Wireless channel congestion control and decentralized resource allocation for 802.11p based V2X communication have been widely investigated for a single Cooperative Awareness service, considering mostly homogenous communication requirement per vehicle. Future connected vehicles will be based on multiple V2X services, with heterogenous number of services and communication needs, which existing resource allocation mechanisms does not address.
In this thesis, we analyze several decentralized congestion control and channel resource allocation protocols standardized in Europe for initial V2X deployment. We present issues with the existing approach, in particular the inefficient channel capacity utilization, classification of V2X services using static priority for Quality of Service, resource allocation at the Access Layer, problematic cross layer coordination, inability to balance resources among multiple V2X safety services and distributed resource allocation for asymmetric number of services per vehicle.
We propose improvements to the shortcomings, considering key requirements for future connected vehicles supporting heterogeneous V2X services. We suggest modifications to Access Layer congestion control and propose shifting the in-vehicle resource allocation intelligence from the Access to the Service Layer. In this regard we design a resource orchestrator at the Service Layer, which dynamically characterizes services using multiple QoS parameters and allocates channel resources among V2X services in close coordination with the Access Layer. Similarly, we present a distributed mechanism to orchestrate channel resource among a mixed distribution of vehicles with diverse channel usage requirements under channel congestion.
Our proposed algorithms and design improvements increase the channel capacity usage, improve V2X safety information freshness, reduce starvation of lower priority services and decentrally allocate additional channel resources to nodes having more and higher priority V2X services. Analytical and simulation-based results show the V2X application performance improvement rendered by our approach, compared to existing standardized protocols.