• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.215-216
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• 2008

Ultra wideband (UWB) system is one of the promising solutions for future short-range communication which has recently received a great attention by many researchers. In this paper, we proposed 128-point low power FFT structure based on the memory for UWB systems. The proposed structure can improve implementation area and power consumption efficiency as it consists of one of the butterfly PE and a little memory.

• Journal of Information Processing Systems
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• v.10 no.3
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• pp.412-428
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• 2014

Request oriented sensor networks have stricter requirements than conventional event-driven or periodic report models. Therefore, in this paper we propose a minimum energy data aggregation (MEDA), which meets the requirements for request oriented sensor networks by exploiting a low power real-time scheduler, on-demand time synchronization, variable response frame structure, and adaptive retransmission. In addition we introduce a test bed consisting of a number of MEDA prototypes, which support near real-time bidirectional sensor networks. The experimental results also demonstrate that the MEDA guarantees deterministic aggregation time, enables minimum energy operation, and provides a reliable data aggregation service.

• Journal of information and communication convergence engineering
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• v.9 no.6
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• pp.652-656
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• 2011

In this paper, a transmitter-based multipath processing and inter-channel interference (ICI) cancellation scheme for a ultra-wideband (UWB) spatial multiplexing (SM) multiple input multiple output (MIMO) system is presented. It consists of taps delayed lines and zero-forcing (ZF) filters in the transmitter and correlators in the receiver. For a UWB SM MIMO system with N transmit antennas, M receive antennas, and Q resolvable multipath components, the BER performance of a linear transmit ZF scheme is analyzed in a log-normal fading channel and also compared with that of a receiver-based ICI rejection approach. It is found that when M ${\leq}$ N, the transmit ZF processing approach outperforms the ZF receiver while making the mobile units low-cost and low-power.

• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.1963-1966
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• 2004

An ultra wide band ultra-high frequency (UHF) signal processing module was designed for on-line UHF partial discharge (PD) monitoring systems for gas-insulated switchgears (GIS). Major advantage of the unit is an improved PD detection sensitivity through minimizing the effect of surrounding interference signals. The detection sensitivity of the unit was <-60 dBm that is sufficient to detect UHF PD signals as low as 1 pC. Precise detection of PD occurred in the GIS, due to internal defects, is possible by using the signal processing unit.

• Proceedings of the KIEE Conference
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• 2004.05b
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• pp.128-131
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• 2004

An ultra wide band ultra-high frequency (UHF) signal processing module was designed for on-line UHF partial discharge (PD) monitoring systems for gas-insulated switchgears (GIS). Major advantage of the unit is an improved PD detection sensitivity through minimizing the effect of surrounding interference signals. The detection sensitivity of the unit was <-60 dBm that is sufficient to detect UHF PD signals as low as 1 pC. Precise detection of PD occurred in the GIS, due to internal defects, is possible by using the signal processing unit.

• JSTS:Journal of Semiconductor Technology and Science
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• v.15 no.2
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• pp.194-201
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• 2015

A frequency modulated ultra-wideband (FM-UWB) transmitter with a high-robust relaxation oscillator for subcarrier generation and a dual-path Ring VCO for RF FM is proposed, featuring low power and low complexity. A prototype 3.65-4.25 GHz FM-UWB transceiver employing the presented transmitter is fabricated in $0.18{\mu}m$ CMOS for short-range wireless data transmission. Experimental results show a bit error rate (BER) of $10^{-6}$ at a data rate of 12.5 kb/s with a communication distance of 60 cm is achieved and the power dissipation of 4.3 mW for the proposed transmitter is observed from a 1.8 V supply.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.1826-1829
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• 2005

Recent advancement in wireless communications and electronics has enabled the development of low power sensor network. Wireless sensor network are often used in remote monitoring control applications, health care, security and environmental monitoring. Wireless sensor networks are an emerging technology consisting of small, low-power, and low-cost devices that integrate limited computation, sensing, and radio communication capabilities. Sensor network platform for health care has been designed, fabricated and tested. This system consists of an embedded micro-controller, Radio Frequency (RF) transceiver, power management, I/O expansion, and serial communication (RS-232). The hardware platform uses Atmel ATmega128L 8-bit ultra low power RISC processor with 128KB flash memory as the program memory and 4KB SRAM as the data memory. The radio transceiver (Chipcon CC1000) operates in the ISM band at 433MHz or 916MHz with a maximum data rate of 76.8kbps. Also, the indoor radio range is approximately 20-30m. When many sensors have to communicate with the controller, standard communication interfaces such as Serial Peripheral Interface (SPI) or Integrated Circuit ($I^{2}C$) allow sharing a single communication bus. With its low power, the smallest and low cost design, the wireless sensor network system and wireless sensing electronics to collect health-related information of human vitality and main physiological parameters (ECG, Temperature, Perspiration, Blood Pressure and some more vitality parameters, etc.)

• Journal of Communications and Networks
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• v.5 no.4
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• pp.344-353
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• 2003

Ultra-wideband (UWB) technology is gaining increasing interest for its potential application to short-range indoor wireless communications. Utilizing ultra-short pulses, UWB baseband transmissions enable rich multipath diversity, and can be demodulated with low complexity receivers. Compliance with the FCC spectral mask, and interference avoidance to, and from, co-existing narrow-band services, calls for judicious design of UWB pulse shapers. This paper introduces pulse shaper designs for UWB radios, which optimally utilize the bandwidth and power allowed by the FCC spectral mask. The resulting baseband UWB systems can be either single-band, or, multi-band. More important, the novel pulse shapers can support dynamic avoidance of narrow-band interference, as well as efficient implementation of fast frequency hopping, without invoking analog carriers.

• Smart Structures and Systems
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• v.6 no.5_6
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• pp.675-687
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• 2010

Structural Health Monitoring (SHM) is the science and technology of monitoring and assessing the condition of aerospace, civil and mechanical infrastructures using a sensing system integrated into the structure. Impedance-based SHM measures impedance of a structure using a PZT (Lead Zirconate Titanate) patch. This paper presents a low-power wireless autonomous and active SHM node called Autonomous SHM Sensor 2 (ASN-2), which is based on the impedance method. In this study, we incorporated three methods to save power. First, entire data processing is performed on-board, which minimizes radio transmission time. Considering that the radio of a wireless sensor node consumes the highest power among all modules, reduction of the transmission time saves substantial power. Second, a rectangular pulse train is used to excite a PZT patch instead of a sinusoidal wave. This eliminates a digital-to-analog converter and reduces the memory space. Third, ASN-2 senses the phase of the response signal instead of the magnitude. Sensing the phase of the signal eliminates an analog-to-digital converter and Fast Fourier Transform operation, which not only saves power, but also enables us to use a low-end low-power processor. Our SHM sensor node ASN-2 is implemented using a TI MSP430 microcontroller evaluation board. A cluster of ASN-2 nodes forms a wireless network. Each node wakes up at a predetermined interval, such as once in four hours, performs an SHM operation, reports the result to the central node wirelessly, and returns to sleep. The power consumption of our ASN-2 is 0.15 mW during the inactive mode and 18 mW during the active mode. Each SHM operation takes about 13 seconds to consume 236 mJ. When our ASN-2 operates once in every four hours, it is estimated to run for about 2.5 years with two AAA-size batteries ignoring the internal battery leakage.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.7A
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• pp.682-687
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• 2010

The IEEE 802.15.4a specification targets the low-rate (LR) Impulse-radio (IR) ultra-wideband (UWB) system which is now widely applied in the WPANs considering rather short distance communications with low complexity and power consumption. The physical (PHY) layer uses concatenated coding with mixed binary phase-shift keying and binary pulse-position modulation (BPSK-BPPM), and direct sequence spreading with time hopping in order that both coherent and non-coherent receiver architectures are supported. In this paper, the performances of multiple access schemes compliant with IEEE 802.15.4a specification are investigated with energy detection receiver, which allow avoiding the complex channel estimation needed by a coherent receiver. However, the performance of energy detection receiver is severely degraded by multi-user interference (MUI), which largely diminishes one of the most fascinating advantages of UWB, namely robustness to MUI as well as the possibility to allow parallel transmissions. So as to improve the performance of multiple access schemes, we propose to apply the novel TH sequences as well as to increase the number of TH positions. The simulation results show that our novel multiple access schemes significantly improve the performance against MUI.