Rethinking Service Chain Embedding for Cellular Network Slicing

5G is set out to address the business contexts of 2020 and beyond, by enabling new network and service capabilities. The industry consensus is that 5G will facilitate ubiquitous connectivity, seamlessly integrating wireless technologies and complementary communication networks, while operators will be capable of providing networks on a need-for-service basis. Furthermore, there is a need for operators to exploit new revenue sources and break the traditional business model of a single network infrastructure ownership, by supporting multi-tenancy. Network slicing can provide a solution towards this end; it is considered a key for meeting 5G's diverse requirements, including future-proof scalability and flexibility. Provisioning and management of network slices in the transition from Long Term Evolution (LTE) to the emerging 5G systems poses the need for the mapping of service chains that express traffic and processing requirements of LTE slices. In this respect, we follow a different approach to the service chain mapping problem, promoting virtualized network function (NF) sharing among multiple service chains that are associated with a certain network slice. Using mixed-integer linear programming formulations, we show that our approach leads to reduced NF state and management overhead, compared to the common resource allocation practice in virtualized Radio Access Networks.