Methods and systems for adaptive modulation are provided. In one
embodiment, a method for a plurality of remote units of an orthogonal
frequency division multiplexing multipoint-to-point communications system
comprises: establishing communication between 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 a
plurality of tones from the plurality of the remote units such that tones
from more than one remote unit are simultaneously received at the host
unit, the plurality of tones modulated with upstream information using
orthogonal frequency division multiplexing; modulating up to a plurality
of tones using a first modulation scheme when transmitting a first type
of upstream information; and modulating up to a plurality of tones using
a second modulation scheme when transmitting a second type of upstream
information.