This letter proposes a simple and efficient random-binning based distributed source coding (DSC) scheme for application to remote source estimation in wireless sensor networks. The scheme jointly encodes data from multiple sensors with side information. It achieves high coding efficiency and reduces power and bandwidth consumption.

A waveguide-based surface plasmon resonance (SPR) sensor with an adsorbed layer is analyzed using the beam-propagation method. For two-dimensional (2-D) models, numerical results show that the change in thickness of the adsorbed layer placed on the metal leads to a significant shift of the maximum absorption wavelength. Through eigenmode analysis, the maximum absorption wavelength is found to be consistent with the cutoff wavelength of the second-order surface plasmon mode. The designed 2-D sensor shows an absorption wavelength shift from 0.595 to 0.603 µm, when the analyte refractive index is increased from 1.330 to 1.334. After a basic investigation using the 2-D models, we next study 3-D models. When the metal with the absorbed layer is wide enough to cover the core region, the 3-D results are similar to the 2-D results. However, as the metal width is reduced, the absorption wavelength shifts toward a shorter wavelength and the sensitivity to the refractive index change degrades gradually. The degradation of the sensitivity is considerable when the metal width is narrower than the core width. As a result, the metal width of the practical SPR sensor should be slightly wider than the core width so as to maintain the sensitivity corresponding to that obtained for the 2-D model.

An intermittent wireless communication system has been developed for low-power sensor networks that improves sensor network efficiency by promoting cooperative optimization among the hardware architecture, communication protocol, and multiple access scheme. The intermittent communication protocol together with hardware for intermittent function contributed to reduce power consumption and extended sensor-node battery lifetime. A multiple access scheme based on the R-ALOHA protocol is used for the wireless link; it works efficiently with the protocol and hardware. Due to its inter-layer optimization, the system has low power consumption regardless of the traffic load and is thus flexible enough to support a wide range of sensor network applications.

This paper proposes a compact interpolation scheme dedicated to a 1-dimensional position sensitive detector (PSD) with an optical sensing pixel array. The pixels are divided into even- and odd-numbered groups and winner take all (WTA) circuits are provided to each of the groups. The simulated results show that the detecting step-width is reduced to the half of the original one after applying the interpolation scheme.

RBAC (Role Based Access Control) was added the concept of the role which user can have access to resources based on the role of the user, and it increased efficiency and expandability. But, evolution of computing power and internet technology has caused the up rise of the dynamic environments, in accordance with it, it will be expected to require a dynamic access control model considering various elements. In this paper, we propose DRBAC (Dynamic RBAC) model in intelligent Home (i-Home). This is an access control model suitable for user-oriented service in i-Home. In order to consider dynamic environment in the existing RBAC models, the proposed model executes assignments user-role and permission-role based on context. In addition, the proposed model provides scalable access control policies which are suitable for the characteristics of intelligent environment as considering the user location information as a temporary constraints condition. Furthermore, we design and implement WSNM (Wireless Sensor Network Module) for its services. Finally, the proposed model provides flexible and efficient authentication method which applied Domain-Group concept as well as user / device authentication.

An electron transfer mediated amperometric enzyme biosensor based on a plasma-polymerized thin film of dimethylaminomethylferrocene (DMAMFc) is reported. A nanoscale thin polymer film containing a redox mediator was plasma-deposited directly onto an electrode with physisorbed glucose oxidase (GOD). Since the redox sites were introduced in the vicinity of the reaction centers of GOD, a highly efficient electron transfer system was formed in which almost all the reaction centers of GOD were connected to redox sites of the polymer matrix. The advantages of this strategy were: no need for prior or further chemical modification of the enzyme molecules, and simplicity of design compared with the use of a conventional polymer matrix. Moreover, the fact that the film deposition was performed using a microfabrication-compatible organic plasma promised great potential for high-throughput production of bioelectronic devices.

This paper overviews the high-speed power-line communication (PLC) technology, and the related standardization and regulatory activities are described. PLC modems of 200 Mbps class become a practical use stage in the West, and the standardization activity is active now. The discussion for deregulation is being continued in also Japan, and regulation values have been proposed. Another topic in this paper is a sensor network application of PLC, which is an indoor fine-grained localization system by acoustic Direct-Sequence Code Division Multiplexed (DS-CDM) signals. The obtained average accuracy of the localization in a 4 m2 plane was 1 cm if there was no obstacle. To realize the localization system, some novel ideas, such as PLC speakers, a synchronization method based on the zero-crossing timing of the mains frequency, and integrated wired/wireless PLC, are introduced.

Accurate and low-cost sensor localization is critical for deployment of wireless sensor networks. Distance between Ultra-wideband (UWB) sensor nodes can be obtained by measuring round trip flying time through two-way ranging (TWR) transaction. Because of difficulties in synchronization and channel estimate, the response delay of UWB node is the order of milliseconds. Comparing with the nanosecond propagation delay, relative clock offset between UWB nodes introduces big error in TWR. This paper presents the management of relative clock offset in TWR transaction. The relative clock offset between sensors is estimated by comparing the claimed and real frame duration. Simulation in the UWB channel model shows the relative clock offset after compensation can be reduced to less than 2 ppm.

We designed a CMOS image sensor capable of capturing variably smoothed images. This sensor uses a negative-feedback technique to set photodiode (PD) capacitance in the pixel circuit to any intermediate voltage during charge accumulation and it provides a neighboring-pixel operation by using their average value when resetting the PD capacitance. Smoothing-filter coefficients are changed by adjusting timing of the pixel-readout and neighboring-pixels operations. The performance of the proposed sensor was evaluated by SPICE simulation and numerical analysis.

In most research work for sensor network routings, perfect aggregation has been assumed. Such an assumption might limit the application of the wireless sensor networks. We address the impact of aggregation efficiency on energy consumption in the context of GIT routing. Our questions are how the most efficient aggregation point changes according to aggregation efficiency and the extent to which energy consumption can decrease compared to the original GIT routing and opportunistic routing. To answer these questions, we analyze a two-source model, which yields results that lend insight into the impact of aggregation efficiency. Based on analytical results, we propose an improved GIT: "aggregation efficiency-aware GIT," or AGIT. We also consider a suppression scheme for exploratory messages: "hop exploratory." Our simulation results show that the AGIT routing saves the energy consumption of the data transmission compared to the original GIT routing and opportunistic routing.

In this paper, the problem of Redundant Duplicated RREQ Network-wide Flooding (RDRNF), induced by multiple sensor nodes during route discovery in event-driven wireless sensor networks, is described. In order to reduce the number of signaling messages during the route discovery phase, a novel extension, named the Localized Route Discovery Extension (LRDE), to the on-demand ad hoc routing protocol, is proposed. The LRDE reduces energy consumption during route discovery. The heuristically and temporarily selected Path Set-up Coordinator (PSC) plays the role of a route request broker that alleviates redundant route request flooding. The LRDE also sets a route path be aggregation-compatible. The PSC can effectively perform data aggregation through the routing path constructed by the LRDE. The simulation results reveal that significant energy is conserved by reducing signaling overhead and performing data aggregation when LRDE is applied to on-demand routing protocols.

With advent of the ubiquitous network era and due to recent progress of III-V nanotechnology, the present III-V heterostructure microelectronics will turn into what one might call III-V heterostructure nanoelectronics, and may open up a new future in much wider application areas than today, combining information technology, nanotechnology and biotechnology. Instead of the traditional top-down approach, new III-V heterostructure nanoelectronics will be formed on nanostructure networks formed by combination of top-down and bottom-up approaches. In addition to communication devices, emerging devices include high speed digital LSIs, various sensors, various smart-chips, quantum LSIs and quantum computation devices covering varieties of application areas. Ultra-low power quantum LSIs may become brains of smart chips and other nano-space systems. Achievements of new functions and higher performances and their on chip integration are key issues. Key processing issue remains to be understanding and control of nanostructure surfaces and interfaces in atomic scale.

In order to reduce the traffic load and improve the system's lifetime, a cluster-based routing protocol has attracted more attention. In cluster-based sensor networks, energy can be conserved by combining redundant data from nearby sensors into cluster head nodes before forwarding the data to the destination. The lifespan of the whole network can also be expanded by the clustering of sensor nodes and through data aggregation. In this paper, we propose a cluster-based routing protocol which uses the location information of sensors to assist in network clustering. Our protocol partitions the entire network into several clusters by a particle swarm optimization (PSO) clustering algorithm. In each cluster, a cluster head is selected to deal with data aggregation or compression of nearby sensor nodes. For this clustering technique, the correct selection of the number of clusters is challenging and important. To cope with this issue, an energy dissipation model is used in our protocol to automatically estimate the optimal number of clusters. Several variations of PSO-clustering algorithm are proposed to improve the performance of our protocol. Simulation results show that the performance of our protocol is better than other protocols.

Sensing elements based on AlGaN/GaN HEMT and Schottky diode structures have been investigated in relation with the strain sensitivity of their characteristics. Piezoresistance of the Al0.3Ga0.7N/GaN HEMT-channel as well as changes in the current-voltage characteristics of the Schottky diodes have been observed with gauge factor (GF) values ranging between 19 and 350 for the selected biasing conditions. While a stable response to strain was measured, the observed temperature dependence of the channel resistance demonstrates the need for a systematic characterisation of the sensor properties to allow compensation of the observed temperature effects.

Pt Schottky diode gas sensors for carbon monoxide (CO) were fabricated using slightly Si doped bulk GaN grown on sapphire substrate. The influence of diode size, Pt thickness, operating temperature on gas sensitivity was investigated. CO sensitivity was improved six times by optimizing the size and thickness of the Pt contact. Surface restructuring and morphology changes of Pt film were observed after thermal annealing. These changes are enhanced as the film thickness is reduced further and contribute to improve CO sensitivity.

We developed a system that detects the vehicle driving immediately ahead of one's own car in the same lane and measures the distance to and relative speed of that vehicle to prevent accidents such as rear-end collisions. The system is the first in the industry to use non-scanning millimeter-wave radar combined with a sturdy stereo image sensor, which keeps cost low. It can operate stably in adverse weather conditions such as rain, which could not easily be done with previous sensors. The system's vehicle detection performance was tested, and the system can correctly detect vehicles driving 3 to 50 m ahead in the same lane with higher than 99% accuracy in clear weather. Detection performance in rainy weather, where water drops and splashes notably degraded visibility, was higher than 90%.

An atmospheric visibility measurement system capable of quantifying the most common operating range of onboard exteroceptive sensors is a key parameter in the creation of driving assistance systems. This information is then utilized to adapt sensor operations and processing or to alert the driver that the onboard assistance system is momentarily inoperative. Moreover, a system capable of either detecting the presence of fog or estimating visibility distances constitutes in itself a driving aid. In this paper, we first present a review of different optical sensors likely to measure the visibility distance. We then present our stereovision based technique to estimate what we call the "mobilized visibility distance". This is the distance to the most distant object on the road surface having a contrast above 5%. In fact, this definition is very close to the definition of the meteorological visibility distance proposed by the International Commission on Illumination (CIE). The method combines the computation of both a depth map of the vehicle environment using the "v-disparity" approach and of local contrasts above 5%. Both methods are described separately. Then, their combination is detailed. A qualitative evaluation is done using different video sequences. Finally, a static quantitative evaluation is also performed thanks to reference targets installed on a dedicated test site.

The superconducting quantum interference device (SQUID) is a transducer that converts magnetic flux into voltage. Its range of linear conversion, however, is very restricted. To overcome its narrow dynamic range, a flux-locked loop (FLL) is used to feedback the output field to cancel the input field. This prevents the operating point of the SQUID from moving far away from the null point. In this paper, an emulator for the SQUID sensor and the feedback coil has been proposed. Magnetic coupling between the original field and the generated field by the feedback coil was emulated by electronic circuits. By using the emulator, FLL circuits can be analyzed and optimized without use of SQUID sensors. This is a useful feature, especially in the early stage of development of the MCG system when a magnetically shielded room or real SQUID sensors may not yet be available. The emulator may also be used as a test signal generator for multi-channel gain calibration and for system maintenance.

A wireless sensor network is a network of compact micro-sensors equipped with wireless communication capability. In a wireless sensor network, saving energy is a critical issue. Furthermore, a sensor node is expected to face many difficulties in signaling and computing. As a MAC scheme for a wireless sensor network, we thus propose an energy-aware version of pure ALOHA scheme, where rather than sacrificing the simplicity of pure ALOHA, we take a straightforward approach in saving energy by trading off throughput performance. First, we add a step of deciding between stop and continuation prior to each delivery attempt for a MAC PDU. Secondly, we find an optimal stopping rule for such a decision in consideration of the losses reflecting energy consumption as well as throughput degradation. In particular, we note that the results of delivery attempts are hardly predictable in the environment that sensor nodes contend for the error-prone wireless resource. Thus, presuming that only partial information about such results is available to sensor nodes, we explicitly draw an optimal stopping rule. Finally, numerical examples are given to demonstrate the expected losses incurred by optimal stopping rules with full and partial information.

A novel technique is proposed for measuring the distributed strain and temperature in a fiber with a very high resolution. This technique makes use of the jagged appearance of Rayleigh backscatter traces from a single-mode fiber measured by using a coherent OTDR with a precisely frequency-controlled light source. Our preliminary experiment indicated the possibility of measuring temperature with a resolution of better than 0.01 and a spatial resolution of one meter. This temperature resolution is two orders of magnitude better than that provided by Brillouin-based distributed sensors.