Author Guidelines sample

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Connectivity Analysis in Vehicular Ad-hoc Network

based on VDTN

Ahmed Ali Hussein, and Dhari Ali Mahmood

Abstract— In the last decade, user demand has been increasing

exponentially based on modern communication systems. One of

these new technologies is known as mobile ad-hoc networking

(MANET). One part of MANET is called a vehicular ad-hoc

network (VANET). It has different types such as vehicle-to-

vehicle (V2V), vehicular delay-tolerant networks, and vehicle-to-

infrastructure (V2I). To provide sufficient quality of

communication service in the Vehicular Delay-Tolerant Network

(VDTN), it is important to present a comprehensive survey that

shows the challenges and limitations of VANET. In this paper, we

focus on one type of VANET, which is known as VDTNs. To

investigate realistic communication systems based on VANET, we

considered intelligent transportation systems (ITSs) and the

possibility of replacing the roadside unit with VDTN. Many

factors can affect the message propagation delay. When road-side

units (RSUs) are present, which leads to an increase in the

message delivery efficiency since RSUs can collaborate with

vehicles on the road to increase the throughput of the network,

we propose new methods based on environment and vehicle

traffic and present a comprehensive evaluation of the newly

suggested VDTN routing method. Furthermore, challenges and

prospects are presented to stimulate interest in the scientific

community.

Index

terms—VANET,

VDTN,

RSU,

Intelligent

transportation

systems,

Vehicle-to-Vehicle,

Vehicle-to-

Infrastructure.

I. INTRODUCTION

Vehicle networks such as the Vehicular Ad-Hoc Network

(VANET) or Vehicular Delay Tolerant Network (VDTN)

offer substantially higher bandwidth. This article focuses on

traditional vehicular ad hoc networks (VANETs), which

connect vehicles to infrastructure such as roadside. This type

of communication aims to improve non-safety and safety

applications in vehicles on the road. The primary goal of using

VANET is to handle accidents on the road.

The VANET have a wide range of applications for human

safety including assisting to drive safely on the roads. The

accidents are becoming more frequent with an increase in

vehicle numbers; hence, it is critical for the vehicles to get the

VANET system incorporated [1]. The high mobility of

Manuscript received January 19, 2023; revised March 29, 2023. Date of

publication June 12, 2023. Date of current version June 12, 2023. The

associate editor prof. Adriana Lipovac has been coordinating the review of

this manuscript and approved it for publication.

Authors are with the Department of Computer Engineering, University of

Technology,

Iraq

(e-mails:

ce.20.07@grad.uotechnology.edu.iq,

dhari.a.mahmood@uotechnology.edu.iq).

Digital Object Identifier (DOI): 10.24138/jcomss-2022-0166

vehicles on highways might lead to varying delays and losses

in communication and limiting the deployment of VANETs

[2]. For the problems and challenges of VANET, such as

sparse connections, irregular connectivity, high latency, longer

delay, high error rates, asymmetrical data rates, and no end-to-

end connection, , the Delay Tolerant Networks (DTNs)

technology can be used, which is a type of network that allows

communication in environments with this problem [3].

The DTN routing protocols can be used in an environment

that is confident in delivering packets to their destinations

without regard for network delay. DTN does not require a high

density of nodes to complete communication. Vehicle

networks have a highly dynamic structure and inconsistent and

disruptive connectivity. Hence, a complete route usually does

not exist in such networks.

VDTN develops technology to address these connection

problems and it is based on bundle-oriented connectivity,

asynchronous forwarding, and a store-carry mechanism.

Moreover, this technology must utilize the most available

resources at network nodes to establish a multi-hop route [4].

With connections sparse and intermittent, the routing protocols

attempt to address those difficulties, which have grown from

basic to the most complex regarding message replication

strategies as well as clearing networks for duplicate messages

that the final destination has already delivered [5].

At night, fewer vehicles run on highways or even in cities,

so creating end-to-end paths may be unfeasible. In such

instances, routing in sparse networks must be considered.

Networks will typically be sparse in the early phases of

vehicular networks when a small number of vehicles are

outfitted with radio transceivers [6].

As we mentioned earlier, because of the high driving

velocities of vehicles, the fundamental problem in transmitting

safety-critical messages is that the required latency is less than

100 milliseconds. As a result, safety messages must be

broadcast as soon as possible. Otherwise, the significance of

these messages will be lost. VANET latency should be

reduced; for that reason, use an RSU may connect with cars

through V2I communication while communicating with the

leading network via a high-speed backhaul link [7].

A. RSU Deployment

RSUs come in two types: connected RSUs with a direct

communication route between them, and disconnected RSUs

that cannot communicate with one another [8]. The

deployment of RSUs throughout the city can enable the real-

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Original scientific article

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time and reliable transfer of emergency traffic information

over VANET [9].

RSUs are major components in vehicle ad-hoc networks

because they send an alarm message from the accident area to

the central controller when it is available. It is impossible to

implement RSU widely because of high costs and market

demand. As a result, determining how to deploy the lowest

percentage of RSUs in a specific area becomes a difficult

challenge [10]. Therefore, many researchers have investigated

the best locations for RSU on roads. RSU placement is defined

as identifying the appropriate combination of RSUs in a

specific target region based on the criteria to meet the

specified goals, such as the best connection, coverage, and low

installation cost [11].

Due to the high installation costs, it difficult to deploy a

large number of RSUs at the early stage of VAENT. The

author in [12] analyzed the RSU deployment method for

vehicular communications in a highway environment and each

vehicle may reach an RSU in two modes: direct access and

multi-hop relaying. There was a comparison of two different

RSU distribution systems. The first is the improved Delay

Minimization Problem (DMP) instance, while the second is

the uniform distribution. This suggested model outperforms

uniform distribution in virtually all circumstances, according

to simulation findings. The DMP model recommends the

optimum RSU deployment approach while keeping the entire

deployment budget in mind, so that the network aggregate

latency is reduced. This increases in the network overall

throughput. In vehicle applications, RSUs are important for

routing, connection, and packet delay. Therefore, installing

sufficient RSUs to achieve universal coverage in a given

region is impossible.

While the author in [13] suggests a safety-based roadside

unit placement strategy to reduce message dissemination

delays in scenarios where stand-alone RSUs are deployed. The

suggested S-BRP method minimizes dissemination latency

and improves mesh policy regarding traffic flow following

accidents. RSUs are expensive and will be in short supply for

a longer period of time as VANETs are gradually deployed.

The author in [14] provides an innovative and powerful

RSU Deployment Problem Model (RDPM) comprised of a

road-network model and a business model. The road network

model in RDPM allows complex road designs while

considering major relevant elements such as lane number and

popularity. Also, the work suggested a genetic algorithm-

based technique to handle an RDPM problem a priori since the

best RSU deployment solution is challenging to find.

This paper proposes a new method to replace RSU with

VDTN and evaluate VDTN routing algorithms by giving a

performance review and a statistical comparison of the

effective VDTN routing protocol and finding the best scenario

depending on the network environment and the traffic vehicle.

We anticipate increasing the use of VDTN due to the high

cost of deploying RSU and difficulties of installing it in some

areas, as well as the high mobility of vehicles, which leads to

frequent network disconnections and the loss in packets.

However, using VDTN, the packet will store, carried, and

forwarded as soon as the connection restoration so that the

packet will reach the next recipient with a tolerant delay. In

some cases where RSUs are already on the road, our method

can be utilized these RSUs as fixed DTNs to store packets.

The fixed DTN technique provides some benefits, such as

collecting data and disseminating the information obtained

from the coverage region.

The remainder of the paper is organized as follows. Section

II shows problem statement and III gives a brief outline of the

VANET. In section IV, a detailed description of the

environment is given. It was followed by section V in which

DTN technique is showed. Section VI descripts in detail the

VDTN, while section VII shows cluster routing. Methodology

and routing schemes are shown in section VIII. Section IX

shows the results of the analysis. Finally, concluding remarks

are provided in section X.

II. PROBLEM STATEMENT

Since RSU installation and maintenance are expensive,

deploying a limited number while ensuring outstanding

network performance is a significant difficulty. VANETs

present various obstacles for RSU installation with regards to

data distribution, packet routing, and connection to the

network, and coverage needed to provide such performance.

However, coverage is one of the primary performance

indicators used to analyze the quality of service provided on a

network.

The primary purpose of the optimization is to establish a

balance between network coverage and pricing. RSU

distribution is represented as a restricted optimization process

with numerous goals such as enhancing network coverage,

optimizing network connections, and decreasing the costs of

RSU implementation. We can generally discover many

suitable subsets of localities for installing RSUs within a

geographic region [11].

RSUs have limitations in terms of their coverage area, and

the number of RSUs deployed may not be sufficient to provide

complete coverage over long stretches of highway. In such

cases, the VDTN approach can be useful, as it provides a way

to overcome the challenges posed by intermittent network

connectivity in sparse or disconnected networks.

III. OVERVIEW OF VANET

VANETs are simply a group of vehicles and RSUs. It’s

identical to MANET up of vehicles and RSUs. Protocols and

tools designed for MANETs cannot be immediately linked to

field VANETs since they must be upgraded to meet the mobile

ad-hoc as well as the operational needs of vehicles.

VANET is an infrastructure-free network without a

predefined architecture via which vehicles can interact.

Because all nodes are allowed to migrate and form their own

networks, they are referred to as "wireless ad-hoc networks."

VANET employs dedicated short-range communication

(DSRC) based on IEEE 802.11p wireless technology, a multi-

hop connection technique that uses geopolitical location to

enable information sharing among network elements [15].

148

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A. Type of Connection in VANET

Many types of communication exist in VANET

technologies, which are:

A.1. Inter-Vehicle Communication

Direct connection between vehicles occurs in this form,

making it rapid, cost-effective, as well as accurate. Wireless

technologies have a limited range such as Wi-Fi as well as

Wireless Access in Vehicular Environment make this possible.

Vehicle is outfitted by specialized electrical devices that allow

them to receive and deliver communications [16].

A.2. Vehicle to Infrastructure Communication

In contrast to the V2V communication paradigm, which

only allows information to be sent between vehicles, the V2I

communication model allows vehicles in transit to interact

with the road system. RFID readers, traffic signals, cameras,

lane markings, street lighting, signage, and parking meters are

among the components. V2I communication is often wireless,

and bidirectional and like V2V use Dedicated Short-Range

Communication (DSRC) frequencies to convey data. This data

is transmitted from infrastructure elements to vehicles, or vice

versa, over an ad hoc network. V2I sensors in ITS may collect

infrastructure data and give real-time advice to passengers,

transmitting data on road conditions, traffic congestion, any

accidents on the road, the presence of building sites, as well as

the availability of parking [17].

A.3. Hybrid Communication

Inter-road communication often mixed both V2V and V2I

connections such as a schema, the car connects with the

roadside unit and exchanges data obtained by infrastructure

with the other cars. Because there isn’t an immediate

connection among them a specialized protocol is utilized for

passing packets through one vehicle to the next until it arrives

at its destination, establishing many hops in vehicle-to-vehicle

connection. Vehicles, in contrast, RSU use to extend

communication, forwarding and transferring data from one to

another node, or gain from RSU capacity to perform specific

applications, establishing V2I communication [18].

B. Challenges of VANET

There are many challenges in a vehicle network, which

varies from typical ad-hoc networks because of the high

degree of mobility, changeable network architecture, network

segmentation, density of nodes, non-persistent connectivity,

and so on. Variations in vehicular density are caused by

factors such as vehicle speed, driver behavior, road conditions,

and traffic congestion. As the density changes, various related

issues occur, resulting in the establishment of dynamic needs

and limits for parameters like connection, bandwidth, data

rate, and so on.

Existing vehicular network architectures are scalable

because they enable ad-hoc, cellular networks, and roadside

units. Many services are provided by these designs, including

intra- and inter-vehicular communication, vehicle-to-vehicle

communication, roadside units, and vehicle service [19].

Recent routing has additional problems and challenges in

terms of scalability, QoS, security and privacy, energy usage,

bandwidth constraints, and broadcasting [20].

If compared with other kinds of MANETs, VANET has

distinct properties that impact the architecture of the

communication network or its routing protocols. Following are

the distinctive characteristics of VANET:

1. High Dynamic of Topology: This is produced by high-

vehicle speeds, particularly on highways [21].

2. Varying network density: The traffic volume in VANET

is not uniform throughout the day and in all environments;

it could be higher during peak hours and during traffic

jams in cities, average at other times, or extremely low as

in rural transportation [21].

3. Patterns of Movement: VANET can distinguish by

possibly a large number of mobile nodes. That high

mobility may be necessary because of the type of routes

(highways, RSUs, and tiny streets). The cars do not drive

randomly; instead, they most likely go in two directions

on established roadways [22].

4. Frequent information exchange: The ad-hoc structure of

VANET encourages nodes to acquire information from

other vehicles and roadside units. As a result, information

sharing between vehicles becomes more common [23].

5. Frequent disconnected of network: In the VANET, The

rapid speed of the cars displays the dynamic topology of

networks since the connection that connects two

communicating vehicles is frequently interrupted, which

is known as intermittent connectivity [23].

C. Components of VANET

1. On-Board Unit (OBU): is a piece of hardware that is put

across every vehicle. The main purpose of an OBU is to

allow communication between RSUs and many other

OBUs inside vehicles. It also has a transceiver, which is

comparable to a radio frequency antenna [24].

2. Road Side Unit (RSUs): embody an antenna, a read/write

memory architecture, as well as a processor. RSUs are

equipped with Interfaces, both wired and wireless. These

units are typically built along roadways. They are also

seen in high-traffic places like crossroads and parking

lots. There are experiments to optimize RSU location

regarding coverage range, data aggregation, and delay

management [24].

D. Routing Protocol in VANET

In VANET, the protocols could be categorized into two

types: position-based routing protocols and topology-based

routing protocols. Fig. 1 [25] illustrates the types of protocols

in VANET. They are classified according to the region and

application for which they are most suited. Protocols based on

topology are divided into three types: proactive, reactive, and

hybrid [26].

D.1 Proactive Protocols

The routing table updates or refreshes often because the

protocols compute the route on a constant schedule; those

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protocols use the Bellman-Ford Process, nodes store

information about the next node. Protocol examples for this

type are Destination Sequenced Distance Vector (DSDV).

Optimized Link State Routing (OLSR).

Fig. 1. Routing protocol in VANET [25].

DSDV is a renowned proactive or table-driven routing

technology in MANET. The DSDV routing method is defined

by the number of hops required to reach the target node,

DSDV protocol uses routing tables maintained in each node to

send data packets throughout the network, DSDV protocol has

three key aspects: reducing the huge routing expense,

avoidance of loops and solving the count to infinity challenge.

Every mobile node has a routing information table that

contains all the routes to destinations as well as other

information [27].

OLSR would optimize the process of broadcasting control

messages to decrease bandwidth usage by utilizing multipoint-

relays (MPR). At broadcasting, each node joins a selection of

its surrounding nodes to send its packet. According to the

MPR distribution approach, every node in the network

obtained the fewest repeats. MPR prevents a subset of nodes

from retransmitting a message to remaining nodes and makes

network topology determines the size of the subgroup [28].

D.2 Reactive Protocols

This protocol does not include knowledge about most of the

nodes. It simply saves the information of nodes that pass

through it. Ad-hoc On-Demand Distance Vector (AODV),

Dynamic Source Control Routing (DSR), and Dynamic

MANET on Demand (DYMO) protocols are examples of this

type.

AODV uses a dynamic source routing technique for route

discovery and management, as well as Sequence numbers and

sequential hop routing. AODV constructs route by executing

“route request/route reply” queries [28].

DSR is one type of reactive routing protocol that is launched

by the originating node of the network. Every packet in this

protocol transports all routing packets and data to all

surrounding nodes, which means increased traffic that is

unsuitable for massive networks. The degree of the operating

protocol overhead grows with network size as measured by the

number of nodes, consuming extra bandwidth in high-traffic

areas with more extensive networks than that in tiny as well as

inactive networks. Although, compared with AODV, this

protocol has a significant advantage in small networks, it may

perform exceptionally well in tiny networks. One of the

benefits of this protocol is that it saves and uses the routing

data saved in the protocol route cache, which is used when

searching for the following route from the root to the last

network node because the route cache includes data on

numerous routes between both pairs of nodes [29].

The DYMO routing protocol is the replacement for AODV

and works in the same way. DYMO has no additional features,

nor is it an extended version of the AODV protocol; instead,

the DYMO routing protocol streamlines AODV by preserving

the primary operation mode necessary to achieve efficient

routing, which is enhanced because it saves each intermediary

hop route, whereas AODV produces entries at the table of

routing and nodes for the destination and following hop [30].

TABLE I

COMPARISON ROUTING PROTOCOL IN VANET

Title

Year

Techniques

Protocol

Type

Performance

Parameters

[32]

2020 ANN, and SVM

Clustering PDR,

and

throughput

[33]

2020 PSO

Geocast

PDR,

throughput,

delay, NRL,

and packet

drop ratio

[34]

2019 GA, and K-

means clustering

Hybrid

Link

reliability

[35]

2019 ABC

Clustering Delay, PDR,

NRL,

and

packet drop

ratio

[36]

2018 SA, and Radial

Basis Function

(RBF)

Neural

Network

Clustering PDR,

throughput,

route

discovery

ratio,

and

NoC

[37]

2018 ACO

Geography PDR,

and

delay

[38]

2019 ACO

Geography PDR, control

packet rate,

and delay

[39]

2019 Artificial Spider-

Web

Geography &

PDR,

routing

overhead, and

delay

[40]

2018 GA

Geography Delay, and

PDR

[41]

2018 PSO

Topology

Packet loss,

PDR, NLR,

and delay

[42]

2018 Taguchi

Optimization

Topology

Delay, PDR,

and

throughput

[43]

2020 Improved Water

Wave

Optimization,

and

Rider

Optimization

Clustering Cluster

overhead,

routing

overhead,

PDR, packet

drop ratio,

throughput,

delay,

and

network

lifetime

[44]

2020 PSO

Clustering PDR,

and

delay

150

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D.3 Hybrid Protocols

This routing strategy is a hybrid of proactive and reactive

routing techniques that decrease delays and overhead that

caused by the continuous exchange of topological. The

network efficiency and scalability have increased thanks to the

hybrid approach. The disadvantage of a hybrid strategy, on the

other side, is excessive latency while traveling new routes.

Zone Routing Protocol (ZRP) is a typical protocol that uses a

hybrid method.

ZRP is designed for wide area networks and uses query-

reply to create routes. It employs Interzone and Intrazone

routing to allow elastic finding of a route with management in

various ad hoc contexts. Interzone routing is handled

worldwide via the reactive routing protocol, whereas intrazone

routing is performed locally via the proactive routing protocol

to retain up-to-date route information [31]. Table I

summarizes some protocols developed in the VANET

environment.

E. MAC Layer in VANET

The MAC layer in VANETs can be implemented through

various mechanisms. Such as the Carrier Sense Multiple

Access with Collision Avoidance (CSMA/CA) protocol,

known as the IEEE 802.11p standard. This protocol is

designed to allow multiple vehicles to share the wireless

channel, while avoiding collisions and minimizing delays.

Here are some of the ways in which the MAC layer can be

applied:

1. Beaconing is a technique used in VANETs to disseminate

information about the network and the surrounding

environment. Vehicles periodically transmit beacons

containing information such as location, speed, and

direction of travel.

2. Quality of Service (QoS) provisioning is essential for

VANETs to support different types of applications with

varying bandwidth, latency, and reliability requirements.

The MAC layer can be used to allocate resources and

prioritize traffic based on the QoS requirements of

different applications

In order to adjust to the variety in node density and

contention severity in VANET, an adaptive mobility variation

of RR-ALOHA is presented by the [45]. The suggested

schema performs better than RR-ALOHA in several ways by

including CSMA into the slot and entirely using the 3-hops

channel state. The NS-2 simulation demonstrates that the

innovative protocol enhances the quality and speed of Basic

Channel (BCH) reservations. The author in [46] Work on

increase the effectiveness of controlling packet collisions

brought on by rapid mobility in VANETs by extending the R-

ALOHA reservation scheme. Terminals have several

opportunities every frame to assess timeslot availability inside

the two-hop neighborhood because of the architecture of

frames with many brief BTSFs. Channel access is thus quicker

and more dependable, and mishaps may be recovered more

quickly. The suggested protocol's faster channel estimation

quickly recovers all reservation losses by rapid network

mobility and improves network mobility handling.

IV. ENVIRONMENT

Vehicle networks work and apply in many environments;

some are high or medium density, while others low. The

density depends Poisson vehicle arrival process, with arrival

rate λ (vehicles/second) Different arrival rate values are

considered, λ ϵ {0.45, 0.65, 0.95} in this case setting the mean

arrival rate to a low value leads to very short clusters, that

mostly consist of isolated vehicles. On the other hand, by

setting it too high, almost all vehicles will be connected into a

single cluster.

Also, many other vectors affect environment classification,

such as the type of area, which is rural or urban, and the time

for measuring the density, which is during the morning peak

or during the evening when the traffic low. In this part, we

provide three categories of density, which are listed below

[47]:

A. Sparse Network

Arrival rates differ during the day, and depending on the

vehicle's arrival, all are exponentially distributed when λ is

low (0 – 0.45). We call this network sparse, and in this type of

network, the connection between vehicles will be poor when

we need to propagate messages to all other vehicles on the

road, so in this environment, we need to consider some

solution to ensure some of the vehicles at least receive the

message, such as using VDTN, which means it is possible to

create connections in case (V2V). This network has a small

number of nodes and a minimal network architecture. As a

result, it is possible that not all nodes have communication

link.

B. Semi-sparse Network

As mentioned earlier, the density depends on arrival rate λ

(vehicles/second), and when it is around (0.46 – 0.65), we call

this network semi-sparse. In this network, the connection can

apply VDTN and also use Roadside unit (V2V), (V2R).These

networks feature further nodes and connections than sparse

networks. For example, a small or developed town close to the

city has an extra significant number of mobility nodes and

base stations providing internet access. Consequently, the

possibility of contact between mobile nodes is more

significant than in a sparse network and data may be sent with

lower latency than in the sparse network.

C. Density Network

In this type of environment, when the arrival rate is high

(0.95), most of the vehicles be in one cluster, and the messages

will arrive to all vehicles, so we will not need to apply VDTN

because the link will not break and can use all connect (V2V)

(V2I) (V2R). Almost nodes in this network are linked

together; there will be a lot of traffic and strain, network nodes

have a high probability of contacting one another. A smart city

is an instance of a dense network in which numerous

heterogeneous nodes are installed and can communicate with

one another.

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V. DELAY-TOLERANT NETWORK (DTN)

Due to changes in the arrival rate and topology of the

vehicle's network, some network spares and link end to end

are not found, as mentioned in section IV, so we can apply

DTN. This architecture implements store-and-forward concept

by superimposing a protocol layer called a bundle layer. This

new layer is intended to offer internetworking on

heterogeneous networks that use various transmission

modalities. A source node creates and stores a bundle in this

network when contact is unavailable. When the source node

contacts an intermediate node considered to be closer to the

target node, the package has been delivered. After that, the

intermediate node stores the bundle and transports it until a

new contact becomes available. Such a step is repeated till the

package arrives at its receiver. Bundles have a limited lifespan

and might be dropped due to buffer overflow [48].

A. Bundle Protocol

The purpose of the DTN bundle protocol is to facilitate

communication in difficult circumstances. It is based on a new

bundle layer, which is put between the application and

transport layers as shown in fig 2. Bundled protocol

connections to lower levels are known as "convergence layer

adapters." It is critical to emphasize that the bundle protocol

does not really need to be installed across all nodes in the

network except termination points and a few selected

transitional nodes [49].

The bundle custom features an overlay network that has the

following benefits [50]:

1) Capability to tolerate intermittent connection.

2) Capability to benefit from planned, opportunistic, and

expected connections.

3) Retransmission depending on custody.

Fig. 2. DTN architecture

B. Store Carry and Forward

In contrast to the Internet technique, which is built on the

store and forward assumption, the DTN uses new design

which includes store, carry, and forward paradigms. This

approach allows intermediate nodes to keep bundles in their

buffers for a long amount of time, while waiting for the chance

to connect with the next node until the packet arrives at its

destination or its time to live ends [51]. DTN node is

accountable for the bundles it transports till they are delivered

or sent to other DTN node. Often that it’s advantageous for a

DTN node to delegate responsibility for replicating,

modifying, or deleting its transported bundles to another node.

[52].

C. Challenges in DTN

DTN has several difficulties like routing algorithms, flow

control, congestion control, and architecture. These difficulties

have a severe impact on DTN performance. These

circumstances, however, should not affect the DTN efficiency

or performance in [50] briefly explain some of them:

1) Limited buffer size: Because of frequent disconnection,

a huge number of packets are stored in the nodes

custody.

2) Very lengthy delays: Latencies can be greater and

transmission rates which be poorer at times.

3) Connection based on opportunity: Communication is

occurring in an ad hoc fashion. As a result, the quantity

of data that may be communicated is limited.

4) Disconnections occur frequently: It is challenging to

estimate once the next node would be ready for

broadcast because node debate is more frequent than

node connection due to the significant delays between

nodes.

VI. VEHICULAR DELAY-TOLERANT NETWORK (VDTN)

VDTN is a type of DTN that provides authoritative and

effective connections. Different routing methods which

already employed in VDTN to improve network performance

in terms of sending information in the form of packets to their

desired locations [53]. Using the VDTN technique reduces

dependence on RSU, which is high cost and low effectiveness

in some environments like a sparse network or using the

hybrid technique (VDTN and RSU) in other types of networks

such as semi-sparse, as mentioned in section IV. A and B.

A. Characteristics of VDTN

The geographic position, density of nodes, buffer size,

target utility, buffer capacity, relay functionality, meeting

prediction, and other indicators are used to make routing

decisions in VDTN [54]. It is a modern topology comprised of

three node types: terminals, relays, and node mobility.

Terminal nodes are stationary or mobile nodes that can be the

data source or destination. They will provide crucial

information regarding road and weather conditions

(entertainment and traffic jams). Relay nodes are static nodes

with store-and-forward capabilities strategically placed at

intersections. Mobile nodes are responsible for physically

transporting and forwarding packages from the origin to the

destination nodes. As a result, offering a unique routing

mechanism enhances the performance of the VDTN, conveys

messages more efficiently, and increases the life span of the

network [55].

VDTN employs nodes of vehicles to carry packets because it

provides for limited opportunistic connections and is

characterized by a low value of density, intermittent vehicular

activity, and no edge connectivity among nodes. The [56]

offers DesCom, a routing protocol for VDTNs in a highly

restricted and sparsely populated environment. This protocol

bases its choice on the transmission rate, message TTL, and

estimation time. Some of the protocols used in the VDTN are

summarized in Table II.

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TABLE II

COMPARISON ROUTING PROTOCOL IN VDTN

Protocol Environment

Scenario

Target of Protocol Performance

Parameters

REMA

[57]

urban, city

The work

proposes a VDTN

resource

management

system.

Reduces lost in

resources, raises the

bundle

delivery

ratio, and minimizes

the

ratio

overhead.

GeoDTC

[58]

Realistic

simulation

environment,

city

Presented a

comprehensive

analysis to

evaluate this

protocol

Performs

show

benefits of extensive

use

Custody

Transfer.

SNHD

[59]

Smart city

Evaluate

this

protocol against

well-known

protocols of DTN

Protocol

outperforms well-

known

DTN

protocols.

DSO [60] Rural areas

communicate in

rural areas using

cellular network

Increased

data

delivery and an

increased delivery

completion rate with

fewer

delivery

delays.

EPRIVO

[61]

Different

scenarios

Evaluation

the

packet size, the

ratio of overhead,

average delay

It has very cheap

cryptographic costs

general.

Furthermore,

displays

average

improvements ratio

of delivery

MACBS

A [62]

urban

scenarios

create intelligent

transportation

networks

Increase network

quality

and

efficiently utilizing

system resources.

MOPSO

[63]

VDTN

scenario

Strategies

for

reducing traffic

congestion.

Utilizing

the

artificial intelligence

method.

B. Challenges in Designing VDTN

While developing the VDTN routing scheme, we

encountered the following difficulties [64]:

1. Data transfer is incomplete when the transmitter and

receiver are within each other interface range, data

transmission occurs in any way (X2V, V2V, or V2X). As

a result, to finish the data transmission, the receiver must

remain in the connection range for the transfer duration.

2. Drop a high number of packets directly impacting the

routing protocol efficiency. Also, a few packets may be

dropped during communication due to a temporary

technical problem. With regular packet drops, unwanted

packet drops are unlikely to occur because the relay node

may drop packets unintentionally owing to route changes

or other issues.

C. Buffer Issue

DTNs method demands that the bundle be saved in the

nodes. As a result, routing protocols must understand how to

manage buffer consumption to prevent many needless bundle

copies from circulating at intermediate network nodes. This

matter occurs with the routing system, where the overhead of

bundles in the network is substantial, rendering it unscalable

[65].

VII. CLUSTER ROUTING

Clustering is the grouping of vehicles based on correlated

geographic distribution and relative velocity, which can be

utilized to improve routing scalability and reliability in

VANET. Cluster-based systems organize nodes into virtual

groups called "clusters." Geographically adjacent nodes are

placed in the same cluster according to rules. A cluster

typically has three nodes: a cluster head (CH), cluster

members (CM), and gateway nodes. In each cluster, a node is

chosen or elected as a CH, with extra functions like access to

the medium or routing. Clustering appears to be an appealing

contender for VANETs in building scalable and durable

vehicles in the face of high movement and frequent dynamic

topology in VANETs for a variety of reasons. Furthermore,

this method of routing avoids conflicts.

This strategy also has drawbacks. Cluster stability is a

significant problem. Cluster rearrangements and cluster-head

changes are unavoidable in a dynamic environment like

VANET, compromising stability. As a result, the ability to

build stable clusters is one of the most important criteria for

any clustering technology in VANETs [66].

A. Clustering in Vehicle

The vehicles are clustered together with their neighbors.

Automobiles in the same cluster can link in multiple hops.

Vehicle clustering effectively achieves scalability and stability

in network processes and control in a VANET with a large

number of cars. Clusters are often grouped in a continuous line

alongside highways [10].

Whenever vehicles are sufficiently together, only vehicles

in the same cluster can exchange messages. However, because

of the high price, complexity, and non-cooperation between

the government and commercial sectors, RSU implementation

is slow [8]. Fig. 3 illustrates how to use the cluster with RSU

and two lanes. When there are RSUs on the road, a large

enough cluster of cars can fill the gap, moving the message

from RSU to RSU farther away from the sender. The symbols

(U1, U2, and U3) refer to the RSUs scattered along the road. R

denotes the vehicle range, and ˆR denotes the RSU range, the

ˆR ≥ R. The red circle indicates the beginning of the accident

and the start of the message Propagation.

Fig. 3. A snapshot of a road at time t with RSU and informed elements

highlighted in green

Fig. 4 shows how to use the cluster with VDTN, the road

has two lanes. The route can have a single informed cluster

with no RSUs. The system dynamics are simple: at times, only

the static message source is aware of the information. When a

vehicle enters the radio coverage of the sender, the cluster

activated by that vehicle is immediately alerted. However,

there will be no informed vehicles on the road when the last

car in the cluster leaves the message source. From the figure,

we can see a buffer store denoted by black circles inside the

A. A. HUSSEIN et al.: CONNECTIVITY ANALYSIS IN VEHICULAR AD-HOC NETWORK BASED ON VDTN

153

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green area for the message store because the VDTN uses store

carry-forward mechanics to improve communication

efficiency. Therefore, we can replace RSU with VDTN and

get almost the same performance on the road.

Fig. 4. A snapshot of a road at time t with VDTN and informed elements

highlighted in green

A cluster is a group of vehicles formed when these vehicles

are within a specific range at a given time (t), and the cluster is

recreated with the help of the DTN Node (DTN-N) after that

time (t +). With DTN-vehicles, the cluster does not start from

R (the vehicle range), and the packet in this case is still

available because it is held by DTN vehicles, (g) represents

the cluster length. The trajectory of the message propagation

distance, D (t), is depicted in Fig. 5. And due to DNT

techniques, the packet reaches the longest possible distance,

making the message reach the drivers within an acceptable

period. When the message arrives at the right moment, it will

assist drivers in avoiding accidents by allowing them to

choose whether to enter congestion or use a side road. The

slope is equal to the velocity (v), and message dissemination

distance decreases with velocity; the speed of leaving the

cluster is equal to the velocity of the car. And when the last car

in the cluster departs the packet source, there will be no

informed cars on the road.

Fig. 5. Trajectory of the information distance D (t)

VIII. ROUTING SCHEMES

In VANETs, the spectrum of frequency is split into six

channels (SCH) and one control (CCH), all having a 10 MHz

bandwidth. According to the ETSI Research center, every

channel is assigned to a specific application type: 5.855 MHz

to 5.875 MHz is reserved for intelligent transportation

systems, 5.875 MHz to 5.905 MHz is reserved for safety in

addition to ameliorating applications while 5.905 MHz until

5.925 MHz is reserved to future intelligent transportation

systems applications [67].

Fig. 6. Multichannel operations for vehicular ad hoc networks [70].

A. Message

Two categories of applications available: safety and non-

safety as shown in fig. 6. In VANETs, the safety applications

can be used to deliver safety messages, such as warning

messages that aid vehicles on the road so that necessary steps

may be taken to avoid accidents and save persons from

dangerous circumstances, Minimal delay and great reliability

are required for these kinds of safety applications. Road

accident updates, emergency vehicle alerts, traffic jam alerts,

and road construction reports are examples of safety messages

for which it is preferred to use RSU, which gives higher

reliability and faster message transmission, but it has a

drawback.

Therefore, it is possible to exploit the routing protocols for

VDTN to deliver the message through this connection, even if

additional time has passed.

Non-safety applications, on either side, provide a more

efficient and pleasurable driving experience. Two types of

non-safety applications: infotainment and traffic control. This

type of message can use the VDTN routing protocol to provide

the preferred results because it can tolerate delay.

B. Analysis Study

Node density, mobility model, and several other factors all

have a substantial impact on the performance of a routing

protocol in VANETs. As a result, creating an effective routing

system for all VANET application is exceedingly difficult

[26]. Therefor depending on the challenges and environment

that mentioned earlier, can obtain a comprehensive

understanding of the VANET structure. It can use traditional

routing protocols with RSU or DTN routing protocols without

RSU which depending on many vectors such as environment,

network type, and so on.

Our taxonomy applying VDTN or RSU depending on

various factors, which shows in Fig. 7. Vehicle networks have

a highly dynamic network structure with disruptive and

inconsistent connectivity. Therefore, VDTN technology was

developed to address these connection problems.

In general, VDTN is based on bundle-oriented connectivity

and includes asynchronous as well as store-and-forward

routing mechanisms. This technology must utilize the most

available resources at network nodes to establish a multi-hop

route [6]. protocol is used with fewer vehicles running on

rural area or even in cities at night, especially when lack of

end-to-end paths. Even in heavily populated metropolitan

areas, sparse networks might exist.

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Fig. 7. Our taxonomy

VDTN protocols could be employed in high, medium, and

low-density environments and used in the application for non-

safety messages that do not require emergency vehicle alerts

or a pre-exit connection. While RSU can be used for safety

messages because it reduces information delivery time and

loss packets, but it is costly compared to VDTN.

Moreover, based on that comparison, hybrid RSU and VDTN

will have superior performance according to environment as

mention in section IV.C.

IX. ANALYSIS

According to our study analysis on VANET, the main

vectors that should be taken into account when designing

network topology are:

1. Environment has three types of VANET, as mentioned in

section IV. When building network infrastructure, we

should consider which type it is to know communication

use (V2V, V2R, and V2DTN).

2. Type of protocol.

From our study analysis, the VANET has many problems,

such as

1. Message propagation (end-to-end delay).

2. Context-aware navigation for driving safety and collision

avoidance.

3. Cooperative adaptive cruise control in an urban roadway.

4. Platooning on the highway.

5. Cooperative environment sensing.

6. Weather condition.

The proposed DTN Protocol and non-DTN Protocol have

been evaluated for the network of mobile nodes in

comprehensive simulation by utilizing the NS2 Simulators.

Table III lists the simulation parameters that were employed.

The experiments in literature review findings reveal that

DTN routing methods outperform non-DTN routing protocols

regarding throughout and delivery ratio in the spare

environment when the arrival rate λ is low. Therefore, DTN

protocols are better suited for highways due to packet

buffering until an obvious path to a target is available.

However, they cause higher average latency owing to

buffering. In conclusion, non-DTN protocols are better suited

to city environments and network structure alterations are

slower than highways.

TABLE III

SIMULATION PARAMETERS

Simulation

NS2 (Network Simulation

Version 2)

Code

TCL, OTCL and C++

Simulation Time

30. 0 Second

Discovery Routing Time

Start From: 0 sec. To

1.5sec.

Time to Send Package

Start From 1.5sec. To 30sec

Number of Nodes

(10-250) Mobile Node

Interface Priority Queue (Ifq)

Drop Tail

Antenna Model

Omniantenna

Transmission Range of the

Nodes in Cluster

250m

Size of the Message getting

Generated

512 KB

Buffer Size of the Nodes in the

Network

Maximum Packet in Ifq 50

X. CONCLUDING REMARKS

This paper studies the significant technologies, RSU and

VDTN in VANET to achieve the best connectivity for vehicle

networks. Specified problems and limitations of both VDTN

and RSU. VDTN technology can maintain a continuous end-

to-end connection because of the constant movement of nodes.

In contrast, RSUs are expensive and challenging to install

along a road. This study indicates that a specific system

performance depends on the resources and environment in

which it operates. Use RSU for the alert message to ensure

timely packet delivery, while for non-safety messages, use

VDTN, which employs store-and-forward technology. In

Future work, we will implement a scenario on the highway

with a length of 10 km and design a protocol dealing with

high-speed vehicles.

REFERENCES

[1] B. Sharma, M. S. P. Sharma, and R. S. Tomar, "A survey: Issues and

challenges of vehicular ad hoc networks (VANETs)," in Proceedings of

International Conference on Sustainable Computing in Science,

Technology and Management (SUSCOM), Amity University Rajasthan,

Jaipur-India, 2019.

[2] E. Cambruzzi, J.-M. Farines, W. Kraus, and R. Macêdo, "A cluster

management system for VANETs," International Journal of Intelligent

Transportation Systems Research, vol. 14, no. 2, pp. 115-126, 2016.

[3] E. Spaho, L. Barolli, V. Kolici, and A. Lala, "Performance Comparison of

Different Routing Protocols in Sparse and Dense VDTNs," in 2016 IEEE

30th International Conference on Advanced Information Networking and

Applications (AINA), 2016: IEEE, pp. 698-703.

[4] R. K. Agarwal, M. Mathuria, and M. Sharma, "Study of routing

algorithms in DTN enabled vehicular ad-hoc network," International

Journal of Computer Applications, vol. 975, p. 8887, 2017.

[5] N. I. Er, K. Singh, and J.-M. Bonnin, "On the performance of VDTN

routing protocols with V2X communications for data delivery in smart

cities," in IWSSS 2017-2nd International Workshop on Smart Sensing

Systems, 2017, pp. 1-2.

[6] J. Bernsen and D. Manivannan, "Delay-Tolerant Routing Protocols for

Vehicular Ad Hoc Networks: A Critical Comparison and Classification,"

in ICWN, 2008, pp. 149-154.

A. A. HUSSEIN et al.: CONNECTIVITY ANALYSIS IN VEHICULAR AD-HOC NETWORK BASED ON VDTN

155

Page 10

[7] T. Karunathilake and A. Förster, "A Survey on Mobile Road Side Units in

VANETs," Vehicles, vol. 4, no. 2, pp. 482-500, 2022.

[8] D. A. Mahmood and G. Horváth, "Analysis of the message propagation

speed in VANET with disconnected RSUs," Mathematics, vol. 8, no. 5, p.

782, 2020.

[9] Y. Shi, L. Lv, H. Yu, L. Yu, and Z. Zhang, "A center-rule-based

neighborhood search algorithm for roadside units deployment in

emergency scenarios," Mathematics, vol. 8, no. 10, p. 1734, 2020.

[10] C. Liu, H. Huang, and H. Du, "Optimal RSUs deployment with delay

bound along highways in VANET," Journal of Combinatorial

Optimization, vol. 33, no. 4, pp. 1168-1182, 2017.

[11] A. Guerna, S. Bitam, and C. T. Calafate, "Roadside unit deployment in

internet of vehicles systems: a survey," Sensors, vol. 22, no. 9, p. 3190,

2022.

[12] Z. Ahmed, S. Naz, and J. Ahmed, "Minimizing transmission delays in

vehicular ad hoc networks by optimized placement of road-side unit,"

Wireless Networks, vol. 26, no. 4, pp. 2905-2914, 2020.

[13] A. Jalooli, M. Song, and X. Xu, "Delay efficient disconnected rsu

placement algorithm for vanet safety applications," in 2017 IEEE

Wireless Communications and Networking Conference (WCNC), 2017:

IEEE, pp. 1-6.

[14] Z. Gao, D. Chen, N. Yao, Z. Lu, and B. Chen, "A novel problem model

and solution scheme for roadside unit deployment problem in VANETs,"

Wireless Personal Communications, vol. 98, no. 1, pp. 651-663, 2018.

[15] R. J. Mousa, Á. Huszák, and M. A. Salman, "Enhancing vanet

connectivity through a realistic model for rsu deployment on highway," in

Journal of Physics: Conference Series, 2021, vol. 1804, no. 1: IOP

Publishing, p. 012104.

[16] M. Tahira, D. Ather, and A. K. Saxena, "Modeling and Evaluation of

Heterogeneous Networks for VANETs," in 2018 International

Conference on System Modeling & Advancement in Research Trends

(SMART), 2018: IEEE, pp. 150-153.

[17] F. Arena and G. Pau, "An overview of vehicular communications,"

Future Internet, vol. 11, no. 2, p. 27, 2019.

[18] A. Zekri and W. Jia, "Heterogeneous vehicular communications: A

comprehensive study," Ad Hoc Networks, vol. 75, pp. 52-79, 2018.

[19] S. Anand and M. V. Ramesh, "Impact of network density on the

performance of delay tolerant protocols in heterogeneous vehicular

network," in 2019 International Conference on Wireless Communications

Signal Processing and Networking (WiSPNET), 2019: IEEE, pp. 293-298.

[20] A. Ahamed and H. Vakilzadian, "Issues and challenges in VANET

routing protocols," in 2018 IEEE international conference on

electro/information technology (EIT), 2018: IEEE, pp. 0723-0728.

[21] A. Bengag and M. El Boukhari, "Classification and comparison of routing

protocols in VANETs," in 2018 International Conference on Intelligent

Systems and Computer Vision (ISCV), 2018: IEEE, pp. 1-8.

[22] M. M. Hamdi, L. Audah, S. A. Rashid, A. H. Mohammed, S. Alani, and

A. S. Mustafa, "A review of applications, characteristics and challenges in

vehicular ad hoc networks (VANETs)," in 2020 International Congress

on Human-Computer Interaction, Optimization and Robotic Applications

(HORA), 2020: IEEE, pp. 1-7.

[23] M. Kumar, A. K. Nigam, and T. Sivakumar, "A survey on topology and

position based routing protocols in vehicular ad hoc network (VANET),"

International Journal on Future Revolution in Computer Science &

Communication Engineering, vol. 4, no. 2, pp. 432-440, 2018.

[24] T. K. Bhatia, R. K. Ramachandran, R. Doss, and L. Pan, "A

comprehensive review on the vehicular ad-hoc networks," in 2020 8th

International Conference on Reliability, Infocom Technologies and

Optimization (Trends and Future Directions)(ICRITO), 2020: IEEE, pp.

515-520.

[25] N. J. Patel and R. H. Jhaveri, "Trust based approaches for secure routing

in VANET: a survey," Procedia Computer Science, vol. 45, pp. 592-601,

2015.

[26] M. R. Ghori, A. S. Sadiq, and A. Ghani, "VANET routing protocols:

review, implementation and analysis," in Journal of Physics: Conference

Series, 2018, vol. 1049, no. 1: IOP Publishing, p. 012064.

[27] F. T. AL-Dhief, N. Sabri, M. Salim, S. Fouad, and S. Aljunid, "MANET

routing protocols evaluation: AODV, DSR and DSDV perspective," in

MATEC web of conferences, 2018, vol. 150: EDP Sciences, p. 06024.

[28] G. D. Singh, R. Tomar, H. G. Sastry, and M. Prateek, "A review on

VANET routing protocols and wireless standards," Smart computing and

informatics, pp. 329-340, 2018.

[29] T. H. Sureshbhai, M. Mahajan, and M. K. Rai, "An investigational

analysis of DSDV, AODV and DSR routing protocols in mobile Ad Hoc

networks," in 2018 International Conference on Intelligent Circuits and

Systems (ICICS), 2018: IEEE, pp. 281-285.

[30] D. Sharma, S. Chaudhary, and S. Aggarwal, "PERFORMANCE

ANALYSIS OF AODV AND DYMO ROUTING PROTOCOLS IN WI-

MAX NETWORKS."

[31] M. A. Shyaa, H. M. Ibrahim, A. Meri, M. Dauwed, and A. Flayh, "The

impact of node density over routing protocols in manet by using NS-3," J.

Adv. Res. Dyn. Control Syst, vol. 11, no. 5 Special Issue, pp. 184-191,

2019.

[32] C. Dutta and D. Singhal, "A hybridization of artificial neural network and

support vector machine for prevention of road accidents in VANET,"

International Journal of Computer Engineering and Technology, vol. 10,

no. 01, 2019.

[33] A. Husain, S. P. Singh, and S. Sharma, "PSO optimized geocast routing in

VANET," Wireless Personal Communications, vol. 115, no. 3, pp. 2269-

2288, 2020.

[34] H. Bello-Salau, A. Aibinu, Z. Wang, A. Onumanyi, E. Onwuka, and J.

Dukiya, "An optimized routing algorithm for vehicle ad-hoc networks,"

Engineering Science and Technology, an International Journal, vol. 22,

no. 3, pp. 754-766, 2019.

[35] A. Lakas, M. E. A. Fekair, A. Korichi, and N. Lagraa, "A

multiconstrained QoS-compliant routing scheme for highway-based

vehicular networks," Wireless Communications and Mobile Computing,

vol. 2019, 2019.

[36] H. Bagherlou and A. Ghaffari, "A routing protocol for vehicular ad hoc

networks using simulated annealing algorithm and neural networks," The

Journal of Supercomputing, vol. 74, no. 6, pp. 2528-2552, 2018.

[37] G. Sun, Y. Zhang, D. Liao, H. Yu, X. Du, and M. Guizani, "Bus-

trajectory-based street-centric routing for message delivery in urban

vehicular ad hoc networks," IEEE Transactions on Vehicular Technology,

vol. 67, no. 8, pp. 7550-7563, 2018.

[38] F. Goudarzi, H. Asgari, and H. S. Al-Raweshidy, "Traffic-aware VANET

routing for city environments—A protocol based on ant colony

optimization," IEEE Systems Journal, vol. 13, no. 1, pp. 571-581, 2018.

[39] C. Chen, L. Liu, T. Qiu, K. Yang, F. Gong, and H. Song, "Asgr: An

artificial spider-web-based geographic routing in heterogeneous vehicular

networks," IEEE Transactions on Intelligent Transportation Systems, vol.

20, no. 5, pp. 1604-1620, 2018.

[40] G. Zhang, M. Wu, W. Duan, and X. Huang, "Genetic algorithm based

QoS perception routing protocol for VANETs," Wireless

Communications and Mobile Computing, vol. 2018, 2018.

[41] N. M. Al-Kharasani, Z. A. Zulkarnain, S. Subramaniam, and Z. M.

Hanapi, "An efficient framework model for optimizing routing

performance in VANETs," Sensors, vol. 18, no. 2, p. 597, 2018.

[42] M. Elshaikh, M. N. B. M. Warip, N. Yaakob, O. Lynn, A. K. Yousif, and

Z. Ishwar, "Taguchi methods for ad hoc on demand distance vector

routing protocol performances improvement in VANETs," in

International Conference of Reliable Information and Communication

Technology, 2017: Springer, pp. 163-170.

[43] M. Raja, "PRAVN: perspective on road safety adopted routing protocol

for hybrid VANET-WSN communication using balanced clustering and

optimal neighborhood selection," Soft Computing, vol. 25, no. 5, pp.

4053-4072, 2021.

[44] X. Bao, H. Li, G. Zhao, L. Chang, J. Zhou, and Y. Li, "Efficient

clustering V2V routing based on PSO in VANETs," Measurement, vol.

152, p. 107306, 2020.

[45] R. Liu, Y. Xiang, and Y. Yang, "MARR-ALOHA: A mobility adaptive

variety of RR-ALOHA for vehicular ad-hoc networks," in 2012 2nd

International Conference on Consumer Electronics, Communications and

Networks (CECNet), 2012: IEEE, pp. 3304-3309.

[46] S. Asadallahi and H. H. Refai, "Modified R-ALOHA: broadcast MAC

protocol for vehicular ad hoc networks," in 2012 8th International

Wireless Communications and Mobile Computing Conference (IWCMC),

2012: IEEE, pp. 734-738.

[47] S. Anand and M. V. Ramesh, "Performance Analysis of Delay Tolerant

Network Routing Protocols in a Heterogeneous Vehicular Network," in

2018 IEEE International Conference on Computational Intelligence and

Computing Research (ICCIC), 2018: IEEE, pp. 1-6.

[48] V. N. Soares, F. Farahmand, and J. J. P. Rodrigues, "Impact of vehicle

movement models on VDTN routing strategies for rural connectivity,"

International Journal of Mobile Network Design and Innovation, vol. 3,

no. 2, p. 103, 2009.

[49] C. Caini, "Delay-tolerant networks (DTNs) for satellite communications,"

in Advances in Delay-Tolerant Networks (DTNs): Elsevier, 2021, pp. 23-

46.

156

JOURNAL OF COMMUNICATIONS SOFTWARE AND SYSTEMS, VOL. 19, NO. 2, JUNE 2023

Page 11

[50] P. Godha, S. Jadon, A. Patle, I. Gupta, B. Sharma, and A. K. Singh,

"Architecture, an efficient routing, applications, and challenges in delay

tolerant network," in 2019 International Conference on Intelligent

Computing and Control Systems (ICCS), 2019: IEEE, pp. 824-829.

[51] M. Benamar, S. Ahnana, F. Z. Saiyari, N. Benamar, M. D. El Ouadghiri,

and J.-M. Bonnin, "Study of VDTN routing protocols performances in

sparse and dense traffic in the presence of relay nodes," Journal of Mobile

Multimedia, pp. 078-093, 2014.

[52] A. Hamza-Cherif, K. Boussetta, G. Diaz, and F. Lahfa, "Performance

evaluation and comparative study of main VDTN routing protocols under

small-and large-scale scenarios," Ad Hoc Networks, vol. 81, pp. 122-142,

2018.

[53] P. Kamal and N. Singh, "A new approach buffer-efficient disruption

tolerant protocol in vehicular delay-tolerant network," Journal of

Information and Optimization Sciences, vol. 41, no. 6, pp. 1395-1405,

2020.

[54] A. Ali, M. Shakil, H. Rafique, and S. M. Cheema, "Connection Time

Estimation between Nodes in VDTN," International Journal of Advanced

Computer Science and Applications, vol. 10, no. 1, pp. 339-345, 2019.

[55] S. Parameswari, "Opportunistic Routing Protocol for Resource

Optimization in Vehicular Delay-Tolerant Networks (VDTN)," Turkish

Journal of Computer and Mathematics Education (TURCOMAT), vol. 12,

no. 11, pp. 3665-3671, 2021.

[56] A. Ali, J. Li, A. Tanveer, M. Batool, and N. Choudhary, "DesCom:

Routing Decision using Estimation Time in VDTN," International

Journal of Advanced Computer Science and Applications, vol. 10, no. 11,

2019.

[57] J. A. Dias, J. J. Rodrigues, N. Kumar, V. Korotaev, and G. Han, "REMA:

A resource management tool to improve the performance of vehicular

delay-tolerant networks," Vehicular Communications, vol. 9, pp. 135-143,

2017.

[58] A. Hamza-Cherif, K. Boussetta, G. Diaz, and F. Lahfa, "GeoDTC: A New

Geographic Routing Protocol Based on Distance, Time and Custody

Transfer," in International Conference on Internet of Vehicles, 2018:

Springer, pp. 27-45.

[59] M. Tsuru, W. N. Cahyo, and P. A. Brastama, "Performance of Delay

Tolerant Network Protocol in Smart City Scenario," in Journal of

Physics: Conference Series, 2020, vol. 1569, no. 2: IOP Publishing, p.

022056.

[60] Y. Teranishi, T. Kimata, E. Kawai, and H. Harai, "Hybrid cellular-DTN

for vehicle volume data collection in rural areas," in 2019 IEEE 43rd

Annual Computer Software and Applications Conference (COMPSAC),

2019, vol. 1: IEEE, pp. 276-284.

[61] N. Magaia, C. Borrego, P. R. Pereira, and M. Correia, "ePRIVO: An

enhanced privacy-preserving opportunistic routing protocol for vehicular

delay-tolerant networks," IEEE Transactions on Vehicular Technology,

vol. 67, no. 11, pp. 11154-11168, 2018.

[62] F. Farooq and N. Bibi, "Message Admission Control along with Buffer

Space Advertisement to Control Congestion in Delay Tolerant Networks

(DTNs)," EAI Endorsed Transactions on Energy Web and Information

Technologies, vol. 5, no. 17, 2018.

[63] V. Chourasia, S. Pandey, and S. Kumar, "Optimizing the performance of

vehicular delay tolerant networks using multi-objective PSO and artificial

intelligence," Computer Communications, vol. 177, pp. 10-23, 2021.

[64] A. K. Singh and R. Pamula, "An efficient and intelligent routing strategy

for vehicular delay tolerant networks," Wireless Networks, vol. 27, no. 1,

pp. 383-400, 2021.

[65] J. Gonçalves Filho, A. Patel, B. L. A. Batista, and J. C. Júnior, "A

systematic technical survey of DTN and VDTN routing protocols,"

Computer Standards & Interfaces, vol. 48, pp. 139-159, 2016.

[66] B. Marzak, H. Toumi, E. Benlahmar, and M. Talea, "Analysing

Clustering Routing Protocols Performance for Vehicular Networks," in

Proceedings of the 2nd international Conference on Big Data, Cloud and

Applications, 2017, pp. 1-7.

[67] F. D. Da Cunha, A. Boukerche, L. Villas, A. C. Viana, and A. A.

Loureiro, "Data communication in VANETs: a survey, challenges and

applications," 2014.

Ahmed Ali Hussein received his B.Sc. Degree in

Computer Engineering from the University of

Technology, Iraq, in 2013. He is a member of the

Iraqi Engineers Association. He is currently a

M.Sc. student at the University of Technology,

Department of Computer Engineering, Iraq. His

research interests are computer engineering,

Wireless networks, ad-hoc wireless networks and

VANET.

Dr. Dhari Ali Mahmood is currently a Lecturer at

the Department of Computer Engineering,

University of Technology, Iraq. Received a B.Sc.

degree in computer engineering from University of

Technology, Baghdad, Iraq, in 2005 and M.Sc.

degree in computer engineering from GGSIP

University, India in 2014. He obtained his Ph.D. in

Computer Engineering from Budapest University

of Technology and Economics, Hungary in 2021.

Research interests mainly focus on Mobile Ad-hoc

Network (MANET), Vehicular Ad-hoc Network

(VANET), Queueing performance and Computer Networks.

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