An SDN-based virtual cell framework for enhancing the QoE in TD-LTE pico cells In this paper, we propose a Software Defined Network (SDN)-based framework for enhanced Quality of Experience (QoE) in the presence of Time Division-Long Term Evolution (TD-LTE) pico-cell hotspots. The proposed framework enables users to utilize radio-resources from multiple base stations and enhance their QoE, by utilizing the concept of virtual cells and by customizing the TD-LTE frame at the picocell stations. In this way, the proposed framework resolves pseudo-congestion and enables elastic radio-resource management while meeting the individual traffic requirements at the end users. The formation of virtual cells is driven by a QoE-centric approach that monitors whether the Mean-Opinion Score (MOS) of specific applications drops below a prescribed user-specific threshold. Accordingly, the TD-LTE frame is centrally optimized by an SDN Controller so as to meet the individual QoE requirements at the end users. System-level simulations demonstrate that the employment of the proposed framework leads to notable improvements in terms of MOS, end-to-end delay and packet loss rate, as compared to existing approaches with static and adaptive frame reconfiguration in TD-LTEpicocells.