JPH06164663A - Radio communication equipment - Google Patents

Abstract

PURPOSE:To detect received electric field strength with high accuracy in a short time. CONSTITUTION:A sampling signal generation part is provided at a synchronizing clock reproducing circuit 65 of a digital demodulation circuit 22, at this part, a sampling signal SP is generated at timing synchronized with each symbol position of a received digital signal, a received electric field strength detection circuit 32 samples the level of the received signal synchronously with this sampling signal SP, the average value of this sampled received signal level is calculated by an averaging means 30a of a control circuit 30, and this average value is defined as the detected value of the received electric field strength.

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 used as, for example, an automobile telephone device, a mobile telephone, or a cordless telephone, and in particular, measures the received electric field strength of a radio carrier signal digitally modulated by the PSK modulation method. The present invention relates to a wireless communication device having a function.

[0002]

2. Description of the Related Art In recent years, in mobile radio communication systems such as automobile / cellular phone systems and cordless telephone systems, systems adopting a digital system have been proposed in order to increase the number of subscribers and effectively use radio frequencies. In the digital method, a communication device on the transmitting side encodes a voice signal and data, a wireless carrier wave is digitally modulated by the encoded signal and transmitted, and the wireless communication device on the receiving side transmits from the transmitting side. This is a method of reproducing a voice signal and data by decoding a demodulated signal after receiving a modulated wave and digitally demodulating the modulated signal. As a modulation method, for example, π / 4 shifted DQPSK (π / 4 Shifted, differ) is used.
entially encoded quadrature phase shift keying) method is used.

In this π / 4 shift DQPSK system, in a modulation circuit, a transmission data stream bm is first converted into two data streams X _k , by a serial / parallel converter.
Y _k , and then these data streams X _k , Y
_k is differentially encoded by a differential encoding mapping circuit as shown in the following equation. I _k = I _k-1 cos [Δφ (X _k , Y _k )] − Q _k-1 sin [Δφ (X _k , Y _k )] Q _k = I _k-1 sin [Δφ (X _k , Y _k )] + Q _k-1 cos [Δφ (X _k , Y _k )] _where I _k-1 and Q _k-1 are the amplitudes of the encoded data at the pulse time one pulse before, and Δφ is the amount of phase change. Are shown respectively. FIG. 7 shows the relationship between the input data streams X _k and Y _k and the phase change amount Δφ. FIG. 8 is a phase space diagram showing the phase mapping positions of the coded data I _k and Q _k output from the differential phase coding mapping circuit.

That is, in the modulation circuit of the π / 4 shift DQPSK system, the signal level (“1”, “0”) of the input data streams X _k , Y _k , and
On the basis of the phase positions of the coded data I _k-1 and Q _k-1 obtained at the pulse time of one pulse before, the coded data I
_k, the phase position of the Q _k is determined. At this phase position,
For each pulse time, one of the phase positions shown by ◯ in the figure and one of the phase positions shown by ◇ are alternately selected. The amplitude values of the encoded data I _k and Q _k have five values, that is, 0, ± 1, ± 2 ^1/2. Any one of (Route 2) is selected. When such a π / 4 shift DQPSK system is used, the spread of the signal band can be suppressed.

By the way, in an automobile / mobile phone system or a cordless telephone device, the transmission power of a mobile unit is controlled according to the distance from the base station, or the base station of the connection destination is changed as the mobile unit in communication moves. It is necessary to perform so-called hand-off control for switching. Therefore, each mobile device detects the received electric field strength of the modulated wireless carrier wave that has arrived from the base station, for example, according to an instruction from the base station during communication.

[0006]

However, in the conventional radio communication device of this type, the reception electric field strength is detected by sampling the reception signal level of the reception intermediate frequency signal at an arbitrary sampling timing, for example. . Therefore, the following problems have occurred.

That is, the phase position of the coded data I _k , Q _k output from the differential coding mapping circuit changes at each pulse time as described above, and is received by the mobile station in response to this. The amplitude of the received intermediate frequency signal also changes. For this reason, in the conventional wireless communication device in which the level of the reception intermediate frequency signal is simply sampled at any timing to obtain the reception electric field strength, the reception level detected at each sampling point tends to vary. As a result, it was difficult to detect the accurate received electric field strength. Further, in order to reduce the influence of the variation in the reception level, it has been considered to obtain an average value of the reception levels detected at a plurality of sampling points. However, in order to sufficiently reduce the influence of the variation in the reception level, the reception level must be detected at many sampling points. For this reason, a long detection time is required to obtain a highly accurate received electric field strength, and as a result, responsiveness of various controls performed based on the detected value of the received electric field strength is deteriorated.

The present invention has been made in view of the above circumstances, and an object of the present invention is to make it possible to detect the received electric field strength in a short time and with high accuracy, thereby enabling various controls based on the received electric field strength. It is to provide a wireless communication device capable of improving responsiveness.

[0009]

To achieve the above object, the present invention comprises a receiving circuit system for receiving a radio signal PSK-modulated by a digital signal in a radio circuit and then demodulating the digital signal in a demodulation circuit. In the wireless communication device, the sampling signal generation means generates a sampling signal in synchronization with the demodulated digital signal or a signal synchronized with the digital signal, and the reception field strength detection means generates the sampling signal by the generated sampling signal. The received electric field strength of the received radio signal is detected at the represented sampling point.

Further, according to the present invention, when a roll-off filter is inserted in the transmission system, the roll-off filter is provided in the radio circuit, and the received electric field strength of the received radio signal after passing through the roll-off filter is set. It is also characterized in that detection is performed at a sampling point represented by the sampling signal.

[0011]

As a result, according to the present invention, the received electric field strength is sampled in synchronization with the demodulated digital signal or the signal synchronized therewith. For this reason, for example, it is possible to always sample the received electric field strength at the same phase convergence position, thereby reducing the variation in the received electric field strength obtained at each sampling point. Therefore, the received electric field strength can be accurately detected, and even when the average value of the received electric field strength is obtained, it is only necessary to detect the received electric field strength at a small number of sampling points. It becomes possible to measure the intensity. As a result, for example, in an automobile / mobile phone system, it becomes possible to perform control of transmission power of a mobile device, handoff control, and the like with good responsiveness.

Further, according to the present invention, by providing the roll-off filter in the radio circuit and detecting the reception electric field strength of the reception radio signal after passing through the roll-off filter, intersymbol interference is eliminated. In this state, that is, the received electric field strength can be detected at the timing corresponding to the phase convergence position where the degree of convergence is high. For this reason, it is possible to further reduce variations in the received electric field strength, which makes it possible to further improve the detection accuracy of the received electric field strength.

[0013]

EXAMPLES The present invention will be described below based on examples.
FIG. 2 is a circuit block diagram showing the configuration of a digital portable radio telephone equipped with a received electric field strength detecting means according to an embodiment of the present invention. This digital mobile phone is
It is roughly divided into a transmission system, a reception system, and a control system. Incidentally, 40 is a power supply circuit using a battery as a power supply.

First, the transmission system includes a microphone 11, a voice encoder (SP-COD) 12, and an error correction encoder (CH).
-COD) 13 and digital modulation circuit (MOD) 14
A mixer 15, a power amplifier (PA) 16, an antenna duplexer 17 having a high frequency switch, and an antenna 18.
Composed of and. The voice encoder 12 encodes the transmission voice signal output from the microphone 11. In the error correction encoder 13, the speech encoder 12
The error correction coding is performed on the coded transmission voice signal output from the control circuit 30 and the control signal output from the control circuit 30.
The error correction coded transmission data is input to the digital modulation circuit 14. In the digital modulation circuit 14,
Using the π / 4 shift DQPSK method, a process for modulating the transmission intermediate frequency signal with the transmission data subjected to the error correction coding is performed. In the mixer 15, the modulated intermediate frequency signal output from the digital modulation circuit 14 is mixed with the local oscillation signal output from the frequency synthesizer 31 and frequency-converted into a high frequency signal. And the wireless transmission signal output from this mixer is
After being amplified to a predetermined transmission power by the power amplifier 16, it is supplied to the antenna 18 via the antenna duplexer 17 and burst-transmitted from the antenna 18 to a base station (not shown).

On the other hand, the receiving system is the receiving circuit (RX) 2
1, a digital demodulation circuit (DEMOD) 22, an error correction decoder (CH-DEC) 23, and a speech decoder (SP
-DEC) 24 and a speaker 25. In the reception circuit 21, the radio carrier signal received by the antenna 18 and the antenna duplexer 17 in the reception time slot of a predetermined radio frequency is frequency-converted into an intermediate frequency signal. The digital demodulation circuit 22 performs bit synchronization and frame synchronization with the reception intermediate frequency signal output from the reception circuit 21, and then digitally demodulates the reception intermediate frequency signal. In the error correction decoder 23, the digital demodulated signal output from the digital demodulator 22 is error correction decoded. The signals output from the error correction decoder 23 include a digital reception signal and a digital control signal. Of these signals, the digital reception signal is input to the voice decoder 24, and the digital control signal is input to the control circuit 30. Speech decoder 2
In 4, the decoding process of the digital received signal is performed. Then, the analog reception signal returned to the original by this decoding processing is output as loudspeaker from the speaker 25.

The control system is a control circuit (CONT) 30.
A frequency synthesizer (SYN) 31, a reception electric field strength detection circuit (RSSI) 32, and a console unit (CU) 33. Of these, the frequency synthesizer 31 generates a transmission and reception local oscillation signal corresponding to the radio channel frequency designated by the control circuit 30. The received electric field strength detection circuit 32 detects the received electric field strength of the radio signal wave coming from the base station. This detection signal is notified to the control circuit 30. The console unit 33 is provided with switches such as dial keys and a transmission switch, and indicators such as a liquid crystal display (LCD) and a light emitting diode.

FIG. 1 is a circuit block diagram showing the configuration of the receiving system in more detail. In the figure, the radio carrier signal received via the antenna 18 is first input to the high frequency amplifier 51 via the antenna duplexer 17.
The high frequency amplifier 51 high frequency amplifies the wireless carrier signal to a predetermined level, and the amplified wireless carrier signal is input to the first mixer 52. This first mixer 52
Then, the radio carrier signal and the reception local oscillation signal output from the frequency synthesizer 31 are mixed, whereby the radio carrier signal is frequency-converted into the first reception intermediate frequency signal. The first received intermediate frequency signal is input to the second mixer 54 after passing through the intermediate frequency filter 53. In the second mixer 54, the first reception intermediate frequency signal and the local oscillation signal output from the fixed local oscillator 55 are mixed, whereby the first reception intermediate frequency signal is further converted into the second reception intermediate frequency signal. To be converted.
This second received intermediate frequency signal is input to an intermediate frequency integrated circuit (IFIC) 57 after passing through an intermediate frequency filter 56. In the intermediate frequency integrated circuit 57, the second received intermediate frequency signal is amplified to a level suitable for A / D conversion described later,
The amplified second intermediate frequency signal is input to the digital demodulation circuit 22.

In the digital demodulation circuit 22, the second intermediate frequency signal is first converted from an analog signal to a digital signal by the A / D converter 61 and then input to the quadrature demodulator 62 where it is quadrature demodulated. This quadrature demodulator 62
The digital demodulated signal output from is transmitted to the root roll-off filter 63 and then input to the delay detector 64 where it is delay-detected and supplied to the error correction decoder 23. The root roll-off filter 63 removes intersymbol buffering interference of signals.

The root roll-off filter 63 is also used.
The digital demodulated signal output from is also input to the synchronization / clock recovery circuit 65. The synchronization / clock reproduction circuit 65 has a synchronization unit for establishing synchronization with the digital demodulation signal, a clock reproduction unit for reproducing the transmission clock, and a sampling signal generation unit. Of these, the sampling signal generator generates a sampling signal SP at a timing corresponding to each symbol position of the digital demodulation signal, and outputs the sampling signal SP to the reception electric field strength detection circuit 32.

FIG. 3 is a diagram showing a circuit configuration of the intermediate frequency integrated circuit 57. In the figure, the second received intermediate frequency signal output from the intermediate frequency filter 56 is input to an intermediate frequency amplifier circuit 57a in which a plurality of amplifiers are connected in series, and is amplified to a predetermined level by the intermediate frequency amplifier circuit 57a. And is output to the digital demodulation circuit 22. The output signals of the amplifiers of the intermediate frequency amplifier circuit 57a are detected by the diode 57b, then combined with each other, and output to the reception electric field strength detection circuit 32.

The reception electric field strength detection circuit 32 is composed of an A / D converter, and the detection output outputted from the intermediate frequency integrated circuit 57 is synchronized with the digital demodulation circuit 22.
It is sampled and digitized in synchronization with the sampling signal SP output from the clock recovery circuit 65. Then, the digitized detection output is output to the control circuit 30 as a reception level detection signal.

The control circuit 30 is provided with averaging means 30a. The averaging means 30a fetches the detection signal each time the reception field strength detection circuit 32 outputs the reception level detection signal and temporarily stores the detection signal.
Then, each time the reception level detection signals for a plurality of predetermined sampling points are stored, the average value of these reception level signals is calculated, and the calculated average value of the reception levels is used as the detection value of the reception electric field strength. , For transmission power control and handoff control.

Next, the received electric field strength detection operation of the digital portable telephone configured as described above will be described. During communication, in the digital demodulation circuit 22, the digital demodulation signal output from the quadrature demodulator 65 passes through the root roll-off filter 63 and is then input to the delay detector 64 for delay detection, and the synchronization / clock generation circuit 65 is input. In the sampling signal generation section of the synchronization / clock generation circuit 65, the sampling signal SP for detecting the received electric field strength is generated in synchronization with the timing corresponding to each symbol position of the digital demodulation signal. Then, this sampling signal SP is supplied to the reception electric field strength detection circuit 32. The generation timing of the sampling signal SP is corrected in consideration of the delay time generated in the circuit from the A / D converter 61 to the root roll-off filter 63.

When the sampling signal SP thus generated is supplied, the detection output of the second reception intermediate frequency signal output from the intermediate frequency integrated circuit 57 in the reception field strength detection circuit 32 is the sampling signal. It is sampled at the sampling timing designated by SP and converted into a digital signal. Then, the digital value of the sampled reception signal level is supplied to the control circuit 30 as a detection signal of the reception signal level.

That is, in the reception electric field strength detection circuit 32, each symbol position of the reception digital signal, that is, the second
The received signal level is detected at the timing corresponding to each phase convergence position of the received intermediate frequency signal.
For example, a phase space diagram (phase constellation) of the second received intermediate frequency signal input to the intermediate frequency integrated circuit 57 is shown in FIG. The received signal level is detected only at the timing corresponding to the phase convergence position P1 on the phase constellation. Therefore, variations in the received signal detection level for each sampling are reduced. Further, in the control circuit, the averaging means 30a
In, the average of the received signal levels detected at the plurality of sampling points is calculated, and the average value of the received signal levels is used for various controls as the detected value of the received electric field strength. Therefore, the detected value of the received electric field strength becomes more accurate.

As described above, in this embodiment, the synchronization / clock recovery circuit 65 of the digital demodulation circuit 22 is provided with the sampling signal generation section, and the sampling signal S is synchronized with the symbol position of the received digital signal.
P is generated, the reception signal strength detection circuit 32 samples the reception signal level in synchronization with the sampling signal SP, and the average value of the sampled reception signal levels is calculated by the averaging means 30a of the control circuit 30. The average value is used as the detected value of the received electric field strength.

Therefore, in this embodiment, for example, FIG.
As shown in (3), only the received signal level at the same phase convergence position P1 of the second received intermediate frequency signal can be sampled, thereby reducing the variation between the sampled received signal levels and reducing the received electric field strength. It can be detected with high accuracy. Further, in order to detect the received electric field strength with high accuracy, it is not necessary to detect the received signal level at many sampling points, and only the received signal levels at a small number of sampling points need to be detected. Therefore, the received electric field strength can be measured with high accuracy in a short time. As a result, for example, in an automobile / mobile phone system, it becomes possible to perform control of transmission power of a mobile device, handoff control, and the like with good responsiveness.

The present invention is not limited to the above embodiment. For example, in the above embodiment, the case where the root roll-off filter 63 is provided in the digital demodulation circuit 22 has been described, but as shown in FIG. 5, it is provided between the second mixer 54 and the intermediate frequency integrated circuit 57 in the reception circuit 21. The root roll-off filter 58 may be provided. With this configuration, the reception electric field strength detection circuit 32 detects the reception signal level of the second reception intermediate frequency signal from which the inter-code interference is removed by passing through the root roll-off filter 58. Here, the root roll-off filter 58
The phase space diagram of the second received intermediate frequency signal that has passed through is as shown in FIG. 6, for example. That is, the degree of convergence at each phase convergence position is higher than that of the signal before passing through the root roll-off filter. Therefore, by detecting the received signal level of the second received intermediate frequency signal that has passed through the root roll-off filter 58, it is possible to detect the received signal level with less variation.

The timing of sampling the reception signal level of the second reception intermediate frequency signal corresponds to other phase convergence positions in addition to the timing corresponding to the phase convergence positions shown in P1 of FIG. 4 and P2 of FIG. May be set to each timing, or may be set to each timing corresponding to a plurality of different phase convergence positions where the received signal levels are almost equal. If the reception signal level is detected at each timing corresponding to a plurality of different phase convergence positions in this way, the number of samplings of the reception signal level per unit time can be increased, which allows the reception electric field strength to be increased. The time required to calculate the average value can be further shortened, and thus the responsiveness of various controls using the received electric field strength can be further improved.

In addition, the configurations of the sampling signal generating means and the received electric field strength detecting means, the type and use of the wireless communication device, the type of modulation method, etc. can be modified in various ways without departing from the scope of the present invention. .

[0031]

As described in detail above, according to the present invention, the sampling signal generating means generates a sampling signal in synchronization with the demodulated digital signal or a signal synchronized with this digital signal, and the received electric field strength detecting means is provided. Thus, the received electric field strength of the received radio signal is detected at the sampling point represented by the generated sampling signal.

Therefore, according to the present invention, there is provided a radio communication device capable of detecting the received electric field strength in a short time and with high accuracy and thereby improving the responsiveness of various controls based on the received electric field strength. be able to.

Further, according to the present invention, when a roll-off filter is inserted in the transmission system, this roll-off filter is provided in the radio circuit, and the reception electric field of the reception radio signal after passing through this roll-off filter. Since the strength is detected at the sampling point represented by the sampling signal, the received electric field strength can be measured with higher accuracy.

[Brief description of drawings]

FIG. 1 is a circuit block diagram showing a configuration of a receiving system of a digital portable radio telephone according to an embodiment of the present invention.

FIG. 2 is a circuit block diagram showing an overall configuration of a digital portable radio telephone according to an embodiment of the present invention.

FIG. 3 is a circuit block diagram showing a configuration of the intermediate frequency integrated circuit shown in FIG.

FIG. 4 is a diagram showing a measurement result of a phase space diagram for use in explaining the operation of the circuit shown in FIG. 1.

FIG. 5 is a circuit block diagram showing a configuration of a receiving system of a digital portable radio telephone according to another embodiment of the present invention.

6 is a diagram showing a measurement result of a phase space diagram for use in explaining the operation of the circuit shown in FIG.

FIG. 7 is a diagram showing a relationship between input data streams X _k and Y _k and a phase change amount Δφ.

FIG. 8 is a diagram showing a phase space diagram showing the phase mapping positions of encoded data I _k and Q _k output from the differential phase encoding mapping circuit.

[Explanation of symbols]

11 ... Microphone 12 ... Speech encoder 13 ... Error correction encoder 14 ... Digital modulation circuit 15 ... Mixer 16 ... Power amplifier (PA) 17 ... Antenna duplexer 18 ... Antenna 21 ... Reception circuit 22 ... Digital demodulation circuit 23 ... Error correction Decoder 24 ... Voice decoder 30 ... Control circuit 30a ... Averaging means 31 ... Frequency synthesizer 32 ... Received field strength detection circuit 33 ... Console unit 51 ... High frequency amplifier 52 ... First mixer 53 ... First intermediate frequency filter 54 ... 2 mixer 55 ... local oscillator 56 ... second intermediate frequency filter 57 ... intermediate frequency integrated circuit 57a ... intermediate frequency amplifier circuit 57b ... detection diode 58, 63 ... root roll-off filter 61 ... A / D converter 62 ... quadrature demodulation Device 64 ... Delay detector 65 ... Synchronization / clock recovery circuit

Claims (2)

[Claims] 1. A radio communication device comprising a receiving circuit system for receiving a radio signal PSK-modulated by a digital signal in a radio circuit and then demodulating the digital signal in a demodulation circuit, wherein the demodulated digital signal or the digital signal Sampling signal generating means for generating a sampling signal in synchronism with a signal synchronized with the signal, and a reception electric field strength of the received radio signal at a sampling point represented by the sampling signal generated by the sampling signal generating means. A wireless communication device comprising: a received electric field strength detection unit for detecting. 2. A roll-off filter for removing frequency components outside the transmission band is provided in the radio circuit, and the received electric field strength is detected from the received radio signal after passing through the roll-off filter. The wireless communication device according to claim 1.