Novel C-RAN Architecture with PON based Midhaul and Wireless Relay Fronthaul

Centralized radio access network (C-RAN) architecture prevails to efficiently forward the ever increasing mobile traffic towards beyond 5G era. Densely deployed radio units (RUs) compose small cells and an ultra high-density distributed antenna system (UHD-DAS). Distributed units (DUs) are placed close to RUs and linked to them via fronthaul to satisfy strict latency requirement. The DUs are connected to a central unit (CU) installed in a central office through optical midhaul links. Although it has been a hot research topic to compose a fronthaul network, there has been little research on the concept of midhaul networking. Therefore, this paper proposes the C-RAN architecture which consists of passive optical network (PON)-based midhaul links and wireless relay fronthaul networks. The goal of the proposed idea is to reduce fiber deployment cost by optical fiber reduction. We also propose a joint routing and dynamic wavelength and bandwidth allocation (DWBA) algorithm for optimally allocating resources considering the bandwidth utilization and the latency requirement. It is confirmed through computer simulations that the accommodation efficiency of optical midhaul can increase fourfold with the proposed scheme.