Pilot-based PSC Fractional Channel Estimation for Self-Adaptive AFDM Communications

Résumé fourni par la source

As a new chirp-based multicarrier scheme, affine frequency division multiplexing (AFDM) can fully compensate for performance degradation caused by both propagation delay and the Doppler effect in wireless communications with high mobility. Furthermore, AFDM can be considered more flexible and adaptive than orthogonal time frequency space (OTFS) modulation. This paper considers integrated sensing and communication (ISAC) based on AFDM that can adapt to users’ mobility. To realize such ISAC, a channel estimation scheme to cope with fractional Doppler shifts is proposed. After transforming received signals in the discrete affine Fourier transform (DAFT) domain into a pseudo delay-Doppler (DD) domain, the proposed scheme searches for peaks of correlation between received pilot signals and a checking function in the pseudo DD domain, which is referred to as pilot-based peak searching correlation (PSC). In contrast with conventional channel estimation methods for AFDM, the proposed algorithm does not require prior information on the number of propagation paths, which can increase the feasibility of the proposed channel estimation scheme in real-world scenarios. AFDM along with the PSC channel estimation can adaptively control parameters of AFDM, thereby achieving better trade-off between spectral efficiency and bit error rate (BER) than that of OTFS. Computer simulations demonstrate that AFDM employing the proposed channel estimation scheme can adjust the parameters to channel conditions, thereby overcoming OTFS in terms of both adaptability and flexibility.

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