Smart optimization in 802.11p media access control protocol for vehicular ad hoc network

International Journal of Electrical and Computer Engineering (IJECE)
Vol. 13, No. 2, April 2023, pp. 2206~2213
ISSN: 2088-8708, DOI: 10.11591/ijece.v13i2.pp2206-2213  2206
Journal homepage: http://ijece.iaescore.com
Smart optimization in 802.11p media access control protocol for
vehicular ad hoc network
Shahirah Mohamed Hatim1
, Haryani Haron2
, Shamsul Jamel Elias3
, Nor Shahniza Kamal Bashah2
1
Faculty of Computer and Mathematical Sciences, Universiti Teknologi MARA, Perak, Malaysia
2
Faculty of Computer and Mathematical Sciences, Universiti Teknologi MARA, Shah Alam, Malaysia
3
Faculty of Computer and Mathematical Sciences, Universiti Teknologi MARA, Kedah, Malaysia
Article Info ABSTRACT
Article history:
Received Dec 23, 2021
Revised Sep 15, 2022
Accepted Oct 11, 2022
The innovative idea presented in this research is that advancements in
automotive networks and embedded devices can be used to assess the impact
of congestion control on throughput and packet delivery ratio (PDR), or so-
called multimedia content delivery. Vehicle networking and the distribution
of multimedia content have become essential factors in getting packets to
their intended recipients due to the availability of bandwidth. Vehicle-to-
infrastructure (V2I) communication systems are crucial in vehicular ad hoc
networks (VANETs), which permit vehicles to connect by distributing and
delivering traffic data and transmission packet schemes. High levels of
mobility and changing network topology necessitate dispersed monitoring
and execution for congestion control. The amount of traffic congestion for
packet transfers could be reduced by enhancing congestion management in
terms of throughput and PDR percentages. In a highway setting, the Taguchi
approach has been used to optimize the parameters for congestion control.
Based on throughput and PDR performance measures, this technique
minimizes superfluous traffic information and lowers the likelihood of
network congestion. The simulation results have shown that the proposed
approach performs better since it increases network performance while
effectively utilizing bandwidth. The effectiveness of the suggested technique
is evaluated using a typical VANETs scenario for V2I communication while
driving on a highway.
Keywords:
Optimization
Packet delivery ratio
Taguchi method
Vehicle-to-infrastructure
Vehicular ad hoc network
This is an open access article under the CC BY-SA license.
Corresponding Author:
Haryani Haron
Faculty of Computer and Mathematical Sciences, Universiti Teknologi MARA
40450 Shah Alam, Selangor, Malaysia
Email: harya265@uitm.edu.my
1. INTRODUCTION
Vehicular ad hoc networks or namely (VANETs) refer to a division of mobile ad hoc networks
(MANETs) in which the network's participant vehicles serve as mobile nodes. This technology was made
available as a way to reduce traffic congestion. It has several unique characteristics that enable it to
outperform standard MANETs, including a dynamic topology, high mobility, and high network density.
Applications for VANETs are divided into two categories: applications for safety and applications for non-
safety [1]–[10]. Applications for safety could be found in drivers' information, such as critical events
involving connectivity, dependability, and delay. The purpose of the safety application is to avoid traffic
accidents by communicating vital information to road users allied to VANETs to save their lives [2], [4],
[10]. In contrast, instead of using delay-sensitive applications, non-safety applications are utilized to improve

Int J Elec & Comp Eng ISSN: 2088-8708 
Smart optimization in 802.11p media access control protocol for … (Shahirah Mohamed Hatim)
2207
the transportation system and services that require them. In VANETs, the testing scenarios for transportation
services include cities, highways, and intersections. The structure of VANETs is illustrated in Figure 1 [1], [11].
Figure 1. The structure of VANETs
In the highway scenario, the speed between vehicles is low when they are traveling in a group, but it
is high when roadside units (RSUs) are present. In all traffic situations, vehicles going in the same and
opposing directions can be assessed. For instance, when more RSUs can be put in the city, driving conditions
there are typically slower than those on the highway. With all the skyscrapers acting as barriers, the route
across the city could be more complicated, and the driver's pattern could also be unpredictable. There are
more RSUs accessible between the transmitter and receiver state circumstances during intersectional traffic
[12].
Direct communication between nodes occurs without using an access point (AP). While in
VANETs, the highways are outfitted through static RSU and mobile nodes with on board units (OBUs) [1],
[2], [4]. It is therefore possible to assess the performance using functional metrics, node density, high node
mobility, and unexpected communication situations. In VANETs, the communication between cars using the
RSUs infrastructure is acknowledged as V2I communications, and the embedded OBUs in the vehicles can
share and transfer data with one another [1].
VANETs are intended to offer a variety of comforts to drivers and passengers, but more
significantly for non-safety uses [1], [13], [14]. Irrespective of the environment, with a relative speed of up to
180 km/h and a range of one kilometer, VANETs are able to provide 802.11p communication with RSUs as
well as other vehicles. VANETs can provide a wealth of information, including position, speed, emergency
warnings, and roadside entertainment, but if users react poorly to the technology, this wealth of information could
delay implementation and increase packet latency [1]–[4], [11], [15], [16].
The connectedness of the nodes' communication and the delivery of packets to their intended locations
are maintained by network performance optimization. Designing the new network parameter is hence an
expensive endeavor to improve network protocols. For VANETs topology changes and to maintain connectivity
and communication between vehicles, increasing the number of RSUs could be highly expensive [1], [2], [4],
[14]. It places a strong emphasis on network optimization and improvement rather than relying exclusively on
alterations to the network's parameters.
This strategy necessitates that the method is intelligent enough to enhance circumstances even in
error-free environments driven by the need to eliminate traffic congestion and delays [15]. In this research,
the Taguchi approach is used to optimize the vehicular networks for packet delivery ratio (PDR) and
throughput. The evaluation condition for this study is the highway scenario.

 ISSN: 2088-8708
Int J Elec & Comp Eng, Vol. 13, No. 2, April 2023: 2206-2213
2208
2. THE PROPOSED METHOD
2.1. Taguchi method as the optimization procedure
Genichi Taguchi initially presented the Taguchi technique in 1960. The goal is to manufacture high-
quality goods at cheaper prices while minimizing process variance and planning a strong experimental design
[17], [18]. The Taguchi method is a type of experimental design used to examine how different variables
affect the mean and variation of a process performance parameter.
Taguchi's method is considered as an optimization approach where it relies on an orthogonal array
(OA) design that can be used to obtain settings that are close to near-optimal [15], [19]. Taguchi, which
offers a methodical approach towards selecting the controlling factors on any experimental simulation, OA
stands as a crucial parameter. Manufacturing processes see the most widespread application of Taguchi's
technique, followed by other technical specialties including wireless communications, power electronics, and
electromagnetic [16], [18], [20], [21]. Figure 2 demonstrates the steps of Taguchi optimization [15].
To ensure better network performance, Taguchi was employed to optimize the radio network's
parameters. Vertical sectorization will lead to a capacity gain that can be realized. Vertical sectorization was
also utilized to improve radio networks, outperforming conventional networks by increasing user throughput
in the 50th and 5th percentiles [14], [22].
Figure 2. Phases in Taguchi optimization
2.2. Planning phase
The goal of this study is to optimize the vehicular network's control parameters for maximum
throughput and optimal packet delivery rates for VANET congestion control. Packet size in kilobyte (KB)
and RSU distance in m are the next control factors that are meant to be optimized. The three sources of noise
are the number of nodes, the frequency of packet creation, and the speed of mobility. Table 1 lists the levels
of variance for the control factors. The range of packet sizes examined is 25 to 125 KB. Along the route, five
RSU stations are set up at intervals of 250 meters, ranging from 1 meter to 1,000 meters. We used the media
access control (MAC) protocol 802.11p. Ad hoc on-demand distance vector (AODV) is used the routing
protocols. Table 2 shows the degree of fluctuation of noise factors.
Table 1. Level of variations of control factors
Parameters Low High
wifiPreambleMode Long Short
SlotTime 5 µs 25 µs
rtsThresholdBytes 500 with rts 2346 without rts/cts
minSuccessThreshold 5 20
successCoef 2.0 8.0
Table 2. Levels of variations for noise factors
Parameters 1 2 3 4 5
Packet size (KB) 25 50 75 100 125
Number of Vehicles 10 20 30 40 50
3. RESEARCH METHOD
The OMNeT++ 4.6 simulator is used to conduct the experiments [15]. This open-source software is
categorized as a software-defined network (SDN), which enables system network framework optimization

2209
through design based on user perception of the proposed framework. The INET framework [23], [24], and
INET-MANET [25] of the OMNeT++ serve as the foundation for all MAC and routing protocols.
The input data used to evaluate the traffic generator is user datagram protocol (UDP). During the
250 simulated seconds, the simulation scenario was carried out in a setting with wireless vehicular mobility
and the generation of three random seeds. Table 3 displays the fundamental simulation setup parameters and
Figure 3 shows the VANETs base station module implementing the AODV routing for 802.11p wireless [13].
Table 3. Experimental parameter sets
Parameter Values
Number of vehicles 60
Number of RSUs 5
Simulation times 250s
Traffic type UDP
Routing protocol AODV
.bitrate 27Mbps
.wlan IEEE 802.11p
.message length 512 bytes
Random Number Generator 3 [15]
Figure 3. VANETs base station module implementing the AODV routing for 802.11p wireless
An .ini file would be used to use and set the necessary parameters of the simulation modules in this
network as well as other simulation components, such as bit rate, rate limit, mobility speed, and transmit
interval, as shown in Figure 2. To establish and develop a hierarchy style, single modules like relay units are
connected via gates and merged to produce a compound module.
3.1. Analysis phase
For each experiment under testing, the signal-to-noise (SN) ratio must be computed in order to
ascertain the impact each factor has on the output. The SN value reveals the difference between an
experimental process's mean and its variance. The following SN ratio, known as the larger-the-better ratio,
should be determined in the scenario where performance parameters are to be maximized:
𝑆𝑁𝑖 = −10𝑙𝑜𝑔 [
1
𝑁𝑖
∑
1
𝑦𝑢
2
𝑁𝑖
𝑢=1 ] (1)

 ISSN: 2088-8708
2210
regarding the nominal-the-best scenario, this is when a particular value is most desirable. Following are the
steps to calculate the SN ratio:
𝑆𝑁𝑖 = 10𝑙𝑜𝑔
𝑦
̅𝑖
2
𝑠𝑖
2 (2)
where:
𝑦
̅𝑖 =
1
𝑁𝑖
∑ 𝑦𝑖,𝑢
𝑁𝑖
𝑢=1 (3)
𝑠𝑖
2
=
1
𝑁𝑖−1
∑ (𝑦𝑖,𝑢 − 𝑦
̅𝑖)
𝑁𝑖
𝑢=1 (4)
In the experimental phase, y indicates the mean response of the experiment, i indicates the
experimentation number, u is the trial number and Ni is the number of trials for experiment i. As mentioned
earlier, safety and non-safety applications are the two main attentions in VANETs [1], [12]. Both have
contrast requirements with low-level quality of service (QoS). However, the demands for non-safety
applications are focusing more on throughput sensitivity than delay. Therefore, to acquire the best congestion
management design for VANETs, especially for non-safety applications, it is recommended to take into
account the larger-the-better performance metric for both PDR and throughput sensitivity. The performance
indicators being assessed in this research are PDR and throughput.
4. RESULTS AND DISCUSSION
This section explained the results of the research and at the same time it provides a comprehensive
discussion. Performance of the PDR and throughput of the proposed work is observed. It is evaluated for
before and after optimization. The result is shown in Figures 4(a) and 4(b).
(a)
(b)
Figure 4. PDR performance of congestion control framework for optimization of AODV routing over
VANETs (a) ratio before (oRIN) and after (inHAN) and (b) percentage for before (oRIN) and after (inHAN)
0,17
0,19
0,21
0,23
25 50 75 100 125
Ratio
Data size (KB)
PDR
inHAN
oRIN
0
2
4
6
8
10
12
25 50 75 100 125
Percentage
(%)
Data size (KB)
PDR in %

2211
Figure 4 shows the accuracy and completeness of the VANETs' AODV congestion control protocol
architecture for non-safety or multimedia applications after optimization. Based on Table 4, there is an
improvement following optimization that, according to the average PDR, is about 8.5 percent. As a result,
packet loss is also decreased. Given that the updated AODV protocol reduces the latency of routing activity
from the source to the destination, the PDR is on a declining trend starting at 25 KB and is lower for a certain
period of time.
In principle, the AODV protocol's properties for congestion control on multimedia applications
demonstrate viability impact on PDR of VANETs. The PDR decreases when there is a significant rise in data
traffic activity, topological changes, and broken links to the following hops or transmissions because data
size increases at intervals of 25 to 125 KB. The graphs in Figure 4 and Table 4 demonstrate the mean S/N
greater is better to produce the best and highest PDR with the best fit parameter setting through the parameter
screening stage, based on the Taguchi design.
When we choose data size as our primary requirement in a high static and dynamic environment, the
corresponding framework performs better in terms of bandwidth efficiency after optimization. Compared to
the previous optimization, Figures 5(a) and 5(b) demonstrates successful data transmission to the intended
recipient (throughput). Shorter hops and the basic route recovery failure phase of AODV in vehicle ad hoc
networks both contributed to an increase in throughput.
According to Table 4, the average throughput improved after optimization by about 11.93%.
Additionally, there is less packet loss. Since the updated AODV protocol reduces the delay of routing
activities from the source to the destination, the throughput is on the rise and is at a high level for a specific
time starting at 50 KB.
Table 4. Normalization percentage of congestion improvement
Data Size 25 50 75 100 125 Average
PDR 9.24 10.02 8.74 5.56 8.99 8.51
Throughput 19.95 19.30 4.51 8.58 7.33 11.93
(a)
(b)
Figure 5. Performance throughput for congestion control framework (a) before (oRIN) and after (inHAN)
optimization of AODV routing over VANETs, and (b) performance percentage of throughput for before and
after optimization of AODV routing over VANETs
200000
400000
600000
800000
25 50 75 100 125
Bps
Data size (KB)
THROUGHPUT
inHAN
oRIN
0
5
10
15
20
25
25 50 75 100 125
Percentage
(%)
Data size (KB)
THROUGHTPUT IN %

 ISSN: 2088-8708
2212
5. CONCLUSION
The performance of VANETs for non-safety or multimedia applications is influenced by a variety of
direct and indirect variables. These elements can be divided into two groups: noise factors and planned or
control elements. For a wide range of design elements, including MAC protocols, routing protocols, network
architecture, and situations, a robust optimization technique is needed. In order to increase the proportion of
congestion control for throughput and PDR, or in other words, multimedia applications in VANETs, this
article developed the Taguchi optimization approach.
In this study, two control parameters and three noise factors were taken into account. The variables
are optimum for packet delivery ratio and throughput. The greatest rank value between two performances
revealed the various aspects when they were examined. A tested factor in increasing network throughput and
PDR is data size. Performance in terms of throughput is significantly impacted by RSU distance, although
PDR is less affected. As a result, the data size, which is one of the key controlling parameters in this
experiment, is significantly impacted by non-safety or multimedia applications that are throughput and PDR
sensitive. It is advised that more parameters be investigated or included in future work for non-safety
applications when optimizing congestion control for VANETs.
ACKNOWLEDGEMENTS
The authors wish to thank Universiti Teknologi MARA, Malaysia and Ministry of Higher Education
of Malaysia for funding this research.
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BIOGRAPHIES OF AUTHORS
Shahirah Mohamed Hatim is an academia at the Faculty of Computer and
Mathematical Sciences Universiti Perak Branch Tapah Campus, Perak, Malaysia. Her research
interests include internet of vehicles (IoV), internet of things (IoT) and artificial intelligence
algorithms. She is a member of IEEE and currently pursuing her PhD in Computer Science
focusing on Vehicular Adhoc Communication. She can be contacted at email:
shahirah88@uitm.edu.my.
Haryani Haron is a Professor in Computer Science with Universiti Teknologi
MARA (UiTM) since 2018. She is currently the Dean of the Faculty of Computer and
Mathematical Sciences, UiTM. She has authored or co-authored more than 100 refereed
journals, conference papers, and book chapters. Her research interests include the applications
of knowledge management, data analytics, and technology foresight. She can be contacted at
email: harya265@uitm.edu.my.
Shamsul Jamel Elias is a lecturer at the Universiti Teknologi MARA Kedah
Branch, Malaysia. His expertise areas are vehicular ad hoc network and performance
evaluation in congestion control mechanisms. He is a senior member of IEEE and a member
of IAENG. He has published his research results in conferences and journals. He can be
reached at email: shamsulje@uitm.edu.my.
Nor Shahniza Kamal Bashah is an Associate Professor at the Faculty of
Computer and Mathematical Sciences, Universiti Teknologi MARA, Malaysia. Her research
interest involved in the field of Mobile and Wireless Communication and Semantic Web. She
can be contacted at shahniza@uitm.edu.my.

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