Creative Commons Attribution 4.0 International license
The broadcast problem is the task of disseminating a message from a single source node to all other nodes in a distributed system, ensuring that every node eventually receives the message despite possible network constraints such as delays, failures, or limited topology knowledge. In this work, we consider the broadcast problem in anonymous, synchronous, dynamic networks. A dynamic network is a network, whose topology changes over time, meaning that communication links can unpredictably appear and disappear. We present a randomized algorithm requiring O(log log n) bits of storage per node and terminating in O(m log n) rounds with high probability. It solves broadcast with stabilizing termination for anonymous, synchronous, 1-interval-connected networks using messages of size O(1). The algorithm is a non-idle-start algorithm. The best known idle-start algorithm for this problem requires O(log n) space, also a lower memory bound of ω(1) space is known. Our contribution affirmatively answers a question of Parzych and Daymude (DISC 2024). We also extend this result to dynamic networks with bounded connectivity time. Furthermore, we prove that for two variants of the broadcast problem in this setting no randomized algorithms exist.
@InProceedings{turau:LIPIcs.SAND.2026.6,
author = {Turau, Volker},
title = {{Broadcasts in Anonymous, Dynamic Networks: A New Algorithm and Impossibility Results}},
booktitle = {5th Symposium on Algorithmic Foundations of Dynamic Networks (SAND 2026)},
pages = {6:1--6:17},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-427-7},
ISSN = {1868-8969},
year = {2026},
volume = {373},
editor = {Mertzios, George B. and Richa, Andr\'{e}a W.},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SAND.2026.6},
URN = {urn:nbn:de:0030-drops-262408},
doi = {10.4230/LIPIcs.SAND.2026.6},
annote = {Keywords: Distributed algorithms, dynamic networks, randomized algorithms, impossibility results}
}