WiMAX基带系统降低PAPR的算法研究及FPGA实现
摘要
随着通信技术飞速发展,移动用户对数据业务的需求不断提高,新一代的移动通信系统期望能提供更高的数据传输率、更好的通信质量、支持更快的终端移动速度。WiMAX(微波接入全球互操作性)即IEEE 802.16系列标准,是宽带移动化的重要里程碑,其中的IEEE 802.16e标准更被称为移动WiMAX,促进了移动宽带的演进和发展。
WiMAX系统以正交频分复用(OFDM)或正交频分多址接入(OFDMA)技术作为其基带信号的调制方式,但是这种技术一直存在着一个固有缺陷,就是峰均功率比(PAPR)过高。这就要求系统中的功率放大器等内部器件具有很大的动态范围和高度线性,以避免传输信号的非线性失真和频谱扩散,然而这么做会导致系统成本和实现难度的增加。
围绕此问题,本论文首先简略地介绍了WiMAX通信技术及其基带子系统的基本原理和关键技术；在此基础上,分析了基带子系统高峰均功率比产生的原因及其分布；然后依次描述了目前国内外降低PAPR的三大主流技术中的各种主要算法及其优缺点,并对这些算法的性能进行了比较,包括是否造成信号线性失真、是否增加系统的发射功率和误比特率(BER)、是否造成系统数据传输速率的损失及计算复杂度和发射接收端实现复杂度；根据IEEE 802.16e标准对降低峰均功率比的要求,再综合考虑硬件实现的复杂度、占用芯片资源等情况,在原有预留子载波算法基础上提出了一种改进算法——受控修剪算法,并根据仿真确定了算法应用的关键参数；最后,基于FPGA实现了该算法,得到比较好的削峰效果,通过对处理时间、硬件资源占用率等性能分析证明本方案在WiMAX基带系统实现中有较大优势。
With the rapid development of communication technology, users of mobile data services as demand increases, so the new wireless communication systems are expected to provide higher transmission rate, offer better quality and support faster moving terminals. WiMAX(Worldwide Interoperability for Microwave Access), namely the series of IEEE 802.16 standards is an important milestone of mobile broadband. The IEEE 802.16e standard is known as mobile WiMAX, it makes the promotion of the mobile broadband evolution and development.
WiMAX system uses orthogonal frequency division multiplexing (OFDM) or orthogonal frequency division multiple access (OFDMA) as the modulation of baseband signal. But the technology has an inherent flaw which is the high Peak to Average Power Ratio (PAPR). This requires the PA system, and other internal device with a large dynamic range and high linearity in order to avoid non-linear distortion of the signal transmission and spread of the spectrum. But to do so will lead to an increase in system cost and more difficult to achieve.
Around this problem, this paper briefly introduces WiMAX communication technology and its basebond subsystem and the basic principles of key technologies firstly; on this basis, it analyzes the causes and distribution of high peak to average power ratio in basebond system; then it descripts the three current domestic and foreign mainstream technologies to get lower PAPR in the variety of algorithms and their main advantages and disadvantages, also the performances of different algorithms are compared, including whether or not caused by linear distortion signal, whether or not to increase the transmitting power system and the bit error rate (BER), whether caused by data transfer rate and the loss of computational complexity and the launch of the receiving end to achieve complexity; according to the IEEE 802.16e standard to reduce PAPR requirements, and considering the complexity of hardware, resources taken up of the chip, an improved method-controlled clipper algorithm is presented based on the original Tone Reservation method, and the key parameters of the algorithm application is determined by simulation; finally, the algorithm is achieved based on the FPGA, and it gained an ideal effect, we can see that this scheme has great advantage in program of WiMAX baseband system from the performance analysis of processing time, occupancy rate of hardware resources.
WiMAX系统以正交频分复用(OFDM)或正交频分多址接入(OFDMA)技术作为其基带信号的调制方式,但是这种技术一直存在着一个固有缺陷,就是峰均功率比(PAPR)过高。这就要求系统中的功率放大器等内部器件具有很大的动态范围和高度线性,以避免传输信号的非线性失真和频谱扩散,然而这么做会导致系统成本和实现难度的增加。
围绕此问题,本论文首先简略地介绍了WiMAX通信技术及其基带子系统的基本原理和关键技术；在此基础上,分析了基带子系统高峰均功率比产生的原因及其分布；然后依次描述了目前国内外降低PAPR的三大主流技术中的各种主要算法及其优缺点,并对这些算法的性能进行了比较,包括是否造成信号线性失真、是否增加系统的发射功率和误比特率(BER)、是否造成系统数据传输速率的损失及计算复杂度和发射接收端实现复杂度；根据IEEE 802.16e标准对降低峰均功率比的要求,再综合考虑硬件实现的复杂度、占用芯片资源等情况,在原有预留子载波算法基础上提出了一种改进算法——受控修剪算法,并根据仿真确定了算法应用的关键参数；最后,基于FPGA实现了该算法,得到比较好的削峰效果,通过对处理时间、硬件资源占用率等性能分析证明本方案在WiMAX基带系统实现中有较大优势。
With the rapid development of communication technology, users of mobile data services as demand increases, so the new wireless communication systems are expected to provide higher transmission rate, offer better quality and support faster moving terminals. WiMAX(Worldwide Interoperability for Microwave Access), namely the series of IEEE 802.16 standards is an important milestone of mobile broadband. The IEEE 802.16e standard is known as mobile WiMAX, it makes the promotion of the mobile broadband evolution and development.
WiMAX system uses orthogonal frequency division multiplexing (OFDM) or orthogonal frequency division multiple access (OFDMA) as the modulation of baseband signal. But the technology has an inherent flaw which is the high Peak to Average Power Ratio (PAPR). This requires the PA system, and other internal device with a large dynamic range and high linearity in order to avoid non-linear distortion of the signal transmission and spread of the spectrum. But to do so will lead to an increase in system cost and more difficult to achieve.
Around this problem, this paper briefly introduces WiMAX communication technology and its basebond subsystem and the basic principles of key technologies firstly; on this basis, it analyzes the causes and distribution of high peak to average power ratio in basebond system; then it descripts the three current domestic and foreign mainstream technologies to get lower PAPR in the variety of algorithms and their main advantages and disadvantages, also the performances of different algorithms are compared, including whether or not caused by linear distortion signal, whether or not to increase the transmitting power system and the bit error rate (BER), whether caused by data transfer rate and the loss of computational complexity and the launch of the receiving end to achieve complexity; according to the IEEE 802.16e standard to reduce PAPR requirements, and considering the complexity of hardware, resources taken up of the chip, an improved method-controlled clipper algorithm is presented based on the original Tone Reservation method, and the key parameters of the algorithm application is determined by simulation; finally, the algorithm is achieved based on the FPGA, and it gained an ideal effect, we can see that this scheme has great advantage in program of WiMAX baseband system from the performance analysis of processing time, occupancy rate of hardware resources.
引文
[1]曾春亮,张宁,王旭莹.WIMAX/802.16原理与应用.机械工业出版社.2007：1-100页
[2]王文博,郑侃.宽带无线通信OFDM技术.北京：人民邮电出版社.2003：15-80页
[3]IEEE Std Part 15.1. Wireless Medium Access Control (MAC) and Physical Layer (PHY) Specifications for Wireless Personal Area Networks (WPANs). June 2002
[4]Irahhauten Z., Nikookar H. and Janssen G. J. M.. An overview of ultra wide band indoor channel measurements and modeling. IEEE microwave and Wireless Components Letters.2004,14(8):386-388P
[5]Israel Koffman and Vincentzio Roman. Broadband wireless access solutions based on OFDM access in IEEE 802.16. IEEE Communication Magazine.2002,4:96-103P
[6]N.Dinur and D.Wulich. Peak to average power ratio in amplitude clipped high orderOFDM. IEEE Military Communications Conference.1998.2: 684-687P
[7]Davis J.A, Jedwab J, Peak-to-mean power control and error correction for OFDM transmission using Golay sequences and Reed-Muller codes, Electronics Letters Volume 33, Issue 4.1997.2:267-268P
[8]Xiaodong Li, Ritcey J.A, M-sequence for OFDM peak-to-average power ratio reduction and error correction, Electronics Letters Volume 33, Issue 7. 1997.3:554-555P
[9]陈琳等.OFDM系统中降低峰均功率比技术的研究.无线电通信技术.2003,29(6)：6-7页
[10]Bauml R W, Fischer R F H and Huber J B.Reducing the peak-to-average power ratio of multicarrier modulation by selected mapping. Electronics Lett.1996.32(22):2056-2057P
[11]S.H.Muller and J.B.Huber. OFDM with reduced peak-to average power ratio byoptimum combination of partial transmit sequences. Electronics Letters.1997.33(5):368-369P
[12]J.Tellado and J.M.Cioffi. PAR reduction with minimal or zero bandwidth lossand low complexity. ANSI, T1E1.4.1998:98-173P
[13]J. Tellado, Peak to Average Power Reduction for Multicarrier Modilation. Ph D. thesis, Stanford University.2000
[14]IEEE Std 802.16-2004. IEEE standard for local and metropolitan area networks, Part 16:Air Interface for Fixed Broadband Wireless Access Systems. Oct 2004
[15]IEEE Std 802.16e. IEEE standard for local and metropolitan area networks, Part 16:Air Interface for Fixed Broadband Wireless Access Systems, Amendment for Physical and Medium Access Control Layers for Combined Fixed and Mobile Operation in Licensed Bands. Feb 2005
[16]Jan-Jaap van de Beek, M.Sandell, P.O.Borjesson. ML Estimation of Time and Frequency Offset in OFDM Systems, IEEE Tran. On Signal Processing. 1997,45(7):1800-1805P
[17]Jiang Yue and Jerry D.Gibson. Performance of OFDM System with Space-Time Coding. Wireless Communications and Net working Conference.2002
[18]尹长川,罗涛,乐光新.多载波宽带无线通信技术.北京：北京邮电大学出版社.2004：31-88页
[19]汪裕民.OFDM关键技术与应用.机械工业出版社.2007：2-40页
[20]佟学俭,罗涛.OFDM移动通信技术原理与应用.北京：人民邮电出版社.2003.6：48-62页
[21]侯鹏.OFDM在实际应用中的关键技术.现代电子技术.2003.30(2)：67-69页
[22]刘昕,王长林.WiMAX关键技术的比较分析.通信与信息技术.2004.8(4)：40-45页
[23]P.H.Moose, A technique for orthorgonal frequency division multiplexing frequency offset correction. IEEE Trans. Commun.1994.42 (10): 2908-2914P
[24]W.D. Warner and C. Leung. OFDM Frame Synchronization for Mobile Radio Data Communication. IEEE Trans. on Vehicular Technology. 1993.42(23):302-313P
[25]Krongold B.S, Jones D.L, PAR reduction in OFDM via active constellation extension, Broadcasting, IEEE Transactions on Volume 49, Issue 3.2003.9: 258-268P
[26]Seung Hee Han, Jae Hong Lee, PAPR reduction of OFDM signals using a reduced complexity PTS, technique Signal Processing Letters, IEEE Volume 11, Issue 11.2004.11:887-890P
[27]Wong Sai Ho, Madhukumar A.S, Chin,F, Peak-to-average power reduction using partial transmit sequences:a suboptimal approach based on dual layered phase sequencing, Broadcasting, IEEE Transactions on Volume 49, Issue 2.2003.6:225-231P
[28]Yan Chan Cho, Seung Hee Han, Jae Hong Lee, Selected mapping technique with novel phase sequences for PAPR reduction of an OFDM signal, Vehicular Technology Conference, Volume 7.2004.9:4781-4785P
[29]Pingyi Fan, Xiang-Gen Xia, Block coded modulation for the reduction of the peak to average power ratio in OFDM systems, Consumer Electronics, IEEE Transactions on Volume 45, Issue 4.1999.9:1025-1029P
[30]Van Nee R.D.J, OFDM codes for peak-to-average power reduction and error correction, Global Telecommunications Conference, Volume 1. 1996.11:740-744P
[31]房海东等.降低正交频分复用信号峰均功率比的方法.中国有线电视.2003.3(4)：18-21页
[32]黄晓等.低复杂度OFDM信号峰均功率比压缩技术.电子学报.2003.31(3)：398-401页
[33]谢小维,谭泽富.减小OFDM信号出现大峰平比的方法研究.中国有线电视.2004.6(2)：10-12页
[34]Tellado J, Cioff.Efficient Algorithms for Reducing PAR in Multicarrier Systems. IEEE ISIT.1998.19(1):25-30P
[35]Tellambura C.Improved phase factor computation for the PAR reduction of an OFDM signal using PTS. IEEE Commun.Lett.2001.5(4):135-137P
[36]房海东,杨知行,潘长勇.一种降低正交频分复用峰均功率比的方法.电讯技术.2002.42(5)
[37]沈亮,基于OFDM系统峰均比问题的研究与FPGA实现.硕士学位论文,东南大学,2006年
[38]刘伟,OFDM系统中降低PAPR的低计算复杂度算法研究.硕士学位论文,汕头大学,2007年
[39]苗晓伟,OFDM系统中峰均功率比问题的研究,硕士学位论文.大连理工大学,2006年
[40]郁光辉,毕冬艳,一种降低正交频分复用通信系统峰均比的装置和方法,中国,H04L27, CN1921468,2007.2
[41]徐光辉,程东旭,黄如.基于FPGA的嵌入式开发与应用.北京：电子工业出版社.2005：1-60页
[42]任晓东.CPLD/FPGA高级应用开发指南.北京：电子工业出版社.2003：8-120页
[43]Michael D. Ciletti. Verilog HDL高级数字设计(张雅绮,李锵).北京： 电子工业出版社.2005.1：361-364页
[44]Altera, FFT MegaCore Function User Guide, San Jose CA.2004.6
[45]张志涌.掌握和精通MATLAB.北京：北京航空航天大学出版社.1997.7
[46]Ray Andraka, A survey of CORDIC algorithms for FPGAs, Proceedings of the 1998 ACM/SIGDA sixth international symposium on Field programmable gate arrays.1998.2:22-24P
[2]王文博,郑侃.宽带无线通信OFDM技术.北京：人民邮电出版社.2003：15-80页
[3]IEEE Std Part 15.1. Wireless Medium Access Control (MAC) and Physical Layer (PHY) Specifications for Wireless Personal Area Networks (WPANs). June 2002
[4]Irahhauten Z., Nikookar H. and Janssen G. J. M.. An overview of ultra wide band indoor channel measurements and modeling. IEEE microwave and Wireless Components Letters.2004,14(8):386-388P
[5]Israel Koffman and Vincentzio Roman. Broadband wireless access solutions based on OFDM access in IEEE 802.16. IEEE Communication Magazine.2002,4:96-103P
[6]N.Dinur and D.Wulich. Peak to average power ratio in amplitude clipped high orderOFDM. IEEE Military Communications Conference.1998.2: 684-687P
[7]Davis J.A, Jedwab J, Peak-to-mean power control and error correction for OFDM transmission using Golay sequences and Reed-Muller codes, Electronics Letters Volume 33, Issue 4.1997.2:267-268P
[8]Xiaodong Li, Ritcey J.A, M-sequence for OFDM peak-to-average power ratio reduction and error correction, Electronics Letters Volume 33, Issue 7. 1997.3:554-555P
[9]陈琳等.OFDM系统中降低峰均功率比技术的研究.无线电通信技术.2003,29(6)：6-7页
[10]Bauml R W, Fischer R F H and Huber J B.Reducing the peak-to-average power ratio of multicarrier modulation by selected mapping. Electronics Lett.1996.32(22):2056-2057P
[11]S.H.Muller and J.B.Huber. OFDM with reduced peak-to average power ratio byoptimum combination of partial transmit sequences. Electronics Letters.1997.33(5):368-369P
[12]J.Tellado and J.M.Cioffi. PAR reduction with minimal or zero bandwidth lossand low complexity. ANSI, T1E1.4.1998:98-173P
[13]J. Tellado, Peak to Average Power Reduction for Multicarrier Modilation. Ph D. thesis, Stanford University.2000
[14]IEEE Std 802.16-2004. IEEE standard for local and metropolitan area networks, Part 16:Air Interface for Fixed Broadband Wireless Access Systems. Oct 2004
[15]IEEE Std 802.16e. IEEE standard for local and metropolitan area networks, Part 16:Air Interface for Fixed Broadband Wireless Access Systems, Amendment for Physical and Medium Access Control Layers for Combined Fixed and Mobile Operation in Licensed Bands. Feb 2005
[16]Jan-Jaap van de Beek, M.Sandell, P.O.Borjesson. ML Estimation of Time and Frequency Offset in OFDM Systems, IEEE Tran. On Signal Processing. 1997,45(7):1800-1805P
[17]Jiang Yue and Jerry D.Gibson. Performance of OFDM System with Space-Time Coding. Wireless Communications and Net working Conference.2002
[18]尹长川,罗涛,乐光新.多载波宽带无线通信技术.北京：北京邮电大学出版社.2004：31-88页
[19]汪裕民.OFDM关键技术与应用.机械工业出版社.2007：2-40页
[20]佟学俭,罗涛.OFDM移动通信技术原理与应用.北京：人民邮电出版社.2003.6：48-62页
[21]侯鹏.OFDM在实际应用中的关键技术.现代电子技术.2003.30(2)：67-69页
[22]刘昕,王长林.WiMAX关键技术的比较分析.通信与信息技术.2004.8(4)：40-45页
[23]P.H.Moose, A technique for orthorgonal frequency division multiplexing frequency offset correction. IEEE Trans. Commun.1994.42 (10): 2908-2914P
[24]W.D. Warner and C. Leung. OFDM Frame Synchronization for Mobile Radio Data Communication. IEEE Trans. on Vehicular Technology. 1993.42(23):302-313P
[25]Krongold B.S, Jones D.L, PAR reduction in OFDM via active constellation extension, Broadcasting, IEEE Transactions on Volume 49, Issue 3.2003.9: 258-268P
[26]Seung Hee Han, Jae Hong Lee, PAPR reduction of OFDM signals using a reduced complexity PTS, technique Signal Processing Letters, IEEE Volume 11, Issue 11.2004.11:887-890P
[27]Wong Sai Ho, Madhukumar A.S, Chin,F, Peak-to-average power reduction using partial transmit sequences:a suboptimal approach based on dual layered phase sequencing, Broadcasting, IEEE Transactions on Volume 49, Issue 2.2003.6:225-231P
[28]Yan Chan Cho, Seung Hee Han, Jae Hong Lee, Selected mapping technique with novel phase sequences for PAPR reduction of an OFDM signal, Vehicular Technology Conference, Volume 7.2004.9:4781-4785P
[29]Pingyi Fan, Xiang-Gen Xia, Block coded modulation for the reduction of the peak to average power ratio in OFDM systems, Consumer Electronics, IEEE Transactions on Volume 45, Issue 4.1999.9:1025-1029P
[30]Van Nee R.D.J, OFDM codes for peak-to-average power reduction and error correction, Global Telecommunications Conference, Volume 1. 1996.11:740-744P
[31]房海东等.降低正交频分复用信号峰均功率比的方法.中国有线电视.2003.3(4)：18-21页
[32]黄晓等.低复杂度OFDM信号峰均功率比压缩技术.电子学报.2003.31(3)：398-401页
[33]谢小维,谭泽富.减小OFDM信号出现大峰平比的方法研究.中国有线电视.2004.6(2)：10-12页
[34]Tellado J, Cioff.Efficient Algorithms for Reducing PAR in Multicarrier Systems. IEEE ISIT.1998.19(1):25-30P
[35]Tellambura C.Improved phase factor computation for the PAR reduction of an OFDM signal using PTS. IEEE Commun.Lett.2001.5(4):135-137P
[36]房海东,杨知行,潘长勇.一种降低正交频分复用峰均功率比的方法.电讯技术.2002.42(5)
[37]沈亮,基于OFDM系统峰均比问题的研究与FPGA实现.硕士学位论文,东南大学,2006年
[38]刘伟,OFDM系统中降低PAPR的低计算复杂度算法研究.硕士学位论文,汕头大学,2007年
[39]苗晓伟,OFDM系统中峰均功率比问题的研究,硕士学位论文.大连理工大学,2006年
[40]郁光辉,毕冬艳,一种降低正交频分复用通信系统峰均比的装置和方法,中国,H04L27, CN1921468,2007.2
[41]徐光辉,程东旭,黄如.基于FPGA的嵌入式开发与应用.北京：电子工业出版社.2005：1-60页
[42]任晓东.CPLD/FPGA高级应用开发指南.北京：电子工业出版社.2003：8-120页
[43]Michael D. Ciletti. Verilog HDL高级数字设计(张雅绮,李锵).北京： 电子工业出版社.2005.1：361-364页
[44]Altera, FFT MegaCore Function User Guide, San Jose CA.2004.6
[45]张志涌.掌握和精通MATLAB.北京：北京航空航天大学出版社.1997.7
[46]Ray Andraka, A survey of CORDIC algorithms for FPGAs, Proceedings of the 1998 ACM/SIGDA sixth international symposium on Field programmable gate arrays.1998.2:22-24P