Whitening matched filter for use in a communications receiver

A method of whitening matched filtering a plurality of received samples received over a channel, said channel having a mixed phase channel impulse response, said method comprising the steps of:

• generating a whitening matched filter transfer function that includes a minimum phase channel impulse response and a matched filter response, said minimum phase channel impulse response derived from said mixed phase channel impulse response in accordance with homomorphic deconvolution employing cepstral transformation techniques;
• processing said received samples in accordance with said whitening matched filter transfer function in reverse time order with respect to equalizer processing subsequently performed;
• processing samples received before a known training sequence in accordance with said whitening matched filter transfer function in forward time order;
• and
• processing samples received after said known training sequence in accordance with said minimum phase channel impulse response in reverse time order.

A method of whitening matched filtering an input signal received over a channel, said channel having a mixed phase channel impulse response, said method comprising the steps of:

• generating a whitening matched filter transfer function of the form
• H
• WMP
• ⁡
• (
• z
• )
• =
• H
• MP
• ⁡
• (
• z
• )
• H
• WP
• ⁡
• (
• z
• )
• that includes a matched filter response HMF(z) concatenated with a whitening filter response HMF(z) that includes a minimum phase channel impulse response, said minimum phase channel impulse response derived from said mixed phase channel impulse response, said matched filter response derived from the time reversed complex conjugate of said channel impulse response expressed in the equation hMF(t)=h*CIR(−t), wherein matched filtering is performed in the anti-causal direction on said input signal;
• and
• processing said received samples using a filter with said whitening matched filter transfer function in reverse time order with respect to equalizer processing subsequently performed on received samples.

A communications receiver for receiving and decoding an M-ary signal transmitted over a channel having a mixed phase channel impulse response, comprising:

• a radio frequency (RF) front end circuit for receiving and converting said M-ary transmitted signal to a baseband signal;
• a demodulator adapted to receive said baseband signal and to generate a received signal therefrom in accordance with the M-ary modulation scheme used to generate said transmitted signal;
• a whitening matched filter for generating an output signal in response to said receive signal, said whitening matched filter implemented using a processor comprising software means operative to:
• generate a whitening matched filter transfer function including a matched filter response and a minimum phase channel impulse response derived from said mixed phase channel impulse response using cepstral transformation techniques;
• process samples received over said channel before and after a known training sequence in accordance with said whitening matched filter response in reverse time order with respect to equalizer processing subsequently performed;
• and
• said equalizer adapted to equalize the output of said whitening filter so as to generate a sequence of hard symbol decisions therefrom.