JP4932755B2 - Wireless communication method - Google Patents

Description

  The present invention relates to a first wireless communication system and a wireless communication method for executing wireless communication by connecting to a second wireless communication system different from the first wireless communication system.

  In recent years, along with the development of wireless communication technology, mobile wireless communication devices such as mobile phone terminals have a plurality of wireless communication systems with different physical layer systems, such as mobile phone systems and iBurst (registered trademark). An environment in which a wireless MAN system can be used simultaneously is being prepared.

IP mobility such as Mobile IPv6 (refer to Non-Patent Document 1) and NEMO Basic Support (refer to Non-Patent Document 2) in order to improve convenience and the like when a wireless communication device uses such a plurality of wireless communication systems. Protocols are defined (for example, Non-Patent Documents 1 and 2).
Johnson, D., Perkins, C. and Arkko, J, “Mobility Support in IPv6 RFC3775”, IETF, 2004 Devarapali, V, et al., “Network Mobility (NEMO) Basic Support Protocol, RFC3963”, IETF, 2005

  In handover (specifically, link layer handover) to another wireless communication system in accordance with the conventional IP mobility protocol described above, (1) the wireless communication system (handover source) of the connected wireless communication system The connection is disconnected, (2) connection to the handover destination radio communication system, and (3) handover to the handover destination radio communication system are sequentially executed.

  For this reason, in order to avoid packet loss at the time of a handover to another radio communication system, it is necessary to always connect to a plurality of radio communication systems. That is, there is a problem that the power consumption of the wireless communication device increases and the battery duration is shortened.

  Therefore, the present invention has been made in view of such a situation, and in the case of using a plurality of wireless communication systems having different physical layer methods, the occurrence of packet loss while reducing power consumption. An object of the present invention is to provide a wireless communication method capable of executing a suppressed handover.

In order to solve the problems described above, the present invention has the following features. First, the first feature of the present invention is that it is connected to a first wireless communication system (wireless communication system 110) and a second wireless communication system (wireless communication system 120) different from the first wireless communication system. a wireless communication method for performing radio communication, the communication quality of the first of the first radio link established with the radio communication system (radio link L1) first link layer (link layer 301a) acquires Steps (S103A, S109) and an upper layer (MIH user 313) for determining preparation for handover from the first radio communication system to the second radio communication system, the communication quality from the first link layer Are transmitted to the second wireless communication system and the second wireless communication system based on the request for preparation for handover from the higher layer (S111, S113). And a step (S210) of requesting the setting of the line link (wireless link L2) via the second link layer (link layer 303a).

  According to a second aspect of the present invention, in accordance with the first aspect of the present invention, the first radio link is disconnected after completion of a handover from the first radio communication system to the second radio communication system. The gist is to further include a step (S370).

  A first feature according to another aspect of the present invention includes a first wireless communication system (wireless communication system 110) and a second wireless communication system (wireless communication system 120) different from the first wireless communication system. ) And wireless communication units (wireless communication units 301 and 303) that perform wireless communication, and a mobility management unit that manages mobility from the first wireless communication system to the second wireless communication system ( A wireless communication device (wireless communication terminal 300) including a mobility management unit 304) for acquiring communication quality of the first wireless link (wireless link L1) set with the first wireless communication system. The communication quality acquired by the quality acquisition unit (communication quality acquisition unit 305) and the communication quality acquisition unit is deteriorated with respect to the first threshold (threshold TH1) or the first threshold. A communication quality determination unit (communication quality determination unit 307) for determining whether or not a second threshold value (threshold value TH2) corresponding to the state is exceeded, and from the first wireless communication system to the second wireless communication system A handover control unit (handover control unit 309) that controls a handover, wherein the handover control unit determines that the communication quality determination unit determines that the communication quality has exceeded the first threshold. Connection with the second wireless communication system, the second wireless communication system and the second wireless link (wireless link L2) are set, and the communication quality is set after the second wireless link is set. Performs a handover from the first radio link to the second radio link when it is determined by the communication quality determination unit that the second threshold has been exceeded It is the gist of.

  According to such a wireless communication apparatus, when the communication quality of the first wireless link set with the first wireless communication system exceeds the first threshold, the connection with the second wireless communication system, specifically First, the setting of the second wireless communication system and the second wireless link is started. In addition, after the second radio link is set, when the communication quality of the first radio link exceeds the second threshold corresponding to the state in which the communication quality is deteriorated from the first threshold, the first radio link A handover to the second radio link is performed.

  For this reason, when the communication quality of the first wireless link is good, it is not connected to the second wireless communication system, so that the power consumption of the wireless communication device can be reduced, that is, the battery duration can be extended. it can.

  Also, when the handover is executed based on the fact that the communication quality of the first radio link has exceeded the second threshold, the second radio link has already been set up, so that packet loss at the time of handover, etc. Therefore, it is possible to avoid a significant deterioration in communication quality. Further, when the handover is executed, the second radio link is already set up, so that a quick handover can be realized.

  In the first feature according to the other aspect of the present invention described above, the handover control unit transmits the same packet (IP packet) from the radio communication unit via the first radio link and the second radio link. P) is transmitted simultaneously, and when the wireless communication unit receives a packet via the second wireless link, it is preferable to disconnect the first wireless link.

  In the first or second feature according to the other aspect of the present invention described above, the handover control unit is configured to perform media non-dependence on a physical layer configuration of the first wireless communication system and the second wireless communication system. Including a dependent handover function (MIH function 311), and the media independent handover function executes the handover based on an instruction from a protocol (MIH user 313) positioned at a higher layer than the media independent handover function It is preferable.

  According to still another aspect of the present invention, there is provided a wireless communication method for performing wireless communication by connecting to a first wireless communication system and a second wireless communication system different from the first wireless communication system. Acquiring communication quality of the first radio link set with the first wireless communication system, determining whether the acquired communication quality exceeds a first threshold, and the communication quality Is determined to exceed the first threshold, a step of starting connection with the second wireless communication system, and a state corresponding to a state in which the communication quality is deteriorated compared to the first threshold. And determining whether or not the communication quality has exceeded the second threshold after the second wireless link is set and the step of determining whether or not the second wireless link is set. Previous from link Further comprising the step of performing a handover to a second radio link to subject matter.

  According to the features of the present invention, when using a plurality of wireless communication systems having different physical layer methods, etc., wireless communication capable of executing handover with reduced packet loss while reducing power consumption. A method can be provided.

  Next, an embodiment of the present invention will be described. Specifically, (1) overall schematic configuration of communication network, (2) functional block configuration of wireless communication device, (3) operation of wireless communication device, (4) action / effect, and (5) other embodiments explain.

  In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic and ratios of dimensions and the like are different from actual ones.

  Accordingly, specific dimensions and the like should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

(1) Overall Schematic Configuration of Communication Network FIG. 1 is an overall schematic configuration diagram of a communication network 10 including a radio communication terminal 300 that constitutes a radio communication device in the present embodiment. As shown in FIG. 1, the communication network 10 includes the Internet 100, a wireless communication system 110, and a wireless communication system 120.

  In this embodiment, the wireless communication system 110 is configured by a wireless MAN system. Specifically, the wireless communication system 110 is a wireless communication system compliant with iBurst (registered trademark). The wireless communication system 110 includes a wireless base station 111 that performs wireless communication with the wireless communication terminal 300.

  In this embodiment, the wireless communication system 120 is configured by a mobile phone system. Specifically, the wireless communication system 120 is a third generation mobile phone system using a CDMA system. More specifically, the wireless communication system 120 is a wireless communication system compliant with a method (for example, cdma2000 1x-EVDO) that can execute high-speed IP packet communication. The wireless communication system 120 includes a wireless base station 121 that performs wireless communication with the wireless communication terminal 300.

  A home agent 210 and an IP telephone terminal 220 are connected to the Internet 100.

  The home agent 210 is a home agent compliant with Mobile IPv6. The home agent 210 acquires a care-of address (CoA) from the wireless communication terminal 300. The home agent 210 associates the care-of address acquired from the wireless communication terminal 300 with a home address (HoA) that is a fixed IP address for identifying the wireless communication terminal 300.

  The IP telephone terminal 220 is a telephone terminal using Voice over IP (VoIP). The IP phone terminal 220 transmits and receives VoIP packets via the Internet 100.

  The wireless communication terminal 300 can connect to the wireless communication system 110 and the wireless communication system 120 to perform wireless communication. Specifically, the radio communication terminal 300 can set a radio link L1 with the radio base station 111 and execute radio communication via the radio link L1. Similarly, the radio communication terminal 300 can set a radio link L2 with the radio base station 121 and perform radio communication via the radio link L2.

  Since the wireless communication terminal 300 performs wireless communication by connecting to the wireless communication system 110 and the wireless communication system 120 having at least different physical layer systems, specifically, the two different wireless communication units, specifically, the wireless communication unit 301, 303 (not shown in FIG. 1, refer to FIG. 2).

  In the present embodiment, the wireless communication terminal 300 transmits / receives VoIP packets to / from the IP telephone terminal 220 using either the wireless communication system 110 or the wireless communication system 120 or both wireless communication systems simultaneously. Further, in the present embodiment, the wireless communication terminal 300 uses the wireless communication system 110 (iBurst (registered trademark)) with priority over the wireless communication system 120 (cdma2000 1x-EVDO). The wireless communication terminal 300 uses the wireless communication system 120 when the desired communication quality cannot be ensured and the wireless communication system 110 cannot be used.

  In addition, the wireless communication terminal 300 does not connect to both wireless communication systems for a long time (so-called constant connection) in order to extend the duration of the battery 320.

(2) Functional Block Configuration of Radio Communication Device Next, a functional block configuration of the radio communication terminal 300 constituting the radio communication device in the present embodiment will be described. Specifically, the overall block configuration of radio communication terminal 300 and the protocol stack of the handover control unit will be described.

(2.1) Overall Block Configuration FIG. 2 is a functional block configuration diagram of the wireless communication terminal 300. As shown in FIG. 2, the wireless communication terminal 300 includes a wireless communication unit 301, a wireless communication unit 303, a mobility management unit 304, a communication quality acquisition unit 305, a communication quality determination unit 307, a handover control unit 309, and a battery 320. . Note that here, only the functional blocks related to the present invention will be described, and it should be noted that the wireless communication terminal 300 includes other functional blocks (for example, a baseband processing unit and a user interface unit) not shown.

  The wireless communication unit 301 performs wireless communication conforming to iBurst (registered trademark) used in the wireless communication system 110.

  The wireless communication unit 303 performs wireless communication conforming to cdma2000 1x-EVDO used in the wireless communication system 120.

  The mobility management unit 304 manages mobility from the wireless communication system 110 to the wireless communication system 120 and mobility from the wireless communication system 120 to the wireless communication system 110.

  Specifically, the mobility management unit 304 performs processing necessary to ensure the IP mobility of the wireless communication terminal 300. In the present embodiment, the mobility management unit 304 performs processing necessary to ensure IP mobility of the wireless communication terminal 300 in accordance with NEMO Basic Support.

  As described above, in the present embodiment, the wireless communication terminal 300 uses the wireless communication system 110 (iBurst (registered trademark)) with priority over the wireless communication system 120 (cdma2000 1x-EVDO). That is, when the communication quality of the radio link L1 is good, the radio link L2 is not set and the radio communication terminal 300 and the radio communication system 120 (radio base station 121) are not connected. For this reason, when the communication quality of the radio link L1 is good, the radio communication unit 303 that performs radio communication conforming to cdma2000 1x-EVDO used in the radio communication system 120 extends the duration of the battery 320. Power is not supplied.

  The communication quality acquisition unit 305 acquires the communication quality of the wireless link L1 set with the wireless communication system 110. Further, the communication quality acquisition unit 305 acquires the communication quality of the wireless link L2 set with the wireless communication system 120.

Specifically, the communication quality acquisition unit 305 acquires the following communication quality parameters for the radio link L1.
(A) Signal to interference noise ratio (SINR)
(B) Received electric field strength (RSSI)
(C) Transmission power (d) Uplink and downlink throughput

In addition, the communication quality acquisition unit 305 acquires the following communication quality parameters for the radio link L2.
(A) SINR
(B) RSSI
(C) DRC (Data Rate Control)

  The communication quality determination unit 307 determines whether or not the communication quality acquired by the communication quality acquisition unit 305 exceeds a predetermined threshold value. Specifically, as illustrated in FIG. 5, the communication quality determination unit 307 determines whether the communication quality (specifically, RSSI) acquired by the communication quality acquisition unit 305 exceeds a threshold value TH1 (first threshold value). Determine whether or not. Further, the communication quality determination unit 307 determines whether or not the threshold value TH2 (second threshold value) corresponding to the state in which the communication quality is deteriorated exceeds the threshold value TH1.

In the present embodiment, the communication quality determination unit 307 can set the threshold value TH1 and the threshold value TH2 for the following communication quality parameters regarding the radio link L1.
(A) RSSI
(B) SINR
(C) Transmission data rate (d) Reception data rate

Further, the communication quality determination unit 307 can set the threshold value TH1 and the threshold value TH2 for the following communication quality parameter regarding the radio link L2.
(A) RSSI
(B) Carrier-to-interference ratio (CIR)
(C) Transmission power

  The handover control unit 309 controls handover from the wireless communication system 110 to the wireless communication system 120.

  Specifically, when the communication quality determination unit 307 determines that the communication quality of the radio link L1 exceeds the threshold value TH1, the handover control unit 309 starts connection with the radio communication system 120. Further, the handover control unit 309 sets up the radio communication system 120 and the radio link L2.

  In addition, when the communication quality determination unit 307 determines that the communication quality of the radio link L1 has exceeded the threshold value TH2 after the radio link L2 is set, the handover control unit 309 changes the radio link L1 to the radio link L2. Perform a handover to

  The handover control unit 309 can simultaneously transmit the same packet, specifically, the IP packet P, from the wireless communication unit 301 and the wireless communication unit 303 via the wireless link L1 and the wireless link L2. Further, the handover control unit 309 can disconnect the radio link L1 when the radio communication unit 303 receives the IP packet P via the radio link L2.

  The battery 320 supplies power necessary for the operation of each functional block constituting the wireless communication terminal 300.

(2.2) Protocol Stack of Handover Control Unit FIG. 3 shows a protocol stack 310 executed by the mobility management unit 304, the communication quality acquisition unit 305, the communication quality determination unit 307, and the handover control unit 309. As shown in FIG. 3, the protocol stack 310 includes a link layer 301a, a link layer 303a, an MIH (Media Independent Handover) function 311 and an MIH user 313.

  The link layer 301 a provides an interface (device driver) function with the wireless communication unit 301. As having. Similarly, the link layer 303a provides an interface (device driver) function of the wireless communication unit 303.

  The MIH function 311 is a media-independent handover function that does not depend on the configuration of the physical layer of the wireless communication system 110 and the wireless communication system 120. In this embodiment, the MIH function 311 is configured by a media-independent handover function defined in IEEE802.21. In the present embodiment, the MIH function 311 supports the function of the handover control unit 309.

  The MIH function 311 executes a handover from the radio link L1 to the radio link L2 based on an instruction from the MIH user 313, which is a protocol positioned at a higher layer than the MIH function 311.

  The MIH function 311 receives a LINK event from the link layers 301a and 303a, and transmits a LINK command including a communication quality acquisition request and a handover instruction.

  The MIH user 313 is positioned in an upper layer of the MIH function 311. The MIH user 313 executes communication with the MIH function 311. In this embodiment, the MIH user 313 is configured by NEMO Basic Support or the like. The MIH user 313 includes Multiple Care-of Address Registration (MCoA), which is an extended specification of Mobile IPv6 / NEMO Basic Support.

  Furthermore, the functions of the communication quality acquisition unit 305 and the communication quality determination unit 307 are supported by the MIH user 313.

  Specifically, the MIH user 313 receives an MIH event from the MIH function 311 or transmits an MIH command including a communication quality acquisition request unit and a handover instruction unit.

(3) Operation of Radio Communication Device Next, the operation of the radio communication terminal 300 constituting the radio communication device in the present embodiment will be described with reference to FIG. 4 and FIG. Specifically, an operation in which the radio communication terminal 300 performs a handover from the radio communication system 110 to the radio communication system 120 will be described.

  FIG. 4 is a diagram showing an internal sequence when the radio communication terminal 300 executes a handover from the radio communication system 110 to the radio communication system 120. Here, it is assumed that radio communication terminal 300 sets radio link L1 with radio communication system 110 (radio base station 111) and transmits / receives VoIP packets to / from IP telephone terminal 220.

  FIG. 5 is a diagram illustrating time transition of communication quality of radio signals transmitted from the radio communication system 110 (wireless MAN system) and the radio communication system 120 (cellular phone system).

  As shown in FIG. 4, in step S101, the MIH user 313 requests the MIH function 311 to acquire the communication quality of the radio link L1. Specifically, the MIH user 313 transmits MIH_Get_Status.request, which is an MIH command requesting acquisition of communication quality, to the MIH function 311.

  In step S103, the MIH function 311 requests the link layer 301a to acquire the communication quality of the radio link L1. Specifically, the MIH function 311 transmits Link_Get_Parameters.request, which is a LINK command for requesting acquisition of communication quality, to the link layer 301a.

  In step S103A, the link layer 301a transmits a communication quality acquisition request to the wireless communication unit 301 based on Link_Get_Parameters.request received from the MIH function 311. Here, RSSI is acquired as the communication quality of the radio link L1.

  In step S109, based on the communication quality acquisition request received from the link layer 301a, the wireless communication unit 301 transmits the RSSI of the wireless signal constituting the wireless link L1 to the link layer 301a.

  In step S <b> 111, the link layer 301 a transmits the RSSI received from the wireless communication unit 301 to the MIH function 311. Specifically, the link layer 301 a transmits Link_Get_Parameters.confirm, which is a LINK event including RSSI received from the wireless communication unit 301, to the MIH function 311.

  In step S113, the MIH function 311 transmits the RSSI received from the link layer 301a to the MIH user 313. Specifically, the MIH function 311 transmits MIH_Get_Status.confirm, which is an MIH event including RSSI received from the link layer 301a, to the MIH user 313.

  Moreover, in this embodiment, the process of step S101-S113 mentioned above is repeated every 500 ms. Further, the link layer 301a avoids erroneously determining that the threshold value TH1 (see FIG. 5) has been exceeded due to RSSI fluctuations caused by fading of the radio signals that configure the radio link L1, so The communication quality (for example, RSSI) values acquired from the above are averaged in units of 500 ms, and the averaged communication quality values are transmitted to the MIH function 311. The link layer 303a can operate in the same manner as the link layer 301a.

  In step S200, the MIH user 313 determines that the communication quality of the radio link L1 has exceeded the threshold value TH1 (communication quality degradation threshold value). Specifically, the MIH user 313 determines that the communication quality of the radio link L1 has exceeded the threshold value TH1 based on the RSSI included in MIH_Get_Status.confirm received from the MIH function 311. In the present embodiment, “exceeding the threshold value TH1” means that the RSSI has fallen below a predetermined value (hereinafter the same).

Specifically, as shown in FIG. 5, at the timing _{t 1,} the communication quality of the wireless communication system 110 (wireless MAN system), i.e., RSSI of the radio link L1 exceeds the threshold TH1 (i.e., below) Determined.

  In step S210, the MIH user 313 requests the MIH function 311 to prepare for handover. Specifically, the MIH user 313 transmits MIH_Handover_Prepare.request, which is an MIH command requesting preparation for handover, to the MIH function 311.

  In step S220, the MIH function 311 requests the link layer 303a to set the radio link L2 based on MIH_Handover_Prepare.request received from the MIH user 313. Specifically, the MIH function 311 transmits Link_UP.request, which is a LINK command for requesting setting of a radio link, to the link layer 303a.

  In step S230, the link layer 303a starts setting of the radio link L2 based on the Link_UP.request received from the MIH function 311. Specifically, the link layer 303 a causes the wireless communication unit 303 that has not been supplied with power to be supplied with power from the battery 320 and activates the wireless communication unit 303. The wireless communication unit 303 activated by the link layer 303a starts connection (setting of a PPP connection) with the wireless communication system 120 via the wireless base station 121.

  When the wireless link L2 is set by the process of step S230, the wireless communication terminal 300 is connected to both the wireless communication system 110 and the wireless communication system 120.

  In step S240, the link layer 303a transmits to the MIH function 311 that the radio link L2 has been set. Specifically, the link layer 303a transmits Link_UP.indication, which is a LINK event indicating that a radio link is set, to the MIH function 311.

As shown in FIG. 5, the setting of the radio link L2 is completed at timing _{t 2,} the wireless communication unit 303 receives a radio signal from the wireless communication system 120 (the radio base station 121).

  In step S250, the MIH function 311 notifies the MIH user 313 that preparation for handover has been completed based on the Link_UP.indication received from the link layer 303a. Specifically, the MIH function 311 transmits MIH_Handover_Prepare.confirm, which is an MIH event indicating that the preparation for handover has been completed, to the MIH user 313.

  Note that the MIH user 313 that has received MIH_Handover_Prepare.confirm obtains a handover destination, that is, a CoA assigned to the radio communication terminal 300 in the radio communication system 120.

  In step S300, as link status acquisition processing, the same processing as in steps S101 to S113 (the portion within the dotted frame in the figure) is repeated every 500 ms. In step S300, the communication quality of the radio link L2 is acquired by the same processing as in steps S101 to S113. That is, the link layer 303 a transmits a communication quality acquisition request to the wireless communication unit 303 based on a request from the MIH function 311. Here, RSSI is acquired as the communication quality of the radio link L2.

  In step S310, the MIH user 313 determines that the communication quality of the radio link L1 has exceeded the threshold value TH2 (handover threshold value). Specifically, the MIH user 313 determines that the communication quality of the radio link L1 has exceeded the threshold value TH2 based on the RSSI included in MIH_Get_Status.confirm received from the MIH function 311.

  In step S320, the MIH user 313 requests the MIH function 311 to perform handover from the radio link L1 to the radio link L2. Specifically, the MIH user 313 transmits MIH_Switch, which is an MIH command requesting handover, to the MIH function 311.

  In step S330, the MIH function 311 performs a handover from the radio link L1 to the radio link L2. Specifically, the MIH function 311 switches from transmission of the IP packet P (for example, VoIP packet) via the radio link L1 to transmission of the IP packet P via the radio link L2.

As shown in FIG. 5, the cutting of the radio link L1 is completed at timing t _3, the wireless communication unit 301 stops the reception of the radio signal transmitted from the wireless communication system 110 (the radio base station 111).

  Note that the MIH function 311 may transmit the same IP packet P via the radio link L1 and the radio link L2 until the IP packet P is received via the radio link L2.

  In step S340, the MIH function 311 requests the MIH user 313 to commit the handover to the MIH user 313. Specifically, the MIH function 311 transmits MIH_Commit.request, which is an MIH event requesting handover commit, to the MIH user 313.

  In step S350, based on the reception of MIH_Commit.request from the MIH function 311, the MIH user 313 transmits a handover commit from the radio link L1 to the radio link L2 to the MIH function 311. Specifically, the MIH user 313 transmits MIH_HandoverComplete.request, which is an MIH command indicating the handover commitment, to the MIH function 311.

  In step S360, the MIH function 311 requests the link layer 301a to disconnect the radio link L1 based on the reception of MIH_HandoverComplete.request from the MIH user 313. Specifically, the MIH function 311 transmits Link_Teardown.request, which is a LINK command for requesting disconnection of the radio link, to the link layer 301a.

  In step S370, the link layer 301a disconnects the radio link L1 based on the Link_Teardown.request received from the MIH function 311. Specifically, the wireless communication unit 301 that has received a wireless link disconnection instruction from the link layer 301 a disconnects the connection (PPP connection) with the wireless communication system 110. In addition, after the connection is disconnected, the supply of power to the wireless communication unit 301 is stopped.

  In step S380, the link layer 301a transmits to the MIH function 311 that the radio link L1 has been disconnected. Specifically, the link layer 301a transmits Link_Teardown.response, which is a LINK event indicating that the radio link is disconnected, to the MIH function 311.

  In step S390, the MIH function 311 notifies the MIH user 313 that the radio link has been disconnected based on the Link_Teardown.response received from the link layer 301a. Specifically, the MIH function 311 transmits MIH_HandoverComplete.response, which is an MIH event indicating that the radio link is disconnected, to the MIH user 313.

(4) Operation / Effect According to the wireless communication terminal 300, when the communication quality of the wireless link L1 set with the wireless communication system 110 exceeds the threshold value TH1, connection with the wireless communication system 120, specifically, wireless Setting of the communication system 120 and the radio link L2 is started. Further, after the wireless link L2 is set, when the communication quality of the wireless link L1 exceeds the threshold value TH2 corresponding to the state in which the wireless link L1 is deteriorated from the threshold value TH1, the handover from the wireless link L1 to the wireless link L2 is executed. .

  For this reason, when the communication quality of the wireless link L1 is good, the wireless communication system 120 is not connected. More specifically, since power is not supplied to the wireless communication unit 303, the power consumption of the wireless communication terminal 300 can be reduced, that is, the duration of the battery 320 can be extended.

  Further, when the handover is executed based on the fact that the communication quality of the radio link L1 exceeds the threshold value TH2, since the radio link L2 has already been set, a significant communication quality such as a packet loss at the time of handover can be obtained. Degradation can be avoided. Furthermore, when the handover is executed, the radio link L2 has already been set, so that a quick handover can be realized.

  In the present embodiment, the handover control unit 309 causes the same IP packet P to be simultaneously transmitted from the wireless communication unit 301 and the wireless communication unit 303 via the wireless link L1 and the wireless link L2, and the wireless communication unit 303 transmits the wireless link L2 When the IP packet P is received via the wireless link L1, the wireless link L1 can be disconnected. For this reason, packet loss during handover can be avoided more reliably.

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

  For example, in the above-described embodiment, the handover from the wireless communication system 110 (wireless link L1) to the wireless communication system 120 (wireless link L2) has been described, but the handover from the wireless communication system 120 to the wireless communication system 110 is similarly performed. May be executed.

  In the embodiment described above, the wireless communication system 110 compliant with iBurst (registered trademark) and the wireless communication system 120 compliant with cdma2000 1x-EVDO are used. However, the wireless communication system 110 and the wireless communication system 120 are used. The method is not limited to iBurst (registered trademark) or cdma2000 1x-EVDO. For example, the wireless communication system 110 may be a wireless communication system compliant with mobile WiMAX. Further, in the case of Mobile IP or the like, a process for registering the acquired CoA may be executed after the radio link is set in step S230 described above.

  Further, the number of wireless communication systems included in the communication network 10 may be further increased.

  In the above-described embodiment, power is not supplied to a wireless communication unit that is not used. However, a state where power is supplied to the wireless communication unit, specifically, a sleep state (dormant state) may be used.

  As described above, the present invention naturally includes various embodiments that are not described herein. Therefore, the technical scope of the present invention is defined only by the invention specifying matters according to the scope of claims reasonable from the above description.

1 is an overall schematic configuration diagram of a communication network including a wireless communication device according to an embodiment of the present invention. It is a functional block block diagram of the radio | wireless communication apparatus which concerns on embodiment of this invention. It is a figure which shows the protocol stack mounted in the radio | wireless communication apparatus which concerns on embodiment of this invention. It is a figure which shows the internal sequence when the radio | wireless communication apparatus which concerns on embodiment of this invention performs a hand-over. It is a figure which shows the time transition of the communication quality of the radio signal transmitted from the radio | wireless communications system which concerns on embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Communication network, 100 ... Internet, 110 ... Wireless communication system, 111 ... Wireless base station, 120 ... Wireless communication system, 121 ... Wireless base station, 210 ... Home agent, 220 ... IP telephone terminal, 300 ... Wireless communication terminal, 301, 303: Wireless communication unit, 301a, 303a ... Link layer, 304 ... Mobility management unit, 305 ... Communication quality acquisition unit, 307 ... Communication quality determination unit, 309 ... Handover control unit, 310 ... Protocol stack, 311 ... MIH function, 313 ... MIH user, 320 ... battery, P ... IP packet, L1 ... radio link, L2 ... wireless _{links, t} 1 ~t 3 _... timing, TH1, TH2 ... threshold

Claims (2)

A wireless communication method for performing wireless communication by connecting to a first wireless communication system and a second wireless communication system different from the first wireless communication system,
A step of the communication quality of the first radio link established with the first radio communication system is the first link layer acquires,
Transmitting the communication quality from the first link layer to an upper layer that determines preparation for handover from the first wireless communication system to the second wireless communication system;
A wireless communication method comprising: requesting setting of the second wireless communication system and a second wireless link via the second link layer based on the handover preparation request from the upper layer.   The wireless communication method according to claim 1, further comprising: disconnecting the first wireless link after completion of a handover from the first wireless communication system to the second wireless communication system.

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