An Energy-Saving BBU-RRH Reconfiguration Scheme for Cloud Radio Access Networks

• Main Authors: Kuang-Wei Su, 蘇光威
• Other Authors: Tong-Ying Juang
• Format: Others
• Language: en_US
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/59973619318478654096

碩士 === 國立臺北大學 === 資訊工程學系 === 102 === Energy saving is an important issue in cloud radio access networks (C-RAN). Existing energy-saving scheme in C-RAN saves energy by turning off the base band unit (BBU) whose utilization ratio is lower than the threshold. However, the low utilization ratio does not indicate that the BBU is not energy efficient. To improve existing works, an energy-saving scheme which saves energy by turning off the BBU whose energy consumption ratio (ECR) is higher than the threshold. ECR is defined as the total power consumption divided by the total number of occupied physical resource block (PRB) subframes. The High ECR indicates the low energy efficiency. When all the radio heads (RRHs) of the BBU with high ECR is reassigned to other BBUs with low ECR, the BBU with high ECR can be turned off. The BBU-RRH reconfiguration is achieved by a greedy approach. The BBU with the highest ECR is reconfigured first that the RRH of this BBU with the highest ECR is reassigned to the nearest BBU with the lowest ECR. The process proceeds until all the BBUs with high ECR have been reconfigured and turned off. To avoid the ping-pong effect, an estimation scheme of the ECR of the BBUs is proposed so that the RRHs will not be reassigned back and forth. Simulation results justify the energy efficiency of the proposed scheme.