Impact of mounting structures twists and sways on point-to-point millimeter-wave backhaul links

This paper investigates an impact of twists and sways of mounting structures on the performance of point-topoint millimeter-wave backhaul links. Characteristics of twists and sways are studied by experimental measurements performed on different telecom infrastructure sites and municipal sites considered for small cells installations. The measurements are done in four cities in Russia and Finland in the period from June to November 2014. Statistical distributions of the twists and sways amplitudes are derived from the experimental data and applied for analysis of the impact that such deflections may have on performance of the millimeter-wave links. An enhanced approach for channel availability estimation is proposed where two statistical parameters are involved as random channel attenuation values: rain absorption and losses caused by antenna deflections due to twists and sways. To illustrate the practical usefulness of the approach, link gain degradations and channel availabilities are calculated for several practical scenarios. For example, it is found that for 2⁰ beamwidth antennas and realistic sways of typical thin lamp poles available in most cities, the received power level may decrease from 2 dB and up to 20 dB. That gives essentially different results for the link distance prediction relative to the case when the twists and sways effects are not taken into account.