Slotted Aloha With Capture for OWC-Based IoT: Finite Block-Length Performance Analysis

In this paper, we analyze the throughput and reliability of an indoor optical wireless communication (OWC)-based Internet of Things (IoT) system based on Slotted ALOHA (SA) where IoT devices exchange data with an access point (AP). Assuming that the OWC receiver at the AP exploits the capture effect, we derive the error probability of decoding a short-length data packet that originates from a randomly selected OWC IoT device in the presence of interfering users. The analysis is based on the derivation of the signal-to-interference-plus-noise-ratio (SINR) statistics and the application of the finite block-length (FBL) information theory. Using these analytical results, we derive relevant performance parameters such as the system throughput and reliability expressed in terms of the outage probability of a user transmission. The main trade-offs between the system performance and the OWC system setup parameters are investigated, in particular, by stressing how the indoor OWC-based system geometry plays an important role in the system performance.Using extensive numerical results, we clearly describe how the presented results are used to optimize the SA-based indoor OWC IoT system design.