第三代合作伙伴（the 3rd generation partnership project, 3GPP）为长期演进车对外界信息交互技术（long term evolution-vehicle to everything, LTE-V2X）定义了集中式（模式3）和分布式（模式4）两种通信模式。模式4支持直连通信，采用基于感知的半持续调度（semi-persistent scheduling, SPS）资源分配方案，车辆通过感知选择最佳的子信道。为了解决模式4中SPS算法存在的资源选择不确定性以及资源利用率低等问题，提出了资源预选方案，提前确定预选资源位置，并在感知过程中根据信道拥塞程度调整感知窗口大小和参考信号接收功率强度的加权方式，从而降低资源碰撞概率，提高传输的可靠性。仿真结果表明，与标准中SPS机制相比，所提出的资源分配方案在较高车流密度场景下可以有效提升数据包接收率，降低了通信时延，满足车联网（Internet of Vehicle, IoV）高可靠低时延的目标。

The 3rd generation partnership project (3GPP) has defined two communication modes of centralized (mode 3) and distributed (mode 4) for long term evolution-vehicle to everything (LTE-V2X). Mode 4 supports direct-connected communication, and adopts the semi-persistent scheduling (SPS) resource allocation scheme based on awareness, and the vehicle selects the best sub-channel through awareness. In order to solve the uncertainty of resource selection and low resource utilization of SPS algorithm in mode 4, a resource pre-selection scheme was proposed to determine the location of pre-selected resources in advance, and adjust the size of the sensing window and the weighting method of the received power intensity of the reference signal according to the degree of channel congestion during the sensing process, so as to reduce the probability of resource collision and improve the reliability of transmission. The simulation results show that compared with the SPS mechanism in the standard, the proposed resource allocation scheme can effectively improve the packet reception ratio, reduce the communication delay and meet the goal of high reliability and low delay of the Internet of Vehicles (IoV) in the high traffic density scenario.