Showing papers by "Marko Hännikäinen published in 2009"
01 Jan 2009
TL;DR: An energy-efficient neighbor discovery protocol targeted at synchronized low duty-cycle medium access control (MAC) schemes such as IEEE 802.15.4 and S-MAC that effectively reduces the need for costly network scans by proactively distributing node schedule information in MAC protocol beacons and by using this information for establishing new communication links.
Abstract: Low energy consumption is a critical design requirement for most wireless sensor network (WSN) applications. Due to minimal transmission power levels, time-varying environmental factors and mobility of nodes, network neighborhood changes frequently. In these conditions, the most critical issue for energy is to minimize the transactions and time consumed for neighbor discovery operations. In this paper, we present an energy-efficient neighbor discovery protocol targeted at synchronized low duty-cycle medium access control (MAC) schemes such as IEEE 802.15.4 and S-MAC. The protocol effectively reduces the need for costly network scans by proactively distributing node schedule information in MAC protocol beacons and by using this information for establishing new communication links. Energy consumption is further reduced by optimizing the beacon transmission rate. The protocol is validated by performance analysis and experimental measurements with physical WSN prototypes. Experimental results show that the protocol can reduce node energy consumption up to 80% at 1-3m/s node mobility.
91 citations
TL;DR: This work gives a new definition to measure and implement QoS in low duty cycle WSNs, namely availability and reliability, and proposes a data forwarding algorithm suitable for resource constrained W SNs that guarantees end-to-end reliability.
Abstract: A wireless sensor network (WSN) is an ad-hoc technology that may even consist of thousands of nodes, which necessitates autonomic, self-organizing and multihop operations. A typical WSN node is battery powered, which makes the network lifetime the primary concern. The highest energy efficiency is achieved with low duty cycle operation, however, this alone is not enough. WSNs are deployed for different uses, each requiring acceptable Quality of Service (QoS). Due to the unique characteristics of WSNs, such as dynamic wireless multihop routing and resource constraints, the legacy QoS metrics are not feasible as such. We give a new definition to measure and implement QoS in low duty cycle WSNs, namely availability and reliability. Then, we analyze the effect of duty cycling for reaching the availability and reliability. The results are obtained by simulations with ZigBee and proprietary TUTWSN protocols. Based on the results, we also propose a data forwarding algorithm suitable for resource constrained WSNs that guarantees end-to-end reliability while adding a small overhead that is relative to the packet error rate (PER). The forwarding algorithm guarantees reliability up to 30% PER.
25 citations
20 Apr 2009
TL;DR: This paper presents how UML2 models of IP-XACT features can be utilized to efficiently design and implement a multiprocessor SoC prototype on FPGA and modeling concepts are improved from earlier work for the utilized integration methodology.
Abstract: IP-XACT is a standard for describing intellectual property metadata for System-on-Chip (SoC) integration. Recently researchers have proposed visualizing and abstracting IP-XACT objects using structural UML2 model elements and diagrams. Despite the number of proposals at conceptual level, experiences on utilizing this representation in practical SoC development environments are very limited. This paper presents how UML2 models of IP-XACT features can be utilized to efficiently design and implement a multiprocessor SoC prototype on FPGA. The main contribution of this paper is the experimental development of a multiprocessor platform on FPGA using UML2 design capture, IP-XACT compatible components, and design automation tools. In addition, modeling concepts are improved from earlier work for the utilized integration methodology.
15 citations
TL;DR: This is the first proposal that defines transformation between UML activity diagrams and streaming data application workload meta models and successfully adopts it for RTES performance evaluation.
Abstract: This article presents an efficient method to capture abstract performance model of streaming data real-time embedded systems (RTESs). Unified Modeling Language version 2 (UML2) is used for the performance modeling and as a front-end for a tool framework that enables simulation-based performance evaluation and design-space exploration. The adopted application meta-model in UML resembles the Kahn Process Network (KPN) model and it is targeted at simulation-based performance evaluation. The application workload modeling is done using UML2 activity diagrams, and platform is described with structural UML2 diagrams and model elements. These concepts are defined using a subset of the profile for Modeling and Analysis of Realtime and Embedded (MARTE) systems from OMG and custom stereotype extensions. The goal of the performance modeling and simulation is to achieve early estimates on task response times, processing element, memory, and on-chip network utilizations, among other information that is used for design-space exploration. As a case study, a video codec application on multiple processors is modeled, evaluated, and explored. In comparison to related work, this is the first proposal that defines transformation between UML activity diagrams and streaming data application workload meta models and successfully adopts it for RTES performance evaluation.
14 citations
17 Nov 2009
TL;DR: A robust Synchronization TREE construction and maintenance protocol that reduces communication overhead to 6% in tree construction and to 10% in remote clock estimation compared to flooding which is commonly used in related protocols.
Abstract: The dynamic and resource constrained nature of Wireless Sensor Networks (WSNs) require that the time synchronization protocol is highly fault tolerant whilst minimizing communication overhead for energy-efficiency In current tree-based WSN synchronization protocols, the tree fault tolerance is not considered at all or incurs a significant messaging overhead In this paper, we present a robust Synchronization TREE construction and maintenance protocol (S-TREE) It can handle failed nodes and communication links, and intermittent connectivity It is integrated to the inherent neighbor discovery to minimize communication overhead The S-TREE protocol minimizes the accumulated synchronization error of any given neighbor clock estimation technique by using minimum hop paths to the reference node The protocol performance is analyzed mathematically For an example scenario of 1000 nodes S-TREE reduces communication overhead to 6% in tree construction and to 10% in remote clock estimation compared to flooding which is commonly used in related protocols
2 citations