Previous dynamic resource allocation methods (Separate Path Select, SPS) for survivable networks are always separated into two steps, that is, to determine an optimal primary path first and then select a backup path f...Previous dynamic resource allocation methods (Separate Path Select, SPS) for survivable networks are always separated into two steps, that is, to determine an optimal primary path first and then select a backup path for the primary path. But SPS cannot achieve a good network performance. In this paper we analyze the drawback of the traditional SPS technique and propose an efficient shared protection method called M _ SPS. Instead of rejecting an arrival call immediately when a backup lightpath for the optimal primary lightpath cannot be found, M _ SPS continue to try the sub-optimal one until a legal primarybackup pair can be selected. We apply M SPS to CERNET_ Like and NSFNET networks. The results show that M _ SPS improves the network performance remarkably.展开更多
In this paper, a Wavelength Division Multiplexing (WDM) network model based on the equivalent networks is described, and wavelength-dependent equivalent arc, equivalent networks, equivalent multicast tree and some oth...In this paper, a Wavelength Division Multiplexing (WDM) network model based on the equivalent networks is described, and wavelength-dependent equivalent arc, equivalent networks, equivalent multicast tree and some other terms are presented. Based on this model and relevant Routing and Wavelength Assign- ment (RWA) strategy, a unicast RWA algorithm and a multicast RWA algorithm are presented. The wave- length-dependent equivalent arc expresses the schedule of local RWA and the equivalent network expresses the whole topology of WDM optical networks, so the two algorithms are of the flexibility in RWA and the optimi- zation of the whole problem. The theoretic analysis and simulation results show the two algorithms are of the stronger capability and the lower complexity than the other existing algorithms for RWA problem, and the complexity of the two algorithms are only related to the scale of the equivalent networks. Finally, we prove the two algorithms’ feasibility and the one-by-one corresponding relation between the equivalent multicast tree and original multicast tree, and point out the superiorities and drawbacks of the two algorithms respectively.展开更多
A plastic surface-relief grating as a wavelength division multiplexer is designed and fabricated with the conventional mould pressing technique using the transmission-type fused quartz phase grating as mask pattern an...A plastic surface-relief grating as a wavelength division multiplexer is designed and fabricated with the conventional mould pressing technique using the transmission-type fused quartz phase grating as mask pattern and polycarbonate as basal material.The experiment results show that in an optimizing process,the plastic surface-relief grating has the highest firstorder diffraction efficiency under adequate groove depth and incident angle,and can be used as the best optical path for wavelength division multiplexing(WDM).We also establish the experiment setup for testing the WDM performance of the plastic surface-relief grating based wavelength division multiplexer.The results show that the proposed wavelength division multiplexer has the high-stability temperature characteristics,the low insertion loss of less than 5 dB,the large isolation of greater than 20 dB,the low polarization-dependent loss(PDL) of less than 0.4 dB and the relatively steep pass-band characteristics.It is a WDM device with good performance,which can be applied in short distance communication.展开更多
文摘Previous dynamic resource allocation methods (Separate Path Select, SPS) for survivable networks are always separated into two steps, that is, to determine an optimal primary path first and then select a backup path for the primary path. But SPS cannot achieve a good network performance. In this paper we analyze the drawback of the traditional SPS technique and propose an efficient shared protection method called M _ SPS. Instead of rejecting an arrival call immediately when a backup lightpath for the optimal primary lightpath cannot be found, M _ SPS continue to try the sub-optimal one until a legal primarybackup pair can be selected. We apply M SPS to CERNET_ Like and NSFNET networks. The results show that M _ SPS improves the network performance remarkably.
基金Supported by the Natrual Science Foundation of Shaanxi (No.2004A02) and Outstanding Scholar Project of P. R. China (2002).
文摘In this paper, a Wavelength Division Multiplexing (WDM) network model based on the equivalent networks is described, and wavelength-dependent equivalent arc, equivalent networks, equivalent multicast tree and some other terms are presented. Based on this model and relevant Routing and Wavelength Assign- ment (RWA) strategy, a unicast RWA algorithm and a multicast RWA algorithm are presented. The wave- length-dependent equivalent arc expresses the schedule of local RWA and the equivalent network expresses the whole topology of WDM optical networks, so the two algorithms are of the flexibility in RWA and the optimi- zation of the whole problem. The theoretic analysis and simulation results show the two algorithms are of the stronger capability and the lower complexity than the other existing algorithms for RWA problem, and the complexity of the two algorithms are only related to the scale of the equivalent networks. Finally, we prove the two algorithms’ feasibility and the one-by-one corresponding relation between the equivalent multicast tree and original multicast tree, and point out the superiorities and drawbacks of the two algorithms respectively.
基金supported by the Natural Science Foundation of Fujian Province of China (No.2011J01353)
文摘A plastic surface-relief grating as a wavelength division multiplexer is designed and fabricated with the conventional mould pressing technique using the transmission-type fused quartz phase grating as mask pattern and polycarbonate as basal material.The experiment results show that in an optimizing process,the plastic surface-relief grating has the highest firstorder diffraction efficiency under adequate groove depth and incident angle,and can be used as the best optical path for wavelength division multiplexing(WDM).We also establish the experiment setup for testing the WDM performance of the plastic surface-relief grating based wavelength division multiplexer.The results show that the proposed wavelength division multiplexer has the high-stability temperature characteristics,the low insertion loss of less than 5 dB,the large isolation of greater than 20 dB,the low polarization-dependent loss(PDL) of less than 0.4 dB and the relatively steep pass-band characteristics.It is a WDM device with good performance,which can be applied in short distance communication.
