  In vehicular communications, traffic-related information should be spread
over the network as quickly as possible to maintain a safe and reliable
transportation system. This motivates us to develop more efficient information
propagation schemes. In this paper, we propose a novel cluster-based
cooperative information forwarding scheme, in which the vehicles
opportunistically form virtual antenna arrays to boost one-hop transmission
range and therefore accelerate information propagation along the highway. Both
closed-form results of the transmission range gain and the improved Information
Propagation Speed (IPS) are derived and verified by simulations. It is observed
that the proposed scheme demonstrates the most significant IPS gain in moderate
traffic scenarios, whereas too dense or too sparse vehicle density results in
less gain. Moreover, it is also shown that increased mobility offers more
contact opportunities and thus facilitates information propagation.
