JP2531250B2 - Cordless telephone device for mobile communication - Google Patents

Description

The present invention relates to a cordless telephone device for mobile communication, in particular, a mobile station of a base station for mobile telephones mounted on a mobile body such as an automobile and utilizing a public telephone network. The present invention relates to a mobile communication telephone device for performing telephone communication.

[Prior Art] In recent years, a mobile station mounted on a moving body such as an automobile or a train is connected to a base station which is a fixed station by wireless communication, and the base station uses a public telephone network to perform telephone communication. The mobile telephone communication for performing is widely used.

Further, as the mobile station, there is a cordless telephone device consisting of a master unit and a slave unit connected by wireless communication, and the advantage that the telephone device can be used not only inside the vehicle but also outside the vehicle. Because it has, it is becoming widespread.

Hereinafter, a cordless telephone device for mobile communication, for example, a cordless telephone device for a car telephone will be described.

First, FIG. 2 shows a schematic diagram of an automobile telephone communication system.

In the figure, 10a, 10b are mobile stations, and 20a, 20b, 20c
Is a base station for car telephone, 30 is the base station 20a, 20b,
Reference numeral 40 is a base control station for controlling each of the 20c, and 40 is an exchange for car telephones. As shown in the figure, the car phone service area SA consists of multiple small wireless zones with a radius of 5 to 20 km.
It is divided into a, b, and c, and each small wireless zone a, b, c is provided with a car telephone base station 20a, 20b, 20c, respectively. At this time, primary (uplink (from the mobile station to the base station)) and downlink (from the base station to the mobile station) line between each of the base stations 20a, 20b, 20c and each of the mobile stations 10a, 10b The carrier frequency is set so that the adjacent small radio zones a, b and c do not use the same frequency, and the same small radio zones a, b and c do not use the same primary carrier frequency at the same time. To be done.

Next, transmission / reception of the primary transmission signal between the mobile station 10a and the base station 20a will be described.

First, when the telephone device of the mobile station 10a is put into the off-hook state, the base station 20a selects the idle primary carrier frequency f _1t for the uplink in the wireless zone a, and the primary carrier frequency f
A signal instructing _1t is transmitted to the mobile station 10a. At this time, the downlink primary carrier frequency f _1r is automatically set to a value having a constant frequency difference from the f _1t .

In response to this, the mobile station 10a exchanges a primary transmission signal such as a dial signal and a voice signal based on the carrier signal of the primary carrier frequency f _1t and transmits it to the base station 20a. Through the car telephone exchange 40, the general public telephone network NW can be used to perform telephone communication with a desired party.

On the other hand, the voice signal from the called party, contrary to the operation described above,
The base station 20a converts the signal into a primary transmission signal having a primary carrier frequency _f1r and transmits the primary transmission signal to the mobile station 10a.

In this way, the mobile station 10a can perform telephone communication via the base station 20a, the base control station 30, and the car telephone switching center 40.

The base station 20a transmits and receives a primary transmission signal to and from the mobile station 10a, monitors the reception quality of the primary transmission signal from the mobile station 10a, and when the reception quality falls below a certain value, the mobile station 10a As a departure from the current small wireless zone a, the base stations 20b and 20c of the adjacent small wireless zones b and c are requested to monitor the reception quality with the mobile station 10a via the base control station 30, respectively.

Then, the base control station 30 determines that the base station with the highest reception quality (in the example of FIG. 2, the base station 20
c) and select 1 of the mobile station 10a via the currently connected base station 20a.
The next carrier frequency is changed from f _1t , f _1r to an empty frequency of the selected base station 20c, for example, f _3t , f _3r .

Therefore, the mobile station 10a can always perform telephone communication even if it freely moves in each of the small wireless zones a, b, c of the service area SA.

 Next, the mobile station 10 will be described with reference to FIG.

The mobile station 10 includes a base unit 100 and a handset unit 120 that are connected by wireless communication to establish a cordless path.

The master unit 100 has a primary transceiver 102 that transmits and receives a primary transmission signal to and from a base station (not shown), and a slave unit 120.
And a parent-side transceiver 104 that transmits and receives a secondary transmission signal, a primary-secondary signal conversion unit 106 that converts a primary transmission signal received from the base station into a secondary transmission signal, and the parent-side transceiver 104. Secondary to convert the secondary transmission signal received in
The primary signal conversion unit 108.

The slave unit 120 also has a slave transceiver 122 that transmits and receives a secondary transmission signal to and from the master unit 100, and a voice / secondary signal conversion unit 126 that converts a dial signal and a voice signal into a secondary transmission signal.
And a secondary / audio signal conversion unit 124 for converting the secondary transmission signal received from the master unit 100 into an audio signal.

Therefore, if such a telephone is used, it is possible to carry out a cordless call not only in a car, but also in a range of a radius of about 10 m to 20 m from the base unit 100 to bring the handset unit 120 out of the car for telephone communication. It will be possible.

Further, the cordless telephone device as described above includes one in which the secondary carrier frequency of the secondary transmission signal is fixed and one in which the secondary carrier frequency signal is selected from a plurality of types of frequencies.

The latter telephone device is a telephone device with a carrier sensor function, and when starting communication, the secondary carrier frequency that is already used in the communicable area between the base unit and the base unit (range of about 10 to 20 m from the base unit) is set. This is to detect and select an unused frequency as a secondary carrier frequency from a plurality of preset frequencies, and to prevent interference when a plurality of cordless telephones are fixedly arranged at close positions. It has the advantage of not doing it.

In order to obtain the matching of the secondary carrier frequency between the master unit 100 and the slave unit 120 at this time, the slave unit 120 detects the secondary carrier frequency transmitted from the master unit 100 and automatically Then, the transmission secondary carrier frequency of the slave unit 120 is controlled.

[Problems to be Solved by the Invention] However, since the conventional cordless telephone device for mobile communication is mounted on a moving body such as an automobile, even if the telephone device with the carrier sensor function described above is connected after the line connection. Since the secondary carrier frequency is fixed, there is a problem that interference occurs when approaching another mobile station that is talking on the same secondary carrier frequency.

The present invention has been made to solve the above problems, and an object of the present invention is to avoid interference interference peculiar to a cordless telephone device for mobile communication.

[Means for Solving the Problem] In order to achieve the above object, in the mobile communication cordless telephone device according to the present invention, the size of the communication area between the master unit and the slave unit is the size of the small wireless zone. Much smaller than
Focusing on that the range in which the above-mentioned interference is likely to occur is within the same small radio zone and that there is no mobile station with the same primary carrier frequency signal in the same small radio zone, Primary carrier frequency monitoring means for monitoring an uplink transmission carrier frequency or a downlink reception carrier frequency between the station and the master unit, and between the master unit and the slave unit based on the primary carrier frequency. Original secondary carrier frequency calculating means for calculating and updating the original secondary carrier frequency FL, which is the basis for determining the secondary carrier frequency, and the calculated original secondary carrier frequency FL and usable secondary carriers Transmission 2 to transmit to the handset unit using the preset frequencies F2 and F3 considering the frequency band
The secondary carrier signal Ft is calculated by Ft = FL + F2, and the received secondary carrier frequency Fr received from the slave unit is calculated by Fr = FL−F3, and the secondary transmission signal between the master unit and the slave unit is calculated. And secondary signal generating means for generating.

[Operation] Since the cordless telephone device for mobile communication according to the present invention is configured as described above, the secondary cord between the master unit and the slave unit is based on the primary carrier frequency between the base station and the mobile station. Since the carrier frequency is determined, the secondary carrier frequencies do not overlap in the communicable range between the master unit and the slave unit, and the interference peculiar to the cordless telephone device can be avoided.

Further, since the device of the present invention constantly monitors the primary carrier frequency, when the mobile body moves to another small radio zone, the secondary carrier frequency is changed according to the updated primary carrier frequency. Therefore, even if the mobile station moves to another small radio zone, interference can be avoided.

[Embodiment] A preferred embodiment of the present invention will be described below with reference to the drawings.

In this embodiment, an example in which the present invention is applied to a low power cordless telephone device for a car telephone will be described.

In the cordless telephone device, in order to make the transmission / reception secondary carrier frequency of the pre-transceiver correspond to the secondary carrier frequency of the master transceiver, it is transmitted from the master unit.
It is well known that the secondary carrier frequency of the next transmission signal is detected and the child side frequency is automatically determined.
In this embodiment, the configuration and operation of the master unit will be mainly described.

FIG. 1 is a block diagram of a master unit of a cordless telephone device for mobile communication according to this embodiment.

Further, in the figure, the same parts as those in the conventional example shown in FIGS. 2 and 3 are designated by the same reference numerals, and detailed description thereof will be omitted.

As shown in FIG. 1, the feature of the device of this embodiment is that the primary carrier frequency f _1t that is the uplink transmission carrier frequency between the base station (not shown) and the master unit is monitored. The carrier frequency monitoring means 200 and the secondary carrier frequency between the master unit and the slave unit are calculated and updated each time based on the primary carrier frequency, and the master unit is based on the carrier of the calculated secondary carrier frequency. Primary / secondary carrier frequency calculation unit 300 that generates a secondary transmission signal between the slave unit and slave unit, and converts the primary transmission signal into a secondary transmission signal based on the output of the original secondary carrier frequency calculation unit 1 Secondary / Secondary signal converter 10
6 and a secondary / primary signal conversion unit 108 for converting a secondary transmission signal into a primary transmission signal based on the output of the original secondary carrier frequency calculation unit 300.

In this embodiment, the original secondary carrier frequency calculation unit 300,
The secondary / 1 / 2-order signal conversion unit 106 and the secondary / first-order signal conversion unit 108 form the secondary carrier frequency calculation means of the present invention.
In addition, as the secondary signal generating means of the present invention, a master side transceiver
A 104 and a child transceiver 122 are provided.

Then, the primary carrier frequency monitoring means 200
A sensor 202 for detecting the primary transmission wave output by the next transceiver 102, an amplifier 204 for amplifying the transmission wave picked up by the sensor 202, a counter 206 for detecting the carrier frequency of the transmission wave, and a count value of the counter. And a controller 210 for controlling writing to the time base register of the counter 206.

The original secondary carrier frequency calculation unit 300 includes a reference frequency oscillator 302, a VCO (voltage controlled oscillator) 304, and a frequency divider 306.
, Phase detector 308, low-pass filter 310
And a mixer 312 and a fixed frequency oscillator 314. The reference frequency oscillator 302 divides the crystal oscillator to generate a reference frequency. The frequency used by the cordless telephone is 380.2125- 380.31
The reception secondary carrier frequency of the base unit is set to 253.8625 ~ 2 at 25MHz.
The transmission / reception secondary carrier frequency can be set at 54.9625 MHz with a channel interval of 12.5 KHz.

Below, the current mobile phone service frequency band (925.00
The operation of the apparatus of this embodiment at 0 to 940.000 MHz will be described.

First, in the primary carrier frequency monitoring means 200, 1
The next carrier frequency is detected, and the output value of the counter 206 is stored in the register 208.

Here, an ordinary base station is operated at an interval of 25 channels (the interval of one channel is 12.5 KHz) due to technical restrictions, and the interval of the frequency used by one base is 12.5 KHz x 25 = 312.5 KH.
It is assigned to z. Therefore, the time base is 3.2μ
When the transmitted wave is counted as sec (the reciprocal of 312.5KHz), for example, the transmitted carrier frequency of 925.3125MHz is 925.3125 × 3.2.
= 2961 is output as a count. Similarly, 925.625MHz (= 92
At 5.3125MHz + 312.5KHz), the count is output as 2962.

Next, the original secondary carrier frequency calculator 300 calculates and outputs the original secondary carrier frequency FL as follows.

That is, the calculation unit 300 uses the frequency divider 306 to divide the oscillation output frequency F0 of the VCO (voltage controlled oscillator) 304 into, for example, 2961 described above.
It operates so that the value divided by is 12.5 kHz.

Then, when the output frequency and phase of the frequency divider 306 do not match the reference frequency of 12.5 kHz in the phase detector 308, a pulse corresponding to the difference is output, and the frequency F0 of the VCO 304 is F0 / N = As a result of operating at 12.5 kHz, 2961 × 12.5 (kHz) = 37.0125 MHz
The output F0 of is obtained.

Then, the F1 output from the fixed frequency oscillator 314 is set to 26
The output frequency F0 (37.012 MHz) of the VCO 304 is mixed with the F1 in the mixer 312 to obtain the original secondary carrier frequency FL.

That is, from the original secondary carrier frequency calculation unit 300, FL
= 261.85 + 37.0125 = 298.8625MHz is output.

Then, based on the original secondary carrier frequency FL,
Primary / secondary signal conversion unit 106 and secondary / primary signal conversion unit 108
Obtains a primary transmission signal from the primary reception carrier frequency Ft as the primary reception carrier frequency and from the parent secondary reception carrier frequency Fr received from the slave unit.

More specifically, the primary / secondary signal modulator 106 modulates the received primary reception signal (downlink signal) into a temporary secondary transmission signal of frequency F2, and then obtains a secondary transmission signal. The fixed frequency F2 at this time is determined as follows.

That is, the transmission mixer 110 in the primary / secondary signal modulator 106
The transmission secondary carrier frequency Ft output by the above is expressed by the following equation.

Ft = FL + F2 (1) Therefore, in the transmission mixer 110, since the parent side transmission secondary carrier frequency Ft is 380.2125 to 381.3125 MHz,
If the first channel is set to 380.2125MHz, (1) above
From the formula, F2 is set to 81.35MHz.

Similarly, the frequency F3 of the temporary secondary reception signal in the secondary / primary signal converter 108 is set as follows.

In other words, the slave unit of the low power cordless telephone device detects the transmission secondary carrier frequency Ft of the master unit and outputs 126.35MHz.
(= Ft-Fr) Low frequency, ie 380.2125-126.35 =
It is configured to transmit at 253.8625MHz (the frequency at this time is the parent side reception secondary carrier frequency Fr).
From the original secondary carrier frequency FL calculated from the next carrier frequency, the frequency F3 of 298.8625-253.8625 = 45 MHz is obtained from the equation (2).

Fr = FL-F3 (2) Then, as described above, if the frequencies F2 and F3 are set in advance, based on the expressions (1) and (2), based on the primary carrier frequency, The secondary carrier frequencies Ft and Fr can be set from the calculated original secondary carrier frequency FL.

When the mobile station 10a moves from the current small radio zone a to the adjacent small radio zone c, the primary carrier frequency is changed to the free frequency _f3t of the small radio zone c.
In the primary carrier frequency monitoring means 200, the frequency f
A count value corresponding to _3t is output, a new original secondary carrier frequency FL is output from the original secondary carrier frequency calculation unit 300, and the secondary transmission signal between the master unit and the slave unit is a new secondary carrier. It will be formed by the frequency signal. Therefore, even if the mobile station freely moves after the line connection, there is no mobile station having the same secondary carrier frequency at least within the effective range of the secondary carrier frequency, so that the interference unique to the cordless telephone device does not occur. .

It should be noted that F0, FL and F1, F2, F3, which are the factors for obtaining the transmission / reception secondary carrier frequencies Ft, Fr on the parent side, can be variously combined depending on the respective transmission / reception secondary carrier frequencies Ft, Fr.

Therefore, the device of the present embodiment pays attention to the fact that, within the small radio zone in which the primary carrier frequency of the mobile phone is the same, different frequencies are always assigned by the control of the base station,
Even if mobile stations in a call approach each other, the secondary carrier frequency signal of each mobile station is determined based on the primary carrier frequency, so that the mobile stations are different from each other and interference peculiar to the cordless telephone device is removed. it can.

As described above, according to the cordless telephone device for mobile communication of the present invention, the effective frequency range between the master unit and the slave unit is always within the small wireless zone, and the same Since different primary carrier frequencies are always assigned to mobile stations in the small radio zone, by determining the secondary carrier frequency between the master unit and the slave unit by the primary carrier frequency, it is possible to move during a call. Even if the stations approach each other, the effect of not causing interference is exerted.

[Brief description of drawings]

FIG. 1 is a block configuration diagram of a main part of a cordless telephone device for mobile telephone communication according to the present invention, FIG. 2 is an explanatory diagram of an automobile telephone communication system, and FIG. 3 is a schematic configuration diagram of a conventional automobile telephone device. is there. Mobile station 20a, 20b, 20c ...... Base station 30 ...... Base control station 40 ...... Car telephone exchange station 100 ...... Main unit 102 ...... Primary transceiver 104 ...... Parent side transceiver 106 …… Primary / secondary signal conversion unit 108 …… Secondary / primary signal conversion unit 120 …… Slave unit 200 …… Primary carrier frequency signal monitoring means 300 …… Original secondary carrier frequency calculation unit .

Claims (1)

(57) [Claims] 1. A mobile communication telephone device mounted on a mobile body such as an automobile and performing telephone communication as a mobile station of a mobile telephone base station utilizing a public telephone public network, wherein the mobile station is a radio station. A base unit and a handset unit connected by communication are included, and the base unit converts the dial signal and the voice signal input from the handset unit into a predetermined primary transmission signal to the base station. In a mobile communication cordless telephone device comprising an uplink transmission means for transmitting, and a downlink reception means for receiving a signal from the base station and outputting it to the slave unit, a mobile telephone base station, Primary carrier frequency monitoring means for monitoring an uplink transmission carrier frequency or a downlink reception carrier frequency between the master unit, and a secondary carrier frequency between the master unit and the slave unit based on the primary carrier frequency. When determining the carrier frequency An original secondary carrier frequency calculating means for calculating and updating the underlying original secondary carrier frequency FL each time, and preset in consideration of the calculated original secondary carrier frequency FL and usable secondary carrier frequency band. Using the frequencies F2 and F3, the transmission secondary carrier frequency Ft to be transmitted to the slave unit is calculated by Ft = FL + F2, and the reception secondary carrier frequency Fr received from the slave unit is Fr = FL-F3. A cordless telephone device for mobile communication, comprising: a secondary signal generation unit that generates a secondary transmission signal between the master unit and the slave unit by calculation.