Functional Split Perspectives: A Disruptive Approach to RAN Performance Improvement
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Radio access network (RAN) centralized processing and cell densification have been promising research and development focuses on the fifth generation (5G) network. The required centralized processing and complexity of an ultra-dense network can be effectively managed with the aids of cloud RAN (C-RAN). The focus on the C-RAN is due to its significant benefits concerning cost-effectiveness and performance optimization. However, the C-RAN mobile fronthaul (MFH) demands transport networks with very low-latency and very high-throughput. These requirements for the 5G use cases and deployment scenarios are stringent and uneconomical in the real-life scenarios. These growing requirements can be effectively lessened with the RAN functional split option (FunStiOn) techniques. This paper offers a comprehensive overview of the traditional C-RAN MFH and considers some viable RAN FunStiOn techniques that can help in relaxing the stringent requirements. The related trade-offs of the considered RAN FunStiOns are also presented. In addition, we offer and discuss a number of relevant cost-effective architectural variants that can relatively simplify the DU designs with low-footprints. The presented architectural variants can be employed to support different use cases of the emerging 5G networks depending on the deployment scenarios.
KeywordsCentral unit Common public radio interface Deployment scenarios Distributed unit Functional split option Mobile fronthaul Mobile network operators Radio access network Use cases
This work is supported by the European Regional Development Fund (FEDER), through the Regional Operational Programme of Lisbon (POR LISBOA 2020) and the Competitiveness and Internationalization Operational Programme (COMPETE 2020) of the Portugal 2020 framework, Project 5G (POCI-01-0247-FEDER-024539), ORCIP (CENTRO-01-0145-FEDER-022141) and SOCA (CENTRO-01-0145-FEDER-000010).
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