/pdf/a-break-in-the-clouds-towards-a-cloud-definition-svovsw1r5a.pdf

A Break in the Clouds: Towards a Cloud Definition

The Bootstrap and Edgeworth Expansion

IEEE transactions on computer-aided design of integrated circuits and systems : a publication of the IEEE Circuits and Systems Society

To support bursty traffic on the Internet (and especially WWW) efficiently, optical burst switching (OBS) is proposed as a way to streamline both protocols and hardware in building the future gener...

Optical burst switching (OBS) - a new paradigm for an optical Internet

Time series analysis and its applications

Achieving fast and precise failure localization has long been a highly desired feature in all-optical mesh networks. M-trail (monitoring trail) has been proposed as the most general monitoring structure for achieving unambiguous failure localization (UFL) of any single link failure while effectively reducing the amount of alarm signals flooded in the networks. However, it is critical to come up with a fast and intelligent m-trail design approach for minimizing the number of m-trails and the totally consumed bandwidth, which ubiquitously determines the length of alarm code and bandwidth overhead for the M-trail deployment, respectively. In this paper, the m-trail design problem is investigated. To gain deeper understanding of the problem, we firstly conduct a bound analysis on the minimum length of alarm code required for UFL. Then, a novel algorithm based on random code assignment (RCA) and random code swapping (RCS) is developed for solving the m-trail design problem. The algorithm prototype can be found in. The algorithm is verified by comparing with an integer linear program (ILP), and the results demonstrate its superiority in minimizing the fault management cost and bandwidth consumption while achieving significant reduction in computation time. To investigate the impact of topology diversity, extensive simulation is conducted on thousands of random network topologies with systematically increased network connectivity. Lastly, we provide abundant discussions and interesting conclusive remarks that position our discoveries.

/pdf/on-monitoring-and-failure-localization-in-mesh-all-optical-4s3fyw4gfr.pdf

On Monitoring and Failure Localization in Mesh All-Optical Networks

A monitoring cycle (m-cycle) is a preconfigured optical loop-back connection of supervisory wavelengths with a dedicated monitor. In an all-optical network (AON), if a link fails, the supervisory optical signals in a set of m-cycles covering this link will be disrupted. The link failure can be localized using the alarm code generated by the corresponding monitors. In this paper, we first formulate an optimal integer linear program (ILP) for m-cycle design. The objective is to minimize the monitoring cost which consists of the monitor cost and the bandwidth cost (i.e., supervisory wavelength-links). To reduce the ILP running time, a heuristic ILP is also formulated. To the best of our survey, this is the first effort in m-cycle design using ILP, and it leads to two contributions: 1) nonsimple m-cycles are considered; and 2) an efficient tradeoff is allowed between the monitor cost and the bandwidth cost. Numerical results show that our ILP-based approach outperforms the existing m-cycle design algorithms with a significant performance gain.

/pdf/monitoring-cycle-design-for-fast-link-failure-localization-4h3v2plr3h.pdf

Monitoring Cycle Design for Fast Link Failure Localization in All-Optical Networks

We consider an optical layer monitoring mechanism for fast link failure localization in all-optical wavelength-division-multiplexing (WDM) mesh networks. A novel framework of all-optical monitoring, called monitoring trail (m-trail), is introduced. It differs from the existing monitoring cycle (m-cycle) method by removing the cycle constraint. As a result, m-trail provides a general all-optical monitoring structure, which includes simple, nonsimple m-cycles, and open trails as special cases. Based on an in-depth theoretical analysis, we formulate an efficient integer linear program (ILP) for m-trail design to achieve unambiguous localization of each link failure. The objective is to minimize the monitoring cost (i.e., monitor cost plus bandwidth cost) of all m-trails in the solution. Numerical results show that the proposed m-trail scheme significantly outperforms its m-cycle-based counterpart.

/pdf/monitoring-trail-on-fast-link-failure-localization-in-all-3u85y9ait9.pdf

Monitoring Trail: On Fast Link Failure Localization in All-Optical WDM Mesh Networks

The concept of p-cycle (preconfigured protection cycle) allows fast and efficient span protection in wavelength division multiplexing (WDM) mesh networks. To design p-cycles for a given network, conventional algorithms need to enumerate cycles in the network to form a candidate set, and then use an integer linear program (ILP) to find a set of p -cycles from the candidate set. Because the size of the candidate set increases exponentially with the network size, candidate cycle enumeration introduces a huge number of ILP variables and slows down the optimization process. In this paper, we focus on p-cycle design without candidate cycle enumeration. Three ILPs for solving the problem of spare capacity placement (SCP) are first formulated. They are based on recursion, flow conservation, and cycle exclusion, respectively. We show that the number of ILP variables/constraints in our cycle exclusion approach only increases linearly with the network size. Then, based on cycle exclusion, we formulate an ILP for solving the joint capacity placement (JCP) problem. Numerical results show that our ILPs are very efficient in generating p -cycle solutions.

/pdf/ilp-formulations-for-p-cycle-design-without-candidate-cycle-38jnl4df9a.pdf

ILP formulations for p-cycle design without candidate cycle enumeration

We study energy detection based spectrum sensing of SU (Secondary User) in cognitive radios. Due to the time varying nature of wireless channels and PU (Primary User) activities, the SINR (Signal to Interference plus Noise Ratio) at the SU receiver changes from slot to slot in a time-slotted system. Unlike the conventional energy detector which uses a fixed energy threshold for spectrum sensing, we dynamically adjust the energy threshold according to the SINR. By limiting the average interference to the PU within a target level, the objective is to maximize the SU's average rate using an optimized policy function, which formulates the threshold as a linear increasing function of the SINR. Simulation results show that the SU's average rate can be significantly improved using the optimized function for dynamic threshold control.

Bin Wu

Papers

On Monitoring and Failure Localization in Mesh All-Optical Networks

Monitoring Cycle Design for Fast Link Failure Localization in All-Optical Networks

Monitoring Trail: On Fast Link Failure Localization in All-Optical WDM Mesh Networks

ILP formulations for p-cycle design without candidate cycle enumeration

Adaptive Threshold Control for Energy Detection Based Spectrum Sensing in Cognitive Radios