Abstract:
A network emulation device and method in a terminal of an IEEE 802.16 communication system supporting IPv6 communications based on a Neighbor Discovery (ND) protocol are provided. The terminal includes an IPv6 module for performing an ND mechanism to search for a neighbor terminal or a router, a MAC module for communicating based on the IEE 802.16 standard, and a network emulation module provided between the IPv6 module and the MAC module for analyzing a ND message received from the IPv6 module and discarding the ND message or generating a response message for the ND message according to the message type. The network emulation module converts a broadcast ND message to a unicast message and provides the unicast message to a corresponding network device if network information needed to internally generate the response message is not collected.

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS 
       [0001]    This application claims the benefit under 35 U.S.C. §119(a) of a Korean Patent Application filed in the Korean Intellectual Property Office on Jan. 4, 2006 and assigned Serial No. 2006-00944, the entire disclosure of which is hereby incorporated by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates generally to a wireless communication system. More particularly, the present invention relates to an emulation device and method for supporting Internet Protocol version 6 (IPv6) over an Institute of Electrical and Electronics Engineers (IEEE) 802.16/Wireless Broadband (WiBro) communication network. 
         [0004]    2. Description of the Related Art 
         [0005]    A broadband wireless communication network technology known as World Interoperability for Microwave Access (WiMax) has recently been adopted as the IEEE 802.16 standard by the IEEE, and a version of WiMax for mobile access, WiBro has been also adopted as IEEE 802.16e. Hence, commercial deployment of portable Internet communication services based on these standards has accelerated. 
         [0006]    However, since the IEEE 802.16/802.16e standards are different from the existing radio access technologies including IEEE 802.11x or 3G, IPv4 or IPv6 cannot be directly applied to an IEEE 802.11 network. 
         [0007]    For IPv6, a Neighbor Discovery (ND) protocol providing broadcast or multicast message exchanges in the processes of address resolution, router discovery, duplicate address detection, and auto configuration, which are performed by broadcast or multicast, is a requisite to a terminal. However, the IEEE 802.16 network is a point-to-multipoint network and the terminal cannot broadcast or multicast. Therefore, the ND protocol of IPv6 cannot work well. 
         [0008]    Accordingly, there is a need for an improved emulation device and method that supports Internet Protocol version 6 (IPv6). 
       SUMMARY OF THE INVENTION 
       [0009]    An aspect of exemplary embodiments of the present invention is to address at least the above problems and/or disadvantages and to provide at least the advantages described below. Accordingly, an aspect of exemplary embodiments of the present invention is to provide an emulation device and terminal for implementing a Neighbor Discovery (ND) protocol of IPv6, while avoiding collision between an IPv6 layer and an IEEE 802.16 Medium Access Control (MAC) layer. 
         [0010]    Certain exemplary embodiments of the present invention provide an emulation device and method for preventing collision between the ND mechanism of IPv6 and an IEEE 802.16 MAC layer which does not support broadcasting/multicasting of a terminal by adding a network emulation layer between an IPv6 layer and a MAC layer in the terminal and feeding back the IP address of a router collected by a MAC management message to the IP layer. 
         [0011]    Certain exemplary embodiments of the present invention provide an emulation device and method for reducing resource consumption by a broadcasting message in the ND mechanism of IPv6 by generating the IPv6 address of the terminal based on router information included in a MAC management message received from a Base Station (BS). 
         [0012]    According to one aspect of exemplary embodiments of the present invention, a terminal, in an IEEE 802.16 communication system supporting IPv6 communications based on a neighbor discovery protocol, includes an IPv6 module for generating a multicast ND message to search for a neighbor terminal or a router, and a MAC module for exchanging MAC management messages with a base station for IPv6 communications, a network emulation device is provided between the IPv6 module and the MAC module. The network emulation device collects network information from a MAC management message received from the base station, generates a response message for the multicast ND message based on the network information, and provides the response message to the IPv6 module, or discards the ND message, or converts the ND message to a unicast message. 
         [0013]    According to another aspect of exemplary embodiments of the present invention, in a network emulation method in a terminal in an IEEE 802.16 communication system supporting IPv6 communications based on a neighbor discovery protocol, the terminal comprises an IPv6 module for generating a multicast ND message to search for a neighbor terminal or a router, a MAC module exchanges MAC management messages with a base station for IPv6 communications, a network emulation layer between the IPv6 module and the MAC module, for supporting the neighbor discovery protocol, collects network information from a MAC management message received, and the neighbor discovery protocol is emulated based on the network information. 
         [0014]    Other objects, advantages, and salient features of the invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses exemplary embodiments of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]    The above and other objects, features and advantages of certain exemplary embodiments of the present invention will be more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which: 
           [0016]      FIG. 1A  illustrates the configuration of an IEEE 802.16 network to which an IPv6 network emulation device and method according to an exemplary embodiment of the present invention are applied; 
           [0017]      FIG. 1B  is a block diagram of an IPv6 layer and a network emulation layer illustrated in  FIG. 1A , for describing interaction between the layers; 
           [0018]      FIG. 2  illustrates the format of an IPv6 packet; 
           [0019]      FIG. 3  illustrates the configuration of an IEEE 801.6 terminal according to an exemplary embodiment of the present invention; 
           [0020]      FIG. 4  illustrates the configuration of a network emulation module illustrated in  FIG. 3 ; 
           [0021]      FIG. 5  is a flowchart illustrating an operation of the IPv6 network emulation module in the IEEE 802.16 system according to an exemplary embodiment of the present invention; and 
           [0022]      FIG. 6  is a detailed flowchart illustrating a network emulation operation described in  FIG. 5 . 
       
    
    
       [0023]    Throughout the drawings, the same drawing reference numerals will be understood to refer to the same elements, features, and structures. 
       DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       [0024]    The matters defined in the description such as a detailed construction and elements are provided to assist in a comprehensive understanding of the embodiments of the invention. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the embodiments described herein can be made without departing from the scope and spirit of the invention. Also, descriptions of well-known functions and constructions are omitted for clarity and conciseness. 
         [0025]      FIG. 1A  illustrates a configuration of an IEEE 802.16 network to which an IPv6 network emulation device and method according to an exemplary embodiment of the present invention are applied. 
         [0026]    Referring to  FIG. 1A , a wireless terminal  11  is connected to a base station (BS)  13  by a radio link  12  and the BS  13  is connected to a router  15  within an IPv6 network by a wired link  14 . The BS  13  converts an Ethernet frame received from a destination terminal (not shown) via the router  15  to an IEEE 802.16 frame and provides the IEEE 802.16 frame to the terminal  11 . The BS  13  also converts an IEEE 802.16 frame received from the terminal  11  to an Ethernet frame and provides the Ethernet frame to the destination terminal via the router  15 . 
         [0027]    The router  15  includes a protocol stack with an Ethernet layer  101 , IP layer  102 , UDP/TCP layer  103 , and an application layer  104 . The terminal  11  operates based on a protocol stack with an IEEE 802.16 MAC layer  110 , network emulation layer  120 , the IP layer  102 , UDP/TCP layer  103 , and application layer  104 . The BS  13  has a protocol stack of the IEEE 802.16 MAC layer  110  and the Ethernet layer  101 . 
         [0028]    While IEEE 802.16 and Ethernet are defined in the MAC layer of the BS  13 , to which the present invention is not limited, the BS  13  supports conversion between headers of most MAC layer protocols. 
         [0029]    The terminal  11  and the BS  13  exchange MAC Protocol Data Units (PDUs) in the MAC layers. A MAC PDU includes a fixed-length MAC header, variable-length payload, and an optional Cyclic Redundancy Check (CRC). The MAC PDU may have a generic header or a bandwidth request header depending on the value of a Header Type (HT) field. A MAC PDU contains a MAC management message or higher-layer data, if it is not a bandwidth request MAC PDU without payload. 
         [0030]    The ND protocol is defined in the IPv6 layer, which addresses address resolution, router discovery, and neighbor unreachability detection. The ND protocol detects the existence of neighbor terminals, exchanges a Neighbor Solicitation (NS) message and a Neighbor Advertisement (NA) message to determine the link layer addresses of the neighbors, and detects routers and maintains the reliability of a route by use of a Router Solicitation (RS) message and a Router advertisement (RA) message. 
         [0031]      FIG. 1B  is a block diagram of the IPv6 layer  102  and the network emulation layer  120  illustrated in  FIG. 1A , for describing interaction between the layers. 
         [0032]    Referring to  FIG. 1B , for IP communications from the terminal  11 , the IPv6 layer  102  sends an NS, NA or RS message, and the network emulation layer  120  analyzes an IPv6 packet received from the IPv6 layer  102  to decide whether the IPv6 packet includes the NS, NA or RS message. In the presence of the NS, NA or RS message in the IPv6 packet, the network emulation layer  120  provides an NA or RA message as a response for the NS, NA or RS message to the IPv6 layer  102 , rather than send the NA or RA through the MAC layer  110 . The response message is generated based on the IP information of a router collected by a MAC management message such as Request-Response (REG-RSP) received from the BS during registration for IP communications. 
         [0033]      FIG. 2  illustrates the format of an IPv6 packet. Referring to  FIG. 2 , the network emulation layer  120  of the terminal  11  determines that transmission data in payload is an Internet Control Message Protocol for IPv6 (ICMPv6) data if a next header field  21  in an IPv6 header is  58 , and analyzes an ICMPv6 header of the ICMPv6 payload. If a type field of the ICMPv6 header is  133  (Router Solicitation),  135  (Neighbor Solicitation) or  136  (Neighbor Advertisement), the network emulation layer  120  generates an NA or RA message, considering that the packet contains an RS, NS or NA message. 
         [0034]    For generation of the response message, the network emulation layer  120  extracts and stores the network information of the terminal  11  from a MAC management message received from the BS  13 . Since the BS  13  is connected to the router  15  by an Ethernet link, the BS  13  can obtain the network information of the router  15  by exchanging MAC messages with the router  15 . 
         [0035]    To obtain the network information from the BS  13 , the terminal  11  exchanges MAC management messages such as (REG-REQ) and REG-RSP with the BS  13 . The network emulation layer  120  extracts the network information from the received MAC management message and stores/updates the network information. 
         [0036]      FIG. 3  illustrates the configuration of an IEEE 801.6 terminal according to an exemplary embodiment of the present invention. 
         [0037]    Referring to  FIG. 3 , the terminal includes an IPv6 module  303 , MAC module  307 , and network emulation module  305 . The IPv6 module  303  outputs higher-layer data in the form of an IP packet and searches for a neighbor terminal or a router by the ND protocol. The MAC module  307  outputs the IP packet in the form of a MAC PDU and transmits a MAC management message for IPv6 communications. The network emulation module  305  collects network information from a response message received for a registration request message, generates a response message for a ND message created by the ND protocol when necessary, and provides the response message to the IPv6 module  303 . The network emulation module  305  also converts a multicast ND message to a unicast message for transmission, and deletes the ND message when necessary. 
         [0038]      FIG. 4  illustrates the configuration of the network emulation module illustrated in  FIG. 3 . Referring to  FIG. 4 , the network emulation module  305  includes an analysis module  41  for determining whether the collected network information contains information needed to generate a response message for the multicast ND message, a response message generation module  43  for, in the presence of the information for generation of the response message, generating the response message and providing the response message to the IPv6 module, and a message conversion module  45  for, in the absence of the information needed to generate the response message, converting the ND message to the unicast ND message and providing the unicast ND message to the MAC module. The network information is stored in a storage  47  and updated/managed by the analysis module  41 . 
         [0039]      FIG. 5  is a flowchart illustrating an operation of the IPv6 network emulation module in the IEEE 802.16 system according to an exemplary embodiment of the present invention. 
         [0040]    Referring to  FIG. 5 , when the terminal enters coverage of the BS and a communication link is completely established between the terminal and the BS, the terminal exchanges MAC management messages with the BS. During the message exchange, the network emulation module collects IPv6 network information from the MAC management message received from the BS in step S 501  and emulates the ND mechanism of the IPv6 network based on the network information in step S 502 . 
         [0041]      FIG. 6  is a detailed flowchart illustrating the network emulation operation described in  FIG. 5 . 
         [0042]    Referring to  FIG. 6 , the network emulation module passes messages other than messages generated by the ND protocol of the IPv6 layer to the MAC layer. Upon receipt of a ND message from the IPv6 module in step S 601 , the network emulation module determines whether the ND message is an NS message in step S 602 . In the case of an NS message, the network emulation module determines whether the NS message has been created for address resolution in step S 603 . If the NS message has been created for address resolution, the network emulation network determines whether the NS message contains information needed for generation of a response message in step S 604 . In the presence of the information, the network emulation module generates an NA message and feeds the NA message back to the IPv6 module in step S 605 . In the absence of the information, the network emulation module converts the NS message to a unicast NS message and provides the unicast NS message to the MAC module in step S 606 . 
         [0043]    On the other hand, if the NS message has not been generated for address resolution, the network emulation module deletes the NS message, considering that the NS message has been generated for duplicate address detection in step S 607 . 
         [0044]    If the ND message is not the NS message in step S 602 , the network emulation module determines whether the ND message is an RS message generated for router discovery in step S 611 . If the ND message is not the RS message, the network emulation module passes the ND message to the MAC module. In the case of the RS message, the network emulation module determines whether the RS message contains information needed for generation of a response message in step S 608 . In the presence of the information, the network emulation module generates an RA message and feeds the RA message back to the IPv6 module in step S 609 . In the absence of the information, the network emulation module converts the RS message to a unicast RS message and provides the unicast RS message to the MAC module in step S 610 . 
         [0045]    As described above, in the IPv6 network emulation method in the IEEE 802.16 system according to exemplary embodiments of the present invention, a terminal creates an internal response message for a broadcast/multicast ND message generated by the ND protocol, deletes the ND message, or converts the ND message to a unicast ND message, based on network information included in a MAC management message received from a BS. Therefore, resources consumption for broadcasting/multicasting is minimized. 
         [0046]    While the invention has been shown and described with reference to certain exemplary embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims and their equivalents.