This paper studies the usage of orthogonal frequency division multiple access (OFDMA) for uplink transmissions in IEEE 802.11ax networks. OFDMA enables simultaneous multi-user transmissions in Wi-Fi, but its usage requires efficient resource allocation algorithms. These algorithms should be able to adapt to the changing channel conditions, including the frequency-selective fading. This paper presents an OFDMA resource allocation algorithm for channels with frequency-selective fading and proposes an approach to adapt the user transmission power and modulation and coding schemes to the varying channel conditions, which is efficient even in the case when the access point has outdated channel state information. The proposed scheduling algorithm and power allocation approach can double the goodput and halve the data transmission time in Wi-Fi networks even in dense deployments of access points.

Non-orthogonal multiple access (NOMA) is a radio access technology that allows significantly improving network performance in scenarios with high heterogeneity. While being typically studied for cellular networks, NOMA can also be used in Wi-Fi networks. This paper proposes a scheduling approach for NOMA-aware resource scheduling in Wi-Fi. This approach is implemented to design NOMA-aware downlink schedulers which follow such wide-spread strategies as max-rate, proportional-fair and shortest-remaining-processing-time.

Non-orthogonal Multiple Access (NOMA) is a technology that can improve the spectral efficiency of Wi-Fi networks in a downlink. NOMA allows data transmission to several devices simultaneously in one timefrequency resource. In this paper, we investigate the geometric mean throughput gain of a Wi-Fi network using NOMA over the classical time-division multiple access method. For this, we develop a simulation model of a Wi-Fi network using NOMA, which is calibrated using a previously developed experimental setup. The results show that the use of NOMA can increase the geometric mean throughput up to 40%.

The number of wireless devices, as well as their traffic volumes, is constantly growing, which degrades the quality of service. To combat this problem, the new Wi-Fi 6 (IEEE 802.11ax) standard introduces the orthogonal frequency division multiple access (OFDMA) mechanism, which allows coordinated multiuser frequency division transmissions. In addition, there is another user multiplexing mechanism, non-orthogonal multiple access (NOMA), that allows transmitting on the same frequencies simultaneously and separating different signals by power level. This paper considers the joint usage of these mechanisms for uplink transmissions in Wi-Fi 6 networks and sets the problem of optimal radio resource allocation between the users to maximize some utility functions, for example, the geometric mean throughput. To solve it, we propose an algorithm that takes into account the channel frequency selectivity and uses OFMDA and NOMA simultaneously. It is shown that the joint usage of OFDMA and NOMA can significantly increase the network throughput and reduce delays.