Wireless communications technologies play an essential role to support the Public Protection and Disaster Relief (PPDR) operational needs. The current Private/Professional Mobile Radio (PMR) technologies used for PPDR communications offer a rich set of voice-centric services but have very limited data transmission capabilities, which are unable to handle the increasing PPDR community demand for a wider range of data-centric services. Though some efforts have been devoted to upgrade PMR technologies with better data transfer capabilities, the progression towards an enhanced mobile broadband PMR standardized solution still lags behind the achievements made in the commercial wireless industry, which recently culminated in Long- Term Evolution (LTE) technology. Because of this contrasting progress, the adoption of commercial mainstream LTE technology to satisfy the PPDR community's data communication needs is gaining momentum and offers significant opportunities to create and exploit the synergies between the commercial and PPDR domains, which have remained almost entirely separate to date. In this context, this paper first discusses the suitability of LTE and related technologies for mobile broadband PPDR service provisioning. Next, it presents the argument that the most plausible future scenarios to deliver the increasingly data-intensive applications demanded by the PPDR agencies are expected to rely on the use of both dedicated and commercial LTE-based mobile networks. From this basis, the paper proposes a system architecture solution for PPDR service provisioning that enables PPDR service access through dedicated and commercial networks in a secure and interoperable manner and ensures proper allocation of the networks' capacity to PPDR applications through the dynamic management of prioritization policies. In addition, the spectrumrelated issues that are central to the proposed PPDR service provisioning solution are addressed, and a solution based on the joint e- ploitation of dedicated and shared spectra is proposed.