Systems and method for orthogonal frequency divisional multiplexing

摘要

Systems and methods for orthogonal frequency division multiplexing are provided. In one embodiment, a multi-carrier modem comprises: a receiver configured to de-modulate symbols from at least one of a plurality of spectrally overlapping carrier signals to produce a receiver output; a transmitter configured to modulate symbols onto at least one of a plurality of the spectrally overlapping carrier signals; a processor coupled to the transmitter, wherein the processor outputs data for transmission by the transmitter, wherein the processor applies an inverse Fourier transform to the data transmitted by the transmitter; the processor coupled to the receiver, wherein the processor applies a Fourier transform to the receiver output; and a controller programmed to instruct the transmitter to transmit at least one symbol representing a request for bandwidth allocation on a first carrier; wherein the controller is further programmed to determine when a collision has occurred on the first carrier.

主权项

1. A remote communication device for operation in a bidirectional communication system, the device comprising:
at least one symbol mapper for mapping symbols using quadrature amplitude modulation (QAM) symbol mapping and phase-shift keying (PSK) symbol mapping; an Inverse Fast Fourier Transform (IFFT) engine operating on frequency domain that receives a frame of parallel frequency domain data based on symbol data generated by the symbol mapper, the Inverse Fast Fourier Transform (IFFT) engine generating a frame of time domain in-phase and quadrature phase data from the frame of parallel frequency domain data which is generated based on symbol data generated by the symbol mapper; at least one converter generating an analog signal based on the stream of time domain in-phase and quadrature phase data; a radio frequency transmitter for transmitting a radio frequency signal based on the analog signal; and a processor, wherein the symbol mapper is responsive to the processor, and the processor controls synchronization of symbol timing and carrier frequency of transmissions from the radio frequency transmitter.