  The fifth generation new radio (5G NR) technology is expected to fulfill
reliable and accurate positioning requirements of industry use cases, such as
autonomous robots, connected vehicles, and future factories. Starting from
Third Generation Partnership Project (3GPP) Release-16, several enhanced
positioning solutions are featured in the 5G standards, including the
multi-cell round trip time (multi-RTT) method. This work presents a novel
framework to estimate the round-trip time (RTT) between a user equipment (UE)
and a base station (gNB) in 5G NR. Unlike the existing scheme in the standards,
RTT can be estimated without the need to send timing measurements from both the
gNB and UE to a central node. The proposed method relies on obtaining multiple
coherent uplink wide-band channel measurements at the gNB by circumventing the
timing advance control loops and the clock drift. The performance is evaluated
through experiments leveraging a real world 5G testbed based on
OpenAirInterface (OAI). Under a moderate system bandwidth of 40MHz, the
experimental results show meter level range accuracy even in low
signal-to-noise ratio (SNR) conditions.
