Due to the network resources conflicting, optical burst switching (OBS) network would raise some contentions, which is
often resolved by head-drop schemes since they are more simple and intuitional. However, the existing head-drop
schemes have two inherent defects, i.e., pseudo-contention and excessive-drop. Besides, they seldom consider how to
support QoS. In consequence of the shortcomings, this paper proposed the QoS-aware head-drop scheme, which can
selectively discard the head part of contending burst or the entire burst according to the priority and the truncated burst
relative length, i.e., the ratio to the original burst length. The simulation results show that it is able to overcome the
mentioned shortcomings, and to provide QoS guarantee.
In this paper, for the first time, we analyze the optical exclusive OR (XOR) gate based on cross-polarization modulation (XPolM) effect in semiconductor optical amplifier (SOA) using nonlinear polarization rotation (NPR) theory. The extinction ratio (ER) of optical XOR gate, which reflects the performance of the gate, is calculated in consideration of the injected current, the length and the polarization angle of input signals of the SOA. The performance of the optical XOR gate can be optimized for some proper parameters of the SOA.