Towards a service-oriented dynamic TDD for 5G networks

Abstract

The emerging 5G networks should accommodate a plethora of heterogeneous services with diverse Service Level Agreements, such as Internet of Things, location and social applications and multimedia. Dynamic Time Division Duplex (TDD) networks have the potential to support asymmetric services providing resource flexibility especially for small data applications and for social applications with interchanging uplink (UL) and downlink (DL) demands. TDD networks can leverage the benefits of network programmability via the means of the Software-Defined Network (SDN) paradigm that enables a logically centralized control plane capable of delivering efficient, optimized and flexible network resource management matching specific application UL and DL traffic requirements. This chapter describes the main mechanisms and components for evolving TDD networks toward 5G. In particular, it provides an overview of various dynamic TDD proposals, before elaborating the concept of TDD virtual cells, which allows users residing at the cell edge to utilize resources from multiple base stations forming a customized TDD frame. The adoption of SDN for programming the network resources and frame (re)configuration of TDD virtual cells follows, elaborating the SDN architecture, the resource programmability logic and the resource sharing in heterogeneous environments considering Frequency Division Duplex macros and TDD small cells. The adoption of SDN for enabling a TDD-specific network slice framework is described next, allowing a different TDD frame configuration to be employed within a certain amount of isolated resources, enhancing in this way the network utilization while optimizing the application perceived performance. Finally, some further considerations and challenges are analyzed considering the adoption of TDD in future 5G networks.