Patent ID: 7881181

Claim:
A remote service unit using minimum allocations in a multipoint-to-point communication system, the remote service unit comprising: a transceiver communicatively coupled with a host unit in a multipoint-to-point configuration, the transceiver configured to communicate with the host unit via a composite orthogonal frequency division multiplexing (OFDM) waveform of adjacent spectrally overlapping sub-carriers, wherein the transceiver further includes: at least one converter generating an analog signal based on a stream of time domain in-phase and quadrature phase data; and a radio frequency transmitter for transmitting a radio frequency signal based on the analog signal; a multi-carrier modem coupled to the transceiver and configured to modulate upstream payload data onto a plurality of OFDM sub-carriers transmitted by the transceiver, the multi-carrier modem synchronized with the host unit such that the upstream payload data transmitted by the transceiver and other upstream OFDM signals from other transceivers received at the host unit combine to form the composite OFDM waveform, wherein the multi-carrier modulator further includes: at least one symbol mapper that maps data into symbols using quadrature amplitude modulation (QAM) symbol mapping and phase-shift keying (PSK) symbol mapping; and a Fast Fourier Transform (FFT) engine, between the at least one symbol mapper and the transceiver, that receives a frame of parallel data, the Fast Fourier Transform (FFT) engine generating time domain in-phase and quadrature phase data from the parallel data; wherein the remote unit receives channel allocations from the host unit, wherein whenever a channel allocation is made for transport of upstream payload data, the channel allocation provides a plurality of OFDM sub-carriers.