How Robust are Timely Gossip Networks to Jamming Attacks?
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We consider a semantics-aware communication system, where timeliness is the semantic measure, with a source which maintains the most current version of a file, and a network of n user nodes with the goal to acquire the latest version of the file. The source gets updated with newer file versions as a point process, and forwards them to the user nodes, which further forward them to their neighbors using a memoryless gossip protocol. We study the average version age of the network in the presence of ñ jammers that disrupt inter-node communications, for the connectivity-constrained ring topology and the connectivity-rich fully connected topology. For the ring topology, we construct an alternate system model of mini-rings and prove that the version age of the original model can be sandwiched between constant multiples of the version age of the alternate model. We show in a ring network that when the number of jammers scales as a fractional power of the network size, i.e., ñ= cn^α, the version age scales as √(n) when α < 1/2, and as n^α when α≥1/2. As version age of a ring network without any jammers scales as √(n), our result implies that version age with gossiping is robust against upto √(n) jammers in a ring network. We then study the connectivity-rich fully connected topology, where we derive a greedy approach to place ñ jammers to maximize age of the resultant network, which uses jammers to isolate as many nodes as possible, thereby consolidating all links into a single mini-fully connected network. We show in this network that version age scales as logn when ñ=cnlogn and as n^α-1, 1<α≤2 when ñ=cn^α, implying the network is robust against nlogn jammers, since the age in a fully connected network without jammers scales as logn.
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