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Resilient SDN based small cell backhaul networks using mmWave bands

Due to the tremendous increase in traffic demand, current mobile access and backhaul networks face a capacity problem. To increase the capacity, one can deploy many small cells, which may be dynamically powered on where traffic demand arises. As a consequence, the backhaul network for dense small cell deployments needs to cope with the massive increase in user demands but rolling out fiber to each small cell is economically not viable. Recently, mmWave based mobile backhaul networks have raised a lot of interest because of the large chunk of available spectrum in the 60 GHz, and 70/80 GHz band. However, due to the specific propagation characteristic of mmWave spectrum, such links may face frequent outage. In addition, a more flexible design of the backhaul network is desired in order to cope with the diversification of service requirements. In this paper, we propose a small cell backhaul network architecture which is based on the concept of Software Defined Networking. In order to cope with the dynamics of mmWave links, we propose that the SDN control plane calculates for each backhaul link a set of backup links. Using OpenFlow Fast Failover groups, a fast local repair of a mmWave backhaul link can be achieved leading to a resilient backhaul mesh architecture. An evaluation of our concept in a network emulator demonstrates the effectiveness of our approach. Particularly how it leads to lower packet loss and consequently higher throughput.