Multiplex communications – Communication techniques for information carried in plural... – Combining or distributing information via frequency channels
Reexamination Certificate
1998-03-16
2001-11-20
Rao, Seema S. (Department: 2662)
Multiplex communications
Communication techniques for information carried in plural...
Combining or distributing information via frequency channels
C370S494000, C370S495000, C370S528000, C379S093280, C379S093310
Reexamination Certificate
active
06320879
ABSTRACT:
FIELD OF THE INVENTION
The present invention generally relates to telephony and data communication and, in particular, to a system and method for concurrently communicating digital data and a telephone ringing cadence to facilitate the transfer of information within a telephone subscriber loop by interleaving the transmission of telephone rings and the transmission of digital data.
BACKGROUND OF THE INVENTION
In data communications over a local telephone subscriber loop where simultaneous or alternating plain old telephone system (POTS) services are present, both digital data and ring signals are transmitted over the same transmission lines. Even though known methods attempt to make the data communications and the POTS communications independent via techniques such as frequency division multiplexing, reliable independence is impractical to achieve. The initiation of a ring signal is unpredictable and will typically cause data transmission errors and disrupt data transmission from the beginning of the ringing cadence, during the ringing cadence, and at least for some duration after cessation of the ringing cadence. Moreover, telephone ring interruption may cause loss of a digital data session due to the long communication interruption.
Some prior art systems have the capability of retransmitting data to a remote modem when communication errors occur. However, in these systems, the remote modem sends a notification to the transmitting modem to indicate that a reception has occurred and to request a retransmission. However, due to the largest and relatively long disturbance of a ringing signal, such notification is often not received by the transmitting modem when a ringing signal is causing the communication error.
Moreover, in some applications where telephone rings occur often, data operation may become impractical due to the frequency of telephone ring interruption. While it is possible to attempt to make the digital data path and the simultaneous POTS path mutually independent, for example, via POTS-splitter filters, this is often practically impossible due to the extremely large amplitude of the interfering signals with respect to the data signals. Therefore, for concurrent digital data communication and POTS communication (where digital data communication may be interrupted from time to time by ring signal requests for POTS service), sustained digital data communication is often not possible during the telephone ringing cadence associated with a request for POTS service.
Thus, a heretofore unaddressed need exists in the industry for providing a system and method for interleaving the transmission of telephone rings and digital data.
SUMMARY OF THE INVENTION
The present invention overcomes the inadequacies and deficiencies of the prior art as discussed herein. The present invention provides for a communication system and method for enabling the reliable concurrent transmission of POTS and digital data in the presence of disturbances such as telephone ringing signals.
The communication system and method utilize a data transmitter and a data receiver. The data transmitter is preferably configured to detect a ring signal, to stop the transmission of any digital data (if any such transmission exists), and to delay and store any desired transmission of digital data until the ring signal has ceased. After the cessation of the interrupting ring signal, the data transmitter preferably retransmits the digital data interrupted by the ring signal (if such interruption occurred) before resuming normal transmission operation. The data receiver is preferably configured to receive the transmitted data, to discard any data interrupted by the ring signal, and to process uninterrupted transmitted data.
In accordance with another feature of the present invention, the retransmitted data may include a header to indicate that the data being transmitted is a retransmission of a previously interrupted data signal. The transmission of this header may prompt the data receiver to discard the data signal received prior to the transmission of the header.
In accordance with another embodiment of the present invention, the data transmitter may be configured to delay the ring signal rather than to allow the ring signal to interrupt the data signal. In this regard, the data transmitter is configured to delay the ring signal when a ring request is received while the data transmitter is transmitting the data signal. The data transmitter ensures that the data signal is successfully transmitted by waiting until the data signal is reliably received by the data receiver before permitting the ring signal to occur.
The communication system and method of the present invention have many advantages, a few of which are delineated hereafter, as examples.
An advantage of the communication system and method is that they provide for the transmission of data signals during the intervals of silence in a ringing cadence. This provides faster and more efficient communications by allowing the concurrent transmission of a ringing cadence and data signals.
Another advantage of the telephone communication system and method is that they provide for elimination of digital data loss when a digital data communication session is interrupted by a ring signal. Such a scheme enhances the reliability of digital data communications over a subscriber loop.
Another advantage of the telephone communication system and method is that interruptions of a transmission of a data signal by a ring signal can be prevented, thereby ensuring the accuracy of the digital data signal.
Other features and advantages of the invention will become apparent to one skilled in the art upon examination of the following drawings in the detailed description. It is intended that all such additional features and advantages be included herein within the scope of the invention, as is defined by the claims.
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Horstemeyer Scott A.
Paradyne Corporation
Rao Seema S.
Thomas Kayden Horstemeyer & Risley
Tsegaye Saba
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