• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.3C
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• pp.224-231
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• 2003

In this paper we proposed system parameter values of ultra-wideband Impulse Radio systems for the frequency band(3.1~10.6GHz), which is allocated by Federal Communications Commission(FCC). We also analyzed performance of the proposed system in the multiple access interference environment. According to result, application of possible pulse duration($t_{n}$) is very limited by 0.04~0.0326 ns in permission frequency range that establish in FCC. In the case of the same pulse signal power, we could know that system performance was changed by pulse repetition number($N_{s}$ ) regardless of pulse duration. Thus, We could know that we have to need duration of monocycle pulse and setting of frame un it time(Τ$_{f}$ ) according to multi user numbers and design proper pulse repetition number by transfer rate in multiple access systems design. In the IR system that needs high speed transmission more than 50 Mbps in multiple access interference environment, we could know that very serious performance decrease by multiple access interference happens. Therefore, as the design of high speed multiple access IR system, it should be designed to additional improvement techniques that can remove multiple access interference at the same time.

• The Journal of Information Technology
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• v.4 no.3
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• pp.65-75
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• 2001

Code-division multiple access has been widely accepted as the major multiple access scheme in mobile communication systems. Wide-band CDMA and its hybrid associate time-division CDMA are key elements in the mobile communication. Since 10 years ago, there has been enormous research activity in analysis of the capacity of these CDMA-based systems. Recently, upgrading service, high quality and the different service classes in radio resource allocation has recently increased. This paper presents an overview of Radio Resource Allocation on the CDMA-based systems that are flexible, support traffic services, minimize call blocking rate and have acceptable radio resource utilization.

• Journal of Korea Society of Industrial Information Systems
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• v.6 no.1
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• pp.15-23
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• 2001

In this paper, we propose a system to cancel the multi-user interference of synchronous BPSK DS/CDMA systems. In this CDMA scheme, the spectrum of the user's signal is directly spread by means of the Simplex code or the phase offsetted PN code. But in arbitrary bit interval, we use the one spreading code of the Simplex code and the phase offsetted PN code. The receiver cancel the multi-user interference and demodulate information bits by using reference correlator. This paper presents a interference cancellation model and analyzes this system mathematically. The suggested system show that the interference resulting from other users are remarkably reduced. In AWGN and Nakagami fading environment we analyze interference generated from other users and compare the resulting performance with that of the conventional receiver in same user side.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.7B
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• pp.1021-1033
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• 2001

본 논문에서는 초광대역 시간 도약 임펄스 무선 전송 (ultra wideband time hopping impulse radio) 다원 접속 시스템을 위한 잡음 부호 기반의 새로운 시간 도약 시퀀스를 제안한다. 임펄스 무선 전송 시스템에 대한 지금까지의 연구에서는 대부분 이상적인 랜덤 시간 도약 시퀀스를 사용하여 여러 사용자가 다원 접속한다고 가정하였다. 본 논문에서는 동일 차수의 다수 m-시퀀스와 십진화기를 이용하여 구현 가능한 시간 도약 시퀀스를 제안하고, 여러 사용자의 동기식 및 비동기식 접속 상황에 대한 모의 실험을 통해 이상적인 랜덤 시퀀스와 유사한 우수한 비트오율 성능을 얻을 수 있음을 확인하였다. 또한 제안된 시간 도약 시퀀스를 사용하는 경우 좀 더 일반적인 상황인 비동기식 다원 접속이 동기식 다원 접속에 비해 우수한 성능을 얻을 수 있음을 분석한다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.11a
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• pp.177-181
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• 2002

본 논문에서는 FCC에서 제정한 허용 주파수 3.1-10.6GHz 대역 내에서 사용 가능한 모노펄스를 이용하여 PPM 변조된 TH IR 시스템 시뮬레이터를 설계하고 시뮬레이터를 이용하여 모노사이클 펄스 특성 및 시스템 성능을 분석하였다. 또한, 제안한 파라미터를 이용하여 다원접속 간섭 환경에서 IR 시스템의 오율 성능을 분석하였다.

• Proceedings of the Korea Information Processing Society Conference
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• 2000.10b
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• pp.1211-1214
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• 2000

의사잡음(PN) 부호는 이상적인 자기상관특성을 갖지 못한다. 본 논문에서는 이상적인 자기상관 특성을 갖지 못하는 PN 부호에 대하여 이상적인 자기상관 특성을 가지도록 하여 동기 직접확산 부호분할 다원접속(DS/CDMA)시스템에서 부가적인 하드웨어 복잡성의 큰 증가 없이 간섭제거가 가능한 수신기 구조를 제안한다. PN 부호 오프셋을 사용하여 사용자 부호를 할당하고, 제안한 수신기 알고리즘을 PN 부호 오프셋을 사용한 시스템에 적용하여 다원접속 간섭 신호가 제거됨을 보이며 컴퓨터 모의실험을 통하여 이를 확인한다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.6 no.7
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• pp.1032-1037
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• 2002

In this paper, derived monocycle pulse that application is possible within permission frequency band (3.1 ~ 10.6GHz) that establish in FCC. Also, PPM modulated TH IR system simulator is designed in AWGN environment. It is analyzed monocycle pulse specific property and system performance using simulator. Also, analyzed BER performances of IR system in multiple access interference environment using proposed parameters. According to result, application of possible pulse duration$(t_n)$ is very limited by 0.04~0.0326 ns in permission frequency range that establish in FCC. In the case of same pulse signal power, we could know that system performance changes by $N_s$ regardless of pulse duration. IR system that need high speed transmission more than 50 Mbps in multiple access interference environment could know that very serious performance decrease by multiple access Interference happens.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.2C
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• pp.187-198
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• 2004

In this paper, we analyze the performance of BPM (Bi-Phase Modulation) UWB (Ultra Wide Band) multiple access system using PN (Pseudo Noise) code based time hopping sequence in indoor wireless channels. In particular, we compare BPM UWB multiple access system with PPM (Pulse Position Modulation) UWB multiple access system in terms of signalling and demodulation schemes. Moreover, we analytically evaluate the performance of these UWB systems by deriving the bit error rate expressions under the assumption that pulse energy and data transmission rate are identical for both systems. Simulation results in additive white Gaussian noise and realistic indoor multipath wireless channels show that the performance of BPM scheme is approximately 1 dB better than that of PPM scheme. However, the performance discrepancy becomes negligible as the number of users increases.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.1
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• pp.1-7
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• 2000

In this paper, we proposed a complex multirate filter bank(CMRFB) based adaptive notch filtering technique to solve the co-existence narrowband interference problem of DS-CDMA and TDMA systems. We have discussed error performance of co-existence of DS-CDMA and TDMA system by using complex multirate filter bank in land mobile channel and computer simulation results show that the proposed scheme can eliminate the narrowband interference(TDMA signals) effectively.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1994.06a
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• pp.176-180
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• 1994