Abstract
The emerging Cloud-Radio Access Network (RAN) architecture within the fifth generation (5G) of wireless networks plays a vital role in enabling higher flexibility and granularity. Cloud-RAN is able to scale and enhance network efficiency to support new features over the next several years by means of centralisation. In Cloud-RAN architecture, baseband functions are centrally deployed providing several benefits in terms of offering high level of cooperation between base stations and RAN sharing. These aspects allow dynamic reconfiguration of resources enabling to fulfil diverse requirements of various vertical industrial applications.Cloud-RAN significantly benefits from the emerging technologies such as softwarization and virtualisation. Softwarization/virtualisation within Cloud-RAN allows adaptive allocation of RAN functions between components of Cloud-RAN introducing the so-called flexible functional split. Flexible functional split is a promising approach aiming at providing greater flexibility to sufficiently fulfil diversified service requirements needed by 5G. However, selecting the appropriate functional split is an important factor.
On the other hand, flexible functional split enables the use of different types of the transport network. The Ethernet-based fronthaul can be an attractive solution for Cloud-RAN. On the one hand, deployment of Ethernet-based fronthaul enables Cloud-RAN to provide more diverse, flexible and cost-efficient solution. On the other hand, Ethernet-based fronthaul requires packetised communication, which imposes challenges in delivering stringent latency requirements between RAN functionalities. To this end, in this thesis, an implementation of Cloud-RAN with functional split over Ethernet-based fronthaul has been considered to benefit from versatility and flexibility provided by functional split and the use of commodity and low-cost industry standard equipment.
In the first part of the thesis, the feasibility of the Medium Access Control (MAC) and physical (PHY) split over the Ethernet-based fronthauling has been addressed. An implementation and deployment of hardaware-based Cloud-RAN has been developed and the impact of packetisation on the fronthaul has been evaluated.
In the second part, three alternatives of RAN function splits have been implemented on a hardware platform supporting Cloud-RAN with Ethernet-based fronthauling. The impact that each functional split have on the fronthaul in the delivery of 5G services has been identified through a system-level evaluation. Then, recommendation on the most appropriate split for a given 5G scenario has been proposed.In the third part, a solution to improve the performance of Ethernet-based fronthaul by means of multi-path diversity and erasure coding has been proposed. Under a probabilistic model that assumes a single service, the average latency required to obtain reliable fronthaul transport and the reliability-latency trade-off are first investigated. The analytical results are then validated and complemented by a numerical study that accounts for the heterogeneous service.In the last part, the proposal to improve reliability of the Ethernet-based fronthaul has been validated by evaluating the performance of the model in industry-garde testbed. Finally, the thesis is concluded with some future researches.
| Date of Award | 1 Mar 2021 |
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| Original language | English |
| Awarding Institution |
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| Supervisor | Toktam Mahmoodi (Supervisor) & Mischa Dohler (Supervisor) |