JPS5925438A - Radio transmitting system of out-band signal - Google Patents

Abstract

PURPOSE:To improve both the signal transmitting reliability and the interference detecting accuracy, by setting two waves outside a main signal band as the carrier waves for transmission of digital signals and using the carrier wave frequency also for detection of interference. CONSTITUTION:At the communication side, the audio signal sent from a terminal 101 is supplied to an adder 104 through an amplitude limiter 102 and a BPF103. While subcarrier generators 106 and 107 receive ON/OFF keying by the digital signal sent from a code generator 105. The keyed signals are added together by an adder 110 through BPF108 and 109 and then synthesized with the analog audio signals at the adder 104. These synthesized signals are transmitted after undergoing FM modulation through a transmitter 111.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides 7iF out-of-band signal wireless transmission which makes it possible to detect same-wireless channel interference, for example, when a digital signal is superimposed and transmitted outside the voice band in a mobile communication system. It is related to the method.

<Background> In a mobile communication system, a mobile area is divided into a plurality of zones z1 to z9, for example, as shown in FIG. 1, and different radio channels are assigned to adjacent zones.

In FIG. 1, there are wireless channels #fs to fn7>1 in zones ZI, ZR+Z7, and Zs. /'-n Z2
, wireless channels fn+1 to fin are allocated to Zs, wireless channels fllll+l to fs1 are allocated to zone 74.7.6, and wireless channel f8n+1% f4H is allocated to zone Z6, so that fewer wireless channels can be used effectively. .

However, in the out-of-band signal wireless transmission method, either a digital signal is directly superimposed outside the lower voice band and the wireless channel is modulated and transmitted, or a subcarrier is provided outside the upper voice band and the subcarrier is converted into a digital signal. FSX modulation is performed, the signal is superimposed on audio, and the radio channel is modulated and transmitted. When these systems are applied to the mobile communication system, interference may occur in these same radio channels because the same radio channels are used in different zones. If interference occurs, the digital signal cannot be detected correctly, so it is necessary to switch to another wireless channel for transmission, for example. In this respect, it is necessary to detect and evaluate interference, and it is conceivable to perform this evaluation based on error rate. But in this case,
Since the signal transmission speed is slow in out-of-band signal transmission, detection time is long and it is difficult to separate the effects of thermal noise and interference. In contrast, multiple tone signals dedicated to interference detection are superimposed outside the 4IF band and outside the lower band of the audio.
A possible method is to assign each tone signal to each zone and determine that there is interference when a tone signal from another zone is detected.

FIG. 2 shows the state of the baseband spectrum in this case. fP, Figure 2. A person places the digital signal 12 outside the lower band of the audio signal 11, and the tone signal p'1 outside the upper band.
．． This is the case where 'f;'t is assigned 7c. In FIG. 2B, a signal 13 obtained by FSK modulating the subcarrier fB with a digital signal is placed outside the upper band of the audio signal 11, and a tone signal F@ is placed outside the lower band of the audio signal 11.

This is the case when F4 is assigned. In these methods, it is necessary to transmit signals separately for digital signal transmission and interference detection, so it is necessary to transmit signals separately for digital signal transmission and interference detection.
The disadvantage is that the number of tone signals for zone differentiation is not sufficient and the reliability of the digital signal is also reduced.

<Summary of the Invention> The purpose of the present invention is to detect interference from many same radio channels, and to detect interference in a short time without reducing the reliability of the digital signal. A8-) The objective is to provide a (flu Itll:A) transmission system.

According to this invention, the digital signal transmission frequency signal and the interference detection frequency signal are used together. That is, a number of subcarriers υ are allocated outside the band-limited main signal band such as an audio signal, and each combination of two waves of these subcarriers is allocated to different same radio channel sources. The digital signal is superimposed on the main signal using two subcarrier waves assigned at intervals of t in these radio channel sources, and the radio channel is modulated and transmitted. υ digital signal by subcarrier f! !
In addition to FA, interference is detected from the presence or absence of other subcarriers.
You can do it with the power of giving out.

<Example> FIG. 3 shows an example of the present invention. Terminal 10 on the sending side
The audio signal from 1 is processed by an audio instantaneous amplitude limiter (II)C)
102. iIY with passband from 0.3 to 3 KHz
The signal is supplied to an adder 104 through a bandpass F-wave unit 103 in sequence. On the other hand, the subcarrier generators 106 and 107 are keyed ON and OFF by the digital signal from the code generator 105, and the subcarrier signals of keyed frequencies ftt and fus from the subcarrier generators 106 and 107, respectively, are turned on and off. The signals are passed through bandpass p-wave devices 108 and 109 with passing frequencies fix and fu+, are added by an adder η-device 110, and further synthesized with an analog audio signal by an adder 104. In this case, the baseband spectrum has a subcarrier f below and above the band of the audio signal 11, as shown in FIG.
Signals 14 and 15 are arranged centered on t, x, and fu+ and spread out at about the transmission speed of a digital signal. The combined output of the adder 104 and υ is used to FM-modulate the dotted line carrier wave in the transmission 4-i 1111 and then transmit it. subcarrier f
For example, in FIG. 1, tx and fat are previously assigned to zone z1.

FIG. 4 shows an example of the receiving side. The audio signal in the signal received and demodulated by the FM receiver 202 is outputted to the output terminal 204 through the bandpass p-wave device 203.

The demodulated output is separated into fzt and f old components by bandpass p-wave filters 205 and 206, respectively, and further 4? divider 20
9. At 210, these integral outputs are outputted by the difference circuit 21.
3, and the difference output is decoded by a decoder 215 to obtain digits (M months).

On the other hand, in order to detect the S interference signal, the output of the FM receiver 202 is sent to bandpass r-wave generators 207 and 208 at a frequency of ft! and f
The components of ug are extracted and these ftp.

The fut components are each divided by
interference is detected.

In the above, when sending out digital signals, for example, a subcarrier of -ftt is sent to a mark, and a subcarrier of ft is sent to a space.
Assign each subcarrier of UL and send out keying,
Alternatively, after keying and transmitting the f tt subcarrier for the mark, keying and transmitting the f old subcarrier, and conversely, keying and transmitting the ftn subcarrier for the space, and then keying and transmitting the ft1 subcarrier. Send keying. This latter method has the characteristic that even if all marks or all spaces are used, the clock timing is not lost on the receiving side and synchronization is stabilized.

In the example shown in Figure 1, the same radio channel, e.g.
In the seas yZi, ZR, Zy, and Ze using l-fn, two different sets of subcarriers, for example, fttfu
t, ft2fu2. f/-tfug and ft2fu2 are respectively assigned, and when the mobile device moves to another zone, the subcarrier assigned to that zone is used.

For this purpose, for example, as shown in FIG. 5, the frequency of the carrier waves generated by the subcarrier generators 106 and 107 can be changed by the controller 301, and the frequency of the carrier waves generated by the subcarrier generators 106 and 107 can be changed accordingly, as shown in FIG. Pass filter 205, 206, 207, 2
The center passing frequency of 08 can be changed by the controller 302.

Since two subcarriers are provided outside the upper band, there are a total of four subcarriers, so there are 40z=6 combinations, making it possible to separate the same radio channel. Similarly, by providing n waves of subcarriers, the same radio channel can be divided into 1102 ways, and out-of-band channels can be divided into 1102 ways. ′ times the transmission is possible.

In the above description, digital signals are transmitted outside the upper and lower bands of the audio signal, but this is not limited to the η-angle signal. The present invention can be applied to the case where signals are transmitted in a superimposed manner.In addition, the present invention can be applied not only to mobile radio, but also when there is a risk of interference between the same radio channel due to weather conditions, and detects that interference. , digital (
It is also possible to take measures such as canceling the communication of the IT.

As explained above, according to this invention, two waves are set outside the main frequency band as subcarriers for digital signal transmission, and the subcarrier frequencies are set on the same radio channel, but there is a risk of interference. Since one or both subcarriers are different between certain radio signal carriers, this subcarrier can also be used for interference detection, which has the advantage of increasing signal transmission reliability and interference detection accuracy. In addition, since there is no need to send a signal exclusively for interference detection, the configuration on the transmitting side can be simplified by 1 m, and many subcarriers can be set within the limited wireless channel band, which allows for the same hot wire channel to be set up as many times as possible. Can distinguish between signal sources.

Furthermore, since interference is detected from a subcarrier different from the own subcarrier, interference can be detected in a shorter time than when interference is detected from the error p rate of the own subcarrier digital signal. Furthermore, each subcarrier wave is assigned to the same radio channel source, and the subcarrier wave is FSK-modulated with a digital signal, and the subcarrier wave is used for digital signal transmission and interference detection.
, but in this case, the spread of the sideband of the subcarrier is relatively large and it is not possible to make many distinctions.

[Brief explanation of drawings]

Fig. 1 is a diagram showing an example of zone and frequency allocation in a mobile communication system, Fig. 2 is a diagram showing a frequency spectrum of out-of-band signal transmission, and Fig. 3 is an example of an out-of-band signal wireless transmission system according to the present invention. 4 is a block diagram showing an example of the receiving side in FIG. 3, FIG. 5 is a diagram showing an example of the baseband frequency spectrum in the out-of-band signal wireless transmission system according to the present invention, and FIG. 6 is a block diagram showing an example of the receiving side in FIG. A block diagram showing another embodiment of the invention, FIG. 7 is a block diagram showing an example of the receiving side corresponding to FIG. 6. 101: Audio input terminal, 103, , t08.109
．． 203.205-208: Ik band pass P wave device, 10
4.110,214: Adder, 111: FM transmitter, 1
05: Digital ID generator, 106.107: Subcarrier generator, 2o2: FM receiver, 204: Audio output!
1 element, 209-212: Integrator, 213: Difference circuit,
215: Digital signal detector, 216: Interference detector. , Patent applicant Nippon Telegraph and Telephone Public Corporation 71 Agent Jij Kusano

Claims (1)

[Claims] (1) In an out-of-band signal wireless transmission system in which a digital signal is superimposed on a main signal (i) within a predetermined band, a digital signal is superimposed outside that band, the wireless channel is modulated, and multiple The subcarriers are divided and two of the plurality of subcarriers are used to transmit the digital signal, and subcarrier combinations are unique to each region in different regions using the same radio channel. Out-of-band signal wireless transmission method.