01-01-2013, 12:59 PM
Vehicle Ad hoc NETworks & Vehicle Safety Communications
[attachment=45968]
Introduction
VANET is one the most challenging flavour of MANET due to high and unpredictable dynamic topology, frequent disconnections.
A Vehicular Ad-Hoc Network is a technology that uses moving cars as nodes in a network to create a mobile network.
VANET turns every participating car into a wireless router or node, allowing cars approximately 100 to 300 metres of each other to connect and, in turn, create a network with a wide range.
As cars fall out of the signal range and drop out of the network, other cars can join in, connecting vehicles to one another so that a mobile Internet is created.
VANET Architecture
In-Vehicle Domain
On-Board Unit(OBU)
OBU responsible for all shared resources between AUs (including external communications).
Application Unit(AU)
Local network/bus to link OBU with all Au’s
Ad hoc Domain
Vehicles to Vehicles (OBUs to OBUs)
Vehicles to Infrastructure (OBUs to RSUs)
Infrastructure Domain
RSUs to RSUs
RSUs to Internet
but also possibly.. vehicles using Wi-Fi or 3G/4G cellular networks
Geographic Source Routing:
Geographic routing is a routing that each node knows it’s own & neighbour node geographic position by position determining services like GPS.
GSR routing is a combination of position-based routing with topological knowledge.
It doesn’t maintain any routing table or exchange any link state information with neighbour nodes.
Information from GPS device is used for routing decision.
Route discovery & management is not required.
Suitable for high node mobility pattern.
Postion Based Routing
Position-based routing protocols requires information about physical position of the participating nodes .
Position is available to the direct neighbours from periodically transmitted beacons.
Routing decision at each node based on the destination’s position contained in the packet and the position of the forwarding node’s neighbours.
Position-based routing does not require establishment /maintenance of routes.
PBR protocol uses greedy forwarding mechanism in which packets are forwarded through nodes geographically closer to the destination than the previous node.
Position of next hop will always be closer to destination node than that of current hop.
Direction Awareness Routing
Mostly used in highway traffic roads.
Cars travelling in the opposite direction are briefly connected than that same direction are connected for extended periods of time.
Choosing peers in the same direction instead of the opposite direction reduces frequent topology changes.
Peer selection policy reduces the rate of topology changes & frequency of route changes, and increasing efficiency of routing.
Dynamic MANET On Demand:
Reduce system requirements of participating nodes, and simplify protocol implementation.
Provides features such as covering possible MANET–Internet gateway scenarios and implementing path accumulation.
Along with route information about a requested target, a node will receive information about all intermediate nodes of a newly discovered path.
Similar to AODV but with slight modification.
AODV, node A knows only the routes to nodes B and D after its route request is satisfied.
DYMO, the node additionally learned a route to node C.
[attachment=45968]
Introduction
VANET is one the most challenging flavour of MANET due to high and unpredictable dynamic topology, frequent disconnections.
A Vehicular Ad-Hoc Network is a technology that uses moving cars as nodes in a network to create a mobile network.
VANET turns every participating car into a wireless router or node, allowing cars approximately 100 to 300 metres of each other to connect and, in turn, create a network with a wide range.
As cars fall out of the signal range and drop out of the network, other cars can join in, connecting vehicles to one another so that a mobile Internet is created.
VANET Architecture
In-Vehicle Domain
On-Board Unit(OBU)
OBU responsible for all shared resources between AUs (including external communications).
Application Unit(AU)
Local network/bus to link OBU with all Au’s
Ad hoc Domain
Vehicles to Vehicles (OBUs to OBUs)
Vehicles to Infrastructure (OBUs to RSUs)
Infrastructure Domain
RSUs to RSUs
RSUs to Internet
but also possibly.. vehicles using Wi-Fi or 3G/4G cellular networks
Geographic Source Routing:
Geographic routing is a routing that each node knows it’s own & neighbour node geographic position by position determining services like GPS.
GSR routing is a combination of position-based routing with topological knowledge.
It doesn’t maintain any routing table or exchange any link state information with neighbour nodes.
Information from GPS device is used for routing decision.
Route discovery & management is not required.
Suitable for high node mobility pattern.
Postion Based Routing
Position-based routing protocols requires information about physical position of the participating nodes .
Position is available to the direct neighbours from periodically transmitted beacons.
Routing decision at each node based on the destination’s position contained in the packet and the position of the forwarding node’s neighbours.
Position-based routing does not require establishment /maintenance of routes.
PBR protocol uses greedy forwarding mechanism in which packets are forwarded through nodes geographically closer to the destination than the previous node.
Position of next hop will always be closer to destination node than that of current hop.
Direction Awareness Routing
Mostly used in highway traffic roads.
Cars travelling in the opposite direction are briefly connected than that same direction are connected for extended periods of time.
Choosing peers in the same direction instead of the opposite direction reduces frequent topology changes.
Peer selection policy reduces the rate of topology changes & frequency of route changes, and increasing efficiency of routing.
Dynamic MANET On Demand:
Reduce system requirements of participating nodes, and simplify protocol implementation.
Provides features such as covering possible MANET–Internet gateway scenarios and implementing path accumulation.
Along with route information about a requested target, a node will receive information about all intermediate nodes of a newly discovered path.
Similar to AODV but with slight modification.
AODV, node A knows only the routes to nodes B and D after its route request is satisfied.
DYMO, the node additionally learned a route to node C.