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Abstract: Delay preemption that combines the techniques of preemption and small buffers is an efficient solution for burst contention. However, due to the phenomenon of over-usage on buffer, the low-loss demand of high priority is not ensured especially in high traffic states. In this article, to improve the blocking of delay preemption, we propose a modified scheme named limited delay preemption based priority (limited-DPP) that constrains the buffered right of low priority within the moderate and high traffic states. To validate the efficiency of limited-DPP, the comprehensive analysis and simulation are performed in terms of loss and buffering time. [Copyright &y& Elsevier]

Abstract: In this paper, we propose a novel high-speed stream cipher encryption scheme based on the true random key generated by a chaotic semiconductor laser. A 5-Gbits/s non-return-to-zero plaintext is successfully encrypted and decrypted using this cryptography by numerical simulations. Compared with chaos-based optical communications for a single channel utilizing analog chaotic optical carrier, the performance of the proposed setup of stream ciphers based on true random numbers generated by chaotic light is improved. The scheme overcomes the shortcoming of quality decrease of chaos communications caused by decline of chaos synchronization. The proposed setup can be applied in the areas of real-time high-speed physical encryption. [Copyright &y& Elsevier]

Unequal spaced channel allocation (USCA) is a technique to reduce Four wave mixing (FWM). In this paper, system performance of 8 channel WDM system considering different optical transmitter formats (RZ, NRZ, Raised cosine and Gaussian) using USCA has been evaluated in terms of Q-factor. The simulation results reveal that four wave mixing is minimum for NRZ format. Also the effect of changing the laser power and increasing the bit rate has been observed. [ABSTRACT FROM AUTHOR]