• Title/Summary/Keyword: WCDMA

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An Implementation Method on SDR-based Integrated Wireless Communication System for CDMA/WCDMA (SDR 기반 CDMA/WCDMA 통합 무선통신 시스템의 구현방안)

  • Shin, Sung-yup;Hwang, Chong-sun
    • Proceedings of the Korea Information Processing Society Conference
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    • 2004.05a
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    • pp.1497-1500
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    • 2004
  • 현재 사용되고 있는 CDMA 망에서 새로이 도입하고자 하는 동기식 IMT-2000과 비동기식 IMT-2000인 WCDMA을 제공하고자 하는 사업체들은 기지국 증설의 장소와 비용부담, 시스템 업그레이드 등의 유지보수 문제로 인해 많은 어려움을 겪고 있다. 이를 해결 하기 위해 많은 회사 혹은 연구소에서 해결 방안을 연구 중이며 모든 이동통신을 하나의 시스템으로 서비스 할 수 있는 방법으로 SDR 기법이 많이 논의 되고 있다. 본 논문에서는 주로 DSP 기술을 응용하여 SDR 기법을 시스템에 적용하여 하나의 시스템에서 소프트웨어 업데이트만으로 시스템의 물리계층을 제어하여 시스템의 유연성을 가지게 하는 구현방안을 CDMA/WCDMA을 중심으로 제시하였다.

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Cardio-Pulmonary Effects of RF Fields Emitted from WCDMA Mobile Phones (WCDMA 휴대전화 전자파에 의한 심호흡계 영향)

  • Kwon, M.K.;Choi, J.L.;Choi, J.Y.;Jang, K.H.;Kim, S.K.;Kim, D.W.
    • Journal of Biomedical Engineering Research
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    • v.33 no.2
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    • pp.59-64
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    • 2012
  • With rapid increasing usage of smart phones, social concerns have arisen about the possible effects of electromagnetic fields emitted from wideband code division multiple access(WCDMA) mobile phones on human health. The number of people with self-reported electromagnetic hypersensitivity(EHS) who complain of various subjective symptoms such as headache, insomnia etc. has also recently increased. However, it is unclear whether EHS results from physiological or other origins. In this double-blinded study, we investigated physiological changes such as heart rate, respiration rate, and heart rate variability with real and sham exposures for 15 EHS and 17 non-EHS persons using a module inside a dummy phone. Experiment was conducted using a WCDMA module with average power of 24 dBm at 1950 MHz with the specific absorption rate of 1.57 W/kg using a headphone for 32 min. As a conclusion, WCDMA RF exposure did not have any effects on the physiological variables in either group.

Performance Analysis of Stepwise Parallel Processing for Cell Search in WCDMA over Rayleigh Fading Channels (레일리 페이딩 채널에서 WCDMA의 단계별 병렬 처리 셀 탐색의 성능 해석)

  • 송문규
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.27 no.2B
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    • pp.125-136
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    • 2002
  • It is very important to acquire the synchronization in a intercell asynchronous WCDMA system, and it is carried out through the three-step cell search process. The cell search can operate in a stepwise parallel manner, where each step works in pipelined operation, to reduce the cell search time. In case that the execution time is set to be the same in each step, excessive accumulations will be caused in both step 1 and step 3, because step 2 should take at least one frame for its processing. In general, the effect of post-detection integration becomes saturated as the number of the accumulations increases. Therefore, the stepwise parallel scheme does not give much enhancement. In this paper, the performance of the stepwise parallel processing for cell search in WCDMA system is analyzed over Rayleigh fading channels. Through the analysis, the effect of cell search parameters such as the number of accumulations in each step and the power ratio allocated among channels is investigated. In addition, the performance of the stepwise parallel cell search is improved by adjusting the execution time appropriately for each step and is compared with that of the conventional stepwise serial processing.

A Channel Estimation Scheme using Early-late Doppler Compensator in uplink WCDMA system (WCDMA 시스템의 역방향 링크에서 Early-late 도플러 보상을 이용한 채널 추정 기법)

  • Choi, Jung-Hyun;Kim, Nak-Myeong
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.27 no.1B
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    • pp.90-98
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    • 2002
  • To increase system capacity in WCDMA receiver, the coherent detection is an essential technology for recovering transmitted symbols correctly. For coherent detection, an accurate and fast channel estimation is required. In next generation mobile communication system, high frequency carriers are used, and high data rate services are provided for subscribers having high mobility. In this communication environment, however, the rapidly-changing doppler frequency degrades the quality of the transmitted signal a lot. In WCDMA system, the channel estimation is conducted using pilot channel and/or pilot symbols which are known to both transmitter and receiver. Some existing channel estimation algorithms utilize these information quite well, but the performance of channel estimation gets very poor in a complicated fading channel distorted by the doppler effect. In this paper, we propose a new channel estimation algorithm combining an early-late doppler compensator so that the doppler effect and the fading characteristics are compensated at the same time. By computer simulation, the proposed algorithm proved to be a much more efficient channel estimation method in the fast fading channel, even at reasonably low Eb/No.

Hybrid Scheduling Algorithm for Guaranteeing QoS of Real-time Traffic in WCDMA Enhanced Uplink (WCDMA 개선된 상향링크에서 실시간 트래픽의 서비스 품질을 보장하는 하이브리드 스케줄링 알고리즘)

  • Kang, You-Jin;Kim, Jun-Su;Sung, Dan-Keun
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.32 no.11A
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    • pp.1106-1112
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    • 2007
  • As a demand for high speed uplink packet services increases, the WCDMA enhanced uplink, also known as high speed uplink packet access (HSUPA), has been specified in release 6 by 3GPP. This HSUPA will provide various types of multimedia services, such as real-time video streaming, gaming, VoIP, and FTP. Generally, the performance of HSUPA is dominated by scheduling policy. Therefore, it is required to design a scheduling algorithm considering the traffic characteristics to provide QoS guaranteed services in various traffic environments. In this paper, we propose a scheduling algorithm considering the traffic characteristics to guarantee QoS in a mixed traffic environment. Finally, the performance of the proposed scheduling algorithm is evaluated in terms of average packet delay, packet delay jitter, and system throughput using a system level simulator.

Design and Performance Analysis of a Decision-feedback Coherent Code Tracking Loop for WCDMA Systems (WCDMA 시스템을 위한 판정궤환 동기식 동기추적 회로의 설계 및 성능분석)

  • 박형래;양연실;김영선;김창주
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.29 no.4A
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    • pp.429-438
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    • 2004
  • In this paper, a decision-feedback coherent code tracking loop is designed for WCDMA systems and its performance is analyzed in terms of jitter variance considering the effect of phase and symbol estimation errors for both AWGN and fading environments. An analytical closed-form formula for jitter variance is Int derived for AWGN environments as a function of a pulse-shaping filter, timing offset, signal-to-interference ratio, and loop bandwidth while involving the phase estimation error and bit error rate, and the upper bound of jitter variance is derived for fading environments. Finally a second-order coherent code tracking loop is designed with the DPCH frame format #13 of the WCDHA forward link selected as a target system, and its performance is evaluated by the closed-form formula and compared with the simulation results for both AWGN and Rayleigh fading environments.

HSDPA 솔루션 출시 '봇물'

  • Kim, Jong-Yul
    • 정보화사회
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    • s.180
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    • pp.22-24
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    • 2006
  • 올 모바일 시장의 최대 화두는 HSDPA로 판단된다. WCDMA 서비스 침체가 장기화되고 있는 시점에서 HSDPA는 WCDMA 서비스 뿐 아니라 모바일 서비스 자체를 견인할 '핵'으로 각광받고 있다. 이에 따라 관련 업체들은 '솔루션' 출시를 앞다퉈 선언하며 시장 선점에 나서고 있다. 한 발 앞서 내딛는 발걸음이 향후 열 발 앞선 행보로 이어질 수 있다는 판단에서이다. 그들의 움직임을 추적했다.

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