Synchronization techniques in multipoint-to-point communication using orthogonal frequency division multiplexing
First Claim
Patent Images
1. A system comprising:
- a host unit;
a plurality of remote units using a multiple access scheme to communicate at the same time with the host unit using orthogonal frequency division multiplexing (OFDM);
wherein the host unit repeatedly performs an analysis of a transmission characteristic of at least one upstream signal from at least one remote unit;
wherein the at least one remote unit makes adjustments to the transmission characteristic based on the analyses performed by the host unit to assist the host unit in demodulating a plurality of upstream signals from the plurality of remote units; and
wherein the at least one remote unit maintains frequency and timing parameters of the at least one upstream signal such that OFDM waveform from distinct remote units of the plurality of remote units combine with the at least one upstream signal to form a unified OFDM waveform of overlapping orthogonal carriers at the host unit.
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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.
679 Citations
14 Claims
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1. A system comprising:
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a host unit; a plurality of remote units using a multiple access scheme to communicate at the same time with the host unit using orthogonal frequency division multiplexing (OFDM); wherein the host unit repeatedly performs an analysis of a transmission characteristic of at least one upstream signal from at least one remote unit; wherein the at least one remote unit makes adjustments to the transmission characteristic based on the analyses performed by the host unit to assist the host unit in demodulating a plurality of upstream signals from the plurality of remote units; and wherein the at least one remote unit maintains frequency and timing parameters of the at least one upstream signal such that OFDM waveform from distinct remote units of the plurality of remote units combine with the at least one upstream signal to form a unified OFDM waveform of overlapping orthogonal carriers at the host unit. - View Dependent Claims (2, 3, 4)
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5. A method for multipoint-to-point communication, the method comprising:
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receiving at a host unit 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; determining respective round trip path delay values associated with each of at least two of the plurality of remote units; and wherein the plurality of orthogonal carriers are synchronized in symbol timing and frequency to form a unified OFDM waveform of overlapping orthogonal carriers at the host unit. - View Dependent Claims (6, 7, 8, 9, 10)
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11. A method for a remote unit of an orthogonal frequency division multiplexing (OFDM) multipoint-to-point communications system, the method comprising:
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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 a unified OFDM waveform having a plurality of orthogonal carriers, the plurality of orthogonal carriers modulated using an inverse Fourier transform; wherein an upstream signal on a first orthogonal carrier from the first remote unit combines with an upstream signal on a second orthogonal carrier from at least one other remote unit to form the unified OFDM waveform; and adjusting a timing of at least one signal transmitted between the first remote unit and the host unit based on a round trip delay and adjusting a frequency of the at least one signal transmitted between the first remote unit and the host unit so that the upstream signal on the first orthogonal carrier and the upstream signal on the second orthogonal carrier are synchronized in timing and frequency to form a unified OFDM waveform of overlapping orthogonal carriers at the host unit. - View Dependent Claims (12, 13, 14)
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Specification