JPH06140971A - Digital portable telephone set - Google Patents

Abstract

PURPOSE:To reduce power consumption and to secure a stable reception level by comparing a measured electric field strength (RSSI value) with a threshold level and selecting a reception antenna from the result of comparison. CONSTITUTION:When a flag is set to 1, the signal is received by an antenna decided by the processing for a super-frame for a prescribed period and the RSSI is measured. When the flag is not set to 1, the signal is received by a selected antenna and the RSSI is measured. When the measured value is smaller than the threshold level in a 3rd memory 17, other antenna is selected and the RSSI is measured. When the measured value is larger than the threshold level, the flag is set to 0 and the antenna is used. When the reception is finished, a changeover switch 16 is used to select the original antenna and when the measured value is smaller than the threshold level, the signal is not received this time, the flag is set to 1 and the changeover switch 16 is used to select the original antenna.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a digital mobile phone device having a diversity control function.

[0002]

2. Description of the Related Art A car telephone, which has been put into practical use as a land mobile communication system, is commonly called a cellular telephone, and because of its convenience, the number of users tends to increase more and more. In addition, as a further advancement of the form of such a car phone, a small and lightweight portable phone is
It is becoming a representative of mobile communication forms targeting individuals.

Under such circumstances, a digital mobile phone device (also called digital cellular) is used as a mobile phone system capable of "anytime, anywhere, with anyone" communication for the coming advanced information society. Is being considered. This digital mobile phone uses a digital mobile communication system, and is superior in compatibility with a fixed digital communication network (ISDN) capable of responding to various services as compared with the conventional analog communication system. It has the characteristic of being Therefore, in terms of economy, there is no doubt that it will have a clear advantage over the current method in the future.

By the way, there are some technical problems to be solved in realizing such a digital portable telephone device. Among them, high-efficiency digital modulation / demodulation technology and fading countermeasure technology are related to digital signal transmission technology. Here, fading means that when a transmitted wave is received at a receiving point via a plurality of propagation paths,
This is a phenomenon in which the level of the received signal fluctuates because the propagation conditions change, such as when the receiving point moves, and they cancel or strengthen each other depending on the phase of the radio waves.

As a measure against this fading,
Diversity control is attracting attention as an effective means in mobile communication systems. With diversity control,
Normally, a plurality of antennas are installed on the receiving side, and when fading deteriorates the reception state, the optimum antenna with good conditions is selected for communication. Therefore,
In a digital mobile phone device, usually, two antennas are arranged at a predetermined interval, and the subframe time is 20 msec.
Diversity control is performed such that the two antennas are switched every time, and the antenna having the higher electric field strength (hereinafter, referred to as RSSI) of the received radio wave is selected as the receiving antenna.

FIG. 2 is a schematic view showing the structure of a super frame used in a conventional digital mobile phone device. As shown in the figure, one superframe is 720 msec, and a plurality of communication channels TCH are allocated during this period. In addition, for each call channel TCH,
As a subframe of 20 msec, a reception section R, an idle section I, a transmission section T, and a diversity control section L are sequentially assigned. Therefore, one superframe has 36 L periods (periods for diversity control). Therefore, the RS of the received radio waves taken from two antennas every L period
A method is used in which the SI value is measured and the antenna with the larger RSSI value is selected and received.

[0007]

However, according to this method, the circuits connected to the two antennas for measuring the RSSI value are always activated, and further, 20
The RSSI value for each antenna is measured by switching each circuit every msec. Therefore, the number of times the circuit is switched is large and power consumption is high. As a result, the battery life is shortened, which causes a problem that the call time and the standby time are shortened.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a digital portable telephone apparatus capable of reducing power consumption in diversity control and always ensuring a stable reception level. There is.

[0009]

In order to achieve the above object, the present invention provides a digital portable telephone apparatus having a diversity control function for selecting and receiving one of a plurality of antennas according to the electric field strength. , A reference antenna setting means for setting an antenna having the largest electric field strength in the first diversity control section given once in the first period as a reference antenna in the first period, and the first period. And a comparison means for comparing an electric field strength obtained through the reference antenna in a second diversity control section given once in each of a plurality of second periods constituting the above with a threshold value, and the electric field strength is a threshold value. When the value is larger than the value, the reference antenna is used for reception, and when the value is smaller than the threshold value, a control means for controlling to receive by switching to another antenna is provided. It is characterized by a door.

Further, according to the present invention, the reference antenna setting means predicts the time change of the electric field strength based on the result of the electric field strength measured in two consecutive first periods, and the next order of It is characterized in that the reference antenna in the period 1 is set. Further, the present invention is characterized in that the first period is a superframe and the second period is a subframe.

[0011]

According to the above structure, the reference antenna setting means sets the antenna that provides the largest electric field strength in the first diversity control section given once in the first period to the reference antenna in the first period. Set as. In this case, the reference antenna setting means has two consecutive antennas.
Based on the result of the electric field strength measured in one of the first periods, the time change of the electric field strength is predicted, and the reference antenna in the next first period is set.

The first period is composed of a plurality of second periods, and one second diversity control section is given to each of the second periods. Here, the first period can be a superframe in digital communication, and the second period can be a subframe. Further, the comparing means compares the electric field strength obtained through the set reference antenna with a threshold value, and further, when the electric field strength is larger than the threshold value, the comparing means receives the electric field strength by the reference antenna and detects the electric field strength. When it is smaller than the threshold value, it is controlled to switch to another antenna for reception.

As a result, in the diversity control of the digital portable telephone device, for example, the reference antenna used in one superframe is selected, and the reception antenna used in each subframe is selected based on this antenna. It Therefore, when the fading phenomenon that is the subject of diversity control is relatively small, the reference antenna can be used for reception with almost no switching of the receiving antenna, and power consumption can be reduced.

[0014]

1 is a block diagram showing the configuration of a mobile device of a digital portable telephone device according to the present invention. This mobile device has two antennas, an antenna A for both transmission and reception and an antenna B for reception, in order to perform diversity control. The antenna A has a transmitting / receiving RF / IF unit 10 and a receiving system RF / IF unit 11 via a transmission / reception selector switch 15.
However, the RF B / IF unit 1 of the receiving system is connected to the antenna B, respectively.

In the RF / IF units 1 and 11 of the reception system, only the input reception RF signal is extracted and amplified by the RF filter and the RF amplifier from the high frequency signals (hereinafter referred to as RF signals) input from the antennas A and B. It is supposed to be done. In addition, the PLL frequency synthesizer (variable frequency divider) 7 receives the RF / IF units 1 and 11 of the receiving system by a control signal from the control unit 6 including a microcomputer.
And a tuning frequency in the RF / IF unit 10 of the transmission system is determined, and a reference clock is generated. And RF of the receiving system
In the IF units 1 and 11, the reference clock and the RF signal from the RF amplifier are mixed by the MIX circuit, and only the difference of the frequency spectrum generated by using the non-linear portion of the transistor is passed through the IF filter and the IF amplifier circuit. It is designed to be taken out.

Next, the RF / IF unit 1 or the RF / IF unit
The frequency signal extracted by the changeover switch 16 from any one of the sections 11 is transferred to the demodulator 2 in the π / 4 shift 4-phase Q mode.
PSK (four-phase quadrature phase shift) demodulation and TD
The MA processing circuit 3 performs TDMA (time division multiplexing) processing.
After this processing, VSELP processing is performed on the audio signal portion, and AD / PCM conversion is performed by the D / A conversion circuit 4.
D / A conversion of (pulse code modulation) is performed. And
The audio processing circuit 5 performs amplification processing and impedance conversion for converting an audio signal into a signal that can be supplied to a speaker or the like, and outputs the audio signal through the speaker or the ringer.

Further, the control data such as a message is demodulated and then processed by a TDMA processing circuit 3 such as decoding and error correction through a data demodulating circuit including a gate array and a DSP (digital signal processor). Done. The processing data is stored in the first memory 13 by the control unit 6, and the processing based on the data stored by the control unit 6 is performed.

On the other hand, on the transmitting side, the voice signal from the microphone emitted by the user is converted into an electric signal by the voice processing circuit 5, and further the ADPCM / P by the A / D conversion circuit 8.
It is converted into a digital signal of CM and VSELP processing is performed. For control data such as messages,
The control unit 6 uses various tables in the first memory 13,
The data modulation circuit performs code conversion and error correction. Subsequently, the digital data of voice and control data is subjected to TDMA processing by the TDMA processing circuit 30, modulated by the π / 4 shift 4-phase QPSK modulator 9, and then mixed with the signal corresponding to the set channel. To be done. Further, in the RF / IF unit 10 of the transmission system, only the necessary frequency component is R
Only the output is efficiently sent out through the antenna A which is taken out by the F filter and the RF amplifier circuit, amplified in power, and switched by the transmission / reception changeover switch 5 for transmission.

The display unit 12 is a circuit for controlling display elements such as LEDs and LCDs, and the key unit 18 is a circuit for controlling input keys. The functions of the second memory 14 and the third memory 17 will be described later. FIG. 3 is a schematic diagram showing a diversity control section in a superframe used in the digital mobile phone device according to the present invention. As shown in the conventional example of FIG. 2, one superframe is 720 msec, and each subframe constituting one superframe is 20 msec. Further, a reception section R, an idle section I, a transmission section T, and a diversity control section L are sequentially assigned to the subframe.

Here, the point L where the RSSI level is measured
Indicates a section indicated by and in the figure. The section is
This is a section in which the RSSI level is measured from both the A and B antennas, and the number of measurements is once in one superframe. The section is a section in which the RSSI level of the radio wave received using the antenna determined in the section as a reference antenna is measured. Then, in the section, the RSSI level of the radio wave received by the reference antenna is measured and compared with a preset threshold value.

FIG. 4 is a flow chart showing the procedure of diversity control in the digital portable telephone device according to the present invention. By the interrupt processing every 20 msec, it is determined whether or not it is a superframe, that is, whether or not the diversity control section L is a section (S
1) If it is a super frame (Yes in S1)
In the case of s), the signal is received by the antenna A or the antenna B (this is referred to as the antenna X ^* ), and RF
-RSSI detected by IF unit 1 or RF / IF unit 11
Measure the value. And RSSI measured with antenna X ^*
The data is stored in the second memory 14. This value is a. Next, the other antenna (this is referred to as antenna Y ^* ) is switched (S3), and the RSSI value is similarly measured and stored in the second memory 14 (S4). Let this value be b.

Next, the data of the RSSI value measured in the previous superframe is set to 1a and 1b, and Ax = 1 with the above-mentioned a and b of the data of the RSSI value measured this time.
Calculation of aa and Bx = 1b-b is performed (S5). In this calculation formula, the absolute values of Ax and Bx represent the time change amount of the RSSI level received from the antenna X ^* and the antenna Y ^* and detected by the IF unit, respectively, and the polarity represents its directionality. ing. And these two data A
Based on x, Bx and each of the above data 1a, 1b, a, b, it is predicted and determined which antenna should receive in the next superframe (S6). For example, when the RSSI level changes linearly in the + direction for both antennas A and B, the RSSI level in the next superframe is calculated by a + Ax and b + Bx.
Therefore, the antenna with the higher predicted RSSI level is selected and switched to the antenna determined by the changeover switch 16 shown in FIG. 1 (S7). The RSSI values a and b measured this time are stored as 1a and 1b in the second memory 14 shown in FIG.

Next, if it is not a superframe, that is, if the diversity control section L is not a section (No in S1), RS in the section is
The SI measurement process (S8 → S16) is executed. First, it is determined whether the flag is 1 (S8). here,
Regarding the flag, when the threshold value is lower than the threshold value set for judging the RSSI value (this value is stored in advance in the third memory 17 shown in FIG. 1), the flag is set. Set up (that is, set to 1). Therefore, when the flag is 1 (Yes in S8), the antenna determined by the processing in the section of the superframe described above is received and the RSSI value is measured (S10). If the flag is not 1 (S
If No in 8), the current antenna is switched (S9), the switched antenna is received, and the RSSI value is measured (S10).

If the measured value is smaller than the threshold value (Yes in S11, RS
If the SI level is degraded), switch to the other antenna and measure the RSSI value (S12). Further, when this measured value is larger than the threshold value (S13
In the case of Yes), the flag is set to 0 and the signal is received by the antenna (S14). When the reception is completed, the changeover switch 16 is used to switch to the original antenna (S15). If the measured value is smaller than the threshold value (No in S13), it is assumed that the reception is not performed this time, the flag is set to 1, and the switch 16 is used to switch to the original antenna (S16). .

By the above processing, 1 is added to the super frame.
The receiving antenna in the next superframe is predicted and determined based on the RSSI values of the antennas A and B measured in the diversity control section provided every time. Then, using this antenna as a reference antenna, the RSSI level is measured in the diversity control section provided once in the subframe,
If it is inappropriate to receive with the reference antenna,
It is controlled to switch to another antenna and receive.
Therefore, under a situation where the fading phenomenon is relatively small, it becomes possible to continue the reception without switching the reference antenna in the section.
Power consumption is reduced.

[0026]

As described above, according to the present invention, the reference antenna setting means sets the reference receiving antenna used in the first period, and the reference antenna setting means sets the reference antenna every second period. Then, the electric field strength of the received radio wave is measured, and the electric field strength measured by the comparison means is compared with a threshold value. From the result, the control means switches the reception antenna.

Therefore, unlike the conventional case, the circuit for measuring the electric field strength is always operated, and it is not necessary to switch the antenna in each measurement, which obviously reduces the number of times the antenna is switched, and the effective power consumption is reduced. You will be able to reduce. As a result, in terms of battery life, it becomes possible to prolong the call time and standby time. Further, since the antennas are switched by comparing the measured electric field strength with the threshold value, it becomes possible to always secure a stable reception level. Therefore, it is possible to provide a digital mobile phone system that is very easy to use and economical.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a mobile device of a digital mobile phone device according to the present invention.

FIG. 2 is a schematic diagram showing a configuration of a super frame used in a conventional digital mobile phone device.

FIG. 3 is a schematic diagram showing a diversity control section in a superframe used in the digital mobile phone device according to the present invention.

FIG. 4 is a flowchart showing a procedure of diversity control in the digital mobile phone device according to the present invention.

[Explanation of symbols]

 1 RF / IF Unit (Reception System) 6 Control Unit 11 RF / IF Unit (Reception System) 14 Second Memory 16 Changeover Switch 17 Third Memory A Antenna B Antenna

Claims (3)

[Claims] 1. In a digital mobile phone device having a diversity control function of selecting and receiving one of a plurality of antennas according to the electric field strength, a first diversity control section provided once in a first period. A reference antenna setting means for setting the antenna that can obtain the largest electric field strength as a reference antenna in the first period, and one in each of the plurality of second periods forming the first period.
Comparing means for comparing an electric field strength obtained through the reference antenna in a second diversity control section given twice with a threshold value; and when the electric field strength is larger than the threshold value, the reference antenna receives the electric field strength. A digital mobile phone device, comprising: a control unit for controlling to receive by switching to another antenna when it is smaller than a threshold value. 2. The reference antenna setting means predicts a temporal change in electric field intensity based on the result of the electric field intensity measured in two consecutive first periods, and predicts the temporal change in the electric field intensity in the next first period. The digital mobile phone device according to claim 1, wherein a reference antenna is set. 3. The digital mobile phone device according to claim 1, wherein the first period is a superframe, and the second period is a subframe.