• Title, Summary, Keyword: code acquisition

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Improvement of code acquisition time in DS/SS systems using a hybrid scheme (복합방식을 이용한 직접대역확산통신시스템의 코드획득 성능개선)

  • 조권도;김선영
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.21 no.3
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    • pp.684-691
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    • 1996
  • Since the period of a spreading code in DS/SS communication systems is generally long, it is necessary to make the code acquisition as fast as possible. The code acquisition time can be sued as a measure to evaluate the performance of code acquisition systems. The search rate of serial search codee acquisition system used in the coventional CDMA cellular system is lower than that of the matched filter technique. In order to reduce the code acquisition time, this paper proposes hybrid code acquisition system composed filters combined with serial search blocks. In the proposed system, the matched filter sweeps possible code phases fast and the acquired phase information is verified by the serial search block. The mean and the variance of its acquisition time are calculated and compared with those of double dwell serial search system. The results indicate better performance of the proposed system by yielding its small vaues of the mean and the variance of code acquisition time.

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Design and implementation of the PN code searcher for CDMA mobile station (CDMA 이동국용 PN 부호 탐색기 설계 및 구현)

  • 연광일;곽기달
    • Journal of the Korean Institute of Telematics and Electronics S
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    • v.34S no.8
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    • pp.37-44
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    • 1997
  • We implemented a code searcher which is used for the PN(pseudo noise) code acquisition in CDMA cellular mobile station. To reduce the reuired hardware and the code acquisition time, we used the double dwell structure which is an effective serial code acquisition metho. We designed a code acquisition has acquired within 1/2 PN chip range. The code searcher is implemented using 0.8 micron code searcher is successfully working in CDMA cellular mobile station and it satisfies the code acquisition time specified in IS-95 standard.

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A ASIC design of the Improved PN Code Acquisition System for DS/CDMA (DS-CDMA용 개선된 PN 코드 포착 시스템의 ASIC 설계)

  • Jo, Byeong-Rok;Park, Jong-U
    • The KIPS Transactions:PartD
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    • v.9D no.1
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    • pp.161-166
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    • 2002
  • The existing method in PN code acquisition process have a problem in PN code acquisition time because PN code searching is accomplished in one epoch. In this paper, we propose algorithm that can reduce PN code acquisition time because PN code searching is accomplished in each other two epoches. The designed ASIC chip using proposed algorithm confirmed that the area (the number of gates) increase more than existing method in PN code acquisition, but the performance of PN code acquisition is better than existing method.

A Satellite Navigation Signal Scheme Using Zadoff-Chu Sequence for Reducing the Signal Acquisition Space

  • Park, Dae-Soon;Kim, Jeong-Been;Lee, Je-Won;Kim, Kap-Jin;Song, Kiwon;Ahn, Jae Min
    • Journal of Positioning, Navigation, and Timing
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    • v.2 no.1
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    • pp.1-8
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    • 2013
  • A signal system for improving the code acquisition complexity of Global Navigation Satellite System (GNSS) receiver is proposed and the receiving correlator scheme is presented accordingly. The proposed signal system is a hierarchical code type with a duplexing configuration which consists of the Zadoff-Chu (ZC) code having a good auto-correlation characteristic and the Pseudo Random Noise (PRN) code for distinguishing satellites. The receiving correlator has the scheme that consists of the primary correlator for the ZC code and the secondary correlator which uses the PRN code for the primary correlation results. The simulation results of code acquisition using the receiving correlator of the proposed signal system show that the proposed signal scheme improves the complexity of GNSS receiver and has the code acquisition performance comparable to the existing GNSS signal system using Coarse/Acquisition (C/A) code.

Ultra-Fast L2-CL Code Acquisition for a Dual Band GPS Receiver

  • Kim, Binhee;Kong, Seung-Hyun
    • Journal of Positioning, Navigation, and Timing
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    • v.4 no.4
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    • pp.151-160
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    • 2015
  • GPS L2C signal is a recently added civil signal to L2 frequency and is constructed by time division multiplexing of civil moderate (L2-CM) and civil long (L2-CL) code signals. While the L2-CM code is 20 ms-periodic and modulates satellite navigation message, the L2-CL code is 1.5s-periodic with 767,250 chips long code sequence and carries no data. Therefore, the L2-CL code signal allows receivers to perform a very long coherent integration. However, due to the length of the L2-CL code, the acquisition of the L2-CL code signal may take too long or require too much hardware resources. In this paper, we propose a three-step ultra-fast L2-CL code acquisition (TSCLA) technique for dual band GPS receivers. In the proposed TSCLA technique, a dual band GPS receiver sequentially acquires the coarse/acquisition (C/A) code signal at L1 frequency, the L2-CM code signal, and the L2-CL code signal to minimize mean acquisition time (MAT). The theoretical performance analysis and numerous Monte Carlo simulations show the significant advantage of the proposed TSCLA technique over conventional techniques introduced in the literature.

O-CDMA Code Acquisition Algorithm Based on Magnitude and Sign of Correlation Values (상관값의 크기와 부호에 기반한 O-CDMA 부호 획득 알고리즘)

  • Chong, Da-Hae;Yoon, Tae-Ung;Lee, Young-Po;Lee, Young-Yoon;Song, Chong-Han;Park, So-Ryoung;Yoon, Seok-Ho
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.34 no.6C
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    • pp.649-655
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    • 2009
  • Mean acquisition time (MAT) is the most important performance measure for code acquisition systems, where a shorter MAT implies a better code acquisition performance. Keshavarzian and Salehi proposed the multiple-shift (MS) algorithm for code acquisition in optical code division multiple access (O-CDMA) systems. Performing two steps acquisition, the MS algorithm has a shorter MAT than that of the conventional serial-search (SS) algorithm. In this paper, we propose a rapid code acquisition algorithm for O-CDMA systems. By using an efficient combination of local signals, correlation value, and the sign of correlation value, the proposed algorithm can provide a shorter MAT compared with that of the MS algorithm. The simulation results show that the proposed algorithm presents a shorter MAT than that of the MS algorithm.

A FPGA Design of Improved Acquisition System for DS-CDMA (DS-CDMA을 이용한 개선된 동기 획득 시스템의 FPGA 설계)

  • 박종우;조병록;송재철
    • Proceedings of the IEEK Conference
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    • pp.67-70
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    • 1999
  • DS-CDMA is used to widely spread spectrum for a cellular mobile digital communication that maximizing users- capacity at the limited frequency bandwidth, solving technical matters with the channel. Especially, the capability of a spread spectrum receiver relied on fast code acquisition time at the demodulation. In this paper, we considered that fast code acquisition time when a spread spectrum system is designed, and existed code acquisition system set up one code epoch on a position at initial processing, but the proposed code acquisition system improved that two code epoch are set up at the same time, therefore code acquisition time is diminished in effect. The structure modeling to VHDL language. Its synthesized the synthesized and, is implemented FPGA chip

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On the Optimum Dwell Time for Fast Code Acquisition is DS/SS Systems (DS/SS 시스템에서 최소 코드획득시간을 위한 최적 코드측정시간에 관한 연구)

  • 조권도;부수일;김철성
    • Journal of the Korean Institute of Telematics and Electronics A
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    • v.30A no.8
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    • pp.11-18
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    • 1993
  • In a spread spectrum system, the bandwidth and period of spreading code is wide and long, respectively. So it is necessary to make the code acquisition time as short as possible. In particular, serial search code acquisition system requires optimum dwell time for fast acquisition. In this paper, code acquisition time is calculated by varying dwell time. Among them, minimum code acquisition time is chosen and then optimum dwell time can be obtained. Detection probability (P$_{D}$) and false alarm probability (P$_{FA}$) can be obtained by integrating chi-square pdf by numerical analysis. The results are compared with that of gaussian approximation method and then it is concluded gaussian approximation method is not suitable for obtaining optimum dwell time. Computer simulation supports theoretical results.

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DS-SS/TDMA Preamble Structure and Code Acquisition Method for Enhanced Code Acquisition Performance (부호획득 성능이 향상된 DS-SS/TDMA 프리앰블 구조 및 부호획득방법)

  • Ryu, Young-Jae;Jang, Jeen-Sang
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.35 no.11B
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    • pp.1725-1731
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    • 2010
  • In this paper, we proposed preamble structure and code acquisition method to improve code acquisition performance for DS-SS/TDMA packet communication systems. Proposed algorithm changes the short PN code position depending on the sub slot number. Proposed algorithm also saves position differences between short PN codes and position offsets between short PN codes and data starting position of the TDMA packet. By using the position difference table, proposed algorithm can find out exact data starting position even though some sub slots were defected. As a result of simulation, we concluded that proposed algorithm has at least 5dB gain compared to conventional method when same short PN code is used. Moreover, proposed algorithm shows same code acquisition performance only with 1/4 shortened short PN code compared to conventional method.

A reference code design for PN code acquisition in DS/SS CDMA systems (DS/SS CDMA 시스템 하에서 유사임의 코드 획득을 위한 reference code 설계)

  • 원승환;장승용;김운경
    • Proceedings of the IEEK Conference
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    • pp.65-68
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    • 2000
  • In CDMA, the currently used PN code acquisition methods detect the phase of the incoming PN signal on the basis of ML estimation. In serial search strategy, it takes relatively long time for PN code acquisition. A study related to reduce processing time of PN code acquisition is important. Therefore we propose a reference code design for a new algorithm that a reference code and the received PN code are fully correlated to detect the transmitted PN code, in detail, the relative phase offset j of c⒡. After choosing two weight factors, we show the mathematical analysis and derivation for the reference code design.

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