Energy-efficient dynamic point selection for cloud radio access networks (C-RAN)

For next generation wireless communications, Cloud-RAN (C-RAN) has become an emerging network architecture of mobile communications, which separates computation entities-Baseband Units (BBUs) from original base stations (BSs), and puts BBUs in the cloud then forms a centralized network architecture. With C-RAN architecture, user equipments (UEs) can receive data from multiple collaborative cells and thus can leverage dynamic point selection (DPS) technology to improve network efficiency. Note that since the UEs are powered by batteries, energy saving is always a critical issue under C-RAN architecture. In current standard of 3GPP LTE-A, it has defined Discontinuous Reception (DRX) mechanism to allow UEs to turn off their radio interfaces and go to sleep to save energy. However, how to save UEs' energy under DPS in C-RAN is still an open issue. Therefore, this paper addresses the resource allocation problem by asking how to optimize the energy conservation of UEs based on DRX while serving UEs as more as possible under the consideration of UEs' quality of service (QoS) in C-RAN with DPS. To solve this problem, we propose an energy-efficient DPS (EE-DPS) scheduling scheme. The key idea of our scheme is to serve the UEs in the intersection of cells continuously and allocate resource tightly to avoid additional wake-up intervals. Extensive simulation results show that our scheme can serve most number of UEs while achieving high throughput as well as lower energy consumption, compared to the existing schemes.