JP2002368660A - Mobile communication terminal - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To transmit / receive information using an antenna that always has a good reception state. SOLUTION: In a rising period of a burst signal for each reception period, an antenna switching control unit 16 performs first switching control for switching connection antennas, and determines a connection antenna in the reception period based on reception levels before and after switching. Then, when the determined antenna is different from the connection antenna at the present time, the second switching control for switching the connection antenna to the determined antenna is performed. As a result, communication can be performed with the antenna in the best reception state for each reception period.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a portable communication terminal having a plurality of antennas and transmitting and receiving information by using an antenna having a good reception state.

[0002]

2. Description of the Related Art Conventionally, in a mobile communication terminal such as a mobile phone, two or more antennas are appropriately arranged in a housing of the mobile phone to perform transmission / reception in order to improve transmission / reception sensitivity due to multipath fading or the like. , So-called diversity. In this diversity, one system is selected from antennas provided in a plurality of systems at the time of reception.
Communication with the wireless network is performed by the system antenna.
Then, when the radio wave condition deteriorates during communication, communication is always performed by an antenna having a good reception state by switching to another antenna.

Here, a time division multiple access system (TDMA;
Consider the case where the above-described diversity is applied to Time Division Multiplex Access). In the time division multiple access system, as shown in FIG. 6, a reception period and a pause period are repeated at a constant cycle. At this time, it is desirable that communication in the reception period be performed by the antenna having the best reception state.

[0004]

SUMMARY OF THE INVENTION However, TDM
Since it is impossible to switch the receiving antenna during the receiving period of A, it takes one receiving period to determine the receiving state of each antenna included in the terminal, and the best antenna can be determined immediately. There was a problem that can not be. In addition, it cannot be determined that the reception state is good or bad without actually switching antennas to receive the signal. Therefore, it is undeniable that the reception state deteriorates as a result of the switching. In such a case, since the antenna cannot be switched during the reception period, communication must be continued using an antenna having a poor reception state. As a result, errors have continued since the antennas have been switched, and there have been problems such as inability to communicate, and there has been a problem that the diversity function cannot be sufficiently exhibited.

The present invention has been made in view of such circumstances, and it is an object of the present invention to provide a portable communication terminal that always transmits and receives information using an antenna having a good reception state.

[0006]

In order to achieve the above object, the present invention comprises a plurality of antennas, and receives a signal from a radio network at a predetermined interval by any one of the antennas. In the portable communication terminal, an antenna switching unit that switches a connection antenna connected to an internal circuit of the portable communication terminal, a smoothing unit that outputs a smoothed voltage obtained by smoothing a radio wave voltage of a received signal, and the antenna switching unit. Antenna switching control means for controlling, in a rising period of the smoothed voltage waveform for each reception period, the antenna switching control means performs first switching control for switching a connected antenna, and performs the smoothing before and after switching. The connection antenna in the reception period is determined based on the voltage, and if the determined antenna is different from the connection antenna at the present time, the connection antenna is To provide a mobile communication terminal and performing a second switching control for switching the antenna to determine the antenna.

[0007] According to such a configuration, an antenna having a good radio wave reception state is determined as a connection antenna for each reception period, so that communication can always be performed using an antenna having a good radio wave state. Thus, stable communication quality can be ensured even for instantaneous received wave fluctuations due to fading or the like. In addition, since the receiving antenna is selected immediately before the received wave, it is possible to reduce the frequency of occurrence of voice interruption during a call due to deterioration of radio quality, and to sharply disturb radio waves such as high-frequency fading. Can be followed. Further, the error rate can be reduced, and disconnection of the line due to deterioration of the reception state can be avoided. Further, since the receiving circuit is a single system, a configuration at a relatively low cost is possible.

Further, according to the present invention, the antenna switching control means performs the first switching control when a voltage value output from the smoothing means exceeds a predetermined value set in advance. The mobile communication terminal according to claim 1, wherein: According to such a configuration, the rising period can be detected by a relatively simple circuit, and the above-described connection antenna can be accurately determined in the rising period.

Further, according to the present invention, the antenna switching control means performs the first switching control after a lapse of a predetermined period set in advance from the start of the period. Provide a mobile communication terminal. According to the time division multiple access method, as shown in FIG. 6, a reception period and a pause period are repeated at a constant cycle. Therefore, the rising period existing between the pause period P0 and the reception period P2 as shown in FIG. 2 is also repeated at a constant period. By grasping this period, the first switching control can be accurately performed in the rising period. It is possible to do.

Further, in the present invention, the antenna switching control means compares the smoothed voltage immediately before and immediately after the antenna switching by the first switching control, and connects an antenna having a higher voltage during the reception period. The portable communication terminal according to any one of claims 1 to 3, wherein an antenna is determined. According to such a configuration, it is possible to easily detect an antenna having a good radio wave condition.

Further, according to the present invention, the antenna switching control means predicts a voltage value after a predetermined time based on a radio wave voltage output from the smoothing means before the antenna switching,
4. The system according to claim 1, wherein the measured value after the antenna switching after the predetermined time is compared with the predicted value, and an antenna having a higher voltage is determined as a connected antenna in the reception period. The portable communication terminal according to any one of the above items is provided. According to such a configuration, even when it is difficult to compare the instantaneous voltage values immediately before and immediately after the antenna switching as described above, it is possible to compare the estimated value after a predetermined time has elapsed with the actually measured value. Thus, it is possible to select an antenna having a good radio wave condition. Also,
Regarding the method of calculating the predicted value after the above-described predetermined time, the above-described smoothed voltage is a waveform that can be expressed by a so-called linear function that changes linearly, so that the voltage value after the predetermined time is predicted by a simple calculation. It becomes possible. As described above, since the predicted value can be obtained by a simple calculation, it is possible to calculate the predicted value in an extremely short time, and it is possible to quickly determine the connection antenna.

The portable communication terminal of the present invention includes a so-called CDMA (code division multiple access) system and a PDC (Pe
In addition to a mobile phone of the rsonal Digital Cellular System (Personal Handyphone System) (registered trademark) type, a portable terminal called a PDA (Personal Digital Assistants: personal information equipment) is also included.
Here, in the case of a PDA, in addition to a device having a built-in communication means, even if a communication means is externally connected, a calling (incoming call, communication) process which will be described later, which is a feature of the present invention, is performed by the PD.
What is performed by the A body is included in the present invention.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a configuration of a mobile communication terminal according to one embodiment of the present invention. As shown in FIG. 1, the mobile communication terminal according to the present embodiment includes two antennas, an antenna A and an antenna B, and one of the antennas is connected to an internal circuit of the terminal by the antenna switching unit 11. Hereinafter, an antenna connected to the terminal internal circuit is referred to as a connection antenna.

The received signal received by the connection antenna is transmitted to an LNA (Low Noise Amplifier) 12, a mixer 1
3. Converted to a low frequency by the intermediate frequency amplifier 14,
DC conversion is performed by the DC conversion circuit 15. As a result,
The voltage waveform of the received signal output from the DC conversion circuit 15 is a burst signal as shown in FIG. The DC conversion circuit 15 is also used as a circuit for deriving an RSSI signal serving as an index for displaying an antenna bar or the like, and is a so-called AC / DC converter. And D
The received signal smoothed by the C conversion circuit 15 is output to the antenna switching control unit 16. The antenna switching control unit 16 controls the antenna switching unit 11 based on the received signal. The details of the processing performed by the antenna switching control unit 16 will be described later.

Next, the operation of the portable communication terminal having the above configuration will be described. First, in the present embodiment, FIG.
In the received signal (hereinafter, referred to as a burst signal) shown in (1), in the rising period P1, the antenna switching control unit 16 performs the first switching control to switch the connection antenna once, and based on the change in the reception level before and after the switching. Thus, the connection antenna in the reception period P2 is determined. Note that the rising period P1 is a very short period existing between the pause period P0 and the reception period P2.

Hereinafter, an antenna determination process performed by the antenna switching control unit to determine a connection antenna in the reception period P2 will be described. << 1st Embodiment >> First, the antenna determination processing of the mobile communication terminal according to the first embodiment of the present invention will be described with reference to FIG. For example, if the antenna A is selected as the connection antenna, the received signal received by the antenna A is output to the DC conversion circuit 15 via the LNA 12, the mixer 13, and the intermediate frequency amplifier 14,
The burst signal smoothed by the DC conversion circuit 15 is output to the antenna switching control unit 16. When the burst signal output from the DC conversion circuit 15 reaches a predetermined reception level f1 set in advance, the antenna switching control section 16 performs first antenna switching control. This is performed by outputting an antenna switching signal to the antenna switching unit 11. Thereby, the antenna switching unit 11 switches the connection antenna at the time t1, and as a result, the connection antenna becomes the antenna B.

When the connected antenna is switched by the antenna switching unit 11, the burst signal after the switching changes. For example, when the reception state of the antenna B is better than the reception state of the antenna A, the reception level at the time of switching becomes higher. On the other hand, when the reception state of the antenna B is worse than the reception state of the antenna A, , The reception level at the time of switching becomes low. Therefore, the antenna switching control unit 16 compares the reception level at the moment when the connection antenna is switched, that is, the reception level at time t1, and determines the antenna with the higher reception level as the connection antenna in the reception period P2.

For example, assume that the burst signal changes as shown in FIG. 4 by switching the connection antenna from antenna A to antenna B at time t1. In this case, as for the reception level at time t1, the reception level by the antenna A is a1, whereas the reception level by the antenna B is b1, and the reception level by the antenna B is lower. Therefore, the antenna switching control unit 16 determines that the reception state of the antenna after switching is worse than the reception state of the antenna before switching, and determines the antenna A that is the connection antenna before switching as the connection antenna in the reception period P2. . Then, the antenna switching control unit 16 determines whether or not the current connection antenna, that is, the connection antenna after the time t1 is different from the antenna determined as the connection antenna in the reception period P2. A switching signal is output (time t4). Accordingly, the antenna switching unit 11 switches the connection antenna from the antenna B to the antenna A at time t4. As a result, communication is performed by the antenna A during the reception period P2. In addition, as a result of performing the first antenna switching control, if the reception level after the antenna switching is higher, the antenna switching controller 16 does not output the antenna switching signal at time t4. Accordingly, communication in the reception period P2 is performed without switching the connection antenna between the time t1 and the time t2.

<< Second Embodiment >> Subsequently, the second embodiment of the present invention
The antenna determination processing of the mobile communication terminal according to the embodiment will be described. In the above-described first embodiment, when the reception level reaches the predetermined value f1, the antenna switching control unit 16
Performs the first antenna switching control, determines the connected antenna in the reception period by comparing the voltage levels immediately before and immediately after the antenna switching, but in the second embodiment, the first antenna switching control is performed before the first antenna switching control is performed. The reception level after a predetermined time is predicted based on the burst waveform output from the DC conversion circuit 15. Then, the measured value and the predicted value after a predetermined time are compared, and the antenna with the higher voltage is determined as the connected antenna in the reception period.

For example, assume that the burst signal changes as shown in FIG. 5 as a result of performing the first antenna switching control at time t1. The antenna switching control unit 16 performs a predetermined time later, for example, at time t3, based on the burst signal output from the DC conversion circuit 15 from time t0 at which the burst signal starts to be input to time t1 at which the first antenna switching control is performed.
Is predicted. Note that the predicted value of the reception level can be obtained by a calculation of a simple linear function.

Subsequently, at time t3, the antenna switching control unit 16 compares the measured value b3 with the predicted value a3, and determines the antenna having the higher reception level as the connection antenna in the reception period P2. According to the burst signal shown in FIG. 5, since the reception level at time t3 is higher for antenna A, antenna switching control section 16 determines the antenna to be connected to antenna A during the reception period. Subsequently, the antenna switching control unit 16 determines whether the connection antenna at the present time is different from the determined connection antenna, and outputs an antenna switching signal if different (time t4). As a result, the antenna switching unit 11 switches the connection antenna from the antenna B to the antenna A at time t4.

If the value at the time t3 is higher for the antenna B than for the antenna A, the antenna switching control unit 16 switches the connected antenna during the reception period to the antenna B.
To decide. In this case, since the connected antenna during the reception period and the current connected antenna are the same, the antenna switching control unit 16 does not output the antenna switching signal to the antenna switching unit 11. Accordingly, the reception period is started while being connected to the antenna B, and communication is performed by the antenna B.

Third Embodiment Next, a third embodiment of the present invention will be described.
The antenna determination processing of the mobile communication terminal according to the embodiment will be described. As shown in FIG. 6, the reception period and the pause period are repeated at a constant cycle. Therefore, the rising period existing between the pause period P0 and the reception period P2 as shown in FIG. 2 is also repeated at a constant period. Therefore, the antenna switching control unit 16 stores this cycle, and performs the above-described first switching control at regular time intervals. Thus, it is possible to accurately perform the first antenna switching control for determining the connection antenna in the rising period. Note that, in the method of determining the connection antenna in the reception period, the above-described determination method of the first embodiment or the second embodiment is employed.

<< Fourth Embodiment >> Subsequently, a third embodiment of the present invention will be described.
The antenna determination processing of the mobile communication terminal according to the embodiment will be described. In the above-described first and second embodiments, the connection antenna in the reception period is determined by comparing the values of the reception levels before and after the antenna switching. In the present embodiment, two output lines from which a burst signal is output from the DC conversion circuit 15 are provided, and the burst signal output from these output lines is used as an input to a comparison circuit (comparator). At this time, a delay circuit is provided on one of the output lines, and a burst waveform delayed by a predetermined time by this delay circuit is input to the comparator.

For example, in the case of the burst signal shown in FIG. 4, when the antenna is switched at time t1, if the reception state of the antenna after the switching is poor, the voltage drops. At this time, although not shown in FIG. 4, the reception level does not decrease instantaneously but gradually decreases with a certain slope.
Therefore, the transition of the reception level immediately after the time t1 has a downward slope. On the other hand, the transition of the reception level before the antenna switching is rising to the right. In this way, the polarity of the waveform changes momentarily before and after the first antenna switching, so that the output of the comparator is also inverted. Then, when the output of the comparator is inverted, the antenna switching control unit 16 determines that the receiving state of the switched antenna is worse, and outputs an antenna switching signal.
Thereby, the antenna switching unit 11 switches the connection antenna.

When making a judgment using such a comparator, it is necessary to set the delay time of the delay circuit very short. That is, it is necessary to set the delay time to such an extent that the inclination of the voltage dropping momentarily by switching the antenna can be detected.

Although the embodiments of the present invention have been described in detail with reference to the drawings, the specific configuration is not limited to the embodiments, and includes a design and the like within a range not departing from the gist of the present invention. It is.

[0028]

As described above, according to the portable communication terminal of the present invention, in the rising period of the smoothed voltage waveform for each reception period, the antenna switching control means performs the first switching control for switching the connection antenna. Performing the second switching control to determine the connection antenna in the reception period based on the smoothed voltage before and after the switching, and to switch the connection antenna to the determined antenna when the determined antenna is different from the current connection antenna. Therefore, communication can always be performed using an antenna whose radio wave condition is good. Thus, stable communication quality can be ensured even for instantaneous received wave fluctuations due to fading or the like. In addition, since the receiving antenna is selected immediately before the received wave, it is possible to reduce the frequency of occurrence of voice interruption during a call due to deterioration of radio quality, and to sharply disturb radio waves such as fading at a high frequency. Can be followed. Further, the error rate can be reduced, and disconnection of the line due to deterioration of the reception state can be avoided. Further, since the receiving circuit is a single system, a configuration at a relatively low cost is possible.

Further, according to the portable communication terminal of the present invention, when the voltage value output from the smoothing means exceeds a predetermined value, the antenna switching control means can perform the first switching.
Since the switching control is performed, the rising period can be detected by a relatively simple circuit, and the above-described connection antenna can be accurately determined in the rising period.

Further, according to the portable communication terminal of the present invention, since the first switching control is performed at a constant period, it is possible to always accurately determine the connection antenna during the rising period. .

Further, according to the portable communication terminal of the present invention, the antenna switching control means compares the smoothed voltage immediately before and after the antenna switching by the first switching control, and determines the antenna having the higher voltage during the reception period. Since the connection antenna is determined as described above, it is possible to easily detect an antenna having a good radio wave condition.

Further, according to the portable communication terminal of the present invention, the antenna switching control means predicts a voltage value after a predetermined time before the antenna switching based on the radio wave voltage output from the smoothing means, and After a lapse of time, the measured value and the predicted value after the antenna switching are compared, and the antenna with the higher voltage is determined as the connected antenna in the reception period. Therefore, the instantaneous voltage values immediately before and immediately after the antenna switching are compared. Even when it is difficult, it is possible to select an antenna with a good radio wave condition. Further, since the predicted value can be obtained by a simple calculation, it is possible to calculate the predicted value in an extremely short time, and it is possible to quickly determine the connection antenna.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a mobile communication terminal according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a burst signal input to an antenna switching control unit.

FIG. 3 is a burst signal for describing an antenna determination process according to the first embodiment of the present invention.

FIG. 4 is a burst signal for explaining antenna determination processing according to the first embodiment of the present invention.

FIG. 5 is a burst signal for describing an antenna determination process according to the second embodiment of the present invention.

FIG. 6 is a diagram illustrating a reception period and a pause period in the TDMA system.

[Explanation of symbols]

11 ... antenna switching unit (antenna switching means), 12 ... L
NA, 13: mixer, 14: intermediate frequency amplifier, 15 ...
DC conversion circuit (smoothing means), 16 antenna switching control section (antenna switching control means), A, B antenna

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5J021 AA02 CA06 DB04 EA04 FA17 FA20 FA26 FA31 GA02 HA05 HA06 HA10 5J047 AA04 AB10 FD01 5K059 CC03 DD02 DD12 DD27 5K067 AA02 BB04 CC04 CC24 KK03

Claims (5)

[Claims] 1. A portable communication terminal having a plurality of antennas and receiving a signal from a radio network at a predetermined interval by any one of the antennas, the connection being connected to an internal circuit of the portable communication terminal. Antenna switching means for switching an antenna, smoothing means for outputting a smoothed voltage obtained by smoothing a radio wave voltage of a received signal, and antenna switching control means for controlling the antenna switching means, In the rising period of the smoothed voltage waveform, the antenna switching control means performs first switching control for switching the connection antenna, and determines and determines the connection antenna in the reception period based on the smoothed voltage before and after switching. If the antenna is different from the current connection antenna, switch the connection antenna to the determined antenna. Mobile communication terminal and performing a second switching control. 2. The method according to claim 1, wherein the antenna switching control unit performs the first switching control when a voltage value output from the smoothing unit exceeds a predetermined value. The mobile communication terminal according to claim 1. 3. The mobile communication terminal according to claim 1, wherein the antenna switching control means performs the first switching control after a predetermined period elapses from the start of the period. 4. The antenna switching control unit compares the smoothed voltage immediately before and immediately after the antenna switching by the first switching control, and determines an antenna having a higher voltage as a connected antenna in the reception period. Claims 1 to 3 characterized by the above-mentioned.
A mobile communication terminal according to claim 1. 5. The antenna switching control unit predicts a voltage value after a predetermined time based on a radio wave voltage output from the smoothing unit before the antenna switching, and after the antenna switching after the predetermined time, 4. The method according to claim 1, further comprising: comparing an actual measurement value with the predicted value and determining an antenna having a higher voltage as a connection antenna in the reception period.
The mobile communication terminal according to any one of the above items.