• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.219-222
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• 2004

There are several factors that disturb an Ultra-Wideband (UWB) radio propagation in an indoor environment such as path loss, shadowing and multipath fading. These factors directly affect the quality of the received signal. In this paper, we investigated the influence of the human body shadowing on UWB propagation based on measured wireless channel in an anechoic chamber. The characteristics of the UWB channel including the transmitter and the receiver antenna effects are acquired over the frequency bandwidth of 3${\sim}$11 GHz. The major factors such as the power delay profile (PDP), the angular power distribution (APD), the pulse distortion and the RMS delay spread caused by the human body shadowing are presented.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.6
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• pp.1511-1519
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• 2010

In this paper, we proposed and analyzed a RSSI based cooperative localization algorithm considering wireless propagation characteristics in indoor and outdoor environments for wireless sensor networks, which can estimate the BN position. The conventional RSSI based estimation scheme has low precision ranging due to instability propagation characteristics by time variable. Hence, we implemented ray-launching simulator for analysis of propagation characteristics in 4 case, and experimented proposed localization scheme with 4 RN and 1 to 5 BN. Simulation results show that NLCA has estimation error as 2m-3.5m, however, proposed CLA/ECLA has 1.3m-2.5m/0.5m-1.2m by same environments. Therefore, if we can consider channel characteristics, the proposed algorithm provides higher localization accuracy than RSSI based conventional one.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.5
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• pp.688-693
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• 2022

In this paper, channel propagation path loss was measured in building corridors for frequency bands of 3.7 GHz and 28 GHz, which are used in 5G mobile communication, and compared and analyzed with CI (Close-In) and FI (Floating-Intercept) channel models. To measure the propagation path loss, the measurement was performed while moving the receiver (Rx) from the transmitter (Tx) by 10 m. As a result of the measurement, the PLE (Path Loss Exponent) values of the CI model at 3.7 GHz and 28 GHz were 1.5293 and 1.7795, respectively, and the standard deviations were analyzed as 9.1606 and 8.5803, respectively. In the FI model, 𝛼 values were 79.5269 and 70.2012, 𝛽 values were -0.6082 and 1.2517, respectively, and the standard deviations were 5.8113 and 4.4810, respectively. In the analysis results through the CI model and the FI model, the standard deviation of the FI model is smaller than that of the CI model, so it can be seen that the FI model is similar to the actual measurement result.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.1
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• pp.198-201
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• 2015

The prompt and accurate location determination of the nodes of the wireless indoor shipboard networks is crucial to forming the stable wireless shipboard sensor networks. To this end in this paper it can be achieved through the measurement of the bi-directional channel qualities among the nodes after the locations of the sensor nodes temporarily placed. For the 1st stage the piconet-type sensor networks are considered to measure the channel qualities between a specific node and the cluster node which is the master node. After finishing the 1st stage measurement the nodes needing the relay nodes are selected and the measurement action goes into the 2nd stage. In the 2nd stage the measurement between a candidate relay node and the node needing a relay node starts to begin. After the 2nd stage the relay nodes to connect to the cluster node are fixed and the information delivery paths between a node and the cluster head are established. In this paper the measurement results in the realistic environment are gathered and analysed to show that the measurement procedure can be applied in the wireless indoor shipboard networks.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.48 no.6
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• pp.51-60
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• 2011

Researches on indoor localization using the wireless sensor network have been actively carried out to be used for indoor area where GPS signal is not received. Computationally efficient WCL(Weighted Centroid Localization) algorithm is shown to perform relatively well. However, to get the best performance for WCL all the anchor nodes must send signal with power to cover 96% of the network. The fact that outside the transmission range of the fixed nodes drastic localization error occurs results in large mean error and deviation. Due to these problems the WCL algorithm is not easily applied for use in the real indoor environment. In this paper we propose SRS(Succesive Region Setting) algorithm which sequentially reduces the estimated location area using the signal strength from the anchor nodes. The proposed algorithm does not show significant performance degradation corresponding to transmission range of the anchor nodes. Simulation results show that the proposed SRS algorithm has mean localization error 5 times lower than that of the WCL under free space propagation environment.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.12
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• pp.97-104
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• 2008

Location-based services provide customized information or services according to the user's location. The existing localization schemes for outdoor environment are not applicable to the indoor localization system which requires higher accuracy of location estimation than that of the outdoor localization system. In this paper, we employ the received signal strength(RSS) to approximate the distance between a moving target and a reference point and use the triangulation method to estimate the location of the moving target for the indoor localization system in IEEE 802.15.4 wireless PAN(personal area network). For the indoor localization system, we propose a scheme which selects the best reference points to enhance the localization accuracy and adaptively reflects the changes in propagation environments of a moving target to the distance approximation. Through the implementation of the localization system, we have verified the performance of the proposed scheme in terms of the estimation accuracy.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.11
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• pp.1442-1447
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• 2018

Since the indoor location recognition system using RFID is a method for predicting the indoor position, an error occurs due to the surrounding environment such as an obstacle. In this paper, we plan to reduce errors using back propagation neural networks. The neural network adjusts and trains the connection values between the layers to reduce the error between the actual position of the object with the reader and the expected position of the object through the experiment. In this paper, we propose a method that uses the median method and the radiation method as input to the neural network. Among the two methods, we want to find out which method is more effective in recognizing the actual position in an environment with obstacles and reduce the error. Consequently, the method using the median has less error, and we confirmed that the more the number of data, the smaller the error.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.5
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• pp.416-425
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• 2002

In this Paper, It is analysed 5 GHz frequency characteristics that carry out interference experimental under the indoor environments for understanding propagation interference between existing 5 GHz band wireless communication system and 5 GHz band wireless LAN system. The interference signal which was generated by signal generator injected to 5 GHz Wireless LAN communication system measured interference characteristics and This radio propagation main interference factors were classified received power level separation by interference source frequency and interference source frequency pulse period & width separation. It is measured transmission rate according to variable data and packet size for conforming the quality of 5 GHz band wireless LAN system. We measured the packet data loss rate and power level of received signal and analyzed its frequency characteristics effected by interference signal.

• The KIPS Transactions:PartC
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• v.16C no.5
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• pp.645-652
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• 2009

Location-based service providing the customized information or service according to the user's location has attracted a lot of attention from the mobile communication industry. The service is realized by means of several building blocks, a localization scheme, service platform, application and service. The localization scheme figures out a moving target's position through measuring and processing a wireless signal. In this paper, we propose an adaptive localization scheme in an indoor localization system based on IEEE 802.15.4 standard. In order to enhance the localization accuracy, the proposed scheme selects the best reference points and adaptively reflects the changes of propagation environments of a moving target to approximate distances between the target and the reference points in RSS(Received Signal Strength) based localization system using triangulation. Through the implementation of the localization system, we verify the performance of the proposed scheme in terms of the localization accuracy.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.9 s.339
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• pp.19-28
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• 2005

We establish a statistical model for the ultra-wide bandwidth (UMB) indoor channel based on over 2000 frequency response measurements campaign in a Practical apartment. The approach is based on the investigation of the statistical properties of the multipath profiles measured in different place with different rooms. Based on the experimental results, a characterization of the propagation channel from theoretic view point is described. Also we describe a method for measurement of the channel impulse response and channel transfer function. Using the measured data, the authors compares channel impulse responses obtained from time-domain and channel transfer functions obtained from frequency-domain with statistical path loss model. The bandwidth of the signal used in this experiment is from 10MHz to 8.01 GHz. The time-domain results such as maximum excess delay, men excess delay and ms delay spread are presented. As well as, omni-directional biconical antenna were used for transmitter and receiver In addition, measurements presented here support m channel model including the antenna characteristics.