Cooperative Download in Vehicular Environments

ABSTRACT:
We consider a complex (i.e., nonlinear) road scenario where users aboard vehicles equipped with communication interfaces are interested in downloading large files from road-side Access Points (APs). We investigate the possibility of exploiting opportunistic encounters among mobile nodes so to augment the transfer rate experienced by vehicular downloaders. To that end, we devise solutions for the selection of carriers and data chunks at the APs, and evaluate them in real-world road topologies, under different AP deployment strategies. Through extensive simulations, we show that carry&forward transfers can significantly increase the download rate of vehicular users in urban/suburban environments, and that such a result holds throughout diverse mobility scenarios, AP placements and network loads.

ARCHITECTURE:

EXISTING SYSTEM:
The cooperative download of contents from users aboard vehicles, that introduced SPAWN, a protocol for the retrieval and sharing of contents vehicular environments. SPAWN is designed for unidirectional traffic over a highway, and is built on the assumption that all on-road vehicles are active downloader’s of a same content.
DISADVANTAGES OF EXISTINGS SYSTEM:
1. Low Network Capacity.
2. Access only simple files not large files.
PROPOSED SYSTEM:
In this paper, we focus on one of the latter tasks, namely the download of large sized files. We identified and proposed solutions to the problems of carrier’s selection and chunk scheduling, and extensively evaluated them. The main contribution of this work lies in the demonstration that vehicular cooperative download in urban environments can bring significant download rate improvements to users traveling on trafficked roads in particular.  
ADVANTAGES OF PROPOSED SYSTEM:
1. Improve the network capacity.
2. Download large-sized files.
3. There are good carry and forward transmission.
4. Cooperative downloads the large sized files.

MODULES:
1. Cooperative Download
2. Chunk Scheduling
2.1 Global
2.2 Hybrid
2.3 Local
3. AP deployment
3.1 Random
3.2 Density-based
3.3 Cross volume-based

MODULES DESCRIPTION:

1. Cooperative Download:

Let us first point out which are the major challenges in the realization of a Vehicular cooperative download system within complex urban road environments. 
The selection of the carrier(s): contacts between cars in urban/suburban environments are not easily predictable. Idle APs cannot randomly or inaccurately select vehicles to carry data chunks, or the latter risks to be never  delivered to their destinations.

Choosing the right carrier(s) for the right downloader vehicle is a key issue in the scenarios we target;

The scheduling of the data chunks: determining which parts of the content should be assigned to one or multiple carriers, and choosing in particular the level of redundancy in this assignment, plays a major role in reducing  the probability that destination vehicles never receive portions of their files.

2. Chunk Scheduling:
Upon selection of a destination for the carry & forward transfer, jointly with the associated local carriers, an AP must decide on which portion of the data the downloader is interested in is to be transferred to the carriers. To that end, we assume that each content is divided into chunks, i.e., small portions of data that can be transferred as a single block from the AP to the carriers, and then from the latter to the destination. Since a same chunk can be transferred by one or multiple APs to one or more carriers, the chunk scheduling problem yields a tradeoff between the reliability (i.e., the probability that a downloader will receive at least one copy of a chunk) and the redundancy (i.e., how many copies of a same chunk are carried around the road topology) of the data transfer.
2.1 Global
The Global chunk scheduling assumes that APs maintain pervehicle distributed chunk databases, similar to the time databases introduced before. These databases store information on which chunks have already been scheduled for either direct or carry & forward delivery to each downloader.

2.2 Hybrid
The Hybrid chunk scheduling allows overlapping between carry & forward transfers scheduled by different APs.
2.3 Local
 The Local chunk scheduling is similar to the Hybrid scheme, since different APs can schedule the same chunks when delegating data to carriers.          

3. AP deployment:
3.1 Random
Under the Random AP positioning scheme, each point of the road topology has the same probability of being selected for the deployment of an AP. The resulting placement may be considered representative of a completely unplanned infrastructure.


3.2 Density-based
The Density-based AP deployment technique aims at maximizing the probability of direct data transfers from APs to downloader vehicles. To that end, this technique places the APs at those crossroads where the traffic is denser.

3.3 Cross volume-based
The Cross volume-based AP placement is designed to favor carry & forward transfers, by increasing the potential for collaboration among vehicles. This technique exploits the predictability of large-scale urban vehicular traffic flows, which are known to follow common mobility patterns over a road topology.
SYSTEM REQUIREMENTS:
HARDWARE REQUIREMENTS:

•         System                 : Pentium IV 2.4 GHz.
•         Hard Disk            : 40 GB.
•         Floppy Drive       : 1.44 Mb.
•         Monitor                : 15 VGA Colour.
•         Mouse                  : Logitech.
•         Ram                      : 512 Mb.

SOFTWARE REQUIREMENTS:

•         Operating system                     :  Windows XP.
•         Coding Language           :  C#.NET
REFERENCE:
Oscar Trullols-Cruces, Student Member, IEEE, Marco Fiore, Member, IEEE, and
Jose M. Barcelo-Ordinas, Member, IEEE, “Cooperative Download in Vehicular Environments”, IEEE TRANSACTIONS ON MOBILE COMPUTING, VOL. 11, NO. 4, APRIL 2012.