Flexible Design for $\alpha$-Duplex Communications in Multi-Tier Cellular Networks

TL;DR

This paper develops a flexible stochastic geometry model for multi-tier cellular networks with full-duplex base stations and mixed duplex mode user equipment, analyzing the practical benefits and limitations of FD and HD configurations.

Contribution

It introduces a tractable modeling framework that accounts for uplink vulnerabilities and backward compatibility, providing insights into when FD UEs are advantageous over HD UEs.

Findings

FD UEs offer marginal rate gains (~5%) over HD UEs when combined with FD BSs.

Adding FD UEs to FD BSs yields limited benefits compared to the implementation complexity.

A closed-form expression for the critical self-interference attenuation is derived for FD UEs to outperform HD UEs.

Abstract

Backward compatibility is an essential ingredient for the success of new technologies. In the context of in-band full-duplex (FD) communication, FD base stations (BSs) should support half-duplex (HD) users' equipment (UEs) without sacrificing the foreseen FD gains. This paper presents flexible and tractable modeling framework for multi-tier cellular networks with FD BSs and FD/HD UEs. The presented model is based on stochastic geometry and accounts for the intrinsic vulnerability of uplink transmissions. The results show that FD UEs are not necessarily required to harvest rate gains from FD BSs. In particular, the results show that adding FD UEs to FD BSs offers a maximum of $5\%$ rate gain over FD BSs and HD UEs case if multi-user diversity is exploited, which is a marginal gain compared to the burden required to implement FD transceivers at the UEs' side. To this end, we shed light on practical scenarios where HD UEs operation with FD BSs outperforms the operation when both the BSs and UEs are FD and we find a closed form expression for the critical value of the self-interference attenuation power required for the FD UEs to outperform HD UEs.