Abstract: Methods and systems to modulate and demodulate first and second path bits within sequences of pulses, where each pulse represents first and second path bits and is position-modulated and phase-modulated based on binary values of the corresponding bits, with no more than 1 phase change per N pulses. Position-modulation may be based on first-path bits. Phase-modulation may be based on second-path bits. A modulator first path has an input data rate Q times that of a second path. The first may include an N-bit encoder. The second path may include a Q-bit encoder and an N-bit repetition encoder. A demodulator includes a first path to determine first path bit values based on pulse coordinates integrated over N frames, and a second path to determine second path bit values based on further integration over Q frames.

Abstract: A mobile communication device to equalize a Doppler shifted received signal according to one embodiment is configured to: extract one or more pilot signals from a segment of the received signal; perform Minimum Mean Square Error (MMSE) filtering on the extracted pilot signals, wherein the filter provides estimated pilot signal impulse responses; estimate the amplitudes of one or more path components of the estimated pilot signal impulse responses; estimate the phases of one or more path components of the estimated pilot signal impulse responses; and combine the estimated amplitudes and the estimated phases of the path components of the pilot signal impulse responses, wherein the combination provides an estimated channel impulse response.

Abstract: Methods and systems to modulate and demodulate first and second path bits within sequences of pulses, where each pulse represents first and second path bits and is position-modulated and phase-modulated based on binary values of the corresponding bits, with no more than 1 phase change per N pulses. Position-modulation may be based on first-path bits. Phase-modulation may be based on second-path bits. A modulator first path has an input data rate Q times that of a second path. The first may include an N-bit encoder. The second path may include a Q-bit encoder and an N-bit repetition encoder. A demodulator includes a first path to determine first path bit values based on pulse coordinates integrated over N frames, and a second path to determine second path bit values based on further integration over Q frames.

Abstract: A mobile communication device to equalize a Doppler shifted received signal according to one embodiment is configured to: extract one or more pilot signals from a segment of the received signal; perform Minimum Mean Square Error (MMSE) filtering on the extracted pilot signals, wherein the filter provides estimated pilot signal impulse responses; estimate the amplitudes of one or more path components of the estimated pilot signal impulse responses; estimate the phases of one or more path components of the estimated pilot signal impulse responses; and combine the estimated amplitudes and the estimated phases of the path components of the pilot signal impulse responses, wherein the combination provides an estimated channel impulse response.