LTE Ground-to-Air Field Measurements in the Context of Flying Relays

Abstract

As future mobile networks move rapidly to 5G, ubiquitous network coverage (even in remote areas), temporary capacity enhancement, and network failure backup are still open issues. The recent advances in unmanned aerial vehicles technology have turned the attention of researchers and the industry toward utilizing flying nodes in 5G cellular. One or more UAVs could act as flying network nodes, extending the network coverage or enhancing system capacity, on demand, fast, accurately, and, most important, at low cost. This article presents field measurements, taken with a UAV connected to the existing LTE network of a mid-sized town, and analyzes the data. The goal of the measurement campaign is to monitor the LTE signals in a range of different altitudes under reallife conditions. Results show that at 60 m to 100 m above ground, the LTE coverage probability climbs to 90 percent and the received power gains ∼18 dB with respect to the ground level. On the other hand, the SIR tends to drop at higher altitudes, but the reduction is limited to 1-2 dB, avoiding the risk of service outage.