JP2009267876A - Mobile terminal, and communication system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mobile terminal and communication system performing high-throughput and stable communication regardless of a position of the mobile terminal in a cell. <P>SOLUTION: A mobile terminal includes: a plurality of communication sections 121-123 selectively communicable with a specific base station among a plurality of base stations; a detection section 131 for acquiring communication quality of each of the base stations; a comparison section 132 for comparing the communication quality acquired by the detection section 131 with a predetermined specific value; and a control section 13 which connects each of the communication sections 121-123 to the base station of which the communication quality exceeds the predetermined specific value, on the basis of a result of the comparison made by the comparison section 132. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a mobile terminal such as a mobile phone having a plurality of communication devices and a communication system.

  Many mobile terminals such as mobile phones are equipped with one communication device configured with an RF circuit or the like, and establish communication links with one base station to perform communication.

  Hereinafter, a general portable terminal and a communication system will be described. FIG. 10 is a diagram illustrating a communication system to which a general mobile terminal is connected.

  As illustrated in FIG. 10, the communication system 4 includes base stations 2 a and 2 b and a mobile terminal 1 connected to the network 3. Base stations 2a and 2b are connected to the network 3, and the mobile terminal 1 communicates with a base station in a cell in which the mobile terminal 1 is located.

  The cell CELa indicates the communication range covered by the base station 2a, and the cell CEELb indicates the communication range covered by the base station 2b. In the example of FIG. 10, the mobile terminal 1 communicates with the base station 2a when the mobile terminal 1 is located in the cell CELa, and communicates with the base station 2b when the mobile terminal 1 is located within the cell CEELb. . When the mobile terminal 1 is located in the area AREa where the cells of the two base stations overlap, the mobile terminal 1 continues to communicate by handing over to the base station with the stronger radio field intensity.

  The electric field strength is strong at the center of the cell, the electric field strength is weak at the end of the cell, and as the distance between the base station and the portable terminal 1 increases, radio interference is more likely to occur due to buildings and the like. Therefore, when the mobile terminal 1 is located in an area where cells of a plurality of base stations overlap (corresponding to the ARE in FIG. 10), throughput may be reduced and stable communication may be difficult.

Thus, a mobile terminal and a communication system that prevent a decrease in throughput even when the mobile terminal is located at the end of a cell (or service area) have been disclosed (for example, see Patent Document 1).
JP 2001-346265 A

  However, the portable terminal disclosed in Patent Document 1 does not continuously establish a communication link with a plurality of base stations, and prevents a decrease in throughput when there is only one connection destination base station. It is difficult to continue stable communication.

  An object of the present invention is to provide a mobile terminal and a communication system capable of performing high-throughput and stable communication regardless of the position of the mobile terminal on the cell.

  A mobile terminal according to a first aspect of the present invention includes a plurality of communication units that can selectively communicate with a specific base station among a plurality of base stations, and an acquisition unit that acquires the communication quality of each of the base stations. A comparison unit that compares the communication quality acquired by the acquisition unit with a predetermined specified value, and a base station whose communication quality exceeds the predetermined specified value based on the comparison result of the comparison unit And a control unit to be connected.

  Preferably, the communication quality includes a reception level, and has an extraction unit that extracts the highest reception level from among the plurality of reception levels, and the comparison unit is the highest extracted by the extraction unit The reception level is compared with the predetermined specified value.

  Preferably, the control unit connects the plurality of communication units to the base station having the highest reception level.

  Preferably, the comparison unit compares the total amount of data waiting for transmission with a second specified value, and the control unit determines that when the total amount of data waiting for transmission exceeds the second specified value, The plurality of communication units are connected in stages to the base station having a high reception level.

  Preferably, the control unit connects each communication unit to a different base station when the highest reception level extracted by the extraction unit is equal to or less than the predetermined specified value.

  Preferably, the comparison unit compares a difference between the highest reception level extracted by the extraction unit and another reception level with a predetermined specified value different from the predetermined specified value, and the control unit The communication unit is connected to the base station with the highest reception level extracted by the extraction unit and the base station with a reception level close to the highest reception level.

  A communication system according to a second aspect of the present invention includes a mobile terminal having a plurality of communication units and a plurality of base stations, and the mobile terminal is selectively connected to a specific base station among the plurality of base stations. A plurality of communication units that can communicate with each other, an acquisition unit that acquires the communication quality of each of the base stations, a comparison unit that compares the communication quality acquired by the acquisition unit with a predetermined specified value, and a comparison of the comparison unit And a control unit that connects each of the communication units to a base station whose communication quality exceeds the predetermined specified value based on the result.

  According to the present invention, high-throughput and stable communication can be performed regardless of the position of the mobile terminal on the cell.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram illustrating an example of a communication system according to the present embodiment.

  A communication system 80 according to the present embodiment includes a mobile phone (UT) 10 as a mobile terminal, a personal computer (PC) 20, base stations (BS) 30A to 30C, a packet data switching node (PDSN) 40, a proxy server (PROXY). ) 50, an Internet network (INTERNET) 60, and a server 70.

  The communication system 80 is, for example, an iBurst (“iBurst” is a trademark application filed by Kyocera Corporation; trademark application 2008-2754), and is a TDMA / TDD (Time Division Multiple Access) system to obtain high frequency utilization efficiency. / Time Division Duplex) method is adopted.

  The communication system 80 is configured on the assumption of a network based on the Internet Protocol (simply called an IP network), and the mobile phone 10 can connect to the Internet network 60.

  In the present embodiment, the connection to the Internet network 60 by the mobile phone 10 will be mainly described.

  When the mobile phone 10 can be connected to a base station with high communication quality (specifically, reception level), the three communication units 121 to 123 have the highest reception level 1 so that high throughput can be obtained. It has a function of performing wireless communication by connecting to one base station (establishing a communication link).

  The mobile phone 10 has a function in which three communication units 121 to 123 connect to a plurality of base stations and perform wireless communication so that stable communication can be maintained when the mobile phone 10 cannot obtain a sufficient reception level. Have.

  Thus, in order to obtain high-speed throughput and stable communication, the mobile phone 10 is provided with three communication units 121 to 123.

  The mobile phone 10 functions as a modem when connected to the personal computer 20 by, for example, USB (Universal Serial Bus) or Bluetooth (registered trademark).

  The mobile phone 10 has a function of transmitting / receiving data to / from the personal computer 20. The mobile phone 10 wirelessly communicates with a specific base station among the base stations 30 </ b> A to 30 </ b> C, and transmits (packet) data received from the personal computer 20 to the server 70 via the Internet network 60. Conversely, the cellular phone 10 transmits data received from a specific base station via the Internet network 60 to the personal computer 20.

  The communication system 80 is fully equipped with a telephone network (not shown) to which base stations 30A to 30C are connected. The mobile phone 10 wirelessly communicates with a specific base station among the base stations 30A to 30C. It has a function of making a voice call in accordance with control of a server connected to the telephone network. In addition to the functions described above, the mobile phone 10 has functions for creating and sending / receiving e-mails, browsing WEB sites and content data (for example, moving images and still images), and the like.

  The personal computer 20 can perform various data processing, and can be connected to the mobile phone 10 to perform voice communication by VolP (Voice over Internet Protocol) or data transfer by FTP (File Transfer Protocol), for example. it can.

  At this time, the proxy software 18 distributes and integrates data transmitted / received via the Internet network 60 in conjunction with the proxy server 50.

  The base stations 30A to 30C have, for example, a plurality (for example, 12) of directional adaptive array antennas, and perform antenna directivity control with respect to mobile phones in the cell. Base stations 30A to 30C receive a radio signal from a mobile phone in the cell via an adaptive array antenna, and control the amplitude and phase of the transmission signal to be transmitted based on the correlation of the radio signal.

  For example, since the base stations 30A to 30C perform multiplex communication (for example, 3 multiplex), the phase and amplitude of the transmission target are controlled so that the signal level strength (electric field strength) of the transmission signal is increased. Then, a transmission signal is transmitted, and a signal having the opposite phase is given to the transmission signal for a transmission target that causes interference, a null point is formed, and then the transmission signal is transmitted.

  As a specific example, for example, the base station 30A transmits a transmission signal with an enhanced signal level to the mobile phone 10 in the cell, and a null point is set to other mobile phones in the cell. The formed transmission signal is transmitted. Thereby, radio wave interference between the base station 30A and another mobile phone is suppressed, communication quality with the base station 30A is improved, and multiplex communication is possible.

  Each of the base stations 30 </ b> A to 30 </ b> C is connected to the packet data exchange node 40, and transmits data transmitted to and received from the mobile phone 10 to the proxy server 50 via the packet data exchange node 40.

  The base stations 30A to 30C broadcast and transmit traffic information for enabling the mobile phone 10 to perform handover.

  The traffic information includes, for example, information for grasping the use status of the line and the base stations to which the own device can be connected.

  The packet data exchange node 40 is connected to each of the base stations 30A to 30C by a VPN (Virtual Private Network). The packet data exchange node 40 transmits and receives data between the packet data exchange node 40 and each base station according to 3GPP2 (Third Generation Partnership Project 2) standardized by the Japan Radio Industry Association. The packet data exchange node 40 also has a function as a termination of PPP (Point to Point Protocol).

  The proxy server 50 is connected between the packet data exchange node 40 and the Internet network 60. The proxy server 50 includes, for example, a mail server, an FTP server, a WEB (World Wide Web) server, and the like, and distributes and integrates data transmitted and received in conjunction with the proxy software 18 of the mobile phone 10.

  The server 70 is connected to the Internet network 60 and processes various data transmitted and received via the Internet network 60.

  Here, the protocol stack of the communication system 80 will be described.

  FIG. 2 is a diagram illustrating an example of a protocol stack of the communication system according to the present embodiment.

  As shown in FIG. 2, the PHY (Physical Layer) layer as the first layer is a protocol for performing channel coding, multiplexing, double modulation, etc. between the PHYs, The mobile phone 10 and the personal computer 20 are provided.

  The MAC (Media Access Control) layer as a second layer is a protocol that defines the frame structure and access method between the mobile phone 10 and the personal computer 20 between the MAC layers. Is provided.

  The PPPoE (PPP over Ethernet (registered trademark)) layer as the third layer is a protocol for performing dial-up connection, for example, and is provided in the mobile phone 10 and the personal computer 20.

  A PPP (Point to Point Protocol) layer as a third layer is a protocol for connecting to the Internet network 60, and is provided in the personal computer 20 and the packet data exchange node 40.

  The IP layer is a protocol for transmitting and receiving IP packets between the IP layers, and is provided in the personal computer 20, the packet data exchange node 40, the proxy server 50, and the server 70.

  The Data Link layer is a protocol that defines a communication method between directly connected devices, and is provided in the base stations 30A to 30C, the packet data exchange node 40, the proxy server 50, and the server 70. .

  The RP (Radio to Packet data) layer is an interface protocol between the base stations 30A to 30C and the packet data exchange node 40 defined by 3GPP2 (Third Generation Partnership Project 2).

  The iB layer is a wireless communication protocol for the iBurst system, and is provided in the first to third layers of the mobile phone 10 and the base stations 30A to 30C.

  The cellular phone 10 constituting the communication system 80 described above has a configuration as shown in FIG.

FIG. 3 is a block diagram illustrating a configuration example of the mobile phone 10 according to the present embodiment.
FIG. 4 is a diagram for explaining a communication method used in the communication system according to the present embodiment.

  As illustrated in FIG. 3, the mobile phone 10 includes an antenna (ANT) 111 to 113, a communication unit (RF) 121 to 123, a control unit (CPU) 13, a storage unit (MEM) 14, and an audio input / output unit (AUD). ) 15, a speaker (SP) 15a, a microphone (MIC) 15b, a display unit (DIS) 16, and an operation unit (KEY) 17.

  The control unit 13 includes a detection unit 131, a comparison unit 132, and a communication control unit 133. The comparison unit 132 corresponds to the comparison unit and the extraction unit according to the present invention, and the communication control unit 133 corresponds to the control unit according to the present invention.

The communication units 121 to 123 are configured by an RF circuit or the like. The communication unit 121 is connected to the antenna 111, the communication unit 122 is connected to the antenna 112, and the communication unit 123 is connected to the antenna 113.
The communication units 121 to 123 establish a communication link with a specific base station among the base stations 30A to 30C under the control of the communication control unit 133, for example, using the TDMA / TDD method, and perform wireless communication.

  At the time of transmission, the communication units 121 to 123 modulate any of the transmission signals output from the control unit 13 into a predetermined modulation method, and use any one of the base stations via the corresponding antennas 111 to 113 as the radio signal. Send to 30A-30C.

  At the time of reception, the communication units 121 to 123 demodulate radio wave signals received from any of the base stations 30A to 30C via the corresponding antennas 111 to 113, and output the demodulated signals to the control unit 13 as reception signals. .

  In the communication system 80, uplink (corresponding to the above transmission and also referred to as uplink) corresponds to eight types of modulation, and downlink (corresponding to the above reception and also referred to as downlink) corresponds to nine types of modulation. It corresponds to the method.

  Specifically, for example, BPSK (Binary Phase Shift Keying), BPSK +, QPSK (Quadrature Phase Shift Keying), QPSK +, 8PSK (Phase Shift Keying), 8PSK +, 12QAM (Quadrature phase Amplitude Modulation) , And 16QAM, and either modulation scheme is used. The downlink demodulation method corresponds to 24QAM in addition to the uplink modulation method.

  In the communication system 80, as shown in FIG. 4A, the frequency band used for wireless communication with the base station is approximately 5 MHz, and the band per carrier is approximately 625 kHz. Therefore, 8 carriers can be transmitted and received simultaneously in the 5 MHz band.

  As shown in FIG. 4B, one frame is composed of approximately 5 ms, and the number of upstream and downstream time slots is 3 slots each (6 slots in total). The uplink and downlink slot lengths are asymmetric, the symbol length is approximately 2 μs, and the symbol rate is 1/2 μ = 500 k symbols / s.

  A guard time of approximately 10 μs is provided between the uplink and the downlink in order to prevent a collision due to propagation delay occurring between the uplink and the downlink, and a guard time of approximately 85 μs is provided after the third slot of the downlink. Time is provided.

  The control unit 13 includes a computer (microprocessor) that executes processing based on a program (operating system, application program, etc.) stored in the storage unit 14, and performs various processing according to the procedure instructed in this program. Can be executed.

  That is, the control unit 13 can sequentially read the instruction code from the operation system or application program stored in the storage unit 14 and execute the process.

  In the communication system 80, once the mobile phone 10 is connected to the Internet network 60, the control unit 13 periodically makes random access to the base station unless the mobile phone 10 is located outside the service area.

  Based on the traffic information broadcasted by the base stations 30A to 30C and the communication quality such as the reception level detected by the detection unit 131 described later, the control unit 13 has the highest throughput and the high reception level. Hand over.

  The control unit 13 controls the communication units 121 to 123 to establish a communication link between these communication units and a specific base station.

  The control unit 13 comprehensively controls the overall operation of the mobile phone 10. That is, the control unit 13 performs various processes of the mobile phone 10 (control of voice calls performed via the network, creation and transmission / reception of e-mails, browsing of the WEB site, etc.) according to the operation of the operation unit 17 by the user. The operation of each component (transmission / reception of radio signals in the communication units 121 to 123, access to the storage unit 14, input / output of audio in the audio input / output unit 15, and image in the display unit 16 so as to be executed in an appropriate procedure Display etc.).

  The detection unit 131 detects a reception level from the reception signal input from the communication unit 121, and outputs the detected reception level to the comparison unit 132 as a detection result S1.

  The detection unit 131 detects the number of communicable base stations from the traffic information. If there are a plurality of communicable base stations, the detection unit 131 outputs a detection result S3 to that effect to the comparison unit 132.

  The comparison unit 132 extracts the highest reception level from the reception levels input from the detection unit 131, and compares whether or not the extracted reception level exceeds a specified value LT1 (corresponding to the specified value of the present invention). To do. The specified value L1 is a value that can maintain stable communication in communication with a base station, for example.

  When the extracted reception level exceeds the specified value LT1, the comparing unit 132 sets the transmission queue length of the data temporarily stored in the storage unit 14 at the time of data transmission to the specified value LT2 (the second specified value of the present invention). It is compared whether or not.

  The transmission queue length refers to the total amount of data waiting for transmission, and is, for example, the total amount of data in uplink slots 1 to 3 shown in FIG.

  When the transmission queue length exceeds the specified value LT2, the comparison unit 132 outputs a control signal S2 to that effect to the communication control unit 133. The specified value L2 is a value that can transmit data stably, for example.

  When the detection result S3 is input from the detection unit 131, the comparison unit 132 obtains a difference between reception levels (reception level difference LD), and compares whether or not the reception level difference LD is smaller than a specified value LT3. When the reception level difference LD is smaller than the specified value LT3, the comparison unit 132 outputs a control signal S4 to that effect to the communication control unit 133. The specified value LT3 is a value that enables stable communication.

  The communication control unit 133 controls any one of the communication units 121 to 123 based on the control signal S2 or S4 input from the comparison unit 132, and a communication link between the communication unit and a specific base station. Establish.

  The storage unit 14 is configured by a non-volatile storage device such as a flash memory, or a storage device such as SRAM or DRAM, and stores proxy software 18.

  The storage unit 14 temporarily stores data (slots) input from the control unit 13 during data transmission, and communicates the stored data via the control unit 13 in the order of data input according to the control of the control unit 13. Output to the units 121 to 123. In addition to the output result of the control unit 13, the storage unit 14 stores an application program executed by the control unit 13 and temporary data used in the process of the program.

  The audio input / output unit 15 processes an audio signal output to the speaker 15a and an audio signal input from the microphone 15b. That is, the voice input / output unit 15 amplifies the voice input from the microphone 15b, performs analog / digital (A / D) conversion, further performs processing such as encoding, and converts it into digital voice data for control. Part 13 output.

  The audio input / output unit 15 performs signal processing such as encoding, digital / analog (D / A) conversion, amplification, and the like on the audio data supplied from the control unit 13, converts the data into an analog audio signal, and then applies the signal to the speaker 15 a. Output.

  The display unit 16 is configured by, for example, a liquid crystal display panel, an organic EL (Electro-Luminescence) panel, and the like, and displays various information according to the video signal supplied from the control unit 13.

  The information displayed on the display unit 16 includes, for example, a telephone number of a call destination at the time of outgoing call (at the time of incoming call), character information such as an e-mail, time information such as a WEB site, a moving image, and a date, a remaining battery level, a success / failure of transmission A standby screen is included.

  The operation unit 17 includes a plurality of keys to which various functions such as a power key, a call key, a numeric key, a character key, a direction key, a determination key, and a call key are assigned. When these keys are operated by the user, the operation unit 17 generates a signal corresponding to the operation content and outputs the signal to the control unit 13 as a user instruction.

  Next, the operation of the mobile phone according to the present embodiment will be described with reference to FIGS.

FIG. 5 is a flowchart showing an operation example of the mobile phone according to the present embodiment.
FIG. 6 is a diagram for explaining the positional relationship of the base stations according to the present embodiment.

  FIG. 6 illustrates the positional relationship between the base stations 30A to 30C. CEL 30A represents a communication range covered by the base station 30A, CEL 30B represents a communication range covered by the base station 30B, and CEL 30C represents a communication range covered by the base station 30C. The cell radii of the base stations 30A to 30C vary depending on geographical conditions and the density of buildings near the base station, but the maximum cell radius in the communication system 80 is approximately 12.75 km.

  In order to prevent leakage of the communication range, each of the base stations 30A to 30C is installed so that some of the cells overlap (overlap). In the following description, the area where the cells overlap is denoted as area ARE. Since the area ARE corresponds to the edge of the cell, the communication quality such as the reception level is lower than the center of the cell. In the following description, it is assumed that the mobile phone 10 exists in the area ARE, and the communication unit 121 has established a communication link with the base station 30A.

  The base stations 30A to 30C broadcast and transmit traffic information and the like. As shown in FIG. 5, the communication unit 121 is configured to recognize a connectable base station and a communication environment of these base stations. Scanning is started (step ST1). At this time, the other communication units 122 and 123 are in a standby state.

  Note that, as described above, the base station scan refers to grasping connectable base stations and communication environments of these base stations, and is executed only by any one communication unit.

  More specifically, the communication unit 121 receives radio signals (denoted as S30A to S30C) such as traffic information received from the base stations 30A to 30C, and receives these radio signals as received signals (S30A to S30C). Output to the detection unit 131.

  The detection unit 131 detects reception levels (denoted as L30A to L30C) from the reception signals S30A to S30C input from the communication unit 121, and outputs the detected reception levels L30A to L30C to the comparison unit 132 as detection results S1. .

  The comparison unit 132 extracts the highest reception level from the reception levels L30A to L30C input from the detection unit 131, and compares whether or not the extracted reception level exceeds the specified value LT1 (step ST2).

  The process of step ST2 is provided for extracting the base station with the best communication quality from the base stations with which the communication link is currently established. When the highest reception level is greater than or equal to the prescribed value LT1 (YES), processing for obtaining higher throughput (steps ST3 to ST6) is performed for the base station with which the current communication link is established.

  On the other hand, when the highest reception level is less than or equal to the specified value LT1 (NO), the communication quality of the base station to which the communication link is currently established is low. Processing (steps ST7 to ST14) for performing the performed communication is performed.

  First, the processing of steps ST3 to ST6 will be described. In step ST2, it is assumed that, for example, reception level L30A is extracted from reception levels L30A to L30C.

  In step ST2, when the extracted reception level exceeds the specified value LT1 (YES), the comparison unit 132 has the transmission queue length of the transmission data temporarily stored in the storage unit 14 equal to or greater than the specified value LT2. Are compared (step ST3).

  In step ST3, when the transmission queue length exceeds the specified value LT2 (YES), the comparison unit 132 outputs a control signal S2 to that effect to the communication control unit 133.

  When the control signal S2 is input from the comparison unit 132, the communication control unit 133 controls the communication unit 122 to establish a communication link between the communication unit 122 and the base station 30A (step ST4).

  Thereafter, the communication units 121 and 122 start wireless communication with the base station 30A and transmit transmission data to the base station 30A.

  As described above, in the process of step ST4, when the data waiting for transmission is larger than the specified value LT2, a plurality of communication units transmit the transmission data in parallel, thereby obtaining high-speed throughput.

  On the other hand, when the transmission queue length does not exceed the specified value LT2 in step ST3 (NO), the process of step ST3 is once ended.

  After the communication unit 122 establishes a communication link with the base station 30A, the process of step ST3 is performed again (step ST5).

  In step ST5, when the transmission queue length exceeds the specified value LT2 (YES), the comparison unit 132 outputs a control signal S2 to that effect to the communication control unit 133.

  When the control signal S2 is input from the comparison unit 132, the communication control unit 133 controls the communication unit 123 to establish a communication link between the communication unit 123 and the base station 30A (step ST6).

  Thereafter, the communication units 122 and 123 start wireless communication with the base station 30A and transmit transmission data to the base station 30A.

  On the other hand, when the transmission queue length does not exceed the specified value LT2 in step ST5 (NO), the process of step ST5 is once ended.

  After the process of step ST6, the process of step ST1 is resumed after a predetermined time has elapsed.

  Here, the processing results of steps ST2 to ST6 described above will be described with reference to FIG.

  FIG. 7 is a diagram showing the processing results of steps ST2 to ST6 according to the present embodiment.

  The processing of steps ST2 to ST6 establishes a plurality of communication links for one base station with the best communication quality in order to perform higher throughput communication.

  As a result, as shown in FIG. 7, three communication sessions Sessions 1 to 3 are established between the mobile phone 10 and the packet data exchange node 40. Note that a session refers to a collection of communications necessary to execute one process.

  Thus, when the radio wave state is good and sufficient communication quality is obtained, high-throughput communication is realized even if the mobile phone 10 is located at the end of a cell such as the area ARE.

  Next, the process of steps ST7 to ST14 will be described.

  In step ST2, when the extracted highest reception level does not exceed the specified value LT1 (NO), the detecting unit 131 detects the number of communicable base stations from the traffic information (step ST7).

  If there are a plurality of communicable base stations in step ST7 (YES), the detection unit 131 outputs a detection result S3 to that effect to the comparison unit 132.

  At this time, for example, two base stations 30A and 30B are detected, and the reception level L30A is greater than the reception level L30B (reception level L30A> reception level L30B).

  When the detection result S3 is input from the detection unit 131, the comparison unit 132 obtains a difference (reception level difference LD) between the reception level L30A and the reception level L30B, and determines whether or not the reception level difference LD is smaller than the specified value LT3. Are compared (step ST8).

  In the process of step ST8, when the communication quality is low (step ST2), there are a plurality of connectable base stations (step ST7), and if the highest reception level in step ST2 is close to the other reception levels, A communication link is established with a plurality of base stations to ensure stable communication.

  In step ST8, when the reception level difference LD is smaller than the specified value LT3 (YES), the comparison unit 132 outputs a control signal S4 to that effect to the communication control unit 133.

  When control signal S4 is input from comparison unit 132, communication control unit 133 controls communication unit 122 to establish a communication link between communication unit 122 and base station 30B (step ST9).

  Thereafter, the communication unit 121 starts wireless communication with the base station 30A, and the communication unit 122 starts wireless communication with the base station 30B, and transmits transmission data to both base stations.

  Here, the processing results of steps ST7 to ST9 described above will be described with reference to FIG.

  FIG. 8 is a diagram showing the processing results of steps ST7 to ST9 according to the present embodiment.

  The processing of steps ST7 to ST9 establishes communication links with a plurality of base stations in order to perform more stable communication.

  As a result, as illustrated in FIG. 8, two communication sessions 1 and 2 are established between the mobile phone 10 and the packet data exchange node 40.

  As described above, even when the communication quality of the base station with which the communication link is currently established is not sufficient, when there is another usable base station, the mobile phone 10 is located at the end of the cell like the area ARE. Even if this is done, stable communication can be secured without being interrupted.

  By the way, although three communication units 121 to 123 are mounted on the mobile phone 10, the present invention is limited to two even if the number of communication units mounted on the mobile phone 10 is four or more. Even applicable.

  Specifically, when the number of communication units mounted on the mobile phone 10 is two (NO in step ST11), after the process in step ST9, the process in step ST1 is resumed after a lapse of a certain time.

  When the number of communication units mounted on the mobile phone 10 is three or more, that is, in the case of the present embodiment (YES in step ST11), the processes in steps ST12 to ST14 are executed.

  Instead of the communication unit 121, the communication unit 122 performs a base station scan (step ST12).

  Then, comparing section 132 compares whether or not the transmission queue length is greater than or equal to specified value LT2 (step ST13).

  In step ST13, when the transmission queue length exceeds the specified value LT2 (YES), the comparison unit 132 outputs a control signal S2 to that effect to the communication control unit 133.

  When the control signal S2 is input from the comparison unit 132, the communication control unit 133 controls the communication unit 123 to establish a communication link between the communication unit 123 and the base station 30C (step ST14).

  On the other hand, when the transmission queue length does not exceed the specified value LT2 in step ST13 (NO), the process of step ST13 is once ended.

  After the process of step ST14, the communication unit 123 is controlled to establish a communication link between the communication unit 123 and the base station 30C (step ST14).

  Thereafter, the communication unit 121 starts wireless communication with the base station 30A, the communication unit 122 starts wireless communication with the base station 30B, the communication unit 123 starts wireless communication with the base station 30C, and the base station 30A Transmission data is transmitted to ˜30C.

  Thereafter, the processing in step ST1 is resumed after a predetermined time has elapsed.

  Here, the processing results of steps ST12 to ST14 described above will be described with reference to FIG.

  FIG. 9 is a diagram showing the processing results of steps ST11 to ST14 according to the present embodiment.

  The processes of steps ST11 to ST14 are processes for performing more stable communication than the processes of steps ST7 to ST9.

  As a result, as shown in FIG. 9, three communication sessions Sessions 1 to 3 are established between the mobile phone 10 and the packet data exchange node 40. Accordingly, more stable communication can be ensured than in the state illustrated in FIG.

  As described above in detail, according to the present embodiment, even when the reception level fluctuates due to the movement of the user and the radio signal from a certain base station becomes weak, high-throughput and stable communication can only be performed. In addition, it is possible to maintain communication at a high symbol rate.

  In the mobile phone according to the present embodiment, all the functions of the constituent elements of the control unit 13 may be realized by software, or a part thereof may be realized by hardware. For example, the data processing of the detection unit 131, the comparison unit 132, and the communication control unit 133 may be realized on a computer by one or a plurality of programs, or at least a part thereof may be realized by hardware. .

It is a figure which shows the example of the communication system which concerns on implementation mobile. It is a figure which shows the example of the protocol stack of the communication system which concerns on embodiment. It is a block diagram which shows the structural example of the mobile telephone 10 which concerns on embodiment. It is a figure for demonstrating the communication system used in the communication system which concerns on embodiment. It is a block diagram which shows the operation example of the mobile telephone which concerns on embodiment. It is a figure for demonstrating the positional relationship of the base station which concerns on embodiment. It is a figure which shows the processing result of step ST2-ST6 which concerns on embodiment. It is a figure which shows the processing result of step ST7-ST9 which concerns on embodiment. It is a figure which shows the processing result of step ST11-ST14 which concerns on embodiment. It is a figure which shows the communication system with which the general portable terminal was connected.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Mobile phone (UT), 111-113 ... Antenna (ANT), 121-122 ... Communication part (RF), 13 ... Control part (CPU), 131 ... Detection part, 132 ... Comparison part, 133 ... Communication control part , 14 ... Memory unit (MEM), 15 ... Audio input / output unit (AUD), 15a ... Speaker (SP), 15b ... Microphone (MIC), 16 ... Display unit (DIS), 17 ... Operation unit (KEY), 18 ... Proxy software, 20 ... Personal computer (PC), 21 ... Proxy software, 30A, 30B, 30C ... Base station (BS), 40 ... Packet data switching node (PDSN), 50 ... Proxy server (PROXY), 60 ... Internet Network (INTERNET), 70 ... server, 80 ... communication system

Claims (7)

A plurality of communication units capable of selectively communicating with a specific base station among a plurality of base stations,
An acquisition unit for acquiring communication quality of each of the base stations;
A comparison unit that compares the communication quality acquired by the acquisition unit with a predetermined specified value;
A mobile terminal comprising: a control unit that connects each of the communication units to a base station whose communication quality exceeds the predetermined specified value based on a comparison result of the comparison unit. The communication quality includes a reception level,
An extraction unit that extracts the highest reception level from the plurality of reception levels;
The comparison unit includes:
The mobile terminal according to claim 1, wherein the highest reception level extracted by the extraction unit is compared with the predetermined specified value. The controller is
The mobile terminal according to claim 2, wherein the plurality of communication units are connected to the base station having the highest reception level. The comparison unit includes:
Compare the total amount of data waiting to be sent to the second specified value,
The controller is
The portable terminal according to claim 2 or 3, wherein when the total amount of data waiting for transmission exceeds the second specified value, the plurality of communication units are connected in stages to a base station having a high reception level. The controller is
The mobile terminal according to claim 2, wherein when the highest reception level extracted by the extraction unit is equal to or lower than the predetermined specified value, each communication unit is connected to a different base station. The comparison unit includes:
The difference between the highest reception level extracted by the extraction unit and other reception levels is compared with a predetermined specified value different from the predetermined specified value,
The controller is
The mobile terminal according to claim 5, wherein each of the communication units is connected to the base station having the highest reception level extracted by the extraction unit and a base station having a reception level close to the highest reception level. A mobile terminal having a plurality of communication units;
A plurality of base stations,
The portable terminal is
A plurality of communication units capable of selectively communicating with a specific base station among a plurality of base stations,
An acquisition unit for acquiring communication quality of each of the base stations;
A comparison unit that compares the communication quality acquired by the acquisition unit with a predetermined specified value;
And a control unit that connects each of the communication units to a base station whose communication quality exceeds the predetermined specified value based on a comparison result of the comparison unit.

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