Patent ID: 7426177

Claim:
A multipoint-to-point, orthogonal frequency division multiplexed (OFDM) communication system comprising: a plurality of remote units; a host unit that includes a demodulator; wherein each of the remote units transmits an upstream OFDM signal using a 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 detects a round trip delay between the host unit and each remote unit; and wherein the host unit transmits at least one timing adjustment signal to at least one of the remote units based at least in part on at least one of the detected round trip delays to assist in aligning the upstream signals received by the host unit; wherein the host unit detects a round trip delay between the host unit and each remote unit at least one of iteratively, repeatedly, and periodically to assist in maintaining alignment of signals at the host unit within the OFDM communication system.