US 10,374,853 B2 · Method and apparatus for low complexity transmission and reception of constant or quasi-constant envelope continuous phase modulation waveforms

Abstract

To reflect advantages of continuous phase modulation (CPM), the invention provides a low complexity transmitter and receiver to transmit and receive CPM signals and addresses a significant reduction in the CPM demodulator complexity, and is especially well-suited for large values of L, e.g., L≥3. The invention utilizes a linear filter front end as an integral part of the CPM demodulation process to reduce the ISI inherent in CPM transmit signal, and minimizes the influence of L in the reception process. To that end, the invention renders the complexity of a CPM demodulator non-exponentially dependent on L, and L only has a weak impact on the number of coefficients of the linear front end filters. Moreover, the invention provides a simple way of forming CPM signals for a digital communication transmitter using parallel Time Invariant Phase Encoders, which simplifies the production of CPM waveforms on software or hardware.

Claims20

Dependent claims

A demodulator for performing low complexity coherent demodulation of constant or quasi-constant envelope Continuous Phase Modulation (CPM) signals for a baseband received signal to generate desired modulation symbol estimates, wherein the demodulator comprises:

a noise reduction filter for filtering the baseband received signal to generate received samples which are sampled at symbol time;
a bank of K linear Minimum Mean Square Error (MMSE) filters for producing CPM pseudosymbol estimates;
and
a symbol detector for performing symbol detection on the CPM pseudosymbol estimates to generate the desired modulation symbol estimates,
wherein the demodulator is compatible with alphabet lengths (M>=2), all modulation indexes (h), all pulse lengths (L), and all pulse types, K=1 when M=2, and K>1 when M>2, and the K linear MMSE filters are in parallel and combat interference for M>2 or L>1.

2 more elements

A method for low complexity coherent demodulation of constant or quasi-constant envelope Continuous Phase Modulation (CPM) signals for a baseband received signal to generate desired modulation symbol estimates, wherein the method comprises:

filtering the baseband received signal using a bank of K noise reduction filters to generate received samples which are sampled at symbol time;
performing linear filtering on the received samples using a bank of K linear Minimum Mean Square Error (MMSE) filters to produce CPM pseudosymbol estimates;
performing symbol detection on the CPM pseudosymbol estimates to generate the desired modulation symbol estimates,
wherein the method is compatible with alphabet lengths (M>=2), all modulation indexes (h), all pulse lengths (L), and all pulse types, K=1 when M=2, and K>1 when M>2, and the K linear MMSE filters are in parallel and combat interference for M>2 or L>1.

1 more element

Dependencies are inferred from the claim text.

Method and apparatus for low complexity transmission and reception of constant or quasi-constant envelope continuous phase modulation waveforms

Life of this patent

Method and apparatus for low complexity transmission and reception of constant or quasi-constant envelope continuous phase modulation waveforms

Life of this patent

Abstract

Claims20