Fluid-Limit Model for Dynamic MU-OFDMA Resource Allocation of Wi-Fi6 Networks

This letter analyses both static and dynamic resource allocation methodologies of the Multi-User Orthogonal Frequency Division Multiple Access (MU-OFDMA) feature of the Wi-Fi 6 network. In contrast to static MU-OFDMA, in the case of dynamic MU-OFDMA system, resource units (RUs) are allocated dynamically between the schedule and random access (RA) RUs based on the heterogeneous traffic requirements of the stations (STAs). In this letter, we first analyze the static MU-OFDMA system using the Fluid limit approach and derive the transmission probability of a STA in a time slot denoted as
$\tau $
as a function of the number of RA RUs (
$N_{RA}$
). Later the dynamic MU-OFDMA system is modeled as a Discrete-Time Markov Chain (DTMC) wherein the
$N_{RA}$
changes with every time slot. The DTMC is solved by using the parameter
$\tau $
as a function of
$N_{RA}$
that is derived previously using the Fluid limit approach. The trade-off between throughput and RA capability (rate of new users accessing the system) of a dynamic system is studied and validated against simulation.