Abstract
IEEE 802.11ax stations can use multi-user (MU) uplink OFDMA-based random access (UORA) to improve per-station throughput in dense deployments in comparison to legacy IEEE 802.11 single-user access. Unfortunately, UORA suffers from a high collision probability and low efficiency under high contention. In this paper, we address this problem by modifying the UORA backoff selection method. The proposed solution allows an access point to adjust the OFDMA random access backoff (OBO) countdown rate to decrease the probability of uplink transmission failures. The implemented changes considerably improve UORA performance. We show through extensive simulations, that the proposed efficient OFDMA random access backoff (E-OBO) ensures throughput, efficiency, and collision probability close to optimal and outperforms state-of-the-art solutions.
Highlights
The IEEE 802.11ax amendment introduces uplink (UL) multi-user (MU) orthogonal frequency-division multiple access (OFDMA) to improve the efficiency of Wi-Fi networks
CHANNEL ACCESS DELAY In Figure 5, we present a comparison of the average channel access delay for uplink OFDMA-based random channel access (UORA)-E-OFDMA random access backoff (OBO) and UORA-OBO-CTRL
In this paper we addressed the problem of low UORA efficiency under dense deployments with high station contention
Summary
The IEEE 802.11ax amendment introduces uplink (UL) multi-user (MU) orthogonal frequency-division multiple access (OFDMA) to improve the efficiency of Wi-Fi networks. This letter was designed to provide uplink OFDMA-based random channel access (UORA). In OFDMA-based channel access, radio channel resources are divided into several sub-carrier groups, called resource units (RUs). This allows multiple stations to perform transmissions at the same time, which improves efficiency in comparison to single user channel access. In case of uplink 802.11ax RA, stations contend for RUs using a novel UL OFDMA random access (UORA) method. The operation of UORA is based on the OFDMA contention window (OCW) and OFDMA random access backoff (OBO). Each station selects a random OBO counter from the range (0, OCW) and decreases it by the number of eligible RUs assigned by the access point (AP) for the uplink transmissions.
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