Age of Information of NOMA-Aided Grant-Free IoT Networks With Iterative Decoding

In this article, we investigate the age of information (AoI) of a wireless network employing an iterative decoding (ID) strategy with nonorthogonal multiple access (NOMA). The ID-NOMA protocol is based on the idea that packets successfully decoded at time slots inside the same frame may be employed to solve previous successive interference cancellation (SIC) collisions, contributing to enhancing the AoI of the system. To demonstrate the benefits of the proposed strategy, we compare ID-NOMA with orthogonal multiple access (OMA) and conventional NOMA. Numerical results show that the joint optimization of the number of slots per frame, transmit power, and transmission probability of each device per time slot are crucial to minimize the AoI. Furthermore, our results demonstrate that ID-NOMA outperforms OMA and conventional NOMA in terms of AoI in all scenarios considered, which demonstrates the benefits of the proposed protocol.