Abstract: A circuit and method that optimizes a set up time and control of bit and energy loadings of data sub-channels in a multi-channel data transmission signal is disclosed. A time out period, or an iteration count are used to control a setup time. An initialization routine attempts to make appropriate loadings within such time out period or within an iteration count parameter. If it is unable to do so, a handoff is made to a second routine to complete the loadings. In a preferred embodiment the initialization routine calculates rough parameters, while the second routine finalizes the capacity calculations. Another aspect of the invention ensures that the initialization routine can be repeated at a later time to re-compute appropriate bit and energy loadings to ensure that significant changes caused by line disturbances or large data rate variations can be quickly accommodated.

Abstract: An ADSL transceiver includes a new circuit and various iterative initialization and fine tuning routines for optimizing the bit and energy configurations of data sub-channels in a multi-channel data transmission signal. The routines quickly converge to a target data rate by first estimating a power margin, and generating a bounded interval that includes the target rate. Thereafter, a binary iterative portion of the routine takes over and effectuates a final convergence to the target rate. A new mechanism for determining useful sub-channels is also disclosed. The resulting routines are extremely useful in that they maximize a data rate for a given power margin, and conversely, maximize a power margin for a given data rate. Two variants of a fine tuning process are also disclosed, and both can be used in combination to maximize system performance.