Abstract:
A data communication system and data communication operating method capable of providing a asynchronous data communication service to a public switching telephone network, X.25 network, and Internet by extensively applying a packet assembler deassembler (PAD) function to an interworking function device provided in a code division multiple access (CDMA) type data communication system. If a certain mobile station requests the asynchronous data service, the data communication system analyzes the condition of terminating information inputted by a user of the mobile station, and selectively connects the mobile station to a public switching telephone network, X.25 network, and Internet according to the result of analysis.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a data communication system and data communication operating method. In particular, the present invention relates to a data communication system and data communication operating method which can provide a data communication service by selectively routing to a public switching telephone network (PSTN), X.25 network, and Internet by extensively applying a packet assembler deassembler (PAD) function to an interworking function device provided in a code division multiple access (CDMA) type data communication system. 
     2. Description of the Related Art 
     Generally, the network structure of an asynchronous circuit data service (service option  4 , 12 ) using the CDMA system recommended by TIA/EIA/IS-99/657/658 is illustrated in FIG.  1 . 
     Referring to FIG. 1, a user of a mobile station requests the asynchronous circuit data service using an AT command. At this time, a mobile phone  2  combined with a data terminal  1  which can be selected among a notebook, personal digital assistant (PDA), laptop, palmtop, portable computer, compact computer, etc., may be used as the mobile station. According to the present invention, it is assumed that the data terminal is the notebook. As is well known, the mobile phone, i.e., the mobile terminal  2  seizes a base transmission station (BTS)  3 , and is connected to a mobile switching center (MSC)  5  through a base station controller (BSC)  4 . 
     A mobile subscriber processing section  51  in the mobile switching center  5  then analyzes the service option when it receives a call connection request from the mobile terminal  2 . At this time, the service option may be classified in accordance with connection/disconnection of the data terminal  1  and the mobile terminal  2  and the inputted AT command. If the user requests the asynchronous circuit data service, a mobile data path is determined from a mobile data path processing section  52  of the mobile switching center  5  to a mobile data path processing section  61  of an interworking function device (IWF)  6  as a communication path. Thereafter, the mobile terminal  2  and a protocol processing section  62  of the interworking function device  6  determine a point-to-point protocol (PPP) and TCP/IP through the determined mobile data path. If the TCP/IP is determined, the mobile terminal  2  transmits the AT command, which has been recognized or has not been recognized, to an IS-99 protocol processing section  63  of the interworking function device  6 . 
     The IS-99 protocol processing section  63  of the interworking function device  6  seizes a modem, and processes the contents recommended by the EIA/TIA/IS-99 with respect to the AT command. 
     Especially with respect to an ATD command, the IS-99 protocol processing section  63  analyzes a next command following the ATD command, extracts a terminating number, and then connects a call to the public switching telephone network path processing section  65  of the interworking function device  6 . The public switching telephone network path processing section  65  requests the call to a public switching telephone network path processing section  54  of the mobile switching center  5  by using the terminating number extracted from the IS-99 protocol processing section  63 . The public switching telephone network path processing section  54  of the mobile switching center  5  detects whether the terminating number corresponds to the terminating call to the mobile subscriber or the terminating call to the public switching telephone network by analyzing the terminating number. In case of the terminating call to the public switching telephone network  10 , the public switching telephone network path processing section  54  connects the call to a wired terminal connected to the public switching telephone network  10  of the mobile switching center  5  through a trunk processing section  53  of the mobile switching center  5 . However, in case of the terminating call to the mobile subscriber, the public switching telephone network path processing section  54  searches location information of the subscriber by communicating with a home location register (HLR) or a visitor location register (VLR). At this time, if the terminating call is the call for the subscriber of the intra mobile switching center as the result of search, the public switching telephone network path processing section  54  connects the call to the interworking function device  6  through the public switching telephone network path processing section  54  of the mobile switching center, while if the terminating call is the call for the subscriber of the inter mobile switching center, it connects the call to another mobile switching center through the trunk processing section  53 . 
     However, according to the conventional network structure, only the calls with the public switching telephone network  10  can be processed in case of the asynchronous circuit data service (service option  4 ,  12 ). Accordingly, in the CDMA type data communication system, the data communication service with the X.25 network and Internet, which are generally used, cannot be provided by the asynchronous circuit data service option. 
     Further, the user should necessarily input the terminating number in order to receive the CDMA asynchronous circuit data service, and should remember the IP server connection numbers in order to connect with the IP servers of the public switching telephone network  10 , using the asynchronous circuit data service. 
     Furthermore, in order for the user to process the terminating call to the public switching telephone network  10 , a waiting time which is longer than that in the wired network is required for identifying the connection state with a wired terminal connected to the public switching telephone network. Specifically, the connection time between the mobile station and the mobile switching center  5 , and the protocol negotiation time between the protocol processing section  62  of the interworking function device  6  and the mobile terminal  2  are required. The negotiation time may be varied according to the radio environment, and may be about 4 to 10 seconds. Also, the negotiation time between the modem  64  of the interworking function device  6  and the modem  7  connected to the public switching telephone network  10  may be about 7 to 10 seconds. 
     SUMMARY OF THE INVENTION 
     Accordingly, the present invention is directed to a data communication system and data communication operating method that substantially obviate one or more of the problems due to limitations and disadvantages of.the related art. 
     An object of the present invention is to provide a data communication system and data communication operating method which can provide data communication service to a public switching telephone network, X.25 network, and Internet by extensively applying a packet assembler deassembler (PAD) function to an interworking function device of a CDMA type data communication system. 
     It is another object of the present invention to provide a data communication system and data communication operating method which can receive an asynchronous circuit data service without inputting a terminating number, and which can connect with an IP server of a public switching telephone network using an asynchronous circuit data service without the necessity of remembering an IP server connection number. 
     It is still another object of the present invention to provide a data communication system and data communication operating method which can provide a waiting time faster than that in a wired network in case of identifying the connection state with a wired terminal connected to a public switching telephone network. 
     Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims thereof as well as the appended drawings. 
     To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, the data communication system is characterized in that if a certain mobile station requests a data service, the data communication system analyzes the condition of terminating information inputted by a user of the mobile station, and selectively connects the mobile station to a public switching telephone network, X.25 network, and Internet. 
     In another aspect of the present invention, there is provided a data communication operating method comprising the steps of determining a data transmission path between a certain mobile station and an interworking function device if the mobile station requests a data service, analyzing the condition of terminating information inputted by a user of the mobile station, and selectively connecting the mobile station to a public switching telephone network, X.25 network, and Internet according to the result of analyzing the condition of terminating information. 
     According to the present invention as described above, a mobile station can be selectively connected to a public switching telephone network, X.25 network, and Internet by extensively applying a PAD function to an interworking function device during an asynchronous circuit data service. Also, a menu for connecting with a host server of the X.25 network, Internet, and public switching telephone network is provided to a terminal user by applying an extensive terminal number analyzing function to the PAD, and thus a call from the mobile station is connected to the respective host server of the X.25 network, Internet, and public switching telephone network if the menu is selected, while the call is connected to a mobile switching center if another number is inputted. Also, according to the present invention, it is not required for the user to remember the connection number of the host server. Specifically, since the connection menu is transmitted from the PAD of the interworking function device to the terminal user before the complete connection to the wired network, the terminal user can receive a response menu faster than the wired network, thereby enabling a very convenient data service. 
     It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention: 
     In the drawings: 
     FIG. 1 is a view illustrating the structure of the circuit data service network in a conventional CDMA type data communication system. 
     FIG. 2 is a block diagram explaining the call process operation during the asynchronous circuit data service in a conventional CDMA type data communication system. 
     FIG. 3 is a view illustrating the structure of the circuit data service network in a CDMA type data communication system according to the present invention. 
     FIG. 4 is a block diagram explaining the call process operation during the asynchronous circuit data service in a CDMA type data communication system according to the present invention. 
     FIG. 5 is a view illustrating the structure of the asynchronous data circuit service protocol stack according to the present invention. 
     FIG. 6 is a view illustrating the structure of the X.25-connected asynchronous data circuit service protocol stack according to the present invention. 
     FIG. 7 is a view illustrating the structure of the Internet-connected asynchronous data circuit service protocol stack according to the present invention. 
     FIG. 8 is a flowchart explaining the call process operation during the asynchronous circuit data service in a CDMA type data communication system according to one embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. 
     FIG. 3 is a view illustrating the structure of the circuit data service network in a CDMA type data communication system according to the present invention. 
     Referring to FIG. 3, the CDMA data communication system according to the present invention includes a plurality of mobile station (MS)  20 , a plurality of base transmission station  30  for repeating the radio communications of the mobile stations in terms of region, a base station controller  40  for controlling the operation of the respective base stations  30 , a mobile switching center  50  for determining a communication path in accordance with a communication service required by the mobile station  20 , an interworking function device  60 , connected to the mobile switching center  50 , for interworking with an public switched telephone network  100  or an X.25 network  200  or an Internet  300 , and a router  310  for performing a routing operation so that the interworking function device  60  is connected to the Internet  300 . 
     Here, it is preferable that a protocol processing section  62 , IS-99 protocol processing section  63 , and PAD processing section  66  are installed on the same hardware. 
     Also, a subscriber such as an enterprise can connect with a desired communication network by connecting the interworking function device  60  directly to a LAN  400 , not through the router  310 . 
     The mobile subscriber processing section  51  of the mobile switching center  50  analyzes whether the call is the voice call or data call according to the service option determined by the user, and if the call is the data call, it connects the data call to the mobile data processing section  52 . The trunk processing section  53  interworks with the public switching telephone network  100 . 
     Also, the mobile data path processing section  52  provided in the mobile switching section  50  and the interworking function device  60 , respectively, performs a frame relay interface recommended by EIA/TIA/IS-658. 
     The interworking function device  60  comprises a mobile data path processing section  61  for performing a frame relay interface recommended by EIA/TIA/IS-658, a protocol processing section  62  for performing a point-to-point protocol (PPP: RFC 1661), Internet protocol (IP: RFC 791), and transmission control protocol (TCP: RFC 793) with the mobile station  20  in accordance with a path determination of the mobile data path processing section  61 , an IS-99 protocol processing section  63  for analyzing terminating information inputted by a user and then transmitted through the protocol processing section  62 , a PAD processing section  66  for receiving a terminating number extracted by the IS-99 protocol processing section  63  and transmitting to the mobile station  20  a PAD service menu stored therein, or discriminating whether the terminating number included in the terminating information corresponds to a subscriber of a public switching telephone network  100 , X.25 network  200 , or Internet  300 , a communication modem  64  for connecting with the IS-99 protocol processing section  63  if the terminating number is discriminated by the PAD processing section  66  to correspond to the subscriber of the public switching telephone network  100 , a public switching telephone path processing section  65  for connecting the communication path to the public switching telephone network  100 , an X.25 protocol processing section  67  for connecting the communication path to the X.25 network  200  if the terminating number is discriminated by the PAD processing section  66  to correspond to the subscriber of the X.25 network  200 , and a PPP server  320  for determining a packet data link with the mobile station and the Internet  300  if the terminating number is discriminated by the PAD processing section  66  to correspond to the subscriber of the Internet  300 . 
     Here, if the IS-99 protocol processing section  63  transfers the terminating number following an ATD command to the PAD processing section  66 , the PAD processing section  66  analyzes the terminating number. 
     The operation of the data communication system according to the preferred embodiment of the present invention will now be explained with reference to FIGS. 3 to  8 . 
     If the data terminal  10  of FIG. 3 requests the asynchronous circuit data service by the user&#39;s selection of the service option (ST 1 ), the mobile terminal  20  connected to the data terminal  10  is connected to the mobile subscriber processing section  61  of the mobile switching center  50  through the base station controller  40  as shown in FIG.  4 . Specifically, the user of the mobile station (MS) is connected to the interworking function device  60  like a null modem so that the analysis of the terminating number and the transmission of the PAD service menu can be easily performed. The mobile subscriber processing section  51  of the mobile switching center  50  connects the call directly to the trunk processing section  53  if the user requests the voice service, while it connects with the mobile data path processing section  52  of the mobile switching center  50  if the user requests the data service. The mobile data path processing section  52  determines the connection mobile data path by performing data communications with the mobile data path processing section  61  of the interworking function device  60 . The mobile terminal  20  and the protocol processing section  62  of the interworking function device  60  determine the PPP and TCP/IP protocol, so that a data transmission path is open between the data terminal  10  and the protocol processing section  62  of the interworking function device  60 . 
     If the ATD command inputted by the user of the data terminal  10  is transmitted to the IS-99 protocol processing section  63  for processing the ATD command by EIA/TIA/IS-99 through the data transmission path formed between the mobile station (MS) and the protocol processing section  62 , the IS-99 protocal processing section  63  extracts a next command following the ATD command (ST 2 ), and then analyzes the recognized command (ST 3 ) to transfer the terminating number following the ATD command to the PAD processing section  66 . The PAD processing section  66  analyzes the terminating number and classifies the result of analysis into four cases: a first case that no terminating number exists following the ATD command; a second case that the number is the PAD terminating number stored in and then provided from the interworking function device  60 ; a third case that the number is the host number connective from the interworking function device  60 ; and a fourth case that the number is the terminating number which does not correspond to any of the above three cases. 
     The PAD processing section  66  performs the following extensive operations with respect to the above four cases. 
     In the first case that no terminal number exists as a result of analyzing the terminating number following the ATD command, the PAD processing section  66  transmits the PAD service menu pre-stored in the interworking function device  60  to the data terminal  10  through the pre-formed data transmission path (ST 6 ). At this time, the user, watching the PAD service menu provided on the screen of the data terminal  10 , selects the server connection menu number or Internet connection number, or inputs the terminating number desired to be connected according to the X.28 recommendations or only the terminating number. Here, the PAD service menu of the interworking function device  60  provided from the PAD processing section  66  provides both the host menu selection number for connecting with X.25 network  200  or Internet  300  and the IP host menu selection number for connecting with the public switching telephone network  100 . 
     Accordingly, the PAD processing section  66  analyzes whether the number inputted by the user is the server connection menu selection number, Internet connection menu, terminal number inputted based on the X.28 recommendations, or only the terminating number (ST 8 ). 
     If the number is the server connection menu selection number as a result of analysis, the PAD processing section  66  analyzes the menu selection number again. If the number corresponds to the IP server of the public switching telephone network  100  (for instance, the data terminal device ( 80   a ) of FIG.  3 ), the PAD processing section  66  seizes the communication modem  64  (ST 7 ), and connects with the public switching telephone network path processing section  65  of the interworking function device  60  to connect with the public switching telephone network (ST 9 ). 
     If the number is the host terminating number provided from the PAD menu as a result of analyzing the terminating number following the ATD command, the PAD processing section  66  discriminates if the number is the X.25 host number (ST 4 ). At this time, if the number corresponds to the host connected to the X.25 network  200  (for instance, the data terminal device ( 80   b ) of FIG.  3 ), the PAD processing section  66  connects with the X.25 processing section  67  of the interworking function device  60  (ST 5 ). 
     Meanwhile, if the number is the Internet connection selection menu as a result of analyzing the terminating number following the ATD command, the PAD processing section  66  of the interworking function device  60  informs the PPP server  320  of the interworking function device  60  that the Internet connection request is produced. At this time, the PPP server  320  of the interworking function device  60  and a mobile host (telephone connection networking program) determine the packet data link based on the PPP link management rule of RFC 1661 (ST 10 ). At this time, if the PPP link control protocol (LCP) is open, the PPP server  320  of the interworking function device  60  allocates the IP to the mobile host by driving the PPP Internet protocol control protocol (IPCP) (ST 11 ). The main function of the PPP Internet protocol control protocol (IPCP) is to allocate the IP to the mobile host, and this is conformable to the RFC 1332 regulations. As a result, the IP datagram is transmitted through the PPP link determined between the PPP server  320  of the interworking function device  60  and the mobile host, and the interworking function device  60  is connected to Internet  300  through the router  310  (ST 12 ). 
     If the number is the terminal number inputted based on the X.28 recommendations as a result of analysis, the PAD processing section  66  attempts to connect with the X.25 network  200  by connecting with the X.25 processing section  67  of the interworking function device  60  using the X.25 connection asynchronous data service protocol as shown in FIG.  6 . 
     Meanwhile, if only the terminal number is inputted as a result of analysis, the PAD processing section  66  seizes the communication modem  64  using the asynchronous data service protocol as shown in FIG. 5, and then connects with the public switching telephone network path processing section  65  of the interworking function device  60 . 
     In the second case that the number is the PAD terminating number provided from the interworking function device  60 , the PAD processing section  66  performs the same operation as the first case that no terminating number is inputted. 
     In the third case that the number is the host number which can be connected by the interworking function device  60 , the PAD processing section  66  does not transmits the PAD service menu provided from the interworking function device  60  to the data terminal  10 , but directly connects the PAD service menu to the X.25 processing section  67 . The X.25 processing section  67  attempts to connect to the X.25 network  200 . 
     In the fourth case that the number is the terminating number which does not correspond to any of the above three cases, the PAD processing section  66  seizes the modem  64  of the interworking function device  60 , and connects with the public switching telephone network path processing section  65  of the interworking function device  60 . The path processing section  65  of the interworking function device  60  perform the same operation as the existing asynchronous circuit data service. 
     At this time, the PAD service menu provided from the interworking function device  60  is down-loaded from a personal computer (PC) or a workstation which serves to operate the interworking function device  60 . Thus, the operator of the interworking function device  60  can optionally change the PAD service menu, and thereby the variableness and extension of the displayed menu can be provided. 
     As described above, the present invention enables the connection with the X.25 network and Internet by analyzing the terminating number by the PAD processing section as compared to the existing asynchronous data service. Also, in case that the user requests the connection with the public switching telephone network  100 , the present invention can provide a user-attractive data service by providing the PAD service menu indicating that the user is connected to the interworking function device. 
     From the foregoing, the present invention can provide a asynchronous data communication service in a CDMA type data communication system by connecting with the X.25 network or Internet not provided by the existing recommendations as well as providing the connection with the public switching telephone network. 
     Also, according to the present invention, by extensively applying the PAD function to the interworking function device, the PAD service menu can provide a PAD menu selection number of the host connected to the X.25 network and Internet, the IP enterprise connected to the public switching telephone network, thereby providing a user-attractive data service in comparison to the prior art technique. 
     Also, according to the present invention, the user can select the IP terminating number provided through the PAD menu without inputting the IP terminating section number when the user wants to connect with the IP connected to the public switching telephone network during the asynchronous data service. 
     Also, according to the present invention, in case of processing the terminating call of the public switching telephone network, the user can identify the connection state with the interworking function device  60  with a waiting time faster than that in the wired network. Specifically, according to the prior art technique, the user can identify the connection state with the IP connected to the public switching telephone network after the time period required for the connection of the mobile terminal to the interworking function device, the protocol (PPP and TCP/IP) negotiation, and the negotiation between the modem of the interworking function device and the modem connected to the public switching telephone network. However, according to the present invention, the user of the mobile terminal can see the PAD service menu before the modem negotiation by applying an extensive PAD function. Practically, the user can see the response menu of about 4 to 7 seconds faster than that in the wired network. 
     While the present invention has been described and illustrated with reference to the preferred embodiments thereof, it will be apparent to those skilled in the art that various modifications and variations can be made therein without departing from the spirit and scope of the invention. Thus, it is intended that the present invention covers the modifications and variations of this invention that come within the scope of the appended claims and their equivalents.