New technologies for sensing and communication act as enablers for cooperative driving applications. Sensors are able to detect objects in the surrounding environment and information such as their current location is exchanged among vehicles. In order to cope with the vehicles' mobility, such information is required to be as fresh as possible for proper operation of cooperative driving applications. The age of information (AoI) has been proposed as a metric for evaluating freshness of information; recently also within the context of intelligent transportation systems (ITS). We investigate mechanisms to reduce the AoI of data transported in form of beacon messages while controlling their emission rate. We aim to balance packet collision probability and beacon frequency using the average peak age of information (PAoI) as a metric. This metric, however, only accounts for the generation time of the data but not for application-specific aspects, such as the location of the transmitting vehicle. We thus propose a new way of interpreting the AoI by considering information context, thereby incorporating vehicles' locations. As an example, we characterize such importance using the orientation and the distance of the involved vehicles. In particular, we introduce a weighting coefficient used in combination with the PAoI to evaluate the information freshness, thus emphasizing on information from more important neighbors. We further design the beaconing approach in a way to meet a given AoI requirement, thus, saving resources on the wireless channel while keeping the AoI minimal. We illustrate the effectiveness of our approach in Manhattan-like urban scenarios, reaching pre-specified targets for the AoI of beacon messages.

翻译：新型传感与通信技术为协同驾驶应用提供了实现基础。传感器能够探测周围环境中的物体，并交换车辆当前位置等信息。为应对车辆移动性，协同驾驶应用需要尽可能新鲜的信息来保证正常运行。信息年龄（AoI）已被提出作为衡量信息新鲜度的指标，近年来也被应用于智能交通系统（ITS）领域。我们研究了在控制信标消息发射速率的同时，降低其传输数据AoI的机制。目标是使用平均峰值信息年龄（PAoI）作为度量标准，在数据包碰撞概率与信标频率之间取得平衡。然而，该指标仅考虑数据生成时间，未涉及应用特定因素（如发送车辆的位置）。因此，我们提出了一种结合信息上下文（即车辆位置）来重新解释AoI的新方法。例如，我们通过相关车辆的方位和距离来表征这种重要性。特别地，我们引入了一个与PAoI协同使用的加权系数来评估信息新鲜度，从而更关注来自更重要邻居节点的信息。我们进一步设计了信标发送方法，以满足给定的AoI要求，从而在保持AoI最小化的同时节省无线信道资源。我们在曼哈顿式城市场景中展示了该方法的效果，成功达到了信标消息AoI的预设目标。