Current Issue : July - September Volume : 2014 Issue Number : 3 Articles : 6 Articles
The paper is devoted to modeling and optimization\nof reliable wireless mesh networks that employ directional\nantennas. We introduce two mixed-integer programming\nformulations that allow to simultaneously characterize\nrouting patterns and transmission schedules. The first model\nallows for maximizing the minimal flow in a network. The\nsecond model involves reliability constraints and aims at\nminimizing the number of used directional antennas. In both\ncases locations of mesh routers are known. However, the\nnumber of installed radio interfaces and their directions are\nsubject to optimization. We discuss a way of solving a cost\nminimization problem based on the introduced characterization,\nand present an extensive numerical study that illustrates\nthe efficiency of the solution algorithm. We also provide an\nalgorithm capable of verifying feasibility of obtained solutions.\nMoreover, in rare cases of failed verification, the algorithm\nprovides additional constraints that should be added to\nthe problem....
Assurance networks are designed to realize trustable\nInternet-Of-Things including terminal devices/infrastructure\nservice applications for new generation networks.\nTo construct assurance networks, it is necessary to evaluate\nthem quantitatively. In this paper, we provide one of case\nstudies to evaluate them quantitatively. In mobile ad hoc networks\n(MANETs), the network environments change over\ntime due to the movement of nodes, the battery level of\nnodes, and so on. Assurance networks must maintain high\nperformance even when such diverse changes of the network\nenvironments occur in the widely applicable domain. And if\ntheir performance degrades, they must early recover from\nthe changes. So far, we have proposed a routing method for\nMANETs, called Route-Split Routing (RSR). RSR can suppress\nescalation of control packets in large scale MANETs.\nHowever, with RSR, drawbacks occur when some nodes exhaust\ntheir batteries. In this paper, we propose a sustainable\nroute-split routing scheme to improve assurance by adapting\nnode faults due to battery exhaustion for MANETs. To\nevaluate the assurance of the proposed method, we have implemented\nit with a simulator and have conducted simulation\nexperiments. The results indicate that the proposed method\ncan maintain high throughput when some nodes experience\nvarious levels of battery power and power consumption and\neven when some nodes die simultaneously....
We review recent work on all-fiber (long-period fiber grating) devices for optical pulse shaping, particularly flat-top pulse\ngeneration, down to the subpicosecond range and their application for nonlinear switching (demultiplexing) of optical timedivision\nmultiplexed (OTDM) data signals in fiber-optic telecommunication links operating up to 640 Gbit/s. Experiments are\npresented demonstrating error-free 640-to-10 Gbit/s demultiplexing of the 64 tributary channels using the generated flat-top\npulses for temporal gating in a Kerr-effect-based nonlinear optical loop mirror. The use of flat-top pulses has critical benefits\nin the demultiplexing process, including a significantly increased timing-jitter tolerance (up to ~500 fs, i.e., 30% of the bit period)\nand the associated improvement in the bit-error-rate performance (e.g., with a sensitivity increase of up to ~13 dB as compared\nwith the use of Gaussian-like gating pulses). Long-period fiber grating pulse shapers with reduced polarization dependence are\nfabricated and successfully used for polarization-independent 640-to-10 Gbit/s demultiplexing experiments....
In this paper, we investigate the problem of survivable\nall-optical routing in WDM networks with physical\nimpairments. One of the recent key issues in survivable optical\nnetwork design refers to maximization of the ratio of\nrouteable demands while keeping the overall network cost\nlow. In WDM networks, this goal can be achieved by routing\nas many demands in all-optical way as possible. Based\non the latest technical trends driven by deployment costs,\ntechnical constraints, and backward compatibility, this will\nnot mean that all demands will be routed in all-optical way\nin the near future.\nNowadays, operators are mostly willing to dedicate only\na given ratio of their power budget to all-optical routing.\nThis in turn implies a new problem to be solved: operators\nhave to find a way to select demands that should be routed\nin all-optical way and which should not. The problem gets\neven more complicated, if we add demand protection issues.\nIn this paper, we introduce and evaluate methods able to\nmaximize the number of demands routed with protection in\nall-optical way in capacity-constrained networks with limitations\non path lengths according to physical impairments....
In this paper, the filterless optical network concept\nis presented and explored through a number of filterless\nsolution examples. In the first part, the filterless network\nconcept is presented and analyzed through a comparative\ncase study. In the second part, the filterless network\ndesign problem is defined and a filterless network design\ntool based on metaheuristics is presented. In the third part of\nthis presentation, filterless network solutions are proposed\nfor a number of core network topologies and compared to\nactive photonic network solutions from the point of view of\ncost and performance. The results show that cost-effective\nfilterless solutions can be found for different network sizes\nand topologies. The results of a comparative study show that\nfilterless networks represent a cost-effective and reliable alternative\nto active optical switching network solutions....
Realization of transmitter and receiver architecture for different uplink and downlink channel for LTE is the major research work being carried out today. There are three control channels available in LTE for downlink. The downlink control channels are PDCCH, PCFICH and PHICH. Physical control format indicator channel (PCFICH) is one among the downlink physical control channel which carries number of OFDM symbols used by the PDCCH. This information carried by the PCFICH channel is denoted as control format indicator (CFI). The CFI is the first information received by the UE and so is important for the LTE performance. In this paper, the realization of transmitter architecture for PCFICH is done using FPGA....
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