JPH1093503A - Transmission output saving device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably activate a power save function to prevent a radio wave interference or the like by saving transmission power required or over operated when an excellent communication state is ensured in a radio communication system. SOLUTION: A plurality of antennas 1a, 1b with different gains are provided. When a reception electric field intensity detected therein is higher than a reference reception electric field intensity, the antenna 1a at a low gain is used and when smaller, the antenna 1b with a high gain is used to save power without adjusting the gain of a power amplifier 9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio communication system such as a cellular system and a PHS (Personal Handy-phone System), for example, in a transmission output between a radio base station and a mobile terminal, and between mobile terminals. The present invention relates to a transmission output saving device for reducing the transmission output.

[0002]

2. Description of the Related Art The concept of an early cordless telephone that enables wireless communication between a master unit and a slave unit indoors has been changed to a concept that allows easy communication by wireless communication even outdoors. In recent years, wireless communication networks based on base stations and portable mobile terminal devices have been rapidly constructed in recent years.

[0003] In the mobile terminal device as described above, in order to reduce the power consumption and at the same time, to suppress the radio interference caused by the radio wave emitted by the mobile terminal device, the mobile terminal device must be able to stably maintain the communication state. In many cases, a power saving function for controlling the transmission output to be as small as possible is provided.
As shown in the figure, the transmission / reception changeover switch 20 converts the received signal a 'obtained from the antenna 21 into an IF (Interme
diate Frequency (intermediate frequency) amplifier 22 and RSSI (R
The level of the RSSI level d 'is obtained by the level detector 23. This RSSI level has a voltage level corresponding to the reception electric field strength, and is RF (Radio Frequency).
The cy (radio frequency) controller 24 controls the output adjustment circuit 25 based on the value of the RSSI level d 'to adjust the gain of the power amplifier 26, thereby activating the power saving function.

[0004]

In a communication system using a portable mobile terminal device as described above, radio waves reflected or diffracted by buildings or the like cause interference, but due to movement or changes in the communication environment, etc. Since the state of interference fluctuates from moment to moment, the level of the received electric field strength at the base station or the portable mobile terminal, that is, the RSSI level also keeps constantly fluctuating. However, when the output is changed by adjusting the gain of the power amplifier 26 as in the above-described conventional example, it is difficult to control the output stably. The problem of becoming very unstable arises.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a wireless communication system in which at least one of the mobile terminals is a power terminal in accordance with a radio wave communication state. An object of the present invention is to provide a transmission output saving device capable of stably maintaining an output when saving.

[0006]

According to a first aspect of the present invention, there is provided a transmission power saving apparatus comprising: a plurality of antennas having different gains; and an antenna switching unit. The transmission output is switched by switching the antenna by the antenna switching unit. In the above configuration, since the transmission output is switched by switching to an antenna having a different sensitivity, it is not necessary to adjust the gain of the amplifier that is difficult to adjust, and the transmission output after executing the power save can be stabilized. For example, if the transmission output saving device is applied to a mobile terminal of mobile communication and the transmission output is switched during power saving, the transmission output from the mobile terminal can be stabilized, so that a stable communication state is maintained. It becomes possible.

According to a second aspect of the present invention, in order to solve the above-mentioned problem, in addition to the configuration of the first aspect, the transmission output saving apparatus divides a range of a detectable reception electric field strength into the number of the antennas. A plurality of thresholds are stored, and an antenna with a higher gain is set to be used in a range where the reception electric field strength is weaker, and the detected reception electric field strength is changed according to the fluctuation of the reception electric field strength. Control means for controlling the antenna switching means is provided so that the set antenna is connected. With the above configuration, when the reception electric field strength is strong and the partner station is nearby, communication is possible even if the transmission output is reduced, so communication is performed by switching to an antenna with low sensitivity, If it is necessary to increase the transmission output and perform communication, such as when the receiving electric field strength is weak, the partner station is far away or the communication condition is not good, connect to a highly sensitive antenna to perform communication. Therefore, the transmission output can be switched without adjusting the gain on the amplifier side so that the transmission is not performed with a transmission output that is more than necessary. Obstacles can be stably suppressed.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIG. In the present embodiment, a configuration relating to the operation at the time of power saving, that is, the operation of reducing the transmission output of the mobile terminal device in the wireless communication system, will be described. However, the following configurations and effects can also be applied to the base station side.

As shown in FIG. 1, the mobile terminal device includes antennas 1a and 1b having different gains, an antenna switch 2 for switching the antennas 1a and 1b,
A transmission / reception switch 3 for switching between a transmission signal and a reception signal is provided. Further, an IF amplifier 4 for amplifying a received radio wave and outputting an RSSI signal indicating the level of the radio wave, a modem 5 for modulating and demodulating the signal, and a voice signal (not shown) for transmitting a signal before modulation and a received signal after demodulation. Based on the RSSI signal, the RF controller 6 controls the switching timing of the antenna switch 2 and the transmission / reception switch 3 while communicating with the converter.
An RSSI level detector 7 for detecting the level of the RSSI signal is provided.

Further, there are provided a quadrature modulator 8 for performing quadrature modulation of a modulated transmission signal from the modem 5 and a power amplifier 9 for performing amplification for transmission from a connected antenna. However, in the above description, it is assumed that the antenna 1a has a lower gain than the antenna 1b. Although not shown, an audio conversion unit having an ADPCM codec unit, a microphone, a receiver, and the like is connected to the RF control unit 6, and the RF control unit 6 performs simple confidential processing, scrambling processing, It also performs timing control related to divided transmission and reception.

The operation of the mobile terminal device at the time of power saving based on the above configuration will be described. In FIG. 1, at the time of reception, first, a received radio wave a received by any one of the antennas selected by the antenna changeover switch 2 is sent to the IF amplifier 4 by the transmission and reception changeover switch 3,
The IF signal b is output and the received radio wave a
The RSSI signal c corresponding to the electric field strength of the above is output. That is, the magnitude of the received electric field strength can be known from the RSSI signal c. After being demodulated by the demodulation unit 5a of the modem 5, the IF signal b is sent to the RF control unit 6, and is converted into audio via an ADPCM codec and a receiver of an audio conversion unit (not shown).

On the other hand, at the time of transmission, the transmission signal converted from the voice by the microphone of the voice converter (not shown) and the ADPCM codec is transmitted to the modem 5 via the RF controller 6.
Is modulated by the quadrature modulator 8 and then amplified by the power amplifier 9 to an output that can be transmitted. Since the RF control unit 6 switches the transmission / reception changeover switch 3 to the transmission side during transmission, the transmission signal is emitted as a radio wave via the antenna connected to the antenna changeover switch 2. In the above, R
The SSI signal c is input to the RSSI level detector 7,
The RSSI level d is proportional to the received electric field strength, and RF
It is input to the control unit 6.

In the RF control unit 6, the RSSI level d
The threshold value is compared with the threshold value, and this threshold value is determined when a call is made using the antenna 1a having a lower gain.
The RSSI level at the time of the received electric field strength immediately before the occurrence of noise or sound interruption (hereinafter referred to as reference received electric field strength) is set, and which of the antennas 1a and 1b is selected depends on the detected RSSI. It is determined by the result of the comparison between the level d and the threshold value. That is, if the RSSI level d is larger than the threshold value at the time of reception, the current reception electric field strength is higher than the reference reception electric field strength, which means that reception can be performed even when the antenna 1a having a low gain is connected. Also, this means that the distance to the partner station or the base station is short or there are few obstacles, so that communication can be performed even if the transmission output is low, and the transmission output is within the range where communication is possible. However, if the antenna is connected to the antenna 1a having a low gain as described above, the transmission output necessarily decreases.
There is no need to adjust the gain of.

Conversely, if the RSSI level d is smaller than the threshold value, the current received electric field strength is lower than the reference received electric field strength, so that it is necessary to connect to the antenna 1b having a higher gain. Also, in this case, it means that the distance to the partner station or the base station is long or there are many obstacles, so it is necessary to increase the transmission output. However, if the antenna is connected to the antenna 1b having a high gain, the transmission efficiency is increased. Since the rising transmission output is improved, it is not necessary to adjust the gain of the power amplifier 9. Of course, it is necessary to set the above-mentioned reference reception electric field strength and adjust the relationship between the reception sensitivity of the mobile terminal device itself and the transmission output so as to be in an optimum state.

As described above, by providing a plurality of antennas with different sensitivities and performing simple control of switching the antenna to be connected according to the received electric field strength and changing the transmission output, stable control is difficult. Since it is not necessary to control the gain of the power amplifier, the transmission output from the power amplifier can be stabilized. As a result, the output during power saving can be stably maintained.

[0016]

As described above, the transmission output saving apparatus according to the first aspect of the present invention includes a plurality of antennas having mutually different gains and the antenna switching means. This is a configuration performed by switching the antenna by means. Therefore, since it is not necessary to switch the transmission output by adjusting the gain of the amplifier, which is difficult to adjust, it is possible to stabilize the transmission output after switching the transmission output at the time of power saving or the like. This has an effect that a stable communication state can be maintained even after the power save.

According to a second aspect of the present invention, in addition to the configuration of the first aspect, the transmission power saving device according to the second aspect of the present invention stores the range of the detectable reception electric field intensity in the number of the antennas and stores it. An antenna having a higher gain is set to be used in a range where the reception electric field strength is weaker, and the antenna set for the detected reception electric field strength is connected according to the fluctuation of the reception electric field strength. Thus, the control means for controlling the antenna switching means is provided. Therefore, in addition to the effect of the configuration of claim 1, since the antenna is switched according to the level of the reception electric field intensity, the transmission output is changed to an appropriate transmission output according to the reception situation, and the transmission is performed with an unnecessary transmission output. As a result, there is an effect that it is possible to stably suppress radio wave interference generated in the communication device main body due to radio waves emitted by the communication device itself.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration example of a mobile terminal device according to the present invention.

FIG. 2 is a block diagram illustrating a mobile terminal device according to a conventional transmission power saving device.

[Explanation of symbols]

 1a antenna 1b antenna 2 antenna changeover switch (antenna changeover means) 3 transmission and reception changeover switch 4 IF amplifier 5 modem 5a demodulation section 5b modulation section 6 RF control section (control means) 7 RSSI level detection section 8 quadrature modulator 9 power amplifier

Claims (2)

[Claims] 1. A transmission output saving device comprising: a plurality of antennas having mutually different gains; and antenna switching means, wherein switching of transmission output is performed by antenna switching by the antenna switching means. 2. A plurality of thresholds for dividing a range of a detectable reception electric field strength into the number of the antennas are stored.
An antenna having a higher gain is set to be used in a range where the reception electric field strength is weaker, and the antenna set for the detected reception electric field strength is connected according to the fluctuation of the reception electric field strength. 2. The transmission power saving device according to claim 1, further comprising control means for controlling the antenna switching means.