This paper presents a technical solution that addresses mission-critical communications by extending the radio frequency coverage area using a flexible and scalable architecture. One of the main objectives is to improve both the reaction time and the coordination between mission-critical practitioners, also called public protection and disaster relief users, that operate in emergency scenarios. Mission-critical services such as voice and data should benefit from reliable communication systems that offer high availability, prioritization and flexible architecture. In this paper, we considered Terrestrial Trunked Radio (TETRA), the mobile radio standard used for mission-critical communications, as it has been designed in this respect and is widely used by first responder organizations. Even if RF coverage is designed before network deployment and continuously updated during the lifetime of the technology, some white areas may exist and should be covered by supplementary base stations or repeaters. The model presented in this paper is an optical repeater for TETRA standard that can offer up to 52.6 dB downlink, 65.6 dB uplink gain and up to 3.71 km coverage distance in a radiating cable installation scenario. The design in not limited, as it can be extended to several different mobile radio standards using the same principle. Flexibility and scalability attributes are taken into consideration, as they can build a cost-effective deployment considering both capital and operational expenditures.
Keywords: TETRA; communications; fiber optics; mission critical; public safety; radio frequency; sensors.