1. Zigbee For Vehicular Communication Systems
J.Ram Harish Yadav1
, K.Dhanunjaya2
1
PG Student, Department of Electronics & Communication Engineering, ASCET, Gudur, A.P, India.
2
Head of the Deepartment, Department of Electronics & Communication Engineering, ASCET, Gudur, A.P, India
1
ramharish.j@gmail.com
Abstract:Vehicular communication is a popular
topic in theacademia and the car industry. The aim of
this growing interestis to develop an effective
communication system for theIntelligent
Transportation System (ITS). In this paper
wepresented the model of wireless base station
goodput evaluation.We used wireless access point
model as a queuing system withvariable requests and
the auto traffic model. The performance ofthe
wireless networks can be impacted from a variety
ofparameters, such as radio communication range,
availablebandwidth and bit rate, the number of clients
in wireless networkrange and vehicle speed. The
basic parameters were analyzedand presented in this
paper.
Index Terms:Short Range Vehicle Network;
802.11n; wirelessnetwork; goodput; network
performance; transport; mobilestations; auto traffic;
vehicle speed; Markov chain.
I. INTRODUCTION
The needs to enhance road safety, traffic efficiency
and to reduce environmental impact of road transport
are seriouschange for both academics and industry.
Researchers aregreatly interested to develop
vehicular communication andnetworking technology
in two realistic ways vehicle tovehicle (V2V) in ad
hoc mode and vehicle to infrastructure(V2I) with
fixed nodes along the road. The potency toexchange
information wireless via V2X is a foundationstone
for building powerful Intelligent Transport
Systems(ITS). In Europe, USA and Japan are great
efforts madefrom automakers and governments to
reach single standardsthrough the several and
common projects such as CAR 2CAR
Communication Consortium, Vehicle Safety
Communication Consortium, and EUCAR SGA etc.
Result fromcommon effort is an international
standard, IEEE802.11p[2], also known as Wireless
Access for VehicularEnvironments (WAVE). This
standard will be used as thegroundwork for
Dedicated Short Range Communications(DSRC).
This type of communication has potential toimprove
safety on the road, traffic flow and provide
comfortfor passengers and drivers with expedited
applications suchas INTERNET, network games,
automatic electronic tollcollection, drive-through
payments, digital map update,wireless diagnostic and
flashing etc. DSRC is the one stepin the future,
because it lets inter-vehicle and vehicle
toinfrastructure wireless communication.
Wireless networking based on IEEE802.11
technology[3] has recently become popular and
broadly available atlow-cost for home networking
and free Wi-Fi orcommercial hotspots. The DSRC
starting idea was to equipvehicular network nodes
with off-the-shelf wirelesstechnology such as
IEEE802.11a. This technology is costeffective and
has potential to grow and new versions havebeen
recently produced. The latest standard of
wirelesslocal area network (WLAN) is IEEE802.11n
[4]. The IEEE802.11n standard promises to improve
and extend mostpopular WLAN standards by
significantly increasingthroughput, reliability and
reach.
Nowadays dispositions of WLAN-based
accesstechnology are predominantly to stationer
indoor andoutdoor users who are most slowly moving
and in rangelimited. Despite the fact that the standard
has not beendeveloped for fast dynamic usage,
nothing limits it to beevaluated for vehicular
communication systems. Themotivation is to
understand the interaction between thevehicle speed
and goodput of WLAN-based network.Realizing
field trials for goodput evaluation ofvehicular
wireless communication systems is very difficultand
costly because many vehicles and
communicationequipments need to be purchased or
rented, and also manyexperimenters need to be
employed. Given such problems,it is highly desirable
to obtain a mathematical descriptionof process with
real data from small scale scenarios ofpractical
measurement results and performance
evaluationsprior to conducting field trials as it is
made in this work.
Proceedings of International Conference on Developments in Engineering Research
ISBN NO : 378 - 26 - 13840 - 9
www.iaetsd.in
INTERNATIONAL ASSOCIATION OF ENGINEERING & TECHNOLOGY FOR SKILL DEVELOPMENT
122

2. This paper constructs as follows: After introducing
theproblem in Section 1, Section 2 provides some
Vehicular Communication Systems. Then, in Section
3 SeVeCom Implementation and demonstrating the
analysis results inSection 4. Section 5 summarize and
concludes this paperwith a brief description on future
works.
II. VEHICULAR COMMUNICATION
SYSTEMS
There are significant differences between devices
such asmobile phones or desktop computers
connected to the Internetand devices in a VC system.
Differences in development,production, and
operation, determine VC-specific constraintsand
conditions:
1) Vehicles have a long life span, lasting several
yearsin most cases. This makes it hard to change on-
boardsystems as reaction to new upcoming risks to
the vehiclesafety.
2) Owners have constant physical access to and full
controlover vehicles. In spite of the involved safety
risks,many users might try to modify or “enhance”
theirvehicles. From a manufacturer’s point of view,
the riskof hardware tampering cannot be neglected.
3) No technical expertise on vehicle electronics or
VCsecurity aspects is expected from a user that runs
avehicle. Hence, the vehicular security measures
have tooperate autonomously with no need for
intervention orfeedback from the user.
4) Robustness requirements and time constraints are
demanding.Functions necessary, for example, for
drivingor alerts received via the VC system must be
processedin real-time: delays or errors could lead to
vehicle malfunctions,driving errors, and consequently
to physicaldamages and injuries.
5) Liability and conformance require precise
formulationof legal issues. Differing regulations and
requirements invarious countries make it even more
difficult to addressthese challenges.
These observations have consequences on the
implementationof a VC security system. Due to the
long vehicle lifecycle, it cannot be ensured that all
threats are thwarted at thetime of development.
Therefore, the VC security mechanismsshould be
flexible, adaptable, and extensible, to allow
lateradjustments to changing security requirements.
To address this need, we propose a component-based
security architecture forVC systems, which allows
adding, replace, and reconfigurecomponents (for
example, substitute cryptographic
algorithms)throughout the life cycle of the vehicle.
The large number and the variety of vehicles have
tobe taken into account. Even for a single car type,
differentproduction and equipment lines lead to many
distinct versionsand variants. Nonetheless, it should
be possible to integratea security system into all those
platforms. In addition, thecommunication stack and
security measures might be designedby different
teams or vendors; a situation that clearly
requireswell-defined but still flexible interfaces.
These reasons ledto the development of the so called
“hooking architecture”,which introduces special
hooks at the interface between everylayer of the
vehicular communication system. The
hookingarchitecture introduces an event-callback
mechanism into thecommunication stack which
allows adding security measureswithout the need to
change the entire communication system.The security
system in a vehicle has to fulfill real-time ornear real-
time requirements. For the underlying
cryptographicprimitives, this implies optimized
cryptographic hardware,in order to guarantee the near
real-time performance. Thepotential trade-off
between security and performance has tobe well
balanced.To enable VC systems to withstand future,
yet unknownattacks, besides the traditional
prevention-oriented approach,functionalities to detect
attacks, such as intrusion detectioncapabilities, and to
recover after an attack, are needed. In thelong run, the
goal is to enhance the resilience of the system.
III. SEVECOM IMPLEMENTATION
The SeVeCom project defines baseline
securityarchitecture for VC systems. Based on a set
of designprinciples, SeVeCom defines an architecture
that comprisesdifferent modules, each addressing
certain security and privacyaspects. Modules contain
components implementing one partof system
functionality. The baseline specification providesone
instantiation of the baseline architecture, building on
wellestablishedmechanisms and cryptographic
primitives, thusbeing easy to implement and to
deploy in upcoming VCsystems.
A. Baseline Architecture: Deployment View
The SeVeCom baseline architecture addresses
different aspects,such as secure communication
protocols, privacy protection,and in-vehicle security.
As the design and development ofVC protocols,
system architectures, and security mechanismsis an
ongoing process, only few parts of the overall system
Proceedings of International Conference on Developments in Engineering Research
ISBN NO : 378 - 26 - 13840 - 9
www.iaetsd.in
INTERNATIONAL ASSOCIATION OF ENGINEERING & TECHNOLOGY FOR SKILL DEVELOPMENT
123

3. areyet finished or standardized. As a result, a VC
security systemcannot be based on a fixed platform
but instead has to beflexible, with the possibility to
adapt to future VC applicationsor new VC
technologies.
To achieve the required flexibility, the SeVeCom
baselinearchitecture consists of modules, which are
responsible fora certain system aspect, such as
identity management. Themodules, in turn, are
composed of multiple components eachhandling a
specific task. For instance, the Secure
CommunicationModule is responsible for
implementing protocols forsecure communication
and consists of several components,each of them
implementing a single protocol. Components
areinstantiated only when their use is required by
certain applications,and they use well-defined
interfaces to communicatewith other components.
Thus, they can be exchanged by morerecent versions,
without other modules being affected.
Fig.1. Baseline Architecture: Deployment View.
As shown in Fig. 1, the Security Manager is the
centralpart of the SeVeCom system architecture. It
instantiates andconfigures the components of all
other security modules andestablishes the connection
to the Cryptographic Support Module.To cope with
different situations, the Security Managermaintains
different policy sets. Policies can enable or
disablesome of the components or adjust their
configuration, forexample, to enhance or relax the
parameters for a pseudonymchange under certain
circumstances.
B. Communication Stack Integration
To be independent of the actual communication
stack, theintegration of the SeVeCom security system
into the protocolstack is based on a hooking concept,
inspired by similararchitectures such as the Linux
Netfilter kernel subsystem.Inter Layer Proxies (ILPs)
are inserted at several points in thecommunication
stack. Every ILP maintains a list of callbackhandlers
that are to be notified of certain events.During
initialization, the SeVeCom components can
registerat an ILP, subscribing for certain message
types and direction(up or down the stack). Therefore,
they have to implement anevent listener interface and
use the registerHandler() methodto connect to an ILP.
Some components may have to register atmultiple
ILPs, subscribing for different kinds of packets.
Whena message arrives at an ILP, an event callback
is triggered forall components that have registered for
this message type andtheir eventHander() method is
called. The callback includes areference to the
received message, and the component is thenable to
inspect or modify it. By the return value the
componentindicates if the message was modified, if it
should be reinsertedinto the stack, or if it should be
simply dropped by the ILP. The Secure Beaconing
Component, for example, connects tothe ILP above
the MAC layer and checks the signatures of
allincoming beacon messages. Beacons with invalid
signaturesare either discarded or tagged. Using this
hooking architecture,it is possible to transparently
integrate security functionalityinto an existing
network stack with minimal modifications.
Whereas events are triggered by the communication
stack,the security system can also access the stack by
means ofcommand calls using a well-defined API
offered by stacklayers. Command calls could, e.g.
instruct the MAC layer toset its MAC address to that
of a new pseudonym.The hooking concept makes
certain assumptions aboutthe network stack. It
assumes a layered architecture, wherethe ILPs can be
inserted in between, and the stack has toimplement a
certain command API, e.g. for change of
MACaddresses. To be able to port the SeVeCom
architecture tomany different communication
platforms, we also providean additional convergence
layer: This defines an abstractioninterface that
proxies call between the communication systemand
the security components. Whenever the SeVeCom
systemis ported to a new platform, besides adapting
to differentpacket formats, only the ILPs and the
convergence layer haveto be modified, while all other
components remain unaffectedboth in terms of
security and communication.
C. Hardware Security Module
As explained, the purpose of the Hardware
SecurityModule (HSM) is to provide a physically
protected environmentfor the storage of private keys
Proceedings of International Conference on Developments in Engineering Research
ISBN NO : 378 - 26 - 13840 - 9
www.iaetsd.in
INTERNATIONAL ASSOCIATION OF ENGINEERING & TECHNOLOGY FOR SKILL DEVELOPMENT
124

4. and for the execution ofcryptographic operations
using them. Clearly, the full implementationof a
HSM is beyond the scope of the SeVeComProject,
but we can summarize the main requirements
thatsuch an implementation should meet in order to
be applicablefor securing vehicle communication
systems.First of all, the HSM must be tamper
resistant, to someextent. High-end tamper resistant
modules (such as the IBM4758 Cryptographic
Coprocessor) are too expensive to beadded to every
vehicle. At the same time, we observe thatLow-end
tamper resistant devices (such as smart cards) donot
provide all the functionality that we need. In
particular,commercially available low-end devices do
not have built-inbatteries, and consequently, cannot
provide a trusted internalclock. As pointed out,
without a trusted source of time,such devices are not
able to produce time-stamps that canbe trusted by
other participants of the system. Therefore, weneed
an HSM implementation somewhere between high-
endand low-end devices. A potential approach is to
implementthe HSM as an Application-Specific
Integrated Circuit(ASIC)with some special coating
that provides a certain level oftamper resistance.
Such a customized device can provide allthe
necessary functionality by design and it can be
producedin large quantity at sufficiently low costs.
Second, the HSM must have an API, through which
itcan provide services to the other modules of the
securityarchitecture that run on the OBU. This API
should supportthe digital signature and timestamping
service, the decryptionservice, as well as the key and
device management servicesdescribed. We specified
such an API in the SeVeComProject, however,
lacking the appropriate HSM hardware; weonly
implemented it in the form of a software library
runningon a general purpose computer. Nevertheless,
besides beinguseful for demonstration purposes, our
implementation canalso serve as a reference for
future implementations on realHSM devices. In our
implementation, we used ECDSA fordigital signature
generation, ECIES with HMAC-SHA1 andAES-CBC
for encryption, and we fully implemented the
keymanagement services of the HSM described.
Finally, we note that some examples published
showthat physically secure modules can successfully
be attackedthrough their weakly designed API. For
this reason, we usedformal verification techniques to
verify the SeVeCom HSMAPI. Our method is based
on the applied pi-calculus and anautomated
verification tool called Prove it. We proved that akey
generated by an adversary cannot be implanted as a
newroot key in the HSM through the API.
Additionally, short-termand long-term private keys
are proved not to be revealed asthe result of possible
series of function calls.
D. In-Vehicle Security
In order to achieve their full potential, VC systems
need access to the in-car network and sensors that
observe thecurrent status of the vehicle and the
environment. This enablesthe VC system to process
signals such as emergency braking,airbag activation,
and slippery road detection, thus greatlycontributing
to the avoidance of accidents and improvementof
road safety.On-board system signals are transferred
inside the carthrough different networks and
domains. Usually, the networkarchitecture and the in-
car gateways restrict the signals tothe defined
network segments and prevent information
fromleaving its dedicated domains. This clear
architecture andstrict separation is one measure that
ensures the entire vehicle,especially its vital functions
(brakes, engine or airbag control),always operate
reliably and cannot be attacked from the outside.
If this were to be changed into a more open
architecture,for example, allowing reading out sensor
information fromin-vehicle networks or displaying
and reacting to warningmessages from external
sources, it would be absolutely necessaryto ensure
that in-vehicle systems are protected from
anyexternal malicious influence.The In-vehicle
Security Module protects the interface betweenthe in-
car networks and the wireless communicationsystem.
It controls external access to the in-car networks,on-
board control units and vehicle sensor data, but it
alsoensures that data and services required by other
V2V andV2I applications are provided correctly.
Within the in-vehiclesecurity module, two main
components are provided: (i) Afirewall that controls
the data flow from external applicationsto the vehicle
and backwards, and (ii) an Intrusion DetectionSystem
(IDS) that constantly monitors the status of the in-
carsystems and provides real-time detection of
attacks.
The firewall realizes a packet or application based
firewallapproach. Its rule-based table states which
application isallowed to access each kind of data or
service the IDS candynamically add rules to the
firewall table, in order to denyaccess for a specific
application or disable a service.The IDS is based on
an anomaly detection approach,which implies that
normal on-board system behavior is clearlydefined
and specified. If an event results in an on-board
systemstate that is not part of the standard
specification, a potentiallydangerous situation is
detected. Depending on the source andtype of the
Proceedings of International Conference on Developments in Engineering Research
ISBN NO : 378 - 26 - 13840 - 9
www.iaetsd.in
INTERNATIONAL ASSOCIATION OF ENGINEERING & TECHNOLOGY FOR SKILL DEVELOPMENT
125

5. event, appropriate reactions are taken to get
thesystem back to a secure and safe state.
IV. ANALYTICAL MODEL
Realizing field trials for good put evaluation of
vehicular wireless communication systems is very
difficult and costly. Numerous vehicles and
communication equipments need to be involved, and
also many experimenters need to be employed. In this
case, it is highly desirable to obtain theoretical
analysis with real data from small scale scenarios of
practical measurement results and perform an
evolution prior to conducting field trials. In terms of
analysis methods, were mapped previous
approximations of vehicle mobility and good put into
Markov M/M/1/N chain model. Use of Markov
model is novel for evaluation of IEEE802.11n
standard in a mobwith legacy standard (i.e.
IEEE802.11g)
A. System model descript
For this model computation, was considering the case
where the access point’s transmission data rate is
variable through the access point coverage
range.Primitive packets flow from finite wireless
mobile users N and arrive to an infinite buffer of the
system and are served by the server or wireless
access point.
In this case our system is expressed by the Kendall
notation like M/M/1//N where first M-defines
exponential inter arrival times between packet
distribution (Poisson process), second M- defines
exponential data packets transmission time
distribution , next number defines the transmission
channel and N- represents the number of packet
sources.Queuing models for M/M/1/N systems are
very elegant in analysis of wireless data networks in
transmission channel with no packet loss and vehicles
simultaneously under the coverage of the access point
speed-N (v) (i.e, ρ (v). Based on this M/M/1/N
queuing model the average good put by a vehicle can
be computed as follows:
where π0 represent the probability of the idle system
where j = 1,2,3,….,N(v), π – the data packet
transmission rate of the channel between vehicular
and base station, λ is the packet arrival rate in the
coverage range of the access point
B. Results
In the computation of the analytical model in the
previous subsection was constructed a topology with
an access point sending file data to all vehicles within
coverage range of an access point. In the
computation, each vehicle maintains its speed as it
derives through the access point coverage range. The
computation compares the results derived from trial
field tests with analytical model for the single-lane in
vehicle traffic.
The range of good put that a vehicle can receive
from the access point per pass shown in Fig.2. The
results here are for the case where there are two types
of vehicles, i.e, wireless-equipped and non-wireless-
equipped vehicles. The type of vehicles can be
interpreted as the penetration rate of wireless-
equipped vehicles for use.
From the Fig.2 can make the following observations:
At low traffic density corresponding to high vehicle
speed, there are few vehicles and as such there is a
few connections using the access point resource and
the value of good put is close to maximum. It is about
two times less than plausible maximum good put.
Fig.2. Average good put of a vehicle at different
speed and WLAN penetration rate
On low velocity increase value of vehicles and
bandwidth connections increases leading to lower
values of good put for the individual user.
Despite reduction of maximum good put due to
mobility at a velocity from 50 km/h to 100 km/h
improves the good put value of a vehicle.
Proceedings of International Conference on Developments in Engineering Research
ISBN NO : 378 - 26 - 13840 - 9
www.iaetsd.in
INTERNATIONAL ASSOCIATION OF ENGINEERING & TECHNOLOGY FOR SKILL DEVELOPMENT
126

6. Penetration rates specify the possible optimal values
of WLAN performance.
V. CONCLUSION AND FUTURE WORK
In this article was presented field trial
evaluationstogether with theoretical analyses of the
IEEE802.11nstandard comparing with legacy
standard in the vehicleenvironment. The trial field
test was performed in thecontext of simple scenario
of one vehicle and access point.At various velocities
has been testing the performance ofWLAN. Wireless
network link under fluent number ofvehicles
respectively active users simultaneously
realizingsuch field trials for goodput evaluation is
very difficult andcostly. Therefore a simple
mathematical model for goodputevaluation of
vehicular communication systems in V2Iscenario was
presented and analyzed for understanding thebasic
processes in wireless data networks prior
toconducting larger field trials.
We mark that while numbers of necessary real time
application of vehicular networks are the
dissemination ofsafety and traffic condition
messages, we can assume Wi-Fi
for vehicle communication systems in the near future
willalso be requested to provide different
applications, for e.g.web browsing, video streaming,
VoIP, downloading files,WiFi radio, etc. These types
of applications have arequirement for high
throughput during connections to theaccess point and
existing mobile communication systemsexcept
WLAN aren’t able to provide growing needs.And it
is also important to note that the results wereshowing
her serve as information for future analysis anddesign
of vehicle networking systems.
VI. REFERENCES
[1] Janis Jansons, Ernests Petersons,
NikolajsBogdanovs, “WiFi for Vehicular
Communication Systems”, 2013 27th International
Conference on Advanced Information Networking
and Applications Workshops.
[2] "Part 11: Wireless LAN Medium Access Control
(MAC) and PhysicalLayer (PHY) Specifications
Amendment 6: Wireless Access inVehicular
Environments",
http://ieeexplore.ieee.org/servlet/opac?punumber=55
14473, IEEE,15.July, 2010.
[3] IEEE 802.11, The Working Group for WLAN
Standards,http://grouper.ieee.org/groups/802/11/ ,
April, 2006.
[4] ”Part 11: Wireless LAN Medium Access Control
(MAC) and PhysicalLayer (PHY) Specifications
Amendment 5: Enhancements for
HigherThroughput”,
http://ieeexplore.ieee.org/servlet/opac?punumber=53
0729, IEEE, 29.October, 2009.
[5] J. P.Singh, N. Bambos, B. Srinivassan and D.
Clawin, Wireless LANperformance under varied
stress conditions in vehicular trafficscenarios,
proceedings of Vehicular Technology Conference,
2002,Vol. 2, pp. 24-28.
[6] J. Ott, D. Kutscher, “Drive–thru Internet: IEEE
802.11b forAutomobile Users”, IEEE Infocom, Hong
Kong, 2004.
[7] R. Gass, J. Scott, C. Diot, “Measurements of In–
Motion 802.11Networking”, WMCSA '06.
Proceedings, 2006, pp. 69-74.
[8] M. Wellens, B. Westphal, P. Mähönen
“Performance Evaluation ofIEEE 802.11–based
WLANs in Vehicular Scenarios”, Proc. VTCSpring,
2007. pp. 1167–1171.
[9] M. Rubinstein, F. Ben Abdesslem, S.
RodriguesCavalcanti, M. EliasMitreCampista, R.
Alves dos Santos, L. Costa, M. Dias de Amorim,O.
Duarte, “Measuring the capacity of in–car to in–car
vehicularnetworks” IEEE Communications
Magazine, Vol. 47., Iss. 11, 2009.,pp. 128–136.
[10] P. Richards Shock waves on the highway.
Operations Research 4,1956, 42–51.
[11] M. Lighthill and G. Whitham “On kinematic
waves: II. A theory oftraffic on long crowded roads.”
Proc. Roy. Soc. of London A 229,1955, pp 317–345.
[12] B. Kerner and P. Konhauser, “Structure and
parameters of clusters intraffic flow”, Physical
Review E 50, 1994, pp 54–83.
Proceedings of International Conference on Developments in Engineering Research
ISBN NO : 378 - 26 - 13840 - 9
www.iaetsd.in
INTERNATIONAL ASSOCIATION OF ENGINEERING & TECHNOLOGY FOR SKILL DEVELOPMENT
127

7. 7Proceedings of International Conference on Developments in Engineering Research
ISBN NO : 378 - 26 - 13840 - 9
www.iaetsd.in
INTERNATIONAL ASSOCIATION OF ENGINEERING & TECHNOLOGY FOR SKILL DEVELOPMENT
128