Status updates through multicast networks

Abstract

Using age of information as the freshness metric, we examine a multicast network in which real-time status updates are generated by the source and sent to a group of n interested receivers. We show that in order to keep the information freshness at each receiver, the source should terminate the transmission of the current update and start sending a new update packet as soon as it receives the acknowledgements back from any k out of n nodes. As the source stopping threshold k increases, a node is more likely to get the latest generated update, but the age of the most recent update is more likely to become outdated. We derive the age minimized stopping threshold k that balances the likelihood of getting the latest update and the freshness of the latest update for shifted exponential link delay. Through numerical evaluations for different stopping strategies, we find that waiting for the acknowledgements from the earliest k out of n nodes leads to lower average age than waiting for a pre-selected group of k nodes. We also observe that a properly chosen threshold k can prevent information staleness for increasing number of nodes n in the multicast network.

Age of Information in Multicast Networks with Multiple Update Streams

“…, n}. Thus, in this section we extend the result from [16] to multiple update streams using the same multicast network.…”

“…When p 1 = 1, i.e., the source node generates only type I updates, ∆ I given in (12) reduces to the single stream result in [16,Theorem 2]. From the symmetry of the network model, the average age expression of type II update stream at an individual node, ∆ II , can be found upon definingȲ accordingly and replacing k 1 , p 1 and X k1:n with k 2 , p 2 and X k2:n in (12).…”

Age of Information for Multicast Transmission With Fixed and Random Deadlines in IoT Systems

“…If device n successfully receives the status update, then the instantaneous AoI is reset to T N (K) when Case C S,1 occurs. In this case, the first and second moments of T N (K) in (31) and (32) are presented in Corollary 1. Corollary 1.…”

“…Based on the aforementioned analysis, we obtain the average AoI and the average peak AoI of the multicast transmission with exponentially distributed deadlines by substituting (24), (25), (31), (32), (36), and (38) into (22) and (23), respectively.…”

Age of Information Scaling in Large Networks with Hierarchical Cooperation

“…In [28], opportunistic contacts between users are utilized to obtain an average age of O(log n) at the This work was supported by NSF Grants CNS 15-26608, CCF 17-13977 and ECCS 18-07348. users. In [29]- [32], single and multihop multicast networks are considered and O(1) average age is obtained at the end nodes by using special transmission schemes such as the earliest k transmission scheme in which the source node waits for delivery to the earliest k out of the total n receiver nodes. Reference [33] on the other hand studies age scaling in the multiaccess setting with massive number of source nodes.…”