Life-critical warning message, abbreviated as warning message, is a special event-driven message that carries emergency warning information in Vehicle-to-Everything (V2X). Three important characteristics that distinguish warning messages from ordinary vehicular messages are sporadicity, crowding, and ultra-time-criticality. In other words, warning messages come only once in a while in a sporadic manner; however, when they come, they tend to come as a crowd and they need to be delivered in short order. This paper puts forth a medium-access control (MAC) protocol for warning messages. To circumvent potential inefficiency arising from sporadicity, we propose an override network architecture whereby warning messages are delivered on the spectrum of the ordinary vehicular messages. Specifically, a vehicle with a warning message first sends an interrupt signal to pre-empt the transmission of ordinary messages, so that the warning message can use the wireless spectrum originally allocated to ordinary messages. In this way, no exclusive spectrum resources need to be pre-allocated to the sporadic warning messages. To meet the crowding and ultra-time-criticality aspects, we use advanced channel access techniques to ensure highly reliable delivery of warning messages within an ultra-short time in the order of 10 ms. In short, the overall MAC protocol operates by means of interrupt-and-access.

中文翻译：

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V2X 中的零星超时间关键人群消息传递

Life-critical warning message，简称警告消息，是一种特殊的事件驱动消息，在V2X（Vehicle-to-Everything，V2X）中携带紧急警告信息。区分警告信息与普通车辆信息的三个重要特征是零星性、拥挤性和超时间紧迫性。换句话说，警告消息只是偶尔以零星的方式出现；然而，当他们来的时候，他们往往会成群结队地来，需要在短时间内送达。本文提出了一种用于警告消息的媒体访问控制（MAC）协议。为了避免偶发性引起的潜在低效率，我们提出了一种覆盖网络架构，其中警告消息在普通车辆消息的频谱上传递。具体来说，有告警信息的车辆首先发送中断信号，抢占普通信息的传输，使告警信息可以使用原来分配给普通信息的无线频谱。这样，不需要为偶发告警消息预先分配独占的频谱资源。为了满足拥挤和超时间紧迫性方面的需求，我们使用先进的信道接入技术来确保在 10 ms 量级的超短时间内高度可靠地传递警告消息。简而言之，整个 MAC 协议通过中断和访问的方式运行。不需要为偶发告警消息预先分配独占频谱资源。为了满足拥挤和超时间紧迫性方面的需求，我们使用先进的信道接入技术来确保在 10 ms 量级的超短时间内高度可靠地传递警告消息。简而言之，整个 MAC 协议通过中断和访问的方式运行。不需要为偶发告警消息预先分配独占频谱资源。为了满足拥挤和超时间紧迫性方面的需求，我们使用先进的信道接入技术来确保在 10 ms 量级的超短时间内高度可靠地传递警告消息。简而言之，整个 MAC 协议通过中断和访问的方式运行。