An Efficient Backoff Procedure for IEEE 802.11ax Uplink OFDMA-based Random Access

IEEE 802.11ax uplink orthogonal frequency division multiple access (OFDMA)-based random access (UORA) is a new feature for random channel access in wireless local area networks (WLANs). Similar to the legacy random access scheme in WLANs, UORA performs the OFDMA backoff (OBO) procedure to access the channel and decides on a random OBO counter within the OFDMA contention window (OCW) value. An access point (AP) can determine the OCW range and inform each station (STA) of it. However, how to determine a reasonable OCW range is beyond the scope of the IEEE 802.11ax standard. The OCW range is crucial to the UORA performance, and it primarily depends on the number of contending STAs, but it is challenging for the AP to accurately and quickly estimate or keep track of the number of contending STAs without the aid of a specific signaling mechanism. In addition, the one for this purpose incurs an additional delay and overhead in the channel access procedure. Therefore, the performance of a UORA scheme can be degraded by an improper OCW range, especially when the number of contending STAs changes dynamically. We first observed the effect of OCW values on channel efficiency and derived its optimal value from an analytical model. Next, we proposed a simple yet effective OBO control scheme where each STA determines its own OBO counter in a distributed manner rather than adjusting the OCW value globally. In the proposed scheme, each STA determines an appropriate OBO counter depending on whether the previous transmission was successful or not so that collisions can be mitigated without leaving OFDMA resource units unnecessarily idle. The results of a simulation study confirm that the throughput of the proposed scheme is comparable to the optimal OCW-based scheme and is improved by up to 15 times compared to the standard UORA scheme.

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Uplink OFDMA-based Random Access Mechanism with Bursty Arrivals for IEEE 802.11ax Systems

IEEE Networking Letters ◽

10.1109/lnet.2021.3138277 ◽

2021 ◽

pp. 1-1

Author(s):

Ray-Guang Cheng ◽

Chi-Ming Yang ◽

Bariq S. Firmansyah ◽

Ruki Harwahyu

Keyword(s):

Random Access ◽

Ieee 802.11Ax

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Adaptive Uplink OFDMA Random Access Grouping Scheme for Ultra-Dense Networks in IEEE 802.11ax

2018 IEEE/CIC International Conference on Communications in China (ICCC) ◽

10.1109/iccchina.2018.8641202 ◽

2018 ◽

Cited By ~ 2

Author(s):

Jiyang Bai ◽

He Fang ◽

Junghoon Suh ◽

Osama Aboul-Magd ◽

Edward Au ◽

...

Keyword(s):

Random Access ◽

Dense Networks ◽

Ieee 802.11Ax

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Performance Analysis of IEEE 802.11ax UL OFDMA-Based Random Access Mechanism

GLOBECOM 2017 - 2017 IEEE Global Communications Conference ◽

10.1109/glocom.2017.8254054 ◽

2017 ◽

Cited By ~ 6

Author(s):

Hang Yang ◽

Der-Jiunn Deng ◽

Kwang-Cheng Chen

Keyword(s):

Performance Analysis ◽

Random Access ◽

Ieee 802.11Ax

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Group-Based Uplink OFDMA Random Access Algorithm for Next-Generation WLANs

Xibei Gongye Daxue Xuebao/Journal of Northwestern Polytechnical University ◽

10.1051/jnwpu/20203810155 ◽

2020 ◽

Vol 38 (1) ◽

pp. 155-161

Author(s):

Annan Yang ◽

Bo Li ◽

Mao Yang ◽

Zhongjiang Yan

Keyword(s):

Multiple Access ◽

Wireless Local Area Network ◽

Local Area Network ◽

Random Access ◽

Local Area ◽

Network Throughput ◽

Practical Significance ◽

Area Network ◽

Ieee 802.11Ax ◽

Access Channel

The traditional wireless local area network(WLAN) standard, IEEE 802.11, adopts carrier sense multiple access/collision avoidance(CSMA/CA) mechanism to allow a single user to compete for channel access. The upcoming WLAN standard, IEEE 802.11ax, combines orthogonal frequency division multiple access(OFDMA) technology with random access, and use Uplink OFDMA Random Access(UORA) technology as uplink random access. Therefore, UORA which allow multiple users to access channel at the same time can improve the utilization of network resources. Although UORA technology in IEEE 802.11ax has the advantage of low signaling overhead, when the number of users of network is large, the increase of random access collisions will lead to the decrease of network throughput. Therefore, we propose a group-based UORA method. As a central scheduling node, Access Point(AP) divide Stations(STAs) and resources to groups and sets different GroupID for different groups. STAs can only access resources with the same GroupID randomly. The validity of group-based UORA method is verified by mathematical model analysis and simulation. The network throughput of our group-based UORA is higher than that of the original UORA in IEEE 802.11ax, so it has great practical significance.

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