Technologies for emergency rollout of broadband public protection and disaster relief (BB-PPDR) communications in humanitarian crisis zones

The ongoing migration flows of refugees and immigrants who escape from war and conflict zones to seek asylum and stable living conditions in European countries, have created a multitude of humanitarian crisis sites. The latter are typically encountered in uninhabited islands, remote coastal areas and other isolated locations, where public protection and disaster relief (PPDR) communications need to be deployed over professional mobile radio (PMR) networks, in order to provide broadband communication services to rescuers, first aiders and other on-site agents. The PMR coverage in such humanitarian crisis sites could not always be guaranteed, whereas radio interferences and jammers from neighbouring countries could further impair the operability of the critical PPDR communications. In such cases, an emergency roll out of broadband PMR services might be required. In order to tackle the interference and poor coverage conditions, this PMR deployment must be reconfigurable by nature and able to co-exist with another primary radio transmission. In the potential scenario we are envisioning, the primary transmission is a 4G LTE one. The key prerequisite of this radio co-existence is the efficient and interference-free use of the licensed spectrum from the secondary broadband PMR transmission. In this chapter we show that using a filter bank multi-carrier (FBMC) waveform for the PMR transmission satisfies these requirements due to its spectral containment and spectral shape. Moreover, given the potentially constrained energy supply and the complex spectral coexistence scenario, the broadband PMR base station transmitter needs to employ power amplifier (PA) digital linearization techniques such as crest factor reduction (CFR) and digital predistortion (DPD), to maximize the energy efficiency when operating with high peak-to-average power (PAPR) multi-carrier modulations and minimize the spectral emission in primary transmission bands due to the PA non-linear distortion. In fact, the inherent spectral benefits of the FBMC modulation cannot be maintained unless linearization techniques are implemented. The LTE-FBMC waveform coexistence is evaluated under different operating conditions using an experimental setup and taking into account the PA linearization techniques. This work was supported in part by the Spanish Government (Ministerio de Ciencia, Innovación y Universidades) and the Fondo Europeo de Desarrollo Regional (FEDER) under grants RTI2018-099841-B-I00, TEC2017-88373 and TEC2017-83343-C4-2-R, and in part by the Generalitat de Catalunya under grants 2017 SGR 891, 2017 SGR 1479 and 2017 SGR 813