JP2009111963A - Portable terminal, program and method of automatically starting narrow-range high-speed radio communication interface - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a portable terminal, a program and a method, for avoiding periodical starting of a narrow-range high-speed radio communication interface from a viewpoint of power consumption without adopting a special communication method to a conventional communication system. <P>SOLUTION: The portable terminal has a wide-range mobile (cellular) communication interface means for communicating with a base station, and a narrow-range high-speed radio (wireless LAN) communication interface means for communicating with an access point. In addition, a communication quality determining means for determining whether a communication quality value of electric wave, which has been detected by the wide-range mobile communication interface means, decreases under predetermined conditions or not, and a starting controlling means for starting the narrow-range high-speed radio communication interface means and causing the controlling it to sense the access point when the communication quality value decreases under the predetermined conditions. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a portable terminal, a program, and a method for automatically starting a narrow-area high-speed wireless communication interface.

  In recent years, portable terminals compatible with multi-mode mobile radio that can switch communication systems according to the current position have been developed. Such a portable terminal needs to detect the service area of the second communication system to be switched to when communicating with the first communication system.

  A mobile terminal compatible with multi-mode mobile radio can usually communicate with both a wide area mobile communication system and a narrow area high speed radio communication system. As a wide area mobile communication system, there is typically a CDMA (Code Division Multiple Access) type cellular communication system. As a narrow area high speed wireless communication system, there is typically a wireless LAN (Local Area Network) communication system of the IEEE 802.11 standard. Therefore, such a portable terminal has a cellular communication interface and a wireless LAN communication interface.

  At present, the wireless LAN communication area is narrower than the cellular communication area, most of which is limited to indoors. For this reason, the mobile terminal needs to periodically discover (sensing) the access point by activating the wireless LAN communication interface when communicating with the base station using the cellular communication interface (for example, non-patented). Reference 1).

  At this time, there is a technique in which a user who has a portable terminal manually selects a communication mode (see, for example, Non-Patent Document 2). According to this technology, the “mobile phone only” mode and the “mobile phone and wireless LAN” mode can be selected as the communication mode. For example, when going out, the mode is switched to the “mobile phone only” mode, and when the mobile phone is moved to a place where the wireless LAN can be used, such as in the office or indoors, the mode is switched to the “mobile phone and wireless LAN” mode. This eliminates the need for sensing the access point of the wireless LAN in the “mobile phone only” mode, and can reduce the power consumption of the battery of the mobile terminal when going out.

  In addition, there is a technology that adopts an architecture for exchanging area information between a cellular communication system and a wireless LAN communication system to improve the problem of always starting a wireless LAN communication interface (see Non-Patent Document 3, for example).

  Furthermore, there is a technique in which a server accumulates area information for wireless LAN communication (see Non-Patent Document 4, for example). According to this technique, the mobile terminal transmits the current position information to the server. On the other hand, the server determines whether or not the current position of the mobile terminal is covered by the wireless LAN communication area, and returns the determination result to the mobile terminal. The portable terminal activates the wireless LAN communication interface when the current position is covered by the wireless LAN communication area. This eliminates the need to always activate the wireless LAN communication interface.

“KDDI, mobile phone, PHS, wireless LAN automatic switching tool provided free of charge”, bb Watch Impress, [online], [searched on September 19, 2007], Internet <URL: http://bb.watch. impress.co.jp/cda/news/2670.html> "DOCOMO develops FOMA" N900iL "for corporations with wireless LAN", Keitai Impress, [online], [Search September 19, 2007], Internet <URL: http://k-tai.impress.co .jp / cda / article / news_toppage / 19695.html> SuKyoung Lee and Nada Golmie, “Power-EfficientInterface Selection Scheme using Paging of WWAN for WLAN in Heterogeneous Wireless Networks,” IEEE International Conference on Communications (ICC) 2006, Jun. 2006. M. Ylianttila, J. Makela and K. Pahlavan, “Analysis of handoff in a location-aware vertical multi-access network,” ComputerNetworks 47 (2), Feb. 2005.

  The capacity of a battery that can be mounted on a portable terminal is limited. Therefore, according to the technique described in Non-Patent Document 1, the mobile terminal is forced to consume power based on periodic sensing of the access point. Further, if the time interval of sensing timing is increased in order to reduce power consumption, discovery of an access point for wireless LAN communication is delayed.

  Of course, there is a technology in which a power saving mode is installed in a wireless LAN communication interface. However, this technique is effective only after the connection between the mobile terminal and the access point is completed. That is, the access point becomes effective only after the negotiation of “when to transmit a signal indicating the presence / absence of data” is executed for the mobile terminal. Therefore, when the mobile terminal is present in an area other than the wireless LAN communication area, the power saving mode function cannot be applied. In the end, it is necessary to activate the wireless LAN communication interface at a position where it is unknown whether it exists in the wireless LAN communication area and to sense the access point for a certain time for each channel of the wireless LAN. This eventually leads to power consumption of the mobile terminal.

  Further, according to the technique described in Non-Patent Document 2, a user who possesses a portable terminal forces the user to perform a complicated operation in order to manually select a communication mode. Also, wireless LAN communication is not used in a wireless LAN communication area that is not recognized by the user.

  Furthermore, according to the techniques described in Non-Patent Documents 3 and 4, it is necessary to adopt a special communication method between the cellular communication system and the wireless LAN communication system, and the existing network cannot be used as it is. .

  Therefore, the present invention provides a portable terminal, a program, and a method that can avoid the constant activation of the narrow-area high-speed wireless communication interface from the viewpoint of power consumption without adopting a special communication method in the existing communication system. With the goal.

According to the present invention, in a mobile terminal having wide area mobile communication interface means for communicating with a base station and narrow area high speed wireless communication interface means for communicating with an access point,
Communication quality determination means for determining whether or not the communication quality value of radio waves detected by the wide area mobile communication interface means has been attenuated under a predetermined condition;
When the communication quality value is attenuated under a predetermined condition, the narrow band high speed wireless communication interface means is activated, and activation control means for controlling to find an access point is provided.

  According to another embodiment of the portable terminal of the present invention, it is also preferable that the predetermined condition of the communication quality determination means determines whether or not the communication quality value has attenuated to a lower threshold value or less.

  According to another embodiment of the portable terminal of the present invention, the predetermined condition of the communication quality determination means is that the communication quality value is attenuated to an upper threshold value or less, and then the communication quality value is lower than the first predetermined time. It is also preferable to determine whether or not the attenuation is below the threshold.

  According to another embodiment of the portable terminal of the present invention, the predetermined condition of the communication quality determination means is that the communication quality value is attenuated to a lower threshold value or less, and then the communication quality value is lower than the second predetermined time. It is also preferable to determine whether or not the operation has continued in the range from the threshold value to the lowest threshold value.

  According to another embodiment of the portable terminal of the present invention, the predetermined condition of the communication quality determination means is that the communication quality value is attenuated to an upper threshold value or less, and then the communication quality value is lower than the first predetermined time. It is also preferable to determine whether or not the communication quality value continues to fall within a range from the lower threshold value to the lowest threshold value during the second predetermined time after the attenuation to below the threshold value.

According to another embodiment of the mobile terminal of the present invention,
The lower threshold is a communication quality value that is detected when the mobile terminal is located indoors,
The upper threshold is a communication quality value that is detected when the mobile terminal is located outdoors,
The lowest threshold is a minimum communication quality value at which the mobile terminal can communicate with the base station, and / or
The range from the lower threshold value to the lowest threshold value is preferably a communication quality value that is detected when the portable terminal is located indoors.

  According to another embodiment of the portable terminal of the present invention, it is also preferable that the predetermined condition of the communication quality determination means determines whether or not the communication quality value has attenuated by a predetermined deterioration value or more within a third predetermined time. .

  According to another embodiment of the portable terminal of the present invention, the predetermined condition of the communication quality determination means is that the communication quality value is attenuated by a predetermined deterioration value or more within the third predetermined time, and then the communication quality value is It is also preferable to determine whether or not it has continued within a predetermined fluctuation range for a predetermined time of 2.

According to another embodiment of the mobile terminal of the present invention,
The predetermined deterioration value is a difference in communication quality value to the extent that the mobile terminal is detected when entering the indoor from the outside, and / or
The predetermined fluctuation range is preferably a communication quality value that is detected when the mobile terminal is located indoors.

  According to another embodiment of the portable terminal of the present invention, it is also preferable that the wide area mobile communication interface means is for cellular communication, and the narrow area high speed wireless communication interface means is for a wireless LAN (Local Area Network).

According to another embodiment of the mobile terminal of the present invention,
It further has an activation hold timer means for measuring the activation hold time of the narrow area high speed wireless communication interface means,
The activation control means instructs the activation suspension timer means to start measuring the activation suspension time when the activated narrow area high speed wireless communication interface means cannot find the access point, and as long as the activation suspension time is in progress, It is also preferable to control the narrow area high speed wireless communication interface to stop.

  According to another embodiment of the portable terminal of the present invention, when the activated narrow-area high-speed wireless communication interface means discovers an access point, the narrow-area high-speed wireless communication interface means communicates with the base station by the wide-area mobile communication interface means. It is also preferable to further have a handover control means for handing over to a state of communicating with the access point by the area high-speed wireless communication interface means.

According to the present invention, in a program for functioning a computer mounted on a portable terminal having wide area mobile communication interface means for communicating with a base station and narrow area high speed wireless communication interface means for communicating with an access point,
Communication quality determination means for determining whether or not the communication quality value of radio waves detected by the wide area mobile communication interface means has been attenuated under a predetermined condition;
When the communication quality value is attenuated under a predetermined condition, the narrow area high-speed wireless communication interface means is activated, and the computer is caused to function as an activation control means for controlling to find an access point.

According to the present invention, in a communication system switching method in a portable terminal having wide area mobile communication interface means for communicating with a base station and narrow area high speed wireless communication interface means for communicating with an access point,
A first step of determining whether or not the communication quality value of the radio wave detected by the wide area mobile communication interface means is attenuated under a predetermined condition;
And a second step of starting the narrow-area high-speed wireless communication interface means and finding an access point when the communication quality value is attenuated under a predetermined condition.

  According to the mobile terminal, the program, and the method of the present invention, since control is performed only on the mobile terminal, it is not necessary to adopt a special communication method for the existing communication system. In addition, since the constant activation of the narrow-area high-speed wireless communication interface can be avoided, low power consumption can be realized for a portable terminal having a limited battery capacity.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a system configuration diagram showing movement of a portable terminal in the present invention.

  According to FIG. 1, a mobile terminal 1 possessed by a user has a cellular communication interface unit that communicates with a base station 3 connected to a mobile phone network 7 and a wireless LAN communication interface unit that communicates with an access point 4. . The cellular communication is, for example, a CDMA system, and the wireless LAN communication is, for example, IEEE 802.11.

  The portable terminal 1 can communicate with the cellular base station 3 outdoors, and can communicate with the access point 4 for wireless LAN indoors. An access point 4 installed indoors is connected to the Internet 6 via a home gateway 5. The counterpart communication device 8 can communicate with the mobile terminal 1 through the base station 3 connected to the mobile phone network 7 or through the access point 4 connected to the Internet 6.

  According to FIG. 1, the user who has the portable terminal 1 is going to move indoors from the outdoors. At present, wireless LAN communication areas are mainly indoors such as airports, restaurants, hotels, companies, and homes. If it can be detected that the mobile terminal 1 has entered the room itself, it is effective to activate the wireless LAN communication interface at that time. Conversely, when outdoors, the wireless LAN communication interface can be stopped (power off or sleep mode). Thus, when the mobile terminal is located outdoors, it is possible to prevent useless power consumption without sensing an access point.

  Cellular communication is generally affected by radio wave attenuation caused by obstruction between the base station and the mobile terminal. At this time, the mobile terminal can detect the attenuation of the reception quality of the radio wave from the base station. That is, when the mobile terminal enters the indoor area, the penetration rate of radio waves from the base station received by the mobile terminal decreases due to the indoor outer wall or the like.

  According to the present invention, when detecting a decrease in the penetration rate of radio waves from the base station, the mobile terminal estimates that the mobile terminal has moved indoors, activates the wireless LAN communication interface, and starts sensing the access point. That is, according to the present invention, whether or not the wireless LAN communication interface is activated is determined based on the communication quality value of the radio wave of cellular communication observed by the mobile terminal.

  FIG. 2 is a functional configuration diagram of the mobile terminal according to the present invention.

  According to FIG. 2, the mobile terminal 1 includes a cellular communication interface unit 101, a wireless LAN communication interface unit 102, a handover control unit 103, a communication quality determination unit 104, an activation control unit 105, and an activation hold timer unit 106. And have. The handover control unit 103, the communication quality determination unit 104, the activation control unit 105, and the activation hold timer unit 106 can be realized by executing a program that causes a computer installed in the mobile terminal 1 to function. Further, this is realized as a communication system switching method in which the activation control unit 105 operates after the determination by the communication quality determination unit 104.

The communication quality determination unit 104 determines whether the radio wave communication quality value detected by the cellular communication interface unit 101 satisfies the following conditions. This determination result is notified to the activation control unit 105. Whether to notify the activation control unit 105 of the determination result when any of the conditions is satisfied is based on the setting of the user or the communication carrier.
(Condition 1) The communication quality value is attenuated below the lower threshold THlow. (Condition 2) The communication quality value is attenuated below the upper threshold THhigh, and then the communication quality value is lower than the first predetermined time T1. Decrease below the threshold THlow (Condition 3) The communication quality value attenuates below the lower threshold THlow, and then the communication quality value decreases from the lower threshold THlow to the lowest threshold THlow-min for the second predetermined time T2. (Condition 4) The communication quality value decays below the upper threshold THhigh, and then the communication quality value decays below the lower threshold THlow within the first predetermined time T1, and then the communication quality The value continues in the range from the lower threshold THlow to the lowest threshold THlow-min during the second predetermined time T2. (Condition 5) The communication quality value falls within a predetermined deterioration value D within the third predetermined time T3. (Condition 6) Communication quality value is third Within the predetermined time T3, attenuated more than a predetermined degradation value D, then the communication quality value, during a second predetermined time T2, and continued at a range of the predetermined variation width R

Lower threshold: Communication quality value that is detected when the mobile terminal is located indoors Upper threshold: Communication quality value that is detected when the mobile terminal is located outdoors Lower threshold: The mobile terminal is Minimum communication quality value that can be communicated with the base station Range from lower threshold to lower threshold:
Communication quality value that is detected when the mobile terminal is located indoors Predetermined degradation value: a level that is detected when the mobile terminal enters the indoor from the outdoors
Difference in communication quality value Predetermined fluctuation range: Communication quality value that is detected when the mobile terminal is located indoors

  The activation control unit 105 activates the wireless LAN communication interface unit 102 when the determination result is notified from the communication quality determination unit 104.

  FIG. 3 is a graph showing the activation timing of the wireless LAN communication interface when the mobile terminal moves from the outdoor to the indoor under conditions 1 to 4. In this graph (including FIG. 4 described later), the vertical axis represents C / I (signal to noise ratio) values, and the horizontal axis represents elapsed time (seconds).

  The change in the communication quality value of the cellular communication in FIG. 3 is specifically a measurement result when a pedestrian holding the mobile terminal enters the door indoors and proceeds through the corridor in the back. As is apparent from the graph, the C / I value is greatly attenuated as soon as the portable terminal enters the room. Thereafter, the C / I value lower than the lower threshold THlow continues.

As the communication quality value of cellular communication, the following values can be used in addition to the C / I value. Of course, these values may be unweighted or weighted moving average values, or a combination of these values.
(1) Received power RxPower
(2) Received signal strength (RSS)
(3) Signal to Interference Ratio (SINR)
(4) Ec / Io (pilot received power / total received power (RSSI))
(5) Packet loss rate (PER)
(6) Frame loss rate FER (Frame Error Rate)

(Condition 1: Control 1) When the communication quality value satisfies Condition 1, the wireless LAN communication interface unit 102 is activated. When the communication quality value of the cellular communication radio wave observed by the mobile terminal is attenuated to the same extent as the indoor communication quality value, it is assumed that the mobile terminal has entered the indoor area, and the wireless LAN communication interface unit 102 is activated, and the access point Start discovery.

(Condition 2: Control 2) When the communication quality value satisfies the condition 2, the wireless LAN communication interface unit 102 is activated. Usually, for example, when a pedestrian enters indoors from outside, the communication quality value of the radio wave of cellular communication observed by the mobile terminal is attenuated at a stretch within a relatively short time. Therefore, when the mobile terminal is attenuated to the same extent as the communication quality value that has entered the indoor from the outside within the relatively short time, it is estimated that the mobile terminal has entered the indoor, and the wireless LAN communication interface unit 102 is activated, Begin discovery of access points. Expressed as the slope of the attenuation of the communication quality value over time.

(Condition 3: Control 3) When the communication quality value satisfies Condition 3, the wireless LAN communication interface unit 102 is activated. Even when the portable terminal is in the indoor state, the portable terminal receives a radio wave of cellular communication having a relatively low communication quality. Accordingly, when the communication quality value of the degree that the portable terminal has entered the indoor from the outside continues for the second predetermined time T2, it is estimated that the portable terminal has entered the indoor, the wireless LAN communication interface unit 102 is activated, and the access point Start discovery.

(Condition 4: Control 4) When the communication quality value satisfies the condition 4, the wireless LAN communication interface unit 102 is activated. This is a combination of condition 2 and condition 3.

  FIG. 4 is a graph showing the activation timing of the wireless LAN communication interface when the mobile terminal moves indoors from outdoors under conditions 5 and 6.

(Condition 5: Control 5) When the communication quality value satisfies the condition 5, the wireless LAN communication interface unit 102 is activated.
Communication quality value at the current time T _now : Q (T _now )
T _now −T3 ≦ t ≦ T _now
max (Q (t)) − Q (T _now ) ≧ predetermined deterioration value D
When the condition is satisfied, the wireless LAN communication interface unit 102 is activated. max represents the maximum value. max (Q (t)) represents the maximum communication quality value in the time range from the past time point T3 to the current time T _now .

Usually, for example, when a pedestrian enters indoors from outside, the communication quality value of the radio wave of cellular communication observed by the mobile terminal is attenuated at a stretch within a relatively short time. Therefore, when an attenuation amount equivalent to the communication quality deterioration value of the portable terminal entering the indoor from the outside is observed within the relatively short time, the wireless LAN communication interface unit 102 is started and discovery of an access point is started. This is expressed as a slope of attenuation of the communication quality value with time. The portable terminal stores the communication quality value from the past time point to the current time T _{now for} T3 time, and compares it with the previously stored communication quality value each time the communication quality value at the current time is acquired.

(Condition 6: Control 6) When the communication quality value satisfies the condition 6, the wireless LAN communication interface unit 102 is activated. Even when the portable terminal is in the indoor state, the portable terminal receives a radio wave of cellular communication having a relatively low communication quality. Accordingly, when the communication quality value of the degree that the portable terminal has entered the indoor from the outside continues for the second predetermined time T2, it is estimated that the portable terminal has entered the indoor, the wireless LAN communication interface unit 102 is activated, and the access point Start discovery.

  According to FIG. 4, the fluctuation range R is represented in the direction of deterioration from the communication quality value at the start of counting at the predetermined time T2. For example, the fluctuation range R may be set in the vertical direction with the communication quality value at the start of counting as the center (or by shifting the center).

Of course, even if the condition 6 is satisfied, the wireless LAN interface unit 102 is activated if the communication quality value is too bad at the deterioration start point (T _now −T3), which is the starting point at which the predetermined deterioration D is observed. You can also avoid it. That is, the communication quality value at the start of deterioration must satisfy the deterioration start upper threshold.

  FIG. 5 is a graph showing a change in the cellular communication quality value when the mobile terminal goes out of line of sight with the base station.

  According to FIG. 5, when the mobile terminal enters an out-of-line view that is behind the building as seen from the base station, the quality of cellular communication is temporarily deteriorated. However, due to the influence of multipath that changes every moment, the communication quality value subsequently changes to be higher than the lower threshold THlow or to approach zero. On the other hand, as shown in FIG. 3 or FIG. 4, when the portable terminal enters indoors, radio waves for cellular communication are not completely received, but are received with a low communication quality value. Conditions 3, 4, and 6 described above use such a difference in characteristics.

  That is, when the communication quality of cellular communication improves to the lower threshold THlow or more before the second predetermined time T2 elapses (conditions 3 and 4), or when the communication quality improves beyond the fluctuation range R (condition 6). ), The wireless LAN communication interface unit 102 is not activated. On the contrary, the radio wave of the cellular communication is continued for the second predetermined time T2 within the range of the low communication quality value (between the lower threshold THlow and the lowest threshold THlow-min) or the fluctuation range R. If the wireless LAN communication interface unit 102 is received, the wireless LAN communication interface unit 102 is activated.

  The activation suspension timer unit 106 measures the activation suspension time of the wireless LAN communication interface unit 102.

  When the activated wireless LAN communication interface unit 102 cannot find an access point, the activation control unit 105 instructs the activation suspension timer unit 106 to start measuring the activation suspension time. The activation control unit 105 controls the wireless LAN communication interface unit 102 to be stopped as long as the activation suspension time is in progress.

  When the activated wireless LAN communication interface unit 102 discovers an access point, the handover control unit 103 communicates with the base station 3 through the cellular communication interface unit 101, and the wireless LAN communication interface unit 102 uses the access point. 4 to control the handover to a state of communicating with

  As described above in detail, according to the mobile terminal, the program, and the method of the present invention, since control is performed only on the mobile terminal, it is not necessary to employ a special communication method in the existing communication system. In addition, since the constant activation of the narrow-area high-speed wireless communication interface can be avoided, low power consumption can be realized for a portable terminal having a limited battery capacity.

  In addition, according to the technique described in Non-Patent Document 1, it is provided with a function of switching to cellular communication when the radio wave intensity of wireless LAN communication is equal to or less than a predetermined threshold (immediately before communication is disabled). This is a technique for solving the problem that communication is interrupted by exiting the wireless LAN communication area during communication using wireless LAN communication. That is, the handover itself from wireless LAN communication to cellular communication is described. Since cellular communication is basically communicable in most areas, it is possible to immediately switch from wireless LAN communication to cellular communication by handover as described above.

  On the other hand, the present invention is characterized by an access point sensing start timing that is a stage before handover from cellular communication to wireless LAN communication. In other words, simply applying the handover technique from wireless LAN communication to cellular communication described in Non-Patent Document 2 does not mean that the present invention can be conceived.

  According to the various embodiments of the present invention described above, those skilled in the art can easily make various changes, modifications and omissions within the scope of the technical idea and the viewpoint of the present invention. The above description is merely an example, and is not intended to be restrictive. The invention is limited only as defined in the following claims and the equivalents thereto.

It is a system configuration figure showing movement of a portable terminal in the present invention. It is a functional block diagram of the portable terminal in this invention. It is a graph showing the starting timing of the wireless LAN communication interface when the mobile terminal moves indoors from outdoors for Conditions 1 to 4. 6 is a graph showing the activation timing of the wireless LAN communication interface when the mobile terminal moves indoors from outdoors with respect to conditions 5 and 6. It is a graph showing the change of the communication quality value of a cellular when a portable terminal goes out of sight with a base station.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Mobile terminal 101 Cellular communication interface part, Wide area mobile communication interface part 102 Wireless LAN communication interface part, Narrow area high speed wireless communication interface part 103 Handover control part 104 Communication quality judgment part 105 Start control part 106 Start hold timer part 2 Building 3 Base Station 4 Access point 5 Home gateway 6 Internet 7 Mobile phone network 8

Claims (14)

In a mobile terminal having wide area mobile communication interface means for communicating with a base station and narrow area high speed wireless communication interface means for communicating with an access point,
Communication quality determination means for determining whether or not the communication quality value of the radio wave detected by the wide area mobile communication interface means is attenuated under a predetermined condition;
A portable terminal comprising activation control means for activating the narrow-area high-speed wireless communication interface means and controlling the discovery of the access point when the communication quality value is attenuated under the predetermined condition.   The mobile terminal according to claim 1, wherein the predetermined condition of the communication quality determination unit determines whether or not the communication quality value is attenuated to a lower threshold value or less.   The predetermined condition of the communication quality determination means determines whether the communication quality value is attenuated to an upper threshold value or less and then the communication quality value is attenuated to a lower threshold value or less within a first predetermined time. The mobile terminal according to claim 1, wherein:   The predetermined condition of the communication quality determination means is that the communication quality value is attenuated to a lower threshold value or less, and then the communication quality value is within a range from the lower threshold value to the lowest threshold value for a second predetermined time. The mobile terminal according to claim 1, wherein it is determined whether or not it has continued.   The predetermined condition of the communication quality determination means is that the communication quality value attenuates to an upper threshold value or less, and then the communication quality value attenuates to a lower threshold value or less within a first predetermined time, and then the communication The portable terminal according to claim 1, wherein it is determined whether or not the quality value continues in a range from the lower threshold value to the lowest threshold value for a second predetermined time. The lower threshold is a communication quality value that is detected when the mobile terminal is located indoors,
The upper threshold is a communication quality value that is detected when the mobile terminal is located outdoors,
The lowest threshold is a minimum communication quality value at which the mobile terminal can communicate with the base station, and / or
6. The communication quality value according to claim 2, wherein the range from the lower threshold value to the lowest threshold value is a communication quality value that is detected when the mobile terminal is located indoors. Mobile devices.   2. The mobile terminal according to claim 1, wherein the predetermined condition of the communication quality determination unit determines whether or not the communication quality value is attenuated by a predetermined deterioration value or more within a third predetermined time. .   The predetermined condition of the communication quality determination means is that the communication quality value is attenuated by a predetermined deterioration value or more within a third predetermined time, and then the communication quality value is changed for a second predetermined time. The mobile terminal according to claim 1, wherein it is determined whether or not it has continued within a range of width. The predetermined deterioration value is a difference in communication quality values to the extent that the mobile terminal is detected when entering the indoor from the outside, and / or
The portable terminal according to claim 7 or 8, wherein the predetermined fluctuation range is a communication quality value that is detected when the portable terminal is located indoors. 10. The wide area mobile communication interface means is for cellular communication, and the narrow area high speed wireless communication interface means is for a wireless local area network (LAN). The portable terminal described. Further comprising an activation hold timer means for measuring the activation hold time of the narrow area high speed wireless communication interface means,
The activation control means instructs the activation suspension timer means to start measuring the activation suspension time when the activated narrow area high speed wireless communication interface means cannot find the access point, and the activation suspension time advances. The mobile terminal according to any one of claims 1 to 10, wherein the mobile terminal is controlled to stop the narrow-area high-speed wireless communication interface as long as the mobile terminal is connected.   When the activated narrow-area high-speed wireless communication interface means discovers the access point, the access is made by the narrow-area high-speed wireless communication interface means from the state in which the narrow-area high-speed wireless communication interface means communicates with the base station by the wide-area mobile communication interface means. The mobile terminal according to claim 1, further comprising a handover control unit that performs handover to a state in which communication is performed with a point. In a program for functioning a computer mounted on a portable terminal having wide area mobile communication interface means for communicating with a base station and narrow area high speed wireless communication interface means for communicating with an access point,
Communication quality determination means for determining whether or not the communication quality value of the radio wave detected by the wide area mobile communication interface means is attenuated under a predetermined condition;
When the communication quality value is attenuated under the predetermined condition, the narrow band high-speed wireless communication interface unit is activated, and the computer is caused to function as an activation control unit that performs control so as to find the access point. A program for terminals. In a communication system switching method in a portable terminal having wide area mobile communication interface means for communicating with a base station and narrow area high speed wireless communication interface means for communicating with an access point,
A first step of determining whether or not a communication quality value of radio waves detected by the wide area mobile communication interface means has been attenuated under a predetermined condition;
And a second step of activating the narrow-area high-speed wireless communication interface means to detect the access point when the communication quality value is attenuated under the predetermined condition. Communication system switching method.

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