Multi-Tenant Radio Access Network Slicing: Statistical Multiplexing of Spatial Loads

This paper addresses the slicing of radio access network resources by multiple tenants, e.g., virtual wireless operators and service providers. We consider a criterion for dynamic resource allocation amongst tenants, based on a weighted proportionally fair objective, which achieves desirable fairness/protection across the network slices of the different tenants and their associated users. Several key properties are established, including: the Pareto-optimality of user association to base stations, the fair allocation of base stations' resources, and the gains resulting from dynamic resource sharing across slices, both in terms of utility gains and capacity savings. We then address algorithmic and practical challenges in realizing the proposed criterion. We show that the objective is NP-hard, making an exact solution impractical, and design a distributed semi-online algorithm, which meets performance guarantees in equilibrium and can be shown to quickly converge to a region around the equilibrium point. Building on this algorithm, we devise a practical approach with limited computational information and handoff overheads. We use detailed simulations to show that our approach is indeed near-optimal and provides substantial gains both to tenants (in terms of capacity savings) and end users (in terms of improved performance).

I. Introduction

Driven by the capacity requirements forecasted for future mobile networks as well as the decreasing margins obtained by operators, infrastructure sharing has established itself as a key business model for mobile operators to reduce the deployment and operational costs of their networks (e.g., [1] reports a 280% increase in deals within the last 5 years). While passive and active sharing solutions, ranging from exclusive allocation of resources to roaming agreements, are used and have been standardized, these sharing approaches are based on fixed contractual agreements with Mobile Virtual Network Operators (MVNO) over long time periods (typically on a monthly/yearly basis). In this paper, we focus on a structured dynamic slicing approach which enables a much more efficient sharing of network resources, as envisioned by the 3GPP Network Sharing Enhancements for future mobile networks which the authors contributed to [2]. Following [3], our approach divides the infrastructure into network slices, assigning a different slice to each operator, and implements the sharing of network resources among operators by dynamically allocating resources to slices. Such a novel network slicing approach is expected to result in new business models and revenue sources for infrastructure providers (see, e.g., [3]). Indeed, this approach supports not only classical players (mobile operators) but also new ones such as Over-The-Top (OTT) service providers that may buy a slice of the network to ensure satisfactory service to their users (e.g., Amazon Kindle’s support for downloading content or a pay TV channel including a premium subscription). In the literature, the term tenants is often used to refer to the different types of players, and multi-tenancy refers to approaches enabling dynamic network slicing and resource sharing for multiple tenants. For simplicity, hereafter we use the term operator in a broad sense to refer to classical (virtual) operators as well as the new players enabled by this approach.