Design and Implementation of Low Complexity Reconfigurable Filtered-OFDM based LDACS

TL;DR

This paper presents a low complexity, reconfigurable filtered OFDM design for LDACS that enhances spectrum utilization and performance, validated through extensive experimental analysis on a Zynq-based testbed.

Contribution

It introduces a novel multi-stage digital filter for LDACS, achieving lower complexity and higher bandwidth than existing methods, and demonstrates its effectiveness through real-world testing.

Findings

Superior spectral attenuation and bandwidth performance

Reduced implementation complexity and group delay

Enhanced robustness against interference and wireless channel effects

Abstract

L-band Digital Aeronautical Communication System (LDACS) aims to exploit vacant spectrum in L-band via spectrum sharing, and orthogonal frequency division multiplexing (OFDM) is the currently accepted LDACS waveform. Recently, various works dealing with improving the spectrum utilization of LDACS via filtering/windowing are being explored. In this direction, we propose an improved and low complexity reconfigurable filtered OFDM (LRef-OFDM) based LDACS using novel interpolation and masking based multi-stage digital filter. The proposed filter is designed to meet the stringent non-uniform spectral attenuation requirements of LDACS standard. It offers significantly lower complexity as well as higher transmission bandwidth than state-of-the-art approaches. We also integrate the proposed filter in our end-to-end LDACS testbed realized using Zynq System on Chip and analyze the performance in the presence of $L$-band legacy user interference as well as LDACS specific wireless channels. Via extensive experimental results, we demonstrate the superiority of the proposed LRef-OFDM over OFDM and Filtered-OFDM based LDACS in terms of power spectral density, bit error rate, implementation complexity, and group delay parameters.