Age of Information in Short Packet Multi-Connectivity Links

In this paper, we investigate multi-connectivity (MC) schemes in the context of status update systems with short payloads. As a performance metric, we use the age of information (AoI). Due to short payloads, transmission errors must be taken into account. In addition to the well-known schemes of packet duplication, message splitting, and multiplexing, we propose a codeword splitting scheme, where each status update is jointly encoded across multiple channels. We derive closed-form expressions of the average AoI for the different schemes and optimize their corresponding parameters, such as blocklengths, message splits, and the cyclic schedule for the multiplexing scheme. Analytical comparisons and numerical evaluations show that the codeword splitting scheme achieves the lowest average AoI when joint encoding and decoding are possible. In scenarios where joint encoding is not feasible, whether message splitting or multiplexing results in a lower average AoI depends on the specific parameters.