摘要:
Systems and methods for orthogonal frequency division multiplexing are provided. In one embodiment, a multi-carrier modem comprises: 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 modulating a first carrier of the plurality of spectrally overlapping carrier signals based on a first modulation scheme while modulating a second carrier of the plurality of spectrally overlapping carrier signals based on a second modulation scheme.
摘要:
Systems and methods for orthogonal frequency division multiplexing are provided. In one embodiment, a multi-carrier modem comprises: 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 modulating a first carrier of the plurality of spectrally overlapping carrier signals based on a first modulation scheme while modulating a second carrier of the plurality of spectrally overlapping carrier signals based on a second modulation scheme.
摘要:
Systems and methods for orthogonal frequency division multiplexing are provided. In one embodiment, a multi-carrier modem comprises: a receiver configured to receive a waveform comprising spectrally overlapping carrier signals from at least two of a plurality of remotes, wherein the spectrally overlapping carrier signals are modulated using an inverse Fourier transform algorithm; a transmitter; a processor coupled to the transmitter, wherein the processor outputs data for transmission by the transmitter, wherein the processor applies an inverse Fourier transform algorithm to the data provided to the transmitter; a controller programmed to calculate an elapsed time for each of the two remotes, the elapsed time representing a time between transmitting a ranging signal to a remote and receiving a signal from the remote in response to the ranging signal; the controller further programmed to reducing any difference between at least two elapsed times by instructing at least one of the plurality of remotes to adjust a delay.
摘要:
Systems and methods for orthogonal frequency division multiplexing are provided. In one embodiment, a multi-carrier modem comprises: a receiver configured to receive a waveform comprising spectrally overlapping carrier signals from at least two of a plurality of remotes, wherein the spectrally overlapping carrier signals are modulated using an inverse Fourier transform algorithm; a transmitter; a processor coupled to the transmitter, wherein the processor outputs data for transmission by the transmitter, wherein the processor applies an inverse Fourier transform algorithm to the data provided to the transmitter; a controller programmed to calculate an elapsed time for each of the two remotes, the elapsed time representing a time between transmitting a ranging signal to a remote and receiving a signal from the remote in response to the ranging signal; the controller further programmed to reducing any difference between at least two elapsed times by instructing at least one of the plurality of remotes to adjust a delay.
摘要:
Systems and methods for orthogonal frequency division multiplexing are provided. In one embodiment, a multi-carrier modem comprises: a receiver configured to receive a waveform comprising a plurality of spectrally overlapping carrier signals from at least two of a plurality of remotes, the carrier signals are modulated using an inverse Fourier transform; a transmitter; a processor coupled to the transmitter, the processor outputs data for transmission to the transmitter, the processor applies an inverse Fourier transform to the data provided to the transmitter; a controller programmed to instruct the transmitter to transmit timing adjustments to the at least two of the plurality of remotes, the timing adjustments instruct the at least two of the plurality of remotes to adjust transmission timing so that transmitted symbols associated with frames of a predetermined multiframe structure are received in sequence from the at least two of the plurality of remotes based on the structure.
摘要:
Systems and methods for orthogonal frequency division multiplexing are provided. In one embodiment, a method for ranging comprises: receiving at a host a plurality of upstream symbols transmitted from a plurality of remote units, the upstream symbols transmitted on a plurality of orthogonal carriers modulated using an inverse Fourier transform; comparing a phase of at least one ranging symbol received from at least one of the plurality of remote units with a phase of a symbol transmitted by the host; and transmitting an adjustment instruction instructing the at least one of the plurality of remote units to vary a phase of transmissions transmitted from the at least one of the plurality of remote units based on a difference in phase between the at least one ranging symbol and the symbol transmitted by the host unit.
摘要:
Systems and methods for orthogonal frequency division multiplexing are provided. In one embodiment, a method for communication comprises receiving baseband user data; modulating the baseband user data onto a first plurality of parallel streams based on a first modulation constellation; modulating non-user data onto a second plurality of parallel streams based on a second modulation constellation, wherein the first modulation constellation provides a higher bit-rate than the second modulation constellation; applying an inverse Fourier transform algorithm to the first plurality of parallel streams and the second plurality of parallel streams to produce a set of complex time-domain samples; and transmitting a radio frequency transmission signal based on the set of complex time-domain samples.
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; a transmitter configured to modulate symbols onto at least one of a plurality of the spectrally overlapping carrier signals; and 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 programmed to multiplex upstream information onto an allocated number of the plurality of spectrally overlapping carrier signals based on an allocation instruction received be the receiver.
摘要:
Systems for contention-based bandwidth requests in orthogonal frequency division multiplexing (OFDM) systems are provided. In one embodiment, a bidirectional communication system comprises: a multipoint-to-point host; and a plurality of remotes communicatively coupled to the multipoint-to-point host through an OFDM waveform; wherein the multipoint-to-point host is configured to receive the OFDM waveform, the OFDM waveform comprising a plurality of tones transmitted by the plurality of remotes, wherein the plurality of tones are simultaneously received at the host from at least two of the plurality of remotes; wherein a first remote is configured to transmit a request for bandwidth to the host on a first tone of the plurality of tones, wherein access to the first tone is contention based; and wherein the multipoint-to-point host transmits information on at least one tone based on whether the host successfully receives the request for bandwidth from the first remote of the plurality of remotes.
摘要:
Systems and methods for orthogonal frequency division multiplexing are provided. In one embodiment, a multi-carrier modem comprises: a receiver configured to receive a waveform comprising a plurality of spectrally overlapping carrier signals from at least two of a plurality of remote units, wherein the plurality of spectrally overlapping carrier signals are modulated using an inverse Fourier transform algorithm; a transmitter; a processor coupled to the transmitter, wherein the processor outputs data for transmission to the transmitter, wherein the processor applies an inverse Fourier transform algorithm to the data provided to the transmitter; and a controller programmed to analyze a training signal received from a first remote unit and adjust receiver equalizer parameters based on the training signal.