Bundling Method of Periodically Generated Packets for Collision-Free Transmission by Uplink OFDMA in Wireless Sensor Networks.

In the recent Internet of Things (IoT) context, smart IoT environments such as smart factory ones must transfer periodically generated data packets as well as aperiodically generated ones with small loss rate. With Orthogonal Frequency-Division Multiple Access (OFDMA) transmission introduced in IEEE 802.11ax, multiple packets are transferred efficiently without collision. In this paper, focusing on the periodicity of the generation of periodic packets, we propose a method that repeatedly transfers periodic packets simultaneously by bundling them into OFDMA transmissions. Packets that are transferred simultaneously by an OFDMA transmission are determined so that total channel occupancy period is minimized based on mathematical analysis. Minimizing the channel occupancy period also contributes to alleviating collision among aperiodic packets because time ratio for transmitting them is increased. Through performance evaluation with computer simulation, we demonstrate the effectiveness of the proposed method.