SDN-Based Centralized Channel Assignment Scheme Using Clustering in Dense WLAN Environments

IEEE WLAN 802.11 uses a contention-based medium access control protocol. Adjacent WLAN access points (APs) and stations (STAs) sharing the same channels causes interference, and affect network performance. Existing distributed channel selection schemes are prone to channel oscillation and ripple effect problems. Additionally, centralized schemes may provide optimal or sub-optimal performance but the computation time complexity increases with number of APs. In this paper, we propose a clustering-based centralized channel selection scheme implemented using software-defined networking architecture to overcome these limitations. In the proposed scheme, we first group the APs using a similarity-based clustering algorithm using proximity information. The channel assignment problem is then formulated using an integer linear programming model. Performance evaluation using simulations indicate that the proposed scheme outperforms the common least congested channel selection (LCCS), in terms of throughput and required number of channels switching. Additionally, for N number of APs, the computation complexity is reduced from \(\mathcal {O}\left( 3^{N}\right)\) to \(\mathcal {O}\left( (N)^2\right)\), in comparison to the common centralized channel selection scheme. The test bed results validate simulation results by achieving better data rates for the STAs compared with the LCCS scheme.