ADeM: Active Delay Management for critical group communication over heterogeneous public cellular networks

As the basis of Next Generation Public Safety Communication (PSC) systems for critical group communication, 4G (LTE) technologies have been chosen from the different stakeholder. Existing 2G and 3G equivalent technologies are and will be used to allow for a sufficient network coverage. Due to the long investment cycles within the public sector, for a long time small band 2G Professional Mobile Radio (PMR) networks will be the backbone of mission critical voice communication. To enable enhanced data exchange 4G networks will provide this capability as an add-on. It is a well known fact that every transmission technology has its own footprint of delay and delay-spread (jitter). This lead to challenges within heterogeneous system environments, because different behavior introduces unfairness into the system, negligent users in legacy networks. The proposed solution in this paper is based on the identification of the unique footprint of the used networks to increase the fairness. In this paper, the authors present an Active Delay Management (ADeM) PSC System that allows for critical group communication in next generation public safety communication network based on ×G technologies. Therefore, the performance limitations of an IP overlay for heterogeneous communication networks have been studied and analyzed for different mobile radio technologies, based on mobile field trials performed in commercial 2G, 3G and 4G networks. Build upon this study, the gathered information is used to classify the transmission networks to enable the proposed ADeM system to actively consider network dependent delays in its Active Queue Management (AQM) decisions. Thereby, enhanced fairness for the different information streams as well as an improved performance in critical communication scenarios can be achieved.