JPH03133224A - Same radio channel interference preventing method for travelling object communication - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for preventing interference in a wireless communication channel in mobile communication. More specifically, a certain wireless channel is given, and one of the many mobile wireless devices in a service area made up of multiple small zones uses this to connect to the opposing wireless base station and the wireless line. If another mobile radio in a different location starts communicating with another radio base station using the same radio channel while communicating with the For this reason, the present invention relates to a method that makes it possible to eliminate adverse effects on communication between mobile radios and a radio base station that are in communication, respectively.

[Prior art] In mobile communications using the small zone system, the same radio channel is used in different locations to prevent mutual interference, but in order to make effective use of frequencies, Systems are designed on the premise that mutual interference will occur with a statistically constant probability, as it is impossible to move the devices far enough away to prevent the occurrence of mutual interference.

In the above-mentioned system, the majority of users can receive call services without mutual interference, but some users may be forced to make uncomfortable calls due to interference. become.

As a measure to reduce mutual interference without reducing the effective utilization rate of frequencies, there is a method called interleaving, in which a new carrier frequency is set between two carrier frequencies and a new channel is installed. This has the disadvantage that the characteristics of the filter must be improved and the synthesizer circuit must be upgraded, making the hardware design conditions stricter.

Also, conventional fixed microwave FD using analog FM modulation
In M (frequency division multiplexing) lines, measures have been taken to reduce interference using a spreading oscillator as described below. In microwave relays, etc., there are cases where a so-called two-frequency system is used, and in this case, the same up and down transmission and reception frequencies of a certain relay station are assigned, so co-channel interference may occur. Must be careful.

Both desired waves (i.e. radio waves used for own communication and which one wishes to receive) and interference waves (i.e. radio waves used for third party communication using the same radio channel and which interfere with one's own communication) are unmodulated. When , the energy of the interference output is the difference frequency F of both signals (mainly of the carrier wave). and its harmonics, but if only one of them is modulated, the energy will be dispersed over many spectra. This phenomenon is detailed in the following literature.

Edited by Kanhara "FM Radio Engineering" Published by Nikkan Kogyo Shimbun, 1950, pp. 392-468 Therefore, in the case of FDM-FM multiplex telephone relay, the interference output appearing in the FM detector output corresponds to a certain communication path. Only the specific frequency spectrum that causes interference in the communication path becomes the output. In this case, if a spreading oscillator as described below is used, the radio carrier wave will be spread, and the interference power located at a particular frequency will be reduced, and the interference will be reduced.

Although the influence of interference is greatest when there is no call, it is also possible to modulate the radio carrier wave at this time to spread the spectrum and reduce the noise.

For example, on a 480 toll line, the multiplex telephone signal is 60
It has a baseband of ~2044kHz, and O~6
Since 0kHz is not used, the modulation frequency for spreading can be set here.

An example of oscillator connections for spreading is shown in FIG.

Since SS-FM multiplex telephone signals are normally arranged every 4kHz, the transmission frequency of the spread oscillator 94 is set to 4kHz.
If H2 is selected, one spread spectrum is allocated to each channel. It is better to make the modulation index mf large so that the signal is spread over as many channels as possible. Even if m( is increased, the modulation frequency is 4 kHz, so the frequency deviation will not become that large. If mj-10, the effective value of the frequency deviation is 40X 2"2 = 28 kHz (
rms) and test sound level 200kHz (rms
), it has almost no effect on the frequency shift (approximately 900 kHz rms) of the multiplex telephone signal (4800H), and it can be said that quasi-crosstalk due to distortion does not increase.

Practically speaking, it is known that in the conventional example described above, the improvement effect of the spread oscillator is about 10 dB 1q.

[Problems to be Solved by the Invention] In various mobile communications using the conventional small zone system, it has not been possible to sufficiently reduce interference within the same radio channel. An object of the present invention is to provide a method that can significantly reduce the probability of occurrence of interference if the same radio channel is used at the same distance as in the prior art.

[Means for solving the problem] When angle modulation is used as a modulation method, the output of a spreading oscillator having a signal frequency component different from the audio frequency band is added to a communication signal such as voice to generate an angle-modulated signal. The modulated wave is transmitted to the other party's radio device that is communicating with the other party, and the other party's radio device that receives it demodulates the received wave and removes the frequency component of the output of the spread oscillator from the demodulated signal. Only communication signals sent from the transmitting side, such as audio, are played back.

Note that the reason why the output of the above-mentioned spreading oscillator is added as the modulator input is that it can play a large role in reducing or eliminating co-channel interference.

[Operation] By superimposing the output of the spread oscillator with the communication signal, angle-modulating the carrier wave, and sending it out into space, the frequency spectrum of the radio signal wave propagating in space, which is the transmission medium, can be Compared to a signal wave, the signal power is spread, that is, the frequency components of the signal power are made uniform and wideband, and the signal power of a specific frequency component is not particularly large. A radio signal wave having such a frequency spectrum has an extremely small amount of interference to a third party communicating using the same radio channel. Therefore, even in cases where the signal of one telephone channel is a communication signal, such as in mobile communication, it is extremely effective as a countermeasure against interference.

[Embodiment] FIG. 1A, FIG. 1B-1, and FIG. 1C show a system configuration for explaining an embodiment of the present invention.

In FIG. 1A, 10 is a general telephone network, and 20 is a gateway exchange for connecting the telephone network 10 and a wireless system. 30 is a wireless base station and a barrier exchange 112
0, a circuit that converts the signal speed, a circuit that allocates and selects time slots, a control unit, etc.
100 (100-1 to 100-n>) and has a wireless transmitting/receiving circuit that transmits and receives wireless signals.

Here, between the barrier switch 20 and the wireless base station 30,
There are transmission lines for transmitting communication signals 22-1 to 22-n including communication signals of communication channels CH1 to CHn and control signals.

FIG. 1B-1 shows a circuit configuration of a mobile radio device 100 that communicates with a radio base station 30. Received signals such as control signals and call signals received by the antenna section enter a radio receiving circuit 135 that includes a receiving mixer 136 and a receiving section 137, and the communication signal that is the output thereof is sent to a speed recovery circuit 138.
is input to the control section 140 and clock regenerator 141. The clock regenerator 141 regenerates a clock from the received signal and sends it to the speed restoration circuit 138 and the control unit 1.
40 and a timing generator 142.

The speed recovery circuit 138 calculates the speed (pitch in the case of an analog signal) of the compressed and segmented communication signal in the received signal.
is restored and input as a continuous signal to the telephone section 101 and the control section 1-40.

The communication signal output from the telephone unit 101 is divided into predetermined time intervals by a speed conversion circuit 131, and the speed (pitch in the case of an analog signal) is made high (compressed) and sent to a transmission mixer 133. The signal is applied to the wireless transmission circuit 132 including the section 134.

FIG. 1B-2 shows the internal configuration of the wireless transmission circuit 132. What should be noted here is the presence of the spread oscillator 154. This oscillator output is mixed with the above-mentioned compressed audio output (output of the speed conversion circuit 131) in a mixer 155,
applied to modulator 153. The output of the modulator 153 is converted to a predetermined radio frequency in the transmission mixer 133,
The signal is transmitted from the antenna section and received by the wireless base station 30. In order to send a radio signal from the mobile radio device 100 to the radio base station 30 using a time slot that is permitted to be used, a timing generator 1 shown in FIG. 1B-1 is used.
This case also assumes that the timing information from 42 is obtained via the control unit 140.

1B-2, switch 122 of FIG. 1B-1
-2 is the point R2 between the modulator 153 and the transmission mixer 133
A point Q between the transmission mixer 133 and the high frequency amplifier 159,
It can be installed at any point P on the output side of the high frequency amplifier 159, and its operation is controlled by the transmission/reception intermittent controller 123.

Using the time slot given by this control,
It becomes possible to transmit the signal to the wireless base station 30.

Although the high frequency amplifier 159 is not provided in FIG. 1B-1, it is a circuit used when it is desired to increase the wireless transmission output.

In this timing generator 142, the clock regenerator 14
1 and a control signal from the control section 140, the transmission/reception intermittent controller 123. It supplies necessary timing to the speed conversion circuit 131 and speed restoration circuit 138.

This mobile radio device 100 further includes a synthesizer 121.
-1 and 121-2, and selector switches 122-1, 1
22-2, a transmission/reception intermittent controller 123 and a timing generator 142 that generate signals for switching the changeover switches 122-1 and 122-2, respectively.
Synthesizers 121 - 1 and 121 - 2 , transmission/reception intermittent controller 123 , and timing generator 142 are controlled by control section 140 . Each synthesizer 121-1.1
21-2 is supplied with a reference frequency from a reference crystal oscillator 120.

FIG. 1B-3 shows another mobile radio 1fi related to the present invention.
The circuit configuration of 100B is shown. The difference between the figure and FIG. 1B-1 is that the switches 122-1 and 122-2 are included inside the wireless transmitting circuit 132 and the wireless receiving circuit 135, and the outputs of the synthesizers 121-1 and 121-2 are directly connected to each other. This is added to the receive or transmit mixers 136 and 133. However, the transmission/reception intermittent controller 123 is provided and still controls the transmitter 134.

FIG. 1B-4 shows the wireless receiving circuit 135 of FIG. 1B-3.
The detailed configuration is shown. High frequency amplifier 1 shown in the figure
49 is provided in front of the receiving mixer 136, and is used when it is desired to lower the noise figure of the receiving section. The output of intermediate frequency amplifier 143 is input to discriminator 145 and demodulated. This output is input to the switch 122-1 and the mobile radio 1
The switch 122-1 is turned on only when a signal in the time slot assigned to 00B arrives, and is turned off for the rest of the time, so that only the desired signal is sent to the high frequency amplifier 149. Receive mixer 136. Intermediate frequency amplifier 143. Discriminator 145. Low frequency filter (high pass filter) 1
47 to the speed restoration circuit 138.

Here, the switch circuit 122-1 may be installed at the point M on the input side of the reception mixer 136 to perform the same operation.

A wireless base station 30 is shown in FIG. 1C.

N-channel communication between gateway exchange 20@22-1
22-n are connected to a signal processing unit 31 forming an interface through a transmission line.

Now, the communication signal 22- sent from the barrier exchange m20
1 to 22-n are input to the signal processing unit 31 of the wireless base station 30. The signal processing section 31 is equipped with an amplifier for compensating for transmission loss, and also performs so-called 2-wire to 4-wire conversion. That is, the input signal and the output signal are mixed and separated, and the input signal from the barrier switch 20 is sent to the signal speed conversion circuit group 51. Also, signal speed restoration circuit group 3
The output signal from 8 is transmitted to the barrier exchange 1N20 by the signal processing unit 31 using the same transmission path as the input signal. Among the above, the input signal from the barrier switch 20 is input to the signal speed conversion circuit group 51 including many signal speed conversion circuits 51-1 to 51-n, and is subjected to speed (pitch) conversion at predetermined time intervals. .

Furthermore, the signal transmitted from the radio base station 30 to the gateway exchange 20 is determined by the output of the radio receiving circuit 35 being transmitted to the signal selection circuit group 39.
is input to the signal speed restoration circuit group 38 via the signal speed (
pitch) is converted and input to the signal processing section 31.

Now, the control of the radio reception circuit 35 or the output of the call signal is performed by a signal selection circuit 39 that selects a signal for each time slot.
-1 to 39-n is input to the signal selection circuit group 39,
Here, speech signals are separated corresponding to each speech channel CH1 to CHn. This output undergoes signal speed (pitch) restoration in a signal speed restoration circuit group 38 including signal speed restoration circuits 38-1 to 38-n provided for each channel, and then is input to the signal processing section 31. , after undergoing 4-wire to 2-wire conversion, this output is sent to the barrier switch 20 as communication signals 22-1 to 22-2.
2-n.

Next, the functions of the signal speed conversion circuit group 51 will be explained.

By storing input signals such as audio signals and control signals divided into a certain length of time in a storage circuit, and changing the speed when reading them out, for example, reading them out at a speed 15 times faster than when they were stored, the signal can be read out. It becomes possible to compress the time length. The principle of the signal speed conversion circuit group 51 is the same as when playing back audio recorded by a tape recorder at high speed.
geCoupled Device > , BBD
(Bucket Brigade Device) can be used, and the memory used in television receivers and tape recorders that compress or expand the time axis of conversations can be used (References: Koita et al.
“A tape recorder that compresses/expands the time axis of conversations” Nikkei Electronics July 26, 1976 92-1
page 33).

The circuit using COD or BBD exemplified in the signal speed conversion circuit group 51 can be used as it is in the signal speed restoration circuit group 38 as described in the above-mentioned literature. This can be achieved by making the reading speed slower than the writing speed by receiving a timing signal from a timing generator 42 that generates timing based on the clock and a control signal from the control unit 40.

The control or audio signals outputted from the barrier switch 20 via the signal processing unit 31 are input to the signal speed conversion circuit group 51, and after speed (pitch) conversion processing is performed, signals are assigned to each time slot. It is applied to the signal allocation circuit group 52. The signal allocation circuit group 52 is a buffer memory circuit that stores one section of high-speed signals output from the signal speed conversion circuit group 51, and receives timing information from the timing generation circuit 42 given by instructions from the control section 40. Then, the signal in the buffer memory is read out and transmitted to the wireless transmission circuit 32. As a result, when viewed in terms of channel correspondence, communication signals are arranged in series without overlapping in chronological order, and when all control signals or communication signals, which will be described later, are implemented, they appear as if they were continuous signal waves. become.

The state of this compressed signal is shown and explained in FIGS. 2A and 2B.

The output signal of the signal speed conversion circuit group 51 is sent to the signal assignment circuit group 5.
2 and are given time slots in a predetermined order. SDI in Figure 2A(a), 802
-, SDn indicate that the speed-converted communication signals are allocated to each time slot.

Here, one time slot accommodates a synchronization signal and a control signal or a call signal as shown in the figure. If the call signal is not implemented, only the synchronization signal is added and the empty slot signal is added to the call signal portion. In this way, as shown in FIG. 2A(a), the wireless transmitting circuit 32
In this case, signals forming one frame in time slots SDI to SDn are applied to the modulation circuit.

Note that, as explained in the circuit configuration of the mobile radio device 100,
Also in the wireless transmission circuit 32 of the wireless base station 30, the first B
In some cases, a spreading oscillator as shown in Figure 2 is added to spread the modulated signal. In the radio reception circuit 135 of the mobile radio device 100 that receives this, a low frequency filter (high pass filter) 147 is inserted at the output of the discriminator 145 as shown in FIG. 1B-4, and Separation of the frequency components from the 30 spreading oscillators from the received signal components is performed.

The time-series multiplexed signal to be transmitted is angularly modulated in the radio transmission circuit 32, and then sent out into space from the antenna section.

When making or receiving a telephone call, the wireless base station 30
Regarding the transmission of control signals between the mobile radio device 100 and the mobile radio device 100, it is possible to use either in-band or out-of-band telephone signals.

Figure 3A shows these frequency relationships. That is, the same (a
) is an example of an out-of-band signal, and as shown in the figure, the low frequency side (250Hz) or the high frequency side (3850Hz>) can be used.This signal can be used, for example, when you want to send a control signal during a call. be done.

FIG. 3A (b) shows an example of an in-band signal, which is used when making and receiving calls.

Although the above examples were all tone signals, it is possible to transmit many types of signals at high speed by increasing the number of tone signals or by modulating the tone and making it into a subcarrier signal.

The above was a case of analog signals, but if a digital data signal is used as a control signal, it is also possible to digitally encode the audio signal and time-division multiplex the two to transmit. The circuit configuration of is shown in FIG. 3C. FIG. 3C shows an audio signal digital encoding circuit 9.
This is an example of a case in which the data signal is digitized at 1, multiplexed with a data signal by a multiplex conversion circuit 92, and applied to a modulation circuit included in the wireless transmission circuit 32.

Then, it is received by the opposite receiver, and the 3rd C
By performing the operation opposite to that shown in the figure, it is possible to extract the audio signal and the control signal separately.

On the other hand, the signal sent from the mobile radio device 100 is received by the antenna section of the radio base station 30 and input to the radio reception circuit 35. FIG. 2A (b) schematically shows this upstream input signal.

That is, time slot SU1. SU2. ...s
un tit, mobile radio va100-1,100-
2° . . . shows a transmission signal addressed to the wireless base station 30 from 100-n. Also, each time slot su't, su2
,..., sun is shown in detail in Figure 2A (b
), it consists of a synchronization signal and a control signal or call signal. However, depending on the short distance between the radio base station 30 and the mobile radio 111100 or the signal speed, it is possible to omit the synchronization signal. Roughly speaking, the time and time of the radio carrier wave of the above uplink radio signal are
Fig. 2B (C) schematically shows the waveform in the slot.
It becomes like this.

Now, among the input signals that have arrived at the wireless base station 30, the control signal is immediately sent to the control unit 40 from the wireless receiving circuit 35.
added to. However, depending on the size of the speed conversion rate, it is also possible to apply the output of the signal speed restoration circuit group 38 to the control unit 40 after the call signal has been subjected to similar processing. Further, the call signal is applied to the signal selection circuit group 39.

A timing signal from a timing generation circuit 42 that generates a predetermined timing is applied to the signal selection circuit group 39 according to a control signal instruction from the control unit 40, and a synchronization signal and a control signal are generated for each time slot SU1 to Sun. The signal or speech signal is separated and output. Each of these signals is input to a signal speed restoration circuit group 38. This circuit is a speed conversion circuit 131 (first
It has a function to perform the inverse conversion of the method shown in Figure B-1), thereby faithfully reproducing the original signal and transmitting it to the gateway exchange 120.

The manner in which signals are transmitted in the signal space according to the present invention will be explained below using the required transmission band and the relationship between this and adjacent wireless channels.

As shown in FIG. 1C, the control signal from the control section 40 is applied to the wireless transmission circuit 32 in parallel with the output of the signal allocation circuit group 52. However, depending on the size of the speed conversion rate, it is also possible to perform the same processing as the call signal and then add it to the wireless transmission circuit 32 from the output of the signal allocation circuit group 52.

Next, as shown in FIG. 1B-1, the mobile radio device 100 also has a circuit configuration required when the radio base station 30 has one communication channel among its functions. Original signal, for example, audio signal (0.3KH2~3.0KHz
) passes through the signal speed conversion circuit group 51 (Figure 1C), the frequency distribution on the output side is shown in Figure 3B. In other words, if the audio signal is converted 15 times as much as described above, then For example, the frequency distribution of the signal is as shown in Figure 3B < 4
．． This means that it is expanded by +-12 from 5KHz to 45KHz. The figure shows a case where the control signals are simultaneously transmitted using the lower frequency band of the audio signal. Of these signals, the control signal (0.2 to 4.0 KH2), the output of the diffusion excavator (for example 50 to 100 H2) and the speech signal CHI (expressed as SDl at 4.5 to 45 KH2) are the time signals. Assume that it is accommodated in a slot, for example SDl. Other time slots SD2~
The same applies to the audio signals accommodated in SDn.

That is, time slot so+ <r=2°3,
・, n> accommodates the control unit @ (0,2~4.0KHz>) and the communication signal CHi (4,5~45KH2>. However, the signals within each time slot are arranged in chronological order. Therefore, signals in more than one time slot at a time are never applied to the wireless transmitter circuit 32 at the same time.

These call signals are sent to the wireless transmission circuit 32 along with control signals.
When added to the angle modulator included in the angular modulator, the required transmission band requires at least fo±45KH2. However, f is the radio carrier frequency. If there are a plurality of wireless channels given to the system, the speed-up of the signal by the signal speed conversion circuit group 51 is limited to a certain value due to the limitations on these frequency intervals. The frequency interval of multiple wireless channels is f
If rep is the maximum signal speed due to the above-mentioned speed increase of the audio signal, fo is the maximum signal speed, then an inequality must be established between the two.

f > 2 f H ep On the other hand, in digital signals, audio is usually digitized at a speed of about 64 kb/s, so read by raising the scale on the horizontal axis in Figure 3B, which explains the case of analog signals, by about one digit. Although necessary, the relationship in the above equation also holds true in this case.

Further, the control signal input from the mobile radio device 100 to the radio base station 30 is input to the radio reception circuit 35, but a part of the output is input to the control unit 40, and the other part is input to the signal selection circuit group 39. The signal is sent to the signal speed restoration circuit group 38 via the signal speed restoration circuit group 38. After the latter control signal undergoes a speed conversion (conversion to a low speed signal) that is completely opposite to that at the time of transmission, it becomes the same signal speed as that used in the general telephone network 10 and is transmitted via the signal processing section 31. It is sent to the barrier exchange 20.

Next, the call originating/receiving operation of the system according to the present invention will be explained by taking the case of a voice signal as an example.

(1) Call origination from mobile radio device 100 This will be explained using the flowcharts shown in FIGS. 4A and 4B.

When the mobile radio device 100 is powered on, the first
In the radio receiving circuit 135 in Fig. B-1, the downlink (radio base station 30→mobile radio device 100) radio channel (channel CH
Start capturing the control signal included in the control signal (denoted as I).

If the system is provided with more than one radio channel, i) the radio channel exhibiting the highest received input electric field; ii) the radio channel dictated by the control signal contained in the radio channel; and iii) the radio channel within the radio channel. A radio channel (hereinafter referred to as channel CHI), such as a channel with an empty time slot among the time slots, enters the receiving state according to the procedure determined by the respective system. This is possible by capturing the synchronization signal within the time slot SDi shown in FIG. 2A(a). In the control unit 140, the synthesizer 121-
A control signal is sent to the synthesizer 122-1 to generate a local frequency that enables reception of the radio channel CH1, and the switch 122-1 is also fixed in the position of the synthesizer 121-1.

Therefore, when the receiver of the telephone unit 101 is off-hook (starts making a call) 5201 (FIG. 4A), the synthesizer 121-2 of FIG. A control signal is received from the control section 140 to generate the following. Further, the switch 122-2 is also turned toward the synthesizer 121-2 side and becomes fixed.

Next, the calling control signal output from the telephone unit 101 is sent out using the wireless channel CH1. This control signal is
The frequency band shown in FIG. 2A (b) is used and is transmitted using, for example, time slot Sun.

The transmission of this control signal is limited to time slot Sun, and is sent in bursts, and no signal is transmitted during other time slots, so it does not adversely affect other communications. However, if the speed of the control signal is relatively slow or the amount of information in the signal is large and cannot be accommodated in one time slot, the same time slot of the next frame will be displayed after one frame or roughly. - Transmitted using slots.

Specifically, the following method is used to capture the time slot Sun. The control signal transmitted from the radio base station 30 includes a synchronization signal and a subsequent control signal, as shown in FIG. becomes possible.

Roughly speaking, this control signal includes control information such as currently used time slots and unused time slots (empty time slot display). Depending on the system, the time slot sot <r=1.2°...
, n) may contain only synchronization and speech signals when they are being used by other communications; By receiving this control signal, mobile radio m1oo can know which time slot should be used to send out the calling signal.

Note that if all time slots are in use,
It is not possible to make a call on this radio channel and it is necessary to sweep and search for another radio channel.

In other systems, there may be no empty slot indication in any of the time slots, in which case the following audio multiplex signals SD1, SD2 . ..., S
It is necessary to search for the presence of Dn one after another and check for empty time slots.

Now, returning to the main topic, the mobile radio t1100, which has received the control information sent from the radio base station 30 by one of the methods described above, determines in which time slot it should send the call control signal, and then determines the transmission You can make decisions including timing.

Therefore, assuming that the time slot Sun for uplink signals is an empty slot, it is decided to use this empty time slot, and the necessary timing is determined from the response signal from the radio base station 30 by sending out a control signal for calling. burst-like control signals can be sent out.

If there is a call from another mobile radio at the same time, the calling signal will not be properly transmitted to the radio base station 30 due to call collision, and the operation will have to be restarted from the beginning, but this probability is When viewed as a system, it is kept to a sufficiently small value. If call collisions are to be significantly reduced, the following method may be used. If the mobile radio 1100 finds an empty time slot in which it can make a call, it does not use the entire time slot, but uses only the first half for some mobile radios and the latter half for others. This is the way to do it. In other words, the time signal is used as a calling signal.
Divide the used portion of the slot into several types, use this to classify a large number of mobile radio devices into groups, and place one of the slots in each group.
This method gives the time period within one time slot.

Another method is to create many different frequencies for the control signal,
This is a method of dividing a large number of mobile wireless devices into groups and applying this to each group. According to this method, even if control signals of different frequencies are transmitted simultaneously using the same time slot, no interference will occur at the radio base station 30. The above two methods may be used separately, or when used together, the effects will increase synergistically.

Now, suppose that the call control signal from the mobile radio device 100 is successfully received by the radio base station 30 and the ID (identification number) of the mobile radio device 100 is detected (S202). Search for time slots. The time slot given to the mobile radio IJ100 may be Sun, but a search is performed just to be sure. This is to accommodate simultaneous calls from other mobile radios in addition to the mobile radio 100, and to provide time slots suitable for service types and service classifications.

As a result, for example, if time slot SD1 is vacant, time slot SD1 of radio channel CH1 is used for mobile radio device 100, and time slot uplink (mobile radio device 100 → radio base station 30 )SLJl.

and instructs to use the corresponding downlink (radio base [30→mobile radio device 100) SDl (3203)
>. In response, the mobile radio device 100 transitions to a state in which it can receive data in the designated time slot SD1, and at the same time shifts to a state in which it can receive data in the designated time slot SD1, and at the same time, the mobile radio device 100 shifts to a state in which it can receive data in the designated time slot SD1, and also changes the time slot 5tJ1 (5tJ1), which is the time slot for the uplink radio channel corresponding to the downlink time slot SD'l. 2
(See Figure A (b)). Mobile radio at this time! 11
In the control unit 140 of 00, the transmission/reception intermittent controller 12
3 to start operating the switches 122-1 and 122-2 (8204). At the same time, it sends a slot switching completion report to the radio base station 30 using uplink time slot SU1 (8205>) and waits for a dial tone (8206>).

Time slot 5L of the radio carrier wave of this upstream radio signal
The state of J1 is schematically shown in FIG. 2B (C). In addition to the time slot SU1, the radio base station 30 also receives SU as an uplink signal from another mobile radio device 100.
3 and Sun are included in one frame and sent.

G at the wireless base station 30 that received the slot switching completion report;
t (3207), sends a calling signal to the MJ exchange va20 (3208>), upon receiving this, the gateway exchange 20 detects the ID of the mobile radio 100, and selects the ID of the mobile radio 100 from among the switches included in the barrier exchange 1120. Turn on the switch (S209>) and send out a dial tone (321)
0, Figure 4B).

This dial tone is transferred by the wireless base station 30 (S211>, and the mobile wireless device 100 confirms that the communication path has been set (S212).

When transitioning to this state, the telephone unit 1 of the mobile radio device 100
Since a dial tone is heard from the 01 handset, the dial signal begins to be sent. This dial signal is speed-converted by the speed conversion circuit 131 and sent out from the wireless transmission circuit 132 including the transmission section 134 and the transmission mixer 133 using the uplink time slot SU1 (3213>. Thus, the transmitted dial signal is The radio receiving circuit 35 of the base station 30 receives the signal.The radio base station 30 already responds to the calling signal from the mobile radio 100, gives the time slot to be used, and receives the signal from the radio base station 30. Selection circuit group 39 and signal assignment circuit group 52
, the uplink time slot SU1 is received, and the downlink time slot SDI signal is transmitted. Therefore, the dial signal transmitted from the mobile radio 100 passes through the signal selection circuit 39-1 of the signal selection circuit group 39, and the signal speed restoration circuit group 38
Here, the original transmission signal is restored and sent to the gateway exchange 20 as a call signal 22-1 via the signal processing section 31.
(3214>, and a communication path to the telephone network 10 is set (3215>).

On the other hand, an input signal from the barrier switch 20 (initial control signal,
When a call is started, the call signal is speed-converted by the signal speed converter circuit group 51 at the wireless base 830, and is given a time slot SD1 by the signal allocation circuit 52-1 of the signal allocation circuit group 52. There is. Then, the time slot SD of the wireless channel downstream from the wireless transmission circuit 32
1 to the mobile radio device 100. In the mobile radio device 100, the time and time of radio channel CH1 are
It is on standby for reception in slot SD1 and is received by radio reception circuit 135, the output of which is input to speed restoration circuit 138. In this circuit, the original signal of the transmission is restored,
It is input to the handset of the telephone unit 101. Thus, a call is started between the mobile radio device 100 and a regular telephone within the regular telephone network 10 (8216>).

The call is terminated by on-hooking the handset of the telephone unit 101 of the mobile radio device 100 (S217>, the end-of-call signal and the on-hook signal from the control unit 140 are transmitted to the speed conversion circuit 1.
31 from the wireless transmission circuit 132 to the wireless base station 30 (321B>, the control unit 140 stops the operation of the transmission/reception intermittent controller 123 and switches the switches 122-1 and 122-2 to the synthesizer. It is fixed to the output ends of 121-1 and 121-2.

On the other hand, in the control unit 40 of the radio base station 30, the mobile radio device 1
Upon receiving the end call signal from 00, the end call signal is transferred to barrier exchange 1!120 (8219), and the switch group (not shown) is turned off to end the call (3220).
. At the same time, the signal selection circuit group 39 and signal allocation circuit group 52 in the radio base station 30 are opened.

In the above explanation, control signals between the radio base station 30 and the mobile radio device 100 are controlled by the signal speed conversion circuit group 51. Although it was explained that the signal speed restoration circuit group 38 etc. are not passed through,
This is for convenience of explanation, and communication can be carried out without any problem even through the signal speed conversion circuit group 51, signal speed restoration circuit group 38, control signal speed conversion circuit 48, or signal processing section 31, as with audio signals. .

(2) Incoming call to mobile radio device 100 The mobile radio device 100 is on standby with the power turned on. In this case, as explained in the section regarding the call origination from the mobile radio device 100, the mobile radio device 100 is in a waiting state to receive a downlink control signal of the radio channel CH1 in accordance with the procedure defined by the system.

Assume that an incoming call signal to the mobile radio device 100 arrives at the radio base station 30 from the general telephone network 10 via the barrier switch 20. These control signals are transmitted as communication signals 22 to the control unit 40 (FIG. 1C) via the signal rate conversion circuit group 51 and the signal allocation circuit group 52, similarly to the voice signals. Then, the control unit 40 uses an empty slot of the downlink time slot of the radio channel CH1 addressed to the mobile radio 11100, for example, SDl, to change the I of the mobile radio 11100.
D signal 10 incoming call signal display signal 10 time slot usage signal (for example, SDl
5tJ1 corresponding to ) is sent.

In the mobile radio device 100 that receives this signal, it is transmitted from the receiving section 137 of the radio receiving circuit 135 to the control section 140. In the control unit 140, this signal is transmitted to the own mobile radio device 10.
Since it is confirmed that the incoming call signal to 0 is necessary, the telephone unit 10
At the same time, the transmission/reception intermittent controller 123 is operated to stand by at the designated time slots SD1 and SU1, and the switch 122-
1°122-2 starts turning on and off. In this way, the state has shifted to a state in which calls can be made.

Next, we will theoretically explain how this system can be used to perform signal transmission in good conditions without adversely affecting other wireless channels within the system. for that,
Let us take an example of an uplink radio signal (transmitted by the mobile radio 1100 and received by the radio base station 30).

First, assume that all uplink radio signals are empty lines, that is, all time slots are not used. The mobile radio device 100 that wishes to make a call receives a control signal in the downlink radio channel, for example, time slot SD1, so that the mobile radio device 100 determines the usable time slot of the uplink radio channel.
After selecting a slot (for example, time slot SDI>), the radio transmitting circuit 132 sends a control signal (a speech signal if a speech path is set) to the radio base station 30 in response to a signal from the timing generation circuit 142.

Similarly, if there is a call originating (terminating) from another mobile radio, a control or conversation signal is sent to the radio base station 30 as an uplink radio signal using another time slot on the same radio channel.

The signals included in the uplink radio channel explained above will be expressed mathematically.

The data or call signal (for signals in analog or digital format), which is the output signal (or control signal) of the telephone section 101 in FIG. 1B-1, is transferred to the speed conversion circuit 13.
It can be expressed as after passing through 1.

However, eT≦t≦(T/n)+e−0,1,2,... (1a)μ(t)−
0 However, (T/n>+eT<t<T+eT (1b>(1)) Also, the control signal and spreading generator 154 that exist outside the band
The output of is, where t is the condition of equation (1a) (2a) μ. (t)-0 However, t is the condition of equation (1b) (2b) (2) Here, al is the magnitude of the amplitude, ωi is the angular frequency of the signal,
θi represents the phase when 1-0. m.

n represents a positive integer. Note that, although the following explanation will be based on a case where diversity transmission is not adopted, analysis can be performed in the same way even when diversity transmission is adopted.

The case of frequency modulation will be described below, but the present invention is similarly applicable to phase modulation. (1) or (1)
) and (2), the resulting modulated wave is as follows: 1=I□ sin f (ω0μ(t)) dt=I□5
in(ωt+5(t)) However, t is the condition of equation (1a) (3a)-0 However, t is the condition of equation (1b) (3b)(3) Or, 1=I□ sin f (ω0μ (1) Ten μ. (t)
>dt=I□5in(ωt+5(t) +5c(t)
) However, t is the condition of equation (1a) (4a) I=0 However, ↑ is the condition of equation (1b) (4b) 4) Here, go to 5(1)″1.fit sin (wHt+θ Kasumi・
= a・/ωH (i = 1-2-3-..., n) 1 5(t) + 5C(t) shown in equation (4) represents the transmission signal in the form of - boat fishing. become.

Now, using equation (3) or equation (4), mobile radio @
The radio signals sent out from 100 antennas are expressed by the following equation.

! −(101/n) [1+2 Fl(n/ml)X
Sill (m7t(/n)CO3mptlxsin
(Ω1 j+s1 (j) +5o1(1)) (5> where n is the number of slots (equal time intervals) within one frame, p is the switching angular frequency, and m is a positive odd number.

Equation (5) is the mobile radio device 10 using the same radio channel.
In this case, the transmission signal from 0 is in one of n slots in one frame, but in a state where all slots are implemented with signals, that is, n mobile radio devices 100 use the same radio channel. The mathematical expression of the signals included in the wireless channel when the wireless channel is in communication is as follows.

1= (I01/n> [1+2.i, (n/mπ)
)xsin (mπ/n)cosmpt]xsin
(Ωt t+ 81 (j) + 5C1(t) )+
(I02/n) [1+21,1(n/m7C”)
)xsin (myr/n) xcos mp (t-2π/ (np)) ]xs
in (Ω2i+S2 (t) +s, 2(t) )
10 (I03/n) [1+2Σ (n/mπ) m=1 ) XSin (m7r/n) xcos mp (t-4yr/ (np) ] ]x
sin (Ω3i +53(1)+5c3(t))+・
... + (I□o/n) [1+2Σ (n/mπ) m=1 ) xsin (mπ/n> xcos mp (t-2(n -1> 7C/ (r
l) ) ]xsin (Ω t+s, (t) +5
oo(t) ) (6) where p is the switching angular frequency, m is a positive odd number, and the switching times for n input waves are equally spaced, that is, the time slot lengths are all the same.

As shown in equation (6), in the wireless base station 30,
The point that it is necessary to receive all signals sent in time series from a large number of mobile radios @ 100 and distribute the demodulated output as audio signals for each channel is the point that when receiving mobile radio 100 as described below, The behavior is different. .

Now, a signal transmitted from the radio base station 30 which is communicating simultaneously with a large number of mobile radio devices in a time-sharing manner is expressed by the following equation (7).

1= (101/ n> [1+2 Fl(n/m7r
) )XSin (m7r/n) CO3mpt
]xsin (Ωt+51(t) +5C1(t))
+(I02/n> [1+2i, (n/mx) )xs
in (mπ/n) xcos rr+p (t-2yr, / (np))
]xsin (Ωi+s2 (t) +5o2(t)
)+ (103/n>[1+2Σ (n/ml)m
=1 XSln (m7r/n> xcos mp (t-4π/ (rl) ) ] xs
in (Ωj+S3 (t) +5o3(t) )+(
I On/n ) [1+2Σ(n/ml) m=1 xsin (mπ/n> xcos mp (t-2(n-1) yr/ (n
o) ) ] x sin (Ωt + sn (t)
+5cn(t) ) (7) However, p is the switching angular frequency, m is a positive odd number, and the signal component St (t) (i = 1.2. ・, n> is naturally (6
) expression, but for convenience we have used the same expression.

Also, the field of view term l01 = IO2, ..., 1oo is considered to be the same in practice, but in order to improve the comparison with the number of the opposing mobile radio device 100, or to perform transmission power control, it is assumed that ( 7) It was expressed as Eq.

Next, regarding the signals received by each mobile radio 11100, in equation (7), only the signals necessary for the mobile radio 100 itself are processed by the timing generator 142 and the transmission/reception intermittent controller shown in FIG. 1B-1. 123 for selective reception.

Now, for the mobile radio device 100-1, the second A
If we use the time slot SDI shown in the figure, (
7) This is the first term on the right side of the equation, that is, the signal shown on the right side. When this signal passes through the amplitude limiter included in the receiving section 137 in FIG. 1B-1, it takes on the form shown in the following equation.

1=Asin (Ωt+51(t) +5C1(t)
) However, t is the condition of equation (1a) (7' a)■=0 However, t is the condition of equation (1b) (7' b) (7'
) Also, A is the imaging width and is not related to frequency or time.

When the equation (7') passes through the frequency discriminator included in the receiving section 137, the demodulated output is e(t)=μ(1)+μC(1) where t is the condition e( t)=0 However, t obtains the condition of equation (1b). If this output is passed through the speed restoration circuit 138 shown in FIG. 1B-1, the original signal is reproduced. However, it is assumed that the output of the spreading oscillator is filtered by a low frequency filter (high bus filter) 147 as shown in FIG. 1B-4.

The demodulated output when the radio base station 30 transmits and the mobile radio device 100 receives the demodulated output has been described above.
0 transmits and the wireless base station 30 receives.

Hereinafter, equation (6) will be modified because it will be necessary to investigate the influence of adjacent channel interference, which will be described later.

The right side of equation (6) is expanded as shown below.

! −(1/n) [sin (Ω t+U1(t))0
1 1 + (n/π) sin (π/n> x[5in ((Ω1+p)i+U1 (t))+5in
((ΩI I)> j+U1 (t) ) ]+ (
n/3π) sin (3π/n>x[5in((Ω
+3E)>t+U1m-(6π/n)(n-1>) +5in((Ω1 3p) t+L11 (t)+(6
π/n>(n-1>)co+(n15π)Sin (57r/n>x[5in
((Ω1+5p) j + lJl (j) − (10π
/n>(n-1>) +5in((Ω1-.5p)t+L11(1) ten(10
π/n>(n-1>)] +...Co+ (102/n> [sin (Ω2 t+LI2
(t) )+(n/π)Sin(π/n> x[5in((Ω2 +p) 'j+U2 (t>)
+sin[(Ω2-p)t+U2(t)) ]+(n/
3π) sin (3π/n> X[5in((Ω2 + 3 p) t + U2 (
t)-(6π/n)(n-1>) +5in((Ω2 3p) j+LI2 (j)+(6
π/n>(n-1>)] + (n15yr) sin (5π/n) x [5in
((Ω2 + 5 p) t + U 2 (t) - (
10π/n>(n-1>) +5in((Ω2 5p)t+U2 (j)+(10π
/n)(n-1>)] +--°-,] + (I□o/n> [sin (Ω, t+Uo(t)
)+(n/π)sin(π/n> x[5in((Ω1+p) to 10un(t))+sin
((Ω −p> 10 u. is)) co+(n/3π)si
n (3π/n) x[5in((Ω, +3p)t+U, (t)−(6π/
n)(n-1)) +5in((Ω-3p)t+U,(t)-(6π/n
>(n-1>)] + (n15π>Sin (5π/rl)x[5in
((Ω +5p)t+U, (t)-(10π/n)(n
−1>) +5in((Ω −5p)t+Uo(t)−(10π/
n>(n-1))ko+...
(8) However, U・(t) = s-(t) +5oH(t)1 (+=1.2...,n) Here, looking at equation (8), we can see that many carrier waves are combined. You can see that it has become our home.

Hereinafter, it will be explained that the system according to the present invention can be operated without any problems in practical use by quantitatively evaluating adjacent wireless channel interference, same radio channel interference, and transmission signal delay time, which are problems in system construction.

(I) Adjacent radio channel interference Taking as an example a case where the number of time slots in one frame is 10, the audio multiplicity is 10.1, and the frame period is 100 ms, most signal components are within one channel. The effect on adjacent channels is extremely small.
This will be explained quantitatively below.

In equation (8), adjacent radio channel interference will be greatest when all implementations are in use, that is, when all time slots are in use. Also, for convenience of calculation, regarding the imaging width Ioi (i-1, 2, . . . n) of the signal sent from the wireless base station 30 and the transmitted signal Ui (i=1.2. . . . n>), U1 =LJ2=-=U.

(9) Iol""02="""= l0n= ■0(9'
), so equation (8) can be expressed as follows.

1/ n= (10/ n ) (sin (Ω1t+
U1(j) )+ (n/:IT)Sin (7r/n
>x [5in ((Ω1+p) t+LJ1 (t) )
+sin [(Ω1-1)) t+L11 (t) )
] + (n/3π) sin (3π/n>x[5in
((Ω1 +3p)t+U1 (t)−(6π/n>(
n-1>) +5in((Ω1 3p) j+U1 (t)-(6π
/n)(n-1))] + (n15π) sin (5yr/n>x[5in
((Ω1 +5p) t+L11 (t)-(10π/
n>(n-1>) 15in((Ω1 5p) t+LJ1(t)-(10
π/n>(n-1>)ko+...] (10) As the value of p included in equation (10), set 20π radians, that is, the frequency to 10H2, and ignore the phase of the carrier wave. However, if the energy (voltage) is expressed as a peak value (this results in a greater evaluation of the influence of interfering radio waves), the following equation is obtained.

I/n= (10/n) (1 + (n/π) sin (π/n> + (n/3yr) sin (3π/rl) 10・
・・)(I□ /n> ((n/π)Sin (7r/
n) ten (n/3π) sin (3π/n>+...)(
11) However, when viewed from other radio channels, the position of the carrier frequency of the above-mentioned jamming radio waves is ±p, ±2p, ±3p, etc. above and below the main carrier frequency, respectively. It is in. However, the calculation continues based on the assumption that the area has the greatest impact.

Therefore, sin (π/n>, sin (3π/n>.

Since the absolute value of 5in (5π/n), . In other words, if these are all set to 1, equation (11) becomes nI/I□ = 1+ (n/π) (1+1/3+115
+...+1/ (2m-1)+...) +(n/π) (1+1/3 +115+...+1/ (2m-1)+...) (12) This formula (12) The 1 in the first term on the right-hand side of is the main carrier component, the second term (n/π)() is the subcarrier component in the upper frequency band of the main carrier, and the third term (
n/π)() represents the subcarrier component in the lower frequency band.

When the energy distribution of a large number of carrier waves shown in equation (12) is shown on the frequency axis, it becomes as shown in FIG. From equation (12), among the subcarrier energy (amplitude value) held in the wireless channel, the energy within 10 KH2 above and below the center frequency is compared with the energy within 10 to 20 KH2. First, the energy (voltage value) within l0KH2 E = (IOKII2) = 2n/yrx 5
．． 5506 (13) Also, the energy E(2
0KHz) is = 2n/πx O, 1421 (14) Therefore, R= E (20KH2) / E (IOKH2)
+0.0256(15) That is, it can be seen that it has gradually decreased to about 1/40.

Similarly, if you find the energy within 20 to 30 KH2 above and below and compare it in the same way, it will be 0.00761 or about 1/1
It has gradually decreased to 30.

The above approximate example is a result of calculations emphasizing the existence of a large number of subcarriers, but the transmission output is still 99%
% or more of the energy exists within the transmission band of its own wireless channel, and the remaining energy of 1% or less may cause radio wave interference to other channels.

Using equation (12), find the carrier power that can cause interference to adjacent channels. However, in the calculations below, it is assumed that the frame configurations of adjacent channels are exactly the same.

It is assumed that the adjacent channels shown in FIG. 5 are separated by H2 with a channel spacing of 125, and that the H2 component causes interference at subcarrier frequencies 75KH2 to 175 within these channels. Actually, the signal component of the adjacent channel is 125
Since it exists within ±30KHz, 95 to 155K
Although only the H2 component is sufficient, a case where the channel spacing is narrowed was also assumed. If taken as described above, this can be considered to be the result of a study in which the channel spacing was 105 KHz. Now, the total power of the interference wave can be obtained by adding 8751 items from the 3751 items on the right side of equation (13). That is, (16) On the other hand, since the energy of the main carrier wave (which is equal to the energy of the main carrier wave of the adjacent channel) is 1, the signal-to-interference-radio wave ratio (hereinafter abbreviated as D/U) is 1/0.00.
27, which is 50 dB when expressed in decibels (however, this is a power ratio).

In the above calculations, p was 20π radians (10Hz), but if we perform the same calculations when p is 100H2 (the purpose of increasing p is to shorten the signal delay time as described later), , the signal-to-interference ratio is 30 dB (
power ratio). By the way, in general mobile communications,
Since the allowable D/U (signal wave to interference wave) value for co-channel interference is about 24 dB (power ratio), the above calculated value is satisfied with a sufficient margin.

That is, it can be seen that even if the transmission wave according to the present invention is operated intermittently in a pulsed manner, the radio wave interference exerted on adjacent channels can be ignored.

(n) Self-intra-channel interference Self-intra-channel interference occurs due to the characteristics of the bandpass filter or intermittent circuit set at the output section of the wireless transmitter circuit, which is the higher order of the transmitted pulse expressed by equation (10). This is because a carrier wave having a large value of n out of Ω1±np is not output. In this case, the ideal shape of the envelope of the signal wave sent out into space is not a rectangle (within which the carrier wave is accommodated), but ultimately a number of sine waves approaching a rectangular wave. The waveform has a superimposed shape (the waveform is the 2nd B
(The state has a beat-shaped envelope as shown in d>).

Then, signal components with this shape will enter other time slots, causing self-intra-channel interference.

This influence will be theoretically determined below.

Assume that time slots SD1 and SD2 are used for communication A and communication B (FIG. 2B (d)). The interference waves that influence communication A on communication B can be expressed numerically with reference to equation (8) as shown in the following equation.

xsin ((2m+1) π/n) [cos
((Ω+ (2m+1) p) to 10tJ(t))−
COS ((Ω-(2m+1) p)t+LI(t))
] (17) In order to specifically obtain equation (17), it is sufficient to perform the same numerical calculation as already done after equation (b).

Therefore, if the characteristics of the filter circuit included in the wireless transmitter circuit 32 are taken as a broadband characteristic, the mO is set to 1000 mO, for example.
(100) IZX 1000 = 100 (H2) or more, it becomes possible to ignore the influence of self-channel interference. In an actual circuit, this condition can be easily satisfied.

(III) Co-channel interference Co-channel interference occurs when the present invention is applied to a small zone system. This occurs when radio waves from the channel are mixed in.

In FIG. 6, a small zone covered by each radio base station 30 is shown as a regular hexagon, and each radio base station 30 is arranged at the center of the hexagon. In this example, each of the radio base stations arranged at 1 to 7 uses a different radio channel, and the number of repetitions is 7.

In FIG. 6, the distance between two wireless base stations 30 using the same wireless channel (from the center of regular hexagon 1 to the other regular hexagon
When the shortest distance of the rectangle 1) is d, it is necessary to find the allowable D/U 1lII (the value of the ratio of the desired wave input level D to the interference wave input level U). To do this, the D/U value can be determined if the frequency used in the system, the transmission power (size of the wireless zone), and the radio wave propagation state are known. In a conventional analog system, the interference value is known for the D/U value obtained in this way, but in the present invention, the modulation mechanism is completely different, so it is impossible to apply the conventional technology. It cannot be determined accurately unless the system is actually constructed and measured.

However, in the case of the present invention, not only the conventional analog system but also the "Time division communication system for mobile communication" (Patent application No. 63-5906) already filed by the inventor of the present invention is applicable.
4> and "Time division communication method in mobile communication" (Patent application 1-163210), the negative effects of interference waves are further reduced, the number of repetitions can be reduced, and the effective use of frequencies is improved. It is expected that

This will be explained in detail below.

As explained in the "Prior Art" section, co-channel interference occurs because the frequency spectrum distribution of the desired wave (D wave) and that of the interfering wave (U wave) overlap, and In that case, the magnitude of the interference increases when the power of a specific frequency in the frequency spectrum of the U wave is large.Therefore, in order to reduce the influence of interference waves under the same number of repetition zones, The following measures should be taken.

i) Expand the frequency spectrum of the interfering waves within the range allowed by system design.

i) Make the power distribution of the frequency spectrum of the interference waves as uniform as possible.

Hereinafter, the measures for the above i>, ii) will be explained using FIG.

FIG. 7 (a> is a schematic diagram of the spectrum of the angle modulated wave when the diffused light 3 & device 154 is not used. Desired wave (D wave)
The carrier waves and sideband waves are shown by solid lines, and the interference waves (U waves) are shown by broken lines. In FIG. 7(a), the U wave influences the D wave in the portion where the carrier wave of the U wave overlaps the solid line triangle among the broken line triangles. On the other hand, FIG. 7(b) shows a schematic diagram of the spectrum of the angle modulated wave when the spread oscillator 154 is used. D-wave carrier wave,
The sideband waves are shown by solid lines, and the U waves are shown by broken lines. In this case, the U wave affects the D wave at the part where the frequency components of the power of both the D and tJ waves overlap, as in Fig. 7(a), but (a) and (b) ) to compare the above two conditions 1).

If ii) is satisfied, interference will be reduced for the following reason.

First, when the frequency spectrum is expanded, the power per unit frequency band is reduced, and the overlapping portion of the D and U wave spectra is relatively reduced. Next, if the power distribution of the signal is almost uniform, as is clear from Figure 7(b), the power of the D wave will be higher than that of the U wave no matter what frequency is taken. . Then, the U wave is suppressed by the D wave through processing within the receiving circuit, and the degree of interference is greatly reduced.

Now, the existence of the spread oscillator 154 of the present invention is due to the above i>
, ii) is effective in realizing the conditions described below.

Looking at the right side of equation (8), it can be seen that after expanding 5in(), many terms as shown below occur.

sin (SoH(t)) (1
8) As is clear from equation (2), the part in parentheses in the above term includes the control signal and the output of the spreading oscillator 154, but since the latter has a low frequency of, for example, 50H2, expand equation (18). . In this case, use the following Neumann formula for the Bessel function. That is, sin (βsinψ)−2ΣJ
(β) Fat 0 2n+1 xsin (2n +1) ψ −2Jl (β) sinψ +2J3 (β) sin3ψ +2J5 (β) Sin5ψ+... cos (βs
inψ)=Jo (β)+2axe, J2n(β)cos2
nψ −J. (β)+2J2 (β)cos2ψ+2J4
(β)cos4ψ+... Here, Jo (β) is the n-th order Be5 of the first kind for β.
se l functions, these take on values like damped oscillatory waves.

When expanded using the above equation, equation (8) can be physically expressed as follows.The spectrum of the signal wave is 50H2IJ
A large number of subcarriers exist at intervals, and signals obtained by angle-modulating communication signals and control signals centered on the subcarriers are superimposed.

Therefore, the signal wave is spread, and it has been proven that the above conditions i>, ii) are satisfied.

The above explanation was about the case where the present invention was applied to a mobile communication system using a time division time compression method, but even if the present invention is applied to a mobile communication system using a normal angle modulation method,
The effect is exactly the same, and it is highly effective in reducing co-channel interference.

[Effects of the Invention] As is clear from the above description, when angle modulation is used as a modulation method in a wireless system that uses the same wireless channel at different locations, in order to reduce mutual interference, By adding the output of the spreading oscillator to the modulated signal and performing angle modulation, co-channel interference can be greatly reduced, so the effects of the present invention are extremely significant.

[Brief explanation of the drawing]

Figure 1A is a conceptual block diagram showing the concept of the system of the present invention, Figure 1B-1 is a circuit diagram of a mobile radio used in the system of the present invention, and Figure 1B-2 is a diagram showing the circuit configuration of a mobile radio used in the system of the present invention. FIG. 1B-3 is a circuit diagram showing another embodiment of the mobile radio used in the system of the present invention, and FIG. A detailed circuit configuration diagram of a radio receiving circuit of a mobile radio device used in the system of the present invention, FIG. 1C is a circuit diagram of a radio base station used in the system of the present invention, and FIG. 2A is a diagram of the system of the present invention. Figure 2B is a diagram showing the radio signal waveform of the time slot; Figures 3A and 3B are the spectrum of the call signal and control signal. FIG. 3C is a circuit configuration diagram for multiplexing audio signals and data signals, FIGS. 4A and 4B are flow charts showing the flow of operation of the system according to the present invention, and FIG. 6 is a configuration diagram showing a small zone configuration to which the present invention is applied, and FIG. 7 is a spectrum diagram for explaining radio wave interference to a channel.
The spectrum diagram of both waves, Figure 8, is a conceptual configuration diagram for explaining the conventional system. 10... Telephone network 20... Gateway switchboard 22
-1 to 22-n...Communication signal 30...Radio base station 31...Control/call signal processing section 32...Wireless transmitting circuit 35...Radio receiving circuit 3
8... Signal speed restoration circuit group 38-1 to 38-n... Transmission speed restoration circuit 39...
Signal selection circuit group 40...Control unit 41...Clock generator 42...Timing generation circuit 51...Signal speed conversion circuit group 51-1 to 51-n...Signal speed conversion circuit 52...・
Signal assignment circuit group 52-1 to 52-n...Signal assignment circuit 91...Digital encoding circuit 92...Multiple conversion circuit 95...Spreading oscillator 96
...FM modulator 97...amplifier 100.10
0-1 to 100-n...Mobile radio 101...Telephone unit 120...Reference crystal oscillator 121-1, 121-2...Synthesizer 122-1
, 122-2...Switch 123...Transmission/reception intermittent controller 131...Speed conversion circuit 132...Wireless transmission circuit 134...Transmission unit 136...Reception mixer 138...Speed restoration circuit 143 . . . Intermediate frequency amplifier 145 . . Discriminator 153 . . . Modulator 155 . 147...Low frequency filter 154...Diffusion oscillator 159...High frequency amplifier.

Claims (1)

[Claims] In an angle modulated signal of a wireless system using angle modulation in which the same radio channel is used at different locations, a spread oscillation means is used to reduce mutual interference, and its output is modulated by the angle modulation. A method for preventing co-channel interference in mobile communications that uses angle modulation in addition to signals.