JPH0548569A - Spread spectrum communicatoin equipment - Google Patents

Abstract

PURPOSE:To reduce the interference due to narrow band disturbance and multipass phasing in a SS communication equipment. CONSTITUTION:In a SS transmitter, a PN code generator 1 and a mixer 3 execute spectrum-spreading of information data, and a wave shaping section 2 makes spectrum flat, then the data is transmitted. In a SS receiver, distributor 10 distributes a SS receiving signal to n+1 and BPF 11 divides the SS receiving signal to n bands. Distributed remaining signals are weighted by weighting section 12 to obtain n weight signals. The level of each BPF output is controlled by a control signal corresponding to the difference between a weighted signal and each BPF signal, signals treated for their respective level controls are synthesized by synthesizer 15, and the synthesized signals are restored to the SS signal by the wave shaping section 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a spread spectrum communication device for reducing narrow band interference and multipath fading.

[0002]

2. Description of the Related Art As a conventional narrow-band interference detecting and removing apparatus in spread spectrum communication (SS communication), there is, for example, Japanese Patent Laid-Open No. 3-92029. This device is SS
The upper band and the lower band of the spectrum of the signal are compared to remove the band with the higher level. For example, as shown in FIG. 11, if narrow band interference is present in the upper band, the lower band is detected. Since the level of the upper band is higher than that of, narrowband interference can be detected and removed.

[0003]

However, generally, only narrow band interference waves do not exist in an actual wireless communication channel, and multipath fading and wide band noise also exist.
For example, when multipath fading is present, the SS signal spectrum fluctuates as shown in FIG. 12, and in the above-mentioned device that only compares the levels of the upper band and the lower band, narrow band interference and multipath interference occur. Fading cannot be distinguished and the SS signal is erroneously removed.
There is a drawback that deteriorates the N ratio.

It is an object of the present invention to provide a spread spectrum communication device that reduces narrow band interference and interference due to multipath fading in a wireless communication path.

[0005]

In order to achieve the above object, a spread spectrum communication apparatus of the present invention spreads information data on the basis of a PN code from a PN code generator to generate a main lobe SS signal. A spectrum spreading means, and a waveform shaping means for flattening the SS signal of the main lobe, and a distributor for distributing the received signal to n + 1 (n is an integer of 2 or more),
N band-pass filters that divide the distributed n signals into bands of different center frequencies, and the remaining distributed signals are divided into n units so that each of them becomes α / n with respect to this signal level α. A weighting unit for dividing, n level control units for controlling the output level of each of the band pass filters based on a control signal, and a level of the output signal of the weighting unit and the output signal of each band. A level difference determination unit that compares and outputs n control signals according to the level difference to each of the level control units, a combining unit that combines the level-controlled signals, and a signal from the combining unit in the main lobe. SS
The gist of the present invention is to include a receiver including a waveform shaping unit that restores a signal.

[0006]

The level of the SS received signal whose spectrum is flattened at the transmitting side is weighted, and the level of the weighted reference signal is divided into N by a bandpass filter (BPF) having a different center frequency to obtain a spread spectrum (SS) signal. The levels are controlled so that they are equal.

[0007]

Embodiments of the present invention shown in the drawings will be described below.
1 and 3 respectively show an embodiment of a transmitter and a receiver of a spread spectrum communication device of the present invention.

The transmitter shown in FIG. 1 has a PN code generator 1, a waveform shaping section 2, mixers 3, 4, a local oscillator 5, and an antenna 6.
The operation will be described below. Information data by the mixer 3 and P output from the PN code generator 1
The waveform shaping section 2 performs multiplication with an N code (referred to as an SS signal), and performs waveform shaping of an SS signal having a main lobe bandwidth B having a (sinX / X) ² type spectrum with power (POWER), As shown in FIG. 2, the spectrum of the main lobe is flattened.

The baseband SS signal with the flattened spectrum is multiplied by the carrier fc generated by the local oscillator 5 by the mixer 4 and transmitted from the antenna 6.

Next, the receiver of FIG. 3 has an antenna 7, a bandpass filter (BPF), an amplifier 9, a distributor 10, and a BP.
F11-1 to 11-n, weighting unit 12, level difference determination unit 13, attenuator units 14-1 to 14-n, combining unit 1
5 and the waveform shaping section 16, each section performs the following operation.

First, an SS signal whose spectrum is flattened with the main lobe bandwidth 2B as shown in FIG. 4A is received from the antenna 7, and only the main lobe of the SS signal is passed by the BPF 8 and then the amplifier is received. Amplification is performed according to 9.

The distributor 10 divides the received SS signal into A
It is distributed to n + 1 pieces of 1 ′ to An ′ and A0. here,
The levels of the outputs A1 'to An' and A0 of the distributor 10 are made equal to each other. BPFs 11-1 to 11-n are
As shown in FIG. 4-2, the distributed SS signals are divided into n frequency bands having different center frequencies (center frequencies f1 to fn).
Make a split.

The weighting section 12 outputs the SS output from the distributor 10.
The level of the signal A0 is weighted and divided into n. Here, the level of each of the n-divided SS signals B1 to Bn is set to be α / n with respect to the level α of the SS signal before input to the weighting unit 12.

The level determination unit 13 is configured to include BPFs 11-1 to 11-1.
The control signal C1 to the attenuator units 14-1 to 14-n is detected by detecting the level difference between the levels of the SS signals A1 to An output from the 1-n and the 12 outputs of the weighting unit.
To Cn are determined, and the attenuator units 14-1 to 14-n are BPFs 11-1 to 11-n according to the control signals C1 to Cn.
Of the SS signals A1 to An output from the weighting unit 12, the levels of the SS signals B1 to Bn output from the weighting unit 12, and the SS signals D1 to D output from the attenuators 14-1 to 14-n.
The n levels are controlled to be equal. For example, for the level a of the SS signal B1 output from the weighting unit 12, B
If the level of the SS signal A1 output from the PF 11-1 changes from a1 to a2 as shown in FIG. 5, the level difference determination unit 13 outputs the control signal D1 as shown in FIG. As shown in FIG. 7, the unit 14-1 outputs the BPF output SS based on the control signal D1 of the level difference determination unit 13.
The attenuation amount of the signal A1 is varied to control the level of the SS signal B1 output from the weighting unit 12 and the level of the SS signal D1 output from the attenuator unit 14-1 to be equal.
Since the SS signals B1 to Bn output from the weighting unit 12 have the same signal level, the attenuator unit 14-1
The SS signals D1 to Dn output from 14 to 14-n have the same signal level. The level V ₁ of the control signal D1 at time t1 in FIGS. 5 to 7 is SS of the BPF 11-1 output.
It corresponds to the attenuation amount X ₁ of the signal A1.

The synthesizer 15 is an attenuator 14-1 to 14-1.
The 4-n output SS signals D1 to Dn are combined, and the waveform shaping unit 6 performs power shaping of an SS signal having a spectrum as shown in FIG. 8 into (sinX / X) ² type power. Restore the SS signal.

Next, the narrow band interference is actually used in the wireless communication path.
Described an operation example in the presence of harm and noise of uniform band.
Bell. From the antenna 7, α as shown in FIG.₁Belief
Signal with signal level and β₁Narrow band with signal level of
Zone interference and γ₁Received uniform band noise with signal level of
To be done. Here, if the number of divisions n = 8, the BPF 11-1
8 different center frequencies (center frequency
(Number f1 to fn) is divided into frequency bands, and BPF 11-1
~ Outputs A1 to A8 of BPF11-8 are SS signal, narrow band
Band interference and noise with uniform band are as shown in Figure 9-2.
The signal level of A3 is ((α₁+ Γ₁) / 8) + β₁  And the other signal levels are (α₁+ Γ₁) / 8.

The SS signals D1 to D8 output from the attenuator units 14-1 to 14-8 are output by the level difference determination unit 13.
The signal levels of the SS signals B1 to B8 output from the weighting unit 12 and the signal levels of the SS signals D1 to D8 output from the attenuator units 14-1 to 14-8 are controlled to be equal to each other, and Since the signal levels of the SS signals B1 to B8 are equal to each other, the signal levels are equal to each other as shown in FIG. 7C, which is (α ₁ + β ₁ + γ ₁ ) / 8.

The synthesizer 15 is an attenuator 14-1 to 14-1.
The signals D1 to D8 of the output of 4-8 are combined to adjust the waveform.
The shaping unit 16 shapes the waveform of the spectrum, and
In power as shown (sinX / X)²Type of spectrum signal
Restore. Where β₁Narrowband interference with signal level of
In the output D3 of the attenuator unit 14-3, the harm is (α₁+ Β₁+ Γ₁) / 8β₁  Therefore, the interference of narrow band interference can be reduced.

Next, the case where narrow band interference, band-uniform noise, and multipath fading are present in the wireless communication channel will be described. From the antenna 7, an SS signal having a signal level of α ₂ subjected to multipath fading as shown in FIG. 10A, a narrow band interference having a signal level of β _{2 and} a band uniform having a signal level of γ ₂ Noise is received.
Here, if the number of divisions n = 8, BPFs 11-1 to 11-
8 have different center frequencies (center frequencies f1 to f1).
fn) divided into frequency bands, and BPFs 11-1 to 11-
The outputs A1 to A8 of FIG. 8 show multipath fading SS signals, narrow band interference, and band uniform noise as shown in FIG.
As shown in.

The SS signals D1 to D8 output from the attenuators 14-1 to 14-8 are output by the level difference determination unit 13.
The signal levels of the SS signals B1 to B8 output from the weighting unit 12 and the signal levels of the SS signals D1 to D8 output from the attenuator units 14-1 to 14-8 are controlled to be equal to each other, and Since the signal levels of the SS signals B1 to B8 are equal to each other, the signal levels are equal to each other as shown in FIG. 10C, which is (α ₂ + β ₂ + γ ₂ ) / 8.

The synthesizer 15 is an attenuator 14-1 to 14-1.
4-8 output SS signals D1 to D8 are combined,
The shape shaping unit 16 performs the waveform shaping of the spectrum, as shown in FIG.
-4 in power (sinX / X)²Mold spectrum
To recover the signal with. Where β₂Signal level of
The narrow band interference that is caused is S of the output of the attenuator unit 14-3.
In the S signal D3, (α₂+ Β₂+ Γ₂) / 8β₂  Is suppressed by the waveform shaping section, and the power (sinX /
X)²To recover the signal with the
Reduces interference due to band interference and multipath fading
it can.

[0022]

As described above, according to the present invention,
In a spread spectrum communication device, it is possible to reduce interference due to narrow band interference and multipath fading.

[Brief description of drawings]

FIG. 1 is a block diagram showing a transmitter according to an embodiment of the present invention.

FIG. 2 is an operation explanatory diagram of the transmitter.

FIG. 3 is a block diagram showing a receiver according to an embodiment of the present invention.

FIG. 4 is an explanatory diagram of band division by BPF in the receiver.

FIG. 5 is a diagram showing a level change of the SS signal of the BPF.

FIG. 6 is a diagram showing a change in a control signal in the receiver.

FIG. 7 is a diagram showing changes in the amount of attenuation of the SS signal output from the BPF.

FIG. 8 is an explanatory diagram of waveform shaping in the receiver.

FIG. 9 is an operation explanatory diagram of the receiver.

FIG. 10 is an operation explanatory diagram of the receiver.

FIG. 11 is an explanatory diagram of detection and removal of narrowband interference in conventional SS communication.

FIG. 12 is a diagram showing a spectrum variation of an SS signal due to multipath fading.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 PN code generator 2 Waveform shaping section 10 Divider 11 BPF 12 Weighting section 13 Level difference determination section 14 Attenuator 15 Combining section 16 Waveform shaping section

Claims (1)

[Claims] 1. Information data from a PN code generator to a PN
Spread spectrum based on code, S of main lobe
A transmitter equipped with a spread spectrum means for generating an S signal and a waveform shaping means for flattening the SS signal of the main lobe, and a distributor for distributing the received signal into n + 1 (n is an integer of 2 or more) , N band-pass filters that divide each of the distributed n signals into bands with different center frequencies, and n of the remaining distributed signals to α / n for each signal level α. A weighting unit that divides the output signal of each band pass filter into n level control units that control the output level of each band pass filter based on a control signal, and the level of the output signal of the weighting unit and the output signal of each band. And a level difference determination unit that outputs n control signals corresponding to the level difference to each of the level control units, a combining unit that combines the level-controlled signals, and a signal from the combining unit. Spread spectrum communication device comprising a waveform shaping unit for restoring the SS signal over blanking the receiver with a, that more made.