This paper describes the need for and features of a low-cost multi-band/multi-mode radio for public safety.
Existing radio communications systems employed in public safety applications today are a disparate mix of equipment operating at frequencies ranging from 25 MHz to 4.99 GHz and using modes ranging from basic analog FM to VoIP. This has created a frustrating and potentially dangerous problem in that first responders from different organizations are often unable to communicate effectively. Existing solutions to this problem are predominately network-based, which requires prior planning and coordination. So, it is desirable to implement some degree of user-based interoperability; that is, to have some radios which are capable of operating in any system without the aid of network-based infrastructure. Such radios would need to be able to operate in any frequency band using any mode that might be encountered. In this paper, the authors describe the requirements for such a radio and consider technical feasibility issues. Specifically, the authors consider a software defined radio (SDR) approach in which the radio uses a small number of RF front ends, each having relatively wide bandwidth and with tuning range sufficient to access most spectrum relevant to public safety communications. Also, two different types of baseband processing strategies will be compared to assess the advantages and disadvantages of Software Communication Architecture (SCA)-based SDR for public safety applications. (Publisher abstract provided)