串行级联连续相位调制系统的性能研究与DSP实现
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摘要
串行级联连续相位调制(SCCPM:Serially Concatenated Continuous Phase Modulation)系统不仅具有很高的频谱利用率和功率利用率,而且具有类似于Turbo码卓越的误码性能。由于连续相位调制可以分解为一个连续相位编码(CPE:Continuous Phase Encoder)和一个无记忆调制器(MM:Memoryless Modulator),而连续相位编码器实际上就是一个简单的递归卷积码,SCCPM不需要独立的内码,具有与串行级联卷积编码(SCCC:Serially Concatenated Convolutional Codes)相似的结构。SCCPM系统进行软输入软输出的迭代译码可以获得很高的交织增益,因此在快衰落和极低的信噪比环境中,SCCPM具有更好的性能,这些优点使得其特别适合于跳频系统和军用Ad-Hoc网络。
本文主要研究了串行级联连续相位调制系统的性能,以及迭代译码算法和系统的DSP实现。本文首先介绍了CPM的特点,推导出CPM的分解模型,在此基础上提出了SCCPM的系统模型,通过计算机仿真得到SCCPM的系统性能;然后深入研究了迭代停止译码算法,提出了一种基于平均外信息交换的迭代停止译码算法,仿真结果证明该算法能够在保证系统性能的前提下大大降低了计算的复杂性,缩短了译码的时间;最后对SCCPM的实际应用进行初步的探索,在DSP软环境下实现了该系统。
Recently, serially concatenated CPM (SCCPM) systems with high spectral efficiency, power efficiency and some turbo-like coding performance draw more attention. Since CPM can be decomposed into a continuous-phase encoder(CPE) and a memory-less modulator(MM),and the CPE is equivalent to a convolutional encoder, there is no need of inner code in SCCPM which has the similar structure compared with serially concatenated convolutional codes. SCCPM with iterative decoding based on soft-input soft-output (SISO) shows a large interleaving gain. It is robust under highly dynamic and fading environment, which is suitable to frequency hopping system and military‘ad hoc’networks.
In this thesis Serially Concatenated Continuous Phase Modulation (SCCPM) and its performance are mainly studied, as well as the algorithms of iterative decoding and the implementation of this system with digital signal processor (DSP). First of all, based on the principle of the CPM signal, a decomposition approach to CPM is developed, and then we present the system model of SCCPM and obtain its performance through computer simulation; secondly, through analysis to the stopping algorithm of dynamic iterative decoding, a new stopping algorithm based on average extrinsic information exchange is proposed, simulation result shows that the combination of average extrinsic information exchange and stopping algorithm of dynamic iterative decoding can improve the BER performance as well as reduce iterative decoding time. Finally we primarily explore the application of SCCPM, and implement it in DSP simulation environment.
本文主要研究了串行级联连续相位调制系统的性能,以及迭代译码算法和系统的DSP实现。本文首先介绍了CPM的特点,推导出CPM的分解模型,在此基础上提出了SCCPM的系统模型,通过计算机仿真得到SCCPM的系统性能;然后深入研究了迭代停止译码算法,提出了一种基于平均外信息交换的迭代停止译码算法,仿真结果证明该算法能够在保证系统性能的前提下大大降低了计算的复杂性,缩短了译码的时间;最后对SCCPM的实际应用进行初步的探索,在DSP软环境下实现了该系统。
Recently, serially concatenated CPM (SCCPM) systems with high spectral efficiency, power efficiency and some turbo-like coding performance draw more attention. Since CPM can be decomposed into a continuous-phase encoder(CPE) and a memory-less modulator(MM),and the CPE is equivalent to a convolutional encoder, there is no need of inner code in SCCPM which has the similar structure compared with serially concatenated convolutional codes. SCCPM with iterative decoding based on soft-input soft-output (SISO) shows a large interleaving gain. It is robust under highly dynamic and fading environment, which is suitable to frequency hopping system and military‘ad hoc’networks.
In this thesis Serially Concatenated Continuous Phase Modulation (SCCPM) and its performance are mainly studied, as well as the algorithms of iterative decoding and the implementation of this system with digital signal processor (DSP). First of all, based on the principle of the CPM signal, a decomposition approach to CPM is developed, and then we present the system model of SCCPM and obtain its performance through computer simulation; secondly, through analysis to the stopping algorithm of dynamic iterative decoding, a new stopping algorithm based on average extrinsic information exchange is proposed, simulation result shows that the combination of average extrinsic information exchange and stopping algorithm of dynamic iterative decoding can improve the BER performance as well as reduce iterative decoding time. Finally we primarily explore the application of SCCPM, and implement it in DSP simulation environment.
引文
[1] C.E.Shannon A mathematical theory of communication.Bell Syst. Tech.J. 27: 379-423/ 623-656. July/Oct.1948
[2] D.J.C.MacKay, "Good error correcting codes based on very sparse matrices," IEEE Trans Inform.Theory, vol.45, no.2, pp.399-431, 1999.
[3]王新梅,肖国镇,“叫错码—原理与方法”西安:西安电子科技大学出版社,1991.
[4] C.Berrou, A.Glavieux, and P.Thitimajshima,"Near Shannon limit error-correcting coding and decoding: turbo-codes,"In Proc.of ICC'93, p.1064-1070, May 1993
[5] D.Divsalar, S.Dolinar, and F.Polara, "Iterative turbo decoder analysis based on density evolution," IEEE Journal on Selected Areas in Communications, vol.19, no.5, pp.891-907, May 2001
[6] R.W.Chang and J.C.Hancock,"On receiver structures for channel shaving memory", IEEE Trans.Inf.Theory, Vol.IT-12, Oct.1966, pp.463-468.
[7] J.Raviv,"Decision making in Markov chains applied to the problem of pattern recognition", IEEE Trans.inf Theory, Vol.IT-13, Oct.1967, pp.536-551.
[8] K.Abend and B.D.Fritchman,"Statistical detection for communication channel swith intersymbol interference", proc.of the IEEE, Vol.58, May 1970, pp .779.785.
[9] G.D.Forney, Jr.,"The Viterbi Algorithm", Proc.of the IEEE, Vol.61, March 1973, pp.268-278
[10] L.R.Bahl, J.Cocke, F.Jelinek, and J.Raviv,"Optimal decoding of linear codes for minimizing symbol error rate", IEEE Trans.Inf.Theory, Vol.IT-20, March 1974, pp.284-287
[11] J.Erfanian, S.Pasupathy, and G.Gulak,"Reduced complexity symbol detectors with paralel structures for ISI channels", IEEE Trans.Comm, Vol.COM-42, Feb/March/April 1994, pp.1661-1671.
[12] Y.Li, B.Vucetic, and Y.Sato,"Optimum soft-output detection for channels with intersymbol interference", IEEE Trans.Inf.Theory, Vol.IT-41, May 1 995, pp.704-713.
[13] J.Hagenauer and P.Hoeber,"A Viterbi algorithm with soft-decision outputs and its applications", Proc. IEEE Global Telecomm.Conf.(GLOBECOM'89), Dalas, TX, USA, Nov.1989, pp. 1680-1686.
[14]刘东华. Turbo码原理与应用技术[M].北京:电子工业出版社
[15] T.Aulin and C.-E.Sundberg, "Continuous phase modulation-PartI and PartII ", IEEE Trans.Commun., vol.COM-29, pp.196-225, May 1981
[16] Bixio E. Rimoldi, "A Decomposition Approach to CPM", IEEE Transactions on Information Theory, Vol.34, NO.2, March 1988
[17] P. Moqvist and T. Aulin,“Serially Concatenated Continuous Phase modulation with Iterative Decoding,”IEEE Trans. on Commun., vol. 49, No. 11, pp. 1901-1915, Nov. 2001.
[18] P.Moqvist, T.Aulin,“Power and Bandwidth Efficient Serially Concatenated CPM with Iterative Decoding”, in Proc. IEEE Global Telecomm. Conf. (GLOBECOM’00), San Francisco, Vol. 2,27 Nov.-1 Dec. 2000 pp.790-794.
[19] T.Richardson.The geometry of turbo decoding dynamics. IEEE Trans. Inform. Theory, 2000, 46:9-23.
[20] D.Agrawal and A.Vardy. The turbo decoding algorithm and its phase trajectories.IEEE Trans.Information Theory, 2001, 47(2):699-722
[21] P.Meshkat and J.D.Villasenor.Generalized Versions of turbo decoding in the famework of Baresian networks and Peral's belief propagation algorithm.Proc. ICC'98. Atlanta, GA,1998, 6:121-125
[22] P.Meshkat and J.D. Villasenor. New schedules for information processing in turbo processing, Proc. ISIT'98.Cambridge, MA, USA 1998, 8:118
[23]韩志学,毕文斌,张兴周,一种提高SCCPM系统迭代检测收敛性的方法.电子与信息学报, Vol.29 No.2 Feb.2007, pp.274-277
[24] P.Moqvist,“Serially concatenated systems: An iterative decoding approach with application to continuous phase modulation,”Lic.Eng. thesis, Chalmers Univ. of Technology, G?teborg, Sweden, 1999. Available:http://www.ce.chalmers.se.
[25] Mark R.Shane, Richard D.Wesel,“Reduced Complexity Iterative Demodulation and Decoding of Serial Concatenated Continuous Phase Modulation”, IEEE Int. Conf. Communications, New York, 28 April-2 May 2002.Vol. 3, pp.1672-1676.
[26] S. Benedetto, D. Divsalar, G. Montorsi, and F. Pollara,“Serial concatenation of interleaved codes: Performance analysis,”IEEE Trans. Inf. Theory, vol. 44, no. 5, pp. 3097–3104, May 1998.
[27] T. Aulin,“Symbol error probability bounds for coherently Viterbi detected continuous phase modulation signals,”IEEE Trans. Commun., vol. COM-29, no. 11, pp. 1707–1715, Nov. 1981.
[28] P. Moqvist and T. Aulin,“Serially concatenated continuous phase modulation with iterative decoding,”IEEE Trans. Commun., vol. 49,no. 11, pp. 1901–1915, Nov. 2001.
[29]彭启琼,李玉柏. DSP技术的发展与应用.高等教育出版社, 2002
[30] Sen M.Kuo, Bob H.Lee.实时数字信号处理——基于TMS320C55X的实现、应用和实验.清华大学出版社, 2003年第1版
[31]李方慧.TMS320C6000系列DSPs原理与应用[M]。电子工业出版社,2002.9
[2] D.J.C.MacKay, "Good error correcting codes based on very sparse matrices," IEEE Trans Inform.Theory, vol.45, no.2, pp.399-431, 1999.
[3]王新梅,肖国镇,“叫错码—原理与方法”西安:西安电子科技大学出版社,1991.
[4] C.Berrou, A.Glavieux, and P.Thitimajshima,"Near Shannon limit error-correcting coding and decoding: turbo-codes,"In Proc.of ICC'93, p.1064-1070, May 1993
[5] D.Divsalar, S.Dolinar, and F.Polara, "Iterative turbo decoder analysis based on density evolution," IEEE Journal on Selected Areas in Communications, vol.19, no.5, pp.891-907, May 2001
[6] R.W.Chang and J.C.Hancock,"On receiver structures for channel shaving memory", IEEE Trans.Inf.Theory, Vol.IT-12, Oct.1966, pp.463-468.
[7] J.Raviv,"Decision making in Markov chains applied to the problem of pattern recognition", IEEE Trans.inf Theory, Vol.IT-13, Oct.1967, pp.536-551.
[8] K.Abend and B.D.Fritchman,"Statistical detection for communication channel swith intersymbol interference", proc.of the IEEE, Vol.58, May 1970, pp .779.785.
[9] G.D.Forney, Jr.,"The Viterbi Algorithm", Proc.of the IEEE, Vol.61, March 1973, pp.268-278
[10] L.R.Bahl, J.Cocke, F.Jelinek, and J.Raviv,"Optimal decoding of linear codes for minimizing symbol error rate", IEEE Trans.Inf.Theory, Vol.IT-20, March 1974, pp.284-287
[11] J.Erfanian, S.Pasupathy, and G.Gulak,"Reduced complexity symbol detectors with paralel structures for ISI channels", IEEE Trans.Comm, Vol.COM-42, Feb/March/April 1994, pp.1661-1671.
[12] Y.Li, B.Vucetic, and Y.Sato,"Optimum soft-output detection for channels with intersymbol interference", IEEE Trans.Inf.Theory, Vol.IT-41, May 1 995, pp.704-713.
[13] J.Hagenauer and P.Hoeber,"A Viterbi algorithm with soft-decision outputs and its applications", Proc. IEEE Global Telecomm.Conf.(GLOBECOM'89), Dalas, TX, USA, Nov.1989, pp. 1680-1686.
[14]刘东华. Turbo码原理与应用技术[M].北京:电子工业出版社
[15] T.Aulin and C.-E.Sundberg, "Continuous phase modulation-PartI and PartII ", IEEE Trans.Commun., vol.COM-29, pp.196-225, May 1981
[16] Bixio E. Rimoldi, "A Decomposition Approach to CPM", IEEE Transactions on Information Theory, Vol.34, NO.2, March 1988
[17] P. Moqvist and T. Aulin,“Serially Concatenated Continuous Phase modulation with Iterative Decoding,”IEEE Trans. on Commun., vol. 49, No. 11, pp. 1901-1915, Nov. 2001.
[18] P.Moqvist, T.Aulin,“Power and Bandwidth Efficient Serially Concatenated CPM with Iterative Decoding”, in Proc. IEEE Global Telecomm. Conf. (GLOBECOM’00), San Francisco, Vol. 2,27 Nov.-1 Dec. 2000 pp.790-794.
[19] T.Richardson.The geometry of turbo decoding dynamics. IEEE Trans. Inform. Theory, 2000, 46:9-23.
[20] D.Agrawal and A.Vardy. The turbo decoding algorithm and its phase trajectories.IEEE Trans.Information Theory, 2001, 47(2):699-722
[21] P.Meshkat and J.D.Villasenor.Generalized Versions of turbo decoding in the famework of Baresian networks and Peral's belief propagation algorithm.Proc. ICC'98. Atlanta, GA,1998, 6:121-125
[22] P.Meshkat and J.D. Villasenor. New schedules for information processing in turbo processing, Proc. ISIT'98.Cambridge, MA, USA 1998, 8:118
[23]韩志学,毕文斌,张兴周,一种提高SCCPM系统迭代检测收敛性的方法.电子与信息学报, Vol.29 No.2 Feb.2007, pp.274-277
[24] P.Moqvist,“Serially concatenated systems: An iterative decoding approach with application to continuous phase modulation,”Lic.Eng. thesis, Chalmers Univ. of Technology, G?teborg, Sweden, 1999. Available:http://www.ce.chalmers.se.
[25] Mark R.Shane, Richard D.Wesel,“Reduced Complexity Iterative Demodulation and Decoding of Serial Concatenated Continuous Phase Modulation”, IEEE Int. Conf. Communications, New York, 28 April-2 May 2002.Vol. 3, pp.1672-1676.
[26] S. Benedetto, D. Divsalar, G. Montorsi, and F. Pollara,“Serial concatenation of interleaved codes: Performance analysis,”IEEE Trans. Inf. Theory, vol. 44, no. 5, pp. 3097–3104, May 1998.
[27] T. Aulin,“Symbol error probability bounds for coherently Viterbi detected continuous phase modulation signals,”IEEE Trans. Commun., vol. COM-29, no. 11, pp. 1707–1715, Nov. 1981.
[28] P. Moqvist and T. Aulin,“Serially concatenated continuous phase modulation with iterative decoding,”IEEE Trans. Commun., vol. 49,no. 11, pp. 1901–1915, Nov. 2001.
[29]彭启琼,李玉柏. DSP技术的发展与应用.高等教育出版社, 2002
[30] Sen M.Kuo, Bob H.Lee.实时数字信号处理——基于TMS320C55X的实现、应用和实验.清华大学出版社, 2003年第1版
[31]李方慧.TMS320C6000系列DSPs原理与应用[M]。电子工业出版社,2002.9