JP3056853B2 - Wireless communication device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio communication apparatus used in a mobile radio communication system such as a portable / automobile radio telephone system and a cordless radio telephone apparatus, and more particularly to an apparatus provided with transmission power control means.

[0002]

2. Description of the Related Art Conventionally, as one of mobile radio communication systems, for example, a cellular radio communication system has been operated. This system includes a control station CS connected to a wired telephone network NW as shown in FIG.
S, a plurality of base stations BS1 to BSn connected to the mobile station P via wired lines CL1 to CLn, respectively.
S1 to PSm. Each of the above base stations BS
1 to BSn form radio zones E1 to En generally called cells in different areas. Mobile station PS1
ＰＳPSm are connected to the base station of the cell in which the own station is located via a free wireless communication channel, and further connected from this base station to the wired telephone network NW via the control station CS. When the mobile stations PS1 to PSm move to another cell during communication, the base station of the connection destination is switched to the base station of the movement destination cell while continuing the communication.

By the way, a mobile station radio communication device used in such a system uses its own transmission power based on transmission power designation information transmitted from a base station BS when setting up a radio channel, for example. Some have a circuit to control. FIG. 4 is a circuit block diagram showing an example of the configuration.

In FIG. 1, a transmission wave is level-controlled by a variable attenuator 1 and then power-amplified by a power amplifier 2 and transmitted from an antenna (not shown). Also,
Part of the transmission wave output from the power amplifier 2 is input to a level detection circuit 3, where the transmission power level is detected. Then, the detected value of the transmission power level is input to the error amplifier circuit 4. The error amplifier 4 detects an error between the detected value of the transmission power level and the reference voltage generated by the reference voltage generator 5. Then, the error signal is held in a holding circuit 6 composed of, for example, a capacitor, and then is used as a control signal for the amount of attenuation.
Will be fed back. Therefore, the amount of attenuation of the variable attenuation circuit 1 is feedback-controlled, whereby the transmission power of the transmission wave is controlled to a value corresponding to the reference voltage. The reference voltage generation circuit 5 generates a reference voltage according to the transmission power designation information sent from the base station.

On the other hand, in recent cellular type portable radio telephone systems, a time division multiple access (TDM) is used as a connection method between a base station and a mobile station in order to increase the capacity of the mobile station.
A) It has been proposed to adopt the method. In the TDMA system, for example, as shown in FIG. 5 (a), the format of a transmission signal is a frame configuration in which six time slots are time-division multiplexed. A time slot is selected and assigned to a mobile station, and thereafter, wireless communication with the mobile station is performed using this time slot.
When this system is used, the mobile station performs transmission only during the time slot to which the mobile station is allocated, as shown in FIG.

[0006]

However, such a T
In a mobile station device of a system adopting the DMA system,
Attempts to control the transmission power have caused the following problems. That is, when the communication is started, the mobile station device performs the transmission operation only during the time slot allocated to the own station as described above, and enters the transmission stop state during the other time slots. For this reason, if the feedback time constant of the transmission power control circuit, that is, the capacity of the capacitor of the holding circuit 6, is small, the attenuation value set in the transmission period of the own time slot is initialized each time another non-transmission time slot period starts. As a result, the transmission power becomes unstable due to the transient response of the feedback loop at the start of transmission of its own time slot.

Therefore, in the prior art, the feedback time constant is generally set to a large value by using a large-capacity capacitor for the holding circuit 6, so that the control signal value of the attenuation amount during the transmission stop period of another time slot is reduced. A method is used to keep it from changing. However, if the feedback time constant is set to a large value in this way, the reference voltage value changes when the base station sends an instruction to change the transmission power when setting up a wireless line in response to an outgoing or incoming call, or during communication. In such a case, it takes a long time for the transmission power control circuit to stabilize, which causes another problem that the time required for connection of the wireless line becomes longer.

The present invention has been made in view of the above circumstances. It is an object of the present invention to stably maintain the transmission power during a communication period and to reduce the transmission power at the start of communication or when the transmission power is changed. It is an object of the present invention to provide a wireless communication device that can be started up in a short time to shorten a connection time.

[0009]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention detects a transmission power level of a transmission wave output from a transmission power variable circuit, and compares this level detection value with a predetermined reference value. A transmission power control loop for generating a level control signal for variably controlling the gain of the transmission power variable means includes control means for controlling the loop, and the control means controls a plurality of times of the digital radio line. During the transmission period of the time slot assigned to itself among the slots, the level control signal generated by the loop is directly supplied to the transmission power variable circuit,
During the other time slot periods, the level control signal generated by the loop during the immediately preceding time slot transmission period is continuously supplied to the transmission power variable circuit.

[0010]

As a result, according to the present invention, the transmission power control loop operates only during the time slot assigned to itself, and the transmission power control loop is fixed during the other time slots. During another time slot, that is, during the non-transmission period, the gain of the transmission power variable circuit does not change and is kept at the value during the transmission period. For this reason, a problem that the transmission power becomes unstable due to the occurrence of a transient response in each own time slot is prevented, and the transmission power during communication is stably maintained. On the other hand, since the feedback time constant of the transmission power control loop can be set to a small value, the transmission power can be started up in a short time at the start of communication or when the transmission power is changed. The time required, that is, the wireless connection time can be reduced.

[0011]

FIG. 1 is a circuit block diagram showing a configuration of a mobile station radio communication apparatus according to an embodiment of the present invention. This device is roughly divided into a transmission system, a reception system, and a control system.
Incidentally, reference numeral 40 denotes a battery as a power supply.

The transmission system includes a transmitter 11 and a speech encoder (S
PCOD) 12 and an error correction encoder (CHCOD) 13
, A digital modulator (MOD) 14, and an adder 15
, A transmission power control circuit (APC) 16, a high frequency switch circuit (SW) 17, and an antenna 18. The speech encoder 12 encodes a transmission signal output from the transmitter 11. Error correction encoder 13
Then, the error correction encoding of the digitized transmission signal output from the voice encoder 12 and the digitized control signal output from the control circuit 31 described later is performed. The digital modulator 14 generates a modulation signal corresponding to the digitized transmission signal output from the error correction encoder 13. In the adder 15, this modulated signal is added to the carrier signal output from the frequency synthesizer 32, and the frequency is converted by this. And the transmission power control circuit 1
At 6, the wireless transmission wave output from the adder 15 is amplified to a predetermined transmission power. The high-frequency switch 17 is in a conductive state only during a transmission time slot designated by the control circuit 31, and supplies a radio transmission wave output from the power amplifier 16 to the antenna 18 during this period to transmit the radio transmission wave from the antenna 18 to the base station BS. Send to.

On the other hand, the receiving system includes a receiver (RX) 21.
, A digital demodulator (DEM) 22, an error correction decoder (CHDEC) 23, and a speech decoder (SPDEC) 2.
4 and a receiver 25. In the receiver 21,
In a predetermined time slot, frequency conversion of a radio reception wave received by the antenna 18 and the high-frequency switch 17 is performed. In the digital demodulator 22, bit synchronization and frame synchronization with respect to the reception signal output from the receiver 21 are performed, and the synchronization signal is transmitted to the control circuit 31.
Supplied to In the error correction decoder 23, the digital demodulated signal output from the digital demodulator 22 is subjected to error correction decoding. Then, the digitized reception signal obtained by the error correction decoding is output to the audio decoder 24, and the digitization control signal is supplied to the control circuit 31. In the voice decoder 24, the digitized speech signal is decoded. Then, the analog reception signal restored by the decoding process is received by the receiver 25.
From the speaker.

The control system includes a control circuit (CONT) 31.
, A frequency synthesizer (SYN) 32, a reception field strength detection circuit (RSSI) 33, and a transmission request switch 34
And The frequency synthesizer 32 generates a local oscillation frequency corresponding to the wireless channel specified by the control circuit 31. The reception electric field strength detection circuit 33 detects the reception electric field strength of the radio wave transmitted from the base station BS, and the detection signal is supplied to the control circuit 31.

The transmission power control circuit 16 is configured as follows. FIG. 2 is a circuit block diagram showing the configuration. In this figure, the same parts as those in FIG. 4 are denoted by the same reference numerals.

The transmission power control circuit 16 includes a variable attenuation circuit 1, a power amplification circuit 2, a level detection circuit 3, an analog / digital (A / D) conversion circuit 61, an operation circuit 62, and a reference value storage. The circuit includes a circuit 63, a latch circuit 64, a timing signal generation circuit 65, and a digital / analog (D / A) conversion circuit 66. The A / D conversion circuit 61 converts the level detection value output from the level detector 3 into a digital signal and inputs the digital signal to the arithmetic circuit 62. The reference value storage circuit 63 stores a reference value consisting of a digital value set by the control circuit 31 according to the transmission power instruction information sent from the base station, and supplies this reference value to the arithmetic circuit 62. The arithmetic circuit 62 calculates a difference component between the reference value supplied from the reference value storage circuit 63 and the level detection value input from the A / D conversion circuit 61,
An attenuation control signal for controlling the variable attenuation circuit 1 is generated and input to the latch circuit 64. The timing signal generation circuit 65 applies a timing signal generated at a predetermined cycle to the latch circuit 64 only during the transmission period of the time slot assigned to the own station. Latch circuit 64
Latches the attenuation control signal supplied from the arithmetic circuit 62 in synchronization with the timing signal. The D / A conversion circuit 66 converts the attenuation control signal output from the latch circuit 66 into an analog signal and feeds it back to the variable attenuation circuit 1. Next, the operation of the device configured as described above will be described. Here, a case where TS1 and TS2 are assigned as transmission time slots will be described as an example.

It is now assumed that a burst transmission wave shown in FIG. 3A is input to the transmission power control circuit at the start of communication. Then, this transmission wave is first input to the variable attenuation circuit 1 and is attenuated to a level corresponding to the initial state of the variable attenuation circuit 1. The attenuated transmission wave is amplified at a predetermined gain in the power amplification circuit 2, and a part of the amplified transmission wave is input to the level detection circuit 3. The level detection circuit 3 detects the transmission power of the input transmission wave. The detection value of the level detection circuit 3 is converted into a digital signal by an A / D conversion circuit 61 and then input to an arithmetic circuit 62.
The arithmetic circuit 62 calculates a difference component between the transmission power detection value supplied from the level detection circuit 3 and the reference value supplied from the reference value storage circuit 63, and generates an attenuation control signal for eliminating the difference component. This is generated and supplied to the latch circuit 64. The latch circuit 64 sequentially latches the attenuation control signal input from the arithmetic circuit 62 in accordance with the timing signal shown in FIG. 3E generated from the timing signal generating circuit 65. Then, this latch output is converted into an analog signal by the D / A conversion circuit 66 and then fed back to the variable attenuation circuit 1.

That is, at the start of communication, the transmission power rises at a high speed with the cycle of the timing signal as the feedback time constant of the transmission power loop. Therefore, for example, if the attenuation of the variable attenuating circuit 1 is minimized in the standby state, the power of the transmission wave output from the power amplifying circuit 2 becomes the first short time as shown in FIG. Only after the change due to the transient response is shown, the value quickly converges to a value corresponding to the reference value.

Further, it is assumed that, for example, an instruction to change the transmission power arrives from the base station during communication, and the reference voltage changes due to this. Also in this case, the transmission power control loop operates at high speed using the period of the timing signal as a feedback time constant, whereby the transmission power level of the transmission wave is changed in accordance with the reference voltage in a short period of time as shown in FIG. Converge to the value obtained. That is, the transmission level of the transmission wave rises in a short period of time both at the start of communication and when the transmission power is changed.

On the other hand, after the communication is started, the timing signal is supplied to the latch circuit 64 only during the time slots TS1 and TS2 assigned to the own station as shown in FIG.
, And the period of the other time slot is cut off. Therefore, during the period of another time slot, the latch circuit 6
4, no new attenuation control signal is latched,
The latch output of the latch circuit 64 is held in the attenuation control signal latched last during its own time slot. Therefore, even if the input of the transmission wave is interrupted as shown in FIG. 3 (b) during another time slot period, the transmission power control loop does not respond to this input interruption state. The power is kept stable without causing a transient response every time slot.

As described above, according to the present embodiment, the latch circuit 64 is used only for the transmission period of the time slot assigned to itself.
Since the transmission power control loop is operated by supplying a timing signal to the transmission power control loop, and the timing signal is cut off during the other time slots, the transmission power control loop is fixed to the state of its own time slot. The transmission power control loop operates in the time slot period of the time slot, thereby preventing the transmission power from causing a transient response change in each time slot. As a result, the transmission power during the communication period can be kept stable. it can.

Further, since the time constant can be set small, it is possible to quickly raise the transmission power at the start of communication and at the time of changing the transmission power, thereby shortening the connection time of the wireless line. be able to. It should be noted that the present invention is not limited to the above-described embodiment, and it is needless to say that various modifications can be made without departing from the spirit of the present invention.

[0023]

According to the present invention, the transmission power control loop is operated only during the time slot assigned to itself, the transmission power control loop is fixed during other time slots, and the transmission power control loop is latched last during the own time slot. Since the power control signal is fed back to the variable attenuating circuit 1, a problem that the transmission power becomes unstable due to the occurrence of a transient response in each time slot is prevented, whereby the transmission power during communication becomes stable. Is held. In addition, since the feedback time constant of the transmission power control loop can be set to a small value, a wireless communication device capable of starting up the transmission power in a short time at the start of communication or changing the transmission power to shorten the connection time can be provided. Can be provided.

[Brief description of the drawings]

FIG. 1 is a circuit block diagram showing a configuration of a mobile station device of a wireless communication system according to one embodiment of the present invention.

FIG. 2 is a circuit block diagram showing a configuration of a transmission power control circuit in the device shown in FIG.

FIG. 3 is a diagram for explaining a format of a transmission signal in a TDMA system.

FIG. 4 is a circuit block diagram showing a configuration of a transmission power control circuit according to a conventional example.

FIG. 5 is a diagram showing a format of a transmission signal in the circuit shown in FIG. 4 and a relationship between a timing signal and a power level of an input / output signal.

FIG. 6 is a schematic configuration diagram illustrating an example of a portable wireless communication system.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Variable attenuation circuit, 2 ... Power amplification circuit, 3 ... Level detection circuit, 4 ... Error amplification circuit, 5 ... Reference voltage generation circuit, 6 ...
Holding circuit, 11: transmitter, 12: voice encoder (SPCO)
D), 13: Error correction encoder (CHCOD), 14: Digital modulator (MOD), 15: Adder, 16: Transmission power control circuit (APC), 17: High frequency switch circuit (SW), 18: Antenna, 21: Receiver (RX), 2
2 ... Digital demodulator (DEM), 23 ... Error correction decoder (CHDEC), 24 ... Speech decoder (SPDEC),
25 receiver, 31 control circuit (CONT), 32 frequency synthesizer (SYN), 33 reception electric field strength detection circuit (RSSI), 34 transmission request switch, 40 battery, 61 analog / digital (A / D) ) Conversion circuit, 62 arithmetic circuit, 63 reference value storage circuit, 64 latch circuit, 65 timing signal generation circuit, 66 digital-analog (D / A) conversion circuit.

Claims (2)

(57) [Claims] 1. A wireless communication apparatus used in a system for performing wireless communication by performing time-division multiple access between a plurality of wireless stations via a digital wireless line having a plurality of time slots. A transmission power variable circuit that variably outputs the transmission power, a level detection unit that detects a transmission power level of a transmission wave output from the transmission power variable circuit, and a reference value generation for generating a reference value that defines the transmission power level Means, comparing a level detection value by the level detection means with a reference value generated from the reference value generation means, and a level control signal for variably controlling the gain of the transmission power variable means based on the comparison result. Control signal generating means for generating, during a transmission period of a time slot assigned to itself among a plurality of time slots of the digital radio line, The level control signal generated by the control signal generating means is supplied as it is to the transmission power variable circuit, and the level control signal generated by the control signal generating means during the immediately preceding own time slot transmission period during other time slots. Control means for continuously supplying a signal to the variable transmission power circuit. 2. The control means includes a latch circuit for latching a digitized level control signal, and supplies a latch signal to the latch circuit at a predetermined period during a transmission period of a time slot assigned to the control means. Latch supply of the level control signal, and stop supplying the latch signal to the latch circuit during the other time slots, and continue the level control signal latched during the transmission period of the immediately preceding own time slot. The wireless communication device according to claim 1, wherein the wireless communication device outputs the data.