Abstract:
The WAN access system has: a user connection process module section for converting analog signals to digital signals so as to process information in a switching system and processing a corresponding request of a user; a WAN connection process module section for selecting TDM buses so as to enable a line switching of a packet switching and extracting data to be transferred to an AAL 1 -processing/UTOPIA-multiplexing section; and a central control process module section for controlling the WAN access system, the central control process module section being connected to the user connection process module section and the WAN connection process module section to perform switching between the TDM buses, so as to enable the line switching and the packet switching, the central control process module section performing an AAL 5  SAR processing and an SAAL processing, and an AAL 1  processing and a UTOPIA bus multiplexing.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a wide area network (WAN) access system capable of performing a line switching and a packet switching, and more particularly to a WAN access system, in which a physical layer has a connection speed of the T 1 /E 1  level, and a data layer above a physical layer can back up both the line switching and the packet switching. 
     2. Description of the Related Art 
     A WAN access system generally has a hardware, in which a specific physical layer backs up a service of a specific data layer. In this case, the physical layer has to realize different access systems according to whether the data exchanging method backed up by the data layer on a WAN protocol is a line switching method or a packet switching method, in a WAN access system having a corresponding physical layer of T 1 /E 1  level, even though the physical layer is not changed, but is the same. 
     Especially, it is a noticeable tendency in recent times that, in the case of the same physical layer, the hardware of the system is not changed, but only the software in the system is changed, according to the data exchanging method in the data layer placed above the physical layer. 
     Meanwhile, in the case where the data layer backs up the line switching method, from the viewpoint of the hardware, the conventional WAN access system includes a user connection process module section  10  for processing requests of corresponding users, a central control process module section  20  for performing a general control process, and a WAN connection process module section  30  for performing a transfer, an extraction, and a conversion of data, as shown in FIG.  1 . 
     The user connection process module section  10  includes an analog/digital connection section  11 , a serial connection section  12 , and a local area network (LAN) connection section  13 . The analog/digital connection section  11  performs an analog connection with a telephone or a facsimile telegraph and a digital connection with a private switching system, that is, a private branch exchange (PBX). The serial connection section  12  processes a V.35 or recommended standard (RS)-449 interface, and the LAN connection section  13  performs a LAN connection. 
     The central control process module section  20  includes a time division multiplexing (TDM) switching section  21 , a voice processing section  22 , and a processor module section  23 . The TDM switching section  21  performs a switching between TDM buses, and the voice processing section  22  performs compression/restoration of voice data transmitted/received through the analog/digital connection section  11 . The processor module section  23  backs up a part of an asynchronous transfer mode (ATM) layer and controls all sections in respective module sections. In this case, the TDM bus means signals including a frame synchronous signal, a data clock signal, a transmission data signal, and a reception data signal. 
     The WAN connection process module section  30  includes a physical medium connection section  31  and a frame conversion section  32 . The physical medium connection section  31  performs a physical medium connection with WAN, and the frame conversion section  32  converts a frame available in the physical layer into an electric signal or converts an electric signal received through the physical medium connection section  31  into frame data. 
     Hereinafter, described will be an operation of the conventional WAN access system having the construction as described above, in which the physical layer has a connection speed of T 1 /E 1  level, and the line switching method used in, e.g., a public telephone network is utilized. 
     First, information or data processed by the analog/digital connection section  11  of the user connection process module section  10  are transferred through a first TDM bus, the TDM switching section  21  of the central control process module section  20 , and a fourth TDM bus, to the frame conversion section  32  of the WAN connection process module section  30 . Otherwise, the data are transferred to the voice processing section  22  through a third TDM bus by the TDM switching section  21  and then is voice-compressed, and thereafter are transferred through the fourth TDM bus to the frame conversion section  32  of the WAN connection process module section  30  and then are transmitted to the WAN through the physical medium connection section  31 . 
     Data received through the serial connection section  12  and the LAN connection section  13  of the user connection process module section  10  are transferred respectively through a serial bus and a LAN interface to the processor module section  23  of the central control process module section  20 . Then, data to be transmitted to the WAN are transferred through a second TDM bus, the TDM switching section  21 , and the fourth TDM bus to the frame conversion section  32  of the WAN connection process module section  30 , and then transmitted through the physical medium connection section  31  to the WAN. 
     On the contrary, data received through the frame conversion section  32  of the WAN connection process module section  30  are transferred to a corresponding user through a reverse process to the above process, in the WAN access system. 
     Meanwhile, in the case where the data layer uses a packet switching method, the hardware of the conventional WAN access system includes the processor module section  23  and a physical layer convergence protocol (PLCP) processing section  33 , further to the hardware shown in FIG. 1, as shown in FIG.  2 . In the following description, the same construction as in the hardware of FIG. 1 will be numbered the same and a description about the same construction will be omitted. 
     A segmentation and reassembly (SAR) processing section  24  is contained in the central control process module section  20  and performs a cell disassembling/assembling function of an ATM adaptation layer  1  (AAL 1 ) and an AAL 5 . The PLCP processing section  33  is contained in the WAN connection process module section  30 . The PLCP processing section  33  transforms data received through a universal-test-and-operation-physical-interface-for-ATM (UTOPIA) bus into a frame available in the physical layer and transfers it to the frame conversion section  32 . Further, the PLCP processing section  33  extracts data to be transferred through the UTOPIA bus to the SAR processing section  24  of the central control process module section  20  from the frame in the physical layer received through the frame conversion section  32 . In this case, the UTOPIA bus means signals including transmission/reception signals set as criteria for exchanging transmission/reception data between the physical layer and the data layer. 
     Hereinafter, described will be an operation of the conventional WAN access system having the construction as described above, in which the physical layer has a connection speed of T 1 /E 1  level, and the packet switching method such as the ATM is utilized. 
     Data processed by the analog/digital connection section  11  of the user connection process module section  10  are transferred through the first TDM bus, the TDM switching section  21  of the central control process module section  20 , and the second TDM bus, to the processor module section  23 . Thereafter, the data are transformed into the mode of the AAL 1  by the SAR processing section  24  and then transferred to the PLCP processing section  33  of the WAN connection process module section  30  by the UTOPIA bus, or the data are transferred through the third TDM to the voice processing section  22  by the TDM switching section  21  and voice-compressed, and then transferred through a host processor (HP) interface to the SAR processing section  24  and transformed into the mode of AAL 5 . Thereafter, the data are transferred through the UTOPIA bus to the PLCP processing section  33  of the WAN connection process module section  30 . In this case, the HP interface means signals including the address/data bus for the data exchange between a processor of the processor module section  23  and an auxiliary processor of the voice processing section  22 , and related control signals. 
     In the meantime, data received through the serial connection section  12  and the LAN connection section  13  of the user connection process module section  10  are transferred respectively through the serial bus and the LAN interface to the processor module section  23  of the central control process module section  20 . Thereafter, data to be transmitted to the WAN are transformed into the mode of AAL 5  by the SAR processing section  24  and then transferred through the UTOPIA bus to the PLCP processing section  33  of the WAN connection process module section  30 . Then, the PLCP processing section  33  transforms the data received through the UTOPIA bus into a T 1 /E 1  frame of the physical layer, and then transfers the data to the frame conversion section  32  through the fourth TDM bus, which is a local TDM bus, so that the data are transmitted through the physical medium connection section  31  to the WAN. 
     In the conventional WAN access system as described above, since a specific physical layer backs up a specific data layer, the conventional WAN access system has a deteriorated hardware flexibility. Further, there is a disadvantage in that the conventional WAN access system has to simultaneously change the hardware construction and the software or employ a new access system, according to a change of the WAN protocol used in the data layer. 
     SUMMARY OF THE INVENTION 
     Accordingly, the present invention has been made in an effort to solve the problems occurring in the related art, and it is an object of the present invention to provide a WAN access system capable of performing a line switching and a packet switching, in which data can be processed by modifying only the software without modifying the hardware construction, even when a data exchanging method, which is a WAN protocol used in a data layer above a physical layer, is changed, in the case where the connection speed of the physical layer is the T 1 /E 1  level. 
     It is another object of the present invention to provide a WAN access system capable of performing a line switching and a packet switching, in which TDM buses, UTOPIA buses, and a processor bus capable of interfacing with the processor module section, are defined as internal interfaces of a WAN connection process module section, so that, even when the connection speed of a physical layer exceeds the T 1 /E 1  level and a data layer is changed into a packet switching mode such as an ATM, the change can be easily coped with by modifying the WAN connection process module section. 
     In accordance with one aspect of the present invention, there is provided a WAN access system capable of performing a line switching and a packet switching, the WAN access system comprising: a user connection process module section for processing a corresponding request of users; a WAN connection process module section for performing transfer, extraction, and transformation of data; and a central control process module section for controlling the WAN access system, wherein the central control process module section comprises: a TDM switching section for performing switching between the TDM buses so as to enable the line switching and the packet switching; a voice processing section for performing compression/restoration for voice data transmitted/received; a processor module section for performing an AAL 5  SAR processing and an SAAL processing and controlling a switching path for the TDM switching section; and an AAL 1 -processing/UTOPIA-multiplexing section for performing an AAL 1  SAR processing and a UTOPIA bus multiplexing processing, and the WAN connection process module section comprises: a physical medium connection section for performing a physical medium connection; a frame conversion section for converting a frame available in a physical layer into an electric signal and converting an electric signal received through the physical medium connection section into frame data; a TDM selection section for selecting and processing a predetermined TDM bus according to a control of the processor module section; and a PLCP processing section for transforming data received through a second UTOPIA bus into a frame available in the physical layer and transferring the frame to the frame conversion section through the TDM selection section, the PLCP processing section extracting data to be transferred through the second UTOPIA bus to the AAL 1 -processing/UTOPIA-multiplexing section from the frame in the physical layer received through the frame conversion section. 
     In this case, a line switching TDM bus for transmission/reception of data is connected between the TDM switching section and the TDM selection section. 
     Further, when the data layer employs the packet switching method, the processor module section transforms data, which have been transferred to the voice processing section by the TDM switching section and voice-compressed, into AAL 5  cells, and transforms data to be transmitted to a WAN, from among data transferred through a serial bus and a LAN interface from the user connection process module section, into AAL 5  cells, and then transfers the AAL 5  cells through a first UTOPIA bus to the AAL 1 -processing/UTOPIA-multiplexing section. 
     In addition, the AAL 1 -processing/UTOPIA-multiplexing section multiplexes the AAL 5  cells, which have been received through the first UTOPIA bus, and the AAL 1  cells, which have been transformed from the data transferred from the TDM switching section, and transfers the multiplexed cells through the second UTOPIA bus to the WAN connection process module section. The AAL 1 -processing/UTOPIA-multiplexing section performs a recombination of AAL 1  cells, which have been extracted from the data transferred through the second UTOPIA bus from the WAN connection process module section, and then transfers the recombined cells through a TDM bus to the TDM switching section, and the AAL 1 -processing/UTOPIA-multiplexing section transfers the AAL 5  cells through the first UTOPIA bus to the processor module section. 
     In accordance with another aspect of the present invention, there is provided a WAN access system capable of performing a line switching and a packet switching, the WAN access system comprising: a user connection process module section for processing a corresponding request of users; a WAN connection process module section for performing transfer, extraction, and transformation of data; and a central control process module section for controlling the WAN access system, wherein the central control process module section comprises: a TDM switching section for performing switching between the TDM buses so as to enable the line switching and the packet switching; a voice processing section for performing compression/restoration for voice data transmitted/received; and a processor module section for performing an AAL 5  SAR processing and an SAAL processing and controlling a switching path for the TDM switching section, and the WAN connection process module section comprises: a physical medium connection section for performing a physical medium connection; a frame conversion section for converting a frame available in a physical layer into an electric signal and converting an electric signal received through the physical medium connection section into frame data; a TDM selection section for selecting and processing a predetermined TDM bus according to a control of the processor module section; an AAL 1 -processing/UTOPIA-multiplexing section for performing an AAL 1  SAR processing and a UTOPIA bus multiplexing processing; and a PLCP processing section for transforming data received through a second UTOPIA bus into a frame available in the physical layer and transferring the frame to the frame conversion section through the TDM selection section, the PLCP processing section extracting data to be transferred through the second UTOPIA bus to the AAL 1 -processing/UTOPIA-multiplexing section from the frame in the physical layer received through the frame conversion section. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above objects, and other features and advantages of the present invention will become more apparent after a reading of the following detailed description when taken in conjunction with the drawings, in which: 
     FIG. 1 is a schematic block diagram of a conventional WAN access system, in which a data layer backs up a line switching method; 
     FIG. 2 is a schematic block diagram of another conventional WAN access system, in which a data layer backs up a packet switching method; 
     FIG. 3 is a schematic block diagram of a WAN access system capable of performing a line switching and a packet switching according to an embodiment of the present invention; 
     and 
     FIG. 4 is a schematic block diagram of a WAN access system capable of performing a line switching and a packet switching according to another embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     The above and other objects, characteristics, and advantages of the present invention will become apparent from the following description along with the accompanying drawings. 
     Referring to FIG. 3, a WAN access system capable of performing a line switching and a packet switching includes a user connection process module section  40 , a central control process module section  50 , and a WAN connection process module section  60 . 
     The user connection process module section  40  includes an analog/digital connection section  41  for performing an analog connection with a telephone and a facsimile telegraph and a digital connection with a digital private switching system, a serial connection section  42  for processing V.35 or RS-449 interface, and a LAN connection section  43  for performing a LAN connection. 
     The central control process module section  50  includes a TDM switching section  51  for performing switching between TDM buses so as to enable the line switching and the packet switching, a voice processing section  52  for performing compression/restoration for voice data transmitted/received through the analog/digital connection section  41 , a processor module section  53  for backing up a part of an ATM layer, performing a control for all sections in all module sections, and performing an AAL 5  SAR processing and an SAAL processing, and an AAL 1 -processing/UTOPIA-multiplexing section  54  for performing an AAL 1  SAR processing and a UTOPIA bus multiplexing processing. 
     The WAN connection process module section  60  includes a physical medium connection section  61  for performing a physical medium connection, a frame conversion section  62  for converting a frame available in the physical layer into an electric signal and converting an electric signal received through the physical medium connection section  61  into frame data, a TDM selection section  63  for selecting and processing a predetermined TDM bus according to a control of the processor module section  53 , and a PLCP processing section  64  for transforming data received through a second UTOPIA bus into a frame available in the physical layer and transferring the frame to the frame conversion section  62  through the TDM selection section  63 . Further, the PLCP processing section  64  extracts data to be transferred through the second UTOPIA bus to the AAL 1 -processing/UTOPIA-multiplexing section  54  of the central control process module section  50  from the frame in the physical layer received through the frame conversion section  62 . 
     Hereinafter, described will be an operation of a WAN access system capable of performing a line switching and a packet switching according to the present invention as described above. 
     At first, described will be an operation of a WAN access system of the present invention employing the line switching method as in a public switched telephone network (PSTN). 
     Data processed by the analog/digital connection section  41  of the user connection process module section  40  are transferred through a first TDM bus, the TDM switching section  51  of the central control process module section  50 , and a fifth TDM bus, to the TDM selection section  63  of the WAN connection process module section  60 . Otherwise, the data are transferred through a third TDM bus to the voice processing section  52  by the TDM switching section  51  and then voice-compressed, and then transferred through a fifth TDM bus to the TDM selection section  63  of the WAN connection process module section  60 . 
     Further, data received through the serial connection section  42  and the LAN connection section  43  of the user connection process module section  40  are transferred through a serial bus and a LAN interface to the processor module section  53  of the central control process module section  50 . Thereafter, data to be transmitted to the WAN are transferred through a second TDM bus to the TDM switching section  51 , and then transferred through the fifth TDM bus to the TDM selection section  63  of the WAN connection process module section  60 . 
     In this case, the data transferred through the fifth TDM bus to the TDM selection section  63  of the WAN connection process module section  60  are not permitted to exceed a limited number of time slots, and are selected according to a control by the processor module section  53  of the central control process module section  50  and transferred through a sixth TDM bus to the frame conversion section  62 , so as to be transmitted through the physical medium connection section  61  to the WAN. On the contrary, the data received through the frame conversion section  62  of the WAN connection process module section  60  from the WAN are transferred through the sixth TDM bus, the TDM selection section  63 , and the fifth TDM bus, to the TDM switching section  51  of the central control process module section  50 . Accordingly, the data transferred to the TDM switching section  51  are transferred through a corresponding TDM bus along a path set by the processor module section  53 , as available data. 
     Next, described will be an operation of a WAN access system of the present invention employing the packet switching method as in a frame relay. 
     Data processed by the analog/digital connection section  41  of the user connection process module section  40  are transferred through the first TDM bus to the TDM switching section  51  of the central control process module section  50 , and then are transferred through the third TDM bus to the voice processing section  52  by the TDM switching section  51  and voice-compressed. Thereafter, the data are transferred through the HP interface to the processor module section  53  and then transformed into a frame relay format in an aspect of the software. Furthermore, the data received through the serial connection section  42  and the LAN connection section  43  of the user connection process module section  40  are transferred respectively through the serial bus and the LAN interface to the processor module section  53  of the central control process module section  50 , and then are transformed into a frame relay format. 
     Thereafter, data transformed into the frame relay format by the processor module section  53  are transferred through the second TDM bus to the TDM switching section  51 , and then are transferred through the fifth TDM bus to the TDM selection section  63  of the WAN connection process module section  60  by the TDM switching section  51 , so as to be transmitted to the WAN, as in the WAN access system employing the line switching method as described above. On the contrary, the data received through the frame conversion section  62  of the WAN connection process module section  60  from the WAN are transferred through the sixth TDM bus, the TDM selection section  63 , and the fifth TDM bus, to the TDM switching section  51  of the central control process module section  50 . Further, the data transferred to the TDM switching section  51  in the above way are transferred through the second TDM bus to the processor module section  53 . Then, the data in a frame relay type are analyzed by the processor module section  53  in an aspect of the software, and then are transferred respectively through the serial bus and the LAN interface to the serial connection section  42  and the LAN connection section  43  and then to the user. The other data are transferred through the third TDM bus to the voice processing section  52  and voice-restored, and then transferred through the third TDM bus, the TDM switching section  51 , and the first TDM bus, to the analog/digital connection section  41 . 
     Finally, described will be an operation of a WAN access system of the present invention employing the packet switching method such as the ATM. 
     Data processed by the analog/digital connection section  41  of the user connection process module section  40  are transferred through the first TDM bus to the TDM switching section  51  of the central control process module section  50 , and then transferred through the third TDM bus to the voice processing section  52  by the TDM switching section  51  and voice-compressed. Thereafter, the data are transformed into AAL 5  cells by the processor module section  53  and then transferred through a first UTOPIA bus to the AAL 1 -processing/UTOPIA-multiplexing section  54 , or the data are transferred through the fourth TDM bus to the AAL 1 -processing/UTOPIA-multiplexing section  54  by the TDM switching section  51  and then transformed into AAL 1  cells. Further, the data received through the serial connection section  42  and the LAN connection section  43  of the user connection process module section  40  are transferred respectively through the serial bus and the LAN interface to the processor module section  53  of the central control process module section  50 . Thereafter, the data to be transmitted to the WAN are transformed into AAL 5  cells by the processor module section  53 , and then are transferred through the first UTOPIA bus to the AAL 1 -processing/UTOPIA-multiplexing section  54 . Then, the AAL 1 -processing/UTOPIA-multiplexing section  54  multiplexes the AAL 5  cells received through the first UTOPIA bus and the AAL 1  cells transformed from the data transferred through the fourth TDM bus, and transfers the multiplexed cells through the second UTOPIA bus to the PLCP processing section  64  of the WAN connection process module section  60 . Then, the PLCP processing section  64  transforms the data received through the second UTOPIA bus into a T 1 /E 1  frame of the physical layer, and then transfers the transformed frame through a seventh TDM bus, the TDM selection section  63 , and the sixth TDM bus, to the frame conversion section  62 , so that the frame is transmitted through the physical medium connection section  61  to the WAN. On the contrary, the data received through the frame conversion section  62  of the WAN connection process module section  60  from the WAN are transferred through the sixth TDM bus, the TDM selection section  63 , and the seventh TDM bus, to the PLCP processing section  64 , and then are transferred through the second UTOPIA bus to the AAL 1 -processing/UTOPIA-multiplexing section  54  of the central control process module section  50  by the PLCP processing section  64 . Subsequently, the AAL 1 -processing/UTOPIA-multiplexing section  54  extracts AAL 1  cells, and executes a recombination of the cells and transfers the recombined cells through the fourth TDM bus to the TDM switching section  51 . The AAL 5  cells, which are the other cells, are transferred through the first UTOPIA bus to the processor module section  53  by the AAL 1 -processing/UTOPIA-multiplexing section  54 . Then, the processor module section  53  performs a cell-recombination for the AAL 5  cells. Thereafter, data to be transferred to the serial connection section  42  and the LAN connection section  43  are transferred respectively through the serial bus and the LAN interface to the user, while the other data are transferred to the voice processing section  52  and voice-restored, and then transferred through the third TDM bus, the TDM switching section  51 , and the first TDM bus, to the analog/digital connection section  41 . Further, the TDM switching section  51  transfers the data, which have been transferred through the third TDM bus and the fifth TDM bus, to the analog/digital connection section  41  through the first TDM bus, which is a path defined by the processor module section  53 . 
     Meanwhile, FIG. 4 shows another WAN access system capable of performing a line switching and a packet switching according to another embodiment of the present invention, which has a construction nearly the same as that of the system shown in FIG. 3, excepting that an AAL 1 -processing/UTOPIA-multiplexing section  65  is contained in the WAN connection process module section  60  in the present embodiment, instead of the AAL 1 -processing/UTOPIA-multiplexing section  54  contained in the central control process module section  50  of the system shown in FIG.  3 . 
     In the present embodiment, the hardware construction for the central control process module section  50  and the WAN connection process module section  60  of the WAN access system has to be modified in the case where the connection speed of the physical layer exceeds the T 1 /E 1  level and the packet switching method such as the ATM is used, while it is sufficient to modify only the software without modifying the hardware construction in the case where the connection speed of the physical layer is the T 1 /E 1  level. 
     In the WAN access system capable of performing a line switching and a packet switching according to the present invention as described above, in the case where the connection speed of the physical layer is the T 1 /E 1  level, data can be processed by modifying only the software without modifying the hardware construction, even when a data exchanging method, which is a WAN protocol used in the data layer above the physical layer, is changed. 
     Further, in the WAN access system of the present invention, TDM buses, UTOPIA buses, and a processor bus capable of interfacing with the processor module section, are defined as the internal interfaces of the WAN connection process module section. Therefore, even when the connection speed of the physical layer exceeds the T 1 /E 1  level and the data layer is changed into a packet switching mode such as an ATM, the change can be easily coped with by modifying the WAN connection process module section. 
     While there have been illustrated and described what are considered to be preferred specific embodiments of the present invention, it will be understood by those skilled in the art that the present invention is not limited to the specific embodiments thereof, and various changes and modifications and equivalents may be substituted for elements thereof without departing from the true scope of the present invention.