• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.29 no.10A
• /
• pp.1177-1188
• /
• 2004

This paper describes and analyzes the performance of MB-OFDM UWB system that is suggested as one of standards in IEEE 802.15 TG3a for UWB application. UMBchannel model that has been contributed in IEEE 802.15 SG3a is a wideband channel model of 6Ghz bandwidth, so we modify it to have 3 subband channels that are obtained by filtering conventional U Channel, considering center frequency hopping and system bandwidth. From simulations, we compare performances of MB-OFDM system in AWGN and WB channel and verify the frequency and time domain diversity gains from time End frequency spreading technique. We also compare and analyze the performance of proposed SFBC MB-OFDM with that of conventional MB-OFDM system. Simulation results show SFBC MB-OFDM system outperforms conventional MB-OFDM system about 1.5dB of Eb/No at target BER of 10$^{-m4}$./.

• 한국ITS학회:학술대회논문집
• /
• 2010.05a
• /
• pp.43-47
• /
• 2010

• 한국ITS학회:학술대회논문집
• /
• 2010.05a
• /
• pp.188-192
• /
• 2010

• Proceedings of the IEEK Conference
• /
• 2004.06a
• /
• pp.293-296
• /
• 2004

This paper proposes an architecture of channel estimation for multi-band OFDM UWB systems presented to IEEE 802.15.3a by Multi-band OFDM alliance(MBOA). The multi-band OFDM (MB-OFDM) systems should have channel estimation for compensation of signal distortion by multi-band channel. The moving-averaging estimation algorithm and multi-band equalization architecture for MB-OFDM UWB systems proposed in this paper was verified by the simulation. Simulation results show that MB-OFDM system with the proposed architecture have the performance improved by about 3.4 dB compared to system with no channel estimation in 0.1$\pi$ phase-rotated channel.

• Proceedings of the IEEK Conference
• /
• 2004.06a
• /
• pp.23-26
• /
• 2004

This paper analyzed time delay and phase distortion that generates in multipath and the degree of distortion due to power attenuation factor when UWB system is applied at indoor environment and the effects of indoor structure and material on distortion factors. Based on these distortion factors, channel model similar to actual environment is mathematically described and multipath and the degree of signal distortion generated when UWB system is applied to random environment is tested through channel model simulation and varies distortion factor that UWB system needs to consider in different indoor environment is analyzed.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.14 no.11
• /
• pp.2457-2462
• /
• 2010

In this paper, We applied CCI canceller to remove multiple access interference in co-channel environment and improved performance of Impulse Radio UWB system. Also, we have evaluated the performance of UWB system with Truncated Type-II Hybrid ARQ scheme for achieving high quality data transmission.

• Proceedings of the IEEK Conference
• /
• 2007.07a
• /
• pp.185-186
• /
• 2007

In this paper, We propose the selective detection scheme based on pulse repetition considering Bit Error Rate (BER) performance and complexity of noncoherent Ultra Wide Band (UWB) systems. To consider system complexity, the proposed scheme transmits the UWB signals by pulse repetition at the transmitter, like the conventional Pulse Repetition Coding (PRC). However, to effectively improve BER performance of the system the proposed scheme performs selective detection by estimating the Signal-to-Noise Ratio (SNR) of the received pulse-repeated signal at the receiver. Hence, the proposed scheme effectively improves BER performance of the noncoherent UWB systems without increase of the system complexity, as compared to the conventional PRC algorithm.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.33 no.3A
• /
• pp.240-247
• /
• 2008

In this paper, we propose a digitally implementable synchronization method for the UWB system. This is achieved by manipulating the frequency components of a synchronizing signal which is the sequence of pulses of periodicity. We analyze the dependancy of the number of pulses and pulse interval on the intrinsic synchronization accuracy. Moreover, through the computer simulation, the performance of the proposed method is examined via varying system parameters.

• Journal of Korea Multimedia Society
• /
• v.9 no.1
• /
• pp.51-58
• /
• 2006

In this paper, we evaluated Ultra Wideband MC-CDMA system which is the combination of DS-CDMA and OFDM systems, which have been drafting in current standardization for IEEE802.15.3a. Too many Rake Fingers are demanded in the DS-CDMA system to detect multi-path signals, which results in high system complexity. OFDM system fails to qualify for FCC certification unless frequency hopping is off. MC-CDMA has lower complexity compared to DS-CDMA and shows good performance against frequency selective fading. In addition, for a wide-band communication, less radio power per spectrum is allowed in the MC-CDMA system than in an OFDM system. The MC-CDMA system is analyzed by a numerical formula and compared with DS-CDMA and OFDM by a computer simulation.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2003.10a
• /
• pp.488-491
• /
• 2003

UWB communication applications is a recent innovation due to high transmission rate and low power emission. There, we analyzed monopulse's characteristics and simulated the performance for various UWB communication applications. we introduced Time-Hopping method and simulated for MAI removal in multi-user communication.