Patent ID: 7480236

Claim:
A multipoint-to-point, orthogonal frequency division multiplexed (OFDM) communication system comprising: a plurality of remote units; and a host unit that includes a demodulator; wherein each of the remote units transmits an upstream OFDM signal using multiple access scheme to the host unit demodulator using at least one of a plurality of orthogonal tones within an OFDM waveform, wherein upstream OFDM signals from at least two of the plurality of remote units combine to a unified OFDM waveform at the host unit; wherein the host unit receives the upstream OFDM signals from a plurality of the remote units, the tones of the upstream signals being substantially orthogonal when received at the host unit; wherein portions of upstream OFDM signals from at least two of the remote units arrive at the host unit at the same time; wherein the host unit demodulator demodulates said portions; 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 the unified OFDM waveform received at the host unit; wherein the host unit incorporates a remote unit identification code within at least one downstream OFDM signal to designate a specific remote unit for which the downstream signal is intended; and wherein the host unit correlates the identification code with a unique identifier for the specific remote unit.