  Accurate and highly-granular channel capacity telemetry of the cellular last
hop is crucial for the effective operation of transport layer protocols and
cutting-edge applications, such as video on demand and videotelephony. This
paper presents the design, implementation, and experimental performance
evaluation of NG-Scope, the first such telemetry tool able to fuse
physical-layer channel occupancy readings from the cellular control channel
with higher-layer packet arrival statistics and make accurate capacity
estimates. NG-Scope handles the latest cellular innovations, such as when
multiple base stations aggregate their signals together to serve mobile users.
End-to-end experiments in a commercial cellular network demonstrate that
wireless capacity varies significantly with channel quality, mobility,
competing traffic within each cell, and the number of aggregated cells. Our
experiments demonstrate significantly improved cell load estimation accuracy,
missing the detection of less than 1% of data capacity overall, a reduction of
82% compared to OWL, the state-of-the-art in cellular monitoring. Further
experiments show that MobileInsight-based CLAW has a root-mean-squared capacity
error of 30.5 Mbit/s, which is 3.3x larger than NG-Scope (9.2 Mbit/s)
