=Paper= {{Paper |id=None |storemode=property |title=Investigation of Data Transfer Capabilities for Heterogeneous Service Support in Critical Mobile Objects Communication Situations |pdfUrl=https://ceur-ws.org/Vol-924/paper15.pdf |volume=Vol-924 |dblpUrl=https://dblp.org/rec/conf/balt/KurmisDA12 }} ==Investigation of Data Transfer Capabilities for Heterogeneous Service Support in Critical Mobile Objects Communication Situations== https://ceur-ws.org/Vol-924/paper15.pdf

154

Investigation of Data Transfer Capabilities
for Heterogeneous Service Support in
Critical Mobile Objects Communication
Situations
Mindaugas KURMISa,c, 1, Dale DZEMYDIENEb and Arunas ANDZIULISc
a
Vilnius University, Institute of Mathematics and Informatics, Lithuania
b
Mykolas Romeris University, Department of Informatics and Software Systems
Lithuania
c
Klaipeda University, Informatics Engineering Department, Lithuania

Abstract. Research of heterogeneous service providing in the fast-changing
topology vehicular communication networks are important because expansion and
integration of this intelligent transport systems platform would greatly improve
traffic safety and reduce injuries on the road. At the same time, the trips would be
more comfortable. In this work, it is investigated data-transfer capabilities for
heterogeneous service support, road safety, assessed their integration potentials
and prospects in vehicle communication networks with changing topology. It is
showed that to provide quality heterogeneous services it is necessary new routing
protocols and channel access methods for the large volume fast changing topology
networks.

Keywords. Multimedia services, vehicular communication networks, routing ad-
hoc networks, mobile nodes, changing topology

Introduction

Today, the vehicle is a very important component of human life, so installed
intelligence based software and hardware equipment, can improve the level of travel
safety and comfort. Currently, one of the most attentions attracting mobile
communication technology is vehicular wireless communication networks. They offer
the potential to develop and produce safer, more reliable, economic and comfortable
vehicles. These networks are gaining more and more commercial relevance, since the
adoption of DSRC (Dedicated Short-Range Communication) / IEEE 802.11p (Wireless
access in vehicular environments (WAVE)) standards in both the EU and the U.S.,
given the possibility to reach an entirely new level of service in a vehicle, covering
many areas, including road safety, traffic management, comfort applications. Vehicles
do not have strict restrictions on power consumption, and therefore, can be easily
equipped with powerful computing devices, wireless transmitters, sensors, complex

1
Mindaugas Kurmis, Vilnius University, Institute of Mathematics and Informatics, Akademijos str. 4,
Vilnius, Lithuania, LT-08663, mindaugas.kurmis@mii.vu.lt, +37065370031
M. Kurmis et al. / Investigation of Data Transfer Capabilities for Heterogeneous Service Support… 155

systems - GPS, photo / video cameras, vibration, acoustic, chemical sensors and, etc.
[1].
Practices of vehicular communication network's deployment, research and
scientific projects are developing in two directions: direct vehicle-vehicle (V2V)
communication and vehicle-to-infrastructure (V2I) communication [2]. Research in this
area addresses many complex communication problems as there are many specific
determinants of the quality of communication, including highly dynamic traffic and
communication conditions, frequent disconnection of nodes as well as heterogeneity of
data transmission links.
This paper explores the evaluation of the data-transfer efficiency in a mobile
communication network when the sender and the receiver is moving in opposite
directions at high speed. It is organized as follows: in Section 1, we analyze the
vehicular communication networks and their architecture, in Section 2, we briefly
present related works. Section 3 describes the experiment methodology and simulation
model. In Section 4, we provide the simulation results for our model. Section 5 offers
our conclusions and prospects for future research.

1. Vehicular Communication Networks and Their Architecture

Vehicular communication networks can be formed spontaneously between the moving
nodes that are equipped with the homogeneous or heterogeneous wireless interfaces
(802.11a/b/g/n/p, WiMax, 3G, LTE and so on.). These networks, also known as the
VANET (Vehicular Ad-Hoc Network) is one of the MANET (mobile ad-hoc network)
applications, allowing communication between the nearby vehicles and vehicles and
stationary equipment (road side units). Vehicular communication application areas can
be divided into three main categories: general information - multimedia services, road
safety and traffic monitoring and management services [2].
An analysis of the scenarios where the communication is made between the sender
and the recipient moving in the opposite directions was made; it is given in Table 1.

Table 1. Scenario analysis of the vehicular communication network
Rural Town City Highway
Average speed Average Low Very low Very high
of the nodes
Node density Low Average Very high Average/low
Interference Low Average Very high Low

1.1. The Specific Characteristics of the Vehicular Communication Networks

Vehicular communication networks have special characteristics and properties that
distinguish them from other types of mobile communication networks. According to
[3] and [4], it was summarized the following unique features:
• High energy reserve;
• Huge mass and size of the vehicle;
• Moving by the patterns.
156 M. Kurmis et al. / Investigation of Data Transfer Capabilities for Heterogeneous Service Support…

Vehicles have much greater energy reserves, compared with a conventional mobile
device. Energy can be obtained from the rechargeable battery and gasoline, diesel or
alternative-fuel motor. The vehicles are many times greater and larger compared to
traditional wireless devices, and therefore, can support a much greater and heavier
computing, radio and sensor components. Computers can be bigger, faster, and provide
very high-capacity memory devices (terabytes of data), and powerful wireless
interfaces, capable of high speed communication. The vehicles can move at very high
speed (160 km/h or more), making it difficult to maintain a consistent, coherent V2V
communication. However, the existing statistical data on vehicle movements, such as
the movement together according to certain patterns or peak time can help to maintain a
link between the mobile automotive groups. Vehicle at any time may be out of
communication coverage (WiFi, cellular, satellite, etc.), so the network protocols must
be designed so that it can easily connect to the Internet, in normal mode. Despite the
many positive unique features, vehicular network's development is faced with specific
challenges, as their primary:
• Large-scale networks;
• High level of mobility;
• Fragmentation of the network;
• Changing topology;
• Complex communication quality assurance.
Unlike the literature described ad-hoc networks, which are quite limited in size,
vehicular communication networks, in principle, can extend across the road network
and cover a huge amount of network equipment (vehicles). The environment in which
networks are operating is extremely dynamic and, in some cases it may be highly
different, for example, in highway speeds can reach up to 300 km/h, in the low-density
roads car density may be as only about 1-2 cars kilometer. On the other hand, the speed
of cars in urban areas is 50-60 km/h and the car density is quite high, particularly
during the peak periods. Often vehicular communication networks may be fragmented.
The dynamic nature of traffic can lead to large gaps between cars in sparsely
populated areas; it can also be created a few isolated clusters of network nodes.
Vehicular communication networks' scenarios are highly different from the classic ad-
hoc networks, since the cars are moving and constantly changing positions, scenarios
are highly dynamic. Furthermore, the network topology changes extremely frequently,
since the very frequent connections and disconnects between network nodes. In fact,
the degree to which the network is combined depends on two factors: the distance
between the wireless nodes and number of connected vehicles [5].

2. Related Work

There is a growing literature on data-transfer capabilities for heterogeneous service
support within vehicular networks, some of which have also considered the application
of our analyzing problem. We briefly discuss the key the most recent relevant
references next, and highlight their difference from our approach.
Analysis of the performance of DSRC-based VANETs in delivering CVSS
(Cooperative vehicle safety systems) messages was made in [6]. Here a network
performance measure is defined, which can be used as an indicator for the success of
M. Kurmis et al. / Investigation of Data Transfer Capabilities for Heterogeneous Service Support… 157

CVSS tracking application. A study into how controllable parameters such as rate and
range of transmission affect this performance measure has revealed interesting
properties of IDR. It is shown that robust control of rate or range of transmission based
on the relationship between IDR and channel occupancy is possible. Based on these
concepts, a robust range control method is analyzed and evaluated.
Another performance evaluation of information propagation in a vehicular ad-hoc
network was made in [7]. The authors’ studies packet loss rate, expected transmission
distance and effective coverage range of road-side station. They state that
communication performances are similar under three distributions in most cases where
negative-exponential distribution shows the worst performance. It can be assumed that
under negative-exponential distribution, the randomness of space headway is strong,
this will break down the connectivity of the communication chain.
In [8] presents results for 35 field trial data sets collected in Australia, Italy,
Germany, Austria, and the United States, covering over 1100 km on the road in a wide
variety of physical environments. The performance results reveal that DSRC/ WAVE
can provide highly reliable communications, and sufficient driver warning times in
support of the targeted road safety applications. However, analysis of channel sounding
data collected shows that NLOS safety-critical conditions require careful attention to
physical layer receiver processing in order to provide a safety benefit.
The performance modeling of message dissemination in vehicular ad-hoc networks
with two priority classes of traffic was presented in [9]. The results showed that the
probability of a receiving node being exposed to interference increases as a function of
the transmission range, and that this increase is faster at higher-density node traffic.
Performance of the 802.11p Physical Layer was estimating in the [10]. Authors
have found that the primary problem is that the channel estimation mechanisms built
into the 802.11p standard only allows for channel estimation at the beginning of each
packet. Because the packet length is not restricted by the standard, the initial channel
estimate can expire before the packet has completed transmission. They state that, the
channel estimate must be updated throughout the length of the packet. Furthermore,
authors make the conclusion that the maximization of throughput is a tradeoff between
high overhead at short packet lengths and poor performance at longer packet lengths.
Nevertheless, the growing number in of researches in terms of data-transfer
capabilities in vehicular communication networks, none of them investigates a special
scenario where the nodes are moving in the opposite direction in a highway. From this
point of view, our work is different and novel.

3. Methodology and Experimental Model

As it was mentioned in the previous section, the services in the vehicular
communication networks can be classified into the road safety, information and
multimedia services' categories. To support high-quality services it must be taken into
account the data rate, packet delivery efficiency and collision rate. The analysis shows
systematic data quality requirements for different services for vehicular communication
networks (Table 2). To determine the influence of the number of vehicles in connection
capacity it was made a number of experiments which goal is to evaluate data-transfer
efficiency when providing mobile multimedia services in the communicative network
between in the opposite directions moving sender and receiver nodes at high speed.
158 M. Kurmis et al. / Investigation of Data Transfer Capabilities for Heterogeneous Service Support…

Table 2. Data transmission quality requirements for different services support in vehicular communication
networks, by the [11, 12]
Service Packet size (in Packet loss Periodicity of Tolerated
bytes) / required influence transmitted data latency (ms)
throughput (KB/s)
Road safety
services
Lane changing ~100 / 1 Average Event ~100
Traffic light ~100 / 1 Average Periodic ~100
control
Warnings about ~100 / 1 High Event ~100
dangers
Warnings on ~100 / 1 Average Periodic ~100
road conditions
Multimedia
services
IPTV ~1300 / 500 Average Periodic <200
VOIP ~100 / 64 Average Periodic <150
Video/audio As high as possible High Periodic -
files exchange
Games As high as possible High Periodic -

The experiments were carried out in the simulation environment NCTUns 6.0 [13],
which was installed on Fedora 12 Linux operating system. The environment was
chosen as it uses the existent Linux TCP/UDP/IP protocols stack, it provides high-
accuracy results; it can be used with any actual Unix application on a simulated node
without additional modifications; it supports 802.11a/b/p, 802.16e communication
networks and vehicle mobility modeling, user-friendly user interface, and it is capable
of repeated the simulation results. In the experimental scenario (Figure 1), a node (4)
sends data to the node (11). Communication is provided via 801.11b standard interface
and is used multi-hop data transmission method.
It was analyzed and structured requirements for the NCTUns simulation model
(Table 3). The experiment was carried out when the number of nodes in the network is
from 10 to 100 - simulating different traffic congestion to determine the impact of the
vehicle's number for the data-transfer efficiency. Senders and receiver's nodes are
moving at high speed (130 km/h) in the opposite directions. The remaining vehicles are
moving at different speeds from 90 km/h to 150 km/h, and their speed and directions of
movement are spread evenly. These parameters are chosen to simulate the realistic
movement of cars on highway conditions.

Figure 1. The experimental scenario
M. Kurmis et al. / Investigation of Data Transfer Capabilities for Heterogeneous Service Support… 159

Table 3. Simulation parameters for the experiment
Parameter Value
Simulation time 60 s
Physical layer 802.11b
protocol
Number of nodes from 10 to 100
Nodes mobility Random,
model highway
Channel frequency 2,4 GHz
Routing protocol AODV

4. Experimental Results

During the experiments, it was evaluated data transmission efficiency – outgoing
throughput, download throughput, packet drops and collisions with a different number
of vehicles on the network. The data was transmitted using the UDP protocol, and a
packet size of 1000 bytes. Simulation was carried out for 60 seconds. The assumption
was made that the communication time between the sender and the recipient is directly
proportional to the number of cars on the network. Furthermore, with increasing
number of nodes it is expected to increase the collision rate and rejected packets.
Analysis of the data collected during the experiments shows the download speed
versus time, with a different node's number on the network (Figure 2). The graph
shows that the longest communication time is achieved by operating the largest
network of vehicles - 100. With the maximum number of vehicles, the network
coverage increases, so the data can be transferred for a longer period of time. With 100
vehicles and about 330 KB/s data transfer rate, we have managed to maintain
communication for 30 seconds. The speed from 31 s decreased to 50 Kb/s, but from 37
s to 41 s the rate rises to 230 Kb/s, and from 46 s to 48 s - to 130 KB/s. When the
vehicles passed each other the connection was lost. The minimum data rate was
achieved by the network operating 50 vehicles. Moreover, in this case, the shortest
communication time is achieved. With a small number of vehicles (10-30), it is
maintained a relatively high data transfer rate, due to the low collision rate.

400
Troughput in the receiver node, KB/s

10 auto
350
30 auto
300
50 auto
250
100 auto
200

150

100

0
1 6 11 16 21 26 31 36 41 46 51 56
Time, s

Figure 2. Data download rate dependence from time with a different number of vehicles in the network
160 M. Kurmis et al. / Investigation of Data Transfer Capabilities for Heterogeneous Service Support…

After the experiment, the other important parameter - the average data uplink and
downlink throughput was measured (Figure 3). In this case, the highest mean transfer
rate achieved by the network operating 20 vehicles, while the meanest - 30. The
maximum average data rate of downlink – 100 vehicles, while the meanest – 50.

600
Data troughput, KB/s

500 Sender node
400
300
Receiver
200
node
100
0
10 auto 20 auto 30 auto 40 auto 50 auto 75 auto 100 auto
Number of nodes

Figure 3. The average data downlink and uplink throughput with a different number of vehicles

It was found out collision's dependence on sender and receiver nodes with a
different number of vehicles (Figure 4). Collision rate is directly proportional to the
number of vehicles. Up to 40 vehicles, collisions rate at the receiver and sender nodes
is similar, but from 50 vehicles, collision is greater in sender node because of
unsuitable channel access mechanisms.

16000
Sender node
14000
Number of collisions

12000
10000 Receiver node
8000
6000
4000
2000
0
10 auto 20 auto 30 auto 40 auto 50 auto 75 auto 100 auto
Number of nodes

Figure 4. Collisions rate dependence on receiver and sender nodes with a different number of vehicles

5. Conclusions

It was performed the experiments in which was investigated communication and data-
transfer efficiency between at high speed moving sender and receiver nodes in the
opposite directions, in the mobile multimedia services communicative network. The
goal was reached, and it was estimated the transmission efficiency and quality of
communication. It was found that the longest communication can be maintained at the
maximum number of vehicles, but that communication quality is inversely proportional
M. Kurmis et al. / Investigation of Data Transfer Capabilities for Heterogeneous Service Support… 161

with the number of vehicles, as the increasing number of vehicles - increasing data and
network flooding occurs in many collisions.
To provide quality heterogeneous services it is necessary new routing protocols
and channel access methods for the large volume fast changing topology networks.
This investigation is important because it examining problems associated with
communication between the sender and the receiver moving in opposite directions in
highway, where the network topology varies very rapidly and, which may contain from
one to several hundred of the network nodes. Future plans to extend the study to
include other proactive, reactive and hybrid (ADV, DSDV, AORP, etc.) routing
protocols.

Acknowledgements

The authors thank the Projects LLII-061 Development of Joint Research and Training
Centre in High Technology Area and LLIV-215 JRTC Extension in Area of
Development of Distributed Real-Time Signal Processing and Control Systems for the
possibility to complete a scientific research.

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