NO Stack: A SDN-based Framework for Future Cellular Networks

Mobile traffic is growing exponentially and various kinds of traffic are emerging. It is hard to support new communication mechanisms in current cellular networks due to their inflexibility. And since link capacities are fairly close to the Shannon limit, further improvements seem to be expensive and will provide limited gains. As a result, people are working on redesigning cellular networks with the introduction of new technologies to meet these radical demands. Software Defined Networking (SDN) is an emerging technology and shows great success in wired IP networks. In this paper, we propose NO Stack (short for "Not Only Stack"), which is a SDN-based framework for future cellular networks. By adapting the SDN principles into cellular networks, NO Stack is abstracted into three layers: infrastructure layer, control layer and application layer. Three key technologies are introduced in NO Stack: C/U Plane separation, GNV (Global Network View), User Flow & Flow Table. The design principles for each technology are given based on a careful comparison between cellular networks and wired IP networks. We push down the vertically stacked protocol stack and encapsulate protocol layers as horizontally chained modules, which can be orchestrated by Network OS flexibly. Control plane is decoupled from user plane and redesigned carefully. A globally indexed, distributively stored and locally accessed GNV is first introduced in NO Stack. User Flow & Flow Table are described in details considering the characteristics of cellular networks. We believe NO Stack is sustainable, flexible, programmable and thus a promising framework for future cellular networks.