JP3479777B2 - Radio transmitting station and radio receiving station for spread spectrum radio communication - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio transmitter station and a radio receiver station for spread spectrum radio communication using a plurality of spread codes.

[0002]

2. Description of the Related Art In wireless communication, there is spread spectrum communication as a communication method having excellent interference resistance, and a method of performing spread spectrum with a plurality of spread codes as a method for increasing an information transmission speed while keeping a processing gain constant. Is JP-A-6
It is disclosed in 3-283246. FIG. 6 is a diagram for explaining a conventional spread spectrum communication system using a plurality of spread codes. In the figure, 6A is a wireless transmission station and 6B is a wireless reception station. First, the configuration of the wireless transmission station will be described. 6-1 is an information signal to be transmitted, 6-2 is a serial / parallel conversion circuit, 6-3-1 to 6-3-n are spread spectrum circuits, and 6-4. Is a synthesizing circuit, 6-5 is a transmitter, and 6-6 is a transmitting antenna. Next, the configuration of the wireless reception station 6B will be described. 6-7 is a receiving antenna, 6-8 is a receiver, and 6-9-
1 to 6-9-n are spectrum despreading circuits, 6-10-
1 to 6-10-n are demodulation circuits, 6-11 is a parallel / serial conversion circuit, and 6-12 is a demodulation signal.

Next, the principle of this spectrum wireless communication system will be described. In the wireless transmission station 6A, the information signal 6-
1 is input to the serial / parallel conversion circuit 6-2 and is converted into n parallel signals S _{1 to} S _n each having the same amount of information and having a transmission rate of 1 / n of the original signal 6-1. To be converted. This straight /
The n output signals S _{1 to} S _n of the parallel conversion circuit 6-2 are input to the spread spectrum circuits 6-3-1 to 6-3-n, respectively, and are multiplied by different spread codes to spread the spectrum. Are converted into _n signals SS _{1 to} SS _n . After n signals SS ₁ ~ SS _n has been made of the spread spectrum is synthesized by the synthesis circuit 6-4 in this manner are input to the transmitter 6-5, antenna 6-6 The transmitter 6-5 Be sent via.

In the radio receiving station 6B, the radio signal is received by the receiver 6-8 via the receiving antenna 6-7, and the received signal is n spectrum despreading circuits 6-9-1 to 6-9-1.
6-9-n. Then, these spectrum despreading circuits 6-9-1 to 6-9-n are used to spread spectrum circuits 6-3-1 to 6-3-n of the wireless transmission station 6A.
The spectrum despreading is performed using the same spreading code as that used in, and the n output signals obtained as a result are demodulated by the demodulation circuits 6-10-1 to 6-10-n, respectively. Then, n demodulation circuits 6-10-1 to 6-10
The output signal of −10-n is input to the parallel / serial conversion circuit 6-11.
By the reverse procedure performed in the parallel conversion circuit 6-2, n parallel signals are combined into a serial signal and output as a demodulated signal 6-12.

FIG. 7 is a diagram showing an example of a spectrum of a conventional technique. In the figure, (a) shows the spectrum of the input signal S ₁ to S _n of the spectrum spreading circuit 6-3-1~6-3-n, (b) is a spread spectrum circuit 6-3-1～
6-3-n output signals SS _{1 to} SS _n spectrum,
(C) is the spectrum of the output signal of the synthesis circuit 6-4. Here, since the serial / parallel-converted n signals have the same frequency bandwidth before spread spectrum and the same frequency bandwidth after spread spectrum, the gain obtained by performing spread spectrum, That is, the processing gains are also equal.

[0006]

In the spread spectrum wireless communication system, in order to perform high quality communication excellent in bit error rate, symbol error rate, frame error rate, etc., the information signal to be transmitted must be It is necessary to perform spread spectrum processing with processing gain as high as possible. However, since there is a limit to the usable frequency bandwidth, there is a limit to increasing the processing gain of spread spectrum and improving communication quality.

On the other hand, the required quality consisting of the bit error rate, the symbol error rate, the frame error rate, etc. often differs depending on the type of information signal to be transmitted. In such a case, if the difference in the required quality of each information signal is ignored and the spread spectrum of the same processing gain is uniformly applied, the processing gain is insufficient for a signal of high required quality,
A situation arises in which the processing gain is excessive for signals with low required quality.

The present invention has been made in view of the circumstances described above, and it is an object of the present invention to provide a spread spectrum wireless communication system for transmitting a plurality of information signals in a form suitable for each required quality.

[0009]

In order to solve the above problems, according to the present invention, in a radio transmission station, spread spectrum is applied to a plurality of information signals with a processing gain corresponding to each required quality.

That is, in the radio transmitter station for spread spectrum radio communication according to claim 1, the transmission rate is a low transmission rate for an information signal having a high required quality and a high transmission rate for an information signal having a low required quality. ₁ , V ₂ , ..., V
_{For n} information signals that are _n (n is an integer of 2 or more),
V ₁ · K ₁ = V ₂ · K ₂ = ... = V _n · K _n Each spreading code having spreading factors K ₁ , K ₂ , ..., K _n (≠ 1) satisfying the condition As a result, n spread spectrum signals (SS _{1 to} SS _n ) are generated, and these spread spectrum signals are combined and transmitted as radio signals in the same frequency band.

Further, in the radio receiving station for spread spectrum radio communication according to claim 2, the transmission rate is a low transmission rate for an information signal having a high required quality and a high transmission rate for an information signal having a low required quality. ₁ , V ₂ , ..., V
_{For n} information signals that are _n (n is an integer of 2 or more),
V ₁ · K ₁ = V ₂ · K ₂ = ... = V _n · K _n Each spreading code having spreading factors K ₁ , K ₂ , ..., K _n (≠ 1) satisfying the condition Thus, n spread spectrum signals (SS _{1 to} SS _n ) are generated, and these spread spectrum signals are combined and transmitted as a radio signal in the same frequency band. Receiving the wireless signal, for the received wireless signal,
Spectrum despreading using each of the plurality of spreading codes is performed, and the results of these spectrum despreading are demodulated.

Further, in the radio transmitter station for spread spectrum radio communication according to claim 3, the transmission rate of n (n is an integer of 2 or more) information signals is low, and the transmission rate of information signals of high required quality is low. , V _1, V ₂ is a high transmission rate with low required quality information signal, ..., is converted to V _n, with respect to the converted n pieces of information signals of the transmission rate, V ₁
By multiplying each spreading code having spreading factors K ₁ , K ₂ , ..., K _n (≠ 1) that satisfy the condition of K ₁ = V ₂ · K ₂ = ... = V _n · K _n Each of the n spread spectrum signals (SS _{1 to} SS _n ) is generated, and the spread spectrum signals are combined and transmitted as a radio signal in the same frequency band.

Further, in the radio receiving station for spread spectrum radio communication according to claim 4, the transmission rate of n (n is an integer of 2 or more) information signals is low, and the transmission rate of information signals of high required quality is low. , V _1, V ₂ is a high transmission rate with low required quality information signal, ..., is converted to V _n, with respect to the converted n pieces of information signals of the transmission rate, V ₁
By multiplying each spreading code having spreading factors K ₁ , K ₂ , ..., K _n (≠ 1) that satisfy the condition of K ₁ = V ₂ · K ₂ = ... = V _n · K _n The radio transmitted from a radio transmission station that generates n spread spectrum signals (SS _{1 to} SS _n ) and combines these spread spectrum signals to transmit as radio signals in the same frequency band. A signal is received, the received radio signal is subjected to spectrum despreading using each of the plurality of spread codes, and the result of the spectrum despreading is demodulated.

In addition, there is no spread spectrum according to claim 5.
In the wireless transmission station for line communication, the information signal to be transmitted is
Transmission speed is low for information signals with high required quality
Therefore, a high transmission rate is required for information signals with low required quality.
V₁, V₂,,, V_nN (n is an integer of 2 or more)
Information signals, and each divided information signal
However, if there are n kinds of spreading codes different from each other,₁・
K₁= V₂・ K₂= …… = V _n・ K_nTo meet the following conditions
Dispersion K₁, K₂, ..., K_nEach spreading code each having (≠ 1)
Spread spectrum was done by multiplying each by
n signals (SS₁~ SS_n) For each of these
Combining n signals with spectrum spreading,
The generated signal is transmitted as a wireless signal in the same frequency band.
It

In addition, there is no spread spectrum according to claim 6.
In the wireless receiving station for line communication, the information signal to be transmitted,
Transmission speed is low for information signals with high required quality
Therefore, a high transmission rate is required for information signals with low required quality.
V₁, V₂,,, V_nN (n is an integer of 2 or more)
Information signals, and each divided information signal
However, if there are n kinds of spreading codes different from each other,₁・
K₁= V₂・ K₂= …… = V _n・ K_nTo meet the following conditions
Dispersion K₁, K₂, ..., K_nEach spreading code each having (≠ 1)
Spread spectrum was done by multiplying each by
n signals (SS₁~ SS_n) For each of these
Combining n signals with spectrum spreading,
The generated signal is transmitted as a wireless signal in the same frequency band
Receives and receives the wireless signal transmitted from the wireless transmission station
The radio signals that have been generated are based on the n kinds of spread codes.
Each of these spectra has been subjected to spectrum despreading.
Demodulates the n signals obtained as a result of despreading, and
The n signals obtained from the
A procedure that is the reverse of the procedure in which the information signal is divided into n information signals.
Synthesize according to.

According to the radio transmitting station for spread spectrum wireless communication according to claim 1 and the radio receiving station for spread spectrum wireless communication according to claim 2, the information signal supplied to the radio transmitting station at a low transmission rate is high spread. Spread spectrum is performed at a high rate, and the information signal supplied to the wireless transmission station at a high transmission rate is spread spectrum at a low spread rate. According to this spread spectrum wireless communication system, a processing gain proportional to the spreading factor applied to each information signal can be obtained. Further, between the transmission rates V _{1 to} V _n of each information signal and the spreading factors K _{1 to} K _n applied to each information signal, V ₁ · K ₁ =
Since the relationship of V ₂ · K ₂ = ... = V _n · K _n is established, each signal subjected to spread spectrum can be transmitted in the same frequency band.

According to the radio transmitting station for spread spectrum wireless communication of the third aspect and the radio receiving station for spread spectrum wireless communication of the fourth aspect, the n information signals supplied to the radio transmitting station are transmitted. Each speed is converted into a predetermined transmission speed, and each information signal is subjected to spread spectrum at a spreading factor inversely proportional to each transmission speed. According to this spread spectrum wireless communication system, a processing gain proportional to the spreading factor applied to each information signal can be obtained. Further, between the transmission rates V _{1 to} V _n of each information signal and the spreading factors K _{1 to} K _n applied to each information signal, V ₁ · K ₁ = V ₂ · K ₂ =
... = each signal subjected to the spectrum spread can be transmitted in the same frequency band because relationship V _n · K _n holds.

Spread spectrum wireless communication according to claim 5
For wireless transmission station and spread spectrum according to claim 6
According to the wireless receiving station for line communication, it was supplied to the wireless transmitting station
Each information signal has a predetermined transmission rate V₁~ V_nN with
Each information signal is divided into information signals and each divided information signal is transmitted.
Spread spectrum is performed with a spreading factor that is inversely proportional to the transmission speed.
It According to this spread spectrum wireless communication system, each information
A processing rate proportional to the spreading factor applied to each of the broadcast signals.
The profit is obtained. In addition, the transmission speed V of each information signal ₁~ V_nWhen
Spreading factor K applied to each information signal₁~ K_nBetween V₁
・ K₁= V₂・ K₂= ... = V_n・ K_nThe relationship holds
Since each signal with spread spectrum has the same frequency
Can be sent by obi.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. (1) Configuration of Embodiment FIG. 1 is a diagram showing the configuration of a specific embodiment of the present invention.
In the figure, 1A is a wireless transmission station and 1B is a wireless reception station. In the wireless transmission station 1A, 1-1 is an information signal to be transmitted, 1-2 is a signal division circuit, and 1-3-1 to 1-3-3.
n is a spread spectrum circuit, 1-4 is a combining circuit, 1-5
Is a transmitter and 1-6 is a transmission antenna. In the wireless reception station 1B, 1-7 is a receiving antenna, 1-8 is a receiver, 1-9-1 to 1-9-n are spectrum despreading circuits, and 1-10-1 to 1-10-n. Is a demodulation circuit, 1-11
Is a signal synthesis circuit, and 1-12 is a demodulation signal.

<Structural Example of Spread Spectrum Circuit> FIG. 2 is a block diagram of the spread spectrum circuit 1-3-1 to 1-3 in this embodiment.
A specific configuration example of -3-n will be shown. In the figure, 2-1
Is a multiplier and 2-2 is a spreading code generator. The output of the signal division circuit 1-2 is input to the multiplier 2-1. The spread code generator 2-2 generates a spread code whose period is represented by Ki, and this spread code is input to the multiplier 2-1. The multiplier 2-1 multiplies the output signal of the signal division circuit 1-2 by the spread code which is the output signal of the spread code generation circuit 2-2,
The spread spectrum signal obtained as a result of this multiplication is output to the combining circuit 1-4.

<Structural Example of Signal Dividing Circuit> FIG. 3 is a diagram for explaining a signal dividing process performed by the signal dividing circuit 1-2 in this embodiment. In this signal division processing, at regular time intervals,
Its time input information signal in (FIG. 3 (a)) is divided into a plurality of information signals D ₁ to D _n (Figure 3 (b)). Then, these information signals D _{1 to} D _n are output within a fixed time regardless of the amount of each information (FIG. 3C). Therefore, among the divided information signals, an information signal having a large amount of information is output at a high transmission rate, and an information signal having a small amount of information is output at a low transmission rate. The signal dividing circuit 1-2 in this embodiment divides the information signal 1-1 into a plurality of information signals S _{1 to} S _n each having a transmission rate of V _{1 to} V _n by performing the above processing. Is.

FIG. 4 shows an example of a concrete configuration of a circuit for performing signal division processing. In the figure, 4-1 is a serial / parallel conversion circuit, and 4-2 is a combining circuit. Transmission speed is 3a (bp
The signal represented by s) is 2a (bps) and a
The case of division into a signal represented by (bps) is shown. The information signal is input to the serial / parallel conversion circuit 4-1 and converted into three signals whose transmission rate is represented by a (bps), and two signals of the three signals are input to the synthesis circuit 4-2. And are combined into a signal having a transmission rate of 2a (bps).

(2) Operation of the embodiment FIG. 5 shows the spectrum of the signal of each part of the wireless transmission station 1A. In FIG. 5, (a) shows the spread spectrum circuit 1-3-1 to 1-3-3. n input signals S _{1 to} S _n
Spectrum, (b) is spread spectrum circuit 1-3
Spectrum of the output signal SS ₁ ~ SS _n of -1~1-3-n, (c) is the spectrum of an output signal of the combining circuit 1-4. Hereinafter, referring to FIG. 5 in addition to the above-mentioned FIG. 1,
The operation of this embodiment will be described.

The information signal 1-1 has a transmission rate of V ₁ , V ₂ , ..., V by the signal dividing circuit 1-2 according to the required quality.
is divided into n information signal S ₁ to S _n, represented by _n. These information signals S _{1 to} S _n have frequency bandwidths corresponding to their respective transmission rates. For example, in FIG. 5A, the information signal S ₁ is output at a low transmission rate, so that the frequency bandwidth is narrow. On the other hand, the information signal S _n is output at a high transmission rate and therefore has a wide frequency bandwidth.

Information having a wide and narrow frequency bandwidth
Signal S₁~ S_nAre spread spectrum circuits 1-3-
1 to 1-3-n. And each signal S₁~ S_n
However, the spread spectrum using different spreading codes
However, the transmission speed is high and the frequency band
A wide information signal (for example, signal S in FIG. 5)_n) Against
Is a spread spectrum using a spreading code with a low spreading factor
Done. In contrast, the transmission speed is low and the frequency bandwidth is
Narrow information signal (for example, signal S in FIG. 5)₁) For
There is no spread spectrum using a spreading code with a high spreading factor.
To be done. More specifically, the transmission speed V₁~ V_nHave
Each information signal S₁~ S_nIn contrast, the above condition V₁・ K₁= V₂
・ K₂= ... = V_n・ K_nDiffusivity K that satisfies₁~ K_nDiffusion
Spread spectrum is performed using a code. As a result,
From each spread spectrum circuit 1-3-1 to 1-3-n,
Signal spread spectrum in the same frequency bandwidth
SS ₁~ SS_nIs obtained.

Further, paying attention to the transmission speed, the transmission rate of the spread spectrum signal SS ₁ ~ SS _n is applied to each and the transmission speed V ₁ ~V _n of the previous signal S ₁ to S _n to be spread It is expressed as the product of the diffusivities K _{1 to} K _n . Therefore, the transmission rate of the signal SS _i after the spread spectrum is V _i · K _i
However, since V ₁ · K ₁ = V ₂ · K ₂ = ... = V _n · K _n , there are n spread spectrum circuits 1-3-1 to 1-3.
Transmission rate of the output signal SS ₁ ~ SS _n of -n are all equal.

[0027] After being synthesized by such n signals SS ₁ was made of the resulting spread spectrum in the ~ SS _n synthesis circuit 1-4 are supplied to the transmitter 1-5, transmission antenna 1-6 Is transmitted as a radio signal in the same frequency band.

In the radio receiving station 1B, the received signal is input to the n despreading circuits 1-8-1 to 1-8-n,
In these despreading circuits, despreading is performed with the same spreading code as in the radio transmitting station 1A, and the n output signals obtained as a result are input to the demodulation circuits 1-10-1 to 1-10-n. Then, the respective output signals of the demodulation circuits 1-10-1 to 1-10-n are input to the signal synthesis circuit 1-11, and in the signal synthesis circuit 1-11, the signal division circuit 1-2 is used. The signals are combined in the reverse procedure and output as a demodulated signal.

(3) Another Embodiment The embodiment of the system in which the wireless transmission station receives the information signal to be transmitted and then divides it into a plurality of information signals has been described above, but the scope of the present invention is not limited to this. For example, the following modifications are possible.

The radio transmitting station receives a plurality of information signals as they are, instead of dividing the radio transmitting station into a plurality of pieces after receiving the information signals. Then, at that time, an information signal having a high required quality is received at a low transmission rate, and the information signal is subjected to spread spectrum using a spreading code having a high spreading factor inversely proportional to the transmission rate. On the other hand, an information signal having a low required quality is received at a high transmission rate, and the information signal is subjected to spread spectrum using a spreading code having a low spreading factor inversely proportional to the transmission rate. In this way, signals of the same frequency band that have been spread spectrum are obtained with a processing gain according to the required quality of each information signal, and then combined and transmitted. The point that the radio receiving station uses the same spreading code as that used in the radio transmitting station is the same as the above embodiment.

The wireless transmission station receives a plurality of information signals as they are. Alternatively, after receiving the information signal, the information signal is divided into a plurality of information signals. Then, among the plurality of information signals received directly or the plurality of information signals obtained by the division, the information signal having a high required quality is converted into a low transmission rate, and a high spreading factor inversely proportional to the transmission rate is applied to this information signal. Spread spectrum using the spread code of. On the other hand, an information signal having a low required quality is converted into a high transmission rate, and the information signal is subjected to spread spectrum using a spreading code having a low spreading factor inversely proportional to the transmission rate. In this way, signals of the same frequency band that have been spread spectrum are obtained with a processing gain according to the required quality of each information signal, and then combined and transmitted. The point that the radio receiving station uses the same spreading code as that used in the radio transmitting station is the same as the above embodiment.

In the above embodiment, an example in which the spread spectrum circuit and the inverse spread spectrum circuit are constructed in the base band is explained, but the same effect can be obtained in the circuit in the intermediate frequency band.

[0033]

As described above, according to the present invention,
The n information signals can be spectrum-spread with a processing gain required for each, and can be transmitted as a radio signal in the same frequency band, and there is an effect that communication according to the required quality of each information signal can be performed.

[Brief description of drawings]

FIG. 1 is a block diagram illustrating a spread spectrum wireless communication system according to an embodiment of the present invention.

FIG. 2 is a diagram showing an example of a spread spectrum circuit in the embodiment.

FIG. 3 is a diagram illustrating a signal division process performed in the embodiment.

FIG. 4 is a diagram showing a configuration example of a signal division circuit in the embodiment.

FIG. 5 is a diagram showing a spectrum of a signal of each part in the embodiment.

FIG. 6 is a diagram illustrating a spread spectrum wireless communication system of a conventional technique.

FIG. 7 is a diagram showing a spectrum of a signal of each unit in a spread spectrum wireless communication system of a conventional technique.

[Explanation of symbols]

1-1 ... Information signal, 1-2 ... Signal division circuit, 1-3
-1 to 1-3-n ... Spread spectrum circuit, 1-4 ...
... Synthesis circuit, 1-5 ... Transmitter, 1-6 ... Transmission antenna, 1-7 ... Reception antenna, 1-8 ... Receiver, 1-
9-1 to 1-9-n ... Despreading circuit, 1-10-1 to 1
-10-n ... Demodulation circuit, 1-11 ... Signal combining circuit,
1-12 ... Demodulated signal.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-5-153086 (JP, A) JP-A-6-14006 (JP, A) JP-A-5-316072 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) H04J 13/00-13/06 H04B 1/69-1/713 H04Q 7/38

Claims (6)

(57) [Claims] 1. An information signal having a high required quality has a low transmission rate, and an information signal having a low required quality has a high transmission rate of V ₁ , V ₂ , ..., V _n (n is 2 or more). For n information signals that are (integer), spreading factors K ₁ , K ₂ , ..., K _n (V ₁ · K ₁ = V ₂ · K ₂ = ... = V _n · K _n satisfying the condition ≠ 1)
N spread spectrum signals (SS _{1 to} SS _n ) are generated by multiplying the spread codes respectively, and these spread spectrum signals are combined into a radio signal of the same frequency band. A wireless transmission station for spread spectrum wireless communication, characterized by transmitting. 2. A transmission rate is a low transmission rate for an information signal having a high required quality, and a high transmission rate for an information signal having a low required quality. V ₁ , V ₂ , ..., V _n (n is 2 or more). For n information signals that are (integer), spreading factors K ₁ , K ₂ , ..., K _n (V ₁ · K ₁ = V ₂ · K ₂ = ... = V _n · K _n satisfying the condition ≠ 1)
N spread spectrum signals (SS _{1 to} SS _n ) are generated by multiplying the spread codes respectively, and these spread spectrum signals are combined into a radio signal of the same frequency band. The radio signal transmitted from the transmitting radio transmission station is received, the received radio signal is subjected to spectrum despreading using each of the plurality of spread codes, and the result of the spectrum despreading is demodulated. A radio receiving station for spread spectrum radio communication, characterized in that 3. The transmission rate of n (n is an integer of 2 or more) information signals is V ₁ which is a low transmission rate for an information signal of high required quality and a high transmission rate for an information signal of low required quality. , V ₂ , ..., V _n , and for these n information signals with converted transmission rates, V ₁ · K ₁ = V ₂ · K ₂ = ... = V _n · K _n Diffusivity K ₁ , K ₂ , ..., K _n (≠ 1)
N spread spectrum signals (SS _{1 to} SS _n ) are generated by multiplying the spread codes respectively, and these spread spectrum signals are combined into a radio signal of the same frequency band. A wireless transmission station for spread spectrum wireless communication, characterized by transmitting. 4. The transmission rate of n (n is an integer of 2 or more) information signals is V ₁ which is a low transmission rate for information signals of high required quality and a high transmission rate for information signals of low required quality. , V ₂ , ..., V _n , and for these n information signals with converted transmission rates, V ₁ · K ₁ = V ₂ · K ₂ = ... = V _n · K _n Diffusivity K ₁ , K ₂ , ..., K _n (≠ 1)
N spread spectrum signals (SS _{1 to} SS _n ) are generated by multiplying the spread codes respectively, and these spread spectrum signals are combined into a radio signal of the same frequency band. The radio signal transmitted from the transmitting radio transmission station is received, the received radio signal is subjected to spectrum despreading using each of the plurality of spread codes, and the result of the spectrum despreading is demodulated. A radio receiving station for spread spectrum radio communication, characterized in that 5. An information signal to be transmitted has a low transmission rate for an information signal having a high required quality, and a high transmission rate for an information signal having a low required quality V ₁ , V ₂ , ...,
V _n is divided into n (n is an integer of 2 or more) information signals, and the divided information signals are n kinds of spreading codes different from each other, and V ₁ · K ₁ = Diffusivities K ₁ , K ₂ , ..., K _n (≠ 1) satisfying the condition of V ₂ · K ₂ = ... = V _n · K _n
By multiplying each of the spreading codes respectively having the following: _n to generate the spread spectrum signals n (SS _{1 to} SS _n ), and to synthesize these spread spectrum n signals. A wireless transmitting station for spread spectrum wireless communication, which transmits the generated signal as a wireless signal in the same frequency band. 6. An information signal to be transmitted has a low transmission rate for an information signal having a high required quality, and a high transmission rate for an information signal having a low required quality V ₁ , V ₂ , ...,
V _n is divided into n (n is an integer of 2 or more) information signals, and the divided information signals are n kinds of spreading codes different from each other, and V ₁ · K ₁ = Diffusivities K ₁ , K ₂ , ..., K _n (≠ 1) satisfying the condition of V ₂ · K ₂ = ... = V _n · K _n
By multiplying each of the spreading codes respectively having the following: _n to generate the spread spectrum signals n (SS _{1 to} SS _n ), and to synthesize these spread spectrum n signals. The radio signal transmitted from a radio transmission station that transmits the signal as a radio signal in the same frequency band, and performs spectrum despreading with the n kinds of spread codes on the received radio signal. The n signals obtained as a result of spectrum despreading are demodulated, and the n signals obtained by this demodulation are subjected to a procedure reverse to the procedure in which the information signal is divided into n information signals in the wireless transmission station. A radio receiving station for spread spectrum radio communication characterized by combining.