Intelligent timing recovery for a broadband adaptive equalizer
First Claim
1. A broadband wireless radio receiver for receiving a QPSK modulated radio signal including one or more packets of user information and overhead symbols, comprising:
- means for demodulating the radio signal into a baseband signal;
means for oversampling the baseband signal coupled to the demodulating means;
channel estimation means for generating a channel impulse response signal based on the baseband signal;
timing recovery means for generating a symbol timing parameter and a burst timing parameter based on the channel impulse response signal;
memory means for storing an oversampled baseband signal and outputting samples of the baseband signal based on the symbol timing parameter and the burst timing parameter; and
an equalizer for receiving the samples of the baseband signal from the memory means and outputting detected data, the equalizer including a feedback section and a feedforward section.
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Accused Products
Abstract
A timing recovery process for digital receivers employing decision-feedback equalization (DFE) or delayed decision-feedback sequence estimation (DDFSE) can be executed prior to equalization, minimizes training complexity, and provides fast equalizer start-up for transmissions of short packets. The optimum symbol timing and burst timing is determined by (i) calculating a signal-to-intersymbol interference-plus-noise ratio (SINR) index by estimating the channel impulse response and the noise power, and (ii) varying the symbol timing and the burst timing to maximize the calculated SINR index. The timing recovery process particularly improves performance of a digital receiver utilizing (a) decision-feedback equalizer structures in which the delay spread is large compared to the span of the feedforward filter, and (b) equalizer structures based on delayed decision-feedback sequence estimation in which the delay spread is large compared to the memory of the Viterbi sequence estimator section.
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Citations
19 Claims
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1. A broadband wireless radio receiver for receiving a QPSK modulated radio signal including one or more packets of user information and overhead symbols, comprising:
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means for demodulating the radio signal into a baseband signal; means for oversampling the baseband signal coupled to the demodulating means; channel estimation means for generating a channel impulse response signal based on the baseband signal; timing recovery means for generating a symbol timing parameter and a burst timing parameter based on the channel impulse response signal; memory means for storing an oversampled baseband signal and outputting samples of the baseband signal based on the symbol timing parameter and the burst timing parameter; and an equalizer for receiving the samples of the baseband signal from the memory means and outputting detected data, the equalizer including a feedback section and a feedforward section. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for detecting data for use in a broadband wireless radio receiver which includes an equalizer, the equalizer including a feedforward section and a feedback section, comprising the following steps:
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(A) generating a channel impulse response signal based on a baseband signal; (B) generating a symbol timing parameter and a burst timing parameter based on the channel impulse response signal; (C) outputting samples of the baseband signal using the symbol timing parameter and the burst timing parameter; and (D) equalizing samples of the baseband signal to detect data. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18, 19)
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Specification