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Performance evaluation of OFDMA and aggregation downlink stateless service disciplines in Wi-Fi networks

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Anh Tuan Giang
Anh Tuan Giang
Anh Tuan Giang
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Anthony Busson at University of Lyon
Anthony Busson
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Abstract and Figures

Aggregation and Orthogonal Frequency Division Multiple Access (OFDMA) are two fundamental features allowing access points and stations to benefit from the high physical transmission rates of the recent WiFi standards. They aim to pool frames with a unique overhead (mainly the physical header and the acknowledgment) to mitigate its impact on the throughput. Natural implementations of these features lead to nonFIFO (First In, First Out) service disciplines that may generate unfairness between frames. In this paper, we evaluate three stateless service disciplines that require a low level of resources (computation and memory). We prove that when OFDMA does not introduce additional delay, one of these greedy algorithms minimizes the overhead. Whereas this service discipline maximizes the system capacity, it generates strong unfairness between the stations. Instead, the two other algorithms may offer a good trade-off between capacity and fairness. These algorithms are evaluated through a theoretical framework and simulations that replay actual Wi-Fi traces.
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ORIGINAL PAPER
Performance evaluation of OFDMA and aggregation downlink
stateless service disciplines in Wi-Fi networks
Anh Tuan Giang
2
•Anthony Busson
1
Accepted: 27 January 2024 / Published online: 27 February 2024
The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature 2024
Abstract
Aggregation and Orthogonal Frequency Division Multiple Access (OFDMA) are two fundamental features allowing access
points and stations to benefit from the high physical transmission rates of the recent WiFi standards. They aim to pool
frames with a unique overhead (mainly the physical header and the acknowledgment) to mitigate its impact on the
throughput. Natural implementations of these features lead to nonFIFO (First In, First Out) service disciplines that may
generate unfairness between frames. In this paper, we evaluate three stateless service disciplines that require a low level of
resources (computation and memory). We prove that when OFDMA does not introduce additional delay, one of these
greedy algorithms minimizes the overhead. Whereas this service discipline maximizes the system capacity, it generates
strong unfairness between the stations. Instead, the two other algorithms may offer a good trade-off between capacity and
fairness. These algorithms are evaluated through a theoretical framework and simulations that replay actual Wi-Fi traces.
Keywords Wi-Fi Scheduling Service discipline OFDMA Aggregation Performance evaluation
1 Introduction
The new Wi-Fi standards, formally the family of IEEE
802.11 standards, continuously improve Wi-Fi networks
from the physical to the MAC layers. Over the years, the
physical transmission rate (at which data is transmitted) has
increased from 1 to 2 Mbit/s up to several Gbit/s for the
last standards. Such transmission rates made the procedure
to access the medium the bottleneck that limits the
throughput as it can be longer than the data transmission
itself. A new feature has then been brought in Wi-Fi 4,
frames aggregation, which pools several frames intended
for the same destination together with a unique access
procedure mitigating its effect on the throughput. More
recently, Orthogonal Frequency Multiple Access
(OFDMA) has been defined in the two recent standards
IEEE 802.11ax (Wi-Fi 6) and IEEE 802.11be. Its purpose
is also to pool several frames together, even if their des-
tinations differ. Basically, OFDMA allocates a subset of
the sub-carries that compose the channel to each frame.
The frames are then sent in parallel with a unique medium
access procedure. These two features definitely improve
the throughput that the Wi-Fi network can reach. However,
aggregation and OFDMA may change the transmission
order regarding the arrival of the frames in the buffer, i.e.,
use a non-FIFO discipline to pool a maximum of frames
together. This change may generate unfairness between the
frames and increase the delay spent in the buffer for certain
frames.
We can make the analogy with a queue in a supermarket
where, for each customer, the cashier begins with a small
chit-chat, scans the products, prints the bill, and waits for
the payment. The technology makes the scans of the
products very fast, and the associated time becomes neg-
ligible with regard to the overhead (chit-chat, bill, and
payment). The idea is then to pool several customers with
only one chit-chat, bill, and payment. However, all cus-
tomers cannot be pooled together. It depends on some
&Anthony Busson
anthony.busson@ens-lyon.fr
Anh Tuan Giang
giang-anh.tuan@usth.edu.vn
1
Laboratoire de l’informatique du Paralle
´lisme, UMR 5668
University Lyon 1 - ENS de Lyon - UCBL - CNRS - Inria,
Lyon, France
2
University of Science and Technology of Hanoi, Vietnam
Academy of Science and Technology, Hanoi, Vietnam
123
Wireless Networks (2024) 30:2571–2587
https://doi.org/10.1007/s11276-024-03689-2(0123456789().,-volV)(0123456789().,-volV)
Content courtesy of Springer Nature, terms of use apply. Rights reserved.
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