User-Access Point Association for High Density MIMO Wireless LANs

TL;DR

This paper proposes an optimized user-AP association method for high density UL-MIMO WLANs that significantly improves throughput by solving a graph matching problem with a modified Kuhn-Munkres algorithm.

Contribution

It introduces a novel graph matching approach to optimize user-AP association in dense UL-MIMO WLANs, enhancing throughput over existing schemes.

Findings

Achieves up to 36.9% throughput gains over default schemes.

Effectively manages interference and contention in dense WLANs.

Dynamic updates adapt to network changes and mobility.

Abstract

Wireless local area network (WLAN) access points (APs) are being deployed in high density to improve coverage and throughput. The emerging multiple-input multiple-output (MIMO) implementation for uplink (UL) transmissions promises high per-user throughput and improved aggregate network throughput. However, the high throughput potential of dense UL-MIMO WLAN is impaired by multiple access channel interference and high contention among densely distributed user stations (STAs). We investigate the problem of actualizing the throughput potential of UL-MIMO in high density WLANs via user-AP association. Since user-AP association influences interference and STA contention, a method to optimally distribute STAs among APs is proposed to maximize aggregate users' throughput utility. This problem is transformed into a graph matching problem with the throughput utility function as the graph edge weights. The graph matching problem is solved as a combinatorial problem using a modified classical Kuhn-Munkres algorithm. A dynamic implementation of the proposed algorithm is used to periodically update user-AP associations when there are changes in the network due to new entrants and/or user mobility. Simulated dense UL-MIMO WLAN scenarios reveal that the proposed scheme achieves an average of $36.9 \%$, $33.5 \%$, $20.4 \%$ and $11.3 \%$ gains over the default strongest signal first (SSF) association scheme used in conventional WLAN, Greedy [14], SmartAssoc [13] and best performance first (BPF) [5] algorithms, respectively.