State-of-the-art wireless communication networks that enable safety and emergency services are predominantly based on Terrestrial Trunked Radio (TETRA). TETRA guarantees four nines of average end-to-end connection availability, but offers low data rate. Originally low-data rate safety and emergency services evolve from basic as voice and messaging towards video and other applications that require high data rate. Emergency and safety-critical voice and messaging, however, fall under a category of ultra-reliable communications and require an average connection availability of five nines, i.e., an average outage time of 5.25 minutes per year. The challenge that we address in this paper is guaranteeing the average connection availability for the ultra-reliable communications as voice, while providing sufficient data rate for the complimentary services as video. We achieve this by using heterogeneous wireless access network, i.e., WLAN, LTE and TETRA, enhanced with automated switching between the wireless technologies through Dynamic Link Exchange Protocol (DLEP). Based on the testbed measurements and reliability analysis, we show that a heterogeneous access network can achieve the five nines availability, while increasing the available data rate in comparison with single technology access networks.     «

State-of-the-art wireless communication networks that enable safety and emergency services are predominantly based on Terrestrial Trunked Radio (TETRA). TETRA guarantees four nines of average end-to-end connection availability, but offers low data rate. Originally low-data rate safety and emergency services evolve from basic as voice and messaging towards video and other applications that require high data rate. Emergency and safety-critical voice and messaging, however, fall under a category o...     »