Vol.:(0123456789)
1 3
J Ambient Intell Human Comput
DOI 10.1007/s12652-017-0588-z
ORIGINAL RESEARCH
Adaptive access mechanism withdelta estimation algorithm
oftraffic loads forsupporting weighted priority inIEEE 802.11e
WLANs
ChunShi
1,2
· Shu‑QianHe
1
· Zheng‑JieDeng
1
· Xian‑FengZhang
1
· ChongShen
3
Received: 5 July 2017 / Accepted: 23 September 2017
© Springer-Verlag GmbH Germany 2017
Keywords Medium access control· Weighted fairness·
Delta estimation· Idle slot intervals· Weighted priority
levels
1 Introduction
With the development of internet of things (IoTs), there are
many different traffic types in wireless networks, such as
voice, data or video. The multiple traffic types have differ-
ent requirements of bandwidth. The weighted priority levels
(WPLs) of throughput proportion that nodes get correspond-
ing bandwidth according to priority levels are one of the
main research directions to improve the QoS performance
of networks. The IEEE 802.11 family has been proved
the most popular channel access control mechanisms that
can support QoS requirements of networks (IEEE 2007).
The contention-based access method and contention-free
access method (controlled channel access method) are two
main types of channel access mechanisms in IEEE 802.11.
We focus our interest on WPLs of packet flows and study
saturated throughput performance of the contention-based
access mechanism.
The distributed coordination function (DCF) is a fun-
damental contention-based access mechanism, which
defines uniform parameters and provides the best effort
service. An enhanced distributed channel access func-
tion (EDCAF) for each access category (AC) can support
QoS requirements, which is an enhanced variant of DCF
and referred to as HCF contention-based channel access
(EDCA) mechanism. The main functions of EDCA mecha-
nism are similar with that of DCF mechanism except some
parameters of each AC. The EDCA mechanism, however,
cannot solve collision problem caused by incremental
number of nodes with the same priority level, but adds
Abstract Focusing on weighted throughput fairness that
nodes get throughput proportions according to priority lev-
els in IEEE 802.11e WLANs, we propose an adaptive and
full-distributed access mechanism with delta estimation
algorithm of traffic loads. We deduce a linear adjustment
rule of Contention Window (CW) about traffic loads, which
connects parameters of access mechanism with dynamic
network conditions. To support weighted priority levels
(WPLs) of throughput proportions, we introduce a prior-
ity index to restrict number of successful data transmission
of nodes with different priority levels for accurate calcu-
lation of channel status information. And then, we give a
delta estimation algorithm of traffic loads, which can reduce
fluctuations of estimated results around true values. By set-
ting different thresholds corresponding to the WPLs, each
node can obtain suitable sizes of CW for better aggregated
throughput even as the variations of traffic loads in networks.
The selected sizes of CW determine the attempt probability
of channel access, which guarantees the weighted fairness of
throughput proportions corresponding to WPLs. The simula-
tion results confirm the validity and good scalability of the
proposed access mechanism with different ratios of node
number between multiple priority levels.
* Shu-Qian He
shipaper17@163.com
1
School ofInformation Science andTechnology,
Hainan Normal University, Haikou571158,
People’sRepublicofChina
2
Key Laboratory ofUnderwater Acoustic Communication
andMarine Information Technology (Xiamen
University), Ministry ofEducation, Xiamen361005,
People’sRepublicofChina
3
School ofInformation Science andTechnology, Hainan
University, Haikou570228, People’sRepublicofChina