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EURASIP Journal on Embedded Systems

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This is an Open Access Journal

Open Access journal
ISSN (Print) 1687-3955 - ISSN (Online) 1687-3963
Published by SpringerOpen

[82 journals]

Implantable RF telemetry for cardiac monitoring in the murine heart: a tutorial review
- Authors: Robert Sobot
  First page: 1
  Abstract: Research and development of implantable RF telemetry systems intended specifically to enable and support cardiac monitoring of genetically engineered small animal subjects, rats and mice in particular, has already gained significant momentum. This article presents the state of the art review of experimental cardiac monitoring telemetry systems, with strong accent on the systems designed to work with a dual pressure--volume conductance-based catheter sensor. These commercially available devices are already small enough to fit inside a left-ventricle of a mouse heart. However, if the complete system is to be fully implanted and the subject allowed to freely move inside a cage, the mouse's small body size sets harsh constrains on the size and power consumption of the required electronics. Consequently, significant portion of the research efforts is directed towards the development of low-volume and -power electronics, as well as RF energy harvesting systems that are required to serve as the energy source to the implanted telemetry instead of the relatively very bulky batteries.
  Citation: EURASIP Journal on Embedded Systems 2013, null:1
  PubDate: 2013-03-11T00:00:00Z
  DOI: 10.1186/1687-3963-2013-1
  Issue No: Vol. ${item.volume} (2013)
Feasibility of backscatter RFID systems on the human body
- Authors: Jasmin Grosinger
  First page: 2
  Abstract: In this contribution, the author examines the feasibility of on-bodybackscatter radio frequency identification (RFID) systems in theultra high frequency range. Four different on-body RFID systems areinvestigated operating monopoles or patch antennas at900 MHz or 2.45 GHz. The systems' feasibility isanalyzed by means of on-body channel measurements in a realistictest environment. The measured channel transfer functions allow toevaluate if enough power is available for a reliable backscattercommunication. This evaluation is done with the aid of outageprobabilities in the forward link and the backward link of thesystems. Using these probabilities, the on-body systems provefeasible when using state-of-the-art reader and transponder chips.In particular, the use of semi-passive RFID transponder chips leadsto a reliable performance in the systems' forward links. The robustperformance of the systems' backward links is clearly shown for the900 MHz monopole antenna configuration, while thelimitations in the backward links of the other systems have to beovercome by the use of a second reader unit on the person's back.The novel feasibility analysis presented here allows to examine eachsystem parameter individually and thus leads to reliable and robustbackscatter RFID systems.
  Citation: EURASIP Journal on Embedded Systems 2013, null:2
  PubDate: 2013-03-20T00:00:00Z
  DOI: 10.1186/1687-3963-2013-2
  Issue No: Vol. ${item.volume} (2013)
Clock refinement in imperative synchronous languages
- Authors: Mike Gemünde|Jens Brandt|Klaus Schneider
  First page: 3
  Abstract: The synchronous model of computation divides the programexecution into a sequence of logical steps. On the one hand, thisview simplifies many analyses and synthesis procedures, but on theother hand, it imposes restrictions on the modeling and optimizationof systems. In this article, we introduce refined clocks inimperative synchronous languages to overcome these restrictionswhile still preserving important properties of the basic model. Wefirst present the idea in detail and motivate various designdecisions with respect to the language extension. Then, we sketchall the adaptations needed in the design flow to support refinedclocks.
  Citation: EURASIP Journal on Embedded Systems 2013, null:3
  PubDate: 2013-04-10T00:00:00Z
  DOI: 10.1186/1687-3963-2013-3
  Issue No: Vol. ${item.volume} (2013)
Using field strength scaling to save energy in mobile HF-band RFID-systems
- Authors: Manuel Menghin|Norbert Druml|Christian Steger|Reinhold Weiss|Holger Bock|Josef Haid
  First page: 4
  Abstract: Radio frequency identification (RFID) is a technology enabling a contactless exchange of data. Thistechnology features the possibility to wirelessly transfer power to the transponder (opponent). HF-RFID is used in mobile devices like smart phones and shows potential for applications like payment,identification, etc. Unfortunately, the needed functionality increases the battery drain of the device. Asa countermeasure, power-management techniques are implemented. However, these techniques com-monly do not consider the whole system, which also consists of the communication to the transpon-der, to prevent wasting energy. One cross-system technique of reducing the wasted energy is magneticfield strength scaling, which regulates the power transfer to the transponder. This article shows threeinvestigations made, regarding field strength scaling to prevent this wastage of energy. The resultsof one investigation, how to use field strength scaling at card detection phase in form of the PTF-Determinator method, is described in detail. This method determines the Power Transfer Function(PTF) during run-time and scales the provided power accordingly to save energy. As a case study thePTF-Determinator is integrated in an application to read digital business cards. The resulting powerconsumption and timing has been evaluated by simulation and measurement of a development plat-form for mobile phones. Furthermore, the impact of field strength scaling to the energy consumptionof a state of the art NFC-enhanced smart phone has been analyzed. The results of the case study showsthat up to 26% less transmission energy (energy drain of NFC) is needed, if field strength scaling isapplied (proofen by measurement). According to this result a smart phone's battery drain (energydrain of the whole system) can be decreased by up to 13% by using field strength scaling for this casestudy.
  Citation: EURASIP Journal on Embedded Systems 2013, null:4
  PubDate: 2013-04-16T00:00:00Z
  DOI: 10.1186/1687-3963-2013-4
  Issue No: Vol. ${item.volume} (2013)
FPGA based wireless sensor node with customizable event-driven architecture
- Authors: Junsong Liao|Brajendra Singh|Mohammed Khalid|Kemal Tepe
  First page: 5
  Abstract: This article presents the design and implementation of modularcustomizable event-driven architecture with parallel executioncapability for the first time with wireless sensor nodes using standalone FPGA. This customizable event-driven architecture is based onmodular generic event dispatchers and autonomous event handlers,which will help WSN application developers to quickly develop theirapplications by adding the required number of event dispatchers andevent handlers as per the need of a WSN application. Thisarchitecture can handle multiple events in parallel, including highpriority ones. Additionally, it provides non-preemptive operationwhich removes the timing uncertainty and overhead involved withinterrupt-driven processor-based sensor node implementation, whichis required in real-time wireless sensor networks (WSNs). Thus,higher computation power of FPGAs combined with the non-preemptivemodular event-driven architecture with parallel execution capabilityenables a variety of new WSN applications and facilitates rapidprototyping of WSN applications. In this article, the performance ofFPGA-based sensor device is compared with general purposeprocessor-based implementations of sensor devices. Results show thatour FPGA-based implementation provides significant improvement insystem efficiency measured in terms of clock cycle counts requiredfor typical sensor network tasks such as packet transmission, relayand reception.
  Citation: EURASIP Journal on Embedded Systems 2013, null:5
  PubDate: 2013-04-19T00:00:00Z
  DOI: 10.1186/1687-3963-2013-5
  Issue No: Vol. ${item.volume} (2013)
Hybrid WSN and RFID indoor positioning and tracking system
- Authors: Zhoubing Xiong|Zhenyu Song|Andrea Scalera|Enrico Ferrera|Fracesco Sottile|Paolo Brizzi|Riccardo Tomasi|Maurizio Spirito
  First page: 6
  Abstract: Wireless sensor networks (WSNs), consisting of a large number of nodes to detect ambient environment, arewidely deployed in a predefined area to provide more sophisticated sensing, communication, and processingcapabilities, especially concerning the maintenance when hundreds or thousands of nodes are required to bedeployed over wide areas at the same time. Radio frequency identification (RFID) technology, by reading thelow-cost passive tags installed on objects or people, has been widely adopted in the tracing and trackingindustry and can support an accurate positioning within a limited distance. Joint utilization of WSN and RFIDtechnologies is attracting increasing attention within the Internet of Things (IoT) community, due to thepotential of providing pervasive context-aware applications with advantages from both fields. WSN-RFIDconvergence is considered especially promising in context-aware systems with indoor positioning capabilities,where data from deployed WSN and RFID systems can be opportunistically exploited to refine and enhance thecollected data with position information. In this papera, we design and evaluate a hybridsystem which combines WSN and RFID technologies to provide an indoor positioning service with the capabilityof feeding position information into a general-purpose IoT environment. Performance of the proposed system isevaluated by means of simulations and a small-scale experimental set-up. The performed analysis demonstratesthat the joint use of heterogeneous technologies can increase the robustness and the accuracy of the indoorpositioning systems.
  Citation: EURASIP Journal on Embedded Systems 2013, null:6
  PubDate: 2013-04-22T00:00:00Z
  DOI: 10.1186/1687-3963-2013-6
  Issue No: Vol. ${item.volume} (2013)
A smart collision recovery receiver for RFIDs
- Authors: Jelena Kaitovic|Robert Langwieser|Markus Rupp
  First page: 7
  Abstract: In this work, we focus on framed slotted Aloha (FSA) and passive ultra high-frequency radiofrequency identification multi-antenna systems with physical layer collision recovery. Wemodify the tags slightly by adding a so-called `postpreamble' that facilitates channel estimation.Furthermore, we investigate the throughput performance of advanced receiver structures in collisionscenarios. More specifically, we analyse the throughput of FSA systems with up to four receiveantennas that can recover from a collision of up to eight tags on the physical layer and acknowledgeall tags involved in that collision. Due to the higher collision recovery capabilities, the framesizes can be significantly reduced, and thus, the throughput can be increased. We also deriveanalytically optimal frame sizes, given that a certain number of collisions can be resolved. Wefurther study the constraints to the throughput due to the structure of our receiver and channelestimation for different collision scenarios. Furthermore, we propose a novel collision recoverymethod with two phases: first, a successive interference cancellation and, second, a projection of theconstellation into the orthogonal subspace of the interference. Additionally, the inventory time,i.e. the number of slots necessary to successfully decode all tags in the reader range, is calculatedand compared for different receiver types. A validation of our theoretical predictions is achieved bymeans of simulations. We show that by our proposed methods, we can realistically achieve more than tentimes higher throughput or, equivalently, a reduction of the inventory time by more than 90%.
  Citation: EURASIP Journal on Embedded Systems 2013, null:7
  PubDate: 2013-04-30T00:00:00Z
  DOI: 10.1186/1687-3963-2013-7
  Issue No: Vol. ${item.volume} (2013)
Automatic leaking carrier canceller adjustment techniques
- Authors: Gregor Lasser|Robert Langwieser|Christoph Mecklenbräuker
  First page: 8
  Abstract: In this contribution, four automatic adjustment algorithms forleakage carrier cancellation in radio frequency identification (RFID) readers are compared: fullsearch, gradient search, fast and direct I/Q algorithms. Further,we propose two enhanced adjustment procedures.First, we analytically calculate the performance of the fastadjustment algorithm in the presence of noise and derive itstheoretical bias. We compare the theoretical results with the numericalresults from accompanying simulations. Further, we evaluate theperformance of these algorithms based on real-world measurementsacquired with our RFID testbed.Finally, we propose and discuss the merits of two enhanced adjustment procedures based on the fast adjustmentalgorithm. The fast adjustment procedure with bipolar probing signals achieves the isolation gain of the(much slower) gradient search algorithm at the expense of a mean penalty of 0.48 dB. We observe that the fastadjustment aided gradient algorithm requires 72% less steps than the gradient search algorithm in ourmeasurements.
  Citation: EURASIP Journal on Embedded Systems 2013, null:8
  PubDate: 2013-05-07T00:00:00Z
  DOI: 10.1186/1687-3963-2013-8
  Issue No: Vol. ${item.volume} (2013)
Use of compiler optimization of software bypassing as a method to improve energy efficiency of exposed data path architectures
- Authors: Vladimír Guzma|Teemu Pitkänen|Jarmo Takala
  First page: 9
  Abstract: In the design of embedded systems, hardware and software need to be co-exploredtogether to meet targets of performance and energy. With the use of application-specific instruction-set processors, as a stand-alone solution or as a part of a systemon chip, the customization of processors for a particular applicationis a known method to reduce energy requirements and provide performance.In particular, processor designs with exposed data paths trade compile time complexity for simplified control hardware and lower running costs. An exposed data path also allows the removal of unused components of interconnection network, once the application is compiled.In this paper, we propose the use of a compiler technique for processors with exposeddata paths, called software bypassing. Software bypassing allows the compiler toschedule data transfers between execution units directly, bypassing the use of a general-purpose register file, increasing scheduling freedom, with reduceddependencies induced by the reuse of registers, decreasing the number of read and writeaccesses to register files, and allowing the use of register files with less read andwrite ports while maintaining or improving performance and maintaining reprogrammability.We compare our proposal against an architecture exploration technique, connectivity reduction,which finds in compiled application all interconnection network componentsthat are used and removes those which are not, leading to an energy-efficientapplication-specific instruction-set processor.We observe that the use of software bypassing leads to improvements in application speed, with architectures having the smallest number of register file ports consistently outperforming architectures with larger number of ports, and reduction in energy consumption. In contrast, connectivity reduction maintains the same application speed, reduces energy consumption, and allows for increase in processor frequency; however, with the clock frequency increased to match the performance of software bypassing, energy consumption grows.We also observe that in case reprogrammability is not an issue, the most energy-efficient solution is a combination of software bypassing and connectivity reduction.
  Citation: EURASIP Journal on Embedded Systems 2013, null:9
  PubDate: 2013-05-10T00:00:00Z
  DOI: 10.1186/1687-3963-2013-9
  Issue No: Vol. ${item.volume} (2013)
Trade-off between maximum cardinality of collision sets and accuracy of RFID reader-to-reader collision detection
- Authors: Linchao Zhang|Filippo Gandino|Renato Ferrero|Bartolomeo Montrucchio|Maurizio Rebaudengo
  First page: 10
  Abstract: As the adoption of the radio-frequency identification (RFID) technology is increasing, many applications require a dense reader deployment. In such environments, reader-to-reader interference becomes a critical problem, so the proposal of effective anti-collision algorithms and their analysis are particularly important. Existing reader-to-reader anti-collision algorithms are typically analyzed using single interference models that consider only direct collisions. The additive interference models, which consider the sum of interferences, are more accurate but require more computational effort. The goal of this paper is to find the difference in accuracy between single and additive interference models and how many interference components should be considered in additive models. An in-depth analysis evaluates to which extent the number of the additive components in a possible collision affects the accuracy of collision detection. The results of the investigation shows that an analysis limited to direct collisions cannot reach a satisfactory accuracy, but the collisions generated by the addition of the interferences from a large number of readers do not affect significantly the detection of RFID reader-to-reader collisions.
  Citation: EURASIP Journal on Embedded Systems 2013, null:10
  PubDate: 2013-05-17T00:00:00Z
  DOI: 10.1186/1687-3963-2013-10
  Issue No: Vol. ${item.volume} (2013)