Cloudification and slicing in 5G radio access network

The forthcoming fifth generation (5G) mobile networks is ambitious to evolve a broad variety of capabilities for the intended usage scenarios. To facilitate this vision, a paradigm shift is provided in 5G to establish a flexible and customizable communication system. Essentially, the 5G architecture shall be designed with a certain level control flexibility via incorporating the principles of softwarization and virtualization to turn a physical network into multiple customized end-to-end (E2E) logical network tailored to multiple service requests. Correspondingly, two key pillars are highlighted and investigated for the 5G network: slicing and cloudification. These two techniques are mostly challenging in the radio access network (RAN) domains due to its stringent requirements among real-timeliness, computing complexity, energy performance, and dependency of geographical and hardware. To this end, this thesis is organized in two parts to investigates these two techniques on the RAN domain. In the first part, we investigate the cloudification of the RAN, i.e., cloud RAN (C-RAN), in which the centralized RAN processing in a cloud can support efficient resource multiplexing and joint multi-cell processing. Despite its appealing, the C-RAN concept faces challenges in terms of the severe capacity and latency requirements of the fronthaul (FH) interface that connects distributed remote radio unit (RRU) toward the centralized baseband processing unit (BBU). We first investigate the impacts among several factors, such as functional split, packetization and packet scheduling, on the Ethernet-bsaed FH transportation to increase multiplexing gain. Further, two implemented functional splits over the OpenAirInterface (OAI) platform are presented and compared in terms of several KPIs to justify the C-RAN applicability. We also present a model and an analytical framework for the E2E RAN service delivery to maximize the network spectral efficiency by considering multiple design factors. In the second part, we focus on the RAN slicing to not only provide different levels of isolation and sharing to each slice but also enable the customization across control plane (CP), user plane (UP), and control logic (CL). Hence, we propose a flexible execution environment, denoted as the RAN runtime slicing system, in order to (a) virtualize slice service instances over the underlying RAN modules, and to (b) abstract radio resource to increase the multiplexing gain. Additionally, a number of new interfaces are identified for the communications between the RAN runtime and the orchestration system in support of slice-based multi-service chain creation and chain placement, with an auto-scaling mechanism to increase the performance. Finally, the runtime software development kit (SDK) is on top of the RAN runtime introduced to facilitate the development of control applications. These control applications can compose sophisticated and customized control logics that can be chained across different domains and planes.