OFDM无线局域网关键技术的FPGA实现
摘要
无线局域网(WLAN)是未来移动通信系统的重要组成部分。由于摆脱了有线连接的束缚,无线局域网具有移动性好、成本低以及网络传输故障少等诸多优点,得到了越来越广泛的发展与应用。正交频分复用(OFDM)技术具有抗多径衰落,频谱利用率高等优点,特别适合于无线环境下的高速数据传输,是高速无线局域网的首选技术之一。从IEEE802.11a,IEEE802.11g到IEEE802.11n都是以OFDM为基础。随着OFDM技术的普及以及下一代通信技术对OFDM的青睐,研究与实现应用于无线局域网的OFDM关键技术具有一定的意义。
本文首先介绍了WLAN的基本概念及相关协议标准和OFDM系统的工作原理,并描述了基于IEEE802.11a和IEEE802.11n标准的OFDM系统的数据帧结构以及系统参数。文中对OFDM传输系统的关键算法进行了详细的研究。然后以Xilinx公司的ISE10.1为软件平台,利用VHDL描述的方式,并以FPGA(现场可编程门阵列)芯片SPARTAN-3E为硬件平台,研究实现了适用于IEEE802.11a和IEEE802.11n的64点16bits复数块浮点结构的FFT模块,(2,1,7)卷积编码和维特比译码模块,以及分组检测和符号定时模块,并进行了仿真、综合、下载验证等工作。
Wireless Local Area Network (WLAN) will become one of the important parts of mobile communication system in the future. Without wires, WLAN is of a good deal of merits, such as high mobility, low cost, little circuit troubles and so on. It is being developed and applied more and more widely. OFDM technology has many advantages, such as robustness against multipath fading and high bandwidth efficiency, which are suitable for the high-rate data transmission in wireless environments. Accordingly, OFDM is one of the preferred techniques in WLAN. IEEE802.11a,IEEE802.11g and IEEE802.11n are all based on OFDM. As OFDM becomes more and more widely applied in the next generation of telecommunication technology, the research and implementation of the key techniques of the OFDM for WLAN is valuable.
Some basic conceptions of WLAN, the standards involved, and the principle of OFDM system are introduced. The OFDM frame structure and system parameters based on the IEEE 802.11a and IEEE 802.11n specifications are described. The key algorithms in the OFDM systems are analyzed. Then, with VHDL description, a 64-point block-floating point complex FFT module, a (2,1,7) convolutional encoder and Viterbi decoder module, and a packet detection and synchronization module are implemented on Xilinx ISE10.1 and SPARTAN-3E FPGA platform. All of them are suitable for IEEE802.11a and IEEE802.11n. The modules are simulated, synthesized, and downloaded.
本文首先介绍了WLAN的基本概念及相关协议标准和OFDM系统的工作原理,并描述了基于IEEE802.11a和IEEE802.11n标准的OFDM系统的数据帧结构以及系统参数。文中对OFDM传输系统的关键算法进行了详细的研究。然后以Xilinx公司的ISE10.1为软件平台,利用VHDL描述的方式,并以FPGA(现场可编程门阵列)芯片SPARTAN-3E为硬件平台,研究实现了适用于IEEE802.11a和IEEE802.11n的64点16bits复数块浮点结构的FFT模块,(2,1,7)卷积编码和维特比译码模块,以及分组检测和符号定时模块,并进行了仿真、综合、下载验证等工作。
Wireless Local Area Network (WLAN) will become one of the important parts of mobile communication system in the future. Without wires, WLAN is of a good deal of merits, such as high mobility, low cost, little circuit troubles and so on. It is being developed and applied more and more widely. OFDM technology has many advantages, such as robustness against multipath fading and high bandwidth efficiency, which are suitable for the high-rate data transmission in wireless environments. Accordingly, OFDM is one of the preferred techniques in WLAN. IEEE802.11a,IEEE802.11g and IEEE802.11n are all based on OFDM. As OFDM becomes more and more widely applied in the next generation of telecommunication technology, the research and implementation of the key techniques of the OFDM for WLAN is valuable.
Some basic conceptions of WLAN, the standards involved, and the principle of OFDM system are introduced. The OFDM frame structure and system parameters based on the IEEE 802.11a and IEEE 802.11n specifications are described. The key algorithms in the OFDM systems are analyzed. Then, with VHDL description, a 64-point block-floating point complex FFT module, a (2,1,7) convolutional encoder and Viterbi decoder module, and a packet detection and synchronization module are implemented on Xilinx ISE10.1 and SPARTAN-3E FPGA platform. All of them are suitable for IEEE802.11a and IEEE802.11n. The modules are simulated, synthesized, and downloaded.
引文
[1] Juha Heiskala, John Terry著,杨晓春,何建吾译. OFDM无线局域网.北京:电子工业出版社,2003. pp:21-42.
[2]田耘,徐文波,张延伟.无线通信FPGA设计.北京:电子工业出版社,2008. pp:5-20.
[3] J.Terry, J.Heiskala. OFDM Wirelsee LANs: A Theroretical and Practical Guide. Indianapolis,Indiana, 46290,USA: Sams Publishing, 201 West 103rd St.. September, 2002.
[4] S.Weinstein,P.Ebert. Data Transmission by Frequency-Division Multiplexing Using The Discrete Fourier transform, IEEE Transaction on Communications, Volume :19,Issue:5. pp:628-634.
[5]闫峥.基于IEEE802.11a无线局域网中正交频分复用技术研究.南京航空航天大学硕士学位论文.2006.pp:7-14.
[6] IEEE Std 802.11-1999. Wireless LAN Medium Acess Control (MAC) and Physical Layer(PHY) Specifications. The Institute of Electrical and Electronics Engineers, Inc.
[7] IEEE Std.802.11a-1999. Wireless LAN Medium Access Contol (MAC) and Physical Layer(PHY) Specification High-speed Physical Layer in the 5 GHz Band. The Institute of Electrical and Rlectronics Engineers,Inc.
[8] Draft STANDARD for Information Technology-Telecommunications and information exchange between systems-Local and metropolitan area networks-Specific requirements-Partl1 : Wireless LAN Medium Access Control(MAC) and Physical Layer(PHY) specifications: Amendment :Enhancements for Higher Throughput,IEEE Draft Std P8021l n/D2.00. February 2007.
[9] J.W.Cooley, J.W.Tukey, An Algorithm for the Machine Computation of Complex Fourier Series. Mathematics of Computation,1965,19. pp:297-301.
[10]郑成根.802.11a物理层数字处理技术研究.北京邮电大学硕士学位论文.2003.
[11]蔡可红.基于FPGA的FFT设计.南京理工大学硕士学位论文.2006.6.
[12] Yutai Ma, Lars Wanhammar. A Hardware Efficient Control of Memory Addressing for High-Performance FFT Processors.IEEE Transaction SignalProcessing. Vol.48, NO.3. March 2000.
[13]王诚,薛小刚,钟信潮. FPGA/CPLD设计工具.北京:人民邮电出版社,2004.
[14]马余泰. FFT处理器无冲突地址生成方法.计算机学报.1995,18(11). pp:875-880.
[15]刘朝晖,韩月秋.用FPGA实现FFT的研究.北京理工大学学报,1999,19(2). pp:234-238.
[16]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,2001.
[17] John G .Proakis. Digital Communication. McGraw-Hill,2001.
[18]罗苑棠. CPLD/FPGA常用模块与综合系统设计实例精讲.北京:电子工业出版社,2007.
[19]刘树棠译.现代通信系统-使用MATLAB.西安:西安交通大学出版社,2001.
[20]庞永强.基于FPGA的Viterbi译码器实现.电子科技大学硕士学位论文,2006. pp:35-55.
[21] WeiChen. RTL Implementation of Viterbi Decoder. Master thesis. June 02, 2006. pp:12-17.
[22] A. Peled, A. Ruiz. Frequency domain data transmission using reduced computational complexity algorithms,in Proc. IEEE Int. Conf. Acoust., Speech, Signal Processing, 1980. pp: 964-967.
[23] Timothy M. Schmidl, Donald C. Cox. Robust Frequency and Timing Synchronization for OFDM. IEEE Trans. Comm.,vol. 45, December 1997. pp:1613-1621.
[24] Andreas Czylwink. Synchronization for Systems with Antenna Diversity. Vehicular Technology Conference, 1999. IEEE VTS 50th,Volume:2. Sep. 1999. pp: 728– 732.
[25] Won-Gi Jeon, You Y. H., Kim J.T. Timing synchronization for IEEE 802.15.3 WPAN applications, IEEE Communications Letters,Volume 9,Issue 3. March 2005. pp:255– 257.
[26] Won-Gi Jeon, You Y.-H., Kim J.T., Dong-Sun Kim; Timing synchronization for IEEE 802.15.3 WPAN applications, IEEE Communications Letters, Volume 9, Issue 3. March 2005. pp:255-257.
[27] Lambrette U., Speth M., Meyr H.,OFDM burst frequency synchronization by single carrier training data, IEEE Communications Letters, Volume 1, Issue 2, March 1997. pp:46– 48.
[28] Guangliang REN, Yilin CHANG , Hui ZHANG and Huining ZHANG.Synchronization Method Based on A New Constant Envelop Preamble for OFDM Systems. IEEE Transaction on Broadcasting, Volume51, No.1, March 2005. pp.139-143.
[29]张鑫,李颖,魏急波.基于软件无线电的OFDM传输系统基带电路设计[J].电子产品世界,2003,19期.
[30]杨晓.突发OFDM系统接收机同步算法设计及其FPGA实现.浙江大学,2005.
[31]赵亮.宽带OFDM系统研究及FPGA实现.浙江大学硕士学位论文,2006.
[32]张骋.基于IEEE 802.11n的MIMO-OFDM无线局域网系统的同步算法研究.浙江大学硕士学位论文, 2008.
[2]田耘,徐文波,张延伟.无线通信FPGA设计.北京:电子工业出版社,2008. pp:5-20.
[3] J.Terry, J.Heiskala. OFDM Wirelsee LANs: A Theroretical and Practical Guide. Indianapolis,Indiana, 46290,USA: Sams Publishing, 201 West 103rd St.. September, 2002.
[4] S.Weinstein,P.Ebert. Data Transmission by Frequency-Division Multiplexing Using The Discrete Fourier transform, IEEE Transaction on Communications, Volume :19,Issue:5. pp:628-634.
[5]闫峥.基于IEEE802.11a无线局域网中正交频分复用技术研究.南京航空航天大学硕士学位论文.2006.pp:7-14.
[6] IEEE Std 802.11-1999. Wireless LAN Medium Acess Control (MAC) and Physical Layer(PHY) Specifications. The Institute of Electrical and Electronics Engineers, Inc.
[7] IEEE Std.802.11a-1999. Wireless LAN Medium Access Contol (MAC) and Physical Layer(PHY) Specification High-speed Physical Layer in the 5 GHz Band. The Institute of Electrical and Rlectronics Engineers,Inc.
[8] Draft STANDARD for Information Technology-Telecommunications and information exchange between systems-Local and metropolitan area networks-Specific requirements-Partl1 : Wireless LAN Medium Access Control(MAC) and Physical Layer(PHY) specifications: Amendment :Enhancements for Higher Throughput,IEEE Draft Std P8021l n/D2.00. February 2007.
[9] J.W.Cooley, J.W.Tukey, An Algorithm for the Machine Computation of Complex Fourier Series. Mathematics of Computation,1965,19. pp:297-301.
[10]郑成根.802.11a物理层数字处理技术研究.北京邮电大学硕士学位论文.2003.
[11]蔡可红.基于FPGA的FFT设计.南京理工大学硕士学位论文.2006.6.
[12] Yutai Ma, Lars Wanhammar. A Hardware Efficient Control of Memory Addressing for High-Performance FFT Processors.IEEE Transaction SignalProcessing. Vol.48, NO.3. March 2000.
[13]王诚,薛小刚,钟信潮. FPGA/CPLD设计工具.北京:人民邮电出版社,2004.
[14]马余泰. FFT处理器无冲突地址生成方法.计算机学报.1995,18(11). pp:875-880.
[15]刘朝晖,韩月秋.用FPGA实现FFT的研究.北京理工大学学报,1999,19(2). pp:234-238.
[16]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,2001.
[17] John G .Proakis. Digital Communication. McGraw-Hill,2001.
[18]罗苑棠. CPLD/FPGA常用模块与综合系统设计实例精讲.北京:电子工业出版社,2007.
[19]刘树棠译.现代通信系统-使用MATLAB.西安:西安交通大学出版社,2001.
[20]庞永强.基于FPGA的Viterbi译码器实现.电子科技大学硕士学位论文,2006. pp:35-55.
[21] WeiChen. RTL Implementation of Viterbi Decoder. Master thesis. June 02, 2006. pp:12-17.
[22] A. Peled, A. Ruiz. Frequency domain data transmission using reduced computational complexity algorithms,in Proc. IEEE Int. Conf. Acoust., Speech, Signal Processing, 1980. pp: 964-967.
[23] Timothy M. Schmidl, Donald C. Cox. Robust Frequency and Timing Synchronization for OFDM. IEEE Trans. Comm.,vol. 45, December 1997. pp:1613-1621.
[24] Andreas Czylwink. Synchronization for Systems with Antenna Diversity. Vehicular Technology Conference, 1999. IEEE VTS 50th,Volume:2. Sep. 1999. pp: 728– 732.
[25] Won-Gi Jeon, You Y. H., Kim J.T. Timing synchronization for IEEE 802.15.3 WPAN applications, IEEE Communications Letters,Volume 9,Issue 3. March 2005. pp:255– 257.
[26] Won-Gi Jeon, You Y.-H., Kim J.T., Dong-Sun Kim; Timing synchronization for IEEE 802.15.3 WPAN applications, IEEE Communications Letters, Volume 9, Issue 3. March 2005. pp:255-257.
[27] Lambrette U., Speth M., Meyr H.,OFDM burst frequency synchronization by single carrier training data, IEEE Communications Letters, Volume 1, Issue 2, March 1997. pp:46– 48.
[28] Guangliang REN, Yilin CHANG , Hui ZHANG and Huining ZHANG.Synchronization Method Based on A New Constant Envelop Preamble for OFDM Systems. IEEE Transaction on Broadcasting, Volume51, No.1, March 2005. pp.139-143.
[29]张鑫,李颖,魏急波.基于软件无线电的OFDM传输系统基带电路设计[J].电子产品世界,2003,19期.
[30]杨晓.突发OFDM系统接收机同步算法设计及其FPGA实现.浙江大学,2005.
[31]赵亮.宽带OFDM系统研究及FPGA实现.浙江大学硕士学位论文,2006.
[32]张骋.基于IEEE 802.11n的MIMO-OFDM无线局域网系统的同步算法研究.浙江大学硕士学位论文, 2008.