JPH05327601A - Time division communication method for mobile body communication - Google Patents

Abstract

PURPOSE:To provide a mobile body communication method in which a digital form time difference telephone signal being a difference between a signal of this frame and a signal of a preceding frame subject to time compression is set to a time slot of frame configuration. CONSTITUTION:The method employs each radio base station 30 covering plural zones and a gate exchange 20 exchanging the communication between the radio base station and each mobile equipment 100 employing a radio channel in which a time difference telephone signal subject to blocking and time compression is set to a time slot of frame configuration. Thus, the signal power of the time difference telephone signal is reduced considerably because there are slots each having a carrier not transmitted and a large multiplexing gain is obtained. Thus, the radio base station 30 and each mobile radio equipment 100 decide a transmission level based on the multiplexing gain and the transmission power is reduced and the frequency is utilized effectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a time division communication method for a mobile communication channel using a variety of digital signals such as digital telephones and various data signals. The present invention relates to effective use of frequencies and reduction of transmission power based on the reduction in power. More specifically, a certain wireless channel is provided, and one of the many mobile wireless devices in the service area is used to set up a wireless channel and communicate with an opposite wireless base station. Among, when the other mobile wireless device starts communication with another wireless base station using the same wireless channel, because of effective use of frequency or radio wave propagation characteristics, respectively, with the mobile wireless device during communication, To provide a method for improving the effective utilization of frequency and a method for constructing an economical system by gradually reducing transmission power, while eliminating the adverse influence on the communication with the radio base station. To do.

[0002]

2. Description of the Related Art In mobile communication using voice to which a small zone method is applied, a method using a time division time compression multiplexed signal is described in the following document.

Reference 1. Ito "Study on mobile phone systems-Proposal of time division time compression FM modulation system-" IEICE Technical Report RC
S89-11 July 1989

Reference 2. Ito "Study on mobile phone system-Theoretical study on time-division time-compression FM modulation system"
RCS89-39 October 1989

Reference 3. Ito "Time division time compression multiplexing (T
CM) Multiple load gain of telephone signal "IEICE Technical Report SST91-58 March 1992

Reference 4. Hayasaka "Introduction to Acoustic Engineering" Published by Nikkan Kogyo Shimbun, March 1978, pages 21-30

That is, in Reference 1, a transmission signal (baseband signal) is divided into predetermined time interval units and stored in a memory circuit, and when reading this, the speed is n times faster than the speed of storing in the memory circuit. Built in mobile radios and radio base stations to read at a predetermined time slot, angle-modulate or amplitude-modulate a carrier wave with the signal accommodated in this time slot, and to transmit and receive intermittently in time. , A switch for a radio receiving circuit having a receiving mixer that communicates with each other, a radio transmitting circuit having a transmitting mixer, a synthesizer applied to the receiving mixer of the radio receiving circuit, and a synthesizer applying to the transmitting mixer of the radio transmitting circuit A circuit is provided, and the output of the synthesizer applied to each is interrupted, and this interrupted state is transmitted and received. For the wireless base station that communicates with each other in an expected manner, the same method as described above for synchronizing the intermittent transmission and reception with that of the mobile wireless device is used, and the receiving side extracts only the signal accommodated in the predetermined time slot. Therefore, by opening and closing the wireless receiving circuit, receiving and demodulating, the signal obtained is stored in the memory circuit, and at the time of reading this, by reading at a low speed of 1 / n of the speed stored in this memory circuit, A system example in which a system that enables reproduction of a transmitted baseband signal, which is an original signal, is constructed has been reported.

Next, in Document 2, the above-mentioned TCM is used.
(Time-division time compression multiplexing) -Adjacent channel interference and co-channel interference, which are problems when the FM system is applied to a small zone, are being studied, and the system can be realized by selecting system parameters appropriately. The possibility is shown.

Further, in Document 3, the multiplex load gain, which has been known to exist in the FDM (frequency division multiplex) signal in the past, has a multiplex load gain similar to that of the FDM signal in the time division time compression multiplex (TCM) system. Reveal that, and
It explains the quantification and operation examples of the system. Then, by using this multiple load gain to deepen the modulation depth of the FM, the transmission power can be significantly reduced, and it is expected that the mobile wireless device can achieve a significant power saving. Has been reported.

Reference 4 describes in detail the nature of human voice.

FIGS. 11A to 11E show waveforms of vowel sounds a, d, a, o, and u of a voice. The first formant of vowel a in FIG.
z, the second formant is at 2400-3000 Hz. The first formant of vowel D in (b) is 350-55.
0 Hz, the second formant is 1500-2000 Hz,
The third formant is at 2500-3000 Hz, and similarly in the case of the vowel a in (c), 600-800 Hz,
1000-1400Hz, 2700-3100Hz,
In the case of the vowel sound (d), 420-500 Hz, 760-
1000 Hz, 1300 to 2000 Hz, 300 to 480 Hz, 1000 to 1400 H in the case of vowel U of (e)
z, 2000-3000 Hz.

The frequency component that characterizes such a vowel is called a formant. On the other hand, the consonant appears in a transient manner only for a short time, its frequency component is relatively high, and its energy is extremely small. Figure 12 is "CHO"
In the pronunciation waveform of (cho), the part where the amplitude is large and conspicuous is CH
This is the part of the vowel O that follows, and the essential consonant is the fine waveform part that appears at the beginning.

The smallest pronunciational unit that constitutes a word is called a syllable. Most Japanese syllables take the form of (consonant c) + (vowel v), but in foreign languages the structure is complicated and typical syllables are (consonant c) + (vowel v) + (consonant c) Such a structure is adopted. Syllable duration is 100-
At 300 ms, the average is 1/8 second and the inter-syllable pause time is 100-200 ms.

[0014]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
In the system construction example shown in FIG. 1, a general description of a mobile communication system using a TCM signal is given, and the system can be constructed by this, but an explanation of the multiple load gain of a frame-structured TCM signal is given. Not done. Although Document 3 describes the multiple load gain of the TCM signal, the multiple load gain of the frame-structured analog TCM signal is not shown, and the multiplex gain for the digital signal is not shown. It was left.

Further, the multiplexing gain is reduced for a system which adopts a method in which the signal to be transmitted in the TCM signal is not transmitted as it is, but is compared with the signal transmitted in the previous frame and only the changed amount is transmitted. Although the increase is expected, the specific multiplexing gain due to the creation of the differential signal has not been clarified, and has been a problem to be solved.

Further, in Document 4, although the nature of a human voice is described in detail, a digitized telephone signal is divided into time signals and a difference signal which is a temporal change amount thereof is related. There is an unsolved problem that there is no explanation and a method for effectively utilizing the property is not disclosed.

[0017]

When transmitting a digitized telephone signal by TCM-FM, the telephone signal is compared with the previous frame signal for each frame, and only the amount of change in amplitude with time is extracted. It is possible to obtain a large multiple load gain by using a divided telephone signal (hereinafter referred to as a time difference telephone signal) that is compressed in time.

[0018]

The present invention relates to a system in which a signal obtained by digitizing an analog telephone signal is further converted into a TCM. The basic action of the invention lies in the feature of the voice signal which is the original signal of the telephone signal. Therefore, the features of the audio signal will be described below.

FIGS. 11 and 12 show that the same signal is repeated repeatedly when the majority of the duration of the telephone signal is separated by short time intervals (eg 10 ms). This is a case where the telephone signal is divided into time signals and a time difference telephone signal which is the time change is created.
It is shown that the signal often has very few components.

The above-mentioned characteristics are also applicable to a signal obtained by digitizing an analog telephone signal. In other words, the redundancy of the signal is the same as that of the analog telephone signal even in the PCM 64 kbps which is the ISDN telephone signal which is practically used not only in Japan but also in the world. continuing. Therefore, when the digitalized telephone signal is divided into time to create a time piece signal and the time piece signal is transmitted in time series, specifically, the time piece signal transmitted in the immediately preceding frame and the next time piece signal are transmitted. When the time piece signal to be transmitted is compared and only the changed amount is transmitted, there is no signal to be transmitted in the signal having redundancy as described above, that is, a no signal state appears. Since this state appears with a high probability, the power of the transmission signal is reduced.

Such a phenomenon means that the input signal of the angle modulator is lowered, and when the angle modulator is operated at the signal level as it is, the modulated signal is considered to be in a state in which there is very little radio interference on adjacent radio channels. Become. Generally, it is better to use Document 3 to explain this phenomenon. That is, the reduction in the power of the transmission signal means that the signal has multiple load gains. Therefore, it is one way to keep the level of the modulator input signal at the conventional state. Alternatively, increase the level of the modulator input signal and keep the radio interference on the adjacent radio channel at the conventional value. , It becomes possible to reduce the wireless transmission power of itself. That is, power saving can be achieved.

In addition to the above, if the signal to be transmitted this time does not change from the signal transmitted in the immediately preceding frame, the radio wave is not transmitted at all if the transmission including the radio carrier is not performed. Therefore, not only the radio interference on the adjacent radio channel but also the possibility that the radio interference to other systems may occur at all can be eliminated, which is a very desirable state.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1, 2 and 3 show a system configuration for explaining a basic operation example of the present invention.

In FIG. 1, reference numeral 10 is a general telephone network, and 20 is a gateway switch for switching and connecting the telephone network 10 and a wireless system. Reference numeral 30 denotes a wireless base station, which is an interface with the gateway switch 20, a circuit for converting a signal speed, a circuit for allocating and selecting a time slot,
There is a control part etc., besides setting and releasing the wireless line,
The mobile wireless device 100 (100-1 to 100-n) has a wireless transmission / reception circuit for exchanging wireless signals.

Here, the gateway exchange 20 and the radio base station 30
And the communication lines 22-1 to 22-n including the call signals of the call channels CH1 to CHn and the control signals. As a signal flowing through this transmission line,
Signal processing is simplified when a digital signal format is used. In the case of the analog format, analog-digital conversion or inverse conversion is required in the wireless base station 30 or mobile wireless device 100 described below.

FIG. 2 shows a circuit configuration of the mobile radio device 100 which communicates with the radio base station 30. A received signal such as a control signal or a call signal received by the antenna unit is received by the wireless receiving circuit 13 including the receiving mixer 136 and the receiving unit 137.
5, and the output communication signal is the speed restoration circuit 1
38, the control unit 140, and the clock regenerator 141. The clock regenerator 141 regenerates a clock from the received signal and applies it to the speed restoration circuit 138, the control unit 140, and the timing generator 142.

The speed restoration circuit 138 restores the speed of the compressed and delimited communication signal in the received signal and inputs it to the telephone section 101 and the control section 140 as a continuous signal.

The communication signal output from the telephone unit 101 is subjected to analog-digital conversion (hereinafter referred to as AD conversion), and then the speed conversion circuit 131 divides the communication signal into predetermined time intervals to increase the speed. The wireless transmission circuit 13 that includes (compresses) and includes the transmission mixer 133 and the transmission unit 134.
2 is applied.

The output of the modulator included in the transmission unit 134 is converted into a predetermined radio frequency in the transmission mixer 133,
The signal is transmitted from the antenna unit and received by the wireless base station 30.

The modulation degree and the transmission output level in the radio transmission circuit 132 are determined by an instruction from the control unit 140 in consideration of a multiplexing gain described later. Mobile radio 1
Using the time slot that is allowed to use from 00,
In order to send a wireless signal to the wireless base station 30, it is necessary that the timing information from the timing generator 142 shown in FIG. 2 be obtained via the control unit 140.

The timing generator 142 supplies the necessary timing to the transmission / reception interrupt controller 123, the speed conversion circuit 131 and the speed restoration circuit 138 by the clock from the clock regenerator 141 and the control signal from the control unit 140. There is.

The mobile radio 100 further includes synthesizers 121-1 and 121-2 and a changeover switch 122.
-1, 122-2 and changeover switches 122-1 and 122
-2 includes a transmission / reception gating controller 123 and a timing generator 142 that generate signals for switching each of -2, and the synthesizers 121-1 and 121-2, the transmission / reception gating controller 123, and the timing generator 142 are control units. It is controlled by 140. Each synthesizer 121
The reference frequency is supplied to the -1, 121-2 from the reference crystal oscillator 120.

A radio base station 30 is shown in FIG.
N-channel communication signal 22-1 with the gateway switch 20
22 to 22-n are connected to the signal processing unit 31 that forms an interface on the transmission path. Therefore, the communication signals 22-1 to 22-n sent from the gateway switch 20 are transmitted to the wireless base station 30.
Is input to the signal processing unit 31. The signal processing unit 31 includes an amplifier for compensating for transmission loss,
So-called 2-line to 4-line conversion is performed. That is, the input signal and the output signal are mixed and separated, and the input signal from the gateway switch 20 is sent to the signal speed conversion circuit group 51. Further, an output signal from the signal speed restoration circuit group 38 uses the same transmission line as the input signal in the signal processing unit 31 to make the gateway switch 20.
Sent to. Of the above, the input signal from the gateway switch 20 is input to the signal speed conversion circuit group 51 including many signal speed conversion circuits 51-1 to 51-n, and when the input signal is in the analog format, A-D After the conversion, the speed (pitch) conversion is performed at predetermined time intervals. Further, the signal transmitted from the wireless base station 30 to the gateway switch 20 is
The output of the wireless reception circuit 35 is input to the signal speed restoration circuit group 38 via the signal selection circuit group 39, converted in speed (pitch), and input to the signal processing unit 31.

The control of the radio receiving circuit 35 or the output of the call signal is performed by the signal selection circuit group 3 including the signal selection circuits 39-1 to 39-n for selecting the signal for each time slot.
9, and the call signals are separated corresponding to each of the call channels CH1 to CHn. This output is the signal speed restoring circuit group 38 including the signal speed restoring circuits 38-1 to 38-n provided for each channel, and after the signal speed (pitch) is restored, the signal in the gateway switch 20 is In the case of the analog format, the signal is DA converted, input to the signal processing unit 31, subjected to 4-line-2 line conversion, and then the output is sent to the gateway exchange 20 as communication signals 22-1 to 22-n. ..

Next, the function of the signal speed conversion circuit group 51 (FIG. 3) will be described. The input signal such as a voice signal or a control signal, which is divided into a certain time length, is stored in a storage circuit, and the speed is changed when reading the input signal, and the read signal is read at a speed of, for example, 15 times that of the storage time. Can be compressed. The principle of time compression of the signal speed conversion circuit group 51 is the same as that when a signal recorded by a tape recorder is reproduced at high speed, and in the case of a digital signal, an IC memory or the like can be used. An IC memory or the like can also be used for the signal speed restoration circuit group 38.

The control or telephone signal output from the gateway switch 20 via the signal processing unit 31 is input to the signal speed conversion circuit group 51. In the case of an analog signal, AD conversion and speed (pitch) conversion, or In the case of a digital signal, it is applied to a signal allocating circuit 52 which allocates a signal for each time slot after the speed conversion process is performed.

The signal allocating circuit 52 is a buffer memory circuit, and outputs 1 from the signal speed converting circuit group 51.
A high-speed signal corresponding to a delimiter is stored in memory, the signal in the buffer memory is read out by the timing information from the timing generation circuit 42 given by the instruction of the control unit 40, and the signal is sent to the wireless transmission circuit 32. As a result, when the communication signals are viewed as channels, they are arranged in series without overlap in time series, and when all the control signals or call signals described later are implemented, it is as if they were continuous signal waves. become.

The above signals are sent to the wireless transmission circuit 32. The modulation degree and the transmission output level in the wireless transmission circuit 32 are determined by an instruction from the control unit 40 in consideration of a multiplexing gain described later. The state of this compressed signal will be described with reference to FIG.

The output signals of the signal speed conversion circuit group 51 are input to the signal allocation circuit 52 and given time slots in a predetermined order. SD in Figure 4 (a)
, SD2, ..., SDn indicate that the speed-converted communication signals are assigned to each time slot. Here, in one time slot, a synchronizing signal and a call signal or / and a control signal are accommodated as shown in the figure. When the call signal is not installed, an empty slot signal is added to the call signal portion only with the synchronization signal, or in some systems, no signal including the carrier wave is transmitted. In this way, as shown in FIG. 4A, in the wireless transmission circuit 32, a signal forming one frame in the time slots SD1 to SDn is added to the modulation circuit. The multiplex signals that are time-series to be transmitted are angle-modulated in the wireless transmission circuit 32, and then transmitted to the space from the antenna section.

Regarding the transmission of the control signal between the radio base station 30 and the mobile radio 100 prior to the call in the incoming and outgoing call of the telephone, either in the band of the telephone signal or out of the band is used. It is possible. For example, a high frequency as an out-of-band signal (24 for a telephone signal of 32 kbps)
Frequency bands above kHz) can be used. This signal is used, for example, when sending a control signal during a call. The circuit configuration in this case is shown in FIG. Figure 5
Since the voice signal is digitized by the digital encoding circuit 91 and the control signal is also a data signal of digital format in general, it is multiplexed with the digitally encoded telephone signal as shown in FIG. This is an example of application to the modulation circuit included in 32. Then, if the opposite receiver receives the signal and the demodulation circuit performs the reverse operation to that shown in FIG. 5, the audio signal and the control signal can be separately taken out.

On the other hand, the signal sent from the mobile radio 100 is received by the antenna section of the radio base station 30 and input to the radio receiving circuit 35. FIG. 4B schematically shows this upstream input signal. That is, the time slots SU1, SU2, ..., SUn represent transmission signals addressed to the radio base station 30 from the mobile radios 100-1, 100-2, ..., 100-n. Further, the details of each of the time slots SU1, SU2, ..., SUn are made up of a call signal and / or a control signal as shown in the lower left of FIG. However, the synchronization signal can be omitted depending on the case where the distance between the mobile wireless device 100 and the wireless base station 30 is small or the signal speed.

The control signal of the input signals arriving at the radio base station 30 is immediately added to the control section 40 from the radio reception circuit 35. However, depending on the size of the speed conversion rate, it is possible to add the signal from the output of the signal speed restoration circuit group 38 to the control unit 40 after performing the same processing as the call signal. The call signal is applied to the signal selection circuit 39. The signal selection circuit group 39 includes a control unit 4
In response to an instruction from the control signal from 0, a timing signal from a timing generation circuit 42 that generates a predetermined timing is applied, and a synchronization signal, a call signal or a control signal is separately output for each time slot SU1 to SUn.

Each of these signals has a signal speed restoration circuit 38.
Is input to. This circuit has a function of performing inverse conversion of the speed conversion circuit 131 (FIG. 2) in the mobile radio device 100 on the transmission side, whereby the original signal is faithfully reproduced and transmitted to the gateway exchange 20. Become.

The control signal from the control unit 40 is applied to the radio transmission circuit 32 in parallel with the output of the signal allocation circuit 52, as shown in FIG. However, depending on the size of the speed conversion rate, after the same processing as the call signal is performed, the signal allocation circuit 5
It is also possible to add from the output of 2 to the wireless transmission circuit 32.

Next, also in the mobile radio 100, as shown in FIG.
As shown in FIG. 5, the circuit configuration is required when the communication path among the functions of the wireless base station 30 is one channel. Hereinafter, an aspect of transmitting the signal space in the present invention will be described by using a required transmission band and a relationship between the required transmission band and an adjacent wireless channel.

Original signal Digital telephone signal of, for example, 32 kbps (frequency band of signal: 0 to 24 kHz)
Shows the frequency distribution on the output side when passing through the signal speed conversion circuit group 51 (FIG. 3), as shown in FIG. That is, if the speed of the telephone signal is converted 15 times as described above, the frequency distribution of the signal is 0 to 360 as shown in FIG.
It means that it has been expanded to kHz. It should be noted that the frequency distribution of the signal is expanded here, but the shape of the waveform is simply subjected to a similarity transformation in which the frequency axis is stretched, and the waveform itself does not change.

Now, FIG. 6 shows an example in which the control signal is mounted in time series in a part of the time slot SD1 in which the digital telephone signal is mounted (the control signal is the same time slot). Used for control of digital telephone signals contained in. In FIG. 6, the call signal channels # 1 to n are time slots S respectively.
It is housed in D1-n and is shown as a triangle. The frequency distribution of these signals is 0 to 360k.
Hz. On the other hand, the control signal for controlling each call signal is shown by a rectangle. The frequency distribution of these signals is shown to be 0 to 360 kHz.

The relationship between the control signals and the digital telephone signals accommodated in the other time slots SD2 to SDn is the same. These n time slots are arranged in time series to form one frame. Therefore, the signals in a plurality of time slots are not simultaneously applied to the wireless transmission circuit 32.

If a time slot for frame synchronization or the like is provided at the beginning or the end of the frame, the control signal does not include a telephone signal in the control time slot.

When these call signals are added to the angle modulator included in the radio transmission circuit 32 together with the control signal, the required transmission band is at least f _C ± 360 kHz.
Need. However, f _C is a radio carrier frequency. If there are a plurality of wireless channels given to the system, the speedup of signals by the signal speed conversion circuit group 51 is limited to a certain value due to the limitation of these frequency intervals. F is the frequency interval of a plurality of wireless channels
Let _rep be the maximum signal speed f _H due to the speedup of the audio signal described above, and the following inequality must be established between the two. f _rep > 2f _H

In addition, from the mobile radio 100 to the radio base station 3
The control signal input to 0 is input to the wireless reception circuit 35, part of its output is input to the control unit 40, and the other is sent to the signal speed restoration circuit group 38 via the signal selection circuit 39. .. The latter control signal undergoes speed conversion (conversion to a low speed signal) completely opposite to that at the time of transmission, and then the general telephone network 10
The signal speed is the same as that used in the above, and it is sent to the gateway exchange 20 via the signal processing unit 31.

Next, the operation of making and receiving a call in the basic operation of the system according to the present invention will be described by taking the case of a voice signal as an example.

(1) Calling from mobile wireless device 100 This will be described with reference to the flowcharts shown in FIGS. 7 and 8.

When the power of the mobile wireless device 100 is turned on, in the wireless receiving circuit 135 of FIG. 2, the wireless receiving circuit 135 is included in the downlink (wireless base station 30 → mobile wireless device 100) wireless channel (referred to as channel CH1). Start capturing control signals. If the system is provided with multiple radio channels, i) the radio channel showing the maximum received input field ii) the radio channel indicated by the control signals contained in the radio channel iii) Within the radio channel , The wireless channel (hereinafter referred to as channel CH1) is being received according to the procedure defined in the system, such as the channel having an empty time slot. This is the time shown in Fig. 4 (a).
This is possible by capturing the sync signal in the slot SDn. The control unit 140 sends a control signal to the synthesizer 121-1 so as to generate a local oscillation frequency that enables reception of the radio channel CH1, and also switches 12
2-1 is also in a state of being tilted and fixed to the synthesizer 121-1 side.

Then, the telephone receiver of the telephone unit 101 is turned off.
When hooked (beginning of call) (S201, FIG. 7), the synthesizer 121-2 of FIG. 2 receives from the control unit 140 a control signal for generating a local oscillation frequency that enables transmission of the radio channel CH1. Further, the switch 122-2 is also tilted to the synthesizer 121-2 side to be in a fixed state.
Next, the call control signal output from the telephone unit 101 is transmitted using the radio channel CH1. This control signal is
The frequency band shown in FIG. 6 is used for transmission, for example, using the time slot SUn.

This control signal is transmitted in the time slot S
It is limited to only Un and is sent in bursts and no signal is sent in other time zones, so that it does not adversely affect other communications. However, if the speed of the control signal is relatively low, or if the amount of information in the signal is large and cannot be accommodated in one time slot, the same time of one frame later or the next frame Sent using slots.

Now, the call control signal from the mobile wireless device 100 is properly received by the wireless base station 30, and the mobile wireless device 10 receives.
If an ID (identification number) of 0 is detected (S20
2) The control unit 40 searches for a currently empty time slot.

As a result, for example, time slot SD
1 is available, the time slot SDn of the radio channel CH1 is used for the mobile radio device 100 and the time slot ascending (the mobile radio device 10) by the downlink control signal.
0 → Radio base station 30) SU1, and the corresponding downlink (radio base station 30 → mobile radio 100) SD1 is instructed to be used (S203). In response to this, the mobile wireless device 100 shifts to a state in which it can be received at the instructed time slot SD1 and SU1 which is a time slot for the uplink radio channel corresponding to the downlink time slot SD1 (see FIG. Select b)). At this time, in the control unit 140 of the mobile wireless device 100, the transmission / reception gating controller 123 is operated to turn on the switch 122-1.
And 122-2 are started to operate (S204). At the same time, a slot switching completion report is sent to the radio base station 30 using the uplink time slot SU1 (S205),
Wait for dial tone (S20)
6).

The radio base station 30 has a time slot S
In addition to U1, SU3 and SUn are included in one frame and transmitted as an upstream signal from another mobile radio 100. The radio base station 30 that has received the slot switching completion report (S207) sends a calling signal together with the ID of the mobile radio 100 to the gateway switch 20 (S20).
8). On the other hand, in the gateway switch 20, the mobile radio 10
The ID of 0 is detected, and a necessary switch of the switch group included in the gateway switch 20 is turned on (S209),
The dial tone is transmitted to the wireless base station 30 (S21).
0, FIG. 8). This dial tone corresponds to the radio base station 30.
Is transferred to the mobile wireless device 100 (S211), and the mobile wireless device 100 confirms that the communication path has been set (S212).

When this state is entered, the mobile wireless device 100
Since a dial tone is heard from the handset of the telephone section 101, the transmission of the dial signal is started. This dial signal is subjected to speed conversion by the speed conversion circuit 131, and the wireless transmission circuit 13 including the transmission unit 134 and the transmission mixer 133.
From 2, the data is transmitted using the upstream time slot SU1 (S213). Thus, the transmitted dial signal is received by the wireless reception circuit 35 of the wireless base station 30.

In the radio base station 30, the mobile radio 1
In response to the call signal from 00, the time slot to be used is given, and the signal selection circuit group 39 and the signal allocation circuit group 52 of the radio base station 30 are operated to receive the upstream time slot SU1. , The downlink time slot SD1 signal is being transmitted. Therefore, the dial signal transmitted from the mobile wireless device 100 passes through the signal selection circuit 39-1 of the signal selection circuit group 39 and is then input to the signal speed restoration circuit group 38, where the original transmission signal is restored, The call signal 22-1 is transferred to the gateway exchange 20 via the signal processing unit 31 (S21).
4) The call path to the telephone network 10 is set (S21).
5).

On the other hand, an input signal (initially a control signal, a call signal if a call is started) from the gateway switch 20 is subjected to speed conversion by the signal speed conversion circuit group 51 in the radio base station 30, and then the signal allocation circuit. Signal allocation circuit 52-1 of group 52
Is given a time slot SD1. Then, the time of the downlink radio channel from the radio transmission circuit 32
It is transmitted to the mobile wireless device 100 using the slot SD1.

In the mobile radio 100, the radio channel CH
In the time slot SD1 of No. 1, the reception is awaited, and it is received by the radio reception circuit 135, and its output is input to the speed restoration circuit 138. In this circuit, the original signal on the transmitting side is restored and input to the handset of the telephone unit 101.
Thus, a call is started between the mobile wireless device 100 and the ordinary telephone in the ordinary telephone network 10 (S21).
6).

The end of the call is the telephone section 101 of the mobile radio 100.
By hooking the handset of the mobile phone (S217),
The end signal and the on-hook signal from the control unit 140
The signal is transmitted from the wireless transmission circuit 132 to the wireless base station 30 via the speed conversion circuit 131 (S218), the control unit 140 stops the operation of the transmission / reception interrupt controller 123, and the switches 122-1 and 122- 2 is fixed to the output terminals of the synthesizers 121-1 and 121-2, respectively.

On the other hand, in the control unit 40 of the radio base station 30,
When the call end signal from the mobile wireless device 100 is received, the call end signal is transferred to the gateway switch 20 (S219), the switches of the switch group (not shown) are turned off to end the call (S).
220). At the same time, the signal selection circuit group 3 in the radio base station 30
9 and the signal allocation circuit group 52 are opened.

In the above description, the control signals are exchanged between the radio base station 30 and the mobile radio 100 without passing through the signal conversion circuit group 51, the signal speed restoration circuit group 38, etc., but this is explained. For the sake of convenience, the signal speed conversion circuit group 51 and the signal speed restoration circuit group 38 are the same as those for the audio signal.
Communication can be performed without any trouble through the signal processing unit 31 and the signal processing unit 31.

(2) Incoming call to the mobile wireless device 100 It is assumed that the mobile wireless device 100 is on standby while the power is on.
In this case, as described in the section of calling from the mobile radio 100, the downlink control signal of the radio channel CH1 according to the procedure defined by the system is in the standby state.

An incoming call signal from the general telephone network 10 to the mobile radio 100 via the gateway switch 20 is transmitted to the radio base station 30.
Suppose you have arrived. Similar to the voice signal, these control signals pass through the signal speed conversion circuit group 51, and are transmitted to the control unit 40 (FIG. 3) through the signal allocation circuit group 52, similarly to the voice signal. Then, the control unit 40 uses the empty slot of the downlink time slot of the radio channel CH1 addressed to the mobile wireless device 100, for example, SD1, to move the mobile wireless device 10
0 ID signal + incoming call signal display signal + time slot use signal (for example, for transmission from the mobile radio 100, S
Use SU1 corresponding to D1). In the mobile wireless device 100 that receives this signal, the signal is transmitted from the receiving unit 137 of the wireless receiving circuit 135 to the control unit 140. Control unit 1
At 40, since it is confirmed that this signal is an incoming call signal to the mobile radio device 100 of its own, the telephone unit 101 sounds a ringing tone, and at the same time, it waits at the instructed time slot SD1, SU1. Transmission / reception intermittent controller 1
23, and switches 122-1 and 12
Turn on and off 2-2. Thus, the call is ready to be made.

Note that it is theoretically explained in Document 2 that signal transmission is executed in good condition using this system and that it does not adversely affect other radio channels in the system. The multiplexing gain obtained when the digital signal of the present invention is time-compressed and the gain added by creating the time difference telephone signal will be described in the following order.

(3) Multiplexing gain of time-compressed digital signal (3.1) Multiplexing gain when compared with FDM (Frequency Division Multiplexing) signal (4) Time difference Time difference signal generated by making telephone signal Gain (4.1) Average power of digital signal (4.1.1) Average power of digital signal with normal pulse train occurrence probability (4.1.2) Average power of digital signal with low pulse train occurrence probability (4) .2) Advantages of digital signal with low average power (4.3) Creation of digital signal with low probability of pulse train generation and creation of time difference telephone signal (4.4) Adoption of power reduction effect of signal by creation of time difference signal System example (5) Method of creating time difference signal for digital telephone signal

(3) Multiplexing gain of time-compressed digital signal (3.1) Multiplexing gain when compared with FDM (Frequency Division Multiplexing) signal A multiplex signal is obtained from n digitized telephone signals. When creating it, the case of TDM (time division multiplex) signal,
Comparing the peak values of both signals in the case of FDM (Frequency Division Multiplexing) signals, the TDM signal has a peak value of 1/100 as compared to the FDM signal, as described in Document 3.
√n smaller. Therefore, the multiplexing gain G ₁ in this case obtains G ₁ = ₁₀ log ₁₀ n.

In addition to this multiplexing gain G ₁ , a frequency effective gain G _f by time compression multiplexing is obtained. This is because the guard band existing between wireless carriers is effectively used. The degree of effective use is as described in Reference 1, and is about 60% at maximum (about 2 dB).

When the digitized telephone signal is multiplexed, not when it is compared with the FDM signal but when it is compared with another time division multiplexed signal having a different multiplicity, the above multiplexing gain G ₁ is I can't get it. In this case, there is only the frequency effective gain G _f with the increase of the multiplicity.

(4) Time difference signal gain due to creation of time difference telephone signal (4.1) Average power possessed by digital signal (4.1.1) Average power possessed by digital signal having normal pulse train occurrence probability Analog telephone signal At (highest frequency f _h ), etc., a pulse train having a repetition frequency of 2 f _h or more is taken, and a sample value is sent by the pulse train, whereby the original information signal can be completely restored. Various modulation methods are conceivable for changing the parameters of the pulse train according to the sample value, and the pulse code modulation (PCM) will be described below as an example.

The PCM coder for ordinary telephone signals samples a voice signal at 8 kHz and then encodes it with 8 bits per sample value. As a result, the signal rate becomes 64 kbps.

Now, the average power of the above pulse code modulated telephone signal is obtained. The peak value when a pulse is output is a. When the pulse is not output, the peak value is 0, and normally the average power of the pulse code modulated telephone signal is the probability (p) when the pulse is output.
And the probability (q) when not output is 1/2,
Since it is 1/2, the average power P (1/2) is P (1/2) = (1/2) a ² × (1/2) = (1/4) a ² (1)

(4.1.2) Average Power of Digital Signal with Low Probability of Generation of Pulse Train The probability of generation of pulse train is reduced by taking some measures in the digital signal of the telephone signal which is pulse code modulated. Suppose That is, it is assumed that the frequency with which the pulse is output is reduced and the frequency with which the pulse is not output is increased. Then, the average power of the signal is reduced.

The average power of a digital signal having a low probability of occurrence of a pulse train will be examined below. The target digital modulation format is pulse code modulation (PCM) as in (4.1.1).

I) p = 1/10, q = 9/10 Average power P (1/10) of the digital signal in this case
P (1/10) = (1/2) a ² × (1/10) = (1/20) a ² (2) Equation (2) has an average power of 1 / (1) compared to Equation (1). It can be seen that the number has dropped to 5.

Ii) p = 1/20, q = 19/20 Average power P (1/20) of the digital signal in this case
P (1/20) = (1/2) a ² × (1/20) = (1/40) a ² (3) Equation (3) has an average power of 1 / (1) compared to Equation (1). It can be seen that it has dropped to 10.

(4.2) Advantages of Digital Signal with Low Average Power The advantages of the digital signal with low average power are as follows.

Generally, in mobile wireless communication using angle modulation, the amount of modulation deviation decreases when the voltage (power) of the signal applied to the modulation is low. Therefore, when adjacent wireless channels exist, the amount of radio wave interference is reduced or eliminated.

When the voltage (power) of the signal applied to the modulation is increased in order to prevent the modulation shift amount of (3) from decreasing, the S / N when the modulation signal is received is improved.

Instead of improving the S / N of, the transmission power can be reduced until the S / N at the time of reception becomes the same value as before. That is, the transmission power can be reduced.

The reason why the above merit is to be utilized is that mobile mobile radios for portable use have recently been widely used, and in this case, there is a great need for reduction in size and weight which are convenient for carrying. That is, if it is possible to reduce the transmission power of the portable mobile radio device, the battery can be downsized, which will greatly contribute to the reduction in size and weight of the portable device.

(4.3) Creation of Digital Signal with Low Probability of Pulse Train and Creation of Time-Differentiated Telephone Signal In the following, it will be examined whether it is possible to create a digital signal with low probability of occurrence of pulse train. Take a telephone signal as an example. If the original signal before digitization, such as a telephone signal, has redundancy, removing this redundancy can equivalently produce gain. Therefore, the basic function is the characteristic of the voice signal which is the original signal of the telephone signal. Therefore, the features of the analog audio signal will be described below.

FIG. 9 (a) shows the signal "a" shown in FIG. 11 (a), and FIG. 9 (b) shows the time difference created from the signal by using the temporally adjacent time piece signals. An example of a telephone signal is shown. That is, the vowel "a" in FIG. 9 (a) (about 220 ms in total time) is cut every 10 ms to form a time piece signal, and the time difference telephone signal in FIG. 9 (b) is created and arranged in a line. Is. However, it is assumed that the pulse noise generated at the time of shifting from one time piece signal to the next time piece signal is removed. The following can be seen from FIGS. 11, 12 and 9.

1) Time difference The amplitude of the telephone signal becomes large only when the short-time amplitude width change of the original telephone signal is large, and the amplitude is extremely small at other times.

2) Since the time length of the time piece signal is about 1 to 30 ms, it is a time length suitable for catching a minute change of the audio signal. As is clear from FIG. 11 and FIG. 12, except for a part of temporally adjacent time piece signals, their signal waveforms are almost the same.

3) Therefore, the following can be generally said as the characteristics of the time difference telephone signal generated by using the time piece signals that are temporally adjacent to each other. First, 50% or more is almost no signal, that is, an empty signal containing no component. Most of the remaining 50% or less have a small signal power except some.

The above is the case where the analog time piece signal is created from the voice signal which is the original signal of the telephone signal. Next, the characteristics when a digital signal is created will be described. However, the time length of the time piece signal is set to about 1 to 30 ms like the analog signal.

The signal format of the digital signal time piece signal is almost the same except when the amplitude of the original telephone signal changes.

Therefore, in many cases, the signal formats of digital signal time piece signals created using time piece signals that are temporally adjacent are the same.

Therefore, in the case of, the time difference signal of the signal becomes no signal. Further, in the case of, when the signal is not completely the same but is almost the same, the signal corresponding to the change amount is output, and the pulse generation rate of the signal becomes a value smaller than 50%.

(4.4) Example of System Employing Power Reduction Effect of Signal by Creating Time Difference Signal Hereinafter, the radio transmission power is reduced by utilizing the power reduction effect of the transmission signal obtained by creating the time difference signal. An example of a system aiming at this will be described.

Taking i) described in (4.1.2) as an example, since the average power of the signal has dropped to 1/5, the level is raised to the original average power and the angle modulator I will add it to. This increases the modulation depth of the angle modulator to 5
This means increasing the dB. Then S / N is 5d
B is improved. 5d transmission power instead of this improvement
Used to reduce B. Thus, the transmission power is 5
It can be seen that the dB can be reduced.

Similarly, taking ii) described in (4.1.2) as an example, it can be seen that the transmission power can be reduced by 10 dB.

(5) Method for creating time difference signal for digital telephone signal Next, the method for creating the time difference telephone signal described above will be described with reference to FIG.
Will be explained. FIG. 10 shows the mobile wireless device 10 shown in FIG.
0 configuration, speed restoration circuit 138, telephone unit 101
And the internal structure of the speed conversion circuit 131 are respectively shown.

In FIG. 10, the radio receiving circuit 1 is shown from the right side.
The compressed digital time difference telephone signal (difference signal) from 35 is input. This input signal is switch 16
5, the telephone signal storage circuit 161-1 or 161 is provided for each time slot (one for each TCM frame unit).
-2 are input and stored respectively. In addition, switch 1
The timing of switching the terminals a and b of 65 is performed by a signal from the timing generator 142. The signal stored here is then read out and restored to the original telephone signal rate by the time expansion circuit 162-1 or 162-2.
Then, the restored telephone signal is still in the form of a staggered telephone signal, and the switch 166-1 or 166-
It is input to the telephone signal reproduction circuit 163-1 or 163-2 by switching between the two terminals a and b (this timing also depends on the signal from the timing generator 142). here,
The time difference telephone signal (difference signal) is added to the signal in the time slot of the immediately preceding frame, and the original telephone signal for one frame is reproduced. And switch 167
The telephone signal reproducing circuit 1 is switched by switching terminals a and b of the telephone (this timing also depends on the signal from the timing generator 142).
The outputs of 63-1 or 163-2 are alternately taken out and sent to the D / A conversion circuit 108 of the telephone section 101.

The left side of FIG. 10 shows the internal construction of the telephone section 101, which includes a control section 140 and a telephone control circuit 105.
Control signals are exchanged between the two. Further, the D / A conversion circuit 108, the A / D conversion circuit 109, the reception circuit 106, and the transmission circuit 107 operate by receiving a signal from the clock reproduction circuit 141.

The internal structure of the speed conversion circuit 131 is shown in the lower part of FIG. 10, and the telephone signal in digital format output from the transmission circuit 107 of the telephone unit 101 is sent to the telephone by the switch 175 via the A / D conversion circuit 109. Telephone signal storage circuit 171-1 or 1 for each frame of signal
71-2 are input and stored respectively. The timing of switching the terminals a and b of the switch 175 is performed by a signal from the timing generator 142. The signal stored here is read out and the switch 176-1 or 176 is read.
-2 terminals a and b are switched (this timing also depends on the signal from the timing generator 142) to be input to the difference signal generation circuit 172-1 or 172-2, where the telephone signal is the frame immediately before that. Is subtracted (takes a difference) from the telephone signal of (1) to be converted into a time difference telephone signal. Then,
The time difference telephone signal thus converted is converted into the time compression circuit 173-.
1 or 173-2. Then, by switching the terminals a and b of the switch 177 (this timing also depends on the signal from the timing generator 142), the wireless transmission circuit 132 is provided for each time slot of the TCM signal (one is given for each TCM frame unit). Sent to.

In the wireless transmission circuit 132 (FIG. 2), the signal is frequency-modulated at a signal level in consideration of the gain due to the time difference telephone signal, and then sent to the transmission mixer 133. Transmission mixer 13
In 3, the frequency-modulated TCM-converted telephone signal becomes one modulated signal wave having the designated carrier frequency and is sent from the antenna to the radio base station 30.

Next, the operation of the radio base station 30 will be described. Among the configurations of the radio base station 30 shown in FIG. 3, the internal configurations of the signal speed restoration circuit group 38 and the signal speed conversion circuit group 51 are different except that signals are transmitted and received at the same time as a large number of mobile wireless devices. For example, it has substantially the same functions as the speed restoration circuit 138 and the speed conversion circuit 131 of the mobile wireless device 100.

As is clear from the above description, the method for creating a time difference telephone signal is easy, and if it is introduced into an actual system, it is possible to obtain a gain by a time difference telephone signal of about 5 dB or more. This can be used to reduce the transmission power.

The above is the utilization of the gain by creating the time difference signal for the digital telephone signal. The operation of the present invention can be applied not only to the telephone signal but also to any signal as long as the signal generally has redundancy.

It should be noted that increasing the modulation depth of the angle modulator may result in increased radio interference to adjacent radio channels. However, there is no particular problem in practice due to the following reasons.

The energy of the signal included in the time difference signal is generally not so large, and the probability of a large signal is small. This is also true for adjacent radio channels, and therefore the probability that signals with large energy in the time difference signals will simultaneously collide is quite small.

By increasing the modulation depth of the digital telephone signal converted into the time difference signal, the resistance against the radio interference received from the adjacent radio channel as well as the radio interference received from other communication and noise is increased.

It is necessary to determine the optimum value by comparing the merit of (1) with the magnitude of interference, but generally the merit is greater.

Strictly speaking, it is necessary to carry out an experiment by giving specific system parameters and to determine appropriate specifications (modulation depth).

Depending on the signal configuration method, when a digital signal having a high probability of occurrence of a pulse train is created by removing the redundancy, the complement is used to generate a pulse train similar to the above. A digital signal with a low probability will be created. That is, it suffices to reverse the generation and non-generation of pulses.

[0112]

As is apparent from the above description, when a telephone signal in digital signal format is transmitted after being converted into a TCM, it is not transmitted as it is, but a time difference signal is created and transmitted, thereby transmitting a transmission signal. Can increase the level of the signal applied to the modulator to the conventional power level by using the feature that the power of the signal is reduced when there is redundancy like a telephone signal, resulting in a deeper modulation depth of the modulator. This makes it possible to secure the same transmission quality as the conventional one, even if the transmission power is lower than the conventional one. Also,
The frequency can be effectively used by operating the signal level slightly lower than the conventional power level. Therefore, in mobile radio systems, reduction in transmission power of portable radios in particular contributes to reduction in battery capacity and eventually to miniaturization. Therefore, the effect of the present invention is extremely large.

[Brief description of drawings]

FIG. 1 is a conceptual configuration diagram showing a concept of a system of the present invention.

FIG. 2 is a circuit configuration diagram for explaining a basic operation of a mobile wireless device used in the system of the present invention.

FIG. 3 is a circuit configuration diagram for explaining a basic operation of a radio base station used in the system of the present invention.

FIG. 4 is a time slot structure diagram for explaining a basic function of a time slot used in the system of the present invention.

FIG. 5 is a circuit configuration diagram for multiplexing a voice signal and a data signal.

FIG. 6 is a spectrum diagram showing spectra of a call signal and a control signal.

FIG. 7 is a flow chart showing a flow of basic operation of the system according to the present invention.

8 is a flow chart showing a flow of basic operation of the system according to the present invention together with FIG. 7.

9 is a waveform diagram showing a time difference signal waveform (b) used in the present invention, which is obtained from the signal waveform (a) of FIG.

10 is a detailed circuit configuration diagram of a speed restoration circuit, a telephone unit, and a speed conversion circuit, which are the constituent elements of FIG.

FIG. 11 is a waveform diagram of a vowel.

FIG. 12 is a waveform diagram of a consonant and a vowel (cho).

[Explanation of symbols]

 10 Telephone Network 20 Gateway Switch 22-1 to 22-n Communication Signal 30 Radio Base Station 31 Signal Processing Unit 32 Radio Transmission Circuit 35 Radio Reception Circuit 38 Signal Speed Restoration Circuit Group 38-1 to 38-n Signal Speed Restoration Circuit 39 Signal Selection circuit group 39-1 to 39-n 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 allocation circuit group 52-1 .About.52-n signal allocation circuit 91 digital encoding circuit 92 multiplex conversion circuit 100, 100-1 to 100-n mobile radio 101 telephone unit 105 telephone control circuit 106 receiver circuit 107 transmission circuit 108 D / A conversion circuit 109 A / D conversion circuit 120 Reference crystal oscillator 121-1, 121-2 Synthesizer 122-1, 122-2 Switch 123 Transmission / reception gating controller 131 Speed conversion circuit 132 Radio transmission circuit 133 Transmission mixer 134 Transmission section 135 Radio reception circuit 136 Reception mixer 137 Reception section 138 Speed restoration circuit 141 Clock regenerator 161-1, 161-2 Telephone signal storage circuit 162 -1,162-2 Time expansion circuit 163-1, 163-2 Telephone signal reproduction circuit 165, 166-1, 166-2, 167 Switch 171-1, 171-2 Telephone signal storage circuit 172-1, 172-2 Difference signal generation circuit 173-1, 173-2 Time compression circuit 175, 176-1, 176-2, 177 switch

Claims (2)

[Claims] 1. A radio base means (30) which covers a plurality of zones to form a service area, and a digital signal which moves across the plurality of zones and is multiplexed with the radio base means. For exchanging communications with each mobile radio means (100) using a radio channel in which a delimited signal, which is time-compressed into time slots of a frame structure to modulate and modulate a radio carrier for communication. In a time division communication method for mobile communication using an exchange means (20), a difference signal which is a change from the previous frame is obtained for each frame in the temporally compressed delimited signal. , A time division communication method for mobile communication, wherein the level of a transmission signal between the radio base means and the mobile radio means is determined based on the level of the difference signal. 2. The time division communication method for mobile communication according to claim 1, wherein the wireless carrier is not transmitted in a time slot when the level of the difference signal is substantially small enough to be ignored.