Predicting Throughput Degradation in Wi-Fi 6 Networks Under Varying Channel Conditions: A Physical Layer Performance Model

Wi-Fi 6, standardized as IEEE 802.11ax, introduces orthogonal frequency-division multiple access (OFDMA), 1024-quadrature amplitude modulation (1024-QAM), uplink multi-user MIMO, and target wake time as the primary mechanisms for improving spectral efficiency and network capacity relative to its predecessors. However, the achievable throughput of 802.11ax networks is strongly dependent on the physical layer channel conditions under which these mechanisms operate, and the relationship between channel quality metrics available at the access point, including reference signal received power, signal-to-noise ratio, and channel capacity estimation, and the actual application-layer throughput delivered to associated stations is not straightforward due to the adaptive nature of the modulation and coding scheme selection process and the overhead structure of the 802.11ax frame format. This paper presents a physical layer performance model that predicts the throughput degradation of Wi-Fi 6 networks under varying channel conditions across the 2.4 GHz and 5 GHz operating bands. The model incorporates a multi-variable regression framework trained on physical layer measurements including received signal strength indication, signal-to-noise ratio, packet error rate, channel bandwidth utilization, and modulation and coding scheme distribution, collected from a testbed of 802.11ax access points and client stations operating under controlled channel conditions imposed by a programmable channel emulator. The model predicts MCS distribution and associated throughput with a mean absolute error of 1.8 Mb/s across the evaluated channel scenarios, representing a significant improvement over link adaptation table-based prediction approaches that do not account for channel impairments beyond SNR. The model is applied to predict throughput in scenarios representative of high-density IoT deployments, enterprise open-plan offices, and outdoor pointto-point links, providing a systematic basis for network planning and capacity optimization in WiFi 6 deployments.