Sau đó, các gói tin có thể nhận được dịch vụ ưu tiên dựa trên trọng lượng với người sử dụng cấu hình được giao cho hàng đợi khác nhau. Trong trường hợp của các mạng gói dữ liệu không dây, tuy nhiên, WFQ không cung cấp sự cô lập của các dòng khác nhau. | Admission Control with QoS Support in Wireless IP Networks 251 One can calculate the total incoming call intensity in the cell denoted as a by using the following relation A a 1 - PB . a hi 1 - PFh t where Ai is the intensity of the calls accepted in a cell. Handover intensity from a cell to its adjacent cells is given by a h Pi a . P. a 1 - Pb i a h 1 - Pn where Pi is the probability that a given call will perform a handover before it will terminate. From one cannot directly determine new call blocking probability and handover blocking probability. For that purpose we should use iterative calculations where initial values for PBi and PFhi are set to zero. Then one does iterations until both probabilities converge. So far we have analyzed QoS parameters of A1 and A2 subclasses but have not referred to A3 traffic at all. But although A3 flows have lower priority compared to A1 and A2 traffic A3 average packet delay cannot be analyzed separately. Simply this is a consequence of the fact that A3 flows use the remaining resources after servicing A1 and A2 flows. For the simplicity of the analysis one may assume that A3 packets arrive at wireless link buffers by a Poisson process although this is not exactly the case the reader should refer to the IP traffic characteristics in Chapter 5 . One can use buffering of A3 packets in base stations according to the FCFS scheme so packets that enter into the wireless link buffer first are transmitted first. The total A3 packet delay is a sum of waiting time in the buffer and transmitting time over the wireless link. According to the discussion above one can model A3 traffic in the base station as a queue with a varying service rate. The service rate can be anything between zero and cell capacity C. The admission control algorithm is used to allocate a specific number of logical channels bandwidth for each call. Below we discuss admission control for each subclass in A class. A call of the A1 subclass created .
