JP2008219482A - Information distribution system in radio packet communication system, information distribution method and information distribution device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide structure by which information is distributed using an SSID field without changing the existing terminal. <P>SOLUTION: This information distribution system is provided with a radio terminal and an access point. The access point is provided with: an SSID transmission information management means for generating a transmission packet in the same form as that of a broadcasting packet to manage the information in the SSID field; an information division packet generation means for dividing the information to generate transmission packets of each piece of information; a transmission packet transmitting means for transmitting the transmission packet; a connection request receiving means for receiving a connection request frame; a connection response discrimination means for discriminating permission of connection to the radio terminal on the basis of terminal side information of the connection request frame and a connection permission response frame for transmitting a connection permission response frame to the radio terminal when the connection is permitted. The radio terminal is provided with a connection request transmitting means for creating the connection request frame on the basis of the information for receiving the transmission packet and simultaneously transmitting the connection request frame. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an information distribution system, an information distribution method, an information distribution apparatus, an information distribution method and an information distribution program in an information distribution apparatus in a wireless packet communication system, and in particular, broadcasts using an SSID field in a beacon frame of a wireless LAN. The present invention relates to an information delivery system, an information delivery method, an information delivery apparatus, an information delivery method in an information delivery apparatus, and an information delivery program.

  Conventionally, a wireless local area network (LAN) defined by IEEE (Institute of Electrical and Electronics Engineers) 802.11 has been known as a wireless packet communication system (Non-patent Document 1).

  Here, a typical configuration of the conventional technology constituting the wireless LAN will be described with reference to the wireless LAN system shown in FIG.

  The wireless LAN system shown in FIG. 15 includes an access point 501, an access point 501A, an access point 501B, a terminal 502A, and a terminal 502B.

  The access point 501 is connected to a wired LAN, and serves as a bridge between a terminal (not shown) connected to the wired LAN side and terminals 502A and 502B connected using the wireless LAN.

  In this case, the range of wireless LANs managed by one access point 501 is distinguished from each other by using a logical ID (identifier) called a network identifier (hereinafter referred to as SSID (Service Set Identifier)). Is done.

  In addition, in the wireless LAN defined by IEEE 802.11, a transmission unit of information corresponding to a packet is called a frame.

  As shown in FIG. 16, the access point 501 shown in FIG. 15 broadcasts a frame called a beacon (hereinafter referred to as a beacon frame) to the terminals 502A and 502B at a constant period (step S161). A plurality of terminals are managed by this beacon frame.

  Note that the terminals 502A and 502B illustrated in FIG. 15 are not limited to two, and may be a plurality or one. In addition, when there is no need to specifically limit the terminal 502A or 502B, the terminal 502A is simply described.

  Here, the format of the beacon frame transmitted by the access point 501 shown in FIG. 15 is shown in FIG.

  The beacon frame format shown in FIG. 17 has a data part (pointing from 606 to 611) of a beacon frame, and has an SSID field 609 for storing the SSID therein.

  Therefore, the access point 501 can notify the SSID of the wireless LAN system by broadcasting a beacon frame to the terminals 502A and 502B at a constant period.

  The wireless LAN terminal 502 receives a beacon frame transmitted from the access point 501 to detect the presence of the wireless LAN network and its SSID, and performs an appropriate connection process.

  Since the SSID is used for the purpose of connection processing, the SSID field 609, which is one of the fields in the beacon frame, is information that can be used by applications in higher-level terminals while being in the MAC layer frame format. It has become.

  Specifically, for example, in the case of a network having a plurality of access points having different SSIDs, the terminal 502 receives a plurality of beacon frames having different SSIDs.

  Then, the SSID is extracted from the SSID field 609 in the received beacon frame, and the acquired SSIDs 701 to 703 are displayed on the screen of the terminal 502 as shown in FIG.

  When the terminal 502 connects to the network, first, the user who uses the terminal 502 selects a connection destination network from the plurality of SSIDs 701 to 703 displayed on the terminal 502, or the terminal 502 internal The wireless LAN connection software automatically selects a preset SSID from SSIDs 701 to 703 of the received beacon frame.

  Next, the terminal 502 transmits a connection request frame including the SSID to be connected to the access point 501 that transmitted the SSID as a destination.

  Next, as shown in FIG. 19, the access point 501 accepts connection by the network of SSID: X (step S183) in response to the connection request (step S182 (SSID: X)) including the SSID from the terminal 502, or Reply with a connection denied frame.

  When the terminal 502 receives a response with the connection permission frame from the access point 501 (step S183), the terminal 502 passes through the access point 501 from that point, thereby connecting to another terminal (not shown). ) And communication with a terminal on the wired LAN side connected to the access point 501 (steps S184 and S185).

  Here, the maximum value of the length of the SSID field in the beacon frame defined in IEEE 802.11 is 32 bytes, and different SSIDs are assigned when the networks are different within the reach of radio waves. It was necessary to adjust in advance.

  An example of a conventional information distribution system is described in Patent Document 1. The information distribution system described in this patent document 1 is shown in FIG.

  As shown in FIG. 20, in the conventional information distribution system, when the enterprise terminal 101, the event information distribution system 102, and the wireless LAN access points 103A and 103B (the wireless LAN access points 103A and 103B are not specified), Wireless LAN access point 103) and event information receiving terminals 104A and 104B (in the event that the event information receiving terminals 104A and 104B are not specified, they are simply referred to as event information receiving terminals 104).

  In this information distribution system, an event information distribution system 102, a wireless LAN access point 103, and an event information receiving terminal 104 are connected via the Internet 106.

  Further, in this information distribution system, a hot spot 105 is composed of a wireless LAN access point 103A, a wireless LAN access point 103B, an event information receiving terminal 104A, and an event information receiving terminal 104B.

  The advertisement distribution system described in Patent Document 1 using a conventional wireless LAN having such a configuration operates as follows.

  As shown in FIG. 21, information distributed from the event information distribution server 102-2 in the event information distribution system 102 is received by the event information receiving unit 103-1 of the wireless LAN access point 103 shown in FIG. Event information is added to various control signals by the beacon transmission unit 103-2, and then transmitted as a beacon frame.

  23 receives the beacon frame transmitted from the wireless LAN access point 103, and the event information display unit 104-2 receives the radio beacon receiver 104-. Event information is extracted from 1 and output to the display screen of the event information receiving terminal 104.

  In FIG. 24, the radio beacon transmission unit 103-2 of the wireless LAN access point 103 transmits a beacon frame, and the beacon frame is transmitted to the radio beacon reception unit 104-1 (radio beacon reception unit in the plurality of event information receiving terminals 104. 104A-1 means all of the radio beacon receiving unit 104C-1). This indicates that the event information is being broadcast.

  In FIG. 25, the event information distribution server 102-2 is connected to the wireless LAN access point 103 of FIG. 22, and the distribution content 102-2-1 stored therein is stored in the wireless LAN access point 801. A state is shown in which the event information receiving unit 103-1 receives and the radio wave beacon transmission unit 103-2 transmits to the event information receiving terminal 104.

Even if the event information receiving terminal 104 is not directly connected to the event information distribution server 102-2 by the above information distribution system, the event information distribution server 102-2 has distribution via the wireless LAN access point 103. Distribution of content 102-2-1 is realized.
JP 2006-245906 A 'Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) specifications', IEEE std 802.11, 1999

  However, in the information distribution system described in Patent Document 1, there is no mechanism for sending information other than control / management information to the beacon frame format of the wireless LAN standard and transmitting it to the event information receiving terminal. When information other than control / management information is entered, the event information receiving terminal also needs to be known in advance about insertion of the information before transmission / reception of information other than control / management information.

  Therefore, in the information distribution system described in Patent Document 1 using the field of Non-Patent Document 1, there is a mechanism for distributing information other than control / management information to the terminal without changing the existing frame format and terminal function. Therefore, there was a problem that the existing frame format and terminal function had to be changed.

  The present invention has been made in view of the above problems, and provides an information distribution system, an information distribution method, an information distribution apparatus, and a mechanism for distributing information using an SSID field without changing an existing terminal. An object is to realize an information distribution method and an information distribution program in an information distribution apparatus.

  An information distribution system according to the present invention is an information distribution system in a wireless packet communication system that includes a wireless terminal and an access point that transmits a broadcast packet to the wireless terminal at a constant period. A transmission packet having the same format as the information packet is generated, the information is stored in the SSID field that stores the network identifier of the transmission packet, and the SSID transmission information management unit that manages the information, and the SSID transmission information management unit When the field length of the information is larger than the SSID field, the information is divided, each divided information is stored in the SSID field, and information divided packet generating means for generating a plurality of transmission packets; The transmission packet in which the information is stored Transmission packet transmitting means for transmitting to the wireless terminal, connection request receiving means for receiving a connection request frame transmitted by the connection request transmitting means of the wireless terminal, and terminal-side information stored from the received connection request frame And, based on the acquired terminal-side information, a connection response determination unit that determines permission of connection to the wireless terminal, and when the connection is permitted to the wireless terminal by the connection response determination unit, Connection permission response frame transmitting means for transmitting a connection permission response frame to the wireless terminal, wherein the wireless terminal receives the transmission packet, and transmits the connection packet to the access point based on the information included in the transmission packet. The connection request frame for requesting connection is created and the connection request frame is transmitted to the access point. Request transmitting means, characterized in that it comprises a.

  In the information distribution system according to the present invention, the wireless terminal is a terminal capable of supporting a virtual network identifier, and the connection request transmitting means is the network identifier or based on the virtual network identifier. The access point creates the connection request frame, and the access point stores the information stored in the SSID transmission information management means as a network identifier of the transmission packet or the virtual network identifier different from the network identifier. The terminal-side information acquired by the connection response determination unit may be the network identifier, or the connection permission for the wireless terminal may be determined based on the virtual network identifier.

  In the information distribution system according to the present invention, when the terminal side information is the virtual network identifier, the connection response determining unit determines that the connection to the wireless terminal is not permitted and uses the virtual network identifier. You may make it further provide the connection non-permission packet transmission means which transmits the connection non-permission packet containing the information to that effect.

  In the information distribution system according to the present invention, the connection response determining unit determines that the connection is not permitted for requesting a handover to the network with the normal network identifier when the terminal-side information is the virtual network identifier. Then, a handover request connection non-permission packet transmission unit that transmits a connection non-permission packet including handover request information to the wireless terminal may be further provided.

  In the information delivery system according to the present invention, when the terminal response information is the virtual network identifier, the connection response determining unit permits temporary connection of the virtual network identifier to the network, and A temporary connection permission packet transmitting means for transmitting a connection permission packet, and a connection including handover request information for requesting a handover of the regular network identifier to the network after transmitting the connection packet for permitting the temporary connection You may make it further provide the connection change packet transmission means which transmits a change packet.

  According to the present invention, the information broadcast is realized by changing only the contents of the SSID field, so that only the access point is changed without changing the existing wireless LAN terminal. Broadcast can be realized.

  In addition, when the information to be sent is divided into arbitrary lengths and transmitted in a plurality of beacons, the connection response determining means responds to a connection request for a beacon frame other than the regular SSID that should be originally used. Since an appropriate connection process can be performed, information having an arbitrary length exceeding the standard value can be transmitted using the SSID field of the beacon frame whose length is fixed according to the standard.

  Thus, it is possible to realize an information distribution system, an information distribution method, an information distribution device, an information distribution method for an information distribution device, and an information distribution program that provide a mechanism for distributing information using an SSID field without changing an existing terminal. .

Next, the configuration of the embodiment of the present invention will be described in detail with reference to the drawings.
(1) Information Distribution System According to First Embodiment (1-1) Configuration of Information Distribution System FIG. 1 is a schematic diagram showing a configuration of an information distribution system according to the first embodiment of the present invention.

  The information distribution system shown in FIG. 1 includes an access point 801, a terminal 802, a terminal 803, and a terminal 804.

  The schematic diagram of the information distribution system shown in FIG. 1 shows a case where the access point 801 having the simplest configuration is one and the access point 801 transmits a plurality of broadcast frames. .

  The information distribution system shown in FIG. 1 is the same as that of the non-patent document 1 of the background art as a system form, an access point 801 is connected to a wired LAN, and a plurality of terminals 802 to 804 exist under the access point. .

  The terminals 802 to 804 under the access point 801 do not necessarily need to be connected to the access point 801 and be in a communicable state, and are within a range where radio waves from the access point 801 can reach and a beacon can be received. Should just be arranged.

  In addition, the access point 801 is not necessarily required, and the implementation according to the present invention is also applied to the case where beacons are alternately transmitted in an ad hoc network such as IBSS (Independent Basic Service Set) of the IEEE 802.11 wireless LAN standard. Is possible.

  By the way, FIG. 17 shown above is a format of a beacon frame that the access point 801 broadcasts to the terminal, and shows an example of the SSID field therein.

  The access point 801 broadcasts to the surroundings of the access point 801 by including the SSID set from the outside in the SSID field 609 (FIG. 17) in the beacon.

  Here, the format of Non-Patent Document 1 is used without modification.

  Also, if information longer than 32 bytes, which is the upper limit of the standard length, is set as the SSID, the information is divided into a plurality of pieces of information not exceeding the maximum length of the original SSID field and set in the SSID field 609. To do.

  In this case, for example, the lengths after the division may be exactly the same, or a division method that is easier to divide according to the grammar of the language used in the information may be used.

  This division method will be described later.

  Next, in FIG. 2, a terminal 804 (any of terminals 802 to 804, which operates in the same manner) can be accessed by a terminal 804 within the radio wave range of an access point 801 corresponding to the present embodiment. When a beacon frame including broadcast information in the SSID is received from the point 801, a screen display example of a terminal screen displayed on the terminal 804 is shown.

  In this terminal screen display example, when the information (A + B + C) to be sent by the access point 801 does not fall within the maximum length of the SSID field of the beacon frame, the information to be sent by the access point 801 as shown in FIG. Is divided into “A”, “B”, and “C” and stored in the SSID field in the beacon.

  In addition, one divided SSID is used as a regular SSID that is actually used in the network, the other SSID is called a virtual network identifier (virtual SSID), and the regular SSID and the virtual SSID are stored in a beacon frame, respectively. To send.

  In FIG. 2, the information to be transmitted is A + B + C, which is divided into SSID: A1202, SSID: B1203, and SSID: C1204, which are stored in the SSID field of different beacon frames, respectively. To send.

  In addition, since the terminal 804 on the receiving side displays a list as different SSIDs, all the information stored in the access point 801 is displayed to the user who uses the terminal 804.

  Further, the terminal 804 that has received the beacon frame is displayed on the screen of the terminal 804 in the order of the continuously received beacon frames, but the order of reception is not necessarily required.

  In addition, the receiving side terminal 804 is not limited to the shape or the terminal form, and therefore any terminal of the terminals 802 to 804 is displayed on the terminal screen.

  Next, the configuration of the terminal 804 will be described with reference to FIGS.

  Since this terminal 804 has the same configuration among the terminals 802 to 804, the terminal 804 will be described as an example.

  Referring to FIG. 3, the terminal 804 is a communication device 901, and includes a physical layer 904 including an antenna, a MAC (media access control) layer 903, and an application 902.

  Referring to FIG. 4, in the terminal 804, when the frame analysis unit 1004 determines the type of frame received by the physical layer 904 and receives a beacon frame, the data in the beacon frame is sent to the SSID field extraction unit 1003. hand over.

  The SSID field extraction unit 1003 extracts the SSID field from the data of the beacon frame received from the frame analysis unit 1004 and passes it to the SSID data processing unit 1002 included in the application 902.

  The SSID data processing unit 1002 passes the SSID data transferred from the SSID field extraction unit 1003 to the SSID display unit 1001 at the time of reception.

  If a language not normally used in the standard is stored, it may be decoded and displayed in the original language.

  Specifically, for example, Japanese encoded in SJIS code may be decoded and displayed.

  Further, at the time of transmission, the SSID processing unit 1002 stores the SSID information from the SSID display unit 1001 in the memory of the SSID data processing unit 1002 and passes it to the connection processing unit 1005.

  If the SSID is configured in a language not normally used in the standard, encoding may be performed using an appropriate character code or the like.

  Specifically, for example, when the data to be transmitted is an ASCII code, it is passed to the connection processing unit without any processing. When the data to be transmitted is data other than an ASCII code such as Japanese, SJIS is used. Japanese codes such as codes and EUC codes, and multilingual codes such as UTF-8 may be used.

  The terminal 804 displays the SSID information obtained from the SSID display unit 1001 and the SSID data processing unit 1002 on the screen of the terminal 804. However, it is not necessarily displayed on the screen of the terminal 804. As another example, for example, it may be read out by voice or the like, or SSID information may be transmitted to another terminal and displayed on another screen. May be.

  Further, the SSID information selected by the user using the terminal 804 is passed to the SSID data processing unit 1002.

  The connection processing unit 1005 acquires connection destination SSID information from the SSID data processing unit 1002, generates a connection request frame in the SSID field in the connection request packet, and passes it to the physical layer 904.

  Next, the configuration of the access point 801 will be described with reference to FIG.

  The frame analysis unit 1102 recognizes the frame type by analyzing the frame received by the physical layer 9040 based on the standard frame format, and passes the frame type to the processing distribution unit 1101 for each frame type.

  The process distribution unit 1101 for each frame type distributes individual processes for each frame type determined by the frame analysis unit 1102. Among these, the connection request frame is transferred to the connection processing unit 1103.

  The connection processing unit 1103 first extracts the SSID field in the connection request frame for the data distributed by the frame type processing distribution unit 1101, and passes it to the virtual SSID processing unit 1104.

  Here, if it is determined that it is a legitimate SSID, it responds with a connection permission frame to the terminal 804 that transmitted the connection request.

  On the other hand, if it is recognized that the SSID is not a regular SSID and if it is recognized as a virtual SSID, no response is returned.

  Alternatively, if the terminal 804 that transmitted the connection request is a terminal corresponding to the virtual SSID, a connection disapproval frame including the reason for the virtual SSID is transmitted.

  Alternatively, if the terminal 804 that transmitted the connection request is a terminal corresponding to the virtual SSID, a connection disapproval frame or a handover request frame including a normal SSID and a virtual SSID is transmitted.

  Alternatively, a connection permission is normally responded to the virtual SSID, and a field other than the SSID field of the beacon frame including the virtual SSID is put a normal value in addition to the time stamp.

  On the other hand, if the SSID is not a regular SSID and is recognized as an SSID that is not a virtual SSID, a connection non-permission frame is transmitted.

  Here, handover in a handover request frame means that a mobile phone or PHS (personal handy phone system) terminal switches the network of a base station or access point to be connected. This refers to transmitting a frame for requesting switching.

  The SSID transmission information management unit 1107 manages information to be included in the SSID field of the beacon frame and passes it to the beacon frame generation unit 1106.

  The beacon frame generation unit 1106 includes the SSID information passed from the SSID transmission information management unit 1107 in the SSID field in the beacon frame and transmits the beacon frame.

  At this time, if the information to be transmitted exceeds the maximum length in the standard of the SSID field, the SSID information to be transmitted is passed to the virtual SSID processing unit 1104.

  The virtual SSID processing unit 1104 divides the SSID information so that the information to be transmitted falls within the maximum value of the SSID field in the beacon frame, and transmits the divided individual information in the SSID field of the beacon frame.

  Information to be sent in this case is shown in FIG.

  The information 1201 to be sent shown in FIG. 6 is divided into three parts A1202, B1203, and C1204, and SSID: A, SSID: B (virtual SSID), and SSID: C (virtual SSID), respectively. Sent.

  At this time, it is desirable that the divided information is continuously transmitted at the specified beacon transmission timing, but it is not always necessary to continuously transmit the information, and it may be transmitted independently at each beacon transmission timing. good.

Further, the information to be sent divided by the virtual SSID processing unit 1104 is not necessarily a broadcast frame such as a beacon frame, but may be included in a single destination or a multicast frame.
(1-2) Overall Operation of Terminal in Information Distribution System Next, the overall operation of the terminal 802 of the information distribution system in the first embodiment will be described in detail with reference to the flowchart of FIG.

  2 exemplifies the terminal 804, the configuration has been described using the terminal 804, but the operation will be described using the terminal 802.

  First, FIG. 7 is a flowchart showing operations related to beacon reception and generation / transmission of a connection request frame based on beacon reception as operations of the terminal 802 constituting the information distribution system in the first exemplary embodiment of the present invention. It is.

  Note that since the terminal 803 and the terminal 804 are similar to the operation of the terminal 802, any terminal may be used and the description thereof is omitted because it is the same operation.

  Step S1 indicating the start of the flowchart in FIG. 7 is a time point when the physical layer 904 of the terminal 802 is ready to receive a frame from the access point 801 in the information distribution system using the wireless LAN system shown in FIG. Indicates.

  After step S1, first, the terminal 802 determines whether to dynamically search for the access point 801 (step S15).

  Here, when the access point 801 is dynamically searched, the process proceeds to step S16 to generate and transmit an access point search frame.

  Then, a search response frame for the search frame from the peripheral access point 801 is received (step S17).

  Here, since the search response frame received in step S17 has the same format as the beacon frame, SSID data is extracted from the SSID field of the search response frame in the same manner as the beacon frame (step S4) on the screen of the terminal 802. SSID information can be displayed on the screen (step S5).

  On the other hand, after step S1, if the terminal 802 does not dynamically search for the access point 801, the process proceeds to step S2, where the terminal 802 receives a beacon frame transmitted by a nearby access point (step S2), It is checked whether or not the reception time is timed out (step S3).

  If the beacon reception time has timed out, the process proceeds to step S4, where the SSID data is extracted from the SSID field of the received beacon frame, and the application displays the SSID information on the screen of the terminal 802 (step S5).

  On the other hand, if the beacon reception time does not time out in step 3, the process returns to step 2 to receive a beacon frame.

  From the SSID information displayed on the screen of the terminal 802, the user selects the SSID information or is automatically selected according to the conditions already set internally (step S6), the terminal 802 generates a connection request frame, It is transmitted to the access point 801 (step S7).

  If the SSID is not selected from the SSID list displayed on the screen, the process returns to step S6 and waits until the SSID is selected.

  When the access point 801 receives the connection request frame generated based on the SSID selected in step S <b> 6, the access point 801 generates a connection permission frame and transmits it to the terminal 802 when the connection is permitted.

  Here, the terminal 802 waits for a connection permission frame for the connection request frame, and checks whether or not to receive a connection permission frame from the access point 801 (step S8).

  That is, when the terminal 802 receives the connection permission frame from the access point 801 as a result of the transmission of the connection request frame, the connection is completed and transmission / reception between the access point 801 and the data frame is started (step S9). ).

  On the other hand, if the terminal 802 does not receive a connection permission frame from the access point 801, the terminal 802 proceeds to step S10, and the same BSSID (basic service set identification: normal access point MAC address is included in the list of SSIDs held. If there is an SSID of the sender address, a connection request frame including the SSID is generated and transmitted (step S10).

  In this case, the terminal 802 waits for a connection permission frame for the connection request frame that has been transmitted again, and checks whether or not the connection permission frame is received again (step S11).

  If the terminal 802 receives a connection permission frame as a result of retransmission of the connection request frame, the terminal 802 proceeds to step 9 to complete the connection.

  On the other hand, if the terminal 802 does not receive the connection permission frame or receives the connection disapproval frame as a result of retransmission of the connection request frame, the terminal 802 proceeds to step S12 and is still held in the terminal 802. It is checked whether there is an SSID in the list of existing SSIDs that includes the same BSSID or sender address as the retransmitted connection request frame.

  Here, if there is an SSID including the same BSSID or sender address as the retransmitted connection request frame, the process returns to step SS10 and the same processing is repeated.

On the other hand, if there is no SSID corresponding to the SSID including the same BSSID or sender address as the retransmitted connection request frame, it is processed as a connection failure (step S13).
(1-3) Beacon Transmission Operation of Access Point in Information Distribution System Next, a beacon transmission operation in the access point 801 will be described with reference to the flowchart of FIG.

  In FIG. 8, step S21 indicating the start of the flowchart indicates that the SSID transmission information management unit 1107 (FIG. 5) has not yet been set to information to be transmitted in the SSID field in the beacon frame.

  Then, when the access point 801 stores the information to be transmitted in the SSID transmission information management unit 1107 (step S22), the beacon frame generation unit 1106 determines whether the information can be stored in the SSID field of the beacon frame (step S22). S23).

  If the information to be transmitted has a length that can be stored in the SSID field of the beacon frame, the process proceeds to step S26, and the information to be transmitted is inserted into the SSID field and transmitted.

  On the other hand, if the information to be transmitted is larger than the size that can be stored in the SSID field of the beacon frame, the information to be transmitted by the virtual SSID processing unit 1104 is divided into lengths that can be stored in the SSID field (step S24). .

Then, the divided information to be transmitted is transmitted in the SSID field of a different beacon frame (step S25).
(1-4) Response Operation with respect to Attribution Request Frame from Terminal in Information Distribution System Next, a response operation with respect to an attribution request frame from the terminal 802 at the access point 801 will be described with reference to FIG.

  In FIG. 9, in step S41 indicating the start of the flowchart, the information to be transmitted is already set in the SSID transmission information storage unit 1107, and the beacon frame is transmitted with the information to be transmitted included in the SSID field. A state of waiting for reception of a connection request frame from 802 is shown.

  First, when the access point 801 receives a connection request frame transmitted by the terminal 802 based on a beacon frame transmitted by the access point 801 or a response frame to the access point search frame from the terminal 802 (step S42), the connection request frame The information in the SSID field is extracted (step S43).

  Check whether the extracted SSID is the SSID generated and transmitted by the access point 801 itself (step S48). If the SSID generated by the access point 801 is a regular SSID, the process proceeds to step S49. A connection permission frame is transmitted to the terminal 802.

  On the other hand, if the SSID is not a regular SSID, the process advances to step S44 to check whether or not the virtual SSID is generated by the virtual SSID processing unit 1104 of the access point 801.

  If it is not the virtual SSID generated by the virtual SSID processing unit 1104 of the access point 801 in step S44, a connection non-permission frame is transmitted to the terminal (step S46).

On the other hand, in the case of the virtual SSID generated by the virtual SSID processing unit 1104 of the access point 801, it does not respond to the connection request or is a virtual SSID for the terminal 802 corresponding to the virtual SSID. A connection non-permission frame including a reason code indicating that connection is not permitted is returned to the terminal 802 (step S45).
(1-5) Operation between Access Point and Terminal by Information Distribution System Next, a frame response between the access point 801 and the terminal 802 in the present embodiment is shown with reference to the sequence diagram of FIG.

  First, in step S81, step S82, and step S83, the access point 801 transmits a beacon frame toward the terminal 802.

  In each SSID field of these three beacons, data to be transmitted from the access point 801 to the terminal 802 is stored.

  In general, beacon frames are continuously transmitted in the order of SSIDs obtained by dividing information to be transmitted. However, it is not always necessary to transmit such beacon frames.

  Next, in step S84, the terminal 802 generates a connection request frame from the beacon frame of SSID: C, and transmits the connection request frame to the access point 801.

  In step S85, SSID: C is managed as a virtual SSID by the access point 801, and a response frame is not transmitted in response to a connection request from the terminal 802.

  Therefore, on the terminal 802 side, a time-out process is performed, and it is recognized that connection to SSID: C is impossible.

  In step S86, as with SSID: C, the terminal 802 generates a connection request frame from the beacon frame in which SSID: B is stored by the access point 801, and transmits the connection request frame to the access point 801.

  Since this frame is also managed as a virtual SSID by the access point 801 as in step S85, the access point 801 does not return a response to the terminal 802 (step S87).

  Thereby, on the terminal 802 side, a timeout process is performed, and it is recognized that connection to SSID: B is impossible.

  In step S 88, terminal 802 generates a connection request frame from the remaining beacon frame storing SSID: A from access point 801, and transmits the connection request frame to access point 801.

In this case, since the access point 801 manages SSID: A as a regular SSID by the access point 801, the access point 801 returns a connection permission response to the terminal 802.
(1-6) Effect of Information Distribution System in First Embodiment According to the present embodiment, the type of SSID to be managed differs for the information transmitted from the access point 801 to the terminal 802. Depending on the type of SSID, if the connection request transmitted by the terminal 802 is a regular SSID, the connection is permitted. If the connection request is not a regular SSID but a virtual SSID, the connection is not permitted.

Thereby, the access point 801 can connect the terminal 802 to the network of the regular SSID only in the case of the regular SSID by not transmitting a response frame to the connection request including the virtual SSID from the terminal 802.
(2) Information distribution system according to second embodiment (2-1) Operation between access point and terminal by information distribution system Next, the information distribution system according to the second embodiment will be described in detail with reference to the drawings. Explained.

  The sequence diagram of FIG. 11 shows a frame response between the access point 801 and the terminal 802 of the information distribution system according to the second embodiment.

  In the second embodiment, the terminal 802 is assumed to be a terminal that supports a virtual SSID.

  First, in step S101, step S102, and step S103, the access point 801 transmits a beacon frame toward the terminal 802.

  In each SSID field of these three beacons, data to be transmitted from the access point 801 to the terminal 802 is stored.

  In step S <b> 104, the terminal 802 generates a connection request frame from the beacon frame of SSID: C, and transmits the connection request frame to the access point 801.

  In step S105, since the SSID: C is managed as a virtual SSID by the access point 801, the access point 801 responds to the connection request from the terminal 802 with a connection non-permission response including the reason for the virtual SSID. Send.

  Here, when the access point 801 returns a connection rejection response frame including the reason for the virtual SSID to the terminal 802, the terminal 802 corresponding to the virtual SSID automatically establishes a connection with another SSID. An attempt is made (step S106).

  This does not necessarily include the fact that it is a virtual SSID, as long as it includes a reason that the terminal 802 automatically tries to connect using another SSID.

  In this case, unlike the first embodiment, since there is no timeout process in the sequence between the access point 801 and the terminal 802, it can be expected that a faster reconnection process is performed.

  In step S106 and step S017, as in the first embodiment, in response to a connection request using a virtual SSID, a connection rejection response including a reason that the access point 801 is a virtual SSID transmitted to the terminal 802. Send a frame.

  In step S <b> 108, terminal 802 generates a connection request frame from the remaining beacon frame storing SSID: A from access point 801, and transmits the connection request frame to access point 801.

  In this case, in the access point 801, SSID: A is managed as a regular SSID in the access point 801.

Accordingly, the access point 801 returns a connection permission response to the terminal 802.
(2-2) Effect of Information Distribution System in Second Embodiment According to the second embodiment, the access point 801 is a virtual SSID in response to a connection request including a virtual SSID from the terminal 802. By transmitting a connection disapproval response frame including the reason to that effect to the terminal 802, the access point 801 can be transmitted to the access point 801 with respect to the terminal 802.

As a result, the access point 801 can permit connection with the terminal 802 using a regular SSID.
(3) Information distribution system according to third embodiment (3-1) Operation between access point and terminal by information distribution system Next, the information distribution system according to the third embodiment will be described in detail with reference to the drawings. Explained.

  The sequence diagram of FIG. 12 shows a frame response between the access point 801 and the terminal 802 of the information distribution system according to the third embodiment.

  First, in step S121, step S122, and step S123, the access point 801 transmits a beacon frame to the terminal 802.

  In each SSID field of these three beacons, data to be transmitted from the access point 801 to the terminal 802 is stored.

  In step S124, the terminal 802 generates a connection request frame from the beacon frame of SSID: C, and transmits the connection request frame to the access point 801.

  In step S125, the access point 801 issues a handover request to another SSID (regular SSID, SSID: A) in response to the connection request frame S124 from the terminal 802, and the access point 801 does not connect to the terminal 802. Send permission frame.

  In step S126, in response to the handover request from the access point 801 (step S125), the terminal 802 transmits a connection request frame including the proposed handover destination SSID: A to the access point 801. .

In step S127, the access point 801 transmits a connection permission response frame to the terminal 802 in response to a connection request (step S126) based on the regular SSID from the terminal 802.
(3-2) Effect of Information Distribution System in Third Embodiment According to the third embodiment, the access point 801 responds to the connection request including the virtual SSID from the terminal 802 as the handover destination SSID. By transmitting a handover request including a proposal of a regular SSID to the terminal 802 and responding, the terminal 802 can transmit a regular SSID connection request to the access point 801 and permit the connection.
(4) Information distribution system according to fourth embodiment (4-1) Operation between access point and terminal by information distribution system Next, the information distribution system according to the fourth embodiment will be described in detail with reference to the drawings. Explained.

  The sequence diagram of FIG. 13 shows a frame response between the access point 801 and the terminal 802 of the information distribution system in the fourth embodiment.

  First, in step S141, step S142, and step S143, the access point 801 transmits a beacon frame to the terminal 802.

  In each SSID field of these three beacons, data to be transmitted from the access point 801 to the terminal 802 is stored.

  In step S144, the terminal 802 generates a connection request frame from the beacon frame of SSID: C, and transmits the connection request frame to the access point 801.

  In step S145, the access point 801 transmits a temporary connection permission response frame from the access point 801 to the terminal 802 in response to the connection request including the virtual SSID from the terminal 802.

  In step S146, the access point 801 transmits a handover request including the normal SSID and the handover destination SSID: A from the access point 801 to the terminal 802 after a temporary connection permission response from the access point 801 to the terminal 802. .

  In step S147, in response to the handover request from the access point 801 (step S146), the terminal 802 transmits a connection request frame including the proposed normal SSID: A of the handover destination included in the access point 801. Send to.

In step S148, the access point 801 transmits a connection permission response frame to the terminal 802 in response to the connection request (step S147) using the regular SSID from the terminal 802.
(4-2) Effect of Information Distribution System in Fourth Embodiment According to the present embodiment, the access point 801 transmits a temporary connection permission to the terminal 802 and at the same time, is a regular SSID handover destination Therefore, the terminal 802 can transmit a connection request frame including a regular SSID to the access point 802.

As a result, the access point 801 can permit connection with the terminal 802 using a regular SSID.
(5) Example Next, the operation | movement corresponding to embodiment in this invention is demonstrated using a specific Example.

  FIG. 14 specifically shows a case where the access point 801 transmits information to the terminal 804 as a specific example.

  Here, the terminal may be any of the terminals 802 to 804, but will be described using the terminal 804 from the shape of the terminal screen to be displayed.

  The terminal screen of the terminal 802 shown in FIG. 14 shows the case where the information to be transmitted by the access point 801 is “NEC, the power to be changed, that is NEC's ubiquitous” 1301.

  First, the virtual SSID processing unit 1104 (FIG. 5) converts “NEC, the power to be changed, that is NEC's ubiquitous”, which is information to be sent, into a unit smaller than 32 bytes and easy to read by humans. To divide.

  In this case, the virtual SSID processing unit 1104 divides it into three parts: “NEC” 1302, “Changing power” 1303, and “That is NEC's ubiquitous” 1304.

  Each divided information is stored as a different SSID in a beacon frame transmitted from the access point 801 and transmitted to the terminal 804.

  In this case, the normal SSID is “NEC” 1302, and the virtual SSID is “the power of changing” 1302 and “that is NEC's ubiquitous” 1304.

  The terminal 804 that has received the beacon frame including the SSID extracts the SSID from the beacon frame and displays it on the screen of the terminal 804.

  As a result, even when the connection request is transmitted to the access point 801 using “NEC” which is a regular SSID or when the connection request is transmitted using another SSID, the terminal 804 finally transmits the regular request. Connected to the network represented by the SSID “NEC”, the connection process ends.

  According to the present invention, it can be applied to uses such as local advertisement and wireless LAN connection service using the SSID field in a beacon frame of a wireless LAN.

It is a schematic diagram which shows the structure of the information delivery system by 1st Embodiment concerning this invention. It is a figure which shows the example of a screen display when the terminal of the information delivery system by the 1st Embodiment which concerns on this invention receives several SSID and several beacon frames. It is a block diagram of the communication apparatus which comprises the terminal by 1st Embodiment concerning this invention. It is a block diagram explaining the structure of the terminal by the 1st Embodiment which concerns on this invention. It is a block diagram explaining the structure of the access point by the 1st Embodiment which concerns on this invention. In the first embodiment according to the present invention, when the information to be transmitted in the SSID field in the beacon frame exceeds the maximum length of the SSID field, it is divided into a plurality of SSIDs and transmitted. It is. 5 is a flowchart showing an overall operation when a terminal performs an operation of connecting to an access point in the first embodiment of the present invention. In 1st Embodiment which concerns on this invention, it is a flowchart which shows the beacon transmission operation | movement which transmits the information which an access point should transmit. 5 is a flowchart showing a response operation to an attribution request frame from a terminal in the first embodiment according to the present invention. In 1st Embodiment based on this invention, it is a sequence diagram which shows the mechanism in which an access point connects with a regular SSID by not responding to the connection request from the terminal by virtual SSID. In the 2nd Embodiment which concerns on this invention, it is a sequence diagram which shows the mechanism in which an access point connects with a regular SSID by making a non-permission response with a reason with respect to the connection request from the terminal by virtual SSID. In the third embodiment of the present invention, an access point connects to a regular SSID by returning a non-permission response including a request for handover to a regular SSID in response to a connection request from a terminal using a virtual SSID. FIG. In the fourth embodiment according to the present invention, the access point temporarily permits connection in response to a connection request from a terminal using a virtual SSID, and then transmits a handover request to a regular SSID to the terminal. It is a sequence diagram which shows the mechanism connected to regular SSID. It is the figure which showed the transmission state which transmitted the information using several SSID and several beacon frames from the access point to the terminal in the specific Example which concerns on this invention, and the state displayed on the terminal screen. In the nonpatent literature 1, it is the schematic diagram which showed the relationship between an access point and a terminal, and the relationship of SSID of an access point. In nonpatent literature 1, it is a sequence figure showing that a beacon frame is transmitted with a fixed cycle from an access point toward a terminal. In nonpatent literature 1, it is a mimetic diagram showing the frame format (beacon frame format) of the beacon frame transmitted with a fixed cycle from an access point toward a terminal. In nonpatent literature 1, it is a mimetic diagram showing the example of a display in which a terminal receives a beacon frame transmitted with a fixed cycle from an access point toward a terminal, extracts SSID in it, and displays it on a terminal screen. In nonpatent literature 1, it is a sequence figure showing the state which transmits a connection request frame from a terminal to an access point based on the beacon frame which a terminal received, and transmission and reception of the data frame and ACK frame which accompany it. 1 is a schematic diagram showing an information distribution system provided with a wireless LAN hot spot in Patent Document 1. FIG. 10 is a block diagram illustrating a configuration of an event information distribution system of an information distribution system in Patent Literature 1. FIG. 10 is a block diagram showing a configuration of a wireless LAN access point of an information distribution system in Patent Document 1. FIG. 10 is a block diagram showing a configuration of an event information receiving terminal of an information distribution system in Patent Document 1. FIG. 10 is a schematic diagram illustrating transmission and reception of radio wave beacons between a wireless LAN access point and an event information receiving terminal of the information distribution system in Patent Document 1. FIG. 10 is a schematic diagram showing transmission and reception of information among an event information distribution server, a wireless LAN access point, and an event information receiving terminal of an information distribution system in Patent Document 1. FIG.

Explanation of symbols

101 Corporate terminal 102 Event information distribution system 102-1 Event information collection server 102-2 Event information distribution server 102-2-1 Distribution content 103 Wireless LAN access point 103A, 103B Wireless LAN access point 103-1 Event information receiving unit 103- 2 Radio wave beacon transmitting unit 104 Event information receiving terminal 104A, 104B, 104C Event information receiving terminal 104-1 Radio beacon receiving unit 104A-1 Radio beacon receiving unit 104B-1 Radio beacon receiving unit 104C-1 Radio beacon receiving unit 104-2 Event information display unit 105 Hot spot 106 Internet 501, 501A, 501B Access point 502A, 502B Terminal 701, 702, 703 SSID
801 Access point 802, 803, 804 Terminal 901 Communication device 902 Application 903 MAC
904 Physical layer 9030 MAC
9040 Physical layer 1001 SSID display unit 1002 SSID data processing unit 1003 SSID field extraction unit 1004 Frame analysis unit 1005 Connection processing unit 1101 Frame type processing distribution unit 1102 Frame analysis unit 1103 Connection processing unit 1104 Virtual SSID processing unit 1105 SSID field extraction unit 1106 Beacon frame generation unit 1107 SSID transmission information management unit 1201 Information to be sent 1202 Regular SSID
1203, 1204 Virtual SSID
1301 Information to be sent 1302 Regular SSID
1303, 1304 Virtual SSID

Claims (18)

An information distribution system in a wireless packet communication system comprising a wireless terminal and an access point that transmits a broadcast packet to the wireless terminal at a constant cycle,
The access point is
Generating a transmission packet of the same format as the broadcast packet, storing information in an SSID field for storing a network identifier of the transmission packet, and managing SSID transmission information management means;
When the field length of the information is larger than the SSID field by the SSID transmission information management means, the information is divided, each divided information is stored in the SSID field, and a plurality of transmission packets are generated. Information dividing packet generating means to perform,
A transmission packet transmitting means for transmitting the transmission packet storing the information to the wireless terminal;
Connection request receiving means for receiving a connection request frame transmitted by the connection request transmitting means of the wireless terminal;
A connection response determination unit that acquires stored terminal-side information from the received connection request frame and determines permission of connection to the wireless terminal based on the acquired terminal-side information;
A connection permission response frame transmitting means for transmitting a connection permission response frame to the wireless terminal when allowing connection to the wireless terminal by the connection response determining means;
The wireless terminal is
Connection request transmission that receives the transmission packet, creates the connection request frame for requesting connection to the access point based on the information included in the transmission packet, and transmits the connection request frame to the access point means,
An information distribution system comprising: The wireless terminal is
A terminal capable of supporting a virtual network identifier,
In the connection request transmission means, the network identifier, or based on the virtual network identifier, create the connection request frame,
The access point is
The information stored in the SSID transmission information management means is a network identifier of the transmission packet or the virtual network identifier different from the network identifier,
The terminal-side information acquired by the connection response determination unit is the network identifier, or the connection permission for the wireless terminal is determined based on the virtual network identifier. Information distribution system. The connection response determining means includes
When the terminal-side information is the virtual network identifier, it is determined that the connection to the wireless terminal is not permitted, and a connection non-permission packet that transmits a connection non-permission packet including information indicating the virtual network identifier The information distribution system according to claim 2, further comprising a transmission unit. The connection response determining means includes
When the terminal side information is the virtual network identifier, it is determined that connection is not permitted for requesting handover to the network with the regular network identifier, and a connection disapproval packet including handover request information is sent to the wireless terminal. The information distribution system according to claim 2, further comprising a handover request connection non-permission packet transmission unit for transmission. The connection response determining means includes
When the terminal side information is the virtual network identifier, temporary connection permission packet transmitting means for permitting temporary connection to the network of the virtual network identifier and transmitting the connection permission packet;
It further comprises connection change packet transmitting means for transmitting a connection change packet including handover request information for requesting handover to the network of the regular network identifier after transmitting the connection packet permitting the temporary connection. The information distribution system according to claim 2, wherein the system is an information distribution system. An information distribution method in a wireless packet communication system comprising a wireless terminal and an access point that transmits a broadcast packet to the wireless terminal at a constant cycle,
The access point generates a transmission packet of the same format as the broadcast packet, stores information in an SSID field that stores a network identifier of the transmission packet, and manages the information by an SSID transmission information management step;
In the SSID transmission information management step, when the field length of the information is larger than the SSID field, the access point divides the information, stores each divided information in the SSID field, and An information division packet generation step for generating a transmission packet of
A transmission packet transmission step in which the access point transmits the transmission packet in which the information is stored to the wireless terminal;
The wireless terminal receives the transmission packet, creates a connection request frame for requesting connection to the access point based on the information included in the transmission packet, and transmits the connection request frame to the access point A connection request sending step,
A connection request receiving step in which the access point receives the connection request frame transmitted in the connection request transmitting step;
A connection response determination step in which the access point acquires stored terminal side information from the received connection request frame, and determines permission of connection to the wireless terminal based on the acquired terminal side information. When,
When the access point permits connection to the wireless terminal in the connection response determination step, a connection permission response frame transmission step of transmitting a connection permission response frame to the wireless terminal;
An information delivery method comprising: The wireless terminal is a terminal capable of supporting a virtual network identifier,
In the access point, the information stored in the SSID transmission information management step is a network identifier of the transmission packet, or the virtual network identifier different from the network identifier,
In the connection request transmission step, the wireless terminal creates the connection request frame based on the network identifier or the virtual network identifier,
The access point determines whether the terminal side information acquired in the connection response determination step is the network identifier, or permission of connection to the wireless terminal based on the virtual network identifier. The information delivery method according to claim 6. The connection response determining step includes:
When the terminal-side information is the virtual network identifier, it is determined that the connection to the wireless terminal is not permitted, and a connection non-permission packet that transmits a connection non-permission packet including information indicating the virtual network identifier The information distribution method according to claim 7, further comprising a transmission step. The connection response determining step includes:
When the terminal side information is the virtual network identifier, it is determined that the connection is not permitted for requesting handover to the network with the regular network identifier, and a handover request for transmitting a connection not permitted packet including handover request information The information distribution method according to claim 7, further comprising a connection non-permission packet transmission step. The connection response determining step includes:
When the terminal-side information is the virtual network identifier, a temporary connection permission packet transmission step of allowing the temporary connection to the network of the virtual network identifier and transmitting the connection permission packet;
A connection change packet transmission step of transmitting a connection change packet including handover request information for requesting handover to the network of the regular network identifier after transmitting the connection packet permitting the temporary connection; 8. The information delivery method according to claim 7, wherein In an information distribution device that transmits a broadcast packet to a wireless terminal at a fixed period,
Generating a transmission packet of the same format as the broadcast packet, storing information in an SSID field for storing a network identifier of the transmission packet, and managing SSID transmission information management means;
When the field length of the information is larger than the SSID field, the information is divided, each divided information is stored in the SSID field, and information divided packet generating means for generating a plurality of transmission packets;
A transmission packet transmitting means for transmitting the transmission packet storing the information to the wireless terminal;
Connection request receiving means for receiving a connection request frame transmitted from the wireless terminal;
A connection response determination unit that acquires stored terminal-side information from the received connection request frame and determines permission of connection to the wireless terminal based on the acquired terminal-side information;
When permitting connection to the wireless terminal by the connection response determining means, a connection permission response frame transmitting means for transmitting a connection permission response frame to the wireless terminal;
An information distribution apparatus comprising: The information stored in the SSID transmission information management means is a network identifier of the transmission packet, or a virtual network identifier different from the network identifier,
The terminal-side information acquired by the connection response determination unit is the network identifier, or the connection permission for the wireless terminal is determined by the virtual network identifier. Information distribution device. An information distribution method in an information distribution apparatus for transmitting a broadcast packet to a wireless terminal at a constant cycle,
SSID transmission information management step for generating a transmission packet of the same format as the broadcast packet, storing information in an SSID field for storing a network identifier of the transmission packet, and managing the information;
When the field length of the information is larger than the SSID field, the information is divided, each divided information is stored in the SSID field, and an information divided packet generating step for generating a plurality of transmission packets;
A transmission packet transmission step of transmitting the transmission packet in which the information is stored to the wireless terminal;
A connection request receiving step of receiving a connection request frame transmitted from the wireless terminal;
A connection response determination step of acquiring stored terminal side information from the received connection request frame and determining permission of connection to the wireless terminal based on the acquired terminal side information;
When permitting connection to the wireless terminal in the connection response determining step, a connection permission response frame transmitting step of transmitting a connection permission response frame to the wireless terminal;
An information delivery method comprising: The information stored in the SSID transmission information management step is a network identifier of the transmission packet, or a virtual network identifier different from the network identifier,
The terminal-side information acquired in the connection response determination step is the network identifier, or the permission of connection to the wireless terminal is determined based on the virtual network identifier. Information delivery method. An information distribution program in an information distribution apparatus that transmits a broadcast packet to a wireless terminal at a constant cycle,
Generating a transmission packet of the same format as the broadcast packet, storing information in an SSID field storing a network identifier of the transmission packet, and managing an SSID transmission information management procedure;
When the field length of the information is larger than the SSID field, the information is divided, each divided information is stored in the SSID field, and an information divided packet generation procedure for generating a plurality of transmission packets;
A transmission packet transmission procedure for transmitting the transmission packet in which the information is stored to the wireless terminal;
A connection request reception procedure for receiving a connection request frame transmitted from the wireless terminal;
A connection response determination procedure for acquiring stored terminal side information from the received connection request frame and determining permission of connection to the wireless terminal based on the acquired terminal side information;
When permitting connection to the wireless terminal by the connection response determination procedure, a connection permission response frame transmission procedure for transmitting a connection permission response frame to the wireless terminal;
An information distribution program for causing a computer to execute The information stored in the SSID transmission information management procedure is a network identifier of the transmission packet or a virtual network identifier different from the network identifier,
The terminal side information acquired in the connection response determination procedure is the network identifier, or causes the computer to determine whether the wireless terminal is permitted to connect based on the virtual network identifier. The information delivery program according to claim 15. The information distribution device according to claim 11 or 12,
An information distribution apparatus, further comprising: a language code conversion storage unit that encodes the information with a language code and converts the information so as to be stored in the SSID field. The wireless terminal according to claim 1 or 2,
A wireless terminal further comprising language code restoration means for recognizing that the information included in the transmission packet is coded by a language code and decoding the coded information.

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