Match to cache: Joint user association and backhaul allocation in cache-aware small cell networks

Francesco Pantisano (1) , Mehdi Bennis (2) , Walid Saad (3) , Mérouane Debbah (4, 5)

1 JRC - European Commission - Joint Research Centre [Ispra]
2 CWC - Centre for Wireless Communications [University of Oulu]
3 Virginia Polytechnic Institute and State University Bradley Department of Electrical and Computer Engineering
4 LANEAS - Large Networks and Systems Group
5 Mathematical and Algorithmic Sciences Lab [Paris]

Caching multimedia files at the network edge has been identified as a key technology for enhancing users' quality-of-service (QoS), while reducing redundant transmissions over capacity-constrained backhauls. Nevertheless, in small cell networks , the efficiency of a caching policy depends on the ability of small base stations (SBSs) to anticipate the requests from the user equipments (UEs). In this paper, we propose a collaborative filtering (CF) scheme for estimating the required backhaul usage at each SBS, by mining the cacheability of UEs' file requests. In the proposed approach, each SBS has a twofold objective: update the bandwidth allocation based on the estimated backhaul utilization, and, given the current bandwidth availability, identify which UEs to service. We formulate the problem as a one-to many matching game between SBSs and UEs, and we propose a novel cache-aware user association algorithm that minimizes the backhaul usage at each SBS, subject to individual QoS requirements. Simulation results, based on real-world service request logs, have shown that the proposed CF-based solution can yield significant gains in terms of backhaul efficiency and cache hit-ratio, reaching up to 25%, with a maximum gap of 9% to an optimal cache-aware association technique. I. INTRODUCTION The exponential growth in the demand for high data rates and quality-of-service (QoS) in wireless cellular networks has led to the introduction of ultra-dense architectures, based on the concept of small base stations (SBSs), such as picocells or femtocells. SBS deployments promise to deliver high QoS, at low operational costs [1], yet, in order to reap those benefits, a number of technical challenges stemming from the backhaul capacity limitations must be addressed [2]. In fact, due to high SBS network density, efficient and scalable backhaul management solutions are essential to harness traffic bottlenecks and deliver the desired performance. To overcome the backhaul capacity limitations, state-of-the-art SBS architectures propose local caching of popular contents at SBS level, in order to reduce the overall traffic load from the core network and, thus, utilize the backhaul bandwidth more efficiently. Caching has been originally proposed in content distribution networks for decentralizing the availability of contents at strategic nodes of the network (e.g., proxy servers, gateways), while balancing the network traffic during off-peak intervals [3–5]. In essence, by decoupling the time instant during which a content is downloaded, from the one during which it is delivered to a UE, an SBS can boost the users' QoS and make a more efficient use of the backhaul resources.

Domaines: Mathématiques [math]; Sciences de l'ingénieur [physics]; Statistiques [stat]

Francesco Pantisano, Mehdi Bennis, Walid Saad, Mérouane Debbah. Match to cache: Joint user association and backhaul allocation in cache-aware small cell networks. IEEE International Conference on Communications (ICC), Jun 2015, London, United Kingdom. ⟨10.1109/ICC.2015.7248797⟩. ⟨hal-01242448⟩