Graph-based dynamic frequency reuse in Cloud-RAN

This work aims to apply a new dynamic frequency reuse scheme based on fractional frequency reuse (FFR) in Cloud-RAN structure. FFR is one of the most efficient schemes to mitigate the inter-cell interference in OFDM system, while strict FFR in traditional cellular system is still facing some problems such as the inefficient use of spectrum. Cloud-RAN is a new network structure comprised of baseband units (BBU) and remote radio heads (RRH), which has the ability to reduce the energy costs of network. We use a graph coloring method to allocate spectrum resource among different cell zones depending on different traffic demands as well as avoiding the inter-cell interference. With the application of our proposed scheme based on Cloud-RAN structure, we can not only improve the spectrum utilization, but also reduce the energy consumption through reducing the working number of BBUs. The simulation results show clearly that our new scheme in Cloud-RAN structure can achieve higher throughput and energy efficiency compared with the strict FFR in traditional cellular system.