GSM系统中的多用户检测技术研究
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摘要
随着移动通信用户的增多,移动通信系统对频谱的需求增大。为了提高频谱利用率,GSM系统采用更加紧密的频率复用方式。高密度的频率复用导致小区内存在大量的同频干扰,严重影响了接收机性能。GSM系统中的多用户检测技术可以有效地抑制同频干扰,对提高接收机性能和增大系统容量具有重要意义。
本文深入研究了GSM系统中的多用户检测技术,主要工作包括：
1.介绍了GSM系统中多用户检测的基本原理,给出了多用户检测系统结构和信号模型,分析了多用户检测系统中的联合信道估计算法。
2.分析和仿真对比了三种联合多用户检测算法：联合最大似然序列估计(JMLSE)算法、联合延迟判决反馈序列估计(JDDFSE)算法和引入自适应状态分配(ASA)的JDDFSE-ASA算法。JMLSE算法性能最优但复杂度高,JDDFSE算法以性能损失为代价获得了复杂度的降低。仿真结果表明：JDDFSE-ASA算法能获得复杂度和性能的折中,具有很大的利用价值。
3.提出了一种新颖的基于Trubo迭代的干扰消除多用户检测算法,该算法对每路同频用户信号分别进行软输入软输出(SISO)检测,利用各译码器输出的软信息重构各用户相互间干扰,从总的接收信号中消除同频干扰,再分别检测各用户信号,以此循环迭代。仿真结果表明：在同频干扰严重的场景下,采用该算法的迭代多用户接收机与传统的Trubo均衡接收机相比具有较大的性能增益。
4.为了降低基于Trubo迭代的干扰消除多用户检测算法的复杂度,本文提出一种新方案,该方案采用基于MMSE准则的软干扰消除算法作为SISO均衡模块算法。基于MMSE准则的软干扰消除算法与基于最大后验概率(MAP)准则的均衡算法相比性能降低,但采用该方案的接收机性能优于传统的Trubo均衡接收机性能。
As the number of GSM subscribers increase quickly, higher spectral efficiency is requested. GSM system uses compact frequency reuse technology to increase the spectral efficiency, which makes Co-channel Interference (CCI) in the cell increase seriously. A GSM system employing conventional detection techniques will be degraded in performance and limited in capacity because of CCI. Multi-user Detection technique applied for GSM is one of the most useful methods to suppress CCI, which makes for good receiver performance and larger system capability.
This thesis investigates algorithms of Multi-user Detection in GSM system, the main work and contributions are described as follows:
1. The principle of Multi-user Detection in GSM system is introduced. Then, the structure of multi-user system and signal model is given. Because of the need of Multi-user Detection, joint channel estimation algorithm is also presented.
2. Three kinds of multi-user detection algorithms:JMLSE, JDDFSE and JDDFSE-ASA are analyzed and simulated. Joint Delayed-Decision Feedback Sequence Estimation (JMLSE) is the optimum algorithm, but its computational complexity is too high. Joint Delayed-Decision Feedback Sequence Estimation (JDDFSE) is a suboptimum algorithm, the performance of which can be increased by adaptive state allocation technique (ASA). Simulation results show that JDDFSE-ASA is valuable, which takes good compromise between performance and complexity.
3. A new multi-user detection algorithm based on Turbo iterative procedure is proposed. The algorithm detects each co-channel signal with a soft-input soft-output (SISO) detector separately. The soft information provided by the decoders is used as the a priori information for the iterative cancellation of CCI. Simulation exhibits that the receiver employing the proposed algorithm outperforms conventional Turbo receiver for CCI dominated scenarios.
4. To reduce the complexity of proposed algorithm, a new scheme is put forward, in which a soft interference cancellation algorithm based on MMSE is used for SISO equalization. Though MMSE-SIC algorithm is inferior to MAP equalization algorithm, the proposed receiver employing this scheme outperforms conventional Turbo receiver.
本文深入研究了GSM系统中的多用户检测技术,主要工作包括：
1.介绍了GSM系统中多用户检测的基本原理,给出了多用户检测系统结构和信号模型,分析了多用户检测系统中的联合信道估计算法。
2.分析和仿真对比了三种联合多用户检测算法：联合最大似然序列估计(JMLSE)算法、联合延迟判决反馈序列估计(JDDFSE)算法和引入自适应状态分配(ASA)的JDDFSE-ASA算法。JMLSE算法性能最优但复杂度高,JDDFSE算法以性能损失为代价获得了复杂度的降低。仿真结果表明：JDDFSE-ASA算法能获得复杂度和性能的折中,具有很大的利用价值。
3.提出了一种新颖的基于Trubo迭代的干扰消除多用户检测算法,该算法对每路同频用户信号分别进行软输入软输出(SISO)检测,利用各译码器输出的软信息重构各用户相互间干扰,从总的接收信号中消除同频干扰,再分别检测各用户信号,以此循环迭代。仿真结果表明：在同频干扰严重的场景下,采用该算法的迭代多用户接收机与传统的Trubo均衡接收机相比具有较大的性能增益。
4.为了降低基于Trubo迭代的干扰消除多用户检测算法的复杂度,本文提出一种新方案,该方案采用基于MMSE准则的软干扰消除算法作为SISO均衡模块算法。基于MMSE准则的软干扰消除算法与基于最大后验概率(MAP)准则的均衡算法相比性能降低,但采用该方案的接收机性能优于传统的Trubo均衡接收机性能。
As the number of GSM subscribers increase quickly, higher spectral efficiency is requested. GSM system uses compact frequency reuse technology to increase the spectral efficiency, which makes Co-channel Interference (CCI) in the cell increase seriously. A GSM system employing conventional detection techniques will be degraded in performance and limited in capacity because of CCI. Multi-user Detection technique applied for GSM is one of the most useful methods to suppress CCI, which makes for good receiver performance and larger system capability.
This thesis investigates algorithms of Multi-user Detection in GSM system, the main work and contributions are described as follows:
1. The principle of Multi-user Detection in GSM system is introduced. Then, the structure of multi-user system and signal model is given. Because of the need of Multi-user Detection, joint channel estimation algorithm is also presented.
2. Three kinds of multi-user detection algorithms:JMLSE, JDDFSE and JDDFSE-ASA are analyzed and simulated. Joint Delayed-Decision Feedback Sequence Estimation (JMLSE) is the optimum algorithm, but its computational complexity is too high. Joint Delayed-Decision Feedback Sequence Estimation (JDDFSE) is a suboptimum algorithm, the performance of which can be increased by adaptive state allocation technique (ASA). Simulation results show that JDDFSE-ASA is valuable, which takes good compromise between performance and complexity.
3. A new multi-user detection algorithm based on Turbo iterative procedure is proposed. The algorithm detects each co-channel signal with a soft-input soft-output (SISO) detector separately. The soft information provided by the decoders is used as the a priori information for the iterative cancellation of CCI. Simulation exhibits that the receiver employing the proposed algorithm outperforms conventional Turbo receiver for CCI dominated scenarios.
4. To reduce the complexity of proposed algorithm, a new scheme is put forward, in which a soft interference cancellation algorithm based on MMSE is used for SISO equalization. Though MMSE-SIC algorithm is inferior to MAP equalization algorithm, the proposed receiver employing this scheme outperforms conventional Turbo receiver.
引文
[1]G Xu, et al., "Maximum likelihood detection of co-channel communications signals via exploitation of spatial diversity," Proc.26th Asilomar Conf. Signals, Syst., Comput. Pacific Grove, CA, pp.1142-1146, Oct.1992.
[2]P. A. Hoeher et al., "Single-antenna co-channel interference cancellation for TDMA cellular radio systems," IEEE Wireless Commun., vol.12, No.2, pp.30-37, Apr. 2005.
[3]C. Tidestav, M. Sternad, and A. Ahlen, "Reuse within a cell-interference rejection or multi-user detection," IEEE Trans. Commun., vol.47, pp.1511-1522, Oct. 1999.
[4]S. Verdu, Multi-user Detection, New York:Cambridge University Press,1998.
[5]S. Verdu, "Minimum Probability of error for asynchronous Gaussian multiple access channels", IEEE Trans, Inform,1986, vol-IT, No.1, pp:85-96.
[6]P. Ranta, A. Hottinen, and Z.-C. Honkasalo, "Co-channel interference cancellation receiver for TDMA mobile systems", in Proc. IEEE ICC'95, Seattle, pp.17-21, June 1995.
[7]G David Fomey. Jr., "Maximum-Likelihood Sequence Estimation of Digital Sequences in the Presence of Inter-symbol Interference", IEEE Trans. on In Theory, Vol.1T-18, No.3, May 1912, pp.363-378.
[8]W. Etten, "Maximum likelihood receiver for multiple channel transmission systems," IEEE Trans. Commun. vol.24, no.2, pp.276-283, Feb.1976.
[9]K. Girid., "Joint estimation algorithms for co-channel signal demodulation," in Proc. IEEE ICC'93, Geneva, Switzerland, pp.1497-1501, May 1993.
[10]L. Nie., "Comparison of Exact and Approximate Multi-User Detection for GSM", Master's thesis Informatics and Mathematical Modeling, DTU.2005.
[11]Hafeez, A., Hui, D., and Arslan, H., "Interference cancellation for EDGE via two-user joint demodulation," Proc. IEEE VTC, fall.2003.
[12]Hoeher PA, Badri-Hoeher S. Deng S, et al., "Single antenna interference cancellation (SAIC) for cellular TDMA networks by means of joint delayed-decision feedback sequence estimation," [J]. IEEE Trans on Wireless Commun,2006,5(6):1234-1237.
[13]M. Eyuboglu and S. Qureshi, "Reduced-state sequence estimation with set partitioning and decision feedback," IEEE Trans. Commun., vol.36, pp.13-20, Jan. 1988.
[14]P. Nickel and W. H. Gerstacker. "Single Antenna Interference Cancellation using Prefiltering and Multi-user Joint Detection based on the M-Algorithm," 14th IST Mobile & Wireless Communications Summit (IST'05), Dresden, Germany, June 2005.user Joint Detection based.
[15]Detert, T. Drauge, R., "An Improved Joint M-Algorithm for Single Antenna Interference Cancellation in TDMA Mobile Radio," IEEE International Conference on Communications, ICC'07, pp.6018-6025,24-28 June 2007.
[16]"Complexity reduction of the MLSD/MLSDE receiver using the adaptive state allocation algorithm," IEEE Trans. Wireless Commun., vol.1, pp.101-111, Jan. 2002.
[17]Marc Chenu-Tournier, Philippe Morgand, and Didier Pirez, "Multi-user detection using mimo channel estimator applied to gsm communications".In IEEE MIMO Communications from concept to implementation, Jan.2002..
[18]P. Nickel, W.H. Gerstacker, and W. Koch. "Turbo Equalization for Single Antenna Co-channel Interference Cancellation in Single Carrier Transmission Systems," IEEE 50th Global Communications Conference (Globe com 2007), Washington, D.C., USA, November 2007.
[19]H. Schoeneich, P. Hoeher, "Single antenna co-channel interference cancellation in asynchronous TDMA systems," in:Proceedings of the Sixth Baiona Workshop on Signal Processing in Communications, Baiona, Spain,2003, pp.157-162.
[20]G SM 05.03 version 8.4.1Release 1999 (Channel coding).
[21]GSM 05.04 version 8.1.2 Release 1999 (Modulation).
[22]GSM 05.05 version 8.5.1 Release 1999 (Radio transmission and reception).
[23]GSM 05.02 version 5.1.0 Release 1996(Multiplexing and multiple access on the radio path).
[24]P. A. Laurent, "Extract and approximate construction of digital phase modulations by superposition of amplitude modulated pulses (AMP)," IEEE Trans. Commun., February 1986, vol.34, pp.150-160.
[25]A. Duel-Hallen and C. Heegard, "Delayed decision-feedback sequence estimation," IEEE Trans. Commun., vol.37, no.5,pp.428-436, May 1989.
[26]C. Douillard, M. JBzBquel, C. Berrou, A. Picart, P. Didier, and A. Glavieux, "Iterative correction of inter-symbol interference:Turbo equalization," European Transactions on Telecommunications, vol.6, pp.507-511, September-October 1995.
[27]王新梅,肖国镇.纠错码-原理与方法.西安电子科技大学出版社.西安.1991.
[28]Michael Tuchler, Ralf Koetter, C. Singer. "Turbo Equalization:Principles and New Results," Transaction on Comm IEEE.Vol 2.50, NO.5. May 2002, pp.754-767.
[29]P. Robertson, E. Villebrun, P.Holier, "A Comparison of Optimal and Sub-Optimal MAP Decoding Algorithms Operating in the Log Domain," Proceeding of the International Conference communications, (Seattle, United states), June,1995, pp.1009-1013.
[30]BauchG, Khorram. H, Hagenauer J., "Iterative equalization and decoding in mobile communications systems," [C] EPMCC 1997. Bonn, Germany:[s.n.],1997: 307-312.
[31]刘文杰,王视环,傅海阳,“码分多址信道中的迭代译码及干扰消除技术”,南京邮电学院通信工程系.
[32]Robertson P, Hoeher P, Villebrun E., "Optimal and sub-optimal maximum a posteriori algorithms suitable for turbo decoding," [J]. Euro Trans Telecomms, 1997,8(2):119-125.
[33]POOR H V, VERDU S., "Probability of Error in MMSE Multi-user Detection," [J]. IEEE Trans on Inform Theory,1997,43:858-871.
[34]A. Duel-Hallen and C. Heegard, "Improved Turbo SICMMSE Equalization for Coded Inter-symbol Interference Channels" IEEE Trans. Commun., vol.37, no.5, may 1998.
[2]P. A. Hoeher et al., "Single-antenna co-channel interference cancellation for TDMA cellular radio systems," IEEE Wireless Commun., vol.12, No.2, pp.30-37, Apr. 2005.
[3]C. Tidestav, M. Sternad, and A. Ahlen, "Reuse within a cell-interference rejection or multi-user detection," IEEE Trans. Commun., vol.47, pp.1511-1522, Oct. 1999.
[4]S. Verdu, Multi-user Detection, New York:Cambridge University Press,1998.
[5]S. Verdu, "Minimum Probability of error for asynchronous Gaussian multiple access channels", IEEE Trans, Inform,1986, vol-IT, No.1, pp:85-96.
[6]P. Ranta, A. Hottinen, and Z.-C. Honkasalo, "Co-channel interference cancellation receiver for TDMA mobile systems", in Proc. IEEE ICC'95, Seattle, pp.17-21, June 1995.
[7]G David Fomey. Jr., "Maximum-Likelihood Sequence Estimation of Digital Sequences in the Presence of Inter-symbol Interference", IEEE Trans. on In Theory, Vol.1T-18, No.3, May 1912, pp.363-378.
[8]W. Etten, "Maximum likelihood receiver for multiple channel transmission systems," IEEE Trans. Commun. vol.24, no.2, pp.276-283, Feb.1976.
[9]K. Girid., "Joint estimation algorithms for co-channel signal demodulation," in Proc. IEEE ICC'93, Geneva, Switzerland, pp.1497-1501, May 1993.
[10]L. Nie., "Comparison of Exact and Approximate Multi-User Detection for GSM", Master's thesis Informatics and Mathematical Modeling, DTU.2005.
[11]Hafeez, A., Hui, D., and Arslan, H., "Interference cancellation for EDGE via two-user joint demodulation," Proc. IEEE VTC, fall.2003.
[12]Hoeher PA, Badri-Hoeher S. Deng S, et al., "Single antenna interference cancellation (SAIC) for cellular TDMA networks by means of joint delayed-decision feedback sequence estimation," [J]. IEEE Trans on Wireless Commun,2006,5(6):1234-1237.
[13]M. Eyuboglu and S. Qureshi, "Reduced-state sequence estimation with set partitioning and decision feedback," IEEE Trans. Commun., vol.36, pp.13-20, Jan. 1988.
[14]P. Nickel and W. H. Gerstacker. "Single Antenna Interference Cancellation using Prefiltering and Multi-user Joint Detection based on the M-Algorithm," 14th IST Mobile & Wireless Communications Summit (IST'05), Dresden, Germany, June 2005.user Joint Detection based.
[15]Detert, T. Drauge, R., "An Improved Joint M-Algorithm for Single Antenna Interference Cancellation in TDMA Mobile Radio," IEEE International Conference on Communications, ICC'07, pp.6018-6025,24-28 June 2007.
[16]"Complexity reduction of the MLSD/MLSDE receiver using the adaptive state allocation algorithm," IEEE Trans. Wireless Commun., vol.1, pp.101-111, Jan. 2002.
[17]Marc Chenu-Tournier, Philippe Morgand, and Didier Pirez, "Multi-user detection using mimo channel estimator applied to gsm communications".In IEEE MIMO Communications from concept to implementation, Jan.2002..
[18]P. Nickel, W.H. Gerstacker, and W. Koch. "Turbo Equalization for Single Antenna Co-channel Interference Cancellation in Single Carrier Transmission Systems," IEEE 50th Global Communications Conference (Globe com 2007), Washington, D.C., USA, November 2007.
[19]H. Schoeneich, P. Hoeher, "Single antenna co-channel interference cancellation in asynchronous TDMA systems," in:Proceedings of the Sixth Baiona Workshop on Signal Processing in Communications, Baiona, Spain,2003, pp.157-162.
[20]G SM 05.03 version 8.4.1Release 1999 (Channel coding).
[21]GSM 05.04 version 8.1.2 Release 1999 (Modulation).
[22]GSM 05.05 version 8.5.1 Release 1999 (Radio transmission and reception).
[23]GSM 05.02 version 5.1.0 Release 1996(Multiplexing and multiple access on the radio path).
[24]P. A. Laurent, "Extract and approximate construction of digital phase modulations by superposition of amplitude modulated pulses (AMP)," IEEE Trans. Commun., February 1986, vol.34, pp.150-160.
[25]A. Duel-Hallen and C. Heegard, "Delayed decision-feedback sequence estimation," IEEE Trans. Commun., vol.37, no.5,pp.428-436, May 1989.
[26]C. Douillard, M. JBzBquel, C. Berrou, A. Picart, P. Didier, and A. Glavieux, "Iterative correction of inter-symbol interference:Turbo equalization," European Transactions on Telecommunications, vol.6, pp.507-511, September-October 1995.
[27]王新梅,肖国镇.纠错码-原理与方法.西安电子科技大学出版社.西安.1991.
[28]Michael Tuchler, Ralf Koetter, C. Singer. "Turbo Equalization:Principles and New Results," Transaction on Comm IEEE.Vol 2.50, NO.5. May 2002, pp.754-767.
[29]P. Robertson, E. Villebrun, P.Holier, "A Comparison of Optimal and Sub-Optimal MAP Decoding Algorithms Operating in the Log Domain," Proceeding of the International Conference communications, (Seattle, United states), June,1995, pp.1009-1013.
[30]BauchG, Khorram. H, Hagenauer J., "Iterative equalization and decoding in mobile communications systems," [C] EPMCC 1997. Bonn, Germany:[s.n.],1997: 307-312.
[31]刘文杰,王视环,傅海阳,“码分多址信道中的迭代译码及干扰消除技术”,南京邮电学院通信工程系.
[32]Robertson P, Hoeher P, Villebrun E., "Optimal and sub-optimal maximum a posteriori algorithms suitable for turbo decoding," [J]. Euro Trans Telecomms, 1997,8(2):119-125.
[33]POOR H V, VERDU S., "Probability of Error in MMSE Multi-user Detection," [J]. IEEE Trans on Inform Theory,1997,43:858-871.
[34]A. Duel-Hallen and C. Heegard, "Improved Turbo SICMMSE Equalization for Coded Inter-symbol Interference Channels" IEEE Trans. Commun., vol.37, no.5, may 1998.