Providing low-latency high-quality data services to mobile terminals has become a mandatory requirement for all mobile broadband standards. Therefore, effective countermeasures against mobile channel impairments, like small- and large-scale fading, are of the utmost importance whenever traditional physical layer channel codes do not provide sufficient resilience or request too much hardware resources. Among the possible countermeasures, the paper investigates the application of packet layer coding, which basically consists in applying forward error control techniques at upper layer (UL-FEC). In the paper the UL-FEC decoder performance analytical model already developed by authors is generalized and extended to include nonperiodic shadowing and small-scale fading. Analytical results are then validated through numerical simulation considering a real application scenario.