@article{Wang2006PTT,
    author = {Y. Wang and M. Zukerman and R. J. Harris},
    title = {{PTT} packet delay analysis for GPRS/GSM links},
    journal  = {IEEE Communications Letters},
    volume = {10},
    number = {6},
    pages = {456-458},
    month = {Jun.},
    year = {2006},
    abstract = {Push-to-talk (PTT) is a new mobile service that enables fast-access and two-way communication between two or more users. This paper develops an approximate evaluation model for PTT delay performance in GPRS/GSM networks based on a quasi-stationary assumption and an M/G/1 processor sharing queueing model. Numerical results are presented in order to illustrate the effect of traffic load and other design parameters on PTT packet delay.}
}