JP3101437B2 - Digital mobile phone device - Google Patents

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 portable telephone device having a diversity control function.

[0002]

2. Description of the Related Art A mobile phone practically used as a land mobile communication system is also called a cellular phone, and the number of users tends to increase due to its convenience. In addition, as a further advance of the form of such a mobile phone, a small, lightweight, portable mobile phone,
It is becoming a typical mobile communication format for individuals.

Under such circumstances, a digital cellular phone device (also referred to as a digital cellular phone) has been proposed as a cellular phone system capable of communicating "anytime, anywhere, with anyone" for the coming advanced information society. Is considered. This digital mobile phone device 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 that there is. Therefore, there is no doubt that the future will clearly have an advantage over the current system in terms of economic efficiency.

[0004] In realizing such a digital portable telephone device, there are some technical problems to be solved. Among them, digital signal transmission technology includes a high-efficiency digital modulation / demodulation technology and a fading countermeasure technology. Here, fading is when a transmission wave is received at a receiving point via a plurality of propagation paths,
This refers to a phenomenon in which the propagation condition changes, such as when the receiving point moves, and the level of the received signal fluctuates due to cancellation or reinforcement depending on the phase of the radio wave.

[0005] As a countermeasure against this fading,
In a mobile communication system, diversity control is attracting attention as an effective means. In diversity control,
Usually, a plurality of antennas are installed on the receiving side, and when the reception state is deteriorated due to fading, an optimum antenna with good conditions is selected to perform communication. Therefore,
In a digital mobile phone device, two antennas are usually arranged at a predetermined interval, and a subframe time of 20 msec is set.
Diversity control is performed such that the two antennas are switched every time and an antenna having a higher electric field strength (hereinafter referred to as RSSI) of a received radio wave is selected as a receiving antenna.

FIG. 2 is a schematic diagram showing the configuration of a superframe used in a conventional digital portable telephone device. As shown in the figure, one superframe is 720 msec, during which a plurality of traffic channels TCH are allocated. In addition, each communication channel TCH includes:
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, there are 36 L periods (period for diversity control) in one superframe. Therefore, the RS of the received radio wave fetched from the two antennas every L period
A method is adopted in which the SI value is measured, and the antenna having the larger RSSI value is selected and received.

[0007]

However, according to this method, each circuit for measuring the RSSI value connected to the two antennas is always operated, and furthermore, 20 circuits are used.
By switching each circuit every msec, the RSSI value of each antenna is measured. For this reason, the number of switching of the circuit is large, and the power consumption is large. As a result, there is a problem that the battery life is shortened and the talk time and the standby time are shortened.

The present invention has been made in view of the above situation, and has as its object to provide a digital portable telephone device capable of reducing power consumption in diversity control and always ensuring a stable reception level. I have.

[0009]

In order to achieve the above object, the present invention relates to a digital portable telephone device having a diversity control function of selecting and receiving one of a plurality of antennas according to the electric field strength. Reference antenna setting means for setting, as a reference antenna in a first period, an antenna that provides the largest electric field strength in a first diversity control section given once in a first period; Comparing means for comparing an electric field intensity obtained through the reference antenna with a threshold value in a second diversity control section given once in each of the plurality of second periods constituting the second period, and a threshold value of the electric field intensity. Control means for controlling reception so as to receive by the reference antenna when the value is larger than the threshold value and to switch to another antenna when the value is smaller than the threshold value. It is characterized by a door.

Further, according to the present invention, the reference antenna setting means predicts a time change of the electric field strength based on a result of the electric field strength measured in the two consecutive first periods, and performs It is characterized in that a reference antenna is set in one period. Further, the invention is characterized in that the first period is a super-frame and the second period is a sub-frame.

[0011]

According to the above arrangement, the reference antenna setting means sets the antenna having 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 sets two consecutive
Based on the result of the electric field strength measured in one first period, a time change of the electric field strength is predicted, and a reference antenna in the next first period is set.

The first period is composed of a plurality of second periods, and each of the second periods is provided with one second diversity control section. 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 receives by the control antenna when the electric field strength is larger than the threshold value by the control means, and 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, a reference antenna used in one superframe is selected, and a reception antenna used in each subframe is selected based on this antenna. You. Therefore, when the fading phenomenon to be subjected to the diversity control is relatively small, it is possible to receive the signal with the reference antenna without changing the receiving antenna, thereby reducing power consumption.

[0014]

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

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

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

Control data such as a message is demodulated, passed through a data demodulation circuit including a gate array and a DSP (Digital Signal Processor), and then processed by a TDMA processing circuit 3 for decoding and error correction. Done. The processing data is stored in the first memory 13 by the control unit 6, and processing based on the data stored by the control unit 6 is performed.

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

The display section 12 is a circuit for controlling display elements such as LEDs and LCDs, and the key section 18 is a circuit for controlling keys to be inputted. 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 super frame 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. In addition, a reception section R, an idle section I, a transmission section T, and a diversity control section L are sequentially assigned to the subframes.

Here, a point L at which the RSSI level is measured
Are sections indicated by and in the figure. The section is
This is a section in which the RSSI level is measured from both antennas A and B, and the number of measurements is one per superframe. The section is a section for measuring the RSSI level of a radio wave received using the antenna determined in the section as a reference antenna. 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 flowchart showing the procedure of the diversity control in the digital portable telephone device according to the present invention. It is determined whether or not the frame is a super frame, that is, whether or not the diversity control section L is a section by interrupt processing every 20 msec (S
1) If it is a super frame (Ye in S1)
s), the signal is received by the antenna A or the antenna B (this is referred to as antenna X ^* ), and the RF
-RSSI detected by IF unit 1 or RF / IF unit 11
Measure the value. And RSSI measured at antenna X ^*
Data is stored in the second memory 14. This value is set to a. Next, the antenna is switched to the other antenna (hereinafter, referred to as antenna Y ^* ) (S3), and the RSSI value is measured and stored in the second memory 14 (S4). This value is set to b.

Subsequently, the data of the RSSI value measured in the previous superframe is defined as 1a and 1b, and the data of the RSSI value measured this time is ax =
The calculation of aa, Bx = 1bb is performed (S5). In this formula, the absolute values of Ax and Bx represent the amount of change over time of the RSSI level received from the antenna X ^* and the antenna Y ^* and detected by the IF unit, and the polarity represents the directionality. ing. And these two data A
Based on x and Bx and the data of 1a, 1b, a, and b described above, which antenna is better to receive in the next superframe is predicted and determined (S6). For example, when the RSSI levels of both the antennas A and B change linearly in the + direction, the RSSI levels in the next superframe are obtained 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 super frame, that is, if the diversity control section L is not a section (No in S1), the RS in the section
The SI measurement processing (S8 → S16) is executed. First, it is determined whether or not the flag is 1 (S8). here,
Regarding the flag, when the threshold value falls below a threshold value set for the determination of the RSSI value (this value is stored in advance in the third memory 17 shown in FIG. 1). It is set up (that is, 1). Therefore, if the flag is 1 (Yes in S8), the signal is received by the antenna determined in the processing in the above-described superframe section, and the RSSI value is measured (S10). If the flag is not 1 (S
In the case of No in 8), the current antenna is switched (S9), the received antenna is received, and the RSSI value is measured (S10).

If the measured value is smaller than the threshold value (Yes in S11,
If the SI level is degraded), switch to the other antenna and measure the RSSI value (S12). Further, when the 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 switch is switched to the original antenna by the changeover switch 16 (S15). If the measured value is smaller than the threshold value (No in S13), it is determined that the reception is not performed this time, the flag is set to 1, and the switch is switched to the original antenna by the switch 16 (S16). .

With the above processing, 1 is added to the superframe.
The receiving antenna in the next superframe is predicted and determined based on the RSSI values for the antennas A and B measured in the diversity control section provided on a frequency basis. Then, using this antenna as a reference antenna, the RSSI level is measured in the diversity control section provided once in the subframe,
If receiving with the reference antenna is inappropriate,
It is controlled to switch to another antenna and receive.
For this reason, in a situation where the fading phenomenon is relatively small, in the section, reception can be continued with almost no switching of the reference antenna,
Power consumption is reduced.

[0026]

According to the present invention described above, the reference receiving antenna used in the first period is set by the reference antenna setting means, and every second period is set based on this set antenna. Then, the electric field strength of the received radio wave is measured, and the electric field strength measured by the comparing means is compared with a threshold value. Based on the result, the receiving antenna is switched by the control means.

Therefore, unlike the related art, the circuit for measuring the electric field strength is always operated, and it is not necessary to switch the antenna in each measurement, so that the number of times of switching the antenna is obviously reduced, and the power consumption is effectively reduced. Reduction can be achieved. As a result, in terms of battery life, call time and standby time can be made longer. Further, antenna switching is performed by comparing the measured electric field strength with a threshold value, so that a stable reception level can always be ensured. Therefore, it is possible to provide an extremely easy-to-use and economical digital mobile phone system.

[Brief description of the 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 super frame 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.

[Description of Signs] 1 RF / IF unit (receiving system) 6 Control unit 11 RF / IF unit (receiving system) 14 Second memory 16 Changeover switch 17 Third memory A Antenna B Antenna

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04B ⁷ /02-7/08 H04B 7/26 H04Q 7/00-7/38

Claims (3)

(57) [Claims] A first diversity control section provided once in a first period in a digital portable telephone device having a diversity control function of selecting and receiving one of a plurality of antennas according to an electric field strength. A reference antenna setting unit that sets an antenna that provides the highest electric field strength as a reference antenna in the first period; and 1 for each of a plurality of second periods that constitute the first period.
Comparing means for comparing the electric field strength obtained through the reference antenna in a second diversity control section given to the reference antenna with a threshold value, and when the electric field strength is larger than the threshold value, receiving the electric field strength by the reference antenna; Control means for switching to another antenna to control reception when the threshold value is smaller than the threshold value. 2. The method according to claim 1, wherein the reference antenna setting unit predicts a time change of the electric field intensity based on a result of the electric field intensity measured in the two consecutive first periods, and sets the time in the next first period. 2. The digital mobile phone device according to claim 1, wherein a reference antenna is set. 3. The digital portable telephone device according to claim 1, wherein said first period is a superframe, and said second period is a subframe.