The Experts below are selected from a list of 20394 Experts worldwide ranked by ideXlab platform
P Castoldi - One of the best experts on this subject based on the ideXlab platform.
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routing code and Spectrum assignment subcarrier spacing and filter configuration in elastic optical networks invited
IEEE\ OSA Journal of Optical Communications and Networking, 2015Co-Authors: N Sambo, G Meloni, F Cugini, Francesco Fresi, A Derrico, L Poti, Paola Iovanna, P CastoldiAbstract:Abstract—In elastic optical networks (EONs), the modulation format can be configured to guarantee the required optical reach with efficient Spectrum Utilization. For this reason, the literature related to EONs has treated the problem of routing and Spectrum assignment together with the problem of modulation format assignment. Recently, in addition to modulation format, code adaptation has also been successfully demonstrated to provide adequate Spectrum Utilization given a target optical reach. This paper presents the concept of routing, code, and Spectrum assignment (RCSA) for EONs. We propose the optimization of multiple transmission parameters including code, subcarrier spacing, and filters’ passband to avoid detrimental filtering effects. Measurements are carried out in an EON testbed to identify the relation between transmission parameters and the number of traversed filters and optical reach. Then, the measurements are used as inputs in simulations to test RCSA. The simulations show that code adaptation reduces blocking probability with respect to format adaptation. Another interesting result shows that the use of several possibilities for the transmission parameter setting may induce high Spectrum fragmentation.
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trading regeneration and Spectrum Utilization in code rate adaptive flexi grid networks
Journal of Lightwave Technology, 2014Co-Authors: Isabella Cerutti, Francesca Martinelli, N Sambo, Filippo Cugini, P CastoldiAbstract:Introduced to improve the spectral efficiency, time-frequency packing technique allows the exploitation of different code rates, leading to different levels of spectral Utilization and all-optical reach. To ensure quality of transmission of the optical signal, opto-electronic regeneration must be used to propagate the transmission beyond the maximum optical reach and can inherently offer conversion of Spectrum and code rate. In this way, multiple code rates can be enabled in optical networks, leading to a flexible design in which Spectrum Utilization and regeneration can be properly optimized and traded. This paper addresses for the first time the joint problem of selecting the code rate, the regeneration nodes, the Spectrum allocation and the route for the requested lightpaths in an optical network with a flexi-grid. A genetic algorithm is proposed that balances the contrasting objectives of minimizing the regeneration nodes and the Spectrum Utilization. Results show that when regeneration nodes are minimized, code-rate adaptation is able to reduce the regeneration nodes as well as the Spectrum Utilization with respect to rate-fixed optical networks. In general, a balance of the two contrasting objectives is preferred to achieve a low resource Utilization.
Yuguang Fang - One of the best experts on this subject based on the ideXlab platform.
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coolest path Spectrum mobility aware routing metrics in cognitive ad hoc networks
International Conference on Distributed Computing Systems, 2011Co-Authors: Xiaoxia Huang, Yuguang FangAbstract:Cognitive Radio (CR) emerges as a promising solution to current unbalanced Spectrum Utilization. The cognitive ad hoc network can take advantage of dynamic Spectrum access and Spectrum diversity over wide Spectrum. It could achieve higher network capacity compared to traditional ad hoc networks, thus supporting bandwidth-demanding applications. A cognitive radio operates over wide Spectrum with unpredictable channel availability. Moreover, the transmission opportunity of a cognitive node is not guaranteed due to the presence of primary users (PUs). These two unique features define new routing problems in cognitive ad hoc networks. To better characterize the unique features of cognitive radio networks, we propose new routing metrics, including accumulated Spectrum temperature, highest Spectrum temperature, and mixed Spectrum temperature to account for the time-varying Spectrum availability. The proposed metrics favor the "coolest'' path, or the path with the most balanced and/or the lowest Spectrum Utilization by the primary users. We also study the computational complexity of the routing algorithm in cognitive ad hoc networks. Experiment results on our USRP-2 testbed show that the proposed metrics are capable of capturing the fluctuation of Spectrum availability and suitable for cognitive ad hoc networks.
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joint routing and link scheduling for cognitive radio networks under uncertain Spectrum supply
International Conference on Computer Communications, 2011Co-Authors: Chi Zhang, Yuguang FangAbstract:The essential impediment to apply cognitive radio (CR) technology for Spectrum Utilization improvement lies in the uncertainty of licensed Spectrum supply. In this paper, we investigate the joint routing and link scheduling problem of multi-hop CR networks under uncertain Spectrum supply. We model the vacancy of licensed bands with a series of random variables, and introduce corresponding scheduling constraints and flow routing constraints for such a network. From a CR network planner/operator's point of view, we characterize the network with a pair of (α; β) parameters, and present a mathematical formulation with the goal of minimizing the required network-wide Spectrum resource at the (α; β) level. Given that (α; β) is specified, we derive a lower bound for the optimization problem and develop a threshold based coarse-grained fixing algorithm for a feasible solution. Simulation results show that i) for any (α; β) level, the proposed algorithm provides a near-optimal solution to the formulated NP-hard problem; ii) the (α; β) based solution is better than expected bandwidth based one in terms of blocking ratio as well as Spectrum Utilization in CR networks.
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Purging the Back-Room Dealing: Secure Spectrum Auction Leveraging Paillier Cryptosystem
IEEE Journal on Selected Areas in Communications, 2011Co-Authors: Yuguang FangAbstract:Microeconomics-inspired Spectrum auctions can dramatically improve the Spectrum Utilization for wireless networks to satisfy the ever increasing service demands. However, the back-room dealing (i.e., the frauds of the insincere auctioneer and the bid-rigging between the greedy bidders and the auctioneer) poses significant security challenges, and fails all existing secure auction designs to allocate Spectrum bands when considering the frequency reuse in wireless networks. In this paper, we propose THEMIS, a secure Spectrum auction leveraging the Paillier cryptosystem to prevent the frauds of the insincere auctioneer as well as the bid-rigging between the bidders and the auctioneer. THEMIS incorporates cryptographic technique into Spectrum auction to address the challenges of back-room dealing. It computes and reveals the results of Spectrum auction while the actual bidding values of bidders are kept confidential. THEMIS also provides a novel procedure for implementing secure Spectrum auction under interference constraints. It has been shown that THEMIS can effectively purge the back-room dealing with limited communication and computational complexity, and achieve similar performance compared with existing insecure Spectrum auction designs in terms of Spectrum Utilization, revenue of the auctioneer, and bidders' satisfaction.
Jie Zhang - One of the best experts on this subject based on the ideXlab platform.
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survivable fragmentation aware Spectrum allocation approaches in software defined elastic optical networks
2016 Asia Communications and Photonics Conference (ACP), 2016Co-Authors: Bowen Chen, Yongli Zhao, Xiaoling Wang, Jie ZhangAbstract:We develop two survivable fragmentation-aware Spectrum allocation approaches to improve Spectrum Utilization in software-defined elastic optical networks. Simulation results show that the proposed Spectrum allocation approaches reduce blocking probability compared to the first-fit Spectrum allocation approach.
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A Novel Definition of Spectrum Holes for Improved Spectrum Utilization Efficiency
Ksii Transactions on Internet and Information Systems, 2014Co-Authors: Qi Zhou, Hui Dai, Jie ZhangAbstract:Improving Spectrum Utilization efficiency is a fundamental goal of dynamic Spectrum access technology. The definition of Spectrum holes determines how to detect and exploit them. Current definitions of Spectrum holes are ineffective in exploiting spatial-temporal Spectrum holes. In this paper, a novel definition of Spectrum holes is proposed, in which throughput loss indicates the impact of secondary users on primary users. The definition specifies Spectrum holes, unifies the impact of secondary users on primary users and is effective exploiting spatial-temporal Spectrum holes. Theoretical analysis and numerical simulations show that the new definition proposed in this paper significantly improves the Spectrum Utilization efficiency.
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experimental demonstration of hierarchical controlled software defined networking hc sdn deployed with pce protocol for large scale multi domain flexi grid optical networks
Asia Communications and Photonics Conference 2013 (2013) paper AW4I.4, 2013Co-Authors: Yongli Zhao, Jie Zhang, Lingnan Gao, Huibin ZhangAbstract:A large scale multi-domain flexi-grid optical networks testbed with 200 nodes is experimental demonstrated based on hierarchical controlled software defined networking (HC-SDN), which is deployed with PCE protocol. Experimental results including lightpath provisioning latency, blocking probability, and Spectrum Utilization are given and analyzed.
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minimum Spectrum block consumption for shared path protection with joint failure probability in flexible bandwidth optical networks
Optical Fiber Communication Conference, 2013Co-Authors: Bowen Chen, Yongli Zhao, Jie Zhang, Shanguo Huang, Wanyi GuAbstract:We propose a minimum-free-Spectrum-block-consumption algorithm (MFSB) for shared-path protection with joint failure probability requirements in flexible bandwidth optical networks. Compared with conventional algorithms, MFSB efficiently decreases the Spectrum block consumption and achieves higher Spectrum Utilization.
Janne Lehtomaki - One of the best experts on this subject based on the ideXlab platform.
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optimum welch fft segment size for duty cycle estimation in Spectrum awareness system
Wireless Communications and Networking Conference, 2015Co-Authors: Hiroki Iwata, Kenta Umebayashi, Samuli Tiiro, Yasuo Suzuki, Janne LehtomakiAbstract:In order to realize practical dynamic Spectrum access (DSA), implementing Spectrum sensing with reasonably low cost is very challenging due to the required detection accuracy and quickness. For this issue, we have introduced an extended DSA, smart Spectrum access (SSA), where any useful information in terms of Spectrum Utilization, such as statistics regarding Spectrum Utilization, is used not only for accomplishing the requirements of Spectrum sensing but also for enhancing the performance of the DSA. In this approach, obtaining the statistics of the Spectrum Utilization is an important issue for which we have developed a Spectrum awareness system prototype. One issue in the Spectrum awareness is the Welch FFT segment size design which is used for Spectrum analysis. This issue involves a trade-off between the Spectrum usage detection accuracy and available frequency resolution. For this issue, we derive an optimum segment size based on analysis and show that the optimum segment size depends on signal-to-measurement bandwidth ratio and duty cycle. The optimum segment size derived by the analysis is validated with numerical simulation and experimental results.
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development of a measurement system for Spectrum awareness
1st International Conference on 5G for Ubiquitous Connectivity, 2014Co-Authors: Kenta Umebayashi, Samuli Tiiro, Janne LehtomakiAbstract:Dynamic Spectrum access (DSA) is an attractive approach to solve the Spectrum scarcity problem. Among DSA techniques, Spectrum overlay is an approach where the Spectrum licensed to a primary user (PU) is shared by a secondary user (SU) while protecting the PU from the interference caused by SU Spectrum reuse. In the case where PU traffic is dynamic, Spectrum sharing is difficult as satisfying requirements of Spectrum sensing, the challenging accuracy, quickness and low cost requirements in practice, is difficult. For this issue, we propose a new concept of smart Spectrum access (SSA) where useful information related to PU Spectrum Utilization is used to achieve not only the above requirements but also more efficient Spectrum Utilization. We also show an approach to realize practical SSA and it consists of a Spectrum awareness system (SAS) and a dynamic Spectrum access system (DSAS). The main role of the SAS is to provide useful information to the DSAS. The information can be obtained by the SAS through Spectrum Utilization measurement and analysis of the measurement data. In this paper, we present a framework for smart Spectrum access and discuss the challenges of this approach. In addition, we report some of the experimental results related to SAS.
Guangming Tan - One of the best experts on this subject based on the ideXlab platform.
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routing and Spectrum allocation for time varying traffic by artificial bee colony algorithm in elastic optical networks
Ubiquitous Computing, 2018Co-Authors: Guojun Yuan, Zhan Wang, Guangming TanAbstract:Elastic optical networks are considered to be a promising technology in high-speed network interconnections. In order to address the time-varying routing and Spectrum allocation problem in elastic optical networks, we propose a algotithm by artificial bee colony algorithm considering the time varying traffic (ABC-TV). The objective of the proposed ABC–TV algorithm is to minimize both the network Spectrum Utilization and the average path length criterions on the effect of benefis by sharing of Spectrum slots among Spectrumadjacent connections. The algorithm is simulated in different networks (NSFNET and EON). The results reveal that the algorithm improves the Spectrum Utilization and minimizes the number of the used frequency slots compared to other considered approaches in elastic optical networks.
