Physical layer security of underlay cognitive radio using maximal ratio combining

We investigate the secrecy outage performance of maximal ratio combining (MRC) in cognitive radio networks over Rayleigh fading channels. In a single-input multiple-output wiretap system, we consider a secondary user (SU-TX) that transmits confidential messages to another secondary user (SU-RX) equipped with M (M ≥ 1) antennas where the MRC technique is adopted to improve its received signal-to-noise ratio. Meanwhile, an eavesdropper equipped with N (N ≥ 1) antennas adopts the MRC scheme to overhear the information between SU-TX and SU-RX. SU-TX adopts the underlay strategy to guarantee the service quality of the primary user without spectrum sensing. We derive the closed-form expressions for an exact and asymptotic secrecy outage probability.     

Maximizing power saving with state transition overhead for multiple mobile subscriber stations in WiMAX

In the IEEE 802.16e/m standard, three power saving classes (PSCs) are defined to save the energy of a mobile sub-scriber station (MSS). However, how to set the parameters of PSCs to maximize the power saving and guarantee the quality of service is not specified in the standard. Thus, many algorithms were proposed to set the PSCs in IEEE 802.16 networks. However, most of the proposed algorithms consider only the power saving for a single MSS. In the algorithms designed for multiple MSSs, the sleep state, which is set for activation of state transition overhead power, is not considered. The PSC setting for real-time connections in multiple MSSs with consideration of the state transition overhead is studied. The problem is non-deterministic polynomial time hard (NP-hard), and a suboptimal algorithm for the problem is proposed. Simulation results demonstrate that the energy saving of the proposed algorithm is higher than that of state-of-the-art algorithms and approaches the optimum limit.     

A cross-layer approach for partition detection at overlay layer for structured P2P in MANETs

Due to limited radio range and mobility of nodes in mobile ad hoc networks (MANETs), the network partitioning and merging could occur frequently. When structured peer-to-peer (P2P) overlays are running over MANETs, then network partition in the physical network can also cause network partition at the overlay layer. Existing approaches for structured P2P overlay over MANETs do not detect network partition at the overlay layer. This paper proposes a cross-layer approach to detect network partition at the overlay layer for structured P2P overlay over MANETs. Simulation results show that the proposed approach is highly effective and efficient in terms of routing overhead, success ratio and false-negative ratio.     

SOA$$^\mathrm{}$$: a new way to design the decision in SOA—based on the new standard Decision Model and Notation (DMN)

In recent years, Service Oriented Architecture (SOA) technologies are emerging as a powerful vehicle for organizations that need to integrate their applications within and across organizational boundaries. In addition, organizations need to make better decisions more quickly. Moreover, they need to change those decisions immediately to adapt to this increasingly dynamic business environment. It is primarily a question in ensuring the decisional aspect by adopting the SOA as a support architecture. In this paper, we describe a new approach called SOA\(^\mathrm{+d}\) based on a certain number of standards. It is going to be studied on three dimensions: The first is related to the definition of the information system implied in the SOA based on the use case model. The second develops the business dimension which is based on the BPMN (Business Process Modeling Notation). The last dimension addresses the need of decision; we use the new standard decision model and notation (DMN) which is recently approved by Object Management Group (OMG) and considered as a simple notation to specify the decision. Finally, Service Oriented Architecture Modeling Language (SoaML) will be used for design of several services. We also present our meta-model Decisional Model of Service (DMS) to define a new set of concepts necessary for modeling the three levels. Some of them are already known, whereas others are new and are proposed as an element of this work. we illustrate our proposal with a real case study in the Pharmacy Inventory Management.     

Towards a formal study of automatic failure recovery in protocol-based web service composition

In the protocol-based Web service composition, the runtime unavailability of component services may result in a failed execution of the composite. In literature, multiple recovery heuristics have been proposed. This work provides a formal study and focuses on the complexity issues of the recovery problem in the protocol-based Web service composition. A recovery is a process responsible of migrating the failed execution into an alternative execution of the composite that still has the ability to reach a final state. The alternative execution is called a recovery execution. Following failure occurrence, several recovery executions may be available. The problem of finding the best recovery execution(s) is called the recovery problem. Several criteria may be used to determine the best recovery execution(s). In this work, we define the best recovery execution as the one which is attainable from the failed execution with a maximal number of invisible compensations with respect to the client. We assume that all transitions are compensatable. For a given recovery execution, we prove that the decision problem associated with computing the number of invisibly compensated transitions is NP-complete, and thus, we conclude that deciding of the best recovery execution is in \(\Sigma _2^P\).     

Top-<Emphasis Type="Italic">k</Emphasis> probabilistic prevalent co-location mining in spatially uncertain data sets

A co-location pattern is a set of spatial features whose instances frequently appear in a spatial neighborhood. This paper efficiently mines the top-k probabilistic prevalent co-locations over spatially uncertain data sets and makes the following contributions: 1) the concept of the top-k probabilistic prevalent co-locations based on a possible world model is defined; 2) a framework for discovering the top-k probabilistic prevalent co-locations is set up; 3) a matrix method is proposed to improve the computation of the prevalence probability of a top-k candidate, and two pruning rules of the matrix block are given to accelerate the search for exact solutions; 4) a polynomial matrix is developed to further speed up the top-k candidate refinement process; 5) an approximate algorithm with compensation factor is introduced so that relatively large quantity of data can be processed quickly. The efficiency of our proposed algorithms as well as the accuracy of the approximation algorithms is evaluated with an extensive set of experiments using both synthetic and real uncertain data sets.     

Distinct element method analysis of a retaining wall using a steel frame and fill materials

A technique is developed to clearly establish the shear resistance of a cellular structure, retaining wall composed of a steel frame and fill materials with both continuous and discontinuous characteristics. To overcome the limitation of the existing analysis approach based on continuum mechanics, in which the shear behavior and interaction between the frames and fill material of this type of structure are difficult to describe, this paper introduces displacement incremental analysis into the distinct element method. The results obtained by using the proposed approach are compared with experimental results to verify its accuracy. The results show an internal friction angle of fill materials and overburdening load are major factor determining the shear resistance of a retaining wall with a cellular structure type. From the results of the parametric study on the shear behavior of this type of structure, this paper also proposes a shear resistance moment-shear displacement formula for designing a retaining wall with a cellular structure type.     

Mesh-free canonical tensor products for six-dimensional density matrix: computation of kinetic energy

The computation of a six-dimensional density matrix is the crucial step for the evaluation of kinetic energy in electronic structure calculations. For molecules with heavy nuclei, one has to consider a very refined mesh in order to deal with the nuclear cusps. This leads to high computational time and needs huge memory for the computation of the density matrix. To reduce the computational complexity and avoid discretization errors in the approximation, we use mesh-free canonical tensor products in electronic structure calculations. In this paper, we approximate the six-dimensional density matrix in an efficient way and then compute the kinetic energy. Accuracy is examined by comparing our computed kinetic energy with the exact computation of the kinetic energy.