A Novel Interference Minimizing Waveform for Wireless Channels with Fractional Delay: Inter-block Interference Analysis

TL;DR

This paper proposes a new waveform design using discrete prolate spheroidal sequences to minimize inter-block interference in 4G/5G systems, addressing the challenge of spectral concentration and resource block interference.

Contribution

It introduces a novel waveform approach with mutually orthogonal pulse shapes that are not time-frequency shifts, reducing inter-block interference in wireless channels.

Findings

Analytical upper bounds on IBI are derived.

Simulation results support the effectiveness of the proposed waveform.

Using DPSS reduces IBI compared to traditional methods.

Abstract

In the physical layer (PHY) of modern cellular systems, information is transmitted as a sequence of resource blocks (RBs) across various domains with each resource block limited to a certain time and frequency duration. In the PHY of 4G/5G systems, data is transmitted in the unit of transport block (TB) across a fixed number of physical RBs based on resource allocation decisions. This simultaneous time and frequency localized structure of resource allocation is at odds with the perennial time-frequency compactness limits. Specifically, the band-limiting operation will disrupt the time localization and lead to inter-block interference (IBI). The IBI extent, i.e., the number of neighboring blocks that contribute to the interference, depends mainly on the spectral concentration properties of the signaling waveforms. Deviating from the standard Gabor-frame based multi-carrier approaches which use time-frequency shifted versions of a single prototype pulse, the use of a set of multiple mutually orthogonal pulse shapes-that are not related by a time-frequency shift relationship-is proposed. We hypothesize that using discrete prolate spheroidal sequences (DPSS) as the set of waveform pulse shapes reduces IBI. Analytical expressions for upper bounds on IBI are derived as well as simulation results provided that support our hypothesis.