In this paper we propose a novel Dynamic Bandwidth Assignment （DBA） algorithm for Ethernet-based Passive Optical Networks （EPON） which offers multiple kinds of services. To satisfy crucial Quality of Service （QoS...In this paper we propose a novel Dynamic Bandwidth Assignment （DBA） algorithm for Ethernet-based Passive Optical Networks （EPON） which offers multiple kinds of services. To satisfy crucial Quality of Service （QoS） requirement for Time Division Multiplexing （TDM） service and achieve fair and high bandwidth utilization simultaneously, the algorithm integrates periodic, for TDM service, and polling granting for Ethernet service. Detailed simulation shows that the algorithm guarantees carrier-grade QoS for TDM service, high bandwidth utilization and good fairness of bandwidth assignment among Optical Network Units （ONU）.展开更多
Larger wireless access networks are required to meet the growing demand for mobile traffic and multimedia services. The use of RoF (Radio over Fiber) technology in combination with millimeter waves is a potential resp...Larger wireless access networks are required to meet the growing demand for mobile traffic and multimedia services. The use of RoF (Radio over Fiber) technology in combination with millimeter waves is a potential response to the requirements of broadband applications and high capacity networks. In this paper, we proposed a RoF architecture able to provide very high-speed wireless access points up to Gbps considering an indoor and outdoor environment conform to IEEE 802.11ad and IEEE 802.15.3c standard. Optical transmission and radio coverage have been studied by considering the uplink and downlink. System performance has been evaluated in the relation to the Error Vector Magnitude (EVM) for various modulation formats (BPSK, QPSK and 16QAM). Results showed that millimeter wave signals are successfully delivered over a 50 km fiber link and a wireless channel up to 32 m. Data throughput up to 5.28 Gbps has been reached. The proposed architecture can extend the range of applications for wireless communications in association with the unlicensed 60 GHz band with the advantages of better capacity, a wider coverage area and a reduction in the investment cost.展开更多
Bulk arrival retrial G-queue with impatient customers and multi-servicessubject to server breakdowns has been analyzed. The system allows the arrival oftwo types of customers: positive customers and negative customers...Bulk arrival retrial G-queue with impatient customers and multi-servicessubject to server breakdowns has been analyzed. The system allows the arrival oftwo types of customers: positive customers and negative customers in the system.The negative customers make the server fail if they find the server in busy state,whereas positive customers are served if the server is idle otherwise they join thevirtual pool of customers called orbit. The customers from the retrial orbit try theirchance again for the service. The customers have the option of obtaining more than oneservice. Moreover, the customers are impatient and may renege from the system withprobability (1−r ). The server is sent for repair as soon as it breakdowns;after repair,the service process starts again. Also, the server has the provision to initiate the servicewhen there areN customers accumulated in the system. Using supplementary variablestechnique and generating functions, various performance measures like reliabilityindices and long run probabilities have been obtained.展开更多
A prepaid subscriber is allowed to simultaneously implement multiple services in online charging mechanism of IP Multimedia Subsystem (IMS). It is a noteworthy discussion to effectively distribute the limited account ...A prepaid subscriber is allowed to simultaneously implement multiple services in online charging mechanism of IP Multimedia Subsystem (IMS). It is a noteworthy discussion to effectively distribute the limited account resources among concurrent services. An account-sharing algorithm is proposed for multi-services,which introduces resource reclamation and redistribution processes based on the resource reservation of standard specifications and dynamically adjusts them according to the changes of Quality of Service (QoS). Three performance indexes are investigated in the simulation experiments, which are average number of accommodated sessions, average number of completed ses- sions, and average number of iterations per accommodated session. The results show that in the normal QoS level, the three indexes of the proposed algorithm averagely increase by 18.7%, 5.4%, and 3.1% compared with the Prepaid Credit Distribution (PCD) algorithm, and by 2.1%, 1.0%, and 1.8% compared with the Prepaid Credit Reclaim (PCR) algorithm. In the poor QoS level, the performance advantages are greater, which averagely increase by 29.1%, 7.1%, and 2.8% compared with PCD, and by 9.4%, 4.1%, and 3.6% compared with PCR.展开更多
基金This workis sponsored by National"863"High Technology Projects of China (2001AA122021 ,2004AA122320) .
文摘In this paper we propose a novel Dynamic Bandwidth Assignment （DBA） algorithm for Ethernet-based Passive Optical Networks （EPON） which offers multiple kinds of services. To satisfy crucial Quality of Service （QoS） requirement for Time Division Multiplexing （TDM） service and achieve fair and high bandwidth utilization simultaneously, the algorithm integrates periodic, for TDM service, and polling granting for Ethernet service. Detailed simulation shows that the algorithm guarantees carrier-grade QoS for TDM service, high bandwidth utilization and good fairness of bandwidth assignment among Optical Network Units （ONU）.
文摘Larger wireless access networks are required to meet the growing demand for mobile traffic and multimedia services. The use of RoF (Radio over Fiber) technology in combination with millimeter waves is a potential response to the requirements of broadband applications and high capacity networks. In this paper, we proposed a RoF architecture able to provide very high-speed wireless access points up to Gbps considering an indoor and outdoor environment conform to IEEE 802.11ad and IEEE 802.15.3c standard. Optical transmission and radio coverage have been studied by considering the uplink and downlink. System performance has been evaluated in the relation to the Error Vector Magnitude (EVM) for various modulation formats (BPSK, QPSK and 16QAM). Results showed that millimeter wave signals are successfully delivered over a 50 km fiber link and a wireless channel up to 32 m. Data throughput up to 5.28 Gbps has been reached. The proposed architecture can extend the range of applications for wireless communications in association with the unlicensed 60 GHz band with the advantages of better capacity, a wider coverage area and a reduction in the investment cost.
文摘Bulk arrival retrial G-queue with impatient customers and multi-servicessubject to server breakdowns has been analyzed. The system allows the arrival oftwo types of customers: positive customers and negative customers in the system.The negative customers make the server fail if they find the server in busy state,whereas positive customers are served if the server is idle otherwise they join thevirtual pool of customers called orbit. The customers from the retrial orbit try theirchance again for the service. The customers have the option of obtaining more than oneservice. Moreover, the customers are impatient and may renege from the system withprobability (1−r ). The server is sent for repair as soon as it breakdowns;after repair,the service process starts again. Also, the server has the provision to initiate the servicewhen there areN customers accumulated in the system. Using supplementary variablestechnique and generating functions, various performance measures like reliabilityindices and long run probabilities have been obtained.
基金Supported by the National Natural Science Fund for Distinguished Young Scholars (No.60525110)the National 973 Program (No.2007CB307100, No.2007CB 307103)the Development Fund Project for Elec-tronic and Information Industry (Mobile Service and Application System Based on 3G)
文摘A prepaid subscriber is allowed to simultaneously implement multiple services in online charging mechanism of IP Multimedia Subsystem (IMS). It is a noteworthy discussion to effectively distribute the limited account resources among concurrent services. An account-sharing algorithm is proposed for multi-services,which introduces resource reclamation and redistribution processes based on the resource reservation of standard specifications and dynamically adjusts them according to the changes of Quality of Service (QoS). Three performance indexes are investigated in the simulation experiments, which are average number of accommodated sessions, average number of completed ses- sions, and average number of iterations per accommodated session. The results show that in the normal QoS level, the three indexes of the proposed algorithm averagely increase by 18.7%, 5.4%, and 3.1% compared with the Prepaid Credit Distribution (PCD) algorithm, and by 2.1%, 1.0%, and 1.8% compared with the Prepaid Credit Reclaim (PCR) algorithm. In the poor QoS level, the performance advantages are greater, which averagely increase by 29.1%, 7.1%, and 2.8% compared with PCD, and by 9.4%, 4.1%, and 3.6% compared with PCR.
