LatSeq: A Low-Impact Internal Latency Measurement Tool for OpenAirInterface

Amongst the appealing features of 5G, ultra low latency is perhaps the most attractive one, as it unleashes a wealth of disruptive services. However, meeting such a challenging goal requires a thorough understanding of latency in the 5G prevailing bottleneck, that is, the Base Station. For this purpose, we propose LatSeq, an open-source tool for fine-grained analysis of latency inside a software Base Station (BS), and implement it on the OpenAirInterface platform. LatSeq tackles each packet's sequence of successive delays across the layers of a Base Station, which reveals enlightening causal links. This paper discusses LatSeq's design choices and evaluates its fitness for purpose in a first baseline usage scenario. We demonstrate the low impact of LatSeq on the observed system, and the relevance of statistics based on individual packet tracing inside the base station.