Multiplex communications – Communication over free space – Having a plurality of contiguous regions served by...
Reexamination Certificate
2000-03-02
2004-08-24
Nguyen, Steven H. D (Department: 2665)
Multiplex communications
Communication over free space
Having a plurality of contiguous regions served by...
C370S235000, C455S442000, C455S445000
Reexamination Certificate
active
06781979
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to connection control for controlling logical and physical connections of data communication and, more particularly, to a connection control device, a connection control method, a recording medium which records a connection control program and a data communication system enabling more efficient communication on a line switching system.
2. Description of the Related Art
Among communication systems for a data communication network such as the internet, most commonly employed is the packet exchange system. On the other hand, for a user to use a data communication network, commonly done is connecting to a provider or the like based on the line switching system using telephone lines.
Line switching system, which is one of switching modes for use in data transmission, is a switching system in which between a transmission side DTE (Data Terminating Equipment) which transmits information and a reception side DTE, a physical communication path is set up for every communication to transmit and receive data. The communication path set up here allows no other user to use and accordingly, a communication charge is ordinarily fixed according to a time period of line use.
In recent years, frequent mode of use is using a data communication network such as the internet from a data terminating equipment by means of a portable communication device outdoors and even in this case, connection to the data communication network is made through a radio telephone line of the line switching system using a portable telephone, personal handyphone system (PHS) or the like.
For making a connection to a data communication network by using the line switching service of a mobile communication network, employed is a dial-up server for the relay to a packet exchange network which terminates connections made by line switching. The dial-up server is in some cases disposed within a mobile communication network.
For making a connection to the internet from a mobile communication terminal, it is a common practice to, after making a connection to a dial-up server using telephone services and establishing a link by means of the PPP(Point to Point Protocol; RFC 1661) which is a layer 2 protocol (data link protocol), use the TCP/IP (Transmission Control Protocol/Internet Protocol) which is a higher-order protocol.
As to connection/disconnection between a mobile communication terminal and a dial-up server, telephone connection and PPP link are established upon a request from a user using the mobile terminal device. PPP monitors a state of a line and when the line is disconnected while a link is being established, ends the link.
In such mobile communication, however, propagation environments are often unstable to cause line disconnection. In data communication and the like using a mobile communication terminal, therefore, a once established logical line link is in many cases released (disconnected) as a physical line is disconnected.
As described in the foregoing, conventional connection control devices have the following problems.
First problem is wasteful consumption of telephone line resources such as radio resource.
The reason is that in data communication employing the line switching system, as described above, connection of a telephone line is continued from a connection request until a disconnection request made by a user similarly to a case of voice communication, thereby exclusively using the line while no data is transmitted thereon.
Telephone line resources such as radio resources are shared by numbers of users and affect a capacity of the entire system, and lack of line resources causes a problem that a new connection can not be made by other users.
In addition, it is a common practice in the line switching system to fix charges of use according to a time period of line use and even a connection time when data is actually neither sent nor received is charged, which is uneconomical for users.
Second problem is that when a line is disconnected due to some reason or other during communication, data communication should be ended halfway to conduct all the procedures for connection all over again from the beginning, which is inefficient and laborious operation.
Thirdly, in mobile communication, line disconnection often happens as mentioned above and every time the line disconnection occurs, a PPP link ends. Then, when communication is to be made with the same connection destination again such as in a case where desired data communication is yet to be completed, a user needs to make a connection request again to establish a PPP link.
Also in communication using the TCP such as the internet, when an interruption occurs, a TCP connection is released, so that data communication should be made over again starting with a connection and set-up of the connection.
SUMMARY OF THE INVENTION
An object of the present invention is to make efficient use of communication resources in data communication employing line switching, as well as providing environments convenient for users and efficient data communication.
According to the first aspect of the invention, a connection control device for controlling data communication involving set-up of a connection
provided on both sides of a communication source and a communication destination to control connection states of both sides in cooperation with a communication partner, each the device controlling communication between a data terminating equipment and a data circuit-terminating equipment on the side the device is disposed, comprising:
connection holding means for holding the state of an established connection after a disconnection of a physical line, and
communication resuming means for resuming communication by the connection held after a re-connection of a physical line.
In the preferred construction, wherein the state of a connection with a communication partner has three kinds of:
a release state indicative of a state where a physical line is disconnected and a connection is released,
a communication state indicative of a state where a physical line is connected and a connection is established, and
a wait state indicative of a state where a physical line is disconnected while holding a connection, and which further comprises
control means for processing a transition of the connection states.
In another preferred construction, the connection control device further comprises a control message communication means for transmitting and receiving information of a communication partner and information of a transition of the connection states to and from the communication partner as a control message, wherein
when receiving an instruction of a kind designated for controlling a connection of communication from the data terminating equipment, the control message communication means transmits the control message indicative of information of the instruction in question to the communication partner prior to execution of the instruction.
In another preferred construction, the connection control device further comprises information storage means for storing information of a communication partner and information of a connection with the communication partner, wherein
every time a new connection is established, the information storage means stores information of a communication partner having the connection in question and information of the connection in question.
In another preferred construction, when at the communication state, a physical line is disconnected without receiving a notification of a communication disconnection by the control message from a communication partner,
information stored in the information storage means is held as it is to make a transition to the wait state without executing processing of communication end by a disconnection of a physical line with respect to the data terminating equipment.
In another preferred construction, the connection control device further comprises a timer for determining a lapse of a fixed time, wherein
when no transmission and reception of communication d
Ebata Koichi
Takeda Kenji
NEC Corporation
Nguyen Steven H. D
Whitham Curtis & Christofferson, PC
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