• Title/Summary/Keyword: Turbo TCM

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Comprehensive Analysis of Turbo TCM over Two Typical Channels

  • Bai, Zhiquan;Yuan, Dongfeng;Kwak, Kyung-Sup
    • Journal of Communications and Networks
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    • v.9 no.1
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    • pp.11-17
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    • 2007
  • In this paper, system performance of turbo trellis coded modulation (turbo TCM) is presented and analyzed through computer simulations over two typical channels, namely additive white Gaussian noise (AWGN) and Rayleigh fading channels. We use and compare different mapping strategies based on Ungerboeck partitioning (UP), block partitioning (BP), mixed partitioning (MP), Gray partitioning (GP), and Ungerboeck-Gray partitioning (UGP) of the signal constellation of the turbo TCM system. Furthermore, taking 8PSK modulation of turbo TCM as an example, our simulation results show that turbo TCM with UP can obtain better performance than turbo TCM with BP, MP, GP, and UGP in both AWGN and Rayleigh fading channels.

Study on DPSAM Turbo TCM in Time-Selective Fading Channels (시간 선택적 페이딩 채널 환경에서 DPSAM Turbo TCM에 관한 연구)

  • Kim, Jeong-Su
    • Journal of the Korea Society of Computer and Information
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    • v.18 no.11
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    • pp.107-113
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    • 2013
  • Mobile mobility and data reliability should be guaranteed as well as amounts of data services are essential in the era of smart media. In order to improve the reliability of high-speed data, strong channel coding and modulation techniques are required. In this paper, the structure of Turbo TCM decoder, applying high-order modulation techniques and the DPSAM method which improves performances in time-selective fading channels in the case of burst errors are suggested through the optimal decoding method and iteration decoding so as to improve bandwidth efficiency in Turbo Codes with excellent encoding gain. The proposed method in comparison with the existing method is that 3dB is superior in case that BER is $10^{-2}$ and the number of iterations is 3. In addition, the function is improved at approximately 6dB in case that BER is $10^{-3}$ and the number of iterations is 7. The proposed method requires additional bandwidth; however, the bandwidth loss can be overcome through Turbo TCM technology on the additional bit rate from the bandwidth loss.

Effective Iterative Control Method to Reduce the Decoding Delay for Turbo TCM Decoder (터보 TCM 디코더의 복호 지연을 감소시키기 위한 효율적인 반복복호 제어기법)

  • 김순영;김정수;장진수;이문호
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.14 no.8
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    • pp.816-822
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    • 2003
  • In this paper, we propose an efficient iteration control method with low complexity for Turbo TCM(Turbo Trellis Coded Modulation) decoding which will be used fur power-limited environment. As the decoding approaches the performance limit of a given turbo code, any further iteration results in very little improvement. Therefore, it is important to devise an efficient criterion to stop the iteration process and prevent unnecessary computations and decoding delay. This paper presents an efficient algorithm for turbo TCM decoding that can greatly reduce the delay and iteration number. The proposed method use adaptive iteration number according to the criterion using the extrinsic information variance parameter in turbo TCM decoding process. The simulation results show that the proposed technique effectively can reduce the decoding delay and computation with very little performance degradation.

Design and Performance Evaluation of 8PSK-TCM System Using Turbo Equalizer for Satellite Communication (위성통신을 위한 터보 등화기를 사용하는 8PSK-TCM 시스템 설계와 성능 평가)

  • An, Changyoung;Ryu, Sang-Burm;Lee, Sang-Gyu;Ryu, Heung-Gyoon
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.28 no.11
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    • pp.837-842
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    • 2017
  • In this paper, as a basic study for combination of turbo equalizer and 4D-8PSK-TCM(4 Dimensional 8 Phase Shift Keying Trellis Coded Modulation) system, which is recommended for X-band band satellite communication in CCSDS, a system combining 8PSK-TCM system and turbo equalizer has designed and performance evaluation of the system has performed. BER performance of 8PSK and 8PSK-TCM systems has evaluated and analyzed in AWGN, Proakis B and Proakis C channels in detail. As results of simulation, BER performance of 8PSK-TCM system is better than 8PSK system in AWGN environment. Furthermore, it can be confirmed that the system combining the 8PSK-TCM system with the turbo equalizer can further improve the BER performance through iterative equalization in the ISI channel environment. The 8PSK-TCM system combined with the turbo equalizer requires SNR of 5.9 dB for BER performance of $10^{-3}$ with 5 iterative equalization in Proakis B and SNR of 9.1 dB for BER of $10^{-2}$ with 5 iterative equalization in Proakis C.

A Study on the Structure of Turbo Trellis Coded Modulation with an Effectively Reduced Complexity in Wireless Communication Channel (무선통신채널에서 효과적으로 감소된 복잡도를 갖는 Turbo Trellis Coded Modulation 구조 연구)

  • Kim Jeong-su
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.5 no.5
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    • pp.409-412
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    • 2004
  • This paper shows that the proposed Turbo TCM(Turbo Trellis Coded Modulation) has a good performance with a little complexity of decoder. The encoder structure, which is connected with Turbo Codes, is the proposed modulation technique for an efficient bandwidth, This method is used symbol by symbol MAP decoder of iteration similar to binary Turbo Codes in the receiver. The result shows that the BER performance according to iteration is improved about 2,5dB at $BER=10^{-2}$ compared to Turbo Codes with Gray mapping.

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Effetive delay reduced control method of iterative decoding for Turbo TCM (터보 TCM을 위한 지연 감소된 효율적인 반복 복호 제어 기법)

  • 김남경;김정수;김순영;이문호
    • Proceedings of the IEEK Conference
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    • 2001.09a
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    • pp.765-768
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    • 2001
  • 본 논문에서는 터보 TCM(Turbo Trellis Coded Modulation)에서 복호기 입력 전에 수신데이터를 이용하여 SNR을 추정하고, SNR에 따라 요구하는 성능을 만족하는 반복 복호수를 적응적으로 복호기 앞단에서 미리 설정하는 반복복호 제어기법을 제안한다. 성능분석결과 최대 반복 복호를 수행했을 때와 비교하여 성능 감소 없이 평균 반복 복호수를 줄일 수 있었다. 따라서 제안구조는 터보 TCM의 복호화 과정에서 문제점 중 하나인 복호 계산량과 지연을 성능 저하 없이 효율적으로 감소시킬 수 있다.

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Performance Analysis of MC-CDMA Systmes for Wireless ATM (무선 ATM 전송을 위한 MC-CDMA 시스템의 성능 분석)

  • 송형규;백종호;조진웅;동용배
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.10 no.4
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    • pp.487-497
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    • 1999
  • In this paper, the performances of MC-CDMA systems for wireless ATM(WATM) is analyzed through computer simulations. The proposed MC-CDMA systems can support the 25 Mbps data rate with about 18.2 MHz bandwidth at 5 GHz carrier frequency, satisfying the specifications of wireless physical layer proposed by Wireless ATM Working Group(WATM WG). For the channel coding strategies, convolutional code, TCM and Turbo TCM(T-TCM) are explored and their performances are compared. From the simulation results, T-TCM becomes superior to the other coding schemes as interative decoding is performed.

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Serially Concatenated Space-Time Code using Iterative Decoding of High Data Rate Wireless Communication (고속 무선 통신을 위한 반복 복호 직렬 연쇄 시.공간 부호)

  • 김웅곤;구본진;양하영;강창언;홍대식
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.25 no.4A
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    • pp.519-527
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    • 2000
  • This paper suggests and analyzes the Serially Concatenated Space-Time Code(SCSTC) with the possibility of a efficient high-speed transmission in a band limited channel. The suggested code has a structure that uses the interleaver to connect the space-time code as an inner code and the convolutional code as a outer code serially. This code keeps the advantage of high-speed transmission and also has the high BER performance. The performance of the suggested system is compared with the conventional bandwidth efficient trellis coded modulation, such as a Serially Concatenated Trellis Coded Modulation (SCTCM) and a Turbo-Trellis Coded Modulation(Turbo-TCM). The results show that the suggested system has a 2.8dB and 3dB better BER performance than SCTCM and Turbo-TCM respectively in case of the transmission rate 2b/s/Hz in fading channel.

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Serial Concatenated Turbo TCM Coding Scheme for Enhanced VSB (개선된 VSB 수신 시스템을 위한 직렬 연접 터보 격자변조부호 방식)

  • Heo, Seo-Weon;Kim, Chang-Joong;Lee, Ho-Kyoung
    • Journal of Broadcast Engineering
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    • v.12 no.4
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    • pp.373-376
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    • 2007
  • Recently, research on the enhancement of the conventional VSB scheme for DTV signal transmission have been done. Not to affect on the performance of the widely spread conventional receivers and at the same time be able to receive the enhanced stream. there have been efforts to enhance the coding scheme which is backward compatible with the conventional method. The conventional schemes proposed so far is based on the idea of combining a new trellis encoder with the standard 8-VSB trellis encoder. In this paper, we Propose serial concatenated turbo TCM scheme which combines two trellis encoder with the interleaver between them. We compare the performance of the proposed scheme and the existing scheme through computer simulation.

Adaptive Trellis-Coded 8PSK Using Symbol Transformation (심볼 변환을 이용한 적응형 8PSK 트렐리스 부호화 방식)

  • 정지원
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.29 no.4C
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    • pp.448-453
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    • 2004
  • Conventional pragmatic TCMs need sector phase quantizer to apply Viterbi decoder which uses 3-bit soft decision. A symbol transformation applied to the incoming I-channel and Q-channel symbols allows to use Viterbi decoder without sector phase quantizer. We analyzed structure and performance of proposed decoder, and applied it to the turbo decoder. We know that the performance of proposed decoder is better than that of conventional decoder by 1 [㏈]because of increasing of Euclidean distance.