Bounding Mobile Latency from Network Interconnections
Shefalit Tushar Kulkarni and John Heidemann
Citation
Shefalit Tushar Kulkarni and John Heidemann. Bounding Mobile Latency from Network Interconnections. "Proceedings of the " # "acm-aintec" (Taipai, Taiwan, Dec. 2026), to appear. [DOI] [PDF] [alt PDF]
Abstract
Mobile latency is determined by how Mobile Network Operators (MNOs) route traffic: from phones, across the MNO’s network to exit-points where it enters the public Internet. Exit-points are few, and MNOs are quiet about details, but their role prompts us to ask: What is the latency cost to send traffic through an exit-point? We develop a new method to evaluate this question, and demonstrate it on the three largest U.S. MNOs, although in principle it can apply globally. Using new analysis of existing traceroutes we find that AT&T, T-Mobile, and Verizon funnel nationwide traffic through only 9, 5, and 9 exits, and the geographic detour they incur adds up to 62.1 ms compared to an ideal, direct-path latency. We show that even assuming speed-of-light paths through the exit-points, latency is still up to 46.9 ms more than optimal. To understand if these costs can be overcome we compare actual to theoretically optimal placements, finding that latency of current placements are 18–66% above the population-weighted optimum and 32–72% above the market-share-weighted with the same number of exits. However, we show this gap is small in absolute terms: perfect placement would recover only a few milliseconds of the tens that remain. We show that geographic optimization saves little latency: the inflation users experience comes from routing and other overhead.Bibtex Citation
@inproceedings{Kulkarni26a,
author = {Kulkarni, Shefalit Tushar and Heidemann, John},
title = {Bounding Mobile Latency from Network Interconnections},
booktitle = "Proceedings of the " # acm-aintec,
month = dec,
year = {2026},
sortdate = {2026-12-01},
project = {ant, sabres, teppit, bripod},
jsubject = {network_topology},
jlocation = {johnh: pafile},
pages = {to appear},
publisher = {ACM},
address = {Taipai, Taiwan},
keywords = {5g, mobile networks, exit points, shiptraceroute, northeastern},
url = {https://ant.isi.edu/%7ejohnh/PAPERS/Kulkarni26a.html},
pdfurl = {https://ant.isi.edu/%7ejohnh/PAPERS/Kulkarni26a.pdf},
xblogurl = {https://ant.isi.edu/blog/?p=tbd},
doi = {https://dx.doi.org/10.1145/3858062.3858394}
}