Competitive Broadcast against Adaptive Adversary in Multi-channel Radio Networks
share
Wireless networks are vulnerable to adversarial jamming due to the open nature of the communication medium. To thwart such malicious behavior, researchers have proposed resource competitive analysis. In this framework, sending, listening, or jamming on one channel for one time slot costs one unit of energy. The adversary can employ arbitrary jamming strategy to disrupt communication, but has a limited energy budget T. The honest nodes, on the other hand, aim to accomplish the distributed computing task in concern with a spending of o(T). In this paper, we focus on solving the broadcast problem, in which a single source node wants to disseminate a message to all other n-1 nodes. Previous work have shown, in single-hop single-channel scenario, each node can receive the message in Õ(T+n) time, while spending only Õ(√(T/n)+1) energy. If C channels are available, then the time complexity can be reduced by a factor of C, without increasing nodes' cost. However, these multi-channel algorithms only work for certain values of n and C, and can only tolerate an oblivious adversary. We develop two new resource competitive algorithms for the broadcast problem. They work for arbitrary n,C values, require minimal prior knowledge, and can tolerate a powerful adaptive adversary. In both algorithms, each node's runtime is dominated by the term O(T/C), and each node's energy cost is dominated by the term Õ(√(T/n)). The time complexity is asymptotically optimal, while the energy complexity is near optimal in some cases. We use "epidemic broadcast" to achieve time efficiency and resource competitiveness, and employ the coupling technique in the analysis to handle the adaptivity of the adversary. These tools might be of independent interest, and can potentially be applied in the design and analysis of other resource competitive algorithms.
READ FULL TEXT