Simulation on performance of forward link in simulcast PDT

Professional Digital Trunked Communication System (PDT) is typically designed to meet professional Chinese users´ requirements. PDT provides a digital trunked system solution with low cost, wide area coverage and probability of smooth upgrading from analog trunked system. In application, digital trunked system is often restricted in shortage of frequency resource, hand-over performance sometimes not capable to meet trunking requirement, and poor coverage in metropolitans and indoor environment. Simulcast can be used to deal with these restrictions, based on the narrowband 4FSK modulation scheme adopted by PDT. In a simulcast cell with multiple sites, the forward link of each site can be assumed to be independent, so signals reaching mobile stations from different sites have different path delay, power loss and channel model which it passed. Thus, the performance of receivers in mobile stations is degraded, which will influence the coverage of the simulcast system. In this paper, features of 4FSK adopted by PDT are discussed; meanwhile forward link channels of non-simulcast cells with a single site and that of simulcast cells with multiple simulcasting sites are studied respectively. Simulation on forward link performance is conducted based on these analyses, which can be referred to when designing the coverage of simulcast PDT systems.