The sensors networks wsn and vsn a

International Journal of Wireless & Mobile Networks (IJWMN) Vol. 6, No. 5, October 2014
THE SENSORS NETWORKS WSN AND VSN: A
THEORETICAL COMPARISON
Bahidja Boukenadil¹
¹Department of Telecommunication, Tlemcen University, Tlemcen,Algeria
ABSTRACT
The development of wireless technology currently allows extending the notion of mobility for access to
information and communication anywhere and anytime. With the emergence of sensor networks
(Traditional (WSN) and vehicular (VSN)), new themes have been opened and new challenges have emerged
to meet the needs of individuals and the requirements of several application areas. Research today is much
focused on vehicular sensor networks (VSN), considerable efforts have emerged to introduce intelligence
into transport systems whose aim is to improve safety, efficiency and usability in road transport. These
networks will play an important role in building the Future Internet, where they will serve as a support for
various communication applications and integrated into our daily lives. In this paper, we surveyed the main
characteristic and applications of two type of Ad hoc networks WSN and VSN.
KEYWORDS
Sensor networks, WSN, Vehicular sensor, VSN
1. INTRODUCTION
Progress in recent decades in the fields of microelectronics, micromechanics, and wireless
communication technologies; have produced a reasonable cost component of a few cubic
millimeters in volume. The latter, known as micro-sensors, embedded systems are real where the
deployment of several of them, to collect and transmit environmental data to one or more
collection points, in an autonomous manner, form a network wireless sensors (WSN; Wireless
Sensor Network). The wireless sensor networks are likely to be widely deployed in the future
because they greatly expand our ability to monitor and control the physical environment to remote
locations. Recently the research group and the car companies were equipped vehicles with regular
sensors, thus practically creating a sensor network based mobile vehicles (VSN). The introduction
of intelligent transport systems requires the existence of networks of interconnected sensors. In the
vehicle, these sensors are scattered throughout the cabin (chips), below or on the sides of the
vehicle (sensors or transmitters) or above (antennas). On roadsides, at crossroads, near bridges or
tunnels, larger infrastructure can be arranged: cameras, gates, infrared radar. Everything is
connected to a central station that provides collection, processing, circulation and storage of data:
the "back office". All these facilities make up the system. But, in the same way that a computer
cannot function without software, this system must be programmed to produce results. These
programs, called "applications" are exploiting the system and make it "smart": they tell it in real
time how to mediate complex situations based on multiple parameters.
DOI : 10.5121/ijwmn.2014.6505 59

The objective of this paper is to make a comparative study between the two sensor networks
(traditional static sensors network and vehicular sensor network).
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2. ORGANIZATION OF THE PAPER
The remainder of the paper is organized as follows. In the following section, we describe the
characteristics and applications of the sensor networks (WSN and VSN), then we give a table of
comparison study for the both network r. Finally, section IV concludes this paper.
3. THE SENSOR NETWORKS
3.1 The Ad-Hoc Network
An ad-hoc network is a collection of hosts equipped with antennas that can communicate without
any centralized administration, using a wireless communication technology such as Wi-Fi,
Bluetooth, etc... In contrast to wired networks where only certain nodes called "routers" are
responsible for routing data in an ad-hoc network all nodes are both routers and terminals. The
choice of nodes that will provide a communication session in an ad-hoc network is dynamically
according to network connectivity, hence the term "ad hoc» [1].
In an ad-hoc network, a node can communicate directly (point-to-point) with any node if it is
located in its area of transmission, while communicating with a node outside its zone Transmission
occurs via several intermediate nodes (multi-hops).
3.2 Advantages of Ad-Hoc Networks
The ad-hoc networks have several advantages; the most important are:
• Easy deployment, fast and
inexpensive: in ad-hoc networks, the tedious task of deploying base stations (wiring, installation,
etc...) Is no longer necessary. Consequently, the deployment is faster and is done with a low cost.
• Fault tolerance: an ad-hoc network
continues to function even if some nodes fail, this is because it has no central nodes.
3.3 Types of Sensor Networks
In this section, we describe two types of ad-hoc networks, i.e. Wireless sensor networks (WSNs)
and Vehicular Sensor Networks (VSNs). We will also present their applications.
Although WSNs and WMNs have several common features, however, they have several
differences involving naturally different communication solutions. We end this section by
comparison table.
3.3.1. Wireless Sensor networks (WSNs)
The WSNs (Wireless Sensor Networks) are ad-hoc networks consist of nodes intelligent sensors
powered by batteries, and they are equipped with processing capabilities and limited storage.
Indeed, the sensor nodes are able to perform three additional tasks: i) the statement of a physical
or environmental (e.g. temperature, pressure, pollution, etc.). ii) the possible treatment of this
information and finally iii) routing. The network may contain a large number of nodes
(thousands) generally static and deployed randomly (e.g. by dropping from a helicopter) in
environments that can be dangerous. In addition to the sensor nodes, a WSN consists of base

stations high in energy (sink nodes) characterized by a processing capacity and greater storage.
These chemicals act as gateways between sensor nodes and the end user (see fig.1).
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Figure 1. Routing paradigm in a sensors networks
3.3.2. Applications of WSN
We distinguish a variety of applications for sensor networks, quoting among others [2]:
• Military applications: WSNs can be used to monitor the activities of enemy forces to terrain
analysis and detection of chemical agents or radiation before sending troops.
• Application security: a sensor network can be an alarm system to be used for distributed
intrusion detection over a wide area.
• Environmental applications: thermo-sensors scattered over a forest may indicate a possible
outbreak of fire, thus allowing greater efficiency in the fight against forest fires. Industrial sites,
nuclear power plants or oil sites, sensors can be deployed to detect leaks of toxic substances
(gases, chemicals, radioactive elements, oil, etc..) And alert users within a sufficiently short to
enable an effective response.
3.3.3. Vehicular Sensor Networks (VSN)
3.3.3.1 The Vehicle and Embedded systems
Embedded systems consist of tangible and intangible resources integrated into the vehicle. It is
the most visible face of the system. It includes systems for the collection, processing and
dissemination of information within the scope of the vehicle.
As part of ITS information gathering takes place at two distinct levels. The first data collection
performed by the vehicle. The second concerns the data collected outside the vehicle (weather,
traffic monitoring, pollution level ...). Automobiles in use today are already equipped with
multiple sensors. Among the most common are found, for example, water temperature sensor,
fuel gauge, speedometer, tachometer, the radio.

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Figure 2. Wireless Vehicular Networks
Recent years more specific features have been added such as wheel rotation sensors, rain sensors,
radar sensors, GPS. We can add to this list another sensor, which is still rarely secured to the
vehicle: the mobile phone. This device tends increasingly to be connected to the vehicle,
including through Bluetooth. Other detection systems more or less sophisticated (internal and
external cameras, sensors for positioning on the floor, radar obstacle detection) are already
available in several ranges of vehicles (Audi, BMW, Ford, Infiniti, Lexus, Mercedes , Opel,
Volkswagen, Volvo ...).
Figure 3. Sensor technologies in the vehicle
3.3.3.2 Features and benefits associated with VSN
3.3.3.2.1. Prevention of accidents
The VSN allows the driver to better control his vehicle, but also to assess its own capacity to lead.
Numerous technological applications have already come in for a long time usage. Without even
thinking, with a simple glance at the dashboard, the driver checks the multiple indicators critical
to safety or operation from the vehicle: fuel level and oil, engine temperature , speed, mileage,
Headlamp ... the high-end vehicles offer more precise indicators and more specialized tire
pressure, belts hanging safety, collision avoidance radar, outside temperature, audio signal of a
risk of freezing rain or fog ... All of these technologies in place during the past two decades
reinforce the safety and comfort of travel. But they are based on an assumption: the driver will be
able to understand the information that may put to flight instruments and he will interpret it and
make the right decisions to adjust his conduct. But the statistics prove this assumption is wrong:
90% of accidents result from human error.
ITS is an answer to this paradox. This is just to increase the number, nature or accuracy indicators
edge, but offset the limitations or human failures.

An example: the driver's ability to control his vehicle. For reasons of culture and habit, the driver
tends to overestimate their abilities and minimize the risks it is exposed. Nervousness, stress,
depression, or conversely an overly excited or euphoric joy disturb the judgment and can cause
accidents. Like alcohol abuse, as is proved alcohol testing: drivers systematically underestimate
the amount of alcohol consumed and difficulty in admitting their inability to respond quickly and
appropriately to unexpected situations. The VSN of new generations of embedded devices will
detect this weakness by measuring different parameters and can alert the driver before he takes
the road, or possibly block the vehicle in case of inconsistent behavior.
It’s the same with regard to lack of sleep. Drowsy driving is the cause of many accidents. Sensors
located on the dashboard or in equipment (steering wheel, seat, outside edge of the vehicle) will
detect its most characteristic symptoms (frequent and prolonged blinking of the eyelids; stiff
neck, repetitive yawning; deviant trajectory of the vehicle against the benchmarks of the roadway,
inappropriate speed, inconsistent or incoherent) and will give warning.
VSN can not only trigger an alarm (an audio message, a bell in the car for the driver), but still be
able to prevent the danger to other road users. For example, the system can warn a driver coming
the opposite direction it faces a frontal impact due to the abnormal trajectory of the first vehicle.
In case of deep sleep, resulting in an off line, using the tracking of the trajectory (Lane Keeping
Support, LKS) can also be activated (the system "takes over" on the vehicle and keeps him in the
middle of the carriageway in order to avoid collisions longitudinal or lateral). It can even help
coordinate with the path of other vehicles identified in the immediate environment. The
"platooning" is to drive a vehicle group together according to established parameters in order to
prevent any risk of collision. Of "Cybernetic Transport Systems" can even manage fleets of
vehicles fully automated.
Another example: the view. An estimated one third of accidents are related in one way or another,
lack of visibility. The VSN can compensate for the weaknesses of the human eye. It's not science
fiction. Engineers do not plan to equip drivers with electronic eyes. But almost, thanks to the
satellite geolocation (GPS, Galileo), we know the exact position of a vehicle on a highway; we
know what direction it is progressing and we can accurately assess its speed.
Through this same process we can identified in the same way another vehicle, for example
located one hundred meters behind the first vehicle. Suppose that the second vehicle is traveling
at a speed much higher than the first, in heavy fog. There is a risk of collision because the driver
of the second vehicle can not see the vehicle in front and toward which he directs. In this
hypothesis, the VSN can establish a link between the two situations: real-time information system
identifies each vehicle, reports the positions and issues a warning because of the risk of accident.
The system can suggest to the first vehicle speed to maintain a safe distance from longitudinal or
in adhering to the side of the road, and recommend to the second vehicle to slow or anticipation.
Thanks to the mediation system, and complement systems of autonomous driving assistance on
board the vehicle, the drivers of both vehicles to "see", despite the distance and fog.
But risk reduction is not limited to "dialogue" between vehicles (V2V called for "Vehicle to
Vehicle"), it also concerns the relationship between vehicles and infrastructure (V2I or, for
"Vehicle to Infrastructure" ). When approaching a crossroads with, motorists will be informed of
the danger of crossing the state possibly faulty installation, or even the presence of other risk
vehicles or pedestrians.
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3.3.3.2.2. The reduction of damage in a collision
The connected car will benefit from several advantages over the autonomous vehicle. The
information system that could be detected just before the collision imminence thereof, he may
undertake immediate measures to reduce its impact. For example, it can accurately measure the
weight, shape and position of each occupant of the vehicle to determine the exact timing and
triggering of airbags inflation level required to reduce the impact of inflation. It can also "take
control" of the vehicle and provide the best brake system based on multiple parameters,
impossible to comprehend as efficiently by the driver in a very short time, the order of a fraction
of a second .
The VSN then instantly calculates vehicle speed, its position on the floor, the existence of specific
barriers on it (other vehicles, pedestrians), specific weather (rain, ice) and acts on the parameters
of the collision.
3.3.3.2.3. The emergency management:
The triggering of emergency is a very important step in the management of traffic accidents and
determines some of the balance disorder. In a very short time, we must take steps to avoid
complications of an accident (an accident caused by the additional first accident), assess the
extent of damage (human, material) and trigger the alarm (to call the police, the firefighters, and
other motorists).
Previously, motorists had no other recourse but to walk to the nearest village to raise the alarm.
With the installation of emergency terminals on the banks of the motorway, the communication
was greatly facilitated. The mobile phone can now go much further and summoning assistance
immediately. But it is still necessary for this reason that the casualty is able to correctly analyze
the situation (the trauma of the accident impairs judgment), and she is conscious.
The VSN can precisely react immediately regardless of the status of the passenger. The detection
of the shock is immediate (GPS instantly identifies the crash and abnormal vehicle, the shock is
detected by onboard sensors programmed to trigger activation of aibags). The analysis of the
environment (other vehicles on the approach) is used to trigger automatic and on-the-field bounds
warning (flashing lights), to reduce the risk of an accident. The VSN are then used to accurately
assess the damage: using sensors and using the communication network GSM (Global System for
Mobile Communication), one can quantify the number of people aboard the vehicle, determine
whether they are conscious or not, estimate the risk of fire or explosion relief indicate the exact
position of the vehicle, he left the floor, if turned...
Much invaluable information to adjust the rescue. Many of these applications in the near future
will have an effect on the rate and severity of accidents will become mandatory in vehicles, as
will soon be systems of "Emergency Call" (automatic communication with the relief collision).
The emergency call is already on the market for many years in Europe (BMW, Mercedes, PSA,
Volvo ...). [3]
3.4Comparison between VSN and WSN:
To our knowledge, this time the mobility of sensor networks is not widely traded. The majority of
existing research considers static networks. In this section we will briefly illustrate the differences
between static sensor networks and mobile. A sensor array consists of a set of nodes deployed in
an area of interest for the purpose of the monitor, and to transmit information to the end user (the
observer).

A static sensor network WSN does not consider any node mobility, or the observer, or the area of
interest. In this case, the sensors are combined to capture for example the temperature in a given
region. This requires an initial installation of communications infrastructure to create the path
between the observer and the sensors.
On the other hand, in mobile sensor network nodes VSN, the area of interest, and the observer are
moving. If the nodes are moving, we are not changing the area of interest which then becomes
"mobile". As the area is changed, the observer will have to reconstruct the path and break the old
one. In this case the observer's interest to build more paths between itself and the nodes and
choose the most beneficial. How a node can be mobile? It can be attached to a robot with a human
being, vehicle, etc... For example in military applications, nodes can be attached to soldiers or
trucks, or in other cases attached to animals to track their movements.
The goal of mobile sensor networks is to gather more information about an environment by using
less of sensor nodes, and allow the network to organize its own nodes. In addition, he becomes
able to move its sensors dynamically according to environmental changes, making it adaptable to
the changing environment. [1]
Although the VSN and WSN have several common characteristics, but they differ in several
aspects [2]:
• The main characteristic of a constituent node VSN is the mobility, while the sensor
65
nodes in a WSN are static.
• In the VSN communication can occur between any network nodes, while in a WSN
communication is always initiated to or from nodes wells over the communications sensor to
sensor are rare, but the transmissions multicast and broadcast are common.
• The VSN are characterized by a lower density compared to the WSN.
• In a VSN all nodes are equal, thus the failure of any node has the same importance,
while a WSN is more sensitive to the failure of nodes as well that of the sensors.
The main differences between VSN and WSN are summarized in the following table :
Table 1. Comparison between WSN and VSN
WSN
VSN
Objective target goal General / Communication
Collaboration Nodes working together
for the same purpose
Each node has its own
target
Data flow Many-to-one Any-to-Any, One-to-All,
One-to-Many
identity Very large number of
nodes without ID
Presence of the concept of
ID

66
main factor Energy resource Throughput, QoS
Type of communication Broadcast Poin to Point (Unicast),
Multicast, Broadcast
mobility Nodes are static The nodes are mobile
Computing capacity Low power computing High calculation capacity
storage space Low storage capacity
Great capacity of storage
Communication
capacity
Low capacity of
communication
reliable communication
energy
Nodes have a
constrained battery
life.
There is no battery life
constraint.
Data volume A small volume of data
generated on the types
of applications
A large volume of data
generated
CONCLUSION
In this paper, we have investigated the main characteristic and applications of two type of Ad hoc
networks WSN and VSN.
Unlike other networks, WSNs are designed for specific applications. Applications include, but are
not limited to, environmental monitoring, industrial machine monitoring, surveillance systems,
and military target tracking. On the other hand VSN will play an important role in the coming
years, whether to communicate with another vehicle or with existing infrastructures. Indeed,
today's cars no longer be satisfied to detect hazards through radar or cameras, they will be able to
receive alert messages sent by other drivers or infrastructure (panels, gantries, etc.. ...) and to
transmit this information to other vehicles. Each application differs in features and requirements.
This study allowed us to make a theoretical comparison between the two networks. In the future,
we aim to make an experimental comparison based on the simulation of a routing protocol in both
environments: Wireless Sensor Networks and Vehicular Sensor Networks.
REFERENCES
[1] Abdallah Makhoul, « Sensor networks: location, coverage and data fusion,» Ph.D. Thesis, University of
Franche-Comté, in November 2008.
[2] S.L. Wu, Y.C. Tseng; « Wireless Ad Hoc Networking: Personal-Area, Local-Area, and the Sensory-
Area Networks »; USA, Auerbach publications, ISBN: 0-8493-9254-3, 2007.
[3] Challenge Bibendum: challenge.bibendum.com

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