Design of a Dual-Level Polar-Coded Scheme for GCI-DCSK Systems

In this letter, we present a polar-coded scheme tailored to enhance transmission reliability in generalized carrier index differential chaos shift keying (GCI-DCSK) systems. Considering the reliability difference between the index and modulated layers in GCI-DCSK, we develop a dual-level polar-coded modulation (DLC-PCM) scheme that provides unequal error protection (UEP). Furthermore, to better manage the reliability differences among index bits in the GCI-DCSK system, we propose a dual-level bit-interleaved polar-coded modulation (DLC-BIPCM) scheme by incorporating a bit-interleaved coded modulation (BICM) structure within the index layer. Additionally, we derive log-likelihood ratio (LLR) expressions and calculate the capacities of both the index and modulated layers to strategically guide the design of the DLC-PCM scheme. Simulation results demonstrate that our proposed polar-coded approach achieves superior bit error rate (BER) performance and lower complexity compared to existing low-density parity-check (LDPC)-based schemes.