presented by:
Avinash H
Jayan Kumar G
Harish M
Bhaskara K M

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Vehicular Monitoring Using Multi-Hop Wireless System
ABSTRACT:-
The accurate location of the accident spot is the key for the correct evaluation of a page link between road and accident process and for right choice of improvement measures in vehicular monitoring systems.
A Multi-hop based wireless adhoc network of nodes can disseminate critical safety information in alert packets. The nodes can be embedded in vehicles. The alert can be used to trigger emergency responses resources. For example, the network can signal unusual events such as accidents, disabled vehicles or road obstructions to operators in nearby vehicles. When the vehicles are equipped with the wireless nodes, the information can easily be broadcast and propagated along the road until the desired destination service center is reached.
Now this concept is used in vehicular accidents to get a medical emergency assistance. When an accident occurs on a road, this is sensed as an event in both victimized vehicles (source node) and an alert packet is broadcast in response to sensing the event. This alert packet is received by a set of candidate nodes (nearby passing vehicles) within a broadcast range of a source node. Each candidate node infers distance between the candidate node and the source node based on the receive power of received alert packet and determines a priority for rebroadcasting the alert packet, wherein the priority is based on the distance to minimizing a probability of collisions while rebroadcast the alert packet and extend a range of the broadcasting.
INTRODUCTION:-
Hop is a method of wireless communication between two nodes. There are levels in hopping namely frequency hopping and multi hopping. Frequency hopping is a technique in which binary data sequence carrying information modulates the frequency of carrier signal resulting in FSK signal. A group of ‘k’ binary bits and a set of 2k subcarrier frequencies are chosen to generate a multi level FSK. This MFSK finally modulates a carrier which hops randomly. By choosing a large number of randomly hopping discrete carrier frequencies it is possible to have a modulated signal of wide bandwidth which in turn results in large processing gain.
Frequency hopping operates between only two nodes so we look for much enhanced operation between multiple nodes hence the improved technology that developed on the basis of frequency hopping called as “Multi HOP ‘’ communication.
Multi Hop communication works on the principle of frequency hop such that each node can communicate with multiple nodes simultaneously i.e., each transmitter can communicate with one or more receivers at a time.
Multi Hop wireless communication system which synchronizes a time signal generated by a timer device included in each of the wireless terminals and sets a different active timing signal to a wireless terminal connected each of a plurality of Multi Hop routes. The wireless terminal monitors the time signal of timer device included in the wireless terminal and activates the wireless communication of the wireless terminal when it is detected such that the timing signal matches an active timing set in the wireless terminal.
GPS:- A tracking system employing global positioning system (GPS) satellites provides extremely accurate position, velocity, and time information for vehicles or any other animate or inanimate object within any mobile radio communication system or information system, including those operating in high rise urban areas. The GSM Modem used with the GPS receiver is used for sending SMS. The GPS receiver calculates the latitude and longitudinal values which are transmitted over to the user mobile through the GSM device.
WORKING PRINCIPLE:-
Consider when the two vehicles are met with an accident as shown in fig (a), then the control system of either or both these vehicles sense this as an event and trigger an emergency alert packet that carry information about medical emergency assistance.
These are sent through wireless Multi-hop communication to the nearest emergency service center through the nearby passing vehicles which are also enabled with same type of wireless control system as shown in fig (b). Each vehicle which receives these packets processes it and retransmits to it’s another nearby passing vehicle. If a vehicle receives a packet which has already received the same, then this packet will be simply discarded off.
This process of chain page link which is a wireless communication continues until an emergency service center is reached.
Once these emergency packets reach the service center such as hospitals, ambulance, etc.., they are decoded and processed and immediately a necessary action is taken by the service personnel about the cause.
A brief description of the preferred embodiment:-
The embodiments of the invention provide a method and system for minimizing a probability of collisions during rebroadcasting of an alert packet in a wireless multi hop broadcast network of nodes. The method assigns a priority to nodes according to a distance, or information that implies a distance, between a source node and a receiving node, i.e., the larger the distance the higher the priority. A node with a higher priority rebroadcasts the packet before a node with a lower priority. If a particular node determines that another node with a higher priority has already rebroadcast the packet, the node does not rebroadcast, thereby reducing the probability of collision as shown in fig ©.
In one embodiment the method uses a global positioning system (GPS) to determine the distances or absolute location of the nodes. The absolute position of the source or relay node is stored in the packet. The actual location can then be used to determine the actual distances between the nodes. This is depicted in fig (d).
The idea of the invention is that if the node is the farthest from the source node transmits first, the coverage area is expanded as quickly as possible, and packet collisions are minimized.
HARDWARE COMPONENTS AND SOFTWARES USED:
HARDWARE REQUIRED
• Multichannel RF Tran receiver module with min 5mtr range
• Small Toy Car Models
• Microcontroller Chip: Atmel or Philips 8051
• Batteries
SOFTWARE REQUIRED
• Microcontroller Chip: Atmel or Philips 8051
• IBM PC with working output port [for connecting uploader]
• Keil Software for writing embedded C program
• PC loaded with Uploader program
• Multichannel RF Transreceiver module with minimum 50 mtr range.
ADVANTAGES:-
 Current scenario of the society is that people do not care about the accident which occurred beside them or near to them. They simply keep on driving along their way without concerning about victimized lives. Hence using this technology they can help the victims indirectly.
 It is helpful in remote areas where there will be no base stations to communicate.
 Enhancing the technology can define various parameters that caused the accident thereby helping cops and insurance companies.