The IEEE 802.11ax (Wi-Fi 6) and IEEE 802.11be (Wi-Fi 7) adopt the OFDMA technology to provide high-speed and uninterrupted communications in the dense network. Until the advent of IEEE 802.11ax standard, Wireless LAN (WLAN) predominantly uses the Random Access (RA) mechanism to access the network. IEEE 802.11ax and IEEE 802.11be (proposed) provide another access mechanism for WLAN (i.e., Wi-Fi), which is known as Scheduled Access (SA). This mechanism utilizes the OFDMA technology to provide highspeed and smooth communications in congested areas. By the way, the performance of the OFDMA based wireless LAN largely depends on the scheduling protocol. Many researchers propose RA and SA protocols independently, which do not consider the simultaneous implementation of both mechanisms. This paper proposes a Proportional Resource Scheduling (PRS) scheme for the OFDMA-based wireless LAN that simultaneously implements RA and SA mechanisms for data transmission. We design two algorithms for the resource scheduling for the PRS protocol. Algorithm 1 provides the initial scheduling information, which is received by Algorithm 2 as the input. After performing revision, Algorithm 2 provides the final scheduling information to the access point. The PRS distributes the channel resources proportionally to the stations according to their available loads. Thus, it utilizes the resources efficiently and increases the throughput and fairness in accessing the channel. We construct analytical models both for the SA and RA mechanisms and conduct rigorous simulations to measure the efficiency of the PRS protocol. The analyses validate the robustness of the proposed protocol in throughput, goodput, fairness, and retransmissions. The main contribution of the proposed protocol is that it provides a framework for simultaneous implementation of RA and SA mechanisms for the future wireless LAN.