JPH07183828A - Spread spectrum transmitter and receiver - Google Patents

Abstract

PURPOSE:To provide a spread spectrum radio device which is capable of realizing a synchronizing CDMA and to provide the radio device which is capable of promptly establishing code synchronization. CONSTITUTION:This transmitter/receiver is provided with a GPS reception part 14, and the part receives three GPS satellite waves or more and calculates an absolute time (GPS time) based on this reception wave. Based on the information at this time, a spreading code is generated, a transmission is performed in a transmission by using this spreading code, and the establishment of the synchronization of the spreading code is performed in a receiver. Therefore, the mutual interference between different code channels is reduced and the improvement of communication quality is expected. Because the spreading code based on the absolute time is calculated, the speed up of the code synchronication is attained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a code synchronization method in a spread spectrum communication apparatus.

[0002]

2. Description of the Related Art Conventionally, asynchronous CDMA (Code D
FIG. 9 is a block diagram showing the configuration of a radio by a frequency hopping (hereinafter, referred to as FH) system that performs multiple access by using the vision multiple multiple access. As shown in FIG. 9, signal data such as voice is converted into a baseband signal in the information processing section 1. Then, the baseband signal is transmitted to the information modulator 2 by FSK (Frequency Shift Ke).
information modulation such as ying). On the other hand, the spreading code generator 3 generates a spreading code for FH (pseudo noise code having a certain periodicity). Then, in synchronization with the generated spread code, the variable frequency synthesizer 4
Generate a pseudo-random transmit carrier frequency. Then, in the spread modulator 5, the above-described information modulated wave and the signal of the transmission carrier frequency are combined and emitted from the antenna 6 to the outside.

FIG. 10 shows a block diagram of an FH receiver for receiving radio waves oscillated by the transmitter shown in FIG. As shown in FIG. 10, the received signal received by the antenna 7 is code-spread as described above, and therefore must be synchronized with this code. Therefore, the code synchronization circuit 8 controls the phase of the spread code generated by the spread code generator 9 of this receiver, and by controlling this phase, the code synchronization with the received signal received by the antenna 7 is achieved. Established.

That is, the variable frequency synthesizer 10 generates a local frequency in synchronization with the spread code generated by the spread code generator 9. The local frequency generated in the variable frequency synthesizer 10 is mixed with the reception signal received from the antenna 7 in the spread demodulation unit 11 described above. This causes so-called spread demodulation. The information demodulation unit 12 applies to the signal after spread demodulation
Performs information demodulation. As a result of this information demodulation, the baseband signal in the transmitter described above is output from this information demodulation unit 12. Finally, the information processing unit 13 converts this baseband signal into the lower signal data and outputs it to the outside.

As a conventional synchronization establishment method, a so-called dependent code synchronization method is generally used in which the receiver detects the phase of the code on the transmitter side and the synchronization is matched with the phase. The code division multiplexing method based on such a dependent code synchronization method is called asynchronous CDM. The dependent code synchronization method can be roughly classified into a search method and a matched filter method.

The search method is a method of demodulating a received wave by using a spreading code appropriately generated on the receiving side and observing its output signal. Then, the phase of the spread code is shifted little by little to obtain the phase at which the output signal becomes maximum. By obtaining such a phase, the spreading code is synchronized between the transmitting side and the receiving side.
The matched filter method is a method of observing a series of received signals by using a predetermined delay element group that holds the received signal for one cycle, instead of shifting the phase of the spread code as in the above search method. Is. Then, the received signal corresponding to the time of this one cycle is always compared with the fixed data of one cycle of the spread code, and the correlation is obtained. By detecting the time when this correlation becomes maximum, the timing at which the fixed data of one cycle and the phase of the received signal match is detected. As a result, if the spread code generation is started at this timing, it is possible for the receiving side to obtain a spread code sequence whose phase matches that of the spread code of the received signal.

The delay element in this matched filter system includes SAW (surface acoustic wave element) and CC.
D (charge coupled device) or DMF (digital matched filter, that is, a shift register) is used.

[0008]

As described above, since the conventional CDMA radio is constructed as described above, synchronization is achieved between radios using different spreading code sequences. Not taken off. Therefore, there is a possibility that the mutual correlation with the communication using another different spreading code sequence becomes large, and as a result, interference between the code sequences may occur.

Further, in code synchronization by the search method or the matched filter method, which is a conventional code synchronization method, the time required to establish the synchronization has the property that it depends on the code rate of the spread code. There is. Therefore,
When this code rate is slow, there is a problem that the time required to establish synchronization becomes long. The present invention has been made in view of the above problems, and an object thereof is to suppress interference between code sequences of different communication systems (hereinafter, referred to as code channels) and achieve code synchronization quickly. It is to provide a spread spectrum wireless device capable of

[0010]

In order to solve the above problems, the first aspect of the present invention is to receive three or more GPS satellite waves,
A GPS receiver that calculates information about the current time, a time synchronization unit that calculates a spread code pattern that is synchronized with the information about the time, and a modulation that spread-code-modulates a signal to be transmitted based on the spread code pattern. A spread spectrum transmitter comprising:

In order to solve the above problems, the second aspect of the present invention receives a GPS satellite wave of three or more and calculates a current time information, and a spread code pattern synchronized with the time information. And a demodulation unit that performs spread code demodulation of a received signal based on the spread code pattern.

In order to solve the above-mentioned problems, a third aspect of the present invention is to receive three or more GPS satellite waves, calculate a current time information, and a spread code pattern synchronized with the time information. And a time synchronization unit that calculates, based on the spread code pattern when the spread code pattern is calculated, based on the spread code pattern obtained by dependent code synchronization when the spread code pattern is not calculated, respectively. A spread spectrum transmitter, comprising: a modulation unit that performs spread code modulation on a signal to be transmitted.

In order to solve the above problems, a fourth aspect of the present invention receives a GPS satellite wave of three or more and calculates a current time information, and a spread code pattern synchronized with the time information. And a time synchronization unit for calculating, based on the spread code pattern when the spread code pattern is calculated, and based on the spread code pattern obtained by dependent code synchronization when the spread code pattern is not calculated, A spread spectrum receiver comprising: a demodulation unit that performs spread code demodulation of a signal.

In order to solve the above-mentioned problems, a fifth aspect of the present invention is the spread spectrum transmitter according to the first or third aspect of the present invention, wherein the modulator performs modulation by frequency hopping. It is a spread transmitter.

In order to solve the above-mentioned problems, a sixth aspect of the present invention is the spread spectrum receiver according to the second or fourth aspect of the present invention, wherein the modulator performs demodulation by frequency hopping. It is a spread receiver.

In order to solve the above-mentioned problems, a seventh aspect of the present invention is the spread spectrum transmitter according to the first or third aspect of the present invention, wherein the modulation section performs direct spread modulation. It is a spread transmitter.

In order to solve the above problems, an eighth aspect of the present invention is the spread spectrum receiver according to the second or fourth aspect of the invention, wherein the modulator performs demodulation by direct spread. It is a spread receiver.

In order to solve the above problems, a ninth aspect of the present invention is the spread spectrum transmitter according to the first or third or fifth or seventh aspect of the present invention, wherein the signal to be transmitted is packet data. It is a spread spectrum transmitter characterized in that

In order to solve the above problems, a tenth aspect of the present invention is the spread spectrum receiver according to the second or fourth or sixth or eighth aspect of the present invention, wherein the received signal is packet data. It is a spread spectrum receiver.

[0020]

The GPS receiving section in the first and second aspects of the present invention calculates the time based on three or more GPS received waves, so that it is easy to obtain code synchronization.

The modulation section in the third and fourth aspects of the present invention comprises:
Even when the GPS receiver cannot be used due to geographical conditions, it is possible to obtain code synchronization by the conventional dependent code synchronization.

The modulation section in the fifth and sixth aspects of the present invention comprises:
Since the modulation is performed by frequency hopping, it is possible to quickly establish code synchronization in a frequency hopping system where code synchronization is difficult.

The modulation section in the seventh and eighth aspects of the present invention is
Since the modulation is performed by direct spreading, the correlation with other communication channels is reduced and the communication quality is improved.

Since the signals to be transmitted and the received signals in the ninth and tenth aspects of the present invention are packet data,
The collision of data transmission can be avoided without monitoring the line status.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the drawings.

Example 1. FIG. 1 is a block diagram showing the configuration of an FH radio device according to the first embodiment of the present invention. In particular, FIG. 1 shows a block diagram of the transmitter.
A corresponding block diagram of the receiver is shown in FIG. 1 and FIG. 2 are the same as those of the conventional ones, which have the same reference numerals as those of FIGS. 9 and 10 described above. The characteristic configuration of this embodiment is that the GPS receiver 14 is provided as shown in FIG. This GP
The S reception unit 14 receives GPS satellite waves of three or more channels and calculates the current time based on those signals. The calculated time is called GPS time in this embodiment.
A characteristic of this embodiment is that the internal time of the receiver is corrected based on this GPS time.
That is, the time synchronization unit 15 can calculate not only the spreading code pattern at the current time but also the spreading code pattern at an arbitrary time timing based on the GPS time and the setting of the code channel. Then, it is possible to perform transmission and reception using the spread code pattern calculated by the time synchronization unit 15.
Since the block diagram of the configuration of the FH transmitter is shown in FIG. 1, this code pattern is used for transmission in FIG. On the other hand, FIG. 2 shows a configuration block diagram of the FH receiver, in which the reception using the code pattern from the time synchronization unit 15 is performed.

As described above, the characteristic configuration of the first embodiment is the GPS receiving section 14 and the time synchronizing section 15 for both the transmitter and the receiver, and the other configurations are exactly the same as the conventional ones.

As described above, according to the first embodiment,
Synchronous CDMA is realized which can achieve code synchronization between different communication systems.

Therefore, since the mutual correlation between the spread codes of different communication systems becomes small, it is possible to reduce the interference with other communication systems.

Example 2. In the first embodiment described above, the wireless device based on FH (frequency hopping) has been described. However, it is also applicable to a wireless device that employs a so-called DS (Direct Spread) system. Figure 3
4 shows a block diagram of the configuration when the GPS receiving unit 14 and the time synchronizing unit 15 are used in a DS radio device. In FIG. 3, the spread modulator 5 is a balanced modulation circuit that performs balanced modulation and the like. As a result, the spread modulator 5
Performs direct spread modulation. Then, the direct diffusion modulated wave is emitted from the antenna 6 and received by the antenna 7 of the receiver shown in FIG. FIG. 4 shows a configuration block diagram of a receiver corresponding to FIG.

As shown in FIG. 4, the direct spread modulated wave received by the antenna 7 is subjected to spread demodulation in the same manner as when it was directly spread.

As described above, the method of synchronizing the GPS time by calculating the GPS time by the GPS receiving section 14 and the time synchronizing section 15 can be applied to the DS radio. Also in this case, as in the case of the FH radio device described above, the mutual correlation with the spreading code of the external communication system becomes small. , Which is the ratio of the signal carrier level to).

Example 3. In the first embodiment, the establishment of the code synchronization and the maintenance of the synchronization in the FH wireless device are realized by calculating the GPS time, but the so-called dependent code synchronization in the related art may be supplementarily used. It is suitable. FIG. 5 shows a block diagram of the configuration of an FH wireless device that supplementarily uses conventional dependent code synchronization together with such a method of establishing synchronization by GPS time. That is, in the FH receiver shown in FIG. 2 described above, the code synchronization circuit 8 (see FIG.
0) is not included in the configuration, but it is also preferable to use the synchronization by the conventional code synchronization circuit 8 in addition to the synchronization by the GPS reception unit 14 and the time synchronization unit 15. For example, it is possible to realize a receiver capable of establishing code synchronization and correcting code synchronization loss in a situation where GPS satellite waves cannot be received due to deterioration of geographical conditions.

Although only the block diagram of the FH receiver is shown in FIG. 5, the same principle can be applied to the FH transmitter.

Example 4. Further, in FIG. 5, the FH receiver uses the conventional code synchronization circuit 8 to establish the synchronization by the GPS receiver 14 and the time synchronizer 15, but it is applied to the DS receiver. It is also possible to do so. Thus, the conventional code synchronization circuit 8 and G
A configuration block diagram of a DS receiver including both the PS receiver 14 and the time synchronizer 15 is shown in FIG. Similarly to the FH receiver shown in FIG. 5, the DS receiver shown in FIG. 6 establishes code synchronization and performs code synchronization even when GPS satellite waves cannot be received due to geographical conditions or the like. It is possible to obtain a receiver capable of correcting the deviation.

Example 5. 7 and 8 show an example in which the time synchronization based on the GPS time described above is used for the transmission timing control when transmitting the position information indicating the position of the wireless device as packet data. In Figure 7,
A configuration block diagram of such an absolute time synchronization packet transmitter is shown, and FIG. 8 shows a configuration block diagram of the absolute time synchronization packet receiver.

As shown in FIG. 7, in the absolute time synchronization packet transmitter according to the present embodiment, in addition to the GPS receiving unit 14 and the time synchronization unit 15, the position of this transmitter is based on GPS satellite waves. A position information calculation unit 16 that calculates is included. One piece of data of this transmitter calculated by the position information calculation unit 16 is supplied to the packet communication unit 17. The packet communication unit 17 sends the supplied one data to packet data such as position information based on the time information calculated by the time synchronization unit 15. In this way, the packet data transmitted from this communication device has its transmission timing controlled based on the absolute time (GPS time).
Even without pre-processing such as monitoring the line status in advance
Efficient communication with few packet collisions is realized.

In the conventional packet communication, the timing of transmitting each packet was random, but since the timing of transmitting the packet can be adjusted in this way, the detection of the packet collision is also possible. It is possible to realize communication that can be performed quickly and can be quickly recovered from a collision. As a result, the throughput of the communication system is improved.

Further, according to the "perfect scheduling method" in which the timing of transmission by each station is completely allocated by the system station, it is possible to obtain a system whose throughput is close to 100%.

[0040]

As described above, according to the present invention, the spread code synchronization in the spread spectrum radio apparatus can be performed by a plurality of Gs.
The configuration is performed based on the time information calculated based on the GPS satellite wave from the PS satellite. Therefore, it is possible to reduce code interference in CDMA, and it is possible to speed up establishment of code synchronization in reception.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a synchronous CDMA FH according to a first embodiment of the present invention.
It is a block block diagram of a transmitter.

FIG. 2 is a diagram illustrating a synchronous CDMA / FH according to the first embodiment of the present invention.
It is a block block diagram of a receiver.

FIG. 3 is a diagram illustrating a synchronous CDMA / DS according to a second embodiment of the present invention.
It is a block block diagram of a transmitter.

FIG. 4 is a synchronous CDMA / DS according to a second embodiment of the present invention.
It is a block block diagram of a receiver.

FIG. 5 is a block configuration diagram of a hybrid code synchronization receiver in Embodiment 3 of the present invention.

FIG. 6 is a block configuration diagram of a hybrid code synchronization GPS receiver according to a fourth embodiment of the present invention.

FIG. 7 is a block configuration diagram of an absolute time synchronization packet transmitter according to a fifth embodiment of the present invention.

FIG. 8 is a block configuration diagram of an absolute time synchronization packet receiver according to a fifth embodiment of the present invention.

FIG. 9 is a block diagram of a conventional FH transmitter.

FIG. 10 is a block diagram of a conventional FH receiver.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Information processing section 2 Information modulation section 3 Spreading code generating section 4 Variable frequency synthesizer 5 Spreading modulation section 6 Antenna 14 GPS receiving section 15 Time synchronizing section

Claims (10)

[Claims] 1. A GPS receiving unit that receives three or more GPS satellite waves and calculates current time information, a time synchronization unit that calculates a spread code pattern synchronized with the time information, and a spread code pattern. A spread spectrum transmitter, comprising: a modulator for performing spread code modulation on a signal to be transmitted based on the spread spectrum transmitter. 2. A GPS receiving unit that receives three or more GPS satellite waves and calculates current time information, a time synchronization unit that calculates a spread code pattern synchronized with the time information, and a spread code pattern And a demodulation unit for performing spread code demodulation on the received signal based on the spread spectrum receiver. 3. A GPS receiving unit that receives three or more GPS satellite waves and calculates current time information, a time synchronization unit that calculates a spread code pattern synchronized with the time information, and the spread code pattern A modulator that spread-code-modulates a signal to be transmitted, based on the spread code pattern if calculated, or based on the spread code pattern obtained by dependent code synchronization if the spread code pattern is not calculated. And a spread spectrum transmitter. 4. A GPS receiving unit that receives three or more GPS satellite waves and calculates current time information, a time synchronization unit that calculates a spread code pattern synchronized with the time information, and the spread code pattern A demodulation unit for performing spread code demodulation of the received signal based on the spread code pattern when calculated, and based on the spread code pattern obtained by dependent code synchronization when the spread code pattern is not calculated. A spread spectrum receiver. 5. The spread spectrum transmitter according to claim 1, wherein the modulation section performs modulation by frequency hopping. 6. The spread spectrum receiver according to claim 2, wherein the modulator performs demodulation by frequency hopping. 7. The spread spectrum transmitter according to claim 1, wherein the modulation section performs modulation by direct spread. 8. The spread spectrum receiver according to claim 2, wherein the modulator performs demodulation by direct spread. 9. The spread spectrum transmitter according to claim 1, 3 or 5 or 7, wherein the signal to be transmitted is packet data. 10. The spread spectrum receiver according to claim 2, 4 or 6 or 8, wherein the received signal is packet data.