JP3243108B2 - Spread spectrum wireless communication system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spread spectrum radio communication system 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 excellent in interference resistance, and a method of performing spread spectrum using a plurality of spreading codes as a method of increasing an information transmission speed while keeping a processing gain constant. Was published in
3-283246. FIG. 6 is a diagram illustrating a conventional spread spectrum communication method using a plurality of spread codes. In the figure, 6A is a wireless transmitting station, and 6B is a wireless receiving 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 spectrum spread circuits, and 6-4. Is a combining circuit, 6-5 is a transmitter, and 6-6 is a transmitting antenna. Next, the configuration of the wireless receiving station 6B will be described. 6-7 is a receiving antenna, 6-8 is a receiver, and 6-9-
1-6-9-n are spectrum despreading circuits, 6-10-
1-6-10-n is a demodulation circuit, 6-11 is a parallel / serial conversion circuit, and 6-12 is a demodulated signal.

Next, the principle of the spectrum radio communication system will be described. In the radio transmitting station 6A, the information signal 6-
1 is inputted to the serial / parallel conversion circuit 6-2, each identical having the amount of information and the n pieces of parallel signals S ₁ to S _n having a transmission speed of 1 / n of the original signal 6-1 Is converted. This direct /
N output signals S ₁ to S _n of the parallel converter 6-2, respectively, are input to the spectrum spreading circuit 6-3-1～6-3-n, each different spreading code is multiplied, spread spectrum It is converted into n signals SS ₁ ~ SS _n which made the the. The n spread-spectrum signals SS _{1 to} SS _n are synthesized by the synthesizing circuit 6-4 and then input to the transmitter 6-5, where the antenna 6-6 is transmitted. Sent via

In the radio receiving station 6B, a radio signal is received by a receiver 6-8 via a receiving antenna 6-7, and the received signal is divided into n number of 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 provide spread spectrum circuits 6-3-1 to 6-3-n of radio transmitting station 6A.
Are despread using the same spreading code as used in (1), and the resulting n output signals are demodulated by demodulation circuits 6-10-1 to 6-10-n, respectively. And n demodulation circuits 6-10-1 to 6-6
The output signal of -10-n is input to the parallel / serial conversion circuit 6-11.
In the reverse procedure performed by 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 according to the prior art. 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～
The output signal SS ₁ ~SS _n of the spectrum of 6-3-n,
(C) is the spectrum of the output signal of the synthesis circuit 6-4. Here, the n signals subjected to the serial / parallel conversion have the same frequency bandwidth before the spread spectrum and the same frequency bandwidth after the spread spectrum, and therefore gain obtained by performing the spread spectrum, That is, the processing gain is 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., an information signal to be transmitted must be transmitted. It is necessary to perform spread spectrum processing with the highest processing gain. However, there is a limit to the usable frequency bandwidth, and there is a limit to increasing the processing gain of spread spectrum to improve communication quality.

On the other hand, the required quality including the bit error rate, symbol error rate, frame error rate and the like often differs depending on the type of information signal to be transmitted. In such a case, ignoring the difference in required quality of each information signal and uniformly applying the spread spectrum of the same processing gain, the processing gain is insufficient for a signal of high required quality,
For signals with low required quality, a situation occurs where the processing gain is excessive.

The present invention has been made in view of the circumstances described above, and has as its object 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-mentioned problems, according to the present invention, a spread spectrum is applied to a plurality of information signals at a radio transmitting station with a processing gain corresponding to each required quality.

That is, in the spread spectrum radio communication system according to the first aspect, the radio transmission station has a transmission speed that is not appropriate.
For high-quality information signals, the transmission speed is low.
For low-quality information signals, high transmission rates V ₁ , V ₂ ,
..., the different required quality is V _n (n is an integer of 2 or more)
With respect to the n information signals, V ₁ · K ₁ = V ₂ · K ₂ =...
.. = V _n · K _n , satisfying the condition of K ₁ , K ₂ ,.
Each of the spread spectrum n signals (SS ₁ ) is multiplied by each of the spreading codes having respective K _n (≠ 1).
ＳＳSS _n ) , combine these spread spectrum signals, and transmit them as radio signals in the same frequency band. Then, the radio receiving station performs spectrum despreading using the plurality of spread codes on the radio signal received from the radio transmitting station, and demodulates the result of the spectrum despreading.

Further, in the spread spectrum wireless communication system according to the second aspect, the wireless transmitting station has different required quality.
N pieces having (n is an integer of 2 or more) and a low transmission rate with high information signals required quality the transmission rate of the information signal, where
For information signals of low quality required, the high transmission speed V ₁ ,
V _2, ..., is converted to V _n, with respect to the converted n pieces of information signals of the transmission _{rate, V 1 · K 1 = V} 2 · K 2 = ...... = V
_The diffusion coefficients K ₁ , K ₂ ,..., K satisfying the condition of _n · K _n
n (≠ 1) is multiplied by each of the spreading codes to obtain n spread-spectrum signals (SS ₁ to SS ₁ ).
SS _n ) , combine these spread spectrum signals, and transmit them as radio signals in the same frequency band. Then, the radio receiving station performs spectrum despreading using the plurality of spread codes on the radio signal received from the radio transmitting station, and demodulates the result of the spectrum despreading.

In the spread spectrum radio communication system according to the third aspect, the radio transmitting station transmits an information signal to be transmitted at a low transmission rate for an information signal having a high required quality.
Speed, and high transmission rate for information signals of low required quality
V _1, V ₂ is, ..., n number is V _n (n is an integer of 2 or more) is divided into an information signal having a required quality of different, with respect to the respective divided information signals are differed from each other n kinds of spreading codes, V ₁ · K ₁ = V ₂ · K ₂ =... = V _n ·
Spreading factor K _1, K ₂ that satisfies K _n becomes conditions, ..., K _n (≠
N number of signals subjected to the spread spectrum by multiplying each of the respective spreading codes each having ₁₎ (SS 1 ~SS _n)
And each of these spread-spectrum n
These signals are combined, and the combined signals are transmitted as wireless signals in the same frequency band. The radio receiving station performs spectrum despreading on the radio signal received from the radio transmitting station with the n kinds of spreading codes, and demodulates n signals obtained as a result of these spectrum despreading, The n signals obtained by the demodulation are combined in the radio transmitting station according to a procedure reverse to a procedure of dividing the information signal into n information signals.

[0013]

According to the spread spectrum radio communication system of the first aspect, the transmission rate is low for an information signal having a high required quality.
Transmission speed, high transmission for information signals with low required quality
V _1, V ₂ is the speed, ..., with V _n (n is an integer of 2 or more)
For n information signals with different required qualities,
Information signal supplied to the wireless transmitting station at a transmission speed have spread spectrum is performed at a low expansion <br/> dispersion rate information signal supplied to the wireless transmitting station at a lower transmission rate spread spectrum with a high spreading factor Done. According to this spread spectrum wireless communication system, a processing gain proportional to the spreading factor applied to each information signal can be obtained. Also, the transmission speeds V _{1 to} V _n of the information signals and the spreading factors K _{1 to} K _n applied to the information signals.
(≠ 1) and V ₁ · K ₁ = V ₂ · K ₂ = ... = V _n · K _n
Holds, each signal subjected to spread spectrum can be transmitted in the same frequency band.

According to the spread spectrum wireless communication system of the present invention, the different required quality supplied to the wireless transmitting station is provided.
Information signals of n (n is an integer of 2 or more) having the low transmission speed in those high information signal transmission rate of the required quality of
At high transmission rates for information signals of low required quality.
The information signals are converted into certain V ₁ , V ₂ ,..., V _n , and each information signal is subjected to spectrum spreading at a spreading factor inversely proportional to each transmission rate. According to this spread spectrum wireless communication system,
A processing gain proportional to the spreading factor applied to each information signal is obtained. Also, the transmission speed of each information signal V _1-
V _n and spreading factors K _{1 to} K _n applied to each information signal (≠ 1)
Can transmit respective signals subjected to the spread spectrum in the same frequency band because _{V 1 · K 1 = V 2} · K 2 = ... = relationship V _n · K _n holds between the.

According to the spread spectrum wireless communication system according to claim 3, the information signal supplied to the wireless transmitting station, Den
For information signals whose transmission rate is high, the transmission rate is low.
For information signals of low required quality, V is a high transmission rate.
_1, V _2, ..., n number of different required quality is V _n
(N is an integer of 2 or more) , and each of the divided information signals is subjected to spectrum spreading at a spreading factor inversely proportional to its transmission 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, = V 1 · K 1 =} V 2 · K 2 between the transmission speed V ₁ ~V _n and spreading factor K ₁ ~K _n applied to each information signal of each information signal (≠ 1) ... =
Since the relationship of V _n · K _n holds, each signal subjected to spread spectrum can be transmitted in the same frequency band.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. (1) Configuration of Embodiment FIG. 1 is a diagram showing a configuration of a specific embodiment of the present invention.
In the figure, 1A is a wireless transmitting station, and 1B is a wireless receiving 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-
n is a spread spectrum circuit, 1-4 is a synthesis circuit, 1-5
Is a transmitter, and 1-6 is a transmitting antenna. In the radio receiving 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 demodulated signal.

<Configuration Example of Spread Spectrum Circuit> FIG. 2 shows a spread spectrum circuit 1-3-1 to -1 in this embodiment.
-3-n shows a specific configuration example. In the figure, 2-1
Is a multiplier, and 2-2 is a spreading code generator. The output of the signal dividing circuit 1-2 is input to the multiplier 2-1. The spreading code generator 2-2 generates a spreading code whose period is represented by Ki, and this spreading 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 the multiplication is output to the synthesis circuit 1-4.

<Configuration 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 the present embodiment. In this signal division processing,
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 irrespective of the amount of information (FIG. 3 (c)). Therefore, an information signal having a large amount of information among the divided information signals is output at a high transmission rate, and an information signal having a small amount of information is output at a low transmission rate. Signal dividing circuit 1-2 in this embodiment that each transmission speed information signal 1-1 is divided into a plurality of information signals S ₁ to S _n is V ₁ ~V _n By performing the aforementioned processing It is.

FIG. 4 shows a specific configuration example of a circuit for performing a signal dividing process. In the figure, 4-1 is a serial / parallel conversion circuit, and 4-2 is a synthesis circuit. Transmission speed of 3a (bp
The signal represented by s) is converted into a signal of 2a (bps) and a
(Bps). The information signal is input to the serial / parallel conversion circuit 4-1 and converted into three signals whose transmission speeds are represented by a (bps). Two of the three signals are input to the synthesis circuit 4-2. The signal is then combined with a signal whose transmission speed is represented by 2a (bps).

(2) Operation of the embodiment FIG. 5 shows the spectrum of the signal of each section of the radio transmitting station 1A. In FIG. 5, (a) shows the spread spectrum circuits 1-3-1 to 1-3-3. n input signals S _{1 to} S _n
And (b) shows a 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 FIG. 1 described above,
The operation of this embodiment will be described.

The information signal 1-1 has a transmission rate of V ₁ , V ₂ ,..., V according to the required quality by the signal dividing circuit 1-2.
is divided into n information signal S ₁ to S _n, represented by _n. These information signals S ₁ to S _n has a frequency band width corresponding to each transmission speed. In example FIG. 5 (a), the information signals S ₁ has been output at a low transmission rate, Accordingly frequency bandwidth becomes narrower. On the other hand, the information signal _Sn is output at a high transmission rate, and therefore has a wide frequency bandwidth.

The information signals S ₁ to S _n with wide and narrow Thus the frequency bandwidth, respectively, spread spectrum circuits 1-3
1 to 1-3-n. Then, each of the signals S _{1 to} S _n
In contrast, spread spectrum using different spreading codes is performed. However, for an information signal having a high transmission rate and a wide frequency bandwidth (for example, signal S _{n in} FIG. 5), a low spreading factor is used. Spread spectrum using codes is performed. On the other hand, an information signal having a low transmission rate and a narrow frequency bandwidth (for example, the signal S _{1 in} FIG. 5) is subjected to spectrum spreading using a spreading code having a high spreading factor. More precisely speaking, for each information signal S ₁ to S _n having a transmission rate V ₁ ~V _n, the condition V ₁ · K ₁ = V ₂
· K ₂ = ... = spreading code spectrum diffusion using the V _n · K _n satisfies the spreading factor K ₁ ~K _n is performed. As a result,
From each of the spread spectrum circuits 1-3-1 to 1-3-3-n,
Spectrum spread signal SS1～SS _n is obtained in one and the same frequency bandwidth.

Further, paying attention to the transmission speed, the transmission rate of the spread spectrum signal SS ₁ ~ SS _n is applied to the transmission speed V ₁ ~V _n and each of the previous signal S ₁ to S _n to be spread expressed as the product of spreading factor K ₁ ~K _n. Therefore, the transmission rate of the signal SS _i after the spread spectrum is V _i · K _i
Where V ₁ · K ₁ = V ₂ · K ₂ =... = V _n · K _n , so that n spread spectrum circuits 1-3-1 to 1-3 are provided.
Transmission rate of the output signal SS ₁ ~ SS _n of -n are all equal.

The thus obtained n spread spectrum signals SS _{1 to} SS _n are combined by a combining circuit 1-4 and then supplied to a transmitter 1-5 to be transmitted to a transmitting antenna 1-6. Are transmitted as wireless signals in the same frequency band.

In the radio receiving station 1B, the received signal is input to n despreading circuits 1-8-1 to 1-8-n.
In these despreading circuits, despreading is performed with the same spreading code as that of the radio transmitting station 1A, and the resulting n output signals are input to demodulation circuits 1-10-1 to 1-10-n, respectively. Each output signal of the demodulation circuits 1-10-1 to 1-10-n is input to a signal combining circuit 1-11, where the signal is divided by the signal dividing circuit 1-2. 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 information signal to be transmitted is received by the radio transmitting station and divided into a plurality of information signals has been described above. However, the scope of the present invention is not limited to this. Instead, for example, the following modifications are also possible.

Instead of dividing the information signal into a plurality of pieces after the wireless transmitting station receives the information signal, the wireless transmitting station receives the plurality of information signals as they are. At this time, an information signal having a high required quality is received at a low transmission rate, and the information signal is subjected to spectrum spreading 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 spectrum spreading using a spreading code having a low spreading factor inversely proportional to the transmission rate. As described above, signals of the same frequency band subjected to spread spectrum with a processing gain corresponding to the required quality of each information signal are obtained, then combined and transmitted. This is the same as the above embodiment in that the wireless receiving station uses the same spreading code used in the wireless transmitting station.

The radio transmitting 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 division, an information signal having a high required quality is converted into a low transmission rate, and a high spreading factor is inversely proportional to the transmission rate for 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 spectrum spreading using a spreading code having a low spreading factor inversely proportional to the transmission rate. As described above, signals of the same frequency band subjected to spread spectrum with a processing gain corresponding to the required quality of each information signal are obtained, then combined and transmitted. This is the same as the above embodiment in that the wireless receiving station uses the same spreading code used in the wireless transmitting station.

In the above embodiment, an example has been described in which the spread spectrum circuit and the inverse spread spectrum circuit are configured in the baseband band. However, the same effect can be obtained in a circuit in the intermediate frequency band.

[0030]

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

[Brief description of the 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 illustrating an example of a spread spectrum circuit according to the embodiment.

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

FIG. 4 is a diagram illustrating a configuration example of a signal dividing circuit according to the embodiment.

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

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

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

[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 synthesis circuit,
1-12: Demodulated signal.

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

Claims (3)

(57) [Claims] 1. A radio transmitting station transmits an information signal having a high required quality at a low transmission rate.
There, V _1, V ₂ is a high transmission rate with low required quality information signal, ..., V _{n (n} is an integer of 2 or more) different are
For n pieces of information signals having the required _{quality, V 1 · K 1 = V} 2 · K 2 = ...... = V n · K n spreading factor K ₁ which satisfies the condition _{that, K 2, ..., K n} ( ≠ 1)
Are respectively multiplied by the respective spreading codes to generate n spread-spectrum signals (SS _{1 to} SS _n ), and combine these spread-spectrum signals to obtain radio signals in the same frequency band. Transmitting, the radio receiving station performs spectrum despreading on the radio signal received from the radio transmission station using the plurality of spreading codes,
A spread-spectrum wireless communication system characterized by demodulating the results of these spectrum despreading. 2. A radio transmission station according to claim 1, wherein the transmission rate of n (n is an integer of 2 or more) information signals having different required qualities is reduced by an information signal having a high required quality.
Transmission speed, high transmission speed for information signals with low required quality
Whenever a is V _1, V _2, ..., is converted to V _n, with respect to the converted n pieces of information signals of the transmission _{rate, V 1 · K 1 = V} 2 · K 2 = ...... = V n · K _n spreading factor satisfies the condition that _{K 1, K 2, ...,} K n (≠ 1)
Are respectively multiplied by the respective spreading codes to generate n spread-spectrum signals (SS _{1 to} SS _n ), and combine these spread-spectrum signals to obtain radio signals in the same frequency band. Transmitting, the radio receiving station performs spectrum despreading on the radio signal received from the radio transmission station using the plurality of spreading codes,
A spread-spectrum wireless communication system characterized by demodulating the results of these spectrum despreading. 3. A radio transmission station, the information signal to be transmitted, a high transmission rate is the required quality information
Information signals with low transmission rates and low required quality
In V _1, V ₂ is a high transmission rate, ..., different is V _n
(N is an integer of 2 or more) having a required quality, and each of the divided information signals is composed of n different spreading codes, V ₁ · K _{1 = V 2 · K 2 = ......} = V n · K n diffusion rate K ₁ to satisfy the condition _{that, K 2, ..., K n} (≠ 1)
Are respectively multiplied by the respective spreading codes to generate n spread-spectrum signals (SS _{1 to} SS _n ) , and these n spread-spectrum signals are combined. The radio receiving station performs spectrum despreading with respect to the radio signal received from the radio transmitting station using the n kinds of spreading codes, respectively. Demodulating the n signals obtained as a result, and synthesizing the n signals obtained by the demodulation according to a procedure reverse to a procedure of dividing the information signal into n information signals in the radio transmitting station. Characteristic spread spectrum wireless communication system.