Mojan Wegener | Searcharxiv

arXiv2026

Open-Loop Transmission with Discrete Blocklengths: Characterization of AoI-Optimal Schedules

In this paper, we consider a general status update system, consisting of a source at which a physical process is monitored and a receiver. For transmission of status updates, a discrete set of blocklength error probability tuples is available. A typical example is a communication system with a fixed set of modulation and coding schemes. We assume that no feedback channel for acknowledgments exists and thus investigate the problem of constructing deterministic schedules for the status updating system. The average Age of Information (AoI) and average exponential AoI are appropriate performance metrics to capture the freshness of information. Interestingly, a static blocklength is shown to be suboptimal in general. While for the average AoI the gains that can be achieved by using a non-trivial periodic schedule are relatively small, they are significant for the average exponential AoI. Motivated by this, we prove conditions for single-blocklength optimality when two blocklengths are available. To achieve this, we use a Dinkelbach-like approach to reformulate the problem as an infinite-state transient average-cost Markov Decision Process and apply careful bounding techniques to derive the optimality conditions. As a converse, we analyze stationary randomized policies to certify the parameter regions where a non-trivial deterministic schedule outperforms the best constant schedule. Extensions to the case with more than two transmission lengths are provided. Numerical results show that the derived conditions cover a large portion of the parameter space and suggest that the optimality conditions for a constant schedule with the shorter blocklength, while sufficient, may also be necessary. As an example, we apply the results to the problem of age-optimal transmission with a small LDPC codebook, which illustrates the practical applicability.

cs.IT↗

arXiv2025

Age of Information in Short Packet Multi-Connectivity Links

In this paper, we investigate multi-connectivity schemes in the context of status update systems with short payloads. As the 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 for the average AoI for the different schemes and optimize their corresponding parameters. We show that the AoI of the multiplexing scheme is a convex function in the offset parameters and use this result to prove that for homogeneous channels, the multiplexing scheme outperforms the packet duplication scheme, which is outperformed by the codeword splitting scheme. Analytical comparisons and numerical evaluations show that the codeword splitting scheme achieves the lowest average AoI when joint coding is feasible. In scenarios where joint coding is not feasible, whether message splitting or multiplexing results in a lower average AoI depends on the specific parameters.

cs.IT↗