Modelling and analysing for multimedia applications in a mobile network, with real-time behaviour taken into consideration, is still a subject of much research. Generalized Stochastic Petri Net (GSPN) is well known formalisms used to represent and analyse communication and computer systems. However, it does not have enough expressive power to model timing behaviours of multimedia applications in a mobile network. To address this limitation, we develop quality of services based GSPN, which is capable of doing so. The extension offers the promise of providing real-time system predictability for systems characterised by substantial stochastic behaviour. With this model we model and analyse the handover and admission control schemes in the different multimedia traffic environments. Our result, thereby, provide the optimal performance achievable for these schemes under the real-time constraints in the given setting of design parameters.