  Vehicular networks will play an important role in enhancing road safety,
improving transportation efficiency, and providing seamless Internet service
for users on the road. Reaping the benefit of vehicular networks is contingent
upon meeting stringent wireless communication performance requirements,
particularly in terms of delay and reliability. In this paper, a dependence
control mechanism is proposed to improve the overall reliability of vehicular
networks. In particular, the dependence between the communication delays of
different vehicle-to-vehicle (V2V) links is first modeled. Then, the concept of
a concordance order, stemming from stochastic ordering theory, is introduced to
show that a higher dependence can lead to a better reliability. Using this
insight, a power allocation problem is formulated to maximize the concordance,
thereby optimizing the overall communication reliability of the V2V system. To
obtain an efficient solution to the power allocation problem, a dual update
method is introduced. Simulation results verify the effectiveness of performing
dependence control for reliability optimization in a vehicular network, and
show that the proposed mechanism can achieve up to 25% reliability gain
compared to a baseline system that uses a random power allocation.
