Location management in object-based distributed computing

Mobile agents are processes that can be dispatched from source computer and be transported to remote servers for execution, have been widely argued to be an important enabling technology for future systems. Location management is a necessity for locating mobile agents in a network of mobile agent hosts for controlling, monitoring and communication during processing and it still represents an open research issue. The cost of location management strategies mainly depends on the cost of search and update. We concentrated on reducing the cost of update and improving the speed of processing of the agents. We proposed a location management technique applicable for multi-region environment in which mobile agent did not update its location at every migration. The technique named as Broadcasting with Search by Path Chase (BSPC). We used the tool time Petri net analyzer TINA to model, analyze and to simulate BSPC. We found that the BSPC behaves as expected and free from any deadlock. We measured the efficiency of BSPC and compared with some existing location management techniques by parametric evaluation. BSPC provided better scalability, location updating availability and interaction fault rate with theoretical considerations of network usage and network fault rate. It gave its best performance for applications of low CMR and having high migration rate of mobile agents within birth region.

Some observations on using meta-heuristics for efficient location management in mobile computing networks

Mobility management is an important aspect in LEO systems. In terrestrial wireless networks, the movement of the user triggers location updating and determines the paging scheme, while in LEO satellite systems, location updating and paging is mainly based on the movement of satellites. Terrestrial location management techniques must be altered to fit LEO systems. The paper introduces a modified movement-based location update and paging scheme in LEO networks. We propose the meta-cell concept, which includes two spot-beams of one satellite. First, we present a location management scheme based on the architecture with a meta-cell location area. Then, an analytical model is applied to formulate the cost of location updating and location paging for the movement and meta-cell based dynamic location update scheme. The comparison of performance between the meta-cell architecture method and the conventional signal-spot-cell architecture method is provided to demonstrate the cost-effectiveness and robustness of the proposed scheme under various parameters. To reduce the impact of meta-cell architecture on location paging cost, we present a forced location update strategy which is used in the case that the meta-cell includes two spot-beams from different satellites.

Location management techniques for mobile systems

Parallel and distributed computing has been the basis to many emerging areas, such as smart networks, cloud computing, big data analysis, and blockchain technology. Without the development of parallel and distributed computing technologies and various types of systems, it is not possible to meet the requirement on efficiency, accuracy, scalability, and reliability for various critical applications that support our modern economy and society. While parallel and distributed computing played a vital role in modern science, engineering, biology, medicine, pharmacy, astronomy, geology, and archaeology, its application has also been extended to business, finance, economics, management, government, and defense, covering all aspects of our modern society and life. Furthermore, parallel and distributed computing has emerged in recent advances of many hotspot research directions including artificial intelligence, machine learning, Internet of Things, bioinformatics, digital medicine, cybersecurity, and social computing, resulting in numerous ground-breading discoveries that are changing our society and life.

A bottom-up approach to parallel anisotropic mesh generation is presented by building a mesh generator starting from the basic operations of vertex insertion and Delaunay triangles. Applications focusing on high-lift design or dynamic stall, or numerical methods and modeling test cases, still focus on two-dimensional domains. This automated parallel mesh generation approach can generate high-fidelity unstructured meshes with anisotropic boundary layers for use in the computational fluid dynamics field. The anisotropy requirement adds a level of complexity to a parallel meshing algorithm by making computation depend on the local alignment of elements, which in turn is dictated by geometric boundaries and the density functions— one-dimensional spacing functions generated from an exponential distribution. This approach yields computational savings in mesh generation and flow solution through well-shaped anisotropic triangles instead of isotropic triangles. The validity of the meshes is shown through solution characteristic comparisons to verified reference solutions. A 79% parallel weak scaling efficiency on 1,024 distributed memory nodes, and a 72% parallel efficiency over the fastest sequential isotropic mesh generator on 512 distributed memory nodes, is shown through numerical experiments.

Distributed parallel Delaunay mesh generation

A template for developing next generation parallel Delaunay refinement methods

In the phase-field simulation of dendrite growth during the solidification of an alloy, the computational cost becomes extremely high when the diffusion length is significantly larger than the curvature radius of a dendrite tip. In such cases, the adaptive mesh refinement (AMR) method is effective for improving the computational performance. In this study, we perform a three-dimensional dendrite growth phase-field simulation in which AMR is implemented via parallel computing using multiple graphics processing units (GPUs), which provide high parallel computation performance. In the parallel GPU computation, we apply dynamic load balancing to parallel computing to equalize the computational cost per GPU. The accuracy of an AMR refinement condition is confirmed through the single-GPU computations of columnar dendrite growth during the directional solidification of a binary alloy. Next, we evaluate the efficiency of dynamic load balancing by performing multiple-GPU parallel computations for three different directional solidification simulations using a moving frame algorithm. Finally, weak scaling tests are performed to confirm the parallel efficiency of the developed code.

This work presents a mobile location management technique based on the clustering. This technique can be implemented on next generation mobile networks by exp loiting the data available on the users (age, function, address, workplace… etc), existing infrastructure (roads, location of base stations… etc) and the users' displacements history The simu lations are carried out using a realistic model of movements. The results show that our strategy requires a min imu m number of location messages compared to the static and dynamic location management techniques.

Increasing demand for wireless mobile communications, coupled with limited network resources, has motivated investigation into alternative efficient mobility management solutions. We consider wireless PCS call setup protocols. We propose a lightweight location lookup protocol, which significantly reduces the network signaling and setup delay during call setup. As an alternative, we consider a reverse connection setup protocol that also performs efficient call setup, while minimizing the cost of failed call attempts. The two protocols have different advantages, in particular when combined with location management techniques including HLR/VLR, HLR/VLR with partial replication, and HLR/VLR with caching. We study the combinations of call setup protocols with location management techniques and compare their performance to find the most efficient call setup schemes. Both analytical and simulation results are presented.

Polygonal finite element provides a great flexibility in mesh generation of crack propagation problems where the topology of the domain changes significantly. However, the control of the discretization error in such problems is a main concern. In this paper, a polygonal-FEM is presented in modeling of crack propagation problems via an automatic adaptive mesh refinement procedure. The adaptive mesh refinement is accomplished based on the Zienkiewicz–Zhu error estimator in conjunction with a weighted SPR technique. Adaptive mesh refinement is employed in some steps for reduction of the discretization error and not for tracking the crack. In the steps that no adaptive mesh refinement is required, local modifications are applied on the mesh to prevent poor polygonal element shapes. Finally, several numerical examples are analyzed to demonstrate the efficiency, accuracy and robustness of the proposed computational algorithm in crack propagation problems.

Due to the anticipated increase in user demand and limited radio resources, efficient location management techniques are desired in future personal communication systems (PCS). The key elements of location management are paging and location registration/updating. This work shows that if intelligence is added to the sequential paging scheme in the form of speed and the most recent interaction area of a portable station (PS), then the cost of location management can be reduced substantially. It is shown that if the PS receives a call within a certain time after reporting its speed to the system, this simple intelligent scheme, which simply classifies subscribers as pedestrians and cars, is indeed better than simultaneous and sequential paging schemes. The schemes are also analysed under a two paging area constraint.

This paper presents current and latest schemes for location management in next generation wireless systems (3G and 4G). First, the hierarchical reference model of 3G wireless systems is introduced. Then a dynamic inter-system location management technique is developed based on new concepts of boundary location area and boundary location register, which are suitable for inter-system roaming scenarios. Moreover, the corresponding mobility application part (MAP) protocol is designed for inter-system location registration and call delivery procedures. The performance is evaluated in terms of signaling costs, latency of location registration and call delivery, as well as call losses due to the inter-system roaming. For the 4G systems, a generic system model is introduced to incorporate the existing wireless local networks and cellular systems and so on. In particular, a new scheme for reducing costs in route optimization is introduced to solve the above problems. In this new scheme, route optimization is performed only when it minimizes the total cost function, which provides the optimal result from the viewpoint of link and signaling costs. The simulation results show that the proposed scheme provides the better performance.

A bottom-up approach to parallel anisotropic mesh generation is presented by building a mesh generator from the principles of point-insertion, triangulation, and Delaunay refinement. Applications focusing on high-lift design or dynamic stall, or numerical methods and modeling test cases use two-dimensional domains. Our push-button parallel mesh generation approach, meaning the user only needs to start the program by specifying the initial geometry, anisotropic gradation, and ray angle constraint, can generate high-fidelity unstructured meshes with anisotropic boundary layers for use in the computational fluid dynamics field. © 2015 The Authors. Published by Elsevier Ltd. Peer-review under responsibility of organizing committee of the 24th International Meshing Roundtable (IMR24).