JPH11298343A - Portable communication equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the linearity of a reception circuit and to improve characteristics to interference waves without increasing current consumption more than needed in a portable communication equipment such as a digital portable telephone terminal using a direct spread spectrum communication system. SOLUTION: In the reception power measurement part 31 of a digital signal processing part 23, reception electric field strength is measured from base band signals demodulated by an orthogonal detection circuit 20 and digitized by an A/D converter 22. In a code error rate measurement part 32, a code error rate in error correction performed in the digital signal processing part 23 for the base band signals from the A/D converter 22 is measured. In a judgement control part 33, when the reception electric field strength is more than prescribed electric field strength and the code error rate is higher than a prescribed error rate, it is judged that reception signals are interfered by the interference waves, the current of an RF amplifier circuit 14 is increased compared to the time of judging that the reception signals are not interfered by the interference waves and the linearity of the RF amplifier circuit 14 is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a portable communication device such as a digital portable telephone terminal using a direct spread spectrum communication system.

[0002]

2. Description of the Related Art A CDMA (Coding System) using direct spread spectrum in which a communication signal is spread by a spread code.
de Division Multiple Access
An ss) type digital mobile phone terminal has become a reality.

[0003] The CDMA system is a system in which a plurality of spread spectrum communication signals, which are spread with different spreading codes, are transmitted in the same time band or frequency band, and individual signals are identified by using differences in spreading codes. By changing the code, it is possible to transmit multiple spread spectrum communication signals in the same time zone and the same frequency band,
Since there is no shortage of wireless communication lines used in the mobile phone terminal and the security is excellent, a good communication environment can be provided to the user of the mobile phone terminal.

[0004]

By the way, in mobile telephone communication, since an FM communication signal and a spread spectrum communication signal have been allocated to the same communication frequency band in recent years, the FM communication signal is located near the spread spectrum communication signal. May be present as an interfering wave. In a digital mobile phone terminal using the direct spread spectrum communication method, a received signal is converted into an intermediate frequency signal, and the converted intermediate frequency signal is used as a pass band in a spread band which is a frequency band of the spread spectrum communication signal. By supplying the filter, unnecessary frequency components are removed from the received signal,
Although only a desired spread spectrum communication signal is extracted, the bandpass filter removes an interference wave such as an FM communication signal allocated to the same communication frequency band as the spread spectrum communication signal as described above. It is not possible.

Therefore, conventionally, in order to avoid intermodulation and cross-modulation in the presence of such an interfering wave, when the reception level is equal to or higher than a certain level, the current of the reception circuit is increased to increase the linearity of the reception circuit. The property is good.

However, the fact that the reception level is high does not necessarily mean that intermodulation or cross modulation is caused by an interfering wave. And especially on mobile phones,
The current consumption of the receiving circuit during standby greatly affects the life of the battery. Therefore, if the current of the receiving circuit is constantly increased when the reception level is equal to or higher than a certain level, the life of the battery is shortened.

Accordingly, the present invention provides a portable communication device such as a digital portable telephone terminal using a direct spread spectrum communication system, which improves the linearity of a receiving circuit without unnecessarily increasing current consumption and prevents interference. This is to improve the characteristics with respect to waves.

[0008]

According to the present invention, a portable communication device converts a received signal into an intermediate frequency signal, detects the intermediate frequency signal, and detects a received electric field intensity of the received signal. An electric field strength detection unit, a code error rate detection unit that detects a code error rate in error correction of the received signal, a reception electric field strength detected by the reception electric field strength detection unit is equal to or higher than a predetermined electric field intensity, and the code When the code error rate detected by the error rate detection unit is equal to or more than a predetermined error rate, it is determined that the received signal is disturbed by an interfering wave, and that the received signal is not disturbed by an interfering wave. A determination control unit that controls the reception unit so as to improve the linearity of a circuit that configures the reception unit as compared with the determination.

In this case, the circuit is an RF amplifier circuit, and when the determination control unit determines that the received signal is disturbed by an interference wave, the reception signal is not disturbed by the interference wave. The current of the RF amplifier circuit can be increased as compared with the case where it is determined.

As described above, the fact that the reception level is high does not necessarily mean that the intermodulation or the cross modulation is caused by the interference wave. Even if the received electric field strength is equal to or higher than the predetermined electric field strength, the code error rate in error correction of the received signal does not deteriorate so much as long as there is no interfering wave affecting the intended received signal. If there is an interfering wave that affects the signal, the bit error rate in error correction of the received signal deteriorates.

In the portable communication device of the present invention, focusing on this point, as described above, when the reception electric field strength is equal to or higher than the predetermined electric field strength and the code error rate is equal to or higher than the predetermined error rate, the reception signal It is determined that the received signal is not disturbed by the interfering wave when the bit error rate is less than the predetermined error rate, even if the received electric field strength is equal to or higher than the predetermined electric field strength. The determination makes it possible to reliably detect whether or not the received signal is being disturbed by the interference wave, and when it is determined that the received signal is being disturbed by the interference wave, the RF amplifier constituting the reception unit is determined. Since the linearity of the circuit is improved by increasing the current of a circuit such as a circuit, it is possible to improve the characteristics with respect to an interfering wave and avoid intermodulation and cross modulation.

Further, in the portable communication device of the present invention, the current of the circuit such as the RF amplifier circuit constituting the receiving section is increased only when it is determined that the received signal is disturbed by the disturbing wave. When it is determined that the received signal is not disturbed by an interfering wave not only at the time of transmission but also at the time of reception as well as at the time of transmission, the above-described processing is not performed. The current consumption of the portable communication device, such as the current consumption of the portable communication device, is not increased more than necessary.

[0013]

FIG. 1 shows an embodiment of a portable communication apparatus according to the present invention, in which the present invention is applied to a digital portable telephone terminal using a direct spread spectrum communication system. The mobile phone terminal of this embodiment is generally
It includes the antenna 12, the antenna duplexer 13, the receiving unit 25, the digital signal processing unit 23, and the transmitting unit 43, and also includes a receiver (speaker), a transmitter (microphone), an operation unit, a display unit, and the like, which are omitted in the drawing.

A direct spread spectrum communication signal 11 from a base station is received by an antenna 12 and supplied to a receiving unit 25 via an antenna duplexer 13. The transmission RF signal from the transmission unit 43 is transmitted from the antenna 12 via the antenna duplexer 13.

The signal received via the antenna duplexer 13 is
After being amplified by the RF amplifier circuit 14, the amplified signal is supplied to the RF filter 15, where the image frequency component is removed from the received signal. The received signal through the RF filter 15 is supplied to an RF mixer 16 as an intermediate frequency conversion circuit,
By the RF local oscillation signal from the RF local oscillator 17,
It is converted to an intermediate frequency signal.

The intermediate frequency signal from the RF mixer 16 is supplied to a band pass filter 18 as an intermediate frequency filter, and an intermediate frequency signal having a predetermined center frequency and a predetermined band is extracted from the band pass filter 18. The intermediate frequency signal from the band pass filter 18 is supplied to an AGC (auto gain control) amplifier circuit 19,
The level is controlled as described below.

The intermediate frequency signal from the AGC amplification circuit 19 is supplied to a quadrature detection circuit 20, and the IF local oscillator 2
1 is demodulated into I and Q baseband signals by the IF local oscillation signal from
After being digitized by the / D converter 22, it is supplied to the digital signal processing unit 23.

The digital signal processing unit 23 includes a CPU, an RO,
The digitalized baseband signal from the A / D converter 22 is configured by a microcomputer including an M and a RAM, and is subjected to digital signal processing such as error correction in a digital signal processing unit 23. The signal is output from the digital signal processing unit 23 as a reception code 24.

The received code 24 is D / A-converted, the converted analog audio signal is supplied to the receiver, and the voice transmitted from the other party is emitted from the receiver.

The audio signal picked up by the transmitter of the portable telephone terminal is A / D-converted, and the converted digital audio signal 41 is supplied to the digital signal processing unit 23, and the digital signal processing unit 23 23, a transmission baseband signal is formed, and the baseband signal is
3 is supplied.

The transmitting section 43 is not directly related to the gist of the present invention, and can have a known configuration. Therefore, the details thereof will be omitted. A transmission RF signal is formed through processing such as frequency conversion and RF amplification, and the transmission RF signal is transmitted from the antenna 12 via the antenna duplexer 13 as described above.

In this embodiment, the digital signal processing unit 2
3, a reception power measurement unit 31, a bit error rate measurement unit 32, and a determination control unit 33 are provided.

In the reception power measuring section 31, the quadrature detection circuit 2
The received field strength is measured from the baseband signal demodulated by 0 and digitized by the A / D converter 22. Then, the reception power measurement unit 31 sends the measurement output of the reception electric field strength to the AGC through the control line 34.
The gain is supplied to the amplifier circuit 19 as a gain control signal, and the gain of the AGC amplifier circuit 19 is controlled so that the baseband signal input to the A / D converter 22 has a constant level.

The code error rate measuring section 32 measures the code error rate in the error correction performed by the digital signal processing section 23 for the digitized baseband signal from the A / D converter 22 as described above.

FIG. 2 shows an example of the bit error rate measuring section 32, and shows a functional block diagram of a bit error rate measuring algorithm in the digital signal processing section 23. The baseband signal from the A / D converter 22 output on the line 61 is error-corrected by the error correction circuit 62, and the error-corrected baseband signal is output on the line 63.

The comparison circuit 64 compares the baseband signal before error correction with the baseband signal after error correction. If the difference between the two is equal to or greater than a predetermined value, the code error rate is equal to or greater than the predetermined error rate. It is determined that there is, and if the difference between them is less than a certain value, it is determined that the code error rate is less than the predetermined error rate, and the result of the determination is output to a line 65.

In the judgment control unit 33, the reception power measurement unit 31
Output of the received electric field strength from the
2 to determine whether or not the received signal is being disturbed by an interference wave.

Specifically, as described above, even if the received electric field strength is equal to or higher than the predetermined electric field strength, the bit error rate is not significantly deteriorated unless there is an interfering wave affecting the intended received signal. However, if there is an interference wave that affects the intended received signal, the bit error rate is degraded, so that the received electric field strength is equal to or higher than the predetermined electric field strength and the code error rate is equal to or higher than the predetermined error rate. , It is determined that the received signal is disturbed by the interference wave, and otherwise, it is determined that the received signal is not disturbed by the interference wave.

The determination control unit 33 supplies the determination output to the RF amplifier circuit 14 through the control line 35, and when it determines that the received signal is disturbed by the interference wave, the received signal disturbs the interference by the interference wave. The current of the RF amplifier circuit 14 is increased compared to when it is determined that the signal has not been received, and the linearity of the RF amplifier circuit 14 is improved.

FIG. 3 shows an example of the RF amplification circuit 14 in this case. The judgment control unit 33 supplied through the control line 35 to the collector side of the RF amplification transistor 51.
The switch 52 is provided to be switched according to the judgment output of the switch 5. When the judgment control section 33 judges that the received signal is not disturbed by the interfering wave, the switch 5
2 is switched to the resistor 53 side as shown in the figure, a current flows from the power supply line 55 to the collector of the transistor 51 through the switch 52 and the resistor 53, and conversely, the judgment control unit 3
3, when it is determined that the received signal is obstructed by the interfering wave, the switch 52 is switched to the line 54 side, contrary to the state shown in the figure, and the transistor 51 is switched from the power supply line 55 through the switch 52 and the line 54.
Is configured so that current flows through the collector.

Therefore, when the determination control unit 33 determines that the received signal is being disturbed by the interference wave, the collector current of the transistor 51 increases, the linearity of the RF amplifier circuit 14 is improved, and the interference wave is improved. Are improved, and intermodulation and cross modulation are avoided.

When the determination control unit 33 determines that the received signal is not disturbed by an interference wave, not only during transmission but also during reception, the collector current of the transistor 51 is suppressed and the RF amplifier circuit 14 Current consumption is reduced.

[0033]

As described above, according to the present invention, in a portable communication device such as a digital portable telephone terminal using the direct spread spectrum communication method, the linearity of the receiving circuit can be increased without unnecessarily increasing the current consumption. The characteristics can be improved, and the characteristics with respect to the interference wave can be improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing one embodiment of a portable communication device of the present invention.

FIG. 2 is a diagram illustrating an example of a bit error rate measurement unit.

FIG. 3 is a diagram illustrating an example of an RF amplifier circuit.

[Explanation of symbols]

11: Direct spread spectrum communication signal, 12: Antenna, 13: Antenna duplexer, 14: RF amplifier circuit, 15
.. RF filter, 16 RF mixer, 17 RF local oscillator, 18 bandpass filter, 19 AGC amplifier circuit, 20 quadrature detection circuit, 21 IF local oscillator, 22
... A / D converter, 23 ... Digital signal processing unit, 24
... Reception code, 25 ... Receiving unit, 31 ... Received power measuring unit, 3
2 ... Code error rate measuring unit, 33 ... Decision control unit, 34 ... Control line, 35 ... Control line, 41 ... Digital audio signal,
43: transmission unit, 52: switch, 62: error correction circuit,
63 ... Comparison circuit

Claims (3)

[Claims] A receiving unit that converts a received signal into an intermediate frequency signal and detects the intermediate frequency signal; a receiving electric field intensity detecting unit that detects a received electric field intensity of the received signal; A code error rate detection unit that detects a code error rate, a reception electric field intensity detected by the reception electric field intensity detection unit is equal to or higher than a predetermined electric field intensity, and a code error rate detected by the code error rate detection unit is a predetermined value. When the error rate is equal to or more than the error rate, it is determined that the received signal is disturbed by an interference wave, and the reception unit is configured as compared with when it is determined that the received signal is not disturbed by an interference wave. A mobile communication device, comprising: a determination control unit that controls the reception unit so as to improve linearity of a circuit. 2. The mobile communication device according to claim 1, wherein the circuit is an RF amplifier circuit, and the determination control unit is
When determining that the received signal is disturbed by an interfering wave, increasing the current of the RF amplifier circuit compared to when determining that the received signal is not disturbed by the interfering wave. Mobile communication device. 3. The mobile communication device according to claim 1, wherein the code error rate detection section compares the received signal before error correction with the received signal after error correction and determines that the difference between the two is equal to or greater than a predetermined value. A mobile communication device that determines that a code error rate is equal to or higher than a predetermined error rate.