• Title/Summary/Keyword: symbol detection

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Performance Characteristics of a Symbol Timing Detection by Superposed Difference Method for OFDM (중첩의 차분화방식에 의한 OFDM 심벌 타이밍검출 성능)

  • Joo, Chang-Bok;Park, Dong-Ho
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.44 no.2
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    • pp.46-54
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    • 2007
  • In this paper, we introduce the performance of improved symbol timing detection by the superposed difference type symbol timing detection method in the OFDM system. Also, we represent the maximum detection probability of symbol synchronization timing at each received delay signal in multipath channel delay profile in the correlation and difference type symbol timing detection methods. The computer simulation results show that the correlation symbol timing detection method have maximum detection probability at the lead of the nth received delay signal of highest amplitude, but the difference type symbol timing detection method always have maximum detection probability at the lead of the first received delay signal in the channel delay spread of $70nsec{\sim}217nsec$. The simulation results indicate the possibility of the perfect detection of OFDM symbol synchronization timing and it fit well with the results of improved S/N to the eb/n0 and the performance of symbol timing detection of the proposed method.

Maximum Likelihood Receivers for DAPSK Signaling

  • Xiao Lei;Dong Xiaodai;Tjhung Tjeng T.
    • Journal of Communications and Networks
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    • v.8 no.2
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    • pp.205-211
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    • 2006
  • This paper considers the maximum likelihood (ML) detection of 16-ary differential amplitude and phase shift keying (DAPSK) in Rayleigh fading channels. Based on the conditional likelihood function, two new receiver structures, namely ML symbol-by-symbol receiver and ML sequence receiver, are proposed. For the symbol-by-symbol detection, the conventional DAPSK detector is shown to be sub-optimum due to the complete separation in the phase and amplitude detection, but it results in very close performance to the ML detector provided that its circular amplitude decision thresholds are optimized. For the sequence detection, a simple Viterbi algorithm with only two states are adopted to provide an SNR gain around 1 dB on the amplitude bit detection compared with the conventional detector.

Sliding Multiple Symbol Differential Detection of Trellis-coded MDPSK (트랠리스 부호화된 MDPSK의 흐름 다중심볼 차동검파)

  • 김한종;강창언
    • Journal of the Korean Institute of Telematics and Electronics A
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    • v.31A no.4
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    • pp.39-46
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    • 1994
  • In this paper, the idea of using a multiple symbol obervation interval to improve error probability performance is applied to differential detection of MTCM(multiple trellis code modulation) with ${\Pi}$/4 shift QPSK, 8DPSK and 16DPSK. We propose two types of sliding multiple symbol differential detection algorithm, type 1 and type 2. The two types of sliding detection scheme are examined and compared with conventional(symbol-by-symbol) detection and bolck detection with these modulation formats in an additive white Gaussian noise(AWGN) using the Monte Carlo simulation. We show that the amount of improvement over conventional and block detection depends on the number of phases and the number of additional symbol intervals added to the observation. Computer simulagtion results are presented for 2,4,8 states in AWGN channel.

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Detection Probability as a Symbol Synchronization Timing at the Lead of Each Received Delay OFDM Signal in Multipath Delay Profile (멀티패스 지연프로필의 각 수신지연파의 선두에서 OFDM 신호의 심벌 동기타이밍으로의 검출확률)

  • Joo, Chang-Bok;Park, Dong-Ho
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.44 no.2
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    • pp.55-61
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    • 2007
  • In this paper, we represent the maximum detection probability formulas of symbol synchronization timing at each received delay signal in multipath channel delay profile in the multiplied correlation and difference type correlated symbol synchronization timing detection method. The computer simulation results show that the correlation symbol timing detection method have maximum detection probability at the lead of received delay signal of highest amplitude, but the difference type of correlation symbol timing detection method always have maximum detection probability at the lead of first received delay signal in the multipath channel models. Using this results, we show the BER characteristics difference between the IEEE802.11a OFDM signals which is obtained in case of the symbol synchronization timing is taken at zero error(perfect) timing position and at -1 sample error symbol timing position from perfect timing position in the multipath channel models regardless the length of channel delay spread.

A new noncoherent detection algorithm for DBO-CSS (새로운 DBO-CSS 수신기 구조)

  • Yoon, Sang-Hun;Chong, Jong-Wha
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.44 no.4
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    • pp.59-64
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    • 2007
  • In this paper, we propose a new decoding method for differentially biorthogonal chirp spread spectrum (DBO-CSS). In DBO-CSS, the information is carried on the differential phase not between the adjacent sub-chirp symbols but between the sub-chirp symbols in the same position of adjacent full-chirp symbol. So, the conventional multiple symbol differential detection (MSDD) algorithms to enhance the BER performance can not be applied to the DBO-CSS directly. In this paper, we propose a new differential detection algorithm based on a partial MSD(multiple symbol detection) and a viterbi algorithm. It is shown that the performance gain of the proposed algorithm when compared with that of the conventional detection algorithm is around 2.5dB at BER = 10-5.

Dominant Color Transform and Circular Pattern Vector: Applications to Traffic Sign Detection and Symbol Recognition

  • An, Jung-Hak;Park, Tae-Young
    • Journal of Electrical Engineering and information Science
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    • v.3 no.1
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    • pp.73-79
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    • 1998
  • In this paper, a new traffic sign detection algorithm.. and a symbol recognition algorithm are proposed. For traffic sign detection, a dominant color transform is introduced, which serves as a tool of highlighting a dominant primary color, while discarding the other two primary colors. For symbol recognition, the curvilinear shape distribution on a circle centered on the centroid of symbol, called a circular pattern vector, is used as a spatial feature of symbol. The circular pattern vector is invariant to scaling, translation, and rotation. As simulation results, the effectiveness of traffic sign detection and recognition algorithms are confirmed, and it is shown that group of circular patter vectors based on concentric circles is more effective than circular pattern vector of a single circle for a given equivalent number of elements of vectors.

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Multi-symbol detection for biorthogonal signals over rayleigh fading channels (레일리 페이딩 채널에서의 이중직교 신호에 대한 다중심볼 검파)

  • 엄의식;윤순영;이황수
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.22 no.1
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    • pp.30-39
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    • 1997
  • In this paper, a new practical coherent detection scheme for biorthogonal signals, which uses multi-symbol observation interval, is proposed and its performances are analyzed and simulated. The technique jointly estimates both the demondulated data and the channel from received signal only while reducing computation complexity by an approximate maximum-likelihood sequence estimation rather than symbol-by-symbol detection as in previous noncoherent detection. The scheme achieves performance close to that of ideal coherent detection with perfect channel estimates when select the appropriate observation symbol interval N in the given symbol alphabet wize M. What is particularly interesting is that the requeired average signal-to-noise ratio per bit ${\gamma}_{b}$ can be reducedd by as much as 1.4dB and the capacity can be increase by as much as 38% when we use this system in the CDMA cellular reverse link.

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격자코드 변조 시스템에서 DFE의 심볼판정 알고리즘 제안 (Symbol Detection Methods for DFEs in Trellis Coded Modulation Systems)

  • Chung, Won-Zoo
    • Journal of IKEEE
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    • v.10 no.1 s.18
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    • pp.69-74
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    • 2006
  • In this paper, we present symbol detection methods for decision feedback equalizers (DFE) in trellis coded modulation systems. The proposed symbol detectors improve symbol error rate (SER) by exploiting the coding structure of trellis coded modulation (TCM). For example, for 8-PAM signals the achieved SER with the proposed detection scheme is improved to $2{\times}10^{-5}$ from $2.5{\times}10^{-2}$ of the conventional symbol-by-symbol detector under AWGN channel at 20dB SNR. This SER improvements mitigate error propagation of DFE.and produces significant over-all SER improvement for under multipath channels (for example, from 0.26 to 0.01 and 0.005 under a severe multipath channel 20dB SNR as shown in the simulation result of this paper).

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Effect of Bandwidth of Moving Average Filter on Symbol Timing Detection Performance (이동 평균 필터의 대역폭이 심벌 타이밍 검출 성능에 미치는 영향)

  • Lee, Jihye;Jeon, Taehyun
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.14 no.5
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    • pp.117-121
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    • 2014
  • In the orthogonal frequency division multiplexing system, the prefix inserted between data symbols should be eliminated to apply the Fourier transform on the valid symbol interval. This functional procedure should be based on the accurate symbol timing detection. The symbol timing detection at the receiver side provides the reference for determining the beginning time index of each symbol whose initial point is located at the boundary between the preamble and the payload part. Also, the detection error is one of the main factors in the overall system performance. In this paper the effect of the bandwidth of the moving average filter on the symbol timing detection is discussed. Simulations are carried out to analyze the detection performance for the varying values of the window size of the moving average filter which is related to the filter bandwidth.

Performance Analysis of the Trellis-Coded 8DPSK with Multiple Symbol Differential Detection (다중 심볼 차동 검파를 이용한 트렐리스 부호화된 8DPSK의 성능 분석)

  • 문태현;김한종;홍대식;강창언
    • The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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    • v.4 no.3
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    • pp.54-62
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    • 1993
  • In this paper, performance comparisions of MTCM systems with 8DPSK over mobile communication channels are obtained by computer simulation. The multiple symbol differential detection scheme is introduced in order to improve the bit error rate performance in the detection of the trellis-coded 8DPSK system. Rician fading channels are used as test channels. The simula- tion results show that the trellis-coded 8DPSK system with multiple symbol detection gives better performance than that of the uncoded DQPSK system. And symbol by symbol interleaving method gives better performance than the symbol pair interleaving method.

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