Multi-Link Operation in Heterogeneous Wi-Fi 7 Networks: Modeling and Throughput Optimization

Multi-link operation (MLO) is regarded as one of the most disruptive features in the upcoming IEEE 802.11be standard, known as Wi-Fi 7. However, the performance characterization of heterogeneous multi-link IEEE 802.11be networks, which consist of Multi-Link Devices (MLDs) and legacy Single-Link Devices (SLDs), remains largely unknown. The challenge originates from the lack of proper modeling of multi-link channel access schemes. In this paper, a novel model is established to study the throughput optimization of heterogeneous two-link IEEE 802.11be networks. MLDs adopt one representative synchronous multi-link channel access scheme with the primary channel. Based on the proposed model, explicit expressions of throughput of MLDs and legacy SLDs are both characterized and verified by simulation results. The network throughput is further maximized by optimally choosing the transmission probabilities of SLDs and MLDs. The analysis shows that MLO can enable MLDs to achieve higher device throughput than SLDs, yet the maximum network throughput of heterogeneous networks decreases compared to homogeneous networks composed solely of MLDs or legacy SLDs.