  Mesh connectivity is attractive for Internet-of- Things (IoT) applications
from various perspectives. The recent Bluetooth mesh specification provides a
full-stack mesh networking solution, potentially for thousands of nodes.
Although Bluetooth mesh has been adopted for various IoT applications, its
performance aspects are not extensively investigated in literature. This paper
provides an experimental evaluation of Bluetooth mesh (using Nordic nRF52840
devices) with an emphasis on those aspects which are not well-investigated in
literature. Such aspects include evaluation of unicast and group modes,
performance under different traffic patterns, impact of message segmentation,
and most importantly, latency performance for perfect reliability. The paper
also investigates performance enhancement of Bluetooth mesh based on different
techniques including parametric adjustments, extended advertisements
(introduced in Bluetooth 5.0), power control, and customized relaying. Results
provide insights into system-level performance of Bluetooth mesh while
clarifying various important issues identified in recent studies.
