<p>Modern communication systems demand low latency, high data rates, and improved energy efficiency. Nevertheless, Orthogonal Frequency Division Multiplexing (OFDM) modulation, utilized in 4G and 5G networks, exhibits its restrictions in high mobility environments due to channel dispersion caused by Doppler and delay effects. To overcome these constraints, we propose an enhanced version of the Orthogonal Time Frequency Space (OTFS) modulation, wherein the Fast Fourier Transform (FFT) block is exchanged by the Weighted Fractional Fourier Transform (WFrFT). This replacement offers an order <InlineEquation ID="IEq1"> <EquationSource Format="TEX">$\alpha$</EquationSource> <EquationSource Format="MATHML"><math> <mi>α</mi> </math></EquationSource> </InlineEquation>, which facilitates the adjustment to be tailored corresponding to the channel conditions. In order maximize this parameter, we suggest a selection approach based on the Carrier to Interference Ratio (CIR), allowing us to identify the optimal order of <InlineEquation ID="IEq2"> <EquationSource Format="TEX">$\alpha _{opt}$</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>α</mi> <mrow> <mi mathvariant="italic">opt</mi> </mrow> </msub> </math></EquationSource> </InlineEquation> that maximizes the system’s performance. Simulation results reveal that the proposed WFrFT–OTFS with <InlineEquation ID="IEq3"> <EquationSource Format="TEX">$\alpha _{opt}$</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>α</mi> <mrow> <mi mathvariant="italic">opt</mi> </mrow> </msub> </math></EquationSource> </InlineEquation> attains a smaller Bit Error Rate (BER) and higher robustness to Doppler over several propagation scenarios, with representative outcome on Vehicular A and Vehicular B channels. These results demonstrate that <InlineEquation ID="IEq4"> <EquationSource Format="TEX">$\alpha$</EquationSource> <EquationSource Format="MATHML"><math> <mi>α</mi> </math></EquationSource> </InlineEquation> adaptation a viable means to enhance OTFS performance without incurring excessive complexity.</p>

Optimal Alpha Selection in WFrFT-OTFS System Over Doubly Selective Channels

期刊论文
发表日期：

2026年3月9日

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Marwa Rjili,
Abdelhakim Khlifi,
Fatma Ben Saleh,
Belgacem Chibani

摘要

Modern communication systems demand low latency, high data rates, and improved energy efficiency. Nevertheless, Orthogonal Frequency Division Multiplexing (OFDM) modulation, utilized in 4G and 5G networks, exhibits its restrictions in high mobility environments due to channel dispersion caused by Doppler and delay effects. To overcome these constraints, we propose an enhanced version of the Orthogonal Time Frequency Space (OTFS) modulation, wherein the Fast Fourier Transform (FFT) block is exchanged by the Weighted Fractional Fourier Transform (WFrFT). This replacement offers an order $\alpha$ $α$ , which facilitates the adjustment to be tailored corresponding to the channel conditions. In order maximize this parameter, we suggest a selection approach based on the Carrier to Interference Ratio (CIR), allowing us to identify the optimal order of $\alpha _{opt}$ $α_{opt}$ that maximizes the system’s performance. Simulation results reveal that the proposed WFrFT–OTFS with $\alpha _{opt}$ $α_{opt}$ attains a smaller Bit Error Rate (BER) and higher robustness to Doppler over several propagation scenarios, with representative outcome on Vehicular A and Vehicular B channels. These results demonstrate that $\alpha$ $α$ adaptation a viable means to enhance OTFS performance without incurring excessive complexity.