Resource management for OFDMA based next generation 802.11 WLANs

Abstract

Recently, IEEE 802.11ax Task Group has adapted OFDMA as a new technique for enabling multi-user transmission. It has been also decided that the scheduling duration should be same for all the users in a multi-user OFDMA so that the transmission of the users should end at the same time. In order to realize that condition, the users with insufficient data should transmit null data (i.e. padding) to fill the duration. While this scheme offers strong features such as resilience to Overlapping Basic Service Set (OBSS) interference and ease of synchronization, it also poses major side issues of degraded throughput performance and waste of devices' energy. In this work, for OFDMA based 802.11 WLANs we first propose practical algorithm in which the scheduling duration is fixed and does not change from time to time. In the second algorithm the scheduling duration is dynamically determined in a resource allocation framework by taking into account the padding overhead, airtime fairness and energy consumption of the users. We analytically investigate our resource allocation problems through Lyapunov optimization techniques and show that our algorithms are arbitrarily close to the optimal performance at the price of reduced convergence rate. We also calculate the overhead of our algorithms in a realistic set-up and propose solutions for the implementation issues.

High-Performance Industrial Wireless: Achieving Reliable and Deterministic Connectivity Over IEEE 802.11 WLANs

“…However, it has been rarely implemented in conventional WLANs. Some recent studies like [19] and [20] have explored resource management aspects of IEEE 802.11ax WLANs. However, the use of IEEE 802.11ax for industrial communication has been rarely investigated.…”

A Novel Low-Overhead Channel Sounding Protocol for Downlink Multi-User MIMO in IEEE 802.11ax WLAN

“…OFDMA is a multiple user technology used even in LTE and WiMAX, where the OFDM subcarriers are grouped into Resource Units (RUs) in order to improve the frequency utilization efficiency by assigning good signal quality RUs to multiple users [15], [16]. In 802.11ax, it is possible to support simultaneous transmission of up to nine users in the 20MHz bandwidth using 1/4th of the sub-carrier spacing arranged with the conventional standards.…”

Scheduling Strategies and Throughput Optimization for the Uplink for IEEE 802.11ax and IEEE 802.11ac Based Networks

“…The AP allocates RUs to the stations which use them later for data transmissions over the UL. In [13] a new method to use OFDMA over the UL is suggested, where MAC Protocol Data Units (MPDU) from the stations are of different lenghs. In [14][15][16][17]…”