A scalable architecture for handling control plane failures in heterogeneous networks

The separation between the control plane and the user plane is a key property of the newly proposed heterogeneous networks that will be widely deployed in 5G. In contrast to the failure of a small cell base station in the user plane which can be directly handled by the associated macrocell base station, the solution to handling a macrocell base station failure in the control plane is less investigated, in particular with regard to the signaling scalability issues of having all the affected small cell base stations directly communicate with the core network. In this article, we propose a small cell controller scheme for controlling and managing affected small cell base stations in a clustered fashion during the corresponding macrocell base station fail-over period. The advantage is to achieve substantial reduction of signaling overhead caused by user device handovers across small cell base station boundaries as compared to the existing solution, while maintaining comparable system performance. The proposed scheme is evaluated through realistic simulation studies and compared against the legacy scheme. The results clearly indicate that the proposed scheme can significantly reduce the signaling latency and processing load on the core network during the macrocell base station fail-over period.