Advanced Micro Devices Corporation

Christine Lee

Chien-Meen Hwang

Xu Zhou

Howard Hicks

Ping Hou

Yong Li

An OFDM wireless transceiver uses a digital automatic gain control (AGC) module. The digital AGC module is configured for setting a gain to an initial gain value for mapping a received wireless signal to a first power value for an input circuit having a prescribed input range. The initial gain value is set relative to the prescribed input range and a prescribed signal to noise ratio. If the digital AGC module determines that the first power value of the received wireless signal does not exceed the prescribed input range, the digital AGC module calculates an optimum gain for the received wireless signal relative to the initial gain value and the first power value; if the first power value exceeds the prescribed input range, the AGC module determines the optimum gain based on setting the gain to a minimum gain value.

Optimal initial gain selection for wireless receiver

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 Viterbi decoder is configured for outputting a prescribed plural number of decoded bit pairs upon execution of each backtracing operation based on accessing a second prescribed number of state history table entries from a surviving state history table. The outputting of more bits per backtrace operation lowers the number of memory accesses, and enables the Viterbi decoder to maintain a high throughput of data flow while maintaining an acceptable bit error rate.

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Mountain View, CA, United States of America

Christine Lee