A fiber-based, star-shaped joint time and frequency dissemination scheme is demonstrated. By working in cooperation with the existing commercial telecommunication network. Our scheme enables the frequency, time, and d...A fiber-based, star-shaped joint time and frequency dissemination scheme is demonstrated. By working in cooperation with the existing commercial telecommunication network. Our scheme enables the frequency, time, and digital data networks to be integrated together and could represent an ideal option of interconnection among scientific institutions.The compensation functions of the time and frequency transfer scheme are set at the client nodes. The complexity of the central node is thus reduced, and future expansion by the addition of further branches will be accomplished more easily.During a performance test in which the ambient temperature fluctuation is 30℃/day, timing signal dissemination stability is achieved to be approximately ±50 ps along 25-km-long fiber spools. After calibration, a timing signal synchronization accuracy of 100 ps is also realized. The proposed scheme offers an option of the construction of large-scale fiber-based frequency and time transfer networks.展开更多
1. Southern Coastal Optical Cable Engineering Project. The cable was completed and put into operation in 1992, and has a total length of 2,800km, starting from Nanjing in the north, via Shanghai, Hangzhou, Fuzhou, Xia...1. Southern Coastal Optical Cable Engineering Project. The cable was completed and put into operation in 1992, and has a total length of 2,800km, starting from Nanjing in the north, via Shanghai, Hangzhou, Fuzhou, Xiamen, Huizhou, leading to Guangzhou in the south, covering Jiangsu, Shanghai, Zhejiang, Fujian and Guangdong. The whole line has展开更多
With the arrival of the 4G and 5G,the telecommunications networks have experienced a large expansion of these networks.That enabled the integration of many services and adequate flow,thus enabling the operators to res...With the arrival of the 4G and 5G,the telecommunications networks have experienced a large expansion of these networks.That enabled the integration of many services and adequate flow,thus enabling the operators to respond to the growing demand of users.This rapid evolution has given the operators to adapt,their methods to the new technologies that increase.This complexity becomes more important,when these networks include several technologies to access different from the heterogeneous network like in the 4G network.The dimensional new challenges tell the application and the considerable increase in demand for services and the compatibility with existing networks,the management of mobility intercellular of users and it offers a better quality of services.Thus,the proposed solution to meet these new requirements is the sizing of the EPC(Evolved Packet Core)core network to support the 5G access network.For the case of Orange Guinea,this involves setting up an architecture for interconnecting the core networks of Sonfonia and Camayenne.The objectives of our work are of two orders:(1)to propose these solutions and recommendations for the heart network EPC sizing and the deployment to be adopted;(2)supply and architectural interconnection in the heart network EPC and an existing heart network.In our work,the model of traffic in communication that we use to calculate the traffic generated with each technology has link in the network of the heart.展开更多
Power grids deliver energy,and telecommunication networks transmit information.These two facilities are critical to human society.In this study,we conduct a comprehensive overview of the development of reliability met...Power grids deliver energy,and telecommunication networks transmit information.These two facilities are critical to human society.In this study,we conduct a comprehensive overview of the development of reliability metrics for power grids and telecommunication networks.The main purpose of this review is to promote and support the formulation of communication network reliability metrics with reference to the development of power grid reliability.We classify the metrics of power grid into the reliability of power distribution and generation/transmis-sion and the metrics of telecommunication network into connectivity-based,performance-based,and state-based metrics.Then,we exhibit and discuss the difference between the situations of the reliability metrics of the two systems.To conclude this study,we conceive a few topics for future research and development for telecommunication network reliability metrics.展开更多
Recently, there have been many mo- bile value-added services in the Chinese mo- bile telecommunication market nowadays. Am- ong them, the characteristics of Multimedia Mes- saging Service (MMS) have not yet been ful...Recently, there have been many mo- bile value-added services in the Chinese mo- bile telecommunication market nowadays. Am- ong them, the characteristics of Multimedia Mes- saging Service (MMS) have not yet been fully understood. In this paper, with the help of a cloud computing platform, we investigated the flow-level charactefistcs of Chinese MMS. All of the experimental data were collected by the TMS equipment deployed in a major node in Sou- them China. The collection time spanned six mo- nths. We performed high-level analysis to show the basic distributions of MMS characteristics. Then, by analysing the detailed MMS features, we determined the distribution of personal MMS, and made a comprehensive comparison between 2G and 3G MMS. Finally, we tried to build a model on the personal MMS inter-arrival time, and we found that the Weibull distribution was optimum.展开更多
In this paper we propose X-MAQoS, a novel XML-based multi-agent system for the QoS management in telecommunications networks. This system is characterized by the following features: (i) it handles a user profile and e...In this paper we propose X-MAQoS, a novel XML-based multi-agent system for the QoS management in telecommunications networks. This system is characterized by the following features: (i) it handles a user profile and exploits it jointly with suitable network resource management techniques to maximize user satisfaction; (ii) it is capable of operating in a large variety of telecommunications networks; (iii) it is semi-automatic; (iv) it exploits XML for guaranteeing a light, versatile and standard mechanism for information representation, storing and exchange. In this paper the basic features of the system are discussed in details. Furthermore, the main results of a performance evaluation study in UMTS environment, aiming at comparing X-MAQoS with alternative agent-based approaches for handling user access to telecommunications networks, are reported.展开更多
A multiobjective routing model for Multiprotocol Label Switching networks with multiple service types and traffic splitting is presented in this paper. The routing problem is formulated as a multiobjective mixed-integ...A multiobjective routing model for Multiprotocol Label Switching networks with multiple service types and traffic splitting is presented in this paper. The routing problem is formulated as a multiobjective mixed-integer program, where the considered objectives are the minimization of the bandwidth routing cost and the minimization of the load cost in the network links with a constraint on the maximal splitting of traffic trunks. Two different exact methods are developed for solving the formulated problem, one based on the classical constraint method and another based on a modified constraint method. A very extensive experimental study, with results on network performance measures in various reference test networks and in randomly generated networks, is also presented and its results are discussed.展开更多
A novel wavelength assignment scheme called the wavelength pre-assignment collision schedule (WPCS) is proposed for wavelength-routed networks. The WPCS pre-assigns the wavelength at the forward detection phase, and...A novel wavelength assignment scheme called the wavelength pre-assignment collision schedule (WPCS) is proposed for wavelength-routed networks. The WPCS pre-assigns the wavelength at the forward detection phase, and schedules the potential collision by priority. The potential collision is scheduled at the forward detection phase and the blocking of the wavelength assignment is reduced. Simulation is conducted with several other existing schemes. The numerical results show that WPCS performs better than other schemes in blocking probability under various traffic conditions.展开更多
Cyclic polling-based dynamic wavelength and bandwidth allocation algorithm supporting differentiated classes of services in wavelength division multiplexing (WDM) passive optical networks (PONs) is proposed. In th...Cyclic polling-based dynamic wavelength and bandwidth allocation algorithm supporting differentiated classes of services in wavelength division multiplexing (WDM) passive optical networks (PONs) is proposed. In this algorithm, the optical line terminal (OLT) polls for optical network unit (ONU) requests to transmit data in a cyclic manner. Services are categorized into three classes: expedited forward (EF) priority, assured forwarding (AF) priority, and best effort (BE) priority. The OLT assigns bandwidth for different priorities with different strategies. Simulation results show that the proposed algorithm saves a lot of downstream bandwidth under low load and does not show the light-load penalty compared with the simultaneous and interleaved polling schemes.展开更多
Using data from 1986-2005, the present paper estimates the impact of direct knowledge spilled over from G-7 countries on China's economy. We use telephone line penetration rates andpersonnel flows to estimate the dir...Using data from 1986-2005, the present paper estimates the impact of direct knowledge spilled over from G-7 countries on China's economy. We use telephone line penetration rates andpersonnel flows to estimate the direct spillover effect. Our results show that direct knowledge spillovers through telecommunication networks and personnelflows are important components of international R&D spillovers in China. These direct channels of spillover effectively accelerate China's economic growth. Therefore, China should invest more in human capital and in its telecommunication network to enhance the absorptive capacity of direct R&D spillovers, and to increase communication with other nations, in particular the USA and Japan. More subsidies to domestic R&D research and purchase of intermediate goods will help to raise China's R&D intensity.展开更多
With the rapid development of optical elements with large capacity and high speed, the network architecture is of great importance in determing the performance of wavelength division multiplexing passive optical netwo...With the rapid development of optical elements with large capacity and high speed, the network architecture is of great importance in determing the performance of wavelength division multiplexing passive optical network (WDM-PON). This paper proposes a switching struc^re based on the tunable wavelength converter (TWC) and the ar- rayed-waveguide grating (AWG) for WDM-PON, in order to provide the function of opitcal virtual private network (OVPN). Using the tunable wavelength converter technology, this switch structure is designed and works between the optical line terminal (OLT) and optical network units (ONUs) in the WDM-PON system. Moreover, the wavelength assignment of upstream/downstream can be realized and direct communication between ONUs is also allowed by privite wavelength channel. Simulation results show that the proposed TWC and AWG based switching structure is able to achieve OVPN function and to gain better performances in terms of bite error rate (BER) and time delay.展开更多
in order to project a reliable telecommunication network ,we have to measure the call lossrate of present traffic and to predzct the traffic of hajective network. In this paper we point out that afactor of real commun...in order to project a reliable telecommunication network ,we have to measure the call lossrate of present traffic and to predzct the traffic of hajective network. In this paper we point out that afactor of real communication needs for subscrihas should be added in studying the traffic source char-acterization. Generally, the predicted traffic does not equal to the real demends, Considered asubscriber's psychological facter for attempts in busy-hour, a mathematical medel of probable dertva-tive calls from each real communication demand is given,with which the calling-up probabity, andthe repeating attempt probability of original subscribers on line occupation are calculated and the rela-tionship between the traffic and the real cammunication need is predicted.展开更多
We propose a new repeat-until-success (RUS) measurement-based scheme to implement quantum controlled phase gates according to the effect of dipole-induced-transparency (DIT) in a cavity and single-photon interfere...We propose a new repeat-until-success (RUS) measurement-based scheme to implement quantum controlled phase gates according to the effect of dipole-induced-transparency (DIT) in a cavity and single-photon interference at a 50:50 beam-splitter. In our scheme, the DIT effect can appropriately attach a photon to the state of the dipoles according to their initial state, and in this way, a suitably encoded dipole-photon state is thus prepared. The measurement of the photon after it passing through a 50:50 beam-splitter can project the encoded matter-photon state to either a desired phase gate operation for the matter qubits or to their initial states. The recurrence of the initial state permits us to implement the desired entangling gate in a RUS way.展开更多
Considering the influence of more random atmospheric turbulence, worse pointing errors and highly dynamic link on the transmission performance of mobile multiple-input multiple-output (MIMO) free space optics (FSO...Considering the influence of more random atmospheric turbulence, worse pointing errors and highly dynamic link on the transmission performance of mobile multiple-input multiple-output (MIMO) free space optics (FSO) communica- tion systems, this paper establishes a channel model for the mobile platform. Based on the combination of Alamouti space-time code and time hopping ultra-wide band (TH-UWB) communications, a novel repetition space-time coding (RSTC) method for mobile 2x2 free-space optical communications with pulse position modulation (PPM) is devel- oped. In particular, two decoding methods of equal gain combining (EGC) maximum likelihood detection (MLD) and correlation matrix detection (CMD) are derived. When a quasi-static fading and weak turbulence channel model are considered, simulation results show that whether the channel state information (CSI) is known or not, the coding sys- tem demonstrates more significant performance of the symbol error rate (SER) than the uncoding. In other words, transmitting diversity can be achieved while conveying the information only through the time delays of the modulated signals transmitted from different antennas. CMD has almost the same effect of signal combining with maximal ratio combining (MRC). However, when the channel correlation increases, SER performance of the coding 2×2 system de- grades significantly.展开更多
基金supported by the National Key Scientific Instrument and Equipment Development Project,China(Grant No.2013YQ09094303)the Program of International Science and Technology Cooperation,China(Grant No.2016YFE0100200)
文摘A fiber-based, star-shaped joint time and frequency dissemination scheme is demonstrated. By working in cooperation with the existing commercial telecommunication network. Our scheme enables the frequency, time, and digital data networks to be integrated together and could represent an ideal option of interconnection among scientific institutions.The compensation functions of the time and frequency transfer scheme are set at the client nodes. The complexity of the central node is thus reduced, and future expansion by the addition of further branches will be accomplished more easily.During a performance test in which the ambient temperature fluctuation is 30℃/day, timing signal dissemination stability is achieved to be approximately ±50 ps along 25-km-long fiber spools. After calibration, a timing signal synchronization accuracy of 100 ps is also realized. The proposed scheme offers an option of the construction of large-scale fiber-based frequency and time transfer networks.
文摘1. Southern Coastal Optical Cable Engineering Project. The cable was completed and put into operation in 1992, and has a total length of 2,800km, starting from Nanjing in the north, via Shanghai, Hangzhou, Fuzhou, Xiamen, Huizhou, leading to Guangzhou in the south, covering Jiangsu, Shanghai, Zhejiang, Fujian and Guangdong. The whole line has
文摘With the arrival of the 4G and 5G,the telecommunications networks have experienced a large expansion of these networks.That enabled the integration of many services and adequate flow,thus enabling the operators to respond to the growing demand of users.This rapid evolution has given the operators to adapt,their methods to the new technologies that increase.This complexity becomes more important,when these networks include several technologies to access different from the heterogeneous network like in the 4G network.The dimensional new challenges tell the application and the considerable increase in demand for services and the compatibility with existing networks,the management of mobility intercellular of users and it offers a better quality of services.Thus,the proposed solution to meet these new requirements is the sizing of the EPC(Evolved Packet Core)core network to support the 5G access network.For the case of Orange Guinea,this involves setting up an architecture for interconnecting the core networks of Sonfonia and Camayenne.The objectives of our work are of two orders:(1)to propose these solutions and recommendations for the heart network EPC sizing and the deployment to be adopted;(2)supply and architectural interconnection in the heart network EPC and an existing heart network.In our work,the model of traffic in communication that we use to calculate the traffic generated with each technology has link in the network of the heart.
文摘Power grids deliver energy,and telecommunication networks transmit information.These two facilities are critical to human society.In this study,we conduct a comprehensive overview of the development of reliability metrics for power grids and telecommunication networks.The main purpose of this review is to promote and support the formulation of communication network reliability metrics with reference to the development of power grid reliability.We classify the metrics of power grid into the reliability of power distribution and generation/transmis-sion and the metrics of telecommunication network into connectivity-based,performance-based,and state-based metrics.Then,we exhibit and discuss the difference between the situations of the reliability metrics of the two systems.To conclude this study,we conceive a few topics for future research and development for telecommunication network reliability metrics.
基金supported by National Natural Science Foundation of China(61304256)Zhejiang Provincial Natural Science Foundation of China(LQ13F030013)+4 种基金Project of the Education Department of Zhejiang Province(Y201327006)Young Researchers Foundation of Zhejiang Provincial Top Key Academic Discipline of Mechanical Engineering and Zhejiang Sci-Tech University Key Laboratory(ZSTUME01B15)New Century 151 Talent Project of Zhejiang Province521 Talent Project of Zhejiang Sci-Tech UniversityYoung and Middle-aged Talents Foundation of Zhejiang Provincial Top Key Academic Discipline of Mechanical Engineering
基金supported in part by the National Science and Technology Major Project under Grant No.2012ZX03002008the National Natural Science Foundation of China under Grant No.61072061the National "111" Project of China’s Higher Education under Grant No.B08004
文摘Recently, there have been many mo- bile value-added services in the Chinese mo- bile telecommunication market nowadays. Am- ong them, the characteristics of Multimedia Mes- saging Service (MMS) have not yet been fully understood. In this paper, with the help of a cloud computing platform, we investigated the flow-level charactefistcs of Chinese MMS. All of the experimental data were collected by the TMS equipment deployed in a major node in Sou- them China. The collection time spanned six mo- nths. We performed high-level analysis to show the basic distributions of MMS characteristics. Then, by analysing the detailed MMS features, we determined the distribution of personal MMS, and made a comprehensive comparison between 2G and 3G MMS. Finally, we tried to build a model on the personal MMS inter-arrival time, and we found that the Weibull distribution was optimum.
文摘In this paper we propose X-MAQoS, a novel XML-based multi-agent system for the QoS management in telecommunications networks. This system is characterized by the following features: (i) it handles a user profile and exploits it jointly with suitable network resource management techniques to maximize user satisfaction; (ii) it is capable of operating in a large variety of telecommunications networks; (iii) it is semi-automatic; (iv) it exploits XML for guaranteeing a light, versatile and standard mechanism for information representation, storing and exchange. In this paper the basic features of the system are discussed in details. Furthermore, the main results of a performance evaluation study in UMTS environment, aiming at comparing X-MAQoS with alternative agent-based approaches for handling user access to telecommunications networks, are reported.
基金financially supported by programme COMPETE of the EC Community Support Framework Ⅲcosponsored by the EC fund FEDERnational funds(Portuguese Foundation for Science and Technology under projects PTDC/EEA-TEL/101884/2008,PEstOE/EEI/UI0308/2014 and PEst-OE/MAT/ UI0152)
文摘A multiobjective routing model for Multiprotocol Label Switching networks with multiple service types and traffic splitting is presented in this paper. The routing problem is formulated as a multiobjective mixed-integer program, where the considered objectives are the minimization of the bandwidth routing cost and the minimization of the load cost in the network links with a constraint on the maximal splitting of traffic trunks. Two different exact methods are developed for solving the formulated problem, one based on the classical constraint method and another based on a modified constraint method. A very extensive experimental study, with results on network performance measures in various reference test networks and in randomly generated networks, is also presented and its results are discussed.
基金supported in part by the National"863" Program of China (No.2007AA01Z252)the National "973" Program of China (No.2007CB310705)+3 种基金the National Natural Science Foundation of China (No.60711140087)the Program for New Century Excellent Talents in University (No.06-0090)the Program for Changjiang Scholars and Innovative Research Team in University (No.IRT0609)the International S & T Cooperation Program of China (No.2006DFA11040)
文摘A novel wavelength assignment scheme called the wavelength pre-assignment collision schedule (WPCS) is proposed for wavelength-routed networks. The WPCS pre-assigns the wavelength at the forward detection phase, and schedules the potential collision by priority. The potential collision is scheduled at the forward detection phase and the blocking of the wavelength assignment is reduced. Simulation is conducted with several other existing schemes. The numerical results show that WPCS performs better than other schemes in blocking probability under various traffic conditions.
基金supported by the National "973" Program of China (No. 2007CB310705)the National Natural Science Foundation of China (Nos. 60772024, 60711140087)+3 种基金the National "863" Program of China (No. 2007AA01Z255)the Program for Changjiang Scholars and Innovative Research Team in University (No. IRT0609)the International Science and Technology Cooperation Project of China (No. 2006DFA11040)the 111 Project of China (No. B07005).
文摘Cyclic polling-based dynamic wavelength and bandwidth allocation algorithm supporting differentiated classes of services in wavelength division multiplexing (WDM) passive optical networks (PONs) is proposed. In this algorithm, the optical line terminal (OLT) polls for optical network unit (ONU) requests to transmit data in a cyclic manner. Services are categorized into three classes: expedited forward (EF) priority, assured forwarding (AF) priority, and best effort (BE) priority. The OLT assigns bandwidth for different priorities with different strategies. Simulation results show that the proposed algorithm saves a lot of downstream bandwidth under low load and does not show the light-load penalty compared with the simultaneous and interleaved polling schemes.
基金supported by the National Natural Science Foundation of China (Grant No. 70672057 and Grant No. 70272025)
文摘Using data from 1986-2005, the present paper estimates the impact of direct knowledge spilled over from G-7 countries on China's economy. We use telephone line penetration rates andpersonnel flows to estimate the direct spillover effect. Our results show that direct knowledge spillovers through telecommunication networks and personnelflows are important components of international R&D spillovers in China. These direct channels of spillover effectively accelerate China's economic growth. Therefore, China should invest more in human capital and in its telecommunication network to enhance the absorptive capacity of direct R&D spillovers, and to increase communication with other nations, in particular the USA and Japan. More subsidies to domestic R&D research and purchase of intermediate goods will help to raise China's R&D intensity.
基金supported by the National High Technical Research and Development Program of China(No.2012AA050804)
文摘With the rapid development of optical elements with large capacity and high speed, the network architecture is of great importance in determing the performance of wavelength division multiplexing passive optical network (WDM-PON). This paper proposes a switching struc^re based on the tunable wavelength converter (TWC) and the ar- rayed-waveguide grating (AWG) for WDM-PON, in order to provide the function of opitcal virtual private network (OVPN). Using the tunable wavelength converter technology, this switch structure is designed and works between the optical line terminal (OLT) and optical network units (ONUs) in the WDM-PON system. Moreover, the wavelength assignment of upstream/downstream can be realized and direct communication between ONUs is also allowed by privite wavelength channel. Simulation results show that the proposed TWC and AWG based switching structure is able to achieve OVPN function and to gain better performances in terms of bite error rate (BER) and time delay.
文摘in order to project a reliable telecommunication network ,we have to measure the call lossrate of present traffic and to predzct the traffic of hajective network. In this paper we point out that afactor of real communication needs for subscrihas should be added in studying the traffic source char-acterization. Generally, the predicted traffic does not equal to the real demends, Considered asubscriber's psychological facter for attempts in busy-hour, a mathematical medel of probable dertva-tive calls from each real communication demand is given,with which the calling-up probabity, andthe repeating attempt probability of original subscribers on line occupation are calculated and the rela-tionship between the traffic and the real cammunication need is predicted.
基金supported by the National Natural Science Foundation of China under Grant No.60578050
文摘We propose a new repeat-until-success (RUS) measurement-based scheme to implement quantum controlled phase gates according to the effect of dipole-induced-transparency (DIT) in a cavity and single-photon interference at a 50:50 beam-splitter. In our scheme, the DIT effect can appropriately attach a photon to the state of the dipoles according to their initial state, and in this way, a suitably encoded dipole-photon state is thus prepared. The measurement of the photon after it passing through a 50:50 beam-splitter can project the encoded matter-photon state to either a desired phase gate operation for the matter qubits or to their initial states. The recurrence of the initial state permits us to implement the desired entangling gate in a RUS way.
基金supported by the National Natural Science Foundation of China(No.61205106)
文摘Considering the influence of more random atmospheric turbulence, worse pointing errors and highly dynamic link on the transmission performance of mobile multiple-input multiple-output (MIMO) free space optics (FSO) communica- tion systems, this paper establishes a channel model for the mobile platform. Based on the combination of Alamouti space-time code and time hopping ultra-wide band (TH-UWB) communications, a novel repetition space-time coding (RSTC) method for mobile 2x2 free-space optical communications with pulse position modulation (PPM) is devel- oped. In particular, two decoding methods of equal gain combining (EGC) maximum likelihood detection (MLD) and correlation matrix detection (CMD) are derived. When a quasi-static fading and weak turbulence channel model are considered, simulation results show that whether the channel state information (CSI) is known or not, the coding sys- tem demonstrates more significant performance of the symbol error rate (SER) than the uncoding. In other words, transmitting diversity can be achieved while conveying the information only through the time delays of the modulated signals transmitted from different antennas. CMD has almost the same effect of signal combining with maximal ratio combining (MRC). However, when the channel correlation increases, SER performance of the coding 2×2 system de- grades significantly.