1. Lisa Kristiana, Corinna Schmitt, Burkhard Stiller
3rd GI/ITG KuVS Fachgespräch IVC, March 19-20, Ulm, Germany
Investigating a Reliable Inter-vehicle Network in a Three Dimensional Environment
Lisa Kristiana, Corinna Schmitt, Burkhard Stiller
Department of Informatics IFI, Communication Systems Group CSG, University of Zürich UZH
Good afternoon, thank you for the introduction. I would like to present my talk with the research topic of Investigating a reliable inter-vehicle network in a three dimensional environment.

2. Agenda Motivation Characteristics Issues Proposed Model Summary
Future Work 1 2 3 4 5
In the beginning of my presentation, I would like to motivate my talk why I am doing this, then followed by some characteristics and issues which inspire me to propose a new method. Some technical details I provide later on, and to evaluate the proposed method, the preliminary simulation result is also provided. And of course the summary and future work. 6

3. Inter-vehicle Network applications1
Driver
Passengers
Vehicle
As a motivation, I would like to give you a short introduction of Inter-vehicle Application. As we all know, the possible applications provided by inter-vehicle network are classified based on purpose into three categories.
1. Driving-related applications assist a driver to reach traffic safety and a partial efficiency by aggregating road-related information and presenting it to the driver.
2. Passenger-related applications which emphasize on convenience and comfort of passengers on board.
3. Vehicle-related applications, this applications do not have impact on the driver and passengers directly, they improve all operations of vehicles and their internal optimization
In my work’s scope, I am interested on passenger-related applications (i.e. infotainment, social media access, or surfing the Web) which can be implemented on public transportation as busses. To make it happen, the main goal is to provide a reliable and stable connectivity between busses.
The term connectivity here is refer to information that can be interchanged among vehicles and how packet from a sender can successfully reach the destination.
Reliable and stable connectivity.
Goals

4. Large City Road Environment1
Now the question is: how to make reliable and stable connectivity in inter-vehicle Network?
First, lets take a look at the environment. Normally, in the most common environment in a large city, we can see intersections, overpass, building, and high traffic density. Based on that, I try to present the large city environment graph as an example.
I am interested to investigate on what I called a three-dimensional environment, that is a hierarchical road topology as shown in this picture.
I Assume that there are two layers of road, the upper road layer represents an overpass or bridge and the lower road layer represent regular road under over-pass or bridge. Busses are distributed on both road layers and establish connectivity among them. Busses’ connectivity has to deal with a hierarchy road topology i.e., busses enter the tunnel.
Second, as the preliminary investigation we consider two aspects in order to design a proper routing protocol in three-dimensional environment.
First is Propagation characteristics and second is forwarding method which I would like to give you in details.

5. Propagation Characteristics2
Source:
Source: ASFINAG
Based on the large city environment, we now consider the characteristics of propagation.
The first is the propagation characteristics where Building between roads is a massive block and has impact to propagation. It influences the signal reception.
Road topology also has impact for example if there is a tunnel. What happen to signal reception when a bus is entering the tunnel.
and the last one is traffic condition. In this case if busses run on a traffic jam, other vehicles can also form as obstacles and restrict the busses movement. . In other work mentioned impact of existing vehicles can lead to link quality. All of these case are also known as Non Line of Sight propagation model.
Source:

6. Forwarding Method 2
A = Nearest with Forwarding Progress (NFP) B = Most Forwarding progress within Radius (MFR) C = Compass Routing,
Beside the propagation characteristics, there is also forwarding methods characteristics. I would like to give you an overview of the Greedy forwarding methods. As we can see in this figure, The source node or a sender (S) has several options to find a relay node for further forwarding a message to the destination (D). Basically Greedy forwarding is to find intermediate node which has closest distance to the destination, in order to minimize number of hops.
Greedy forwarding method has some variants:
The first relay node is A = Nearest with Forwarding Progress (NFP), which means that S will forward a message to the node which closest to the sender.
S also has option to select B = Most Forwarding progress within Radius (MFR), which means that S will forward a message to the node which basically has the most forwarding progress. MFR is a good strategy in scenario where the sender cannot adapt the signal strength.
An the last one is node C = Compass Routing, where the intermediate node is selected based on the smallest angle with respect to ‘virtual line’ between S and D.
All of these variant are mostly implemented on a planar area.

7. Position-based Routing Protocol2
Greedy Perimeter Stateless Routing (GPSR)
- Greedy Forwarding 3
- Perimeter Forwarding
Here, we discuss about routing protocol issues which based on position location.  A position-based routing in principle, is a routing that relies on geographic position information. We assume here that location service is provided by Global Positioning System (GPS) and location information is error-free.
GPSR as the conventional position-based routing has the following steps:
First, it use Greedy forwarding mechanism, means that the intermediate node is selected because the intermediate node has the closest distance to destination node.
Second, when void area happen it will use the perimeter mechanism based on right hand rule to find the next forwarding node. (counter clock-wise),
(void area is a problem when a current node cannot find an intermediate node in transmission range as shown in grey color)

8. Issues Propagation in hierarchical road topology Forwarding mechanism3
Propagation in hierarchical road topology
Signal attenuation Inside the tunnel
Forwarding mechanism
Greedy forwarding  only satisfy in open space area
Position based routing protocol
Delay IncreasesWrong direction forwarding
By investigating the characteristics we see potential issues in each of them.
First, Propagation in hierarchical road topology, is experiencing signal attenuation such as in a specific case as inside the tunnel
Beside the propagation issues, there is forwarding mechanism issues, that is the greedy forwarding mechanism performs well in only open space area.
Last issue is Position based routing protocol creates significant delay when a wrong direction forwarding occurs.

9. Position-based Routing Algorithm3
Characteristics
Propagation
Forwarding Methods
Three-dimensional area
Greedy Perimeter Stateless Routing
GPSR NO
YES
Link State Hierarchy Routing
LSHR NO
YES
Proposed Solution
Vehicular-to-Vehicular Urban Network
V2VUNet
YES
To the best of our knowledge, For the first position based routing protocol, it only concern about forwarding methods and it does not implement propagation characteristic and three dimensional area, so GPSR performs well only when the propagation is said to be Line-of-Sight. and when three dimensional area is applied, it results a number of delays.
The Second Routing protocol is also based on GPSR mechanism, but in LSHR there is a modification on forwarding method so it can be implemented in three-dimensional area. However, the propagation issue is not implemented, because it assumes that vehicles in upper and lower road layer do not experience signal reception issues.
So, we propose the solution by combining characteristics and trying to reduce the weaknesses as our contribution.
We name it VeVUNet as an abbreviation of Vehicle-to-Vehicle Urban Network. Our goal is to design a reliable vehicle-to-vehicle network in large city environment in order to provide passenger related application.

10. Vehicle to Vehicle Urban Network (V2VUNet)
Proposed Model 4
Vehicle to Vehicle Urban Network (V2VUNet)
Three-dimensional Propagation Mode
Location information (x, y, and z ≠0)
Intermediate Node Filtering
Disconnect transmission
Search for other potential mobile nodes  Greedy Forwarding
In Order to deal with an environment with hierarchical road topology. Our proposed model focuses on connectivity in three-dimensional environment. It has two step as following:
First, the three-dimensional environmental is indicated with hierarchical road topology as shown in this figure. Bus A has the location information of bus B . One of these busses has location coordinates denoted as x, y and z is not equal to zero.
Transmission radius is evaluated between two busses denoted as l, m, and n. Here, l represents the distance where bus A cannot reach bus B, and m represents the distance where bus A has the optimum transmission range to bus B while n represents transmission with attenuation, because bus B will move into the tunnel and signal reception will be very weak or even lost.
Second step, the intermediate node filtering, when Bus B is in distance n, bus A will disconnect transmission and search for other potential mobile nodes using basic greedy forwarding.

11. Simulation Road Topology Scenario Visualize trace file4
Road Topology
Scenario
Visualize trace file
Busses’ mobility
Speed and initial placement
To evaluate the proposed method, we simulate it the hierarchy road topology, simulation time, packet size, the height of upper road etc. in NS3.
Also to visualize the trace file, we use NetAnim as it is embedded in NS3.
Then, to generate busses’ mobility, the speed and initial placement, we use Matlab,

12. Simulation Environment4
Parameter
Transmission Range
1000 m
Routing Protocols
GPSR, V2VUNet
Number of Busses
20 – 50
Simulation Area
2000m x 2000m
Upper Road Height
10 m
Busses Velocity
0 – 60 km/h
Transfer Rate
2048 kbps
Packet Size
64 bits
Simulation TIme
400s
Number of Lane 2
Our simulation running on these parameters, and under this environment where there are busses running on both layer and both direction with two lanes of each layer and intersection. As this is a working on progress, I haven’t included yet other vehicles like taxis or private cars as well as the existence of obstacles such as trees and buildings.
This is the animation snapshot provided by netAnim, shows the simulation area, blue and red dots are the running busses.

13. Throughput vs Number of Busses and Speed of Busses4
This is the preliminary result that shows the throughput of V2VUNet and non-modified forwarding method. The term of Non-modified forwarding method is used because only GPSR routing protocol as a comparison to my proposed method at a moment.
The complete explanation about this graph is:
At low speed, the throughput of V2VUnet is higher than GPSR, this is because the connectivity among busses remain stable. But at high speed, GPSR shows better throughput.
Then, when more busses are added, V2VUNeght performs better than GPSR. It means at dense traffic condition, the average throughput of V2VUNet is higher than GPSR.
Although a small improvement showed, it is important since this indicates that in case of higher traffic density, V2VUNet performs better than GPSR in three-dimensional environment.
However, we need more parameters, more complex scenario, different forwarding method and of course longer simulation time to validate it.

14. Summary Position-based routing protocol requires modification5
Position-based routing protocol requires modification
In three-dimensional area, the transmission range is influenced by obstruction (i.e., tunnel)
V2VUNet performs better in three-dimensional environment in a dense traffic condition.
As a summary, There are three points I learned at the moment,
First, The classic position-based routing protocol such as GPSR does not perform well in three-dimensional environment. It requires modifications and adaptations to road topology.
Second, In a real scenario of three-dimensional area, the transmission range is influenced by obstruction (i.e., tunnel).
Third, V2VUNet shows better performance than GPSR in a condition where road traffic is dense.

15. Future Work Parameter Current Work Future Work 6 Obstacles Tunnel
Building, trees and high vehicles
Number of Busses
Up to 200
Number of Lanes 2
Up to 4
Routing Protocol
GPSR, V2VUNet
Other position-based routing
For my future work, I would do the following steps,
First, It is necessary to include other factors that potentially form obstacles such as buildings and trees. As well as other high vehicles that influence the propagation range.
Second, Traffic condition are added such as traffic density for instance in an intersection road where the vehicle reduce the speed as well as in multiple lanes. Then in sparse network which leads to an intermittent connectivity.
And the last one, I plan to use other modified position-based routing protocol to be compared with my proposed method in order to find the most reliable and stable routing in this particular environment.

16. Thank you

17. References
[1]A. S. Alfa, M. F. Neuts: Modelling Vehicular Traffic Using the Discrete Time Markovian Arrival Process, Transportation Science, Vol. 29, No. 2, pp. 109–117, May 1995 [2]K. Barry: How Smartphones Can Improve Public Transit, Wired, last access October 2014 [3]T. Kosch, C. Schroth, M. Strassberger, M. Bechler: Application Classification and Requirement, Automotive Internetworking, John Wiley & Sons Ltd, pp 13–36, February [4]R. Meraihi, S. M. Senouci, D. E. Meddour, M. Jerbi: Vehicle-to-Vehicle Communications: Application and Perspectives, Wireless Ad Hoc and Sensor Networks, pp , Januari 2010 [5]M. Mauve and B. Scheuermann: VANET Convenience and Efficiency Applications, VANET Vehicular Applications and Inter-Networking Technologies, JohnWiley & Sons Ltd, pp 81 –105, NOV 2009 [6]B. Paul, M. Ibrahim, M. Bikas, and A. Naser: Experimental Analysis of AODV & DSR over TCP & CBR Connections With Varying Speed And Node Density in VANET, Vol. 24, No. 4, pp. 30–37, [7]S. Yousefi, M.-S. Mousavi, M. Fathy: Vehicular Ad Hoc Networks (VANETs): Challenges and Perspectives, 6th International Conference on ITS Telecommunications, Chengdu, China, pp , June 2006 [8]B. Karp and H. T. Kung: GPSR : Greedy Perimeter Stateless Routing for Wireless Networks, International Conference on Mobile Computing and Networking, pp 243–254, 2000 [9]K. Kastaros, M. Dianati, R. Tafazolli: CLWPR - A Novel Cross-layer Optimized Position-based Routing Protocol for VANETs, IEEE Vehicular Networking Conference, (VNC 2011), Amsterdam, Netherland, pp , November [10]K. Katsaros, M. Dianati, K. Roscher: A Position-based Routing Module for Simulation of VANETs in NS-3, Proceedings of the 5th International Institute for Computer Sciences, Social-Informatics and Telecommunications Engineering (ICST) Conference on Simulation Tools and Techniques, (SIMUTOOLS 2012), pp , Desenzano, Italy, March 2012 [11]Q. Lin, C. Li, X. Wang, L. Zhu: A Three-Dimensional Scenario Oriented Routing Protocol in Vehicular Ad Hoc Networks, Vehicular Technology Conference, (VTC Spring 2013), Dresden, pp. 1-5, June 2013.

18. Back up Slides
Using DSRC Max data rate 27 Mbps, Max range 1km and Mobility is very high
WLAN: WiFi Max data rate 11 or 54 Mbps, max range 100 m (outdoor) and mobility is middle
WPAN: ZigBee Max Data rate 250 Kbps, Max range 300 m (outdoor) and mobility is middle
(reference: Vehicular Networks-Model and Algorithms)

19. Three-dimensional Environment

20. GPS Information