ADAPTIVE MODULATION IN MULTIPOINT-TO-POINT COMMUNICATION USING ORTHOGONAL FREQUENCY DIVISION MULTIPLEXING

摘要

Systems for adaptive modulation in multipoint-to-point communication using orthgonal frequency division multiplexing (OFDM) are provided. In one embodiment, a system comprises: a host unit; and a plurality of remote units using a multiple access scheme to communicate at the same time with the host unit using OFDM; wherein the host unit sends an adjustment signal to at least one of the remote units instructing the at least one remote unit to adjust the timing of transmissions from the remote unit to improve orthogonality of an OFDM waveform received at the host unit; wherein the host unit allocates tones within the OFDM waveform to the plurality of remote units; wherein different modulation schemes are used on different tones within the OFDM waveform; and wherein the host unit allocates tones within the OFDM waveform based on at least one of type of data to be transmitted and error rate requirement.