JP2873996B2 - 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 device,
Especially used for mobile communications such as car phones and mobile phones,
The present invention relates to a wireless communication device that performs transmission and reception in digital wireless communication alternately using carrier waves of the same frequency.

[0002]

2. Description of the Related Art In mobile communications, a radio wave propagation path is out of line of sight, so that a radio wave passing through a large number of propagation paths is irregularly strengthened or weakened and input to a receiver, a so-called fading phenomenon. When the signal level falls below the reference sensitivity due to the weakening of radio waves, the quality of the received signal deteriorates significantly.

As a method for preventing this, there is a method of increasing the transmission power to reduce the probability that the signal level falls below the reference value. However, in this method, transmission may be performed with unnecessarily large power. In many cases, wasteful power consumption occurs, and other communication devices are obstructed. To solve the above-mentioned drawbacks, there is known automatic transmission power control that automatically performs transmission with a minimum necessary power in accordance with the fading condition of the transmission path.

In a digital radio communication system in which transmission and reception are alternately performed using carrier waves of the same frequency,
It is known that the effects of fading on a received signal alternately received between two transceivers have a high correlation with each other. Also, assuming that the signal is transmitted from the base station with a constant power, the received signal level at the mobile station indicates a level change due to fading in the transmission path.

[0005] Therefore, in the automatic transmission power control in the digital radio communication system as described above, the so-called forward-looking method of measuring the reception signal level and controlling the transmission signal level on the transmission side so as to compensate for the decrease in the level of the reception signal. The automatic transmission power control based on the forward control cancels the effect of fading with a minimum necessary power, thereby suppressing power consumption while maintaining good signal quality. . In addition,
This automatic transmission power control functions particularly effectively in the forward control performed when transmitting from the mobile station to the base station (uplink) as described above.

On the other hand, since the characteristics of the transmission line constantly change over time, in the automatic transmission power control described above, prediction control for performing control while predicting the future based on past data is effective. In the automatic transmission power control including the above, the received signal is in-phase component and quadrature component rather than controlling the transmission power by predicting the level fluctuation on the transmission side using the signal level (amplitude value of the modulated wave) of the received signal itself. It has been reported that it is better to control the transmission power by predicting the level fluctuation on the transmission side using each component to obtain a higher quality signal.

[0007]

However, although the automatic transmission power control as described above has been reported as one concept, it is not clear how to actually implement it as a circuit. At present, the realization is expected as an effective means for canceling the effect of fading with the minimum necessary power. The present invention has been proposed in view of the above, and an object of the present invention is to provide a wireless communication device that can suppress power consumption while maintaining good signal quality and that does not interfere with other communication devices. .

[0008]

In order to achieve the above object, a wireless communication apparatus according to the present invention provides a wireless communication apparatus which performs transmission and reception in digital wireless communication alternately using a carrier wave of the same frequency. Gain control means for suppressing the level fluctuation of the signal with a control voltage corresponding to the level fluctuation and controlling the gain of the received signal to be constant; and an output signal from the gain control means, a reproduced carrier signal extracted from the output signal. Demodulation means for performing synchronous demodulation using the same, quadrature detection means for performing quadrature detection on the reproduced carrier signal using a detection signal having the same frequency, and outputting in-phase and quadrature baseband signals, and in-phase and quadrature base signals from the quadrature detection means. Transmission power control means for performing transmission power optimum control of the transmission signal based on the band signal and the control voltage of the gain control means. It was.

[0009]

As described above, according to the present invention, the transmission power is controlled based on the in-phase and quadrature baseband signals obtained by quadrature detection of the reproduced carrier and the control voltage for controlling the gain of the modulation signal to be constant. Control. The control voltage and the like include information on the effect of fading in the transmission path, and by controlling the transmission power based on the control voltage and the like, the transmission signal will appear when it reaches the other party. The effect of fading can be canceled.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 2 is an explanatory diagram of a digital wireless communication system to which the wireless communication device of the present invention is applied. FIG.
In (a), a mobile station 82 incorporates a wireless communication device 100 of the present invention, which will be described in detail later. The mobile station 82 transmits a digital wireless signal transmitted from a partner via a base station 81 to its own station. Received by the wireless communication device 100,
The wireless communication device 100 transmits and transmits a digital wireless signal to the other party. Transmission and reception of digital signals in this digital wireless communication are performed at the same frequency f0.
2B, the transmission of the transmission signal TX and the transmission of the reception signal RX are alternately performed at a period Tf by time-division directional control.

FIG. 1 is a block diagram showing a configuration of a characteristic portion of a wireless communication apparatus according to the present invention. As described above, the wireless communication apparatus according to the present invention is of a digital wireless communication system in which transmission and reception are performed alternately using a carrier having the same frequency f0, and the level fluctuation of the received signal is controlled according to the level fluctuation. Gain control means 1 for controlling with a voltage A (t) and controlling the gain of a received signal to be constant; gain control means 1
And a demodulation means 2 for synchronously demodulating the output signal from the output carrier signal using the reproduced carrier signal Sc extracted from the output signal, and performing quadrature detection on the reproduced carrier signal Sc using a detection signal having the same frequency to obtain an in-phase baseband signal Cx ( t) and quadrature detection means 4 for outputting quadrature baseband signal Cy (t)
And transmission power for performing transmission power optimum control of the transmission signal based on the in-phase and quadrature baseband signals Cx (t) and Cy (t) from the quadrature detection means 4 and the control voltage A (t) in the gain control means. And control means 5.

Next, the configuration of the wireless communication device will be described more specifically with reference to FIGS. 3, 4 and 5. FIG. 3 is a diagram illustrating a more specific configuration example of the wireless communication device.
In the figure, the modulated wave signal from the other party received by the antenna 70 passes through the antenna duplexer 60 of the wireless communication device 100, is amplified by the receiving amplifier 11, and then enters the automatic gain control circuit 10. The automatic gain control circuit 10 detects the gain (amplitude) of the received signal, generates a control voltage A (t) corresponding to the gain fluctuation, and controls the gain of the received signal to be constant with the control voltage A (t). Then, the signal is output to the demodulation and determination circuit 20 as the controlled reception signal S1.

The demodulation and determination circuit 20 is a circuit for synchronously demodulating the controlled reception signal S1 using the reproduced carrier signal. As shown in FIG. 4, a phase detector 21, a low-pass filter 22, and a determination circuit 23 comprising a series circuit 20a
And a series circuit 20b including a phase detector 24, a low-pass filter 25, and a determination circuit 26 are provided in parallel.

The demodulation and judgment circuit 20 is provided with a carrier recovery circuit 30. As will be described in detail later, each output signal from the serial circuits 20a and 20b and a controlled signal from the automatic gain control circuit 10 are controlled. In response to the received signal S1, a carrier is extracted and output as a reproduced carrier signal Sc.

The above-described series circuit 20a includes a phase detector 21
, The phase of the controlled reception signal S1 and the phase shifter 27 is 9
Upon receiving the reproduced carrier signal Sc shifted in phase by 0 °, it performs synchronous detection, and outputs the in-phase component IR of the received digital signal determined and demodulated by the determination circuit 23 every symbol period. Further, the serial circuit 20b receives the controlled reception signal S1 and the reproduced carrier signal Sc in the phase detector 24, performs synchronous detection, and determines the orthogonal component QR of the received digital signal determined and demodulated by the determination circuit 26 for each symbol period. Output to

FIG. 5 is a block diagram showing the configuration of the carrier recovery circuit 30 described above. The controlled reception signal S1 input to the carrier recovery circuit 30 is input to the quadrature modulation circuit 30a after being delayed by a time delay in the demodulation and determination circuit 20 by the delay circuit 31. Quadrature modulation circuit 3
0a, as shown in the figure, comprises modulators 32 and 34, an inverting circuit 33, a phase shifter 35, etc., receives the in-phase component IR and the quadrature component QR of the received digital signal, and reverses the controlled reception signal S1. The carrier signal is reproduced by modulating and recovering the phase change due to the quadrature modulation received at the time of transmission by the other party. The reproduced signal is input to the resonance circuit 36 to remove a noise component, and then becomes a reproduced carrier signal Sc.

The reproduced carrier signal Sc from the carrier recovery circuit 30 is further output to the quadrature detection circuit 40. The quadrature detection circuit 40 performs quadrature detection on the reproduced carrier signal Sc using a detection signal having the same frequency f0 as the carrier, and outputs an in-phase baseband signal Cx (t) and a quadrature baseband signal Cy (t). Circuit. That is, as shown in FIG. 4, the phase detector 41 has the same frequency f0 as the carrier from the local oscillator 46 and has a phase shifted by 90 ° in the phase shifter 41 and a reproduced carrier signal Sc. And synchronous detection. The synchronously detected signal is output to the transmission power control circuit 50 as the in-phase baseband signal Cx (t) via the low-pass filter 42. Similarly, the phase detector 43 receives the detection signal from the local oscillator 46 and the reproduced carrier signal Sc and performs synchronous detection. The synchronously detected signal passes through the low-pass filter 44 and is subjected to the quadrature baseband signal Cy. (T) is output to the transmission power control circuit 50.

Returning to FIG. 3, the transmission power control circuit 50 will be described. The transmission power control circuit 50 includes the quadrature detection circuit 4
0, the in-phase and quadrature baseband signals Cx (t),
Cy (t) and the control voltage A in the automatic gain control circuit 10
This is a circuit provided for receiving (t) and optimally controlling the transmission power of the transmission signal based on those signals, and is configured mainly with, for example, a DSP (digital signal processor).

Incidentally, the reproduced carrier signal Sc follows the phase fluctuation in the transmission path. Therefore, the in-phase and quadrature baseband signals Cx (t) and Cy (t), which are the output signals of the quadrature detection circuit 40, represent the relative in-phase and quadrature components of the transmission line fluctuation. However, since the amplitude is kept constant by the automatic gain control circuit 10, the level information of the transmission line is lost. On the other hand, the level information of the transmission line appears in the control voltage A (t) of the automatic gain control circuit 10. Therefore, the transmission power control circuit 50 uses the control voltage A (t) indicating the level information of the transmission line to predict a signal gain variation that the transmission digital signal will receive in the following manner.

First, amplitude information on fluctuations in the transmission path is included.
Relative in- phase component p (t) and quadrature component q (t)
Is given by the following equations (1) and (2), respectively. p (t) ≡A (t) · C x (t) ····· (1) q (t) ≡A (t) · C y (t) ····· (2)

Therefore, the transmission power control circuit 50 uses them to predict future fluctuations in the transmission path. For example, the in-phase component p (t) and the quadrature component q at the future time t3 are calculated from the values of the reception times t1, t2 (t2 ≧ t1).
The value of (t) is predicted using the following equations (3) and (4). p (t3) = p (t2) + {p (t2) -p (t1)} / (t2-t1) (t3-t2) (3) q (t3) = q (t2) + {Q (t2) -q (t1)} / (t2-t1) (t3-t2) (4)

The amplitude B (t at future time t3
3) is predicted using the following equation (5). ^{B (t3) = {p 2} (t3) + q 2 (t3)} 1/2 ··· (5)

After performing the above-described prediction calculation, the transmission power control circuit 50 controls the gain of the variable gain amplifier 52 so as to perform control equivalent to multiplication by the reciprocal of the amplitude B (t3). As shown in FIG. 3, the transmission digital signals IT and QT undergo quadrature modulation in a modulation circuit 51, and then undergo normal gain control and gain control by the transmission power control circuit 50 in a variable gain amplifier 52, as shown in FIG. Thereafter, the signal is transmitted from the antenna 70 via the antenna duplexer 60.

As described above, in this embodiment, the reproduced carrier S including the information on the effect of fading on the transmission path is used.
Since the transmission power is controlled based on the in-phase and quadrature baseband signals Cx (t) and Cy (t) and the control voltage A (t) obtained by quadrature detection of c, when the transmission signal reaches the other party Can be canceled with the minimum necessary power, and power consumption can be suppressed while maintaining good signal quality. In addition, since transmission is performed with the minimum necessary power, there is no interference with other communication devices.

Further, the transmission power control circuit in the forward control, which has not been provided as a specific circuit configuration based on only the conventional concept, is replaced with a control voltage A in the automatic gain control circuit 10.
Since it is provided specifically using (t) and the like, a wireless communication device with good signal quality can be realized, and a digital wireless communication system with good communication quality can be constructed using the wireless communication device.

[0026]

As described above, according to the radio communication apparatus of the present invention, the in-phase and quadrature baseband signals and the control voltage obtained by performing quadrature detection on the reproduced carrier, including the information on the effect of fading on the transmission line. , The transmission power is controlled, so that the effect of fading, which would appear when the transmission signal reaches the other party, can be canceled with the minimum necessary power, and the signal quality is kept good. Thus, power consumption can be suppressed. In addition, since transmission is performed with the minimum necessary power, there is no interference with other communication devices. Furthermore, a transmission power control circuit in forward control, which was not provided as a specific circuit configuration based on the conventional concept alone, is specifically provided using a control voltage or the like, so that a wireless communication device with good signal quality is provided. This has enabled the construction of a digital wireless communication system with good communication quality using the wireless communication device.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a characteristic portion of a wireless communication device according to the present invention.

FIG. 2 is an explanatory diagram of a digital wireless communication system to which the wireless communication device of the present invention is applied.

FIG. 3 is a diagram illustrating a more specific configuration example of a wireless communication device.

FIG. 4 is a block diagram illustrating a configuration of a demodulation and determination circuit and a quadrature detection circuit.

FIG. 5 is a block diagram illustrating a configuration of a carrier recovery circuit.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 gain control means 2 demodulation means 4 quadrature detection means 5 transmission power control means 10 automatic gain control circuit 20 demodulation and judgment circuit 30 carrier recovery circuit 40 quadrature detection circuit 50 transmission power control circuit 100 wireless communication device

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-64-16149 (JP, A) JP-A-5-344021 (JP, A) IEICE Technical Report, Vol. 93, no. 255, RCS 93-55, p. 29-34 (1993-9-30) (58) Fields investigated (Int. Cl. ⁶ , DB name) H04L 27/00-27/38 H03G 3/20 H04B 1/54 H04B 7/26 102

Claims (1)

(57) [Claims] 1. A radio communication apparatus for performing transmission and reception in digital radio communication alternately using a carrier wave of the same frequency, wherein the level fluctuation of a received signal is suppressed by a control voltage corresponding to the level fluctuation, and the gain of the received signal is reduced. Gain control means for controlling the output signal from the gain control means, and demodulation means for synchronously demodulating an output signal from the gain control means using a reproduced carrier signal extracted from the output signal; and a detection signal having the same frequency as the reproduced carrier signal. And quadrature detection means for outputting quadrature detection and in-phase and quadrature baseband signals using the quadrature detection means, and transmission power optimization of the transmission signal based on the in-phase and quadrature baseband signals from the quadrature detection means and the control voltage in the gain control means. And a transmission power control means for performing control.