Convergence Evaluation of OFDMA-IDMA Combination Based on IEEE 802.11ax

The 802.11ax standard incorporates Orthogonal Frequency Division Multiple Access (OFDMA) to address transmission challenges by dividing the channel into Resource Units (RU) allocated to Stations (STAs). This is particularly useful in Uplink (UL) multi-user transmission. However, OFDMA faces difficulties with numerous STAs, primarily due to RU size or bandwidth limitations. Non-Orthogonal Multiple Access (NOMA) emerges as a highly valued wireless network technique to tackle these challenges. As a variety of NOMA, Interleave Division Multiple Access (IDMA) demonstrates the potential to enhance spectrum efficiency, STA capacity, and data rates without neces-sitating changes in RU size or bandwidth. This paper proposes to incorporate IDMA with the existing OFDMA 802.11ax system to drastically increase the number of STAs in a UL multi-user system. OFDMA-IDMA can reduce the number of STAs per RU, reducing Multiple Access Interference, which is a problem when using IDMA individually. The paper also shows the upper bound of the number of STAs per RU when implementing OFDMA-IDMA that the maximum number of STAs can be transmitted on 20 MHz, and it proposed using a higher bandwidth to ensure Quality of Service (QoS) constraints.