Improved Received Method of 1/3-CPCK Systems Based on Pre-FrFT-Filter and Coherent Demodulation

Using very minimum frequency shift chirp (VMFS-chirp) signal as carrier, 1/3 continuous phase chirp keying (1/3-CPCK) has high bandwidth efficient and has been used in bandwidth-limited wireless communication. With high correlation between 1/3-CPCK carriers, the ability of noise suppression in 1/3-CPCK system was low. In order to solve this problem, an improved received method of 1/3-CPCK system was presented in the paper. Using the difference of convergent between VMFS-chirp signal and additive white Gaussian noise (AWGN) in FrFT domain, the improved received method used pre-FrFT-filter (instead of general band-pass filter)before coherent demodulation to suppress AWGN. The difference of convergent was analyzed, and then the improved received method model was built and simulated. Theoretical analysis and simulation results showed that comparing present receiver method with band-pass filter and coherent demodulation, the improved received method has stronger ability of noise suppression and got more than 2dB processing gain.