• Journal of Communications and Networks
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• v.5 no.4
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• pp.309-318
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• 2003

This paper presents an in-depth study of a UWB indoor radio channel between 1 and 9 GHz, which was used for the subsequent development of a new statistical UWB multipath channel model, focusing on short range indoor scenarios. The channel sounding process was carried out covering different indoor environments, such as laboratories, halls or corridors. A combination of new and traditional parameters has been used to accurately model the channel impulse response in order to perform a precise temporal estimation of the received pulse shape. This model is designed specifically for UWB digital systems, where the received pulse is correlated with an estimated replica of itself. The precision of the model has been verified through the comparison with measured data from equivalent scenarios and cases, and highly satisfactory results were obtained.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.10a
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• pp.807-810
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• 2007

Recently, ultra-wideband (UWB) technology based on the transmission of short duration pulses has gained much interest for its application to wireless communications. UWB small scale channel modeling work, including statistical characterization and potential models, are discussed. The significance, in terms of performance, of the channel impulse response model chosen for the simulation of UWB communications systems is also evaluated. Three traditional models are found to be useful for modeling NLOS UWB channels, but not LOS channels. In this paper, a new model for LOS UWB channels is presented and shown to represent LOS channels much more accurately than the traditional models.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.11C
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• pp.949-954
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• 2008

An ultrawide band (UWB) signal model is proposed to estimate the angle-of-arrivals of the signals arrived in clusters at an UWB receiver for a short-range, high-speed, indoor wireless communication system in an elliptical scattering environment. And a new estimation technique is proposed by modifying the conventional MUSIC algorithm. By using this estimation technique, the estimates of the two unknown parameter sets, angle-of-arrivals and distribution parameters, are obtained with the proposed UWB signal model. The proposed UWB signal model and estimation technique are verified through computer simulations in an ultrawide band communication environment.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.7B
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• pp.1058-1065
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• 2010

In the recent, the importance of ubiquitous-related technique is increased as many companies and researchers make an effort to create a new service model using ubiquitous computing and network technologies. Especially, the research of indoor location recognition has gained a lot of interest because it is a critical component for supporting ubiquitous services. Nevertheless, the simulation tool for indoor location recognition hardly has studied compared to their importance. In this paper, we propose a Ptolemy-based simulator over UWB channel that provides short-range and high-bandwidth communication. Finally, we conduct experiments using the proposed simulator and analyze the performance of various location recognition algorithms.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.3
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• pp.648-653
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• 2011

We propose a new frequency offset estimation technique for multiband orthogonal frequency modulation (MB-OFDM) based ultra wideband (UWB) systems. The proposed frequency offset estimation technique is related to the scheme of Schmidl for channel model 1 (4-1Om NLOS, rms. delay =14.3ns.) using more than two symbols and with alternate symbols. Variance of frequency offset estimate obtained from the proposed frequency offset estimation technique approaches very nearing to Cramer Rao Lower Bound (CRLB) in an AWGN channel. BER performance of the proposed technique is also presented.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.4
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• pp.494-500
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• 2020

This paper proposes a new distance estimation technique for indoor localization in ultra wideband (UWB) systems. The proposed technique is based on recurrent neural network (RNN), one of the deep learning methods. The RNN is known to be useful to deal with time series data, and since UWB signals can be seen as a time series data, RNN is employed in this paper. Specifically, the transmitted UWB signal passes through IEEE802.15.4a indoor channel model, and from the received signal, the RNN regressor is trained to estimate the distance from the transmitter to the receiver. To verify the performance of the trained RNN regressor, new received UWB signals are used and the conventional threshold based technique is also compared. For the performance measure, root mean square error (RMSE) is assessed. According to the computer simulation results, the proposed distance estimator is always much better than the conventional technique in all signal-to-noise ratios and distances between the transmitter and the receiver.

• The Journal of the Korea Contents Association
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• v.7 no.1
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• pp.147-154
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• 2007

In this paper, we propose a new parallel search algorithm to acquire synchronization for UWB(Ultra Wideband) systems that reduces computation of the correlation. The conventional synchronization acquisition algorithms check all the possible signal phases simultaneously using multiple correlators. However it reduces the acquisition time, it makes high power consumption owing to increasing of correlation. The proposed algorithm divides the preamble signal to input the correlator into an m-bit bunch. We check the result of the correlation at first stage of an m-bit bunch data and predict whether it has some synchronization acquisition information or not. Thus, it eliminates the unnecessary operation and save the number of correlation. We evaluate the proposed algorithm under the AWGN and the multi-Path channel model with MATLAB. The proposed parallel search scheme reduces number of the correlation 65% on the AWGN and 20% on the multi-path fading channel.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.2C
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• pp.145-152
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• 2009

Ultra-wideband communication systems for impulse radio have merits that are possible for either high resolution ranging system or radio determination. Conventionally, in order to accomplish these functions, the rapid analog to digital convertor (ADC) is necessary to apply radio determination system operating in time domain. However, considering that low rate - wireless personal area network (LR-WPAN) aims to low-cost hardware implementation, the expensive ADC converting GHz sampling per second is not appropriate. So, this paper introduces the high resolution ranging system operating in frequency domain with using low sampling rate ADC, and a new non-coherent ranging scheme utilizing analog Frequency Modulation (FM) mode for the frequency domain transformation. To verify the superiority of the proposed ranging algorithm working in frequency domain, the suggested IEEE 802.15.4a TG channel model is used to exploit affirmative features of the proposed algorithm with conducting the simulation results.