JP2013255048A - Mobile communication terminal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to commonly use an antenna comprised in a mobile communication device that can communicate using a plurality of frequencies.SOLUTION: A mobile communication terminal 10 is normally in a state in which a first switch 140 connects a first duplexer 130 with a first front-end 110 and a second switch 240 connects a second duplexer 230 with a second front-end 210. If the received electric field strength of a first frequency is stronger than a predetermined first criterion and the first front-end does not perform communication by SIMO using MIMO or MRC, the mobile communication terminal 10 switches to a state in which the first switch 140 connects the second duplexer 230 with the first front-end 110. Moreover, when a second frequency is used and if the received electric field strength of the second frequency is weaker than a predetermined second criterion, it switches to a state in which the second switch 240 connects the first duplexer 130 with the second front-end 210.

Description

  The present invention relates to a mobile communication terminal that uses a plurality of frequencies simultaneously.

  Patent Document 1 discloses a mobile communication terminal that selects an antenna having the best reception quality from among a plurality of antennas, and Patent Documents 2 and 3 illustrate antenna switching operations.

  There is also a mobile communication terminal that performs communication by a plurality of communication methods using a plurality of frequencies. FIG. 1 shows a configuration example of a mobile communication terminal capable of performing communication by MIMO (Multiple Input Multiple Output) using two antennas at the first frequency and capable of communicating with a single antenna at the second frequency. . 1 includes a first front end 110, a second front end 210, a first main antenna 121, a first sub antenna 122, and a second antenna 220. The first front end 110 is a front end for a first frequency capable of MIMO communication. The second front end 210 is a front end for the second frequency. The first main antenna 121 is a main antenna for the first frequency connected to the first front end. The first sub antenna 122 is a sub antenna for the first frequency. The second antenna 220 is a second frequency antenna. Thus, in a mobile communication terminal that performs communication at a plurality of frequencies, an antenna and a front end are provided independently for each frequency.

International Publication No. 2007/080760 Pamphlet JP 2008-42743 A JP 2011-166286 A

  Since the conventional antenna switching techniques such as Patent Documents 1 to 3 are based on the premise of switching with the same frequency communication method, one mobile communication terminal as shown in FIG. 1 supports a plurality of frequencies. Sometimes antennas and switching functions must be provided for each frequency. Therefore, in a mobile communication terminal that supports a plurality of frequencies, a large number of antennas must be mounted in order to be able to select a high-performance antenna. In addition, since the antenna has an appropriate shape and size for each frequency, even if the antenna is forcibly shared between different frequencies, the performance of the antenna for the different frequency is deteriorated and cannot be shared in practice.

  An object of the present invention is to make it possible to practically share an antenna provided in a mobile communication device capable of communicating at a plurality of frequencies.

  The mobile communication terminal of the present invention performs communication at a first frequency and a second frequency that are different in frequency within a range that can be received by the same antenna. The mobile communication terminal of the present invention includes a first front end, a second front end, a first main antenna, a first sub antenna, a second antenna, a first duplexer, a second duplexer, a first switch, and a second switch. The first front end is for a first frequency capable of communication by MIMO (Multiple Input Multiple Output) or SIMC (Single Input Multiple Output) using MRC (maximum ratio combining) (receive diversity using maximum ratio combining). Front end. The second front end is a front end for the second frequency. The first main antenna is a main antenna for the first frequency connected to the first front end. The first sub antenna is a sub antenna for the first frequency. The second antenna is an antenna for the second frequency. The first duplexer is connected to the first sub-antenna and multiplexes and demultiplexes the first frequency and the second frequency. The second duplexer is connected to the second antenna and multiplexes and demultiplexes the first frequency and the second frequency. The first switch selectively connects the first duplexer or the second duplexer to the first front end. The second switch selectively connects the first duplexer or the second duplexer to the second front end. Normally, the first switch connects the first duplexer to the first front end, and the second switch connects the second duplexer to the second front end. When the received electric field strength of the first frequency is stronger than a predetermined first reference and the first front end is not performing communication by MIMO or MIMO using MRC, the first switch connects the second duplexer to the first front. Switch to the state connected to the end. Then, when the communication by SIMO using MIMO or MRC does not start or when the communication by SIMO using MIMO or MRC ends, the first switch returns to a state in which the first duplexer is connected to the first front end. When the second frequency is used and the received electric field strength of the second frequency is weaker than a predetermined second reference, the second switch switches to a state where the first duplexer is connected to the second front end. . When the received electric field strength at the second frequency is equal to or lower than the received electric field strength before the switching of the second switch, the second switch returns to the state in which the second duplexer is connected to the second front end.

  According to the mobile communication terminal of the present invention, antennas are switched under conditions that focus on practical problems, so that antennas for different frequencies can be shared.

The figure which shows the structural example of the mobile communication terminal in which the communication by MIMO using two antennas is possible in the 1st frequency, and communication with a single antenna is possible in the 2nd frequency. The figure which shows the function structural example of the mobile communication terminal of this invention. The figure which shows the control flow for 1st frequencies of Example 1. FIG. The figure which shows the control flow for 2nd frequencies of this invention. The figure which shows the control flow for 1st frequencies of a modification.

  Hereinafter, embodiments of the present invention will be described in detail. In addition, the same number is attached | subjected to the structure part which has the same function, and duplication description is abbreviate | omitted.

  FIG. 2 shows a functional configuration example of the mobile communication terminal of the present invention, FIG. 3 shows a control flow for the first frequency, and FIG. 4 shows a control flow for the second frequency. If the frequencies are different so that they cannot be received by the same antenna, the antenna cannot be shared in the first place. Therefore, the mobile communication terminal 10 communicates at the first frequency and the second frequency, which are different in the frequency range that can be received by the same antenna. It is a mobile communication terminal that is supposed to be performed. For example, the first frequency may be 1.7 GHz, 2 GHz, or 2.6 GHz, and the second frequency may be 2.4 GHz or 2.5 GHz. With such a frequency, UMTS / LTE communication by MIMO (Multiple Input Multiple Output) can be performed at the first frequency, and communication by Bluetooth (registered trademark) or W-LAN can be performed at the second frequency.

  The mobile communication terminal 10 includes a first front end 110, a second front end 210, a first main antenna 121, a first sub antenna 122, a second antenna 220, a first duplexer 130, a second duplexer 230, a first switch 140, A second switch 240 is provided. The first front end 110 is a front end for a first frequency capable of MIMO communication. The second front end 210 is a front end for the second frequency.

  The first main antenna 121 is a main antenna for the first frequency connected to the first front end. The first sub antenna 122 is a sub antenna for the first frequency. The 1 main antenna 121 and the first sub antenna 122 are antennas designed to be optimal at the first frequency. The second antenna 220 is a second frequency antenna. That is, the second antenna 220 is an antenna designed to be optimal at the second frequency. When performing UMTS / LTE communication by MIMO at the first frequency and performing communication such as Bluetooth (registered trademark) or W-LAN at the second frequency, the radio wave condition of the first frequency is deteriorated by human hands. In order to prevent the first main antenna 121 and the first sub-antenna 122 from being separated as much as possible, the first main antenna 121 and the first sub-antenna 122 are separated from the lower part (side closer to the human mouth) and the upper part (person) of the mobile communication terminal 10. In many cases, the second antenna 220 is arranged near the center of the mobile communication terminal 10.

  The first duplexer 130 is connected to the first sub antenna 122 and multiplexes and demultiplexes the first frequency and the second frequency. The second duplexer 230 is connected to the second antenna 220 and multiplexes and demultiplexes the first frequency and the second frequency. The first switch 140 selectively connects the input / output for the first frequency of the first duplexer 130 or the input / output for the first frequency of the second duplexer 230 to the first front end 110. The second switch 240 selectively connects the input / output for the second frequency of the first duplexer 130 or the input / output for the second frequency of the second duplexer 230 to the second front end 210. Normally, the first switch 140 connects the first duplexer 130 to the first front end 110, and the second switch 240 connects the second duplexer 230 to the second front end 210.

  First, the control for the first frequency will be described. When the correlation coefficient between the two antennas is close to 1, even if the reception sensitivity of the antenna is good, communication by MIMO cannot be performed. In this case, since it is the same state as communicating only with the 1st main antenna 121, even if the reception state of the 1st subantenna 122 is good, it is not useful for improvement of a communication speed. Therefore, in such a state, it is better to connect the second antenna 220 having a weak reception electric field strength to the first front end 110 and perform communication by MIMO using the first main antenna 121 and the second antenna 220. The communication speed can be improved. FIG. 3 is a control flow considering this point.

  This control flow will be described with reference to FIG. The control flow starts when the first frequency is used. The mobile communication terminal 10 confirms that the received electric field strength of the first frequency is stronger than a predetermined first reference and that the communication performed by the first front end 110 is not MIMO (S11). If the first standard is stronger than this standard, the received electric field strength that is likely to be used for MIMO communication may be examined and set in advance. Whether or not the MIMO communication is performed may be confirmed by checking whether the RANK Indicator is 1 or 2. RANK Indicator = 1 is not MIMO, and RANK Indicator = 2 is MIMO. If any of the conditions is not satisfied (S11 is No), step S11 is repeated after a predetermined time interval. The “predetermined time” is an interval for repeating the confirmation. If the time is too short, the processing of the mobile communication terminal 10 is added. Therefore, the time may be appropriately designed from the time when the radio wave state is considered to change.

  When step S11 is Yes, the 1st switch 140 switches to the state which connected the input / output for 1st frequencies of the 2nd duplexer 230 to the 1st front end 110 (S12). The mobile communication terminal 10 confirms whether MIMO communication is performed at the first front end 110 after a predetermined time (S13). If MIMO communication is being performed (S13 is Yes), step S13 is repeated after a predetermined time interval. When MIMO communication is not performed (when S13 is No), the first switch 140 returns to a state in which the input / output for the first frequency of the first duplexer 130 is connected to the first front end 110 ( S14). That is, when the MIMO communication does not start or the MIMO communication ends, the first switch 140 returns to the state where the first duplexer 130 is connected to the first front end 110.

  Next, the control for the second frequency will be described. The control flow starts when the second frequency is used. In the case of the second frequency, a human hand covering the second antenna 220 most affects the communication. And when the 2nd antenna 220 is covered by hand, the receiving electric field strength of the 2nd frequency in the 1st subantenna 122 may become stronger. Therefore, the mobile communication terminal 10 confirms whether the received electric field strength of the second frequency is weaker than a predetermined second reference (S21). The second reference is the received electric field strength at the second frequency at the second antenna 220 when the second antenna 220 is covered by hand, and the received electric field strength at the second frequency at the first sub-antenna 122. May be set to a received electric field intensity that may increase the If step S21 is No, step S21 is repeated after a predetermined time interval.

  If step S21 is Yes, the second switch 240 switches to a state where the second frequency input / output of the first duplexer 130 is connected to the second front end 210 (S22). Then, it is confirmed whether the received electric field strength of the second frequency is stronger than the received electric field strength before switching of the second switch 240 (S23). If the received electric field intensity is less than or equal to that before switching (when S23 is No), the second switch 240 returns to the state where the second duplexer 230 is connected to the second front end 210 (S24).

  On the other hand, when the received electric field strength is stronger than before switching (when S23 is Yes), it is confirmed whether a predetermined condition is satisfied after a predetermined time (S25). In the case of Yes, step S25 is repeated after a predetermined time interval. In No, the 2nd switch 240 returns to the state which connects the 2nd duplexer 230 to the 2nd front end 210 (S26). The “predetermined condition” is a condition for maintaining the state where the second switch 240 is switched. For example, “the reception field strength of the second frequency is stronger than the reception field strength before switching of the second switch 240”, “the reception field strength of the second frequency is stronger than a predetermined third reference”, etc. However, it is not necessary to limit to these.

Note that the control flow for the first frequency (FIG. 3) and the control flow for the second frequency (FIG. 4) can be processed independently. Therefore, as a connection state,
(A) State in which the first sub-antenna 122 is connected to the first front end 110 and the second antenna 220 is connected to the second front end 210 (normal state)
(B) State where the second antenna 220 is connected to the first front end 110, and the second antenna 220 is connected to the second front end 210. (C) The first sub-antenna 122 is connected to the first front end 110. A state in which the first sub-antenna 122 is connected to the second front end 210 (D) A state in which the second antenna 220 is connected to the first front end 110 and the first sub-antenna 122 is connected to the second front end 210 There can be four.

  In addition, since the control flow for the first frequency (FIG. 3) and the control flow for the second frequency (FIG. 4) can be processed independently as described above, only one of the functions is installed in the mobile communication terminal. May be. For example, when only the control for the first frequency is mounted, the first duplexer 130 and the second switch 240 are unnecessary, and the first switch 140 is used for the first frequency of the first sub-antenna 122 or the second duplexer 230. Input / output may be selectively connected to the first front end 110.

  In the present invention, conditions that can be improved from the analysis of practical issues regarding the use of antennas for different frequencies, which are unlikely to improve communication speed and received electric field strength, are reflected in the control flow. . Therefore, the mobile communication terminal of the present invention can share antennas for different frequencies.

[Modification]
In the first embodiment, an example in which MIMO communication is performed at the first frequency is shown. However, reception diversity using maximum ratio combining at the first frequency (SIMO (Single Input Multiple Output) using maximum ratio combining (MRC)) is used. The present invention can also be applied to communication, and all the “MIMO” portions shown in the first embodiment may be changed to “SIMO using MRC”.

  More specifically, it is as follows. The first front end 110 is a front end for the first frequency capable of communication by SIMO using MRC. Communication using SIMO using MRC at the first frequency is performed, and communication such as Bluetooth (registered trademark) or W-LAN is performed at the second frequency. Also in this case, the first main antenna 121 and the first sub antenna 122 are used to prevent the radio wave condition of the first frequency from being deteriorated by human hands and to separate the first main antenna 121 and the first sub antenna 122 as much as possible. Are arranged at the lower part (side closer to the human mouth) and the upper part (side closer to the human ear) of the mobile communication terminal 10, and the second antenna 220 is often arranged near the center of the mobile communication terminal 10.

  Similarly to the case of MIMO, if the correlation coefficient of two antennas is close to 1, communication by SIMO using MRC is not possible even if the reception sensitivity of the antenna is good. Therefore, in such a state, the second antenna 220 having a weak reception electric field strength is connected to the first front end 110, and the first main antenna 121 and the second antenna 220 are used to perform communication by SIMO using MRC. Can improve communication speed.

  FIG. 5 is a control flow considering this point. The difference from FIG. 3 is steps S31 and S33. That is, in step S31, the mobile communication terminal 10 confirms that the received electric field strength of the first frequency is stronger than the predetermined first reference, and the communication performed by the first front end 110 is not SIMO using MRC. Confirm (S31). If any of the conditions is not satisfied (S31 is No), step S11 is repeated after a predetermined time interval. When step S31 is Yes, it progresses to step S12.

  In step S33, the mobile communication terminal 10 confirms whether communication using SIMC using MRC is performed in the first front end 110 after a predetermined time (S33). Then, when SIMO communication using MRC is performed (when S33 is Yes), step S33 is repeated after a predetermined time interval. When the communication by SIMO using MRC is not performed (when S33 is No), the process proceeds to step S14.

  The control for the second frequency is the same as in the first embodiment. Some mobile communication terminals 10 can switch between MIMO and SIMO using MRC. In the case of such a mobile communication terminal 10, it is sufficient to have both the function of the first embodiment and the function of the modified example.

  Since the mobile communication terminal of the modification has the above-described configuration, it can share antennas for different frequencies as in the first embodiment.

  The present invention can be used for a mobile communication terminal that communicates using a plurality of frequencies.

10, 90 Mobile communication terminal 110 First front end 121 First main antenna 122 First sub antenna 130 First duplexer 140 First switch 210 Second front end 220 Second antenna 230 Second duplexer 240 Second switch

Claims (3)

A mobile communication terminal for performing communication at a first frequency and a second frequency having different frequencies within a range that can be received by the same antenna,
A first front end for the first frequency capable of communication by SIMO using MIMO or MRC;
A second front end for the second frequency;
A first main antenna for the first frequency connected to the first front end;
A first sub-antenna for the first frequency;
A second antenna for the second frequency;
A first duplexer connected to the first sub-antenna for multiplexing and demultiplexing the first frequency and the second frequency;
A second duplexer connected to the second antenna, for multiplexing and demultiplexing the first frequency and the second frequency;
A first switch for selectively connecting an input / output for a first frequency of the first duplexer or the second duplexer to the first front end;
A second switch for selectively connecting an input / output for a second frequency of the first duplexer or the second duplexer to the second front end;
With
Usually, the first switch connects the first duplexer to the first front end, and the second switch connects the second duplexer to the second front end.
When the received electric field strength of the first frequency is stronger than a predetermined first reference and the first front end is not performing communication by MIMO or MIMO using MRC, the first switch is connected to the second duplexer. Is switched to the state connected to the first front end, and when the communication using SIMO using MIMO or MRC does not start or when the communication using SIMO using MIMO or MRC is completed, the first switch is connected to the first duplexer. To the state of connecting to the first front end,
If the received electric field strength at the second frequency is weaker than a predetermined second reference, the second switch switches the first duplexer to a state connected to the second front end, and the received electric field strength at the second frequency. The mobile communication terminal is configured to return the second switch to a state in which the second duplexer is connected to the second front end when is less than or equal to the received electric field strength before the switching of the second switch. The mobile communication terminal according to claim 1, wherein
The first main antenna and the first sub-antenna are disposed at a lower part and an upper part of the mobile communication terminal;
The mobile communication terminal, wherein the second antenna is arranged near the center of the mobile communication terminal. A mobile communication terminal for performing communication at a first frequency and a second frequency having different frequencies within a range that can be received by the same antenna,
A first front end for the first frequency capable of communication by SIMO using MIMO or MRC;
A second front end for the second frequency;
A first main antenna for the first frequency connected to the first front end;
A first sub-antenna for the first frequency;
A second antenna for the second frequency;
A second duplexer connected to the second antenna, for multiplexing and demultiplexing the first frequency and the second frequency;
A first switch for selectively connecting an input / output for a first frequency of the first sub-antenna or the second duplexer to the first front end;
With
Usually, the first switch connects the first duplexer to the first front end, and the second switch connects the second duplexer to the second front end.
When the received electric field strength of the first frequency is stronger than a predetermined first reference and the first front end is not performing communication by MIMO or MIMO using MRC, the first switch is connected to the second duplexer. Is switched to the state connected to the first front end, and when the communication using SIMO using MIMO or MRC does not start or when the communication using SIMO using MIMO or MRC is completed, the first switch is connected to the first duplexer. The mobile communication terminal is returned to the state of being connected to the first front end.

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