Patent ID: 7391711

Claim:
A method for a plurality of remote units of an orthogonal frequency division multiplexing multipoint-to-point communications system, the method comprising: 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; adjusting a characteristic of at least one tone of the plurality of tones of at least one remote unit, in response to adjustment commands from the host unit, such that the orthogonality of the simultaneously received tones is improved as received at the host unit; and wherein adjusting the characteristic comprises adjusting a carrier frequency and a phase.