JPH11186938A - Spread spectrum communication system and spread spectrum communication method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To use an amplifier with a small back-off by decreasing the ratio of peak power to mean power of communication data in the multiplexed spread spectrum communication system. SOLUTION: A transmitter 2 in the spread spectrum communication system generates first coded data ϕ3, by multiplying orthogonal processing spread codes with parallel data ϕ5 and sums the products at a base band. Then a sum conversion circuit 13 converts the first coded data ϕ3 into second coded data ϕ4 where a difference between a mean value and a peak is reduced, and the data are amplified at an amplifier 27. A ratio of the peak power to the mean power of the output after the modulation is reduced by such a conversion above. Thus, in the multiplexed spread spectrum communication system, in spite of the use of an amplifier with small back-off, the distortion in communication data and increase in adjacent channel leakage power are prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spread spectrum communication system and a spread spectrum communication method for receiving a carrier modulated by coded communication data, decoding the received carrier and decoding the communication data. is there.

[0002]

2. Description of the Related Art Examples of a transmitter and a receiver used in a conventional spread spectrum communication system are shown in FIGS. 6 and 7, respectively. As shown in FIG. 6, a transmitter 70 used in a spread spectrum communication system includes a communication data generation device 71 that outputs encoded communication data.
And an output device 72 that modulates and transmits a carrier wave with the communication data.

[0003] The communication data generation device 71 has an input terminal 11.
The input terminal 11 receives a binary signal having two levels of +1 and -1 as digital data to be transmitted. This binary signal is a signal that changes at the symbol rate. The transmission data (binary signal) input to the input terminal 11 is supplied to the multiplier 73 by the spreading code generator 7.
4 is subjected to an encoding process by multiplying it by the output of No. 4 and then supplied to the output device 72. The output of the spreading code generator 74 is a pseudo-random sequence having two levels, +1 and -1. In this manner, the encoded communication data is output from the communication data generation device 71 to the output device 72. On the other hand, the output device 72 is a local oscillator 25 for outputting a carrier wave.
And a modulator 24 for modulating a carrier with the supplied communication data. The output of the modulator 24 is converted to a frequency propagating in space by a frequency converter 26, and then amplified by an amplifier 27. After being amplified, it is transmitted from the antenna 28.

On the other hand, as shown in FIG. 7, a receiver 80 of a spread spectrum communication system is provided with an input device 81 for demodulating a received signal and converting the signal into coded communication data indicating communication contents. A reception data generation device 82 that demodulates the encoded communication data.

The input device 81 has an antenna 31, and a received signal input to the antenna 31
After being amplified by 2, the frequency is converted to an intermediate frequency in the frequency converter 33. This intermediate frequency signal is supplied to the local oscillator 35
Is input to the mixer 34 together with the carrier wave output from the base station, where it is converted into a baseband signal and supplied to the reception data generation device 82.

[0006] The reception data generation device 82 includes a multiplier 43, and the signal supplied from the input device 81 is multiplied by the same pseudo-random sequence on the transmission side in the multiplier 43. In order to make this pseudo-random sequence the same phase as that on the transmitting side, the output of the multiplier 43 is integrated by the synchronizing circuit 46 after the integration operation for one symbol duration of the transmission data input to the integrator 45. The phase of the spreading code generator 44 is controlled so that is maximized. The output of the integrator 45 is output to the output terminal 42 after the polarity of the signal amplitude input to the discriminator 47 is determined.

If the symbol rate of the transmission data supplied to the input terminal 11 of the transmitter 70 is increased in order to increase the information transmission rate in such a spread spectrum communication system, the spread ratio cannot be secured. On the other hand, in a spread spectrum communication system, by multiplexing and transmitting information using a plurality of spread signals orthogonal to each other, the amount of information that can be transmitted at one time can be increased. Therefore, if information is multiplexed and transmitted, the information transmission speed can be substantially increased. Such a spread spectrum communication system is disclosed in Japanese Patent Application Laid-Open No. 145365/1995, and examples of a transmitter and a receiver of the multiplexed spread spectrum communication system are shown in FIGS. 8 and 9, respectively. is there.

The communication data generating device 71 of the transmitter 75 shown in FIG. 8 includes a serial-parallel conversion circuit 14 for converting transmission data (serial data) input from the input terminal 11 into parallel data. This serial-parallel conversion circuit 1
Each of the parallel data separated in 4 is multiplied by a spreading code in corresponding multipliers 18, 19 and 20. Here, the respective spread code generators 15, 16 and 17 output spread codes orthogonal to each other, and the data multiplied by the spread codes is added in the adder 21 to multiplex information. . The output of the adder 21 modulates the carrier from the local oscillator 25 in the modulator 24 of the output device 72 as described above. Modulator 24
Is output from the frequency conversion unit 26, is amplified by the amplifier 27, and is transmitted from the antenna 28.

A receiver 85 shown in FIG. 9 has an input device 81 similar to the input device 81 of the above-described receiver 80, and a baseband signal generated by the input device 81 is composed of three parallel data. And supplied to the parallel data generation devices 38, 39 and 40 of the reception data generation device 82. Parallel data generators 38 and 39
And 40 are multiplied by a spreading code having the same phase as that of the transmitting side and having the same phase, and then converted into serial data in a parallel-serial conversion circuit 41 and output from an output terminal 42. Is output. The information transmission speed of such a receiver 85 increases in proportion to the number of multiplexes.

Here, the carrier frequency output from the local oscillator 25 is ω, and the modulation method is BPSK (Binary Ph.D.).
ase Shift Keying). Thus, the output Vadd obtained by adding the outputs of the multipliers 18, 19 and 20 by the adder 21 is represented by the following equation (1).

[0011]

(Equation 1)

Accordingly, the output V of the modulator 24 is given by the following equation (2)
It is represented by

[0013]

(Equation 2)

Thus, the amplitude of the communication data takes four levels. For example, the amplitude of the communication data becomes -3 only when all the outputs of the multipliers are -1. On the other hand, the amplitude of the communication data is -1 when one of the outputs of the multiplier is +1 and the remaining two outputs are -1. In such a case, there are three cases. Note that the probability of occurrence of each amplitude value follows a binomial distribution.

[0015]

In the multiplexed spread spectrum communication system described above, as the number of multiplexed information increases, the probability of occurrence of communication data having a small amplitude increases. On the other hand, an increase in the number of multiplexed information increases the peak value of the amplitude and increases the ratio between the peak power and the average power. When the ratio between the peak power and the average power increases, the amplifier (R) provided in the output device of the transmitter is used.
When the ratio between the 1 dB gain compression point of the F amplifier and the operation input level, that is, the back-off is small, the communication data is distorted and the adjacent channel leakage power increases.

Therefore, it is conceivable to secure a large back-off while using the same amplifier. However, if the back-off is increased, the efficiency of the amplifier is reduced. Therefore, in order to obtain a required transmission output, an amplifier having large power consumption must be used. An external control circuit that changes the operating bias point of the amplifier according to the strength of the input signal may be used in order to prevent the distortion characteristics from deteriorating even with a small back-off. It is not preferable because it causes the cost of the machine to rise.

Therefore, the present invention provides a communication system and a communication method including a spread spectrum transmitting apparatus and a receiving apparatus capable of reducing the ratio between peak power and average power while having a high information transmission rate. It is intended to provide.

[0018]

Therefore, in the spread spectrum communication system and the spread spectrum communication method of the present invention, the parallel data are multiplied by orthogonalized spreading codes and added in the baseband. After the first encoded data is generated, the value of at least a part of the first encoded data is further changed to generate second encoded data in which the difference between the average value and the peak value is reduced. Like that.

That is, in the transmitter for a spread spectrum communication system according to the present invention, a transmitter for a spread spectrum communication system having an output device for modulating a carrier with coded communication data, amplifying and transmitting the modulated carrier, The communication data generating device converts input serial data into a plurality of parallel data, and generates first encoded data by multiplying each parallel data by an orthogonalized spreading code and adding them. A first encoding device, and a second encoding device that changes at least a part of the value of the first encoded data to generate second encoded data in which a difference between an average value and a peak value is reduced. And an encoding device.

A receiving apparatus for a spread spectrum communication system according to the present invention further comprises: an input apparatus for amplifying and demodulating a received signal to obtain communication data including second encoded data indicating communication contents; And a reception data generation device for decoding data. The second encoded data is the first
Is converted so that the difference between the average value and the peak value is reduced. The reception data generation device
A first decoding device for inversely transforming the second encoded data into the first encoded data, and a plurality of parallel data generated by multiplying the first encoded data by an orthogonalized spreading code; And a second decoding device that converts the plurality of parallel data into serial data and outputs the serial data.

In the spread spectrum communication system according to the present invention using such a transmitting apparatus and a receiving apparatus, a carrier wave which has been modulated after being coded by coded communication data and which has been amplified and transmitted is received and amplified. In a spread spectrum communication system that decodes communication data in which a carrier wave is demodulated, communication data converts input serial data into a plurality of parallel data and multiplies each parallel data by an orthogonalized spreading code. A first encoding process of converting the first encoded data into a first encoded data by adding, and converting a value of at least a part of the first encoded data into a different value to obtain a difference between an average value and a peak value. And a second encoding process for generating second encoded data in which is reduced.

Further, in the spread spectrum communication method according to the present invention, a transmitting step of transmitting a carrier wave that has been modulated by coded communication data and then amplified, and a communication process in which the received and amplified carrier wave is demodulated. And a receiving step of decoding data, wherein the transmitting step converts the input serial data into a plurality of parallel data, multiplies each parallel data by an orthogonalized spreading code, and adds them. A first encoding step of converting the first encoded data into a value different from at least a part of the value of the first encoded data,
A second encoding step of generating second encoded data in which the difference between the average value and the peak value is reduced. The receiving step includes a first decoding step of inversely converting the second coded data into the first coded data, and a plurality of parallel codes obtained by multiplying the first coded data by an orthogonalized spreading code. A second decoding step of generating data and converting the plurality of parallel data into serial data.

In the spread spectrum communication system and the spread spectrum communication method according to the present invention, the ratio between the peak value and the average value of the first coded data is increased by multiplexing the information, but the second value is increased. The encoding process converts the data into second encoded data in which the difference between the peak value and the average value is reduced. The output power modulated by the second encoded data is proportional to the square of the value of the second encoded data. Therefore, the ratio between the peak power and the average power of the signal to be amplified during transmission and reception is reduced. Therefore, even if an amplifier (RF amplifier) with a small back-off is used, distortion of communication data and increase in adjacent channel leakage power can be prevented. Also, since an amplifier with a small back-off can be used at the time of transmission and reception, the efficiency of the amplifier does not decrease,
Further, the power consumption of the amplifier does not increase.
Furthermore, since it is not necessary to use an expensive amplifier with complicated control, a spread spectrum communication system can be constructed at low cost.

In the second encoding device or the second encoding process, the difference between the peak value and the average value is reduced by adding or subtracting a uniform reference value to or from the first encoded data. It can be converted to second encoded data. In such a conversion method, despite the fact that the communication data is subjected to the second encoding process on the transmitting side, the receiving side multiplies the second encoded data by the orthogonalized spreading code. A third decoding step similar to the related art, in which a plurality of parallel data are generated and the plurality of parallel data are converted into serial data, can be executed.

Also, by a method such as replacing the first encoded data, the second encoded data can be generated so that the modulated output is balanced modulated. When such second encoded data is employed, transmitted and received signals are balanced, so that it is possible to prevent the carrier suppression degree from deteriorating. Therefore, a high-quality signal with little modulation distortion or the like can be transmitted, and high-quality communication data can be demodulated.

Here, as the transmitting device, a device having two sets of communication data generating devices, and having an output device that orthogonally modulates a carrier with the communication data of the two sets of communication data generating devices is employed. It is possible. With such a device, information can be multiplexed more and more easily, and the information transmission speed can be easily increased.

[0027]

[First Embodiment] A spread spectrum communication system to which the present invention is applied will be described below with reference to the drawings. FIGS. 1 and 2 respectively show, using a block diagram, a schematic configuration of a transmitting apparatus and a receiving apparatus of the spread spectrum communication system of the present example. The transmitting device 2 of this example is a device to which transmission data (serial data) φ1 in which a binary signal taking two levels of ± 1 changes at a symbol rate is input, and encodes this serial data φ1 to transmit communication data. It has a communication data generating device 3 for outputting as φ2 and an output device 4 for modulating and transmitting a carrier wave with the communication data φ2.

The communication data generating device 3 includes an input terminal 11 to which the serial data φ1 is input, and a serial data φ1 input to the input terminal 11 for converting a plurality of parallel data φ5.
And a first encoding device 12 that generates first encoded data φ3 by multiplying each parallel data φ5 by an orthogonalized spreading code and adding them, and a first encoding device
Value conversion circuit as a second encoding device that changes at least a part of the encoded data φ3 to generate second encoded data φ4 in which the difference between the average value and the peak value is reduced. 13 are provided.

The first encoding device 12 includes a serial-parallel conversion circuit 14 for converting serial data φ1 input to the input terminal 11 into three parallel data φ5, and a serial-parallel conversion circuit 14.
Spreading code generators 15, 16 and 17 for generating spreading codes orthogonalized to each other by a number equal to the parallel number of parallel converting circuit 14, and each of parallel data φ5 and each of spreading code generators 15, 16 and 17 Multipliers 18, 19, and 20 for multiplying by the output spreading code, and an adder 21 for adding the signals multiplied by the multipliers 18, 19, and 20 are provided. Addition value conversion circuit 13
Can convert the input first encoded data φ3 into second encoded data φ4 having a small ratio between the peak power and the average power and output the converted second encoded data φ4. In addition, the addition value conversion circuit 13 can convert the first encoded data φ3 so that the modulation in the output device 4 is uniform (balanced modulation).

The output device 4 includes a modulator 24 for modulating a carrier with communication data φ2 (second coded data φ4) from the communication data generator 3, a local oscillator 25 for outputting a carrier, and a modulator 24. A frequency converter 26 for converting the frequency of the modulated communication data φ2, an amplifier 27 for amplifying the communication data φ2 output from the frequency converter 26, and an antenna 28 for transmitting the communication data φ2 amplified by the amplifier 27; It has.

On the other hand, as shown in FIG. 2, the receiving apparatus 5 of the spread spectrum communication system of the present embodiment demodulates the received signal to obtain the communication data φ2 including the second encoded data φ4 indicating the communication contents. Input device 6 that performs communication, and received data generation device 7 that decodes communication data φ2 acquired by input device 6.
And

The input device 6 includes an antenna 31 for receiving a carrier wave modulated by the communication data φ2, and an antenna 3
An amplifier 32 for amplifying the signal received at 1;
A frequency converter 33 for converting the signal amplified by the above into an intermediate frequency signal, a mixer 34 and a local oscillator 35 for converting the intermediate frequency signal into a baseband signal.

The received data generation device 7 includes an addition value inverse transform circuit 36 as a first decoding device for inversely transforming the second encoded data φ4 into the first encoded data φ3, and the first encoded data. A second decoding device 37 that multiplies the data φ3 by an orthogonalized spreading code to generate a plurality of parallel data φ5, converts the plurality of parallel data φ5 into serial data φ1, and outputs the serial data φ1. . The second decoding device 37 generates 3 parallel data φ5 for generating 3 parallel data φ5.
A set of parallel data generators 38, 39 and 40;
These parallel data generators 38, 39 and 40
A parallel-serial conversion circuit 41 for converting the parallel data φ5 generated by the above into serial data φ1 and an output terminal 42 for outputting the serial data φ1 are provided. Each parallel data generating device 38, 39 and 40
Includes a multiplier 43, a spreading code generator 44, an integrator 45, a synchronizing circuit 46, and a discriminator 47, similarly to the parallel data generating device of the conventional receiving device 85.

FIG. 3 shows a transmission method in a spread spectrum communication system using the transmitting apparatus 2 and the receiving apparatus 5 of the present embodiment.
And FIG. 4 is a flowchart. FIG. 3 shows processing in the transmission device 2. First, in step ST1, when serial data φ1 is input to the input terminal 11, the serial-parallel conversion circuit 14 divides the serial data φ3 into three parallel data φ5 in step ST2. 19 and 20
Are multiplied by the orthogonalized spreading code. Each of the spreading code generators 15, 16 and 17 outputs a spreading code which is orthogonalized to each other so that information can be multiplexed. The parallel data φ5 multiplied by the spreading code in each of the multipliers 18, 19 and 20 is fully added in an adder 21 to form first encoded data φ3.

The first encoded data φ3 is subjected to a second encoding process in the addition value conversion circuit 13. That is, in step ST3, the first encoded data φ3
Are converted to the second encoded data φ4 such that the ratio between the peak power and the average power is small and the modulation in the modulator 24 is balanced. This second encoding process is performed, for example, as follows. Although the number of multiplexes of information in the transmitter shown in FIG. 1 is three, in order to make the effect of the present invention easier to understand, for example, when the number of multiplexes is seven, the first Encoded data φ3
From the above equation (2), (-7, -5, -3,-
Eight kinds of amplitude levels of 1, +1, +3, +5, +7) are taken. In the addition value conversion circuit 13, (+6, +2,
-2, -6, +6, +2, -2, -6) are added to the second encoded data φ4 of (-1, -3, -5, -7, +5, +3, +1). Convert. First before conversion
The probability that each value of the coded data φ3 of the following appears appears in accordance with the binomial distribution, and the average value of the absolute value is 2.1875.
Becomes Therefore, the ratio between the peak power and the average power of the output signal modulated by the first encoded data φ3 is (7 / 2.18)
75) ² = 10.2, which is 10.1 dB when converted to decibel units. On the other hand, the probability that the respective values of the converted second encoded data φ4 appear according to the binomial distribution as in the case of the first encoded data φ3,
The average of the absolute values is 5.8125. Therefore, the ratio between the peak power and the average power of the output signal modulated by the second encoded data φ4 is (7 / 5.8125) ² = 1.44.
When converted to decibel units, it becomes 1.6 dB. As described above, the ratio between the peak power and the average power of the transmitted / received signal is reduced by encoding the first encoded data φ3 and converting the encoded data to the second encoded data φ4 by the addition value conversion circuit 13. Communication data φ2 capable of modulating a carrier wave as described above.

Next, in step ST4, the modulator 24 modulates the carrier output from the local oscillator 25 with the second encoded data φ4. A well-known modulation method can be adopted as a modulation method in the modulator 24. For example,
The BPSK method can be adopted. In the present example, the second coded data φ4 converted by the addition value conversion circuit 13 is modulated so that the modulation in the modulator 24 is balanced, and a high-quality signal with little distortion or the like is obtained.

Finally, the output signal of the modulator 24 is subjected to appropriate processing by the frequency converter 26 and the amplifier 27,
It is transmitted from the antenna 28.

FIG. 4 shows processing in the receiving device 5. In the receiving apparatus 5, first, in step ST11, when the carrier modulated by the second coded data φ4 is received by the antenna 31, the carrier is amplified by the amplifier 32 and converted into the intermediate frequency signal by the frequency converter 33. Is done.
Next, in step ST12, the intermediate frequency signal is
4 is converted into the second coded data φ4 demodulated and output to the reception data generation device 7. Next, in step ST13, the second encoded data φ4 is inversely transformed into the first encoded data φ3 in the addition value inverse transform circuit 36 of the received data generating device 7. Next, step ST14
, The first encoded data φ3 is subjected to a second decoding process. That is, the first encoded data φ3 is branched and converted into parallel data φ6 by the parallel data generators 38, 39 and 40, and then converted into serial data φ1 by the parallel-serial conversion circuit 41. At the time of decoding, synchronization can be achieved using a header or the like prior to the communication data φ2.

As described above, in the spread spectrum communication system including the transmitting device 2 and the receiving device 5 of the present embodiment, the first coded data φ3 in which the ratio between the peak value and the average value is increased by multiplexing information. Is supplied to the addition value conversion circuit 13, where the data is converted into second encoded data φ4 in which the difference between the peak value and the average value is reduced. Therefore, the ratio between the peak power and the average power of the output signal modulated by the second encoded data φ4 is equal to the first encoded data φ3
Becomes smaller than the ratio between the peak power and the average power of the output signal modulated by. That is, the ratio between the peak power and the average power of the signal to be amplified during transmission and reception is reduced.
Therefore, even if an amplifier (RF amplifier) having a small back-off is used, distortion of communication data and increase in adjacent channel leakage power can be prevented. Further, since the amplifiers 27 and 32 having a small back-off can be used at the time of transmission and reception, the efficiency of the amplifier does not decrease, and the power consumption of the amplifier does not increase. Furthermore, there is no need to use expensive amplifiers with complicated control. Therefore, a low-cost, high-reliability spread spectrum communication system having excellent data quality can be constructed.

The addition value conversion circuit 13 includes a modulator 2
The first coded data φ3 is converted into the second coded data φ4 so that the output after the modulation by the first data 4 is uniform (balanced modulation). When such second encoded data is employed, transmitted and received signals are balanced, so that it is possible to prevent the carrier suppression degree from deteriorating. Therefore, a high-quality signal with little modulation distortion or the like can be transmitted, and high-quality communication data can be demodulated.

[Second Embodiment] Here, in the transmitting apparatus 2 described above, in the second encoding process in the addition value conversion circuit 13, non-uniform data is added to the first encoded data φ3. Thus, the data is converted to the second encoded data φ4 in which the difference between the peak value and the average value is reduced. On the other hand, it is also possible to add data of a predetermined constant value to the first encoded data φ3 and convert the data to the second encoded data φ4 to reduce the difference between the peak value and the average value. is there. For example, for ease of explanation in this example, assuming that the number of multiplexes is 7, (−7, −5, −
3, -1, +1, +3, +5, +7) are the first encoded data φ3 having eight different amplitude levels.
3 is input. The data “8” is uniformly added to the first encoded data φ3 as a reference value (+1, +3, +5, +7, +9, +11, +13,
+15) can be converted to the second encoded data φ4.
In this way, the probability that each value of the second encoded data φ4 appears will follow the binomial distribution, and the average of the absolute values will be 8.0. Therefore, the ratio between the peak power and the average power of the output signal modulated by the second encoded data φ4 is (15 / 8.0) ² = 1.875, which is 2.73 dB when converted to decibel units. In contrast,
As described above, the ratio between the peak power and the average power of the output signal modulated with the first encoded data φ3 before modulation is (7
/2.1875) ² = 10.2 (10.1 dB). Therefore, the second encoded data φ4 that can reduce the ratio between the peak power and the average power of the modulated output can be generated by adding or subtracting a uniform reference value.
Therefore, it is possible to realize a multiplexed spread-spectrum communication system in which distortion of communication data and increase in adjacent channel leakage power do not occur while using an amplifier having a small back-off. High quality and high reliability can be achieved. In addition to this,
When the conversion method of this example is adopted, the value “8” uniformly added in the addition value conversion circuit 13 is multiplied by the spread code in the receiving device 5 and subjected to integration operation for one symbol duration. Since it is 0 ", there is an advantage that the conventional receiver can be used with the same configuration. That is,
On the receiving side, the second encoded data φ4 is multiplied by the orthogonalized spreading code to generate a plurality of parallel data φ5,
These parallel data φ5 are converted to serial data φ1.
(A third decoding step).
However, when such second encoded data φ4 is used,
Since the modulation in the modulator 24 is not balanced, the degree of carrier suppression is degraded. Therefore, the quality of the communication data φ2 (second encoded data φ4) at the time of reception is likely to deteriorate, so that it is desirable to use a modulation device with little modulation distortion or the like.

[Third Embodiment] FIG. 5 shows a different example of the transmitting apparatus of the present invention. Transmission device 2 shown in FIG.
a has two sets of communication data generators 3a and 3b, and the output unit 4 includes a quadrature modulator 24a that orthogonally modulates a carrier with the communication data of the two sets of communication data generators 3a and 3b. I have. The configurations of the communication data generating devices 3a and 3b and the output device 4 are substantially the same as those in the above-described example, and thus the same reference numerals are given and the description is omitted.

The transmitting device 2a includes a serial-to-conversion circuit 14a for separating the serial data φ1 input to the input terminal 11 into two parallel data I and Q. In such a transmitting device 2a, the serial data φ1 input from the input terminal is separated into two parallel data I and Q by a serial-parallel conversion circuit 14a, each of which is two sets of communication data generating devices 3a and 3b. Is input to Communication data generating devices 3a and 3b
Then, similarly to the communication data generation device 3 described above, after separating the data input to the communication data generation devices 3a and 3b into three parallel data, each of them is multiplied by an orthogonalized spreading code, and these are multiplied. A first encoding process is performed by adding in the baseband band. Further, the first encoded data subjected to the first encoding process is converted into second encoded data in which the difference between the peak value and the average value is reduced and output. Then, in the output device 4, the carrier output from the local oscillator 25 is quadrature-modulated by the quadrature modulator 24a using the respective second encoded data from the two sets of communication data generating devices 3a and 3b. Therefore, the transmitting apparatus 2a can transmit twice as much data as the transmitting apparatus 2 by multiplexing again at the time of modulation, and as a result, the transmission speed is also doubled. Further, in the receiving apparatus that receives the communication data φ2 transmitted in this manner, it is possible to separate the data multiplexed after being modulated using the quadrature modulator 24a, and to separate each of the separated data. The transmitted data can be reproduced by performing the same demodulation processing as described above.

[0044]

As described above, in the spread spectrum communication system and the spread spectrum communication method according to the present invention, the first data is multiplied by the orthogonalized spread code and added in the baseband.
After generating the coded data of the above, further, at least a part of the value of the first coded data is changed to a different value to generate the second coded data in which the difference between the average value and the peak value is reduced. I am trying to do it. Therefore, the ratio between the peak power and the average power of the signal to be amplified at the time of transmission and reception can be reduced, and even if an amplifier (RF amplifier) with a small back-off is used, distortion of communication data and increase in adjacent channel leakage power can be reduced. Can be prevented. Further, since an amplifier with a small back-off can be used at the time of transmission and reception, the efficiency of the amplifier does not decrease and the power consumption in the amplifier does not increase. Further, since there is no need to use an expensive amplifier with complicated control, a reliable and low-cost spread spectrum communication system having excellent data quality can be constructed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic configuration of a transmission device of a spread spectrum communication system to which the present invention is applied.

FIG. 2 is a block diagram illustrating a schematic configuration of a receiving apparatus of a spread spectrum communication system to which the present invention has been applied.

FIG. 3 is a flowchart of data processing in the transmission device shown in FIG.

FIG. 4 is a flowchart of data processing in the receiving device shown in FIG. 2;

FIG. 5 is a block diagram illustrating a schematic configuration of a transmission device of an example different from FIG. 1;

FIG. 6 is a block diagram showing a schematic configuration of a transmitter of a conventional spread spectrum communication system.

FIG. 7 is a block diagram illustrating a schematic configuration of a receiver of a conventional spread spectrum communication system.

FIG. 8 is a block diagram showing a schematic configuration of a transmitter of a multiplexed spread spectrum communication system.

FIG. 9 is a block diagram showing a schematic configuration of a multiplexed spread spectrum communication system receiver.

[Explanation of symbols]

 2, 2a ··· Transmitting device of spread spectrum communication system 3, 3a, 3b ··· Communication data generating device 4 ··· Output device 5 ··· Receiving device of spread spectrum communication system 6 ··· Input device 7 ··· Received data generating device 12. first encoding device 13 addition value conversion circuit 14, 14a serial-conversion circuit 15, 16, 17 spreading code generator 18, 19, 20 multiplier 21 adder 24 modulator 24a quadrature modulator 25 local oscillator 36 addition value inverse conversion circuit 37 second decoding device 38, 39, 40 parallel data generation device 41 parallel-serial conversion circuit

Claims (12)

[Claims] 1. A transmission apparatus for a spread spectrum communication system, comprising: a communication data generation device that outputs encoded communication data; and an output device that modulates a carrier wave with the communication data, amplifies and transmits the modulated carrier wave, The communication data generating device converts the input serial data into a plurality of parallel data, multiplies each of the parallel data by an orthogonalized spreading code, and adds them to generate first encoded data. And a second code that changes at least a part of the value of the first encoded data to generate second encoded data in which a difference between an average value and a peak value is reduced. A transmission device for a spread spectrum communication system, comprising: 2. The transmitting apparatus for a spread spectrum communication system according to claim 1, wherein said second encoding apparatus adds or subtracts a predetermined reference value to or from said first encoded data. 3. The spectrum according to claim 1, wherein the second encoding device converts the first encoded data such that a modulated output from the output device is balanced-modulated. Transmitter for spread communication systems. 4. The communication device according to claim 1, further comprising: two sets of said communication data generating devices, wherein said output device performs quadrature modulation of a carrier wave by respective communication data of said two sets of communication data generating devices. For a spread spectrum communication system. 5. An input device for amplifying and demodulating a received signal to obtain communication data including second encoded data indicating communication contents, and a reception data generating device for decoding the communication data. The second encoded data is obtained by transforming the first encoded data so that a difference between an average value and a peak value is reduced. And a first decoding device for inversely transforming the first encoded data into the first encoded data. The first encoded data is multiplied by an orthogonalized spread code to generate a plurality of parallel data, And a second decoding device for converting the data into serial data and outputting the serial data. 6. The transmission device according to claim 1, wherein
A spread spectrum communication system, comprising: the receiving device according to claim 1. 7. A plurality of parallel data by multiplying a transmission device according to claim 2, a second encoded data obtained by demodulating a signal after reception and amplification and an orthogonalized spread code, and A spread-spectrum communication system, comprising: a receiving device that generates, converts the plurality of parallel data into serial data, and outputs the serial data. 8. A spread spectrum communication system for transmitting a carrier modulated after being modulated by encoded communication data, and decoding communication data obtained by demodulating the received and amplified carrier, wherein the communication is performed. The first data is obtained by converting input serial data into a plurality of parallel data, multiplying each of the parallel data by an orthogonalized spreading code and adding them.
A first encoding process of converting the first encoded data into at least a part of the first encoded data to a different value to reduce a difference between an average value and a peak value. And a second encoding process for generating encoded data. 9. The method according to claim 8, wherein, in the second encoding processing, the second encoded data is generated by adding or subtracting a predetermined reference value to or from the first encoded data. A spread spectrum communication system characterized by the following: 10. The spread spectrum communication system according to claim 8, wherein said second encoding process converts said first encoded data so that a modulated output is balanced-modulated. 11. A transmitting step of transmitting a carrier modulated after being modulated by encoded communication data and a receiving step of decoding communication data obtained by demodulating the received and amplified carrier. In the spread spectrum communication method, the transmitting step converts the input serial data into a plurality of parallel data, multiplies each parallel data by an orthogonalized spreading code, and adds the first data. A first encoding step of converting the data into data, and a second encoded data in which at least a part of the first encoded data is changed to a different value to reduce a difference between an average value and a peak value. And a second decoding step of generating the following. The receiving step includes a first decoding step of inversely converting the second coded data into the first coded data; Sign A second decoding step of generating a plurality of parallel data by multiplying the data by an orthogonalized spreading code, and converting the plurality of parallel data into serial data. . 12. A transmitting step of transmitting a carrier wave that has been modulated after being modulated by encoded communication data, and a receiving step of decoding communication data that has received and amplified the demodulated carrier wave. In the spread spectrum communication method, the transmitting step converts the input serial data into a plurality of parallel data, multiplies each parallel data by an orthogonalized spreading code, and adds the first data. A first encoding step of converting the data into data, and a second encoding step of generating second encoded data by adding or subtracting a predetermined reference value to or from the first encoded data. The receiving step includes generating a plurality of parallel data by multiplying the second encoded data by an orthogonalized spreading code, and converting the plurality of parallel data into serial data; A spread spectrum communication method comprising a third decoding step of converting.