This paper presents an overlay multicast tree construction algorithm for synchronized realtime media multicast service over Internet which traditionally supports only best-effort service. The proposed tree construction algorithm is implemented to reduce not only the average delay of group members in order to support realtime media service, but also the delay variance among group members to provide an effective synchronized service. Basically, the orthogonal genetic algorithm is employed to obtain the near optimal tree among clusters with low computational complexity since the given problem is NP-complete. In addition, a dynamic tree maintenance process is proposed to effectively update the tree when members change due to leave or join. Finally, we describe experiments that show the superior performance of the proposed algorithm.

A shared buffer ATM switch loaded with bursty input traffic is modeled by a discrete-time queueing system. Also, the unbalanced and correlated routing traffic patterns are considered. An approximation method to analyze the queueing system under consideration is developed. To overcome the problem regarding the size of state space to be dealt with, the entire switching system is decomposed into several subsystems, and then each subsystem is analyzed in isolation. We first propose an efficient algorithm for superposing all the individual bursty cell arrival processes to the switch. And then, the maximum entropy method is applied to obtain the steady-state probability distribution of the queueing system. From the obtained steady-state probabilities, we can derive some performance measures such as cell loss probability and average delay. Numerical examples of the proposed approximation method are given, which are compared with simulation results.

In this paper, CDMA slotted ALOHA system with finite size of buffers is proposed. To analyze the system performance, we use the linear approximate solution based on restricted occupancy urn models. We evaluate the system performance in terms of throughput, average delay, and rejection probability and clarify the effect of buffer capacity.

We study behavior of multi-zone MCA (Multi-Channel Access) mobile communication systems with a finite number of channels in each zone. Three queueing schemes for channel requests named holding scheme, ready-nonready scheme, and optimum scheme are investigated. The delay performance of channel requests is studied through computer simulations.