WDM-Pulse-position modulation technique in SI-POF transmission is proposed to overcome the limitation from mode dispersion. It can expand the flat transmission bandwidth to 80MHz with 100m-fiber length.
Recently, network coding has been applied to the loss recovery of reliable broadcast transmission in wireless networks. Since it was proved that fi nding the optimal set of lost packets for XOR-ing is a complex NP-com...Recently, network coding has been applied to the loss recovery of reliable broadcast transmission in wireless networks. Since it was proved that fi nding the optimal set of lost packets for XOR-ing is a complex NP-complete problem, the available time-based retransmission scheme and its enhanced retransmission scheme have exponential computational complexity and thus are not scalable to large networks. In this paper, we present an efficient heuristic scheme based on hypergraph coloring and also its enhanced heuristic scheme to improve the transmission efficiency. Basically, our proposed schemes fi rst create a hypergraph according to the packet-loss matrix. Then our schemes solve the problem of generating XORed packets by coloring the edges of hypergraph. Extensive simulation results demonstrate that, the heuristic scheme based on hypergraph coloring and its enhanced scheme can achieve almost the same transmission efficiency as the available ones, but have much lower computational complexity, which is very important for the wireless devices without high computation capacity.展开更多
The dispensing mechanism of active code is the key technology in activenetwork. Conventional capsule and programmable switch approaches have their own shortcomings. DCCANmechanism presented in this paper overcomes the...The dispensing mechanism of active code is the key technology in activenetwork. Conventional capsule and programmable switch approaches have their own shortcomings. DCCANmechanism presented in this paper overcomes their shortcomings. In this paper, capsule andprogrammable switch, approaches are introduced and their shortcomings are analyzed. The principle ofDCCAN mechanism is described. The theoretical analyses in transmission bandwidth based on DCCANmechanism and capsule approach are described, and key factors which affect the transmissionbandwidth based on DCCAN mechanism are also discussed. At the same time, the theoretical analyses inlatency based on DCCAN mechanism and capsule approach are described. The using condition of DCCANmechanism is also discussed.展开更多
In an active network, users can insert customized active codes into activenodes, to execute. Thus it needs more resources than those required by conventional networks, andthese resources must be effectively monitored ...In an active network, users can insert customized active codes into activenodes, to execute. Thus it needs more resources than those required by conventional networks, andthese resources must be effectively monitored and managed. Management policies in existing OSs aretoo complicated to apply to simple active packets. In this paper, we present new resourcesmanagement policies that are mainly adoped to manage CPU, storage and transmission bandwidth.Namely, we use SPF algorithm to schedule and process active packets, and import an interval queuemethod to allocate transmission bandwidth, and use feedback mechanism to control congestion . At thesame time, we design some experiments on prototype systems with and without resources managementpolicies respectively. The experiments results show that management policies presented by us caneffectively manage resources in active nodes and can improve the performance of active networks.展开更多
文摘WDM-Pulse-position modulation technique in SI-POF transmission is proposed to overcome the limitation from mode dispersion. It can expand the flat transmission bandwidth to 80MHz with 100m-fiber length.
基金supported by the National Natural Science Foundation of China (60502046, 60573034)863 Foundation of China (2007AA01Z215)
文摘Recently, network coding has been applied to the loss recovery of reliable broadcast transmission in wireless networks. Since it was proved that fi nding the optimal set of lost packets for XOR-ing is a complex NP-complete problem, the available time-based retransmission scheme and its enhanced retransmission scheme have exponential computational complexity and thus are not scalable to large networks. In this paper, we present an efficient heuristic scheme based on hypergraph coloring and also its enhanced heuristic scheme to improve the transmission efficiency. Basically, our proposed schemes fi rst create a hypergraph according to the packet-loss matrix. Then our schemes solve the problem of generating XORed packets by coloring the edges of hypergraph. Extensive simulation results demonstrate that, the heuristic scheme based on hypergraph coloring and its enhanced scheme can achieve almost the same transmission efficiency as the available ones, but have much lower computational complexity, which is very important for the wireless devices without high computation capacity.
文摘The dispensing mechanism of active code is the key technology in activenetwork. Conventional capsule and programmable switch approaches have their own shortcomings. DCCANmechanism presented in this paper overcomes their shortcomings. In this paper, capsule andprogrammable switch, approaches are introduced and their shortcomings are analyzed. The principle ofDCCAN mechanism is described. The theoretical analyses in transmission bandwidth based on DCCANmechanism and capsule approach are described, and key factors which affect the transmissionbandwidth based on DCCAN mechanism are also discussed. At the same time, the theoretical analyses inlatency based on DCCAN mechanism and capsule approach are described. The using condition of DCCANmechanism is also discussed.
文摘In an active network, users can insert customized active codes into activenodes, to execute. Thus it needs more resources than those required by conventional networks, andthese resources must be effectively monitored and managed. Management policies in existing OSs aretoo complicated to apply to simple active packets. In this paper, we present new resourcesmanagement policies that are mainly adoped to manage CPU, storage and transmission bandwidth.Namely, we use SPF algorithm to schedule and process active packets, and import an interval queuemethod to allocate transmission bandwidth, and use feedback mechanism to control congestion . At thesame time, we design some experiments on prototype systems with and without resources managementpolicies respectively. The experiments results show that management policies presented by us caneffectively manage resources in active nodes and can improve the performance of active networks.