Orthogonal frequency division multiple access (OFDMA) is one of the critical features adopted in IEEE 802.11ax, where multiple stations can simultaneously access the wireless channel. Although appropriate sub-channel allocation is crucial to improving channel efficiency, the allocation method is vendor specific, since there is no central controller in the Wi-Fi network. In this chapter, we propose a utility-based dynamic resource allocation (UDRA) scheme for orthogonal frequency division multiple access resource management in IEEE 802.11ax WLANs. In UDRA, each access point (AP) obtains neighbor information using a newly proposed modified clear-to-send (M-CTS) frame by overhearing stations in an area overlapping with the other APs’ signal area. After that, we formulate the network-wise utility maximization problem, which considers both throughput and fairness, to determine which sub-channels should be allocated to which stations. Furthermore, we adopt a genetic algorithm to solve the derived optimization problem since the problem is known to be NP-hard. We map the proposed scheme, UDRA, onto a terminology of genetic algorithm. Extensive simulation results demonstrate that UDRA can guarantee comparable throughput to exhaustive search while preserving improved fairness with significantly reduced computing time.