This document provides a review of approaches for enhancing the performance of vehicular ad hoc networks (VANETs) using CSMA-MACA. It begins with an introduction to VANETs and discusses some of their key properties including high dynamic topology, frequent disconnections, and the hidden terminal problem. The document then reviews related work on hybrid approaches combining CSMA and MACA for routing in VANETs. Finally, it provides details on commonly used routing protocols like AODV and discusses how accounting for obstacles in simulations can improve safety performance evaluations of VANET applications.

1. IOSR Journal of Computer Engineering (IOSR-JCE)
e-ISSN: 2278-0661,p-ISSN: 2278-8727, Volume 17, Issue 3, Ver. II (May – Jun. 2015), PP 99-104
www.iosrjournals.org
DOI: 10.9790/0661-173299104 www.iosrjournals.org 99 | Page
A Hybrid Approach for Performance Enhancement of VANET
using CSMA-MACA: a Review
Sheenam Arora1
, Chakshu Goel², Benu3
1
(M.Tech Scholar, Department of ECE, SBSSTC, Ferozepur (Pb.), India)
2
(Assistant Professor, Department of ECE, SBSSTC, Ferozepur (Pb.), India)
3
(Lecturer, Department of ECE, SBSSTC Poly wing, Ferozepur (Pb.), India)
Abstract: A wireless sensor network (WSNs) have increased gigantic consideration for their extensive variety
of utilization, for example, environmental checking, military consideration, medical services, fiasco
administration and so forth .A Vehicular ad hoc network (VANET) utilizes cars as versatile nodes as a part of a
MANET to make a portable system. A VANET transforms each partaking car into a remote or switch or node,
permitting cars pretty nearly100 to 300 meters of one another to associate and, thus, make a system with a wide
range. In wireless networking, the shrouded node issue or concealed terminal issue happens when a node is
obvious from a wireless access point(AP), yet not from different nodes communicating with that AP.In our work
we will dispose of the issue of concealed terminal node issue.
Keywords: AODV, Hidden terminal node, VANET’s, WSN.
I. Introduction
A wireless network is any sort of PC system that uses remote information associations for associating
system hubs. Remote systems administration is a system by which homes, information transfers systems and
endeavor (business) establishments evade the unreasonable methodology of bringing links into a building, or as
an association between different supplies locations. Wireless information transfers systems are by and large
actualized and controlled utilizing radio communication.
II. Types of Wireless Networks
2.1 Wireless PAN
Wireless personal area networks (WPANs) interconnect gadgets inside a moderately little region that is
for the most part inside an individual's reach. For instance, both Bluetooth radio and undetectable infrared light
gives a WPAN to interconnecting a headset to a portable computer. Zig Bee likewise underpins WPAN
applications. Wi-Fi PANs are getting to be typical (2010) as gear originators begin to coordinate Wi-Fi into a
mixed bag of purchaser electronic gadgets. Intel "My Wi-Fi" and Windows 7"virtual Wi-Fi" abilities have made
Wi-Fi PANs easier and simpler to set up and design.
2.2 Wireless LAN
A wireless local area network joins two or more gadgets over a short separation utilizing a remote
conveyance system, generally giving an association through a right to gain entrance point for Internet access.
The utilization of spread-range or OFDM advances may permit clients to move around inside a neighborhood
scope zone, and still stay joined with the system. Items utilizing the IEEE 802.11 WLAN guidelines are
advertised under the Wi-Fi brand name. Settled remote innovation actualizes point-to-point interfaces between
PCs or systems at two removed areas, regularly utilizing committed microwave or tweaked laser light pillars
over observable pathway ways. It is frequently utilized as a part of urban communities to associate systems in
two or more structures without introducing a wired connection.
2.3 Wireless Mesh network
A wireless mesh network is a remote system made up of radio hubs composed in a lattice topology.
Every hub advances messages for the benefit of alternate hubs. Cross section systems can "self recuperate",
naturally re-directing around a hub that has lost force.
III. Properties OF WSN
3.1 Performance
Every standard differs in geographical range, subsequently making one standard more perfect than the
following relying upon what it is one is attempting to finish with a remote network. The execution of remote
systems fulfills a mixture of uses, for example, voice and feature. The utilization of this innovation likewise
gives space for extensions, for example, from 2G to 3Gand, most as of late, 4G innovation, which remains for

2. A Hybrid Approach for Performance Enhancement of VANET using CSMA-MACA: a Review
DOI: 10.9790/0661-173299104 www.iosrjournals.org 100 | Page
fourth era of mobile phone versatile correspondences measures. As remote systems administration has gotten to
be typical, refinement increments through design of system equipment and programming, and more noteworthy
ability to send and get bigger measures of information, speedier, is achieved.
3.2 Space
Space is an alternate normal for remote systems administration. Remote systems offer numerous points
of interest with regards to hard to-wire regions attempting to impart, for example, over a road or waterway, a
stockroom on the opposite side of the reason or structures that are physically divided however work as one.
Remote systems take into account clients to assign a certain space which the system will have the capacity to
speak with different gadgets through that system. Space is likewise made in homes as a consequence of
dispensing with jumbles of wiring. This innovation takes into account an option to introducing physical system
mediums, for example, TPs, cajoles, or fiber-optics, which can likewise be lavish.
IV. VANET
A vehicular ad hoc network (VANET) utilizes autos as versatile hubs in a MANET to make a portable
system. A VANET transforms each taking an interest auto into a remote switch or hub, permitting autos more or
less 100 to 300 meters of one another to unite and, thus, make a system with a wide range. As autos drop out of
the sign range and drop out of the system, different autos can join in, joining vehicles to each other so that a
portable Internet is made. It is assessed that the first frameworks that will incorporate this innovation are police
and fire vehicles to speak with one another for security purposes.
4.1 High Dynamic Topology
The topology of VANET changes due to the development of vehicles at high speed. Suppose two
vehicles are moving at the pace of 20m/sec and the radio range between them is 160 m. At that point the
connection between the two vehicles will last 160/20 = 8 sec.
4.2 Frequent disconnected network
From the very dynamic topology results we watch that successive disconnection happen between two
vehicles when they are trading data. This disconnection will happen most in inadequate system.
4.3 Mobility modeling
The versatility example of vehicles relies on upon activity environment, streets structure, the rate of vehicles,
driver's driving conduct etc.
4.4 Battery power and storage capacity
In advanced vehicles battery force and capacity is boundless. Subsequently it has enough figuring force which is
distracted in MANET. It is useful for successful correspondence & settling on directing choices.
4.5 Communication Environment
The correspondence environment between vehicles is distinctive in scanty system & thick system. In
thick system building, trees & different articles act as hindrances and in inadequate system like high-way this
things are non attendant. So the steering methodology of scanty & thick system will be diverse.
4.6 Interaction with onboard sensors
The current position & the development of hubs can without much of a stretch be sensed by installed sensors
like GPS gadget. It helps for compelling correspondence and steering choices.
V. Hidden Terminal Problem
In Fig. 1, transmitter TX1 and transmitter TX2 are out of radio range of each other, i.e., they are hidden
to one another. Therefore they may access the medium at the same time, making the receivers RX1-RX3
experience a data collision, i.e., being unable to decode any of the two packets. This phenomenon is termed the
hidden terminal problem and in wireless ad hoc networks, it can occur regardless of MAC method.

3. A Hybrid Approach for Performance Enhancement of VANET using CSMA-MACA: a Review
DOI: 10.9790/0661-173299104 www.iosrjournals.org 101 | Page
Fig.1 Hidden Terminal Problem
VI. Related Work
6.1 Related work
Bhatt, U.R. et al [1] "ONU arrangement in Fiber-Wireless (Fi-Wi) Networks" as of late, there is a
touchy development in a web clients which oblige a broadband access system with high limit and better
adaptability and gets benefit in "anyplace at whatever time" way. The arrangement is a FIWI innovation which
substantiating itself a principle apparatus in the field of telecom by its own benefits over the other existing
advances. Fiber-Wireless (FiWi) Network is a blend of Passive Optical Network (PON) and Wireless Mesh
Network (WMN). It gives vast transmission capacity limit and high steadiness in optical system and lower cost
in remote system. In this way, Fi-Wi offers clients to broadband access benefit in an "anyplace at whatever
time" way. In this paper, the principle concentrates on the ONU situation in Fi-Wi system to make an expense
effective system. The key issue in FiWi system is the arrangement of optical system unit (ONU) since ONU
gives interface between the optical system and wireless system. The arrangement of ONU assumes additionally
an essential part in system throughput.In Fi-Wi system, situation of ONU such that it help both sort of activity
i.e. Web activity and distributed (P2P) movement. Web movement means activity from the remote customer to
web and distributed movement means movement starting with one remote customer then onto the next remote
customer. In this paper, the related work done in ONU situation to help both sorts of activity and to minimizing
the quantities of ONU in a FiWi network is concentrated on.
Zhao Cheng et al [2] "Investigation and Optimization Model of Cognitive Wireless Mesh Networks"
Recently, much consideration has been committed to cognitive radio system (CRN) and thusly, it replenishes the
enthusiasm for enhancing the execution of remote lattice systems (WMNs). It has been demonstrated that
cognitive radio innovation consolidated with multi-radio multi-channel innovation is a guaranteeing route for
remote system execution change. In the meantime, they additionally prompt some new difficulties for system
building design configuration and convention improvement. This paper exhibits a multi-radio cognitive remote
lattice system structural engineering CR Mesh, which incorporates the cognitive radio (CR) innovation with
existing remote cross section system advancements consistently. A 3G Model is proposed, which can depict
CRN precisely from the point of view of bundle sending. The improvement issue of higher layer system control
conventions is investigated on the perspective of asset portion. A novel asset assignment plan and comparing
cross-layer advancement system are proposed. This paper exhibits a general plan of cognitive remote cross
section system structural planning configuration and convention advancement.
Abbas, F et al [3] "Protection mindful course following and disavowal diversions in VANET-based
mists" The predicted long for dependable, safe, and open to driving background is yet to end up reality since car
commercial ventures are trying their waters for VANET (Vehicular Ad Hoc Network) organization. Anyway by
the by, security and protection issues have been the underlying driver of obstacle in VANET deployment. As of
late, VANET advanced to VANET-based mists as a consequence of assets rich top of the line autos. Before
long, Hussain et al. characterized diverse building systems for VANET-based mists. In this paper, author goes
for a particular structure to be specific VUC (VANET utilizing Clouds) where VANET and CC (Cloud
Computing) participate with one another keeping in mind the end goal to give VANET clients with
administrations. Author was proposed a lightweight protection mindful disavowal and course following
component for VuC. Signals showed by vehicles are put away in cloud framework as collaboration from
VANET and in the wake of transforming, cloud gives VANET endorsers administrations. Denial powers can
disavow and follow the way taken by the target hub for a pointed out time span by abusing the signals put away
in the cloud. Our proposed plan is secure, jelly contingent security, and is computationally less costly than the
already proposed plans.
Craftsman, S.E.et al [4] "Hindrance Shadowing Influences in VANET Safety" Wireless interchanges
between vehicles empowers both wellbeing applications, for example, mischance evasion, and non safety
applications, for example, movement blockage alarms with the expectation of enhancing security in driving
conditions. Since expense restricted proving ground situations oblige model testing, VANET scientists regularly

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turn rather to reproduction toolsets from which a rich set of ecological situations are displayed. Notwithstanding,
regardless of the accessibility of such apparatuses, results are conflicting. While VANET specialists regularly
demonstrate proliferation misfortune deterministically subordinate upon transmitter recipient separation,
blurring and shadowing impacts are frequently displayed stochastically, prompting probabilistic results which
are autonomous of the genuine environment and accordingly neglect to consider practical street topologies and
the vicinity of snags. In this work, we actualize for ns-3 [3] the exactly accepted hindrance shadowing model
from by leveraging building information from Open Street Map (OSM) to deterministically assess observable
pathway spread impacts utilizing methods from computational geometry, and we further stretch out results to
assess wellbeing execution evaluations. The effect to security execution estimation of snags in VANET
reenactments inspires the accompanying examination objective: The objective of this exploration is to show
quantitatively how precise, deterministic hindrance blurring models affect the execution appraisal of VANET
wellbeing applications. Counting reasonable deterrent shadowing in VANET reproduction demonstrating
enhances VANET evaluation and reinforces wellbeing, along these lines supporting one of the essential
objectives of joined vehicle frameworks.
Siyue Chen et al [5] "Estimation of Packet Loss Rate at Wireless Link of VANET—RPLE" Vehicular
Ad hoc Network (VANET), as a subclass of portable Ad hoc Networks (MANETs), is a guaranteeing
methodology for movement security, versatile web and V2V correspondence. While the bundle misfortune
estimation of VANET effects directing convention and transmission control calculation, it just so happens to be
an essential issue. In this paper, author was proposed an estimation calculation for bundle misfortune on
VANET, RPLE (Real time parcel misfortune estimation), which utilizes few test bundles and improve the
estimation precision than conventional routines for bundle misfortune on remote systems. Because of hub
movement and complex radio environment, bundle misfortune estimation in VANET is a hard issue. On the
other hand, parcel misfortune estimation effects directing convention and transmission control calculation of
VANET, so it is a critical issue. In light of mass on-street estimations, we have gotten the general factual
principals of parcel misfortune rate (PLR) by separations on VANET, and we utilize Gaussian Mixture Model
(GMM) to present PLR likelihood thickness. All things considered, to get ongoing PLR by sending a couple of
test parcels, RPLE use greatest a posteriori likelihood strategy to gauge the current PLR focused around the
GMM of PLR likelihood thickness and the testing result. In genuine urban street situation, the investigation
results indicate that RPLE can get more precise PLR estimation by few test parcels instantly.
Vijayakarthika, R. et al [6] "Vehicular impromptu systems (VANETs) are a developing innovation that
gives productive and solid information correspondence between vehicles utilizing Roadside units (RSU). In any
case it obliges proficient and powerful steering conventions for their correspondence. We abuse the altered base
of Roadside units (RSUs) to proficiently and dependably course parcels in VANETs. All the RSUs are
interconnected with one another. Our VANET framework works by utilizing vehicles to convey and forward
messages from a source vehicle to a close-by RSU and, if necessary, course these messages through the RSU
system and, at long last send them from a RSU to the end of the line vehicle. All the RSUs are interconnected
with one another. To actualize the same vehicle correspondence with server based way. By our server based
system the vanet correspondence will be more successful. The separate will reaction for table support that
information in its information base. In our task idea we have the opportunity to lessened deferral with boosted
throughput in VANET furthermore we can ready to anticipate the activity thickness of specific range of our
system. We assess the execution of our framework utilizing the ns2 recreation and contrast our result and
existing framework.
VII. Approaches Used
7.1 AODV
In AODV, the system is quiet until a connection is required. By then the network node that needs a
connection telecasts an appeal for connection. Other AODV nodes forward this message, and record the node
that they heard it from, making a blast of short term routes back to the needy node. At the point when a node
gets such a message and has a route to the wanted node, it communicates something specific rearward through
an impermanent route to the asking for node. The needy node then starts utilizing the route that has the slightest
number of hops through different nodes. Unused passages in the routing tables are reused after a period. At the
point when a connection falls flat, a routing error is passed once more to a transmitting node, and the process
repeats.
7.2 OSP
Open Street Map is an activity to make and give free geographic data, for example, street maps, to
anybody. The Open Street Map Foundation is an universal not-revenue driven association supporting, yet not
controlling, the Open Street Map Project. It is devoted to empowering the development, advancement and
conveyance of free geospatial data and to giving geospatial data to anybody to utilize.

5. A Hybrid Approach for Performance Enhancement of VANET using CSMA-MACA: a Review
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7.3 CSMA
The term ―Carrier Sense‖ signifies the capability of the terminal to listen to the channel and find out
whether it is busy or not. At first sight it seems that with CSMA one can succeed in avoiding collisions
altogether. Indeed, if all terminals transmit their packets only when the channel is not busy and pick a random
retransmission time if they find the channel busy, then it seems that a collision will occur only when two or
more terminals begin transmission simultaneously, an event that is quite unlikely. However, the situation is not
as rosy as it seems, due to the finite duration it takes for a signal to spread from one terminal to another. The
modified CSMA system, whose principles of operation were described above, comes by the name CSMA/CA,
where CA stands for Collision Avoidance. The acronym signifies that collisions are sought to be avoided and
not that they are avoided altogether. Due to the retransmission policy of the CSMA system, collisions that may
occur are not detrimental: in case of collision, the ACK message or RTS CTS messages will not be received and
the transmitting terminal will defer its transmission for a later time. However, if the propagation delays are
relatively large and the system is heavily loaded, collisions may degrade the performance of the system.
7.4 MACA
MACA does not make use of carrier-sensing for channel access. It uses two additional signaling
packets: the Request-To-Send (RTS) packet and Clear-To-Send (CTS) packet. When a node wants to transmit
data packet, it first transmits an RTS packet. The receiver node, on accepting RTS packet, in the event that it is
prepared to get the data packet, transmits a CTS packet. Once the sender gets the CTS packet with no mistake, it
begins transmitting the data packet. On the off chance that a data transmitted by a node is lost, the node utilizes
the binary exponential back-off (BEB) algorithm to back-off for an irregular interim of time before retrying. In
the BEB mechanism each time a collision is detected, the node doubles its maximum back-off window.
Neighbor nodes near the sender that hear the RTS packet do not transmit for a long enough period of time so
that the sender could receive the CTS packet. Both, RTS and the CTS packets convey the normal length of time
of the data packet transmission. A node the receiver, after listening to the CTS packet, concedes its transmission
till the recipient gets the data packet. Thus, MACA overcomes the hidden terminal problem. Similarly, a node
receiving an RTS defers only for a short period of time till the sender could receive the CTS. If the node hears
NO CTS during its waiting period, it is free to transmit packets once the waiting interval is over. Thus a node
that hears only the RTS packet is free to transmit simultaneously when the sender of the RTS is transmitting
data packets. Hence the exposed terminal problem is also overcome in MACA.
7.5 DSRC
The primary motivation for deploying DSRC is to enable collision prevention applications. These
applications depend on frequent data exchanges among vehicles, and between vehicles and roadside
infrastructure DSRC, which is a candidate for use in a VANET, is a short to medium range communication
service that supports both public safety and private communication. The communication environment of DSRC
is both vehicle-to-vehicle and vehicle-to/from-roadside. The VANET plans to give a high data rate and in the
meantime minimize inactivity inside a generally little communication zone Dedicated Short-Range
Communication (DSRC) is a standard that intends to bring vehicular networks to North America. Activity
fatalities have been a long standing issue in the United States, as in whatever remains of the world. As a sign of
the seriousness of the issue, in 1999 there were 6,279,000 engine vehicle mischance’s that represented 41,611
passing in the United States. In 1991, the US Congress passed the Intermodal Surface Transportation Efficiency
Act of 1991 that brought about the creation the original of Intelligent Transportation System (ITS). The
objective of the ITS system is to consolidate innovation into the transportation base to enhance wellbeing.
VIII. Conclusion
The concealed terminal issue is regularly said to be the significant restricting execution figure in
vehicular ad hoc networks. In vehicular ad hoc networks (VANET) the hidden terminal problem is not as
straight forward to define. The term ―Carrier Sense‖ signifies the capability of the terminal to listen to the
channel and find out whether it is busy or not. MACA does not make use of carrier-sensing for channel access.
It uses two additional signaling packets: the Request-To-Send (RTS) packet and the Clear-To-Send (CTS)
packet. We will enhance our work by using hybrid CSMA + MACA protocol in VANET to solve the hidden
terminal problem.
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