抄録
This paper considers the performance of optical burst switched networks with burst segmentation, wavelength conversion and upper-layer retransmission. When a burst arrives at an intermediate node and finds its allocated wavelength occupied, it attempts to find another idle wavelength among a limited number of wavelengths to which the allocated wavelength can be converted. If the incoming burst cannot find any idle wavelength in the range, the ongoing burst in the allocated wavelength is segmented and its tail part which overlaps with the incoming burst is dropped and retransmitted as a retransmitted burst in a later time by upper-layer retransmission mechanisms such as TCP. Focusing on an outgoing optical fiber shared under wavelength division multiplexing, we model it as a multi-server retrial queueing system without waiting room, in which an arriving customer chooses his server out of a group of servers with a state-dependent probability. We formulate a bivariate Markov chain to analyze the model and also perform simulation experiments to validate the analysis model. Numerical examples show that the wavelength conversion technique is effective to lessen the contention of bursts at low traffic intensity and that the degree of contention among bursts is almost insensitive to the retransmission rate. They further reveal that even a small range of wavelength conversion can significantly alleviate the contention among bursts.
