In this paper, we propose a mathe- matical model for long reach Passive Optical Networks （PON） planning. The model consid- ers the traffic demand, user requirements and physical constraints. It can support conven- t...In this paper, we propose a mathe- matical model for long reach Passive Optical Networks （PON） planning. The model consid- ers the traffic demand, user requirements and physical constraints. It can support conven- tional star-like topologies as well as cascade PON networks. Then a two-stage evolutional algorithm is described to solve this problem. The first stage was to find a proper splitter can- didate site set, composing the outer loop. The second stage aimed to get the optimal topology when the splitter locations were selected, com- posing the internal loop. In this algorithm, the Pr/ifer sequence is used to build up a one-to-one correspondence between a PON network configuration and a chromosome. Compared with the results obtained by the enumeration method, the proposed model and algorithm are shown to be effective and accu- rate.展开更多
The explosive increase in data traffic requires networks to provide higher capacity and long-haul transmission capabilities.This paper introduces new results on high-order modulation and efficient Digital Signal Proce...The explosive increase in data traffic requires networks to provide higher capacity and long-haul transmission capabilities.This paper introduces new results on high-order modulation and efficient Digital Signal Processing algorithms to reduce various transmission limitations in coherent receiving systems.Polarization Division Multiplexed Quadrature Phase Shift Keying(PDM-QPSK)is deployed to reach high bit rates,provides modified digital clock recovery,and allows BER-Aided Constant Modulus Algorithm(BA-CMA)equalising.A Soft Decision-Forward Error Correction(SD-FEC)algorithm and a joint scheme with timing recovery and adaptive equaliser are used to achieve better performance.A compact coherent transceiver is also developed.These techniques have been applied in the largest 100 G Optical Transport Network(OTN)deployment in the world,the backbone expansion project for Phase 3 of the China Education and Research Network(CERNET),with a total transmission length of 10 000 km.展开更多
Applying network duality and elastic mechanics, we investigate the interactions among Internet flows by con- structing a weighted undirected network, where the vertices and the edges represent the flows and the mutual...Applying network duality and elastic mechanics, we investigate the interactions among Internet flows by con- structing a weighted undirected network, where the vertices and the edges represent the flows and the mutual dependence between flows, respectively. Based on the obtained flow interaction network, we find the existence of ＇super flow＇ in the Internet, indicating that some flows have a great impact on a huge number of other flows; moreover, one flow can spread its influence to another through a limited quantity of flows （less than 5 in the experimental simulations）, which shows strong small-world characteristics like the social network. To reflect the flow interactions in the physical network congestion evaluation, the ＇congestion coefficient＇ is proposed as a new metric which shows a finer observation on congestion than the eonventional one.展开更多
基金supported by National High Technology Research and Development Program of China under Grant No.2011AA01A104National 973 Program underGrant No. 2013CB329204National Natural Science Foundation of China under Grant No.61100206
文摘In this paper, we propose a mathe- matical model for long reach Passive Optical Networks （PON） planning. The model consid- ers the traffic demand, user requirements and physical constraints. It can support conven- tional star-like topologies as well as cascade PON networks. Then a two-stage evolutional algorithm is described to solve this problem. The first stage was to find a proper splitter can- didate site set, composing the outer loop. The second stage aimed to get the optimal topology when the splitter locations were selected, com- posing the internal loop. In this algorithm, the Pr/ifer sequence is used to build up a one-to-one correspondence between a PON network configuration and a chromosome. Compared with the results obtained by the enumeration method, the proposed model and algorithm are shown to be effective and accu- rate.
基金supported by the National Natural Science Foundation of China under Grant No. 60932004the National High Technical Research and Development Program of China (863 Program) under Grants No. 2012AA011301,No. 2012AA011303
文摘The explosive increase in data traffic requires networks to provide higher capacity and long-haul transmission capabilities.This paper introduces new results on high-order modulation and efficient Digital Signal Processing algorithms to reduce various transmission limitations in coherent receiving systems.Polarization Division Multiplexed Quadrature Phase Shift Keying(PDM-QPSK)is deployed to reach high bit rates,provides modified digital clock recovery,and allows BER-Aided Constant Modulus Algorithm(BA-CMA)equalising.A Soft Decision-Forward Error Correction(SD-FEC)algorithm and a joint scheme with timing recovery and adaptive equaliser are used to achieve better performance.A compact coherent transceiver is also developed.These techniques have been applied in the largest 100 G Optical Transport Network(OTN)deployment in the world,the backbone expansion project for Phase 3 of the China Education and Research Network(CERNET),with a total transmission length of 10 000 km.
基金Supported by the National Natural Science Foundation of China under Grant No 61100206the Beijing Natural Science Foundation under Grant No 4142036the Research Fund for Doctoral Program of Higher Education of China under Grant No20120005130001
文摘Applying network duality and elastic mechanics, we investigate the interactions among Internet flows by con- structing a weighted undirected network, where the vertices and the edges represent the flows and the mutual dependence between flows, respectively. Based on the obtained flow interaction network, we find the existence of ＇super flow＇ in the Internet, indicating that some flows have a great impact on a huge number of other flows; moreover, one flow can spread its influence to another through a limited quantity of flows （less than 5 in the experimental simulations）, which shows strong small-world characteristics like the social network. To reflect the flow interactions in the physical network congestion evaluation, the ＇congestion coefficient＇ is proposed as a new metric which shows a finer observation on congestion than the eonventional one.
