• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.2 s.344
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• pp.7-15
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• 2006

Recently, Ultra-wideband (UWB) Communication systems have become a popular research topic. UWB system is characterized by the fact that the digital information represented by a subnanosecond pulses is transmitted through the air. In this paper, we consider the PPSM scheme that combine PPM and PSM. We provide the performance in AWGN and SV multipath channel which consists of $CM1\~CM4$. The optimal symbol set for M-ary system in multipath channel which shows good performance is also presented. The simulation results show that the performance in CM4 is worse than that in CMI due to long delay spread, many multipath components, 4-ary system outperforms binary system in Low$E_b/N_0$ but not in high $E_b/N_0$. We find system have the optimal symbol set in multipath channel.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.12 s.103
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• pp.1194-1205
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• 2005

This paper proposes a uni-planar elliptical element UWB antenna with band-notched characteristic and modified pound plane fed by CPW. The antenna achieves VSWR below 2 for UWB band(3.1 GHz${\~}$10.6 GHz). In addition, a band-notched characteristic is achieved by inserting a horizontal slot on the radiation element to avoid the interference with 5 GHz(5.15 GHz${\~}$5.825 GHz) band limited by IEEE 802.1la. The antenna has a thin profile, compact size, and ease of manufacture by adopting a CPW feed structure without any additional background plane. Measured data show that the proposed antenna has good return loss below -10 dB, about 2.1 dB${\~}$4.75 dB maximum gain over the bandwidth, omni-directional radiation patterns, linear phase response.

• ETRI Journal
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• v.35 no.3
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• pp.534-537
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• 2013

A compact monopole antenna excited by a conductor-backed coplanar waveguide (CBCPW) is developed for wireless USB dongle applications. The proposed antenna has a compact dimension of $14mm{\times}47.4mm{\times}3.5mm$, which is suitable for a USB dongle housing. A slotted elliptical patch and a CBCPW with vertical vias are employed to achieve a further size reduction and an improved impedance bandwidth. The measurement result demonstrates that the fabricated antenna resonates from 2.25 GHz to 10.9 GHz, which covers all of the important wireless communication bands, including WiBro (2.3 GHz to 2.4 GHz), Bluetooth (2.4 GHz to 2.484 GHz), WiMAX (2.5 GHz to 2.7 GHz and 3.4 GHz to 3.6 GHz), satellite DMB (2.605 GHz to 2.655 GHz), 802.11b/g/a WLAN (2.4 GHz to 2.485 GHz and 5.15 GHz to 5.825 GHz), and ultra-wideband (3.1 GHz to 10.6 GHz) services. The radiation characteristics of the proposed antenna when attached to a laptop are tested to investigate the influence of the keypad and the LCD panel of the laptop.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.5
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• pp.162-167
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• 2009

In this paper, we present a compact Ultra-Wideband band-pass filter using a high-pass filter and low-pass filter. The structure of our proposed band-pass filter is very simple and the DGS(Defected Ground Structure) structure is used to get the low-pass filter characteristic. Our proposed band-pass filter can be much smaller than a cascaded filter. As a result of measurement the insertion loss is less than 0.5dB throughout the pass-band of $2.1GHz{\sim}10.56GHz$, the return loss is more than 20dB and the group delay maximum variation is 0.23ns from 0.12ns to 0.35ns.

• ETRI Journal
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• v.34 no.2
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• pp.175-183
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• 2012

Conventional synchronization algorithms for impulse radio require high-speed sampling and a precise local clock. Here, a phase-locked loop (PLL) scheme is introduced to acquire and track periodical impulses. The proposed impulse PLL (iPLL) is analyzed under an ideal Gaussian noise channel and multipath environment. The timing synchronization can be recovered directly from the locked frequency and phase. To make full use of the high harmonics of the received impulses efficiently in synchronization, the switching phase detector is applied in iPLL. It is capable of obtaining higher loop gain without a rise in timing errors. In different environments, simulations verify our analysis and show about one-tenth of the root mean square errors of conventional impulse synchronizations. The developed iPLL prototype applied in a high-speed ultra-wideband transceiver shows its feasibility, low complexity, and high precision.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.05a
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• pp.563-567
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• 2002

본 논문에서는 UWB/TH(Ultra Wideband/Time Hopping：이하 Impulse Radio) 시스템을 의사 잡음 부호 발생기에 의해 생성된 시간 도약 패턴을 사용하여 시간 영역에서 다인 접속 간섭이 배제되는 경우에 대해 동일 주파수 대역을 사용하는 기존 시스템에 의한 간섭 발생시 IR 시스템의 성능을 분석하였다. 간섭 점유율이 0.1 이하인 경우는 5GHz 대역에서 ISM 대역의 80MHz 대역폭이나 802.11a의 사용대역폭 20MHZ와 같은 IR(Impulse Radio) 시스템에 비해 매우 협소한 대역을 사용하는 경우로써 향후 5-10GHz 대역에서 공유되는 IR 시스템에서 간섭으로 영향을 미칠 경우를 상정하여 분석하였다. 결과에 의하면, IR 전체 대역폭에서 간섭 점유율이 클수록 시스템 성능이 크게 열화되고 부분대역 간섭 자체가 시스템 성능을 크게 열화 시킴을 알 수 있었다. SIR 30dB 이하에서 간섭 점유율이 0.1 이상 일 때는 SIR이 증가할수록 성능 향상폭이 커지지만 점유율이 0.1 이하에서는 l$\times$10­$^1$1이하의 성능개선이 이루어지고 30dB 이상에서는 일정 성능을 유지함을 알 수 있었다. 또한, 간섭 전력의 증가면에서는 간섭 점유율이 적을수록 거의 영향이 미치지 않았다. 따라서, IR시스템에서는 간섭의 전력면 보다는 간섭의 점유 대역폭에 따라서 성능 열화가 크게 나타남을 알 수 있었다.

• Journal of Communications and Networks
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• v.14 no.5
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• pp.501-509
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• 2012

This paper proposes a joint timing synchronization, channel estimation, and data detection for the impulse radio ultra-wideband systems. The proposed timing synchronizer consists of coarse and fine timing estimation. The synchronizer discovers synchronization points in two stages and performs adaptive threshold based on the maximum pulse averaging and maximum (MAX-PA) method for more precise synchronization. Then, iterative channel estimation is performed based on the discovered synchronization points, and data are detected using the selective rake (S-RAKE) detector employing maximal ratio combining. The proposed synchronizer produces two signals-the start signal for channel estimation and the start signal for start frame delimiter (SFD) detection that detects the packet synchronization signal. With the proposed synchronization, channel estimation, and SFD detection, an S-RAKE receiver with binary pulse position modulation binary phase-shift keying modulation was constructed. In addition, an IEEE 802.15.4a channel model was used for performance comparison. The comparison results show that the constructed receiver yields high performance close to perfect synchronization.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.7 s.98
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• pp.709-719
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• 2005

The forward link of the 3 G CDMA system may become limited under the increasing of the number of users. The conventional channelization code, Walsh code, has not enough sizes for much possible non, therefore, the quasi orthogonal function(QOF), which process optimal cross-correlation with Walsh code, is considered. In this paper, we investigate quasi orthogonal function on Jacket matrices, which can lead lower correlations values and better performance in 3 G CDMA system. Moreover, to simple the detector and improve the BER performance, a novel detection for QOF CDMA system is proposed. Finally, the simple recursive generation of the bent sequences for QOF mask function is discussed.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.7
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• pp.3-9
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• 2013

This paper proposes a selective-weighted energy detection (S-WED) and a synchronization algorithm appropriate for it in IR-UWB system. Energy detectors that are practical in terms of implementation are employed widely for noncoherent reception in IR-UWB systems. However, they show low performance due to using the energy samples captured at symbol rate. For this reason, weighted energy detectors are developed to improve the performance of EDs. Hence, for WED, not only synchronization but also the weight coefficients are needed to be obtained prior to data detection. Meanwhile, the optimal weighting coefficients of WEDs are known to be energy values. Therefore, synchronization and the weighting coefficients can be obtained simultaneously. This paper proposes an S-WED and a simple synchronization algorithm for it in which sub-intervals having energies under a certain level are excluded in energy accumulation resulting in a simpler WED with a bit performance increase in low SNR region. The proposed algorithm is verified through simulations using the preamble symbol and channel models defined in the IEEE 802.15.4a.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.7A
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• pp.669-681
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• 2010

In this paper, we analyze the active RFID system ISO/IEC 18000-7. In order to apply to USN, which consists active RFID tags and sensor nodes, we propose UWB-based Class 4 active RFID protocol using active RFID relay tag as relay AP. To compare the performance between the existing ISO/IEC 18000-7 system and the proposed system, we introduce sensitivity-based measurement of achieved coverage and system efficiency. Also, we analyze the performance of the proposed system and compare it with that of the existing system through MCL analysis and SLS analysis.