Challenges of designing jointly the backhaul and radio access network in a cloud-based mobile network

In this work, we give an overview of the main challenges that must be tackled to perform a joint design of the backhaul and radio access network in a cloud-based mobile network. The deployment of a very dense network based on small cells connected through a heterogeneous backhaul is a realistic way of achieving a high throughput in a mobile network. But, the non-ideal characteristics of this backhaul and the blurring borders between access and the backhaul networks require a joint design of both, involving the three lower OSI layers. In the physical layer, we consider to use adaptable techniques including In-Network-Processing (INP) and Multi-Point Turbo Detection, as well as Coordinated Beamforming and Joint Network-Channel Coding. Regarding the MAC layer, we pay special attention to partly distributed algorithms operating on smaller time-scales that take into account backhaul constraints and inter-cell interference. Finally, in the network layer we propose the use of cooperative routing schemes that optimize the cell load distribution and admission and congestion control algorithms that use access and backhaul information. Based on these approaches, a joint design of access and backhaul network can be effectively carried out, in order to enable the deployment of small-cells and heterogeneous backhaul.