• Title/Summary/Keyword: Direct sequence spread spectrum

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Performance of PN Code Synchronization with Extended Kalman Filter for a Direct-Sequence Spread-Spectrum System (직접시퀀스 확산대역 시스템을 위한 Extended Kalman Filter 기반의 PN 부호 동기화 성능)

  • Kim, Jin-Young;Yang, Jae-Soo
    • Journal of The Institute of Information and Telecommunication Facilities Engineering
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    • v.8 no.3
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    • pp.107-110
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    • 2009
  • In this paper, a PN code tracking loop with extended Kalman filter (EKF) is proposed for a direct-sequence spread-spectrum. EKF is used to estimate amplitude and delay in a multipath. fading channel. It is shown that tracking error performance is significantly improved by EKF compared with a conventional tracking loop.

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A Study on Binary Direct-Sequence Spread Spectrum Multiple Access Communications over Rayleigh Fading Channels (Rayleigh 페이팅 채널에서의 Binary 직접 시퀀스 확산 대역 다중 접근 통신에 관한 연구)

  • 허문기;박상규
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.26 no.12
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    • pp.1910-1917
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    • 1989
  • This paper shows the performances of asynchronous binary direct-sequence spread-spectrum multiple access communication systems with Rayleigh fading and White Gaussian noise. The performance measures considered are worst-case bit error probability and average SNR depending on code sequences and chip waveforms. The code sequences used are m-sequence and Gold sequence with period 31.The chip waveforms employed are rectangular, sinusoidal and something other chip waveforms.

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Sea Trial Results of the Direct Sequence Spread Spectrum Underwater Acoustic Communication in the East Sea (동해에서 직접 수열 대역확산 수중음향통신 기법의 해상실험 결과)

  • Han, Jeong-Woo;Kim, Ki-Man;Yun, Yeong-Jung;Mun, Hyeon-Uk;Chun, Seung-Yong;Son, Kweon
    • The Journal of the Acoustical Society of Korea
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    • v.31 no.7
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    • pp.441-448
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    • 2012
  • Spread spectrum provides the minimized inter-symbol interference, the low probability of intercept and the multiple access capability. This paper presents a direct sequence spread spectrum with carrier/timing recovery and equalizer which compensates the delay spread caused by multipath transmission. When the sea trials were performed in Korean East Sea, the bit error rates of QPSK and direct sequence spread spectrum are $1.46{\times}10^{-2}$ and $5.17{\times}10^{-4}$ at 3 km source-receiver range, respectively.

A Survey of Security Mechanisms with Direct Sequence Spread Spectrum Signals

  • Kang, Taeho;Li, Xiang;Yu, Chansu;Kim, Jong
    • Journal of Computing Science and Engineering
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    • v.7 no.3
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    • pp.187-197
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    • 2013
  • Security has long been a challenging problem in wireless networks, mainly due to its broadcast nature of communication. This opens up simple yet effective measures to thwart useful communications between legitimate radios. Spread spectrum technologies, such as direct sequence spread spectrum (DSSS), have been developed as effective countermeasures against, for example, jamming attacks. This paper surveys previous research on securing a DSSS channel even further, using physical layer attributes-keyless DSSS mechanisms, and watermarked DSSS (WDSSS) schemes. The former has been motivated by the fact that it is still an open question to establish and share the secret spread sequence between the transmitter and the receiver without being noticed by adversaries. The basic idea of the latter is to exploit the redundancy inherent in DSSS's spreading process to embed watermark information. It can be considered a counter measure (authentication) for an intelligent attacker who obtains the spread sequence to generate fake messages. This paper also presents and evaluates an adaptive DSSS scheme that takes both jam resistance and communication efficiency into account.

Simulation and Design of a Direct Sequence Spread Spectrum Transceiver for Wireless CCTV (확산대역 통신방식을 이용한 무선 CCD 카메라를 위한 기저대역 신호처리부 설계)

  • 김지은;송봉섭;김수환;황인근;김환우
    • Proceedings of the IEEK Conference
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    • 2000.09a
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    • pp.569-572
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    • 2000
  • 본 논문에서는 DSSS(Direct Sequence Spread Spectrum)를 사용한 무선 감시용 카메라를 위한 모뎀을 제안한다 무선 환경에서 발생할 수 있는 여러 가지 간섭과 다중 경로에 의한 오류 발생 확률 등을 고려해야 하고 또한 여러 대의 카메라를 설치하고 각각의 카메라로부터의 신호를 선택적으로 모니터하기 위해 각각의 신호를 구분할 수 있는 변조 방식의 사용이 필요하다. 이를 위해 컴퓨터 모의 실험을 통한 성능 분석과 실제 FPGA설계 및 제작으로 이를 확인한다.

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Performance of PN Tracking with Extended Kalman Filter (Extended Kalman Filter기반의 PN부호 추적성능)

  • Bae, Jung-Nam;Koo, Sung-Wan;Kim, Sung-Ill;Kim, Jin-Young
    • 한국정보통신설비학회:학술대회논문집
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    • 2009.08a
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    • pp.112-114
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    • 2009
  • In this paper, a PN code tracking loop with extended Kalman filter (EKF) is proposed for a direct-sequence spread-spectrum. EKF is used to estimate amplitude and delay in a multipath fading channel. It is shown that tracking error performance is significantly improved by EKF compared with a conventional tracking loop.

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Direct Sequence Spread Spectrum Transmitter using FPGAs

  • Abhijit S. Pandya;Souza, Ralph-D′;Chae, Gyoo-Yong
    • Journal of information and communication convergence engineering
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    • v.2 no.2
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    • pp.76-79
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    • 2004
  • The DS-SS (Direct Sequence Spread Spec1nun) transmitter is part of a low data rate (∼150 kbps - burst rate and 64 bps - average data rate) wireless communication system. It is traditionally implemented using Digital Signal processing chip (DSP). However, with rapid increase in variety of services through cell phones, such as, web access, video transfer, online games etc. demand for higher rate is increasing steadily. Since the chip rate and thereby the sampling rate requirements of the system are fairly high, the transmitter should implemented using Field programmable Gate Arrays FPGAs instead of a DSP. This paper shows the steps taken to get a working prototype of the transmitter unit on a FPGA based platform.

Median Prefilter Based Robust Acquisition Of Direct Sequence Spread Spectrum Signals In Wideband Pulse Jamming (미디언 필터를 이용한 광대역 펄스 재밍 환경에서의 직접 시퀀스 확산 대역 신호의 강인한 포착)

  • 김승준;이용환
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.24 no.6B
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    • pp.1015-1023
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    • 1999
  • We propose nonlinear processing schemes for robust acquisition of direct-sequence spread spectrum (DS/SS) signals in wideband pulse jamming. To mitigate the interference effect due to impulse-like wideband jamming signals, the received signal is preprocessed by using the median filter, a simple order statistic filter Since only parts of the PN sequence are used for rapid acquisition, it is indispensable for analytic design of an acquisition scheme to have an appropriate model of the partial PN signal. The partial correlation of the median filtered PN signal is approximated by a two-piecewise linear model using an approximate upper bound. The acquisition performance of the proposed schemes is compared to that of other schemes. Finally, the analytic design is verified by computer simulation.

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Self-Encoded Spread Spectrum with Iterative Detection under Pulsed-Noise Jamming

  • Duraisamy, Poomathi;Nguyen, Lim
    • Journal of Communications and Networks
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    • v.15 no.3
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    • pp.276-282
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    • 2013
  • Self-encoded spread spectrum (SESS) is a novel modulation technique that acquires its spreading code from a random information source, rather than using the traditional pseudo-random noise (PN) codes. In this paper, we present our study of the SESS system performance under pulsed-noise jamming and show that iterative detection can significantly improve the bit error rate (BER) performance. The jamming performance of the SESS with correlation detection is verified to be similar to that of the conventional direct sequence spread spectrum (DSSS) system. On the other hand, the time diversity detection of the SESS can completely mitigate the effect of jamming by exploiting the inherent temporal diversity of the SESS system. Furthermore, iterative detection with multiple iterations can not only eliminate the jamming completely but also achieve a gain of approximately 1 dB at $10^{-3}$ BER as compared with the binary phase shift keying (BPSK) system under additive white gaussian noise (AWGN) by effectively combining the correlation and time diversity detections.

Performance Analysis of Sequential Estimation Schemes for Fast Acquisition of Direct Sequence Spread Spectrum Systems (직접 수열 확산 대역 시스템의 고속 부호 획득을 위한 순차 추정 기법들의 성능 분석)

  • Lee, Seong Ro;Chae, Keunhong;Yoon, Seokho;Jeong, Min-A
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.39A no.8
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    • pp.467-473
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    • 2014
  • In the direct sequence spread spectrum system, the correct synchronization is very important; hence, several acquisition schemes based on the sequential estimation have been developed. Typically, the rapid acquisition sequential estimation (RASE) scheme, the seed accumulating sequential estimation (SASE) scheme, the recursive soft sequential estimation (RSSE) scheme have been developed for the correct acquisition. However, the objective performance comparison and analysis between former estimation schemes have not been performed so far. In this paper, we compare and analyze the performance of the above sequential estimation schemes by simulating the correct chip probability and the mean acquisition time (MAT).