Comparison of LTE centralized RRM and IEEE 802.11 decentralized RRM for ITS cooperative awareness

Cooperative Intelligent Transport Systems (C-ITS) are based on the exchange of messages between vehicles and with the road infrastructure in order to improve road safety, traffic efficiency, and travel comfort. Although the lower layers of the European C-ITS protocol stack support different wireless communication technologies, ITS-G5 is currently the preferred option for direct communication between traffic participants (i.e. without relaying the information through network infrastructure, such as a base station). In particular, the ITS-G5 specification is based on the IEEE 802.11-2012 standard, and therefore, implements decentralized radio resource management. As a result, the performance of ITS-G5 might be limited by congestion and hidden node problems. These issues can be overcome with an approach that centrally manages the radio resources, as in current LTE networks and proposed for the future 5G mobile communication standard. Both management approaches — centralized and decentralized — are compared in this paper with the focus on their ability to support cooperative awareness. Results show that the centralized approach is able to increase the number of vehicles experiencing high quality of service compared to the decentralized approach.