Study Of Buffer Of WATM

Wireless ATM is a new developing technique and may be applied to many cases. But the change of the transmission media results in many problems such as the channel bandwidth narrowing and the quality of the channel degrading, when ATM evolved to Wireless ATM. Insuring the reliable transmission and the transmission delay as small as possible is the most intractable problem. However, constructing a buffer area utilizing buffer is a general approach that can achieve the tradeoff among the important performance index of the system.Wireless ATM needs the specific buffer capacity satisfying the demand of the channel characteristics besides the buffer capacity fulfilling the switching delay. Hence, the buffer capacity demanded by Wireless ATM is far more than that demanded by ATM. The huge buffer capacity is the important factor limiting the performance of the Wireless ATM, which become the difficulty and hotspot of studying the Wireless ATM buffer techniques.The thesis discusses and analyzes the service type and the flow control scheme supplied by the ATM network, and presents the flow control scheme for the individual note in the network aiming at the Wireless ATM and analyzes the advantages and the existed problems of several flow controls in the VBR service.The thesis investigates the performance of single output Wireless ATM buffer utilizing the generation function method, and established the buffer model based on the generation function, and obtains the statistic behavior of the WATM buffer capacity and the statistic behavior of the transmission delay and the expression of probability generation function of the buffer capacity and the information delay and the mean and variance of the buffer capacity and information delay.Concluded the two important conclusions:First, the mean of the WATM buffer capacity and that of the information delay satisfy D=U/A'(l) , namely, the average buffer area capacity is directly proportional to the meant of the information delay.Second, in the same condition, demand of the packet service time obeying the geometry distribution for the buffer average capacity and the variance of buffer capacity and the mean of the information delay and the variance of the delay are maximal. That is, So far as the buffer capacity and the information delay are concerned, the geometry distribution is most adverse distribution.The thesis study the channel model that input queue is relevant and the burst service source have the arbitrary distribution and WATM buffer has the multiple output, and obtain the closed-form expression of the buffer system capacity, and give the closed-form expression of the buffer capacity mean and the average packet delay and the probability. expression of the buffer overflow when the buffer capacity is limited. Conclude the two important conclusions:First, in the assumption of the multi-output and the arbitrary service source and the relevant input queue, the mean of the WATM buffer capacity reduces linearly as the parameter // of the geometry distribution increases.Second, the average packet delay of the WATM system is directly proportional to the mean of the buffer capacity. That is to say, the larger the buffer capacity of the WATM system is, the larger the packet delay is, which is right. After the analysis method is suitably adjusted, it can be applied to the extensive buffer system. Therefore, it extends Hie study range of the WATM system, and can guide the design of the WATM buffer system.