Joint Carrier Phase Estimation and Turbo Decoding Using Bit Carrier Phase APP Decoder

Abstract

-In this paper we present an algorithm for joint carrier phase estimation and turbo decoding for the case of rapidly varying carrier phase during the transmitted block. The proposed algorithm shows improved performance over previously proposed communication schemes, both coherent and non-coherent, for channels with Additive White Gaussian Noise (AWGN) and high carrier phase noise. The novel algorithm utilizes a modified "two dimensional" Bit-Carrierphase A Posteriori Probability (BCAPP) decoder containing additional states representing the received carrier phase. The BCAPP decoder calculates two extrinsic metrics; one representing the bit soft value and the other representing the received carrier phase Probability Density Function (PDF) approximation. A modified structure of the turbo code iterations is suggested, implementing separate propagation of the two metrics between the BCAPP decoders. Most known methods to combat very high phase noise in the channel at low signal to noise ratio are based on non-coherent demodulation. Such reception schemes are designed for the worst-case phase noise and suffer high degradation for any level of phase noise. In our scheme, together with improved performance in high phase noise, the degradation decreases with the actual channel phase noise level. We show the robustness against phase noise model mismatch.

Robust algorithm for high‐dynamic and low‐signal‐to‐noise ratio signal reception in deep space communications

“…Some algorithms are based on the maximum-likelihood (ML) or maximum-a-posteriori (MAP) estimation [11], which offers sufficient theoretical support but suffers from high computational complexity. Other algorithms utilise the soft decision outputs of decoder as the feedback information to construct a target function, and then estimate the synchronisation parameters by optimisation [12,13].…”