Communication device

Provided is a wireless transmitter-receiver capable of suppressing undesirable power consumption and elongating the continuous operation time by operation of a user with the intention of controlling transmission power and also suitable to secure the “symmetry of communication”.The wireless transmitter-receiver decreases the upper limit value of transmission power by an operation of an operation means 114 and decreases the reception sensitivity in accordance with the decreased upper limit value of transmission power. Thereby, a user can determine the upper limit value of transmission power of the wireless transmitter-receiver and manage the transmission power to suppress power consumption and elongate a continuous operation time. Moreover, the wireless transmitter-receiver can eliminate the influence of radio frequency electromagnetic field on a human body. Furthermore, the degree of imbalance in the “symmetry of communication” can be minimized.

FIELD OF THE INVENTION

The present invention relates to a wireless transmitter-receiver and more specifically to controlling transmission power of a wireless transmitter-receiver.

BACKGROUND OF THE INVENTION

In recent years, wireless terminals such as a cellular phone using a battery as a power source and a mobile PC installed with a communication device widely spread to be used in a mobile communication system. In accordance with the trend, the effort to elongate the continuous operation time of these wireless terminals has been made by using various energy saving technologies.

Meanwhile, a wireless terminal consumes the most power in transmitting a signal in the total power consumption. The power required for transmission in a conventional wireless terminal is determined by the intensity or quality of the signal transmitted by a radio base station and received by the wireless terminal in a mobile communication system.

As an example of prior art, patent document 1 relates to a radio communication system, wherein transmission power is determined on the basis of measured intensity of a received signal.

Patent Document 1: JP 07-226710 A

SUMMARY OF THE INVENTION

Problem to be Solved by the Invention

The conventional wireless terminal, however, does not allow a user to control the transmission power with the intention. Therefore, a user cannot decrease the transmission power with the intention of saving energy consumption when the power is on. If a wireless terminal is in an environment to which a radio base station can hardly transmit a radio wave, the wireless terminal performs transmission with the maximum power. As a result, the wireless terminal consumes more power than that the user has expected, which is one of the reason why the continuous operation time is shortened.

The object of the present invention is to provide a wireless transmitter-receiver capable of controlling undesirable power consumption and elongating the continuous operation time by operation of a user with the intention of controlling transmission power, and the control means thereof.

A radio wave propagated by predetermined transmission power from a radio base station undergoes propagation loss on the path to a wireless terminal, and then is received by the wireless terminal.

The radio wave propagated by the wireless terminal undergoes the same amount of propagation loss as mentioned above on the path to the base station. As in this case, the amounts of propagation loss are equal between the transmission side and the reception side. Therefore, the communication is considered to be symmetrical in this meaning.

The maximum values of transmission power are different in general between a radio base station and a wireless terminal. Even in such a case, a system is designed taking account of the characteristics of antennas, noise figure of a receiver unit, etc. so that the “symmetry of communication” is sustained.

Here, if only the transmission power is decreased, the signal received by a radio base station is made weak and the “symmetry of communication” becomes incompatible. In this state, in order to sustain the “symmetry of communication” only on the wireless terminal side, the wireless terminal only needs to decrease reception sensitivity by an amount corresponding to the decreased amount of the transmission power by the wireless terminal.

The object of the present invention is to make transmission power to be changeable with the intention of the user while securing the “symmetry of communication”.

Means for Solving the Problem

To achieve the objects, Invention 1 is a wireless transmitter-receiver characterized in comprising a transmission power controlling means and a reception sensitivity controlling means, the transmission power controlling means and the reception sensitivity controlling means being controlled by a single operation.

Here, controlling the transmission power controlling means and the reception sensitivity controlling means by a single operation means the operation performed when the power of a wireless transmitter-receiver is on, and does not include, for example, switching the power from on to off to make the upper limit value of transmission power and the reception sensitivity simultaneously to be zero.

Moreover, to achieve the objects, Invention 2 is a wireless transmitter-receiver characterized in being provided with a means for decreasing the upper limit value of transmission power by a prescribed operation and a means for decreasing reception performance in accordance with the upper limit value of transmission power decreased by the prescribed operation.

In such a configuration as mentioned above, which is provided with the means for decreasing the upper limit value of transmission power by a prescribed operation, thereby an effect such that the power consumption can be suppressed by managing the transmission power by the user and that the continuous operation time can be elongated is demonstrated. Furthermore, in such a configuration, which is provided with the means for decreasing the reception performance in accordance with the decreased upper limit value of transmission power, thereby an effect such that the degree of imbalance in the “symmetry of communication” can be minimized is demonstrated.

Moreover, Invention 3 is a wireless transmitter-receiver of Inventions 2 characterized in that the reception performance is reception sensitivity.

Moreover, Invention 4 is a wireless transmitter-receiver of Invention 2 characterized in that the reception performance is a reference value in determining if the communication is compatible.

Moreover, Invention 5 is a wireless transmitter-receiver of invention 2 characterized in that the reception performance is an allowance for an error rate of received data.

Moreover, to achieve the objects, Invention 6 is a wireless transmitter-receiver characterized in being provided with a means for decreasing an upper limit value of transmission power by a prescribed operation and a means for notifying a partner in communication of a reception state in the case when reception performance is decreased or assumed to be decreased in accordance with the upper limit value of transmission power decreased by a prescribed operation.

In such a configuration as mentioned above, which is provided with the means for decreasing the upper limit value of transmission power by a prescribed operation, thereby an effect such that the power consumption can be suppressed by managing the transmission power by the user and the continuous operation time can be elongated is demonstrated. Furthermore, in such a configuration, which is provided with the means for notifying a partner in communication of a reception state in the case when reception performance is decreased or assumed to be decreased in accordance with the upper limit value of transmission power decreased by a prescribed operation, for example, if the partner in communication can control the transmission power, etc. on the basis of the reception state of the wireless transmitter-receiver in the configuration, thereby an effect such that the degree of imbalance in the “symmetry of communication” can be minimized is demonstrated.

Moreover, Invention 7 is a wireless transmitter-receiver of Invention 6 characterized in that the reception performance is reception sensitivity.

Moreover, Invention 8 is a wireless transmitter-receiver of Invention 6 characterized in that the reception performance is a reference value in determining if the communication is compatible.

Moreover, Invention 9 is a wireless transmitter-receiver of Invention 6 characterized in that the reception performance is an allowance for an error rate of received data.

Moreover, Invention 10 is a wireless transmitter-receiver of either of Inventions 3 and 7 characterized by establishing communication to a partner in radio transmission and reception with higher radio wave intensity than the previously registered radio wave intensity while using the decreased reception sensitivity.

Moreover, Invention 11 is a wireless transmitter-receiver of Invention 10 characterized in being capable of decreasing and restoring to normal values simultaneously the upper limit value of transmission power and the reception sensitivity by a control signal generated by the prescribed operation by a user.

Moreover, Invention 12 is a wireless transmitter-receiver of Invention 10 characterized in being capable of decreasing and restoring to normal values simultaneously the upper limit value of transmission power and the reception sensitivity by a control signal generated by a remote operation caused by the information transmitted from the outside.

Moreover, invention 13 is a wireless transmitter-receiver of Invention 10 characterized in that when a call to a previously registered partner in the information transmission is made in a state in which the upper limit value of transmitting power and the reception sensitivity have been decreased, the upper limit value of transmitting power that has been decreased returns to a normal value.

Moreover, Invention 14 is a wireless transmitter-receiver of Invention 10 characterized in that when a call from a previously registered partner in an information transmission is received in a state in which the upper limit value of transmitting power and the reception sensitivity have been decreased, the upper limit value of transmitting power that has been decreased returns to a normal value.

Moreover, Invention 15 is a wireless transmitter-receiver of Invention 10 characterized in that when a previously registered specific event is detected in a state in which the upper limit value of transmitting power and the reception sensitivity have been decreased, the upper limit value of transmitting power that has been decreased returns to a normal value.

Here, the specific event means a state that allows the decreased upper limit value of transmitting power to return to a normal value without an operation of a user.

The wireless transmitter-receiver of Invention 15 is characterized in that the upper limit value of transmitting power that has been decreased returns to a normal value when, for example, being connected with wired earphones, being connected with a wired microphone, being connected with wireless earphones, being connected with a wireless microphone, being located in a previously registered area, and/or it is in the period of time previously registered.

Moreover, to achieve the objects, invention 16 is a wireless transmitter-receiver comprising a transmitting power controlling means and a reception sensitivity controlling means, wherein: the transmitting power controlling means and the reception sensitivity controlling means have a common control signal; the wireless transmitter-receiver is capable of decreasing and restoring to normal values simultaneously the upper limit value of transmission power and the reception sensitivity by operating the control signal; the wireless transmitter-receiver is capable of establishing communication to a partner in radio transmission and reception with higher radio wave intensity than the previously registered radio wave intensity while using the decreased reception sensitivity; and the wireless transmitter-receiver comprises a location detecting means and is capable of decreasing and restoring to normal values the upper limit value of transmission power when detecting being located in a previously registered area.

Moreover, Invention 17 is a wireless transmitter-receiver of Invention 16 characterized in controlling reception sensitivity in conjunction with transmission output power.

Moreover, Invention 18 is a wireless transmitter-receiver of Invention 16 characterized in that reception sensitivity changes in conjunction with transmission output power.

Effect of the Invention

According to the present invention, a user can determine the upper limit value of transmission power of a wireless transmitter-receiver and manage the transmission power to suppress power consumption and to elongate a continuous operation time. Moreover, the wireless transmitter-receiver can eliminate an influence of radio frequency electromagnetic field on a human body.

BEST MODES FOR CARRYING OUT THE INVENTION

Exemplary embodiments of the present invention are described. Herein, relationships between mobile communication systems and embodiments of the present invention are described.

A configuration of a mobile communication system connected with cellular phones, mobile PCs installed with communication devices, etc. comprises at least wireless terminals, a “radio base station, which is a partner in radio transmission and reception” (hereinafter, referred to as a “radio base station”), a public communication network, and a “terminal to be a partner in an information transmission”.

In the mobile communication system when the wireless terminal from this side intends to establish a communication with a “terminal to be a partner in an information transmission and reception”, the wireless terminal on this side is connected with the “radio base station”, and through the public communication network connected with the “terminal to be a partner in an information transmission”.

The present invention can be widely applied not only to a wireless terminal and a radio base station in a mobile communication system but also to one-to-one radio communication, etc. The following wireless transmitter-receivers according to first to fifth embodiments of the present invention, however, are described as the examples of the present invention applied to wireless terminals in a mobile communication system.

In the embodiments of the present application the states of transmission power and reception sensitivity represented by “normal” and “lower than normal” are defined as follows.

The transmission power of a wireless transmitter-receiver in a conventional mobile communication system could not be changed to an intended value by a user with the intention of doing so. The transmission power was determined by the base station and the wireless terminal on the basis of the results of the measured intensity of the radio wave propagated from the base station.

In the embodiments according to the present invention the transmission power not changed by a user is defined as “normal transmission power”, while the transmission power decreased by a user with the intention to do so is defined as “decreased transmission power below normal”,

First Embodiment

A wireless transmitter-receiver according to a first embodiment of the present invention is explained.FIG. 1shows a basic configuration of a wireless transmitter-receiver according to a first embodiment.

A configuration of the wireless transmitter-receiver and actions of respective parts are explained. The wireless transmitter-receiver is constituted by an antenna111, a receiving unit410, a transmitting unit470, a control-signal generation unit450, and an operation means114.

The receiving unit410comprises at least a bandwidth limiter121, a sensitivity controller122, an automatic gain control amplifier123, a channel tuner126, and a demodulator128.

A received signal331caught by the antenna111is inputted to the receiving unit410and a demodulated signal332is outputted from the receiving unit410. The demodulated signal332includes the “information transmitted by a base station”.

The sensitivity controller122can change reception sensitivity by a correction control signal352generated by a control signal generator450.

FIG. 11shows a circuit example of the sensitivity controller122. The sensitivity controller122may have a configuration as indicated inFIG. 11(a), for example, comprising: a first capacitor the one end of which is connected with the bandwidth limiter121; a PIN diode564the anode terminal of which is connected with the other end of the first capacitor and the cathode terminal of which is grounded; a resistance element the one end of which is inputted with the correction control signal352; a coil the one end of which is connected with the other end of the resistance element and the other end of which is connected with an anode terminal of the PIN diode564; and a second capacitor the one end of which is connected with the anode terminal of the PIN diode564and the other end of which is connected with the automatic gain control amplifier123.

The sensitivity controller122may have another configuration as indicated inFIG. 11(b), for example, comprising: a first capacitor the one end of which is connected with the bandwidth limiter121; a second capacitor the one end of which is grounded; a first resistance element the one end of which is grounded; a second resistance element the one end of which is inputted with the correction control signal352; a dual gate field-effect transistor the first gate terminal G1of which is connected with the other end of the first capacitor, and the second gate terminal G2of which is connected with the second capacitor, the other end of the first resistance element, and the other end of the second resistance element; a third capacitor the one end of which is connected with a source terminal S of the dual gate field-effect transistor and the other end of which is grounded; a third resistance element the one end of which is connected with the source terminal S of the dual gate field-effect transistor and the other end of which is grounded; a fourth resistance element the one end of which is connected with a drain terminal D of the dual gate field-effect transistor and the other end of which is connected with a power source VDD; a fourth capacitor the one end of which is connected with the power source VDD and the other end of which is grounded; and a fifth capacitor the one end of which is connected with the drain terminal D of the dual gate field-effect transistor and the other end of which is connected with the automatic gain control amplifier123.

The transmitting unit470comprises at least a carrier wave generator171, a demodulator172, and a transmission power controller173.

A modulating signal374having “information to be transmitted to a partner” is inputted to the transmitting unit470. The transmitting unit470generates a transmission signal375and outputs the transmission signal375to an antenna111.

The transmission power controller173can change transmission power in accordance with the correction control signal352generated by the control signal generator450.

FIG. 12shows a circuit example of the transmission power controller173. The transmission power controller173may have a configuration as indicated inFIG. 12(a), for example, comprising: a first capacitor the one end of which is connected with a modulator172; a PIN diode564the anode terminal of which is connected with the other end of the first capacitor and the cathode terminal of which is grounded; a resistance element the one end of which is inputted with the correction control signal352; a coil the one end of which is connected with the other end of the resistance element and the other end of which is connected with an anode terminal of the PIN diode564; a second capacitor the one end of which is connected with the anode terminal of the PIN diode564; and a power amplifier566the input terminal of which is connected with the other end of the second capacitor and the output terminal of which outputs a transmission signal375.

The transmission power controller173may have another configuration as indicated inFIG. 12(b), for example, comprising a gain-changeable power amplifier567which is inputted with the signal outputted by the modulator172and the correction control signal352to an input terminal and outputs an transmission signal375from an output terminal.

An operation means114generates an operation signal315on the basis of the operation made by a user, etc. and outputs the operation signal315to the control signal generator450.

The control signal generator450is inputted with the operation signal315from the operation means114and outputs the correction control signal352determined on the basis of the state of the operation signal315. The control signal generator450generates and outputs the correction control signal352to the transmitting unit470and the receiving unit410in common.

In other word, the transmitting unit470and the receiving unit410are controlled by a single operation made by the operation means114.

FIG. 13shows a circuit example of the control signal generator450. The control signal generator450may have a configuration as indicated inFIG. 13(a), for example, comprising: a first resistance element the one end of which is connected with a power source VDD; a second resistance element the one end of which is connected with the power source VDD; a flip-flop577the set terminal S of which is connected with the other end of the first resistance element and the reset terminal R of which is connected with the other end of the second resistance element; an analog switch the control terminal of which is connected with an output terminal Q of the flip-flop577; a third resistance element the one end of which is connected with the power source VDD and the other end of which is connected with the one end of the analog switch578; a fourth resistance element the one end of which is connected with the one end of the analog switch578and the other end of which is grounded; a fifth resistance element the one end of which is connected with the other end of the analog switch578and the other end of which is grounded; and a voltage-follower amplifier551the input terminal of which is connected with the one end of the analog switch578and the output terminal of which outputs a correction control signal352.

The control signal generator450may have another configuration as indicated inFIG. 13(b), for example, comprising: a first resistance the one end of which is connected with a power source VDD; a second resistance the one end of which is connected with a power source VDD; a flip-flop577the set terminal S of which is connected with the other end of the first resistance element and the reset terminal R of which is connected with the other end of the second resistance element; a first three-state buffer576the output enable terminal OE of which is connected with the output terminal Q of the flip-flop577and the output terminal of which outputs a correction control signal352; n+1 first switch elements the one ends of which are respectively connected with the n+1 input terminals of the first three-state buffer576and the other ends of which are grounded; n+1 third resistance elements the one ends of which are connected with the power source VDD and the other ends of which are respectively connected with the n+1 input terminals of the first three-state buffer576; a second three-state buffer576the output enable terminal OE of which is connected with the inverted output terminal−Q of the flip-flop577and the output terminal of which outputs a correction control signal352; n+1 second switch elements the one ends of which are respectively connected with the n+1 input terminals of the second three-state buffer576and the other ends of which are grounded; and; n+1 fourth resistance elements the one ends of which are connected with the power source VDD and the other ends of which are respectively connected with the n+1 input terminals of the second three-state buffer576.

FIGS. 13(a) and13(b) show the examples of the operation means114having a configuration which comprises a first switch element the one end of which is connected with the set terminal S of the flip-flop577and the other end of which is grounded and a second switch element the one end of which is connected with the reset terminal R of the flip-flop577and the other end of which is grounded.

The action of the wireless transmitter-receiver in the case when the transmission power of the wireless transmitter-receiver is “normal transmission power” is described below.

Note that the action of the wireless transmitter-receiver in the case when the transmission power is the “normal transmission power” is identical to the action of a conventional wireless terminal.

When the transmission power of the wireless transmitter-receiver is “normal transmission power” the control signal generator450generates the correction control signal352having the value for sustaining the “normal transmission power” and the “normal reception sensitivity” and outputs the correction control signal352to the transmitting unit470and the receiving unit410.

The transmission power controller173which is a component of the transmitting unit470is inputted with the correction control signal352having the value for sustaining the “normal transmission power”. The transmitting unit470therefore outputs the transmission signal375with the “normal transmission power”.

The sensitivity controller122which is a component of the receiving unit410is inputted with the correction control signal352having the value for sustaining the “normal reception sensitivity”. The receiving unit410therefore generates the demodulated signal332with the “normal reception sensitivity”.

Here, a problem caused when the transmission power is decreased is described. A wireless transmitter-receiver determines the transmission power in accordance with the intensity of the radio wave propagated from a wireless base station.

If the radio wave propagated from the radio base station is strong enough the wireless transmitter-receiver decreases the transmission power. Meanwhile, if the radio wave propagated from the radio base station is weak the wireless transmitter-receiver increases the transmission power.

A wireless transmitter-receiver performs transmission with the minimum necessary transmission power in the normal state. In the state in which a wireless transmitter-receiver can receive the radio wave propagated from a radio base station, for example, if the wireless transmitter-receiver simply decreases the transmission power, the radio wave from the wireless transmitter-receiver cannot be propagated to the radio base station and the communication is stopped. Moreover, the “symmetry of communication” between the transmission power and reception sensitivity of the wireless transmitter-receiver becomes imbalanced if seen from the radio base station, Consequently, the radio base station and the base station network cannot operate normal communication with the wireless transmitter-receiver.

The problem mentioned above and the means for solving the problem are more concretely described in comparison with conventional means.

FIG. 21(a)-(c) are charts respectively showing transmission power characteristics, reception sensitivity characteristics, and reception intensity characteristics of a conventional wireless terminal, andFIG. 21(d)-(f) are charts respectively showing transmission power characteristics, reception sensitivity characteristics, and reception intensity characteristics of a conventional wireless terminal in the case when only the upper limit value of transmission power is decreased.

FIG. 22(a)-(c) are charts respectively showing transmission power characteristics, reception sensitivity characteristics, and reception intensity characteristics of a conventional wireless terminal, andFIG. 22(d)-(f) are charts respectively showing transmission power characteristics, reception sensitivity characteristics, and reception intensity characteristics of a wireless transmitter-receiver according to the present embodiment.

The vertical axes800inFIGS. 21(a) and (d) andFIGS. 22(a) and (d) represent transmission power, the vertical axes801inFIGS. 21(b) and (e) andFIGS. 22(b) and (e) represent reception sensitivity, and the vertical axes802inFIGS. 21(c) and (f) andFIGS. 22(c) and (f) represent reception intensity. The horizontal axes803inFIG. 21andFIG. 22represent the propagation loss (≈distance) between a conventional wireless terminal (or a wireless transmitter-receiver according to the present embodiment) and a radio base station.

A conventional wireless terminal controls transmission power in such a manner that as the propagation loss on the way to/from a radio base station increases (that is, as the radio wave propagated from the radio base station becomes weaker) the transmission power increases as shown inFIG. 21(a). The transmission power becomes constant at the maximum transmission power804that the wireless terminal can exert, and when the propagation loss becomes a little higher than the value at the maximum transmission power804the wireless terminal cannot transmit a signal to the radio base station anymore. Meanwhile, the reception sensitivity is set, regardless of the propagation loss, to be the maximum reception sensitivity805that the wireless terminal can exert as shown inFIG. 21(b). Therefore, as the propagation loss becomes higher the reception intensity decreases from the maximum reception intensity815as shown inFIG. 21(c), and when the reception intensity decreases to the allowance806the wireless terminal cannot receive a signal from the radio base station anymore.

In the state mentioned above, the range807where the wireless terminal can transmit a signal to the radio base station and the range808where the wireless terminal can receive a signal from the radio base station are identical, and therefore the “symmetry of communication” is compatible. That is because the system is designed so that the “symmetry of communication” is sustained taking account of the characteristics of antennas, noise figure of a receiver unit, etc. Therefore, when the propagation loss (a distance or an area) increases beyond the range807and808to the range809and810, the wireless terminal cannot establish the communication with the radio base station anymore and displays “out of range”.

Meanwhile, in the case when only the upper limit value of transmission power is decreased to a fixed value811, the transmission power becomes constant at the fixed value811as shown inFIG. 21(d). When the propagation loss becomes a little higher than the value which corresponds to the fixed value811, the wireless terminal cannot transmit a signal to the radio base station anymore. Therefore, the range812of the propagation loss (a distance or an area) where the wireless terminal can transmit a signal to the radio base station becomes narrower than that in the case when the upper limit value of transmission power is not decreased. The reception sensitivity, however, is set, regardless of the propagation loss, to be the maximum reception sensitivity805as shown inFIG. 21(e). Therefore, as the propagation loss becomes higher the reception intensity decreases from the maximum reception intensity815as shown inFIG. 21(f), and when the reception intensity decreases to the allowance806the wireless terminal cannot receive a signal from the radio base station anymore. Consequently, the range808where the wireless terminal can receive a signal from the radio base station becomes identical to the range in the case when the upper limit value of transmission power is not decreased.

In the state mentioned above, the range812of the propagation loss where the wireless terminal can transmit a signal to the radio base station and the range808of the propagation loss where the wireless terminal can receive a signal from the radio base station are not identical, and therefore the “symmetry of communication” is incompatible. Namely, in the case when the propagation loss exceeds the range812and does not exceed the range808, the wireless terminal cannot transmit a signal to the radio base station and, however, can receive a signal from the radio base station. In this one-way communication, the wireless terminal cannot make a call to the radio base station whereas the wireless terminal does not display “out of range”. In this state the user is made confused, and in addition, the radio base station and the base station network cannot operate normal communication with the wireless transmitter-receiver.

To solve the problem mentioned above, in the case when the upper limit value of transmission power is decreased to a fixed value811by the operation of an operation means114as shown inFIG. 22(d) the wireless transmitter-receiver according to the present embodiment decreases the reception sensitivity to a fixed value813in accordance with the decreased upper limit value of transmission power811as shown inFIG. 22(e), In the case, for example, when the upper limit value of transmission power is decreased from the maximum transmission power804(for example, 1 [W]) to a constant value811(for example, 0.1 [W]) the wireless transmitter-receiver decreases the reception sensitivity from the maximum reception sensitivity805(for example, 0 [dB]) to a fixed value813(for example, −10 [dB]). When the reception sensitivity is decreased, as the propagation loss becomes higher the reception intensity also decreases from a constant value816which is the value decreased from the maximum reception intensity815by a prescribed value (corresponding to the difference between the maximum reception sensitivity805and the fixed value813) as shown inFIG. 22(e). Furthermore, when the reception intensity decreases to the allowance806the wireless terminal cannot receive a signal from the radio base station anymore. Thus, the range of the reception intensity becomes narrower, and therefore the range814where the wireless transmitter-receiver can receive a signal from the radio base station becomes narrower than that in the case when reception sensitivity is not decreased.

Thereby the range812of the propagation loss where the wireless transmitter-receiver can transmit a signal to the radio base station and the range814of the propagation loss where the wireless terminal can receive a signal from the radio base station become identical, and therefore the “symmetry of communication” is sustained compatible.

The reception sensitivity may be decreased in accordance with the upper limit value of transmission power. In this case it is preferable to decrease the reception sensitivity in such a manner that the range (reception range) where the wireless transmitter-receiver can receive a signal from the radio base station and the range (transmission range) where the wireless terminal can transmit a signal to the radio base station become identical. However, the reception range and the transmission range do not have to be completely identical. If only the portion in which the reception range and the transmission range do not coincide is minimized in comparison with the case when the reception sensitivity is not decreased at all, the degree of imbalance in the “symmetry of communication” can be minimized. Therefore, when the upper limit value of transmission power is decreased, the reception sensitivity only has to be decreased so that the reception range and the transmission range coincide or the portion in which the both ranges do not coincide is minimized.

Next, the action of the wireless transmitter-receiver according to the present embodiment in the case when the transmission power is switched to the “decreased transmission power below normal” and the action for inhibiting the problem mentioned above are described in the example using a variable attenuator as the sensitivity controller122shown inFIG. 1.

Here, suppose that a user is decreasing the transmission power which is fluctuating within a prescribed range to 1/10 by manual operation as a usual operation.

When the user operates an operation means114, a correction control signal352generated by a control signal generator450is inputted to the sensitivity controller122(variable attenuator) and a transmission power controller173.

Here, the correction control signal352has a value indicating decrease to 1/10. The transmission power controller173sets the transmission power to be 1/10 of the original maximum transmission power.

The sensitivity controller122(variable attenuator) sets an attenuation factor to be 1/10. Accordingly, the wireless transmitter-receiver according to the present embodiment is capable of switching the transmission power to the “decreased transmission power below normal” and restoring to the “normal transmission power” and also capable of switching the reception sensitivity to the “decreased reception sensitivity below normal” and restoring to the “normal reception sensitivity” in conjunction with switching the transmission power.

A method for decreasing the reception sensitivity of the receiving unit410is described below. The sensitivity controller122which is a component of the receiving unit410can be implemented by using a variable amplifier and a variable attenuator.

As the other method, narrowing the gain variable range of an automatic gain control amplifier123is capable of decreasing the reception sensitivity of the receiving unit410.

In such a way as in the present embodiment the wireless transmitter-receiver decreases the upper limit value of transmission power by the operation of the operation means114and decreases the reception sensitivity in accordance with the decreased upper limit value of transmission power.

Thereby, a user can determine the upper limit value of transmission power of the wireless transmitter-receiver and manage the transmission power to suppress power consumption and to elongate a continuous operation time. Moreover, the wireless transmitter-receiver can eliminate the influence of radio frequency electromagnetic field on a human body. Furthermore, the degree of imbalance in the “symmetry of communication” can be minimized.

Second Embodiment

A wireless transmitter-receiver according to a second embodiment of the present invention is explained.FIG. 2shows a basic configuration of a wireless transmitter-receiver according to a second embodiment.

A configuration of the wireless transmitter-receiver and actions of respective parts are explained. The wireless transmitter-receiver is constituted by an antenna111, a receiving unit420, a determination unit for communication compatibility430, a determination unit for transmission power460, a transmitting unit470, a control-signal generation unit450, and an operation means114.

The receiving unit420comprises at least a bandwidth limiter121, an automatic gain control amplifier A124, an automatic gain control amplifier B125, a channel tuner126, a demodulator128, and a reception level generator129.

A received signal331caught by the antenna111is inputted to the receiving unit420and a demodulated signal332is outputted from the receiving unit420. The demodulated signal332includes the “information transmitted by a base station”.

The reception level generator129converts the intensity or quality of the received signal331inputted to the receiving unit420to a reception level signal335, and outputs the reception level signal335simultaneously to the determination unit for communication compatibility430and a determination unit for transmission power460.

Incidentally, the automatic gain control amplifier A124and the automatic gain control amplifier B125are not always necessary. At least one automatic gain control amplifier is necessary to implement the embodiment.

The determination unit for communication compatibility430comprises at least a level comparator141. The reception level signal335from the receiving unit420and a correction control signal352from a control signal generator450are inputted to the determination unit for communication compatibility430.

The determination unit for communication compatibility430compares the value of the reception level signal335with the value of the correction control signal352, and determines the state of a determination signal for communication compatibility343.

The determination signal for communication compatibility343is outputted in either state of “communication is compatible” or “communication is incompatible”.

FIG. 15shows a circuit example of the determination unit for communication compatibility430. The determination unit for communication compatibility430may have a configuration as indicated inFIG. 15(a), for example, comprising a level comparator141. The level comparator141has a configuration comprising a comparator553built by means of an analog circuit. The comparator553is inputted with the reception level signal335to a non-inverting input terminal and with the correction control signal352to an inverting-input terminal, and outputs the determination signal for communication compatibility343from an output terminal.

The determination unit for communication compatibility430may have another configuration as indicated inFIG. 15(b), for example, comprising a level comparator141. The level comparator141has a configuration comprising an A/D converter568for being inputted with and analog-to-digital converting the reception level signal335and a weighted comparator558built by means of a logic circuit. The comparator558is inputted with the analog-to-digital converted reception level signal335to a first input terminal and with the correction control signal352(a digital signal) to a second terminal, and outputs the determination signal for communication compatibility343from an output terminal.

The determination unit for transmission power460comprises at least a level arithmetic unit163and a level limiter161.

The reception level signal335from the receiving unit420and the correction control signal352from a control signal generator450are inputted to the determination unit for transmission power460.

The level arithmetic unit163in the determination unit for transmission power460determines the transmission power from the value of the reception level signal335.

The level limiter161verifies whether the transmission power determined by the level arithmetic unit163does not exceed the upper limit value based on the value of the correction control signal352. If the transmission power exceeds the upper limit value, the level limiter161changes the transmission power to the upper limit value and outputs the result as a transmission power control signal362to the transmitting unit470.

Namely, the upper limit value is restricted in accordance with the value of the correction control signal352. Therefore, the transmission power control signal362within the restricted upper limit value is outputted so that the transmission power is suppressed below an intended value.

FIG. 16andFIG. 17show a circuit examples of the determination unit for transmission power460. The determination unit for transmission power460may have a configuration as indicated inFIG. 16(a), for example, comprising a level limiter161and a level arithmetic unit163. The level arithmetic unit163has a configuration comprising an inverting amplifier533built by means of an analog circuit. The inverting amplifier533is inputted with, amplifies and outputs the reception level signal335. The level limiter161has a configuration comprising a level limiter559built by means of an analog circuit. The level limiter559is inputted with the amplified reception level signal335to an input terminal and with the correction control signal352as a level restriction reference voltage717, and outputs the transmission power control signal362from an output terminal.

The determination unit for transmission power460may have another configuration as indicated inFIG. 16(b), for example, comprising a level limiter161and a level arithmetic unit163. The level arithmetic unit163has a configuration comprising an inverting amplifier533built by means of an analog circuit. The inverting amplifier533is inputted with, amplifies and outputs the reception level signal335. The level limiter161has a configuration comprising a D/A converter569for being inputted with and digital-to-analog converting the correction control signal352(a digital signal) and a level limiter559built by means of an analog circuit. The level limiter559is inputted with the amplified reception level signal335to an input terminal and with the correction control signal352as a level restriction reference voltage717, and outputs the transmission power control signal362from an output terminal.

The determination unit for transmission power460may have another configuration as indicated inFIG. 17(a), for example, comprising a subtractor555built by means of an analog circuit. The subtractor555is inputted with the reception level signal335and the correction control signal352, subtracts the correction control signal352from the reception level signal335, and outputs the subtraction result as a transmission power control signal362from an output terminal.

The determination unit for transmission power460may have another configuration as indicated inFIG. 17(b), for example, comprising a D/A converter569for being inputted with and digital-to-analog converting the correction control signal352(a digital signal) and a subtractor555built by means of an analog circuit. The subtractor555is inputted with the reception level signal335and the D/A converted correction control signal352, subtracts the correction control signal352from the reception level signal335, and outputs the subtraction result as the transmission power control signal362from an output terminal.

The determination unit for transmission power460may have another configuration as indicated inFIG. 17(c), for example, comprising a A/D converter568for being inputted with and analog-to-digital converting the reception level signal335, a subtractor557built by means of a logic circuit, and a D/A converter569for digital-to-analog converting an output signal from the subtractor557and outputting the transmission power control signal362. The subtractor557is inputted with the A/D converted reception level signal335and the correction control signal352(a digital signal), subtracts the correction control signal352from the reception level signal335, and outputs the subtraction result from an output terminal.

The transmitting unit470comprises at least a carrier wave generator171, a modulator172, and a transmission power controller173.

A modulating signal374having “information to be transmitted to a partner” is inputted to the transmitting unit470. The transmitting unit470generates a transmission signal375and inputs the transmission signal375into an antenna111.

The transmission power controller173can change transmission power by the transmission power control signal362inputted from the determination unit for transmission power460. The circuit example of the transmission power controller173is shown inFIG. 12.

An operation means114generates an operation signal315on the basis of the conducted operation and outputs an operation signal315to a control signal generator450.

The control signal generator450is inputted with the operation signal315and determines the value of a correction control signal352to be generated on the basis of the state of the operation signal315. The control signal generator450generates and outputs the correction control signal352to the determination unit for transmission power460and the determination unit for communication compatibility430. The circuit example of the control signal generator450is shown inFIG. 13.

A role of a reception level generator129is described below. The reception level generator129receives information of the signal intensity, signal error rate, etc. from an automatic gain control amplifier A124, an automatic gain control amplifier B125, a demodulator128, etc. which are the components of the receiving unit420, and generates a reception level signal335in accordance with the evaluation results of the information.

The signal intensity, signal error rate, etc. may be used individually or together. In the latter case a plurality of items may be inputted in parallel or in the sum.

A role of a determination unit for communication compatibility430is described below. A reception level signal335is outputted corresponding to the signal intensity of the radio wave transmitted by a radio base station and received by a wireless transmitter-receiver. The determination unit for communication compatibility430determines if the radio wave with the transmission power controlled by the correction control signal352can be propagated to the base station taking account of the value of the reception level signal335and if the communication is compatible or not.

When the state of the determination signal for communication compatibility343is “communication is incompatible” the radio wave transmitted by the wireless transmitter-receiver may possibly not be received by the radio base station. Therefore, even if the radio base station requires starting communication the wireless transmitter-receiver can stop starting the communication.

Incidentally, restricting the communication with the radio base station transmitting weaker signal than the previously registered radio wave intensity by determining the communication compatibility by using the reception level signal335is identical to inhibiting the communication with the radio base station presenting a weak reception signal level by decreasing reception sensitivity.

The action of the wireless transmitter-receiver in the case when the transmission power is the “normal transmission power” is described as blow.

Note that the action of the wireless transmitter-receiver in the case when the transmission power is the “normal transmission power” is identical to the action of a conventional wireless terminal.

When the transmission power of the wireless transmitter-receiver is the “normal transmission power” the control signal generator450generates and outputs the correction control signal352having the value for sustaining the “normal transmission power” and the “normal reception sensitivity” to the determination unit for transmission power460and the determination unit for communication compatibility430.

The determination unit for transmission power460determines the value of the transmission power control signal362to be outputted to the transmitting unit470in accordance with the value of the reception level signal335.

Namely, when the value of the reception level signal335becomes high, the determination unit for transmission power460determines that a radio base station exists a short distance away, and therefore decreases the value of the transmission power control signal362to suppress the transmission power. Conversely, when the value of the reception level signal335becomes low, the determination unit for transmission power460determines that a radio base station exists in the distance, and therefore increases the value of the transmission power control signal362.

Here, the correction control signal352inputted to the determination unit for transmission power460has the value for sustaining the “normal transmission power”. In the latter case the value corresponds to the “maximum transmission power”. Therefore, the value of the transmission power control signal362outputted to the transmitting unit470by the determination unit for transmission power460can be controlled up to the value corresponding to the “maximum transmission power”.

Moreover, the correction control signal352inputted to the determination unit for communication compatibility430has the value for sustaining the “normal reception sensitivity” Therefore, the determination unit for communication compatibility430determines if the demodulated signal332at that time is propagated from the radio base station to which the wireless transmitter-receiver can transmit a radio wave propagated with the “maximum transmission power”, and outputs the determination signal for communication compatibility343in either state of “communication is compatible” or “communication is incompatible”. These actions are identical to those of a conventional wireless terminal.

In this situation, the conventional wireless terminal, however, does not allow a user to change transmission power to the “decreased transmission power below normal”. Namely, a user cannot suppress the power consumption by decreasing transmission power in accordance with the situation.

Furthermore, if the transmission power is simply decreased by some means such a problem that “the radio wave propagated by the wireless transmitter-receiver becomes too weak to reach a radio base station, while the radio wave from the radio base station is received with the same intensity as before” is expected to be caused.

Here, the action of the wireless transmitter-receiver according to the present embodiment in the case when transmission power is changed to the “decreased transmission power below normal” and the action for inhibiting the problem are described.

For example, when a user makes an operation for decreasing the transmission power of the wireless transmitter-receiver below normal, the control signal generator450outputs the correction control signal352having the value for setting the “decreased transmission power below normal” and “decreased reception sensitivity below normal” to the determination unit for transmission power460and the determination unit for communication compatibility430in common.

Namely, the determination unit for transmission power460and the determination unit for communication compatibility430are controlled by a single operation.

The determination unit for transmission power460outputs the transmission power control signal362having the value within the upper limit value corresponding to the value of the correction control signal352to the transmitting unit470.

Therefore, the transmitting unit470outputs the transmission signal375with the power within the upper limit value.

At the same time the control signal generator450outputs the correction control signal352to the determination unit for communication compatibility430.

If the reception signal level propagated from a radio base station is higher (stronger) than the value indicated by the correction control signal352, the determination unit for communication compatibility430sets the state of the determination signal for communication compatibility343for determining the communication compatibility to be “communication is compatible”.

When the wireless transmitter-receiver receives the relatively weak radio wave propagated from the radio base station located at the position which the radio wave propagated with the “decreased transmission power below normal” from the wireless transmitter-receiver cannot reach, the value of the reception level signal335outputted by the receiving unit420becomes lower (weaker) than the value indicated by the correction control signal352. Therefore, the determination unit for communication compatibility430sets the state of the determination signal for communication compatibility343to be “communication is incompatible”.

The determination signal for communication compatibility343may be inputted at the start of the communication or at the time when the transmission signal375comes up to the upper limit value of the “decreased transmission power below normal”.

Incidentally, the “value indicated by the correction control signal352” is not a level in positive or negative logic in the circuit, but the value obtained by relatively comparing the “decreased transmission power below normal” with the “normal transmission power”.

As mentioned above, by referring to the determination signal for communication compatibility343the wireless transmitter-receiver only performs the communication with the radio wave propagated from the radio base station located in the range which the radio wave propagated with the “decreased transmission power below normal” from the wireless transmitter-receiver can reach. Therefore, such a problem that “the radio wave propagated by the wireless transmitter-receiver becomes too weak to reach a radio base station, while the radio wave from the radio base station is received with the same intensity as before” does not occur.

FIG. 6is a flow chart summarizing the action mentioned above, andFIG. 9shows transmission power characteristics.

FIG. 9shows (a) transmission power characteristics of a conventional wireless transmitter-receiver, and (b) transmission power characteristics of a wireless transmitter-receiver according to the present embodiment.

InFIG. 9the transmission power characteristics without correction control is shown as994, the transmission power characteristics corrected by −10 [dB] as995, and the transmission power characteristics corrected by −20 [dB] as996.

As mentioned above, the wireless transmitter-receiver according to the present embodiment is capable of varying the upper limit value of the transmission power thereof by a user, and of inhibiting the problem that may occur together with decreasing the maximum transmission power by changing the reception sensitivity in conjunction with the upper limit value of the transmission power.

The determination signal for communication compatibility343simulating the decreased reception level signal335is outputted downward while the real reception level signal335does not decrease.

Thereby a user can suppress power consumption by decreasing transmission power in accordance with the situation.

So far changing the value of the transmission power of the wireless transmitter-receiver is described in the case in which a user selects either of “normal transmission power” and “decreased transmission power below normal” by using a selector switch.

Another case may be employed by using a multi-step selector switch, etc. so that a user can select the “decreased transmission power below normal” having the value desired by a user by setting multi-selection with short steps such as 1, 0.5, 0.2, 0.1, 0.05, 0.01, 0.0.001 [W].

Moreover, another case may be employed by using a variable resistor so that a user can vary the value continuously and select the “decreased transmission power below normal” having the value desired by a user.

Displaying the states of the wireless transmitter-receiver, such as the upper limit value of transmission power set by a user, present transmission power, actual reception intensity, and decreased reception sensitivity, and warning messages is described as below.

When the upper limit value of transmission power and the reception sensitivity are changed in conjunction, both of or either of the upper limit value of transmission power and the present transmission power may be displayed.

Both of or either of the signal intensity of “normal reception sensitivity” and the “deceased reception sensitivity below normal” may be displayed.

By designating the state in which the communication is not available by decreasing the upper limit value of transmission power and the reception sensitivity in conjunction as the simulated out-of-range, the state may be indicated by displaying “simulated out-of-range”. The other means, for example, a lamp, sound, and voice may be used to notify a user of the state. Thereby, a user knows if the communication is available or not.

If the intensity of the radio wave propagated from the “partner in radio transmission and reception” becomes weak in a call, the user may be notified of the state by means of displaying, a lamp, sound, or voice.

Furthermore, when the wireless transmitter-receiver is set to use the “decreased transmission power below normal”, the information for notifying that “decreased transmission power below normal” is set to be used may be transmitted to the “partner in radio transmission and reception”.

The concrete action of the wireless transmitter-receiver according to the present embodiment is described in an example of an ordinary commercial cellular phone.

The cellular phone has been set to use the “decreased transmission power below normal” from previous turning the power on and also to use the “decreased reception sensitivity below normal” at the same time. In this case, for example, the maximum transmission power is set to be 0.1 [W] and the reception sensitivity −10 [dB], while the normal maximum transmission power is 1 [W] and the normal reception sensitivity 0 [dB].

Now the cellular phone is placed at a camp site in a valley far from a base station. The communication cannot be connected even with the most powerful base station with the transmission power of 0.1 [W] and the reception sensitivity of −10 [dB]. The communication in the normal conditions with the transmission power of 1 [W] and the reception sensitivity of ±0 [dB] can be connected.

Here, suppose that in the condition wherein the power of a cellular phone is off a user turn on the power. A cellular phone, in general, transmits a control signal to a base station that can receive the signal, is registered with the base station, and is connected in the communication. However, the cellular phone is set to use the transmission power of 0.1 [W] at the maximum and the reception sensitivity of −10 [dB], and therefore cannot be connected.

At that time the cellular phone displays the indication shown inFIG. 7. The sign of transmission power978indicates that the maximum transmission power is restricted. The sign of signal intensity with normal reception sensitivity974indicates that the received signal is weak. The sign of signal intensity with decreased reception sensitivity975indicates that no radio wave is received. The incompatible state of the communication is caused by setting the transmission power to be the “decreased transmission power below normal” by the user. Therefore, the sign of the “simulated out-of-range”976is highlighted.

FIG. 8shows modified icon designs ofFIG. 7. The sign of transmission power988indicates that the maximum transmission power is restricted. The sign of signal intensity with normal reception sensitivity984indicates that the received signal is weak. The sign of signal intensity with decreased reception sensitivity985indicates that no radio wave is received. The incompatible state of the communication is caused by setting the transmission power to be the “decreased transmission power below normal” by the user. Therefore, the sign of the “simulated out-of-range”986is highlighted.

The user wants to make a call by all means, and therefore pushes the key switch911inFIG. 10that is for setting transmission power and reception sensitivity to be normal. Then, the transmission power of the cellular phone is set to be 1 [W] and the reception sensitivity to be the maximum, which is a normal condition. Thereby, the user can make a call.

After the communication ends, if the key switch912inFIG. 10for setting transmission power and reception sensitivity to be in lower states than normal is pushed the maximum transmission power is set to be 0.1 [W] and the reception sensitivity −10 [dB].

In such a manner the wireless transmitter-receptor according to the present embodiment decreases the upper limit value of transmission power by the operation of the operation means114, and decreases the reference value in determining if the communication is compatible in accordance with the decreased upper limit value of transmission power.

Thereby, a user can determine the upper limit value of transmission power of the wireless transmitter-receiver, and thus manage the transmission power to suppress power consumption and to elongate a continuous operation time. Moreover, the wireless transmitter-receiver can eliminate the influence of radio frequency electromagnetic field on a human body. Furthermore, the degree of imbalance in the “symmetry of communication” can be minimized.

Note that the correction control signal352inputted to the determination unit for communication compatibility430in the present embodiment corresponds to the “reference value in determining if the communication is compatible” in Invention 4.

Third Embodiment

A wireless transmitter-receiver according to a third embodiment of the present invention is explained.FIG. 3shows a basic configuration of a wireless transmitter-receiver according to a third embodiment.

The wireless transmitter-receiver has a different configuration from that of the wireless transmitter-receiver according to the second embodiment while having the equivalent effect as the second embodiment.

In the wireless transmitter-receiver according to the second embodiment the correction control signal352is outputted to both of the determination unit for transmission power460and the determination unit for communication compatibility430at the same time, and thus, transmission power and reception sensitivity are controlled in conjunction.

Moreover, the determination unit for communication compatibility430determines if fine communication to a radio base station can be expected by comparing the value of the reception level signal335with the value of the correction control signal352.

In comparison with the wireless transmitter-receiver according to the second embodiment, the wireless transmitter-receiver according to the present embodiment is provided with a sensitivity converter112on the input side of a determination unit for communication compatibility440and a reference-value generator142in addition to a level comparator141in the determination unit for communication compatibility440.

FIG. 18shows a circuit example of the sensitivity converter112. The sensitivity converter112may be configured as shown inFIG. 18(a). The sensitivity converter112has a configuration comprising an adder554built by means of an analog circuit in the example ofFIG. 18(a). The adder554is inputted with a reception level signal335and a correction control signal352, adds the correction control signal352to the reception level signal335, and outputs a converted reception level signal313that is a result of addition from an output terminal.

The sensitivity converter112may be configured as shown inFIG. 18(b). The sensitivity converter112has a configuration comprising a D/A converter569for being inputted with and digital-to-analog converting the correction control signal352(a digital signal) and an adder554built by means of an analog circuit in the example ofFIG. 18(b). The adder554is inputted with a reception level signal335and a D/A converted correction control signal352, adds the correction control signal352to the reception level signal335, and outputs a converted reception level signal313that is a result of addition from an output terminal.

The sensitivity converter112may be configured as shown inFIG. 18(c). The sensitivity converter112has a configuration comprising an A/D converter568for being inputted with and analog-to-digital converting the reception level signal335and an adder556built by means of a logic circuit in the example ofFIG. 18(c). The adder556is inputted with an A/D converted reception level signal335and a correction control signal352(a digital signal), adds the correction control signal352to the reception level signal335, and outputs a converted reception level signal313(a digital signal) that is a result of addition from an output terminal.

Furthermore,FIG. 19andFIG. 20show circuit examples of the determination unit for communication compatibility440.

The determination unit for communication compatibility440may be configured as shown inFIG. 19(a). The determination unit for communication compatibility440has a configuration comprising a level comparator141and a reference-value generator142in the example ofFIG. 19(a). The level comparator141has a configuration comprising a comparator553built by means of an analog circuit. The comparator553is inputted with the converted reception level signal313to a non-inverting input terminal and with a reference voltage719to an inverting-input terminal, and outputs the determination signal for communication compatibility343from an output terminal. The reference-value generator142has a configuration comprising a first resistance element the one end of which is connected with a power source VDD and the other end of which is connected with an inverting input terminal of the comparator553and a second resistance element the one end of which is connected with the inverting input terminal of the comparator553and the other end of which is grounded.

The determination unit for communication compatibility440may be configured as shown inFIG. 19(b). The determination unit for communication compatibility440has a configuration comprising a level comparator141and a reference-value generator142in the example ofFIG. 19(b). The level comparator141has an identical configuration toFIG. 19(a). The reference-value generator142has a configuration comprising a CPU545for outputting a data signal (a digital signal) corresponding to the reference voltage719and a D/A converter569for digital-to-analog converting and outputting the data signal from the CPU545as the reference voltage719.

The determination unit for communication compatibility440may be configured as shown inFIG. 19(c). The determination unit for communication compatibility440has a configuration comprising a level comparator141and a reference-value generator142in the example ofFIG. 19(c). The level comparator141has an identical configuration toFIG. 19(a). The reference-value generator142has a configuration comprising a resistance element the one end of which is connected with a power source VDD and the other end of which is connected with an inverting input terminal of the comparator553and a zener diode565the cathode terminal of which is connected with the inverting input terminal of the comparator553and the anode terminal of which is grounded.

The determination unit for communication compatibility440may be configured as shown inFIG. 20(a). The determination unit for communication compatibility440has a configuration comprising a level comparator141and a reference-value generator142in the example ofFIG. 20(a). The level comparator141has a configuration comprising a weighted comparator558built by means of a logic circuit. The comparator558is inputted with the converted reception level signal313(a digital signal) to a first input terminal and with a reference value718to a second terminal, and outputs a determination signal for communication compatibility343from an output terminal. The reference-value generator142comprises n+1 resistance elements the one ends of which are connected with the power source VDD and n+1 switch elements the one ends of which are respectively connected with the other ends of the n+1 resistance elements and the other ends of which are grounded. Output signals from the other ends of the n+1 resistance elements correspond to respective bits of a reference value718composed of n+1 bits.

The determination unit for communication compatibility440may be configured as shown inFIG. 20(b). The determination unit for communication compatibility440has a configuration comprising a level comparator141and a reference-value generator142in the example ofFIG. 20(b). The level comparator141has an identical configuration toFIG. 20(a). The reference-value generator142has a configuration comprising a first resistance element the one end of which is connected with a power source VDD, a second resistance element the one end of which is grounded, and an A/D converter568for analog-to-digital converting the output signal from the other ends of the first resistance element and the second resistance element and outputting a reference value718.

The determination unit for communication compatibility440may be configured as shown inFIG. 20(c). The determination unit for communication compatibility440has a configuration comprising a level comparator141and a reference-value generator142in the example ofFIG. 20(c). The level comparator141has an identical configuration toFIG. 20(a). The reference-value generator142has a configuration comprising a resistance element the one end of which is connected with a power source VDD, a zener diode565the anode terminal of which is grounded, and an A/D converter568for analog-to-digital converting the output signal from the other end of the resistance element and the cathode terminal of the zener diode565and outputting a reference value718.

Here, a correction control signal352outputted from a control signal generator450is inputted to a determination unit for transmission power460and a sensitivity converter112at the same time. The correction control signal352thereby controls transmission power and reception sensitivity in conjunction.

A reception level signal335outputted from a receiving unit420is inputted to the sensitivity converter112. The value of the reception level signal335is converted with a conversion rate which changes according to the value of a correction control signal352and outputted as a converted reception level signal313.

The converted reception level signal313is inputted to a determination unit for communication compatibility440and compared with the value generated by a reference value generator142by a level comparator141for the determination unit for communication compatibility440to determine the state of a determination signal for communication compatibility343.

The determination signal for communication compatibility343is outputted in either state of “communication is compatible” or “communication is incompatible”.

Note that the value generated by the reference value generator142is determined and registered in a suitable value by any of a communication carrier, a device manufacturer, and a user. Moreover, a wireless transmitter-receiver may calculate and register an optimum value. Furthermore, the combination of the plurality of members mentioned above may be employed.

As mentioned above the wireless transmitter-receiver according to the present embodiment enables a user to change the upper limit value of transmission power of the wireless transmitter-receiver. The wireless transmitter-receiver is also capable of inhibiting the problem that may occur together with decreasing the maximum transmission power by changing the reception sensitivity in conjunction with the upper limit value of the transmission power and referring to the determination signal for communication compatibility343.

A user thereby can suppress the power consumption by decreasing transmission power in accordance with the situation.

Note that the correction control signal352inputted to the sensitivity converter112in the present embodiment corresponds to the reference value in determining if the communication is compatible in Invention 4.

Fourth Embodiment

A wireless transmitter-receiver according to a fourth embodiment of the present invention is explained. The fourth embodiment corresponds to examples of the wireless transmitter-receiver of Inventions 11-15.FIG. 4shows a basic configuration of the wireless transmitter-receiver according to the fourth embodiment.

The wireless transmitter-receiver is a wireless transmitter-receiver according to the second embodiment added with a means for detecting and processing various events116.

The means for detecting and processing various events116, in the situation intended or previously registered by a user, changes transmission power and reception sensitivity in conjunction.

The examples of the wireless transmitter-receiver of Invention 11, in particular, only the added parts are described below.

The wireless transmitter-receiver, due to the means mentioned below, is capable of changing an upper limit value of transmission power by an operation of the user, and also capable of inhibiting the problem that may occur together with decreasing only the maximum transmission power by changing the reception sensitivity in conjunction with the upper limit value of the transmission power.

The example of the wireless transmitter-receiver of Invention 11 is the wireless transmitter-receiver according to the second embodiment added with a operation means114, an operating direction processor481, and a control signal generator480which is capable of processing request information391.

FIG. 14shows a circuit example of the control signal generator480. As shown inFIG. 14the control signal generator480has a configuration comprising a CPU545for performing calculation and control on the basis of a control program, a ROM547for previously storing the control program, etc. of the CPU545in a prescribed region, a RAM546for storing the data read out from the ROM547, etc. and calculation results necessary in the calculation process of the CPU545, and a D/A converter569for digital-to-analog converting a data signal from the CPU545and outputting a correction control signal352. These components are connected with each other by a “CPU bus” that is a signal line for transmitting data so as to be capable of transferring/receiving data.

The operating direction processor481is connected with the “CPU bus” via an interface (I/F) (not illustrated), and the request information391from the operating direction processor481is inputted to the control signal generator480. The operation means114is connected with the operating direction processor481, which is inputted with an operation signal315from the operation means114.

A remote operating direction detecting processor482is connected with the “CPU bus” via an I/F (not illustrated), and the request information392from the remote operating direction detecting processor482is inputted to the control signal generator480.

A communication partner detecting comparator483is connected with the “CPU bus” via an I/F (not illustrated), and the request information393from the communication partner detecting comparator483is inputted to the control signal generator480.

A wired earphone and microphone detector484is connected with the “CPU bus” via an I/F (not illustrated), and the request information394from the wired earphone and microphone detector484is inputted to the control signal generator480.

A wireless earphone and microphone detector485is connected with the “CPU bus” via an I/F (not illustrated), and the request information395from the wireless earphone and microphone detector485is inputted to the control signal generator480.

A present position detecting area comparator486is connected with the “CPU bus” via an I/F (not illustrated), and the request information396from the present position detecting area comparator486is inputted to the control signal generator480.

A time information acquiring hours comparator487is connected with the “CPU bus” via an I/F (not illustrated), and the request information397from the time information acquiring hours comparator487is inputted to the control signal generator480.

An emergency call transmission detector488is connected with the “CPU bus” via an I/F (not illustrated), and the request information398from the emergency call transmission detector488is inputted to the control signal generator480.

An emergency warning reception detector489is connected with the “CPU bus” via an I/F (not illustrated), and the request information399from the emergency warning reception detector489is inputted to the control signal generator480.

The control signal generator480is provided with the operating direction processor481on the input side. The operating direction processor481is provided with the operation means114on the input side.

The operation signal315is inputted from the operation means114to the operating direction processor481. The request information391is inputted from the operating direction processor481to the control signal generator480.

The role of the operation means114is implemented by a selector switch, push button switch, and variable resistor. When a user perform an operation the operation means114generates and inputs the operation signal315to the operating direction processor481.

The operating direction processor481executes processing on the basis of the operation signal315outputted by the operation means114and outputs the result to the control signal generator480as the request information391.

The control signal generator480generates and outputs a correction control signal352in accordance with the request information391.

Thereby, the operation performed by the user can change an upper limit value of transmission power and reception sensitivity in conjunction therewith, and also restore the upper limit value of transmission power to the maximum value.

Thus, a user can switch transmission power to “decreased transmission power below normal” and restore to “normal transmission power” by the operation of the user. Reception sensitivity is also switched to “decreased reception sensitivity below normal” and restored to “normal reception sensitivity” in conjunction with switching of transmission power.

For example, the action of the operating direction processor481and the control signal generator480when a user set the upper limit value of transmission power to be lower than the normal value by operating the operation means114of a main body is described below.

When a user operates an operation means114of a main body the operation means114outputs an operation signal315to an operating direction processor481.

The operating direction processor481processes the inputted operation signal315and outputs the request information391for changing the upper limit value of transmission power to a control signal generator480.

The control signal generator480outputs a correction control signal352for changing the upper limit value of transmission power and the reception sensitivity in accordance with the inputted request information391.

The examples of the wireless transmitter-receiver of invention 12, in particular, only the added parts are described below.

The wireless transmitter-receiver, due to the addition of the means mentioned below, can change the upper limit value of transmission power and also reception sensitivity in conjunction therewith by remote operation using a communication means from outside.

The example of the wireless transmitter-receiver of Invention 12 is the wireless transmitter-receiver according to the second embodiment added with a remote operating direction detecting processor482and a control signal generator480which is capable of processing request information392.FIG. 14shows a circuit example of the control signal generator480.

The control signal generator480is provided with the remote operating direction detecting processor482on the input side.

A demodulated signal332is outputted from the receiving unit420and inputted to the remote operating direction detecting processor482.

Request information392is outputted from the remote operating direction detecting processor482and inputted to the control signal generator480.

The remote operating direction detecting processor482detects remote operating direction information in the information transmitted from the outside by using communication means, creates the request information392from the results, and outputs the request information392to the control signal generator480.

Moreover, the remote operating direction detecting processor482determines if the remote operation is valid or not by comparing the identification information such as a line number, IP address, URL, mail address, and MAC address of a remote operation sender with the “previously registered identification information of remote operation senders”.

The control signal generator480outputs a correction control signal352for changing the upper limit value of transmission power and the reception sensitivity on the basis of the request information392outputted by the remote operating direction detecting processor482.

Note that the “previously registered identification information of remote operation senders” is registered with intention by any of a communication carrier, a device manufacturer, and a user. Moreover, a wireless transmitter-receiver may create and register the information. Furthermore, the combination of the plurality of members mentioned above may be employed.

Here, the contents of the “previously registered identification information of remote operation senders” is considered to be a line number, IP address, URL, mail address, MAC address, etc. identifying the specific person in charge of management of the wireless transmitter-receiver.

The remote operation may use any communication containing the operating direction information. For example, a mail containing an operating direction code, a voice call signal containing operating direction pulses, a voice call signal containing operating direction tones, a phone call containing a number of operating direction times, etc. may be used.

Moreover, the remote operation makes it possible for a wireless transmitter-receiver in charge of management to operate and manage the states of transmission power of a plurality of the other wireless transmitter-receivers.

The examples of the wireless transmitter-receiver of Invention 13, in particular, only the added parts are described below.

The wireless transmitter-receiver, due to the means mentioned below, restores the decreased upper limit value of transmission power to the normal value when the wireless transmitter-receiver calls the previously registered “partner in the information transmission”.

The example of the wireless transmitter-receiver of Invention 13 is the wireless transmitter-receiver according to the second embodiment added with a communication partner detecting comparator483and a control signal generator480which is capable of processing request information393.FIG. 14shows a circuit example of the control signal generator480.

The control signal generator480is provided with a communication partner detecting comparator483on the input side.

The request information393is outputted from the communication partner detecting comparator483and inputted to the control signal generator480.

The communication partner detecting comparator483detects the identification information such as a line number, IP address, URL, mail address, and MAC address of the “partner in the information transmission” to start calling to, compares the identification information with the “identification information of previously registered important communication partners”, and outputs the request information393to the control signal generator480on the basis of the comparison results.

The control signal generator480makes the upper limit value of transmission power be greater or the maximum, and generates and outputs a correction control signal352for changing the reception sensitivity in conjunction with the upper limit value of transmission power.

For example, in the state in which transmission power has been set to be the “decreased transmission power below normal” when a call to a “partner in the information transmission” registered in the “identification information of previously registered important communication partners” is started, the “decreased transmission power below normal” can be restored to the “normal transmission power”. Moreover, the reception sensitivity that has been “decreased reception sensitivity below normal” also returns to the “normal reception sensitivity” in conjunction with the transmission power.

Note that the “identification information of previously registered important communication partners” is registered by any of a communication carrier, a device manufacturer, and a user. Moreover, a wireless transmitter-receiver may register a partner who has made many calls. Furthermore, the combination of the plurality of members mentioned above may be employed.

The contents of the “identification information of previously registered important communication partners” is considered to contain the line numbers, IP addresses, URLs, mail addresses, MAC addresses, etc. identifying, for example, the public institutions requiring high emergency in general such as police stations and firehouses, and the partners important to the user such as the family members, special friends, workplaces, and special business parties.

The examples of the wireless transmitter-receiver of Invention 14, in particular, only the added parts are described below.

The wireless transmitter-receiver of Invention 14 restores the transmission power that has been “decreased transmission power below normal” to the “normal transmission power” when the call from a “partner in the information transmission” registered in “identification information of previously registered important communication partners” is received. Moreover, the reception sensitivity that has been “decreased reception sensitivity below normal” also returns to the “normal reception sensitivity” in conjunction with the transmission power.

The example of the wireless transmitter-receiver of Invention 14 functions on the same configuration as that of the example of the wireless transmitter-receiver of Invention 13.

The communication partner detecting comparator483detects the identification information such as a line number, IP address, URL, mail address, and MAC address of the “partner in the information transmission” the call of which is received, compares the identification information with the “identification information of previously registered important communication partners”, and outputs the request information393to the control signal generator480on the basis of the comparison results.

The control signal generator480makes the upper limit value of transmission power be greater or the maximum, and generates and outputs a correction control signal352for changing the reception sensitivity in conjunction with the upper limit value of transmission power.

For example, in the state in which transmission power has been set to be “decreased transmission power below normal” when a call from a “partner in the information transmission” registered in the “identification information of previously registered important communication partners” is received, the “decreased transmission power below normal” can be restored to the “normal transmission power”. Moreover, the reception sensitivity that has been “decreased reception sensitivity below normal” also returns to the “normal reception sensitivity” in conjunction with the transmission power.

In the state in which the transmission power is restored to “normal transmission power” during the communication with the “partner in the information transmission” registered in the “identification information of previously registered important communication partners”, when the communication ends the transmission power is switched again to the “decreased transmission power below normal” at a certain timing. The transmission power may be switched to the “decreased transmission power below normal” soon after the communication ends or some period of time after the communication ends. Moreover, the state of reception sensitivity is switched in conjunction with the state of the transmission power.

An example of the wireless transmitter-receiver of Invention 15 is described below.

In the example of the wireless transmitter-receiver of Invention 15, the wireless transmitter-receiver according to the second embodiment, due to the additional means mentioned below for detecting and processing specific events, is capable of changing the upper limit value of transmission power and changing the reception power in conjunction therewith.

A wired earphone and microphone detector484, in particular, the additional part is described below.

The wireless transmitter-receiver, due to the added means mentioned below, restores the decreased upper limit value of transmission power to the normal value when a wired earphone or wired microphone is connected.

The example of the wireless transmitter-receiver is the wireless transmitter-receiver according to the second embodiment added with a wired earphone and microphone detector484and a control signal generator480which is capable of processing request information394.FIG. 14shows a circuit example of the control signal generator480.

The control signal generator480is provided with the wired earphone and microphone detector484on the input side.

The request information394is outputted from the wired earphone and microphone detector484and inputted to the control signal generator480.

The wired earphone and microphone detector484detects the connection of a wired earphone or wired microphone with a main body and then outputs the request information394to the control signal generator480.

The control signal generator480makes the upper limit value of transmission power be greater or the maximum, and changes the reception sensitivity in conjunction therewith.

Namely, the “decreased transmission power below normal” is restored to the “normal transmission power”. Moreover, the reception sensitivity that has been “decreased reception sensitivity below normal” also returns to the “normal reception sensitivity” in conjunction with the state of transmission power.

A wireless earphone and microphone detector485, in particular, the additional part is described below.

The wireless transmitter-receiver, due to the added means mentioned below, restores the decreased upper limit value of transmission power to the normal value when a wireless earphone or wireless microphone is connected.

The example of the wireless transmitter-receiver is the wireless transmitter-receiver according to the second embodiment added with a wireless earphone and microphone detector485and a control signal generator480which is capable of processing request information395.FIG. 14shows a circuit example of the control signal generator480.

The control signal generator480is provided with the wireless earphone and microphone detector485on the input side.

The request information395is outputted from the wireless earphone and microphone detector485and inputted to the control signal generator480.

The wireless earphone and microphone detector485detects the connection of a wireless earphone or wireless microphone with a main body and then outputs the request information395to the control signal generator480.

The control signal generator480makes the upper limit value of transmission power be greater or the maximum, and changes the reception sensitivity in conjunction therewith.

Namely, the “decreased transmission power below normal” is restored to the “normal transmission power”. Moreover, the reception sensitivity that has been “decreased reception sensitivity below normal” also returns to the “normal reception sensitivity” in conjunction with the state of transmission power.

A present position detecting area comparator486, in particular, the additional part is described below.

The wireless transmitter-receiver, due to the added means mentioned below, restores the decreased upper limit value of transmission power to the normal value when the wireless transmitter-receiver is located in the previously registered area.

The example of the wireless transmitter-receiver is the wireless transmitter-receiver according to the second embodiment added with a present position detecting area comparator486and a control signal generator480which is capable of processing request information396.FIG. 14shows a circuit example of the control signal generator480.

The control signal generator480is provided with the present position detecting area comparator486on the input side.

The request information396is outputted from the present position detecting area comparator486and inputted to the control signal generator480.

The present position detecting area comparator486detects and compares the present position information with the “previously registered area information”, and outputs the request information396to the control signal generator480.

The control signal generator480makes the upper limit value of transmission power be greater or the maximum, and changes the reception sensitivity in conjunction therewith.

Namely, the “decreased transmission power below normal” is restored to the “normal transmission power”. Moreover, the reception sensitivity that has been “decreased reception sensitivity below normal” also returns to the “normal reception sensitivity” in conjunction with the state of transmission power.

Note that the “previously registered area information” is registered with intention by any of a communication carrier, a device manufacturer, and a user. Moreover, a wireless transmitter-receiver may create and register the area information. Furthermore, the combination of the plurality of members mentioned above may be employed.

The contents of the “previously registered area information” is considered to contain the sites of medical facilities, etc.

A time information acquiring hours comparator487, in particular, the additional part is described below.

The wireless transmitter-receiver, due to the added means mentioned below, restores the decreased upper limit value of transmission power to the normal value when it is in the previously registered period of time.

The example of the wireless transmitter-receiver is the wireless transmitter-receiver according to the second embodiment added with a time information acquiring hours comparator487and a control signal generator480which is capable of processing request information397.FIG. 14shows a circuit example of the control signal generator480.

The control signal generator480is provided with the time information acquiring hours comparator487on the input side.

The request information397is outputted from the time information acquiring hours comparator487and inputted to the control signal generator480.

The time information acquiring hours comparator487acquires and compares the present time information with the “previously registered period of time”, and outputs the request information397to the control signal generator480.

The control signal generator480makes the upper limit value of transmission power be greater or the maximum, and changes the reception sensitivity in conjunction therewith.

Namely, the “decreased transmission power below normal” is restored to the “normal transmission power”. Moreover, the reception sensitivity that has been “decreased reception sensitivity below normal” also returns to the “normal reception sensitivity” in conjunction with the state of transmission power.

Note that the “previously registered period of time” is registered with intention by any of a communication carrier, a device manufacturer, and a user. Moreover, a wireless transmitter-receiver may create and register the information of a period of time. Furthermore, the combination of the plurality of members mentioned above may be employed.

The contents of the “previously registered period of time” are considered to contain the commuting hours to/from workplaces, schools, cram schools, etc.

An emergency call transmission detector488, in particular, the additional part is described below.

The wireless transmitter-receiver, due to the added means mentioned below, restores the decreased upper limit value of transmission power to the normal value when an emergency call transmission function is used.

The example of the wireless transmitter-receiver is the wireless transmitter-receiver according to the second embodiment added with an emergency call transmission detector488and a control signal generator480which is capable of processing request information398.FIG. 14shows a circuit example of the control signal generator480.

The control signal generator480is provided with the emergency call transmission detector488on the input side.

The request information398is outputted from the emergency call transmission detector488and inputted to the control signal generator480.

The emergency call transmission detector488detects the information outputted from the emergency call transmission function, and outputs the request information398to the control signal generator480.

The control signal generator480makes the upper limit value of transmission power be greater or the maximum, and changes the reception sensitivity in conjunction therewith.

Namely, the “decreased transmission power below normal” is restored to the “normal transmission power”. Moreover, the reception sensitivity that has been “decreased reception sensitivity below normal” also returns to the “normal reception sensitivity” in conjunction with the state of transmission power.

Note that the emergency call transmission function is provided to the wireless transmitter-receiver in the main body and enables a user to make a call to emergency contacts immediately and easily without inputting the line number in an emergency such as a fire and the other hazards.

The emergency contacts are considered to contain the public institutions such as police stations and firehouses, security companies, school staff, neighborhood association, and guardians.

An emergency warning reception detector489, in particular, the additional part is described below.

The wireless transmitter-receiver, due to the added means mentioned below, restores the decreased upper limit value of transmission power to the normal value when an emergency warning signal is received.

The example of the wireless transmitter-receiver is the wireless transmitter-receiver according to the second embodiment added with an emergency warning reception detector489and a control signal generator480which is capable of processing request information399.FIG. 14shows a circuit example of the control signal generator480.

The control signal generator480is provided with the emergency warning reception detector489on the input side.

A demodulated signal332is outputted from a receiving unit420and inputted to the emergency warning reception detector489.

The request information399is outputted from the emergency warning reception detector489and inputted to the control signal generator480.

The emergency warning reception detector489detects the received emergency warning signal, and outputs the request information399to the control signal generator480.

The control signal generator480makes the upper limit value of transmission power be greater or the maximum, and changes the reception sensitivity in conjunction therewith.

Namely, the “decreased transmission power below normal” is restored to the “normal transmission power”. Moreover, the reception sensitivity that has been “decreased reception sensitivity below normal” also returns to the “normal reception sensitivity” in conjunction with the state of transmission power.

Note that the emergency warning signal is a radio signal provided by activating the emergency call transmission function. The emergency warning signal may be a radio signal provided on the basis of the earthquake information or tsunami information issued by administrative agencies.

Note that the correction control signal352inputted to the determination unit for communication compatibility430in the present embodiment corresponds to the “reference value in determining if the communication is compatible” in Invention 4.

Fifth Embodiment

A wireless transmitter-receiver according to a fifth embodiment of the present invention is explained.FIG. 5shows a basic configuration of the wireless transmitter-receiver according to the fifth embodiment.

The wireless transmitter-receiver detects the present location thereof, decreases the upper limit value of transmission power, and also decreases the reception sensitivity in conjunction therewith if the wireless transmitter-receiver locates in the previously registered area. Namely, the transmission power and the reception sensitivity are decreased simultaneously.

The wireless transmitter-receiver according to this embodiment is the wireless transmitter-receiver according to the second embodiment which is added with a present position detecting area comparator486and a control signal generator480which is capable of processing request information396.FIG. 14shows a circuit example of the control signal generator480.

The control signal generator480is provided with the present position detecting area comparator486on the input side.

The request information396is outputted from the present position detecting area comparator486and inputted to the control signal generator480.

The present position detecting area comparator486detects the present location of the wireless transmitter-receiver, judges which the location is inside or outside of the area indicate by “previously registered area information”, then judges whether the state of transmission power is to be switched or not, and outputs the result to the control signal generator480as the request information396.

The control signal generator480generates and outputs a correction control signal352on the basis of the request information396. The correction control signal352is outputted to a determination unit for transmission power460and simultaneously to a determination unit for communication compatibility430.

Namely, the determination unit for transmission power460and the determination unit for communication compatibility430are controlled by a single operation.

Therefore, the wireless transmitter-receiver can switch transmission power to “decreased transmission power below normal” and restore to “normal transmission power” in accordance with the location of the wireless transmitter-receiver. Reception sensitivity is also switched to “decreased reception sensitivity below normal” and restored to “normal reception sensitivity” in conjunction with switching of transmission power.

Note that the correction control signal352inputted to the determination unit for communication compatibility430in the present embodiment corresponds to the “reference value in determining if the communication is compatible” in Invention 4.

Modification Example

A modification example in which a wireless transmitter-receiver according to the first to fifth embodiments is applied to the wireless transmitter-receiver in a mobile communication system and area information of a site of a hospital is registered in the “previously registered area information” is explained.

In the case when a picocell is installed in a hospital ward, the wireless transmitter-receiver that is set as a “partner in radio transmission and reception” by the picocell can suppress the transmission power. However, if the wireless transmitter-receiver, for example, is placed at the window and, therefore, the radio wave propagated from a radio base station located outside the site of the hospital is stronger, the wireless transmitter-receiver performs communication with high transmission power in accordance with the radio wave propagated from the radio base station outside and may consequently fail to suppress the transmission power.

Even in that case the wireless transmitter-receiver can securely suppress the transmission power in the site of the hospital by registering the area information of the site of the hospital in the “previously registered area information” as in the wireless transmitter-receiver according to the fourth embodiment.

Note that the picocell has a function of a radio base station in a mobile communication system, in particular, a small radio base station for in-building radio transmission and reception covering a limited small area with low transmission power.

In the first to fifth embodiments an example of the wireless transmitter-receiver is described, that is, the case in which when a user changes transmission power, a change is also given to the “reception system” at the same time to suppress the harmful influence caused by changing the transmission power and prevent the user from being confused.

In the first to fifth embodiments the examples of the wireless transmitter-receivers applied in a mobile communication system are described. However, the present invention can be employed in one-to-one communication such as a transceiver.

In the second to fifth embodiments the wireless transmitter-receiver measures the intensity of the received radio wave, controls transmission power on the basis thereof, and determines the state in which the suitable communication is expectable. However, in a digital communication system a wireless transmitter-receiver may measure the error rate of the received data as an alternative to measuring the intensity of the received radio wave, control reception sensitivity on the basis of the error rate, and determine the state in which the suitable communication is expectable.

In the first embodiment and the modification example a configuration wherein reception sensitivity is decreased in accordance with the upper limit value of power consumption decreased by an operation of an operation means114. However, in a digital communication system not limited to the configuration above, a configuration wherein an allowance for an error rate of received data is decreased in accordance with the upper limit value of transmission power decreased by an operation of an operation means114can be employed. Concretely speaking, in the state of the “normal transmission power” the communication is determined compatible when the error rate of received data is not higher than a first threshold value (an allowance for the error rate), and in the state of the “decreased transmission power below normal” the communication is determined compatible when the error rate of received data is not higher than a second threshold value (an allowance for the error rate) that is lower than the first threshold value.

In the first to fifth embodiments and the modification examples, not limited to the configuration wherein transmission and reception are controlled with a single operation, (1) a configuration wherein transmission and reception are controlled with a plurality of operations, (2) a configuration wherein transmission is controlled with a first operation (a single or a plurality of operations) and then reception is controlled with a second operation (a single or a plurality of operations), (3) a configuration wherein reception is controlled with a first operation (a single or a plurality of operations) and then transmission is controlled with a second operation (a single or a plurality of operations), or (4) a configuration wherein transmission is controlled with a prescribed operation (a single or a plurality of operations) and reception is controlled without an operation so that the reception range and the transmission range coincides or the portion in which the both ranges do not coincide is minimized may be employed. Moreover, a prescribed operation which works as a trigger to control transmission or reception may act as a common operation to activate the other functions. For example, if the prescribed operation is made common to the operation to increase and decrease phone volume, the upper limit value of transmission power is decreased in association with the operation to lower phone volume.

In the first to fifth embodiments and the modification examples, the configuration, wherein the reception performance (for example, reception sensitivity, a reference value in determining if the communication is compatible, and an allowance for an error rate of received data) is decreased in accordance with the upper limit value of transmission power decreased by an operation of an operation means114, is employed. However, not limited to the configuration above, for example, in the configuration wherein a wireless transmitter-receiver notifies a radio base station of the reception state and the radio base station controls transmission power, etc. on the basis of the reception state, a reception state in the case when reception performance is decreased or assumed to be decreased in accordance with the upper limit value of transmission power decreased by a prescribed operation may be notified to a partner in communication. In this configuration the wireless transmitter-receiver may decrease reception performance as in the first to fifth embodiments or need not to decrease reception performance. If the wireless transmitter-receiver actually decreases the reception performance, the wireless transmitter-receiver notifies a partner in communication of the reception state in which the reception performance is decreased in accordance with the decreased upper limit value of transmission power. Meanwhile, if the wireless transmitter-receiver does not decrease the reception performance and pretends to decrease the reception performance for the radio base station, the wireless transmitter-receiver notifies a partner in communication of the simulated reception state assuming that the reception performance is decreased in accordance with the decreased upper limit value of transmission power. The reception state is indicated in an analog communication system, for example, as “Present reception intensity is ##[dB].” and in a digital communication system, for example, as “Present error rate is ##.” The transmitted signal only needs to contain the information of “##”.

In the first embodiment and the modification example, the configuration wherein only the upper limit value of transmission power in the transmission power properties is decreased as shown inFIGS. 22(a) and (d) is employed. However, not limited to the configuration, for example, the configuration wherein the whole properties of transmission power are decreased may be employed. The same also applies to the second to fifth embodiments and the modification examples thereof.

In the first embodiment and the modification example, the configuration wherein the reception sensitivity is decreased to a fixed value813regardless of the propagation loss as shown inFIGS. 22(b) and (e) is employed. However, not limited to the configuration, for example, the configuration wherein the reception sensitivity is decreased stepwise from the maximum reception sensitivity to a fixed value813as the propagation loss increases may be employed. The same also applies to the second to fifth embodiments and the modification examples.

In the first embodiment and the modification example, the configuration wherein the wireless transmitter-receiver decreases the upper limit value of transmission power by an operation of an operation means114and decreases the reception sensitivity in accordance with the decreased upper limit value of transmission power is employed. However, the configuration wherein when the maximum transmission power804is used inFIG. 22the wireless transmitter-receiver sets a lower value (fixed value813) than the transmission power (maximum transmission power804) needed for the communication with a radio base station as the upper limit value of transmission power to suppress transmission power may be employed. The same also applies to the second to fifth embodiments and the modification examples.

EXPLANATION OF LETTERS OR NUMERALS

116means for detecting and processing various events

123automatic gain control amplifier

124automatic gain control amplifier A

125automatic gain control amplifier B

129reception level generator

171carrier wave generator

173transmission power controller

313converted reception level signal

335reception level signal

337signal intensity information A

338signal intensity information B

339signal error rate information

343determination signal for communication compatibility

352correction control signal

362transmission power control signal

391-399request information

430,440determination unit for communication compatibility

450,480control-signal generation unit

460determination unit for transmission power

481operating direction processor

482remote operating direction detecting processor

484wired earphone and microphone detector

485wireless earphone and microphone detector

486present position detecting area comparator

487time information acquiring hours comparator

488emergency call transmission detector

489emergency warning reception detector

533inverting amplifier built by means of an analog circuit

553comparator built by means of an analog circuit

554adder built by means of an analog circuit

555subtractor built by means of an analog circuit

556adder built by means of a logic circuit

557subtractor built by means of a logic circuit

558weighted comparator built by means of a logic circuit

559level limiter built by means of an analog circuit

567gain-changeable power amplifier

717level restriction reference voltage

803propagation loss between a conventional wireless terminal (or a wireless transmitter-receiver according to a first embodiment) and a radio base station

804maximum transmission power that a wireless transmitter-receiver (or a conventional wireless terminal) can exert

805maximum reception sensitivity that a wireless transmitter-receiver (or a conventional wireless terminal) can exert

807,812range of the propagation loss where a wireless transmitter-receiver (or a conventional wireless terminal) can transmit a signal to a radio base station

808,814range of the propagation loss where a wireless transmitter-receiver (or a conventional wireless terminal) can receive a signal from a radio base station

809range of the propagation loss where a conventional wireless terminal cannot transmit a signal to a radio base station

810range of the propagation loss where a conventional wireless terminal cannot receive a signal from a radio base station

811,813,816a fixed value

911key switch for setting transmission power and reception sensitivity to be normal

912key switch for setting transmission power and reception sensitivity to be in lower states than normal

961A user performs an operation for decreasing transmission power.

964Determines if fine communication is expectable

972hatching section indicating a set upper limit value of transmission power

973black section indicating a present transmission power

974sign of signal intensity when using normal reception sensitivity

975sign of signal intensity when using decreased reception sensitivity

978sign of transmission power

982hatching section indicating a set upper limit value of transmission power

983black section indicating a present transmission power

984sign of signal intensity with normal reception sensitivity (left bars)

985sign of signal intensity with decreased reception sensitivity (right bars)

988sign of transmission power

992reciprocal of a reception level signal

993correction control signal

994transmission power characteristics without correction control

995transmission power characteristics corrected by −10 [dB]

996transmission power characteristics corrected by −20 [dB]

997transmission power characteristics of a conventional wireless transmitter-receiver