Abstract encouraged a cyber penetration in a

Abstract – A wireless communications will
always be affected by fading, interferences or hidden terminal problems. For
vehicle, an urban scenario is centre stage to roam around the concrete jungle.
Beaconing message is the most common communications which has an ability to let
the vehicle know about its neighbouring vehicle in order to choose a right
forwarder for non-safety or safety message. However, a congestion that resulting
in low messages and overhead beacon that caused by the influx of the broadcast
messages were give a negative impact for a low reception message and in excessive
delay. An emergency messages may be affected from the street beacon and
resulting in interferences. In this paper scheme were proposed in order to
cancel an interferences by using adaptive transmission control because of the
problem caused by communications of inter-street beacons, while at the same
time maintaining the application layer of the transmission range through
network coding and forwarding multi-chop beacon. From the simulation, it show
that the scheme produced is much higher in packet delivery ratio and also have higher successful channel utilization
compared with the CSMA/CA protocol.

Keywords- Control of congestion,
Interference, Coding network,
Beacon.

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I.             INTRODUCTION

  
  It has been witnessed from the industry such as
communication in vehicular network as well as academia. This because of many
applications such as, traffic monitoring, driver assistance infotainment and
collision notifications. From the research conduct it can be conclude that the Internet
and cloud has a negative influence where it is encouraged a cyber penetration in
a big way in a vehicular network. A lot of data application required for the
various intelligent transportation systems (IPTS) in order to be able to
communicate between  ‘Vehicle-to-Vehicle’, (V2V) and also with
a Vehicle Infrastructure networks (V2I). Based on 3 it is say that beaconing
is one of the important necessity to cater a safety applications for DSRC/WAVE.
The bacon must can go to 10 beacons per seconds so it can be able to deal with
the changes of direction for the rear end and head collision of the vehicle. To
improve the accuracy of the neighbourhood information a frequent beaconing is
need to be done. A time needed to be considered if commuting by using a public
transport or private transport. A connection may
establish between the vehicle and the base station through a mobile gateway or
directly 27. Vehicular network may also being used in cellular service in
order to give access services from mobile offloading 28 into the travelling
passenger that follows a private or public transport. A data were forwarded
based on the multi-hop since the sensing in the vehicular network is sensible
because of the plethora incidents. A high bandwidth requirements were had by
all this communications. We can conclude that since by assuming the future WIFI
and mobile communications will exploits the vehicular network it will needed a
lot of MAC and also network layer protocol. Vehicular network has its own
technical challenge such as, high mobility of vehicle, reliability requirements
3 of real time applications, large differences in vehicle speeds;
inter-street interferences 29 and stringent delay. To ensure a considerable
overload only can affect the control channel performances 1 a several kind of
message were generate. The approaching were made based on the interference of
the other vehicle in this paper, where it reduced the interference by lowering
node of each transmission power when the vehicle is not part of the same
segment of the road. Transmission power is reduced for the safety of the
transmission power application and in order to obtain much lower transmission
ranged from the original transmission range needed. Separated by certain
distances, a separated preselecting process need to be done for the forwarding nodes.
The process of rebroadcasting a resulting message were done from the opposite
direction when the forwarder were receive the beacon message. This process will
continues until the beacon message is forwarded anymore and when the range for
the application layer is reached. When transmission power for the beacon
message is reduced, the interference can be negate and it can manage congestion
control. There is several section in this paper, and each section has explain a
different things where, section II present a discussion about the challenges
and state of art, section III described about the protocol that being proposed,
section IV is about the evaluation based on the simulation and the performance
of proposed approach and the final section V is about the conclusion of this
paper and about future work.

II.            RELATED WORKS

    Using a single and separated allocated
channel in order to control the message 14. By
depending on various active safety precautions 12 we can get the accuracy of
the beacon message. When beacon
frequency increase its accuracy also increase, but as a result channel for the
communication became congested because of the higher rate of the beacon.
            

    The
channel busy time problem were occur because of the increasing on the node
density and at the same time it cause decreasing on the reception probability
of beacon 1. In 2, extremely saturated scenario, a reduction in beacon
probability is demonstrated. An obstacles such
as buildings had a major role in vehicular network since it can alter
perspective all together. Many realistic model have been develop for
simulations in this recent years 30. The attenuation were add by these model
to receive the signal. Map and building structures were used to compute the
attenuation. But, the attenuation values varies drastically based upon the
buildings structure and maps. The packet reception is usually much lower for
the city scenario compare to highway scenario 30. Many proposal has been made
in loss recovery model 25 in vehicular network.  Sub layer also were proposed based on
the paper 24 to optimize the broadcasting for VANETs. VANETs can be used to
reduce congestion using rebroadcasting of
message. In 25 a proposal regarding wireless
broadcast transmission using random network were done. Based on the proposal a
combining packets were combine into one source code by linear network coding
for retransmission while the original packets is decode by the receivers. In
26 it explained that the author has discovered that Network coding has a
benefit in improving performance for a repetition based loss recovery in safety
communications.

   Multi-hop and one-hop
only can be supported after the hidden terminal problem is eliminate and by
using implicit acknowledgement 20. Vehicles were move into the opposite
direction because of the node mobility on the control channel, and this caused
by disjoint assigning set of time slot, thus transmission collision is reduced
for road side unit.    As the
topologies became more, higher the control for the congestion became more,
harder because of the change of the network size became more frequent. Four
main approached is adopted in order to reduce the effect of the 81518. Contention
window is considered as ineffective for broadcast message 4 however due to
dynamic variation it enchance the network performance. In
order to adapt with the problem a formulae called as empirical formulae is
proposed, where it functioning based on the received beacons during las few
seconds from neighbours 11.

   By increasing beacon rate
more accurate data can be gain about the neighbours, but at the cost of higher
probability.

   Number of nodes were
influenced by change in transmission power where it share a same bandwidth
channel in the fixed beacon frequency. In the
literature most of the proposal is about a transmission power mechanisms which
has the ability to adapt with the node density. From
17 it show that a proposal done by Artimy where the proposal is about  a transmission power control scheme to
estimate a density for a local traffic in each node then from there a suitable
transmission range will be determine, but the main objective is actually to
maintain the connectivity. At 19 a proposal about a fair power adjustment were
made by Torrent-Moreno. The proposal propose a power management of VANET where
based on the proposal a vehicle can adjust its transmission power and at the
same time keep the beacon load within. Because
of this, a situation where the bandwidth always enables to be reserved is occur
and usually for the driven messages, but the disadvantage is more overhead is
happen cause by the multi-hop is used. If it
were seen based on the congestion scenario, a transmission control mechanisms
can work well, but as a side effect a scalability issue were occur caused by
the congestion 14

   In
this paper we can see the proposed technique can be considered as unique since
it has the ability to reduce transmission power in order to reduce and get rid
the congestion and also the interferences. The proposal indicate that, during
forwarding beacons the channel will be reduced 22.

III.          CODING
NETWORK FOR

  PROTOCOL INTERFERENCE    

 FREE

    Interference Free (NC-IF) protocol is a
proposed protocol with objective to get rid of the interference due to hidden
terminals problems and inter street communications. The proposal were archived
by fulfil the following objective which by reducing the vehicle transmission
range. By doing this it can solve two types of purpose, which is: (a) the
intra-street communications were free allowed by the interferences; and (b)
reduces congestion (beacon load). By assuming the system is aware of the
digitals map a distance between nearby vehicle with the street can be
calculated. In the proposal a power control transmission module were used in
order to deal with the range of the adaptive transmission. In order to archive
the transmission layer range a multi-hop transmission beacon were used, as the
transmission range is reduced; a network coding forwarder must be preselected
as one of the forwarding nodes. The delay may
increase substantially as the hop-counts increase; beacons is allowed forward for a quickest time as
long as the timer and delay control the module.

Figure 1.
Show Inter-street interference

A.
Motivations

    From Figure 1 above, it seen that when ‘S’
Node send a beacon, it’s received by the other nodes at the neighbourhood. This
beacon messages is important to be received by nodes 1,2,3,4,5,6 and 7 because
it’s shared same road segment with node S. The
beacon messages may be receive successfully send by F  neither by nodes A,B,C,E and F, or an
interesting signal will be received. Because of the various obstacles come from
the buildings the beacon has no choice but come through it and resulting in a
several attenuated signal even though the nodes in within the S transmission
range. Since beacon S shared same bandwidth with the others nodes (A,B,C,E,F)
it is not a very good phenomena even some of the node successfully in receiving
the beacon messages. Thus the transmission power for node ‘S’ need to be
reduced and multi-hop beacon is send in order to ensure it reach the same road
segment for the neighbouring node.

B.
Power Control of Dynamic Transmission

   It is required about 300m for the
transmission range layer (R) by the DSRC based active-safety application 21.
Forwarding nodes is needed in order to forward beacon in multi-hop, and at the
same time it will allow for the vehicles to receive the beacons sending from
the other vehicle (R vehicle) in apart distance. To take care the forwarding
there is a forwarding node. After the power is reduced one of the forwarder is
put within the transmission range. ‘T’ is denoted as the transmission range
where it should be at least 50 meters at most R. A distance between the nearby
road segment with the vehicle is considered as D. Initial value of T can be
defined as:

T=  + D                (1)

    Multiple of D is transmission range, T. The
lowest transmission range a node poses is the initial value of, T. Usually a
problem such as terminal problem is a lesser importance since the neighbouring
connectivity is more important in a case when the scenario is lower.  The transmission range still increase even
there is a few packets of beacon getting drop because of the hidden terminal
and inter street interference problem. The new transmission range can go up to
T=R as it became T=T+D. ‘T’ will be computed by using equation in (1) if the
situation change for example is density.

C.
Selection of NC-Forwarders

    In
order for every vehicle can send its beacon between the R, transmission range it
must be preselected so that the multi-hop forwarding can be used. In forwarding node selection it is must be done
without interfere the communications of inter-vehicle. The forwarding nodes
known as Network coding forwards or also known as NC-Forwarders. The distance
between these forwarders must be at least 50m which is same with M. Selection
must be made start from the extreme south west point in the road segment. We
consider that the road segment is lies from left to right horizontally as in
the example where the nodes P in the left side get declared as a NC-Forwarders. After the beacon message is received there is another node which declares itself as a
NC-Forwarder known as node Q where after receive a beacon message it lies in
the right side of P.
When nodes receive a declaration from node Q it cannot declare itself in the
area of the neighbourhood P as NC-Forwarder. When
the process continue into the right side of Q the moving direction of all
NC-Forwarders is moving at the same direction as P. A new node will take over
after the NC-Forwarder leaves the road segment.

D.
Network Coding of forwarding Multi-hop beacon

    By using Multi-hop the power transmission of
the vehicle were reduced and at the same tie the messages were also forwarding
by Multi-hop. A transmission range will
be reduced as a result from overhead where every vehicle will broadcast the
beacons, thus a significant delay problem will occur for the multi-hop and
finally the beacon message cannot be lowered. By adopting the
efficient forwarding mechanisms hop delay can be reduced as explained in E
section. As a result the contention delay will be lowered and as the number for
the packet transmission can be reduced the queuing delay also is. Maximum
benefits of reducing transmission range and to overcome the issue can be
achieve by exploiting the packet level of the network coding 22.

   
Forwarding algorithm: Has a function to
improve the overall throughput where the packet level network coding were
applied. To take appropriate coding decisions each of the nodes maintain a
coding table along with the neighbours table. In neighbours table it is contain
of position, id, transmission power and speed of neighbours. Beacon received
from a node and NodeID are include in each entry of the coding table.

   The position of the sender
with the transmission power were used in order
to determine the forwarding region from receiving the beacon when the nodes is
types NC-Forwarder. If it is inside the forwarding region it will became one of
the candidates which has a function to forward the beacon. To
choose the node as a forwarder it must fulfil the condition where it must be
the farthest NC-Forwarder where it must in within the forwarding region and
also must from the sender among all the NC-Forwarders

Figure 2.
Show forwarding and network coding for multi-hop.

    The
beacon only can be coded when the sender is not within the range between each
other, where this applied when there is two received beacons. Here we let the beacon be terms as a partner beacon.
A suitable partner will be search by the node in its coding table. In order to locate the neighbour entry a Node ID is
used for every entry based on the table code. Update position were update using
neighbours dynamics such as position, speed and acceleration. For the neighbour
to have an ability to serve as a partner beacon the update for the position is
needed. When the partner beacons is found a coded beacon will be formed between
node XORs and the received beacon. If not, the node ID with the sender ID will
be put away into the table coding and will be stored there until a partner for
the beacon is received. From Figure 2 it can be
seen that the transmission range R of the application layer were in node S. As the transmission
range is reduced the beacons is forwarded through X,Y and Z to the one end. The
left side of node S is replicated in this process. The broadcasted beacon messages
from S were all received by the neighbours including node X and S. Beacon
message might be received from the right for node X. Here
node X has a function to apply network coding into the packet then rebroadcast
the node. Besides that, the network will be rebroadcast when node X has extract
the beacons sent by S. The applying network coding will only will get
rebroadcast when node Z receives the packets for the network coded. Coded packet
A XOR B were created after node Z performs the XOR operations, thus finally
broadcast it when it receiving a packets from A and B. When X and Y received
the network packet a it still can obtain the
packets from each other just by XOR-ring again with their own packet.

    Forwarder
will receive two packets of beacons as a result of opposing direction in order
to make a maximum benefits from the network coding. If forwarder not receive
any beacon packets or only receive a packets from one direction only then it
will start to starve. Total delay will increase in this forwarding. It is impossible for the network to receive a packet
from one direction while the others packets also follow from other direction.
Forwarder will not wait for another packets in order to form a network coding
packets since it will forwards the packets immediately when it is in approach.  

E.
Timer and delay control

    NC-Forwarders
broadcast its network coding packets along with its beacon message. A scheduling mechanisms is required for such high
number of message exchange. All of the idle
period were keep in track by sensing the medium of the NC-Forwarders. When the beacon message is received for a new
vehicle the NC-slots will update if not a new message for the vehicle will not
exist. When NC-Forwarders receive more than one
beacon message from opposite site a new network coding need to be applied thus
a new packet will be scheduled so it can be broadcast. When the situation where
the a new packet is not receive a new packet were receive will be broadcast directly
without need to apply a network coding.

F.  Coding Gain Estimation

   Packet
for (1-p) is forwarded without using a network coding based in the proposed
scheme. The number of vehicle between transmission range is given by n/h, where
n is defined total vehicle in the road segment

              (2)

          (h-1)                (3)

   Nc
and Nwc based on the equation above is defined as a number of transmission.
Since P=3/4 gain given by Nwc/Nc became very high.

 

IV. EVALUATION OF PERFORMANCE

A. 
Metrics of the performances

   
1)    Packet Delivery Ratio: Can be defined as a number of vehicle that
can receive a beacon into the total expected receivers. Dissemination is one of
the important criterion in beacon transmission system where it is worth to
compare it with the packet delivery ratio CSMA/CA proposed in this paper.   

2)    Successful
channel busy time: Average time period can be defined as a channel which is
busy receiving a beacons in the state of average period of time. A measurement
were done for each node where it is set to 1 sec for every measurement. In
order to ensure the message reception is successful it is action take in
measure of the channel utilization.

3)    Average
Beacon Forwarding Delay: Can be defined as a nodes within the application
layer (between nodes to another nodes) in a transmission range which also can
be known as average delay for beacon to be received.   

4)   
Coding gain: Can be defined as a ratio of the transmitted network
packet to the ratio of the network coding transmitted packets.

Table
1: Simulation of Parameters

Data
Rate

3Mbps

Transmission
Range

50m,100m,150m,200m
,250m,300m

Model
of channel

Two
Ray Ground

Number
of Streets

4

Road
Length

1km

Velocity

10m/s-20m/s

Size packet

200Bytes

Random
noise

5dB-26dB

Bacons
numbers

10
Beacons/sec

 

B.   Simulation Setup

    Matlab were used to perform the simulation.
The simulation were done to find out about the NC-IF protocol performance.
Information (parameter) in order to run the simulation can be seen on the Table
1. The simulation were run in the environment where a 1km lanes is separated
with distance, 100m. In the simulation, when the receiver is not belong to the
segment where the beacon is forwarded an attenuation (a random one) will be put
at the end of the receivers. For the simulation Ns-2 is choose.

C.
  Result and Discussion

    As can be seen on Figure 3 a result from the
simulation for varying node density for the packets delivery ratio were
presented. From the simulation done we can see that there is a decreasing in both of the protocol for the
packet delivery ratio as the node density is increase. It is shown that, the
CSMA/CA is suffering from the congestion and collision where it can be said
that it happen as one of the impact from the interference. When the NC-IF has
no interferences thus we know that the packets is free from the collision
problem. Based on the simulation we learn that with high densities a PDR in
CSMA/CA has a very high degradation problem. From the observation, when there is a lot of collision occur it will
resulting in many vehicles which choose a same beacon interferences-(cause of
such severity).

   From
the simulation we were presented in Figure 4 is a delay protocol (NC-IF)
compared with the CSMA/CA. To remove the interference during the simulation a
multiple hop were choose, but in case of CSMA/CA one hops were used to get rid
the interferences. Even the interferences were getting rid a number of vehicles
is not much changing, this because of the position where it much close to the
old position since the delay is so low.

    An identical channel can be seen from the
result of the simulation for both of the protocol as can be seen in Figure 5.
We want to conclude that, most of the packets were received successfully even
though extra packet were send. As result NC-IF is not changed even at the busy
time.

    Coding gain is shown in Figure 6. From the graph
simulate it can be seen that a 1.3 coding gain high where it is around 30%. Besides
that, the gain is increased when there is increasing in node density. When node
density is increasing we learn that the power of the transmission also reduced
adaptively while at the same time when the node density increase the number of
hops also increase. Thus, as the node density increased the gain is
higher.

Figure
3: Ratio of Packet Delivery

Figure
4: Delay of Beacon Transmission within Transmission Distance of Application
Layer (i.e 300m)

Figure
5:  Channel successful in busy time (Time
of node spend in successfully receiving packets)

Figure
6: NC-IF coding gain

V. 
FUTURE WORKS AND CONCLUSION

   
The benefit of the network coding and the power control of the
adaptive transmission power is evaluated in to reduce overhead beacon and inter-street
interferences. By reducing the transmission range of the beacons the channel
contention also reduce. For transmission range specified in safety applications
the beacons can be delivered into the receivers placed with exploiting the
level for the network coding packet. The basic CSMA/CA were outperform in terms
of packets ratio delivery in the proposed scheme and it same with the channel
successful in busy time as can be seen on the simulation conduct. The multi-hop
delay beacon is under control as shown from the simulation as an evident. It is confirmed that the nodes has the ability to
send a beacon into the significant number of receivers at the high density
scenario.

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