Terminal adapter, switching equipment ancillary device and data communication system

• US 5,722,085 A
• Filed: 09/18/1995
• Issued: 02/24/1998
• Est. Priority Date: 09/20/1994
• Status: Expired due to Fees

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Horikawa, Kiyotaka
• Primary Examiner(s): MacDonald, Allen R.
• Assistant Examiner(s): Richardson, Scott
• Application Number:
  US08/529,443
• Time in Patent Office: 890 Days
• Field of Search: 379/58, 379/59, 379/60, 455/10, 455/33.1, 455/33.2, 455/54.2, 455/557
• US Class Current: 455/557
• CPC Class Codes: H04M 11/06 Simultaneous speech and data transmission, e.g. telegraphic transmission over the same conductors

Abstract

Each of a terminal adapter and a switching equipment ancillary device has a protocol controller for analyzing and controlling a communication protocol control signal transmitted from a data terminal, so that a modem interface can directly be set to an originate mode or an answer mode. As a mobile station has no modem function, the switching equipment ancillary device and a modem terminal are synchronized with each other by a clock signal, and transmit and receive data therebetween. A transmission delay caused by a retransmission effected under error correction control on a communication line is adjusted by flow control between the modem interface and the modem terminal.

Claims

1. A terminal adapter for use in a mobile station of a data communication system, comprising:

a terminal interface unit configured to interface with a data terminal;

a protocol controller coupled to the terminal interface unit and configured to analyze and control a communication protocol control signal transmitted to and received from said data terminal; and

an ARQ interface unit coupled to the protocol controller and the terminal interface unit and configured to effect ARQ control as an error correction control on a transmission path connected to switching equipment of the data communication system,

wherein, upon output of an originate mode call request command and an accompanying destination telephone number from the data terminal, the protocol controller discriminates the outputted data and outputs the discriminated data according to a particular protocol format to the switching equipment, and

wherein the protocol controller further outputs a connection request to the switching equipment for connection to a switching equipment ancillary device coupled to the switching equipment, so as to establish ARQ synchronization between the ARQ interface unit and the switching equipment ancillary device.

5. A data communication system according to claim 1, wherein the mobile station does not include a modem function, and wherein the switching equipment serves as the modem function for the mobile station for a data communications between the mobile station and a destination location.

2. A switching equipment ancillary device for effecting data communications between switching equipment of a data communication system and a mobile station which includes a terminal adapter having an interface unit configured to interface with a data terminal, an analyzing and controlling unit configured to analyze and control a communication protocol control signal transmitted to and received from the data terminal, and an ARQ interface unit configured to control as an error correction control on a transmission path connected to the switching equipment, the switching equipment ancillary device comprising:

a controller configured to control communication protocols matching transmission path characteristics between the switching equipment and the data terminal; and

a modem interface coupled to the controller and configured to effect data communications with a modem terminal at a destination location separate from the mobile station, the modem terminal being connected to a destination location via a telephone line;

wherein the modem interface effects flow control during the data communications with the modem terminal, and

wherein clock synchronization is required only between the modem interface of the switching equipment ancillary device and the modem terminal to effect the data communications between the mobile station and the destination location.

6. A data communication system according to claim 2, wherein no clock synchronization is maintained at the mobile station during the data communications between the mobile station and the destination location.

8. A data communication system according to claim 2, wherein, when the controller receives an originate mode call request command from the mobile station to initiate a call setup to the destination location, the controller sets the modem interface to an originate mode, and

wherein negotiations for communication protocols are then started between the modem interface in the originate mode and the destination location.

9. A data communication system according to claim 8, wherein, upon completion of the negotiations, the switching equipment ancillary device transmits a negotiations signal to the mobile station, so as to inform the mobile station that the data communications can be started between the mobile station and the destination location.

3. A data communication system comprising:

switching equipment;

a mobile station connected to the switching equipment through a communication line, and including a data terminal, a mobile unit, and a terminal adapter having a terminal interface unit coupled to the data terminal and configured to analyze and control a communication protocol signal transmitted to and received from the data terminal, and an ARQ interface coupled to the terminal interface unit and configured to provide ARQ control as an error correction control on a transmission path connection to the switching equipment;

a fixed station connected to the switching equipment through a public telephone network and having a modem terminal and a data terminal; and

a switching equipment ancillary device including a protocol controller configured to control communication protocols matching transmission path characteristics between the switching equipment and the data terminal, a modem interface coupled to the protocol controller and configured to effect data communications with an analog data modem, the modem interface also providing flow control during the data communications with the analog data modem.

wherein the analog data modem is located at a destination location which corresponds to a desired location of a call originated from the mobile station, and

wherein clock synchronization is maintained only between the analog data modem at the destination location and the modem interface at the switching equipment ancillary device during the data communications between the mobile station and the destination location.

7. A data communication system according to claim 3, wherein no clock synchronization is maintained at the mobile station during the data communications between the mobile station and the destination location.

10. A data communication system according to claim 3, wherein, when the protocol controller receives an originate mode call request command from the mobile station to initiate a call setup to the destination location, the protocol controller sets the modem interface to an originate mode, and

wherein negotiations for communication protocols are then started between the modem interface in the originate mode and the destination location.

11. A data communication system according to claim 10, wherein, upon completion of the negotiations, the switching equipment ancillary device transmits a negotiations signal to the mobile station, so as to inform the mobile station that the data communications can be started between the mobile station and the destination location.

4. A data communication method carried out by a data communication system which includes a mobile station connected to a switching equipment through a communication path, the mobile station including a data terminal, a mobile unit, and a terminal adapter, the data communication system further including a fixed station communicatively connected to the switching equipment through a public telephone network, the fixed station having a modem terminal and a data terminal, and the data communication system still further including a switching equipment ancillary device connected to the switching equipment, the method comprising the steps of:

entering an originate mode call request command and a fixed station telephone number from the data terminal into the terminal adapter;

discriminating the originate mode call request command and the fixed station telephone number in the terminal adapter, and indicating the fixed station telephone number to the mobile unit;

transmitting the indicated fixed station telephone number from the mobile unit and connecting the mobile unit to the fixed station;

sending a connection request from the terminal adapter through the mobile unit to the switching equipment for connection to the switching equipment ancillary device;

starting the switching equipment ancillary device from the switching equipment to establish ARQ synchronization between the terminal adapter and the switching equipment ancillary device;

transmitting an answer tone from the fixed station to the switching equipment ancillary device when the incoming call from the mobile station is detected by the fixed station;

transmitting an originate mode call request command from the terminal adapter to the switching equipment ancillary device;

starting negotiations for communication protocols between the switching equipment ancillary device and the fixed station when the switching equipment ancillary device receives the originate mode call request command;

indicating completion of the negotiations from the switching equipment ancillary device to the terminal adapter when the negotiations are completed successfully; and

transmitting and receiving data between the data terminal of the mobile station and the data terminal of the fixed station through the terminal adapter, the mobile unit, the switching equipment and the switching equipment ancillary device.