Baseband Unit Pool Planning for Cloud Radio Access Networks: An Approximation Algorithm

Cloud radio access networks (C-RANs) are proposed as promising architecture to improve the capacity and enhance the coverage of mobile communication systems. In this letter, we study the baseband unit (BBU) pools planning problem in the C-RAN, where we try to minimize the total deployment cost while satisfying the traffic demands of remote radio heads connected to the BBU pools, the processing capacity of each BBU pool, and the latency requirements of the C-RAN. Our problem formulation leads a mixed integer linear programming problem that is NP-hard. We introduce an approximation algorithm to address it efficiently. Numerical results show that our proposed algorithm performs much better than other heuristic ones that are popular to deal with such kind of optimization tasks. Moreover, our proposal also yields a performance guaranteed scheme for the BBU pools planning problem in the C-RAN.