JPH09321662A - Synchronization system for transmission reception system for mobile communication and its system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the time taking synchronization between a base station and a mobile station for the mobile communication. SOLUTION: A signal subject to spread modulation and sent from a base station B to a mobile station P in the mobile communication is given to a reception section 14 of the mobile station P, in which spread demodulation is taken by a spread code and synchronization is taken. The moment when the synchronization is established, the reception section 14 observes a phase of the spread code and when the phase reaches 0, a control signal is sent to a phase reset circuit 15. The phase reset circuit 15 receiving the control signal sends a signal R1 to reset the phase of the spread code to a transmission section 13. Then the phase of the spread code of the transmission section 13 is reset and in matching with the phase of the spread code when the synchronization is established in the reception section 14. Then the mobile station P sends the signal subject to spread modulation by the spread code to the base station B. The signal sent from the mobile station P to the base station B is synchronized while being subject to spread demodulation by the spread code of the reception section 94 synchronously with the spread code of the transmission section 93 of the base station.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a synchronization system for a transmission / reception system of mobile communication and its system, and more particularly, synchronization of a transmission / reception system of mobile communication using spread spectrum (SS) or code division multiple access (CDMA). Regarding

[0002]

2. Description of the Related Art As a conventional technique relating to this type of synchronization system, there is one disclosed in the following document. "Applied technology for spread spectrum communication method, 1992, supervised by Masao Nakagawa" P. 30-32

A conventional synchronization method of a transmission / reception system of mobile communication represented by the above-mentioned documents will be described. Generally, the receiving side knows the carrier frequency Fc, the data bit rate, the spreading code chip rate, and the spreading code 0.
It is one pattern, and the phase of the spreading code is often ignorant. Therefore, it is necessary to match the phases (timings) of the spreading codes on the transmitting side and the receiving side before performing communication. Matching the phases of the spreading codes of the transmission system and the reception system in this way is called "synchronization".

Generally, in spread spectrum (SS) or code division multiple access (CDMA), the phases of the spread codes are out of phase on the transmitting side and the receiving side if nothing is done. Therefore, in order to achieve synchronization, the phase of the spread code on the receiving side (timing for obtaining correlation with the spread code) is slid in order to obtain correlation, and when the correlation value exceeds a certain threshold (correlation value Synchronization is completed when the peak of is found).

[0005]

In the above conventional method, time for synchronization is required by the phase difference between the spreading codes on the transmitting side and the receiving side. When the cycle of the spreading code is short, the time required for synchronization is small even in the above-mentioned conventional method, but when the cycle of the spreading code is large, the time required for synchronization is long. Therefore, in the conventional method, it is difficult to synchronize in a short time when a spreading code with a long cycle is used.

From the above, it has been desired to develop a transmission / reception system synchronization method and a system therefor capable of shortening the processing time at the time of synchronization between a mobile communication base station and a mobile station. It was

[0007]

According to the present invention, there is provided a transmission / reception system synchronization method for a mobile communication base station to a mobile station.
A step of transmitting a signal that has been spread and modulated by the spreading code on the transmitting side of the fixed station, and a step of performing synchronization while spreading and demodulating the signal sent from the base station to the mobile station by the spreading code on the receiving side of the mobile station. And a step of synchronizing the spreading code on the transmission side of the mobile station with the spreading code when the synchronization of the received signal is established, and spreading from the mobile station to the base station using the synchronized spreading code on the transmission side. Transmitting the modulated signal,
A step of spreading and demodulating a signal sent from the mobile station to the base station by a spreading code on the receiving side that is synchronized with the spreading code on the transmitting side of the fixed station, and synchronizing.

Further, the synchronization system of the transmitting and receiving system according to the present invention is a mobile communication system for transmitting and receiving between a mobile station and a base station, wherein the mobile station receives a signal transmitted from the base station. And a means for synchronizing the received signal by spreading modulation on the receiving side by means of the spreading code on the receiving side and a means for generating a control signal when the synchronization of the receiving signal is established, and the spreading code on the transmitting side based on the control signal. And a means for transmitting a signal spread-modulated by the synchronized spreading code on the transmitting side to the base station, and the fixed station includes the mobile station. A means for transmitting a signal that is spread and modulated by a spreading code on the transmitting side, a means for receiving a signal transmitted from a mobile station,
The reception signal is spread and demodulated by the spreading code on the receiving side, which is synchronized with the spreading code on the transmitting side of the fixed station, and means for synchronizing the received signal.

In this type of mobile communication (SS, CDMA communication), in order to realize a telephone call service, it is essential that bidirectional communication is possible. The present invention shortens the time for synchronizing by utilizing the fact that this two-way communication is possible, and when the transmitting side and the receiving side synchronize for the first time (initial synchronization acquisition), Although the above conventional method will be used, if one-way communication is already synchronized in bidirectional communication, it is possible to shorten the synchronization time compared to the conventional method by using that. become.

Here, for convenience of explanation, it is assumed that the device that transmits the spread code to be synchronized is the mobile station P, and the device that receives the signal and performs the initial acquisition of the spread code is the base station B. In the mobile station P, a sync signal is extracted from the signal sent from the base station B, and the sync position of the transmitter of the base station B is adjusted to the position of the signal. For example, first, the signal S1 is sent from the base station B to the mobile station P via the high frequency RF. High frequency R at mobile station P
The signal S1 ′ is received by the receiving unit via F. In the receiving unit, the phase of the spread code is slid in order by the above conventional method to establish synchronization. At the same time when the synchronization is established, a control signal C2 indicating ON is sent from the receiving unit to, for example, a phase reset circuit as shown in an example in the embodiment described later.
Upon receiving the control signal C2, the phase reset circuit resets the phase of the spread code (resets the clock of the transmitter).
The signal R1 for sending is sent to the transmitting side. The transmitting unit receiving this signal R1 resets the clock and generates a spreading code having the same phase as the receiving unit. By performing the above operation,
The phase difference between the spreading code of the transmission system of the mobile station P and the spreading code of the reception system of the base station B is only the propagation delay between the base station B and the mobile station P. Therefore, the receiver of the base station B can achieve code synchronization in a very short time.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment of the Invention) FIG. 1 is a block diagram showing a configuration of a transmission / reception system according to a first embodiment of the present invention. Here, a case where a modulation scheme is CDMA is described. The mobile station P includes an antenna 11 and a radio unit 1.
2, transmitter 13, receiver 14, and phase reset circuit 15
It is composed of In addition, the base station B has an antenna 9
1, a wireless unit 92, a transmitting unit 93, and a receiving unit 94.

In the base station B, the transmission section 93 performs spread modulation, and the radio wave is transmitted from the antenna 91 via the radio section 92. The mobile station P receives the data D1 received from the antenna 11.
Is modulated into a baseband signal D2 by the wireless unit 12 and sent to the receiving unit 14. The receiving unit 14 performs an operation to synchronize with the received signal D2. The receiving unit 14 observes the phase of the spreading code of the receiving unit at the moment when the synchronization is established, and when the phase of the spreading code of the receiving unit becomes 0, sends the control signal C2 indicating ON to the phase reset circuit 15. . The phase reset circuit 15 that receives the control signal C2 resets the phase of the spread code (resets the clock of the transmitter 13).
1 is sent to the transmitter 13. Receiving the signal R1, the transmitting unit 13 resets the clock, generates the spreading code having the same phase as the receiving unit 14, generates the transmission signal E1 of the mobile station P, and outputs the transmission signal E1 to the radio unit 12. The wireless unit 12 wirelessly modulates the transmission signal E1 to generate a transmission signal E2, and transmits a radio wave to the base station B via the antenna 11.

In the base station B, the antenna 91 receives the power F1 from the mobile station P, and the receiving section 94 is received via the radio section 92.
And outputs the baseband signal F2. In the receiver 94,
A spreading code having the same phase as that of the transmitting unit 93 is generated and an operation for synchronizing is performed. At this time, the phase difference (time difference) between the spread code of the transmitter of the mobile station P and the spread code of the receiver of the base station B is only the phase difference of the propagation path delay.

Next, a detailed description of each part will be given. —Base Station (Transmission) — FIG. 2 is a block diagram showing the configuration of the transmission side including details of the transmission unit 93 of the base station B. 2 includes a PN clock generator 21, a spread code generator 22, and a spread modulator 2.
3, a baseband filter 24 and a D / A converter 25. The PN clock generator 21 generates the clock CLKs1 at a certain timing. The spread code generator 22 generates a spread code PNs1 synchronized with the clock CLKs1. In the spread modulator 23, the spread code P
The data Ds1 is spread-modulated with Ns1 and modulated data Ds2
Through a baseband filter 24 to a D / A converter 25
Output to The D / A converter 25 performs digital / analog conversion on the modulated data Ds2 to generate data Ds3 and outputs the data Ds3 to the wireless transmission unit 92S. In the wireless transmitter 92S,
The data Ds3 is wirelessly modulated and an electric wave is transmitted to the mobile station P via the antenna 91.

-Mobile Station (Reception)-FIG. 3 is a block diagram showing the configuration of the receiving side including the details of the receiving unit 14 of the mobile station P. The receiving unit 14 of FIG.
It is composed of a converter 31, a spread code generator 32, a spread demodulator 33, a synchronization decision unit 34 and a PN clock generator 35. The data Dr1 received from the antenna 11 is modulated into a baseband signal Dr2 by the wireless reception unit 12R and output to the A / D converter 31. A / D converter 31
Then, the received analog signal Dr2 is converted to digital signal Dr3
And outputs to the spread demodulator 33. In the spread code generator 32, the clock CLK of the PN clock generator 35
A spreading code PNr1 synchronized with r1 is generated.

In the spread demodulator 33, the received signal D3
And the spread code PNr1 generated by the spread code generator 32.
And the correlation value CP1 is obtained by demodulating
P1 is output to the synchronization determiner 34. When the correlation value CP1 is less than or equal to the "threshold value" of the synchronization determiner 34, the operation of changing the clock of the PN clock generator 35 is performed, and the spreading code generator 32 synchronizes with the new clock CLKr1 '. 'Occurs. Then, the new spreading code PNr1 'is then multiplied by the spreading demodulator 33 on the signal D3 to obtain the correlation, and the correlation value CP1' is obtained, and the synchronization determining unit 34 determines the synchronization in the same manner as described above.

When the correlation value CP1 becomes equal to or larger than the "threshold value" of the synchronization determiner 34 by repeating the above operation,
It is assumed that transmission and reception are synchronized. By changing the clock in this way to change the phase of the spread code of the spread code generator 32, the phase difference between the transmit and receive spread codes can be changed. The spreading code in this synchronized state is PNr
c1 and the clock are CLKrc1.

The synchronization determiner 34 observes a change in the phase of the spread code PNrc1 and when the phase of the spread code PNrc1 becomes 0 (that is, when the code sequence of PNrc1 becomes the initial value), the phase reset circuit. A control signal C2 indicating ON is output to 15. Control signal C from the synchronization determiner 34
The phase reset circuit 15 that has received 2 outputs the signal R1 for resetting the clock of the transmission unit 13 to the transmission unit 13.

-Mobile Station (Transmission)-FIG. 4 is a block diagram showing the configuration of the receiving side including the details of the transmitting unit 13 of the mobile station P. The transmitter 13 of FIG. 4 includes a PN clock generator 41, a spread code generator 42, and a spread modulator 4.
3, a baseband filter 44 and a D / A converter 45. Signal R1 from the phase reset circuit 15
The PN clock generator 41 which has received the? Initializes the PN clock and outputs the newly generated clock CLKS2 to the spread code generator 42. Here, CLKS2 and CLKrc1 move at the same timing. Next, in the spreading code generator 42, the spreading code P synchronized with CLKS2
Generate NS2. In the spread modulator 43, the spread code PN
The data DS1 is spread-modulated in S2, and the modulated data DS2 is output to the D / A converter 45 via the baseband filter 44. The D / A converter 45 digital-analog converts the modulated data DS2 to generate data DS3 and outputs the data DS3 to the wireless transmission unit 12. The wireless transmission unit 12S receives the data D
S3 is wirelessly modulated and a radio wave is transmitted to the base station B via the antenna 11.

-Base Station (Reception)-FIG. 5 is a block diagram showing the configuration of the receiving side including the details of the receiving section 94 of the base station B. The receiving unit 94 in FIG.
It is composed of a converter 51, a spread code generator 52, a spread demodulator 53, a synchronization decision unit 54 and a PN clock generator 55. The data DRl received from the antenna 91 is modulated into the baseband signal DR2 by the wireless reception unit 92,
It is output to the A / D converter 51. The A / D converter 51 converts the received analog signal DR2 into a digital signal DR3 and outputs it to the spread demodulator 53. Here, the PN clock generator 55 has the same initial phase as the PN clock generator 21, and generates the clock CLKR2 at the same timing as the transmission clock.

Next, the spread code generator 52 generates a spread code PNR2 synchronized with the clock CLKR2 of the PN clock generator 55. Here, the difference between the phase of the spreading code PNS2 of the transmitter of the mobile station and the phase of the spreading code PNR2 of the base station B is the propagation delay of the base station B and the mobile station P by performing the above series of operations. Only the hard delay difference. The spread demodulator 53 multiplies the received signal DR3 and the spread code PNR2 generated by the spread code generator 52 and demodulates it to obtain a correlation value CP2, and outputs the correlation value CP2 to the synchronization determiner 54. When the correlation value CP2 is less than or equal to the “threshold value” of the synchronization determiner 54, the synchronization determiner 5
4 outputs a control signal C56 to the PN clock generator 55. PN clock generator 55 receiving control signal C56
Performs the operation of changing the clock CLKR2 (for example, advancing the clock by one), and the new clock CL
Generate KR2 '. The spreading code generator 52 generates the spreading code PNR2 'synchronized with the new clock CLKR2'. Then, next, this new spreading code PNR2 'is multiplied by the signal DR3 in the spreading demodulator 53 to obtain the correlation,
The correlation value CP2 ′ is obtained, and the synchronization determiner 5 is operated in the same manner as above.
At 4, the synchronization determination is performed.

When the above-mentioned operation is repeated and the correlation value CP2 becomes equal to or more than the "threshold value" of the synchronization judging device, it is considered that transmission and reception are synchronized. Here, the phase difference between the spreading code PNS2 of the transmitter of the mobile station and the spreading code PNR2 of the base station B is, as described above, only the difference between the propagation delay and the hard delay. The number of times of changing the clock of the PN clock generator 55 can be reduced as compared with the method. Therefore, it is possible to shorten the time until the synchronization is achieved.

FIG. 7 is a timing chart showing a conceptual diagram of the series of synchronous operations. As you can see from Figure 7,
It can be seen that the synchronization time (search time in the figure) of the receiver 94 of the base station B is shorter than the synchronization time (search time) of the mobile station.

[0024]

As described above, according to the present invention, a base station for mobile communication transmits a signal spread-modulated by a spreading code on the transmitting side of the base station to the mobile station, and the base station moves from the base station. The signal sent to the station is code-synchronized while spreading and demodulating the spreading code on the receiving side of the mobile station, and the spreading code on the transmitting side of the mobile station is received on the receiving side when the code synchronization of the received signal is established. The mobile station transmits the signal spread-modulated by the synchronized spreading code of the transmitting side to the base station, and then fixes the signal sent from the mobile station to the base station. The spreading code on the receiving side of the fixed station is synchronized with the spreading code on the transmitting side of the station. Are synchronized with each other, and as a result, the transmission system of the mobile station spreads. It is possible to reduce the phase difference between the receiving system of the spread code No. and the base station, it is possible code synchronization in a short time at the receiving end of the base station. This is especially useful when you need to synchronize quickly.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a transmission / reception system according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a transmission side including details of a transmission unit of the base station of FIG.

3 is a block diagram showing a configuration of a receiving side including details of a receiving unit of the mobile station of FIG.

FIG. 4 is a block diagram showing a configuration of a transmission side including details of a transmission unit of the mobile station of FIG.

5 is a block diagram showing a configuration of a receiving side including details of a base station receiving section of FIG. 1. FIG.

6 is a timing chart showing a mechanism of a synchronous operation in the embodiment of FIG.

Claims (2)

[Claims] 1. A step of transmitting a signal spread-modulated by a spreading code on the transmission side of the fixed station from a base station for mobile communication to a mobile station, and the signal being transmitted from the base station to the mobile station. Synchronizing the received signal with the spreading code on the receiving side of the mobile station while spreading and demodulating, and synchronizing the spreading code on the transmitting side of the mobile station with the spreading code when the code synchronization of the received signal is established. The step of transmitting, from the mobile station to the base station, the step of transmitting a signal spread-modulated by the synchronized spreading code on the transmitting side, and a signal sent from the mobile station to the base station. , A step of performing synchronization while spreading and demodulating with the spreading code of the receiving side of the fixed station which is synchronized with the spreading code of the transmitting side of the fixed station. 2. A mobile communication system for transmitting and receiving between a mobile station and a base station, wherein the mobile station includes means for receiving a signal transmitted from the base station, and a spread code on the receiving side. A means for synchronizing the received signal while spreading and demodulating the received signal, and generating a control signal when the synchronization of the received signal is established, and synchronizing the spreading code on the transmitting side with the spreading code on the receiving side based on the control signal. And a means for transmitting a signal spread-modulated by the synchronized spreading code on the transmitting side to the base station, and the fixed station includes a transmitting side for the mobile station. Means for transmitting a signal spread-modulated by the spreading code, means for receiving the signal transmitted from the mobile station, and the received signal in synchronization with the spreading code on the transmitting side of the fixed station. Spreading code on the receiving side Transceiver system synchronization system characterized by comprising a means for taking a preparative synchronization with more spread demodulation.