JPH10224267A - Spread spectrum communication equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To acquire code synchronization in a short time with high accuracy. SOLUTION: In a synchronization acquisition part 110, in addition to a result of discriminating a level of a correlation value obtained by positive phase correlation device 111 with positive phase comparator 112, a result of discriminating a level of a correlation value, obtained by an advanced phase correlation device 122 with an advanced phase comparator 117 provided to a synchronization follow-up part 210 is inputted to a phase controller 118, where a control signal representing a phase control amount is generated, based on the level discrimination result of the positive phase and the advanced phase. So that a phase of a PN code generated from a spread code generator 116 is shifted and controlled by the phase control signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
Mobile phone system, cordless phone system, wireless LA
The present invention relates to a communication device used in a wireless communication system such as an N system, and in particular, to a code division multiple access (CDMA) system using a spread spectrum communication system.
ccess) relates to a spread spectrum communication device used in a system that enables communication.

[0002]

2. Description of the Related Art In recent years, as one of communication systems used in a mobile communication system, a spread spectrum communication system requiring less power per unit frequency and more resistant to interference and interference has been attracting attention.

In a radio communication system using a spread spectrum communication system, for example, a transmitter device modulates digitized voice data or image data by a digital modulation system such as a PSK modulation system and then modulates the data. Pseudo noise code (pseudo noise code)
The signal is converted into a wideband baseband signal using a spreading code such as a random noise code (PN code), and then upconverted into a radio frequency band signal and transmitted. On the other hand, the receiving device down-converts the received radio frequency band signal to an intermediate frequency or baseband frequency signal, and then despreads using the same spreading code as that used by the transmitting device. Then, digital demodulation is performed by a digital demodulation method such as the PSK demodulation method to reproduce the received data.

By the way, in this type of system, it is necessary to establish code synchronization between the transmission-side spreading code and the reception-side spreading code prior to performing communication between the transmitting-side device and the receiving-side device. Various types of synchronization methods have been conventionally considered, but a sliding correlation method has attracted attention because of its relatively simple circuit configuration.

[0005] In the sliding correlation system, a reception-side apparatus removes unnecessary frequency components by passing a reception signal despread by a reception-side spreading code through a band-pass filter, and square-detects the signal by a square-law detector to obtain a base signal. The received signal is converted into a band signal, and the baseband received signal is integrated for a predetermined period by an integrator to detect a correlation value between the received signal and a spread code on the receiving side. Then, while monitoring the correlation value, the phase of the reception-side spread code is sequentially shifted by a predetermined chip phase, and when the correlation value becomes equal to or more than a predetermined value, the code at the phase of the reception-side spread code at that time is obtained. Synchronization is assumed to have been established, and the process proceeds to a synchronization following operation.

FIG. 7 is a circuit block diagram showing a configuration of a synchronization unit provided in a search receiver and a finger circuit of a conventional spread spectrum communication apparatus. The synchronization unit includes a synchronization acquisition unit 100 and a synchronization follow-up unit 200, and a sliding correlation operation is performed by the synchronization acquisition unit 100. That is, the received signal is input to the normal phase correlator 111, where the correlation with the spread code (positive phase) generated from the spread code generator 116 is obtained. And this positive phase correlator 1
The correlation value output from 11 is compared with the threshold value in the in-phase comparator 112. As a result, if the correlation value is equal to or greater than the threshold value, it is set to "1"; 1-bit comparison output is output.

[0007] In the phase controller 113, the positive phase comparator 1
The phase control amount corresponding to the 1-bit comparison output output from the output unit 12 is output. FIG. 8 shows an example of the correspondence between the comparison output and the phase control amount. For example, when the comparison output is "1", it is determined that the received spread code phase does not match the received signal phase, and the received spread code phase is set to 1/4 [chip] or 1/2 [chip]. A phase control amount for shifting is output. This phase controller 113
Is supplied to a voltage controlled oscillator (VCO) 115 via a changeover switch 114, whereby the reference clock frequency output from the VCO 115 is varied, and consequently the spreading code generator 116 The phase of the generated reception spread code is variably controlled.

The above-described synchronization acquisition operation is repeated until synchronization is acquired. When the comparison output becomes "0", it is determined that the received spread code phase coincides with the received signal phase. Is a value equivalent to 0 [chip]. At this time, a phase capture end signal is output from the positive phase comparator 112 to the changeover switch 114, and the changeover switch 114 is changed from the phase control 113 for synchronization acquisition to the phase control 125 for synchronization tracking by this signal. And the apparatus shifts to the synchronous tracking operation thereafter.

That is, in the synchronization follow-up section 200, the received signal is input to the phase correlator 121 and the phase correlator 122, where the delay and the phase of the spread code output from the spread code generator 116 are respectively obtained. Is obtained. Here, the phase of the spread code is 1/2 that of the normal phase.
The phase is delayed by [chip], and the advanced phase is advanced by 1/2 [chip] with respect to the normal phase. Each of the above correlators 12
The correlation values output from 1, 122 are subtracted by a subtractor 123 to generate a control signal called an S curve. The comparator 124 obtains a comparison result between the S curve and the threshold value, and outputs a phase control amount for phase tracking from the phase controller 125 for synchronization tracking based on the comparison result. For this reason, the phase of the spread code generated by the spread code generator 116 is variably controlled.

[0010]

However, when synchronization is acquired using the above-described sliding correlation method, the phase is shifted over a length corresponding to one cycle of the spreading code at the longest. In other words, when the SN ratio of the received signal is poor, a longer phase shift is required. For example, a long-period code sequence such as 2 ¹⁵ [chip] is used for the spread code. Therefore, in the method in which the phase of the received spread code is shifted by 1/4 [chip] or [1/2] [chip] as described above, the time required to acquire synchronization is extremely long, for example, several tens of seconds.

As a countermeasure, conventionally, for example, Japanese Unexamined Patent Publication No.
As shown in -58665, a contrivance has been made to add a capturing circuit to the synchronous tracking circuit so that the synchronous tracking circuit can be used for both tracking and capturing. However, in such a circuit, although the capture time can be shortened, a complicated and large circuit configuration cannot be avoided.

On the other hand, it is conceivable to shorten the time required for synchronization acquisition by setting a large phase shift width. However, when the phase shift width is increased, the correlation value does not exceed the threshold value even when the received spreading code phase approaches the synchronization point, and it is more susceptible to noise and interference on the transmission line. Causes a decrease in accuracy.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a spread spectrum communication apparatus capable of capturing at least code synchronization in a short time and with high accuracy. It is in.

[0014]

In order to achieve the above object, a first aspect of the present invention is to receive a radio signal which is spread spectrum by a transmission spread code, and convert the received signal to the same reception spread code as the transmission spread code. In a spread spectrum communication apparatus that reproduces transmission data by despreading a received signal, a first received spread code and a second received spread code having a phase shifted by a predetermined amount with respect to the first received spread code are generated. Receiving spread code generating means, first correlation means for calculating a correlation value between the received signal and the first received spreading code, and second correlation means for calculating a correlation value between the received signal and the second received spreading code. 2 correlation means and phase control means for synchronization acquisition. Then, in the phase control means for acquiring synchronization, level determination is performed for each correlation value obtained by the first and second correlation means, and the first and second receptions are performed based on the level determination results. The phase of the first and second received spread codes generated from the received spread code generation circuit is shift-controlled so that the phase of the spread code approaches the phase of the received signal.

Therefore, according to the first aspect of the present invention, not only the correlation value between the received signal and the first received spread code but also the correlation value between the received signal and the second received spread code are simultaneously used to acquire the synchronization. Control will be performed. Therefore, the phase shift width of the received spread code is increased while maintaining the step of monitoring the correlation value, as compared with the case where the synchronization acquisition control is performed using only the correlation value between the received signal and the first received spread code. Becomes possible. Therefore, the time required for synchronization acquisition can be reduced without lowering the accuracy of synchronization acquisition.

In the present invention, the following can be considered as the configuration of the reception spread code generation means and the phase control means for synchronization acquisition. In the first configuration, a positive-phase reception spreading code is generated as a first reception spreading code, and an advanced-phase reception spreading code whose phase is advanced by a predetermined amount with respect to the normal-phase reception spreading code as a second reception spreading code. A spread code is generated, and the phase of the received spread code generated by the received spread code generating means is shift-controlled based on the result of level determination of the correlation values between the received signal and the positive-phase and advanced-phase received spread codes. Is what you do.

The second configuration is such that a positive-phase reception spreading code is generated as a first reception spreading code, and a second reception spreading code is a delay having a phase delayed by a predetermined amount with respect to the positive-phase reception spreading code. The received spread code generated by the received spread code generation means is generated based on the result of level determination of the correlation value between the received signal and the positive-phase and late-phase received spread codes. The shift control is performed.

The third configuration is such that a positive-phase reception spreading code is generated as a first reception spreading code, and a second phase is advanced by a predetermined amount with respect to the positive-phase reception spreading code as a second reception spreading code. The received spread code and the delayed receive spread code whose phase is delayed by a predetermined amount are respectively generated, and the level determination is performed on each correlation value between each of the positive spread, the early spread and the late receive spread codes and the received signal. Overall, the phase of the received spread code generated by the received spread code generating means is shift-controlled.

According to the first and second configurations, the received spread code can be shifted with a maximum shift width of twice the phase difference between the positive-phase received spread code and the early-phase or late-phase received spread code. It is possible. In the case of the third configuration, it is possible to shift the reception spread code with a maximum shift width of three times,
The time required for synchronization acquisition can be further reduced.

Further, according to the present invention, in the phase control section for synchronizing acquisition, a phase for synchronizing a phase of a leading spread code or a phase of a late spread code generated by a received spread code generating means with a received signal is provided. After performing the shift control, and after capturing the phase synchronization, the phase of each reception spread code generated from the reception spread code generation means is uniformly changed between the above-mentioned advance or late reception spread code and the normal phase receive spread code. Is shifted by an amount corresponding to the phase difference of (1), and the phase of the in-phase received spread code is synchronized with the received signal.

As described above, when the synchronization between the reception spread code of the early phase or the late phase and the reception signal is monitored, the synchronization between the reception spread code of the normal phase and the reception signal is monitored depending on the shift direction of the reception spread code. It is possible to acquire the synchronization earlier than in the case where the synchronization is performed, thereby making it possible to further reduce the time required for acquiring the synchronization. In addition, when the shift direction of the received spread code is reversed, synchronization can be established at the in-phase position after confirming the synchronization acquisition state at a plurality of phase positions. Can be.

On the other hand, a spread spectrum communication apparatus according to a second aspect of the present invention provides a reception spread code having a positive phase, a reception spread code having an advanced phase which is advanced by a predetermined amount with respect to the reception spread code having a normal phase, and a delay code which is delayed by a predetermined amount. A reception spread code generating circuit for generating a phase reception spread code, a positive phase correlator for obtaining a correlation value between a received signal and the positive phase reception spread code, a received signal and the advanced phase receive spread code, A fast correlator for determining the correlation value of, and a slow correlator for determining the correlation value between the received signal and the received spreading code of the above-mentioned phase, further comprising a phase control unit for synchronization acquisition,
A phase control unit for synchronous tracking.

In a state where the phase synchronization of the reception spread code with respect to the reception signal is not acquired, the synchronization acquisition phase control unit performs a level judgment on the correlation value obtained by the positive phase correlator. To obtain a first determination result, and perform a level determination on at least one of the correlation value obtained by the early phase correlator and the correlation value obtained by the late phase correlator.
And the phase of each received spread code generated from the received spread code generating circuit is shift-controlled based on the first and second level determination results. Further, after the phase acquisition is acquired by the synchronization acquisition circuit, the correlation value obtained by the early phase correlator and the correlation value obtained by the slow phase correlator by the phase controller for synchronization follow-up. Is obtained, and the phase of each received spread code generated from the received spread code generation circuit is controlled to reduce this level difference.

That is, as the early phase correlation value or the late phase correlation value used in the synchronization acquisition operation, a value obtained by an early phase correlator or a late phase correlator already provided for synchronization tracking is used. Things. Therefore,
There is no need to provide a new correlator other than the positive-phase correlator for synchronization acquisition, thereby realizing a simple and compact circuit.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) FIG. 1 is a circuit block diagram showing a first embodiment of a spread spectrum communication apparatus according to the present invention.

The transmission voice signal of the speaker output from the microphone 10a is converted into an analog-to-digital converter (A-
D) After being converted into a digital signal by 11 a, the signal is encoded by a speech encoder-decoder (speach coder-decoder, hereinafter referred to as vocoder) 12. In the microprocessor (MPU) 13, a control signal and the like are added to the encoded transmission signal output from the vocoder 12, and thereby transmission data is generated.

The transmission data is added with an error detection code and an error correction code by a data generation circuit 14, then encoded by a convolutional encoder 15, and further processed by an interleave circuit 16 for interleaving. .
Then, the transmission data output from the interleave circuit 16 is spread by a spectrum spreader 17 into a wideband signal by a PN code. After the unnecessary frequency components are removed by the digital filter 18, the spread spectrum transmission signal is converted into an analog signal by a digital-analog converter (DA) 19. Then, the analog transmission signal is up-converted to a predetermined radio channel frequency by the analog front end 20 and power-amplified to a predetermined transmission power level, and then transmitted from the antenna 21 to, for example, a mobile communication base station. .

On the other hand, the radio signal received by the antenna 21 is low-noise amplified by the analog front end 20 and down-converted to an intermediate frequency or a baseband frequency. The received signal output from the analog front end 20 is an analog signal.
After being converted into a digital signal at a predetermined sampling period by a digital converter (AD) 22, the signal is supplied to a search receiver 23, an automatic gain control (AGC) circuit 24, and three finger circuits 25, 26, and 27, respectively. Is entered.

Each of the finger circuits 25, 26, and 27 includes a spread code generator, a synchronization acquisition unit, a synchronization tracking unit, and a data demodulation unit, which will be described later. Among them, the data demodulation unit performs spectrum despreading of the received transmission signal arriving from the base station using the PN code generated from the PN code generation unit, and further integrates the signal over an one symbol period by the integration dump filter. The reason why three finger circuits are provided is that a multipath reception signal is received at a high SN ratio using a path diversity effect and that a base station of a connection destination is switched without disconnecting a radio path during communication. This is for performing soft handoff.

The search receiver 23 is for searching for the PN code of the pilot signal broadcast for each radio frequency from the base station and capturing its offset. Basically, the finger circuits 25, 26, It has the same configuration as 27. The power control data obtained by this PN code search operation is taken into the microprocessor 13.

The symbols demodulated by the finger circuits 25, 26, and 27 are input to a symbol combiner 28 together with synchronization information and are combined with each other. Then, the combined demodulated symbols are input to a deinterleave circuit 29 together with timing information, and the deinterleave circuit 29 performs a deinterleave process. Subsequently, the demodulated symbols after the deinterleaving are Viterbi-decoded in the Viterbi decoder 30, and the demodulated symbols after the Viterbi decoding are error-correction-decoded by the error correction circuit 31 to become reception data.
3 is input. In the microprocessor 13, the input received data is separated into voice data and control data. The voice data is subjected to voice decoding by the vocoder 12 and then to a digital-analog converter (DA) 1.
1b is converted to an analog signal, and then the speaker 1
0b is output.

The keypad / display 32 is
It is provided for a user to input dial data, control data, and the like, and to display various information relating to the operation state of the mobile station. The operation of the keypad display 32 is controlled by the microprocessor 13.

By the way, the search code receiver 23 and the spread code generator, the synchronization acquisition unit and the synchronization follower of each of the finger circuits 25, 26 and 27 are configured as follows. FIG.
FIG. 2 is a circuit block diagram showing the configuration. In the figure, the same parts as those in FIG. 7 are denoted by the same reference numerals.

That is, the spreading code generator comprises a spreading code generator 116 and a voltage controlled oscillator (VCO) 115 for giving a reference clock frequency to the spreading code generator 16. The spreading code generator 116 includes a positive-phase PN code having a length of 2 ¹⁵ , a PN code having a phase delayed by [[chip] with respect to the PN code having the positive phase, Leading PN with a phase advanced by 1/2 [chip] with respect to the PN code
And a sign respectively.

The synchronization follow-up unit 210 includes a slow phase correlator 121
, The phase correlator 122, the subtractor 123, and the comparator 12
4 and a phase controller 125. Slow correlator 1
At 21, the correlation value between the received signal and the delayed PN code generated by the spreading code generator 116 is obtained. In the leading phase correlator 122, the received signal and the spread code
The correlation value with the advanced PN code generated from the above is obtained.
The subtractor 123 subtracts the correlation value obtained by the early phase correlator 122 from the correlation value obtained by the late phase correlator 121 to obtain the level difference. Comparator 124
Compares this level difference with a threshold value, thereby detecting the state of the phase shift of the received spread code with respect to the received signal. The phase controller 125 outputs a phase control amount for bringing the phase shift closer to zero in accordance with the state of the detected phase shift.

The synchronization acquisition unit 110 includes a positive-phase correlator 111
, A positive phase comparator 112, a phase advance comparator 117, a phase controller 118, and a changeover switch 114. In the positive phase correlator 111, the received signal and the spread code
The correlation value with the positive-phase PN code generated from 16 is obtained. The positive-phase comparator 112 compares the correlation value obtained by the positive-phase correlator 111 with a threshold value. When the correlation value is equal to or greater than the threshold value, it becomes “1”. A 1-bit comparison signal which becomes "0" is output. Similarly, the phase advance comparator 117 compares the correlation value output from the phase advance correlator 122 of the synchronization tracking section 210 with a threshold value, and when the correlation value is equal to or greater than the threshold value, it becomes “1”. If the value is less than the threshold value, a 1-bit comparison signal which becomes "0" is output.

The phase controller 118 is connected to the in-phase comparator 11
2 and outputs a phase control amount for shifting the phase of the PN code generated from the reception spread code generator 116 in accordance with the comparison signal output from the phase comparator 117 and the comparison signal output from the phase comparator 117. I do. The changeover switch 114 switches to the phase controller 118 during the synchronization acquisition operation, and outputs the phase control amount output from the phase controller 118 to the VCO 1.
15 Further, when the spread code synchronization is captured and the comparison signal of “1” level is output from the positive phase comparator 112, the phase controller 125 switches to the phase controller 125 side, and thereafter the phase control amount output from the phase controller 118 is changed. It is supplied to the VCO 115.

Next, the spread code synchronizing operation of the apparatus configured as described above will be described. First, in an initial state where spread code synchronization is not established, such as immediately after power-on, etc.,
The changeover switch 114 has been switched to the phase controller 118 for synchronization acquisition. When a received signal is input in this state, a correlation value between the received signal and the positive-phase PN code is obtained by the positive-phase correlator 111, and the correlation value is calculated by the positive-phase comparator 112.
It is determined whether or not is greater than or equal to the threshold. At the same time, the phase comparator 117 determines whether or not the correlation value between the reception signal obtained by the phase correlator 122 and the phase PN code is equal to or larger than the threshold value. And both comparators 1
On the basis of the level determination results of the steps 12 and 117, the phase controller 11
In FIG. 8, a control signal indicating the amount of phase control is output according to the information shown in FIG. 3, whereby the phase of the PN code generated by the spreading code generator 116 is controlled.

For example, if the determination results of both comparators 112 and 117 are both "0", it is determined that the phase of the received PN code with respect to the received signal is completely different, and the phase controller 118 generates a spread code. A control signal for shifting the phase of the PN code generated by the device 116 by one chip is output. Therefore, the phase of the received PN code is 1 [chi
p] is shifted. Thereafter, as long as the comparison results of the comparators 112 and 117 are both "0", the above-described synchronization acquisition operation is repeated. In other words, when no synchronization is acquired, the received PN code is shifted at a relatively large interval of 1 [chip].

During the above-described synchronization acquisition operation, the positive-phase comparator 1
12 remains “0”, but the phase comparator 1
It is assumed that the comparison result of No. 17 is “1”. Then, the phase controller 118 determines that the phase of the advanced PN code matches the received signal, and the phase controller 118 changes the phase of the PN code generated by the spreading code generator 116 to 1/2 [c
A hip] shift control signal is output. Therefore, the phase of the received PN code is shifted by [[chip].
That is, the phase of the positive-phase PN code with respect to the received signal is 1 /
When the distance approaches 2 [chip], the shift of the received PN code becomes 1 /
It is changed to a narrow interval of 2 [chip].

When the comparison output of the positive phase comparator 112 becomes "1", the phase controller 118 determines that the phase of the positive phase PN code matches the received signal, and the spread code generator 116 generates. The phase of the PN code is fixed. Thus, the operation of acquiring the reception PN code for the reception signal ends.

When the synchronization acquisition operation is completed, the changeover switch 114 is switched from the synchronization acquisition phase controller 118 to the synchronization tracking phase controller 125 by the comparison result "1" output from the positive phase comparator 112. Side, and thereafter, shifts to the synchronization following operation by the synchronization following section 210.

That is, in the synchronization follow-up section 210, the correlation value between the received signal and the delayed PN code and the correlation value between the received signal and the advanced PN code are obtained in the slow correlator 121 and the early correlator 122, respectively. , And the subtractor 123 subtracts these correlation values from each other to generate a control signal called an S curve. This control signal is output from the comparator 1
At 24, a level is determined by comparing with a plurality of threshold values, and based on the determination result, a phase control signal for tracking the phase of the received PN code with respect to the received signal is output from the phase control unit 125. Spread code generator 1 by control signal
The phase of the PN code generated from 16 is modified.

It is assumed that the correlation value of the positive-phase correlator 111 has become smaller than the threshold value during the synchronous tracking operation due to, for example, the occurrence of interference or a decrease in the reception level. Then, the comparison result of the positive phase comparator 112 becomes “0”, whereby the changeover switch 114 switches from the phase controller 125 for synchronization tracking to the phase controller 118 for synchronization acquisition. A synchronization acquisition operation is performed.

As described above, in the first embodiment,
In the synchronization acquisition section 110, the correlation value obtained by the positive phase correlator 111 is obtained by the leading phase correlator 122 provided in the synchronization tracking section 210 in addition to the result of the level determination by the positive phase comparator 112. The result of the level determination of the correlation value by the comparator 117 is input to the phase controller 118, and the phase controller 118 generates a control signal indicating the amount of phase control based on each of the positive-phase and advanced-phase level determination results. The phase control signal shift-controls the phase of the PN code generated from the spreading code generator 116.

That is, an acquisition operation of PN code synchronization for the received signal is performed using both the positive correlation value between the received signal and the positive PN code and the fast correlation value between the received signal and the advanced PN code. Like that.

Therefore, the monitoring step width of the correlation value is set to 1
It is possible to increase the phase shift width of the received PN code to 1 [chip] while keeping the equivalent of / 2 [chip], thereby shortening the time required for synchronization acquisition without lowering the accuracy of synchronization acquisition. It becomes possible. This means that the required time for synchronization acquisition can be reduced to ず without deteriorating the acquisition accuracy as compared with the conventional method in which the phase shift width is １ ／ [chip], and the effect is extremely large. Further, in the present embodiment, since the correlation value of the early phase correlator 122 already provided in the synchronization follow-up unit 210 is used as it is for synchronization acquisition, it is not necessary to provide a new correlator. Can be easily miniaturized.

(Second Embodiment) FIG. 4 is a circuit block diagram showing a second embodiment of the synchronization section of the spread spectrum communication apparatus according to the present invention. 2, the same parts as those in FIG. 2 are denoted by the same reference numerals, and detailed description is omitted.

The synchronization acquisition unit 120 includes the spreading code generator 1
The delay units 131 and 13 correspond to the positive-phase PN code, the late-phase PN code, and the early-phase PN code generated from
2, 133 and changeover switches 134, 135, 136 are provided. Each of the delay units 131, 132, and 133 respectively has the positive phase PN generated by the spreading code generator 116.
The phase of the code, the delayed PN code, and the advanced PN code are uniformly delayed by [[chip]. Changeover switch 1
Reference numerals 34, 135, and 136 denote the positive-phase PN code, the late-phase PN code, and the early-phase PN code generated from the spread code generator 116.
An N code and one of a positive PN code, a late PN code, and a leading PN code delayed by the delay units 131, 132, and 133 are selected, and the positive phase correlator 111 and the slow phase correlator 12 are selected.
1 and the leading phase correlator 122.

The synchronization acquisition unit 120 includes the positive-phase comparator 1
12 as well as the early phase comparator 117 and the late phase comparator 137
Is provided. These comparators 112, 117, 1
37 is a positive phase correlator 111 and a slow phase correlator 121, respectively.
In addition, the correlation value output from the phase advance correlator 122 is compared with a threshold value to perform level determination, and the determination result is supplied to the phase controller 138.

The phase controller 138 is connected to each of the comparators 11
Based on the judgment result supplied from 2,117,137,
The optimal phase control amount at that time is read from the database shown in FIG. Then, a control signal indicating this phase control amount is supplied to the VCO 115 via the changeover switch 114, thereby shifting the phase of each PN code generated from the spread code generator 116.

The switches 134, 135, and 136 for switching the PN code and the switch 114 for switching the phase control route are switched according to the level determination result of the phase comparator 137.

Next, a description will be given of the synchronization acquisition operation of the device configured as described above. In an initial state where spread code synchronization has not been established, the changeover switch 114 has been switched to the phase controller 138 for synchronization acquisition. Also, PN
Code changeover switches 134, 135, and 136
Are switched to the side that selects the PN code immediately after output from the spreading code generator 116.

When a received signal is input in this state, the correlation value between the received signal and the positive-phase PN code is calculated by the positive-phase correlator 11.
The positive phase comparator 112 determines whether the correlation value is equal to or greater than a threshold value. Also with it
The correlation values obtained by the slow correlator 121 and the fast correlator 122 of the synchronization follower 220 are respectively
7 and the phase advance comparator 117 determine whether or not the threshold value is exceeded. Then, these comparators 112, 1
The phase controller 138 reads the optimum phase control amount at that time from the database shown in FIG. 5 based on the results of the level determinations 37 and 117, and supplies this control signal to the VCO 115 via the changeover switch 114. Thereby, the phase of the PN code generated by the spreading code generator 116 is controlled.

For example, each of the comparators 112, 137, 1
17 are all "0", it is determined that the phase of the received PN code with respect to the received signal is completely different, and the phase controller 138 sends the spread code generator 1
A phase control signal is output to shift the phase of the PN code generated by 16 by 3/2 [chip]. Therefore, the phase of the received PN code is shifted by 3/2 [chip]. Thereafter, as long as the level determination results of the comparators 112, 137, and 117 are all "0", the above-described synchronization acquisition operation is repeated. That is, in the state where no synchronization is acquired, the received PN code is shifted at a relatively large interval of 3/2 [chip].

Further, the phase advance comparator 117 and the positive phase comparator 1
It is assumed that at least one of the twelve determination outputs has become “1”. At this time, in the database of the phase controller 138, a phase control amount determined so that the late PN code matches the received signal phase is stored in advance. For this reason, the phase controller 138 determines that the phase synchronization of the delayed PN code with respect to the received signal phase is close, and performs phase control for shifting the phase of the received PN code by [[chip] as shown in FIG. A signal is output. Therefore, the phase of the received PN code is shifted by [[chip]. That is, just before synchronization acquisition, the received PN code phase is precisely shifted by 1/2 [chip], which is smaller than 3/2 [chip], which is the normal shift width.

When the determination result "1" is output from the delay comparator 137, the phase controller 138 determines that the phase of the delayed PN code matches the received signal, and the spreading code generator 116 generates The phase of the PN code is fixed.

When the synchronization acquisition operation is completed, the changeover switches 134, 135, and 136 are switched to the delay units 131, 132, and 133, respectively, according to the determination result "1" output from the delay comparator 137. For this reason,
As shown in FIG. 6, the phase of each PN code supplied to each of the correlators 111, 121 and 122 is uniformly shifted by a delay of １ ／ [chip]. Will match. At the same time, the determination result “1” output from the delay comparator 137 makes
The changeover switch 114 switches from the phase controller 138 for synchronization acquisition to the phase controller 125 on the synchronization tracking side. Therefore, the apparatus shifts to the synchronization following operation by the synchronization following section 220 thereafter. The synchronization tracking control by the synchronization tracking unit 220 is the same as in the first embodiment.

As described above, in the present embodiment, in the synchronization acquisition operation, the level determination result of the correlation value of the positive-phase correlator 111 and the result of the determination of the late-phase correlator 121 and the The phase controller 138 integrates the level determination result of each correlation value of the detector 122 and
Code phase shift control is performed. For this reason, the phase shift width of the received PN code can be increased to 3/2 [chip] while keeping the correlation value monitoring step width equivalent to 1/2 [chip], thereby lowering the accuracy of synchronization acquisition. Without doing so, it is possible to further reduce the time required for synchronization acquisition.

Further, the phase of the delayed PN code is made coincident with the received signal phase, and after the coincidence, the received PN code is uniformly reduced to ［[chi].
By delaying by p] in the delay units 131, 132, and 133, the PN code of the positive phase matches the received signal phase. Therefore, the acquisition phase can be determined after sequentially confirming the synchronization state of the phase of the reception PN code with respect to the reception signal at the position of the leading phase, the position of the positive phase, and the position of the lagging phase. The accuracy of synchronization acquisition can be improved as compared with the case where immediate synchronization is established at the time when synchronization is achieved at the position.

The present invention is not limited to the above embodiments. For example, in the first embodiment, the shift control of the received PN code is performed based on the correlation value level determination result of the positive phase correlator 111 and the correlation value level determination result of the leading phase correlator 122. However, the level determination result of the correlation value of the positive-phase
The shift control of the received PN code may be performed based on the level determination result of the correlation value of 1.

In the second embodiment, the coincidence of the phase of the delayed PN code with the received signal is monitored, and when this coincidence is detected, the PN code phase is uniformly shifted by 1/2 [chip]. However, the coincidence of the phase of the leading PN code with respect to the received signal is monitored, and when this coincidence is detected, the PN code phase is uniformly reduced to 1/2 [c
hip], the synchronization acquisition may be determined.

In addition, the configuration of the spread spectrum communication apparatus,
The configurations of the synchronization acquisition unit and the synchronization tracking unit, the procedures of the synchronization acquisition control and the synchronization tracking control, and the like can be variously modified and implemented without departing from the gist of the present invention.

[0064]

As described in detail above, according to the present invention,
Since not only the correlation value between the received signal and the first received spread code but also the correlation value between the received signal and the second received spread code are used at the same time, the synchronization acquisition control is performed. Compared to the case where the synchronization acquisition control is performed using only the correlation value with the received spread code of 1, the phase shift width of the received spread code can be increased while maintaining the step of monitoring the correlation value. The time required for synchronization acquisition can be reduced without lowering the accuracy of the synchronization.

[Brief description of the drawings]

FIG. 1 is a circuit block diagram showing a first embodiment of a spread spectrum communication apparatus according to the present invention.

FIG. 2 is a circuit block diagram showing a configuration of a synchronization unit of the device shown in FIG.

FIG. 3 is a view showing contents of a database of a phase controller for synchronization acquisition in the synchronization unit shown in FIG. 2;

FIG. 4 is a circuit block diagram illustrating a configuration of a synchronization unit in a second embodiment of the spread spectrum communication apparatus according to the present invention.

FIG. 5 is a diagram showing the contents of a database of a phase controller for synchronization acquisition in the synchronization unit shown in FIG. 4;

FIG. 6 is a view for explaining a synchronization acquisition operation of the synchronization unit shown in FIG. 4;

FIG. 7 is a circuit block diagram showing a configuration example of a synchronization unit used in a conventional spread spectrum communication apparatus.

FIG. 8 is a diagram showing contents of a database of a phase controller for synchronization acquisition in the synchronization unit shown in FIG. 7;

[Explanation of symbols]

 11a, 22 ... Analog-to-digital converter (AD) 11b, 19 ... Digital-to-analog converter (DA) 12 ... Speech encoding / decoding (vocoder) 13 ... Microprocessor (MPU) 14 ... Data Generation circuit 15 Convolutional encoder 16 Interleave circuit 17 Spectrum spreader 18 Digital filter 20 Analog front end 21 Antenna 23 Search receiver 24 Automatic gain control (AGC) circuit 25, 26, 27 ... Finger circuit 28 ... Symbol combiner 29 ... Deinterleave circuit 30 ... Viterbi decoder 31 ... Error correction circuit 32 ... Keypad / display 100,110,120 ... Synchronization acquisition unit 111 ... Positive phase correlator 112 ... Positive phase comparison Units 113, 118, 138... Phase controller 114 for synchronization acquisition. Switch 115: Voltage controlled oscillator (VCO) 116: Spread code generator 117: Phase comparator 200, 210, 220 ... Synchronous tracking unit 121 ... Slow phase correlator 122 ... Lead phase correlator 123 ... Subtractor 124 ... Comparator 125 ... phase controller for synchronization tracking 131, 132, 133 ... delay unit 134, 135, 136 ... changeover switch 137 ... delay comparator

Claims (7)

[Claims] 1. A spread spectrum communication apparatus for receiving a radio signal that has been spread with a transmission spread code and despreading the received signal using the same receive spread code as the transmit spread code to reproduce transmission data. Receiving spread code generating means for respectively generating a first receive spread code and a second receive spread code having a phase shifted by a predetermined amount with respect to the first receive spread code; A first correlation unit for obtaining a correlation value with a reception spread code; a second correlation unit for obtaining a correlation value between the reception signal and the second reception spread code; and the first and second correlation units. A level determination is performed for each of the obtained correlation values, and the reception spreading is performed based on the level determination result so that the phases of the first and second reception spreading codes are closer to the phase of the reception signal. Spread spectrum communication apparatus characterized by comprising a phase control means of the synchronization capturing for shift control of the first and second received spreading code phase is generated from the No. generating circuit. 2. The receiving spread code generating means generates a positive receiving spread code as a first receiving spreading code, and has a phase relative to the positive receiving spreading code as a second receiving spread code. A phase control means for synchronization acquisition generates a quantitatively advanced reception spreading code, and a level determination result of a correlation value between a reception signal and the positive-phase reception spreading code; 2. A phase shift control of a positive-phase and a leading-phase received spread code generated by said received spread code generating means based on a result of level determination of a correlation value with a received spread code. Spread spectrum communication equipment. 3. The receiving spread code generating means generates a positive receiving spread code as a first receiving spreading code, and has a phase relative to the positive receiving spreading code as a second receiving spread code. Generates a delayed reception spread code with a fixed amount of delay, the phase control means for synchronization acquisition determines the level of the correlation value between the received signal and the positive-phase received spread code, 2. A phase shift control of the positive-phase and late-phase received spread codes generated by said received spread code generation means based on a result of level determination of a correlation value with a received spread code. Spread spectrum communication equipment. 4. The reception spread code generating means generates a normal phase receive spread code as a first receive spread code, and has a phase relative to the normal phase receive spread code as a second receive spread code. A phase-advanced reception spreading code and a phase-delaying reception spreading code whose phase is delayed by a predetermined amount are generated, respectively, and the phase control means for synchronization acquisition is a correlation value between the reception signal and the in-phase reception spreading code. Based on the result of level determination, the result of level determination of the correlation value between the received signal and the advanced reception spread code, and the result of level determination of the correlation value between the received signal and the late receive spread code. 2. The spread spectrum communication apparatus according to claim 1, wherein the phase of each of the positive-phase, early-phase and late-phase received spread codes generated by the received spread code generating means is shift-controlled. 5. The phase control unit for acquiring synchronization performs phase shift control for synchronizing a phase of a leading spread code generated by the spread code generation means with the received signal. After capturing, the phase of each reception spreading code generated from the reception spreading code generation means is uniformly shifted by an amount corresponding to the phase difference between the leading reception spreading code and the normal phase reception spreading code. 3. The spread spectrum communication apparatus according to claim 2, wherein the phase of the positive-phase received spread code is synchronized with a received signal. 6. The phase control section for acquiring synchronization performs phase shift control for synchronizing the phase of a delayed reception spread code generated by the reception spread code generation means with the received signal. After capturing, the phase of each received spread code generated from the received spread code generating means is uniformly shifted by an amount corresponding to the phase difference between the delayed receive spread code and the positive receive spread code. 4. The spread spectrum communication apparatus according to claim 3, wherein the phase of the in-phase received spread code is synchronized with a received signal. 7. A spread spectrum communication apparatus for receiving a radio signal that has been spread by a transmission spread code and despreading the received signal using the same reception spread code as the transmission spread code to reproduce transmission data. A reception spreading code for generating a reception spreading code of a positive phase, a reception spreading code of a leading phase whose phase is advanced by a predetermined amount with respect to the reception spreading code of the positive phase, and a reception spreading code of a phase lagging behind by the predetermined amount. A generating circuit, a positive-phase correlator that calculates a correlation value between the received signal and the positive-phase reception spread code, a phase correlator that calculates a correlation value between the received signal and the advanced reception spread code, A slow correlator that calculates a correlation value between the received signal and the delayed received spread code; and a phase correlator that obtains a correlation value of the received spread code with respect to the received signal when the phase synchronization of the received spread code is not captured. A level determination is performed on the obtained correlation value to obtain a first determination result, and a level determination is performed on at least one of the correlation value obtained by the early phase correlator and the correlation value obtained by the late phase correlator. Second row
A phase control unit for synchronization acquisition for shifting and controlling the phase of each reception spread code generated from the reception spread code generation circuit based on the first and second level determination results; After the phase acquisition is acquired by the synchronization acquisition circuit, the level difference between the correlation value obtained by the early phase correlator and the correlation value obtained by the late phase correlator is obtained, and this level difference is reduced. A spread spectrum communication apparatus comprising: a synchronization control phase control unit for controlling the phase of each reception spread code generated from the reception spread code generation circuit.