Multiplex communications – Diagnostic testing – Fault detection
Reexamination Certificate
1997-10-16
2001-06-12
Pham, Chi H. (Department: 2731)
Multiplex communications
Diagnostic testing
Fault detection
C370S338000, C370S401000
Reexamination Certificate
active
06246670
ABSTRACT:
The present invention relates generally to the communication of packet data with a wireless host identified with a temporary address during a communication session between the wireless host and another host device. More particularly, the present invention relates to a method and apparatus for preventing misrouting of data subsequent to an abnormal termination of the communication session by the wireless host.
When the communication session is terminated by the wireless host abnormally, the other host device is unaware of the termination and continues sending packet data. Operation of an embodiment of the present invention selectively withholds reassignment of the temporary address, used to identify the terminating wireless host, thereby to prevent reassignment of the temporary address to identify another wireless host. Misrouting of data from the other host device to an other-than-intended wireless host is thereby avoided.
An embodiment of the present invention is operable, for instance, in an Internet application. A wireless host is coupled, in such an application, by way of a mobile communication system and an Internet backbone to an Internet host. In the event of abnormal communication session termination by the mobile host, the temporary address used to identify the wireless host is not immediately reassigned to identify another wireless host, thereby avoiding the misrouting of data to an other-than-intended wireless host.
BACKGROUND OF THE INVENTION
Many new types of communication systems have become feasible and commercially viable in recent years due to advancements in the fields of electronics and communications. The introduction and commercialization of such new types of communication systems have, in many instances, provided manners by which information can be affordably communicated to locations to which such information could previously not otherwise be communicated.
A cellular telephone system is exemplary of a communication system made feasible due to such advancements. Communication pursuant to a cellular telephone system, or other radio telephonic system, is advantageous as a radio frequency communication channel forms the communication channel connecting a sending and a receiving station operable therein. Because a radio frequency communication channel forms the communication channel, fixed or hard-wired connections are not required to be formed between the sending and receiving stations. Utilization of a cellular, or other radio telephonic, communication system is therefore particularly advantageous when the use of fixed or hard-wired connections to effectuate communications would be inconvenient or impractical.
New services and new forms of communication for new radio communication systems and pursuant to already-installed cellular, and other radio telephonic, networks have also been developed.
Packet data communication systems, for instance, have been developed. In a packet data communication system, information which is to be transmitted between a sending and a receiving station is formatted into discrete packets of data. The packets are sent on a communication channel from the sending station to the receiving station. Because the information is communicated by way of discrete packets which can be transmitted during intermittent bursts, the sending station utilizes the channel only during the time periods required to send the discrete packets. A shared channel, used by a plurality of sending stations, can be used. Because a single channel can be shared by the plurality of sending stations, dedicated channels allocated to individual ones of the sending stations is not required. Lowered costs of communication are thereby possible.
Communications effectuated via the Internet and communications effectuated pursuant to paging networks are exemplary of communication systems in which packet data is transmitted. Standards have also, e.g., been set forth for the communication of packet data in existing cellular networks. GPRS (general packet radio service) communications proposed for the existing GSM (general system for mobile communications) cellular communication system is one such proposal. GPRS provides an existing GSM cellular network with the capability of communicating packet data.
A communication station, referred to as a host, such as a notebook computer, sends and receives packet data. In an Internet application, a host is formed of a computing device. Typically, although not of necessity, when the host accesses the Internet by way of a radio communication system, the host is formed of a notebook computer, or other portable device. And, when the Internet is accessed by way of a radio communication system, the host is also coupled to a radio transceiver, such as a mobile station or, e.g., a PCMCIA radio modem card. The host, together with the mobile station, or analogous device, shall, at times, together hereafter be referred to collectively as a wireless communication station or a “wireless host”.
To communicate a packet of data to a wireless communication station requires that the packet be addressed with an address which identifies the wireless communication station. An Internet protocol (IP) address is exemplary of an identification address which is sometimes used to identify a communication station.
Analogous addresses are used pursuant to other protocols, such as the X.25 protocol.
The identification address used to identify the wireless communication station can be assigned temporarily with a temporary identification address. By assigning a temporary address to identify a wireless communication station, packet data can be addressed with the temporary address. And, therefore, the packet data can be routed to the wireless communication station. The wireless communication station need not have a permanent identification assigned to it as a new temporary address can be assigned to the wireless communication station for each communication session. Also, because a temporary address is used to identify the wireless communication station for only a limited time, the same address can be reassigned for use by different wireless communication stations on an as-needed basis.
A problem might occur, however, if a wireless communication station terminates a communication session abnormally. In an Internet application, for instance, the wireless communication station might access another host device to request information therefrom. And, as noted previously, a notebook computer might form a portion of the wireless communication station. If the notebook computer shuts down during a communication session without undergoing normal log-out procedures, the other host device might not be informed of the termination of the communication session. The other host device similarly might not be informed of the termination if supply of power to the wireless communication station is interrupted, or the wireless communication station moves beyond range of the radio communication network through which it accesses the Internet. Once the communication session is terminated, the temporary address used to identify the wireless communication station might be reassigned to another wireless communication station. And, packet data might be misrouted to the wireless communication station newly-identified with the temporary identification address.
A manner by which to prevent misrouting of packet data subsequent to an abnormal, communication session termination would therefore be advantageous.
It is in light of this background information related to packet data communications that the significant improvements of the present invention have evolved.
SUMMARY OF THE INVENTION
The present invention, accordingly, advantageously provides a method and apparatus for preventing misrouting of data subsequent to an abnormal termination of a communication session between a wireless host and another host device.
In one aspect of the present invention, the wireless host is identified by a temporary address. When the communication session is terminated abnormally by the wireless host, the other host devic
Andersson Dick
Karlsson Torgny
Jenkens & Gilchrist
Pham Chi H.
Telefonaktiebolaget L M Ericsson (publ)
Yao Kwang B.
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