An emergence alert broadcast based on cluster diversity for autonomous vehicles in indoor environments

This paper addresses an emergency alert broadcast for autonomous vehicles in indoor environments. For a rapid alert broadcast, a novel cluster diversity is proposed. Using the cluster diversity, the alert broadcast can significantly reduce the number of rebroadcasts. This leads to the rapid delivery of emergency alerts. The cluster diversity consists of clustering and diversity combining. For the clustering, the cluster diversity technique utilizes the location information of autonomous vehicles. Using the location information, a cluster head is selected in each cluster. The cluster head rebroadcasts the emergency alert to the autonomous vehicles. Therefore, the clustering can lessen the number of rebroadcasts. In order to further reduce the number of rebroadcasts, a diversity combining technique is proposed in this paper. The diversity approach is based on the clustering. For the diversity, the emergency alert packet is repeated in the transmitted OFDM block. For each cluster, the emergency alert packet can orthogonally be allocated to the corresponding frequency sub-band in the OFDM block. In the received OFDM block, the autonomous vehicle utilizes the emergency alert packet with the maximum power in order to achieve a diversity. The experimental results exhibit that the proposed cluster diversity can considerably reduce the number of rebroadcasts in indoor environments. The results also show that the presented approach substantially outperforms the conventional technique in terms of the number of outage vehicles in the cases of rebroadcasts under indoor environments.