Cognitive Interference Alignment for OFDM Two-tiered Networks

TL;DR

This paper proposes an interference alignment scheme for OFDM two-tiered networks, enabling coexistence of macro-cell and cognitive small-cell, with an optimal linear strategy maximizing spectral efficiency under Rayleigh and exponential decay channels.

Contribution

It introduces an optimal linear precoding strategy for cognitive small-cells in OFDM networks, enhancing spectral efficiency in two-tiered structures.

Findings

Proposed precoder is optimal for Rayleigh and exponential decay channels.

Analytical and numerical results confirm the scheme's effectiveness.

Maximizes spectral efficiency for secondary base stations.

Abstract

In this contribution, we introduce an interference alignment scheme that allows the coexistence of an orthogonal frequency division multiplexing (OFDM) macro-cell and a cognitive small-cell, deployed in a two-tiered structure and transmitting over the same bandwidth. We derive the optimal linear strategy for the single antenna secondary base station, maximizing the spectral efficiency of the opportunistic link, accounting for both signal sub-space structure and power loading strategy. Our analytical and numerical findings prove that the precoder structure proposed is optimal for the considered scenario in the face of Rayleigh and exponential decaying channels.