• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.4
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• pp.53-60
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• 2011

In Wireless Sensor Networks, IEEE 802.11 happen unnecessary energy consume because of packet transmission using maximum power between sensor node. The BASIC scheme is to use maximum transmission power for RTS-CTS and minimum required transmission power so as to high energy efficiency for DATA-ACK. However BASIC scheme may degrade network throughput with collision of ACK packet by node in carrier sensing zone and may result in higher energy consumption than when using IEEE 802.11 without power control. Existing PCM(Power Control MAC) scheme is to use DATA packet transmission method by periodically maximum power level so as to sensing DATA packet transmit in carrier sensing zone of transmission node, and this method can avoid collision of ACK packet. This paper present problem by energy efficiency of PCM scheme, and design some more improved PCM scheme.

• Journal of Digital Convergence
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• v.11 no.12
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• pp.447-452
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• 2013

Berkley Media Access Control (B-MAC) protocol is one of the well-known MAC protocols, which uses adaptive preamble sampling scheme and is designed for wireless sensor networks (WSN). In this paper, we are reviewed about security vulnerability in B-MAC, and analyzed the power which is consumed at each stage of B-MAC protocol according to vulnerability of denial of sleep(DoS) and replay problem. From our analytical results, it can be considered the need of power efficient authentication scheme which provides the reliability, efficiency, and security for a general B-MAC communication. This is the case study of possible DoS vulnerability and its power consumption in B-MAC.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.10 no.5
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• pp.60-70
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• 2011

Vehicle location detection and wireless communication method have be designed along the same lines as GPS, CDMA and WLAN, which is based upon the selecting factors such as state-of-art technology trend, accuracy, stability, and economic feasibility, in order to select the optimum method of information communication networks for integrated "Transportation-Power-Facilities" on the electric bus. In addition, the key features of each alternative for an efficient linkage have been review and the integration methodology for linking among Transportation Charging Center, Transportation(ITS, BIS) Center and smart Grid Center has been drawn up based on a technical level of difficulty of each alternative, political and administrative difficulties, and expense justification.

• Journal of Communications and Networks
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• v.16 no.1
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• pp.36-44
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• 2014

Exploiting the energy-delay tradeoff for energy saving is critical for developing green wireless communication systems. In this paper, we investigate the delay-constrained energy-efficient packet transmission. We aim to minimize the energy consumption of multiple randomly arrived packets in an additive white Gaussian noise channel subject to individual packet delay constraints, by taking into account the practical on-off circuit power consumption at the transmitter. First, we consider the offline case, by assuming that the full packet arrival information is known a priori at the transmitter, and formulate the energy minimization problem as a non-convex optimization problem. By exploiting the specific problem structure, we propose an efficient scheduling algorithm to obtain the globally optimal solution. It is shown that the optimal solution consists of two types of scheduling intervals, namely "selected-off" and "always-on" intervals, which correspond to bits-per-joule energy efficiency maximization and "lazy scheduling" rate allocation, respectively. Next, we consider the practical online case where only causal packet arrival information is available. Inspired by the optimal offline solution, we propose a new online scheme. It is shown by simulations that the proposed online scheme has a comparable performance with the optimal offline one and outperforms the design without considering on-off circuit power as well as the other heuristically designed online schemes.

• Journal of IKEEE
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• v.15 no.3
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• pp.227-234
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• 2011

The Interest in robotics has been steadily increasing in recent times both in Korea as well as abroad. Research on robots for new and diverse fields is ongoing. This study discusses the current research and development on robot actuator, which are used to control the joints of robots, and focuses on developing more efficient technology for joint control, as compared with the current technologies. It also aims to find means to apply the abovementioned technology to diverse industrial fields. We found that easy and effective control of actuators could be achieved by using ZigBee sensor networks, which were widely being used on wireless communications. Throughout the experiments it is proved that the developed wireless actuator could be used for easy control of various robot joints. This technology can be effectively applied to develop two-legged robots that will be able to walk like human, or even quadruped and hexapod robots. It can also be applied to motors used in industry. In this study, we develop an extremely minimized ZigBee sensor network module that can be used to control various servo motors with low power consumption even if it is long distances. We realized effective wireless control by optimizing the ZigBee antenna, and were able to quickly check the status of relevant Tree node through mutual communication between the servo motors composing the ZigBee sensor network and the main server control modules. The developed Servo Motor with ZigBee sensor network modules can be applied in both robotics as well as for home or factory automation.

• Journal of the Korea Society for Simulation
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• v.17 no.1
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• pp.17-22
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• 2008

Double-binary turbo code has been adopted as an error control code of various future communication systems including wireless metropolitan area networks(WMAN) due to its powerful error correction capability. One of the components affecting the performance of turbo code is internal interleaver. In 802.16 d/e system, an almost regular permutation(ARP) interleaver has been included as a part of specification, however it seems that the interleaver is not optimized in terms of decoding performance. In this paper, we propose three optimization methods for the interleaver based on spatial distance, spread and minimum distance between original and interleaved sequence. We find optimized interleaving parameters for each optimization method and evaluate the performances of the proposed methods by computer simulation under additive white Gaussian noise(AWGN) channel. Optimized parameters can provide up to 1.0 dB power gain over the conventional method and furthermore the obtainable gain does not require any additional hardware complexity.

• International Journal of Internet, Broadcasting and Communication
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• v.14 no.2
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• pp.23-29
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• 2022

To improve spectrum and energy efficiency in the fifth generation (5G) wireless channels, intelligent reflecting surface (IRS) transmissions have been envisioned, possibly towards the sixth generation (6G) networks. In this paper, we analyze the bit-error rate (BER) performance of intelligent reflecting surface (IRS) assisted non-orthogonal multiple access (NOMA) systems. First, we derive a closed-form expression of the BER in terms of Q functions. Then we analyze the BER improvement of the IRS NOMA system over the conventional NOMA system with respect to the power allocation. Furthermore, we also demonstrate numerically the BER improvement of the IRS NOMA network over the conventional NOMA network in respect of the number of reflecting devices.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.10a
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• pp.527-530
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• 2010

WSN is composed of a lot of small sensors with the limited hardware resources. In WSN, at the initial stage, sensor nodes are randomly deployed over the region of interest, and self-configure the clustered networks by grouping a bunch of sensor nodes and selecting a cluster header among them. Specially, in WSN environment, in which the administrator's intervention is restricted, the self-configuration capability is essential to establish a power-conservative WSN which provides broad sensing coverage and communication coverage. In this paper, we propose a communication coverage-aware cluster head election algorithm for Herearchical WSNs which consists of communication coverage-aware of the Base station is the cluster head node is elected and a clustering.

• Journal of Information Technology Applications and Management
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• v.12 no.4
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• pp.93-104
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• 2005

Recently, RFID/USN is one of fundamental technologies in information and communications networks. Low-Rate WPAN, IEEE802.15.4 is a low-cost communication network that allows wireless connectivity in applications with limited Power and relaxed throughput requirements. Its applications are building automation, personal healthcare, industrial control, consumer electronics, and so on. Some applications require location information. Of course location awareness is useful to improve usability of data Low-Rate WPAN Is regarded as a key specification of the sensor network with the characteristics of wireless communication, computing, energy scavenging, self-networking, and etc. Unfortunately ZigBee alliance propose a lot of applications based on location aware technologies, but the specification and low-rate WPAN devices don't support anything about location-based services. RSSI ( Received Signal Strength indication) is for energy detection to associate, channel selection, and etc. RSSI is used to find the location of a potable device in WLAN. In this paper we studied indoor location awareness using vector matching of RSSI in low-Rate wireless PAN. We analyzed the characteristics of RSSI according to distance and experimented location awareness. We implemented sensor nodes with different shapes and configured the sensor network for the location awareness with 4 fixed nodes and a mobile node. We try to contribute developing location awareness method using RSSI in 3-dimension space.

• Journal of Korea Society of Digital Industry and Information Management
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• v.11 no.3
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• pp.91-98
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• 2015

There is a new evolution in technological advancement taking place called the Internet of Things (IoT), The IoT enables physical world objects in our surrounding to be connected to the Internet. ISM (Industrial Scientific Medical) band that is 2.4GHz band authorized free of charge is being widely used for smart devices. Accordingly studies have been continuously conducted on the possibility of coexistence among nodes using ISM band. In particular, the interference of IEEE 802.11b based Wi-Fi devices using overlapping channel during communication among IEEE 802.15.4 based wireless sensor nodes suitable for low-power, low-speed communication using ISM band. Because serious network performance deterioration of wireless sensor networks. In this paper, we will propose an algorithm that identifies the possibility of using more accurate channels by mixing utilization of interference signal and RSSI (Received Signal Strength Indicator) Min/Max/Activity of Interference signal by wireless sensor nodes. In addition, it will verify our algorithm by using OPNET Network verification simulator.