An Efficient Spectral Leakage Filtering for IEEE 802.11af in TV White Space

TL;DR

This paper introduces an asymmetric pulse shaping scheme that effectively reduces spectral leakage in IEEE 802.11af OFDM systems while minimizing inter-symbol interference, enhancing spectral efficiency.

Contribution

It proposes a novel asymmetric pulse shaping method that outperforms conventional filters in spectral leakage suppression with shorter guard intervals.

Findings

Better spectral leakage suppression compared to traditional filters.

Reduced inter-symbol interference with shorter guard intervals.

Improved spectral efficiency in IEEE 802.11af systems.

Abstract

Orthogonal frequency division multiplexing (OFDM) has been widely adopted for modern wireless standards and become a key enabling technology for cognitive radios. However, one of its main drawbacks is significant spectral leakage due to the accumulation of multiple sinc-shaped subcarriers. In this paper, we present a novel pulse shaping scheme for efficient spectral leakage suppression in OFDM based physical layer of IEEE 802.11af standard. With conventional pulse shaping filters such as a raised-cosine filter, vestigial symmetry can be used to reduce spectral leakage very effectively. However, these pulse shaping filters require long guard interval, i.e., cyclic prefix in an OFDM system, to avoid inter-symbol interference (ISI), resulting in a loss of spectral efficiency. The proposed pulse shaping method based on asymmetric pulse shaping achieves better spectral leakage suppression and decreases ISI caused by filtering as compared to conventional pulse shaping filters.