Sliding-window multi-carrier frequency division multiplexing system
First Claim
1. A receiver comprising a time-to-frequency converter, said time-to-frequency converter configured to receive a stream of data samples and calculate M streams of output values for M communication channels, said converter configured to calculate each of said output values using N input values, wherein the value of N is selected on a channel-by-channel basis such that a first channel uses a value for N that is different from a value of N used by a second channel, said receiver further comprising a first sliding window transform configured to transform said received stream of data samples to said first channel using a first transform length and a second sliding window transform configured to transform said received stream of data samples to said second channel using a second transform length.
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Abstract
A sliding-window multi-carrier communication system is described, wherein the carriers are orthogonal in a local sense, but not necessarily in a global sense. In one embodiment, the system allows a reduction of the length of the basis function time as compared to conventional OFDM systems. In some circumstances, the symbol time can be reduced almost to the basis function length even though the delay spread from channel-to-channel is significant. In one embodiment, a discrete Fourier transform DFT is used in the sliding-window receiver. In one embodiment, the DFT produces M outputs (one output for each of M channels) for each time-domain input. In one embodiment, the DFT produces outputs for M channels from N samples, where N is a basis function length. In one embodiment, the sliding-window receiver provides an adjustable basis-function length. In one embodiment, the basis-function length can be separately selected for each channel. In one embodiment, the sliding-window receiver provides independent equalization for each channel by extracting equalization information from a packet header.
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Citations
29 Claims
- 1. A receiver comprising a time-to-frequency converter, said time-to-frequency converter configured to receive a stream of data samples and calculate M streams of output values for M communication channels, said converter configured to calculate each of said output values using N input values, wherein the value of N is selected on a channel-by-channel basis such that a first channel uses a value for N that is different from a value of N used by a second channel, said receiver further comprising a first sliding window transform configured to transform said received stream of data samples to said first channel using a first transform length and a second sliding window transform configured to transform said received stream of data samples to said second channel using a second transform length.
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8. A communication receiver configured to receive data transmitted on a plurality of carriers, comprising:
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a sub-band filter for separating a received analog signal into a plurality of separate sub-band signals corresponding to a plurality of sub-bands, where at least one of said sub-bands comprises a plurality of sub-channels, said plurality of sub-channels comprising a first sub-channel and a second sub-channel; an analog to digital converter configured to convert a first sub-band signal into a first sub-band digital data stream; a first sliding-window transform configured to transform said first sub-band digital data stream into a first channel data stream using N time-domain input values to generate M frequency domain output values; and
a second sliding-window transform configured to transform said first sub-band digital data stream into a second channel data stream using N input values to generate M frequency domain output values, where the value N used for said second channel is different form the value of N used for said first channel. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29)
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Specification