Buffer-Aided Cooperative Relays in Orbital Angular Momentum Based IoT Networks

Abstract

Orbital Angular Momentum (OAM) is an essential property of electromagnetic transmission. Nowadays, OAM is popular due to its capabilities to improve the electromagnetic spectrum efficiency which increases throughput. However, employing an OAM-based solution is costly as it suffers wave divergence mainly at high OAM orders (modes). This difficulty limits the distance range for successful communication link, particularly in wireless communication which is essential for realizing Internet of Things (IoT) applications. One of the available solutions to deal with this limitation is utilizing a cooperative relaying system. Relays are known for their potential to shorten the link connecting the source to the destination, as well as provide an alternative link to avoid deep fading. Nonetheless, conventional relaying technique (without buffers) are surpassed by adding buffering capabilities to relays, this enhances the system throughput. In this article, we suggest employing buffer-aided relays in OAM-based networks. Simulation trials show that the proposed buffer-aided relay solution assists the OAM-based network in obtaining higher throughput than its counterpart the traditional relays. The gain of using buffer-aided relays grows as the OAM-based networks become more restricted when they are transmitting at higher OAM orders. Furthermore, at higher thresholds, the rate of successful transmission goes down which degrades the system throughput. The results show that the buffer-aided relays outrun conventional relays at any threshold and the difference in performance becomes greater at more restricted higher thresholds. In addition, the buffer-aided relays help the OAM-based networks achieve lower outage probability than that achieved with traditional relays.