Queueing theory has long been an important area of applied probability. Realistic applications require fairly complex systems. In particular arrivals to a single queue may come from a number of different distributions. These can be modeled as a superposition of point processes. This research is designed to identify and solve the important problems in applying this type of model to communication systems. Problems in communications can often be solved by studying appropriate probability models. This research is designed to identify such problems and solve them by using the appropriate probability models.