Abstract: In order to efficiently utilize wireless channels in Wireless Local Area Network (WLAN), a novel channel access scheme using an alternative primary channel is proposed in this paper. In the next generation Wireless Local Area Network (WLAN), IEEE 802.11ax, since, non-contiguous channels access is allowed, channel efficiency can be enhanced very much. However, there has been no proposal on specific rules and study on performance analysis. In this study, specific protocol to fully utilize non-contiguous channels by designating alternative primary channel is proposed. The performance of the proposed scheme is fully evaluated by mathematical analysis.