• IEMEK Journal of Embedded Systems and Applications
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• v.2 no.1
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• pp.24-30
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• 2007

According to development of wireless communication technologies, we need not only high data rate but low data rate system of low power consumption. This low data rate system is utilized in the field of home automation, health care, sensoring and monitoring, etc. IEEE 802.15.4 LR-WPAN system is the best choice for realizing ubiquitous networking system. In this paper SoC Architecture for IEEE 802.15.4 Low Rate WPAN is designed. IEEE 802.15.4 Low Rate WPAN system serves the functions and realization of home area network. We propose the SoC architecture for 868/915MHz frequency band of IEEE 802.15.4 Low Rate WPAN system. The key issue is to design SoC architecture which provides the function of Low Rate WPAN system to meet the requirement of IEEE 802.15.4 standards.

• The Journal of the Korea institute of electronic communication sciences
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• v.11 no.7
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• pp.665-670
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• 2016

In this paper, we suggest the design of OP-AMP using MOSFET in the operation of sub-threshold condition as a basic unit of an IoT. The sub-threshold operation of MOSFET is useful for an ultra low power consumption of sensor network system in the IoT, because it cause the supply voltage to be reduced. From the simulation result using 0.35 um CMOS process, the supply voltage, VDD can be reduced with 0.6 V, open-loop gain of 43 dB and the power consumption was evaluated with about $1.3{\mu}W$ and the active size for an integration was measured with $64{\mu}m{\times}105{\mu}m$. It is expected that the proposed circuit is applied to the low power sensor network for IoT.

• Journal of the Korea Society of Computer and Information
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• v.11 no.1 s.39
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• pp.177-184
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• 2006

The sensors in a ubiquitous network are limited because of the low power and ultra light weight, so many studies have revolved around the sensor. This study improves the process of the registration and authorization and suggests a way to minimize discloser of privacy by using an alias. We introduce RA(Relay Agent) for the restrict function of sensor node, and improve anonymity for private information of each sensor node by assigning alias from SM(Service Manager) in procedure of registration and authentication. The privacy of sensor node is secure in procedure of registration, authentication, and communication between nodes. We could improve the level of security with the only partial increment of computation power of RA and SM without an increase in the amount of sensor nodes.

• Journal of Internet Computing and Services
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• v.11 no.3
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• pp.33-41
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• 2010

The battery consumption and the wireless communication pattern were analyzed for the low power and the improvement of channel interferences between of Zigbee networks and WPAN(Wireless Personal Area Network). The communication patterns considering end device's battery saving during channel searching period were analyzed for low power consumption topology of Zigbee dynamic ad-hoc characteristics. And, the communication patterns were analyzed due to channel interferences between WLAN and Random Back off of Zigbee, too. As a result, the communication patterns of Zigbee's coordinator and end devices is alleviated for the longer battery life time of Zigbee's end device due to Zigbee's end device setting techniques.

• ETRI Journal
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• v.30 no.1
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• pp.33-46
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• 2008

This paper presents the experimental results of a low-power low-cost RF transceiver for the 915 MHz band IEEE 802.15.4b standard. Low power and low cost are achieved by optimizing the transceiver architecture and circuit design techniques. The proposed transceiver shares the analog baseband section for both receive and transmit modes to reduce the silicon area. The RF transceiver consumes 11.2 mA in receive mode and 22.5 mA in transmit mode under a supply voltage of 1.8 V, in which 5 mA of quadrature voltage controlled oscillator is included. The proposed transceiver is implemented in a 0.18 ${\mu}m$ CMOS process and occupies 10 $mm^2$ of silicon area.

• Proceedings of the IEEK Conference
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• 2003.11b
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• pp.61-64
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• 2003

Technological progress in integrated, low-power, CMOS communication devices and sensors makes a rich design space of networked sensors viable. These sensors can be deeply embedded in the physical world and spread throughout sensor network environment like smart dust. So ubiquitous computing will be come true. SmartDust project is the one of ubiquitous computing approach. It produces TinyOS, mote(mica, mica2, rene2, mica2dot, etc.), NesC, TinyDB, etc. We constructs sensor network test bed and tests to approach sensor network and ubiquitous computing.

• Proceedings of the KIEE Conference
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• 2005.10b
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• pp.337-339
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• 2005

The demand for a real-time image surveillance system using network camera server is increasing as the network infra has been grown and digital video compression techniques have been developed. The image surveillance system using network camera server has several merits compared to existing real-time image surveillance system using CCTV. It would be more convenient if wireless realtime image transmission were possible. In this paper, a bluetooth module is designed and implemented for a real-time image surveillance system to send and receive informations wirelessly. It may simplify the system development procedures and increase the productivity by low power consumption, low cost, and simple wireless installation. A scatter-net formation is proposed using dynamic and distributed algorithm so that the network connection is reliable.

• Journal of Industrial Technology
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• v.27 no.B
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• pp.37-42
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• 2007

A mobile ad hoc network (MANET) is a kind of wireless ad hoc network. It is a self-configuring network of mobile nodes connected by wireless links. Infostation is a lower cost and low power system that provides very high bit rate with limited coverage. In this study, we propose search and rescue system that combines MANET of climbers with Infostations. A climber shares location information of climbers with other climbers while climbing, and delivers the information to Infostations. This system is an intermittent network due to the mobility of nodes. From the system, we can track the locations of missing climbers. Ultimately, proposed system achieves low cost and reduces memory requirement using Infestations. We also analyze the performance of the proposed system by simulation. From the performance analysis results, we expect that the proposed system will be very useful to early detect climbers' locations in emergency situations in Korea mountain areas.

• Proceedings of the KIEE Conference
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• 2003.11c
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• pp.476-479
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• 2003

Recently, Bluetooth has been regarded as a new technology for short-range wireless connection. Although initial application of Bluetooth technology has been focused mainly on replacing cables between hand-held devices due to a limited packet size and short-range, general wireless telecommunication such as PAN and Ad hoc networks via Bluetooth-equipped devices is expected to be one of the most popular applications. Wireless equipments have been used to exchange data between host and mobile unit. The exchanging data may be several bytes of control command and the value of sensors with ultra-sonic, vision sensor, and encoder from mobile robot. However, most wireless equipments have some drawbacks such as lack of authentication, large size and high price. On the other hand, the benefits of Bluetooth are small size, low power, low price except short-range. Especially, there are some difficulties when wireless modules are used in indoor environments. In this paper, a method of using wire network in Bluetooth network is investigated as a solution to overcome the short-range problem of Bluetooth and difficulty in indoor environment.

• ETRI Journal
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• v.31 no.3
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• pp.263-270
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• 2009

This paper investigates linear soft combination schemes for cooperative spectrum sensing in cognitive radio networks. We propose two weight-setting strategies under different basic optimality criteria to improve the overall sensing performance in the network. The corresponding optimal weights are derived, which are determined by the noise power levels and the received primary user signal energies of multiple cooperative secondary users in the network. However, to obtain the instantaneous measurement of these noise power levels and primary user signal energies with high accuracy is extremely challenging. It can even be infeasible in practical implementations under a low signal-to-noise ratio regime. We therefore propose reference data matrices to scavenge the indispensable information of primary user signal energies and noise power levels for setting the proposed combining weights adaptively by keeping records of the most recent spectrum observations. Analyses and simulation results demonstrate that the proposed linear soft combination schemes outperform the conventional maximal ratio combination and equal gain combination schemes and yield significant performance improvements in spectrum sensing.