In ISDN and ATM, performance evaluation of packetized voice is an important problem. To analyse the superposed voice packets from a number of voice sources, the Markov modulated Poisson process (MMPP) has been used for approximating the superposed non-renewal process. In this approximation, a large computer time was needed for determining the MMPP parameters by the numerical inversion of Laplace transform. In this paper, introducing the index of skewness for counts as well as the index of dispersion, and using their conservation low, limiting property and differential coefficient at the origin, we propose a simplified method for determining the parameters.

A half-cylindrical BK-7 prism/dielectric film with a grating/Ag film/fluorescent polymer film structure was prepared, and its surface plasmon (SP) excitation property was investigated. It was confirmed experimentally that SP excitations are possible in this structure by using prism and grating couplings. The SP excitation property depended on the direction of the grating vector. Furthermore, intense photoluminescence was observed when the SPs were simultaneously excited at the Ag/polymer interface by prism coupling and at the Cytop/Ag interface by grating coupling.