Wi-Fi 6 performance measurements of 1024-QAM and DL OFDMA

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Abstract
IEEE 802.11ax is the new standard introduced by the IEEE that focuses on improving efficiency of Wireless LANs. Among others, two of the newly introduced features are 1024 Quadrature Amplitude Modulation (QAM) and Orthogonal Frequency Division Multiple Access (OFDMA). In this paper, the expected throughput gain of 25% with the new 1024-QAM and expected latency reduction with downlink (DL) OFDMA are examined with state of the art reference boards of two different Wi-Fi chipset manufacturers. Using three Samsung S10 mobile phones as clients, experiments were performed to measure the expected increase in throughput and decrease in latency.The 25% increase in throughput with 1024-QAM was achieved, albeit with a maximum range of operation of less than 6 meters when using a maximal transmit power for MCS 11. We observed a very low percentage of packets transmitted using DL OFDMA in the traffic profiles used. We conclude that the introduction of DL OFDMA does not have a significant impact on the latency with the test scenarios covered. The performance of DL OFDMA is heavily dependent on the ability of the access point to properly schedule DL OFDMA transmissions. The number of clients, packet size, and buffer size play an essential role in the scheduling process. Based on our measurements the benefit of DL OFDMA is expected to be limited unless the number of clients is substantially higher than the three clients used, as would be the case in a stadium, train, or mall.