Advanced Micro Devices Corporation

Ping Hou

Chien-Meen Hwang

Xu Zhou

Harish Kutagulla

Christine Lee

Yong Li

Jia-Pei Shen

A channel tracking module, configured for generating updated equalization coefficients for a frequency equalizer, is configured for determining a digital-based error value between equalized signals output by the frequency equalizer relative to predicted signals, for each subcarrier frequency of an OFDM symbol. The channel tracking module determines an accumulated error based on accumulating the digital-based error values for all the subcarrier frequencies of the OFDM symbol, for a prescribed successive number of OFDM symbols. The channel tracking module also determines a step size based on the accumulated error and relative to a prescribed step function configured for optimizing equalizer adjustments within stability limits. The channel tracking updates the equalization coefficients for each subscarrier frequency based on the accumulated error and the step size. Hence, the channel tracking module can be implemented in an economical manner while ensuring optimum equalizer adjustments within stability limits that ensure convergence of the equalization coefficients.

Channel tracking using step size based on norm-1 based errors across multiple OFDM symbols

A channel estimator is configured for determining a gain adjustment for a received wireless signal having a prescribed plurality of tones. The channel estimator is configured for generating, for each of the tones, a corresponding pseudo power value representing a detected power level for the corresponding tone. An accumulated pseudo power value is obtained based on accumulating the respective pseudo power values of the prescribed plurality of tones. Each of the pseudo power values is selectively adjusted by an adjustment factor based on a determined difference between the accumulated pseudo power value relative to an expected accumulated power level relative to a prescribed dynamic range. The pseudo power values are then output for decoding of data modulated at the respective tones.

OFDM receiver having adaptive channel estimator for correcting channel fading based on accumulated pseudo power values

An OFDM receiver has an autocorrelation circuit configured for generating autocorrelated power values from samples of received short preamble symbols in a received data packet, and a median filter configured for generating a median autocorrelation value from at least a prescribed minimum number of the autocorrelated signal values. A comparator is configured for detecting a symbol boundary, identifying an end of the short preamble symbols, based on the autocorrelated signal values falling below a threshold that is based on the median autocorrelation value. Hence, the threshold used to identify the symbol boundary is dynamically calculated on a per-packet basis, eliminating errors due to varying energy levels or propagation characteristics from different packet sources; moreover, the median autocorrelation value minimizes effects due to noise components, minimizing false detection errors.

Autocorrelation threshold generation based on median filtering for symbol boundary detection in an OFDM receiver

A channel estimator, configured for supplying equalization coefficients to a frequency equalizer, is configured for determining equalizer coefficients for a received wireless signal based on a minimum equalization error-based estimation. The channel estimator is configured for identifying first and second long preambles from the received wireless signal, determining an equalization coefficient for a selected frequency based on a minimized cost function for the first and second long preambles relative to a prescribed preamble value for the selected frequency, and supplying the equalization coefficient for the selected frequency to a frequency equalizer for equalization of the received wireless signal.

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San Carlos, CA, United States of America

Ping Hou