Reliability issues such as a soft error and NBTI (negative bias temperature instability) have become a matter of concern as integrated circuits continue to shrink. It is getting more and more important to take reliability requirements into account even for consumer products. This paper presents a dynamic continuous signature monitoring (DCSM) technique for high reliable computer systems. The DCSM technique dynamically generates reference signatures as well as runtime ones during executing a program. The DCSM technique stores the generated signatures in a signature table, which is a small storage circuit in a microprocessor, unlike the conventional static continuous signature monitoring techniques and contributes to saving program or data memory space that stores the signatures. Our experiments showed that our DCSM technique protected 1.4-100.0% of executed instructions depending on the size of signature tables.

A continuous-time waveform monitoring technique for quality on-chip power noise measurements features matched probing performance among a variety of voltage domains of interest in a VLSI circuit, covering digital Vdd, analog Vdd, as well as at Vss, and multiple probing capability at various locations on power planes. A calibration flow eliminates the offset as well as gain errors among probing channels. The consistency of waveforms acquired by the proposed continuous-time monitoring and sampled-time precise digitization techniques is ensured. A 90-nm CMOS on-chip monitor prototype demonstrates dynamic power supply noise measurements with 200 mV at 2.5 V, 1.0 V, and 0.0 V, respectively, with less than 4 mV deviation among 240 probing channels.

This paper proposes an all-digital process variability monitor which utilizes a simple buffer ring with a pulse counter. The proposed circuit monitors the process variability according to a count number of a single pulse which propagates on the buffer ring and a fixed logic level after the pulse vanishes. The proposed circuit has been fabricated in 65 nm CMOS process and the measurement results demonstrate that we can monitor the PMOS and NMOS variabilities independently using the proposed monitoring circuit. The proposed monitoring technique is suitable not only for the on-chip process variability monitoring but also for the in-field monitoring of aging effects such as negative/positive bias instability (NBTI/PBTI).

In this paper, a 0.18-V input three-stage charge pump circuit applying forward body bias is proposed for energy harvesting applications. In the developed charge pump, all the MOSFETs are forward body biased by using the inter-stage/output voltages. By applying the proposed charge pump as the startup in the boost converter, the kick-up input voltage of the boost converter is reduced to 0.18 V. To verify the circuit characteristics, the conventional zero body bias charge pump and the proposed forward body bias charge pump were fabricated with 65 nm CMOS process. The measured output current of the proposed charge pump under 0.18-V input voltage is increased by 170% comparing to the conventional one at the output voltage of 0.5 V. In addition, the boost converter successfully boosts the 0.18-V input to higher than 0.65-V output.

We describe a parameter estimation method for a target object in an area that sensors monitor. The parameters to be estimated are the perimeter length, size, and parameter determined by the interior angles of the target object. The estimation method does not use sensor location information, only the binary information on whether each sensor detects the target object. First, the sensing area of each sensor is assumed to be line-segment-shaped, which is a model of an infrared distance measurement sensor. Second, based on the analytical results of assuming line-segment-shaped sensing areas, we developed a unified equation that works with general sensing areas and general target-object shapes to estimate the parameters of the target objects. Numerical examples using computer simulation show that our method yields accurate results.

In this paper, we establish our child safety system model related to the addressing contradictory issue of wireless sensor networks caused by the mutual authentication and privacy protection of an end-user. Based on the system model, we propose the novel location-aware and privacy-preserving approach for providing child safety over wireless sensor networks. Although we illustrate our protocol over the sensor networks, the proposed protocol can be operated by various wireless networks (e.g., WiFi and UWB) which can support RSSI (Received Signal Strength Indication). Compared to a few previous works, the proposed approach can show the potential of enhancing accuracy with location information, preserve the privacy of an end-user, and provide the capability of controlling the child safety service to an end-user.

DCT encoding of images leads to block artifact and mosquito noise degradations in the decoded pictures. We propose an estimation to determine the mosquito noise block and level; however, this technique lacks sufficient linearity. To improve its performance, we use the sub-divided block for edge effect suppression. The subsequent results are mostly linear with the quantization.

This paper proposes a technique to reduce the capacitance spread in switched-capacitor (SC) filters. The proposed technique is based on a simple charge distribution and partial charge transfer which is applicable to various integrator topologies. An implementation example on an existing integrator topology and a design example of a 2nd-order SC low-pass filter are given to demonstrate the performance of the proposed technique. A design example of an SC filter show that the filter designed using the proposed technique has an approximately 23% less total capacitance than the one of SC low-pass filter with conventional capacitance spread reduction technique.

This paper presents a novel time-domain design procedure for fast-settling three-stage nested-Miller compensated (NMC) amplifiers. In the proposed design methodology, the amplifier is designed to settle within a definite time period with a given settling accuracy by optimizing both the power consumption and silicon die area. Detailed design equations are presented and the circuit level simulation results are provided to verify the usefulness of the proposed design procedure with respect to the previously reported design schemes.

The number of SIP-based services provided by network service providers (NSPs) is increasing. SIP allows NSPs to control services and to collect the information relating to charging for the usage of their customer communications. Monitoring SIP messages (exchanged between SIP proxy servers and user terminals) is vital for providing the stable SIP-based services. Monitoring SIP messages enables NSPs to quickly discover a fault location where SIP messages are lost, and to determine the subsequent recovery solutions. This paper proposes a lightweight method for determining the location of SIP message loss through relationships based on the SIP's retransmission mechanism. Numerical analyses show that the proposed method can locate the lossy links of SIP messages with a low probability of detection failure.

A novel one-transistor dynamic random access memory (1T DRAM) cell has been proposed for a low-voltage operation and longer data retention time. The proposed 1T DRAM cell has three features compared with a conventional 1T DRAM cell: low body doping concentration, a recessed gate structure, and a P + poly-Si gate. Simulation results show that the proposed 1T DRAM cell has < 1-ns program time and > 100-ms data retention time under the condition of sub-1-V operating voltage.

A Real-time Capacitor Compensation (RCC) scheme is proposed for low power and continuous communication in the wearable inductive coupling transceiver. Since inductance values of wearable inductor vary dynamically with deterioration of its communication characteristics, the inductance value is monitored and its resonance frequency is adjusted by additive parallel/serial capacitors in real time. RLC Bridge for detection of the inductance variations and the Dual-edge Sampling Comparator for recognition of the variance direction are proposed. It is implemented in a 0.18 µm CMOS technology, and it occupies a 12.7 mm2 chip area. The proposed transceiver consumes only 426.6 µW at 4 Mbps data rate. The compensation time takes 4.78 µs, including 3 µs of detection and 1.78 µs for compensation process in worst case.

Recently wireless sensor networks (WSN) has risen as one of the advanced candidate technologies in order to provide more efficient structure health monitoring (SHM) solution in construction sites. In this paper, we proposed WSN monitoring framework in building sites based on 3D visualization and Augmented Reality (AR) in mobile devices. The proposed system applies 3D visualization and AR technology to camera-enabled mobile devices in WSN environment in order to gather much more information than before. Based on the proposed system, we made an experiment to validate the effectiveness of 3D and AR mode using collected data in IEEE 802.15.4-based WSN.

This manuscript reported basic examination results of the wireless network communication performance at the coast. We consider that underwater environment condition monitoring is a sort of likely typical application for ubiquitous sensor networks. The result of the experiment shows the performance of the wireless network communication at the coastal area.

Ubiquitous technologies such as sensor network and RFID have enabled companies to realize more rapid and agile manufacturing and service systems. In this paper, we addresses how the huge amount of real-time events coming from these devices can be filtered and integrated to business process such as manufacturing, logistics, and supply chain process. In particular, we focus on complex event processing of sensor and RFID events in order to integrate them to business rules in business activities. We also illustrate a ubiquitous event processing system, named ueFilter, which helps to filter and aggregate sensor event, to detect event patterns from sensors and RFID by means of event pattern languages (EPL), and trigger event-condition-action (ECA) in logistics processes.

A new best-relay selection scheme is proposed in this letter in order to maintain a reliable cooperative communications for ubiquitous sensor networks in indoor environments. The suggested technique relies on eigenvalue decomposition to select the best relay. The simulation results confirm that the performance of the proposed approach is better than that of the previous scheme in indoor environments.

A novel peak-to-average power ratio (PAR) control algorithm for feedback-controlled multitone-hopping code-division multiple access (FC/MH-CDMA) signals is proposed. In FC/MH-CDMA, since each chip consists of plural tones, the energy consumption due to a large PAR is not negligible at the transmitter. The proposed PAR control algorithm iteratively constructs a time-frequency code that achieves a preset, target PAR under the condition that all signals are asynchronously transmitted. A PAR of 1 dB is shown to be achievable, and the bit-error rate performance is shown to be only slightly influenced if the target PAR is set to be larger than 3 dB. The influence of quantization is also discussed in terms of its application to limited feedback channels.

Slow development in battery technology and rapid advances in ultra-capacitor design have motivated us to investigate the possibility of using capacitors as the sole energy storage for wireless sensor nodes to support ubiquitous computing. The starting point of this work is TwinStar, which uses ultra-capacitor as the only energy storage unit. To efficiently use the harvested energy, we design and implement feedback control techniques to match the activity of sensor nodes with the dynamic energy supply from environments. We conduct system evaluation by deploying sensor devices under three typical real-world settings -- indoor, outdoor, and mobile backpack under a wide range of system settings. Results indicate our feedback control can effectively utilize energy and ensure system sustainability. Nodes running feedback control have longer operational time than the ones running non-feedback control.

We present a new paging algorithm for wireless networks with ultra-short-range radio access links (picocells). The ubiquitous office (u-office) network is a good example of such a network, and we present some u-office example applications. In addition, we show that conventional paging algorithms are not feasible in such networks. Therefore, we derived a new paging algorithm from the measurement results of an experimental sensor network with short-range wireless links deployed in our office. We equipped persons with sensors and deployed sensor readers at selected places in our office. The sensors transmit messages to the sensor readers at regular intervals. If no sensor reader is in range, the message is lost. Our main observation is that, if a picocell shows an attraction property to a certain person, the residence time of an attached mobile terminal is not gamma distributed (as described in the literature) and the probability of long-lasting residences increases. Thus, if the residence time is larger than a certain threshold, the probability of a long-lasting residence time increases if a sensor reader location has an attraction property to a person. Based on this observation, our proposed paging algorithm registers the location of the mobile terminal only when the residence time in the cell is longer than a predetermined constant. By appropriately setting this constant, we can significantly reduce the registration message frequency while ensuring that the probability of the network successfully connecting to a mobile terminal remains high.

The importance of respiratory monitoring systems during sleep have increased due to early diagnosis of sleep apnea syndrome (SAS) in the home. This paper presents a simple respiratory monitoring system suitable for home use having 3D ranging of targets. The range resolution and azimuth resolution are obtained by a stepped frequency transmitting signal and MIMO arrays with preferred pair M-sequence codes doubly modulating in transmission and reception, respectively. Due to the use of these codes, Gold sequence codes corresponding to all the antenna combinations are equivalently modulated in receiver. The signal to interchannel interference ratio of the reconstructed image is evaluated by numerical simulations. The results of experiments on a developed prototype 3D-MIMO radar system show that this system can extract only the motion of respiration of a human subject 2 m apart from a metallic rotatable reflector. Moreover, it is found that this system can successfully measure the respiration information of sleeping human subjects for 96.6 percent of the whole measurement time except for instances of large posture change.