Recent penetration of SDR (Software defined radio) technology into mobile systems of new generation as well as increasing throughput demands in radio access network (RAN) are main development engines of new paradigm in radio access network world, better known as Cloud-Radio Access Network (C-RAN). This inovative architecture whose main proponent among telecom companies is China Mobile, should significantly decrease bussiness costs of Telcos, mainly on the long term basis, and also enable higher resource utilization as well as faster and more flexibile development of radio access networks following the IT concept of Cloud Computing. Although the architecture itself, applied to this field, is quite revolutionary compared to the present one, its realization would be based on optimal combination of existing technologies that would have to be adjusted to system requirements of, mainly, LTE and LTE advanced systems. Even though theoretically, reviewed architecture provides a number of improvements, for its wider acceptance and implementation, certain problems must be solved due to the current capabilities of SDR technology and optical infrastructure. This paper will present brief overview of pros and cons of this architecture as well as an estimate of further progress in this field. This paper will present a new overview of all known techniques to realize a system capable to support a C-RAN network. We explored all the external factors that affect the radio access network and we made our own conclusions.