• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.6 no.3
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• pp.111-121
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• 2007

In this paper, we propose a TH-Multiband-UWB system through pulse shaping to fit in domestic UWB spectrum regulation. We propose the transmission pulse of Multi-Carrier type for pulse shaping and use Cognitive Radio to detect interfering frequency. We use Genetic Algorithm in Cognitive Radio's calculation propose and propose solution of interference problem between TH-UWB using Cognitive Radio and typical MB-OFDM UWB system or other communication systems. In this paper, we explain how Cognitive Engine detects the interfering frequency. The technique of TH-Multiband-UWB system using Cognitive Radio shows a good performance in interference condition.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.9C
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• pp.1306-1315
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• 2004

UWB, which is now in a process of being standardized in WPAN communication, has some problems such as difficulty of implementation and interference with existing systems. To overcome these problems we will explain the MIMO structure to alleviate difficulties of implementation. In this paper we propose the UWB transceiver structure using multiband scheme to mitigate narrow band interference from PCS Of WLAN which is widely used these days and analyze the effect of noise and narrow band interference by simulation based on numerical analysis.

• ETRI Journal
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• v.30 no.6
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• pp.850-852
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• 2008

This letter presents a power efficient 64-state Viterbi decoder (VD) employing a two-stage radix-4 add-compare-select architecture. A class of VD architectures is implemented, and their hardware complexity, maximum operating speed, and power consumption are compared. Implementation results show that the proposed VD architecture is suitable for multiband orthogonal frequency-division multiplexing (MB-OFDM) ultra-wideband (UWB) systems, which can support the data rate of 480 Mbps even when implemented using 0.18-${\mu}m$ CMOS technology.

• Journal of electromagnetic engineering and science
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• v.14 no.1
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• pp.31-35
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• 2014

An ultra-wideband (UWB) circular monopole antenna with a multiband-notched characteristic is proposed. The multiband-notched filter consists of three different sized folded slots, which are distinctly assigned for the notched band at the 3.5-GHz WiMAX, 5-GHz WLAN, and 8-GHz ITU bands. The proposed antenna results in a measured ${\mid}S_{11}{\mid}$ < -10 dB, which completely covers the UWB band (3.1 10.6 GHz) with three notched bands at 3.5, 5.5, and 8.0 GHz. The antenna yields an omnidirectional radiation pattern and high radiation efficiency.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.12
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• pp.69-75
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• 2004

In the paper, system is combined multiband system with DS-UWB techniques with properties including low peak-to-average power ratio, robustness to multiuser interference and excellent security. Because each sub-band is not satisfied with coherence bandwidth, rake receiver in each sub-band is applied to the Proposed system receiver. Output of rake receiver is combined by using Maximal Ratio combining technology. In this paper we mathematically analyse the BER of the DS-UWB system with singleband and multiband systems in the narrow interference channel condition and multi user interference channel condition, the simulation results show that proposed scheme is getting robuster with increasing of the number of subbands.

• 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.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.8C
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• pp.613-616
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• 2008

In this paper, a fine residual frequency offset estimation scheme is proposed for multiband orthogonal frequency division multiplexing ultra-wideband (MB-OFDM UWB) systems. The basic idea of our approach is based on the fact that two adjacent OFDM symbols carry the identical information in the MB-OFDM UWB system, thus removing the need of pilot symbols. The mean square error of the synchronization scheme is evaluated and simulation results are used to verify the effectiveness of the proposed estimator. When compared to the pilot-aided conventional estimator, the proposed estimator has a lower estimation error.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2004.07a
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• pp.439-439
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• 2004

• 전자공학회논문지 IE
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• v.47 no.3
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• pp.35-40
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• 2010

In this paper, we propose an algorithm to improve the precision of initial carrier-frequency offset estimation for multiband-OFDM (MB-OFDM) UWB system which is considering the quantization-noise effect. In the general OFDM system, the two adjacent and repeated preamble symbols are used for the initial carrier-frequency synchronization while the performance of the frequency-offset estimation is bounded by quantization effect generated from analog-to-digital conversion at the receiver. This paper proposes a method in which one-symbol interval between two adjacent preamble symbols for the initial frequency synchronization is extended to multiple-symbol interval between non-adjacent symbols in an extent that phase ambiguity does not occur. In this paper, we also present '6' as optimal multiple symbol interval for the MB-OFDM system with 30 preamble symbols on 3-band hopping and with 4-bit A/D conversion at the receiver. Under the channel environments for the MB-OFDM UWB system, the simulation results show that the proposed estimation algorithm can achieve the initial estimation in offset precision less than 5 ppm.

• Journal of Communications and Networks
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• v.5 no.4
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• pp.374-385
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• 2003

The growing interest towards ultra-wideband (UWB) communications stems from its unique features such as baseband operation, ample multipath diversity, and the potential of enhanced user capacity. But since UWB has to overlay existing narrowband systems, multiple access has to be achieved in the presence of narrowband interference (NBI). However, existing baseband spreading codes for UWB multiple access are not flexible in handling NBI. In this paper, we introduce two novel spreading codes that not only enable baseband UWB multiple access, but also facilitate flexible NBI cancellation. We construct our codes using a single carrier or multiple carriers (SC or MC), which can be implemented with standard discrete-cosine transform (DCT) circuits. With our SC/MC codes, NBI can be avoided by simply nulling undesired digital carriers. Being digital, these SC/MC codes give rise to multiband UWB systems, without invoking analog carriers. In addition, our SC/MC codes enable full multipath diversity, and maximum coding gains. Equally attractive is their capability to reduce the number of interfering users, with simple matched filter operations. Comprehensive simulations are also carried out to corroborate our analysis.