Benefits of DCC Facilities in ITS-G5 Networks - First Simulated Results

Abstract

In the recent years we are experiencing a roll-out of Connected Vehicles (CVs) in Europe. At the same time, a high number of new facilities are being developed for them. Sending such a high amount of information makes a wise allocation of channel resources indispensable. It is also important for the scarce resources to be divided between the stations. Decentralized Congestion Control (DCC) was developed to address these issues. However, due to the agnostic nature of the communication protocol stack, higher layers are not aware of the delay and packet-drop that DCC causes. For this reason the facilities layer part of DCC (DCC_Fac) has been designed. We have implemented the newly developed mechanism by the European Telecommunications Standards Institute (ETSI) on a simulation framework and tested it under demanding conditions with different communication channel loads and traffic densities in a highway scenario. This paper evaluates if DCC_Fac can mitigate some of the shortcomings of the existing DCC mechanism. To the best of our knowledge this is the first paper assessing the newly developed congestion controller. From our work, we find out that the new mechanism effectively prevents packets from being dropped in the queues of access layer DCC (DCC_Acc). Furthermore, DCC_Fac is able to maintain a significantly lower end-to-end delay in high interference scenarios. In the end we show that it also delivers better inter-packet gaps for high-priority messages than the existing mechanism. In conclusion to our work, we confirm the added value of DCC_Fac.