From network sharing to multi-tenancy: The 5G network slice broker.

The ever-increasing traffic demand is pushing network operators to find new cost-efficient solutions toward the deployment of future 5G mobile networks. The network sharing paradigm was explored in the past and partially deployed. Nowadays, advanced mobile network multi-tenancy approaches are increasingly gaining momentum, paving the way toward further decreasing capital expenditure and operational expenditure (CAPEX/OPEX) costs, while enabling new business opportunities. This article provides an overview of the 3GPP standard evolution from network sharing principles, mechanisms, and architectures to future on-demand multi-tenant systems. In particular, it introduces the concept of the 5G Network Slice Broker in 5G systems, which enables mobile virtual network operators, over-the-top providers, and industry vertical market players to request and lease resources from infrastructure providers dynamically via signaling means. Finally, it reviews the latest standardization efforts, considering remaining open issues for enabling advanced network slicing solutions, taking into account the allocation of virtualized network functions based on ETSI NFV, the introduction of shared network functions, and flexible service chaining.