On Optimal Network Topologies for Noise-Limited Wireless Mesh Networks with Delay Constraints

Network densification is seen as one viable solution to provide the ample capacity for urban 5G networks. One of the technical challenges in this development is how to provide sufficient backhaul connectivity to all the new small cell base stations that will be installed to new types of locations like lamp posts and bus stops. One potential solution is to use multi-hop millimeter wave backhaul with beamforming antennas. In such wireless backhaul networks, interference is usually a minor issue and the connectivity is limited mostly by high attenuation. At the same time, one of the major challenges with multihop wireless networks is to meet the 5G delay budget. Furthermore, in this kind of deployment scenario, the fragility of millimeter wave links should be considered and thus the network resiliency increased by adopting partial mesh network topology. In this paper, we will show that in these type of networks and with given constraints the backhaul network topology should favor low node degree (3–4) over low hop-count. Furthermore, we will show that the spatial scaling constraints in realistic network deployments limit the network growth rate as the network diameter increases. This fact is then shown to reduce the scaling penalty of partial mesh topologies compared to tree structured networks. We will analyze the effects of spatial constraints by using an incremental network deployment simulation model. The results will indicate that, in practice, partial mesh network topology can achieve similar worst case delay targets compared to tree structured networks and that it is possible to compensate the small differences in scaling properties with minimal increases in BH node density.