Methods for an orthogonal frequency division multiplexing
multipoint-to-point communications system are provided. In one
embodiment, a method comprises: establishing communication between a
first remote unit of a plurality of remote units and a host unit, the
plurality of remote units communicatively coupled to the host unit in a
multipoint-to-point configuration; transmitting up to a plurality of
tones from the first remote unit, the up to a plurality of tones
modulated with upstream information using orthogonal frequency division
multiplexing; adjusting at least one characteristic of the plurality of
tones such that when any tones are transmitted from the first remote unit
and at least one other remote unit of the plurality of remote units, the
orthogonality of the tones when received at the host unit is improved;
and dynamically switching modulation between tones of the plurality of
tones to reduce the impact of using any corrupted tones.