Colony-RAN architecture for future cellular network

Abstract

Mobile data traffic has been increasing at a rapid pace over the past few years due to the rise of both smartphones and tablets. To accommodate such a huge traffic volume in cellular systems, it is imperative to reduce cell size to increase system capacity. To reduce cell size, the main issue confronting mobile network operators is system cost to provide coverage areas with small cells. Therefore, we propose a suitable RAN architecture for deploying small cells. First, a base band is physically separated into one baseband unit (BBU) and remote radio heads (RRHs). The BBUs are centralized in some locations. One BBU can connect to one or more RRHs. Such a network architecture, which we call Colony-RAN due to its ability to flexibly change cell layout, can dynamically change the connections of BBUs and RRHs in respect to traffic demand. As a result, because traffic distribution is non-uniform, Colony-RAN can drastically reduce the number of BBUs due to the statistical multiplexing effect. As a rough estimation based on the population of the Tokyo metropolitan area, we confirmed that the number of BBUs can be reduced by 75% with the co-located BBU and RRHs compared with conventional cellular systems. Another characteristic of Colony-RAN is its ability to reduce inter-cell interference and increase link quality by accommodating several RRHs in the same BBU taking user mobility and/or user distributions into consideration.