Multicast IP optical networks in multimedia communications

近年来，对从点到多点传输多播业务的需求不断增加。另一方面，由于互联网业务量的快速增长，需要在现有的ATM网络和下一代光突发交换网络上灵活地传输IP业务。在本研究中，首先，我们提出了一种在局域网中的WDM单跳网络中多播业务下具有收发机调谐延迟的波长分配算法。我们提出的算法可以通过将相同的波长分配给数据信道来屏蔽收发机的调谐时间，在该数据信道中，节点在连续的时隙中向相同的目的节点发送数据分组或从相同的源节点接收数据分组。仿真结果表明，该算法能够提高平均分组时延和吞吐量性能。其次，提出了一种主动缓存优先的可变长度IP分组在输入缓冲ATM交换机上的调度算法。活动缓冲器被定义为属于分组的信元到达某个时隙的缓冲器，并且这些信元可以在不增加队列长度的情况下有效地交换。我们在计算机模拟中评估了分组丢失率和平均分组时延。结果表明，该方案能有效地提高丢包率。第三，提出了一种最小化光突发交换WDM网络中到达突发所产生的空闲数据信道容量(称为空闲)的调度算法。在该调度算法中，当某个时刻到达光核心路由器的突发可以利用空闲在某些数据信道上传输时，该调度算法选择在突发传输后新产生空闲的数据信道。计算机仿真结果表明，该算法能有效地提高突发丢失率。

Recently, the need for transmitting multicast traffic from point to multipoint is increasing. On the other hand, due to the rapid increase of the Internet traffic, the flexible transmission of IP traffic on the existing ATM network as well as next generation optical burst switched network is needed. In this research, first, we propose a wavelength assignment algorithm with transceiver tuning latencies under multicast traffic in WDM single-hop network in LAN. Our proposed algorithm can mask tuning time of a transceiver by assigning the identical wavelength to the data channel in which the node transmits data packet to the same destination node or receives data packet from the same source node in continuous time slots. It is shown that the proposed algorithm can improve the mean packet delay and the throughput performance. Second, we propose a scheduling algorithm with priority of active buffer for variable length IP packet over input buffered ATM switch. The active buffer is defined as a buffer at which cells that belong to a packet arrive at a certain time slot, and these cells can be switched effectively without increasing queue length. We evaluate the packet loss probability and the mean packet delay in the computer simulations. As a result, it is shown that the proposed scheme can improve the packet loss probability effectively. Third, we propose a scheduling algorithm minimizing the unused data channel capacity (it is called void) generated by arriving bursts in optical burst switched WDM network. In the proposed scheduling algorithm, when the burst which has arrived at optical core router at a certain time can be transmitted in some data channels by using a void, the proposed scheduling algorithm selects the data channel in which a void newly being generated after the burst transmission becomes minimum. By computer simulations, it is shown that our proposed algorithm can improve burst loss ratio.