Age-of-Information Optimization for NOMA-Assisted Wireless Backscatter Networks

In real-time applications requiring frequent status updates, the freshness of information, quantified by the age of information (AoI), is of utmost importance. This letter focuses on non-orthogonal multiple access (NOMA)-assisted wireless backscatter networks comprising freshness-sensitive and non-sensitive nodes. We formulate a joint optimization problem encompassing backscatter coefficient configuration, node matching, and time slot allocation. To solve this, we introduce a computationally efficient backscatter node matching algorithm. Our iterative approach optimizes backscatter coefficients and time slot allocation alternately to minimize the average AoI of freshness-sensitive nodes. Specifically, we transform the fractional programming problem into a linear one using quadratic transform and Taylor expansion. Dynamic time slot allocation is achieved by adjusting constraints. Simulations verify our algorithm’s effectiveness in selectively reducing the average AoI of critical nodes, ensuring high information freshness and timely status updates.