JP4399016B2 - Mobile communication terminal, communication apparatus, mobile communication method and communication method - Google Patents

Description

  The present invention relates to a mobile communication terminal, a communication apparatus, a mobile communication method, and a communication method for establishing a communication link by PPP (Point-to-Point Protocol) with a communication partner.

  As a communication technology that transmits and receives packets using a plurality of communication routes, there is an IP mobility technology that supports route changes accompanying changes in IP (Internet Protocol) addresses. Mobile IP (see Non-Patent Document 1) is a representative protocol of IP mobility technology. Mobile IP is a technology that supports mobility in a network layer, and a communication terminal notifies a home agent of an IP address change and communicates with a communication partner via the home agent. This IP address change process may cause communication interruption or instantaneous interruption.

  There is also a method called multilink PPP that aggregates a plurality of communication links into one communication link (see Non-Patent Document 2). In multilink PPP, since it looks like a single communication path when viewed from a layer 3 protocol such as IP, the IP address is not changed even if the communication path is switched. If this multi-link PPP is used, a plurality of communication links can be used on a single communication path in terms of IP. However, multilink PPP is usually designed to establish a high-speed link by aggregating multiple low-speed communication links, assuming that the quality of all communication links is constant, etc. It is.

There has also been proposed a method in which this multi-link PPP is extended to add a control function for distributing packets to communication links having different communication qualities (see Patent Documents 1 and 2). If these methods are used, packets can be efficiently transmitted by aggregating communication links having different communication qualities.
IETF RFC3344 “IP MobilitySupport for IPv4” IETF RFC1717 “The PPPMultilink Protocol (MP)” JP 2000-216815 A JP 2007-60494 A

  The above-described multilink PPP is intended to widen the communication path and does not provide handover between radio links. In other words, the above-described method does not provide a mechanism that can add a wireless link that has become newly valid during communication or exclude a wireless link that has become invalid. As a result, in the above-described method, there is a possibility that PPP communication cannot be continued properly in an environment where the terminal moves and the communication environment changes as needed.

  The present invention has been made in order to solve the above-described problems, and is a movement that enables communication by PPP to be appropriately continued even in an environment in which the terminal moves and the communication environment changes as needed. An object is to provide a communication terminal, a communication device, a mobile communication method, and a communication method.

  In order to achieve the above object, a mobile communication terminal according to the present invention includes a plurality of wireless access means for establishing a communication link by PPP for wireless communication with different schemes with a communication partner, and a plurality of wireless access. Aggregation means for aggregating communication links established by the means, detection means for detecting that wireless communication is possible for at least one of the plurality of wireless access means, and wireless communication by the detection means Control means for controlling the wireless access means detected to establish a communication link.

  In the mobile communication terminal according to the present invention, a PPP communication link for wireless communication with a different method is established with a communication partner by a plurality of wireless access means, and the established communication links are aggregated. Thereby, communication using a plurality of communication links as one communication path is performed between the mobile communication terminal according to the present invention and the communication partner. Further, it is detected that wireless communication is possible for at least one of wireless access means that perform wireless communication with different systems, and a communication link is established by the detected wireless access means. Thereby, according to the mobile communication terminal according to the present invention, effective communication links can be aggregated at any time, so that communication by PPP is appropriately continued even in an environment where the terminal moves and the communication environment changes as needed. It becomes possible to do.

  It is desirable that one of the wireless access means acquires an IP address, establishes L2 tunneling with the communication partner using the IP address, and establishes a communication link via the L2 tunneling. According to this configuration, a communication link can be established even when a PPP communication link cannot be established directly with a communication partner. Thereby, the redundancy of a communication link can be improved and it becomes possible to continue communication more appropriately.

  The detecting means detects that the communication link established by the wireless access means has become invalid for at least one of the plurality of wireless access means, and the aggregation means has been invalidated by the detecting means. It is desirable to exclude detected communication links. According to this configuration, it is possible to appropriately manage the communication link in the mobile communication terminal.

  The mobile communication terminal includes a measuring unit that measures the radio field intensity of the communication link established by the radio access unit, a switching unit that switches a communication link that transmits a packet based on the radio field intensity measured by the measuring unit, and a switching unit Thus, it is desirable to further comprise notification means for notifying the other party of the communication when the communication link for transmitting the packet is switched. According to this configuration, it is possible to efficiently and appropriately transmit a packet to a communication partner, such as preventing packet loss due to deterioration of radio field intensity.

  The mobile communication terminal transmits a packet based on a communication link change accepting unit that accepts a request for changing a communication link that transmits a packet from a communication partner, and a request for changing the communication link accepted by the communication link change accepting unit. It is preferable to further include a switching unit that switches the communication link to be notified, and a notification unit that notifies the communication partner when the communication link that transmits the packet is switched by the switching unit. According to this configuration, it is possible to efficiently and appropriately transmit a packet to a communication partner based on a request from the communication partner according to the usage status of the communication line.

  A communication apparatus according to the present invention includes a plurality of communication means for establishing a communication link by PPP of communication of different methods with a communication partner, and an aggregation means for aggregating communication links established by a plurality of communication means. Monitoring means for monitoring the communication status of at least one of the plurality of communication means, and communication requesting the communication partner to change the communication link for transmitting packets based on the communication status monitored by the monitoring means Link change requesting means.

  In the communication apparatus according to the present invention, the mobile communication terminal as a communication partner is requested to change the communication link for transmitting packets according to the communication status such as the usage status of the communication line. Therefore, according to the communication apparatus according to the present invention, the communication line can be efficiently used, and the mobile communication terminal can efficiently and appropriately transmit the packet to the communication partner (self apparatus).

  By the way, the present invention can be described as an invention of a mobile communication terminal and a communication apparatus as described above, and can also be described as an invention of a mobile communication method and a communication method as follows. This is substantially the same invention only in different categories, and has the same operations and effects.

  That is, the mobile communication method according to the present invention is a mobile communication method in a mobile communication terminal comprising a plurality of wireless access means for establishing a communication link by PPP of wireless communication with different methods with a communication partner, An aggregation step of aggregating communication links established by a plurality of wireless access means, a detection step of detecting that wireless communication is possible for at least one of the plurality of wireless access means, and wireless communication by the detection means And a control step of controlling the wireless access means detected to be possible to establish a communication link.

  The communication method according to the present invention is a communication method in a communication apparatus including a plurality of communication means for establishing a communication link by PPP with a communication method different from each other with a communication partner. An aggregation step for aggregating established communication links, a monitoring step for monitoring a communication status of at least one of a plurality of communication means, and a packet to a communication partner based on the communication status monitored in the monitoring step And a communication link change requesting step for requesting a change of the communication link for transmitting.

  According to the present invention, communication links that are valid at any time can be aggregated, so that it is possible to appropriately continue communication using PPP even in an environment where the terminal moves and the communication environment changes as needed.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of a mobile communication terminal, a communication apparatus, a mobile communication method, and a communication method according to the present invention will be described in detail with reference to the drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 1 shows configurations of the mobile communication terminal 10 and the fixed communication device 20 according to the present embodiment. The mobile communication terminal 10 is a device that can connect to a plurality of communication networks N1 and N2 and perform a plurality of wireless communications with different methods, and specifically corresponds to a mobile phone or the like. Examples of communication networks to which the mobile communication terminal 10 can be connected include a telephone network N1 and the Internet N2. As will be described later, the telephone network N1 is connected via mobile communication (W-CDMA (Wideband Code Division Multiple Access)) and the Internet N2 via a wireless LAN (Local Area Network).

  The mobile communication terminal 10 can also establish a communication link by PPP of the above wireless communication with a communication partner, and can send and receive packets to and from the communication partner through the communication link. As shown in FIG. 1, specifically, for example, the mobile communication terminal 10 establishes a communication link with a fixed communication device 20 connected to the communication networks N1 and N2 by wire and transmits / receives packets. Can do. Here, between the mobile communication terminal 10 and the fixed communication device 20, as will be described in more detail, a communication link based on PPP of wireless communication with different methods can be established. That is, the communication system according to the present embodiment has a configuration according to the multilink PPP communication system.

  The fixed communication device 20 is a communication device that is connected to a plurality of communication networks N1 and N2 by wire, and can connect to the communication networks N1 and N2 to perform a plurality of communications with different methods. Specifically, for example, it corresponds to a PPP access server. As described above, the fixed communication device 20 establishes a PPP communication link (PPP connection) via the communication networks N1 and N2 with the mobile communication terminal 10, and performs communication using the communication link.

  Next, more detailed functional configurations of the mobile communication terminal 10 and the fixed communication device 20 will be described. As shown in FIG. 1, the mobile communication terminal 10 includes a W-CDMA communication modem 11, a wireless LAN adapter 12, an L2TP (Layer 2 Tunneling Protocol) virtual device 13, a PPP device 14, and an IP layer 15. A wireless LAN searching unit 16 and a wireless LAN radio wave intensity measuring unit 17 are provided. In addition, the mobile communication terminal 10 usually has components such as a mobile phone in addition to the functional components described above. The fixed communication apparatus 20 includes an ISDN modem 21, an Ethernet (registered trademark) adapter 22, an L2TP virtual device 23, a PPP device 24, and an IP layer 25.

  The W-CDMA communication modem 11 is a wireless access unit that performs wireless communication by the W-CDMA system and establishes a communication link by PPP of the wireless communication with the fixed communication device 20. Specifically, the W-CDMA communication modem 11 connects to the telephone network N1 by wireless communication using the W-CDMA method, and transmits a PPP connection request to the fixed communication device 20 connected to the telephone network N1 through the telephone network N1. The PPP communication link (PPP connection) is established. In the fixed communication device 20, an ISDN (Integrated Services Digital Network) modem 21 has a function of connecting to the telephone network N1, receives a PPP connection request from the W-CDMA communication modem 11, and receives a W-CDMA communication modem. 11 establishes a communication link with the terminal 11. In other words, the ISDB modem 21 included in the fixed communication device 20 is a communication unit that establishes a PPP communication link with the mobile communication terminal for ISDN communication. An IP address related to the fixed communication device 20 is set in the ISDB modem 21. When establishing a communication link, the W-CDMA communication modem 11 acquires a predetermined IP address. Communication links established by the W-CDMA communication modem 11 are managed by the PPP device 14 in an aggregated manner.

  The wireless LAN adapter 12 is a function of wireless access means for performing wireless communication by a wireless LAN method and connecting to the Internet N2 (through a wireless LAN). The wireless LAN adapter 12 acquires an IP address from the Internet N2. The acquisition of the IP address is performed by control using a protocol such as DHCP (Dynamic Host Configuration Protocol) from the IP layer 15. This IP address is acquired in order to establish a communication link by PPP as will be described later.

  The L2TP virtual device 13 establishes L2TP tunneling (L2 tunneling) with the fixed communication device 20 using the IP address acquired by the wireless LAN adapter 12, and establishes a communication link by PPP via the L2TP tunneling. This is a function of wireless access means. Specifically, the L2TP virtual device 13 establishes L2TP tunneling by transmitting an L2TP connection request to the fixed communication device 20 connected to the Internet N2 through the Internet N2 via the wireless LAN adapter. In the fixed communication apparatus 20, the L2TP virtual device 23 receives an L2TP connection request from the mobile communication terminal 10 via the Ethernet adapter 22 connected to the Internet N2, and establishes L2TP tunneling with the L2TP virtual device 13. Process.

  Subsequently, a process of establishing a PPP communication link via the established L2TP tunneling is performed between the L2TP virtual device 13 and the Ethernet adapter 22. When establishing the communication link, the L2TP virtual device 23 acquires the same IP address as that acquired by the W-CDMA communication modem 11 (different from the IP address acquired by the wireless LAN adapter 12). This is because a single PPP device 14 aggregates a plurality of communication links. Communication links established by the L2TP virtual device 13 are aggregated and managed by the PPP device 14.

  That is, the Ethernet adapter 22 included in the fixed communication device 20 is a function of a communication unit that performs communication using the Ethernet method and connects to the Internet N2. An IP address related to the fixed communication device 20 is set in the Ethernet adapter 22. In addition, the L2TP virtual device 23 included in the fixed communication device 20 is connected to the Ethernet adapter 22, and as described above, L2TP tunneling is performed between the mobile communication terminal 10 and the IP address set in the Ethernet adapter 22. This is a function of communication means for establishing (L2 tunneling) and establishing a communication link by PPP via the L2TP tunneling.

  As described above, the mobile communication terminal 10 establishes two PPP communication links, that is, the communication link established by the W-CDMA communication modem 11 and the communication link established by the wireless LAN adapter 12 and the L2TP virtual device 13. Can be done.

  When the L2TP virtual device 13 establishes the communication link (second communication link) when the PPP communication link (first communication link) is established by the W-CDMA communication modem 11, it is normal. Unlike PPP connection, only LCP (Link Control Protocol) steps are performed, and authentication and NCP (Network Control Protocol) are omitted.

  The PPP device 14 is an aggregation unit that aggregates communication links established by a plurality of radio access units. As a result, the same IP address can be supplied by a plurality of PPP communication links. The aggregation of a plurality of communication links is performed in the same manner as multilink PPP.

  The PPP device 14 transmits the packet input from the IP layer 15 to the fixed communication device 20 through any established communication link, and receives the packet from the fixed communication device 20 through any established communication link. The received packet is received and output to the IP layer 15. The PPP device 14 transmits and receives packets via each wireless access means (serial communication device) 11, 12, 13. Accordingly, the PPP device 14 can use a plurality of communication paths by holding pointers to a plurality of serial communication devices. In addition, all the serial communication devices hold a point to the common PPP device 14, and packets from any communication link can be received by one PPP device 14. When a plurality of communication links are established, the PPP device 14 sets a communication link used for packet transmission.

  When the PPP device 14 receives a notification from the invalid wireless LAN searching unit 16 that a wireless LAN access point with which the wireless LAN adapter 12 can communicate is detected, as will be described later, the wireless LAN adapter 14 12 and L2TP virtual device 13 are also control means for controlling to establish a communication link (control to IP layer 15 is also performed to obtain an IP address).

  In addition, the PPP device 14 receives a notification of the radio field strength of the communication link established by the wireless LAN adapter 12 and the L2TP virtual device 13 from the wireless LAN radio field strength measurement unit 17 as described later, and based on the radio field strength. Take control. The PPP device 14 detects that the communication link is invalid based on the radio wave intensity. Specifically, the PPP device 14 detects that the communication link has become invalid when the radio wave intensity is lower than a predetermined threshold or when the radio wave cannot be received. That is, the PPP device 14 is a function of detection means for detecting that the communication link has become invalid.

  When the PPP device 14 detects that the communication link has become invalid, the PPP device 14 switches the communication link used for packet transmission to the communication link by the W-CDMA communication modem 11. That is, the PPP device 14 is a switching unit that switches a communication link that transmits a packet based on the measured radio wave intensity. The PPP device 14 is also a notification means for notifying the fixed communication device 20 when a communication link for transmitting a packet is switched. The notification is performed by transmitting a communication link change request to the fixed communication device 20 through the communication link before or after switching. Further, the PPP device 14 excludes communication links that have been detected to be invalid.

  Note that the switching of the communication link described above is not necessarily performed when the communication link is invalidated, but also when the measured radio field intensity is higher than a predetermined (first) switching threshold. May be. In addition, when the measured radio field intensity is higher than a predetermined (second) switching threshold, and the packet transmission by the communication link by the W-CDMA communication modem 11 is performed at that time, The communication link established by the wireless LAN adapter 12 and the L2TP virtual device 13 may be switched.

  The IP layer 15 is means for performing communication processing according to IP. Specifically, the packet to be transmitted to the PPP device 14 is output and the received packet is input. In addition, as described above, an IP address is acquired. An API (Application Program Interface) from the IP layer 15 to the PPP device 14 can select a communication link in packet transmission. Accordingly, a communication link used for packet transmission can be selected according to the value and characteristics of information transmitted from an upper layer (application).

  The fixed communication apparatus 20 is also provided with a PPP device 24 and an IP layer 25, and has functions corresponding to the PPP device 14 and the IP layer 15 of the mobile communication terminal 10. That is, the PPP device 24 is connected to the ISDN modem 21 and the L2TP virtual device 23, and is an aggregation unit that aggregates communication links established by the ISDN modem 21, the Ethernet adapter 22, and the L2TP virtual device 23.

  The effective wireless LAN search unit 16 is a means for searching for a wireless LAN access point (effective wireless LAN access point) with which the wireless LAN adapter 12 can communicate. That is, the effective wireless LAN search unit 16 is a detection unit that detects that wireless communication by the wireless access unit is possible. Specifically, the effective wireless LAN search unit 16 monitors the wireless LAN adapter 12 to determine whether or not a radio wave from a wireless LAN access point is received, and performs the above search. When the effective wireless LAN search unit 16 detects a wireless LAN access point with which the wireless LAN adapter 12 can communicate, the effective wireless LAN search unit 16 notifies the PPP device 14 to that effect.

  The detection of whether wireless communication is possible may be performed for at least one of the plurality of wireless access means 11 and 12. For example, in the present embodiment, whether or not wireless communication by the wireless LAN is possible is detected, but a configuration in which wireless communication by the W-CDMA communication modem 11 is similarly detected may be employed.

  The wireless LAN radio field intensity measurement unit 17 is a measurement unit that measures the radio field intensity of the communication link established by the wireless LAN adapter 12 and the L2TP virtual device 13. The wireless LAN radio field intensity measurement unit 17 notifies the measured radio field intensity to the PPP device 14. The information on the radio field intensity is used to detect that the communication link has become invalid. That is, the wireless LAN radio wave intensity measuring unit 17 is a function of a detecting unit that detects that the established communication link is invalid. Further, the information on the radio wave intensity is used to determine switching of the communication link used for packet transmission. The above is the functional configuration of the mobile communication terminal 10 according to the present embodiment.

  FIG. 2 shows a hardware configuration of the mobile communication terminal 10. As shown in FIG. 2, a mobile communication terminal 10 includes a CPU (Central Processing Unit) 101, a RAM (Random Access Memory) 102 and a ROM 103 (Read Only Memory) that are main storage devices, an operation unit 104, a wireless communication unit 105, a display. 106 and hardware such as an antenna 107. The wireless communication unit 105 is usually provided for each wireless communication method. By operating these components, the functions of the mobile communication terminal 10 described above and described later are exhibited.

  FIG. 8 shows a hardware configuration of the fixed communication device 20. As shown in FIG. 8, the fixed communication device 20 includes hardware such as a CPU 201, a RAM 202 and a ROM 203 which are main storage devices, a communication module 204 which is a data transmission / reception device such as a network card, and an auxiliary storage device 205 such as a hard disk. It is configured as a computer equipped. When these components operate, the functions described above and described later of the fixed communication device 20 are exhibited.

  Subsequently, processing (mobile communication method) executed in the mobile communication terminal 10 (and the fixed communication device 20) according to the present embodiment will be described with reference to the sequence diagrams of FIGS. This process is performed when the mobile communication terminal 10 transmits / receives a packet to / from the fixed communication device 20 through a PPP communication link, triggered by a user operation on the mobile communication terminal 10 or the like. The fixed communication device 20 as a communication partner is also designated at that time.

  In the mobile communication terminal 10, the W-CDMA communication modem 11 transmits a PPP connection request to the fixed communication device 20 through the telephone network N1 (S101). In the fixed communication device 20, the PPP connection request is received by the ISDN modem 21 (S131), and the first PPP connection is established between the mobile communication terminal 10 and the fixed communication device 20. The established first PPP connection is managed by the PPP device 14. At this time, the PPP device 14 sets a first PPP connection as a communication link for transmitting packets.

  Using the first PPP connection, the mobile communication terminal 10 and the fixed communication device 20 start communication. However, since the bandwidth of the W-CDMA communication link is narrow, when the wireless LAN becomes available, it is better to switch to the wireless LAN communication link with a wider bandwidth for communication. For this purpose, the following processing is performed in the present embodiment.

  In the mobile communication terminal 10, the effective wireless LAN search unit 16 searches for an effective access point (S102, detection step). This search is always performed. When the mobile communication terminal 10 moves into the wireless LAN service area and the effective wireless LAN search unit 16 detects a valid access point, the effective wireless LAN search unit 16 notifies the PPP device 14 to that effect. (S103, control step). When a valid access point is not detected (S103), an access point search is repeated.

  When a valid access point is detected in the PPP device 14, processing for establishing a second PPP connection is performed as described below under the control of the PPP device 14. First, the IP layer 15 uses a protocol such as DHCP to obtain an IP address for the wireless LAN adapter 12. Subsequently, an L2TP connection request for establishing L2TP tunneling between the IP address and the IP address assigned to the Ethernet adapter 22 of the fixed communication device 20 is sent from the L2TP virtual device 13 to the fixed communication device 20. It is transmitted (S104, control step). In the fixed communication device 20, the L2TP virtual device 23 receives the L2TP connection request via the Ethernet adapter 22, and establishes L2TP tunneling (S132).

  Subsequently, in the mobile communication terminal 10, a PPP connection request for the second PPP connection is transmitted by the L2TP virtual device 13 to the fixed communication device 20 via L2 tunneling (S105, control step). In the fixed communication device 20, the PPP connection request is received by the L2TP virtual device 23 via the Ethernet adapter 22, and the second PPP connection is established between the mobile communication terminal 10 and the fixed communication device 20 (S133). ). Here, the IP address related to the second PPP connection is the same as the IP address related to the first PPP connection.

  Subsequently, in the mobile communication terminal 10, the PPP device 14 aggregates the second PPP connection and the first PPP connection (S106, aggregation step). Also, the PPP device 14 switches the communication link for transmitting packets from the first PPP connection (W-CDMA communication link) to the second PPP connection (wireless LAN communication link) (S107, switching step). On the other hand, also in the fixed communication apparatus 20, the second PPP connection and the first PPP connection are aggregated by the PPP device 24 (S134, aggregation step).

  Subsequently, in the mobile communication terminal 10, the PPP device 14 transmits a link change request to the wireless LAN communication link to the fixed communication device 20 (S108, notification step). In the fixed communication apparatus 20, the PPP device 24 receives the link change request, and the communication link for transmitting the packet changes from the first PPP connection (W-CDMA communication link) to the second PPP connection (Internet communication). Link) (S135).

  Through the series of processes described above, the mobile communication terminal 10 can switch the PPP communication to the wireless LAN after entering the wireless LAN service area, thereby enabling broadband communication.

  Next, an example in which the mobile communication terminal 10 has moved out of the wireless LAN service area will be described with reference to the sequence diagram of FIG.

  In the mobile communication terminal 10, the wireless LAN radio wave intensity measuring unit 17 periodically measures the radio wave intensity from the access point of the wireless LAN used for communication during communication. The measured radio field intensity is notified from the wireless LAN radio field intensity measurement unit 17 to the PPP device 14. Subsequently, the PPP device 14 that has received the notification determines whether the radio wave intensity is lower than a predetermined threshold value, or whether the terminal 10 cannot receive radio waves (invalid) (S111, measurement). Step, detection step). When it is determined that the radio field intensity is not lower than a predetermined threshold and the terminal 10 cannot receive radio waves, the measurement of the radio field intensity by the wireless LAN radio field intensity measurement unit 17 is continued.

  When it is determined that the radio wave intensity is lower than a predetermined threshold value or the terminal 10 cannot receive radio waves, the PPP device 14 sets a communication link for transmitting a packet to the second PPP connection (wireless The first PPP connection (W-CDMA communication link) is switched from the LAN communication link). At this time, the PPP device 14 excludes the second PPP connection (S112, switching step, exclusion step).

  Accordingly, in the mobile communication terminal 10, the PPP device 14 transmits a link change request to the W-CDMA communication link to the fixed communication device 20 (S113, notification step). In the fixed communication apparatus 20, the PPP device 24 receives the link change request, and the communication link for transmitting the packet changes from the second PPP connection (Internet communication link) to the first PPP connection (W-CDMA communication). Link) (S141).

  Subsequently, in the mobile communication terminal 10, the PPP disconnection request for the second PPP connection is transmitted to the fixed communication device 20 by the L2TP virtual device 13, and the second PPP connection is disconnected (S114, control step). In the fixed communication device 20, the PPP disconnection request is received by the L2TP virtual device 23, and the second PPP connection is disconnected (S142).

  Subsequently, in the mobile communication terminal 10, an L2TP tunneling disconnection request is transmitted from the L2TP virtual device 13 to the fixed communication device 20 (S115, control step). In the fixed communication apparatus 20, the L2TP virtual device 23 receives the L2TP tunneling disconnection request and disconnects the L2TP tunneling (S143).

  Through the above-described processing, the mobile communication terminal 10 is in a state where only the first PPP connection (W-CDMA communication link) has been established (state before S102 shown in FIG. 3). Thereafter, the mobile communication terminal 10 returns to the process of S102 shown in FIG. If a newly enabled wireless LAN access point is detected in S102, the processing from S104 onward is performed.

  Through the series of processes described above, the mobile communication terminal 10 can appropriately continue PPP communication by updating the access of the valid wireless LAN even while moving.

  The processing described with reference to FIG. 4 shows an example in which the second PPP connection and L2TP tunneling are disconnected and the step of searching for a new effective wireless LAN access point is entered when the radio wave strength of the wireless LAN becomes weak. However, the processing up to S113 can be performed (the processing of S114 and S115 is not performed), and the second PPP connection can be maintained. In that case, the process shown in the sequence diagram of FIG. 5 is performed. In this case, the above-described wireless LAN communication link exclusion process is not performed.

  As shown in FIG. 5, thereafter, in the mobile communication terminal 10, the radio LAN radio field strength measurement unit 17 periodically measures the radio field strength of the communication link of the wireless LAN held as the second PPP connection. The measured radio field intensity is notified from the wireless LAN radio field intensity measurement unit 17 to the PPP device 14. Subsequently, the PPP device 14 that has received the notification determines whether or not the radio wave intensity is higher than a predetermined (second) switching threshold (S121, measurement step). If it is determined that the radio field intensity is not higher than a predetermined switching threshold, the measurement of the radio field intensity by the wireless LAN radio field intensity measurement unit 17 is continued.

  If it is determined that the radio field intensity is higher than a predetermined switching threshold, the PPP device 14 changes the communication link for transmitting the packet from the first PPP connection (W-CDMA communication link) to the second. PPP connection (wireless LAN communication link) (S122, switching step).

  Accordingly, in the mobile communication terminal 10, the PPP device 14 transmits a link change request to the Internet communication link to the fixed communication device 20 (S123, notification step). In the fixed communication apparatus 20, the PPP device 24 receives the link change request, and the communication link for transmitting the packet changes from the first PPP connection (W-CDMA communication link) to the second PPP connection (Internet communication). Link) (S151). Thereafter, the above-described processing after S111 is repeatedly performed.

  Through the series of processes described above, the mobile communication terminal 10 can appropriately continue the PPP communication by switching the desired communication link as needed without disconnecting the PPP connection by the wireless LAN.

  Subsequently, information transmitted and received between the mobile communication terminal 10 and the fixed communication device 20 used when notifying switching of a communication link for transmitting a packet will be described. The notification uses a PPP LCP negotiation message. FIG. 6 shows examples of a link change request message M101 and a response message M102. The link change request message M101 stores a value indicating the link change request in the Code field indicating the instruction code. A device number is specified in the data field of the message M101. In this example, “1” is the first PPP connection and “2” is the second PPP connection. The response message M102 to the link change request message M101 stores a value indicating the link change request response in the Code field. Then, a value indicating whether the link change has succeeded or failed is stored in the data field of the response message M102.

  Subsequently, FIG. 7 shows a data structure of a PPP device driver managed by the PPP device 14 in order to realize the mobile communication terminal 10 of the present embodiment. In FreeBSD 4.11R, the PPP device driver holds data in a structure called ppp_softc. The ppp_softc structure contains an ifnet structure that contains IP address information, etc., a pointer sc_devp to the tty structure used for the communication link, sc_rawq for the receive packet queue, sc_inq for the PPP control receive packet queue, sc_fastq for the send packet queue, etc. keeping. In addition, sc_master and sc_slave are added in this embodiment in order to hold a plurality of communication links in one ppp_softc structure so that they can be switched arbitrarily, each of which is connected to one communication link (tty structure). It is a pointer. sc_devp becomes a pointer to sc_master or sc_slave in order to select which communication link is used. In this embodiment, two types of communication links are used, but even if there are three or more types of communication links, it can be realized by simply adding a pointer to the third type of communication link. The tty structure of each communication link has a back pointer t_sc to the ppp_softc structure that manages the communication link. In the case of a PPP multilink that realizes a plurality of communication paths, t_sc of a plurality of tty structures is a pointer to the same ppp_softc structure. Therefore, packets received from a plurality of communication links can be placed in the reception packet queue sc_rawq of the same ppp_softc structure.

The selection of a communication link for transmitting a packet can be switched depending on whether the sc_devp pointer is set to sc_master or sc_slave. This switching can be performed by a control system call ioctl to the communication link device shown below.
int ioctl (int d, PPPIOSCDEVICE, int dev_id)
An ID PPPIOCSDEVICE is added to the second argument of ioctl, and the communication link specified by the third argument can be selected for the PPP device 14 associated with the communication link device specified by the first argument.

Further, in order to aggregate a plurality of communication links into one PPP device, a control ID called PPPIOCMUNIT is added as follows, and the PPP device 14 associated with the communication link device specified by the first argument is connected to the third device. The communication links established by the PPP device 14 having the unit number specified by the argument are aggregated.
int ioctl (int d, PPPIOCMUNIT, int unit)

  By adding these device control system calls, it is possible to collect and select communication links from PPPd, which is a PPP control daemon, and other applications, and communication links according to the value and characteristics of information at the application level. Can be selected.

  As described above, according to the present embodiment, a PPP communication link of wireless communication with a different method is established by a plurality of wireless access means such as the W-CDMA communication modem 11, the wireless LAN adapter 12, and the L2TP virtual device 13. And established communication links are aggregated. Thereby, communication using a plurality of communication links as one communication path is performed.

  In this embodiment, it is detected that communication by the wireless LAN adapter 12 is possible, and a communication link is established by the wireless LAN adapter 12 and the L2TP virtual device 13. As a result, according to the present embodiment, communication links that are valid at any time that can be communicated can be aggregated. Therefore, even in an environment in which the terminal moves and the communication environment changes at any time, PPP communication is appropriately continued. It becomes possible to do.

  Further, as in this embodiment, if L2 tunneling is established with a communication partner and a communication link via the L2 tunneling is established, a PPP communication link is established directly via the Internet or the like. Even if it is not possible, a communication link can be established. Thereby, the redundancy of a communication link can be improved and it becomes possible to continue communication more appropriately.

  Further, as in the present embodiment, if the communication link is detected to be invalid and excluded from aggregation, the communication link in the mobile communication terminal 10 can be appropriately managed.

  In addition, as in this embodiment, if the communication link that transmits a packet is switched based on the radio field strength, packet loss due to the degradation of the radio field strength can be prevented. Can be sent.

  In the present embodiment, only the wireless LAN communication link is controlled, but the configuration is not necessarily required. The W-CDMA communication link is the same as the wireless LAN communication link or the W-CDMA communication link. Only the CDMA communication link may be controlled.

  In this embodiment, the packet transmission is performed through one communication link. However, it is not always necessary to perform the transmission through only one communication link. For example, the communication states of a plurality of established communication links are all good. In such a case, the packet may be transmitted through a plurality of communication links as in the conventional multilink PPP.

  Subsequently, the fixed communication device 20a and the mobile communication terminal 10 according to the second embodiment of the present invention will be described.

  FIG. 9 shows configurations of the fixed communication device 20a and the mobile communication terminal 10 according to the present embodiment. The basic configuration of the fixed communication device 20a and the mobile communication terminal 10 according to the present embodiment is the same as that of the fixed communication device 20 and the mobile communication terminal 10 of the above-described embodiment. As shown in FIG. 9, the fixed communication device 20 a according to the present embodiment further includes a communication line monitoring unit 26. The communication line monitoring unit 26 is connected to the PPP device 24 and can transmit / receive information to / from the PPP device 24 and monitor the ISDN modem 21 through the PPP device 24 described below.

  The communication line monitoring unit 26 is means for monitoring the number of PPP connections established by the ISDN modem 21 via the telephone network N1. That is, the communication line monitoring unit 26 is a monitoring unit that monitors the communication status of at least one communication among a plurality of communication units in the own device 20a. The monitored communication status corresponds to, for example, the usage status of the communication line (the number of established PPP connections) as described above.

  The communication line monitoring unit 26 is a communication link change request unit that requests the mobile communication terminal 10 that is a communication partner to change the communication link that transmits a packet, based on the number of monitored PPP connections. . Specifically, the following functions are provided. The communication line monitoring unit 26 stores in advance the maximum allowable number of PPP connections with respect to the number of PPP connections via the telephone network N1. Here, the maximum allowable number of PPP connections is the number by which the fixed communication device 20a (its ISDN modem 21) can simultaneously accept PPP connections from the telephone network N1. When the PPP connection through the telephone network N1 is established between the mobile communication terminal 10 and the own apparatus 20a, the communication line monitoring unit 26 allows the ISDN modem 21 to communicate with another communication apparatus (another communication apparatus through the telephone network N1). When a PPP connection request from a mobile communication terminal 10 is received, the following processing is performed. When a PPP connection request is accepted, the fact is notified from the ISDN modem 21 to the communication line monitoring unit 26 via the PPP device 24.

  The communication line monitoring unit 26 compares the monitored number of current PPP connections with the maximum allowable number of PPP connections, and determines whether the free capacity of the PPP connection via the telephone network N1 is sufficient. For example, when the maximum allowable PPP connection number is 2 and the current number of PPP connections is 1, it is determined that the free capacity is 1 and the free capacity is sufficient. On the other hand, when the number of current PPP connections is 2, it is determined that the free capacity is 0 and the free capacity is not sufficient. If it is determined that the free capacity of the PPP connection is sufficient, the communication line monitoring unit 26 instructs the ISDN modem 21 to establish a PPP connection with the communication apparatus that has transmitted the PPP connection request as usual. Instruct.

  When it is determined that the free capacity of the PPP connection is not sufficient, the communication line monitoring unit 26 requests the mobile communication terminal 10 having established the PPP connection via the telephone network N1 to change the communication link for transmitting the packet. (Link change request). Specifically, it is a request for a change from the telephone network N1 to another communication network such as the Internet N2. The request for the change is made by transmitting a signal related to the request via the telephone network N1 (by the ISDN modem 21 under the control of the communication line monitoring unit 26).

  Further, as described later, the PPP device 24 receives a link change request transmitted from the mobile communication terminal 10 in response to the above request, and sets the communication link for transmitting the packet to the first PPP connection (W-CDMA). The communication link is switched to the second PPP connection (Internet communication link). Further, after the communication link is changed as described above, the communication line monitoring unit 26 causes the ISDN modem 21 to establish a PPP connection with the communication apparatus that has transmitted the PPP connection request as usual. Instruct. The above is the configuration of the fixed communication device 20a according to the present embodiment.

  Corresponding to the above-described fixed communication device 20a, the mobile communication terminal 10 according to the present embodiment has the following functions in addition to the mobile communication terminal 10 of the previous embodiment. The W-CDMA communication modem 11 also functions as a communication link change accepting unit that accepts a request for changing the communication made from the fixed communication device 20a. Specifically, as described above, the W-CDMA communication modem 11 receives the change request signal transmitted from the fixed communication device 20a. The W-CDMA communication modem 11 notifies the PPP device 14 that a request for changing communication has been accepted.

  The PPP device 14 also functions as a switching unit that switches a communication link that transmits a packet based on a communication link change request received by the W-CDMA communication modem 11. When the PPP connection via the Internet N2 (the second PPP connection in the previous embodiment) is established between the own device 10 and the fixed communication device 20a, the PPP device 14 transmits the PPP connection to the packet. Set as the communication link used for.

  When the PPP connection via the Internet N2 is not established between the own terminal 10 and the fixed communication device 20a, the PPP device 14 establishes the PPP connection via the Internet N2 between the own terminal 10 and the fixed communication device 20a. Then, the PPP connection is set as a communication link used for packet transmission. Subsequently, the PPP device 14 transmits a link change request to the communication link of the wireless LAN to the fixed communication device 20a as in the previous embodiment. The above is the configuration of the mobile communication terminal 10 according to the present embodiment.

  Subsequently, processing (mobile communication method and communication method) executed in the mobile communication terminal 10 and the fixed communication device 20a according to the present embodiment will be described using the sequence diagram of FIG. Here, PPP connection (first PPP connection) via the telephone network N1 is established between the mobile communication terminal 10 and the fixed communication device 20a, and PPP connection (second PPP connection via the Internet N2 is established. Connection) is not established.

  In the fixed communication device 20a, the communication line monitoring unit 26 monitors the number of first PPP connections established by the ISDN modem 21 (S170, monitoring step). Note that the number of PPP connections is not monitored at a predetermined timing, but is always performed (for example, at regular intervals).

  Here, a PPP connection request is transmitted to the fixed communication device 20a from a communication device different from the mobile communication terminal 10 described above. In the fixed communication device 20a, the PPP connection request is accepted by the ISDN modem 21 (S171). Subsequently, the communication line monitoring unit 26 compares the number of monitored current PPP connections with the maximum allowable number of PPP connections to determine whether or not the free capacity of the first PPP connection is sufficient (S172). , Communication link change request step). When it is determined that the free capacity of the first PPP connection is sufficient, the following processing is not performed.

  When it is determined that the free capacity of the first PPP connection is not sufficient, the communication line monitoring unit 26 (control) subsequently transmits a packet to the mobile communication terminal 10 in which the first PPP connection is established. A communication link change request is made (S173, communication link change request step). The mobile communication terminal 10 for which a communication link change request is made (that is, the communication link change target) is based on a predetermined rule stored in the fixed communication device 20a (in its communication line monitoring unit 26). Can be decided. For example, a request is made to the mobile communication terminal 10 in which the first communication link has been established earliest (that is, the longest first communication link has been established).

  In the mobile communication terminal 10, the request is received by the W-CDMA communication modem 11 (S161, communication link change reception). Subsequently, in the mobile communication terminal 10, in accordance with the link change request, it is determined whether or not it is possible to establish a second PPP connection that can change the link by the PPP device 14 (S161, detection step, switching). Step). In this embodiment, it is determined whether or not wireless communication by the wireless LAN by the wireless LAN adapter 12 is valid. When it is determined that the second PPP connection cannot be established, the mobile communication terminal 10 does not perform the following process.

  When it is determined that the second PPP connection can be established, a PPP connection request for the second PPP connection is made to the fixed communication apparatus 20 by the L2TP virtual device 13 under the control of the PPP device 14 as in the previous embodiment. It is transmitted (S162, control step, switching step). In the fixed communication device 20a, the L2TP virtual device 23 receives the PPP connection request via the Ethernet adapter 22, and the second PPP connection is established between the mobile communication terminal 10 and the fixed communication device 20a (S174). ).

  Subsequently, in the mobile communication terminal 10, the PPP device 14 aggregates the second PPP connection and the first PPP connection (S163, aggregation step, switching step). Further, the PPP device 14 switches the communication link for transmitting packets from the first PPP connection to the second PPP connection (S164, switching step). On the other hand, also in the fixed communication apparatus 20, the second PPP connection and the first PPP connection are aggregated by the PPP device 24 (S175, aggregation step).

  Subsequently, in the mobile communication terminal 10, the PPP device 14 transmits a link change request to the wireless LAN communication link to the fixed communication device 20a (S165, notification step). In the fixed communication device 20a, when the link change request is received by the PPP device 24, the communication link for transmitting the packet changes from the first PPP connection (W-CDMA communication link) to the second PPP connection (Internet communication). Link) (S176).

  Subsequently, in the mobile communication terminal 10 and the fixed communication device 20a, the first PPP connection is disconnected (S166, S177). The fixed communication device 20a then performs a process of establishing a PPP connection with the communication device related to the PPP connection request accepted in S171 (not shown).

  Through the series of processes described above, the mobile communication terminal 10 can shift the communication link used by the mobile communication terminal 10 to another communication network while continuing communication with the mobile communication terminal 10 in communication. it can. The communication link is changed according to the communication status such as the usage status of the communication line. Therefore, according to the present embodiment, the communication line can be efficiently used, and the mobile communication terminal 10 can efficiently and appropriately transmit the packet to the fixed communication device 20a that is the communication partner.

  In the above-described embodiment, when a PPP connection request is received from the mobile communication terminal 10, it is determined to change the communication link. However, when a plurality of communication links have already been established, (PPP connection) The above determination may be made without triggering the request. In addition, although the number of established PPP connections is used for the above determination, an index indicating the other communication status related to the communication means may be used for the above determination. In addition, the communication link is changed from a PPP connection via the telephone network N1 to a PPP connection via the Internet N2, but the opposite change may be made depending on the communication status. In that case, the communication status of the Internet N2 is monitored.

It is a figure which shows the function structure of the mobile communication terminal which concerns on embodiment of this invention. It is a figure which shows the hardware constitutions of the mobile communication terminal which concerns on embodiment of this invention. It is a sequence diagram which shows the process (mobile communication method) performed by the mobile communication terminal which concerns on embodiment of this invention. It is a sequence diagram which shows the process (mobile communication method) performed by the mobile communication terminal which concerns on embodiment of this invention. It is a sequence diagram which shows the process (mobile communication method) performed by the mobile communication terminal which concerns on embodiment of this invention. It is a figure which shows the example of the information used when notifying switching of the communication link which transmits a packet. It is a figure which shows the data structure of the PPP device driver managed by a PPP device. It is a figure which shows the hardware constitutions of the fixed communication apparatus which concerns on embodiment of this invention. It is a figure which shows the function structure of the mobile communication terminal which concerns on the 2nd Embodiment of this invention. It is a sequence diagram which shows the process (mobile communication method and communication method) performed by the mobile communication terminal and fixed communication apparatus which concern on embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Mobile communication terminal, 11 ... W-CDMA communication modem, 12 ... Wireless LAN adapter, 13 ... L2TP virtual device, 14 ... PPP device, 15 ... IP layer, 16 ... Effective wireless LAN search part, 17 ... Wireless LAN radio wave intensity Measurement unit, 101 ... CPU, 102 ... RAM, 103 ... ROM, 104 ... operation unit, 105 ... wireless communication unit, 106 ... display, 107 ... antenna, 20, 20a ... fixed communication device, 21 ... ISDN modem, 22 ... Ethernet Adapter, 23 ... L2TP virtual device, 24 ... PPP device, 25 ... IP layer, 26 ... Communication line monitoring unit, 201 ... CPU, 202 ... RAM, 203 ... ROM, 204 ... Communication module, 205 ... Auxiliary storage device.

Claims (8)

A plurality of wireless access means for establishing a communication link by PPP for wireless communication, each of which has a different method, with a communication partner;
Aggregating means for aggregating the communication links established by the plurality of radio access means;
Detecting means for detecting that wireless communication is possible for at least one of the plurality of wireless access means;
Control means for controlling the wireless access means detected to be capable of wireless communication by the detecting means to establish the communication link;
A mobile communication terminal comprising:   One of the wireless access means acquires an IP address, establishes L2 tunneling with the communication partner using the IP address, and establishes a communication link via the L2 tunneling. The mobile communication terminal according to claim 1. The detecting means detects, for at least one of the plurality of wireless access means, that a communication link established by the wireless access means has become invalid;
The aggregation means excludes the communication link detected to be invalid by the detection means;
The mobile communication terminal according to claim 1, wherein the mobile communication terminal is a mobile communication terminal. Measuring means for measuring the radio field intensity of the communication link established by the wireless access means;
Switching means for switching communication links for transmitting packets based on the radio field intensity measured by the measuring means;
When the communication link for transmitting a packet is switched by the switching means, a notification means for notifying the communication partner to that effect;
The mobile communication terminal according to any one of claims 1 to 3, further comprising: Communication link change accepting means for accepting a request for changing a communication link for transmitting a packet from the communication partner;
Switching means for switching a communication link for transmitting a packet based on a request for changing the communication link received by the communication link change receiving means;
When the communication link for transmitting a packet is switched by the switching means, a notification means for notifying the communication partner to that effect;
The mobile communication terminal according to any one of claims 1 to 4, further comprising: A plurality of communication means for establishing a communication link by means of PPP with a communication method different from each other with a communication partner;
Aggregating means for aggregating the communication links established by the plurality of communication means;
Monitoring means for monitoring a communication status of at least one of the plurality of communication means;
Based on the communication status monitored by the monitoring means, communication link change request means for requesting the communication partner to change the communication link for transmitting packets;
A communication device comprising: A mobile communication method in a mobile communication terminal comprising a plurality of wireless access means for establishing a communication link by PPP of wireless communication with different methods with a communication partner,
An aggregation step of aggregating the communication links established by the plurality of wireless access means;
A detection step of detecting that wireless communication is possible for at least one of the plurality of wireless access means;
A control step of controlling the wireless access means that is detected to be capable of wireless communication by the detecting means to establish the communication link;
A mobile communication method including: A communication method in a communication device comprising a plurality of communication means for establishing a communication link by means of PPP with different communication methods with a communication partner,
An aggregation step of aggregating the communication links established by the plurality of communication means;
A monitoring step of monitoring a communication status of at least one of the plurality of communication means;
Based on the communication status monitored in the monitoring step, a communication link change request step for requesting the communication partner to change a communication link for transmitting a packet;
Including a communication method.

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