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.
Highlights
Accommodating the heterogeneity of users’ requirements is one of the main challenges that both industry and academia are facing in order to make 5G a reality [1]
This paper considers the coexistence of enhanced Mobile BroadBand (eMBB) and Ultra Reliable Low Latency Communications (URLLC) services in the uplink of an analog
The rate expressions for URLLC and eMBB users under Orthogonal and Non-Orthogonal Multiple Access (OMA and NOMA, respectively) have been derived considering Analog Radio-over-Copper (A-RoC) as a sample scenario, the proposed model can be adapted to other analog fronthaul technologies
Summary
Accommodating the heterogeneity of users’ requirements is one of the main challenges that both industry and academia are facing in order to make 5G a reality [1]. Next-generation wireless communication systems must be designed to provision different services, each of which with distinct constraints in terms of latency, reliability, and information rate. 5G is expected to support three different macro-categories of services, namely enhanced Mobile BroadBand (eMBB), massive Machine-Type Communications (mMTC), and Ultra-Reliable and Low-Latency. EMBB service is meant to provide very-high data-rate communications as compared with current (4G) networks. This can be generally achieved by using codewords that spread over a large number of time-frequency resources, given that latency is not an issue. MMTC supports low-rate bursty communication between a massive number of uncoordinated devices and the network. URLLC is designed to ensure low-rate ultra-reliable radio access for a few nodes, while guaranteeing very low-latency. URLLC transmissions need to be localized in time, and URLLC packets should be short [5]
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