The arrival processes of the two kinds of voice packets are all Poisson processes.After arriving at the mixing module, each packet queues in its finite capacity buffer.

• 假定两类音频包的到达为相互独立的泊松过程，到达混合模块后分别在各自的有限容量缓冲区中排队，混合器的服务规则依据队列排队状态而定，服务时间服从负指数分布。