Abstract:

To mitigate the severe inter-tier interference and enhance limited cooperative gains resulting from the constrained and non-ideal transmissions between adjacent base stations in heterogeneous networks（HetNet），and solve the emerging problems including the complex delivery of control signaling and difficult convergence with the existing mobile cellular networks in cloud radio access networks（C-RAN），heterogeneous cloud radio access networks （H-CRAN）were proposed as the promising solution for the fifth generation radio access network. The core characteristics of H-CRAN are to combine the advantages of HetNet and C-RAN，decouple the control plane from C-RAN into the existing heterogeneous high power nodes（HPN），and deploy dense simple remote radio heads（RRH） to absorb huge traffic in some hot spots. The issues of system architectures，promising key techniques，and researching challenges were discussed.

Key words: heterogeneous cloud radio access network, the fifth generation mobile communication system, cloud radio access network, cloud computing