In the delay time of the Forward Collision Warning (FCW) system under Vehicle-to-Vehicle (V2V) communication, the traditional model assumes uniform speed of the host vehicle and error-free Global Positioning System (GPS), so as to significantly underestimate the risk of collision. Aiming at this problem, a new FCW strategy was proposed with correcting GPS errors and considering the movement state of the host vehicle within the delay time. Firstly, the overall workflow of the FCW system based on V2V communication was analyzed, and the key delays in the system were modeled by using the Gaussian model. Then, a collision avoidance model was established with correcting GPS errors and taking the movement state of the host vehicle within the delay time into consideration. And different warning strategies were formulated corresponding to three scenarios of the constant speed, acceleration and deceleration of the remote vehicle. Finally, in view of the situation where the host vehicle accelerated in the delay time, Matlab was used to simulate the proposed FCW strategy. Simulation results show that the average successful collision avoidance rate of the proposed warning strategy can reach 96%, verifying the effectiveness of it in different scenarios.

Improving sync accuracy in Wireless Sensor Network (WSN) usually causes additional sync overhead. To optimize the compatibility of higher sync accuracy and lower sync overhead, a time sync algorithm based on the component decoupling fusion was proposed. With the two-way broadcast sync mechanism and the clock correlations, the clock deviations between synchronized nodes and reference nodes were estimated by the component decoupling fusion. Besides, the computation for the weights of different components was discussed according to the linear unbiased minimum variance estimation. The simulation results show that, without the additional energy consumption, the proposed algorithm can improve its sync accuracy after 20 sync rounds by 4.52μs, 13.8μs and 25.48μs, compared to PBS (Pairwise Broadcast Synchronization), TPSN (Timing-sync Protocol for Sensor Network) and RBS (Reference Broadcast Sync) respectively.