A multipoint-to-point, orthogonal frequency division multiplexed (OFDM) communication system is provided. The system includes a plurality of remote units and a host unit that includes a demodulator. Each of the remote units transmits an upstream OFDM signal using a multiple access scheme to the host...http://www.google.de/patents/US7912138?utm_source=gb-gplus-sharePatent US7912138 - Timing and symbol alignment in multipoint-to-point communication using orthogonal frequency division multiplexing
