Backhaul Provisioning for LTE-Advanced & Small Cells

This paper considers transport capacity provisioning in LTE-Advanced (release 10) heterogeneous networks. It builds on the detailed analyses in LTE release 8 homogenous macrocells networks presented in NGMN’s “Guidelines for LTE Backhaul Traffic Estimation”, and also in “Small Cell Backhaul Requirements”. These works showed that backhaul traffic per cell site can be characterised by a ‘busy time’ loaded figure and a ‘quiet time’ peak. Perhaps counter-intuitively, the highest data rates seen on a last mile backhaul link occur during the light loading conditions needed to achieve the ‘headline’ peak user data rates. When the whole network is busy, inter-cell interference and users with a range of signal qualities result in lower cell average throughput figures. For the LTE downlink, peak rates are around 4-6x the busy time mean. When provisioning transport for the ‘last mile’ to the base station, the peak can dominate. When provisioning for aggregates of several cells towards the core network, the busy time mean dominates.