JP2004260690A - Mobile communication system, mobile communication terminal and switching control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mobile communication system capable of efficiently performing handover, a mobile communication terminal used for the same and a handover control method. <P>SOLUTION: The mobile communication terminal 10 is connected with a base station 20 via a radio communication line and performs communication by switching the base station 20 to be a connection partner and is provided with a positional information detection means 15 for detecting a position of the mobile communication terminal 10, a radio wave state measurement means for measuring the radio wave state of the base station 20 and a storage means 14 for storing the positional information detected by the positional information detection means 15 and the measured radio wave state of the base station 20 corresponding to the positional information. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a mobile communication terminal, and more particularly, to a mobile communication system capable of performing handover efficiently, a mobile communication terminal used therefor, and a handover control method.
[0002]
[Prior art]
In a mobile communication system, a base station is installed such that cells (service areas communicable from a base station) are adjacent to each other, and a mobile communication terminal sets a wireless communication line with any of the base stations, Perform communication. Then, when the mobile communication terminal moves, a base station to be a communication partner is selected, a wireless communication line is re-established with the base station constituting the cell to which the mobile communication terminal belongs, and the mobile communication terminal moves. However, communication can be performed without interruption. The process of selecting the base station and switching the wireless communication line is called handover.
[0003]
In order to select a base station suitable for this handover, receiving means for receiving the position information of the wireless device, position calculating means for processing and detecting the position information received by the receiving means, the position calculating means and the position calculating means A position information storage unit connected to the control unit and having map information of the road on which the vehicle travels, and storing an arbitrary position on the map information; and detecting that the vehicle has reached the stored position during a call. A means for connecting to an adjacent base station and continuing the call, storing a predetermined point, and switching a communication channel at the point.
[0004]
[Patent Document 1]
JP-A-10-341470
[0005]
[Problems to be solved by the invention]
However, in the above-described conventional mobile radio, a plurality of handover points need to be set on a map in advance, so that a large amount of map data information is required. Furthermore, even if a handover point is set on a map, it is difficult to set an accurate handover point because the actual radio wave condition is affected by the terrain, buildings, and the like.
[0006]
In order to solve the above-mentioned problem, the present applicant has filed an application in Japanese Patent Application No. 2003-13654 for predicting a point at which a handover is to be performed by using map information and a GPS device. Similarly, a large amount of map data was required.
[0007]
The present invention has been made in view of the above problems, obtains position information by GPS, stores the radio wave state of the base station in the position information, and performs an accurate handover based on the stored radio wave condition. It is an object of the present invention to provide a mobile communication system for performing the above.
[0008]
[Means for Solving the Problems]
A first invention is a mobile communication terminal which is connected to a base station via a wireless communication line and performs communication by switching a base station to be connected to, and a position information detecting means for detecting a position of the mobile communication terminal. A radio wave condition measuring means for measuring the radio wave condition of the base station, and storage means for storing the position information detected by the position information detecting means and the measured radio wave condition of the base station corresponding to the position information, It is characterized by having.
[0009]
According to a second invention, in the first invention, an averaging means for obtaining an average of the radio wave condition of the base station is provided, and the storage means stores the averaged radio wave condition.
[0010]
In a third aspect based on the first aspect, there is provided an averaging means for calculating a weighted average of the radio condition of the base station using the number of times of measurement of the radio condition of the base station, and the storage means comprises: And storing the measured number of times of the radio wave state and the radio wave state of the base station.
[0011]
In a fourth aspect based on the first to third aspects, the base station to be connected to is switched using the radio wave state stored in the storage unit based on the current position information detected by the position detection unit. Is controlled.
[0012]
A fifth invention is based on the fourth invention, further comprising a storage determination unit that determines whether a radio wave state corresponding to current position information detected by the position detection unit is stored in the storage unit, When the storage determining unit determines that the radio wave state corresponding to the current position information is stored in the storage unit, the base station serving as a connection partner is determined using the radio wave state stored in the storage unit. Select and transmit a connection request with the base station, and when the storage determining means determines that the radio wave state corresponding to the current position information is not stored in the storage means, By selecting a base station to be connected with using the radio wave state of the base station and transmitting a connection request with the base station, switching of the base station to be connected is controlled.
[0013]
In a sixth aspect based on the fifth aspect, the storage means is stored in the storage means based on a comparison result between a radio wave state with the base station measured by the radio wave state measurement means and a predetermined value. It is characterized in that it is determined whether or not to select a base station to be connected using the radio wave state obtained.
[0014]
A seventh invention is based on the fourth invention, further comprising a storage determination unit that determines whether a radio wave state corresponding to current position information detected by the position detection unit is stored in the storage unit, When the storage determining unit determines that the radio wave state corresponding to the current position information is stored in the storage unit, the radio wave state stored in the storage unit is transmitted to the base station. When the determination unit determines that the radio wave state corresponding to the current position information is not stored in the storage unit, the measured radio wave state of the base station is transmitted to the base station, and the connection partner is determined. Switching of the base station to be performed is controlled.
[0015]
In an eighth aspect based on the seventh aspect, the radio wave state stored in the storage means is based on a comparison result between a radio wave state with the base station measured by the radio wave state measuring means and a predetermined value. It is characterized in that it is determined whether or not the transmitted radio wave state is transmitted to the base station.
[0016]
A ninth invention comprises a mobile communication terminal and a base station connected to the mobile communication terminal via a wireless communication line, and the mobile communication terminal performs communication by switching a base station to be connected to. In the mobile communication system, the mobile communication terminal includes a position information detecting unit that detects a position of the mobile communication terminal, a radio wave state measuring unit that measures a radio wave state of the base station, and a position detected by the position information detecting unit. Storage means for storing information and the measured radio wave state with the base station corresponding to the position information, and stored in the storage means based on the current position information detected by the position detection means. The base station serving as a connection partner of the mobile communication terminal is switched using the received radio wave state.
[0017]
A tenth invention is characterized in that, in the ninth invention, averaging means for obtaining an average of the radio wave condition of the base station is provided, and the storage means stores the averaged radio wave condition.
[0018]
In an eleventh aspect based on the ninth aspect, the ninth aspect further comprises averaging means for obtaining a weighted average of the radio condition of the base station using the number of times of measurement of the radio condition of the base station, And storing the measured number of times of the radio wave state and the radio wave state of the base station.
[0019]
In a twelfth aspect based on the ninth to eleventh aspects, the mobile communication terminal determines whether or not a radio wave state corresponding to the current position information detected by the position detection means is stored in the storage means. When it is determined that the radio wave condition corresponding to the current position information is stored in the storage device, the radio wave condition stored in the storage device is used. Select a base station to be connected to, transmit a connection request with the base station, and determine by the storage determination means that the radio wave state corresponding to the current position information is not stored in the storage means. In this case, the base station to be connected is selected using the measured radio wave state of the base station, a connection request with the base station is transmitted, and the base station is transmitted from the mobile communication terminal. Connection required Based on, and controls the switching of the base station.
[0020]
In a thirteenth aspect based on the twelfth aspect, the mobile communication terminal is characterized in that, based on a comparison result between a radio wave state with the base station measured by the radio wave state measuring means and a predetermined value, It is characterized in that it is determined whether or not to select a base station to be connected with using the radio wave state stored in the storage means.
[0021]
In a fourteenth aspect based on the ninth to eleventh aspects, the mobile communication terminal determines whether or not a radio wave state corresponding to the current position information detected by the position detection means is stored in the storage means. When it is determined that the radio wave state corresponding to the current position information is stored in the storage means, the radio wave state stored in the storage means is changed to the Transmitting the measured radio wave condition of the base station to the base station when the storage determining device determines that the radio wave condition corresponding to the current position information is not stored in the storage device. And the base station selects a base station to be connected to the mobile communication terminal based on the radio wave condition of the base station transmitted from the mobile communication terminal, and controls switching of the base station. And wherein the door.
[0022]
In a fifteenth aspect based on the fourteenth aspect, the radio wave condition stored in the storage device is based on a comparison result between a radio wave condition with the base station measured by the radio wave condition measuring device and a predetermined value. It is characterized in that it is determined whether or not the transmitted radio wave state is transmitted to the base station.
[0023]
According to a sixteenth aspect, in a mobile communication system including a mobile communication terminal and a base station connected to the mobile communication terminal via a wireless communication line, a base station serving as a connection partner of the mobile communication terminal is provided. A switching control method, comprising detecting a position of the mobile communication terminal, measuring a radio wave state with the base station, and detecting the detected position information and the measured base station corresponding to the position information. The radio wave condition is stored, and the base station to be connected to the mobile communication terminal is switched using the radio wave condition read out based on the detected current position information.
[0024]
According to a seventeenth aspect based on the sixteenth aspect, an average is obtained for the radio wave condition of the base station, and the averaged radio wave condition is stored.
[0025]
In an eighteenth aspect based on the sixteenth aspect, a weighted average is obtained for the radio condition of the base station using the number of times of measurement of the radio condition of the base station, and the averaged radio condition and the radio wave of the base station are obtained. The number of times of state measurement is stored.
[0026]
In a nineteenth aspect based on the sixteenth aspect, the mobile communication terminal determines whether or not a radio wave state corresponding to the detected current position information is stored, and If it is determined that the received radio wave state is stored, a base station to be connected is selected using the stored radio wave state, a request for connection with the base station is transmitted, and the current position information is transmitted. If it is determined that the radio wave state corresponding to is not stored, the base station to be connected is selected using the measured radio wave state of the base station, and a connection request with the base station is transmitted. And the base station controls switching of the base station based on a connection request transmitted from the mobile communication terminal.
[0027]
In a twentieth aspect based on the nineteenth aspect, the mobile communication terminal is characterized in that the radio wave condition read out based on a comparison result between the measured radio wave condition with the base station and a predetermined value. Is used to determine whether or not to select a base station to be a connection partner.
[0028]
In a twenty-first aspect based on the sixteenth to eighteenth aspects, the mobile communication terminal determines whether or not a radio wave state corresponding to the detected current position information is stored, and the mobile communication terminal responds to the current position information. When it is determined that the radio wave state to be stored is stored, the stored radio wave state is transmitted to the base station, and when it is determined that the radio wave state corresponding to the current position information is not stored, The measured radio wave condition of the base station is transmitted to the base station, and the base station is a base station to which the mobile communication terminal is connected based on the radio wave condition of the base station transmitted from the mobile communication terminal. Is selected to control the switching of the base station.
[0029]
In a twenty-second aspect based on the twenty-first aspect, the stored radio wave state is transmitted to the base station based on a result of comparison between the measured radio wave state with the base station and a predetermined value. It is characterized by determining whether or not to transmit.
[0030]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings.
[0031]
FIG. 1 is a block diagram showing the configuration of the mobile communication system according to the first embodiment of the present invention.
[0032]
A mobile communication terminal 10 is connected to a plurality of base stations (20A, 20B, 20C) via an antenna 11 by wireless communication. The base stations 20 are connected to each other by a public network or a dedicated line. The mobile communication terminal 10 includes an antenna 11, a radio unit 12, a control unit 13, a storage unit 14, a GPS unit 15, a GPS antenna 16, an operation / display unit 17, and the like.
[0033]
The radio unit 12 includes a transmission / reception unit, an RF control unit, and the like. The radio unit 12 monitors the state of radio waves (for example, electric field strength (RSSI) and line quality information (CIR)) from the base station 20, and And transmits a radio wave to the base station 20. The transmission / reception unit includes a transmission unit and a reception unit. The transmission unit generates a high-frequency signal transmitted from the antenna 11, and the reception unit amplifies the high-frequency signal received by the antenna 11, performs frequency conversion, and the like, and generates a baseband signal. Output to RF control unit. The RF control unit includes a baseband unit and a radio control unit, and the baseband unit demodulates the baseband signal into an audio signal using a codec unit in the baseband unit. The codec modulates the audio signal to generate a baseband signal. Further, the wireless control unit controls the frequency transmitted and received by the transmitting and receiving unit, the transmission and reception timing, and the output of the radio wave to be transmitted.
[0034]
Further, the control unit 13 is mainly configured by a CPU, and based on data stored in a storage unit (RAM and ROM) 14, a portable unit such as a wireless unit 12, a GPS unit 15, an operation unit / display unit 17, and the like. Control each part of the telephone.
[0035]
The GPS unit 15 receives radio waves from GPS satellites via the GPS antenna 16, measures the position (latitude and longitude) of the own device, and acquires position information.
[0036]
The operation unit / display unit 17 accepts input of characters and numbers from the user and instructions for operation to the mobile phone, and also receives text information, image information, operation states (radio wave intensity, (Remaining battery power, time) and the like are displayed.
[0037]
Further, the mobile communication terminal 10 has a transmitting unit (not shown) for converting an acoustic signal into an electric signal and a receiving unit (not shown) for converting an electric signal into an acoustic signal.
[0038]
Next, the operation of the first embodiment of the present invention configured as described above will be described.
[0039]
The first embodiment is applicable to, for example, an MAHO (Mobile Assisted Hand Over) system that performs handover under the initiative of a mobile communication terminal, which is employed in a PDC system or the like. The storage unit 14 periodically stores the position information measured by the GPS unit 15 of the mobile communication terminal 10 and the electric field strength from the base station 20 in the position information. Then, it is checked whether or not the current position information measured by the GPS unit 15 matches any of the position information already stored in the storage unit 14. The electric field strength information of the corresponding base station 20 is read, and it is determined whether to perform a handover based on the read electric field strength information of the base station.
[0040]
Furthermore, when the electric field strength of the base station 20 corresponding to the same position information is acquired a plurality of times, the information to be stored in the storage unit 14 is calculated and stored as an average value of each. By using the average electric field intensity value in this way, information on the electric field intensity of the base station 20 measured at the same point is accumulated, and more accurate handover control can be performed by the learning effect.
[0041]
For example, the current position information measured by the GPS unit 15 is already stored in the storage unit 14, and the information that the electric field intensity information of the base station (20A) is higher than the electric field intensity information of the base station (20B) is stored. If stored, the mobile communication terminal 10 communicating with the base station (20B) storing the lower electric field strength information communicates with the base station (20A) storing the higher electric field strength information. Handover to the base station (20A).
[0042]
FIG. 2 is a flowchart illustrating a flow of a process in which the mobile communication terminal 10 according to the first embodiment stores the electric field strength information from the base station in the measured position information in the storage unit 14.
[0043]
First, the radio unit 12 acquires the electric field strength of the base station currently receiving (step 101). At this time, the field strengths of a plurality of base stations capable of simultaneously receiving radio waves are obtained.
[0044]
Then, the GPS unit 15 acquires the position information of the current point. This position information is obtained as information on the latitude and longitude of the receiving point by radio waves from GPS satellites (step 102). At this time, the received latitude and longitude information can be obtained finely to the decimal point, but in the present embodiment, the received latitude and longitude information is determined in advance by a predetermined number of digits depending on the range of the cell of the base station. (For example, position information with 100 m square as one range).
[0045]
Next, it is determined whether or not the electric field intensity information corresponding to the position information acquired in step 102 has already been stored in the storage unit 14 (step 103). If it is determined that the electric field strength information at the same position information has not already been stored in the storage unit 14, it is determined whether there is a free space in the electric field strength information storage area of the storage unit 14 (step 107). If there is no free space in the electric field intensity information storage area, the electric field intensity information having the oldest last update time is deleted from the storage unit 14 (step 108). After that, the electric field strength information acquired in step 101 and the position information acquired in step 102 are stored in the storage unit 14 (step 106).
[0046]
On the other hand, when the electric field intensity information of the same position information is stored in the storage unit 14, the electric field intensity information of each of the base stations 20A, 20B, and 20C in the already stored position information and the electric field intensity information acquired in step 101 Is calculated by weighting and averaging (step 104). This averaging operation is performed by a weighted average (weighted average) based on the number of acquisitions. That is, by adding the newly acquired electric field intensity to the product of the electric field intensity information stored corresponding to the position information and the number of measurements, and dividing by the value obtained by adding 1 to the number of acquisitions, An average weighted according to the number of measurements is obtained. This is because when the electric field intensity information of the base station 20 measured at the same point is acquired a plurality of times, the electric field intensity information is averaged, data is accumulated, and a more temporary change in the radio wave state is obtained. This is because leveled electric field intensity information can be obtained by exclusion.
[0047]
Next, the location information and the number of times of acquisition of the field strength information stored corresponding to each of the base stations 20A, 20B, and 20C are updated by adding 1 (step 105).
[0048]
At step 106, the new electric field strength information obtained by the calculation at step 104 is stored.
[0049]
By the above processing, the electric field strength of the signal from the base station 20 corresponding to the position information acquired by the GPS unit 15 is stored in the storage unit 14.
[0050]
FIG. 3 shows an example of the electric field intensity information, the position information, and the like stored in the storage unit 14 in step 106 described above, and FIG. 4 shows the terrain corresponding to the position information of FIG. Here is an example.
[0051]
When there are base stations (BS1, BS2) and obstacles such as mountains as shown in FIG. 4, and the mobile communication terminal 10 moves around the obstacles, the electric field strength as shown in FIG. 3 is measured.
[0052]
The leftmost column (No.) of the table is a serial number assigned in the order in which the position information was acquired. The position is position information measured by the GPS unit 15, and is represented as latitude and longitude information in a specific geodetic system. The base station ID is information uniquely assigned to the base station with which the mobile communication terminal 10 communicates. The electric field strength indicates a state of a radio signal communicating with the base station 20. The number of times indicates how many times the position and the electric field strength information of the base station 20 have been acquired, and is used for weighting when averaging (step 104 in FIG. 2). The last update time indicates the time when the electric field strength information of the base station 20 corresponding to the position was last obtained, and is used for deleting old data (step 108 in FIG. 2).
[0053]
Next, a process of performing a handover based on the stored position information, the electric field strength information of the base station 20, and the current position information will be described.
[0054]
FIG. 5 is a flowchart illustrating a process of performing handover from current position information in the wireless communication system according to the first embodiment.
[0055]
First, the electric field strength of the base station 20 currently being received by the radio unit 12 is acquired (step 201).
[0056]
Next, the position information of the local point is acquired by the GPS unit 15 (step 202). Next, it is determined whether or not the acquired location information of the local point is stored in the storage unit 14 (step 203). When it is determined that the position information of the local point is not stored in the storage unit 14, the normal handover process is performed without performing the handover based on the stored electric field strength information (step 206). That is, it is determined whether or not to perform handover based on the electric field intensity measured at present.
[0057]
On the other hand, when it is determined that the location information of the local point is stored in the storage unit 14, it is determined whether or not the electric field strength of the base station 20 acquired in step 201 is 0. When the electric field strength of the signal transmitted from the base station 20 is 0, the signal from the base station cannot be received, so that the signal is excluded from the handover target, and the handover based on the stored electric field strength information is not performed. Is performed. That is, it is determined whether or not to perform handover based on the electric field strength measured at present (step 206). This is because, when the electric field strength from the base station 20 is 0, it is considered that a failure of the corresponding base station 20 has occurred. This is because it is desirable to perform a handover so as to communicate with the station 20.
[0058]
In this case, the threshold value of the electric field strength is not set to 0, and the value is set to a value at which the communication is interrupted when the handover to the base station is performed, so that the communication interruption due to the handover is prevented based on the stored electric field strength information. Is also good.
[0059]
On the other hand, when the electric field strength from the base station 20 is not 0, since the signal from the base station is received, the handover based on the stored electric field strength information is performed, that is, the stored position is determined. The electric field strength information of the base station 20 corresponding to the information is read, and it is determined whether or not to perform the handover. Specifically, the field strength information of the base station 20 currently in communication read from the storage unit 14 is compared with the field strength information of the neighboring base station 20 read from the storage unit 14 to determine whether to perform a handover. Is determined.
[0060]
For example, if the read field strength information of the base station (20A) is better than the field strength information of the base station (20B) currently communicating, the mobile communication terminal 10 determines that a handover is necessary, and 20A). On the other hand, if the read electric field strength information of the base station (20A) is inferior to the electric field strength information of the base station (20B) with which communication is currently being performed, it is determined that the handover is unnecessary, and the handover is not requested.
[0061]
By the processing in FIG. 5 described above, it is possible to determine whether or not to perform a handover based on the acquired electric field strength information and the already stored electric field strength information.
[0062]
In the mobile communication system according to the first embodiment configured as described above, the position information acquired by the GPS unit 15 and the accumulated data of the electric field intensity information of the base station 20 stored corresponding to the position information are used. Since it is determined whether or not to perform a handover, it is possible to reduce handovers that are frequently performed due to a change in a radio wave state due to a radio wave disturbance or a terrain state while the mobile phone is moving.
[0063]
Next, a mobile communication system according to a second embodiment will be described.
[0064]
In the mobile communication system according to the second embodiment, as compared with the first embodiment, it is not determined whether the mobile phone performs the handover, but it is determined whether the base station performs the handover. The points are different. This is applicable to, for example, a handover method adopted in a CDMA system or the like, in which a base station takes the initiative to determine a handover destination base station. Note that components having the same functions as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.
[0065]
FIG. 6 is a block diagram illustrating a configuration of the wireless communication system according to the second embodiment.
[0066]
The control station 30 is connected to the base station 20. The control station 30 performs a process of determining whether or not to perform a handover of the mobile communication terminal 10 that is performing communication with the base station 20.
[0067]
The storage unit 14 periodically stores the position information measured by the GPS unit 15 of the mobile communication terminal 10 and the desired wave to interference wave ratio (CIR) as the line quality information of the signal from the base station 20 in the position information. I do. Then, it is checked whether or not the current position information measured by the GPS unit 15 matches any of the position information already stored in the storage unit 14. The channel quality information of the corresponding base station 20 is read, and it is determined whether or not to perform a handover based on the read channel quality information of the base station.
[0068]
Further, when the CIR of the base station 20 corresponding to the same position information is acquired a plurality of times, the information to be stored in the storage unit 14 is calculated by averaging by weighting according to the number of acquisitions and stored. By using the averaged line quality information weighted in this way, the line quality information of the base station 20 measured at the same point is accumulated, and more accurate handover control can be performed by the learning effect.
[0069]
For example, the current position information measured by the GPS unit 15 is already stored in the storage unit 14, and the CIR of the base station (20A) is higher than the CIR of the base station (20B). If the channel quality information is stored, the control station 30 that has obtained the channel quality information of these base stations, the mobile communication terminal 10 that is communicating with the base station (20B) in which the lower channel quality information is stored becomes more mobile. The mobile communication terminal 10 is instructed to perform handover to the base station (20A) in order to communicate with the base station (20A) in which the high channel quality information is stored.
[0070]
Next, the operation of the second embodiment configured as described above will be described.
[0071]
FIG. 7 is a flowchart illustrating a flow of a process in which the mobile communication terminal 10 according to the first embodiment stores the electric field strength information from the base station in the measured position information in the storage unit 14.
[0072]
First, the radio unit 12 acquires the channel quality (desired wave to interference wave ratio (CIR)) of the base station that is currently receiving (step 301). At this time, the CIRs of a plurality of base stations capable of simultaneously receiving radio waves are obtained.
[0073]
Then, the GPS unit 15 acquires the position information of the current point. This position information is obtained as information on the latitude and longitude of the receiving point by radio waves from GPS satellites (step 302). At this time, the received latitude and longitude information can be obtained finely to the decimal point, but in the present embodiment, the received latitude and longitude information is determined in advance by a predetermined number of digits depending on the range of the cell of the base station. (For example, position information with 100 m square as one range).
[0074]
Next, it is determined whether or not the line quality information corresponding to the position information acquired in step 302 is already stored in the storage unit 14 (step 303). If it is determined that the line quality information at the same location information has not been stored in the storage unit 14, it is determined whether there is a free space in the line quality information storage area of the storage unit 14 (step 307). If there is no free space in the line quality information storage area, the line quality information having the oldest update time is deleted from the storage unit 14 (step 308). Thereafter, the line quality information obtained in step 301 and the position information obtained in step 302 are stored in the storage unit 14 (step 306).
[0075]
On the other hand, when the line quality information of the same location information is stored in the storage unit 14, the channel quality information of each of the base stations 20A, 20B, and 20C in the already stored location information, and the CIR acquired in step 301, Is weighted and averaged (step 304). This averaging operation is performed by a weighted average (weighted average) based on the number of acquisitions. That is, by adding the newly acquired CIR to the product of the line quality information stored corresponding to the location information and the number of measurements, and dividing by the value obtained by adding 1 to the number of acquisitions, An average weighted according to the number of times is obtained. This is because, when the line quality information of the base station 20 measured at the same point is acquired a plurality of times, the data is accumulated by averaging the line quality information, and the temporary change of the radio wave state is reduced. This is because it is possible to obtain line quality information that is excluded and leveled.
[0076]
Next, the location information and the number of times of acquisition of the line quality information stored corresponding to each of the base stations 20A, 20B, and 20C are updated by adding 1 (step 305).
[0077]
In step 306, the new line quality information obtained by the calculation in step 304 is stored.
[0078]
Through the above processing, the line quality of the signal from the base station 20 corresponding to the position information acquired by the GPS unit 15 is stored in the storage unit 14.
[0079]
When the base station (BS1, BS2) and obstacles such as mountains exist as shown in FIG. 4 and the mobile communication terminal 10 moves around the obstacles, as in the first embodiment, FIG. Is measured as shown in FIG.
[0080]
Next, a process for performing a handover based on the position information and the channel quality information stored in the storage unit 14 and the current position information will be described.
[0081]
FIG. 8 is a flowchart illustrating a process of performing handover from current position information in the wireless communication system according to the second embodiment.
[0082]
First, the channel quality (desired wave to interference wave ratio (CIR)) of the base station 20 currently being received by the radio unit 12 is acquired (step 401).
[0083]
Next, the position information of the local point is acquired by the GPS unit 15 (step 402). Next, it is determined whether or not the acquired location information of the local point is stored in the storage unit 14 (step 403). When it is determined that the location information of the local point is not stored in the storage unit 14, the normal handover process is performed without performing the handover based on the stored channel quality information. That is, the currently measured CIR is transmitted to the base station 20 (step 406). Then, the control station 30 determines whether or not to perform a handover based on the transmitted CIR.
[0084]
On the other hand, when it is determined that the location information of the local point is stored in the storage unit 14, it is determined whether or not the CIR of the base station 20 acquired in step 401 is 0 (step 404). If the CIR of the signal transmitted from the base station 20 is 0, the signal from the base station cannot be received, so that the signal is excluded from the target of handover, and the handover based on the stored line quality information is not performed. Perform handover. That is, the currently measured CIR is transmitted to the base station 20 (step 405). Then, the control station 30 determines whether or not to perform a handover based on the transmitted CIR. This is because when the CIR from the base station 20 is 0, it is considered that a failure of the corresponding base station 20 has occurred. This is because it is desirable to perform a handover so as to communicate with the H.20.
[0085]
In this case, the threshold value of the line quality is set to a value that is not 0 and the communication is interrupted when the handover to the base station is performed, so that the communication interruption due to the handover based on the stored line quality information is prevented. Good.
[0086]
On the other hand, if the line quality from the base station 20 is not 0, a signal from the base station has been received, and the signal is stored so that handover is performed based on the stored line quality information. The channel quality information is transmitted to the base station 20 (Step 405). Then, the control station 30 determines whether to perform a handover based on the transmitted line quality information.
That is, the control station 30 acquires the line quality information of the base station 20 corresponding to the position information stored in the mobile communication terminal 10, and determines whether to perform the handover. Specifically, the mobile communication terminal 10 transmits the channel quality information on the base station 20 currently in communication read from the storage unit 14 and the channel quality information on the neighboring base station 20 read from the storage unit 14. Therefore, a process of comparing these two to determine whether to perform handover is performed.
[0087]
For example, when the line quality information of the base station (20A) is better than the line quality information of the base station (20B) currently communicating, it is determined that a handover is necessary, and the handover is instructed to the mobile communication terminal 10. I do. On the other hand, if the read line quality information of the base station (20A) is inferior to the line quality information of the currently communicating base station (20B), it is determined that the handover is unnecessary, and the handover instruction to the mobile communication terminal 10 is given. Do not.
[0088]
By the processing in FIG. 8 described above, it is possible to determine whether to perform a handover based on the acquired line quality information and the already stored line quality information.
[0089]
In the mobile communication system according to the second embodiment configured as described above, the position information acquired by the GPS unit 15 and the accumulated data of the channel quality information of the base station 20 stored corresponding to the position information are used. Since it is determined whether or not to perform a handover, it is possible to reduce handovers that are frequently performed due to a change in a radio wave state due to a radio wave disturbance or a terrain state while the mobile phone is moving.
[0090]
In the first embodiment, the necessity of the handover is determined based on the electric field strength information. In the second embodiment, the necessity of the handover is determined based on the line quality information (desired wave to interference wave ratio (CIR)). For the determination, information such as a signal-to-interference noise power ratio (SIR) and a signal-to-noise ratio (S / N) may be used for the determination of the handover. In the wireless communication systems of the first and second embodiments, a system with a PCD system or a CDMA system has been described as an example, but this can be applied to a wireless communication system using another communication system.
[0091]
【The invention's effect】
According to the present invention, the current position information of the wireless communication terminal and the radio wave condition (electric field strength information, line quality information, etc.) between the wireless communication terminal and the base station are stored in association with each other by the GPS device, Since the information is accumulated by averaging the radio wave state of the base station, handover to an appropriate base station can be performed without storing a huge amount of data such as a map and placing a burden on the base station. In particular, since human daily behavior patterns are often repeated and travel routes are often the same every day, stored data is accumulated for places where a user of a mobile communication terminal frequently travels by utilizing this property, and handover is performed. Can be appropriately performed by the learning effect.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a configuration of a wireless communication system according to a first embodiment of this invention.
FIG. 2 is a flowchart illustrating a flow of a process of storing position information and electric field strength information according to the first embodiment.
FIG. 3 shows an example of an electric field strength, position information, and the like stored in a storage unit 14 according to the first embodiment.
FIG. 4 also shows an example of the terrain corresponding to the position information and the movement route of the mobile communication terminal 10 according to the first embodiment.
FIG. 5 is a flowchart illustrating a process of performing a handover from position information according to the first embodiment.
FIG. 6 is a block diagram illustrating a configuration of a wireless communication system according to a second embodiment of this invention.
FIG. 7 is a flowchart showing a flow of a process for storing location information and channel quality information according to the second embodiment.
FIG. 8 is a flowchart illustrating a process of performing handover from current position information according to the second embodiment.
[Explanation of symbols]
10 Mobile communication terminals
11 Antenna
12 Radio section
13 Control unit
14 Storage unit
15 GPS unit
16 GPS antenna
17 Operation / display section
20A, 20B, 20C base station
30 control stations

Claims (22)

A mobile communication terminal that is connected to a base station via a wireless communication line and performs communication by switching a base station that is a connection partner,
Position information detecting means for detecting the position of the mobile communication terminal;
Radio wave condition measuring means for measuring the radio wave condition of the base station,
A mobile communication terminal, comprising: storage means for storing the position information detected by the position information detection means and the measured radio wave state of the base station corresponding to the position information. An averaging means for obtaining an average for the radio wave state of the base station,
The mobile communication terminal according to claim 1, wherein the storage unit stores the averaged radio wave condition. Using the number of measurements of the radio state of the base station, comprising an averaging means for obtaining a weighted average for the radio state of the base station,
The mobile communication terminal according to claim 1, wherein the storage unit stores the averaged radio wave state and the number of times of measurement of the radio wave state of the base station. 4. The switching of a base station to be connected to is controlled using a radio wave state stored in the storage unit based on current position information detected by the position detection unit. Mobile communication terminal according to any one of the above. A storage determination unit that determines whether a radio wave state corresponding to current position information detected by the position detection unit is stored in the storage unit,
When the storage determining unit determines that the radio wave state corresponding to the current position information is stored in the storage unit, the base station serving as a connection partner is determined using the radio wave state stored in the storage unit. Select and send a connection request with the base station,
If it is determined by the storage determination unit that the radio wave state corresponding to the current position information is not stored in the storage unit, a base station to be a connection partner is determined using the measured radio wave state of the base station. By selecting and sending a connection request with the base station,
The mobile communication terminal according to claim 4, wherein switching of a base station to be connected is controlled. Based on a comparison result between the radio wave state with the base station measured by the radio wave state measuring means and a predetermined value, a base station to be connected to using the radio wave state stored in the storage means. The mobile communication terminal according to claim 5, wherein it is determined whether or not to select. A storage determination unit that determines whether a radio wave state corresponding to current position information detected by the position detection unit is stored in the storage unit,
If it is determined by the storage determination unit that the radio wave state corresponding to the current position information is stored in the storage unit, the radio wave state stored in the storage unit is transmitted to the base station,
When the storage determination unit determines that the radio wave state corresponding to the current position information is not stored in the storage unit, by transmitting the measured radio wave state of the base station to the base station,
The mobile communication terminal according to claim 4, wherein switching of a base station to be connected is controlled. Whether to transmit the radio wave state stored in the storage means to the base station based on a comparison result between the radio wave state with the base station measured by the radio wave state measuring means and a predetermined value. The mobile communication terminal according to claim 7, wherein the mobile communication terminal determines whether or not the mobile communication terminal is a mobile terminal. In a mobile communication system configured by a mobile communication terminal and a base station connected to the mobile communication terminal via a wireless communication line, the mobile communication terminal performs communication by switching a base station to be a connection partner.
The mobile communication terminal,
Position information detecting means for detecting the position of the mobile communication terminal;
Radio wave condition measuring means for measuring the radio wave condition of the base station,
Storage means for storing the position information detected by the position information detection means and the measured radio wave state with the base station corresponding to the position information,
A mobile communication system, wherein a base station to be connected to the mobile communication terminal is switched using a radio wave state stored in the storage unit based on current position information detected by the position detection unit. An averaging means for obtaining an average for the radio wave state of the base station,
The mobile communication system according to claim 9, wherein the storage unit stores the averaged radio wave condition. Using the number of measurements of the radio state of the base station, comprising an averaging means for obtaining a weighted average for the radio state of the base station,
The mobile communication system according to claim 9, wherein the storage unit stores the averaged radio wave state and the number of times of measurement of the radio wave state of the base station. The mobile communication terminal,
A storage determination unit that determines whether a radio wave state corresponding to current position information detected by the position detection unit is stored in the storage unit,
When the storage determining unit determines that the radio wave state corresponding to the current position information is stored in the storage unit, the base station serving as a connection partner is determined using the radio wave state stored in the storage unit. Select and send a connection request with the base station,
If it is determined by the storage determination unit that the radio wave state corresponding to the current position information is not stored in the storage unit, a base station to be a connection partner is determined using the measured radio wave state of the base station. Select and send a connection request with the base station,
The mobile communication system according to any one of claims 9 to 11, wherein the base station controls switching of the base station based on a connection request transmitted from the mobile communication terminal. The mobile communication terminal uses a radio wave state stored in the storage unit based on a comparison result between a radio wave state with the base station measured by the radio wave state measurement unit and a predetermined value. The mobile communication system according to claim 12, wherein it is determined whether to select a base station to be connected. The mobile communication terminal,
A storage determination unit that determines whether a radio wave state corresponding to current position information detected by the position detection unit is stored in the storage unit,
If it is determined by the storage determination unit that the radio wave state corresponding to the current position information is stored in the storage unit, the radio wave state stored in the storage unit is transmitted to the base station,
If it is determined by the storage determination unit that the radio wave state corresponding to the current position information is not stored in the storage unit, transmit the measured radio wave state of the base station to the base station,
The base station selects a base station as a connection partner of the mobile communication terminal based on a radio wave state of the base station transmitted from the mobile communication terminal, and controls switching of the base station. The mobile communication system according to claim 9. Whether to transmit the radio wave state stored in the storage means to the base station based on a comparison result between the radio wave state with the base station measured by the radio wave state measuring means and a predetermined value. The mobile communication system according to claim 14, wherein it is determined whether or not the mobile communication is performed. In a mobile communication system including a mobile communication terminal and a base station connected to the mobile communication terminal via a wireless communication line, a switching control method of a base station to which the mobile communication terminal is connected is provided. ,
Detecting the position of the mobile communication terminal,
Measure the radio wave condition with the base station,
The detected position information and the measured radio wave state with the base station corresponding to the position information are stored,
A switching control method, wherein a base station to be connected to the mobile communication terminal is switched using a radio wave state read based on the detected current position information. Find the average of the radio conditions of the base station,
17. The switching control method according to claim 16, wherein the averaged radio wave state is stored. Using the number of measurements of the radio state of the base station, to obtain a weighted average of the radio state of the base station,
17. The switching control method according to claim 16, wherein the averaged radio wave state and the number of times of measurement of the radio wave state of the base station are stored. The mobile communication terminal,
Determine whether the radio wave state corresponding to the detected current position information is stored,
If it is determined that the radio wave state corresponding to the current position information is stored, a base station to be connected is selected using the stored radio wave state, and a connection request with the base station is transmitted. And
When it is determined that the radio wave state corresponding to the current position information is not stored, the base station to be connected is selected using the measured radio wave state of the base station, and the connection with the base station is performed. Submit the request,
19. The switching control method according to claim 16, wherein the base station controls switching of the base station based on a connection request transmitted from the mobile communication terminal. The mobile communication terminal selects a base station to be connected to using the measured radio wave condition with the base station and a radio wave condition read based on a comparison result of a predetermined value. 20. The switching control method according to claim 19, wherein it is determined whether or not the switching is performed. The mobile communication terminal,
Determine whether the radio wave state corresponding to the detected current position information is stored,
When it is determined that the radio wave state corresponding to the current position information is stored, the stored radio wave state is transmitted to the base station,
When it is determined that the radio wave state corresponding to the current position information is not stored, the measured radio wave state of the base station is transmitted to the base station,
The base station selects a base station as a connection partner of the mobile communication terminal based on a radio wave state of the base station transmitted from the mobile communication terminal, and controls switching of the base station. The switching control method according to claim 16. The measured radio wave state with the base station and, based on a comparison result of a predetermined value, determining whether to transmit the stored radio wave state to the base station, The switching control method according to claim 21, wherein

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