coefficient control section 403 has high AFC reliability when the correlation power is sufficiently large,
The loopback coefficient generator 404 is controlled to increase the loopback coefficient.

As described above, when the CRC result is incorrect, the correlation power in the initial synchronization processing is referred to and the TC
By determining whether to control the XO from the beginning again, the reliability of the AFC can be further enhanced. Further, by controlling the loopback coefficient based on the correlation power in the initial synchronization processing, the AFC convergence speed can be controlled according to the reliability.

In the present embodiment, the correlation power in the initial synchronization processing can be used only for determining whether to restart the TCXO control from the beginning or for controlling the loopback coefficient.

(Embodiment 3) The received electric field strength changes due to the movement of the communication terminal device or the change of the propagation condition of the radio wave. In a CDMA communication terminal device, a delay profile is usually created and the radio wave reception intensity is constantly monitored.

The third embodiment is a mode in which it is determined whether to control the TCXO continuously or to start over from the beginning, based on the CRC result and the correlation power after detection.

FIG. 5 is a block diagram showing the configuration of the main part of a communication terminal device equipped with the oscillator control circuit according to the present embodiment. In addition, in the communication terminal device of FIG. 5, the same components as those of the communication terminal device of FIG. 1 are designated by the same reference numerals and description thereof will be omitted.

The synchronization section 501 creates a delay profile, monitors the correlation power of the output signals of the detection section 106 and the detection section 107, and inputs the output signal with the larger correlation power to the phase difference detection section 110. Then, the switch 502 is controlled to be switched. Further, the synchronization unit 501 outputs the correlation power to the oscillator control circuit 503.

FIG. 6 is a block diagram showing the internal structure of the oscillator control circuit 503 according to the present embodiment. In the oscillator control circuit 503 of FIG. 6, components common to those of the oscillator control circuit 401 of FIG. 4 will be assigned the same reference numerals as those in FIG. 4 and description thereof will be omitted.

In FIG. 6, the reset controller 601 is
The CRC result is input from the decoding unit 109, and the synchronization unit 50
Input the correlation power from 1. Then, the reset control unit 6
In 01, even when the signal indicating the information that the CRC result is erroneous is input, if the correlation power is sufficiently large,
Since the reliability of AFC is high, switching control is not performed on the switch 206 and the switch 209.

The loopback coefficient control unit 602 has high AFC reliability when the correlation power is sufficiently large.
The loopback coefficient generator 603 is controlled so as to increase the loopback coefficient.

As described above, when the CRC result is erroneous, the correlation power after detection is referred to determine whether or not the control of the TCXO is restarted from the beginning, thereby further improving the reliability of the AFC. be able to. Also, by controlling the loopback coefficient based on the correlation power after detection, the convergence speed of AFC can be controlled according to reliability.

In the present embodiment, the correlation power after detection can be used only for determining whether to restart the TCXO control from the beginning or for controlling the loopback coefficient.

Further, in each of the above-described embodiments, the description has been made assuming that the reception sequence for performing the despreading process and the detection process is two sequences, but the present invention is not limited to this, and the reception sequence is three or more sequences. However, the same effect can be obtained.

[0087]

As described above, according to the oscillator control circuit and the oscillator control method of the present invention, the TCXO control signal is returned to the initial value and the correction signal is set to 0 when the input data such as the CRC result is inappropriate. Then, the control of the TCXO is restarted from the beginning, so that the reliability of the AFC can be improved. Further, the convergence speed of the AFC can be adaptively controlled according to the reliability of the input data.

[Brief description of drawings]

FIG. 1 is a block diagram showing a main configuration of a communication terminal device equipped with an oscillator control circuit according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing an internal configuration of an oscillator control circuit according to the above embodiment.

FIG. 3 is a block diagram showing an internal configuration of a code detection unit of a communication terminal device equipped with an oscillator control circuit according to a second embodiment of the present invention.

FIG. 4 is a block diagram showing an internal configuration of an oscillator control circuit according to the above embodiment.

FIG. 5 is a block diagram showing a main configuration of a communication terminal device equipped with an oscillator control circuit according to a third embodiment of the present invention.

FIG. 6 is a block diagram showing an internal configuration of an oscillator control circuit according to the above embodiment.

FIG. 7 is a block diagram showing an internal configuration of a conventional oscillator control circuit.

[Explanation of symbols]

109 decoding section 110 Phase difference detector 111, 401, 503 oscillator control circuit 112 TCXO 201 correction signal generation unit 202, 404, 603 Loopback coefficient generator 204, 402, 601 Reset control unit 301 code detector 315 Threshold determination unit 403, 602 Loopback coefficient control unit 501 synchronization unit

─────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-58-186245 (JP, A) JP-A-10-134523 (JP, A) JP-A-9-284178 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) H04L 7/033 H03L 7/08 H04B 1/707 H04J 3/06 H04L 7/00

Claims (12)

(57) [Claims] 1. A correction signal generating means for generating a correction signal based on a phase difference between a received signal and an output signal of an oscillator, and a coefficient multiplying means for multiplying the correction signal output from the correction signal generating means by a coefficient. A coefficient control means for controlling the coefficient multiplication means based on the inputted information; a control signal generation means for adding a correction signal obtained by multiplying the previous control signal of the oscillator by the coefficient to generate an oscillator control signal; An oscillator control circuit comprising: an initialization unit that initializes the control signal based on the information and sets the correction signal to 0. 2. The oscillator control circuit according to claim 1, wherein the initialization means initializes the control signal and sets the correction signal to 0 when a signal indicating a synchronization error is input. 3. The initialization means inputs a signal indicating a synchronization error and initializes the control signal to correct when the correlation power between the spread code estimated by the initial synchronization processing and the received signal is smaller than a threshold value. The oscillator control circuit according to claim 1, wherein the signal is set to zero. 4. The initialization means inputs a signal indicating a synchronization error, and initializes the control signal and sets the correction signal to 0 when the correlation power between the spread code of the communication channel and the received signal is smaller than the threshold value. The oscillator control circuit according to claim 1, wherein: 5. The coefficient control means, the larger the correlation power between the spread code estimated in the initial synchronization processing and the received signal,
The oscillator control circuit according to any one of claims 1 to 4, wherein the coefficient multiplication means is controlled so as to increase the coefficient. 6. The coefficient controlling means controls the coefficient multiplying means such that the coefficient increases as the correlation power between the spread code of the communication channel and the received signal increases. The oscillator control circuit according to any one of 1. 7. A communication terminal device, wherein an oscillator is controlled by the oscillator control circuit according to any one of claims 1 to 6. 8. A control of an oscillator by multiplying a correction signal generated based on a phase difference between a received signal and an output signal of the oscillator by a coefficient and adding the correction signal multiplied by the coefficient to a control signal of the previous oscillator. An oscillator control method characterized in that, when a signal is generated and a signal indicating a synchronization error is input, the control signal is initialized and the correction signal is set to zero. 9. A control of an oscillator by multiplying a correction signal generated based on a phase difference between a received signal and an output signal of the oscillator by a coefficient, and adding the correction signal multiplied by the coefficient to a control signal of the previous oscillator. When a signal is generated, a signal indicating a synchronization error is input, and the correlation power between the spreading code estimated in the initial synchronization processing and the received signal is smaller than the threshold value, the control signal is initialized and the correction signal is set to 0. Oscillator control method. 10. A control of an oscillator by multiplying a correction signal generated based on a phase difference between a received signal and an output signal of the oscillator by a coefficient, and adding the correction signal multiplied by the coefficient to a control signal of the previous oscillator. Generate a signal, input a signal indicating a synchronization error, and initialize the control signal and set the correction signal to 0 when the correlation power between the spread code of the communication channel and the received signal is smaller than a threshold value. An oscillator control method characterized by the above. 11. enough correlation power of initial synchronization spreading code estimated by the processing and the received signal is large, 請claim 8, characterized in that to increase the coefficient to be multiplied by the correction signal
11. The oscillator control method according to any one of claim 10 . 12. The oscillator control according to claim 8 , wherein the larger the correlation power between the spread code of the communication channel and the received signal, the larger the coefficient by which the correction signal is multiplied. Method.