05-10-2012, 11:39 AM
Inter-Vehicle Communication Systems: A Survey
[attachment=35364]
Taxonomy and Assumptions
The paper starts with the taxonomy of 3 types of vehicle communication systems:
• Inter-vehicle communication (IVC) systems.
These systems are completely infrastructure free. Based on whether information is retransmitted at intermediate nodes, we can distinguish between:
o Single-hop IVC (SIVC). A vehicle can only send messages to vehicles in its transmission range.
o Multi-hop IVC (MIVC). A vehicle can send messages beyond his transmission range. According to the paper this requires a network layer.
• Roadside-to-vehicle communication (RVC) systems.
Communication takes place between roadside infrastructure and a car’s onboard unit (OBU). Two types of systems can be distinguished:
o Sparse RVC (SRVC) systems. These systems provide services at hot spots like for instance a busy intersection or a car park.
o Ubiquitous RVC (URVC) systems. These systems provide all roads with high-speed communications. This requires a major investment.
• Hybrid vehicular communication (HVC) systems. The combination of above systems. Vehicles may communicate with infrastructure, even when they are not in range. The kind of supported applications are the same as for RVC systems. This solution requires less infrastructure however network connectivity is not guaranteed.
Public Safety Applications
These applications have the potential to reduce the number of vehicle collisions. In some cases, the collision is imminent but the system may prepare the vehicles for collision.
These applications are obviously time constrained and either a MIVC or a URVC (SRVC for intersections) system can be used.
The system penetration has a direct influence on the usability of the system i.e. with p percent of penetration, an equipped vehicle will benefit in p percent of the situations.
In terms of addressing, the destinations in these applications will not be individual vehicles, but rather any relevant vehicle.
Traffic Management Applications
These applications focus on traffic flow improvements. Three examples are mentioned:
• Traffic monitoring.
Each vehicle acts as a sensor (determining its speed), a relay (information is to travel for more than the direct transmission range) and as destination (using information from other vehicles). The information may be used to inform the driver, reroute a vehicle, and control the traffic by using adaptive speed limits, etc.
• Traffic light scheduling.
A SRVC system may provide additional information like queuing time as well as expected number of vehicles to arrive. This may improve efficiency of schedules.
• Emergency vehicles.
May notify the relevant vehicles as well as equipped stop lights of their presence and intended routes.
Like in safety applications, the destinations of the messages are relevant vehicles.
Traffic Coordination and Assistance Applications
This type of application has been the main research topic of many IVC projects. Two examples are mentioned:
• Platooning.
Forming tight columns of closely following vehicles. This application has the potential of radically increasing highway capacity.
• Passing and lane change.
Reduce the risk during these maneuvers. This application requires close-range IVC with tight real-time constrains. It can be implemented using SIVC or URVC.
Comfort applications
The main focus of these applications is to make travel more pleasant. Examples are the communication between two vehicles (e.g. voice, instance messaging, etc.), internet or applications to collect road tolls or parking fees.
These applications may be implemented using IVC or URVC systems. All applications require individual addressing rather than geographic.
Short-range communication technologies
The technologies mentioned in the paper focus on the physical layer:
• Radar range measurements @ 60 GHz. Given the frequency band, this technology works best with a line of sight. Mirrors may therefore be used to “see” around the corner. This technology can be used for ranging as well as for communication aspects.
• Ultra-wideband communication systems. These systems have a very good ranging capacity. In addition, these systems have the potential for high bandwidths at short ranges. However, the power limitation (imposed by the FCC) limits the transmission range to a few meters (and thus reducing the applicability of these systems).
• Optical communication systems are suited for direct line of sight and relative short communication (i.e. suitable for SIVC). Just like radar range measurements, this technology can be used for range measurements.
[attachment=35364]
Taxonomy and Assumptions
The paper starts with the taxonomy of 3 types of vehicle communication systems:
• Inter-vehicle communication (IVC) systems.
These systems are completely infrastructure free. Based on whether information is retransmitted at intermediate nodes, we can distinguish between:
o Single-hop IVC (SIVC). A vehicle can only send messages to vehicles in its transmission range.
o Multi-hop IVC (MIVC). A vehicle can send messages beyond his transmission range. According to the paper this requires a network layer.
• Roadside-to-vehicle communication (RVC) systems.
Communication takes place between roadside infrastructure and a car’s onboard unit (OBU). Two types of systems can be distinguished:
o Sparse RVC (SRVC) systems. These systems provide services at hot spots like for instance a busy intersection or a car park.
o Ubiquitous RVC (URVC) systems. These systems provide all roads with high-speed communications. This requires a major investment.
• Hybrid vehicular communication (HVC) systems. The combination of above systems. Vehicles may communicate with infrastructure, even when they are not in range. The kind of supported applications are the same as for RVC systems. This solution requires less infrastructure however network connectivity is not guaranteed.
Public Safety Applications
These applications have the potential to reduce the number of vehicle collisions. In some cases, the collision is imminent but the system may prepare the vehicles for collision.
These applications are obviously time constrained and either a MIVC or a URVC (SRVC for intersections) system can be used.
The system penetration has a direct influence on the usability of the system i.e. with p percent of penetration, an equipped vehicle will benefit in p percent of the situations.
In terms of addressing, the destinations in these applications will not be individual vehicles, but rather any relevant vehicle.
Traffic Management Applications
These applications focus on traffic flow improvements. Three examples are mentioned:
• Traffic monitoring.
Each vehicle acts as a sensor (determining its speed), a relay (information is to travel for more than the direct transmission range) and as destination (using information from other vehicles). The information may be used to inform the driver, reroute a vehicle, and control the traffic by using adaptive speed limits, etc.
• Traffic light scheduling.
A SRVC system may provide additional information like queuing time as well as expected number of vehicles to arrive. This may improve efficiency of schedules.
• Emergency vehicles.
May notify the relevant vehicles as well as equipped stop lights of their presence and intended routes.
Like in safety applications, the destinations of the messages are relevant vehicles.
Traffic Coordination and Assistance Applications
This type of application has been the main research topic of many IVC projects. Two examples are mentioned:
• Platooning.
Forming tight columns of closely following vehicles. This application has the potential of radically increasing highway capacity.
• Passing and lane change.
Reduce the risk during these maneuvers. This application requires close-range IVC with tight real-time constrains. It can be implemented using SIVC or URVC.
Comfort applications
The main focus of these applications is to make travel more pleasant. Examples are the communication between two vehicles (e.g. voice, instance messaging, etc.), internet or applications to collect road tolls or parking fees.
These applications may be implemented using IVC or URVC systems. All applications require individual addressing rather than geographic.
Short-range communication technologies
The technologies mentioned in the paper focus on the physical layer:
• Radar range measurements @ 60 GHz. Given the frequency band, this technology works best with a line of sight. Mirrors may therefore be used to “see” around the corner. This technology can be used for ranging as well as for communication aspects.
• Ultra-wideband communication systems. These systems have a very good ranging capacity. In addition, these systems have the potential for high bandwidths at short ranges. However, the power limitation (imposed by the FCC) limits the transmission range to a few meters (and thus reducing the applicability of these systems).
• Optical communication systems are suited for direct line of sight and relative short communication (i.e. suitable for SIVC). Just like radar range measurements, this technology can be used for range measurements.