JP2009010757A - Wireless terminal and wireless communication method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wireless terminal capable of improving the throughput in a configuration which is connectable to a plurality of wireless communication systems. <P>SOLUTION: A wireless terminal 10 compares throughput corresponding to the RSSI measured by an EV-DO communication unit 10b, with the throughput corresponding to the RSSI measured by a WLAN communication unit 10a and performs communication, by using either an EV-DO communication unit or a WLAN communication unit 10a which has the higher throughput. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a first radio communication system, a radio terminal connectable to a second radio communication system different from the first radio communication system, and a radio communication method.

  In recent years, with the spread of wireless communication technology, an environment in which a plurality of wireless communication systems with different communication methods can be used simultaneously is being prepared. For example, cdma 2000 nx evolution-data only (EV-DO), which is a kind of third-generation mobile phone system, and a wireless LAN system (hereinafter referred to as “WLAN”) defined by IEEE802.11 etc. Providing possible wireless terminals is under consideration.

A wireless terminal that can be connected to such a plurality of wireless communication systems monitors the reception quality (for example, RSSI) of a wireless signal received from the connected wireless base station, and the communication being executed is performed due to the deterioration of the reception quality. Before disconnection, handoff to a radio base station of another radio communication system can be executed (see, for example, Patent Document 1).
Japanese Patent Laying-Open No. 2005-311702 (page 7, FIG. 2)

  By the way, both EV-DO and WLAN systems theoretically enable faster data communication using WLAN than EV-DO. For this reason, when determining the handoff destination based on the reception quality as described above, if the reception quality of both EV-DO and WLAN systems is equivalent, the wireless terminal performs a handoff to the WLAN wireless base station. It is possible.

  However, the effective data communication amount per unit time (hereinafter referred to as “throughput”) in the wireless terminal is determined according to the hardware configuration of the wireless terminal and the load status in the wireless base station to which the wireless terminal is connected. Therefore, even if the reception quality of both EV-DO and WLAN systems is the same in a wireless terminal, there are cases where high-speed data communication is possible using EV-DO rather than WLAN.

  As described above, a wireless terminal that can be connected to a plurality of wireless communication systems has room for improvement in terms of improving throughput.

  Accordingly, the present invention has been made to solve the above-described problem, and provides a wireless terminal and a wireless communication method capable of improving throughput in a configuration connectable to a plurality of wireless communication systems. With the goal.

  A first feature of the present invention is a wireless terminal (wireless terminal 10) connectable to a first wireless communication system (EV-DO) and a second wireless communication system (WLAN) different from the first wireless communication system. The first radio for measuring the reception quality (RSSI) of the radio signal received from the first radio base station while connecting to the first radio base station (radio base station 21) constituting the first radio communication system. Connected to the communication unit (EV-DO communication unit 10b) and the second radio base station (access point 22) constituting the second radio communication system, and received quality of radio signals received from the second radio base station A first correspondence table (EV-DO table) that associates the second wireless communication unit (WLAN communication unit 10a) that measures reception with the reception quality and throughput in the first wireless communication system From T1), the first throughput acquisition unit (handoff control unit 176) that acquires the throughput corresponding to the reception quality measured by the first wireless communication unit is associated with the reception quality and the throughput in the second wireless communication system. A second throughput acquisition unit (handoff control unit 176) for acquiring a throughput corresponding to the reception quality measured by the second wireless communication unit from the second correspondence table (WLAN table T2), and the first throughput acquisition unit Comparing the throughput acquired by the second throughput acquiring unit and the throughput acquired by the second throughput acquiring unit, and using the higher one of the first wireless communication unit and the second wireless communication unit for communication The gist is to include a communication control unit (hand-off control unit 176).

  According to such a feature, the communication control unit compares the throughput corresponding to the reception quality measured by the first radio communication unit with the throughput corresponding to the reception quality measured by the second radio communication unit, Communication is performed using the higher one of the first wireless communication unit and the second wireless communication unit. Therefore, it is possible to provide a wireless terminal capable of improving throughput in a configuration that can be connected to a plurality of wireless communication systems.

  The second feature of the present invention relates to the first feature of the present invention, and is the connection number determination for determining the number of connections (total value of FT Valid) which is the number of wireless terminals currently connected to the first wireless base station. (EV-DO communication control unit 172), and the communication control unit corrects the throughput acquired by the first throughput acquisition unit according to the number of connections determined by the connection number determination unit. This is the gist.

  A third feature of the present invention relates to the second feature of the present invention, wherein the connection number determination unit is based on broadcast information (QuickConfig Message) broadcast by the first radio base station at the time of standby. The gist is to determine the number of connections.

  A fourth feature of the present invention relates to the second feature of the present invention, wherein the connection number determination unit is a control used for controlling communication among the plurality of first radio base stations when performing communication. The gist is to determine the number of connections for the reference base station based on broadcast information (QuickConfig Message) broadcast by a reference base station (Reference PN) that transmits and receives a message (signaling message).

  A fifth feature of the present invention relates to the first feature of the present invention, in which a first communication throughput measurement unit (throughput detection unit 177) that periodically measures the throughput of the first wireless communication unit, and the second feature A second communication throughput measurement unit (throughput detection unit 177) that periodically measures the throughput of the wireless communication unit, and in the first correspondence table according to an average value of the throughput measured by the first communication throughput measurement unit A first throughput updating unit (handoff control unit 176) that updates the throughput of the second correspondence table, and a second that updates the throughput in the second correspondence table according to the average value of the throughputs measured by the second communication throughput measuring unit. The gist is to further include a throughput updating unit (hand-off control unit 176).

  A sixth feature of the present invention relates to the fifth feature of the present invention, and is directed to an application execution unit (application 170) that executes a predetermined application and an application throughput measurement unit (throughput detection) that measures the throughput of the predetermined application. 177), and when the throughput measured by the application throughput measurement unit is smaller than the throughput measured by the second communication throughput measurement unit, the first correspondence table The main point is to reduce the throughput.

  A seventh feature of the present invention relates to the fifth feature of the present invention, wherein an application execution unit that executes a predetermined application and a data amount to be processed by the predetermined application exceed a certain amount (upper limit watermark). A flow control unit (flow control unit 178) that executes flow control that is a control to stop communication when the second radio communication unit is connected to the second radio base station. When the flow control is executed by the flow control unit during communication, the gist is to reduce the throughput in the first correspondence table.

  The eighth feature of the present invention is that the first radio communication unit is connected to the first radio base station constituting the first radio communication system and measures the reception quality of the radio signal received from the first radio base station. A second radio communication unit connected to a second radio base station constituting a second radio communication system different from the first radio communication system and measuring reception quality of radio signals received from the second radio base station; A wireless communication method in a wireless terminal comprising: a first correspondence table in which reception quality and throughput in the first wireless communication system are associated with each other, and a throughput corresponding to the reception quality measured by the first wireless communication unit. From the second correspondence table in which the step of obtaining (step S102) and the reception quality and throughput in the second wireless communication system are associated with each other, The step of acquiring a throughput corresponding to the reception quality measured by the second wireless communication unit (step S102), the throughput acquired by the first throughput acquisition unit, and the throughput acquired by the second throughput acquisition unit And the step of communicating using the higher one of the first wireless communication unit and the second wireless communication unit according to the result of the comparing step (step S104) (step S104) And S105).

  According to the present invention, it is possible to provide a wireless terminal and a wireless communication method capable of improving throughput in a configuration connectable to a plurality of wireless communication systems.

  Next, an embodiment of the present invention will be described with reference to the drawings. Specifically, (1) overall schematic configuration, (2) configuration of wireless terminal, (3) operation of wireless terminal, (4) operation and effect, and (5) other embodiments will be described.

  In the description of the drawings in the following embodiments, the same or similar parts are denoted by the same or similar reference numerals.

(1) Overall Schematic Configuration FIG. 1 is an overall schematic configuration diagram of a communication system 1 according to the present embodiment. The communication system 1 includes a plurality of wireless communication systems.

  Specifically, the communication system 1 includes a wireless communication system (first wireless communication system) compliant with EV-DO, and a WLAN (WLAN) system (second wireless communication system) defined by IEEE 802.11 or the like. .

  Further, the communication system 1 includes a radio base station 21, an access point 22, a network 30, a radio terminal 10 and a content server 40.

  The wireless terminal 10 can perform wireless communication with the wireless base station 21 and the access point 22. That is, the wireless terminal 10 can be connected to both a wireless communication system compliant with EV-DO and a WLAN defined by IEEE 802.11 or the like.

  The radio base station 21 is included in a radio communication system compliant with EV-DO. The access point 22 is included in a wireless communication system compliant with WLAN.

  The content server 40 provides various contents to the wireless terminal 10 via the network 30. In the present embodiment, the wireless terminal 10 executes an application (for example, Web browsing or the like) that involves communication with the content server 40.

(2) Configuration of Wireless Terminal Next, the configuration of the wireless terminal 10 will be described with reference to FIGS. Specifically, (2.1) schematic configuration of wireless terminal, (2.2) table configuration, and (2.3) detailed configuration of wireless terminal will be described.

(2.1) Schematic Configuration of Wireless Terminal FIG. 2 is a schematic configuration diagram of the wireless terminal 10. The wireless terminal 10 includes a WLAN communication unit 10a, an EV-DO communication unit 10b, a control unit 17, a storage unit 18, a display unit 19a, an input unit 19b, a microphone 20a, and a speaker 20b.

  The WLAN communication unit 10 a transmits and receives wireless signals according to the WLAN to the access point 22. Further, the WLAN communication unit 10 a performs conversion between the radio signal and the baseband signal, and transmits and receives the baseband signal to and from the control unit 17.

  The EV-DO communication unit 10 b transmits and receives a radio signal according to EV-DO to and from the radio base station 21. In addition, the EV-DO communication unit 10 b performs conversion between the radio signal and the baseband signal, and transmits and receives the baseband signal to and from the control unit 17.

  The display unit 19a displays an image received via the control unit 17, and displays operation details (such as an input telephone number and an address). The input unit 19b is configured by a numeric keypad, function keys, and the like, and is an interface used for inputting user operation content.

  The microphone 20a collects sound and inputs sound data to the control unit 17 based on the collected sound. The speaker 20b outputs sound based on the sound data acquired from the control unit 17.

  The control unit 17 controls various functions that the wireless terminal 10 has. The control unit 17 executes various protocols such as RTP, IP, and SIP. The storage unit 18 stores various information used for control in the wireless terminal 10.

  The WLAN communication unit 10a includes an antenna 11a, a transmission / reception selector switch 12a, a WLAN transmission unit 13a, a WLAN reception unit 13b, an encoding unit 15a, and a decoding unit 15b.

  The encoding unit 15 a encodes the baseband signal from the control unit 17. The WLAN transmission unit 13a performs up-conversion and amplification of the encoded baseband signal. Thereby, a radio signal (RF signal) is generated. The generated RF signal is transmitted to the outside through the transmission / reception selector switch 12a and the antenna 11a.

  The WLAN receiver 13b performs amplification and down-conversion of the RF signal input via the antenna 11a and the transmission / reception selector switch 12a, and generates a baseband signal. The decoding unit 15 b decodes the generated baseband signal and inputs the decoded baseband signal to the control unit 17.

  The EV-DO communication unit 10b includes an antenna 11b, an antenna 11c, a transmission / reception selector switch 12b, an RF transmission unit 14a, an RF reception unit 14b, an RF reception unit 14c, an encoding unit 16a, a decoding unit 16b, and a decoding unit 16c. . Since the outline of each block of the EV-DO communication unit 10b is the same as that of the WLAN communication unit 10a, description thereof is omitted.

(2.2) Table Configuration Next, the EV-DO table T1 and the WLAN table T2 stored in the storage unit 18 will be described. FIG. 3 is a table configuration diagram showing a table configuration of the EV-DO table T1 and the WLAN table T2.

  The EV-DO table T1 and the WLAN table T2 associate numbers (No.), radio communication systems (communication units), electric field strength (RSSI), and throughput.

  In the throughputs in the EV-DO table T1 and the WLAN table T2, downlink throughput when the wireless terminal 10 executes an application that can be processed at the fastest speed is stored as an initial value. In the example shown in FIG. The relationship 4> 1> 5> 2> 3> 6 holds.

  In the throughput in the EV-DO table T1 and the WLAN table T2, the numerical values in parentheses indicate the theoretical values of the communication speed, and are not actually stored in the EV-DO table T1 and the WLAN table T2.

(2.3) Detailed Configuration of Wireless Terminal FIG. 4 is a functional block diagram showing a detailed configuration of the wireless terminal 10, specifically, each function executed by the control unit 17.

  The control unit 17 includes an application 170, a WLAN communication control unit 171, an EV-DO communication control unit 172, a WLAN field strength detection unit 173, an EV-DO field strength detection unit 174, a handoff control unit 176, a throughput detection unit 177, and a flow control. Unit 178 and a mobile IP (MIP) control unit 179.

  In the present embodiment, the application 170 is an application that involves communication with the content server 40.

  The WLAN communication control unit 171 controls the WLAN communication unit 10a. The EV-DO communication control unit 172 controls the EV-DO communication unit 10b.

  The WLAN field strength detection unit 173 detects the RSSI measured by the WLAN communication unit 10a. The EV-DO field strength detection unit 174 detects the RSSI measured by the EV-DO communication unit 10b.

  In addition, the WLAN field strength detection unit 173 and the EV-DO field strength detection unit 174 notify the handoff control unit 176 of RSSI at regular intervals (1 second). Here, the RSSI value is an effective index even in a wireless environment in which rapid fluctuations are likely to occur by using an average value over a certain time, not an instantaneous value.

  The handoff control unit 176 refers to the values of the EV-DO table T1 and the WLAN table T2 according to the RSSI of WLAN and EV-DO, and instructs the WLAN communication control unit 171 and the EV-DO communication control unit 172 to perform handoff. . The handoff control unit 176 manages the EV-DO table T1 and the WLAN table T2.

  For example, as shown in FIG. When the WLAN RSSI deteriorates and falls below -50 dBm, and the EV-DO RSSI is higher than -60 dBm, the RSSI is lower than -50 dBm in the WLAN table T2. The throughput is 1.7 Mbps, which is lower than the throughput of 2 Mbps corresponding to RSSI of −60 dBm or higher in the EV-DO table T1. Therefore, the handoff control unit 176 has the No. Since the EV-DO of No. 1 has a higher throughput, control is performed to handoff to the EV-DO.

  On the other hand, when the RSSI of EV-DO is lower than -70 dBm, the handoff control unit 176 determines the WLAN No. of the currently executing communication. Since the throughput of 4 is higher, handoff is not executed.

  Further, when the WLAN RSSI improves after handoff from WLAN to EV-DO and exceeds −40 dBm, the handoff control unit 176 has a throughput corresponding to RSSI exceeding −40 dBm in the WLAN table T2 according to the EV. Since the throughput of 1 is exceeded, a handoff to the WLAN is performed. In this way, the handoff control unit 176 performs handoff between WLAN and EV-DO in consideration of RSSI and throughput in real time.

  The throughput detection unit 177 detects the throughput of the application 170, the throughput of the WLAN communication unit 10a, and the throughput of the EV-DO communication unit 10b.

  The flow control unit 178 executes flow control when the amount of data to be processed by the application 170 exceeds the upper limit watermark. In flow control, when the amount of data to be processed by the application 170 exceeds the upper limit watermark, communication is not performed until the lower limit watermark is reached.

  The MIP control unit 179 manages the IP address assigned to the wireless terminal 10.

(3) Operation of Wireless Terminal Next, with reference to FIGS. 5 to 9, the operation of the wireless terminal 10, specifically, (3.1) handoff processing and (3.2) table update processing will be described. .

(3.1) Handoff Processing Hereinafter, the procedure of (3.1.1) handoff processing and (3.1.2) EV-DO throughput adjustment processing will be described.

(3.1.1) Procedure for Handoff Processing FIG. 5 is a flowchart showing the procedure for handoff processing executed by the wireless terminal 10.

  In step S <b> 101, the WLAN communication unit 10 a measures RSSI from the access point 22. The WLAN field strength detection unit 173 detects the RSSI measured by the WLAN communication unit 10a and notifies the handoff control unit 176 of the detected RSSI.

  In addition, the EV-DO communication unit 10 b measures RSSI from the radio base station 21. The EV-DO field strength detection unit 174 detects the RSSI measured by the EV-DO communication unit 10b and notifies the handoff control unit 176 of the detected RSSI.

  In step S102, the handoff control unit 176 acquires the throughput corresponding to the RSSI notified by the WLAN field strength detection unit 173 from the WLAN table T2 via the table management unit 175.

  The handoff control unit 176 acquires the throughput corresponding to the RSSI notified by the EV-DO field strength detection unit 174 from the EV-DO table T1 via the table management unit 175.

  In step S103, the EV-DO communication control unit 172 determines the number of terminals connected to the currently connected wireless base station 21, and based on the determined number of terminals, the connection rate (connected) of the currently connected wireless base station 21 Number of terminals / total number of connectable terminals). The handoff control unit 176 adjusts the throughput acquired from the EV-DO table T1 according to the connection rate calculated by the EV-DO communication control unit 172.

  In step S104, the handoff control unit 176 compares the throughput acquired from the WLAN table T2 with the throughput acquired from the EV-DO table T1 (adjusted throughput).

  In step S105, the handoff control unit 176 performs control so as to handoff to the wireless communication system with higher throughput according to the comparison result in step S104.

  When handing off to the radio base station 21, the handoff control unit 176 instructs the EV-DO communication control unit 172 to start communication with the radio base station 21. On the other hand, when handing off to the access point 22, the handoff control unit 176 instructs the WLAN communication control unit 171 to start communication with the access point 22.

(3.1.2) Procedure of EV-DO Throughput Adjustment Process FIG. 6 is a flowchart showing details of the EV-DO throughput adjustment process executed by the wireless terminal 10, that is, the details of step S103 in FIG.

  In step S <b> 201, the EV-DO communication control unit 172 acquires RPC and FT Valid in the QuickConfig Message received from the radio base station 21.

  Specifically, when the EV-DO communication control unit 172 is in a standby state, the EV-DO communication control unit 172 acquires a QuickConfig Message that is notified by the currently waiting radio base station 21 (PN). On the other hand, when the EV-DO communication control unit 172 is in a communication state, the EV-DO communication control unit 172 acquires a QuickConfig Message broadcast by the current reference base station (Reference PN).

  The RPC is information indicating the total number of MAC indexes that the radio base station 21 can use for downlink communication, that is, the number of connections that can be connected to the radio base station 21. FT Valid is information indicating whether or not the wireless base station 21 is in use for each MAC index that can be used for downlink communication.

  In step S202, the EV-DO communication control unit 172 calculates the total value of FT Valid. Specifically, the EV-DO communication control unit 172 determines whether the MAC index is in use for each FT Valid, and connects the total number of MAC indexes in use to the radio base station 21. Specify as the number of terminals.

  In step S203, the EV-DO communication control unit 172 determines the connection rate (number of connected terminals / connections) of the radio base station 21 based on the number of connectable terminals specified by the PRC and the number of connected terminals specified by the FT Valid. The total number of possible terminals) is calculated.

  In step S204, the handoff control unit 176 multiplies the throughput acquired from the EV-DO table T1 by using 100−connection rate (%) as an index of handoff. Thereby, the throughput acquired from the EV-DO table T1 is adjusted so as to approach the actual throughput.

(3.2) Table Update Processing Here, (3.2.1) Table update processing procedure and (3.2.2) Table update processing procedure based on application throughput will be described.

(3.2.1) Schematic Procedure for Table Update Processing FIG. 7 is a flowchart showing a schematic procedure for table update processing executed by the wireless terminal 10.

  In step S301, the radio terminal 10 measures the electric field strength from the radio communication system (the radio base station 21 or the access point 22) in communication. That is, either the WLAN field strength detection unit 173 or the EV-DO field strength detection unit 174 detects the field strength.

  The throughput detector 177 detects the throughput of the communication unit (either the WLAN communication unit 10a or the EV-DO communication unit 10b) used for communication.

  Hereinafter, a case where the wireless terminal 10 is communicating with the access point 22 will be described as an example. That is, the WLAN field strength detection unit 173 detects the field strength from the access point 22. The throughput detector 177 detects the throughput of the WLAN communication unit 10a. Further, the process of step S301 is executed at a constant interval (for example, about 10 seconds).

  In step S302, the table management unit 175 calculates the average value of the electric field strength detected by the WLAN field strength detection unit 173 and the average value of the throughput of the WLAN communication unit 10a detected by the throughput detection unit 177.

  Further, the table management unit 175 calculates the difference between the calculated average value of the electric field strength and the average value of the throughput and the electric field strength and the throughput in the WLAN table T2, and updates the WLAN table T2 by correcting the difference. To do.

  In step S303, the flow control unit 178 determines whether or not the amount of data temporarily stored in a buffer unit (not shown) (to be processed by the application 170) exceeds the upper limit watermark. If the amount of data to be processed by the application 170 exceeds the upper limit watermark, the process proceeds to step S304. On the other hand, if the amount of data to be processed by the application 170 does not exceed the upper limit watermark, the process returns to step S301.

  In step S304, the table management unit 175 performs update processing of the EV-DO table T1 and the WLAN table T2. Details of the update process will be described later.

  In step S305, the table management unit 175 determines whether or not the application 170 has finished executing the application. When the execution of the application is completed, the process proceeds to step S306. On the other hand, if the application is being executed, the process returns to step S301.

  In step S306, the table management unit 175 initializes the EV-DO table T1 and the WLAN table T2, that is, returns to the state of FIG.

(3.2.2) Detailed Procedure of Table Update Process FIG. 8 is a flowchart showing the detailed procedure of the table update process, that is, the details of step S204 in FIG.

  In step S401, the flow control unit 178 transmits an UpperFlow Message to the handoff control unit 176 when the amount of data temporarily stored in the buffer unit (not shown) (to be processed by the application 170) exceeds the upper limit watermark. To do.

  In step S402, when receiving the UpperFlow Message, the handoff control unit 176 instructs the throughput detection unit 177 to start measuring the throughput. In addition, the handoff control unit 176 controls to stop communication with the content server 40 until the amount of data to be processed by the application 170 reaches the lower limit Watermark.

  In step S403, the throughput detection unit 177 starts time measurement.

  In step S404, the flow control unit 178 detects that the amount of data temporarily stored in the buffer unit (not shown) (to be processed by the application 170) has reached the lower limit Watermark, and sends the LowerFlow Message to the handoff control unit 176. Send to.

  In step S405, when receiving the LowerFlow Message, the handoff control unit 176 instructs the throughput detection unit 177 to stop the time measurement. When the throughput detection unit 177 is instructed to stop the time measurement, the throughput detection unit 177 stops the time measurement.

  The throughput detection unit 177 calculates the throughput of the application 170 based on the measured time. For example, the throughput detection unit 177 calculates the throughput of the application 170 by dividing the data amount of the difference between the upper limit watermark and the lower limit watermark by the measured time.

  In step S406, the throughput detection unit 177 notifies the handoff control unit 176 of the calculated throughput.

  In step S407, the handoff control unit 176 refers to the current MaxRate and confirms that the throughput of the application 170 is higher than MaxRate. Here, MaxRate is the highest throughput among the throughputs in the EV-DO table T1 and the WLAN table T2.

  When the throughput of the application 170 is lower than MaxRate, it indicates that the processing capability of the application 170 is lower than the communication capability. In this case, the handoff control unit 176 reduces the throughput in the EV-DO table T1 and the WLAN table T2.

  For example, when the throughput of the application 170 is 2.3 MBps, MaxRate is 2.5 MBps in the example of FIG. Therefore, ((2.5-2.3) /2.5) = 8%, and each throughput in the EV-DO table T1 and the WLAN table T2 in FIG. 3 is reduced by 8% as shown in FIG. Is done.

  Here, the throughput in both the EV-DO table T1 and the WLAN table T2 is uniformly reduced, but only the throughput in the table of the wireless communication system different from the wireless communication system in communication is reduced. Also good.

(4) Operation / Effect According to the present embodiment, the wireless terminal 10 calculates the throughput corresponding to the RSSI measured by the EV-DO communication unit 10b and the throughput corresponding to the RSSI measured by the WLAN communication unit 10a. In comparison, the EV-DO communication unit 10b and the WLAN communication unit 10a communicate using the higher throughput.

  Therefore, it is possible to provide the radio terminal 10 capable of improving the throughput in a configuration connectable to a plurality of radio communication systems.

  According to the present embodiment, the wireless terminal 10 calculates the connection rate of the wireless base station 21 from the total value of FT Valid and the PRC, and the throughput acquired from the EV-DO table T1 according to the calculated connection rate. Correct.

  Therefore, the wireless terminal 10 can determine the handoff destination wireless communication system in consideration of a decrease in throughput due to the connection rate, and thus can improve the throughput.

  According to the present embodiment, the wireless terminal 10 determines the number of connections based on the QuickConfig Message notified by the wireless base station 21 during standby.

  Therefore, the wireless terminal 10 can determine the number of connections even when waiting using an existing message.

  According to the present embodiment, the wireless terminal 10 connects to the reference base station (Reference PN) based on the QuickConfig Message broadcast by the reference base station (Reference PN) that transmits and receives a signaling message when executing communication. Determine the number.

  Therefore, the wireless terminal 10 can determine the number of connections for the reference base station (Reference PN) using an existing message.

  According to the present embodiment, the wireless terminal 10 periodically measures the throughput of the EV-DO communication unit 10b. The wireless terminal 10 periodically measures the throughput of the WLAN communication unit 10a. Further, the wireless terminal 10 updates the throughput in the EV-DO table T1 and the WLAN table T2 according to the measured average value of the throughput.

  Therefore, the throughput in the EV-DO table T1 and the WLAN table T2 can be adapted to the environment in which the wireless terminal 10 is used (for example, the radio wave environment and the load status of the wireless base station 21 and the access point 22). For this reason, the throughput of the wireless terminal 10 can be improved.

  According to the present embodiment, the wireless terminal 10 reduces the throughput in the EV-DO table T1 when the flow control is performed while the WLAN communication unit 10a is performing communication.

  As described above, when the WLAN table T2 is updated in accordance with the decrease in the throughput of the WLAN communication unit 10a, the throughput in the WLAN table T2 decreases, and handoff to EV-DO occurs.

  However, when the throughput of the WLAN communication unit 10a is reduced because the throughput of the application 170 is low, the handoff is a useless handoff. In other words, throughput does not improve even when handoff is performed.

  In such a case, by reducing the throughput in the EV-DO table T1, occurrence of useless handoff can be avoided and the load on the network 30 can be reduced.

  Similarly, when the flow control is performed while the EV-DO communication unit 10b is performing communication, the wireless terminal 10 decreases the throughput in the WLAN table T2. As a result, it is possible to avoid the occurrence of useless handoff, and the load on the network 30 can be reduced.

(5) Other Embodiments As described above, the present invention has been described according to the embodiment. However, it should not be understood that the description and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

  For example, the wireless terminal 10 may measure the throughput of the application 170 and reduce the throughput in the EV-DO table T1 when the measured throughput is smaller than the throughput of the communicating WLAN communication unit 10a. In addition, the wireless terminal 10 may measure the throughput of the application 170, and when the measured throughput is smaller than the throughput of the EV-DO communication unit 10b during communication, the wireless terminal 10 may reduce the throughput in the WLAN table T2.

  As a result, it is possible to avoid the occurrence of useless handoff, and the load on the network 30 can be reduced.

  In the above-described embodiment, the wireless terminal 10 that can be connected to both EV-DO and WLAN wireless communication systems has been described. However, the present invention is not limited to EV-DO and WLAN. For example, the wireless terminal 10 may be configured to be connectable to a wireless communication system (WiMAX; registered trademark) based on IEEE 802.16e.

  In the embodiment described above, RSSI is used as the reception quality from the radio base station 21 and the access point 22, but not limited to RSSI, SNR (Signal to Noise Ratio), CNR (Carrier to Noise Raito) or error. A rate or the like may be used. Ec / Io may also be used. An example of the EV-DO table T1 and the WLAN table T2 based on the SNR is shown in FIG. An example of the EV-DO table T1 and the WLAN table T2 based on Ec / Io is shown in FIG.

  In the above-described embodiment, the throughput is adjusted based on the connection rate of the radio base station 21 only for EV-DO. However, when the number of terminal connections and the connection rate are notified from the access point 22, throughput adjustment based on the connection rate may be performed for the WLAN.

  In the above-described embodiment, the wireless terminal 10 communicates with the content server 40. However, the present invention is not limited to this, and a voice call is performed with a communication destination terminal by executing a VoIP (Voice over Internet Protocol) application. Also good.

  Thus, it should be understood that the present invention includes various embodiments and the like not described herein. Therefore, the present invention is limited only by the invention specifying matters in the scope of claims reasonable from this disclosure.

1 is an overall schematic configuration diagram of a communication system according to an embodiment of the present invention. It is a schematic block diagram of the radio | wireless terminal which concerns on embodiment of this invention. It is a table block diagram which shows the table structure of the EV-DO table and WLAN table which concern on embodiment of this invention. It is a functional block diagram which shows each function performed by the control part of the radio | wireless terminal which concerns on embodiment of this invention. It is a flowchart which shows the procedure of the handoff process performed by the radio | wireless terminal which concerns on embodiment of this invention. It is a flowchart which shows the EV-DO throughput adjustment process performed by the radio | wireless terminal which concerns on embodiment of this invention. It is a flowchart which shows the schematic procedure of the table update process performed by the radio | wireless terminal which concerns on embodiment of this invention. It is a flowchart which shows the detailed procedure of the table update process performed by the radio | wireless terminal which concerns on embodiment of this invention. It is a figure which shows an example which reduced each throughput in the EV-DO table and WLAN table shown in FIG. It is a table block diagram which shows the table structure of the EV-DO table and WLAN table which concern on other embodiment (the 1). It is a table block diagram which shows the table structure of the EV-DO table and WLAN table which concern on other embodiment (the 2).

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Communication system, 10 ... Wireless terminal, 10a ... WLAN communication part, 10b ... EV-DO communication part, 11a-11c ... Antenna, 12a, 12b ... Transmission / reception changeover switch, 13a ... WLAN transmission part, 13b ... WLAN reception part, 14a ... RF transmitting unit, 14b, 14c ... RF receiving unit, 15a, 16a ... encoding unit, 15b, 16b, 16c ... decoding unit, 17 ... control unit, 18 ... storage unit, 19a ... display unit, 19b ... input unit 20a ... microphone, 20b ... speaker, 21 ... wireless base station, 22 ... access point, 30 ... network, 40 ... content server, 170 ... application, 171 ... WLAN communication control unit, 172 ... EV-DO communication control unit, 173 ... WLAN field strength detection unit, 174 ... EV-DO field strength detection unit, 175 ... Table management unit, 176 ... Han Off control unit, 177 ... throughput detection unit, 178 ... flow control unit, 179 ... MIP controller

Claims (8)

A wireless terminal connectable to a first wireless communication system and a second wireless communication system different from the first wireless communication system,
A first wireless communication unit connected to a first wireless base station constituting the first wireless communication system and measuring reception quality of a wireless signal received from the first wireless base station;
A second radio communication unit connected to a second radio base station constituting the second radio communication system and measuring reception quality of a radio signal received from the second radio base station;
A first throughput acquisition unit for acquiring a throughput corresponding to the reception quality measured by the first wireless communication unit from a first correspondence table in which the reception quality and the throughput in the first wireless communication system are associated;
A second throughput acquisition unit for acquiring a throughput corresponding to the reception quality measured by the second wireless communication unit from a second correspondence table in which the reception quality and the throughput in the second wireless communication system are associated with each other;
Comparing the throughput acquired by the first throughput acquisition unit with the throughput acquired by the second throughput acquisition unit, the higher one of the first wireless communication unit and the second wireless communication unit And a communication control unit that communicates using the wireless terminal. A connection number determination unit that determines the number of connections that is the number of wireless terminals connected to the first wireless base station;
The wireless terminal according to claim 1, wherein the communication control unit corrects the throughput acquired by the first throughput acquisition unit according to the number of connections determined by the connection number determination unit.   The wireless terminal according to claim 2, wherein the connection number determination unit determines the number of connections based on broadcast information broadcast by the first wireless base station during standby.   The connection number determination unit, based on broadcast information broadcast by a reference base station that transmits and receives a control message used to control communication among the first radio base stations when performing communication. The wireless terminal according to claim 2, wherein the number of connections is determined for. A first communication throughput measuring unit that periodically measures the throughput of the first wireless communication unit;
A second communication throughput measuring unit that periodically measures the throughput of the second wireless communication unit;
A first throughput updating unit that updates a throughput in the first correspondence table according to an average value of the throughput measured by the first communication throughput measuring unit;
The wireless terminal according to claim 1, further comprising: a second throughput updating unit that updates a throughput in the second correspondence table according to an average value of the throughput measured by the second communication throughput measuring unit. An application execution unit for executing a predetermined application;
An application throughput measuring unit that measures the throughput of the predetermined application;
The first throughput update unit reduces the throughput in the first correspondence table when the throughput measured by the application throughput measurement unit is smaller than the throughput measured by the second communication throughput measurement unit. 5. A wireless terminal according to 5. An application execution unit for executing a predetermined application;
A flow control unit that executes flow control that is control for stopping communication when the amount of data to be processed by the predetermined application exceeds a certain amount;
When the flow control is executed by the flow control unit while the second radio communication unit is executing communication with the second radio base station, the first throughput update unit is configured to perform throughput in the first correspondence table. The wireless terminal according to claim 5, wherein the wireless terminal is reduced. A first wireless communication unit for connecting to a first wireless base station constituting the first wireless communication system and measuring reception quality of a wireless signal received from the first wireless base station;
A second radio communication unit that connects to a second radio base station that constitutes a second radio communication system different from the first radio communication system, and that measures reception quality of radio signals received from the second radio base station; A wireless communication method in a wireless terminal comprising:
Obtaining a throughput corresponding to the reception quality measured by the first wireless communication unit from a first correspondence table in which the reception quality and the throughput in the first wireless communication system are associated with each other;
Obtaining a throughput corresponding to the reception quality measured by the second wireless communication unit from a second correspondence table in which the reception quality and the throughput in the second wireless communication system are associated with each other;
Comparing the throughput acquired by the first throughput acquisition unit with the throughput acquired by the second throughput acquisition unit;
And a step of communicating using a higher throughput of the first wireless communication unit and the second wireless communication unit according to a result of the comparing step.