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. 2018 Sep 2;20(9):661.
doi: 10.3390/e20090661.

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

Andrea Matera  1 , Rahif Kassab  2 , Osvaldo Simeone  2 , Umberto Spagnolini  1
Affiliations

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

Andrea Matera et al. Entropy (Basel). .

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.

Keywords: C-RAN; RoC; URLLC; eMBB; network slicing.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
C-RAN architecture overview for uplink direction: (a) Digital Radio-over-Fiber, (b) Analog Radio-over-Fiber, (c) Analog Radio-over-Radio, (d) Analog Radio-over-Copper.
Figure 2
Figure 2
Model of the uplink of C-RAN system based on Analog Radio-over-Copper (A-RoC) fronthauling.
Figure 3
Figure 3
Time-frequency resource allocation: (a) Orthogonal Multiple Access (OMA) and (b) Non-Orthogonal Multiple Access (NOMA). Downwards arrows denote arrival of URLLC packets.
Figure 4
Figure 4
Space-frequency cable resource allocation.
Figure 5
Figure 5
Mapping of radio resources over cable resources: (a) maximum normalized cable bandwidth (full redundancy), μ=1, or η=lS; (b) minimal normalized cable bandwidth (no redundancy), μ=1/lS, or η=1.
Figure 6
Figure 6
Relationship between the signal rk (21) obtained at the output of the combiner and the radio received signal yk in (15).
Figure 7
Figure 7
Block diagram of the operation of the ENs and BBU for Orthogonal Multiple Access (OMA). A/A stands for Analog-to-Analog.
Figure 8
Figure 8
Block diagram of the operation of the ENs and BBU for Non-Orthogonal Multiple Access (NOMA) by puncturing and Treating Interference as Noise (TIN). A/A stands for Analog-to-Analog.
Figure 9
Figure 9
Block diagram of the operation of the ENs and BBU for Non-Orthogonal Multiple Access (NOMA) by Successive Interference Cancellation (SIC). A/A stands for Analog-to-Analog.
Figure 10
Figure 10
URLLC and eMBB per-UE rates as a function of fronthaul crosstalk interference power γ2 for OMA and NOMA with puncturing.
Figure 11
Figure 11
URLLC and eMBB rates vs. probability of URLLC arrival q for OMA and NOMA by puncturing, treating interference as noise (TIN), and successive interference cancellation (SIC).
Figure 12
Figure 12
eMBB rates for NOMA by SIC vs. power of residual URLLC interference ρ2.
Figure 13
Figure 13
URLLC and eMBB per-UE rates as a function of access latency LU for OMA and NOMA with puncturing.
See this image and copyright information in PMC

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