For statistical evaluation, the drive test procedure is repeated several times on a number of well-known test routes.  Each test route allows the ATC team to analyze different settings, such as frequency of LTE band, network coverage, and carrier aggregation. These different test routes also allow ATC to investigate the AUT’s behavior in worst-case and best-case scenarios. For example, AUT’s tested in a good network coverage environment with the highest data throughput could suffer from link interruptions or low throughput in a bad network environment and vice versa. Under these circumstances, the complexity of analysis increases based on the huge amount of end-user key performance indicators (KPI) present in 4G networks which need to be considered. RSRP relates to the gain of the AUT at the antenna-level and must be analyzed, although its effects are included in some system metrics. For system performance, other KPIs have to be analyzed to get valuable test metrics.

Figure 2 shows throughput as a function of vehicle position on an urban test route in Hamburg, Germany. As expected, the results highlight that throughput constantly varies during drive tests as a result of the multipath and multi-user environment. However, the wide range of measured throughput is quite remarkable. For example, some areas highlighted in red/orange along the test route (<10 Mbit/s) have network coverage with up to 150 Mbit/s maximum data throughput. In contrast, the spot marked with a red ellipse has up to three Carriers in LTE band 3 & 7 available and thereby has a maximum data throughput of 475 Mbit/s. In this urban region ATC measured some samples with up to 130 Mbit/s data throughput, which is very high because data throughput is shared to all attached users.