Abstract: 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 unit demodulator using at least one of a plurality of orthogonal tones within an OFDM waveform. The host unit receives the upstream OFDM signals from a plurality of the remote units. Portions of upstream OFDM signals from at least two of the remote units arrive at the host unit at the same time. The host unit demodulator demodulates the portions and the upstream signals from the plurality of remote units arrive at the host unit synchronized in time and frequency within the OFDM waveform.

Abstract: Systems and methods for orthogonal frequency division multiplexing are provided. In one embodiment, a multi-carrier modem comprising: 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; 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; and a controller programmed to instruct the transmitter to transmit a coarse timing adjustment followed by at least one secondary timing adjustment, wherein the secondary timing adjustment is a fine tuning adjustment with respect to the coarse timing adjustment.

Abstract: A bidirectional communication system is provided. In one embodiment, a method for an orthogonal frequency division multiplexing multipoint-to-point communications system comprises establishing communication between a first remote unit of a plurality of remote units and a host unit, the plurality of remote units communicatively coupled to the host unit in a multipoint-to-point configuration using orthogonal frequency division multiplexing; and adjusting a round trip path delay associated with the first remote unit.

Abstract: 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 unit demodulator using at least one of a plurality of orthogonal tones within an OFDM waveform. 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. Portions of upstream OFDM signals from at least two of the remote units arrive at the host unit at the same time. The host unit demodulator demodulates the portions of the upstream OFDM signals.

Abstract: 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.

Abstract: Systems and methods for orthogonal frequency division multiplexing are provided. In one embodiment, a multi-carrier modem comprising: 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; 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; and a controller programmed to multiplex both payload data and control data onto a first carrier of the spectrally overlapping carrier signals.

Abstract: A bidirectional communication system is provided. In one embodiment, a system comprises a host and a plurality of remote units, wherein a plurality of tones is shared among the plurality of remote units in order to communicate with the host using orthogonal frequency division multiplexing, wherein the plurality of tones is shared in a manner that permits at least two of the remote units to transmit to the host at any one time using the plurality of tones. The host causes at least one remote unit to adjust a timing of symbols transmitted on at least one of the plurality of orthogonal tones in order to improve an alignment of multiframes received at the host.

Abstract: Systems and methods for ranging adjustments are provided. In one embodiment, a remote service unit comprises: a transceiver communicatively coupled with a host in a multi-point to point configuration, the transceiver configured to communicate with the host via an OFDM waveform; and a multi-carrier modem coupled to the transceiver and configured to demodulate downstream information data from the OFDM waveform, the multi-carrier modem further configured to modulate upstream information data onto the OFDM waveform. The multi-carrier modem modulates upstream information data onto distinct subcarriers of the OFDM waveform, the multi-carrier modem synchronized with the host so that upstream OFDM signals transmitted by the transceiver and other upstream OFDM signals received at the host unit combine to a unified OFDM waveform. The multi-carrier modem adjusts a round trip path delay between the remote service unit and the host based on a path delay correction received from the host unit.

Abstract: Systems and methods for OFDM tone allocation are provided. In one embodiment, an end-user communication device comprises: a first remote unit for communicating with a host unit using orthogonal frequency division multiplexing (OFDM), the host unit communicatively coupled to a plurality of remote units in a multipoint-to-point configuration, wherein OFDM waveform from distinct remote units of the plurality of remote units combine to a unified OFDM waveform at the host unit. The first remote unit is configured to transmit up to a plurality of tones, the up to a plurality of tones modulated with upstream information using OFDM. The first remote unit is configured to determine when bandwidth is needed for upstream transmission to the host unit. The first remote unit is configured to transmit a request for bandwidth to the host unit on a first tone of the plurality of tones, wherein access to the first tone is contention-based.

Abstract: Methods and systems for selecting modulation in an orthogonal frequency division multiplexing system are provided. In one embodiment, a method for a remote unit of an OFDM multipoint-to-point communications system comprises: establishing communication between a first remote unit and a host unit, the first remote unit and a plurality of remote units communicatively coupled to the host unit in a multipoint-to-point configuration; transmitting a plurality of tones from the first remote unit such that tones from the first remote unit and at least one other remote unit are simultaneously received at the host unit, the plurality of tones modulated with upstream information using OFDM; modulating up to a plurality of tones using a first modulation scheme when transmitting a first type of upstream information; and modulating up to a plurality of tones using a second modulation scheme when transmitting a second type of upstream information.

Abstract: Systems and methods for synchronization techniques in multipoint-to-point communication using orthogonal frequency division multiplexing are provided. In one embodiment, a method for multipoint-to-point communication 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; and determining respective round trip path delay values associated with each of at least two of the plurality of remote units.

Abstract: A multipoint-to-point, orthogonal frequency division multiplexed (OFDM) communication system is provided. In one embodiment, a system includes: a host unit including a demodulator that simultaneously demodulates upstream information modulated on a plurality of tones within an OFDM waveform, and a plurality of remote units for transmission of upstream information, each remote unit including a modem, the remote units modulating a plurality of tones with upstream information so that when received at the host unit the tones are orthogonal within the OFDM waveform.

Abstract: A bidirectional communication system is provided. The system includes a first remote unit for communicating with a host unit using orthogonal frequency division multiplexing. The host unit is communicatively coupled to a plurality of remote units in a multipoint-to-point configuration. The first remote unit is configured to transmit up to a plurality of tones and the first remote unit includes a modulator for modulating the plurality of tones with upstream information using orthogonal frequency division multiplexing such that when any tones are transmitted from the first remote unit and at least one other remote unit of the plurality of remote units, the tones are substantially orthogonal when received at the host unit.

Abstract: Systems for multiple use subchannels are provided. In one embodiment, a bidirectional communication system comprises: a first remote unit for communicating with a host using OFDM, the host communicatively coupled to a plurality of remote units in a multipoint-to-point configuration. The first remote unit is configured to transmit up to a plurality of tones, the up to a plurality of tones modulated with upstream information using OFDM, the first remote unit including a modulator for modulating the up to a plurality of tones using OFDM. The modulator is configured to adjust a carrier frequency and timing of the plurality of tones such that when any tones are transmitted from the first remote unit and at least one other remote unit, the orthogonality of the tones when received at the host unit is improved. Both control data and payload data are transmitted on a first tone of the plurality of tones.

Abstract: Systems and methods for multiuse subcarriers in multipoint-to-point communication using orthogonal frequency division multiplexing (OFDM) are provided. In one embodiment, a remote unit for communicating with a host unit using OFDM is provided, the host unit communicatively coupled to a plurality of remote units in a multipoint-to-point configuration. The remote unit comprises a modulator for modulating up to a plurality of tones with upstream information using orthogonal frequency division multiplexing, wherein the modulator is configured to adjust a carrier frequency and timing of the plurality of tones such that spectrally overlapping tones transmitted from the remote unit and at least one other remote unit of the plurality of remote units are orthogonal and combine to form an OFDM waveform when received at the host; and wherein a first tone of the plurality of tones carries both control data and payload data.

Abstract: Systems and methods for an orthogonal frequency division multiplexing multipoint-to-point communications system are provided. In one embodiment, a method comprises establishing communication between a first remote unit of a plurality of remote units and a host unit, the plurality of remote units communicatively coupled to the host unit in a multipoint-to-point configuration; transmitting up to a plurality of tones from the first remote unit, the up to a plurality of tones modulated with upstream information using orthogonal frequency division multiplexing; modulating the up to a plurality of tones using a first modulation scheme when transmitting a first type of upstream information; and modulating the up to a plurality of tones using a second modulation scheme when transmitting a second type of upstream information.

Abstract: Methods and systems for training sequences are provided. In one embodiment, a bi-directional communication system comprises: a multipoint-to-point host unit; and a plurality of remote units communicatively coupled to the multipoint-to-point host unit through an orthogonal frequency division multiplexing waveform. The multipoint-to-point host unit is configured to receive the orthogonal frequency division multiplexing waveform, the orthogonal frequency division multiplexing waveform comprising a plurality of tones transmitted by the plurality of remote units. The plurality of remote units each transmit a training pattern to the host unit on at least one of the plurality of tones; and the multipoint-to-point host unit is configured to adjust demodulation of upstream information from the plurality of tones based on the training pattern.

Abstract: Systems and methods for round-trip-delay adjustment in a multipoint-to-point orthogonal frequency division multiplexing (OFDM) system are provided. In one embodiment, a method for a remote unit to request bandwidth in an Orthogonal Frequency Division Multiplexing (OFDM) multi-point to point system comprises: transmitting a signal from a remote unit having a request for bandwidth to a host unit on a first tone, the signal from the remote unit configured to combine with a signal from at least one other remote unit on a different tone to form a coherent OFDM waveform; determining when a collision has occurred on the first tone between the signal transmitted by the remote unit and a signal from at least one other remote unit; and when a collision occurs, re-transmitting the request for bandwidth on the first tone.

Abstract: Systems for multiple use subchannels are provided. In one embodiment, a bidirectional communication system comprises: a first remote for communicating with a host using orthogonal frequency division multiplexing (OFDM), the host communicatively coupled to a plurality of remotes in a multipoint-to-point configuration; wherein the first remote is configured to transmit up to a plurality of tones modulated with upstream information using OFDM; the first remote including a modulator for modulating the up to a plurality of tones with upstream information using OFDM, wherein the modulator is configured to adjust a carrier frequency of the plurality of tones such that when any tones are transmitted from the first remote and at least one other remote of the plurality of remotes, the orthogonality of the tones when received at the host is improved; and wherein both control data and payload data are transmitted on a first tone of the plurality of tones.

Abstract: Systems and methods for bidirectional communication are provided. In one embodiment, a multipoint-to-point, orthogonal frequency division multiplexed (OFDM) communication system comprises: a plurality of remote units, a host unit; wherein the host sends an adjustment signal to a remote instructing the remote to adjust the timing of transmissions from the remote to improve orthogonality of the OFDM waveform received at the host, wherein the host sends an adjustment signal to a remote instructing the remote to adjust the frequency of transmissions from the remote to improve orthogonality of the OFDM waveform received at the host, wherein payload data is transmitted between a remote and the host over a first orthogonal tone within the OFDM communication system during a first time interval, and wherein control data is transmitted between a remote and the host over the first orthogonal tone within the OFDM communication system during a second time interval.