Telecommunications – Radiotelephone system – Zoned or cellular telephone system
Reexamination Certificate
1998-08-07
2001-05-08
Maung, Nay (Department: 2681)
Telecommunications
Radiotelephone system
Zoned or cellular telephone system
C455S556200, C455S557000
Reexamination Certificate
active
06230012
ABSTRACT:
BACKGROUND OF THE INVENTION
I. Field of the Invention
The present invention relates to wireless data services. More particularly, the present invention relates to a novel and improved method and system for performing proxy mobile node registration of a terminal device requesting IP mobility support.
II. Description of the Related Art
Internetworking, i.e., the connection of individual local area networks (LANs), has rapidly become very popular. The infrastructure and associated protocols commonly referred to as the “Internet” have become well known and widely used. At the heart of the Internet is the Internet Protocol (IP) which supports the routing of datagrams between the LANs as is well known in the art, and further described in Request For Comment (RFC) 791 entitled, “INTERNET PROTOCOL DARPA INTERNET PROGRAM PROTOCOL SPECIFICATION,” dated September 1981.
IP is a datagram-oriented protocol which provides several services, including addressing. The IP protocol encapsulates data into an IP packet for transmission, and affixes addressing information to the header of the packet. IP headers contain 32-bit addresses that identify the sending and receiving hosts. These addresses are used by intermediate routers to select a path through the network for the packet towards its ultimate destination at the intended address. A basic concept of IP addressing is that initial prefixes of the IP address can be used for generalized routing decisions. For example, the first 16 bits of an address might identify Qualcomm, Inc., the first 20 bits identify the Qualcomm's main office, the first 26 bits identify a particular Ethernet in that office, and the entire 32 bits identify a particular host on that Ethernet. As a further example, every address in Qualcomm's IP network might be of the form (in “dotted-quad notation”): 129.46.xxx.xxx, where “xxx” refers to any allowable integer between zero and 255.
As is evident by this prefix-based routing characteristic of IP, the IP addresses contain implied geographical information about the location of a particular host on the Internet. In other words, whenever any router on the Internet receives a packet having a destination IP address that begins “129.46” the router forwards that packet in a particular direction towards the Qualcomm, Inc. network in San Diego, Calif., USA. Thus, the IP protocol allows datagrams originating at any Internet node in the world to be routed to any other Internet node in the world, given that the originating party knows the IP address of the destination party.
As mobile computing and mobile Internet access have grown in popularity, a need has arisen to provide mobile data support for mobile terminals such as laptop or palmtop computers using the IP protocol. However, as just mentioned, the IP addressing scheme used for Internet routing contains implied geographic information. In other words, if a user desires to use a fixed IP address to identify his mobile terminal, the IP packets intended for that mobile terminal will not be routed to that mobile terminal when it is away from its “home” network (i.e., the network which encompasses its fixed IP address) in the absence of some technique for “forwarding” IP packets to the mobile terminal.
For example, suppose a user decides to remove his mobile terminal from its “home” IP network at Qualcomm, Inc. in San Diego, and take it with him on a trip to Palo Alto, Calif., and there connect to Stanford University's IP network while still keeping his Qualcomm-assigned fixed IP address. Any IP datagram intended for the mobile terminal will still be routed to Qualcomm's IP network because of the geographical location information implicit in the mobile terminal's fixed IP address. Such IP packets will not be delivered to the mobile terminal while away from its “home” network unless some mechanism is in place to forward IP packets from Qualcomm's IP network to the mobile terminal at its current point of attachment to the Internet at Stanford University's IP network in Palo Alto.
In order to meet this need, RFC 2002, entitled “IP Mobility Support,” dated October 1996, specifies protocol enhancements that allow transparent routing of IP datagrams to mobile nodes in the Internet. Using the techniques described in RFC 2002, each mobile node may always be identified by its “home” IP address, regardless of its current point of attachment to the Internet. While situated away from its home IP network, a mobile terminal may become associated with a “care-of” address, thereby providing forwarding information necessary to route IP datagrams to its current point of attachment to the internet. RFC 2002 accomplishes this by providing for registration of the care-of address with a “home agent.” This home agent forwards IP datagrams intended for the mobile terminal by using a technique called “IP tunneling.” IP tunneling involves the home agent attaching a new IP header which contains the care-of address to any arriving IP packet which has a destination address corresponding to the mobile terminal's home IP address. After arriving at the care-of address, a “foreign agent” at the care-of address strips off the IP tunneling header, and delivers the IP packet to the mobile terminal at its current point of attachment to the internet.
In this way, the techniques of RFC 2002 provide mobile data services for users who desire to relocate their mobile terminal's point of attachment to the internet without having to change the mobile terminal's IP address. This ability has several advantages. First, it allows originating nodes elsewhere on the Internet to send periodic “push” services to the mobile terminal regardless of where it is. Such services might include stock quotes or e-mail. This obviates the need for the mobile user to “dial in” or otherwise contact his home network in order to retrieve information. Furthermore, it allows the mobile terminal to relocate as often as desired, without any originating parties having to keep track of where the mobile terminal is currently located.
To increase the freedom of mobility of the mobile terminal, many mobile users will typically use wireless communication devices, such as cellular or portable phones, to connect to the Internet. In other words, many mobile users will use wireless communication devices, commonly referred to as “mobile stations,” or MT2 devices, as the point of access to the land-based network. As used herein, “mobile station” or “MT2 device” will refer to any subscriber station in the public wireless radio network that is intended to be used while in motion or during halts at unspecified points. Mobile stations and MT2 devices include portable units (e.g., hand-held personal phones) and units installed in vehicles, as well as wireless local loop (WLL) telephones.
FIG. 1
illustrates a high-level block diagram of a wireless data communication system in which a mobile terminal (TE2 device)
102
communicates with an Interworking Function (IWF)
108
via a wireless communication system which includes wireless communication device (MT2 device)
104
and Base Station/Mobile Switching Center (BS/MSC)
106
. In
FIG. 1
, the IWF
108
serves as the access point to the Internet. IWF
108
is coupled to, and often co-located with BS/MSC
106
, which may be a conventional wireless base station as is known in the art. TE2 device
102
is coupled to MT2 device
104
, which is in turn in wireless communication with BS/MSC
106
and IWF
108
.
Many protocols exist which allow data communication between the TE2 device
102
and the IWF
108
. For example, Telecommunications Industry Association (TIA)/Electronics Industries Association (EIA) Interim Standard IS-707.5, entitled “Data Service Options for Wideband Spread Spectrum Systems: Packet Data Services,” published February 1998, defines requirements for support of packet data transmission capability on TIA/EIA IS-95 wideband spread spectrum systems, of which BS/MSC
106
and IWF
108
may be a part. IS-707.5 specifies a packet data bearer service that may be used
Armstrong Susan M.
Lioy Marcello
Willkie James J.
Brown Charled D.
Edwards Christopher O.
Maung Nay
Qualcomm Incorporated
Vuong Quochien B.
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