# A Comprehensive Worst Case Bounds Analysis of IEEE 802.15.7
## 2 Related Work  
There are already some works that analyze the performance of VLC networks in terms of delay and throughput. The authors in ref. [3] analyzed the carrier sensing multiple access with collision avoidance (CSMA/CA) mechanism of the IEEE 802.15.7. By relying upon Markov chain analysis, they derived the performance metrics for saturated traffic in a star topology network. The model was simulated over MATLAB and the authors studied metrics such as collision probability and transmission probability. Authors in ref. [4; 5] also carried out a performance analysis using a Markov chain model for saturated traffic in a star topology network. In accordance with the evaluation service time distribution, they propose a queuing model and analyze the resulting performance improvement. However, under these analyses the worst-case bounds of the network are not clearly defined. Defining the worst case bounds can help in the adaption of this technology in time-critical applications. Some simulation tools have also been proposed in the literature. Researchers in ref. [6] propose a Matlab simulation framework that partially implements the MAC sub-Layer of IEEE 802.15.7 along with the necessary primitives and frame structures. However, none of these models encompass the GTS mechanism, turning them unsuitable to analyze applications with strict timeliness requirements. Authors in ref. [7] used a network calculus model to analyze a broadcasting topology in order to determine its performance. They also carried out an experimental evaluation with OOK modulation on both the transmitter and receiver and evaluated the throughput for various transceiver distances. By encompassing frame synchronization based TDMA over their Network Calculus model, they concluded that it would be possible to support improved levels of QoS in VLC multichannel broadcasting. Some authors have also enhanced the existing characteristics of the IEEE 802.15.7 protocol. For instance, authors in ref. [8] proposed a priority-enabled MAC based upon multi-parameter tuning. Using the back-off times, back-off exponent and contention window of the CSMA/CA they support different priorities to enable a multilevel differentiatedservice. They analyze its performance in a Visible Personal Area Network (VPAN) context using a discrete Markov chain model. VLC have been gaining traction in several application domains such as vehicular networking, IoT and Wireless Body Area Networks. Researchers are taking a step forward in the domain of smart homes using applications like indoor presence detection systems using Optical Camera Communication (OCC) [9]. Researchers in ref. [10] use hybrid spatial phase-shift keying to support a communication architecture for vehicular systems. In these experiments they showcase an object detection algorithm for real-time region-of-interest tracking in city driving (at speeds around 30 km/h) and highway night driving (at a speeds >60 km/h) scenarios. It is to be noticed that visible light communications (VLC) channels are highly dynamic, very unpredictable, and subject to many noise sources. Researchers in ref. [11] propose a novel signal to noise ratio (SNR)-adaptive visible light communication receiver architecture aimed for automotive applications. They use an open loop signal processing technique that does a real-time SNR analysis. The receiver evaluates the SNR and re-configures its structural design in order to ensure a proper signal treatment, while providing an optimal trade-off between communication performances and computational resources usage. In this work, we propose a reconfiguration approach that will help improve the scalability of the network. The authors in ref. [12] argue that RF-based wireless communications are hardly suited to guarantee strict QoS requirements due to the limited bandwidth, severe interference, and multi-path reflections.