Nova Patents
EP1237340A1

Receiver window design for multicarrier communication systems

Abstract

A receiver window design algorithm (210) is developed which minimizes the noise power of the demodulated multicarrier signal. The windows are effective on a variety of different channels and noise sources. Receiver windowing is a computationally efficient technique for reducing noise spreading in multicarrier communication systems. The algorithm may be implemented in a receiver by utilizing a frequency equalization (FEQ) structure to equalize a channel having a cyclic prefix and shaping a receiver window as a function of the observed channel and noise conditions to reduce the number of errors of the equalized channel in the frequency domain.

EP1237340A1, drawing sheet 1
Sheet 1 of 88

Term

Term ended

Projected expiry passed 28 February 2022, 4.6 years ago.

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20 claims: 13 independent, 7 dependent

  1. 1
    A receiver for use with a multicarrier modulation communication system having noise conditions comprising:a demodulation module dividing a communication channel into multiple subchannels;an equalizer processing the channel;and at least one window having a window output applied before the equalizer responsive to observed the channel and the noise conditions and adapted to reduce error in the demodulator output on a selected set of the subchannels.
  2. 5
    The receiver of any preceding claim where the communication channel has a cyclic prefix and the window is designed according to the equation:w ˆ = R -1 r where: R = E └ Y X , t * Y X,t T ┘ r = E [ Y X,t * d t ] and H ( k ) is the response of subchannel k, X t ( k ) is the input to subchannel k for the t th frame of data, Y t (k) is the unwindowed demodulator output for subchannel k for the t th frame of data, y t ( n ) is the n th received signal from the t th frame of data, N is the number of input symbols, P is the length of the prefix, and W is the length of the window.
  3. 6
    The receiver of any preceding claim comprising multiple said windows each adapted for a predetermined subset of the subchannels, the window outputs being combined to reduce the error in the demodulator output on a selected set of the subchannels.
  4. 9
    The receiver of any preceding claim where the communication channel input has a cyclic prefix and the window is updated iteratively according to the equation:w ˆ = w ˆ +µ( k ) e t ( k ) y e,t * ( k ) where µ( k ) is a scalar.
  5. 10
    A method of receiver windowing in a multicarrier modulation communication system, comprising the steps of:a) utilizing a frequency equalization (FEQ) structure to equalize a channel having a    cyclic prefix;and b) shaping a receiver window as a function of the observed channel and noise conditions to    reduce the number of errors of the equalized channel in the frequency domain.
  6. 13
    The method of any of claims 10 to 12 wherein the receiver window is incorporated prior to the FEQ structure.
  7. 14
    The method of any of claims 10 to 13 wherein the receiver window is adapted for use in a discrete multitone (DMT) modulation system.
  8. 15
    The method of any of claims 10 to 14 wherein the receiver window is adapted for use in an orthogonal frequency division multiplexing (OFDM) modulation system.
  9. 16
    The method of any of claims 10 to 15 wherein the receiver window is responsively updated for a given channel and noise environment.
  10. 17
    The method of any of claims 10 to 16 comprising multiple said receiver windows, each said receiver window optimized for a given subset of subchannels.
  11. 18
    The receiver of any of claims 10 to 17 wherein the receiver window minimizing the noise at the FEQ output is defined by the equation:w ˆ = R D -1 r D where: R D = E [ Y X,t * DY X,t T ] r D = E [ Y X,t * Dd t ] D = Q H Q and Q is a matrix.
  12. 19
    The method of any of claims 10 to 18 wherein the receiver window minimizing the noise at the FEQ output is defined by the equation:w ˆ = w ˆ +µ( k ) e t ( k ) y e,t * ( k ) where µ( k ) is a scalar.
  13. 20
    The method of any of claims 10 to 19 wherein the receiver window utilizes samples of the cyclic prefix to alter samples from the end of a DMT symbol.
Independent claims13