Error Rate Analysis and Low-Complexity Receiver Design for Zero-Padded AFDM

TL;DR

This work addresses reliable data transmission in high-mobility, doubly selective channels by introducing zero-padded AFDM (ZP-AFDM). It develops a transceiver that exploits the ZP-induced lower-triangular time-domain channel structure and proposes two low-complexity detectors: a Cholesky-based MMSE detector without matrix inversion and an MRC-TD detector, alongside BER analyses for ML and MMSE detection. Theoretical BER expressions and complexity analyses are complemented by simulations showing that the proposed detectors achieve BERs nearly identical to a conventional MMSE detector but with substantial reductions in complexity, and that ZP-AFDM outperforms CPP-AFDM and CP-OFDM in the tested scenarios. These results suggest practical, Doppler-resilient multicarrier receivers with reduced computation for next-generation wireless systems.

Abstract

This paper studies the error rate performance and low-complexity receiver design for zero-padded affine frequency division multiplexing (ZP-AFDM) systems. By exploiting the unique ZP-aided lower triangular structure of the time domain (TD) channel matrix, we propose {a novel low-complexity} minimum mean square error (MMSE) detector and {a} maximum ratio combining-based TD (MRC-TD) detector. Furthermore, the theoretical bit error rate (BER) {performance} of both MMSE and maximum likelihood detectors {is} analyzed. Simulation results demonstrate {that} the proposed detectors can achieve identical BER performance to that of {the conventional MMSE detector based on matrix inversion} while {enjoying significantly reduced complexity.}

Figures (7)

• Figure 1: Transceiver diagram of the proposed ZP-AFDM system.
• Figure 2: Illustration of the TD channel matrix $\mathbf{H}$ for CPP-AFDM and ZP-AFDM with $N=16$ and $Q = 3$.
• Figure 3: The Cholesky factorization of the banded matrix $\mathbf{\Psi}$ with $N=8$ and $Q=2$.
• Figure 4: BER performance of the ML detector and theoretical upper bounds for the ZP-AFDM system with different numbers of paths.
• Figure 5: Simulated and analytical BER comparisons of CPP-AFDM and ZP-AFDM systems using conventional MMSE detector under $\nu_{\max} = 0.5$.