Cache-aware user association in backhaul-constrained small cell networks

International audienceAnticipating multimedia file requests via caching at the small cell base stations (SBSs) of a cellular network has emerged as a promising technique for optimizing the quality of service (QoS) of wireless user equipments (UEs). However, developing efficient caching strategies must properly account for specific small cell constraints, such as backhaul congestion and limited storage capacity. In this paper, we address the problem of devising a user-cell association, in which the SBSs exploit caching capabilities to overcome the backhaul capacity limitations and enhance the users' QoS. In the proposed approach, the SBSs individually decide on which UEs to service based on both content availability and on the data rates they can deliver, given the interference and backhaul capacity limitations. We formulate the problem as a one-to-many matching game between SBSs and UEs. To solve this game, we propose a distributed algorithm, based on the deferred acceptance scheme, that enables the players (i.e., UEs and SBSs) to self-organize into a stable matching, in a reasonable number of algorithm iterations. Simulation results show that the proposed cell association scheme yields significant gains, reaching up to 21% improvement compared to a traditional cell association techniques with no caching considerations

Load & Backhaul Aware Decoupled Downlink/Uplink Access in 5G Systems

Until the 4th Generation (4G) cellular 3GPP systems, a user equipment's (UE) cell association has been based on the downlink received power from the strongest base station. Recent work has shown that - with an increasing degree of heterogeneity in emerging 5G systems - such an approach is dramatically suboptimal, advocating for an independent association of the downlink and uplink where the downlink is served by the macro cell and the uplink by the nearest small cell. In this paper, we advance prior art by explicitly considering the cell-load as well as the available backhaul capacity during the association process. We introduce a novel association algorithm and prove its superiority w.r.t. prior art by means of simulations that are based on Vodafone's small cell trial network and employing a high resolution pathloss prediction and realistic user distributions. We also study the effect that different power control settings have on the performance of our algorithm.Comment: 6 pages, 6 figures. Submitted to the IEEE International Conference on Communications (ICC 2015

In-Network Caching and Content Placement in Cooperative Small Cell Networks

International audience—Anticipating multimedia file requests via caching at the small cell base stations (SBSs) has emerged as a promising technique for enhancing the quality-of-service (QoS) of cellular user equipments (UEs). Nevertheless, in traditional caching approaches, files are retrieved from evolved packet core (EPC) of the network, and without coordination among SBSs, which introduces new challenges of content duplication and unbalanced traffic load on the backhaul. In this paper, we propose a collaborative framework in which the SBSs can access files from the caches of other SBSs within the same network domain (i.e., connected to the same service gateway). We design a cost model for the content retrieval of contents across SBSs and from the EPC, and we propose a cost-aware decentralized algorithm, based on which the SBSs devise individual caching strategies (i.e., which files to cache, and from where). Simulation results show that the proposed cooperative caching scheme yields significant gains in terms of in-network content availability, reaching up to 21% improvement compared to a traditional approaches based on geographical distribution of the UEs