空间光通信RS码技术研究
摘要
随着通信技术发展的日新月异,通信的方式也不断出新。采用高频激光进行空间光通信已经成为现代通信技术发展的新热点。在空间光通信系统中传送数据信息,由于衰落、噪声和干扰等的影响,信号在传输过程中将产生严重的畸变,这样,就要求采用有效的信道编码方法以保证误码率在允许的范围之内。
本文首先对空间光通信系统进行了概述,进而分析其信道特性,建立了两类信道模型:对应大气条件,建立了高斯信道模型;对应自由空间条件,建立了泊松信道模型。针对这两种信道模型,根据信道编码理论,提出了两种信道编码的设计方案:高斯信道采用交织卷积码方案;泊松信道采用RS码、BCH码级联方案。最后在Matlab上对纠错前后误码性能进行了对比分析。实验结果表明两个方案都是可行的,可以满足两类信道抗干扰的要求。
With the development of communication technology, the method of communication brings forth the fresh continuously .Using high frequency laser to communicate on space satellite have become modern communication a new focus today. Because of the effect of decline , noise and influence , the signals will cause serious distortion during transmission. Therefore , it must adopt an effective error control method which has very strong error-correcting ability to ensure the error rates within the range of permission . RS (Reed-Solomen) code have strong error-correcting ability in both random mistake and sudden mistake.
Firstly, space optical communication system was summaried in this paper, and then the channel characteristics were analyzed, we establish two-type channel models respectively: corresponding air conditions, we establish Gaussian channel; I make a simple introduction of channel-encode and error control system at first, and then explain RS code algorithms and principle , put forward laser communication design scheme, the key technologies such as encode, interleaving, decode are particularly discussion. The whole structural design and algorithms program have finished on FPGA and the performance verification have applied in Matlab. Experiment results showed that it has a good performance, and can reach to the system demand.
while corresponding free space conditions, we establish Possion channel.In allusion to these two models, based on channel coding theory, we design two-type schemes of channel coding: corresponding Gaussian channel,we adopt interleaving convolution code ; while corresponding Possion channel,we make use of RS code、BCH code cascaded. Passing through Matlab simulation and analyzing its performance verification.we have proved two-type schemes feasible and each item satisfied.They are fitly appiled in their channel respectively.
At present, the main method of communications transfers are microwave FDDI system and so on. Microwave-communications can save a great quantity of material to compare with Wire-communications, and can span the intricacy landform easily. And can buildup the communications net with the points and lines combined flexibly.In this way it can make the user who live on the island, mountainous area or countryside exchange the information expediently with the help of trunk line. But compare with FDDI-communications system, Microwave-communications also has some shortcomings just like narrow frequency, channel capacitance limited, code frequency lower and so on. The line of FDDI-communications system has a large capacitance, it is not disturbed easily by environment, but it must have the public channels for install the FDDI. The project construction will be hard and cost longtime and a lot of money if the landform situation badly. Space light-communications combine the merits of FDDI-communications and microwave-communications , it does not only have a large capacitance but also no need to pave the FDDI system. It uses laser to be the carrier of information, it can be used to communicate from space to the land. The transmission characteristic is the light can be transmitted straight and can transmit without wave-guide in the free space. So the Space light-communications obtain the fast development during more than ten years. It becomes one of the most cogent communications methods.
Microwave-communications started to be used as an advanced communications technology in the fiftieth of last century. It becomes one of the important transmit method to communicate with the fast development because of the fast speed of construction, stable quality, easy to maintenance and lower cost, it can also save a lot of colored metal and span the intricacy landform easily to compare with the Wire-communications. But because the Micro-communications line capacitance limited, the Space light-communications technology was created then.
To compare with the Micro-communications, Space light-communications has those merits as below:
1.It increase the channel width, make the information capacitance bigger : the frequency of microwave is about between several GHz to more than ten GHz, but the frequency of laser is about hundreds of THz, it is much bigger about 5 times than Microwave. So it can increase the transmit speed greatly.
2.Small size and light weight: Because the energy of Space light-communications used well, this make the weight of sending set and its power supply system become lighter. And also because of the short wave of laser, with the same requirement of radiation corner and receiving point of view, the antenna caliber of launching and receiving can be also reduced.
3.Direction-sense is much better, density of power increased: the length of laser wave is about between micron and submicron but radio and microwave length is between several ten centimeters and millimeters .
4.The highly of keeping secret : because the width of laser is much narrower than the microwave ,to catch and disturb the narrower laser is very difficult. It can suffice the requirement of keeping secret and disturbance proof, in this way it make communications more safety.
5. Deep space is a good transmission media for the light-wave. Light-wave will waste less when transmit in the deep space. To transmit the same equipment of data and information ,light-communications is the best choice.
Space light-communications has the big capacitance and high speed merit.
Because it will not be affected by the atmosphere when transmit in the space, space can be looked upon as a good stage for space light-communications to show its merit.
RS code increase the ability of disturb proof greatly for the space light-communications system, exert the very important function in space light-communications system. Now RS code (255,223)has become the standard code in the deep space communications for grade contact system between NASA and ESA. In addition, RS code is used widely for computer memorizer, digital tape, Compact Disc and disk. It is mainly used to correct the untidy of the surface causing the mistake. (ex. Disfigurement or dust make the“reading or writing magnetic head and media”changed). For example RS code (15,9) is the standard correcting code for the light storage system. Recently, RS code is used in the daily life on DVB and HDTV.
The assignment of the essay is according to the item requirement,combine the characterizer of the space light-communications system,make the RS code(255,223) which is suitable for the CCSDS standard interlace ,disinterlace ,coding,then dowload to the CMOS chip (FPGA) in order to carry out the wave emulational.Compare the coding data with the original data,then can check the validity and practicability of the design.At last do some contrast and analysis about correcting on the Matlab.
With the development of the channel coding theory, the technology of the channel coding is used widely in the communications engineering area. Especially with the rising of space light-communications, it supply the much wider space for the channel coding. Without any overstatement, with using coding technology in the space light-communications system, to control the mistake of data transmission, reduce the wrong code frequency, increase the dependability of the data transmission, make the stable communications come true. Channel coding technology must have nice future and bright foreground.
本文首先对空间光通信系统进行了概述,进而分析其信道特性,建立了两类信道模型:对应大气条件,建立了高斯信道模型;对应自由空间条件,建立了泊松信道模型。针对这两种信道模型,根据信道编码理论,提出了两种信道编码的设计方案:高斯信道采用交织卷积码方案;泊松信道采用RS码、BCH码级联方案。最后在Matlab上对纠错前后误码性能进行了对比分析。实验结果表明两个方案都是可行的,可以满足两类信道抗干扰的要求。
With the development of communication technology, the method of communication brings forth the fresh continuously .Using high frequency laser to communicate on space satellite have become modern communication a new focus today. Because of the effect of decline , noise and influence , the signals will cause serious distortion during transmission. Therefore , it must adopt an effective error control method which has very strong error-correcting ability to ensure the error rates within the range of permission . RS (Reed-Solomen) code have strong error-correcting ability in both random mistake and sudden mistake.
Firstly, space optical communication system was summaried in this paper, and then the channel characteristics were analyzed, we establish two-type channel models respectively: corresponding air conditions, we establish Gaussian channel; I make a simple introduction of channel-encode and error control system at first, and then explain RS code algorithms and principle , put forward laser communication design scheme, the key technologies such as encode, interleaving, decode are particularly discussion. The whole structural design and algorithms program have finished on FPGA and the performance verification have applied in Matlab. Experiment results showed that it has a good performance, and can reach to the system demand.
while corresponding free space conditions, we establish Possion channel.In allusion to these two models, based on channel coding theory, we design two-type schemes of channel coding: corresponding Gaussian channel,we adopt interleaving convolution code ; while corresponding Possion channel,we make use of RS code、BCH code cascaded. Passing through Matlab simulation and analyzing its performance verification.we have proved two-type schemes feasible and each item satisfied.They are fitly appiled in their channel respectively.
At present, the main method of communications transfers are microwave FDDI system and so on. Microwave-communications can save a great quantity of material to compare with Wire-communications, and can span the intricacy landform easily. And can buildup the communications net with the points and lines combined flexibly.In this way it can make the user who live on the island, mountainous area or countryside exchange the information expediently with the help of trunk line. But compare with FDDI-communications system, Microwave-communications also has some shortcomings just like narrow frequency, channel capacitance limited, code frequency lower and so on. The line of FDDI-communications system has a large capacitance, it is not disturbed easily by environment, but it must have the public channels for install the FDDI. The project construction will be hard and cost longtime and a lot of money if the landform situation badly. Space light-communications combine the merits of FDDI-communications and microwave-communications , it does not only have a large capacitance but also no need to pave the FDDI system. It uses laser to be the carrier of information, it can be used to communicate from space to the land. The transmission characteristic is the light can be transmitted straight and can transmit without wave-guide in the free space. So the Space light-communications obtain the fast development during more than ten years. It becomes one of the most cogent communications methods.
Microwave-communications started to be used as an advanced communications technology in the fiftieth of last century. It becomes one of the important transmit method to communicate with the fast development because of the fast speed of construction, stable quality, easy to maintenance and lower cost, it can also save a lot of colored metal and span the intricacy landform easily to compare with the Wire-communications. But because the Micro-communications line capacitance limited, the Space light-communications technology was created then.
To compare with the Micro-communications, Space light-communications has those merits as below:
1.It increase the channel width, make the information capacitance bigger : the frequency of microwave is about between several GHz to more than ten GHz, but the frequency of laser is about hundreds of THz, it is much bigger about 5 times than Microwave. So it can increase the transmit speed greatly.
2.Small size and light weight: Because the energy of Space light-communications used well, this make the weight of sending set and its power supply system become lighter. And also because of the short wave of laser, with the same requirement of radiation corner and receiving point of view, the antenna caliber of launching and receiving can be also reduced.
3.Direction-sense is much better, density of power increased: the length of laser wave is about between micron and submicron but radio and microwave length is between several ten centimeters and millimeters .
4.The highly of keeping secret : because the width of laser is much narrower than the microwave ,to catch and disturb the narrower laser is very difficult. It can suffice the requirement of keeping secret and disturbance proof, in this way it make communications more safety.
5. Deep space is a good transmission media for the light-wave. Light-wave will waste less when transmit in the deep space. To transmit the same equipment of data and information ,light-communications is the best choice.
Space light-communications has the big capacitance and high speed merit.
Because it will not be affected by the atmosphere when transmit in the space, space can be looked upon as a good stage for space light-communications to show its merit.
RS code increase the ability of disturb proof greatly for the space light-communications system, exert the very important function in space light-communications system. Now RS code (255,223)has become the standard code in the deep space communications for grade contact system between NASA and ESA. In addition, RS code is used widely for computer memorizer, digital tape, Compact Disc and disk. It is mainly used to correct the untidy of the surface causing the mistake. (ex. Disfigurement or dust make the“reading or writing magnetic head and media”changed). For example RS code (15,9) is the standard correcting code for the light storage system. Recently, RS code is used in the daily life on DVB and HDTV.
The assignment of the essay is according to the item requirement,combine the characterizer of the space light-communications system,make the RS code(255,223) which is suitable for the CCSDS standard interlace ,disinterlace ,coding,then dowload to the CMOS chip (FPGA) in order to carry out the wave emulational.Compare the coding data with the original data,then can check the validity and practicability of the design.At last do some contrast and analysis about correcting on the Matlab.
With the development of the channel coding theory, the technology of the channel coding is used widely in the communications engineering area. Especially with the rising of space light-communications, it supply the much wider space for the channel coding. Without any overstatement, with using coding technology in the space light-communications system, to control the mistake of data transmission, reduce the wrong code frequency, increase the dependability of the data transmission, make the stable communications come true. Channel coding technology must have nice future and bright foreground.
引文
1 王萍萍. 空间光通信系统的研究与设计:[硕士学位论文].武汉:武汉大学,2004
2 吴玉成, 杨士中 ,刘嘉兴. 差错控制编码在卫星通信中的应用.电讯技术.2000,1(5):1～5
3 池秀清. 信源编码与信道编码. 科技情报开发与经济. 2001,11(6):1～2
4 Peter Sweeney.差错控制编码.北京:清华大学出版社,2004:12～14
5 任 友. RS 码编译码算法研究及其硬件实现:[硕士学位论文]. 成都:中国电子科技集团公司第十研究所,2003
6 李 劲. Reed-Solomon 码编译码器的研究和仿真:[硕士学位论文]. 成都:成都理工大学,2004
7 白宝明,马啸,王新梅.随机交织器的设计与实现.通信学报.2000,21(6):6～11
8 井洪,尹俊勋.移动信道中交错 RS 码纠错能力的计算机模拟.华南理工大学学报(自然科学版).1996,24(4):.63～69
9 曾晓洋,郝志航, 魏仲慧.RS 码时域编码算法及其计算机模拟.系统工程与电子技术. 2001,23(3):16～18
10 朱起悦.RS 码编码和译码的算法.电讯技术.1999,39(2):23～27
11 史学军,于舒娟.MATLAB 软件在 CDMA 通信仿真中的应用.电脑与信息技术.2003.1(6):1～5
12 杜安源.大气激光通信系统中 RS 码的研究与实现:[硕士学位论文].西安:西安理工大学电路与系统,2005
13 曾晓洋.高性能 Reed-Solomon 码编译码方法及相关技术的研究:[博士学位论文].长春:中国科学院长春光学精密机械与物理研究所,2001
14 徐明远.MATLAB 仿真在通信与电子工程中的应用. 西安:西安电子科技大学出版社,2005
15 曹志刚,钱亚生.《现代通信原理》.北京:清华大学出版社,1992
16 赵曾珠,张兴周,贾红轶.一种新型级联码.应用科技.2005,32(10):20～23
17 刘淑华.空间光通信链路光束捕获、对准、跟踪技术及数字化仿真:[硕士学位论文]. 成都:电子科技大学,2002
18 王军选.信道编码的发展.现代电子技术.2003,164(21):16～18
19 刘玉君.《信道编码》. 河南:河南科学技术出版社.1992
20 林苏,科斯特洛.《差错控制编码基础和应用》(王育民,王新梅 译).北京:人民邮电出版社,1986
21 王晓海.卫星激光通信技术发展现状及未来前景展望.中国航天.2004,6(2):29～31
22 张志涌.精通 MATLAB6.5 版精通.北京:北京航空航天大学出版社,2003
23 赵旦峰,刘会红.卷积码及维特比译码在卫星通信中的应用.无线电工程.2003,33(12):35～40
24 J.Hagenauer,P.Hoeher.A Viterbi Algorithm with Soft-Decision Outputs and its Applications. Process of IEEE Globecom Dallas, Texas,1989:11-17
25 王新梅,马文平,武传坤.《纠错密码理论》.北京:人民邮电出版社,2001
26 王新梅,肖国镇.《纠错码——原理与方法》.西安:西安电子科技大学出版社,2000
27 黄安鹏,无线光 CDMA 信道编码技术研究:[硕士学位论文]. 成都:电子科技大学,2000
28 张鸣瑞,邹世开.《编码理论》.北京:北京航空航天大学出版社,1990
29 G.C.Clark, Jr., J. B. Cain, Error-Correction Coding for Digital Communications,New York: Plenum Press, 1981
30 J.G. Proakis, Digital Communications, New York: McGraw-Hill, 2001
31 S.B.Wicker, Error Control Systems for Digital Communication and Storage, Englewood Cliffs: Prentice-Hall, Inc., 1995
32 S.G.Wilson, Digital Modulation and Coding, Englewood Cliffs: Prentice-Hall,Inc.,1996
33 C.E.Shannon, “A Mathematical Theory of Communications”, Bell Syst. Tech. J.,1948, 27:379～423 & : 623～656
34 D. J. Costello, Jr., J. Hagenauer & H. Imai, et al., “Applications of Error-Control Coding”, IEEE Trans. on Information Theory, 1998,44(6): 2531～2560
35 E.Boutillon, A. Dehamel, “Architecture for a Smart Reed-Solomon Decoder”,IEEE Trans. on Information Theory, 1991, 37(4):236～239
36 E. Petre, G. Masera, “A Parametrical Architecture for Reed-Solomon Decoders”, 1996 IEEE: 81～84
37 E.R. Berlekamp, “Bit-Serial Reed-Solomon Encoders”, IEEE Trans. on Information Theory, 1982, IT-28(6):869～874
38 G.D. Forney, Jr., “Generalized Minimum Distance Decoding”, IEEE Trans. on Information Theory, 1966,IT-12(2):125～131
39 G.D. Forney, Jr., “On Decoding BCH Codes”, IEEE Trans. on Information Theory,1965, IT-11(4): 549～557
40 G. L. Feng, “A VLSI Architecture for Fast Inversion in GF(2m) ”, IEEE Trans. on Computers, 1989,38(10):1383～1386
41 H. Brunner, A. Curiger & M. Hofstetter, “On Computing Multiplicative Inverses in GF(2m) ”, 1993, 42(8):1010～1015
42 H. M. Shao, I. S. Reed, “A VLSI Design of a Pipeline Reed-Solomon Decoder”,IEEE Trans. on Computers, 1985, C-34(5):393～402
43 H.M. Shao, I. S. Reed, “On the VLSI Design of a Pipeline Reed-Solomon Decoder Using Systolic Arrays”,IEEE Trans. On Computers, 1988, 37(10): 1273～1280
2 吴玉成, 杨士中 ,刘嘉兴. 差错控制编码在卫星通信中的应用.电讯技术.2000,1(5):1～5
3 池秀清. 信源编码与信道编码. 科技情报开发与经济. 2001,11(6):1～2
4 Peter Sweeney.差错控制编码.北京:清华大学出版社,2004:12～14
5 任 友. RS 码编译码算法研究及其硬件实现:[硕士学位论文]. 成都:中国电子科技集团公司第十研究所,2003
6 李 劲. Reed-Solomon 码编译码器的研究和仿真:[硕士学位论文]. 成都:成都理工大学,2004
7 白宝明,马啸,王新梅.随机交织器的设计与实现.通信学报.2000,21(6):6～11
8 井洪,尹俊勋.移动信道中交错 RS 码纠错能力的计算机模拟.华南理工大学学报(自然科学版).1996,24(4):.63～69
9 曾晓洋,郝志航, 魏仲慧.RS 码时域编码算法及其计算机模拟.系统工程与电子技术. 2001,23(3):16～18
10 朱起悦.RS 码编码和译码的算法.电讯技术.1999,39(2):23～27
11 史学军,于舒娟.MATLAB 软件在 CDMA 通信仿真中的应用.电脑与信息技术.2003.1(6):1～5
12 杜安源.大气激光通信系统中 RS 码的研究与实现:[硕士学位论文].西安:西安理工大学电路与系统,2005
13 曾晓洋.高性能 Reed-Solomon 码编译码方法及相关技术的研究:[博士学位论文].长春:中国科学院长春光学精密机械与物理研究所,2001
14 徐明远.MATLAB 仿真在通信与电子工程中的应用. 西安:西安电子科技大学出版社,2005
15 曹志刚,钱亚生.《现代通信原理》.北京:清华大学出版社,1992
16 赵曾珠,张兴周,贾红轶.一种新型级联码.应用科技.2005,32(10):20～23
17 刘淑华.空间光通信链路光束捕获、对准、跟踪技术及数字化仿真:[硕士学位论文]. 成都:电子科技大学,2002
18 王军选.信道编码的发展.现代电子技术.2003,164(21):16～18
19 刘玉君.《信道编码》. 河南:河南科学技术出版社.1992
20 林苏,科斯特洛.《差错控制编码基础和应用》(王育民,王新梅 译).北京:人民邮电出版社,1986
21 王晓海.卫星激光通信技术发展现状及未来前景展望.中国航天.2004,6(2):29～31
22 张志涌.精通 MATLAB6.5 版精通.北京:北京航空航天大学出版社,2003
23 赵旦峰,刘会红.卷积码及维特比译码在卫星通信中的应用.无线电工程.2003,33(12):35～40
24 J.Hagenauer,P.Hoeher.A Viterbi Algorithm with Soft-Decision Outputs and its Applications. Process of IEEE Globecom Dallas, Texas,1989:11-17
25 王新梅,马文平,武传坤.《纠错密码理论》.北京:人民邮电出版社,2001
26 王新梅,肖国镇.《纠错码——原理与方法》.西安:西安电子科技大学出版社,2000
27 黄安鹏,无线光 CDMA 信道编码技术研究:[硕士学位论文]. 成都:电子科技大学,2000
28 张鸣瑞,邹世开.《编码理论》.北京:北京航空航天大学出版社,1990
29 G.C.Clark, Jr., J. B. Cain, Error-Correction Coding for Digital Communications,New York: Plenum Press, 1981
30 J.G. Proakis, Digital Communications, New York: McGraw-Hill, 2001
31 S.B.Wicker, Error Control Systems for Digital Communication and Storage, Englewood Cliffs: Prentice-Hall, Inc., 1995
32 S.G.Wilson, Digital Modulation and Coding, Englewood Cliffs: Prentice-Hall,Inc.,1996
33 C.E.Shannon, “A Mathematical Theory of Communications”, Bell Syst. Tech. J.,1948, 27:379～423 & : 623～656
34 D. J. Costello, Jr., J. Hagenauer & H. Imai, et al., “Applications of Error-Control Coding”, IEEE Trans. on Information Theory, 1998,44(6): 2531～2560
35 E.Boutillon, A. Dehamel, “Architecture for a Smart Reed-Solomon Decoder”,IEEE Trans. on Information Theory, 1991, 37(4):236～239
36 E. Petre, G. Masera, “A Parametrical Architecture for Reed-Solomon Decoders”, 1996 IEEE: 81～84
37 E.R. Berlekamp, “Bit-Serial Reed-Solomon Encoders”, IEEE Trans. on Information Theory, 1982, IT-28(6):869～874
38 G.D. Forney, Jr., “Generalized Minimum Distance Decoding”, IEEE Trans. on Information Theory, 1966,IT-12(2):125～131
39 G.D. Forney, Jr., “On Decoding BCH Codes”, IEEE Trans. on Information Theory,1965, IT-11(4): 549～557
40 G. L. Feng, “A VLSI Architecture for Fast Inversion in GF(2m) ”, IEEE Trans. on Computers, 1989,38(10):1383～1386
41 H. Brunner, A. Curiger & M. Hofstetter, “On Computing Multiplicative Inverses in GF(2m) ”, 1993, 42(8):1010～1015
42 H. M. Shao, I. S. Reed, “A VLSI Design of a Pipeline Reed-Solomon Decoder”,IEEE Trans. on Computers, 1985, C-34(5):393～402
43 H.M. Shao, I. S. Reed, “On the VLSI Design of a Pipeline Reed-Solomon Decoder Using Systolic Arrays”,IEEE Trans. On Computers, 1988, 37(10): 1273～1280