Cloud Radio Access Network (C-RAN) is a promising solution to meet the 5GGP requirements for 5G Networks. The C-RAN is based on the idea of splitting the conventional eNB into two parts: the Remote Radio Head (RRH) and the Base Band Unit (BBU). The RRH will be responsible for the RF transmission and it will be densified to enhance the capacity of the network and the quality of service in response to the ever-increasing high demand for the applications. The BBU will care about the computational processing. To reduce the installation and maintenance costs and to enable and improve advanced features of the network such as Coordinated Multi-Point (CoMP) and enhanced Inter-Cell Interference Coordination (e-ICIC), the RRHs should be pooled and grouped into clusters. Several RRHs will be assigned to one BBU which will break with the conventional one-to-one mapping. The Clustering task is considered to be an NP-Hard problem. This article surveys the literature on Clustering algorithms and techniques as they apply to C-RAN Architecture and evaluate the resulting configuration of BBU pools.