Abstract

For CDMA to be a variable multiaccess approach to integrate multimedium services over a wide range of constant and variable bit rate server, it is important to come out with suitable admission and congestion control techniques. This is because in CDMA systems the user's transmission overlap and large bit error probabilities would result that users violate their average bit rate agreements with satellite. Our work tries to minimize the number of ATM/CDMA call overlap by proper traffic shaping function. In this work, we show by computer simulation ways of alleviating congestion in ATM/CDMA broadband integrated satellite systems. A hybrid CDMA/TDMA/ATM approach is taken where a mixture of user classes namely video, voice, file and interactive data share a TDMA frame compared of four subframes where an ATM/CDMA technique is used by users of each class to access the time slots within their subframe. An M-array orthogonal sequence CDMA modulation is adopted and multipath fading satellite environment is assumed. Users are assumed to have the ATM/CDMA/TDMA interface and to commemorate their signals directly to the satellite in a hubless fashion. Traffic shaping is something that happens in the customer premise equipment. If the policing function is the policeman, and the charging function is the judge, then the traffic shaping function is the lawyer. The traffic shaping function uses information about the policing and charging functions in order to change the traffic characteristics of the customer's stream to get the lowest charge or the smallest cell-loss, etc. In this work, we simulated the policing function and traffic shaping function which the leaky bucket scheme is investigated.