The ambitious goal of the upcoming IEEE 802.11ax (HEW) standard for wireless LANs (WLANs) to enhance throughput by four times (and beyond), compared with IEEE 802.11ac, demands a radical improvement of present medium access control (MAC) functionality. To this end, a promising paradigm would be a graceful migration towards new MAC protocols which incorporate higher certainty in their decisions. However, this requires adequate information to be available to the devices, which in turn incurs

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... sive costs due to information exchange between devices. Also, scalability becomes an issue for emerging dense networks. In this paper, we take a step forward by proposing an opportunistic MAC (OMAC), which restrains these costs, while increasing throughput of the new generation HEW. OMAC eliminates overhead costs by solely relying on the local capability of devices in measuring signal activities in the channel. A particular OMAC node continually collects and records the received signal strengths (RSS) overheard from the channel, and regards each individual RSS level as being transmitted by a unique node without the need to know the actual identity of the node. The OMAC node uses this knowledge to select a recorded RSS as its reference, and triggers a desired transmission policy whenever a transmission with an RSS sufficiently close to this reference RSS is detected. Our results, obtained using simulations, indicate that OMAC improves the throughput performance significantly, and that the performance gain increases with an increase in network density.