Wi-Fi evolution: the IEEE 802.11ax standard for dense wireless local area networks
The journey from IEEE 802.11n to IEEE 802.11ac standard contained many technological advances of the standards for Wireless Local Area Networks (WLANs). The transition to the 5 GHz band in IEEE 802.11ac led to the use of non-adjacent channels for increasing transmission bandwidth to 160 MHz. The modulation schemes that are employed achieved a further increase of the data rate in the order of 6.9 Gbps. In 2014 the IEEE 802.11ax Working Group was established for the purpose of creating a modification of IEEE 802.11ac that will operate in dense wireless LANs. The new model will use many of the features of IEEE 802.11ac but will also include many new features and enhancements. The aim is to support simultaneous transmissions and reduce the interference in dense WLAN environments. From the literature, it is apparent that the Orthogonal Frequency-Division Multiple Access (OFDMA) is a basic technology to be used in IEEE 802.11ax standard. Moreover, the management of multiple Overlapping Basic Service Sets (OBSSs) through the dynamic adjustment of the Clear Channel Assessment (CCA) threshold for minimizing the interference is an important parameter studied by the IEEE 802.11ax Working Group. The optimal setting of CCA is an important feature for enhancing spatial reuse. The Working Group has already performed studies and proposed the introduction of two CCA thresholds for OBSSs environments.