Non-Orthogonal eMBB-URLLC Radio Access for Cloud Radio Access Networks with Analog Fronthauling

TL;DR

This paper analyzes the performance of non-orthogonal radio access in C-RAN architectures with analog fronthauling, showing NOMA's advantages in higher eMBB rates and reliable URLLC with low latency, using an information-theoretic approach.

Contribution

It provides an information-theoretic analysis of NOMA versus OMA in analog fronthaul C-RAN, highlighting performance benefits and decoding strategies.

Findings

NOMA achieves higher eMBB rates than OMA.

NOMA with SIC provides the best overall performance.

TIN outperforms puncturing in analog fronthaul scenarios.

Abstract

This paper considers the coexistence of Ultra Reliable Low Latency Communications (URLLC) and enhanced Mobile BroadBand (eMBB) services in the uplink of Cloud Radio Access Network (C-RAN) architecture based on the relaying of radio signals over analog fronthaul links. While Orthogonal Multiple Access (OMA) to the radio resources enables the isolation and the separate design of different 5G services, Non-Orthogonal Multiple Access (NOMA) can enhance the system performance by sharing wireless and fronthaul resources. This paper provides an information-theoretic perspective in the performance of URLLC and eMBB traffic under both OMA and NOMA. The analysis focuses on standard cellular models with additive Gaussian noise links and a finite inter-cell interference span, and it accounts for different decoding strategies such as puncturing, Treating Interference as Noise (TIN) and Successive Interference Cancellation (SIC). Numerical results demonstrate that, for the considered analog fronthauling C-RAN architecture, NOMA achieves higher eMBB rates with respect to OMA, while guaranteeing reliable low-rate URLLC communication with minimal access latency. Moreover, NOMA under SIC is seen to achieve the best performance, while, unlike the case with digital capacity-constrained fronthaul links, TIN always outperforms puncturing.