Cell network architectures confront enormous challenges due to the unusual rise in mobile data traffic usage, thus reducing spectrum accessibility and heavy power consumption. Research communities are looking for breakthroughs in the development of advanced infrastructure networks to meet increased consumer demand and, at the same time, to reduce network operators' capital and operational costs. Cloud Radio Access Network (Cloud-RAN) architecture is a recently proposed solution for wireless networks and is considered a strong candidate for potential 5G cellular coverage worldwide. This paper presents a literature survey on Cloud-RAN architectures toward Green 5G wireless communication systems and highlights Cloud-RAN benefits and limitations. Furthermore, this paper discusses Cloud-RAN's potential enhancement techniques, including robust beamforming, multiple-input-multiple-output (MIMO) with non-orthogonal multiple access (NOMA) cooperative scheme, massive MIMO, mmWave communication, clustering techniques, coalition formation, energy harvesting and reinforcement learning output.
