Hybridization of Ring and Mesh Topologies in Fifth Generation (5g) Small Cells for Energy Optimisation of Millimetre-Wave Backhaul

Abstract

Small cells are positioned as a complementary solution to the existing cellular infrastructure, rather than a complete replacement. However, densification of cells leads to an exponential rise in power consumption, especially in the backhaul segment connecting the small cells. Adopting mm Wave spectrum with a vast bandwidth for wireless backhaul links can provide multi-gigabit capacity through intelligent network design. Hence, the paper presents a hybrid backhaul architecture combining the reliability of ring topologies with the flexibility of mesh interconnects using mmWave technology. The methodology developed the hybrid ring-mesh (HRM) topology adaptation spanning the physical link and network layers. The optimisation problem formulation used a bio-inspired firefly algorithm and was embedded in MATLAB Simulink environment. The result showed that HRM topology has the highest throughput of 900Mbps and is fastest compared to Ring and Star topologies of 300Mbps and 500 Mbps, respectively. It maximises energy efficiency from 30Mbps/W and 50Mbps/W of Ring and Star topologies to 90Mbps/W and a latency of approximately 0.5ms. The study provides an alternative means for mm Wave backhauling of small cells as it maximises energy efficiency while ensuring stringent quality of service (QoS) and also offers considerable throughput and latency where there is few number of small cell base stations.