Telecommunications – Radiotelephone system – Zoned or cellular telephone system
Reexamination Certificate
1999-01-21
2003-12-16
Maung, Nay (Department: 2684)
Telecommunications
Radiotelephone system
Zoned or cellular telephone system
C455S432300, C455S556200
Reexamination Certificate
active
06665537
ABSTRACT:
BACKGROUND OF THE INVENTION
I. Field of the Invention
This invention generally relates to the field of wireless communications. More particularly, the present invention relates to a novel and improved method and system for automatically invoking a mobile terminal device to initiate IP mobility support in a wireless communications network.
II. Description of Related Art
Recent innovations in wireless communication and computer-related technologies, as well as the unprecedented growth of Internet subscribers, have paved the way for mobile computing. In fact, the popularity of mobile computing has placed greater demands on the current Internet infrastructure to provide mobile users with more support. The life blood of this infrastructure is the packet-oriented Internet Protocol (IP) which provides various services, including the addressing and routing of packets (datagrams) between local area networks (LANs). IP protocol is defined in Request For Comment 791 (RFC 791) entitled, “INTERNET PROTOCOL DARPA INTERNET PROGRAM PROTOCOL SPECIFICATION,” dated September 1981, and herein incorporated by reference.
Heuristically, according to the IP protocol, data is encapsulated into IP packets for transmission. Addressing and routing information is affixed 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. These prefixes 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 packets 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.
Ideally, mobile computing should provide users with seamless and transparent Internet access regardless of time and its current point-of-attachment. The access should be seamless in the sense that, as the mobile user roams or migrates between networks, there is continuous Internet connectivity with no inconvenience or noticeable difference to the mobile user. The access should be transparent to the user such that applications do not need to be recompiled, reconfigured, or re-executed as the mobile user roams across various networks. Conventional internetworking protocols (e.g., TCP/IP, IPX, Appletalk™, etc.) are, at best, awkward in handling mobile users who migrate between networks. This is because, as stated above, the IP addressing scheme used for Internet routing inherently contains geographic information. If a mobile user desires to use a fixed IP address to identify his mobile terminal, the IP packets intended for the user will not be routed to the mobile terminal when the terminal happens to be away from the network corresponding to the fixed IP address (i.e., its “home” network). If the terminal attempts to rectify this by changing its address, it will lose all connectivity.
By way of example, suppose a user decides to remove his mobile terminal from its “home” network at QUALCOMM, Inc. in San Diego, and connect to Stanford University's network in Palo Alto, Calif. while maintaining his QUALCOMM-assigned fixed IP address. Conventionally, any IP packet intended for the mobile terminal will still be routed to QUALCOMM's network in San Diego 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 or route IP packets from QUALCOMM's network to the mobile terminal's current point-of-attachment at Stanford University's network in Palo Alto.
In order to meet the need for seamless and transparent Internet access, Request For Comment 2002 (RFC 2002), entitled “IP MOBILITY SUPPORT,” dated October 1996 and herein incorporated by reference, specifies protocol techniques to achieve the transparent forwarding of IP packets to mobile terminals regardless of their particular point-of-attachment. Using these Mobile IP techniques, each mobile terminal is always identified by its “home” network IP address, regardless of its current point-of-attachment to the Internet. When the mobile terminal is located within its home IP network, it operates without the use of Mobile IP techniques. However, upon the mobile terminal detecting that it is no longer operating within its home IP network but is visiting a “foreign IP network”, it obtains a foreign network “care-of” address which provides forwarding information necessary to route IP packets to its current point-of-attachment. This care-of-address may be proffered by an agent on the foreign network, “Foreign Agent” (e.g., a router in the foreign network) through its Agent Advertisement message. Mobile IP techniques require that the mobile terminal send a Registration-Request message to a “Mobility Agent” in order to register a desired care-of-address. This Mobility Agent may either be a “Home Agent” (i.e., a router in the terminal's home network) or the “Foreign Agent” and is responsible for returning a Registration-Reply granting or denying the Registration-Request. If granted, the Home Agent forwards the IP packets 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, the 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, Mobile IP supports mobile terminals that roam across different foreign networks and vary their network point-of-attachment, without having to change the mobile terminal's IP address. This capability has several advantages. First, it allows other nodes elsewhere on the Internet to send periodic “push” services (e.g., stock quotes, e-mail, etc.) to the mobile terminal regardless of the mobile terminal's location. This obviates the need for the mobile user to actively retrieve information from his home network. Second, Mobile IP allows the mobile terminal to relocate to different sub-networks, as often as desired, without any originating parties having to keep track of what sub-network the mobile terminal is currently attached to. Third, by design, Mobile IP is compatible with a variety of networks and media, ensuring seamless and transparent Internet access. For example, Mobile IP is capable of supporting packet traffic generated by a mobile terminal as it travels from its home Ethernet network segment to a foreign wireless LAN, without any significant interruption in service.
As stated above, the current trend is for mobile users to use mobile computers, such as laptop or palmtop computers, in conjunction with wireless communication devices, such as cellular or portable phones, to access the Internet. To wit, just as users conventionally employ “wired” communication devices to connect their computers to land-based networks, mobile users will use wireless communication devices, commonly referred to as “mobile stations” (MSs), to connect their mobile terminals to such networks. As used herein, mobile station or MS will refer to any subscriber station in the public wireless radio network that is intended to be used while in transit or during halts at unspecified points. MS devices include portable units (e
Brown Charles D.
Cheatham Kevin T.
Gesesse Tilahun
Maung Nay
Qualcomm Incorporated
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