05-09-2016, 11:50 AM
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Abstract
This paper proposes a vehicle-to-vehicle communication
protocol for cooperative collision warning. Emerging wireless
technologies for vehicle-to-vehicle (V2V) and vehicleto-roadside
(V2R) communications such as DSRC [1] are
promising to dramatically reduce the number of fatal roadway
accidents by providing early warnings. One major
technical challenge addressed in this paper is to achieve
low-latency in delivering emergency warnings in various
road situations. Based on a careful analysis of application
requirements, we design an effective protocol, comprising
congestion control policies, service differentiation mechanisms
and methods for emergency warning dissemination.
Simulation results demonstrate that the proposed protocol
achieves low latency in delivering emergency warnings and
efficient bandwidth usage in stressful road scenarios.
Introduction
Traffic accidents have been taking thousands of lives
each year, outnumbering any deadly diseases or natural disasters.
Studies [18] show that about 60% roadway collisions
could be avoided if the operator of the vehicle was
provided warning at least one-half second prior to a collision.
Human drivers suffer from perception limitations on
roadway emergency events, resulting in large delay in propagating
emergency warnings, as the following simplified example
illustrates. In Figure 1, three vehicles, namely A B
Related Work
Previous research work with regard to V2V communication
has focused on three aspects: medium access control,
message forwarding, and group management.
In [9], Lee et. al. propose a wireless token ring MAC protocol
(WTRP) for platoon vehicle communication, in which
all participating vehicles form a group and drive cooperatively.
A slot-reservation MAC protocol, R-ALOHA, for
inter-vehicle communication is discussed in [17]. Several
slot reservation MAC protocols [11, 10, 13] are proposed
for the Fleetnet Project [7]. Xu et. al. discuss a vehicleto-vehicle
Location-Based Broadcast communication protocol,
in which each vehicle generates emergency messages
at a constant rate [19]. The optimum transmission probability
at MAC layer for each message is then identified to reduce
the packet collision probability.
Message forwarding can help warning message reach vehicles
beyond the radio transmission range. In [14], the authors
propose a multi-hop broadcast protocol based on slotreservation
MAC. Considering the scenario that not all vehicles
will be equipped with wireless transceivers, emergency
message forwarding in sparsely connected ad hoc network
consisting of highly mobile vehicles is studied in [3]. Motion
properties of vehicles are exploited in [4] to help with
message relay. Two protocols to reduced the amount of forwarding
messages were proposed in [16].
When an emergency event occurs, there are usually a
group of vehicles affected by the abnormal situation. In
terms of group management, [12] defines so called “proximity
group” based on the location and functional aspects of
mobile hosts; [5] defines a “peer space”, in which all traf-
fic participants share a common interest; [2] also discusses
group membership management for inter-vehicle communication.