At+t Corp.

Mahendra Patel

Robert Earl Scott

James L Archibald

Joan E Landry

In transmitting information over a cellular communications channel to an opposite endpoint, a modem's autorating routine is 'data-driven.' In particular, when the amount of information to transmit to the opposite endpoint is low, the modem's data rate is low e.g., 4800 bps, and the modem's ability to autorate upwards, i.e., fallforward, is disabled. However, when the amount of information to transmit to the opposite endpoint is high the modem's ability to fallforward is enabled so that the modem's data rate can increase to the highest permissible data rate for the cellular channel in order to transmit large blocks of information.

Data-driven autorating for use in data communications

Some data communications networks employ the use of both a leased line and a dial-up line between two modems. Typically, the dial-up line provides a backup capability when the leased line causes a degradation in the signal quality of the data signal. This degradation of the signal quality of the data signal is detected by one of the two modems, which then automatically establishes a data connection over the dial-up line. However, it is preferable to switch back to the leased line as soon as possible since the leased line usually costs less than the dial-up line. Therefore, in order to test the leased line, the entire data signal is simultaneously transmitted on both the dial-up line and the leased line. The use of the existing data signal to test the leased line's effect on signal quality allows the modem to perform a more complete analysis of the returned data signal so that a premature transition back to the leased line does not occur.

Method and apparatus for switching communications from a secondary

In a mobile data communications system, a near-end modem initiates a data connection to a far-end modem at the highest permissible data rate, e.g., at 9600 bits per second (bps). If the communications channel subsequently degrades, either the near-end modem, or the far-end modem, initiates an autorate, or fallback sequence, e.g., to 4800 bps. However, if channel performance is still poor at 4800 bps, then one, or both, of the modems initiate a fallback to 1200 bps--skipping over the data rate of 2400 bps, which is not included within the fallback sequence.

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Brandon, FL, United States of America

Mahendra Patel