A hybrid TIM-NOMA scheme for the SISO Broadcast Channel

TL;DR

This paper proposes a hybrid TIM-NOMA scheme for SISO broadcast channels that enhances network capacity by combining interference management techniques, achieving significant sum rate improvements at high SNR levels without requiring channel state information at transmitters.

Contribution

It introduces a novel hybrid TIM-NOMA scheme for SISO K-user cells, combining interference management and superposition coding to improve sum rate performance.

Findings

At high SNR, the scheme doubles the sum rate compared to TDMA.

The method effectively manages inter-group and intra-group interference.

Achieves 1/T DoF per user in the proposed grouping.

Abstract

Future mobile communication networks will require enhanced network efficiency and reduced system overhead due to their user density and high data rate demanding applications of the mobile devices. Research on Blind Interference Alignment (BIA) and Topological Interference Management (TIM) has shown that optimal Degrees of Freedom (DoF) can be achieved, in the absence of Channel State Information (CSI) at the transmitters, reducing the network's overhead. Moreover, the recently emerged Non-Orthogonal Multiple Access (NOMA) scheme suggests a different multiple access approach, compared to the current orthogonal methods employed in 4G networks, resulting in high capacity gains. Our contribution is a hybrid TIM-NOMA scheme in Single-Input-Single-Output (SISO) K-user cells, in which users are divided into T groups, and 1/T DoF is achieved for each user. By superimposing users in the power domain, we introduce a two-stage decoding process, managing 'inter-group' interference based on the TIM principles, and 'intra-group' interference based on Successful Interference Cancellation (SIC), as proposed by NOMA. We show that for high SNR values the hybrid scheme can improve the sum rate by at least 100% when compared to Time Division Multiple Access (TDMA).