Will SDN be part of 5G?

For many, this is no longer a valid question and the case is considered settled with SDN/NFV (Software Defined Networking/Network Function Virtualization) providing the inevitable innovation enablers solving many outstanding management issues regarding 5G. However, given the monumental task of softwarization of radio access network (RAN) while 5G is just around the corner and some companies have started unveiling their 5G equipment already, the concern is very realistic that we may only see some point solutions involving SDN technology instead of a fully SDN-enabled RAN. This survey paper identifies all important obstacles in the way and looks at the state of the art of the relevant solutions. This survey is different from the previous surveys on SDN-based RAN as it focuses on the salient problems and discusses solutions proposed within and outside SDN literature. Our main focus is on fronthaul, backward compatibility, supposedly disruptive nature of SDN deployment, business cases and monetization of SDN related upgrades, latency of general purpose processors (GPP), and additional security vulnerabilities, softwarization brings along to the RAN. We have also provided a summary of the architectural developments in SDN-based RAN landscape as not all work can be covered under the focused issues. This paper provides a comprehensive survey on the state of the art of SDN-based RAN and clearly points out the gaps in the technology.Comment: 33 pages, 10 figure

Joint Beamforming and Admission Control for Cache-Enabled Cloud-RAN with Limited Fronthaul Capacity

Caching is a promising solution for the cloud radio access network (Cloud-RAN) to mitigate the traffic load problem in the fronthaul links. Multiuser downlink beamforming plays an important role for efficient utilization of spectrum and transmission power while satisfying the user’s quality of service (QoS) requirements. When the number of users exceeds the serving capacity of the network, certain users will have to be dropped or re-scheduled. This is normally achieved by appropriate admission control mechanisms. Introducing local storage or cache at the remote radio heads (RRHs) where some popular contents are cached, we propose beamforming and admission control technique for cache-enabled Cloud-RAN in the downlink. This minimizes the total network cost including power and fronthaul cost while admitting as many users as possible. We formulate this multi-objective optimization problem as a single objective optimization problem. The original problem which is mixed-integer non-linear program (MINLP) is first co verted to the mixed-integer second order cone programming form (MISOCP). Branch and Bound (BnB) algorithm is then used to determine the optimal and suboptimal solutions. Simulation study has been conducted to assess the performance of both methods