Evaluation and improvement of QoS metrics for safety-critical broadcast services in VANETs

Quality of service (QoS) is an important issue for safety-critical broadcast services in vehicular ad hoc networks (VANETs). Unlike traditional wireless network applications, vehicular safety-related communication requires faster and more reliable message delivery, and it usually demands broadcast communication. However, there is few QoS metrics specifically for vehicular safety communications, and the current channel access scheme defined in IEEE 1609.4 cannot meet these requirements well. In this paper, we first introduce three QoS metrics specifically for one-hop safety broadcast communication in VANETs, including the packet success rate (PSR), the packet transmission rate (PTR) and the packet loss percentage (PLP). Then, we proposed an adaptive independent channel switching scheme to improve QoS of vehicular safety communications. Simulation results show that our proposed scheme outperforms the current IEEE 802.11p/1609.x protocol stacks in terms of PSR, PTR and PLP.