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A Robust LLR Initialization Method for Combating Constant Amplitude Random Phase Jamming
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DOI：10.1109/TCOMM.2026.3658377.png)
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Abstract
En 中文
Jamming in some cases observed at its transmitting side could be modeled as a constant amplitude but random phase signal: <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$J(t) = A_{J}\cdot e^{j\phi (t)}$ </tex-math></inline-formula>. Such situation may happen in single-tone or multi-tone jammed frequency hopping systems, in cellular mobile systems under co-channel interference, etc. In order to appropriately handle this kind of jamming through channel coding technologies, a jamming model based log-likelihood ratio (LLR) initialization method is proposed to replace their conventional AWGN model based LLR initialization method. Accordingly, the optimal LLR initialization formula is derived based on the analysis of the probability density function of jammed signals. Then, the approximation of optimal LLR initialization as well as its robust variant are further provided, hence the complexity is significantly reduced and only the signal-to-noise ratio (SNR) and signal-to-jamming ratio (SJR) are required as the a priori knowledge. The proposed LLR initialization method is tested in a Polar Code (PC) coded Orthogonal Frequency Division Multiplexing (OFDM) system, where both the AWGN and the Rayleigh fading channel models are considered. The obtained simulation results demonstrate that the proposed method outperforms the conventional Gaussian model based one and other existed robust initialization methods.
Keywords:
Anti-jamming
log-likelihood ratio
channel coding
Journal
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8.3
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1.2W
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3.6W