Average age of information for irregular repetition slotted ALOHA

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In this talk, we will discuss the average age of information (AAoI) performance of Irregular Repetition Slotted ALOHA (IRSA) which is a grant free access mechanism for massive machine type communication (mMTC). The mMTC paradigm has enabled the deployment of wide-area sensor networks with a very large number of sensors. Grant-free access mechanisms are useful in mMTC due to their low complexity and ability to scale to a large number of sensors. IRSA is a frame-based grant free channel access scheme which uses repeated transmissions of a data packet within a frame followed by successive interference cancellation at the base station to decode packets. The repetition of data packets in a frame is controlled by the choice of a repetition distribution. IRSA is known to achieve higher values of throughput compared to conventional random access methods. The AAoI is a relevant metric for evaluating the performance of a sensor network in which measurements about a process are transmitted over a channel to a base-station which remotely estimates the process. We consider AAoI performance of frame-based IRSA since AAoI is a more relevant metric for the use case outlined above. We present our results on the characterization of AAoI for IRSA for the cases where measurements are taken by a sensor either at the start of a frame or just before the first transmission of a packet. We also consider a successive interference cancellation scheme that is applied in every slot and characterize its AAoI performance. These characterizations of AAoI depend on the choice of the repetition distribution and we also present our results on the optimal choice of the repetition distribution to minimize the AAoI. The challenges in this optimization problem and the characterization of AAoI will also be discussed.

Vineeth B.S., IIST Thiruvananthapuram

Vineeth is an Assistant Professor at the Department of Avionics in the Indian Institute of Space Science and Technology, Thiruvananthapuram. He received his PhD from the Department of Electrical Communication Engineering, IISc and his B.Tech from the College of Engineering, Trivandrum. His research interests lies in the development and application of models and analytical tools for performance analysis and optimization of engineering systems.