Abstract: Beacon transmission power control algorithm based on the preset threshold was put forward in vehicle ad-hoc networks (VANETs). First， according to the preset channel load threshold， a reasonable channel load interval is adjusted to ensure that all the nodes transmit beacon messages. Based on the beacon transmission power of all the vehicles in the carrier sensing range of the target node， the channel load is controlled within a certain range to avoid channel congestion. Then， by simulating the basic sections of eight-lane highways and actual road driving tests， the beacon transmission power control algorithm based on the preset threshold is verified with the correlation analysis. The experimental results show that this power control algorithm can effectively control channel load， avoid channel congestion， and enhance the stability and robustness of wireless beacon message transmission in VANETs.

Key words: intelligent transportation, power control algorithm, channel load, preset threshold, vehicle ad-hoc network (VANET)