SINR Analysis of Different Multicarrier Waveforms over Doubly Dispersive Channels

TL;DR

This paper derives a closed-form SINR expression for different multicarrier waveforms over doubly dispersive channels, considering both time and frequency selectivity effects simultaneously, and compares their performance.

Contribution

It provides a comprehensive SINR analysis for CP-, ZP-, and UF-OFDM considering joint time-frequency selectivity, which was not addressed in prior work.

Findings

Closed-form SINR expressions derived for various multicarrier schemes.

Comparison of OFDM, ZP-OFDM, and UF-OFDM under different channel conditions.

Insights into the interplay of time and frequency selectivity on multicarrier performance.

Abstract

Wireless channels generally exhibit dispersion in both time and frequency domain, known as doubly selective or doubly dispersive channels. To combat the delay spread effect, multicarrier modulation (MCM) such as orthogonal frequency division multiplexing (OFDM) and its universal filtered variant (UF-OFDM) is employed, leading to the simple per-subcarrier one tap equalization. The time-varying nature of the channel, in particular, the intra-multicarrier-symbol channel variation induces spectral broadening and thus inter-carrier interference (ICI). Existing works address both effects separately, focus on the one effect while ignoring the respective other. This paper considers both effect simultaneously for cyclic prefix (CP)-, zero padded (ZP)- and UF-based OFDM with simple one tap equalization, assuming a general wireless channel model. For this general channel model, we show that the independent (wide sense stationary uncorrelated scatter, WSSUS) selectivity in time and frequency starts to intertwine in contrast to the ideal cases with single selectivity. We derive signal-to-interference-plus-noise ratio (SINR) in closed form for arbitrary system settings and channel parameters, e.g., bandwidth, delay- and Doppler-spread. With the SINR analysis, we compare the three MCM schemes under different channel scenarios.