Vertical Antenna Tilt Optimization for LTE Base Stations

An optimal vertical antenna tilt in a wireless access network plays a key role for coverage and capacity in the system. The autonomous (re-)optimization of tilts bears a large saving potential for operators as manual intervention is particularly costly. In this paper, we present a heuristic variant of the gradient ascent method to continuously optimize antenna tilts with quick convergence. We show that the average spectral efficiency in the system increases by 10% and that the spectral efficiency at the cell edge (5% quantile) increases by 100% after optimization. Changing conditions during the operational phase of the network, as for instance cell outage, can successfully be detected and compensated by an autonomous re-optimization.