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

Bai, Jiyang; Fang, He; Suh, Junghoon; Aboul-Magd, Osama; Au, Edward; Wang, Xianbin

doi:10.1109/iccchina.2018.8641202

Cited by 17 publications

(18 citation statements)

References 8 publications

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“…Little work related to TWT has been published. In [23], an adaptive UL OFDMA random access grouping scheme for IEEE 802.11ax WLANs is proposed. The performance of both the system and each STA is improved by coordinating the group size according to the UORA process during the TWT SP.…”

Section: The Current Progress In Twtmentioning

confidence: 99%

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A Target Wake Time Scheduling Scheme for Uplink Multiuser Transmission in IEEE 802.11ax-Based Next Generation WLANs

Chen

Weng

et al. 2019

IEEE Access

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IEEE 802.11ax Wireless Local Area Networks (WLANs) introduce Orthogonal Frequency Division Multiple Access (OFDMA) physical layer technology to improve throughput in dense scenarios. In order to save power of battery operated stations (STAs), a novel broadcast Target Wake Time (TWT) operation for negotiating wake time between an access point (AP) and a group of STAs is also proposed by making full use of the new capability of uplink OFDMA-based multiuser transmissions. However, if the wake time of each STA which is determined by the offset and wake interval (listen interval) is not properly scheduled, deteriorated throughput and high power consumption occur because of collisions. In this paper, we take the advantage of uplink multiuser transmission with the novel TWT scheduling to maximize throughput. We first investigate the fundamental relationship between throughput and energy efficiency with several key aspects, such as the number of simultaneously active STAs, the number of eligible random access resource units, and the contention window size. We further derive the formulations of throughput and energy efficiency on the listen interval of each STA. Based on the relationship, a TWT-based sleep/wake-up scheduling scheme (TSS) is proposed to improve the throughput by reducing or even cancelling collisions. Simulation results demonstrate the effectiveness in terms of average throughput and energy efficiency. The TSS also makes a practical step towards a collision-free and deterministic access in future WLANs when cooperating with TWT service period scheduling. INDEX TERMS IEEE 802.11ax, WLAN, power conservation, target wake time (TWT), orthogonal frequency division multiple access (OFDMA).

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Section: The Current Progress In Twtmentioning

confidence: 99%

“…where t i denotes the optimal LI assigned to STA s i . Now, we explain the constraints in throughput maximization problem in (23). Since the average number of active STAs in a beacon slot greatly impacts the throughput, it is reasonable to get optimal contention level d cl to maximize throughput.…”

Section: ) Energy Efficiency (Ee)mentioning

confidence: 99%

A Target Wake Time Scheduling Scheme for Uplink Multiuser Transmission in IEEE 802.11ax-Based Next Generation WLANs

Chen

Weng

et al. 2019

IEEE Access

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“…A group-based approach to reducing the collision rate for UORA is proposed in [15]. With this approach, the AP divides the STAs into groups and uses the Target Wake Time (TWT) mechanism to assign a Service Period (SP) to every group.…”

Section: Related Workmentioning

confidence: 99%

Enabling Massive Real-Time Applications in IEEE 802.11be Networks

Avdotin

Bankov

Khorov

et al. 2019

2019 IEEE 30th Annual International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC)

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Next generation Wi-Fi networks are expected to support real-time applications that impose strict requirements on the packet transmission delay and packet loss ratio. Such applications form an essential target for the future Wi-Fi standard, namely IEEE 802.11be, the development process of which started in 2019. A promising way to provide efficient real-time communications in 802.11be networks requires some modification of the uplink OFDMA feature originally introduced in the IEEE 802.11ax amendment to the Wi-Fi standard. This feature allows the access point to reserve channel resources for upcoming urgent transmissions. The paper explains why uplink OFDMA random access of 802.11ax does not perfectly fit the requirements of real-time applications and proposes an easy-to-implement modification of the channel access rules for future 802.11be networks. With extensive simulation, it is shown that this modification together with a new resource allocation algorithm outperforms the existing ways to support real-time applications, especially for a heavy load and a high number of users. In particular, they provide extremely low delays for real-time traffic, while the throughput for non-real-time traffic is reduced insignificantly.

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“…Meanwhile, the authors in [ 27 , 28 , 29 ] attempted to combine UORA with other features in IEEE 802.11ax to improve the channel efficiency. In [ 27 ], the target wake time (TWT) mechanism, aimed at improving the power-saving performance of IEEE 802.11ax, was considered for grouping the STAs. By employing TWT, the STAs are classified into different groups, and their wake and sleep times are controlled collectively.…”

Section: Introductionmentioning

confidence: 99%

“…The number of STAs contending to access RUs can be controlled by means of TWT, and thus transmission collisions can be decreased. In [ 27 ], the optimal number of STAs in a group was also derived to maximize the channel efficiency. This work was extended in [ 28 ] by considering a network situation where the STA delivers BSR based on UORA; the relationship between group size and RU efficiency was analyzed, and an adaptive grouping algorithm with variable group size was proposed to achieve the optimal efficiency of BSR delivery.…”

Section: Introductionmentioning

confidence: 99%

OFDMA Backoff Control Scheme for Improving Channel Efficiency in the Dynamic Network Environment of IEEE 802.11ax WLANs

Kim

Kwon

Park

2021

Sensors

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

Cited by 17 publications

References 8 publications

A Target Wake Time Scheduling Scheme for Uplink Multiuser Transmission in IEEE 802.11ax-Based Next Generation WLANs

A Target Wake Time Scheduling Scheme for Uplink Multiuser Transmission in IEEE 802.11ax-Based Next Generation WLANs

Enabling Massive Real-Time Applications in IEEE 802.11be Networks

OFDMA Backoff Control Scheme for Improving Channel Efficiency in the Dynamic Network Environment of IEEE 802.11ax WLANs

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