  The radio access networks (RANs) need to support massive and diverse data
traffic with limited spectrum and energy. To cope with this challenge,
software-defined radio access network (SDRAN) architectures have been proposed
to renovate the RANs. However, current researches lack the design and
evaluation of network protocols. In this paper, we address this problem by
presenting the protocol design and evaluation of hyper-cellular networks
(HyCell), an SDRAN framework making base station (BS) operations globally
resource-optimized and energy-efficient (GREEN). Specifically, we first propose
a separation scheme to realize the decoupled air interface in HyCell. Then we
design a BS dispatching protocol which determines and assigns the optimal BS
for serving mobile users, and a BS sleeping protocol to improve the network
energy efficiency. Finally, we evaluate the proposed design in our HyCell
testbed. Our evaluation validates the feasibility of the proposed separation
scheme, demonstrates the effectiveness of BS dispatching, and shows great
potential in energy saving through BS sleeping control.
