An improved multi-agent simulation methodology for modelling and evaluating wireless communication systems resource allocation algorithms

Multi-Agent Systems (MAS) constitute a well known approach in modelling dynamical real world systems. Recently, this technology has been applied to Wireless Communication Systems (WCS), where efficient resource allocation is a primary goal, for modelling the physical entities involved, like Base Stations (BS), service providers and network operators. This paper presents a novel approach in applying MAS methodology to WCS resource allocation by modelling more abstract entities involved in WCS operation, and especially the concurrent network procedures (services). Due to the concurrent nature of a WCS, MAS technology presents a suitable modelling solution. Services such as new call admission, handoff, user movement and call termination are independent to one another and may occur at the same time for many different users in the network. Thus, the required network procedures for supporting the above services act autonomously, interact with the network environment (gather information such as interference conditions), take decisions (e.g. call establishment), etc, and can be modelled as agents. Based on this novel simulation approach, the agent cooperation in terms of negotiation and agreement becomes a critical issue. To this end, two negotiation strategies are presented and evaluated in this research effort and among them the distributed negotiation and communication scheme between network agents is presented to be highly efficient in terms of network performance. The multi-agent concept adapted to the concurrent nature of large scale WCS is, also, discussed in this paper

A model of time dependent behavior in concurrent software systems

A great difficulty in building distributed systems lies in being able to predict what the systems behavior will be. A distributed or communicating system is defined here to be one in in which the hardware consists of a set of processors each with their own memory, connected by some communication medium (there is no shared memory), and the software is assumed to be of the CSP (Hoare's Communicating Sequential Processes) type.In the past few years some theories have been proposed to model features of communicating systems. Milner's Calculus of communicating Systems (CCS), Winskel's Synchronization Trees (ST), Hennessy's Acceptance Trees (AT), and Hoare and Brookes's theory of communicating processes are examples of formal models of such systems. All of these models concentrate on modelling observable properties of a system.Event Dependency Trees (EDT) is a new representation of communicating systems that models the time dependent nature of such systems. None of the representations mentioned above explicitly represent time but time is precisely the factor that introduces so much variability and complexity into such software and systems. EDT provides a representation based on trees and a set of operations over the EDT trees that can be used to produce deadlock-free software. The model supplies potentially important information for the design and construction of distributed, parallel software systems

A Modular Integrated Development Environment for Coloured Petri Net Models

Distributed software systems are becoming increasingly popular and used. Most of modern distributed systems provide the application of concurrency, also in- cluding resource sharing, communication and synchronization between different modules. These distributed systems comes with the challenges concerning data synchronization, scalability and performance, among others. By modelling these systems helps with solving these challenges, and there exists multiple tools for this. CPN Tools is one of these tools. CPN Tools is used for editing, simulating and analyzing Coloured Petri nets models. A need has been identified to devel- oped new software for develop new and up to date tools for editing, simulating and analyzing Coloured Petri nets to further development and fit the increasing need for distributed systems. Answering this need, a new simulating tool has been proposed. This thesis proposes an editor focusing on the modelling and visualization with the potentially integrate this simulator. This editor consists of an application running on Electron and using GoJS for modelling. This has resulted in a modelling tool for creating CPN models, with the possibility of increased abstraction of the models of the modern distributed systems.Masteroppgave i Programvareutvikling samarbeid med HVLPROG399MAMN-PRO

Overview of Swallow --- A Scalable 480-core System for Investigating the Performance and Energy Efficiency of Many-core Applications and Operating Systems

We present Swallow, a scalable many-core architecture, with a current configuration of 480 x 32-bit processors. Swallow is an open-source architecture, designed from the ground up to deliver scalable increases in usable computational power to allow experimentation with many-core applications and the operating systems that support them. Scalability is enabled by the creation of a tile-able system with a low-latency interconnect, featuring an attractive communication-to-computation ratio and the use of a distributed memory configuration. We analyse the energy and computational and communication performances of Swallow. The system provides 240GIPS with each core consuming 71--193mW, dependent on workload. Power consumption per instruction is lower than almost all systems of comparable scale. We also show how the use of a distributed operating system (nOS) allows the easy creation of scalable software to exploit Swallow's potential. Finally, we show two use case studies: modelling neurons and the overlay of shared memory on a distributed memory system.Comment: An open source release of the Swallow system design and code will follow and references to these will be added at a later dat

Towards a Multi Metamodelling Approach for Developing Distributed Healthcare Applications

Model Driven Engineering (MDE) uses formal methods to build mathematically rigorous models of complex systems. Metamodelling plays an important role in MDE as it is used to specify domain specific modelling languages. However, the potential of metamodelling has not been fully explored. Current approaches of MDE are often at a low level of abstraction and lack domain concepts for specifying behavior. In previous work, we proposed a multi metamodelling approach that captures the complexity of systems by using a metamodelling hierarchy, built from individually defined metamodels, each capturing different aspects of a healthcare domain. In this paper, we focus on modelling distributed healthcare applications and present an example from the healthcare domain. We address certain modelling aspects related to distributed applications such as process modelling, using message passing communication, and coordination of processes and resources

Fluid approximation of broadcasting systems

Nature-inspired paradigms have been proposed to design and forecast behaviour of open distributed systems, such as sensor networks and the internet of things. In these paradigms system behaviour emerges from (complex) interactions among a large number of agents. Modelling these interactions in terms of classical point-to-point communication is often not practical. This is due to the large scale and the open nature of the systems, which means that partners for point-to-point communication may not be available at any given time. Nevertheless the need for efficient formal verification of qualitative and quantitative properties of these systems is of utmost importance, especially given their proposed pervasive and transparent nature. CARMA is a recently proposed formal modelling language for open distributed systems, which is equipped with a broadcast communication in order to meet the communication challenges of such systems. The inclusion of quantitative information about the timing and probability of actions gives rise to models suitable for analysing questions such as the probability that information will achieve total coverage within a system, or the expected market share that might be gained by competing service providers relying on viral advertising. The ability to express models is not the only challenge, because the scale of the systems we are interested in often defies discrete state-based analysis techniques such as stochastic simulation. This is the problem that we address in this paper as we consider how to provide an efficient fluid approximation, supporting efficient and accurate quantitative analysis of large scale systems, for a language that incorporates broadcast communication

HyperPRAW : architecture-aware hypergraph restreaming partition to improve performance of parallel applications running on high performance computing systems

High Performance Computing (HPC) demand is on the rise, particularly for large distributed computing. HPC systems have, by design, very heterogeneous architectures, both in computation and in communication bandwidth, resulting in wide variations in the cost of communications between compute units. If large distributed applications are to take full advantage of HPC, the physical communication capabilities must be taken into consideration when allocating workload. Hypergraphs are good at modelling total volume of communication in parallel and distributed applications. To the best of our knowledge, there are no hypergraph partitioning algorithms to date that are architecture-aware. We propose a novel restreaming hypergraph partitioning algorithm (HyperPRAW) that takes advantage of peer to peer physical bandwidth profiling data to improve distributed applications performance in HPC systems. Our results show that not only the quality of the partitions achieved by our algorithm is comparable with state-of-the-art multilevel partitioning, but that the runtime performance in a synthetic benchmark is significantly reduced in 10 hypergraph models tested, with speedup factors of up to 14x