Station clustering strategy for DCF-based centralized OFDMA WLAN systems

To enhance the throughput of orthogonal frequency division multiple access (OFDMA) wireless local area network (WLAN) systems, this paper proposes a stations-clustering strategy in which stations in the basic service set (BSS) are grouped into clusters. In the proposed scheme, initially, to obtain statistics required for calculating the expected throughput achieved by OFDMA WLAN when the stations are grouped into a certain clustered-pattern, the access point (AP) and all stations belong to the same cluster and transmit DATA frames for a certain period. After that, the AP calculates the expected throughput for all clustered-patterns and chooses a clustered-pattern that maximizes the expected throughput. Then, the stations are grouped into clusters in accordance with the selected clustered-pattern, and the stations within the same cluster share the radio resource by OFDMA WLAN scheme. Numerical simulation confirms that the proposed scheme can maximize throughput performance by introduction of dynamic station clustering in the single BSS environment and it is also effective in preventing channel state information (CSI) feedback blocking due to station exposition in the overlapping BSS environment.