Throughput Optimization Based Joint Access Point Association and Transmission Time Allocation in WLANs

Zhiwei Mao

doi:10.1109/ojcoms.2021.3072573

Abstract

In this paper, the joint access point (AP) association and transmission time allocation problem in densely deployed multirate WLANs based on time sharing medium access control (MAC) is considered. In our study, the centralized coordinated joint AP association and transmission time allocation problem with heterogeneous station (STA) throughput demands is first formulated as an NP-hard single non-zero programming (SNZP) optimization problem with proportionally fair (PF) throughput based objective function. To solve the NP-hard SNZP problem, two novel algorithms, the SNZP relaxation (SNZPR) algorithm and the iterative SNZPR (iSNZPR) algorithm, are proposed. The property and complexity of the proposed algorithms are analyzed. In addition, for dynamic network scenarios where there are new STAs arriving at and trying to join the network, a distributed joint admission, AP association and transmission time allocation (DAAA) algorithm is proposed to determine whether to admit a new STA arriving at the network or not. The performance of the proposed algorithms is then investigated and compared with that of some existing algorithms based on numerical results.

Highlights

T HE WIDESPREAD of mobile devices and increasing demand for low-cost wireless connectivity have promoted wide deployment of Wi-Fi wireless local area network (WLAN) based on IEEE 802.11 standard [1]
In areas with large number of users, such as airports, stadiums, large business office buildings, multistory apartment buildings, and other hotspots, WLANs are deployed in a dense manner, with tens to hundreds of access point (AP) closely deployed in a given area with densely and unevenly distributed STAs resulting in overlapping basic service set (OBSS)
Based on the results of property analysis, we propose a novel algorithm, the DAAA algorithm for distributed joint admission, AP association and transmission time allocation, in the scenarios where some STAs arriving at the network cannot be supported and need to be rejected

Summary

INTRODUCTION

T HE WIDESPREAD of mobile devices and increasing demand for low-cost wireless connectivity have promoted wide deployment of Wi-Fi wireless local area network (WLAN) based on IEEE 802.11 standard [1]. We consider centralized coordinated joint AP association and transmission time allocation with heterogeneous STA throughput demands in the considered networks. The centralized coordinated joint AP association and transmission time allocation problem is first formulated as an NP-hard single non-zero programming (SNZP) optimization problem with proportionally fair (PF) throughput based objective function. STAs can associate with and obtain transmission time from multiple APs. Reference [24] proposed an online centralized AP association and channel time allocation scheme based on reinforcement learning which minimizes the STAs dissatisfaction in terms of obtained throughput. Based on the network model discussed above, the centralized coordinated joint AP association and transmission time allocation problem can be formulated as the following constrained mixed integer programming (MIP) optimization problem [21], [22], [34]. We will use the formulation in (5)

SNZPR AND ISNZPR ALGORITHMS

COMPLEXITY ANALYSIS

DAAA ALGORITHM

VIII. CONCLUSION